Analysis of n-alkanes at sub microgram per liter level after direct solid phase microextraction from aqueous samples.

PubMed

Farajzadeh, Mirali; Hatami, Mehdi

2002-11-01

This work describes the application of the previously presented solid phase microextraction (SPME) fiber in direct mode for sampling of C10-C20 n-alkanes from aqueous solution. The fiber has simple composition and is constructed from activated charcoal:PVC suspension in tetrahydrofuran. When the composition of the fiber was optimized that the optimum composition was 90:10 (activated charcoal:PVC) for direct mode, whereas it was 75:25 for sampling from the headspace of aqueous samples. This fiber is completely stable in contact with water. The extraction efficiency is improved in the presence of 0.1 M NaCl. The value is between 17.8-38.5% for the first extraction, which better than the efficiency of similar commercial fibers. After seven extractions, all analytes are removed from the aqueous samples nearly 100%. Single fiber repeatability and fiber-to-fiber reproducibility are good and both are less than 13% for all studied alkanes. Finally, direct mode SPME was used in the determination of n-alkanes in the range of sub microg L(-1) without any additional preconcentration procedure. Gas chromatography along with flame ionization detection were used for separation and detection of the studied analytes.

Aqueous fluid composition in CI chondritic materials: Chemical equilibrium assessments in closed systems

NASA Astrophysics Data System (ADS)

Zolotov, Mikhail Yu.

2012-08-01

Solids of nearly solar composition have interacted with aqueous fluids on carbonaceous asteroids, icy moons, and trans-neptunian objects. These processes altered mineralogy of accreted materials together with compositions of aqueous and gaseous phases. We evaluated chemistry of aqueous solutions coexisted with CI-type chondritic solids through calculations of chemical equilibria in closed water-rock-gas systems at different compositions of initial fluids, water/rock mass ratios (0.1-1000), temperatures (<350 °C), and pressures (<2 kbars). The calculations show that fluid compositions are mainly affected by solubilities of solids, the speciation of chlorine in initial water-rock mixtures, and the occurrence of Na-bearing secondary minerals such as saponite. The major species in modeled alkaline solutions are Na+, Cl-, CO32-,HCO3-, K+, OH-, H2, and CO2. Aqueous species of Mg, Fe, Ca, Mn, Al, Ni, Cr, S, and P are not abundant in these fluids owing to low solubility of corresponding solids. Typical NaCl type alkaline fluids coexist with saponite-bearing mineralogy that usually present in aqueously altered chondrites. A common occurrence of these fluids is consistent with the composition of grains emitted from Enceladus. Na-rich fluids with abundant CO32-,HCO3-, and OH- anions coexist with secondary mineralogy depleted in Na. The Na2CO3 and NaHCO3 type fluids could form via accretion of cometary ices. NaOH type fluids form in reduced environments and may locally occur on parent bodies of CR carbonaceous chondrites. Supposed melting of accreted HCl-bearing ices leads to early acidic fluids enriched in Mg, Fe and other metals, consistent with signs of low-pH alteration in chondrites. Neutralization of these solutions leads to alkaline Na-rich fluids. Sulfate species have negligible concentrations in closed systems, which remain reduced, especially at elevated pressures created by forming H2 gas. Hydrogen, CO2, and H2O dominate in the gaseous phase, though the abundance of methane cannot be fairly estimated.

Effects of solid/liquid phase fractionation on pH and aqueous species molality in subduction zone fluids

NASA Astrophysics Data System (ADS)

Zhong, X.; Galvez, M. E.

2017-12-01

Metamorphic fluids are a crucial ingredient of geodynamic evolution, i.e. heat transfer, rock mechanics and metamorphic/metasomatic reactions. During crustal evolution at elevated P and T, rock forming components can be effectively fractionated from the reactive rock system by at least two processes: 1. extraction from porous rocks by liquid phases such as solute-bearing (e.g. Na+, Mg2+) aqueous fluids or partial melts. 2. isolation from effective bulk rock composition due to slow intragranular diffusion in high-P refractory phases such as garnet. The effect of phase fractionation (garnet, partial melt and aqueous species) on fluid - rock composition and properties remain unclear, mainly due to a high demand in quantitative computations of the thermodynamic interactions between rocks and fluids over a wide P-T range. To investigate this problem, we build our work on an approach initially introduced by Galvez et al., (2015) with new functionalities added in a MATLAB code (Rubisco). The fluxes of fractionated components in fluid, melt and garnet are monitored along a typical prograde P-T path for a model crustal pelite. Some preliminary results suggest a marginal effect of fractionated aqueous species on fluid and rock properties (e.g. pH, composition), but the corresponding fluxes are significant in the context of mantle wedge metasomatism. Our work provides insight into the role of high-P phase fractionation on mass redistribution between the surface and deep Earth in subduction zones. Existing limitations relevant to our liquid/mineral speciation/fractionation model will be discussed as well. ReferencesGalvez, M.E., Manning, C.E., Connolly, J.A.D., Rumble, D., 2015. The solubility of rocks in metamorphic fluids: A model for rock-dominated conditions to upper mantle pressure and temperature. Earth Planet. Sci. Lett. 430, 486-498.

Aqueous Alteration and Hydrogen Generation on Parent Bodies of Unequilibrated Ordinary Chondrites: Thermodynamic Modeling for the Semarkona Composition

NASA Technical Reports Server (NTRS)

Zolotov, M. Y.; Mironenko, M. V.; Shock, E. L.

2005-01-01

Ordinary chondrites are the most abundant class of meteorites that could represent rocky parts of solar system bodies. However, even the most primitive unequilibrated ordinary chondrites (UOC) reveal signs of mild alteration that affected the matrix and peripheral zones of chondrules. Major chemical changes include oxidation of kamacite, alteration of glass, removal of alkalis, Al, and Si from chondrules, and formation of phases enriched in halogens, alkalis, and hydrogen. Secondary mineralogical changes include formation of magnetite, ferrous olivine, fayalite, pentlandite, awaruite, smectites, phosphates, carbonates, and carbides. Aqueous alteration is consistent with the oxygen isotope data for magnetite. The presence of secondary magnetite, Ni-rich metal alloys, and ferrous silicates in UOC implies that H2O was the oxidizing agent. However, oxidation by H2O means that H2 is produced in each oxidative pathway. In turn, production of H2, and its redistribution and possible escape should have affected total pressure, as well as the oxidation state of gas, aqueous and mineral phases in the parent body. Here we use equilibrium thermodynamic modeling to explore water-rock reactions in UOC. The chemical composition of gas, aqueous, and mineral phases is considered.

Laboratory studies of aqueous-phase oxidation of polyols in submicron particles

NASA Astrophysics Data System (ADS)

Daumit, K. E.; Carrasquillo, A. J.; Hunter, J. F.; Kroll, J. H.

2013-12-01

Aqueous-phase oxidation has received recent attention as a potential pathway for the formation of highly oxidized organic aerosol. However most aqueous oxidation studies are performed in bulk solutions rather than aqueous droplets. Here we describe experiments in which aqueous oxidation is carried out within submicron particles, allowing for gas-particle partitioning of reactants, intermediates, and products. Using Fenton chemistry as a source of hydroxyl radicals, and a high-resolution aerosol mass spectrometer (AMS) for online characterization of particle composition, we find that aqueous oxidation can be quite rapid. The formation of high concentrations of oxalic acid is observed in the particle phase with some loss of carbon to the gas phase, indicating the formation of volatile products. We see a rapid degradation of condensed-phase oxidation products upon exposure to ultraviolet lights (centered at 350 nm) suggesting that these products may exist as iron(III)-oxalate complexes. Similar results are also seen when oxidation is carried out in bulk solution (with AMS analysis of the atomized solution); however in some cases the mass loss is less than is observed for submicron particles, likely due to differences in partitioning of early-generation products. Such products can partition out of the aqueous phase at the low liquid water contents in the chamber but remain in solution for further aqueous processing in bulk oxidation experiments. This work suggests that the product distributions from oxidation in aqueous aerosol may be substantially different than those in bulk oxidation, pointing to the need to carry out aqueous oxidation studies under atmospherically relevant partitioning conditions (with liquid water contents mimicking those of cloud droplets or wet aerosol).

One-step triple-phase interfacial synthesis of polyaniline-coated polypyrrole composite and its application as electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Lei, Wen; He, Ping; Zhang, Susu; Dong, Faqin; Ma, Yongjun

2014-11-01

We first present an alternative one-step route for constructing a novel polyaniline (PANI)-coated polypyrrole (PPy) composite in an ingenious triple-phase interface system, where PPy and PANI are prepared in individual non-interference interfaces and, in the middle aqueous phase, smaller PANI particles are uniformly coated on the surface of PPy particles, forming a core-shell structure. The prepared PPy/PANI composite electrode shows a superior capacitance behavior that is more suitable for supercapacitor application.

Aqueous two-phase assisted by ultrasound for the extraction of anthocyanins from Lycium ruthenicum Murr.

PubMed

Qin, Benlin; Liu, Xuecong; Cui, Haiming; Ma, Yue; Wang, Zimin; Han, Jing

2017-10-21

In this study, an efficient ultrasound-assisted aqueous two-phase extraction method was used for the extraction of anthocyanins from Lycium ruthenicum Murr. An ethanol/ammonium sulfate system was chosen for the aqueous two-phase system due to its fine partitioning and recycling behaviors. Single-factor experiments were conducted to determine the optimized composition of the system, and the response surface methodology was used for the further optimization of the ultrasound-assisted aqueous two-phase extraction. The optimal conditions were as follows: a salt concentration of 20%, an ethanol concentration of 25%, an extraction time of 33.7 min, an extraction temperature of 25°C, a liquid/solid ratio of 50:1 w/w, pH value of 3.98, and an ultrasound power of 600 W. Under the above conditions, the yields of anthocyanins reached 4.71 mg/g dry sample. For the further purification, D-101 resin was used, and the purity of anthocyanins reached 25.3%. In conclusion, ultrasound-assisted aqueous two-phase extraction was an efficient, ecofriendly, and economical method, and it may be a promising technique for extracting bioactive components from plants.

Characterization of charged polymer self-assemblies by multidetector thermal field-flow fractionation in aqueous mobile phases.

PubMed

Greyling, Guilaume; Pasch, Harald

2018-01-12

Charged block copolymer self-assemblies, such as charged micelles, have attracted much attention as versatile drug delivery systems due to their readily tunable characteristics such as size and surface charge. However, current column-based analytical techniques are not suitable to fractionate and comprehensively characterize charged micelles in terms of size, molar mass, chemical composition and morphology. Multidetector thermal field-flow fractionation (ThFFF) is shown to be a unique characterization platform that can be used to characterize charged micelles in terms of size, molar mass, chemical composition and morphology in aqueous mobile phases with various ionic strengths and pH. This is demonstrated by the characterization of poly(methacrylic acid)-b-poly(methyl methacrylate) self-assemblies in high pH buffers as well as the characterization of cationic poly(2-vinyl pyridine)-b-polystyrene and poly(4-vinyl pyridine)-b-polystyrene self-assemblies in low pH buffers. Moreover, it is shown that ThFFF is capable of separating charged micelles according to the corona composition. These investigations prove convincingly that ThFFF is broadly applicable to the comprehensive characterization of amphiphilic self-assemblies even when aqueous mobile phases are used. Copyright © 2017 Elsevier B.V. All rights reserved.

Preferential adsorption of fluorescing fulvic and humic acid components on activated carbon using flow field-flow fractionation analysis.

PubMed

Schmit, Kathryn H; Wells, Martha J M

2002-02-01

Activated carbon treatment of drinking water is used to remove natural organic matter (NOM) precursors that lead to the formation of disinfection byproducts. The innate hydrophobic nature and macromolecular size of NOM render it amenable to sorption by activated carbon. Batch equilibrium and minicolumn breakthrough adsorption studies were performed using granular activated carbon to treat NOM-contaminated water. Ultraviolet (UV) absorption spectroscopy and flow field-flow fractionation analysis using tandem diode-array and fluorescence detectors were used to monitor the activated carbon sorption of NOM. Using these techniques, it was possible to study activated carbon adsorption properties of UV absorbing, fluorescing and nonfluorescing, polyelectrolytic macromolecules fractionated from the total macromolecular and nonmacromolecular composition of NOM. Adsorption isotherms were constructed at pH 6 and pH 9. Data were described by the traditional and modified Freundlich models. Activated carbon capacity and adsorbability were compared among fractionated molecular subsets of fulvic and humic acids. Preferential adsorption (or adsorptive fractionation) of polyelectrolytic, fluorescing fulvic and humic macromolecules on activated carbon was observed. The significance of observing preferential adsorption on activated carbon of fluorescing macromolecular components relative to nonfluorescing components is that this phenomenon changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the composition that existed in the aqueous phase prior to adsorption. Likewise, it changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the adsorbed phase. This research increases our understanding of NOM interactions with activated carbon which may lead to improved methods of potable water production.

Aqueous solubility calculation for petroleum mixtures in soil using comprehensive two-dimensional gas chromatography analysis data.

PubMed

Mao, Debin; Lookman, Richard; Van De Weghe, Hendrik; Vanermen, Guido; De Brucker, Nicole; Diels, Ludo

2009-04-03

An assessment of aqueous solubility (leaching potential) of soil contaminations with petroleum hydrocarbons (TPH) is important in the context of the evaluation of (migration) risks and soil/groundwater remediation. Field measurements using monitoring wells often overestimate real TPH concentrations in case of presence of pure oil in the screened interval of the well. This paper presents a method to calculate TPH equilibrium concentrations in groundwater using soil analysis by high-performance liquid chromatography followed by comprehensive two-dimensional gas chromatography (HPLC-GCXGC). The oil in the soil sample is divided into 79 defined hydrocarbon fractions on two GCXGC color plots. To each of these fractions a representative water solubility is assigned. Overall equilibrium water solubility of the non-aqueous phase liquid (NAPL) present in the sample and the water phase's chemical composition (in terms of the 79 fractions defined) are then calculated using Raoult's law. The calculation method was validated using soil spiked with 13 different TPH mixtures and 1 field-contaminated soil. Measured water solubilities using a column recirculation equilibration experiment agreed well to calculated equilibrium concentrations and water phase TPH composition.

Predicting the Fluid-Phase Behavior of Aqueous Solutions of ELP (VPGVG) Sequences Using SAFT-VR.

PubMed

Zhao, Binwu; Lindeboom, Tom; Benner, Steven; Jackson, George; Galindo, Amparo; Hall, Carol K

2017-10-24

The statistical associating fluid theory for potentials of variable range (SAFT-VR) is used to predict the fluid phase behavior of elastin-like polypeptide (ELP) sequences in aqueous solution with special focus on the loci of lower critical solution temperatures (LCSTs). A SAFT-VR model for these solutions is developed following a coarse-graining approach combining information from atomistic simulations and from previous SAFT models for previously reported relevant systems. Constant-pressure temperature-composition phase diagrams are determined for solutions of (VPGVG) n sequences + water with n = 1 to 300. The SAFT-VR equation of state lends itself to the straightforward calculation of phase boundaries so that complete fluid-phase equilibria can be calculated efficiently. A broad range of thermodynamic conditions of temperature and pressure are considered, and regions of vapor-liquid and liquid-liquid coexistence, including LCSTs, are found. The calculated phase boundaries at low concentrations match those measured experimentally. The temperature-composition phase diagrams of the aqueous ELP solutions at low pressure (0.1 MPa) are similar to those of types V and VI phase behavior in the classification of Scott and van Konynenburg. An analysis of the high-pressure phase behavior confirms, however, that a closed-loop liquid-liquid immiscibility region, separate from the gas-liquid envelope, is present for aqueous solutions of (VPGVG) 30 ; such a phase diagram is typical of type VI phase behavior. ELPs with shorter lengths exhibit both liquid-liquid and gas-liquid regions, both of which become less extensive as the chain length of the ELP is decreased. The strength of the hydrogen-bonding interaction is also found to affect the phase diagram of the (VPGVG) 30 system in that the liquid-liquid and gas-liquid regions expand as the hydrogen-bonding strength is decreased and shrink as it is increased. The LCSTs of the mixtures are seen to decrease as the ELP chain length is increased.

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

NASA Astrophysics Data System (ADS)

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.; Berkemeier, Thomas; Shiraiwa, Manabu; Zuend, Andreas; Nin Chan, Man

2017-12-01

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C5H8O4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C5) hydroxyl functionalization product (C5H8O5) and a C4 fragmentation product (C4H6O3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon-carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.

Recovery of sugars from ionic liquid biomass liquor by solvent extraction

DOEpatents

Brennan, Timothy Charles R.; Holmes, Bradley M.; Simmons, Blake A.; Blanch, Harvey W.

2015-10-13

The present invention provides for a composition comprising a solution comprising (a) an ionic liquid (IL) or ionic liquid-aqueous (ILA) phase and (b) an organic phase, wherein the solution comprises a sugar and a boronic acid. The present invention also provides for a method of removing a sugar from a solution, comprising: (a) providing a solution comprising (i) an IL or ILA phase and (ii) an organic phase, wherein the solution comprises an IL, a sugar and a boronic acid; (b) contacting the sugar with the boronic acid to form a sugar-boronic acid complex, (c) separating the organic phase and the aqueous phase, wherein the organic phase contains the sugar-boronic acid complex, and optionally (d) separating the sugar from the organic phase.

Aqueous Alteration of Basalts: Earth, Moon, and Mars

NASA Technical Reports Server (NTRS)

Ming, Douglas W.

2007-01-01

The geologic processes responsible for aqueous alteration of basaltic materials on Mars are modeled beginning with our knowledge of analog processes on Earth, i.e., characterization of elemental and mineralogical compositions of terrestrial environments where the alteration and weathering pathways related to aqueous activity are better understood. A key ingredient to successful modeling of aqueous processes on Mars is identification of phases that have formed by those processes. The purpose of this paper is to describe what is known about the elemental and mineralogical composition of aqueous alteration products of basaltic materials on Mars and their implications for specific aqueous environments based upon our knowledge of terrestrial systems. Although aqueous alteration has not occurred on the Moon, it is crucial to understand the behaviors of basaltic materials exposed to aqueous environments in support of human exploration to the Moon over the next two decades. Several methods or indices have been used to evaluate the extent of basalt alteration/weathering based upon measurements made at Mars by the Mars Exploration Rover (MER) Moessbauer and Alpha Particle X-Ray Spectrometers. The Mineralogical Alteration Index (MAI) is based upon the percentage of total Fe (Fe(sub T)) present as Fe(3+) in alteration products (Morris et al., 2006). A second method is the evaluation of compositional trends to determine the extent to which elements have been removed from the host rock and the likely formation of secondary phases (Nesbitt and Young, 1992; Ming et al., 2007). Most of the basalts that have been altered by aqueous processes at the two MER landing sites in Gusev crater and on Meridiani Planum have not undergone extensive leaching in an open hydrolytic system with the exception of an outcrop in the Columbia Hills. The extent of aqueous alteration however ranges from relatively unaltered to pervasively altered materials. Several experimental studies have focused upon the aqueous alteration of lunar materials and simulants (e.g., Keller and Huang, 1971; Eick et al., 1996). Lunar basalts are void of water and highly reduced, hence, these materials are initially very reactive when exposed to water under oxidizing conditions.

Nanoparticle and Gelation Stabilized Functional Composites of an Ionic Salt in a Hydrophobic Polymer Matrix

PubMed Central

Kanyas, Selin; Aydın, Derya; Kizilel, Riza; Demirel, A. Levent; Kizilel, Seda

2014-01-01

Polymer composites consisted of small hydrophilic pockets homogeneously dispersed in a hydrophobic polymer matrix are important in many applications where controlled release of the functional agent from the hydrophilic phase is needed. As an example, a release of biomolecules or drugs from therapeutic formulations or release of salt in anti-icing application can be mentioned. Here, we report a method for preparation of such a composite material consisted of small KCOOH salt pockets distributed in the styrene-butadiene-styrene (SBS) polymer matrix and demonstrate its effectiveness in anti-icing coatings. The mixtures of the aqueous KCOOH and SBS-cyclohexane solutions were firstly stabilized by adding silica nanoparticles to the emulsions and, even more, by gelation of the aqueous phase by agarose. The emulsions were observed in optical microscope to check its stability in time and characterized by rheological measurements. The dry composite materials were obtained via casting the emulsions onto the glass substrates and evaporations of the organic solvent. Composite polymer films were characterized by water contact angle (WCA) measurements. The release of KCOOH salt into water and the freezing delay experiments of water droplets on dry composite films demonstrated their anti-icing properties. It has been concluded that hydrophobic and thermoplastic SBS polymer allows incorporation of the hydrophilic pockets/phases through our technique that opens the possibility for controlled delivering of anti-icing agents from the composite. PMID:24516593

Aqueous Two Phase System Assisted Self-Assembled PLGA Microparticles

NASA Astrophysics Data System (ADS)

Yeredla, Nitish; Kojima, Taisuke; Yang, Yi; Takayama, Shuichi; Kanapathipillai, Mathumai

2016-06-01

Here, we produce poly(lactide-co-glycolide) (PLGA) based microparticles with varying morphologies, and temperature responsive properties utilizing a Pluronic F127/dextran aqueous two-phase system (ATPS) assisted self-assembly. The PLGA polymer, when emulsified in Pluronic F127/dextran ATPS, forms unique microparticle structures due to ATPS guided-self assembly. Depending on the PLGA concentration, the particles either formed a core-shell or a composite microparticle structure. The microparticles facilitate the simultaneous incorporation of both hydrophobic and hydrophilic molecules, due to their amphiphilic macromolecule composition. Further, due to the lower critical solution temperature (LCST) properties of Pluronic F127, the particles exhibit temperature responsiveness. The ATPS based microparticle formation demonstrated in this study, serves as a novel platform for PLGA/polymer based tunable micro/nano particle and polymersome development. The unique properties may be useful in applications such as theranostics, synthesis of complex structure particles, bioreaction/mineralization at the two-phase interface, and bioseparations.

Three-phase compositional modeling of CO2 injection by higher-order finite element methods with CPA equation of state for aqueous phase

NASA Astrophysics Data System (ADS)

Moortgat, Joachim; Li, Zhidong; Firoozabadi, Abbas

2012-12-01

Most simulators for subsurface flow of water, gas, and oil phases use empirical correlations, such as Henry's law, for the CO2 composition in the aqueous phase, and equations of state (EOS) that do not represent the polar interactions between CO2and water. Widely used simulators are also based on lowest-order finite difference methods and suffer from numerical dispersion and grid sensitivity. They may not capture the viscous and gravitational fingering that can negatively affect hydrocarbon (HC) recovery, or aid carbon sequestration in aquifers. We present a three-phase compositional model based on higher-order finite element methods and incorporate rigorous and efficient three-phase-split computations for either three HC phases or water-oil-gas systems. For HC phases, we use the Peng-Robinson EOS. We allow solubility of CO2in water and adopt a new cubic-plus-association (CPA) EOS, which accounts for cross association between H2O and CO2 molecules, and association between H2O molecules. The CPA-EOS is highly accurate over a broad range of pressures and temperatures. The main novelty of this work is the formulation of a reservoir simulator with new EOS-based unique three-phase-split computations, which satisfy both the equalities of fugacities in all three phases and the global minimum of Gibbs free energy. We provide five examples that demonstrate twice the convergence rate of our method compared with a finite difference approach, and compare with experimental data and other simulators. The examples consider gravitational fingering during CO2sequestration in aquifers, viscous fingering in water-alternating-gas injection, and full compositional modeling of three HC phases.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei Chen; Kan, A.T.; Tomson, M.B.

Both the adsorption and the desorption processes play important roles in the transport and fate of organic contaminants in water-sediments and groundwater systems. The adsorption-desorption processes are shown to be influenced by a number of factors, including sediments organic carbon content, contaminant aqueous solubility, aqueous-phase concentration as well as some natural environmental factors such as pH, pE, ionic strength and temperature. External mechanical forces, such as sediment perturbation, and repeated dredging will also have finite effect on the microscopic interparticle forces that control bonds between large and small grain particles. The objective of this research is to study the influencesmore » of various environmental effects on the equilibrium or non-equilibrium desorption behavior of nonpolar organic pollutants in historically contaminated natural sediments of Lake Charles, LA. Differences of desorption behavior between freshly and historically contaminated sediments will be compared in order to evaluated the desorption mechanism. The influences of particle size, mineral composition, organic matter concentration, and aqueous phase matrix composition on desorption behaviour will also be evaluated.« less

Pulsed corona discharge: the role of ozone and hydroxyl radical in aqueous pollutants oxidation.

PubMed

Preis, S; Panorel, I C; Kornev, I; Hatakka, H; Kallas, J

2013-01-01

Ozone and hydroxyl radical are the most active oxidizing species in water treated with gas-phase pulsed corona discharge (PCD). The ratio of the species dependent on the gas phase composition and treated water contact surface was the objective for the experimental research undertaken for aqueous phenol (fast reaction) and oxalic acid (slow reaction) solutions. The experiments were carried out in the reactor, where aqueous solutions showered between electrodes were treated with 100-ns pulses of 20 kV voltage and 400 A current amplitude. The role of ozone increased with increasing oxygen concentration and the oxidation reaction rate. The PCD treatment showed energy efficiency surpassing that of conventional ozonation.

A novel TFC forward osmosis (FO) membrane supported by polyimide (PI) microporous nanofiber membrane

NASA Astrophysics Data System (ADS)

Chi, Xiang-Yu; Zhang, Ping-Yun; Guo, Xue-Jiao; Xu, Zhen-Liang

2018-01-01

A novel interfacial polymerization (IP) procedure on polyimide (PI) microporous nanofiber membrane support with mean pore size 1.27 μm was reported. Using m-phenylenediamine (MPD) as aqueous phase monomer, trimesoyl chloride (TMC) as organic phase monomer, ethanol as aqueous phase co-solvent, thin-film composite (TFC) forward osmosis (FO) membrane was fabricated by two IP procedures. The first IP procedure with the unconventional order (ie, the membrane was immersed in the TMC organic phase first, then in the co-solvent ethanol-water MPD aqueous phase) was used to diminish the pore size of PI microporous nanofiber membrane support for the formation of the polyamide layer. The secondary IP procedure was employed to form the relatively dense polyamide layer with conventional order (ie, the membrane was immersed in the co-solvent ethanol-water MPD aqueous phase first, then in the TMC organic phase). The experimental results showed that higher ethanol concentration led to the relatively higher pure water permeability in RO process and osmotic water flux in FO process, whereas NaCl rejection in RO process decreased and reverse salt flux increased. The specific salt flux (Js/Jv) of TFC FO PI nanofiber membrane (PIN-2-4) could be as low as 0.095 g/L in FO mode. These results could be attributed to influence of the addition of ethanol into aqueous phase on the surface morphology, hydrophilicity and polyamide layer structure.

Extraction of Biomolecules Using Phosphonium-Based Ionic Liquids + K3PO4 Aqueous Biphasic Systems

PubMed Central

Louros, Cláudia L. S.; Cláudio, Ana Filipa M.; Neves, Catarina M. S. S.; Freire, Mara G.; Marrucho, Isabel M.; Pauly, Jérôme; Coutinho, João A. P.

2010-01-01

Aqueous biphasic systems (ABS) provide an alternative and efficient approach for the extraction, recovery and purification of biomolecules through their partitioning between two liquid aqueous phases. In this work, the ability of hydrophilic phosphonium-based ionic liquids (ILs) to form ABS with aqueous K3PO4 solutions was evaluated for the first time. Ternary phase diagrams, and respective tie-lines and tie-lines length, formed by distinct phosphonium-based ILs, water, and K3PO4 at 298 K, were measured and are reported. The studied phosphonium-based ILs have shown to be more effective in promoting ABS compared to the imidazolium-based counterparts with similar anions. Moreover, the extractive capability of such systems was assessed for distinct biomolecules (including amino acids, food colourants and alkaloids). Densities and viscosities of both aqueous phases, at the mass fraction compositions used for the biomolecules extraction, were also determined. The evaluated IL-based ABS have been shown to be prospective extraction media, particularly for hydrophobic biomolecules, with several advantages over conventional polymer-inorganic salt ABS. PMID:20480041

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

DOEpatents

Smith, Douglas D.; Hiller, John M.

1998-01-01

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration.

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, D.D.; Hiller, J.M.

1998-02-24

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changesmore » in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.« less

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

DOEpatents

Smith, D.D.; Hiller, J.M.

1998-02-24

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.

Reactivity of Iron Bearing Minerals and CO 2 Sequestration: A Multi-­Disciplinary and Experimental Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoonen, Martin A.

2014-12-22

The reactivity of sandstones was studied under conditions relevant to the injection of supercritical carbon dioxide in the context of carbon geosequestration. The emphasis of the study was on the reactivity of iron-­bearing minerals when exposed to supercritical CO 2 (scCO 2) and scCO 2 with commingled aqueous solutions containing H 2S and/or SO 2. Flow through and batch experiments were conducted. Results indicate that sandstones, irrespective of their mineralogy, are not reactive when exposed to pure scCO2 or scCO 2 with commingled aqueous solutions containing H 2S and/or SO 2 under conditions simulating the environment near the injection pointmore » (flow through experiments). However, sandstones are reactive under conditions simulating the edge of the injected CO 2 plume or ahead of the plume (batch experiments). Sandstones containing hematite (red sandstone) are particularly reactive. The composition of the reaction products is strongly dependent on the composition of the aqueous phase. The presence of dissolved sulfide leads to the conversion of hematite into pyrite and siderite. The relative amount of the pyrite and siderite is influenced by the ionic strength of the solution. Little reactivity is observed when sulfite is present in the aqueous phase. Sandstones without hematite (grey sandstones) show little reactivity regardless of the solution composition.« less

Development of cost-effective surfactant flooding technology. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pope, G.A.; Sepehrnoori, K.

1996-11-01

Task 1 of this research was the development of a high-resolution, fully implicit, finite-difference, multiphase, multicomponent, compositional simulator for chemical flooding. The major physical phenomena modeled in this simulator are dispersion, heterogeneous permeability and porosity, adsorption, interfacial tension, relative permeability and capillary desaturation, compositional phase viscosity, compositional phase density and gravity effects, capillary pressure, and aqueous-oleic-microemulsion phase behavior. Polymer and its non-Newtonian rheology properties include shear-thinning viscosity, permeability reduction, inaccessible pore volume, and adsorption. Options of constant or variable space grids and time steps, constant-pressure or constant-rate well conditions, horizontal and vertical wells, and multiple slug injections are also availablemore » in the simulator. The solution scheme used in this simulator is fully implicit. The pressure equation and the mass-conservation equations are solved simultaneously for the aqueous-phase pressure and the total concentrations of each component. A third-order-in-space, second-order-in-time finite-difference method and a new total-variation-diminishing (TVD) third-order flux limiter are used that greatly reduce numerical dispersion effects. Task 2 was the optimization of surfactant flooding. The code UTCHEM was used to simulate surfactant polymer flooding.« less

Melting of metasomatized peridotite at 4-6 GPa and up to 1200 °C: an experimental approach

NASA Astrophysics Data System (ADS)

Kessel, R.; Pettke, T.; Fumagalli, P.

2015-04-01

The phase assemblages and compositions in a K-bearing lherzolite + H2O system are determined between 4 and 6 GPa and 850-1200 °C, and the melting reactions occurring at subarc depth in subduction zones are constrained. Experiments were performed on a rocking multi-anvil apparatus. The experiments had around 16 wt% water content, and hydrous melt or aqueous fluid was segregated and trapped in a diamond aggregate layer. The compositions of the aqueous fluid and hydrous melt phases were measured using the cryogenic LA-ICP-MS technique. The residual lherzolite consists of olivine, orthopyroxene, clinopyroxene, and garnet, while diamond (C) is assumed to be inert. Hydrous and alkali-rich minerals were absent from the run products due to preferred dissolution of K2O (and Na2O) to the aqueous fluid/hydrous melt phases. The role of phlogopite in melting relations is, thus, controlled by the water content in the system: at the water content of around 16 wt% used here, phlogopite is unstable and thus does not participate in melting reactions. The water-saturated solidus, i.e., the first appearance of hydrous melt in the K-lherzolite composition, is located between 900 and 1000 °C at 4 GPa and between 1000 and 1100 °C at 5 and 6 GPa. Compositional jumps between hydrous melt and aqueous fluid at the solidus include a significant increase in the total dissolved solids load. All melts/fluids are peralkaline and calcium-rich. The melting reactions at the solidus are peritectic, as olivine, clinopyroxene, garnet, and H2O are consumed to generate hydrous melt plus orthopyroxene. Our fluid/melt compositional data demonstrate that the water-saturated hybrid peridotite solidus lies above 1000 °C at depths greater than 150 km and that the second critical endpoint is not reached at 6 GPa for a K2O-Na2O-CaO-FeO-MgO-Al2O3-SiO2-H2O-Cr2O3(-TiO2) peridotite composition.

Oligomers Formed Through In-cloud Metylglyoxal Reactions: Chemical Composition, Properties, and Mechanisms Investigated by Ultra-high Resolution FT-ICR Mass Spectrometry

EPA Science Inventory

Secondary organic aerosol (SOA) is a substantial component of total atmospheric organic particulate matter, but little is known about the composition of SOA formed through cloud processing. We conducted aqueous phase photooxidation experiments of methylglyoxal and hydroxyl radica...

Manganese in Endeavour Crater Rim Materials, Mars, and Implications for Habitability

NASA Astrophysics Data System (ADS)

Arvidson, R. E.; Catalano, J. G.; Clark, B. C.; Fischer, W. W.; Grotzinger, J. P.; Gellert, R.; Guinness, E. A.; Herkenhoff, K. E.; Johnson, J. R.; McLennan, S. M.; Ming, D. W.; Morris, R. V.; Squyres, S. W.; Yen, A. S.

2014-12-01

The Opportunity Mars rover wheels overturned two adjacent rocks and exposed underlying fracture-filling deposits while exploring the Murray Ridge rim segment of the Noachian-aged Endeavour Crater. These two small rocks, Pinnacle Island (~4 cm across) and Stuart Island (ranging from ~3 to 8 cm wide and ~10 cm long), were subsequently examined in detail to determine the textures, spectral reflectances (0.4 to 1.0 μm), and compositions of the fracture-filling materials. Relatively bright materials with a composition enriched in Mg, Fe, and S, and spectral features indicative of hydrated sulfates, are overlain with a dark, purple mineral phase or phases with a composition enriched in Mn, Ni, P, and Ca, all relative to underlying bedrock. Reflectance spectra for the dark, purple material are consistent with the presence of one or more Mn-oxide phases. Results indicate two aqueous events, one to deposit the Fe and Mg-rich sulfates, and one to deposit the Mn-rich mineral(s), perhaps with scavenging of Ni from the fluid. Ca and P-rich phases (e.g., Ca-phosphates) co-precipitated with Mn-bearing mineral(s) or were incorporated into one or more of them. Mixing of reducing ground waters with an oxidizing atmosphere or other waters likely produced both the S and Mn-enriched deposits. Oxidation of Mn, in particular, requires a very high potential oxidant relative to what is required for S or Fe oxidation. This suggests oxidation by O2 or species derived from O2. Mn-oxide phases would have provided highly favorable substrates for microbial respiration, making this period of aqueous flow through the fractures a potentially habitable environment. These results add to the evolving story of aqueous alteration of Endeavour's rim rocks, including evidence for nontronite, montmorillonite, Ca-sulfate-rich veins, and hematitic concretions.

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C 5Hmore » 8O 4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C 5) hydroxyl functionalization product (C 5H 8O 5) and a C 4 fragmentation product (C 4H 6O 3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.« less

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

DOE PAGES

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.; ...

2017-12-05

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C 5Hmore » 8O 4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C 5) hydroxyl functionalization product (C 5H 8O 5) and a C 4 fragmentation product (C 4H 6O 3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.« less

End-Member Formulation of Solid Solutions and Reactive Transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lichtner, Peter C.

2015-09-01

A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed tomore » correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.« less

Aqueous phase oligomerization of methyl vinyl ketone through photooxidation - Part 1: Aging processes of oligomers

NASA Astrophysics Data System (ADS)

Renard, P.; Siekmann, F.; Salque, G.; Smaani, A.; Demelas, C.; Coulomb, B.; Vassalo, L.; Ravier, S.; Temime-Roussel, B.; Voisin, D.; Monod, A.

2014-06-01

Secondary organic aerosol (SOA) represents a substantial part of organic aerosol, which affects climate and human health. It is now accepted that one of the important pathways of SOA formation occurs via aqueous phase chemistry in the atmosphere. Recently, we have shown in a previous study (Renard et al., 2013) the mechanism of oligomerization of MVK (methyl vinyl ketone), and suggested that unsaturated water soluble organic compounds (UWSOC) might efficiently form SOA in wet aerosol particles, even for weakly soluble ones like MVK. The atmospheric relevance of these processes is explored by means of process model studies (in a companion paper). In the present study we investigate the aging of these aqueous phase MVK-oligomers (Part 1). We compared aqueous phase composition and SOA composition after nebulization, mainly by means of UPLC-ESI-MS and AMS, respectively. Both instruments match and show similar trend of oligomer formation and aging. The SMPS analysis performed on the nebulized solutions allow to quantify these SOA and to measure their mass yields. We have highlighted in the current study that MVK •OH-oxidation undergoes kinetic competition between functionalization and oligomerization. The SOA composition and its evolution highly depend on the precursor initial concentration. We determined the threshold of MVK concentration, i.e. 2 mM, from which oligomerization prevails over functionalization. Hence, at these concentrations, •OH-oxidation of MVK forms oligomers that are SV-OOA, with low O / C and high f43. Oligomers are then fragmented, via unidentified intermediates that have the properties of LV-OOA which then end into succinic, malonic and oxalic diacids. For lower initial MVK concentrations, the oligomerization is not the major process, and functionalization dominates, resulting in small carbonyls, dicarbonyls and mainly monoacids. The aging of these oligomers could be an explanation for the presence of a part of the diacids observed in aerosol.

Extraction processes and solvents for recovery of cesium, strontium, rare earth elements, technetium and actinides from liquid radioactive waste

DOEpatents

Zaitsev, Boris N.; Esimantovskiy, Vyacheslav M.; Lazarev, Leonard N.; Dzekun, Evgeniy G.; Romanovskiy, Valeriy N.; Todd, Terry A.; Brewer, Ken N.; Herbst, Ronald S.; Law, Jack D.

2001-01-01

Cesium and strontium are extracted from aqueous acidic radioactive waste containing rare earth elements, technetium and actinides, by contacting the waste with a composition of a complex organoboron compound and polyethylene glycol in an organofluorine diluent mixture. In a preferred embodiment the complex organoboron compound is chlorinated cobalt dicarbollide, the polyethylene glycol has the formula RC.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.n OH, and the organofluorine diluent is a mixture of bis-tetrafluoropropyl ether of diethylene glycol with at least one of bis-tetrafluoropropyl ether of ethylene glycol and bis-tetrafluoropropyl formal. The rare earths, technetium and the actinides (especially uranium, plutonium and americium), are extracted from the aqueous phase using a phosphine oxide in a hydrocarbon diluent, and reextracted from the resulting organic phase into an aqueous phase by using a suitable strip reagent.

Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions.

PubMed

Samanta, Archana; Takkar, Sonam; Kulshreshtha, Ritu; Nandan, Bhanu; Srivastava, Rajiv K

2016-12-01

The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. Copyright © 2016 Elsevier B.V. All rights reserved.

Extractant composition including crown ether and calixarene extractants

DOEpatents

Meikrantz, David H.; Todd, Terry A.; Riddle, Catherine L.; Law, Jack D.; Peterman, Dean R.; Mincher, Bruce J.; McGrath, Christopher A.; Baker, John D.

2009-04-28

An extractant composition comprising a mixed extractant solvent consisting of calix[4] arene-bis-(tert-octylbenzo)-crown-6 ("BOBCalixC6"), 4',4',(5')-di-(t-butyldicyclo-hexano)-18-crown-6 ("DtBu18C6"), and at least one modifier dissolved in a diluent. The DtBu18C6 may be present at from approximately 0.01M to approximately 0.4M, such as at from approximately 0.086 M to approximately 0.108 M. The modifier may be 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol ("Cs-7SB") and may be present at from approximately 0.01M to approximately 0.8M. In one embodiment, the mixed extractant solvent includes approximately 0.15M DtBu18C6, approximately 0.007M BOBCalixC6, and approximately 0.75M Cs-7SB modifier dissolved in an isoparaffinic hydrocarbon diluent. The extractant composition further comprises an aqueous phase. The mixed extractant solvent may be used to remove cesium and strontium from the aqueous phase.

Using design of experiments to optimize derivatization with methyl chloroformate for quantitative analysis of the aqueous phase from hydrothermal liquefaction of biomass.

PubMed

Madsen, René Bjerregaard; Jensen, Mads Mørk; Mørup, Anders Juul; Houlberg, Kasper; Christensen, Per Sigaard; Klemmer, Maika; Becker, Jacob; Iversen, Bo Brummerstedt; Glasius, Marianne

2016-03-01

Hydrothermal liquefaction is a promising technique for the production of bio-oil. The process produces an oil phase, a gas phase, a solid residue, and an aqueous phase. Gas chromatography coupled with mass spectrometry is used to analyze the complex aqueous phase. Especially small organic acids and nitrogen-containing compounds are of interest. The efficient derivatization reagent methyl chloroformate was used to make analysis of the complex aqueous phase from hydrothermal liquefaction of dried distillers grains with solubles possible. A circumscribed central composite design was used to optimize the responses of both derivatized and nonderivatized analytes, which included small organic acids, pyrazines, phenol, and cyclic ketones. Response surface methodology was used to visualize significant factors and identify optimized derivatization conditions (volumes of methyl chloroformate, NaOH solution, methanol, and pyridine). Twenty-nine analytes of small organic acids, pyrazines, phenol, and cyclic ketones were quantified. An additional three analytes were pseudoquantified with use of standards with similar mass spectra. Calibration curves with high correlation coefficients were obtained, in most cases R (2)  > 0.991. Method validation was evaluated with repeatability, and spike recoveries of all 29 analytes were obtained. The 32 analytes were quantified in samples from the commissioning of a continuous flow reactor and in samples from recirculation experiments involving the aqueous phase. The results indicated when the steady-state condition of the flow reactor was obtained and the effects of recirculation. The validated method will be especially useful for investigations of the effect of small organic acids on the hydrothermal liquefaction process.

Corrosion behavior of a superduplex stainless steel in chloride aqueous solution

NASA Astrophysics Data System (ADS)

Dabalà, Manuele; Calliari, Irene; Variola, Alessandra

2004-04-01

Super duplex stainless steels (SDSS) have been widely used as structural materials for chemical plants (especially in those engaged in phosphoric acid production), in the hydrometallurgy industries, and as materials for offshore applications due to their excellent corrosion resistance in chloride environments, compared with other commercial types of ferritic stainless steels. These alloys also possess superior weldability and better mechanical properties than austenitic stainless steels. However, due to their two-phase structure, the nature of which is very dependent on their composition and thermal history, the behavior of SDSS regarding localized corrosion appears difficult to predict, especially in chloride environments. To improve their final properties, the effect of the partition of the alloying elements between the two phases, and the composition and microstructure of each phase are the key to understanding the localized corrosion phenomena of SDSS. This paper concerns the effects of the SDSS microstructure and heat treatment on the SDSS corrosion resistance in aqueous solutions, containing different amounts of NaCl at room temperature.

Preparation, characterization, and thermal properties of starch microencapsulated fatty acids as phase change materials thermal energy storage applications

USDA-ARS?s Scientific Manuscript database

Stable starch-oil composites can be prepared from renewable resources by excess steam jet-cooking aqueous slurries of starch and vegetable oils or other hydrophobic materials. Fatty acids such as stearic acid are promising phase change materials (PCMs) for latent heat thermal energy storage applica...

Thermodynamics of manganese oxides: Sodium, potassium, and calcium birnessite and cryptomelane

PubMed Central

Birkner, Nancy; Navrotsky, Alexandra

2017-01-01

Manganese oxides with layer and tunnel structures occur widely in nature and inspire technological applications. Having variable compositions, these structures often are found as small particles (nanophases). This study explores, using experimental thermochemistry, the role of composition, oxidation state, structure, and surface energy in the their thermodynamic stability. The measured surface energies of cryptomelane, sodium birnessite, potassium birnessite and calcium birnessite are all significantly lower than those of binary manganese oxides (Mn3O4, Mn2O3, and MnO2), consistent with added stabilization of the layer and tunnel structures at the nanoscale. Surface energies generally decrease with decreasing average manganese oxidation state. A stabilizing enthalpy contribution arises from increasing counter-cation content. The formation of cryptomelane from birnessite in contact with aqueous solution is favored by the removal of ions from the layered phase. At large surface area, surface-energy differences make cryptomelane formation thermodynamically less favorable than birnessite formation. In contrast, at small to moderate surface areas, bulk thermodynamics and the energetics of the aqueous phase drive cryptomelane formation from birnessite, perhaps aided by oxidation-state differences. Transformation among birnessite phases of increasing surface area favors compositions with lower surface energy. These quantitative thermodynamic findings explain and support qualitative observations of phase-transformation patterns gathered from natural and synthetic manganese oxides. PMID:28130549

Microfluidic control of droplet formation from stable emulsions formed by aqueous two-phase systems

NASA Astrophysics Data System (ADS)

Teixeira, Alyne G.; Tsai, Meng-Chiao; Frampton, John P.

2018-02-01

Aqueous two-phase systems (ATPSs) form from the thermodynamic separation of two dissolved incompatible solutes, such as two polymers, a polymer and a salt, and a polymer and a surfactant. At most supercritical concentrations, ATPS emulsions can be formed by vigorous mixing. These emulsions typically settle into distinct layers in minutes to hours. However, it is also possible to choose ATPS compositions with extremely long settling times that resemble stable emulsions. Here, we generated stable emulsions from a polyethylene glycol (PEG)-dextran ATPS by selecting ATPS compositions at the extreme ends of the tie lines connecting the binodal curve delineating phase-separating compositions. Droplets of PEG in a continuous dextran phase did not coalesce appreciably over the course of several days when stored in a conical tube or syringe. However, upon exposure to laminar flow conditions in a microfluidic channel, droplets were observed to coalesce. Through microscopic characterization of droplet volume, an increase in droplet size and decrease in overall droplet number was observed as a function of channel distance, suggesting a progressive droplet merging phenomenon. This novel approach to control droplet size by encouraging coalescence of stable emulsions under laminar flow in a microfluidic channel enables the production of droplets ranging from fL to several pL, which may enable various future biotechnology applications.

Aqueous dispersion polymerization: a new paradigm for in situ block copolymer self-assembly in concentrated solution.

PubMed

Sugihara, Shinji; Blanazs, Adam; Armes, Steven P; Ryan, Anthony J; Lewis, Andrew L

2011-10-05

Reversible addition-fragmentation chain transfer polymerization has been utilized to polymerize 2-hydroxypropyl methacrylate (HPMA) using a water-soluble macromolecular chain transfer agent based on poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC). A detailed phase diagram has been elucidated for this aqueous dispersion polymerization formulation that reliably predicts the precise block compositions associated with well-defined particle morphologies (i.e., pure phases). Unlike the ad hoc approaches described in the literature, this strategy enables the facile, efficient, and reproducible preparation of diblock copolymer spheres, worms, or vesicles directly in concentrated aqueous solution. Chain extension of the highly hydrated zwitterionic PMPC block with HPMA in water at 70 °C produces a hydrophobic poly(2-hydroxypropyl methacrylate) (PHPMA) block, which drives in situ self-assembly to form well-defined diblock copolymer spheres, worms, or vesicles. The final particle morphology obtained at full monomer conversion is dictated by (i) the target degree of polymerization of the PHPMA block and (ii) the total solids concentration at which the HPMA polymerization is conducted. Moreover, if the targeted diblock copolymer composition corresponds to vesicle phase space at full monomer conversion, the in situ particle morphology evolves from spheres to worms to vesicles during the in situ polymerization of HPMA. In the case of PMPC(25)-PHPMA(400) particles, this systematic approach allows the direct, reproducible, and highly efficient preparation of either block copolymer vesicles at up to 25% solids or well-defined worms at 16-25% solids in aqueous solution.

Preparation and characterization of polyaniline-copper composites by electrical explosion of wire.

PubMed

Liu, Aijie; Bac, Luong Huu; Kim, Jin-Chun; Liu, Lizhu

2012-07-01

Polyaniline-copper composites with a polyacrylic acid (PAA) were synthesized by electrical explosion of wire. Polyaniline (PANI) and PAA were put into the explosion medium, deionized water (DIW) and ethanol, stirred for 24 hrs and sonicated for 2 hrs. These solutions were used as base liquids for explosion process to fabricate Cu nanoparticle. Optical absorption in the UV-visible region of PANI and PANI/PAA-Cu composites was measured in a range of 200-900 nm. X-ray diffraction was used to analyze the phase of the composites. XRD pattern showed the PANI was amorphous and copper was polycrystalline. Two phases of Cu and Cu2O were formed in aqueous solution while single Cu phase was obtained in ethanol solution. Field emission scanning electron microscope was used to observe the microstructure of the composites. The synthesized composites were extensively characterized by Fourier Transform Infrared (FTIR) spectroscopy and electrical measurements.

Fluid Inclusion Study of Quartz Xenocrysts in Mafic Dykes from Kawant Area, Chhota Udaipur District, Gujarat, India

NASA Astrophysics Data System (ADS)

Randive, Kirtikumar; Hurai, Vratislav

2015-09-01

Unusual mafic dykes occur in the proximity of the Ambadongar Carbonatite Complex, Lower Narmada Valley, Gujarat, India. The dykes contain dense population of quartz xenocrysts within the basaltic matrix metasomatised by carbonate-rich fluids. Plagioclase feldspars, relict pyroxenes, chlorite, barite, rutile, magnetite, Fe-Ti oxides and glass were identified in the basaltic matrix. Quartz xenocrysts occur in various shapes and sizes and form an intricate growth pattern with carbonates. The xenocrysts are fractured and contain several types of primary and secondary, single phase and two-phase fluid inclusions. The two-phase inclusions are dominated by aqueous liquid, whereas the monophase inclusions are composed of carbonic gas and the aqueous inclusions homogenize to liquid between 226°C and 361°C. Majority of the inclusions are secondary in origin and are therefore unrelated to the crystallization of quartz. Moreover, the inclusions have mixed carbonic-aqueous compositions that inhibit their direct correlation with the crustal or mantle fluids. The composition of dilute CO2-rich fluids observed in the quartz xenocrysts appear similar to those exsolved during the final stages of evolution of the Amba Dongar carbonatites. However, the carbonates are devoid of fluid inclusions and therefore their genetic relation with the quartz xenocrysts cannot be established.

Evaluation of amorphous magnesium phosphate (AMP) based non-exothermic orthopedic cements.

PubMed

Babaie, Elham; Lin, Boren; Goel, Vijay K; Bhaduri, Sarit B

2016-10-07

This paper reports for the first time the development of a biodegradable, non-exothermic, self-setting orthopedic cement composition based on amorphous magnesium phosphate (AMP). The occurrence of undesirable exothermic reactions was avoided through using AMP as the solid precursor. The phenomenon of self-setting with optimum rheology is achieved by incorporating a water soluble biocompatible/biodegradable polymer, polyvinyl alcohol (PVA). Additionally, PVA enables a controlled growth of the final phase via a biomimetic process. The AMP powder was synthesized using a precipitation method. The powder, when in contact with the aqueous PVA solution, forms a putty resulting in a nanocrystalline magnesium phosphate phase of cattiite. The as-prepared cement compositions were evaluated for setting times, exothermicity, compressive strength, biodegradation, and microstructural features before and after soaking in SBF, and in vitro cytocompatibility. Since cattiite is relatively unexplored in the literature, a first time evaluation reveals that it is cytocompatible, just like the other phases in the MgO-P 2 O 5 (Mg-P) system. The cement composition prepared with 15% PVA in an aqueous medium achieved clinically relevant setting times, mechanical properties, and biodegradation. Simulated body fluid (SBF) soaking resulted in coating of bobierrite onto the cement particle surfaces.

Formation, Phase, and Elemental Composition of Micro- and Nano-Dimensional Particles of the Fe-Ti System

NASA Astrophysics Data System (ADS)

Dresvyannikov, A. F.; Kolpakov, M. E.

2018-05-01

X-ray fluorescence, X-ray phase analysis, and transmission Mössbauer and NGR spectrometry are used to study the formation, phase, and elemental composition of Fe-Ti particles. The interaction between Fe(III) ions and dispersed titanium in an aqueous solution containing chloride ions and HF is studied. It is shown that the resulting Fe-Ti samples are a set of core-shell microparticles with titanium cores coated with micro- and nanosized α-Fe nucleation centers with the thinness outer layer of iron(III) oxide characterized by a developed surface.

A Novel Aqueous Two Phase System Composed of Surfactant and Xylitol for the Purification of Lipase from Pumpkin (Cucurbita moschata) Seeds and Recycling of Phase Components.

PubMed

Amid, Mehrnoush; Manap, Mohd Yazid; Hussin, Muhaini; Mustafa, Shuhaimi

2015-06-17

Lipase is one of the more important enzymes used in various industries such as the food, detergent, pharmaceutical, textile, and pulp and paper sectors. A novel aqueous two-phase system composed of surfactant and xylitol was employed for the first time to purify lipase from Cucurbita moschata. The influence of different parameters such as type and concentration of surfactants, and the composition of the surfactant/xylitol mixtures on the partitioning behavior and recovery of lipase was investigated. Moreover, the effect of system pH and crude load on the degree of purification and yield of the purified lipase were studied. The results indicated that the lipase was partitioned into the top surfactant rich phase while the impurities partitioned into the bottom xylitol-rich phase using an aqueous two phase system composed of 24% (w/w) Triton X-100 and 20% (w/w) xylitol, at 56.2% of tie line length (TLL), (TTL is one of the important parameters in this study and it is determined from a bimodal curve in which the tie-line connects two nodes on the bimodal, that represent concentration of phase components in the top and bottom phases) and a crude load of 25% (w/w) at pH 8.0. Recovery and recycling of components was also measured in each successive step process. The enzyme was successfully recovered by the proposed method with a high purification factor of 16.4 and yield of 97.4% while over 97% of the phase components were also recovered and recycled. This study demonstrated that the proposed novel aqueous two phase system method is more efficient and economical than the traditional aqueous two phase system method for the purification and recovery of the valuable enzyme lipase.

Control and measurement of the phase behavior of aqueous solutions using microfluidics

PubMed Central

Shim, Jung-uk; Cristobal, Galder; Link, Darren R.; Thorsen, Todd; Jia, Yanwei; Piattelli, Katie; Fraden, Seth

2008-01-01

A microfluidic device denoted the Phase Chip has been designed to measure and manipulate the phase diagram of multi-component fluid mixtures. The Phase Chip exploits the permeation of water through poly(dimethylsiloxane) (PDMS) in order to controllably vary the concentration of solutes in aqueous nanoliter volume microdrops stored in wells. The permeation of water in the Phase Chip is modeled using the diffusion equation and good agreement between experiment and theory is obtained. The Phase Chip operates by first creating drops of the water/solute mixture whose composition varies sequentially. Next, drops are transported down channels and guided into storage wells using surface tension forces. Finally, the solute concentration of each stored drop is simultaneously varied and measured. Two applications of the Phase Chip are presented. First, the phase diagram of a polymer/salt mixture is measured on-chip and validated off-chip and second, protein crystallization rates are enhanced through the manipulation of the kinetics of nucleation and growth. PMID:17580868

EXTRACTION METHOD FOR SEPARATING URANIUM, PLUTONIUM, AND FISSION PRODUCTS FROM COMPOSITIONS CONTAINING SAME

DOEpatents

Seaborg, G.T.

1957-10-29

Methods for separating plutonium from the fission products present in masses of neutron irradiated uranium are reported. The neutron irradiated uranium is first dissolved in an aqueous solution of nitric acid. The plutonium in this solution is present as plutonous nitrate. The aqueous solution is then agitated with an organic solvent, which is not miscible with water, such as diethyl ether. The ether extracts 90% of the uraryl nitrate leaving, substantially all of the plutonium in the aqueous phase. The aqueous solution of plutonous nitrate is then oxidized to the hexavalent state, and agitated with diethyl ether again. In the ether phase there is then obtained 90% of plutonium as a solution of plutonyl nitrate. The ether solution of plutonyl nitrate is then agitated with water containing a reducing agent such as sulfur dioxide, and the plutonium dissolves in the water and is reduced to the plutonous state. The uranyl nitrate remains in the ether. The plutonous nitrate in the water may be recovered by precipitation.

Iron oxide functionalized graphene nano-composite for dispersive solid phase extraction of chemical warfare agents from aqueous samples.

PubMed

Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Goud, D Raghavender; Dubey, D K; Pardasani, Deepak

2015-05-15

Present study deals with the preparation and evaluation of graphene based magnetic nano-composite for dispersive solid phase extraction of Chemical Weapons Convention (CWC) relevant chemicals from aqueous samples. Nano-composite, Fe3O4@SiO2-G was synthesized by covalently bonding silica coated Fe3O4 onto the graphene sheets. Nerve agents (NA), Sulfur mustard (SM) and their non-toxic environmental markers were the target analytes. Extraction parameters like amount of sorbent, extraction time and desorption conditions were optimized. Dispersion of 20 milligram of sorbent in 200mL of water sample for 20min. followed by methanol/chloroform extraction produced average to good recoveries (27-94%) of targeted analytes. Recoveries of real agents exhibited great dependency upon sample pH and ionic strength. Sarin produced maximum recovery under mild acidic conditions (56% at pH 5) while VX demanded alkaline media (83% at pH 9). Salts presence in the aqueous samples was found to be advantageous, raising the recoveries to as high as 94% for SM. Excellent limits of detection (LOD) for sulphur mustard and VX (0.11ngmL(-1) and 0.19ngmL(-1) respectively) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. Copyright © 2015 Elsevier B.V. All rights reserved.

Double emulsions for the compatibilization of hydrophilic nanocellulose with non-polar polymers and validation in the synthesis of composite fibers.

PubMed

Carrillo, Carlos A; Nypelö, Tiina; Rojas, Orlando J

2016-03-14

A route for the compatibilization of aqueous dispersions of cellulose nanofibrils (CNFs) with a non-polar polymer matrix is proposed to overcome a major challenge in CNF-based material synthesis. Non-ionic surfactants were used in CNF aqueous dispersions equilibrated with an organic phase (for demonstration, a polystyrene solution, PS, was used). Stable water-in-oil-in-water (W/O/W) double emulsions were produced as a result of the compromise between composition and formulation variables. Most remarkably, the proposed route for CNF integration with hydrophobic polymers removed the need for drying or solvent-exchange of the CNF aqueous dispersion prior to processing. The rheological behavior of the double emulsions showed strong shear thinning behavior and facilitated CNF-PS co-mixing in solid nanofibers upon electrospinning. The morphology and thermal properties of the resultant nanofibers revealed that CNFs were efficiently integrated in the hydrophobic matrix which was consistent with the high interfacial area of the precursor double emulsion. In addition, the morphology and quality of the composite nanofibers can be controlled by the conductivity (ionic strength) of the CNF dispersion. Overall, double emulsion systems are proposed as a novel, efficient and scalable platform for CNF co-processing with non-polar systems and they open up the possibility for the redispersion of CNFs after removal of the organic phase.

Nanoemulsion-based delivery systems for polyunsaturated (ω-3) oils: formation using a spontaneous emulsification method.

PubMed

Gulotta, Alessandro; Saberi, Amir Hossein; Nicoli, Maria Cristina; McClements, David Julian

2014-02-19

Nanoemulsion-based delivery systems are finding increasing utilization to encapsulate lipophilic bioactive components in food, personal care, cosmetic, and pharmaceutical applications. In this study, a spontaneous emulsification method was used to fabricate nanoemulsions from polyunsaturated (ω-3) oils, that is, fish oil. This low-energy method relies on formation of fine oil droplets when an oil/surfactant mixture is added to an aqueous solution. The influence of surfactant-to-oil ratio (SOR), oil composition (lemon oil and MCT), and cosolvent composition (glycerol, ethanol, propylene glycol, and water) on the formation and stability of the systems was determined. Optically transparent nanoemulsions could be formed by controlling SOR, oil composition, and aqueous phase composition. The spontaneous emulsification method therefore has considerable potential for fabricating nanoemulsion-based delivery systems for incorporating polyunsatured oils into clear food, personal care, and pharmaceutical products.

Fundamental and applied aspects of the chemistry of radioactive iodine in gas and aqueous media

NASA Astrophysics Data System (ADS)

Kulyukhin, Sergei A.

2012-10-01

The results of investigations carried out in the past 15-20 years in the chemistry of radioactive iodine in the gas phase and in aqueous media of various compositions are described systematically and analyzed. The prospects for practical application of the obtained data in various fields of nuclear power industry including accidents at nuclear power plants and enterprises engaged in spent nuclear fuel reprocessing are estimated. The bibliography includes 206 references.

Direct purification of pectinase from mango (Mangifera Indica Cv. Chokanan) peel using a PEG/salt-based Aqueous Two Phase System.

PubMed

Mehrnoush, Amid; Sarker, Md Zaidul Islam; Mustafa, Shuhaimi; Yazid, Abdul Manap Mohd

2011-10-10

An Aqueous Two-Phase System (ATPS) was employed for the first time for the separation and purification of pectinase from mango (Mangifera Indica Cv. Chokanan) peel. The effects of different parameters such as molecular weight of the polymer (polyethylene glycol, 2,000-10,000), potassium phosphate composition (12-20%, w/w), system pH (6-9), and addition of different concentrations of neutral salts (0-8%, w/w) on partition behavior of pectinase were investigated. The partition coefficient of the enzyme was decreased by increasing the PEG molecular weight. Additionally, the phase composition showed a significant effect on purification factor and yield of the enzyme. Optimum conditions for purification of pectinase from mango peel were achieved in a 14% PEG 4000-14% potassium phosphate system using 3% (w/w) NaCl addition at pH 7.0. Based on this system, the purification factor of pectinase was increased to 13.2 with a high yield of (97.6%). Thus, this study proves that ATPS can be an inexpensive and effective method for partitioning of pectinase from mango peel.

The influence of drop size-dependent fog chemistry on aerosol processing by San Joaquin Valley fogs

NASA Astrophysics Data System (ADS)

Hoag, Katherine J.; Collett, Jeffrey L., Jr.; Pandis, Spyros N.

Drop size-resolved measurements of fog chemistry in California's San Joaquin Valley during the 1995 Integrated Monitoring Study reveal that fog composition varies with drop size. Small fog drops were less alkaline and typically contained higher major ion (nitrate, sulfate, ammonium) concentrations than large drops. Small drops often contained higher concentrations of Fe and Mn than large drops while H 2O 2 concentrations exhibited no strong drop size dependence. Simulation of an extended fog episode in Fresno, California revealed the capability of a drop size-resolved fog chemistry model to reproduce the measured (based on two drop size categories) drop size dependence of several key species. The model was also able to satisfactorily reproduce measured species-dependent deposition rates (ammonium>sulfate>nitrate) resulting from fog drop sedimentation. Both the model simulation and direct analysis of size-resolved fog composition observations and measured gas-phase oxidant concentrations indicate the importance of ozone as an aqueous-phase S(IV) oxidant in these high pH fogs. Due to the nonlinear dependence of the rate law for the ozone pathway on the hydrogen ion concentration, use of the average fog drop composition can lead to significant underprediction of aqueous phase sulfate production rates in these chemically heterogeneous fogs.

Concurrence of aqueous and gas phase contamination of groundwater in the Wattenberg oil and gas field of northern Colorado.

PubMed

Li, Huishu; Son, Ji-Hee; Carlson, Kenneth H

2016-01-01

The potential impact of rapid development of unconventional oil and natural gas resources using hydraulic fracturing and horizontal drilling on regional groundwater quality has received significant attention. Major concerns are methane or oil/gas related hydrocarbon (such as TPHs, BTEX including benzene, toluene, ethybenzene and xylene) leaks into the aquifer due to the failure of casing and/or stray gas migration. Previously, we investigated the relationship between oil and gas activity and dissolved methane concentration in a drinking water aquifer with the major finding being the presence of thermogenic methane contamination, but did not find detectable concentrations of TPHs or BTEX. To understand if aqueous and gas phases from the producing formation were transported concurrently to drinking water aquifers without the presence of oil/gas related hydrocarbons, the ionic composition of three water groups was studied: (1) uncontaminated deep confined aquifer, (2) suspected contaminated groundwater - deep confined aquifer containing thermogenic methane, and (3) produced water from nearby oil and gas wells that would represent aqueous phase contaminants. On the basis of quantitative and spatial analysis, we identified that the "thermogenic methane contaminated" groundwater did not have similarities to produced water in terms of ionic character (e.g. Cl/TDS ratio), but rather to the "uncontaminated" groundwater. The analysis indicates that aquifer wells with demonstrated gas phase contamination have not been contacted by an aqueous phase from oil and gas operations according to the methodology we use in this study and the current groundwater quality data from COGCC. However, the research does not prove conclusively that this the case. The results may provide insight on contamination mechanisms since improperly sealed well casing may result in stray gas but not aqueous phase transport. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molecular Modeling of Thermodynamic and Transport Properties for CO 2 and Aqueous Brines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Hao; Economou, Ioannis G.; Panagiotopoulos, Athanassios Z.

Molecular simulation techniques using classical force-fields occupy the space between ab initio quantum mechanical methods and phenomenological correlations. In particular, Monte Carlo and molecular dynamics algorithms can be used to provide quantitative predictions of thermodynamic and transport properties of fluids relevant for geologic carbon sequestration at conditions for which experimental data are uncertain or not available. These methods can cover time and length scales far exceeding those of quantum chemical methods, while maintaining transferability and predictive power lacking from phenomenological correlations. The accuracy of predictions depends sensitively on the quality of the molecular models used. Many existing fixed-point-charge models formore » water and aqueous mixtures fail to represent accurately these fluid properties, especially when descriptions covering broad ranges of thermodynamic conditions are needed. Recent work on development of accurate models for water, CO 2, and dissolved salts, as well as their mixtures, is summarized in this Account. Polarizable models that can respond to the different dielectric environments in aqueous versus nonaqueous phases are necessary for predictions of properties over extended ranges of temperatures and pressures. Phase compositions and densities, activity coefficients of the dissolved salts, interfacial tensions, viscosities and diffusivities can be obtained in near-quantitative agreement to available experimental data, using relatively modest computational resources. In some cases, for example, for the composition of the CO 2-rich phase in coexistence with an aqueous phase, recent results from molecular simulations have helped discriminate among conflicting experimental data sets. The sensitivity of properties on the quality of the intermolecular interaction model varies significantly. Properties such as the phase compositions or electrolyte activity coefficients are much more sensitive than phase densities, viscosities, or component diffusivities. Strong confinement effects on physical properties in nanoscale media can also be directly obtained from molecular simulations. Future work on molecular modeling for CO 2 and aqueous brines is likely to be focused on more systematic generation of interaction models by utilizing quantum chemical as well as direct experimental measurements. New ion models need to be developed for use with the current generation of polarizable water models, including ion–ion interactions that will allow for accurate description of dense, mixed brines. Methods will need to be devised that go beyond the use of effective potentials for incorporation of quantum effects known to be important for water, and reactive force fields developed that can handle bond creation and breaking in systems with carbonate and silicate minerals. Lastly, another area of potential future work is the integration of molecular simulation methods in multiscale models for the chemical reactions leading to mineral dissolution and flow within the porous media in underground formations.« less

Molecular Modeling of Thermodynamic and Transport Properties for CO2 and Aqueous Brines.

PubMed

Jiang, Hao; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

2017-04-18

Molecular simulation techniques using classical force-fields occupy the space between ab initio quantum mechanical methods and phenomenological correlations. In particular, Monte Carlo and molecular dynamics algorithms can be used to provide quantitative predictions of thermodynamic and transport properties of fluids relevant for geologic carbon sequestration at conditions for which experimental data are uncertain or not available. These methods can cover time and length scales far exceeding those of quantum chemical methods, while maintaining transferability and predictive power lacking from phenomenological correlations. The accuracy of predictions depends sensitively on the quality of the molecular models used. Many existing fixed-point-charge models for water and aqueous mixtures fail to represent accurately these fluid properties, especially when descriptions covering broad ranges of thermodynamic conditions are needed. Recent work on development of accurate models for water, CO 2 , and dissolved salts, as well as their mixtures, is summarized in this Account. Polarizable models that can respond to the different dielectric environments in aqueous versus nonaqueous phases are necessary for predictions of properties over extended ranges of temperatures and pressures. Phase compositions and densities, activity coefficients of the dissolved salts, interfacial tensions, viscosities and diffusivities can be obtained in near-quantitative agreement to available experimental data, using relatively modest computational resources. In some cases, for example, for the composition of the CO 2 -rich phase in coexistence with an aqueous phase, recent results from molecular simulations have helped discriminate among conflicting experimental data sets. The sensitivity of properties on the quality of the intermolecular interaction model varies significantly. Properties such as the phase compositions or electrolyte activity coefficients are much more sensitive than phase densities, viscosities, or component diffusivities. Strong confinement effects on physical properties in nanoscale media can also be directly obtained from molecular simulations. Future work on molecular modeling for CO 2 and aqueous brines is likely to be focused on more systematic generation of interaction models by utilizing quantum chemical as well as direct experimental measurements. New ion models need to be developed for use with the current generation of polarizable water models, including ion-ion interactions that will allow for accurate description of dense, mixed brines. Methods will need to be devised that go beyond the use of effective potentials for incorporation of quantum effects known to be important for water, and reactive force fields developed that can handle bond creation and breaking in systems with carbonate and silicate minerals. Another area of potential future work is the integration of molecular simulation methods in multiscale models for the chemical reactions leading to mineral dissolution and flow within the porous media in underground formations.

Molecular Modeling of Thermodynamic and Transport Properties for CO 2 and Aqueous Brines

DOE PAGES

Jiang, Hao; Economou, Ioannis G.; Panagiotopoulos, Athanassios Z.

2017-02-24

Molecular simulation techniques using classical force-fields occupy the space between ab initio quantum mechanical methods and phenomenological correlations. In particular, Monte Carlo and molecular dynamics algorithms can be used to provide quantitative predictions of thermodynamic and transport properties of fluids relevant for geologic carbon sequestration at conditions for which experimental data are uncertain or not available. These methods can cover time and length scales far exceeding those of quantum chemical methods, while maintaining transferability and predictive power lacking from phenomenological correlations. The accuracy of predictions depends sensitively on the quality of the molecular models used. Many existing fixed-point-charge models formore » water and aqueous mixtures fail to represent accurately these fluid properties, especially when descriptions covering broad ranges of thermodynamic conditions are needed. Recent work on development of accurate models for water, CO 2, and dissolved salts, as well as their mixtures, is summarized in this Account. Polarizable models that can respond to the different dielectric environments in aqueous versus nonaqueous phases are necessary for predictions of properties over extended ranges of temperatures and pressures. Phase compositions and densities, activity coefficients of the dissolved salts, interfacial tensions, viscosities and diffusivities can be obtained in near-quantitative agreement to available experimental data, using relatively modest computational resources. In some cases, for example, for the composition of the CO 2-rich phase in coexistence with an aqueous phase, recent results from molecular simulations have helped discriminate among conflicting experimental data sets. The sensitivity of properties on the quality of the intermolecular interaction model varies significantly. Properties such as the phase compositions or electrolyte activity coefficients are much more sensitive than phase densities, viscosities, or component diffusivities. Strong confinement effects on physical properties in nanoscale media can also be directly obtained from molecular simulations. Future work on molecular modeling for CO 2 and aqueous brines is likely to be focused on more systematic generation of interaction models by utilizing quantum chemical as well as direct experimental measurements. New ion models need to be developed for use with the current generation of polarizable water models, including ion–ion interactions that will allow for accurate description of dense, mixed brines. Methods will need to be devised that go beyond the use of effective potentials for incorporation of quantum effects known to be important for water, and reactive force fields developed that can handle bond creation and breaking in systems with carbonate and silicate minerals. Lastly, another area of potential future work is the integration of molecular simulation methods in multiscale models for the chemical reactions leading to mineral dissolution and flow within the porous media in underground formations.« less

Aqueous cholesteric liquid crystals using uncharged rodlike polypeptides. Polypeptide vesicles by conformation-specific assembly. Ordered chiral macroporous hybrid silica-polypeptide composites

NASA Astrophysics Data System (ADS)

Bellomo, Enrico Giuseppe

2005-07-01

Aqueous cholesteric liquid crystals using uncharged rodlike polypeptides . The aqueous, lyotropic liquid-crystalline phase behavior of an alpha helical polypeptide, has been studied using optical microscopy and X-ray scattering. Solutions of optically pure polypeptide were found to form cholesteric liquid crystals at volume fractions that decreased with increasing average chain length. At very high volume fractions, the formation of a hexagonal mesophase was observed. The pitch of the cholesteric phase could be varied by a mixture of enantiomeric samples, where the pitch increased as the mixture approached equimolar. The cholesteric phases could be untwisted, using either magnetic field or shear flow, into nematic phases, which relaxed into cholesterics upon removal of field or shear. We have found that the phase diagram of this polypeptide in aqueous solution parallels that of poly(gamma-benzyl glutamate) in organic solvents, thus providing a useful system for liquid-crystal applications requiring water as solvent. Polypeptide vesicles by conformation-specific assembly. We have found that block copolymers composed of polypeptide segments provide significant advantages in controlling both the function and supramolecular structure of bioinspired self-assemblies. Incorporation of the stable chain conformations found in proteins into block copolymers was found to provide an additional element of control, beyond amphiphilicity and composition that defines self-assembled architecture. The abundance of functionality present in amino acids, and the ease by which they can be incorporated into these materials, also provides a powerful mechanism to impart block copolypeptides with function. This combination of structure and function work synergistically to enable significant advantages in the preparation of therapeutic agents as well as provide insight into design of self-assemblies beginning to approach the complexity of natural structures such as virus capsids. Ordered chiral macroporous hybrid silica-polypeptide composites. The mineralization of organic templates has been investigated as an effective way to control the size and structure of inorganic frameworks. Hybrid structures incorporating polypeptide with silica have been prepared and characterized using X-ray scattering, TGA, SEM and TEM. The results support the interaction between silica and polymer to form ordered chiral macroporous structures that can be easily controlled by polymer molecular weight and volume fraction.

Aqueous alteration and brecciation in Bells, an unusual, saponite-bearing, CM chondrite

NASA Astrophysics Data System (ADS)

Brearley, Adrian J.

1995-06-01

The petrological and mineralogical characteristics of the unusual CM2 chondrite, Bells, have been investigated in detail by scanning electron microscopy (SEM), electron microprobe analysis (EPMA), and transmission electron microscopy (TEM). Bells is a highly brecciated chondrite which contains few intact chondrules, a very low abundance of refractory inclusions, and is notable in having an unusually high abundance of magnetite, which is disseminated throughout the fine-grained matrix. Fragmental olivines and pyroxenes are common and, based on compositional data, appear to have been derived from chondrules as a result of extensive brecciation. The fine-grained mineralogy of matrix in Bells differs considerably from other CM chondrites and has closer affinities to matrix in CI chondrites. The dominant phases are fine-grained saponite interlayered with serpentine, and phases such as tochilinite and cronstedtite, which are typical of CM chondrite matrices, are entirely absent. Pentlandite, pyrrhotite, magnetite, anhydrite, calcite, and rare Ti-oxides also occur as accessory phases. Based on its oxygen and noble gas isotopic compositions (Zadnik, 1985; Rowe et al., 1994), Bells can be considered to be a CM2 chondrite, although its bulk composition shows some departures from the typical range exhibited by this group. However, these variations in bulk chemistry are entirely consistent with the observed mineralogy of Bells. The unusual fine-grained mineralogy of Bells matrix can be reasonably attributed to the combined effects of aqueous alteration and advanced brecciation in a parent body environment. Extensive brecciation has assisted aqueous alteration by reducing chondrules and mineral grains into progressively smaller grains with high surface areas, which are more susceptible to dissolution reactions involving aqueous fluids. This has resulted in the preferential dissolution of Fe-rich chondrule olivines, which are now completely absent in Bells although present in other CM chondrites. The formation of saponite in Bells probably resulted from the dissolution of relatively silica-rich phases, such as pyroxene and olivine, that were derived from chondrules. The result of such dissolution reactions would be to increase the activity of silica in the fluid phase, at least on a localized scale, stabilizing saponite in preference to serpentine. An increase in aSiO 2 would also have destabilized preexisting cronstedtite which may have reacted to form magnetite and MgFe serpentine under conditions of constant ƒO 2 .

Analysis of Direct Samples of Extraterrestrial, Organic-Bearing, Aqueous Fluids

NASA Technical Reports Server (NTRS)

Zolensky, Michael

2016-01-01

I will describe water we have found in 4.5 billion year old extraterrestrial salt, and the organics that are also present. We hypothesize that organics being carried through the parent body of the halite have been deposited adjacent to the fluid inclusions, where they have been preserved against any thermal metamorphism. We are making bulk compositional, carbon and hydrogen isotopic measurements of solid organic phases associated with the aqueous fluid inclusions in the meteorites. We will compare these organics with those found in chondrites and Wild-2 comet coma particles to determine whether these classes of organics had an origin within aqueous solutions.

Chemical characterization of some aqueous leachates from crop residues in 'CELSS'

NASA Technical Reports Server (NTRS)

Madsen, Brooks C.

1992-01-01

Aqueous leachate samples prepared from crop residues that are produced as a component of the Controlled Ecological Life Support System program designed to support long duration space missions have been compared and general chemical characterization has been accomplished. Solid phase extraction and high performance liquid chromatography were used to accomplish comparisons based on chromatographic and ultraviolet absorption properties of the components that are present. Specific compounds were not identified, however, general composition related to the presence of phenol-like compounds was explored.

Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene.

PubMed

Tsai, Hung-Sheng; Tsai, Teh-Hua

2012-01-04

The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied. By graphical and numerical analysis, the compositions of indium-D2EHPA complexes in organic phase and stoichiometry of the extraction reaction were examined. Nitric acid solutions with various indium concentrations at 25 °C were used to obtain the equilibrium constant of InR₃ in the organic phase. The experimental results showed that the extraction distribution ratios of indium(III) between the organic phase and the aqueous solution increased when either the pH value of the aqueous solution and/or the concentration of the organic phase extractant increased. Finally, the recovery efficiency of indium(III) in nitric acid was measured.

[DNA complexes, formed on aqueous phase surfaces: new planar polymeric and composite nanostructures].

PubMed

Antipina, M N; Gaĭnutdinov, R V; Rakhnianskaia, A A; Sergeev-Cherenkov, A N; Tolstikhina, A L; Iurova, T V; Kislov, V V; Khomutov, G B

2003-01-01

The formation of DNA complexes with Langmuir monolayers of the cationic lipid octadecylamine (ODA) and the new amphiphilic polycation poly-4-vinylpyridine with 16% of cetylpyridinium groups (PVP-16) on the surface of an aqueous solution of native DNA of low ionic strength was studied. Topographic images of Langmuir-Blodgett films of DNA/ODA and DNA/PVP-16 complexes applied to micaceous substrates were investigated by the method of atomic force microscopy. It was found that films of the amphiphilic polycation have an ordered planar polycrystalline structure. The morphology of planar DNA complexes with the amphiphilic cation substantially depended on the incubation time and the phase state of the monolayer on the surface of the aqueous DNA solution. Complex structures and individual DNA molecules were observed on the surface of the amphiphilic monolayer. Along with quasi-linear individual bound DNA molecules, characteristic extended net-like structures and quasi-circular toroidal condensed conformations of planar DNA complexes were detected. Mono- and multilayer films of DNA/PVP-16 complexes were used as templates and nanoreactors for the synthesis of inorganic nanostructures via the binding of metal cations from the solution and subsequent generation of the inorganic phase. As a result, ultrathin polymeric composite films with integrated DNA building blocks and quasi-linear arrays of inorganic semiconductor (CdS) and iron oxide nanoparticles and nanowires were obtained. The nanostructures obtained were characterized by scanning probe microscopy and transmission electron microscopy techniques. The methods developed are promising for investigating the mechanisms of structural organization and transformation in DNA and polyelectrolyte complexes at the gas-liquid interface and for the design of new extremely thin highly ordered planar polymeric and composite materials, films, and coatings with controlled ultrastructure for applications in nanoelectronics and nanobiotechnology.

Effect of hydrothermal liquefaction aqueous phase recycling on bio-crude yields and composition.

PubMed

Biller, Patrick; Madsen, René B; Klemmer, Maika; Becker, Jacob; Iversen, Bo B; Glasius, Marianne

2016-11-01

Hydrothermal liquefaction (HTL) is a promising thermo-chemical processing technology for the production of biofuels but produces large amounts of process water. Therefore recirculation of process water from HTL of dried distillers grains with solubles (DDGS) is investigated. Two sets of recirculation on a continuous reactor system using K2CO3 as catalyst were carried out. Following this, the process water was recirculated in batch experiments for a total of 10 rounds. To assess the effect of alkali catalyst, non-catalytic HTL process water recycling was performed with 9 recycle rounds. Both sets of experiments showed a large increase in bio-crude yields from approximately 35 to 55wt%. The water phase and bio-crude samples from all experiments were analysed via quantitative gas chromatography-mass spectrometry (GC-MS) to investigate their composition and build-up of organic compounds. Overall the results show an increase in HTL conversion efficiency and a lower volume, more concentrated aqueous by-product following recycling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantifying Mass Transfer Processes in Groundwater as a Function of Molecular Structure Variation for Multicomponent NAPL Sources

NASA Astrophysics Data System (ADS)

Abbott, J. B., III; Tick, G. R.; Greenberg, R. R.; Carroll, K. C.

2017-12-01

The remediation of nonaqueous liquid (NAPL) contamination sources in groundwater has been shown to be challenging and have limited success in the field. The presence of multicomponent NAPL sources further complicates the remediation due to variability of mass-transfer (dissolution) behavior as a result of compositional and molecular structure variations between the different compounds within the NAPL phase. This study investigates the effects of the contaminant of concern (COC) composition and the bulk-NAPL components molecular structure (i.e. carbon chain length, aliphatic and aromatic) on dissolution and aqueous phase concentrations in groundwater. The specific COCs tested include trichloroethene (TCE), toluene (TOL), and perfluorooctanoic acid (PFOA). Each COC was tested in a series of binary batch experiments using insoluble bulk NAPL including n-hexane (HEX), n-decane (DEC), and n-hexadecane (HEXDEC). These equilibrium batch tests were performed to understand how different carbon-chain-length (NAPL) systems affect resulting COC aqueous phase concentrations. The experiments were conducted with four different COC mole fractions mixed within the bulk-NAPL derivatives (0.1:0.9, 0.05:0.95, 0.01:0.99, 0.001:0.999). Raoult's Law was used to assess the relative ideality of the mass transfer processes for each binary equilibrium dissolution experiment. Preliminary results indicate that as mole fraction of the COC decreases (composition effects), greater deviance from dissolution ideality occurs. It was also shown that greater variation in molecular structure (i.e. greater carbon chain length of bulk-NAPL with COC and aromatic COC presence) exhibited greater dissolution nonideality via Raoult's Law analysis. For instance, TOL (aromatic structure) showed greater nonideality than TCE (aliphatic structure) in the presence of the different bulk-NAPL derivatives (i.e. of various aliphatic carbon chains lengths). The results suggest that the prediction of aqueous phase concentration, from complex multicomponent NAPL sources, is highly dependent upon both composition and molecular structure variations of COC-NAPL mixtures, and such impacts should be taken into account when designing and evaluating a remediation strategy and/or predicting COC concentrations from a source zone region.

Ground-water contamination by organic bases derived from coal-tar wastes

USGS Publications Warehouse

Pereira, Wilfred E.; Rostad, Colleen E.; Garbarino, John R.; Hult, Marc F.

1983-01-01

A fluid sample from a shallow aquifer contaminated by coal-tar wastes was analyzed for organic bases. The sample consisted of a mixture of aqueous and oily-tar phases. The phases were separated by centrifugation and filtration. Organic bases were isolated from each phase by pH adjustment and solvent extraction. Organic bases in the oily-tar phase were further purified by neutral-alumina, micro-column adsorption chromatography. Separation and identification of the organic bases in each phase were achieved by using capillary gas chromatography-mass spectrometry-computer (GC-MS-COM) and probe distillation-high resolution mass spectrometry (PD-HRMS) techniques. Organic bases present in the aqueous phase included primary aromatic amines (such as aniline, alkylated anilines, and naphthylamines) as well as azaarenes (such as alkylated pyridines, quinolines, acridine, and benzoquinolines). The oily-tar phase contained acridine, benzacridines, dibenzacridines, and numerous other azaarenes, the elemental compositions of which were determined by PD-HRMS. Azaarenes in the oily-tar phase, varying in size from 6 to 12 rings, are reported for the first time. The origin and environmental significance of these compounds are discussed.

Groundwater contamination by organic bases derived from coal-tar wastes

USGS Publications Warehouse

Pereira, W.E.; Rostad, C.E.; Garbarino, J.R.; Hult, M.F.

1983-01-01

A fluid sample from a shallow aquifer contaminated by coal-tar wastes was analyzed for organic bases. The sample consisted of a mixture of aqueous and oily-tar phases. The phases were separated by centrifugation and filtration. Organic bases were isolated from each phase by pH adjustment and solvent extraction. Organic bases in the oily-tar phase were further purified by neutral-alumina, micro-column adsorption chromatography. Separation and identification of the organic bases in each phase were achieved by using capillary gas chromatography-mass spectrometry-computer (GC-MS-COM) and probe distillation-high resolution mass spectrometry (PD-HRMS) techniques. Organic bases present in the aqueous phase included primary aromatic amines (such as aniline, alkylated anilines, and naphthylamines) as well as azaarenes (such as alkylated pyridines, quinolines, acridine, and benzoquinolines). The oily-tar phase contained acridine, benzacridines, dibenzacridines, and numerous other azaarenes, the elemental compositions of which were determined by PD-HRMS. Azaarenes in the oily-tar phase, varying in size from 6 to 12 rings, are reported for the first time. The origin and environmental significance of these compounds are discussed. ?? 1983.

Influence of aqueous chemistry on the chemical composition of fog water and interstitial aerosol in Fresno

NASA Astrophysics Data System (ADS)

Kim, Hwajin; Ge, Xinlei; Collier, Sonya; Xu, Jianzhong; Sun, Yele; Wang, Youliang; Herckes, Pierre; Zhang, Qi

2015-04-01

A measurement study was conducted in the Central Valley (Fresno) of California in January 2010, during which radiation fog events were frequently observed. Fog plays important roles in atmospheric chemistry by scavenging aerosol particles and trace gases and serving as a medium for various aqueous-phase reactions. Understanding the effects of fog on the microphysical and chemical processing of aerosol particles requires detailed information on their chemical composition. In this study, we characterized the chemical composition of fog water and interstitial aerosol particles to study the effects of fog processing on aerosol properties. Fog water samples were collected during the 2010 Fresno campaigns with a Caltech Active Strand Cloud water Collector (CASCC) while interstitial submicron aerosols were characterized in real time with an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a scanning Mobility Particle Sizer (SMPS). The fog water samples were later analyzed using the HR-ToF-AMS, ion chromatography, and a total carbon analyzer. The chemical composition and characteristics of interstitial particles during the fog events were compared to those of dissolved inorganic and organic matter in fog waters. Compared to interstitial aerosols, fog water is composed of a higher fraction of ammonium nitrate and oxygenated organics, due to aqueous formation of secondary aerosol species as well as enhanced gas-to-particle partitioning of water soluble species under water rich conditions. Sulfate is formed most efficiently in fog water although its contribution to total dissolved mass is relatively low. The HR-ToF-AMS mass spectra of organic matter in fog water (FOM) are very similar to that of oxygenated organic aerosols (OOA) derived from positive matrix factorization (PMF) of the HR-ToF-AMS spectra of ambient aerosol (r2 = 0.96), but FOM appears to contain a large fraction of acidic functional groups than OOA. FOM is also enriched of organic nitrogen compounds, with an average N/C ratio ~3.8 times that of OOA. Most strikingly is the enhancement of the CxHyN2+ family ions in FOM spectra, indicating the presence of imidazole compounds, which commonly result from the aqueous phase reactions of tropospheric aldehyde such as glyoxal, formaldehyde or acetaldehyde with amino compounds. The results of this study demonstrate that aqueous phase reactions in fog water lead to the formation of some oxidized and nitrogen-containing compounds. Details and the environmental implications of results will be discussed.

Differential partition of virulent Aeromonas salmonicida and attenuated derivatives possessing specific cell surface alterations in polymer aqueous-phase systems

NASA Technical Reports Server (NTRS)

Van Alstine, J. M.; Trust, T. J.; Brooks, D. E.

1986-01-01

Two-polymer aqueous-phase systems in which partitioning of biological matter between the phases occurs according to surface properties such as hydrophobicity, charge, and lipid composition are used to compare the surface properties of strains of the fish pathogen Aeromonas salmonicida. The differential ability of strains to produce a surface protein array crucial to their virulence, the A layer, and to produce smooth lipopolysaccharide is found to be important in the partitioning behavior of Aeromonas salmonicida. The presence of the A layer is shown to decrease the surface hydrophilicity of the pathogen, and to increase specifically its surface affinity for fatty acid esters of polyethylene glycol. The method has application to the analysis of surface properties crucial to bacterial virulence, and to the selection of strains and mutants with specific surface characteristics.

User`s guide for UTCHEM implicit (1.0) a three dimensional chemical flood simulator. Final report, September 30, 1992--December 31, 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-07-01

UTCHEM IMPLICIT is a three-dimensional chemical flooding simulator. The solution scheme is fully implicit. The pressure equation and the mass conservation equations are solved simultaneously for the aqueous phase pressure and the total concentrations of each component. A third-order-in-space, second-order-in-time finite-difference method and a new total-variation-diminishing (TVD) third-order flux limiter are used to reduce numerical dispersion effects. Saturations and phase concentrations are solved in a flash routine. The major physical phenomena modeled in the simulator are: dispersion, adsorption, aqueous-oleic-microemulsion phase behavior, interfacial tension, relative permeability, capillary trapping, compositional phase viscosity, capillary pressure, phase density, polymer properties: shear thinning viscosity, inaccessiblemore » pore volume, permeability reduction, and adsorption. The following options are available in the simulator: constant or variable time-step sizes, uniform or nonuniform grid, pressure or rate constrained wells, horizontal and vertical wells.« less

Interfacially polymerized layers for oxygen enrichment: a method to overcome Robeson's upper-bound limit.

PubMed

Tsai, Ching-Wei; Tsai, Chieh; Ruaan, Ruoh-Chyu; Hu, Chien-Chieh; Lee, Kueir-Rarn

2013-06-26

Interfacial polymerization of four aqueous phase monomers, diethylenetriamine (DETA), m-phenylenediamine (mPD), melamine (Mela), and piperazine (PIP), and two organic phase monomers, trimethyl chloride (TMC) and cyanuric chloride (CC), produce a thin-film composite membrane of polymerized polyamide layer capable of O2/N2 separation. To achieve maximum efficiency in gas permeance and O2/N2 permselectivity, the concentrations of monomers, time of interfacial polymerization, number of reactive groups in monomers, and the structure of monomers need to be optimized. By controlling the aqueous/organic monomer ratio between 1.9 and 2.7, we were able to obtain a uniformly interfacial polymerized layer. To achieve a highly cross-linked layer, three reactive groups in both the aqueous and organic phase monomers are required; however, if the monomers were arranged in a planar structure, the likelihood of structural defects also increased. On the contrary, linear polymers are less likely to result in structural defects, and can also produce polymer layers with moderate O2/N2 selectivity. To minimize structural defects while maximizing O2/N2 selectivity, the planar monomer, TMC, containing 3 reactive groups, was reacted with the semirigid monomer, PIP, containing 2 reactive groups to produce a membrane with an adequate gas permeance of 7.72 × 10(-6) cm(3) (STP) s(-1) cm(-2) cm Hg(-1) and a high O2/N2 selectivity of 10.43, allowing us to exceed the upper-bound limit of conventional thin-film composite membranes.

Computing gas solubility in reservoir waters for environmental chemistry applications: the role of satellite observations

NASA Astrophysics Data System (ADS)

Rosa, R.; Lima, I.; Ramos, F.; Bambace, L.; Assireu, A.; Stech, J.; Novo, E.; Lorenzeti, L.

Atmospheric greenhouse gases concentration has increased during the past centuries basically due to biogenic and pyrogenic anthopogenic emissions Recent investigations have shown that gas emission methane as an important example from tropical hydroelectric reservoirs may comprise a considerable fraction of the total anthropogenic bulk In order to evaluate the concentration of gases of potential importance in environmental chemistry the solubility of such gases have been collected and converted into a uniform format using the Henry s law which states that the solubility of a gas in a liquid is directly proportional to its partial pressure However the Henry s law can be derived as a function of temperature density molar mixing ratio in the aqueous phase and molar mass of water In this paper we show that due to the complex temperature variation and water composition measured in brazilian tropical reservoirs as Serra da Mesa and Manso expressive secular variation on the traditional solubility constants concentration of a species in the aqueous phase by the partial pressure of that species in the gas phase can change in a rate of approximately 30 in 6 decades This estimation comes from a computational analysis of temperature variation measured during 6 months in Serra da Mesa and Manso reservoirs taking into account a simulated density and molar mass variation of the aqueous composition in these environments As an important global change issue from this preliminary analysis we discuss its role in the current estimations on the concentration emission rates

[Partitioning of taxifolin-iron ions complexes in octanol-water system].

PubMed

Shatalin, Iu V; Shubina, V S

2014-01-01

The composition of taxifolin-iron ions complexes in an octanol-water biphasic system was studied using the method of absorption spectrophotometry. It was found that at pH 5.0 in an aqueous biphasic system the complex of [Tf2 x Fe x (OH)k(H2O)8-k] is present, but at pH 7.0 and 9.0 the complexes of [Tf2 x Fe x (OH)k(H2O)2-k] and [Tf x Fe x OH)k(H2O)4-k] are predominantly observed. The formation of a stable [Tf3 x Fe] complex occurred in octanol phase. The charged iron ion of this complex is surrounded by taxifolin molecules, which shield the iron ion from lipophilic solvent. During transition from water to octanol phase the changes of the composition of complexes are accompanied by reciprocal changes in portion of taxifolin and iron ions in these phases. It was shown that the portion of taxifolin in aqueous solution in the presence of iron ions is increased at high pH values, and the portion of iron ions is minimal at pH 7.0. In addition, the parameters of solubility limits of taxifolin-iron ions complexes in an aqueous solution were determined. The data obtained gain a better understanding of the role of complexation of polyphenol with metal of variable valency in passive transport of flavonoids and metal ions across lipid membranes.

Hydrophilic organic/salt-containing aqueous two-phase solvent system for counter-current chromatography: a novel technique for separation of polar compounds.

PubMed

Liu, Dan; Zou, Xiaowei; Gao, Mingzhe; Gu, Ming; Xiao, Hongbin

2014-08-22

Hydrophilic organic/salt-containing aqueous two-phase system composing of ethanol, water and ammonium sulfate for separation polar compounds was investigated on multilayer coil associated with J-type HSCCC devices. Compared to the classical polar solvent system based on 1-butanol-water or PEG1000-ammonium sulfate-water, the water content of upper phase in ethanol-ammonium sulfate-water systems was from 53.7% to 32.8% (wt%), closed to PEG1000-ammonium sulfate-water aqueous two-phase systems and higher than 1-butanol-water (22.0%, wt%). Therefore, the polarity of ethanol-ammonium sulfate-water is in the middle of 1-butanol-water and PEG-ammonium sulfate-water system, which is quite good for separating polar compounds like phenols, nucleosides and amino acids with low partition coefficient in 1-octanol-water system. The retention of stationary phase in four elution mode on type-J counter-current chromatography devices with multilayer coil column changed from 26% to 71%. Hydrodynamic trend possess both intermediate and hydrophilic solvent system property, which closely related to the composition of solvent system. The applicability of this system was demonstrated by successful separation of adenosine, uridine guanosine and cytidine. Copyright © 2014 Elsevier B.V. All rights reserved.

Cell separation in immunoaffinity partition in aqueous polymer two-phase systems

NASA Technical Reports Server (NTRS)

Karr, Laurel J.; Van Alstine, James M.; Snyder, Robert S.; Shafer, Steven G.; Harris, J. Milton

1989-01-01

Two methods for immunoaffinity partitioning are described. One technique involves the covalent coupling of poly (ethylene glycol) (PEG) to immunoglobulin G antibody preparations. In the second method PEG-modified Protein A is used to complex with cells and unmodified antibody. The effects of PEG molecular weight, the degree of modification, and varying phase system composition on antibody activity and its affinity for the upper phase are studied. It is observed that both methods resulted in effective cell separation.

Enhanced adsorbability and photocatalytic activity of TiO2-graphene composite for polycyclic aromatic hydrocarbons removal in aqueous phase.

PubMed

Bai, Hongzhen; Zhou, Jun; Zhang, Hongjian; Tang, Guping

2017-02-01

Photodegradation via titanium dioxide (TiO 2 ) has been used to remove polycyclic aromatic hydrocarbons (PAHs) from environmental media broadly. In this study, a series of TiO 2 -graphene composites (P25-GR) with different GR weight ratios were synthesized via hydrothermal reaction of graphene oxide (GO) and P25. Their structures were characterized and the proprieties were tested in aqueous phase. Phenanthrene (PHE), fluoranthene (FLAN), and benzo[a]pyrene (BaP) were selected as models of PAHs. The experiment indicated that P25-2.5%GR exhibited enhancement in both adsorption and photodegradation, ∼80% of PAHs were removed after 2h photocatalysis. The influence of photodegradation rate was studied, including PAHs initial concentration and pH. Aromatic intermediates were identified during the reaction process and the degradation pathways were portrayed. This work explored the enhanced photocatalysis performance was attributed to the PAH-selective adsorbability and the strong electron transfer ability of the composite. The analysis of the degradation intermediates confirmed that the reaction proceeded with the formation of free radicals, leading to the gradual PAH mineralization. Copyright © 2016 Elsevier B.V. All rights reserved.

A Systematic Evaluation of the Extent of Photochemical Processing in Different Types of Secondary Organic Aerosols in the Aqueous Phase

NASA Astrophysics Data System (ADS)

Romonosky, D.; Lee, H.; Epstein, S. A.; Nizkorodov, S.; Laskin, J.; Laskin, A.

2013-12-01

A significant fraction of atmospheric organic compounds are predominantly found in condensed phases, such as organic phase in aerosol particles or aqueous phase in cloud droplets. The oxidation of VOCs followed by the condensation of products into particles was thought to be the main mechanism of organic aerosol (OA) formation. However, in the last several years, scientists have realized that a large fraction, if not the majority of organic particles, is produced through cloud and fog photochemical processes. Many of these organic compounds are photolabile, and can degrade through direct photolysis or indirect photooxidation processes on time scales that are comparable to the typical lifetimes of droplets (hours) and particles (days). We previously reported that compounds in secondary organic aerosol (SOA) from ozonolysis of d-limonene efficiently photodegrade in both organic (Walser et al., 2007) and aqueous phases (Bateman et al., 2011). Significant photolysis was also observed in an aqueous extract of SOA from high-NOx photooxidation of isoprene (Nguyen et al., 2012). More recent experiments studying the response to irradiation of complex aqueous mixtures (as opposed to solutions of isolated compounds) found surprising resilience to photodegradation in aqueous extracts of SOA prepared by photooxidation of alpha-pinene (Romonosky et al., unpublished). We present a systematic investigation of the extent of photochemical processing in different types of SOA from various biogenic and anthropogenic precursors. Chamber- or flowtube-generated SOA is collected on an inert substrate, extracted in a methanol/water solution (70:30), photolyzed in the aqueous solution, and the extent of change in the molecular level composition of the material is assessed with high-resolution mass spectrometry (HR-MS). The outcome of this study will be improved understanding of the role of condensed-phase photochemistry in chemical aging of aerosol particles and cloud droplets. Bateman et al. Photolytic processing of secondary organic aerosols dissolved in cloud droplets. Phys. Chem. Chem. Phys. 2011, 13, 12199. Nguyen et al. Direct aqueous photochemistry of isoprene high-NOx secondary organic aerosol. Phys. Chem. Chem. Phys. 2012, 14, 9702. Walser et al. Photochemical aging of secondary organic aerosol particles generated from the oxidation of d-limonene. J. Phys. Chem. A 2007, 111, 1907.

Preparation and physicochemical characteristics of polylactide microspheres of emamectin benzoate by modified solvent evaporation/extraction method.

PubMed

Zhang, Shao Fei; Chen, Peng Hao; Zhang, Fei; Yang, Yan Fang; Liu, De Kun; Wu, Gang

2013-12-18

Emamectin benzoate is highly effective against insect pests and widely used in the world. However, its biological activity is limited because of high resistance of target insects and rapid degradation speed in fields. Preparation and physicochemical characterization of degradable microcapsules of emamectin benzoate were studied by modified solvent evaporation/extraction method using polylactide (PLA) as wall material. The influence of different compositions of the solvent in internal organic phase and external aqueous phase on diameter, span, pesticide loading, and entrapment rate of the microspheres was investigated. The results indicated that the process of solvent extraction and the formation of the microcapsules would be accelerated by adding water-miscible organic solvents such as ethyl ether, acetone, ethyl acetate, or n-butanol into internal organic phase and external aqueous phase. Accelerated formation of the microcapsules would result in entrapment rates of emamectin benzoate increased to as high as 97%. In addition, by adding ethanol into the external aqueous phase, diameters would reduce to 6.28 μm, whereas the loading efficiency of emamectin benzoate did not increase. The PLA microspheres prepared under optimum conditions were smoother and more spherical. The degradation rate in PLA microspheres of emamectin benzoate on the 10th day was 4.29 ± 0.74%, whereas the degradation rates of emamectin benzoate in methanol solution and solid technical material were 46.3 ± 2.11 and 22.7 ± 1.51%, respectively. The PLA skeleton had combined with emamectin benzoate in an amorphous or molecular state by using differential scanning calorimetry (DSC) determination. The results indicated that PLA microspheres of emamectin benzoate with high entrapment rate, loading efficiency, and physicochemical characteristics could be obtained by adding water-miscible organic solvents into the internal organic phase and external aqueous phase.

Stable Aqueous Foams from Cellulose Nanocrystals and Methyl Cellulose.

PubMed

Hu, Zhen; Xu, Richard; Cranston, Emily D; Pelton, Robert H

2016-12-12

The addition of cellulose nanocrystals (CNC) greatly enhanced the properties of methylcellulose (MC) stabilized aqueous foams. CNC addition decreased air bubble size, initial foam densities and drainage rates. Mixtures of 2 wt % CNC + 0.5 wt % MC gave the lowest density foams. This composition sits near the onset of nematic phase formation and also near the overlap concentration of methylcellulose. More than 94% of the added CNC particles remained in the foam phase, not leaving with the draining water. We propose that the nanoscale CNC particles bind to the larger MC coils both in solution and with MC at the air/water interface, forming weak gels that stabilize air bubbles. Wet CNC-MC foams were sufficiently robust to withstand high temperature (70 °C for 6 h) polymerization of water-soluble monomers giving macroporous CNC composite hydrogels based on acrylamide (AM), 2-hydroxyethyl methacrylate (HEMA), or polyethylene glycol diacrylate (PEGDA). At high temperatures, the MC was present as a fibrillar gel phase reinforced by CNC particles, explaining the very high foam stability. Finally, our CNC-MC foams are based on commercially available forms of CNC and MC, already approved for many applications. This is a "shovel-ready" technology.

Degradation of trichloroethene with a noval ball milled Fe-C nanocomposite

DOE PAGES

Gao, Jie; Wang, Wei; Rondinone, Adam Justin; ...

2015-07-18

Nanoscale zero-valent iron (NZVI) is effective in reductively degrading dense non-aqueous phase liquids (DNAPLs), such as trichloroethene (TCE), in groundwater (i.e., dechlorination) although the NZVI technology itself still suffers from high material costs and inability to target hydrophobic contaminants in source zones. To address these problems, we developed a novel, inexpensive iron-carbon (Fe-C) nanocomposite material by simultaneously milling micron-size iron and activated carbon powder. Microscopic and X-ray diffraction (XRD) characterization of the composite material revealed that nanoparticles of Fe were dispersed in activated carbon and a new iron carbide phase was formed. Bench-scale studies showed that this material instantaneously sorbedmore » >90% of TCE from aqueous solutions and subsequently decomposed TCE into non-chlorinated products. Compared to milled Fe, Fe-C nanocomposite dechlorinated TCE at a slightly slower rate and favored the production of ethene over other TCE degradation products such as C 3-C 6 compounds. When placed in hexane-water mixture, the Fe-C nanocomposite materials are preferentially partitioned into the organic phase, indicating the ability of the composite materials to target DNAPL during remediation.« less

Precipitation of Secondary Phases from the Dissolution of Silicate Glasses

NASA Technical Reports Server (NTRS)

Ming, Douglas W.; Golden, D. C.

2004-01-01

Basaltic and anorthositic glasses were subjected to aqueous weathering conditions in the laboratory where the variables were pH, temperature, glass composition, solution composition, and time. Leached layers formed at the surfaces of glasses followed by the precipitation of X-ray amorphous iron and titanium oxides in acidic and neutral solutions at 25 C over time. Glass under oxidative hydrothermal treatments at 150 C yielded a three-layered surface; which included an outer smectite layer, a Fe-Ti oxide layer and an innermost thin leached layer. The introduction of Mg into solutions facilitated the formation of phyllosilicates. Aqueous hydrothermal treatment of anorthositic glasses (high Ca, low Ti) at 200 C readily formed smectite, whereas, the basaltic glasses (high Ti) were more resistant to alteration and smectite was not observed. Alkaline hydrothermal treatment at 2000e produced zeolites and smectites; only smectites formed at 200 C in neutral solutions. These mineralogical changes, although observed under controlled conditions, have direct applications in interpreting planetary (e.g., meteorite parent bodies) and terrestrial aqueous alteration processes.

Characterizing the Phyllosilicates and Amorphous Phases Found by MSL Using Laboratory XRD and EGA Measurements of Natural and Synthetic Materials

NASA Technical Reports Server (NTRS)

Rampe, Elizabeth B.; Morris, Richard V.; Chipera, Steve; Bish, David L.; Bristow, Thomas; Archer, Paul Douglas; Blake, David; Achilles, Cherie; Ming, Douglas W.; Vaniman, David;

TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: phase diagrams and molecular dynamic simulations.

PubMed

Taha, Mohamed; Lee, Ming-Jer

2013-06-28

Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol∕acetonitrile∕acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.

Pore Scale Dynamics of Microemulsion Formation.

PubMed

Unsal, Evren; Broens, Marc; Armstrong, Ryan T

2016-07-19

Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (<10(-2) mN m(-1)) that is required for miscibility to occur. Many studies focus on microemulsion formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

A novel strategy towards designing a CdSe quantum dot-metallohydrogel composite material.

PubMed

Chatterjee, Sayantan; Maitra, Uday

2016-08-11

We have described here an efficient method to disperse hydrophobic CdSe quantum dots (QDs) in an aqueous phase using cetyltrimethylammonium bromide (CTAB) micelles without any surface ligand exchange. The water soluble QDs were then embedded in 3D self assembled fibrillar networks (SAFINs) of a hydrogel showing homogeneous dispersibility as evidenced from optical and electron microscopic techniques. The photophysical studies of the hydrogel-QD composite are reported for the first time. These composite materials may have potential applications in biology, optoelectronics, sensors, non-linear optics and materials science.

Plasmid DNA partitioning and separation using poly(ethylene glycol)/poly(acrylate)/salt aqueous two-phase systems.

PubMed

Johansson, Hans-Olof; Matos, Tiago; Luz, Juliana S; Feitosa, Eloi; Oliveira, Carla C; Pessoa, Adalberto; Bülow, Leif; Tjerneld, Folke

2012-04-13

Phase diagrams of poly(ethylene glycol)/polyacrylate/Na(2)SO(4) systems have been investigated with respect to polymer size and pH. Plasmid DNA from Escherichia coli can depending on pH and polymer molecular weight be directed to a poly(ethylene glycol) or to a polyacrylate-rich phase in an aqueous two-phase system formed by these polymers. Bovine serum albumin (BSA) and E. coli homogenate proteins can be directed opposite to the plasmid partitioning in these systems. Two bioseparation processes have been developed where in the final step the pDNA is partitioned to a salt-rich phase giving a total process yield of 60-70%. In one of them the pDNA is partitioned between the polyacrylate and PEG-phases in order to remove proteins. In a more simplified process the plasmid is partitioned to a PEG-phase and back-extracted into a Na(2)SO(4)-rich phase. The novel polyacrylate/PEG system allows a strong change of the partitioning between the phases with relatively small changes in composition or pH. Copyright © 2012 Elsevier B.V. All rights reserved.

Aqueous stream characterization from biomass fast pyrolysis and catalytic fast pyrolysis

DOE PAGES

Black, Brenna A.; Michener, William E.; Ramirez, Kelsey J.; ...

2016-09-05

Here, biomass pyrolysis offers a promising means to rapidly depolymerize lignocellulosic biomass for subsequent catalytic upgrading to renewable fuels. Substantial efforts are currently ongoing to optimize pyrolysis processes including various fast pyrolysis and catalytic fast pyrolysis schemes. In all cases, complex aqueous streams are generated containing solubilized organic compounds that are not converted to target fuels or chemicals and are often slated for wastewater treatment, in turn creating an economic burden on the biorefinery. Valorization of the species in these aqueous streams, however, offers significant potential for substantially improving the economics and sustainability of thermochemical biorefineries. To that end, heremore » we provide a thorough characterization of the aqueous streams from four pilot-scale pyrolysis processes: namely, from fast pyrolysis, fast pyrolysis with downstream fractionation, in situ catalytic fast pyrolysis, and ex situ catalytic fast pyrolysis. These configurations and processes represent characteristic pyrolysis processes undergoing intense development currently. Using a comprehensive suite of aqueous-compatible analytical techniques, we quantitatively characterize between 12 g kg -1 of organic carbon of a highly aqueous catalytic fast pyrolysis stream and up to 315 g kg -1 of organic carbon present in the fast pyrolysis aqueous streams. In all cases, the analysis ranges between 75 and 100% of mass closure. The composition and stream properties closely match the nature of pyrolysis processes, with high contents of carbohydrate-derived compounds in the fast pyrolysis aqueous phase, high acid content in nearly all streams, and mostly recalcitrant phenolics in the heavily deoxygenated ex situ catalytic fast pyrolysis stream. Overall, this work provides a detailed compositional analysis of aqueous streams from leading thermochemical processes -- analyses that are critical for subsequent development of selective valorization strategies for these waste streams.« less

Aqueous stream characterization from biomass fast pyrolysis and catalytic fast pyrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Black, Brenna A.; Michener, William E.; Ramirez, Kelsey J.

Here, biomass pyrolysis offers a promising means to rapidly depolymerize lignocellulosic biomass for subsequent catalytic upgrading to renewable fuels. Substantial efforts are currently ongoing to optimize pyrolysis processes including various fast pyrolysis and catalytic fast pyrolysis schemes. In all cases, complex aqueous streams are generated containing solubilized organic compounds that are not converted to target fuels or chemicals and are often slated for wastewater treatment, in turn creating an economic burden on the biorefinery. Valorization of the species in these aqueous streams, however, offers significant potential for substantially improving the economics and sustainability of thermochemical biorefineries. To that end, heremore » we provide a thorough characterization of the aqueous streams from four pilot-scale pyrolysis processes: namely, from fast pyrolysis, fast pyrolysis with downstream fractionation, in situ catalytic fast pyrolysis, and ex situ catalytic fast pyrolysis. These configurations and processes represent characteristic pyrolysis processes undergoing intense development currently. Using a comprehensive suite of aqueous-compatible analytical techniques, we quantitatively characterize between 12 g kg -1 of organic carbon of a highly aqueous catalytic fast pyrolysis stream and up to 315 g kg -1 of organic carbon present in the fast pyrolysis aqueous streams. In all cases, the analysis ranges between 75 and 100% of mass closure. The composition and stream properties closely match the nature of pyrolysis processes, with high contents of carbohydrate-derived compounds in the fast pyrolysis aqueous phase, high acid content in nearly all streams, and mostly recalcitrant phenolics in the heavily deoxygenated ex situ catalytic fast pyrolysis stream. Overall, this work provides a detailed compositional analysis of aqueous streams from leading thermochemical processes -- analyses that are critical for subsequent development of selective valorization strategies for these waste streams.« less

Fe-Bearing Phases Identified by the Moessbauer Spectrometers on the Mars Exploration Rovers: An Overview

NASA Technical Reports Server (NTRS)

Morris, R. V.; Klingelhoefer, G.; Rodionov, D.; Yen, A.; Gellert, R.

2006-01-01

The twin Mars Exploration Rovers Spirit and Opportunity have explored the martian surface at Gusev Crater (GC) and Meridiani Planum (MP), respectively, for about two Earth years. The Moessbauer (MB) spectrometers on both rovers have analyzed an aggregate of 200 surface targets and have returned to Earth information on the oxidation state of iron, the mineralogical composition of Febearing phases, and the distribution of Fe among oxidation states and phases at the two landing sites [1-7]. To date, 15 component subspectra (10 doublets and 5 sextets) have been identified and most have been assigned to mineralogical compositions. Two subspectra are assigned to phases (jarosite and goethite) that are marker minerals for aqueous processes because they contain hydroxide anion in their structures. In this paper, we give an overview of the Febearing phases identified and their distributions at Gusev crater and Meridiani Planum.

Fe-Bearing Phases Indentified by the Moessbauer Spectrometers on the Mars Exploration Rovers: An Overview

NASA Technical Reports Server (NTRS)

Morris, R. V.; Klingelhoefer, G.; Ming, D. W.; Schroeder, C.; Rodionov, D.; Yen, A.; Gellert, R.

2006-01-01

The twin Mars Exploration Rovers Spirit and Opportunity have explored the martian surface at Gusev Crater (GC) and Meridiani Planum (MP), respectively, for about two Earth years. The Moessbauer (MB) spectrometers on both rovers have analyzed an aggregate of approx.200 surface targets and have returned to Earth information on the oxidation state of iron, the mineralogical composition of Fe-bearing phases, and the distribution of Fe among oxidation states and phases at the two landing sites [1-7]. To date, 15 component subspectra (10 doublets and 5 sextets) have been identified and most have been assigned to mineralogical compositions. Two subspectra are assigned to phases (jarosite and goethite) that are marker minerals for aqueous processes because they contain hydroxide anion in their structures. In this paper, we give an overview of the Febearing phases identified and their distributions at Gusev crater and Meridiani Planum.

Biotic and abiotic pathways of phosphorus cycling in minerals and sediments: insights from oxygen isotopes in phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaisi, Deb P.; Kukkadapu, Ravi K.; Stout, Lisa M.

2011-07-06

A key question to address in the development of oxygen isotope ratios in phosphate (18Op) as a tracer of biogeochemical cycling of phosphorus in ancient and modern environments is the nature of isotopic signatures associated with uptake and cycling of mineral-bound phosphate by microorganisms. Here we present experimental results aimed at understanding the biotic and abiotic pathway of P cycling during biological uptake of phosphate sorbed to ferrihydrite and the selective uptake of specific sedimentary phosphate phases by Escherichia coli, Vibrio fischeri and Marinobacter aquaeolei. Results indicate that a significant fraction of ferrihydrite-bound phosphate is biologically available. The fraction ofmore » phosphate taken up by E. coli attained an equilibrium isotopic composition in a short time (<50 hrs) due to efficient O-isotope exchange between phosphate and water (biotic pathway). The difference in isotopic composition between newly equilibrated aqueous and residual sorbed phosphate promoted the exchange of intact phosphate radicals (abiotic pathway) so that this difference gradually became negligible. In sediment containing different P phases, E. coli and V. fischeri ‘extracted’ loosely sorbed phosphate first while M. aquaeolei preferred iron-oxide bound phosphate. Each bacterium imprinted a biotic isotopic signature on each P phase that it took up and cycled. For example, the 18Op value of the sorbed phosphate phase shifted gradually towards equilibrium isotopic composition and the value of Fe oxide-bound phosphate showed slight changes at first, but when new iron oxides were formed, co-precipitated/occluded phosphate retained 18O values of aqueous phosphate at that time. Concentrations and isotopic compositions of authigenic and detrital phosphates did not change, suggesting that these phosphate phases were not utilized by bacteria. These findings support burgeoning applications of 18Op as a tracer of phosphorus cycling in sediments, soils and aquatic environments and as an indicator of paleo- environmental conditions.« less

Synthetic fluid inclusions in natural quartz I. Compositional types synthesized and applications to experimental geochemistry

NASA Astrophysics Data System (ADS)

Sterner, S. Michael; Bodnar, Robert J.

1984-12-01

Synthetic fluid inclusions having a wide range of geologically applicable compositions in the C-O-H-S-Na-K-Ca-Cl-Cu-Fe system have been formed by healing fractures in inclusion-free natural quartz and by precipitating new quartz overgrowths on an original "seed" crystal. Inclusion types synthesized include: (1) liquid-rich, pure H 2O inclusions of primary and secondary origin, (2) pure H 2O inclusions with the critical density, (3) liquid-rich inclusions containing undersaturated aqueous solutions of NaCl or KCl or CaCl 2, or mixtures of the three salts, (4) H 2O-NaCl inclusions containing halite daughter minerals, (5) H 2O-NaCl-KCl inclusions containing halite and sylvite daughter minerals, (6) H 2O-CO 2 inclusions of various compositions containing liquid H 2O and either CO 2 vapor or CO 2 liquid, or both, at 25°C, (7) H 2O-CO 2-NaCl inclusions containing an aqueous phase, liquid and vapor CO 2, and halite at 25°C, (8) C-O-H inclusions containing liquid H 2O, a CO 2-CH 4 liquid phase and graphite daughter minerals at 25°C, (9) H 2O-NaCl inclusions that contain a chalcopyrite daughter mineral, and (10)inclusions representing trapping of the coexisting, immiscible fluids in the H 2O-NaCl, H 2O-CO 2-NaCl, and Na-C-O-H systems. The inclusions exhibit uniform phase ratios at room temperature, and the temperatures of various phase changes within individual inclusions agree with those predicted from experimental and theoretical data, indicating that the inclusion fluid has the same composition and density as the parent solution. These 'miniature autoclaves' thus may be used to study various problems related to fluid inclusion research, to calibrate analytical equipment used to study natural inclusions, and to study phase equilibria, solubility and PVT relations of a variety of chemical systems.

Equivalent Aqueous Phase Modulation of Domain Segregation in Myelin Monolayers and Bilayer Vesicles

PubMed Central

Oliveira, Rafael G.; Schneck, Emanuel; Funari, Sergio S.; Tanaka, Motomu; Maggio, Bruno

2010-01-01

Purified myelin can be spread as monomolecular films at the air/aqueous interface. These films were visualized by fluorescence and Brewster angle microscopy, showing phase coexistence at low and medium surface pressures (<20–30 mN/m). Beyond this threshold, the film becomes homogeneous or not, depending on the aqueous subphase composition. Pure water as well as sucrose, glycerol, dimethylsulfoxide, and dimethylformamide solutions (20% in water) produced monolayers that become homogeneous at high surface pressures; on the other hand, the presence of salts (NaCl, CaCl2) in Ringer's and physiological solution leads to phase domain microheterogeneity over the whole compression isotherm. These results show that surface heterogeneity is favored by the ionic milieu. The modulation of the phase-mixing behavior in monolayers is paralleled by the behavior of multilamellar vesicles as determined by small-angle and wide-angle x-ray scattering. The correspondence of the behavior of monolayers and multilayers is achieved only at high surface pressures near the equilibrium adsorption surface pressure; at lower surface pressures, the correspondence breaks down. The equilibrium surface tension on all subphases corresponds to that of the air/alkane interface (27 mN/m), independently on the surface tension of the clean subphase. PMID:20816062

Optimization of Ultrasonic-Assisted Aqueous Two-Phase Extraction of Phloridzin from Malus Micromalus Makino with Ethanol/Ammonia Sulfate System.

PubMed

Zhang, Zhen; Liu, Fang; He, Caian; Yu, Yueli; Wang, Min

2017-12-01

Application of an aqueous two-phase system (ATPS) coupled with ultrasonic technology for the extraction of phloridzin from Malus micromalus Makino was evaluated and optimized by response surface methodology (RSM). The ethanol/ammonium sulfate ATPS was selected for detailed investigation, including the phase diagram, effect of phase composition and extract conditions on the partition of phloridzin, and the recycling of ammonium sulfate. In addition, the evaluation of extraction efficiency and the identification of phloridzin were investigated. The optimal partition coefficient (6.55) and recovery (92.86%) of phloridzin were obtained in a system composed of 35% ethanol (w/w) and 16% (NH 4 ) 2 SO 4 (w/w), 51:1 liquid-to-solid ratio, and extraction temperature of 36 °C. Comparing with the traditional solvent extraction with respective 35% and 80% ethanol, ultrasonic-assisted aqueous two-phase extraction (UAATPE) strategy had significant advantages with lower ethanol consumption, less impurity of sugar and protein, and higher extracting efficiency of phloridzin. Our result indicated that UAATPE was a valuable method for the extraction and preliminary purification of phloridzin from the fruit of Malus micromalus Makino, which has great potential in the deep processing of Malus micromalus Makino industry to increase these fruits' additional value and drive the local economic development. © 2017 Institute of Food Technologists®.

Molecularly imprinted polymer/cryogel composites for solid-phase extraction of bisphenol A from river water and wine.

PubMed

Baggiani, Claudio; Baravalle, Patrizia; Giovannoli, Cristina; Anfossi, Laura; Giraudi, Gianfranco

2010-05-01

Superporous monolithic hydrogels (cryogel monoliths) are elastic, sponge-like materials that can be prepared in an aqueous medium through a cryotropic gelation technique. These monoliths show interesting properties for the development of high-throughput solid-phase extraction supports to treat large volumes of aqueous samples. In this work, a cryogel-supported molecularly imprinted solid-phase extraction approach for the endocrine disruptor bisphenol A (BPA) from river water and wine samples is presented. An imprinted polymer with molecular recognition properties for BPA was prepared in acetonitrile by thermal polymerization of a mixture of 4,4'-dihydroxy-2,2-diphenyl-1,1,1,3,3,3-trifluoropropane as a mimic template of BPA, 4-vinylpyridine and trimethylolpropane trimethacrylate in a molar ratio of 1 + 6 + 6. Fine imprinted particles (<10 microm) were embedded in a poly-acrylamide-co-N,N'-methylenbisacrylamide cryogel obtained by ammonium persulfate-induced cryopolymerization at -18 degrees C. The resulting monolithic gel was evaluated for its use as a sorbent support in an off-line solid-phase extraction approach to recover BPA from dilute aqueous samples with minimum pre-loading work-up. The optimized extraction protocol resulted in a reliable MISPE method suitable to selectively extract and preconcentrate BPA from river water and red wine samples, demonstrating the practical feasibility of cryogel-trapped imprinted polymers as solid-phase extraction materials.

Effects of Material Properties on Sedimentation and Aggregation of Titanium Dioxide Nanoparticles of Anatase and Rutile in the Aqueous Phase

EPA Science Inventory

This study investigated the sedimentation and aggregation kinetics of titanium dioxide (TiO2) nanoparticles with varying material properties (i.e., crystallinity, morphology, and chemical compositions). Used in the study were various types of commercially available TiO2 nanoparti...

Metal-Catalyzed Aqueous Oxidation Processes in Merged Microdroplets

NASA Astrophysics Data System (ADS)

Davis, R. D.; Wilson, K. R.

2017-12-01

Iron-catalyzed production of reactive oxygen species (ROS) from hydrogen peroxide (Fenton's reaction) is a fundamental process throughout nature, from groundwater to cloud droplets. In recent years, Fenton's chemistry has gained further interest in atmospheric science as a potentially important process in the oxidation of aqueous secondary organic aerosol (e.g., Chu et al., Sci. Rep., 2017), with some observations indicating that Fenton's reaction proceeds at a higher rate at aerosol interfaces compared to in the bulk (Enami et al., PNAS, 2014). However, a fundamental-level mechanistic understanding of this process remains elusive and the relative importance of interfacial versus bulk chemistry for aqueous organic processing via Fenton's has yet to be fully established. Here, we present a microreactor experimental approach to studying aqueous-phase Fenton's chemistry in microdroplets by rapidly mixing droplets of different composition. Utilizing two on-demand droplet generators, a stream of microdroplets containing aqueous iron chloride were merged with a separate stream of microdroplets containing aqueous hydrogen peroxide and a range of aromatic organic compounds, initiating ROS production and subsequent aqueous-phase oxidation reactions. Upon merging, mixing of the microdroplets occurred in submillisecond timescales, thus allowing the reaction progress to be monitored with high spatial and temporal resolution. For relatively large microreactor (droplet) sizes (50 µm diameter post-merging), the Fenton-initiated aqueous oxidation of aromatic organic compounds in merged microdroplets was consistent with bulk predictions with hydroxyl radicals as the ROS. The microdroplet-size dependence of this observation, along with the role of other ROS species produced from Fenton and Fenton-like processes, will be discussed in the context of relative importance to aqueous organic processing of atmospheric particles.

Electric Double Layer Composed of an Antagonistic Salt in an Aqueous Mixture: Local Charge Separation and Surface Phase Transition

NASA Astrophysics Data System (ADS)

Yabunaka, Shunsuke; Onuki, Akira

2017-09-01

We examine an electric double layer containing an antagonistic salt in an aqueous mixture, where the cations are small and hydrophilic but the anions are large and hydrophobic. In this situation, a strong coupling arises between the charge density and the solvent composition. As a result, the anions are trapped in an oil-rich adsorption layer on a hydrophobic wall. We then vary the surface charge density σ on the wall. For σ >0 the anions remain accumulated, but for σ <0 the cations are attracted to the wall with increasing |σ |. Furthermore, the electric potential drop Ψ (σ ) is nonmonotonic when the solvent interaction parameter χ (T ) exceeds a critical value χc determined by the composition and the ion density in the bulk. This leads to a first-order phase transition between two kinds of electric double layers with different σ and common Ψ . In equilibrium such two-layer regions can coexist. The steric effect due to finite ion sizes is crucial in these phenomena.

Aqueous Solution-Phase Selenized CuIn(S,Se)2 Thin Film Solar Cells Annealed under Inert Atmosphere.

PubMed

Oh, Yunjung; Yang, Wooseok; Kim, Jimin; Woo, Kyoohee; Moon, Jooho

2015-10-14

A nonvacuum solution-based approach can potentially be used to realize low cost, roll-to-roll fabrication of chalcopyrite CuIn(S,Se)2 (CISSe) thin film solar cells. However, most solution-based fabrication methods involve highly toxic solvents and inevitably require sulfurization and/or postselenization with hazardous H2S/H2Se gases. Herein, we introduce novel aqueous-based Cu-In-S and Se inks that contain an amine additive for producing a high-quality absorber layer. CISSe films were fabricated by simple deposition of Cu-In-S ink and Se ink followed by annealing under an inert atmosphere. Compositional and phase analyses confirmed that our simple aqueous ink-based method facilitated in-site selenization of the CIS layer. In addition, we investigated the molecular structures of our aqueous inks to determine how crystalline chalcopyrite absorber layers developed without sulfurization and/or postselenization. CISSe thin film solar cells annealed at 550 °C exhibited an efficiency of 4.55% under AM 1.5 illumination. The low-cost, nonvacuum method to deposit chalcopyrite absorber layers described here allows for safe and simple processing of thin film solar cells.

Preparing polymeric matrix composites using an aqueous slurry technique

NASA Technical Reports Server (NTRS)

Johnston, Norman J. (Inventor); Towell, Timothy W. (Inventor)

1993-01-01

An aqueous process was developed to prepare a consolidated composite laminate from an aqueous slurry. An aqueous poly(amic acid) surfactant solution was prepared by dissolving a poly(amic acid) powder in an aqueous ammonia solution. A polymeric powder was added to this solution to form a slurry. The slurry was deposited on carbon fiber to form a prepreg which was dried and stacked to form a composite laminate. The composite laminate was consolidated using pressure and was heated to form the polymeric matrix. The resulting composite laminate exhibited high fracture toughness and excellent consolidation.

Potential Cement Phases in Sedimentary Rocks Drilled by Curiosity at Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Rampe, E. B.; Morris, R. V.; Bish, D. L.; Chipera, S. J.; Ming, D. W.; Blake, D. F.; Vaniman, D. T.; Bristow, T. F.; Cavanagh, P.; Farmer, J. D.;

Synthesis and Characterization of Graphene Oxide-Polystyrene Composite Capsules with Aqueous Cargo via a Water-Oil-Water Multiple Emulsion Templating Route.

PubMed

Ali, Muthana; McCoy, Thomas M; McKinnon, Ian R; Majumder, Mainak; Tabor, Rico F

2017-05-31

Graphene oxide/polystyrene (GO/PS) nanocomposite capsules containing a two-compartment cargo have been successfully fabricated using a Pickering emulsion strategy. Highly purified GO sheets with typically micrometer-scale lateral dimensions and amphiphilic characteristics were prepared from the oxidation reaction of graphite with concomitant exfoliation of the graphite structure. These GO sheets were employed as a stabilizer for oil-in-water emulsions where the oil phase comprised toluene or olive oil. The stability and morphology of the emulsions were extensively studied as a function of different parameters including GO concentration, aqueous phase pH, ultrasonication time, effects of added electrolytes and stability to dilution. In selected conditions, the olive oil emulsions showed spontaneous formation of multiple w/o/w emulsions with high stability, whereas toluene formed simple o/w emulsions of lower overall stability. Olive oil emulsions were therefore used to prepare capsules templated from emulsion droplets by surrounding the oil phase with a GO/PS shell. The GO sheets, emulsions and composite capsules were characterized using a variety of physical and spectroscopic techniques in order to unravel the interactions responsible for capsule formation. The ability of the capsules to control the release of a model active agent in the form of a hydrophilic dye was explored, and release kinetics were monitored using UV-visible spectroscopy to obtain rate parameters. The composite capsules showed promising sustained release properties, with release rates 11× lower than the precursor GO-stabilized multiple emulsion droplets.

Characterizing Oxidized North American Fire Emissions and Their Aqueous/Multiphase Atmospheric Transformations Through the FIREX Campaign

NASA Astrophysics Data System (ADS)

Tomaz, S.; Cui, T.; Chen, Y.; Sexton, K.; Surratt, J. D.; Turpin, B. J.

2017-12-01

Aqueous multiphase chemistry of water-soluble organic gases (WSOGs) is now recognized to be a potential and significant source of atmospheric secondary organic aerosol (SOA). SOA formation through aqueous-phase chemistry of WSOGs, known to be present in wildfire emissions, such as glycolaldehyde or phenols, remains unclear. Furthermore, most oxidized organic constituents of biomass burning (BB) emissions still remain unidentified and may represent a major source of atmospheric aqueous SOA (aqSOA). In the present work, we investigated the chemical composition of gas-phase emissions from the combustion of several western U.S. fuels at the Fire Science Laboratory as part of FIREX, using a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) equipped with iodide reagent ion chemistry. By using the HR-ToF-CIMS, more than 50 oxygen (O)-containing and 15 nitrogen (N)-containing organic compounds were identified in the gas-phase emissions from BB of the western U.S. fuel types. Amongst these compounds, potential precursors of aqSOA were selected based on their atomic O/C ratio, water solubility, abundance and potential reactivity toward hydroxyl (OH) radical using literature data. These results indicated the high potency of BB as a source of aqSOA. We compared these results with water samples collected during the FIREX experiments, by scrubbing gaseous emissions into water using mist chamber samplers. We investigated the composition of these samples using both ion chromatography (IC) and high-resolution quadrupole time-of-flight mass spectrometry equipped with electrospray ionization (ESI-HR-QTOFMS). The presence of potential reactive compounds was evaluated by oxidizing these samples with OH radical (H2O2/UV). Known precursors of aqSOA, such as acetic and glycolic acids, were identified in those samples. The formation of low-volatility organics, such as oxalic and pyruvic acids, through OH oxidation also indicates the potential formation of aqSOA from BB emissions during wildfires.

Determination of ammonium in aqueous samples using new headspace dynamic in-syringe liquid-phase microextraction with in situ derivitazation coupled with liquid chromatography-fluorescence detection.

PubMed

Muniraj, Sarangapani; Yan, Cheing-Tong; Shih, Hou-Kung; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

2012-11-19

A new simultaneous derivatization and extraction method for the preconcentration of ammonia using new one-step headspace dynamic in-syringe liquid-phase microextraction with in situ derivatization was developed for the trace determination of ammonium in aqueous samples by liquid chromatography with fluorescence detection (LC-FLD). The acceptor phase (as derivatization reagent) containing o-phthaldehyde and sodium sulfite was held within a syringe barrel and immersed in the headspace of sample container. The gaseous ammonia from the alkalized aqueous sample formed a stable isoindole derivative with the acceptor phase inside the syringe barrel through the reciprocated movements of plunger. After derivatization-cum-extraction, the acceptor phase was directly injected into LC-FLD for analysis. Parameters affecting the ammonia evolution and the extraction/derivatization efficiency such as sample matrix, pH, temperature, sampling time, and the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger, were studied thoroughly. Results indicated that the maximum extraction efficiency was obtained by using 100μL derivatization reagent in a 1-mL gastight syringe under 8 reciprocated movements of plunger per min to extract ammonia evolved from a 20mL alkalized aqueous solution at 70°C (preheated 4min) with 380rpm stirring for 8min. The detection was linear in the concentration range of 0.625-10μM with the correlation coefficient of 0.9967 and detection limit of 0.33μM (5.6ng mL(-1)) based on SN(-1)=3. The method was applied successfully to determine ammonium in real water samples without any prior cleanup of the samples, and has been proved to be a simple, sensitive, efficient and cost-effective procedure for trace ammonium determination in aqueous samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling.

PubMed

Boone, Eric J; Laskin, Alexander; Laskin, Julia; Wirth, Christopher; Shepson, Paul B; Stirm, Brian H; Pratt, Kerri A

2015-07-21

Cloudwater and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry (HRMS) with nanospray desorption electrospray ionization (nano-DESI) and direct infusion electrospray ionization (ESI) were utilized to compare the organic composition of the particle and cloudwater samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloudwater, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloudwater samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloudwater when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.

Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boone, Eric J.; Laskin, Alexander; Laskin, Julia

2015-07-21

Cloud water and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry with nanospray desorption electrospray ionization and direct infusion electrospray ionization were utilized to compare the organic composition of the particle and cloud water samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloud water, showing the significant influencemore » of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloud water samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloud water when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.« less

Application of fluid-rock reaction studies to in situ recovery from oil sand deposits, Alberta, Canada - I. Aqueous phase results for an experimental-statistical study of water-bitumen-shale reactions

NASA Astrophysics Data System (ADS)

Boon, J. A.; Hitchon, Brian

1983-02-01

In situ recovery operations in oil sand deposits effectively represent man-imposed low to intermediate temperature metamorphism of the sediments in the deposit. In order to evaluate some of the reactions which occur, a factorial experiment was earned out in which a shale from the Lower Cretaceous McMurray Formation in the Athabasca oil sand deposit of Alberta, in the presence or absence of bitumen, was subjected to hydrothermal treatment with aqueous fluids of varying pH and salinity, at two different temperatures, for periods up to 92 hours. The aqueous fluid was analyzed and the analytical data subjected to statistical factor analysis and analysis of variance, which enabled identification of the main processes, namely, cation exchange, the production of two types of colloidal material, and the dissolution of quartz There is also saturation of the aqueous phase by. as yet unidentified, "total organic carbon" and complete conversion and removal of all nitrogen in the shale to the aqueous phase. These reactions have implications with regards to the economics of the in situ recovery process, specifically with respect to the reuse and/or disposal of the produced water and the plugging of the pore space and hence of reduction of permeability between the injection and production wells. As a result of these experiments it is suggested that monitoring of the composition of the produced water from in situ recovery operations in oil sand deposits would be advisable.

CARBON DIOXIDE SEPARATION BY PHASE ENHANCED GAS-LIQUID ABSORPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang Hu

A new process called phase enhanced gas-liquid absorption has been developed in its early stage. It was found that adding another phase into the absorption system of gas/aqueous phase could enhance the absorption rate. A system with three phases was studied. In the system, gas phase was carbon dioxide. Two liquid phases were used. One was organic phase. Another was aqueous phase. By addition of organic phase into the absorption system of CO{sub 2}-aqueous phase, the absorption rate of CO{sub 2} was increased significantly. CO{sub 2} finally accumulated into aqueous phase. The experimental results proved that (1) Absorption rate ofmore » carbon dioxide was enhanced by adding organic phase into gas aqueous phase system; (2) Organic phase played the role of transportation of gas solute (CO{sub 2}). Carbon dioxide finally accumulated into aqueous phase.« less

Non-Boussinesq Dissolution-Driven Convection in Porous Media

NASA Astrophysics Data System (ADS)

Amooie, M. A.; Soltanian, M. R.; Moortgat, J.

2017-12-01

Geological carbon dioxide (CO2) sequestration in deep saline aquifers has been increasingly recognized as a feasible technology to stabilize the atmospheric carbon concentrations and subsequently mitigate the global warming. Solubility trapping is one of the most effective storage mechanisms, which is associated initially with diffusion-driven slow dissolution of gaseous CO2 into the aqueous phase, followed by density-driven convective mixing of CO2 throughout the aquifer. The convection includes both diffusion and fast advective transport of the dissolved CO2. We study the fluid dynamics of CO2 convection in the underlying single aqueous-phase region. Two modeling approaches are employed to define the system: (i) a constant-concentration condition for CO2 in aqueous phase at the top boundary, and (ii) a sufficiently low, constant injection-rate for CO2 from top boundary. The latter allows for thermodynamically consistent evolution of the CO2 composition and the aqueous phase density against the rate at which the dissolved CO2 convects. Here we accurately model the full nonlinear phase behavior of brine-CO2 mixture in a confined domain altered by dissolution and compressibility, while relaxing the common Boussinesq approximation. We discover new flow regimes and present quantitative scaling relations for global characters of spreading, mixing, and dissolution flux in two- and three-dimensional media for the both model types. We then revisit the universal Sherwood-Rayleigh scaling that is under debate for porous media convective flows. Our findings confirm the sublinear scaling for the constant-concentration case, while reconciling the classical linear scaling for the constant-injection model problem. The results provide a detailed perspective into how the available modeling strategies affect the prediction ability for the total amount of CO2 dissolved in the long term within saline aquifers of different permeabilities.

Influence of frequency on the structure of zirconium oxide coatings deposited from aqueous electrolytes under microplasma oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gubaidulina, Tatiana A., E-mail: goub2002@mail.ru; Sergeev, Viktor P., E-mail: vserg@mail.tomsknet.ru; Fedorischeva, Marina V., E-mail: fmw@ispms.tsc.ru

2015-10-27

The work describes the microplasma oxidation (MPO) of zirconium surface resulting in the formation of zirconium oxide Zr-Al-Nb-O. We have used novel power supply to deposit oxide ceramic coatings by MPO and studied the effect of current density on the phase structure of oxide ceramic coatings. The size of microcracks in the coatings was determined at different frequencies. We have also used EVO50c scanning election microscope with an attachment for elemental analysis to study the morphology and elemental composition of oxide ceramic coating. In addition, we have established the influence of the frequency on the phase composition of the coating:more » at the frequency of 2500 Hz, the fraction of monoclinic phase was 18%, while the fraction of tetragonal phase amounted to 72%. The oxide ceramic coating produced at 250 Hz contained 38% of monoclinic phase and 62% of tetragonal phase; in addition, it had no buildups and craters.« less

Lignin solubilization and aqueous phase reforming for the production of aromatic chemicals and hydrogen.

PubMed

Zakzeski, Joseph; Weckhuysen, Bert M

2011-03-21

The solubilization and aqueous phase reforming of lignin, including kraft, soda, and alcell lignin along with sugarcane bagasse, at low temperatures (T≤498 K) and pressures (P≤29 bar) is reported for the first time for the production of aromatic chemicals and hydrogen. Analysis of lignin model compounds and the distribution of products obtained during the lignin aqueous phase reforming revealed that lignin was depolymerized through disruption of the abundant β-O-4 linkages and, to a lesser extent, the 5-5' carbon-carbon linkages to form monomeric aromatic compounds. The alkyl chains contained on these monomeric compounds were readily reformed to produce hydrogen and simple aromatic platform chemicals, particularly guaiacol and syringol, with the distribution of each depending on the lignin source. The methoxy groups present on the aromatic rings were subject to hydrolysis to form methanol, which was also readily reformed to produce hydrogen and carbon dioxide. The composition of the isolated yields of monomeric aromatic compounds and overall lignin conversion based on these isolated yields varied from 10-15% depending on the lignin sample, with the balance consisting of gaseous products and residual solid material. Furthermore, we introduce the use of a high-pressure autoclave with optical windows and an autoclave with ATR-IR sentinel for on-line in situ spectroscopic monitoring of biomass conversion processes, which provides direct insight into, for example, the solubilization process and aqueous phase reforming reaction of lignin. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measurement of natural carbon isotopic composition of acetone in human urine.

PubMed

Yamada, Keita; Ohishi, Kazuki; Gilbert, Alexis; Akasaka, Mai; Yoshida, Naohiro; Yoshimura, Ryoko

2016-02-01

The natural carbon isotopic composition of acetone in urine was measured in healthy subjects using gas chromatography-combustion-isotope ratio mass spectrometry combined with headspace solid-phase microextraction (HS-SPME-GC-C-IRMS). Before applying the technique to a urine sample, we optimized the measurement conditions of HS-SPME-GC-C-IRMS using aqueous solutions of commercial acetone reagents. The optimization enabled us to determine the carbon isotopic compositions within ±0.2 ‰ of precision and ±0.3‰ of error using 0.05 or 0.2 mL of aqueous solutions with acetone concentrations of 0.3-121 mg/L. For several days, we monitored the carbon isotopic compositions and concentrations of acetone in urine from three subjects who lived a daily life with no restrictions. We also monitored one subject for 3 days including a fasting period of 24 h. These results suggest that changes in the availability of glucose in the liver are reflected in changes in the carbon isotopic compositions of urine acetone. Results demonstrate that carbon isotopic measurement of metabolites in human biological samples at natural abundance levels has great potential as a tool for detecting metabolic changes caused by changes in physiological states and disease.

Volatility of organic aerosol: evaporation of ammonium sulfate/succinic acid aqueous solution droplets.

PubMed

Yli-Juuti, Taina; Zardini, Alessandro A; Eriksson, Axel C; Hansen, Anne Maria K; Pagels, Joakim H; Swietlicki, Erik; Svenningsson, Birgitta; Glasius, Marianne; Worsnop, Douglas R; Riipinen, Ilona; Bilde, Merete

2013-01-01

Condensation and evaporation modify the properties and effects of atmospheric aerosol particles. We studied the evaporation of aqueous succinic acid and succinic acid/ammonium sulfate droplets to obtain insights on the effect of ammonium sulfate on the gas/particle partitioning of atmospheric organic acids. Droplet evaporation in a laminar flow tube was measured in a Tandem Differential Mobility Analyzer setup. A wide range of droplet compositions was investigated, and for some of the experiments the composition was tracked using an Aerosol Mass Spectrometer. The measured evaporation was compared to model predictions where the ammonium sulfate was assumed not to directly affect succinic acid evaporation. The model captured the evaporation rates for droplets with large organic content but overestimated the droplet size change when the molar concentration of succinic acid was similar to or lower than that of ammonium sulfate, suggesting that ammonium sulfate enhances the partitioning of dicarboxylic acids to aqueous particles more than currently expected from simple mixture thermodynamics. If extrapolated to the real atmosphere, these results imply enhanced partitioning of secondary organic compounds to particulate phase in environments dominated by inorganic aerosol.

MoOx thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors

PubMed Central

Liu, Can; Li, Zhengcao; Zhang, Zhengjun

2013-01-01

In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoOx films (2 ⩽ x ⩽ 2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li2SO4. The MoOx (x ≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm−2 measured at 5 mV s−1), best rate capability and excellent stability at potentials below −0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO2 nanocrystals and amorphous MoOx (2.3 < x ⩽ 3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO2 grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process. PMID:27877625

MoO x thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors.

PubMed

Liu, Can; Li, Zhengcao; Zhang, Zhengjun

2013-12-01

In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoO x films (2 ⩽ x ⩽ 2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li 2 SO 4 . The MoO x ( x ≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm -2 measured at 5 mV s -1 ), best rate capability and excellent stability at potentials below -0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO 2 nanocrystals and amorphous MoO x (2.3 < x ⩽ 3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO 2 grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process.

MoOx thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Can; Li, Zhengcao; Zhang, Zhengjun

2013-12-01

In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoOx films (2 ⩽ x ⩽ 2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li2SO4. The MoOx (x ≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm-2 measured at 5 mV s-1), best rate capability and excellent stability at potentials below -0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO2 nanocrystals and amorphous MoOx (2.3 < x ⩽ 3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO2 grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process.

High-energy MnO2 nanowire/graphene and graphene asymmetric electrochemical capacitors.

PubMed

Wu, Zhong-Shuai; Ren, Wencai; Wang, Da-Wei; Li, Feng; Liu, Bilu; Cheng, Hui-Ming

2010-10-26

In order to achieve high energy and power densities, we developed a high-voltage asymmetric electrochemical capacitor (EC) based on graphene as negative electrode and a MnO(2) nanowire/graphene composite (MGC) as positive electrode in a neutral aqueous Na(2)SO(4) solution as electrolyte. MGC was prepared by solution-phase assembly of graphene sheets and α-MnO(2) nanowires. Such aqueous electrolyte-based asymmetric ECs can be cycled reversibly in the high-voltage region of 0-2.0 V and exhibit a superior energy density of 30.4 Wh kg(-1), which is much higher than those of symmetric ECs based on graphene//graphene (2.8 Wh kg(-1)) and MGC//MGC (5.2 Wh kg(-1)). Moreover, they present a high power density (5000 W kg(-1) at 7.0 Wh kg(-1)) and acceptable cycling performance of ∼79% retention after 1000 cycles. These findings open up the possibility of graphene-based composites for applications in safe aqueous electrolyte-based high-voltage asymmetric ECs with high energy and power densities.

Volatility of Organic Aerosol: Evaporation of Ammonium Sulfate/Succinic Acid Aqueous Solution Droplets

PubMed Central

2013-01-01

Condensation and evaporation modify the properties and effects of atmospheric aerosol particles. We studied the evaporation of aqueous succinic acid and succinic acid/ammonium sulfate droplets to obtain insights on the effect of ammonium sulfate on the gas/particle partitioning of atmospheric organic acids. Droplet evaporation in a laminar flow tube was measured in a Tandem Differential Mobility Analyzer setup. A wide range of droplet compositions was investigated, and for some of the experiments the composition was tracked using an Aerosol Mass Spectrometer. The measured evaporation was compared to model predictions where the ammonium sulfate was assumed not to directly affect succinic acid evaporation. The model captured the evaporation rates for droplets with large organic content but overestimated the droplet size change when the molar concentration of succinic acid was similar to or lower than that of ammonium sulfate, suggesting that ammonium sulfate enhances the partitioning of dicarboxylic acids to aqueous particles more than currently expected from simple mixture thermodynamics. If extrapolated to the real atmosphere, these results imply enhanced partitioning of secondary organic compounds to particulate phase in environments dominated by inorganic aerosol. PMID:24107221

Geochemical constraints on possible subduction components in lavas of Mayon and Taal Volcanoes, Southern Luzon, Philippines

USGS Publications Warehouse

Castillo, P.R.; Newhall, C.G.

2004-01-01

Mayon is the most active volcano along the east margin of southern Luzon, Philippines. Petrographic and major element data indicate that Mayon has produced a basaltic to andesitic lava series by fractional crystallization and magma mixing. Trace element data indicate that the parental basalts came from a heterogeneous mantle source. The unmodified composition of the mantle wedge is similar to that beneath the Indian Ocean. To this mantle was added a subduction component consisting of melt from subducted pelagic sediment and aqueous fluid dehydrated from the subducted basaltic crust. Lavas from the highly active Taal Volcano on the west margin of southern Luzon are compositionally more variable than Mayon lavas. Taal lavas also originated from a mantle wedge metasomatized by aqueous fluid dehydrated from the subducted basaltic crust and melt plus fluid derived from the subducted terrigenous sediment. More sediment is involved in the generation of Taal lavas. Lead isotopes argue against crustal contamination. Some heterogeneity of the unmodified mantle wedge and differences in whether the sediment signature is transferred into the lava source through an aqueous fluid or melt phase are needed to explain the regional compositional variation of Philippine arc lavas. ?? Oxford University Press 2004; all rights reserved.

User's guide to PHREEQC (Version 2) : a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations

USGS Publications Warehouse

Parkhurst, David L.; Appelo, C.A.J.

1999-01-01

PHREEQC version 2 is a computer program written in the C programming language that is designed to perform a wide variety of low-temperature aqueous geochemical calculations. PHREEQC is based on an ion-association aqueous model and has capabilities for (1) speciation and saturation-index calculations; (2) batch-reaction and one-dimensional (1D) transport calculations involving reversible reactions, which include aqueous, mineral, gas, solid-solution, surface-complexation, and ion-exchange equilibria, and irreversible reactions, which include specified mole transfers of reactants, kinetically controlled reactions, mixing of solutions, and temperature changes; and (3) inverse modeling, which finds sets of mineral and gas mole transfers that account for differences in composition between waters, within specified compositional uncertainty limits.New features in PHREEQC version 2 relative to version 1 include capabilities to simulate dispersion (or diffusion) and stagnant zones in 1D-transport calculations, to model kinetic reactions with user-defined rate expressions, to model the formation or dissolution of ideal, multicomponent or nonideal, binary solid solutions, to model fixed-volume gas phases in addition to fixed-pressure gas phases, to allow the number of surface or exchange sites to vary with the dissolution or precipitation of minerals or kinetic reactants, to include isotope mole balances in inverse modeling calculations, to automatically use multiple sets of convergence parameters, to print user-defined quantities to the primary output file and (or) to a file suitable for importation into a spreadsheet, and to define solution compositions in a format more compatible with spreadsheet programs. This report presents the equations that are the basis for chemical equilibrium, kinetic, transport, and inverse-modeling calculations in PHREEQC; describes the input for the program; and presents examples that demonstrate most of the program's capabilities.

Biosignatures in modern sulfates: texture, composition and depositional environments of gypsum deposits at Guerrero Negro, Baja, Mexico

NASA Astrophysics Data System (ADS)

Vogel, M. B.; Des Marais, D. J.; Jahnke, L. L.; Turk, K.; Kubo, M.

2007-12-01

Gypsum (CaSO4·H2O) is an important phase in biogeochemistry and sedimentology as a mineral sink for sulfur, a paleoclimatic indicator, and an endolithic niche for phototrophic and chemotrophic bacteria. Sulfate deposits are also important targets of exploration for evidence of habitable environments and life on Mars. Gypsum deposits from a range of sedimentary environments at the Guerrero Negro crystallizer ponds and sabkha settings were investigated for microscale structure and composition to differentiate fabrics formed under microbial influence from those formed under abiogenic conditions. Sub-sedimentary gypsum forms in sabkha environments as mm to cm scale selenite discs (termed bird beak gypsum; Warren, 2006) and selenite disc aggregates. Selenite discs and other sub-sedimentary gypsum are characterized by a sinuous axial microtexture and poikilitically enclosed detrital particles. Sub-aqueous gypsum forms as cements, granules (termed gypsooids), and massive botryoidal crusts that line the sediment water interface and margins of managed crystallizer ponds and natural anchialine pools. Sub-aqueous gypsum exhibits a wide range of textures and mineral/biofilm associations that include amorphous to euhedral, tabular, needle and lensoidal morphologies. Elemental sulfur forms rinds on prismatic, growth aligned gypsum twins and reticulate magnesian carbonate is interspersed with both twinned crystals and rosette aggregates in stratified sub-aqueous environments. Intracrystalline biofilms and cell material was observed in association with nearly all sub-aqueous morphologies but only scarce evidence has been found for intercrystalline microbial communities. Columnar microbial communities living in anchialine pools were found to host precipitation of mm scale gypsum granules in their EPS matrix. Fine scale gypsum textures are unlikely to persist through diagenetic alteration, but understanding their primary associations with sulfur and carbonates is necessary for interpreting sulfates or their replacement phases in the ancient record.

A composite reactor with wetted-wall column for mineral carbonation study in three-phase systems.

PubMed

Zhu, Chen; Yao, Xizhi; Zhao, Liang; Teng, H Henry

2016-11-01

Despite the availability of various reactors designed to study gas-liquid reactions, no appropriate devices are available to accurately investigate triple-phased mineral carbonation reactions involving CO 2 gas, aqueous solutions (containing divalent cations), and carbonate minerals. This report presents a composite reactor that combines a modified conventional wetted-wall column, a pH control module, and an attachment to monitor precipitation reactions. Our test and calibration experiments show that the absorption column behaved largely in agreement with theoretical predictions and previous observations. Experimental confirmation of CO 2 absorption in NaOH and ethanolamine supported the effectiveness of the column for gas-liquid interaction. A test run in the CO 2 -NH 3 -MgCl 2 system carried out for real time investigation of the relevant carbonation reactions shows that the reactor's performance closely followed the expected reaction path reflected in pH change, the occurrence of precipitation, and the rate of NH 3 addition, indicating the appropriateness of the composite device in studying triple-phase carbonation process.

Synthesis, characterisation and phase transition behaviour of temperature-responsive physically crosslinked poly (N-vinylcaprolactam) based polymers for biomedical applications.

PubMed

Halligan, Shane C; Dalton, Maurice B; Murray, Kieran A; Dong, Yixiao; Wang, Wenxin; Lyons, John G; Geever, Luke M

2017-10-01

Poly (N-vinylcaprolactam) (PNVCL) is a polymer which offers superior characteristics for various potential medical device applications. In particular it offers unique thermoresponsive capabilities, which fulfils the material technology constraints required in targeted drug delivery applications. PNVCL phase transitions can be tailored in order to suit the requirements of current and next generation devices, by modifying the contents with regard to the material composition and aqueous polymer concentration. In this study, physically crosslinked Poly (N-vinylcaprolactam)-Vinyl acetate (PNVCL-VAc) copolymers were prepared by photopolymerisation. The structure of the polymers was established by Fourier transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography. The polymers were further characterised using differential scanning calorimetry and swelling studies. Determination of the LCST of the polymers in aqueous solution was achieved by employing four techniques; cloud point, UV-spectrometry, differential scanning calorimetry and rheometry. Sol-gel transition was established using tube inversion method and rheological analysis. This study was conducted to determine the characteristics of PNVCL with the addition of VAc, and to establish the effects on the phase transition. The PNVCL based polymers exhibited a decrease in the LCST as the composition of VAc increased. Sol-gel transition could be controlled by altering the monomeric feed ratio and polymer concentration in aqueous milieu. Importantly all copolymers (10wt% in solution) underwent gelation between 33.6 and 35.9°C, and based on this and the other materials properties recorded in this study, these novel copolymers have potential for use as injectable in situ forming drug delivery systems for targeted drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Cloud Processing of Secondary Organic Aerosol from Isoprene and Methacrolein Photooxidation.

PubMed

Giorio, Chiara; Monod, Anne; Brégonzio-Rozier, Lola; DeWitt, Helen Langley; Cazaunau, Mathieu; Temime-Roussel, Brice; Gratien, Aline; Michoud, Vincent; Pangui, Edouard; Ravier, Sylvain; Zielinski, Arthur T; Tapparo, Andrea; Vermeylen, Reinhilde; Claeys, Magda; Voisin, Didier; Kalberer, Markus; Doussin, Jean-François

2017-10-12

Aerosol-cloud interaction contributes to the largest uncertainties in the estimation and interpretation of the Earth's changing energy budget. The present study explores experimentally the impacts of water condensation-evaporation events, mimicking processes occurring in atmospheric clouds, on the molecular composition of secondary organic aerosol (SOA) from the photooxidation of methacrolein. A range of on- and off-line mass spectrometry techniques were used to obtain a detailed chemical characterization of SOA formed in control experiments in dry conditions, in triphasic experiments simulating gas-particle-cloud droplet interactions (starting from dry conditions and from 60% relative humidity (RH)), and in bulk aqueous-phase experiments. We observed that cloud events trigger fast SOA formation accompanied by evaporative losses. These evaporative losses decreased SOA concentration in the simulation chamber by 25-32% upon RH increase, while aqueous SOA was found to be metastable and slowly evaporated after cloud dissipation. In the simulation chamber, SOA composition measured with a high-resolution time-of-flight aerosol mass spectrometer, did not change during cloud events compared with high RH conditions (RH > 80%). In all experiments, off-line mass spectrometry techniques emphasize the critical role of 2-methylglyceric acid as a major product of isoprene chemistry, as an important contributor to the total SOA mass (15-20%) and as a key building block of oligomers found in the particulate phase. Interestingly, the comparison between the series of oligomers obtained from experiments performed under different conditions show a markedly different reactivity. In particular, long reaction times at high RH seem to create the conditions for aqueous-phase processing to occur in a more efficient manner than during two relatively short cloud events.

Novel Displacement Agents for Aqueous 2-Phase Extraction Can Be Estimated Based on Hybrid Shortcut Calculations.

PubMed

Kress, Christian; Sadowski, Gabriele; Brandenbusch, Christoph

2016-10-01

The purification of therapeutic proteins is a challenging task with immediate need for optimization. Besides other techniques, aqueous 2-phase extraction (ATPE) of proteins has been shown to be a promising alternative to cost-intensive state-of-the-art chromatographic protein purification. Most likely, to enable a selective extraction, protein partitioning has to be influenced using a displacement agent to isolate the target protein from the impurities. In this work, a new displacement agent (lithium bromide [LiBr]) allowing for the selective separation of the target protein IgG from human serum albumin (represents the impurity) within a citrate-polyethylene glycol (PEG) ATPS is presented. In order to characterize the displacement suitability of LiBr on IgG, the mutual influence of LiBr and the phase formers on the aqueous 2-phase system (ATPS) and partitioning is investigated. Using osmotic virial coefficients (B22 and B23) accessible by composition gradient multiangle light-scattering measurements, the precipitating effect of LiBr on both proteins and an estimation of both protein partition coefficients is estimated. The stabilizing effect of LiBr on both proteins was estimated based on B22 and experimentally validated within the citrate-PEG ATPS. Our approach contributes to an efficient implementation of ATPE within the downstream processing development of therapeutic proteins. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Stability of citral in oil-in-water emulsions prepared with medium-chain triacylglycerols and triacetin.

PubMed

Choi, Seung Jun; Decker, Eric Andrew; Henson, Lulu; Popplewell, L Michael; McClements, David Julian

2009-12-09

Citral is widely used in the beverage, food, and fragrance industries for its characteristic flavor profile. However, it chemically degrades over time in aqueous solutions due to an acid-catalyzed reaction, which leads to loss of desirable flavor notes and formation of off-flavor notes. The objective of this research was to examine the impact of organic phase composition [triacetin and medium-chain triacylglycerols (MCT)] on the oil-water partitioning and chemical degradation of citral in oil-in-water emulsions. MCT was present as emulsion droplets (d approximately 900 nm), whereas triacetin was present as microemulsion droplets (d approximately 10 nm). In the absence of organic phase, the rate of citral degradation increased as the aqueous phase pH was reduced from 7 to 3. The percentage of citral within the aqueous phase increased with increasing triacetin concentration at both pH 3 and 7, which was attributed to a reduction in MCT droplet concentration. There was no significant change in the particle size distribution of the emulsions during storage, independent of triacetin concentration and pH, which indicated that they were physically stable. Both 5 wt % MCT as emulsion droplets and 5 wt % triacetin as microemulsion droplets were able to appreciably slow citral degradation at pH 3. These results may have important implications for understanding and improving the chemical stability of citral in beverage emulsions.

Atomic insights into nanoparticle formation of hydroxyfluorinated anatase featuring titanium vacancies

DOE PAGES

Li, Wei; Body, Monique; Legein, Christophe; ...

2016-06-28

Anatase TiO 2 with exposed highly reactive (001) surface is commonly prepared using solution-based synthesis in the presence of a fluorinating agent acting as a structure directing agent. Here, the solvothermal reaction of titanium tetraisopropoxide in the presence of aqueous HF has resulted in the stabilization of an oxyhydroxyfluorinated anatase phase featuring cationic vacancies. In the present work, we have studied its formation mechanism, revealing a solid-state transformation of a highly defective anatase phase having a hydroxyfluoride composition that subsequently evolves through an oxolation reaction into an oxyhydroxyfluoride phase. Importantly, this work confirms that titanium alkoxide precursors can react withmore » HF via a fluorolysis process yielding fluorinated molecular precursors, which further condense to produce new composition and structural features deviating from a well ordered anatase network.« less

Thickening compositions containing xanthomonas gum and hydroxyalkyl ether of guar gum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jordan, W.A.

1973-07-24

Natural and synthetic gums have been used as thickeners for foods, coatings, paints, dyes, explosive slurries, oil-well fluids, and many other applications. Thickening compositions are described which consist of xanthomonas gum and hydroxyalkyl ether of guar gum and are suitable for use in explosive slurries. Aqueous sols of xanthomonas gum are plastic in nature and exhibit higher gel strengths than sols of other gums. Aqueous sols of hydroxyalkyl ether of guar are almost Newtonian and exhibit little or no gel strength. Aqueous sols of the thickening compositions of the present invention are plastic in character. At certain concentrations of themore » thickening compositions in aqueous sols, the sols have higher gel strengths than can be obtained from xanthomonas gum alone. At certain concentrations, the aqueous sols containing the thickening compositions exhibit greater viscosity differentials than do sols containing xanthomonas gum alone. In addition, the aqueous sols exhibit a greater drop in viscosity as the thickening composition concentration is reduced than do aqueous sols of xanthomonas gum alone.(5 claims)« less

Hierarchical porous structured zeolite composite for removal of ionic contaminants from waste streams and effective encapsulation of hazardous waste.

PubMed

Al-Jubouri, Sama M; Curry, Nicholas A; Holmes, Stuart M

2016-12-15

A hierarchical structured composite made from clinoptilolite supported on date stones carbon is synthesized using two techniques. The composites are manufactured by fixing a natural zeolite (clinoptilolite) to the porous surface of date stones carbon or by direct hydrothermal synthesis on to the surface to provide a supported high surface area ion-exchange material for metal ion removal from aqueous streams. The fixing of the clinoptilolite is achieved using sucrose and citric acid as a binder. The composites and pure clinoptilolite were compared to test the efficacy for the removal of Sr 2+ ions from an aqueous phase. The encapsulation of the Sr 2+ using either vitrification or a geo-polymer addition was tested to ensure that the hazardous waste can be made safe for disposal. The hierarchical structured composites were shown to achieve a higher ion exchange capacity per gram of zeolite than the pure clinoptilolite (65mg/g for the pure natural clinoptilolite and 72mg/g for the pure synthesized clinoptilolite) with the synthesized composite (160mg/g) having higher capacity than the natural clinoptilolite composite (95mg/g). The rate at which the equilibria were established followed the same trend showing the composite structure facilitates diffusion to the ion-exchange sites in the zeolite. Copyright © 2016 Elsevier B.V. All rights reserved.

Extension of the CAPRAM mechanism with the improved mechanism generator GECKO-A

NASA Astrophysics Data System (ADS)

Bräuer, Peter; Mouchel-Vallon, Camille; Tilgner, Andreas; Wolke, Ralf; Aumont, Bernard; Herrmann, Hartmut

2013-04-01

Organic compounds are an ubiquitous constituent of the tropospheric multiphase system. With either biogenic or anthropogenic sources, they have a major influence on the atmospheric multiphase system and thus have become a main research topic within the last decades. Modelling can provide a useful tool to explore the tropospheric multiphase chemistry. While in the gas phase several comprehensive near-explicit mechanisms exist, in the aqueous phase those mechanisms are very limited. The current study aims to advance the currently most comprehensive aqueous phase mechanism CAPRAM 3.0 by means of automated mechanism construction. Therefore, the mechanism generator GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere; see Aumont et al., 2005) has been advanced to the aqueous phase. A protocol has been designed for automated mechanism construction based on reviewed experimental data and evaluated prediction methods. The generator is able to describe the oxidation of aliphatic organic compounds by OH and NO3. For the mechanism construction, mainly structure-activity relationships are used, which are completed by Evans-Polanyi-type correlations and further suitable estimates. GECKO-A has been used to create new CAPRAM versions, where branching ratios are introduced and new chemical subsystems with species with up to 4 carbon atoms are added. The currently most comprehensive version, CAPRAM 3.7, includes about 2000 aqueous phase species and more than 3300 reactions in the aqueous phase. Box model studies have been performed using a meteorological scenario with non-permanent clouds. Besides the investigation of the concentration-time profiles, detailed time-resolved flux analyses have been performed. Several aqueous phase subsystems have been investigated, such as the formation of oxidised mono- and diacids in the aqueous phase, as well as interactions to inorganic cycles and the influence on the gas phase chemistry and composition. Results have been compared to results of previous versions and show a significant improvement in the new mechanism versions, when comparing the modelled data to field data from literature. For example, in CAPRAM 3.7 there is a malonic acid production of about 80 ng m-3 compared to a few ng m-3 in CAPRAM 3.0. The results in CAPRAM 3.7 confirm recent measurements by Bao et al. (2012), who measure up to 137 ng m-3. Moreover, several attempts have been undertaken to validate the mechanisms created by GECKO-A with own field experiments, such as the HCCT-2010 campaign and chamber experiments in the LEAK chamber. References Aumont, B., Szopa, S., Madronich, S.: Modelling the evolution of organic carbon during its gas-phase tropospheric oxidation: development of an explicit model based on a self generating approach. Atmos. Chem. Phys., 5, 2497-2517 (2005). Bao, L., Matsumoto, M., Kubota, T., Sekiguchi, K., Wang, Q., Sakamoto, K.: Gas/particle partitioning of low-molecular-weight dicarboxylic acids at a suburban site in Saitama, Japan. Atmos. Env., 47, 546 - 553 (2012).

Effects of elevated temperature and mobile phase composition on a novel C18 silica column.

PubMed

Lippert, J Andreas; Johnson, Todd M; Lloyd, Jarem B; Smith, Jared P; Johnson, Bryce T; Furlow, Jason; Proctor, Angela; Marin, Stephanie J

2007-05-01

A novel polydentate C18 silica column was evaluated at an elevated temperature under acidic, basic, and neutral mobile phase conditions using ACN and methanol as the mobile phase organic modifier. The temperature range was 40-200 degrees C. The mobile phase compositions were from 0 to 80% organic-aqueous v/v and the mobile phase pH levels were between 2 and 12. The maximum operating temperature of the column was affected by the amount and type of organic modifier used in the mobile phase. Under neutral conditions, the column showed good column thermal stability at temperatures ranging between 120 and 200 degrees C in methanol-water and ACN-water solvent systems. At pH 2 and 3, the column performed well up to about 160 degrees C at two fixed ACN-buffer compositions. Under basic conditions at elevated temperatures, the column material deteriorated more quickly, but still remained stable up to 100 degrees C at pH 9 and 60 degrees C at pH 10. The results of this study indicate that this novel C18 silica-based column represents a significant advancement in RPLC column technology with enhanced thermal and pH stability when compared to traditional bonded phase silica columns.

Organic-Inorganic Composites Toward Biomaterial Application.

PubMed

Miyazaki, Toshiki; Sugawara-Narutaki, Ayae; Ohtsuki, Chikara

2015-01-01

Bioactive ceramics are known to exhibit specific biological affinities and are able to show direct integration with surrounding bone when implanted in bony defects. However, their inadequate mechanical properties, such as low fracture toughness and high Young's modulus in comparison to natural bone, limit their clinical application. Bone is a kind of organic-inorganic composite where apatite nanocrystals are precipitated onto collagen fibre networks. Thus, one way to address these problems is to mimic the natural composition of bone by using bioactive ceramics via material designs based on organic-inorganic composites. In this chapter, the current research on the development of the various organic-inorganic composites designed for biomaterial applications has been reviewed. Various compounds such as calcium phosphate, calcium sulphate and calcium carbonate can be used for the inorganic phases to design composites with the desired mechanical and biological properties of bone. Not only classical mechanical mixing but also coating of the inorganic phase in aqueous conditions is available for the fabrication of such composites. Organic modifications using various polymers enable the control of the crystalline structure of the calcium carbonate in the composites. These approaches on the fabrication of organic-inorganic composites provide important options for biomedical materials with novel functions. © 2015 S. Karger AG, Basel.

Enhancing the biocompatibility of microfluidics-assisted fabrication of cell-laden microgels with channel geometry.

PubMed

Kim, Suntae; Oh, Jonghyun; Cha, Chaenyung

2016-11-01

Microfluidic flow-focusing devices (FFD) are widely used to generate monodisperse droplets and microgels with controllable size, shape and composition for various biomedical applications. However, highly inconsistent and often low viability of cells encapsulated within the microgels prepared via microfluidic FFD has been a major concern, and yet this aspect has not been systematically explored. In this study, we demonstrate that the biocompatibility of microfluidic FFD to fabricate cell-laden microgels can be significantly enhanced by controlling the channel geometry. When a single emulsion ("single") microfluidic FFD is used to fabricate cell-laden microgels, there is a significant decrease and batch-to-batch variability in the cell viability, regardless of their size and composition. It is determined that during droplet generation, some of the cells are exposed to the oil phase which is shown to have a cytotoxic effect. Therefore, a microfluidic device with a sequential ('double') flow-focusing channels is employed instead, in which a secondary aqueous phase containing cells enters the primary aqueous phase, so the cells' exposure to the oil phase is minimized by directing them to the center of droplets. This microfluidic channel geometry significantly enhances the biocompatibility of cell-laden microgels, while maintaining the benefits of a typical microfluidic process. This study therefore provides a simple and yet highly effective strategy to improve the biocompatibility of microfluidic fabrication of cell-laden microgels. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative characterization of the aqueous fraction from hydrothermal liquefaction of algae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddi, Balakrishna; Panisko, Ellen; Wietsma, Thomas

Aqueous streams generated from hydrothermal liquefaction contain approximately 30% of the total carbon present from the algal feed. Hence, this aqueous carbon must be utilized to produce liquid fuels and/or specialty chemicals for economic sustainability of hydrothermal liquefaction on industrial scale. In this study, aqueous fractions produced from the hydrothermal liquefaction of fresh water and saline water algal cultures were analyzed using a wide variety of analytical instruments to determine their compositional characteristics. This study will also inform researchers designing catalysts for down-stream processing such as high-pressure catalytic conversion of organics in aqueous phase, catalytic hydrothermal gasification, and biological conversions.more » Organic chemical compounds present in all eight aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compounds include organic acids, nitrogen compounds and aldehydes/ketones. Conventional gas chromatography and liquid chromatography methods were utilized to quantify the identified compounds. Inorganic species in the aqueous stream of hydrothermal liquefaction of algae were identified using ion chromatography and inductively coupled plasma optical emission spectrometer. The concentrations of organic chemical compounds and inorganic species are reported. The amount quantified carbon ranged from 45 to 72 % of total carbon in the aqueous fractions.« less

Coupled enzyme reactions performed in heterogeneous reaction media: experiments and modeling for glucose oxidase and horseradish peroxidase in a PEG/citrate aqueous two-phase system.

PubMed

Aumiller, William M; Davis, Bradley W; Hashemian, Negar; Maranas, Costas; Armaou, Antonios; Keating, Christine D

2014-03-06

The intracellular environment in which biological reactions occur is crowded with macromolecules and subdivided into microenvironments that differ in both physical properties and chemical composition. The work described here combines experimental and computational model systems to help understand the consequences of this heterogeneous reaction media on the outcome of coupled enzyme reactions. Our experimental model system for solution heterogeneity is a biphasic polyethylene glycol (PEG)/sodium citrate aqueous mixture that provides coexisting PEG-rich and citrate-rich phases. Reaction kinetics for the coupled enzyme reaction between glucose oxidase (GOX) and horseradish peroxidase (HRP) were measured in the PEG/citrate aqueous two-phase system (ATPS). Enzyme kinetics differed between the two phases, particularly for the HRP. Both enzymes, as well as the substrates glucose and H2O2, partitioned to the citrate-rich phase; however, the Amplex Red substrate necessary to complete the sequential reaction partitioned strongly to the PEG-rich phase. Reactions in ATPS were quantitatively described by a mathematical model that incorporated measured partitioning and kinetic parameters. The model was then extended to new reaction conditions, i.e., higher enzyme concentration. Both experimental and computational results suggest mass transfer across the interface is vital to maintain the observed rate of product formation, which may be a means of metabolic regulation in vivo. Although outcomes for a specific system will depend on the particulars of the enzyme reactions and the microenvironments, this work demonstrates how coupled enzymatic reactions in complex, heterogeneous media can be understood in terms of a mathematical model.

The effect of dissolution of volcanic glass on the water chemistry in a tuffaceous aquifer, Rainier Mesa, Nevada

USGS Publications Warehouse

White, Art F.; Claassen, H.C.; Benson, Larry V.

1980-01-01

Geochemistry of ground water associated with the Tertiary tuffs within Rainier Mesa, southern Nevada, was investigated to determine the relative importance of glass dissolution in controlling water chemistry. Water samples were obtained both from interstitial pores in core sections and from free-flowing fractures. Cation com- positions showed that calcium and magnesium decreased as a function of depth in the mesa, as sodium increased. The maximum effect occurs within alteration zones containing clinoptilolite and montmorillonite, suggesting these minerals effectively remove bivalent cations from the system. Comparisons are made between compositions of ground waters found within Rainier Mesa that apparently have not reacted with secondary minerals and compositions of waters produced by experimental dissolution of vitric and crystalline tufts which comprise the principal aquifers in the area. The two tuff phases have the same bulk chemistry but produce aqueous solutions of different chemistry. Rapid parabolic dissolution of sodium and silica from, and the retention of, potassium within the vitric phase verify previous predictions concerning water compositions associated with vitric volcanic rocks. Parabolic dissolution of the crystalline phase results in solutions high in calcium and magnesium and low in silica. Extrapolation of the parabolic dissolution mechanism for the vitric tuff to long times successfully reproduces, at com- parable pH, cation ratios existing in Rainier Mesa ground water. Comparison of mass- transfer rates of the vitric and crystalline tuffs indicates that the apparent higher glass-surface to aqueous-volume ratio associated with the vitric rocks may account for dominance of the glass reaction.

Fe-Ni metal and sulfide minerals in CM chondrites: An indicator for thermal history

USGS Publications Warehouse

Kimura, M.; Grossman, J.N.; Weisberg, M.K.

2011-01-01

CM chondrites were subjected to aqueous alteration and, in some cases, to secondary metamorphic heating. The effects of these processes vary widely, and have mainly been documented in silicate phases. Herein, we report the characteristic features of Fe-Ni metal and sulfide phases in 13 CM and 2 CM-related chondrites to explore the thermal history of these chondrites. The texture and compositional distribution of the metal in CM are different from those in unequilibrated ordinary and CO chondrites, but most have similarities to those in highly primitive chondrites, such as CH, CR, and Acfer 094. We classified the CM samples into three categories based on metal composition and sulfide texture. Fe-Ni metal in category A is kamacite to martensite. Category B is characterized by pyrrhotite grains always containing blebs or lamellae of pentlandite. Opaque mineral assemblages of category C are typically kamacite, Ni-Co-rich metal, and pyrrhotite. These categories are closely related to the degree of secondary heating and are not related to degree of the aqueous alteration. The characteristic features of the opaque minerals can be explained by secondary heating processes after aqueous alteration. Category A CM chondrites are unheated, whereas those in category B experienced small degrees of secondary heating. CMs in category C were subjected to the most severe secondary heating process. Thus, opaque minerals can provide constraints on the thermal history for CM chondrites. ?? The Meteoritical Society, 2011.

SOLVENT EXTRACTION PROCESS

DOEpatents

Jonke, A.A.

1957-10-01

In improved solvent extraction process is described for the extraction of metal values from highly dilute aqueous solutions. The process comprises contacting an aqueous solution with an organic substantially water-immiscible solvent, whereby metal values are taken up by a solvent extract phase; scrubbing the solvent extract phase with an aqueous scrubbing solution; separating an aqueous solution from the scrubbed solvent extract phase; and contacting the scrubbed solvent phase with an aqueous medium whereby the extracted metal values are removed from the solvent phase and taken up by said medium to form a strip solution containing said metal values, the aqueous scrubbing solution being a mixture of strip solution and an aqueous solution which contains mineral acids anions and is free of the metal values. The process is particularly effective for purifying uranium, where one starts with impure aqueous uranyl nitrate, extracts with tributyl phosphate dissolved in carbon tetrachloride, scrubs with aqueous nitric acid and employs water to strip the uranium from the scrubbed organic phase.

How salt lakes affect atmospheric new particle formation: A case study in Western Australia.

PubMed

Kamilli, K A; Ofner, J; Krause, T; Sattler, T; Schmitt-Kopplin, P; Eitenberger, E; Friedbacher, G; Lendl, B; Lohninger, H; Schöler, H F; Held, A

2016-12-15

New particle formation was studied above salt lakes in-situ using a mobile aerosol chamber set up above the salt crust and organic-enriched layers of seven different salt lakes in Western Australia. This unique setup made it possible to explore the influence of salt lake emissions on atmospheric new particle formation, and to identify interactions of aqueous-phase and gas-phase chemistry. New particle formation was typically observed at enhanced air temperatures and enhanced solar irradiance. Volatile organic compounds were released from the salt lake surfaces, probably from a soil layer enriched in organic compounds from decomposed leaf litter, and accumulated in the chamber air. After oxidation of these organic precursor gases, the reaction products contributed to new particle formation with observed growth rates from 2.7 to 25.4nmh -1 . The presence of ferrous and ferric iron and a drop of pH values in the salt lake water just before new particle formation events indicated that organic compounds were also oxidized in the aqueous phase, affecting the new particle formation process in the atmosphere. The contribution of aqueous-phase chemistry to new particle formation is assumed, as a mixture of hundreds of oxidized organic compounds was characterized with several analytical techniques. This chemically diverse composition of the organic aerosol fraction contained sulfur- and nitrogen-containing organic compounds, and halogenated organic compounds. Coarse mode particles were analyzed using electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. Ultra-high resolution mass spectrometry was applied to analyze filter samples. A targeted mass spectral analysis revealed the formation of organosulfates from monoterpene precursors and two known tracers for secondary organic aerosol formation from atmospheric oxidation of 1,8-cineole, which indicates that a complex interplay of aqueous-phase and gas-phase oxidation of monoterpenes contributes to new particle formation in the investigated salt lake environment. Copyright © 2016. Published by Elsevier B.V.

Microfluidic Droplet Dehydration for Concentrating Processes in Biomolecules

NASA Astrophysics Data System (ADS)

Anna, Shelley

2014-03-01

Droplets in microfluidic devices have proven useful as picoliter reactors for biochemical processing operations such as polymerase chain reaction, protein crystallization, and the study of enzyme kinetics. Although droplets are typically considered to be self-contained, constant volume reactors, there can be significant transport between the dispersed and continuous phases depending on solubility and other factors. In the present talk, we show that water droplets trapped within a microfluidic device for tens of hours slowly dehydrate, concentrating the contents encapsulated within. We use this slow dehydration along with control of the initial droplet composition to influence gellation, crystallization, and phase separation processes. By examining these concentrating processes in many trapped drops at once we gain insight into the stochastic nature of the events. In one example, we show that dehydration rate impacts the probability of forming a specific crystal habit in a crystallizing amino acid. In another example, we phase separate a common aqueous two-phase system within droplets and use the ensuing two phases to separate DNA from an initial mixture. We further influence wetting conditions between the two aqueous polymer phases and the continuous oil, promoting complete de-wetting and physical separation of the polymer phases. Thus, controlled dehydration of droplets allows for concentration, separation, and purification of important biomolecules on a chip.

Focused microwave-assisted solvent extraction and HPLC determination of effective constituents in Eucommia ulmodies Oliv. (E. ulmodies).

PubMed

Li, Hui; Chen, Bo; Zhang, Zhaohui; Yao, Shouzhuo

2004-06-17

A new focused microwave-assisted solvent extraction method using water as solvent has been developed for leaching geniposidic and chlorogenic acids from Eucommia ulmodies Oliv. The extraction procedures were optimized using a two indexes orthogonal experimental design and graphical analysis, by varying irradiation time, solvent volume, solvent composition and microwave power. The optimum extraction conditions were obtained: for geniposidic acid, 50% micorwave power, 40s irradiation, and 80% (v/v) aqueous methanol as extraction solvent (20mlg(-1) sample); and for chlorogenic acid, 50% micorwave power, 30s irradiation, and 20% aqueous methanol (20mlg(-1) sample). The composition of the extraction solvent was optimized and can be directly used as the mobile phase in the HPLC separation. Quantification of organic acids was done by HPLC at room temperature using Spherigel C(18) chromatographic column (250 mm x4.6 mm , i.d. 5mum), the methanol:water:acetic acid (20:80:1.0, v/v) mobile phase and UV detection at 240nm. The R.S.D. of the extraction process for geniposidic and chlorogenic acid were 3.8 and 4.1%, respectively.

User's guide to PHREEQC, a computer program for speciation, reaction-path, advective-transport, and inverse geochemical calculations

USGS Publications Warehouse

Parkhurst, D.L.

1995-01-01

PHREEQC is a computer program written in the C pwgranuning language that is designed to perform a wide variety of aqueous geochemical calculations. PHREEQC is based on an ion-association aqueous model and has capabilities for (1) speciation and saturation-index calculations, (2) reaction-path and advective-transport calculations involving specified irreversible reactions, mixing of solutions, mineral and gas equilibria surface-complex-ation reactions, and ion-exchange reactions, and (3) inverse modeling, which finds sets of mineral and gas mole transfers that account for composition differences between waters, within specified compositional uncertainties. PHREEQC is derived from the Fortran program PHREEQE, but it has been completely rewritten in C with the addition many new capabilities. New features include the capabilities to use redox couples to distribute redox elements among their valence states in speciation calculations; to model ion-exchange and surface-compiexation reactions; to model reactions with a fixed-pressure, multicomponent gas phase (that is, a gas bubble); to calculate the mass of water in the aqueous phase during reaction and transport calculations; to keep track of the moles of minerals present in the solid phases and determine antomaticaHy the thermodynamically stable phase assemblage; to simulate advective transport in combination with PHREEQC's reaction-modeling capability; and to make inverse modeling calculations that allow for uncertainties in the analytical data. The user interface is improved through the use of a simplified approach to redox reactions, which includes explicit mole-balance equations for hydrogen and oxygen; the use of a revised input that is modular and completely free format; and the use of mineral names and standard chemical symbolism rather than index numbers. The use of (2 eliminates nearly all limitations on army sizes, including numbers of elements, aqueous species, solutions, phases, and lengths of character strings. A new equation solver that optimizes a set of equalities subject to both equality and inequality constraints is used to determine the thermodynamically stable set of phases in equilibrium with a solution. A more complete Newton-Raphson formulation, master-species switching, and scaling of the algebraic equations reduce the number of failures of the nunmrical method in PHREEQC relative to PHREEQE. This report presents the equations that are the basis for chemical equilibrium and inverse-modeling calculations in PHREEQC, describes the input for the program, and presents twelve examples that demonstrate most of the program's capabilities.

Graphite oxide/β-Ni(OH)2 composites for application in supercapacitors

NASA Astrophysics Data System (ADS)

Singh, Arvinder; Chandra, Amreesh

2013-06-01

Graphite oxide/β-Ni(OH)2 composites have been investigated as electrode material in supercapacitors. Phase formation of electrode material is investigated using diffraction measurements. Particle shape-size studies show deposition of β-Ni(OH)2 nanoparticles on graphite oxide (GO) sheets. Electrochemical performance of GO/β-Ni(OH)2 composite in supercapacitors is discussed based on the analysis of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge studies. Excellent energy density of ˜53 Wh/kg in 1M Na2SO4 aqueous electrolyte is reported at power density of ˜1364W/kg. The significance of results is discussed in the paper.

Distribution of free and antibody-bound peptide hormones in two-phase aqueous polymer systems

PubMed Central

Desbuquois, Bernard; Aurbach, G. D.

1972-01-01

Peptide hormones labelled with radioactive iodine were partitioned into the aqueous two-phase polymer systems developed by Albertsson (1960) and the conditions required for separation of free from antibody-bound hormone have been worked out. Hormones studied included insulin, growth hormone, parathyroid hormone and [arginine]-vasopressin. Free and antibody-bound hormones show different distribution coefficients in a number of systems tested; two systems, the dextran–polyethylene glycol and dextran sulphate–polyethylene glycol system, give optimum separation. Free hormones distribute readily into the upper phase of these systems, whereas hormone–antibody complexes, as well as uncombined antibody, are found almost completely in the lower phase. Various factors including the polymer concentration, the ionic composition of the system, the nature of the hormone and the nature of added serum protein differentially affect the distribution coefficients for free and antibody-bound hormone. These factors can be adequately controlled so as to improve separation. The two-phase partition method has been successfully applied to measure binding of labelled hormone to antibody under standard radioimmunoassay conditions. It exhibits several advantages over the method of equilibration dialysis and can be applied to the study of non-immunological interactions. PMID:4672674

Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical

DOE PAGES

Yu, L.; Smith, J.; Laskin, A.; ...

2014-08-19

Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the reactions of phenol and two methoxy-phenols (syringol and guaiacol) with two major aqueous phase oxidants – the triplet excited states of an aromatic carbonyl ( 3C*) and hydroxyl radical (·OH). We thoroughly characterize the low-volatility species produced from these reactions and interpret their formation mechanisms using aerosol mass spectrometry (AMS), nanospray desorption electrospray ionization mass spectrometry (nano-DESI MS), and ion chromatography (IC). A large number of oxygenated molecules aremore » identified, including oligomers containing up to six monomer units, functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acid anions (e.g., formate, acetate, oxalate, and malate). The average atomic oxygen-to-carbon (O / C) ratios of phenolic aqSOA are in the range of 0.85–1.23, similar to those of low-volatility oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA compositions are overall similar for the same precursor, but the reactions mediated by 3C* are faster than ·OH-mediated reactions and produce more oligomers and hydroxylated species at the point when 50% of the phenol had reacted. Profiles determined using a thermodenuder indicate that the volatility of phenolic aqSOA is influenced by both oligomer content and O / C ratio. In addition, the aqSOA shows enhanced light absorption in the UV-vis region, suggesting that aqueous-phase reactions of phenols are likely an important source of brown carbon in the atmosphere, especially in regions influenced by biomass burning.« less

A Comparative Study of the Adsorption of Methylene Blue onto Synthesized Nanoscale Zero-Valent Iron-Bamboo and Manganese-Bamboo Composites

PubMed Central

Shaibu, Solomon E.; Adekola, Folahan A.; Adegoke, Halimat I.; Ayanda, Olushola S.

2014-01-01

In this study, bamboo impregnated with nanoscale zero-valent iron (nZVI) and nanoscale manganese (nMn) were prepared by the aqueous phase borohydride reduction method and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and PIXE analysis. The synthesized nMn-bamboo and nZVI-bamboo composites were subsequently applied to the sorption of methylene blue (MB) dye from aqueous solution. The adsorption of MB dye was investigated under various experimental conditions such as pH, contact time, initial concentration of MB dye and adsorbent dosage. The results showed that the synthesized nZVI-bamboo composite was more effective than nMn-bamboo composite in terms of higher MB dye adsorption capacity of 322.5 mg/g compared to 263.5 mg/g of nMn-bamboo composite. At a concentration of 140 mg/L MB dye, 0.02 g of nZVI-bamboo and nMn-bamboo composites resulted in 79.6% and 78.3% removal, respectively, at 165 rpm, contact time of 120 min and at a solution pH of 7.6. The equilibrium data was best represented by Freundlich isotherm model and the pseudo-second order kinetic model better explained the kinetic data for both nZVI-bamboo and nMn-bamboo composites. PMID:28788688

Investigation of Tank 241-AW-104 Composite Floating Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meznarich, H. K.; Bolling, S. D.; Lachut, J. S.

Seven grab samples and one field blank were taken from Tank 241-AW-104 (AW-104) on June 2, 2017, and received at 222-S Laboratory on June 5, 2017. A visible layer with brown solids was observed floating on the top of two surface tank waste samples (4AW-17-02 and 4AW 17 02DUP). The floating layer from both samples was collected, composited, and submitted for chemical analyses and solid phase characterization in order to understand the composition of the floating layer. Tributyl phosphate and tridecane were higher in the floating layer than in the aqueous phase. Density in the floating layer was slightly lowermore » than the mean density of all grab samples. Sodium nitrate and sodium carbonate were major components with a trace of gibbsite and very small size agglomerates were present in the solids of the floating layer. The supernate consisted of organics, soluble salt, and particulates.« less

Reinforced Superhydrophobic Coating on Silicone Rubber for Longstanding Anti-Icing Performance in Severe Conditions.

PubMed

Emelyanenko, Alexandre M; Boinovich, Ludmila B; Bezdomnikov, Alexey A; Chulkova, Elizaveta V; Emelyanenko, Kirill A

2017-07-19

We present a simple method for fabricating the superhydrophobic coatings on composite silicone rubber used for electrical outdoor applications. The coating is characterized by contact angles as high as 170° and is mechanically durable in contact with the aqueous phase. We discuss the impact of mechanical durability of the surface texture on the anti-icing performance of the coating on the basis of the experimental data on freezing delay of sessile aqueous droplets. A set of complementary data obtained in laboratory and outdoor experiments on freezing delay time, variation of wettability and practical work of adhesion for supercooled aqueous sessile droplets, impacting behavior of droplets at low negative temperatures, as well as the results of snow and ice accumulation in outdoor experiments indicate the very prospective icephobic properties of the developed coating.

Preparation of ZnS/ZnO core - Shell nanocomposite and its photocatalytic behaviour for dye degradation

NASA Astrophysics Data System (ADS)

Patil, Bharati N.; Acharya, Smita A.

2018-05-01

In the present work ZnS-ZnO core-shell-type composite nanostructures was prepared by hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD) for structural confirmation. Microstructural study by scanning electron microscopy (SEM) exhibit nanoscale dimensions of as-synthesized composite. UV/VIS spectra were recorded for evaluation of photophysical properties. The composite was explored as photocatalysts to study dye degradation using methylene blue in aqueous slurry under irradiation of 663 nm wavelength and congo red under irradiation of 493 nm wavelength. Under the same conditions the photocatalytic activity of the individual phases ZnS and ZnO were also examined, just for sake of comparison. The ZnS-ZnO composite is found to be enhancing the rate of photo degradation of toxic dyes in presence of visible light as compared to ZnS and ZnO individual phases. Thus ZnS based metal sulphide/oxide semiconductor nanocomposites are potential material for Photo-degradation of toxic dyes, and act as good photocatalyst.

Description and Evaluation of Chiral Interactive Sites on Bonded Cyclodextrin Stationary Phases for Liquid Chromatography

NASA Astrophysics Data System (ADS)

Beesley, Thomas E.

Development of chiral separations has been essential to the drug discovery and development process. The solubility requirements for a number of methods and/or the mobile phase requirements for application of certain detection systems have opened up many opportunities for cyclodextrin-based CSPs for liquid chromatography. Even though a few chiral stationary phases cover a wide area of enantioselectivity, they do not meet the entire needs of the industry. Cyclodextrin phases offer some unique mechanisms and opportunities to resolve chiral separation problems especially in the aqueous reversed-phase and non-aqueous polar organic modes. This chapter addresses the need to understand the chiral stationary phase structure, the mechanisms at work, and the role mobile phase composition plays in driving those mechanisms to produce enantioselectivity. In addition, the development of certain derivatives has played an essential part in expanding that basic role for certain chiral separations. What these derivatives contribute in concert with the basic structure is a critical part of the understanding to the effective use of these phases. During this study it was determined that the role of steric hindrance has been vastly underestimated, both to the extent that it has occurred and to its effectiveness for obtaining enantioselectivity. References to the entire 20-year history of the cyclodextrin phase development and application literature up to this current date have been reviewed and incorporated.

2015 Progress Report/July 2016: Iron Oxide Redox Transformation Pathways: The Bulk Electrical Conduction Mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scherer, Michelle M.; Rosso, Kevin M.

Despite decades of research on the reactivity and stable isotope properties of Fe oxides, the ability to describe the redox behavior of Fe oxides in the environment is still quite limited. This is due, in large part, to the analytical and spatial complexities associated with studying microscopic processes at the Fe oxide-water interface. This project had the long-term vision of filling this gap by developing a detailed understanding of the relationship between interfacial ET processes, surface structure and charge, and mineral semiconducting properties. We focused on the Fe(III)-oxides and oxyhydroxides because of their geochemical preponderance, versatility in synthesis of compositionally,more » structurally, and morphologically tailored phases, and because they are amenable to a wide range of surface and bulk properties characterization. In particular, reductive transformation of phases such as hematite (α-Fe 2O 3) and goethite (α-FeOOH) in aqueous solution can serve as excellent model systems for studies of electron conduction processes, as well as provide valuable insights into effect of nanoscale conductive materials on contaminant fate at DOE sites. More specifically, the goal of the Iowa component of this project was to use stable Fe isotope measurements to simultaneously measure isotope specific oxidation states and concentrations of Fe at the hematite-water and goethite-water interface. This work builds on our previous work where we used an innovative combination of 57Fe Mössbauer spectroscopy and high precision isotope ratio measurements (MC-ICP-MS) to probe the dynamics of the reaction of aqueous Fe(II) with goethite. Mössbauer spectroscopy detects 57Fe only among all other Fe isotopes and we have capitalized on this to spectroscopically demonstrate Fe(II)-Fe(III) electron transfer between sorbed Fe(II) and Fe(III) oxides (Handler, et al., 2009; Gorski, et al. 2010; Rosso et al., 2010). By combining the Mössbauer spectroscopy and stable isotopes measurements, we have been able to simultaneously track the oxidation state and isotope concentration of the bulk Fe oxide and aqueous Fe. One of our most compelling findings is that despite the apparent stability of the Fe(II)-goethite system, there is actually a tremendous amount of Fe atom cycling occurring between the aqueous phase and the bulk goethite as indicated by the isotopic composition of both phases approaching the mass balance average (Handler et al., 2009). How such extensive re-crystallization and Fe atom exchange can occur with no significant morphological change is a fascinating question. Based on previous work from PI Rosso’s group showing that a potential gradient across hematite crystal faces leads to conduction through hematite and growth and dissolution at separate crystal faces we proposed that a redox-driven recrystallization could be occurring that would explain the extensive mixing observed with the isotope data. From our previous studies utilizing Mössbauer spectroscopy, we know that sorption of Fe(II) onto goethite results in electron transfer between the sorbed Fe(II) and the structural Fe(III) in goethite. Oxidation of the sorbed Fe(II) produces growth of goethite on goethite (i.e., homoepitaxy), as well as injection of an electron into goethite. It is possible that electron transfer from sorbed Fe(II) occurs across a potential gradient, and that Fe(II) atoms are dissolved at a different location on the goethite surface. These newly-reduced Fe(II) atoms could then dissolve into the aqueous phase, exposing fresh Fe(III) goethite to the aqueous phase. Through a repeated series of these five steps of sorption–electron transfer–crystal growth–conduction– dissolution, a redox-driven conveyor belt, could be established that would allow all of the goethite to be eventually exposed to the aqueous phase and exchanged. This surface-mediated recrystallization process would result in similar Fe isotope distributions in the aqueous phase and goethite particle, as we have observed here. It would also result in a stable aqueous Fe(II) concentration, if there were equal rates of goethite growth and dissolution.« less

High-pressure sapphire cell for phase equilibria measurements of CO2/organic/water systems.

PubMed

Pollet, Pamela; Ethier, Amy L; Senter, James C; Eckert, Charles A; Liotta, Charles L

2014-01-24

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40 °C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure. The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)(1-4). For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion.

High-pressure liquid chromatographic analysis of pramoxine hydrochloride in high lipoid aerosol foam dosage form.

PubMed

Weinberger, R; Mann, B; Posluszny, J

1980-04-01

A rapid and quantitative method for the determination of pramoxine hydrochloride by high-pressure liquid chromatography is presented. The drug is extracted as the salt from a preparation with a high lipoid composition by partitioning it to the aqueous phase of an ether-methanol-water-acetic acid system. The extract is chromatographed on an octadecylsilane bonded packing with a methanol-water-acetic acid-methanesulfonic acid mobile phase. The time required for each separation is approximately 6 min. Analytical recoveries of 100.4 +/- 1.5% were obtained.

Tungstate-based glass-ceramics for the immobilization of radio cesium

NASA Astrophysics Data System (ADS)

Drabarek, Elizabeth; McLeod, Terry I.; Hanna, John V.; Griffith, Christopher S.; Luca, Vittorio

2009-02-01

The preparation of tungstate-containing glass-ceramic composites (GCC) for the potential immobilization of radio cesium has been considered. The GCC materials were prepared by blending two oxide precursor compositions in various proportions. These included a preformed Cs-containing hexagonal tungsten bronze (HTB) phase (Cs 0.3Ti 0.2W 0.8O 3, P6 3/ mcm) and a blend of silica and other oxides. The use of the HTB phase was motivated on the assumption that a HTB-based adsorbent could be used to remove cesium directly from aqueous high level liquid waste feeds. In the absence of the HTB, glass-ceramics were relatively easily prepared from the Cs-containing glass-forming oxide blend. On melting the mixture a relative complex GCC phase assemblage formed. The principal components of this phase assemblage were determined using X-ray powder diffraction, 133Cs MAS-NMR, and cross-sectional SEM and included glass, various zeolites, scheelite (CaWO 4) and a range of other oxide phases and Cs-containing aluminosilicate. Importantly, under no circumstance was cesium partitioned into the glass phase irrespective of whether or not the composition included the preformed Cs-containing HTB compound. For compositions containing the HTB, cesium was partitioned into one of four major phases including zeolite; Cs-silica-tungstate bronze, pollucite (CsAlSi 2O 6), and an aluminosilicate with an Al/Si ratio close to one. The leach resistance of all materials was evaluated and related to the cesium distribution within the GCC phase assemblages. In general, the GCCs prepared from the HTB had superior durability compared with materials not containing tungsten. Indeed the compositions in many cases had leach resistances comparable to the best ceramics or glass materials.

Simultaneous Separation of Manganese, Cobalt, and Nickel by the Organic-Aqueous-Aqueous Three-Phase Solvent Extraction

NASA Astrophysics Data System (ADS)

Shirayama, Sakae; Uda, Tetsuya

2016-04-01

This research outlines an organic-aqueous-aqueous three-phase solvent extraction method and proposes its use in a new metal separation process for the recycling of manganese (Mn), cobalt (Co), and nickel (Ni) from used lithium ion batteries (LIBs). The three-phase system was formed by mixing xylene organic solution, 50 pct polyethylene glycol (PEG) aqueous solution, and 1 mol L-1 sodium sulfate (Na2SO4) aqueous solution. The xylene organic solution contained 2-ethylhexylphosphonic acid (D2EHPA) as an extractant for Mn ion, and the Na2SO4 aqueous solution contained 1 mol L-1 potassium thiocyanate (KSCN) as an extractant for Co ion. Concentrations of the metal ions were varied by dissolving metal sulfates in the Na2SO4 aqueous solution. As a result of the experiments, Mn, Co, and Ni ions were distributed in the xylene organic phase, PEG-rich aqueous phase, and Na2SO4-rich aqueous phase, respectively. The separation was effective when the pH value was around 4. Numerical simulation was also conducted in order to predict the distribution of metal ions after the multi-stage counter-current extractions.

Investigation of fragrance stability used in the formulation of cosmetic and hygienic products using headspace solid-phase microextraction by nanostructured materials followed by gas chromatography with mass spectrometry.

PubMed

Masoum, Saeed; Gholami, Ali; Ghaheri, Salehe; Bouveresse, Delphine Jouan-Rimbaud; Cordella, Christophe B Y; Rutledge, Douglas N

2016-07-01

A new composite coating of polypyrrole and sodium lauryl ether sulfate was electrochemically prepared on a stainless-steel wire using cyclic voltammetry. The application and performance of the fiber was evaluated for the headspace solid-phase microextraction of a fragrance in aqueous bleach samples followed by gas chromatography combined with mass spectrometry to assess the fragrance stability in this kind of household cleaning product. To obtain a stable and efficient composite coating, parameters related to the coating process such as scan rate and numbers of cycles were optimized using a central composite design. In addition, the effects of various parameters on the extraction efficiency of the headspace solid-phase microextraction process such as extraction temperature and time, ionic strength, sample volume, and stirring rate were investigated by experimental design methods using Plackett-Burman and Doehlert designs. The optimum values of 53°C and 28 min for sample temperature and time, respectively, were found through response surface methodology. Results show that the combination of polypyrrole and sodium lauryl ether sulfate in a composite form presents desirable opportunities to produce new materials to study fragrance stability by headspace solid-phase microextraction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel aqueous micellar two-phase system composed of surfactant and sorbitol for purification of pectinase enzyme from Psidium guajava and recycling phase components.

PubMed

Amid, Mehrnoush; Murshid, Fara Syazana; Manap, Mohd Yazid; Hussin, Muhaini

2015-01-01

A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme.

Aqueous Alteration on Mars. Chapter 23

NASA Technical Reports Server (NTRS)

Ming, Douglas W.; Morris, Richard V.; Clark, Benton C.

2007-01-01

Aqueous alteration is the change in composition of a rock, produced in response to interactions with H2O-bearing ices, liquids, and vapors by chemical weathering. A variety of mineralogical and geochemical indicators for aqueous alteration on Mars have been identified by a combination of surface and orbital robotic missions, telescopic observations, characterization of Martian meteorites, and laboratory and terrestrial analog studies. Mineralogical indicators for aqueous alteration include goethite (lander), jarosite (lander), kieserite (orbiter), gypsum (orbiter) and other Fe-, Mg-, and Ca-sulfates (landers), halides (meteorites, lander), phyllosilicates (orbiter, meteorites), hematite and nanophase iron oxides (telescopic, orbiter, lander), and Fe-, Mg-, and Ca-carbonates (meteorites). Geochemical indicators (landers only) for aqueous alteration include Mg-, Ca-, and Fe-sulfates, halides, and secondary aluminosilicates such as smectite. Based upon these indicators, several styles of aqueous alteration have been suggested on Mars. Acid-sulfate weathering (e.g., formation of jarosite, gypsum, hematite, and goethite), may occur during (1) the oxidative weathering of ultramafic igneous rocks containing sulfides, (2) sulfuric acid weathering of basaltic materials, and (3) acid fog (i.e., vapors rich in H2SO4) weathering of basaltic or basaltic-derived materials. Near-neutral or alkaline alteration occurs when solutions with pH near or above 7 move through basaltic materials and form phases such as phyllosilicates and carbonates. Very low water:rock ratios appear to have been prominent at most of the sites visited by landed missions because there is very little alteration (leaching) of the original basaltic composition (i.e., the alteration is isochemical or in a closed hydrologic system). Most of the aqueous alteration appears to have occurred early in the history of the planet (3 to 4.5 billion years ago); however, minor aqueous alteration may be occurring at the surface even today (e.g., in thin films of water or by acid fog).

Managing Zirconium Chemistry and Phase Compatibility in Combined Process Separations for Minor Actinide Partitioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wall, Nathalie; Nash, Ken; Martin, Leigh

In response to the NEUP Program Supporting Fuel Cycle R&D Separations and Waste Forms call DEFOA- 0000799, this report describes the results of an R&D project focusing on streamlining separation processes for advanced fuel cycles. An example of such a process relevant to the U.S. DOE FCR&D program would be one combining the functions of the TRUEX process for partitioning of lanthanides and minor actinides from PUREX(UREX) raffinates with that of the TALSPEAK process for separating transplutonium actinides from fission product lanthanides. A fully-developed PUREX(UREX)/TRUEX/TALSPEAK suite would generate actinides as product(s) for reuse (or transmutation) and fission products as waste.more » As standalone, consecutive unit-operations, TRUEX and TALSPEAK employ different extractant solutions (solvating (CMPO, octyl(phenyl)-N,Ndiisobutylcarbamoylmethylphosphine oxide) vs. cation exchanging (HDEHP, di-2(ethyl)hexylphosphoric acid) extractants), and distinct aqueous phases (2-4 M HNO 3 vs. concentrated pH 3.5 carboxylic acid buffers containing actinide selective chelating agents). The separate processes may also operate with different phase transfer kinetic constraints. Experience teaches (and it has been demonstrated at the lab scale) that, with proper control, multiple process separation systems can operate successfully. However, it is also recognized that considerable economies of scale could be achieved if multiple operations could be merged into a single process based on a combined extractant solvent. The task of accountability of nuclear materials through the process(es) also becomes more robust with fewer steps, providing that the processes can be accurately modeled. Work is underway in the U.S. and Europe on developing several new options for combined processes (TRUSPEAK, ALSEP, SANEX, GANEX, ExAm are examples). There are unique challenges associated with the operation of such processes, some relating to organic phase chemistry, others arising from the variable composition of the aqueous medium. This project targets in particular two problematic issues in designing combined process systems: managing the chemistry of challenging aqueous species (like Zr 4+) and optimizing the composition and properties of combined extractant organic phases.« less

[Intersection point rule for the retention value with mobile phase composition and boiling point of the homologues and chlorobenzenes in soil leaching column chromatography].

PubMed

Xu, F; Liang, X; Lin, B; Su, F

1999-03-01

Based on the linear retention equation of the logarithm of the capacity factor (logk') vs. the methanol volume fraction (psi) of aqueous binary mobile phase in soil leaching column chromatography, the intersection point rule for the logk' of homologues and weak polar chlorobenzenes, with psi, as well as with boiling point, has been derived due to existence of the similar interactions among solutes of the same series, stationary phase (soil) and eluent (methanol-water). These rules were testified by experimental data of homologues (n-alkylbenzenes, methylbenzenes) and weak polar chlorobenzenes.

Superior lithium-ion insertion/extraction properties of a novel LiFePO4/C/graphene material used as a cathode in aqueous solution.

PubMed

Duan, Wenyuan; Zhao, Mingshu; Shen, Junfang; Zhao, Suixin; Song, Xiaoping

2017-09-28

Herein, olivine LiFePO 4 covered with graphene and carbon layers is prepared via a sol-gel method, followed by calcination, and the resultant composite is used as a cathode material in aqueous rechargeable lithium-ion batteries (ARLBs). The phase structure and morphology of the composite are characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and specific surface area analysis (BET). The ARLB system is fabricated using LiFePO 4 /C/graphene as the cathode and a zinc anode in 1 mol L -1 ZnSO 4 ·7H 2 O and saturated LiNO 3 aqueous solution without dissolved oxygen, which delivers a capacity of 153 mA h g -1 at 0.5C rate. Even at a 50C rate, it maintains a capacity of 95 mA h g -1 after 200 cycles. The excellent rate capabilities show that this cathode material exhibits good electrochemical performance and this novel ARLB has great potential in the fields of energy storage and high power sources.

Solubilisation of poorly water-soluble drugs during in vitro lipolysis of medium- and long-chain triacylglycerols.

PubMed

Christensen, Janne Ørskov; Schultz, Kirsten; Mollgaard, Birgitte; Kristensen, Henning Gjelstrup; Mullertz, Anette

2004-11-01

The partitioning of poorly soluble drugs into an aqueous micellar phase was exploited using an in vitro lipid digestion model, simulating the events taking place during digestion of acylglycerols in the duodenum. The aqueous micellar phase was isolated after ultracentrifugation of samples obtained at different degrees of triacylglycerol hydrolysis. Flupentixol, 1'-[4-[1-(4-fluorophenyl)-1-H-indol-3-yl]-1-butyl]spiro[iso-benzofuran-1(3H), 4' piperidine] (LU 28-179) and probucol were studied. The effect of the alkyl chain length of the triacylglycerol was studied using a medium-chain triacylglycerol (MCT) and a long-chain triacylglycerol (LCT), respectively. In general, an oil solution was used as the lipid source in the model. Samples were analysed in regard to micellar size, lipid composition and drug concentration. During lipolysis, the content of lipolytic products in the aqueous micellar phase increased. The micellar size (R(H) approximately 3 nm) only increased when long-chain lipolytic products were incorporated in the mixed micelles (R(H) approximately 7.8 nm). Flupentixol was quickly transferred to the mixed micelles due to high solubility in this phase (100% released). A tendency towards higher solubilisation of LU 28-179, when it was administered in the LCT (approximately 24% released) compared to when it was administered in the MCT (approximately 15% released) at 70% hydrolysis, and a lagphase was observed. There was no difference in the solubilisation of probucol using MCT or LCT ( approximately 20% released), respectively. Differences in the physicochemical properties of the drugs resulted in differences in their distribution between the phases arising during lipolysis.

Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

Treesearch

K. Heckman; A.S. Grandy; X. Gao; M. Keiluweit; K. Wickings; K. Carpenter; J. Chorover; C. Rasmussen

2013-01-01

Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering...

A composite numerical model for assessing subsurface transport of oily wastes and chemical constituents

NASA Astrophysics Data System (ADS)

Panday, S.; Wu, Y. S.; Huyakorn, P. S.; Wade, S. C.; Saleem, Z. A.

1997-02-01

Subsurface fate and transport models are utilized to predict concentrations of chemicals leaching from wastes into downgradient receptor wells. The contaminant concentrations in groundwater provide a measure of the risk to human health and the environment. The level of potential risk is currently used by the U.S. Environmental Protection Agency to determine whether management of the wastes should conform to hazardous waste management standards. It is important that the transport and fate of contaminants is simulated realistically. Most models in common use are inappropriate for simulating the migration of wastes containing significant fractions of nonaqueous-phase liquids (NAPLs). The migration of NAPL and its dissolved constituents may not be reliably predicted using conventional aqueous-phase transport simulations. To overcome this deficiency, an efficient and robust regulatory assessment model incorporating multiphase flow and transport in the unsaturated and saturated zones of the subsurface environment has been developed. The proposed composite model takes into account all of the major transport processes including infiltration and ambient flow of NAPL, entrapment of residual NAPL, adsorption, volatilization, degradation, dissolution of chemical constituents, and transport by advection and hydrodynamic dispersion. Conceptually, the subsurface is treated as a composite unsaturated zone-saturated zone system. The composite simulator consists of three major interconnected computational modules representing the following components of the migration pathway: (1) vertical multiphase flow and transport in the unsaturated zone; (2) areal movement of the free-product lens in the saturated zone with vertical equilibrium; and (3) three-dimensional aqueous-phase transport of dissolved chemicals in ambient groundwater. Such a composite model configuration promotes computational efficiency and robustness (desirable for regulatory assessment applications). Two examples are presented to demonstrate the model verification and a site application. Simulation results obtained using the composite modeling approach are compared with a rigorous numerical solution and field observations of crude oil saturations and plume concentrations of total dissolved organic carbon at a spill site in Minnesota, U.S.A. These comparisons demonstrate the ability of the present model to provide realistic depiction of field-scale situations.

Evolution of supercritical fluid in deeply subducted continental crust: a case study of composite granite-quartz veins in the Sulu belt, China

NASA Astrophysics Data System (ADS)

Wang, S.; Wang, L.; Brown, M.

2016-12-01

Although fluid plays a key role in element transport and rock strength during subduction to and exhumation from ultrahigh pressure (UHP) metamorphic conditions, the source of supercritical fluid at P above the second critical endpoints (SCE) and the subsequent evolution are not well constrained. To provide insight into the evolution of supercritical fluid in continental subduction zones, we undertook an integrated study of composite granite-quartz veins in retrogressed and migmatitic UHP eclogite at General's Hill, N of Qingdao, in the central Sulu belt. The composite veins are irregularly distributed in the eclogite, which occurs as blocks within gneiss. The granite component is enriched in large ion lithophile elements and light rare earth elements but depleted in high field strength elements and heavy rare earth elements, indicating crystallization from a melt phase of crustal origin. Additionally, the granite contains high modal phengite (22-30 vol%) and clinozoisite/epidote (3-10 vol%), implying precipitation from a H2O-rich silicate melt. By contrast, the quartz component is dominated by SiO2 (99.10 wt%), and contains low total rare earth elements (ΣREE = 0.46 ppm), indicating precipitation from an aqueous fluid. The crystallization age of the composite veins is 221 ± 2 Ma, which is younger than the UHP metamorphism in the Sulu belt at ca 230 Ma, consistent with formation during exhumation. Initial 176Hf/177Hf ratios and δ18O values of metamorphic zircons from the composite veins, and Sr-Nd isotope compositions of the granites all lie between values for eclogite and gneiss, indicating a mixed source. Accordingly, we propose that a supercritical fluid generated from the gneiss and the included blocks of eclogite at P-T conditions above the SCE for both compositions became trapped in the eclogite during exhumation. At P below the SCE for the hydrous granite system, the mixed supercritical fluid separated into immiscible aqueous melt and aqueous fluid and crystallized as the composite veins. Thus, these vein systems provide information critical to understanding the evolution of supercritical fluid during exhumation and the partitioning of elements between hydrous granite and aqueous fluid. These data inform our understanding of crust-mantle interactions in continental subduction zones.

Stable isotope (C, O) and monovalent cation fractionation upon synthesis of carbonate-bearing hydroxyl apatite (CHAP) via calcite transformation

NASA Astrophysics Data System (ADS)

Böttcher, Michael E.; Schmiedinger, Iris; Wacker, Ulrike; Conrad, Anika C.; Grathoff, Georg; Schmidt, Burkhard; Bahlo, Rainer; Gehlken, Peer-L.; Fiebig, Jens

2016-04-01

Carbonate-bearing hydroxyl-apatite (CHAP) is of fundamental and applied interest to the (bio)geochemical, paleontological, medical and material science communities, since it forms the basic mineral phase in human and animal teeth and bones. In addition, it is found in non-biogenic phosphate deposits. The stable isotope and foreign element composition of biogenic CHAP is widely used to estimate the formation conditions. This requires careful experimental calibration under well-defined boundary conditions. Within the DFG project EXCALIBOR, synthesis of carbonate-bearing hydroxyapatite was conducted via the transformation of synthetic calcite powder in aqueous solution as a function of time, pH, and temperature using batch-type experiments. The aqueous solution was analyzed for the carbon isotope composition of dissolved inorganic carbonate (gas irmMS), the oxygen isotope composition of water (LCRDS), and the cationic composition. The solid was characterized by powder X-ray diffraction, micro Raman and FTIR spectroscopy, SEM-EDX, elemental analysis (EA, ICP-OES) and gas irmMS. Temperature was found to significantly impact the transformation rate of calcite to CHAP. Upon complete transformation, CHAP was found to contain up to 5% dwt carbonate, depending on the solution composition (e.g., pH), both incorporated on the A and B type position of the crystal lattice. The oxygen isotope fractionation between water and CHAP decreased with increasing temperature with a tentative slope shallower than those reported in the literature for apatite, calcite or aragonite. In addition, the presence of dissolved NH4+, K+ or Na+ in aqueous solution led to partial incorporation into the CHAP lattice. How these distortions of the crystal lattice may impact stable isotope discrimination is subject of future investigations.

Mineralogy and petrology of comet 81P/wild 2 nucleus samples

USGS Publications Warehouse

Zolensky, M.E.; Zega, T.J.; Yano, H.; Wirick, S.; Westphal, A.J.; Weisberg, M.K.; Weber, I.; Warren, J.L.; Velbel, M.A.; Tsuchiyama, A.; Tsou, P.; Toppani, A.; Tomioka, N.; Tomeoka, K.; Teslich, N.; Taheri, M.; Susini, J.; Stroud, R.; Stephan, T.; Stadermann, F.J.; Snead, C.J.; Simon, S.B.; Simionovici, A.; See, T.H.; Robert, F.; Rietmeijer, F.J.M.; Rao, W.; Perronnet, M.C.; Papanastassiou, D.A.; Okudaira, K.; Ohsumi, K.; Ohnishi, I.; Nakamura-Messenger, K.; Nakamura, T.; Mostefaoui, S.; Mikouchi, T.; Meibom, A.; Matrajt, G.; Marcus, M.A.; Leroux, H.; Lemelle, L.; Le, L.; Lanzirotti, A.; Langenhorst, F.; Krot, A.N.; Keller, L.P.; Kearsley, A.T.; Joswiak, D.; Jacob, D.; Ishii, H.; Harvey, R.; Hagiya, K.; Grossman, L.; Grossman, J.H.; Graham, G.A.; Gounalle, M.; Gillet, P.; Genge, M.J.; Flynn, G.; Ferroir, T.; Fallon, S.; Ebel, D.S.; Dai, Z.R.; Cordier, P.; Clark, B.; Chi, M.; Butterworth, Anna L.; Brownlee, D.E.; Bridges, J.C.; Brennan, S.; Brearley, A.; Bradley, J.P.; Bleuet, P.; Bland, P.A.; Bastien, R.

2006-01-01

The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.

Zinc-based electrolyte compositions, and related electrochemical processes and articles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kniajanski, Sergei; Soloveichik, Grigorii Lev

An aqueous electrolyte composition is described, including a zinc salt based on zinc acetate or zinc glocolate. The saturation concentration of zinc in the electrolyte composition is in the range of about 2.5M to about 3.5M. The composition also contains at least one salt of a monovalent cation. The molar ratio of zinc to the monovalent cation is about 1:2. An aqueous zinc electroplating bath, containing the aqueous electrolyte composition, is also disclosed, along with a method for the electrochemical deposition of zinc onto a substrate surface, using the electroplating bath. Related flow batteries are also described, including a catholyte,more » as well as an anolyte based on the aqueous electrolyte composition, with a membrane between the catholyte and the anolyte.« less

Direct Observations of Isoprene Secondary Organic Aerosol Formation in Ambient Cloud Droplets

NASA Astrophysics Data System (ADS)

Zelenyuk, A.; Bell, D.; Thornton, J. A.; Fast, J. D.; Shrivastava, M. B.; Berg, L. K.; Imre, D. G.; Mei, F.; Shilling, J.; Suski, K. J.; Liu, J.; Tomlinson, J. M.; Wang, J.

2017-12-01

Multiphase chemistry of isoprene photooxidation products has been shown to be one of the major sources of secondary organic aerosol (SOA) in the atmosphere. A number of recent studies indicate that aqueous aerosol phase provides a medium for reactive uptake of isoprene photooxidation products, and in particular, isomeric isoprene epoxydiols (IEPOX), with reaction rates and yields being dependent on aerosol acidity, water content, sulfate concentration, and organic coatings. However, very few studies focused on chemistry occurring within actual cloud droplets. We will present data acquired during recent Holistic Interactions of Shallow Clouds, Aerosols, and Land Ecosystems (HI-SCALE) Campaign, which provide direct evidence for IEPOX-SOA formation in cloud droplets. Single particle mass spectrometer, miniSPLAT, and a high-resolution, time-of-flight aerosol mass spectrometer were used to characterize the composition of aerosol particles and cloud droplet residuals, while a high-resolution, time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) was used to characterize gas-phase compounds. We find that the composition of cloud droplet residuals was markedly different than that of aerosol particles sampled outside the cloud. Cloud droplet residuals were comprised of individual particles with high relative fractions of sulfate and nitrate and significant fraction of particles with mass spectra that are nearly identical to those of laboratory-generated IEPOX-SOA particles. The observed cloud-induced formation of IEPOX-SOA was accompanied by simultaneous decrease in measured concentrations of IEPOX and other gas-phase isoprene photooxidation products. Ultimately, the combined cloud, aerosol, and gas-phase measurements conducted during HI-SCALE will be used to develop and evaluate model treatments of aqueous-phase isoprene SOA formation.

Cation Exchange in the Presence of Oil in Porous Media

PubMed Central

2017-01-01

Cation exchange is an interfacial process during which cations on a clay surface are replaced by other cations. This study investigates the effect of oil type and composition on cation exchange on rock surfaces, relevant for a variety of oil-recovery processes. We perform experiments in which brine with a different composition than that of the in situ brine is injected into cores with and without remaining oil saturation. The cation-exchange capacity (CEC) of the rocks was calculated using PHREEQC software (coupled to a multipurpose transport simulator) with the ionic composition of the effluent histories as input parameters. We observe that in the presence of crude oil, ion exchange is a kinetically controlled process and its rate depends on residence time of the oil in the pore, the temperature, and kinetic rate of adsorption of the polar groups on the rock surface. The cation-exchange process occurs in two stages during two phase flow in porous media. Initially, the charged sites of the internal surface of the clays establish a new equilibrium by exchanging cations with the aqueous phase. At later stages, the components of the aqueous and oleic phases compete for the charged sites on the external surface or edges of the clays. When there is sufficient time for crude oil to interact with the rock (i.e., when the core is aged with crude oil), a fraction of the charged sites are neutralized by the charged components stemming from crude oil. Moreover, the positively charged calcite and dolomite surfaces (at the prevailing pH environment of our experiments) are covered with the negatively charged components of the crude oil and therefore less mineral dissolution takes place when oil is present in porous media. PMID:28580442

Up-scaling mineral-aqueous interfacial processes that govern isotope and trace element partitioning during calcite growth

NASA Astrophysics Data System (ADS)

Lammers, L. N.

2014-12-01

The dependence of the isotopic and trace element composition of calcium carbonate minerals on growth conditions including temperature, pH, and salinity is widely used to infer paleoclimate conditions. These inferences rely heavily on phenomenological observations of biogenic and inorganic precipitation both in and ex situ, where only limited variability in solution conditions can be explored. Ionic fluxes between the mineral surface and aqueous growth solution govern the net uptake of both stoichiometric and trace species during calcification, so developing a mechanistic understanding of the reactions governing these fluxes is critical to refine existing proxies and to develop new ones. The micro-scale mechanisms of calcite precipitation from aqueous solution have been extensively studied, and net ionic uptake post-nucleation is known to occur primarily at monomolecular kink sites along step edges at the mineral surface. In this talk, I will present a theoretical framework that uses the quasi-elementary ion attachment and detachment reactions governing ion uptake at kink sites to simultaneously model bulk mineral growth kinetics and tracer partitioning during calcite precipitation. Several distinct processes occur during ion uptake at kink sites that can influence the distribution of trace species, directly impacting the composition of various carbonate paleoproxies including δ44Ca, δ18O, Sr/Ca and Mg/Ca. The distribution of these trace species will be shown to depend on (1) the relative rates of ion desolvation during attachment to kink sites, (2) the relative rates of bond breaking during detachment from kink sites, and (3) the equilibrium partitioning of trace aqueous species. This model accounts for the impact of solution conditions on net ion fluxes and surface speciation, which in turn controls the population of kink sites available for direct ion exchange with the aqueous phase. The impacts of solution variables including pH, temperature and salinity can be treated independently, which unlike traditional partitioning studies allows the impacts of these parameters to be deconvolved. The type of theoretical framework discussed here can be readily extended to explicitly account for each of the major solution composition variables that are implicated in paleoproxy composition.

Amino acid compositions in heated carbonaceous chondrites and their compound-specific nitrogen isotopic ratios

NASA Astrophysics Data System (ADS)

Chan, Queenie Hoi Shan; Chikaraishi, Yoshito; Takano, Yoshinori; Ogawa, Nanako O.; Ohkouchi, Naohiko

2016-01-01

A novel method has been developed for compound-specific nitrogen isotope compositions with an achiral column which was previously shown to offer high precision for nitrogen isotopic analysis. We applied the method to determine the amino acid contents and stable nitrogen isotopic compositions of individual amino acids from the thermally metamorphosed (above 500 °C) Antarctic carbonaceous chondrites Ivuna-like (CI)1 (or CI-like) Yamato (Y) 980115 and Ornans-like (CO)3.5 Allan Hills (ALH) A77003 with the use of gas chromatography/combustion/isotope ratio mass spectrometry. ALHA77003 was deprived of amino acids due to its extended thermal alteration history. Amino acids were unambiguously identified in Y-980115, and the δ15N values of selected amino acids (glycine +144.8 ‰; α-alanine +121.2 ‰) are clearly extraterrestrial. Y-980115 has experienced an extended period of aqueous alteration as indicated by the presence of hydrous mineral phases. It has also been exposed to at least one post-hydration short-lived thermal metamorphism. Glycine and alanine were possibly produced shortly after the accretion event of the asteroid parent body during the course of an extensive aqueous alteration event and have abstained from the short-term post-aqueous alteration heating due to the heterogeneity of the parent body composition and porosity. These carbonaceous chondrite samples are good analogs that offer important insights into the target asteroid Ryugu of the Hayabusa-2 mission, which is a C-type asteroid likely composed of heterogeneous materials including hydrated and dehydrated minerals.

Solvent extraction system for plutonium colloids and other oxide nano-particles

DOEpatents

Soderholm, Lynda; Wilson, Richard E; Chiarizia, Renato; Skanthakumar, Suntharalingam

2014-06-03

The invention provides a method for extracting plutonium from spent nuclear fuel, the method comprising supplying plutonium in a first aqueous phase; contacting the plutonium aqueous phase with a mixture of a dielectric and a moiety having a first acidity so as to allow the plutonium to substantially extract into the mixture; and contacting the extracted plutonium with second a aqueous phase, wherein the second aqueous phase has a second acidity higher than the first acidity, so as to allow the extracted plutonium to extract into the second aqueous phase. The invented method facilitates isolation of plutonium polymer without the formation of crud or unwanted emulsions.

WxC-β-SiC Nanocomposite Catalysts Used in Aqueous Phase Hydrogenation of Furfural.

PubMed

Rogowski, Jacek; Andrzejczuk, Mariusz; Berlowska, Joanna; Binczarski, Michal; Kregiel, Dorota; Kubiak, Andrzej; Modelska, Magdalena; Szubiakiewicz, Elzbieta; Stanishevsky, Andrei; Tomaszewska, Jolanta; Witonska, Izabela Alina

2017-11-22

This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO₂ in the presence of WO₃ at 1550 °C in argon resulted in the formation of W x C-β-SiC nanocomposite powders with significant variations in particle morphology and content of W x C-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA) of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA) and tetrahydrofurfuryl alcohol (THFA). Nanocomposite W x C-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest W x C crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

Cloud Chemistry in the United States: Problems and Prospects

NASA Astrophysics Data System (ADS)

Carlton, A. G.; Barth, M. C.; Lance, S.; Fahey, K.; McNeill, V. F.; Weber, R. J.

2017-12-01

Clouds cover 60% of the Earth's surface at a given time and are the primary means by which atmospheric trace species are lofted from the polluted boundary layer to the free troposphere. Clouds also play an important role as atmospheric aqueous phase reactors, scavenging soluble gas phase precursors and providing a medium for oxidation reactions that yield lower volatility products that contribute to increased aerosol mass when cloud drops evaporate. On a global average, most sulfate particles are formed during cloud processing, and organic particles known to form through aqueous phase pathways are found above clouds. However, atmospheric chemistry observations are generally biased for clear sky conditions. For example, aircraft field deployments typically avoid clouds. Satellite retrievals impacted by clouds are often screened from the final data products. This hinders knowledge of cloud chemistry and the impacts on tropospheric composition. In this work, we explore temporal and geospatial trends in trace species related to cloud processing in the U.S. with a focus on organic chemistry. We apply 3-dimensional and 0-dimensional models to recent campaigns and mountaintop cloud sampling sites, and compare to measurements.

Aqueous self-assembly of poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) copolymers: disparate diblock copolymer compositions give rise to nano- and meso-scale bilayered vesicles

NASA Astrophysics Data System (ADS)

Qi, Wei; Ghoroghchian, P. Peter; Li, Guizhi; Hammer, Daniel A.; Therien, Michael J.

2013-10-01

Nanoparticles formed from diblock copolymers of FDA approved PEO and PCL have generated considerable interest as in vivo drug delivery vehicles. Herein, we report the synthesis of the most extensive family PEO-b-PCL copolymers that vary over the largest range of number-average molecular weights (Mn: 3.6-57k), PEO weight fractions (fPEO: 0.08-0.33), and PEO chain lengths (0.75-5.8k) reported to date. These polymers were synthesized in order to establish the full range of aqueous phase behaviours of these diblock copolymers and to specifically identify formulations that were able to generate bilayered vesicles (polymersomes). Cryogenic transmission electron microscopy (cryo-TEM) was utilized in order to visualize the morphology of these structures upon aqueous self-assembly of dry polymer films. Nanoscale polymersomes were formed from PEO-b-PCL copolymers over a wide range of PEO weight fractions (fPEO: 0.14-0.27) and PEO molecular weights (0.75-3.8k) after extrusion of aqueous suspensions. Comparative morphology diagrams, which describe the nature of self-assembled structures as a function of diblock copolymer molecular weight and PEO weight fraction, show that in contrast to micron-scale polymersomes, which form only from a limited range of PEO-b-PCL diblock copolymer compositions, a multiplicity of PEO-b-PCL diblock copolymer compositions are able to give rise to nanoscale vesicles. These data underscore that PEO-b-PCL compositions that spontaneously form micron-sized polymersomes, as well as those that have previously been reported to form polymersomes via a cosolvent fabrication system, provide only limited insights into the distribution of PEO-b-PCL diblocks that give rise to nanoscale vesicles. The broad range of polymersome-forming PEO-b-PCL compositions described herein suggest the ability to construct extensive families of nanoscale vesicles of varied bilayer thickness, providing the ability to tune the timescales of vesicle degradation and encapsulant release based on the intended in vivo application.Nanoparticles formed from diblock copolymers of FDA approved PEO and PCL have generated considerable interest as in vivo drug delivery vehicles. Herein, we report the synthesis of the most extensive family PEO-b-PCL copolymers that vary over the largest range of number-average molecular weights (Mn: 3.6-57k), PEO weight fractions (fPEO: 0.08-0.33), and PEO chain lengths (0.75-5.8k) reported to date. These polymers were synthesized in order to establish the full range of aqueous phase behaviours of these diblock copolymers and to specifically identify formulations that were able to generate bilayered vesicles (polymersomes). Cryogenic transmission electron microscopy (cryo-TEM) was utilized in order to visualize the morphology of these structures upon aqueous self-assembly of dry polymer films. Nanoscale polymersomes were formed from PEO-b-PCL copolymers over a wide range of PEO weight fractions (fPEO: 0.14-0.27) and PEO molecular weights (0.75-3.8k) after extrusion of aqueous suspensions. Comparative morphology diagrams, which describe the nature of self-assembled structures as a function of diblock copolymer molecular weight and PEO weight fraction, show that in contrast to micron-scale polymersomes, which form only from a limited range of PEO-b-PCL diblock copolymer compositions, a multiplicity of PEO-b-PCL diblock copolymer compositions are able to give rise to nanoscale vesicles. These data underscore that PEO-b-PCL compositions that spontaneously form micron-sized polymersomes, as well as those that have previously been reported to form polymersomes via a cosolvent fabrication system, provide only limited insights into the distribution of PEO-b-PCL diblocks that give rise to nanoscale vesicles. The broad range of polymersome-forming PEO-b-PCL compositions described herein suggest the ability to construct extensive families of nanoscale vesicles of varied bilayer thickness, providing the ability to tune the timescales of vesicle degradation and encapsulant release based on the intended in vivo application. Electronic supplementary information (ESI) available: Materials and methods, characterization data. See DOI: 10.1039/c3nr03250g

Protein instability toward organic solvent/water emulsification: implications for protein microencapsulation into microspheres.

PubMed

Sah, H

1999-01-01

The objective of this study was to investigate the behavior of three proteins at an organic solvent/water interface. To simulate the first microencapsulation step of a water-in-oil-in-water emulsion technique, a water-in-oil emulsion was prepared by emulsifying an aqueous protein solution in either methylene chloride or ethyl acetate. Phase separation was then followed to collect protein samples from the aqueous phase and the organic solvent/water interface. Their properties were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size exclusion-HPLC. Bovine serum albumin was relatively unharmed during emulsification, compared to other proteins such as ovalbumin and lysozyme. In particular, the methylene chloride treatment on ovalbumin led to the formation of a large quantity of water-insoluble, solid-like aggregates and changes in the composition of monomeric and dimeric ovalbumin species. With regard to the question of ovalbumin recovery, only 9.74 approximately 37.72% of the used ovalbumin was present in the aqueous phases after emulsification. Similar penchant was noted with lysozyme. Water-insoluble aggregates brought with by emulsification were found to be covalently bound. Interestingly, less emulsification-induced denaturing effects were observed with ethyl acetate. Our study clearly demonstrated the emulsification-induced adverse events that were detrimental to the integrity of proteins and the importance of preserving protein stability toward microencapsulation.

Simultaneous enantioselective determination of six pesticides in aqueous environmental samples by chiral liquid chromatography with tandem mass spectrometry.

PubMed

Zhao, Pengfei; Lei, Shuo; Xing, Mingming; Xiong, Shihang; Guo, Xingjie

2018-03-01

A robust and sensitive method was developed for the enantiomeric analysis of six chiral pesticides (including metalaxyl, epoxiconazole, myclobutanil, hexaconazole, napropamide, and isocarbophos) in aquatic environmental samples. The optimized chromatographic conditions for the quantification of all the 12 enantiomers were performed with Chiralcel OD-RH column using mobile phase consisting of 0.1% aqueous formic acid and acetonitrile operated under reversed-phase conditions and then analyzed using liquid chromatography with tandem mass spectrometry. Twelve enantiomers were detected in multiple reaction monitoring mode. Solid-phase extraction and dispersive liquid-liquid microextraction were employed in this study. Response surface methodology was applied to assist in the dispersive liquid-liquid microextraction optimization. Under the optimum conditions, recoveries of pesticides enantiomers varied from 83.0 to 103.2% at two spiked levels with relative standard deviation less than 11.5%. The concentration factors were up to 1000 times. Method detection and quantification limits varied from 0.11 to 0.48 ng/L and from 0.46 to 1.49 ng/L, respectively. Finally, this method was used to determination of the enantiomers composition of the six pesticides in environmental aqueous matrices, which will help better understand the behavior of individual enantiomer and make accurate risk assessment to ecosystems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Oxygen Isotopic Composition of MIL 090001: A CR2 Chondrite with Abundant Refractory Inclusions

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.; McKeegan, K. D.; Sharp, Z. D.

2012-01-01

MIL 090001 is a large (>6 kg) carbonaceous chondrite that was classified as a member of the CV reduced subgroup (CVred) that was recovered during the 2009-2010 ANSMET field season [1]. Based on the abundance of refractory inclusions and the extent of aqueous alteration, Keller [2] suggested a CV2 classification. Here we report additional mineralogical and petrographic data for MIL 090001, its whole-rock oxygen isotopic composition and ion microprobe analyses of individual phases. The whole rock oxygen isotopic analyses show that MIL 090001 should be classified as a CR chondrite.

The temporal evolution of magnesium isotope fractionation during hydromagnesite dissolution, precipitation, and at equilibrium

NASA Astrophysics Data System (ADS)

Oelkers, Eric H.; Berninger, Ulf-Niklas; Pérez-Fernàndez, Andrea; Chmeleff, Jérôme; Mavromatis, Vasileios

2018-04-01

This study provides experimental evidence of the resetting of the magnesium (Mg) isotope signatures of hydromagnesite in the presence of an aqueous fluid during its congruent dissolution, precipitation, and at equilibrium at ambient temperatures over month-long timescales. All experiments were performed in batch reactors in aqueous sodium carbonate buffer solutions having a pH from 7.8 to 9.2. The fluid phase in all experiments attained bulk chemical equilibrium within analytical uncertainty with hydromagnesite within several days, but the experiments were allowed to continue for up to 575 days. During congruent hydromagnesite dissolution, the fluid first became enriched in isotopically light Mg compared to the dissolving hydromagnesite, but this Mg isotope composition became heavier after the fluid attained chemical equilibrium with the mineral. The δ26Mg composition of the fluid was up to ∼0.35‰ heavier than the initial dissolving hydromagnesite at the end of the dissolution experiments. Hydromagnesite precipitation was provoked during one experiment by increasing the reaction temperature from 4 to 50 °C. The δ26Mg composition of the fluid increased as hydromagnesite precipitated and continued to increase after the fluid attained bulk equilibrium with this phase. These observations are consistent with the hypothesis that mineral-fluid equilibrium is dynamic (i.e. dissolution and precipitation occur at equal, non-zero rates at equilibrium). Moreover the results presented in this study confirm (1) that the transfer of material from the solid to the fluid phase may not be conservative during stoichiometric dissolution, and (2) that the isotopic compositions of carbonate minerals can evolve even when the mineral is in bulk chemical equilibrium with its coexisting fluid. This latter observation suggests that the preservation of isotopic signatures of carbonate minerals in the geological record may require a combination of the isolation of fluid-mineral system from external chemical input and/or the existence of a yet to be defined dissolution/precipitation inhibition mechanism.

Mass transfer and carbon isotope evolution in natural water systems

USGS Publications Warehouse

Wigley, T.M.L.; Plummer, Niel; Pearson, F.J.

1978-01-01

This paper presents a theoretical treatment of the evolution of the carbon isotopes C13 and C14 in natural waters and in precipitates which derive from such waters. The effects of an arbitrary number of sources (such as dissolution of carbonate minerals and oxidation of organic material) and sinks (such as mineral precipitation, CO2 degassing and production of methane), and of equilibrium fractionation between solid, gas and aqueous phases are considered. The results are expressed as equations relating changes in isotopic composition to changes in conventional carbonate chemistry. One implication of the equations is that the isotopic composition of an aqueous phase may approach a limiting value whenever there are simultaneous inputs and outputs of carbonate. In order to unambiguously interpret isotopic data from carbonate precipitates and identify reactants and products in reacting natural waters, it is essential that isotopic changes are determined chiefly by reactant and product stoichiometry, independent of reaction path. We demonstrate that this is so by means of quantitative examples. The evolution equations are applied to: 1. (1) carbon-14 dating of groundwaters; 2. (2) interpretation of the isotopic composition of carbonate precipitates, carbonate cements and diagenetically altered carbonates; and 3. (3) the identification of chemical reaction stoichiometry. These applications are illustrated by examples which show the variation of ??C13 in solutions and in precipitates formed under a variety of conditions involving incongruent dissolution, CO2 degassing, methane production and mineral precipitation. ?? 1978.

Extension of the CAPRAM mechanism with the improved mechanism generator GECKO-A

NASA Astrophysics Data System (ADS)

Herrmann, H.; Bräuer, P.; Mouchel-Vallon, C.; Tilgner, A.; Wolke, R.; Aumont, B.

2013-12-01

The ubiquitous abundance of organic compounds in natural and anthropogenically influenced eco-systems has put these compounds into the focus of environmental research. To investigate the chemistry of organic compounds in the tropospheric multiphase system, modelling can provide a useful tool. While in the gas phase several comprehensive near-explicit mechanisms exist, in the aqueous phase those mechanisms are very limited. The present study aims to advance the currently most comprehensive aqueous phase mechanism CAPRAM 3.0n (Tilgner and Herrmann, 2010; Bräuer et al., 2013) by means of automated mechanism self-construction. Therefore, the mechanism generator GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere; see Aumont et al., 2005) has been advanced to the aqueous phase. A protocol has been designed for automated mechanism construction based on reviewed experimental data and evaluated prediction methods. The generator is able to describe the oxidation of aliphatic organic compounds by OH and NO3. For the mechanism construction, mainly structure-activity relationships are used. They are completed by Evans-Polanyi-type correlations, which have been further improved for the purpose of automated mechanism self-construction. GECKO-A has been used to create new CAPRAM versions, where branching ratios are introduced and new chemical subsystems with species with up to 4 carbon atoms are added. The currently most comprehensive version, CAPRAM 3.5alpha, includes about 2000 aqueous phase species and more than 3300 reactions in the aqueous phase. Process studies with the box model SPACCIM (SPectral Aerosol Cloud Chemistry Interaction Model; Wolke et al., 2005) have been performed using a meteorological scenario with non-permanent clouds. Besides the investigation of the concentration-time profiles, detailed time-resolved flux analyses have been performed. Several aqueous phase subsystems have been investigated, such as the formation of oxidised mono- and diacids in the aqueous phase as well as interactions to inorganic cycles and the influence on the gas phase chemistry and composition. Results have been compared to results of previous versions and show a significant improvement in CAPRAM 3.5alpha when comparing the modelled data to literature data from field experiments. For example, in CAPRAM 3.5alpha there is a malonic acid production of about 80 ng/m3 compared to a few ng m-3 in CAPRAM 3.0n. The results in CAPRAM 3.5alpha confirm recent measurements by Bao et al. (2012), who measured up to 137 ng m-3. Moreover, several attempts have been undertaken to validate the mechanisms created by GECKO-A with own experiments, such as the HCCT-2010 campaign and LEAK chamber experiments. References Aumont, B et al., Atmos. Chem. Phys., 5, 2497-2517, 2005. Bräuer, P. et al., J. Atmos. Chem., 70(1), 1 - 34, 2013. Bao, L. et al., Atmos. Env., 47, 546 - 553, 2012. Tilgner, A. and Herrmann, H., Atmos. Environ., 44, 5415 - 5422, 2010. Wolke, R. et al., Atmos. Environ., 39, 4375 - 4388, 2005.

Fractionated-combustion analysis of carbonate-containing phases in composite materials of the hydroxyapatite-calcium carbonate system

NASA Astrophysics Data System (ADS)

Goldberg, M. A.; Shibaeva, T. V.; Smirnov, V. V.; Kutsev, S. V.; Barinov, S. M.; Grigorovich, K. V.

2012-12-01

Materials in the hydroxyapatite (HA)-calcium carbonate (CC) system were synthesized by a precipitation method from aqueous solutions. According to the data of X-ray phase analysis and IR spectroscopy, the powders consisted of CC and AB-type carbonate-substituted HA (CHA). In order to determine the content of carbonate-containing phases in materials, the temperature-temporal mode of fractionated-combustion analysis of carbon was developed. The quantitative phase ratios and the degree of substitution of carbonate groups in CHA were determined. It was shown that the degree of substitution of carbonate groups in CHA increased from 2.47 to 5.31 wt % as the CC content increased from 13.50 to 88.33 wt %.

The effect of calcination temperature on the microstructure and photocatalytic activity of TiO2-based composite nanotubes prepared by an in situ template dissolution method

NASA Astrophysics Data System (ADS)

Fan, Jiajie; Zhao, Li; Yu, Jiaguo; Liu, Gang

2012-09-01

TiO2-based composite nanotubes, based on an in situ template dissolution method, were one-step fabricated in a mixed aqueous solution of ammonium hexafluorotitanate and boric acid using ZnO nanorods as templates, and then the samples were calcined at different temperatures. The photocatalytic activity of the samples was evaluated by photocatalytic decoloration of Methyl Orange (MO) aqueous solution at ambient temperature under UV light. The results showed that the prepared sample possessed nanoscale tubular morphology with a wall thickness of ca. 30-50 nm, inner diameters of ca. 50-150 nm and lengths of ca. 400-2000 nm. The calcined samples exhibited excellent stabilization of the anatase phase in a wide temperature range of 300-800 °C. The un-calcined and calcined samples possessed hierarchically macro-mesoporous structures. The sample calcined at 600 °C exhibited the highest photocatalytic activity, corresponding to the maximal formation rate of \\z.rad OH on the photocatalyst. This is attributed to the improvement of anatase TiO2 crystallization, the formation of multi-phase structures including anatase, cubic Zn2TiO4, hexagonal ZnTiO3 and cubic ZnTiO3, and the presence of hierarchically macro-mesoporous structures.

Enhanced electrochemical performances with a copper/xylose-based carbon composite electrode

NASA Astrophysics Data System (ADS)

Sirisomboonchai, Suchada; Kongparakul, Suwadee; Nueangnoraj, Khanin; Zhang, Haibo; Wei, Lu; Reubroycharoen, Prasert; Guan, Guoqing; Samart, Chanatip

2018-04-01

Copper/carbon (Cu/C) composites were prepared through the simple and environmentally benign hydrothermal carbonization of xylose in the presence of Cu2+ ions. The morphology, specific surface area, phase structure and chemical composition were investigated. Using a three-electrode system in 0.1 M H2SO4 aqueous electrolyte, the Cu/C composite (10 wt% Cu) heat-treated at 600 °C gave the highest specific capacitance (316.2 and 350.1 F g-1 at 0.5 A g-1 and 20 mV s-1, respectively). The addition of Cu was the major factor in improving the electrochemical performance, enhancing the specific capacitance more than 30 times that of the C without Cu. Therefore, the Cu/C composite presented promising results in improving biomass-based C electrodes for supercapacitors.

Halogenated solvent remediation

DOEpatents

Sorenson, Kent S.

2004-08-31

Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. A preferred method includes adding a composition to the ground water wherein the composition is an electron donor for microbe-mediated reductive dehalogenation of the halogenated solvents and enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative compositions effective in these methods include surfactants such as C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof. Especially preferred compositions for use in these methods include lactic acid, salts of lactic acid, such as sodium lactate, lactate esters, and mixtures thereof. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the composition.

Reactive transport modeling to study changes in water chemistry induced by CO2 injection at the Frio-I Brine Pilot

USGS Publications Warehouse

Xu, T.; Kharaka, Y.K.; Doughty, C.; Freifeld, B.M.; Daley, T.M.

2010-01-01

To demonstrate the potential for geologic storage of CO2 in saline aquifers, the Frio-I Brine Pilot was conducted, during which 1600 tons of CO2 were injected into a high-permeability sandstone and the resulting subsurface plume of CO2 was monitored using a variety of hydrogeological, geophysical, and geochemical techniques. Fluid samples were obtained before CO2 injection for baseline geochemical characterization, during the CO2 injection to track its breakthrough at a nearby observation well, and after injection to investigate changes in fluid composition and potential leakage into an overlying zone. Following CO2 breakthrough at the observation well, brine samples showed sharp drops in pH, pronounced increases in HCO3- and aqueous Fe, and significant shifts in the isotopic compositions of H2O and dissolved inorganic carbon. Based on a calibrated 1-D radial flow model, reactive transport modeling was performed for the Frio-I Brine Pilot. A simple kinetic model of Fe release from the solid to aqueous phase was developed, which can reproduce the observed increases in aqueous Fe concentration. Brine samples collected after half a year had lower Fe concentrations due to carbonate precipitation, and this trend can be also captured by our modeling. The paper provides a method for estimating potential mobile Fe inventory, and its bounding concentration in the storage formation from limited observation data. Long-term simulations show that the CO2 plume gradually spreads outward due to capillary forces, and the gas saturation gradually decreases due to its dissolution and precipitation of carbonates. The gas phase is predicted to disappear after 500 years. Elevated aqueous CO2 concentrations remain for a longer time, but eventually decrease due to carbonate precipitation. For the Frio-I Brine Pilot, all injected CO2 could ultimately be sequestered as carbonate minerals. ?? 2010 Elsevier B.V.

Chemical resistance and cleanability of glazed surfaces

NASA Astrophysics Data System (ADS)

Hupa, Leena; Bergman, Roger; Fröberg, Linda; Vane-Tempest, Stina; Hupa, Mikko; Kronberg, Thomas; Pesonen-Leinonen, Eija; Sjöberg, Anna-Maija

2005-06-01

Adhesion of soil on glazed surfaces and their cleanability depends on chemical composition, phase composition, and roughness of the surface. The surface can be glossy consisting mainly of a smooth glassy phase. A matt and rough surface consists of a glassy phase and one or more crystalline phases. The origin and composition of the crystalline phases affect the chemical resistance and the cleanability of the surface. Fifteen experimental glossy and matt glazes were soaked in a slightly alkaline cleaning agent solution. The surfaces were spin-coated with sebum, i.e. a soil component typical for sanitary facilities. After wiping out the soil film in a controlled manner, the surface conditions and the soil left were evaluated with colour measurements, SEM/EDXA and COM. The results show that wollastonite-type crystals in the glaze surfaces were attacked in aqueous solutions containing typical cleaning agents. This corrosion led to significant decrease in the cleanability of the surface. The other crystal types observed, i.e. diopside and quartz crystals were not corroded, and the cleanability of glazes containing only these crystals was not changed in the cleaning agent exposures. Also the glassy phase was found to be attacked in some formulations leading to a somewhat decreased cleanability. The repeated soiling and cleaning procedures indicated that soil is accumulated on rough surfaces and surfaces which were clearly corroded by the cleaning agent.

Compositions comprising free-standing two-dimensional nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barsoum, Michel W.; Gogotsi, Yury; Abdelmalak, Michael Naguib

2017-12-05

The present invention is directed to methods of transferring urea from an aqueous solution comprising urea to a MXene composition, the method comprising contacting the aqueous solution comprising urea with the MXene composition for a time sufficient to form an intercalated MXene composition comprising urea.

Partition of nonionic organic compounds in aquatic systems

USGS Publications Warehouse

Smith, James A.; Witkowski, Patrick J.; Chiou, Cary T.

1988-01-01

In aqueous systems, the distribution of many nonionic organic solutes in soil-sediment, aquatic organisms, and dissolved organic matter can be explained in terms of a partition model. The nonionic organic solute is distributed between water and different organic phases that behave as bulk solvents. Factors such as polarity, composition, and molecular size of the solute and organic phase determine the relative importance of partition to the environmental distribution of the solute. This chapter reviews these factors in the context of a partition model and also examines several environmental applications of the partition model for surface- and ground-water systems.

Aqueous Alteration of Carbonaceous Chondrites: New Insights from Comparative Studies of Two Unbrecciated CM2 Chondrites, Y 791198 and ALH 81002

NASA Technical Reports Server (NTRS)

Chizmadia, L. J.; Brearley, A. J.

2004-01-01

Carbonaceous chondrites are an important resource for understanding the physical and chemical conditions in the early solar system. In particular, a long-standing question concerns the role of water in the cosmochemical evolution of carbonaceous chondrites. It is well established that extensive hydration of primary nebular phases occurred in the CM and CI chondrites, but the location where this alteration occurred remains controversial. In the CM2 chondrites, hydration formed secondary phases such as serpentine, tochilinite, pentlandite, carbonate and PCP. There are several textural observations which suggest that alteration occurred before the accretion of the final CM parent asteroid, i.e. preaccretionary alteration. Conversely, there is a significant body of evidence that supports parent-body alteration. In order to test these two competing hypotheses further, we studied two CM chondrites, Y-791198 and ALH81002, two meteorites that exhibit widely differing degrees of aqueous alteration. In addition, both meteorites have primary accretionary textures, i.e. experienced minimal asteroidal brecciation. Brecciation significantly complicates the task of unraveling alteration histories, mixing components that have been altered to different degrees from different locations on the same asteroidal parent body. Alteration in Y-791198 is mostly confined to chondrule mesostases, FeNi metal and fine-grained matrix and rims. In comparison, the primary chondrule silicates in ALH81002 have undergone extensive replacement by secondary hydrous phases. This study focuses on compositional and textural relationships between chondrule mesostasis and the associated rim materials. Our hypothesis is: both these components are highly susceptible to aqueous alteration and should be sensitive recorders of the alteration process. For parent body alteration, we expect systematic coupled mineralogical and compositional changes in rims and altered mesostasis, as elemental exchange between these components occurs. Conversely, for preaccretionary alteration, there should be no clear relationships between the rims and mesostases.

Aerosol Fragmentation Driven by Coupling of Acid-Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals.

PubMed

Liu, Matthew J; Wiegel, Aaron A; Wilson, Kevin R; Houle, Frances A

2017-08-10

A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps with physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular weight gas-phase reaction products and decreasing particle size.

Aerosol Fragmentation Driven by Coupling of Acid–Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals

DOE PAGES

Liu, Matthew J.; Wiegel, Aaron A.; Wilson, Kevin R.; ...

2017-07-14

A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps withmore » physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular weight gas-phase reaction products and decreasing particle size.« less

Aerosol Fragmentation Driven by Coupling of Acid–Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Matthew J.; Wiegel, Aaron A.; Wilson, Kevin R.

A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps withmore » physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular weight gas-phase reaction products and decreasing particle size.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Guohui; Qafoku, Nikolla; Lawter, Amanda R.

A series of batch and column experiments combined with solid phase characterization studies (i.e., quantitative x-ray diffraction and wet chemical extractions) were conducted to address a variety of scientific issues and evaluate the impacts of the potential leakage of carbon dioxide (CO2) from deep subsurface storage reservoirs. The main objective was to gain an understanding of how CO2 gas influences: 1) the aqueous phase pH; and 2) mobilization of major, minor, and trace elements from minerals present in an aquifer overlying potential CO2 sequestration subsurface repositories. Rocks and slightly weathered rocks representative of an unconfined, oxidizing carbonate aquifer within themore » continental US, i.e., the Edwards aquifer in Texas, were used in these studies. These materials were exposed to a CO2 gas stream or were leached with a CO2-saturated influent solution to simulate different CO2 gas leakage scenarios, and changes in aqueous phase pH and chemical composition were measured in the liquid samples collected at pre-determined experimental times (batch experiments) or continuously (column experiments). The results from the strong acid extraction tests confirmed that in addition to the usual elements present in most soils, rocks, and sediments, the Edward aquifer samples contain As, Cd, Pb, Cu, and occasionally Zn, which may potentially be mobilized from the solid to the aqueous phase during or after exposure to CO2. The results from the batch and column experiments confirmed the release of major chemical elements into the contacting aqueous phase (such as Ca, Mg, Ba, Sr, Si, Na, and K); the mobilization and possible rapid immobilization of minor elements (such as Fe, Al, and Mn), which are able to form highly reactive secondary phases; and sporadic mobilization of only low concentrations of trace elements (such as As, Cd, Pb, Cu, Zn, Mo, etc.). The results from this experimental research effort will help in developing a systematic understanding of how CO2 leakage is likely to influence pertinent geochemical processes (e.g., dissolution/precipitation, sorption/desorption) in the aquifer sediments and will support site selection, risk assessment, policy-making, and public education efforts associated with geologic carbon sequestration.« less

POLONIUM SEPARATION PROCESS

DOEpatents

Karraker, D.G.

1959-07-14

A liquid-liquid extraction process is presented for the recovery of polonium from lead and bismuth. According to the invention an acidic aqueous chloride phase containing the polonium, lead, and bismuth values is contacted with a tributyl phosphate ether phase. The polonium preferentially enters the organic phase which is then separated and washed with an aqueous hydrochloric solution to remove any lead or bismuth which may also have been extracted. The now highly purified polonium in the organic phase may be transferred to an aqueous solution by extraction with aqueous nitric acid.

Crustal structure and igneous processes in a chondritic Io

NASA Technical Reports Server (NTRS)

Kargel, J. S.

1993-01-01

Liquid sulfur can form when metal-free C1 or C2 chondrites are heated. It may be obtained either by direct melting of native sulfur in disequilibrated C1 or C2 chondrites or by incongruent melting of pyrite and other sulfides in thermodynamically equilibrated rocks of the same composition. Hence, Lewis considered C2 chondrites to be the best meteoritic analog for Io's bulk composition. Metal-bearing C3 and ordinary chondrites are too chemically reduced to yield liquid sulfur and are not thought to represent plausible analogs of Io's bulk composition. An important aspect of Lewis' work is that CaSO4 and MgSO4 are predicted to be important in Io. Real C1 and C2 chondrites contain averages of, respectively, 11 percent and 3 percent by mass of salts (plus water of hydration). The most abundant chondritic salts are magnesium and calcium sulfates, but other important components include sulfates of sodium, potassium, and nickel and carbonates of magnesium, calcium, and iron. It is widely accepted that chondritic salts are formed by low-temperature aqueous alteration. Even if Io originally did not contain salts, it is likely that aqueous alteration would have yielded several percent sulfates and carbonates. In any event, Io probably contains sulfates and carbonates. This report presents the results of a model of differentiation of a simplified C2 chondrite-like composition that includes 1.92 percent MgSO4, 0.56 percent CaSO4, 0.53 percent CaCO3, and 0.094 percent elemental sulfur. The temperature of the model is gradually increased; ensuing fractional melting results in these components extruding or intruding at gravitationally stable levels in Io's crust. Relevant phase equilibria were reviewed. A deficiency of high-pressure phase equilibria renders the present model qualitative.

Temperature-responsive chromatography for the separation of biomolecules.

PubMed

Kanazawa, Hideko; Okano, Teruo

2011-12-09

Temperature-responsive chromatography for the separation of biomolecules utilizing poly(N-isopropylacrylamide) (PNIPAAm) and its copolymer-modified stationary phase is performed with an aqueous mobile phase without using organic solvent. The surface properties and function of the stationary phase are controlled by external temperature changes without changing the mobile-phase composition. This analytical system is based on nonspecific adsorption by the reversible transition of a hydrophilic-hydrophobic PNIPAAm-grafted surface. The driving force for retention is hydrophobic interaction between the solute molecules and the hydrophobized polymer chains on the stationary phase surface. The separation of the biomolecules, such as nucleotides and proteins was achieved by a dual temperature- and pH-responsive chromatography system. The electrostatic and hydrophobic interactions could be modulated simultaneously with the temperature in an aqueous mobile phase, thus the separation system would have potential applications in the separation of biomolecules. Additionally, chromatographic matrices prepared by a surface-initiated atom transfer radical polymerization (ATRP) exhibit a strong interaction with analytes, because the polymerization procedure forms a densely packed polymer, called a polymer brush, on the surfaces. The copolymer brush grafted surfaces prepared by ATRP was an effective tool for separating basic biomolecules by modulating the electrostatic and hydrophobic interactions. Applications of thermally responsive columns for the separations of biomolecules are reviewed here. Copyright © 2011 Elsevier B.V. All rights reserved.

A Novel Aqueous Micellar Two-Phase System Composed of Surfactant and Sorbitol for Purification of Pectinase Enzyme from Psidium guajava and Recycling Phase Components

PubMed Central

Murshid, Fara Syazana; Manap, Mohd Yazid; Hussin, Muhaini

2015-01-01

A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme. PMID:25756051

One-step hydrothermal preparation of (NH4)2V3O8/carbon composites and conversion to porous V2O5 nanoparticles as supercapacitor electrode with excellent pseudocapacitive capability

NASA Astrophysics Data System (ADS)

Zhang, Yifu; Zheng, Jiqi; Wang, Qiushi; Zhang, Shaoqing; Hu, Tao; Meng, Changgong

2017-11-01

(NH4)2V3O8/carbon composites were successfully achieved using NH4VO3 and glucose as the starting materials via a one-step hydrothermal route for the first time. The composites consisted a layer structured (NH4)2V3O8 and amorphous carbon with aromatic structures containing lots of active function groups. Then porous V2O5 nanoparticles were fabricated by the thermal treatment of (NH4)2V3O8/carbon composites in air atmospheres. The BET specific surface area of (NH4)2V3O8/carbon composites measured 1.68 m2 g-1, whereas BET surface area of porous V2O5 nanoparticles reached 10.6 m2 g-1 and the average pore size totaled 28.9 nm. The synthetic process of (NH4)2V3O8/carbon composites and porous V2O5 nanoparticles was briefly discussed. Electrochemical properties of porous V2O5 nanoparticles as supercapacitor electrodes were investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) both in the aqueous and organic electrolytes. The influence of calcined temperature and time and the mole ratio of NH4VO3/glucose on specific capacitance, phase and morphology of samples were discussed in detail. Porous V2O5 nanoparticles respectively exhibited the specific capacitance of 433 and 545 F g-1 in the aqueous and organic electrolytes at the current density of 1 A g-1. After 100 cycles, the capacitance retention was 89.6% in organic electrolyte, whereas it was only 22.9% in aqueous electrolyte. It turned out that electrochemical properties of porous V2O5 nanoparticles were greatly improved by using organic electrolyte.

Electrochemical luminescence determination of hyperin using a sol-gel@graphene luminescent composite film modified electrode for solid phase microextraction

NASA Astrophysics Data System (ADS)

Zou, Xiaojun; Shang, Fang; Wang, Sui

2017-02-01

In this paper, a novel electrochemiluminescence (ECL) sensor of sol-gel@graphene luminescent composite film modified electrode for hyperin determination was prepared using graphene (G) as solid-phase microextraction (SPME) material, based on selective preconcentration of target onto an electrode and followed by luminol ECL detection. Hyperin was firstly extracted from aqueous solution through the modified GCE. Hydrogel, electrogenerated chemiluminescence reagents, pH of working solution, extraction time and temperature and scan rate were discussed. Under the optimum conditions, the change of ECL intensity was in proportion to the concentration of hyperin in the range of 0.02-0.24 μg/mL with a detection limit of 0.01 μg/mL. This method showed good performance in stability, reproducibility and precision for the determination of hyperin.

Micellar versus hydro-organic mobile phases for retention-hydrophobicity relationship studies with ionizable diuretics and an anionic surfactant.

PubMed

Ruiz-Angel, M J; Carda-Broch, S; García-Alvarez-Coque, M C; Berthod, A

2004-03-19

Logarithm of retention factors (log k) of a group of 14 ionizable diuretics were correlated with the molecular (log P o/w) and apparent (log P(app)) octanol-water partition coefficients. The compounds were chromatographed using aqueous-organic (reversed-phase liquid chromatography, RPLC) and micellar-organic mobile phases (micellar liquid chromatography, MLC) with the anionic surfactant sodium dodecyl sulfate (SDS), in the pH range 3-7, and a conventional octadecylsilane column. Acetonitrile was used as the organic modifier in both modes. The quality of the correlations obtained for log P(app) at varying ionization degree confirms that this correction is required in the aqueous-organic mixtures. The correlation is less improved with SDS micellar media because the acid-base equilibriums are shifted towards higher pH values for acidic compounds. In micellar chromatography, an electrostatic interaction with charged solutes is added to hydrophobic forces; consequently, different correlations should be established for neutral and acidic compounds, and for basic compounds. Correlations between log k and the isocratic descriptors log k(w), log k(wm) (extrapolated retention to pure water in the aqueous-organic and micellar-organic systems, respectively), and psi0 (extrapolated mobile phase composition giving a k = 1 retention factor or twice the dead time), and between these descriptors and log P(app) were also satisfactory, although poorer than those between log k and log P(app) due to the extrapolation. The study shows that, in the particular case of the ionizable diuretics studied, classical RPLC gives better results than MLC with SDS in the retention hydrophobicity correlations.

Predicting the pKa and stability of organic acids and bases at an oil-water interface.

PubMed

Andersson, M P; Olsson, M H M; Stipp, S L S

2014-06-10

We have used density functional theory and the implicit solvent model, COSMO-RS, to investigate how the acidity constant, pKa, of organic acids and bases adsorbed at the organic compound-aqueous solution interface changes, compared to its value in the aqueous phase. The pKa determine the surface charge density of the molecules that accumulate at the fluid-fluid interface. We have estimated the pKa by comparing the stability of the protonated and unprotonated forms of a series of molecules in the bulk aqueous solution and at an interface where parts of each molecule reside in the hydrophobic phase and the rest remains in the hydrophilic phase. We found that the pKa for acids is shifted by ∼1 pH unit to higher values compared to the bulk water pKa, whereas they are shifted to lower values by a similar amount for bases. Because this pKa shift is similar in magnitude for each of the molecules studied, we propose that the pKa for molecules at a water-organic compound interface can easily be predicted by adding a small shift to the aqueous pKa. This shift is general and correlates with the functional group. We also found that the relative composition of molecules at the fluid-fluid interface is not the same as in the bulk. For example, species such as carboxylic acids are enriched at the interface, where they can dominate surface properties, even when they are a modest component in the bulk fluid. For high surface concentrations of carboxylic acid groups at an interface, such as a self-assembled monolayer, we have demonstrated that the pKa depends on the degree of deprotonation through direct hydrogen bonding between protonated and deprotonated acidic headgroups.

Ternary liquid-liquid equilibrium for eugenol + tert-butanol + water system at 303.15 and 323.15K and atmospheric pressure

NASA Astrophysics Data System (ADS)

Sucipto, Retno Kumala Hesti; Kuswandi, Wibawa, Gede

2017-05-01

The objective of this study was to determine ternary liquid-liquid equilibrium for eugenol + tert-butanol + water system at 303.15 and 323.15K and atmospheric pressure. Using 25 mL equilibrium cell equipped jacketted water connected to water bath to maintain equilibrium temperature constant. The procedure of this experiment was conducted by inserting mixture of eugenol + tert-butanol + water system at certain composition into equilibrium cell. The solution was stirred for 4 hours and then was allowed for 20 hours in order to separate aqueous and organic phases completely. The temperature equilibrium cell of and the atmosphere pressure were recorded as equilibrium temperature and pressure for each measurenment. The equilibrium compositions of each phase were analyzed using Gas Chromatography. The experimental data obtained in this work were correlated with NRTL and UNIQUAC models with root mean square deviation between esperimental and calculated equilibrium compositions of 0.03% and 0.04% respectively.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patil, B. N.; Acharya, S. A., E-mail: saha275@yahoo.com

In the present work ZnS-CdS composite was prepared by hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD) to confirm formation of nano particles, Scanning electron microscopy (SEM) images exhibit nanoscale dimensions of as synthesized individual phases. UV/VIS spectra were recorded for evaluation of photophysical properties. The composite was explored as photocatalysts to study dye degradation using methylene blue in aqueous slurry under irradiation of 663 nm wavelength and congo red under irradiation of 493 nm wavelength. Under the same conditions the photocatalytic activity of the individual phases ZnS and CdS were also examined. The ZnS-CdS composite is found inmore » enhancing the rate of photo degradation of toxic dyes as compare to ZnS and CdS individually in presence of visible light. This ZnS based metal sulphide/oxide semiconductor nanocomposites are high potential material for Photo-degradation of toxic dyes, and act as good photocatalyst in visible light.« less

Treatment of aqueous phase of bio-oil by granular activated carbon and evaluation of biogas production.

PubMed

Shanmugam, Saravanan R; Adhikari, Sushil; Wang, Zhouhang; Shakya, Rajdeep

2017-01-01

Hydrothermal liquefaction of wet biomass such as algae is a promising thermochemical process for the production of bio-oil. Bio-oil aqueous phase generated during liquefaction process is rich in complex organics and can be utilized for biogas production following its pre-treatment with granular activated carbon. In our study, use of 30% activated carbon resulted in higher chemical oxygen demand (COD) reduction (53±0.3%) from aqueous phase. Higher CH 4 production (84±12mL/gCOD) was also observed in 30% carbon-treated aqueous phase fed cultures, whereas only 32±6mLCH 4 /gCOD was observed in control (non-carbon treated) cultures. The results from this study indicate that almost 67±0.3% initial COD of aqueous phase can be reduced using a combination of both carbon treatment and biogas production. This study shows that aqueous phase can be utilized for CH 4 production. Copyright © 2016 Elsevier Ltd. All rights reserved.

In situ quantification of β-carotene partitioning in oil-in-water emulsions by confocal Raman microscopy.

PubMed

Wan Mohamad, W A Fahmi; Buckow, Roman; Augustin, MaryAnn; McNaughton, Don

2017-10-15

Confocal Raman microscopy (CRM) was able to quantify the β-carotene concentration in oil droplets and determine the partitioning characteristics of β-carotene within the emulsion system in situ. The results were validated by a conventional method involving solvent extraction of β-carotene separately from the total emulsion as well as the aqueous phase separated by centrifugation, and quantification by absorption spectrophotometry. CRM also enabled the localization of β-carotene in an emulsion. From the Raman image, the β-carotene partitioning between the aqueous and oil phases of palm olein-in-water emulsions stabilized by whey protein isolate (WPI) was observed. Increasing the concentration of β-carotene in an emulsion (from 0.1 to 0.3g/kg emulsion) with a fixed gross composition (10% palm olein:2% WPI) decreased the concentration of β-carotene in the oil droplet. CRM is a powerful tool for in situ analyses of components in heterogeneous systems such as emulsions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling Degradation Product Partitioning in Chlorinated-DNAPL Source Zones

NASA Astrophysics Data System (ADS)

Boroumand, A.; Ramsburg, A.; Christ, J.; Abriola, L.

2009-12-01

Metabolic reductive dechlorination degrades aqueous phase contaminant concentrations, increasing the driving force for DNAPL dissolution. Results from laboratory and field investigations suggest that accumulation of cis-dichloroethene (cis-DCE) and vinyl chloride (VC) may occur within DNAPL source zones. The lack of (or slow) degradation of cis-DCE and VC within bioactive DNAPL source zones may result in these dechlorination products becoming distributed among the solid, aqueous, and organic phases. Partitioning of cis-DCE and VC into the organic phase may reduce aqueous phase concentrations of these contaminants and result in the enrichment of these dechlorination products within the non-aqueous phase. Enrichment of degradation products within DNAPL may reduce some of the advantages associated with the application of bioremediation in DNAPL source zones. Thus, it is important to quantify how partitioning (between the aqueous and organic phases) influences the transport of cis-DCE and VC within bioactive DNAPL source zones. In this work, abiotic two-phase (PCE-water) one-dimensional column experiments are modeled using analytical and numerical methods to examine the rate of partitioning and the capacity of PCE-DNAPL to reversibly sequester cis-DCE. These models consider aqueous-phase, nonaqueous phase, and aqueous plus nonaqueous phase mass transfer resistance using linear driving force and spherical diffusion expressions. Model parameters are examined and compared for different experimental conditions to evaluate the mechanisms controlling partitioning. Biot number, a dimensionless number which is an index of the ratio of the aqueous phase mass transfer rate in boundary layer to the mass transfer rate within the NAPL, is used to characterize conditions in which either or both processes are controlling. Results show that application of a single aqueous resistance is capable to capture breakthrough curves when DNAPL is distributed in porous media as low-saturation ganglia, while diffusion within the DNAPL should be considered for larger NAPL pools. These results offer important insights to the monitoring and interpretation of bioremediation strategies employed within DNAPL source zones.

Elucidating Particle Acidity during North China Winter Haze Events

NASA Astrophysics Data System (ADS)

Song, S.; Gao, M.; Sun, Y.; Li, M.; Wang, S.; Wang, Y.; Xu, W.; Zhu, L.; Munger, W.; McElroy, M. B.

2017-12-01

A characteristic feature of North China winter haze pollution is the rapid formation of sulfate. An accurate prediction of particle acidity, or pH, is critical for evaluating the contributions of various aqueous and heterogeneous sulfate production mechanisms (e.g. the reactions involving reactive nitrogen and transition metal ions), and is also important for evaluating the toxicity of atmospheric particles. However, particle acidity during winter haze periods is poorly constrained, and estimates in several recent studies display significant discrepancies, ranging from moderately acidic (pH 4) to neutral (pH 7). In this study, we calculate fine particle pH for several haze episodes during the 2014/2015 winter, using several methods including phase partitioning of ammonia, ion balance, and multiple thermodynamic equilibrium models. Hourly gaseous and particle composition measurements were taken at an urban site in Beijing. We find that the discrepancies in the calculated pH for recent studies are largely due to their differences in assumed methodology. The ion balance method and the reverse modes of thermodynamic models (using only aerosol phase compositions as input) are not suitable for calculating pH in this atmospheric environment. We also find, for the first time, that hydroxymethanesulfonate (HMS), formed from complexation of sulfite and bisulfite with formaldehyde in the aqueous phase, can serve as a tracer of particle pH during winter haze events. Here the concentrations of HMS are quantified using measurement data from an Aerodyne high-resolution aerosol mass spectrometer. HMS is found to contribute a few percent to particle mass during winter haze episodes. The presence of HMS is also identified with data from a single particle aerosol mass spectrometer. Since it may be incorrectly identified as sulfate during the typical chemical composition analysis of fine particles (e.g. ion chromatography), the existence of HMS could explain a significant fraction of the underestimation of sulfate formation in current air quality models. Preliminary results suggest that particle pH values estimated with the HMS tracer, phase partitioning of ammonia, and the forward modes (specifying total concentrations of gas and particle phases) of thermodynamic models are in good agreement.

Short Range-Ordered Minerals: Insight into Aqueous Alteration Processes on Mars

NASA Technical Reports Server (NTRS)

Ming, Douglas W.; Morris, R. V.; Golden, D. C.

2011-01-01

Short range-ordered (SRO) aluminosilicates (e.g., allophane) and nanophase ferric oxides (npOx) are common SRO minerals derived during aqueous alteration of basaltic materials. NpOx refers to poorly crystalline or amorphous alteration products that can be any combination of superparamagnetic hematite and/or goethite, akaganeite, schwertmannite, ferrihydrite, iddingsite, and nanometer-sized ferric oxide particles that pigment palagonitic tephra. Nearly 30 years ago, SRO phases were suggested as alteration phases on Mars based on similar spectral properties for altered basaltic tephra on the slopes of Mauna Kea in Hawaii and Martian bright regions measured by Earth-based telescopes. Detailed characterization of altered basaltic tephra on Mauna Kea have identified a variety of alteration phases including allophane, npOx, hisingerite, jarosite, alunite, hematite, goethite, ferrihydrite, halloysite, kaolinite, smectite, and zeolites. The presence of npOx and other Fe-bearing minerals (jarosite, hematite, goethite) was confirmed by the M ssbauer Spectrometer onboard the Mars Exploration Rovers. Although the presence of allophane has not been definitely identified on Mars robotic missions, chemical analysis by the Spirit and Opportunity rovers and thermal infrared spectral orbital measurements suggest the presence of allophane or allophane-like phases on Mars. SRO phases form under a variety of environmental conditions on Earth ranging from cold and arid to warm and humid, including hydrothermal conditions. The formation of SRO aluminosilicates such as allophane (and crystalline halloysite) from basaltic material is controlled by several key factors including activity of water, extent of leaching, Si activity in solution, and available Al. Generally, a low leaching index (e.g., wet-dry cycles) and slightly acidic to alkaline conditions are necessary. NpOx generally form under aqueous oxidative weathering conditions, although thermal oxidative alteration may occasional be involved. The style of aqueous alteration (hydrolytic vs. acid sulfate) impacts which phases will form (e.g., oxides, oxysulfates, and oxyhydroxides). Knowledge on the formation processes of SRO phases in basaltic materials on Earth has allowed significant enhancement in our understanding of the aqueous processes at work on Mars. The 2011 Mars Science Laboratory (MSL) will provide an instrument suite that should improve our understanding of the mineralogical and chemical compositions of SRO phases. CheMin is an X-ray diffraction instrument that may provide broad X-ray diffraction peaks for SRO phases; e.g., broad peaks around 0.33 and 0.23 nm for allophane. Sample Analysis at Mars (SAM) heats samples and detects evolved gases of volatile-bearing phases including SRO phases (i.e., carbonates, sulfates, hydrated minerals). The Alpha Particle X-ray Spectrometer (APXS) and ChemCam element analyzers will provide chemical characterization of samples. The identification of SRO phases in surface materials on MSL will be challenging due to their nanocrystalline properties; their detection and identification will require utilizing the MSL instrument suite in concert. Ultimately, sample return missions will be required to definitively identify and fully characterize SRO minerals with state-of-the-art laboratory instrumentation back on Earth.

Continuous-flow ultrasound assisted oxidative desulfurization (UAOD) process: An efficient diesel treatment by injection of the aqueous phase.

PubMed

Rahimi, Masoud; Shahhosseini, Shahrokh; Movahedirad, Salman

2017-11-01

A new continuous-flow ultrasound assisted oxidative desulfurization (UAOD) process was developed in order to decrease energy and aqueous phase consumption. In this process the aqueous phase is injected below the horn tip leading to enhanced mixing of the phases. Diesel fuel as the oil phase with sulfur content of 1550ppmw and an appropriate mixture of hydrogen peroxide and formic acid as the aqueous phase were used. At the first step, the optimized condition for the sulfur removal has been obtained in the batch mode operation. Hence, the effect of more important oxidation parameters; oxidant-to-sulfur molar ratio, acid-to-sulfur molar ratio and sonication time were investigated. Then the optimized conditions were obtained using Response Surface Methodology (RSM) technique. Afterwards, some experiments corresponding to the best batch condition and also with objective of minimizing the residence time and aqueous phase to fuel volume ratio have been conducted in a newly designed double-compartment reactor with injection of the aqueous phase to evaluate the process in a continuous flow operation. In addition, the effect of nozzle diameter has been examined. Significant improvement on the sulfur removal was observed specially in lower sonication time in the case of dispersion method in comparison with the conventional contact between two phases. Ultimately, the flow pattern induced by ultrasonic device, and also injection of the aqueous phase were analyzed quantitatively and qualitatively by capturing the sequential images. Copyright © 2017 Elsevier B.V. All rights reserved.

Sol-gel synthesis and adsorption properties of mesoporous manganese oxide

NASA Astrophysics Data System (ADS)

Ivanets, A. I.; Kuznetsova, T. F.; Prozorovich, V. G.

2015-03-01

Sol-gel synthesis of mesoporous xerogels of manganese oxide with different phase compositions has been performed. The manganese oxide sols were obtained by redox reactions of potassium permanganate with hydrogen peroxide or manganese(II) chloride in aqueous solutions. The isotherms of the low-temperature adsorption-desorption of nitrogen with manganese oxide xerogels treated at 80, 200, 400, and 600°C were measured. The samples were studied by electron microscopy and thermal and XRD analysis. The phase transformation and the changes in the adsorption and capillary-condensation properties of manganese oxide were shown to depend on the sol synthesis conditions and the temperature of the thermal treatment of the gel. The X-ray amorphous samples heated at 80°C were shown to have low values of the specific surface; at higher temperatures, the xerogel crystallized into mixed phases with various compositions and its surface area increased at 200-400°C and decreased at 600°C.

Responsive copolymers for enhanced petroleum recovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCormick, Charles; Hester, Roger

The objectives of this work were to: synthesize responsive, amphiphilic systems; characterize molecular structure and solution behavior; measure rheological properties of the aqueous fluids including behavior in fixed geometry flow profiles and beds; and to tailor final polymer compositions for in situ rheology control under simulated reservoir conditions. This report focuses on the first phase of the research emphasizing synthesis and the development of photophysical techniques and rheological means of following segmental organization at the structural level.

Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical

DOE PAGES

Yu, L.; Smith, J.; Laskin, A.; ...

2014-12-23

Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the reactions of phenol (compound with formula C 6H 5OH)), guaiacol (2-methoxyphenol), and syringol (2,6-dimethoxyphenol) with two major aqueous-phase oxidants – the triplet excited states of an aromatic carbonyl ( 3C *) and hydroxyl radical (· OH). We thoroughly characterize the low-volatility species produced from these reactions and interpret their formation mechanisms using aerosol mass spectrometry (AMS), nanospray desorption electrospray ionization mass spectrometry (nano-DESI MS), and ion chromatography (IC). Amore » large number of oxygenated molecules are identified, including oligomers containing up to six monomer units, functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acid anions (e.g., formate, acetate, oxalate, and malate). The average atomic oxygen-to-carbon (O / C) ratios of phenolic aqSOA are in the range of 0.85–1.23, similar to those of low-volatility oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA compositions are overall similar for the same precursor, but the reactions mediated by 3C * are faster than · OH-mediated reactions and produce more oligomers and hydroxylated species at the point when 50% of the phenolic compound has reacted. Profiles determined using a thermodenuder indicate that the volatility of phenolic aqSOA is influenced by both oligomer content and O / C ratio. In addition, the aqSOA shows enhanced light absorption in the UV–visible region, suggesting that aqueous-phase reactions of phenols may contribute to formation of secondary brown carbon in the atmosphere, especially in regions influenced by biomass burning.« less

Comparison of Methods for Predicting the Compositional Dependence of the Density and Refractive Index of Organic-Aqueous Aerosols.

PubMed

Cai, Chen; Miles, Rachael E H; Cotterell, Michael I; Marsh, Aleksandra; Rovelli, Grazia; Rickards, Andrew M J; Zhang, Yun-Hong; Reid, Jonathan P

2016-08-25

Representing the physicochemical properties of aerosol particles of complex composition is of crucial importance for understanding and predicting aerosol thermodynamic, kinetic, and optical properties and processes and for interpreting and comparing analysis methods. Here, we consider the representations of the density and refractive index of aqueous-organic aerosol with a particular focus on the dependence of these properties on relative humidity and water content, including an examination of the properties of solution aerosol droplets existing at supersaturated solute concentrations. Using bulk phase measurements of density and refractive index for typical organic aerosol components, we provide robust approaches for the estimation of these properties for aerosol at any intermediate composition between pure water and pure solute. Approximately 70 compounds are considered, including mono-, di- and tricarboxylic acids, alcohols, diols, nitriles, sulfoxides, amides, ethers, sugars, amino acids, aminium sulfates, and polyols. We conclude that the molar refraction mixing rule should be used to predict the refractive index of the solution using a density treatment that assumes ideal mixing or, preferably, a polynomial dependence on the square root of the mass fraction of solute, depending on the solubility limit of the organic component. Although the uncertainties in the density and refractive index predictions depend on the range of subsaturated compositional data available for each compound, typical errors for estimating the solution density and refractive index are less than ±0.1% and ±0.05%, respectively. Owing to the direct connection between molar refraction and the molecular polarizability, along with the availability of group contribution models for predicting molecular polarizability for organic species, our rigorous testing of the molar refraction mixing rule provides a route to predicting refractive indices for aqueous solutions containing organic molecules of arbitrary structure.

Elephant Moraine 96029, a very mildly aqueously altered and heated CM carbonaceous chondrite: Implications for the drivers of parent body processing

NASA Astrophysics Data System (ADS)

Lee, Martin R.; Lindgren, Paula; King, Ashley J.; Greenwood, Richard C.; Franchi, Ian A.; Sparkes, Robert

2016-08-01

Elephant Moraine (EET) 96029 is a CM carbonaceous chondrite regolith breccia with evidence for unusually mild aqueous alteration, a later phase of heating and terrestrial weathering. The presence of phyllosilicates and carbonates within chondrules and the fine-grained matrix indicates that this meteorite was aqueously altered in its parent body. Features showing that water-mediated processing was arrested at a very early stage include a matrix with a low magnesium/iron ratio, chondrules whose mesostasis contains glass and/or quench crystallites, and a gehlenite-bearing calcium- and aluminium-rich inclusion. EET 96029 is also rich in Fe,Ni metal relative to other CM chondrites, and more was present prior to its partial replacement by goethite during Antarctic weathering. In combination, these properties indicate that EET 96029 is one of the least aqueously altered CMs yet described (CM2.7) and so provides new insights into the original composition of its parent body. Following aqueous alteration, and whilst still in the parent body regolith, the meteorite was heated to ∼400-600 °C by impacts or solar radiation. Heating led to the amorphisation and dehydroxylation of serpentine, replacement of tochilinite by magnetite, loss of sulphur from the matrix, and modification to the structure of organic matter that includes organic nanoglobules. Significant differences between samples in oxygen isotope compositions, and water/hydroxyl contents, suggests that the meteorite contains lithologies that have undergone different intensities of heating. EET 96029 may be more representative of the true nature of parent body regoliths than many other CM meteorites, and as such can help interpret results from the forthcoming missions to study and return samples from C-complex asteroids.

Organic contaminant separator

DOEpatents

Del Mar, P.

1993-12-28

A process is presented of sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium by (a) passing an initial aqueous medium including a minor amount of the organic contaminant through a composite tube comprised of a blend of a polyolefin and a polyester, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit the organic contaminant to adhere to the composite tube, (b) passing a solvent through the composite tube. The solvent is capable of separating the adhered organic contaminant from the composite tube. Further, an extraction apparatus is presented for sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium. The apparatus includes a composite tube comprised of a blend of a polyolefin and a polyester. The composite tube has an internal diameter of from about 0.1 to about 2.0 millimeters and has sufficient length to permit an organic contaminant contained within an aqueous medium passed therethrough to adhere to the composite tube. 2 figures.

The effect of the type of HA on the degradation of PLGA/HA composites.

PubMed

Naik, Ashutosh; Shepherd, David V; Shepherd, Jennifer H; Best, Serena M; Cameron, Ruth E

2017-01-01

The aim of this study is to explore the importance of the potentially competing effects of buffering effects of the calcium phosphate filler and particle-mediated water sorption on the degradation products of poly(d,l lactide-co-glycolide (50:50))(PLGA)/hydroxyapatite(HA) composites. Further the influence of type of HA on the mechanical properties of the composites was investigated. Phase pure HA was synthesised via a reaction between aqueous solutions of calcium hydroxide and orthophosphoric acid. The powder produced was either used as produced (uncalcined) or calcined in air or calcined in a humidified argon atmosphere. An in-vitro degradation study was carried out in phosphate buffered saline (PBS). The results obtained indicated that the degradation rate of the composite might be better understood if both the buffering effects and the rate of water sorption by the composites are considered. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of Complex Fluids in Lignocellulose Processing

NASA Astrophysics Data System (ADS)

Carrillo Lugo, Carlos A.

Complex fluids such as emulsions, microemulsions and foams, have been used for different applications due to the multiplicity of properties they possess. In the present work, such fluids are introduced as effective media for processing lignocellulosic biomass. A demonstration of the generic benefits of complex fluids is presented to enhance biomass impregnation, to facilitate pretreatment for fiber deconstruction and to make compatible cellulose fibrils with hydrophobic polymers during composite manufacture. An improved impregnation of woody biomass was accomplished by application of water-continuous microemulsions. Microemulsions with high water content, > 85%, were formulated and wood samples were impregnated by wicking and capillary flooding at atmospheric pressure and temperature. Formulations were designed to effectively impregnate different wood species during shorter times and to a larger extent compared to the single components of the microemulsions (water, oil or surfactant solutions). The viscosity of the microemulsions and their interactions with cell wall constituents in fibers were critical to define the extent of impregnation and solubilization. The relation between composition and formulation variables and the extent of microemulsion penetration in different woody substrates was studied. Formulation variables such as salinity content of the aqueous phase and type of surfactant were elucidated. Likewise, composition variables such as the water-to-oil ratio and surfactant concentration were investigated. These variables affected the characteristics of the microemulsion and determined their effectiveness in wood treatment. Also, the interactions between the surfactant and the substrate had an important contribution in defining microemulsion penetration in the capillary structure of wood. Microemulsions as an alternative pretreatment for the manufacture of cellulose nanofibrils (CNFs) was also studied. Microemulsions were applied to pretreat lignin-free and lignin-containing fibers obtained from various processes. Incorporation of active agents in the microemulsion facilitated fiber pretreatment before deconstruction via grinding and microfluidization. The energy consumed during the manufacture of cellulose nanofibrils was reduced by up to 55 and 32% in the case of lignin-containing and lignin-free fibers. Moreover, such pre-treatment did not affect negatively the mechanical properties of films prepared with the produced CNF. CNF was also used to enhance the stability of normal and multiple emulsions of the water-in-oil-in-water (W/O/W) type and to prevent their creaming. This was achieved by the marked increase in viscosity of the aqueous phase in the presence CNF. Finally, water-continuous emulsions were used to prepare nanocomposite fibers containing polystyrene and CNF. The morphology of composite fibers obtained after electrospinning of emulsions incorporating polystyrene and CNF was affected by parameters such the concentration of surfactant additives present in the microemulsion and the conductivity of the aqueous phase. Overall, emulsions and microemulsions are presented as a convenient platform to improve the compatibility between polymers of different hydrophilicity, to facilitate their processing and integration in composites.

Tryptophan and tryptophan-like substances in cloud water: Occurrence and photochemical fate

NASA Astrophysics Data System (ADS)

Bianco, Angelica; Passananti, Monica; Deguillaume, Laurent; Mailhot, Gilles; Brigante, Marcello

2016-07-01

This work investigates the occurrence and photochemical behaviour of tryptophan (TRP) in the cloud aqueous phase. The concentrations of tryptophan, TRYptophan LIke Substances (TRYLIS) and HUmic LIke Substances (HULIS) in real cloud water, collected between October 2013 and November 2014 at the top of the puy de Dôme station, were determined using the Excitation-Emission-Matrix (EEM) technique. The amount of free and complexed tryptophan (TRP) up to 10-7 M in cloud aqueous phase was quantified by HPLC-UV-fluorescence analysis, and its photoreactivity under sun-simulated conditions was investigated in synthetic water samples mimicking cloud aqueous phase compositions (oceanic and continental origins). TRP undergoes direct photolysis, and its degradation is enhanced in the presence of naturally occurring species able to photo-generate hydroxyl radicals (HOrad). The polychromatic quantum yield of TRP (ϕ290-340nmTRP) is estimated to be 8.37 × 10-4 between 290 and 340 nm, corresponding to the degradation rate (RTRPd) of 1.29 × 10-11 M s-1 under our irradiation conditions. The degradation is accelerated up to 3.65 × 10-10 and 8.26 × 10-10 M s-1 in synthetic oceanic and continental cloud water samples doped with 100 μM hydrogen peroxide, respectively. Hydroxyl radical-mediated transformation leads to the generation of different functionalized and oxidized products, as well as small carboxylic acids, such as formate and acetate. Moreover, fluorescent signals of irradiated solutions indicate the formation of HULIS.

Green polymer chemistry: investigating the mechanism of radical ring-opening redox polymerization (R3P) of 3,6-dioxa-1,8-octanedithiol (DODT).

PubMed

Rosenthal-Kim, Emily Q; Puskas, Judit E

2015-04-13

The mechanism of the new Radical Ring-opening Redox Polymerization (R3P) of 3,6-dioxa-1,8-octanedithiol (DODT) by triethylamine (TEA) and dilute H2O2 was investigated. Scouting studies showed that the formation of high molecular weight polymers required a 1:2 molar ratio of DODT to TEA and of DODT to H2O2. Further investigation into the chemical composition of the organic and aqueous phases by 1H-NMR spectroscopy and mass spectrometry demonstrated that DODT is ionized by two TEA molecules (one for each thiol group) and thus transferred into the aqueous phase. The organic phase was found to have cyclic disulfide dimers, trimers and tetramers. Dissolving DODT and TEA in water before the addition of H2O2 yielded a polymer with Mn = 55,000 g/mol, in comparison with Mn = 92,000 g/mol when aqueous H2O2 was added to a DODT/TEA mixture. After polymer removal, MALDI-ToF MS analysis of the residual reaction mixtures showed only cyclic oligomers remaining. Below the LCST for TEA in water, 18.7 °C, the system yielded a stable emulsion, and only cyclic oligomers were found. Below DODT/TEA and H2O2 1:2 molar ratio mostly linear oligomers were formed, with <20% cyclic oligomers. The findings support the proposed mechanism of R3P.

A partially coupled, fraction-by-fraction modelling approach to the subsurface migration of gasoline spills

NASA Astrophysics Data System (ADS)

Fagerlund, F.; Niemi, A.

2007-01-01

The subsurface spreading behaviour of gasoline, as well as several other common soil- and groundwater pollutants (e.g. diesel, creosote), is complicated by the fact that it is a mixture of hundreds of different constituents, behaving differently with respect to e.g. dissolution, volatilisation, adsorption and biodegradation. Especially for scenarios where the non-aqueous phase liquid (NAPL) phase is highly mobile, such as for sudden spills in connection with accidents, it is necessary to simultaneously analyse the migration of the NAPL and its individual components in order to assess risks and environmental impacts. Although a few fully coupled, multi-phase, multi-constituent models exist, such models are highly complex and may be time consuming to use. A new, somewhat simplified methodology for modelling the subsurface migration of gasoline while taking its multi-constituent nature into account is therefore introduced here. Constituents with similar properties are grouped together into eight fractions. The migration of each fraction in the aqueous and gaseous phases as well as adsorption is modelled separately using a single-constituent multi-phase flow model, while the movement of the free-phase gasoline is essentially the same for all fractions. The modelling is done stepwise to allow updating of the free-phase gasoline composition at certain time intervals. The output is the concentration of the eight different fractions in the aqueous, gaseous, free gasoline and solid phases with time. The approach is evaluated by comparing it to a fully coupled multi-phase, multi-constituent numerical simulator in the modelling of a typical accident-type spill scenario, based on a tanker accident in northern Sweden. Here the PCFF method produces results similar to those of the more sophisticated, fully coupled model. The benefit of the method is that it is easy to use and can be applied to any single-constituent multi-phase numerical simulator, which in turn may have different strengths in incorporating various processes. The results demonstrate that the different fractions have significantly different migration behaviours and although the methodology involves some simplifications, it is a considerable improvement compared to modelling the gasoline constituents completely individually or as one single mixture.

Characteristics of regenerated nanocellulosic fibers from cellulose dissolution in aqueous solutions for wood fiber/polypropylene composites

Treesearch

Sangyeob Lee; Hui Pan; Chung Y. Hse; Alfred R. Gunasekaran; Todd F. Shupe

2014-01-01

The effects of aqueous solutions were evaluated on the properties of regenerated cellulosic nanofibers prepared from pure cellulose fibers in various formulations of aqueous solutions. Thermoplastic composites were prepared with reinforcement of the regenerated cellulosic nanofibers. The regenerated cellulosic fibers from cellulosic woody biomass were obtained from...

A method for preparing ferric activated carbon composites adsorbents to remove arsenic from drinking water.

PubMed

Zhang, Qiao Li; Lin, Y C; Chen, X; Gao, Nai Yun

2007-09-30

Iron oxide/activated carbon (FeO/AC) composite adsorbent material, which was used to modify the coal-based activated carbon (AC) 12 x 40, was prepared by the special ferric oxide microcrystal in this study. This composite can be used as the adsorbent to remove arsenic from drinking water, and Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Then, the arsenic desorption can subsequently be separated from the medium by using a 1% aqueous NaOH solution. The apparent characters and physical chemistry performances of FeO/AC composite were investigated by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Batch and column adsorption experiments were carried out to investigate and compare the arsenic removal capability of the prepared FeO/AC composite material and virgin activated carbon. It can be concluded that: (1) the main phase present in this composite are magnetite (Fe(3)O(4)), maghemite (gamma-Fe(2)O(3)), hematite (alpha-Fe(2)O(3)) and goethite (alpha-FeO(OH)); (2) the presence of iron oxides did not significantly affect the surface area or the pore structure of the activated carbon; (3) the comparisons between the adsorption isotherms of arsenic from aqueous solution onto the composite and virgin activated carbon showed that the FeO/AC composite behave an excellent capacity of adsorption arsenic than the virgin activated carbon; (4) column adsorption experiments with FeO/AC composite adsorbent showed that the arsenic could be removed to below 0.01 mg/L within 1250 mL empty bed volume when influent concentration was 0.5mg/L.

Gel-like double-emulsion droplets

NASA Astrophysics Data System (ADS)

Guzowski, Jan; Korczyk, Piotr; Garstecki, Piotr; Stone, Howard

2015-11-01

We experimentally study the problem of packing of micro-droplets inside a droplet of another immiscible liquid phase. We use microfluidics to encapsulate multiple monodisperse aqueous segments inside a drop of oil. For small numbers N (N<10) of the aqueous droplets and at their volume fraction in oil exceeding the close-packing threshold we observe multiple metastable structures with well-defined point-group symmetries. We attribute the observed metastability to the deformability of the droplets which leads to effective many-body interactions and energy barriers for rearrangement. By changing the composition of the oil phase we find that when the surface tensions of the droplets and of the encapsulating phase are comparable, the energy barriers are high enough to trap elongated structures or even linear chains, independently of N. However, when the surface tension of the encapsulating phase is much larger than that of the droplets, non-spherical morphologies are stable only at sufficiently high N. In such a case multiple internal interfaces can hold stresses and prevent relaxation of the global deformations which leads to a plastic, gel-like behavior. Our findings can serve as guidelines for synthesis of functional particles as well as for designing biomimetic materials, e.g. for tissue engineering. J.G. acknowledges financial support from Polish Ministry of Science provided within the framework Mobility Plus.

Electrodeposition of nickel-iridium alloy films from aqueous solutions

NASA Astrophysics Data System (ADS)

Wu, Wangping; Jiang, Jinjin; Jiang, Peng; Wang, Zhizhi; Yuan, Ningyi; Ding, Jianning

2018-03-01

Nickel-iridium (Ni-Ir) alloy films were electrodeposited from aqueous solutions on copper substrates under galvanostatic conditions. The effects of bath composition and deposition time on the faradaic efficiency (FE), partial current densities, chemical composition, morphology and crystallographic structure of the films were studied. The results show that the Ni-Ir alloys with Ir content as high as 37 at% and FE as high as 44% were obtained. Increase in concentration of citric acid had little or no effect on the composition of the alloys, but resulted in a significant decrease in FE and partial current densities of Ni and Ir. The FE and the partial current density of Ni slightly decreased with increasing Ir3+ concentration, however, Ir content increased while partial current density of Ir remained stable. The increase of Ni2+ concentration could result in the increase of the FE and the rate of Ni-Ir deposition, and even no cracks formed on the surface. The surface average roughness and root mean square roughness of the film were 6.8 ± 0.3 nm and 5.4 ± 0.3 nm, respectively. The mixture phases contained significant amounts of Ni oxides and a small amount of metallic Ni, Ir and Ir oxides on the surface. After argon ion sputter cleaning, the film was mainly composed of metallic Ni and Ir. The film consisted of the amorphous and nanocrystalline phases. The Ni content in the deposits was higher than that in the electrolyte, the co-deposition of Ni-Ir alloy was a normal deposition.

Development of an alkaline/surfactant/polymer compositional reservoir simulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhuyan, D.

1989-01-01

The mathematical formulation of a generalized three-dimensional compositional reservoir simulator for high-pH chemical flooding processes is presented in this work. The model assumes local thermodynamic equilibrium with respect to both reaction chemistry and phase behavior and calculates equilibrium electrolyte and phase compositions as a function of time and position. The reaction chemistry considers aqueous electrolytic chemistry, precipitation/dissolution of minerals, ion exchange reactions on matrix surface, reaction of acidic components of crude oil with the bases in the aqueous solution and cation exchange reactions with the micelles. The simulator combines this detailed reaction chemistry associated with these processes with the extensivemore » physical and flow property modeling schemes of an existing chemical flood simulator (UTCHEM) to model the multiphase, multidimensional displacement processes. The formulation of the chemical equilibrium model is quite general and is adaptable to simulate a variety of chemical descriptions. In addition to its use in the simulation of high-pH chemical flooding processes, the model will find application in the simulation of other reactive flow problems like the ground water contamination, reinjection of produced water, chemical waste disposal, etc. in one, two or three dimensions and under multiphase flow conditions. In this work, the model is used to simulate several hypothetical cases of high-pH chemical floods, which include cases from a simple alkaline preflush of a micellar/polymer flood to surfactant enhanced alkaline-polymer flooding and the results are analyzed. Finally, a few published alkaline, alkaline-polymer and surfactant-alkaline-polymer corefloods are simulated and compared with the experimental results.« less

Biphasic catalysis in water/carbon dioxide micellar systems

DOEpatents

Jacobson, Gunilla B.; Tumas, William; Johnston, Keith P.

2002-01-01

A process is provided for catalyzing an organic reaction to form a reaction product by placing reactants and a catalyst for the organic reaction, the catalyst of a metal complex and at least one ligand soluble within one of the phases of said aqueous biphasic system, within an aqueous biphasic system including a water phase, a dense phase fluid, and a surfactant adapted for forming an emulsion or microemulsion within the aqueous biphasic system, the reactants soluble within one of the phases of the aqueous biphasic system and convertible in the presence of the catalyst to a product having low solubility in the phase in which the catalyst is soluble; and, maintaining the aqueous biphasic system under pressures, at temperatures, and for a period of time sufficient for the organic reaction to occur and form the reaction product and to maintain sufficient density on the dense phase fluid, the reaction product characterized as having low solubility in the phase in which the catalyst is soluble.

Effect of Coriolis force on counter-current chromatographic separation by centrifugal partition chromatography.

PubMed

Ikehata, Jun-Ichi; Shinomiya, Kazufusa; Kobayashi, Koji; Ohshima, Hisashi; Kitanaka, Susumu; Ito, Yoichiro

2004-02-06

The effect of Coriolis force on the counter-current chromatographic separation was studied using centrifugal partition chromatography (CPC) with four different two-phase solvent systems including n-hexane-acetonitrile (ACN); tert-butyl methyl ether (MtBE)-aqueous 0.1% trifluoroacetic acid (TFA) (1:1); MtBE-ACN-aqueous 0.1% TFA (2:2:3); and 12.5% (w/w) polyethylene glycol (PEG) 1000-12.5% (w/w) dibasic potassium phosphate. Each separation was performed by eluting either the upper phase in the ascending mode or the lower phase in the descending mode, each in clockwise (CW) and counterclockwise column rotation. Better partition efficiencies were attained by the CW rotation in both mobile phases in all the two-phase solvent systems examined. The mathematical analysis also revealed the Coriolis force works favorably under the CW column rotation for both mobile phases. The overall results demonstrated that the Coriolis force produces substantial effects on CPC separation in both organic-aqueous and aqueous-aqueous two-phase systems.

Reversible, on-demand generation of aqueous two-phase microdroplets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collier, Charles Patrick; Retterer, Scott Thomas; Boreyko, Jonathan Barton

The present invention provides methods of on-demand, reversible generation of aqueous two-phase microdroplets core-shell microbeads, microparticle preparations comprising the core-shell microbeads, and drug delivery formulation comprising the microparticle preparations. Because these aqueous microdroplets have volumes comparable to those of cells, they provide an approach to mimicking the dynamic microcompartmentation of biomaterial that naturally occurs within the cytoplasm of cells. Hence, the present methods generate femtoliter aqueous two-phase droplets within a microfluidic oil channel using gated pressure pulses to generate individual, stationary two-phase microdroplets with a well-defined time zero for carrying out controlled and sequential phase transformations over time. Reversible phasemore » transitions between single-phase, two-phase, and core-shell microbead states are obtained via evaporation-induced dehydration and water rehydration.« less

Gas-Phase Functionalization of Macroscopic Carbon Nanotube Fiber Assemblies: Reaction Control, Electrochemical Properties, and Use for Flexible Supercapacitors.

PubMed

Iglesias, Daniel; Senokos, Evgeny; Alemán, Belén; Cabana, Laura; Navío, Cristina; Marcilla, Rebeca; Prato, Maurizio; Vilatela, Juan J; Marchesan, Silvia

2018-02-14

The assembly of aligned carbon nanotubes (CNTs) into fibers (CNTFs) is a convenient approach to exploit and apply the unique physico-chemical properties of CNTs in many fields. CNT functionalization has been extensively used for its implementation into composites and devices. However, CNTF functionalization is still in its infancy because of the challenges associated with preservation of CNTF morphology. Here, we report a thorough study of the gas-phase functionalization of CNTF assemblies using ozone which was generated in situ from a UV source. In contrast with liquid-based oxidation methods, this gas-phase approach preserves CNTF morphology, while notably increasing its hydrophilicity. The functionalized material is thoroughly characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. Its newly acquired hydrophilicity enables CNTF electrochemical characterization in aqueous media, which was not possible for the pristine material. Through comparison of electrochemical measurements in aqueous electrolytes and ionic liquids, we decouple the effects of functionalization on pseudocapacitive reactions and quantum capacitance. The functionalized CNTF assembly is successfully used as an active material and a current collector in all-solid supercapacitor flexible devices with an ionic liquid-based polymer electrolyte.

Phase equilibria of the magnesium sulfate-water system to 4 kbars

NASA Technical Reports Server (NTRS)

Hogenboom, D. L.; Kargel, J. S.; Ganasan, J. P.; Lee, L.

1993-01-01

Magnesium sulfate is the most abundant salt in carbonaceous chondrites, and it may be important in the low-temperature igneous evolution and aqueous differentiation of icy satellites and large chondritic asteroids. Accordingly, we are investigating high-pressure phase equilibria in MgSO4-H2O solutions under pressures up to four kbars. An initial report was presented two years ago. This abstract summarizes our results to date including studies of solutions containing 15.3 percent, 17 percent, and 22 percent MgSO4. Briefly, these results demonstrate that increasing pressure causes the eutectic and peritectic compositions to shift to much lower concentrations of magnesium sulfate, and the existence of a new low-density phase of magnesium sulfate hydrate.

Anomalous behavior of poly(ethylene glycol) p-tert-octylphenyl ether (Triton X-100) in the water-cyclohexane system

NASA Astrophysics Data System (ADS)

Chernysheva, M. G.; Tyasto, Z. A.; Badun, G. A.

2009-02-01

The distribution of Triton X-100 nonionic surfactant in the water-cyclohexane system was investigated by the scintillating phase method. It was shown that an increase in the distribution coefficient as the volume ratio between the aqueous and organic phases grew was explained by the presence in Triton X-100 of homologues with different numbers of ethoxyethyl groups and with the distribution coefficients between the phases different by many times. For the real composition of Triton X-100, distribution coefficients of components of the surfactant were estimated, and the behavior of the surfactant in the system under consideration was simulated; the results were in close agreement with the experimental data.

Nighttime aqueous-phase secondary organic aerosols in Los Angeles and its implication for fine particulate matter composition and oxidative potential

NASA Astrophysics Data System (ADS)

Saffari, Arian; Hasheminassab, Sina; Shafer, Martin M.; Schauer, James J.; Chatila, Talal A.; Sioutas, Constantinos

2016-05-01

Recent investigations suggest that aqueous phase oxidation of hydrophilic organic compounds can be a significant source of secondary organic aerosols (SOA) in the atmosphere. Here we investigate the possibility of nighttime aqueous phase formation of SOA in Los Angeles during winter, through examination of trends in fine particulate matter (PM2.5) carbonaceous content during two contrasting seasons. Distinctive winter and summer trends were observed for the diurnal variation of organic carbon (OC) and secondary organic carbon (SOC), with elevated levels during the nighttime in winter, suggesting an enhanced formation of SOA during that period. The nighttime ratio of SOC to OC was positively associated with the relative humidity (RH) at high RH levels (above 70%), which is when the liquid water content of the ambient aerosol would be high and could facilitate dissolution of hydrophilic primary organic compounds into the aqueous phase. Time-integrated collection and analysis of wintertime particles at three time periods of the day (morning, 6:00 a.m.-9:00 a.m.; afternoon, 11:00 a.m.-3:00 p.m.; night, 8:00 p.m.-4:00 a.m.) revealed higher levels of water soluble organic carbon (WSOC) and organic acids during the night and afternoon periods compared to the morning period, indicating that the SOA formation in winter continues throughout the nighttime. Furthermore, diurnal trends in concentrations of semi-volatile organic compounds (SVOCs) from primary emissions showed that partitioning of SVOCs from the gas to the particle phase due to the decreased nighttime temperatures cannot explain the substantial OC and SOC increase at night. The oxidative potential of the collected particles (quantified using a biological macrophage-based reactive oxygen species assay, in addition to the dithiothreitol assay) was comparable during afternoon and nighttime periods, but higher (by at least ∼30%) compared to the morning period, suggesting that SOA formation processes possibly enhance the toxicity of the ambient particles compared to mobile-source dominated primary emissions in the Los Angeles area.

Characterizing Fullerene Nanoparticles in Aqueous Suspensions

EPA Science Inventory

Studies have indicated that fullerenes can form stable colloidal suspensions in water when introduced to the aqueous phase through solvent exchange, sonication, or extended mixing. The colloidal suspensions created using these techniques have effective aqueous phase concentratio...

Effects of NO(y) aging on the dehydration dynamics of model sea spray aerosol.

PubMed

Woods, Ephraim; Heylman, Kevin D; Gibson, Amanda K; Ashwell, Adam P; Rossi, Sean R

2013-05-23

The reactions of NO(y) species in the atmosphere with sea spray aerosol replace halogen anions with nitrate. These experiments show the effect of increasing the nitrate content of model sea spray aerosol particles on the morphology changes and the phase transitions driven by changes in relative humidity (RH). The components of the model particles include H2O, Na+, Mg2+, Cl-, NO3-, and SO4(2-). Tandem differential mobility analyzer (TDMA) measurements yield the water content and efflorescence relative humidity (ERH) of these particles, and probe molecule spectroscopic measurements reveal subsequent phase transitions and partially characterize the salt composition on the surface of dry particles. The results show three effects of increasing the nitrate composition: decreasing the EFH (46 to 29%), production of a metastable aqueous layer on the surface of effloresced particles, and decreasing the sulfate content near the surface of dry particles. For the mixtures studied here, the initial crystallization event forms a core of NaCl. For particles that contain a substantial metastable aqueous layer following efflorescence, probe molecule spectroscopy shows a second crystallization at a lower RH. This subsequent phase transition is likely the formation of Na2SO4. Homogeneous nucleation theory (HNT) using a semiempirical formulation predicts the ERH of all mixtures within 2.0% RH, with a mean absolute deviation of 1.0%. The calculations suggest that structures associated with highly concentrated or supersaturated magnesium ions strongly affect the interfacial tension between the NaCl crystal nucleus and the droplet from which it forms.

H 2OCH 4NaClCO 2 inclusions from the footwall contact of the Tanco granitic pegmatite: Estimates of internal pressure and composition from microthermometry, laser Raman spectroscopy, and gas chromatography

NASA Astrophysics Data System (ADS)

Thomas, A. V.; Pasteris, J. D.; Bray, C. J.; Spooner, E. T. C.

1990-03-01

Fluid inclusions in tourmaline and quartz from the footwall contact of the Tanco granitic pegmatite, S.E. Manitoba were studied using microthermometry (MT), laser Raman spectroscopy (LRS) and gas chromatography (GC). CH 4-bearing, aqueous inclusions occur in metasomatic tourmaline of the footwall amphibolite contact. The internal pressures estimated from MT are lower than those obtained from LRS (mean difference = 54 ± 19 bars). The difference is probably due to errors in the measurement of Th CH 4 (V) and to the presence of clathrate at Th CH 4 (V) into which CO 2 had been preferentially partitioned. LRS estimates of pressure (125-184 bars) are believed to be more accurate. Aqueous phase salinities based on LRS estimates of pressure are higher than those derived using the data from MT: 10-20 eq. wt% NaCl. The composition of the inclusions determined by GC bulk analysis is 97.3 mol% H 2O, 2.2 mol% CH 4, 0.4 mol% CO 2, 250 ppm C 2H 6, 130 ppm N 2, 33 ppm C 3H 8, 11 ppm C 2H 4, and 3 ppm C 3H 6, plus trace amounts of C 4 hydrocarbons. The composition is broadly similar to that calculated from MT (92% H 2O and 8% CH 4, with 7 eq. wt% NaCl dissolved in the aqueous phase and 2 mol% CO 2 dissolved in the CH 4 phase), as expected due to the dominance of a single generation of inclusions in the tourmaline. However, two important differences in composition are: (i) the CH 4 to CO 2 ratio of this fluid determined by GC is 5.33, which is significantly lower than that indicated by MT (49.0); and (ii) the H 2O content estimated from MT is 92 mol% compared to 98 mol% from GC. GC analyses may have been contaminated by the presence of secondary inclusions in the tourmaline. However, the rarity of the latter suggests that they cannot be completely responsible for the discrepancy. The differences may be accounted for by the presence of clathrate during measurement of Th CH 4 (critical), which would reduce CO 2 relative to CH 4 in the residual fluid, and by errors in visually estimating vol% H 2O. The compositions of the primary inclusions in tourmaline are unlike any of those found within the pegmatite and indicate that the fluid was externally derived, probably of metamorphic origin. Inclusions in quartz of the border unit of the pegmatite are secondary and are either aqueous (18 to 30 eq. wt% CaCl 2; Th total = 184 ± 14° C) or carbonic. Tm CO 2 for the carbonic inclusions ranges from -57.5 to -65.4°C and is positively correlated with Th CO 2. Analyses of X CH 4 based on LRS agree within 5 mol% of those derived from MT and together indicate a range of compositions from 5 to 50 mol% CH 4 in the CO 2 phase. Bulk analysis by GC gives 99.0 mol% H 2O, 0.6 mol% CO 2, 0.4 mol% CH 4, 160 ppm N 2, 7 ppm C 2H 6, 4 ppm C 3H 8, and 2 ppm C 2H 4, with trace amounts of COS (carbonyl sulphide) and C 3H 6. The level of H 2O in the analysis is consistent with the dominance of the aqueous inclusions in these samples, and the CH4: CO2 ratios are consistent with estimates from MT and LRS. The preservation of variable ratios of CH 4:CO 2 in inclusions < 50 μm apart indicates that neither H 2 diffusion out of the inclusions nor reduction of fluids leaving the pegmatite were responsible for the more oxidized chemistries of the border unit inclusions relative to those in the tourmaline of the metasomatised amphibolite. The compositions of the inclusions in the quartz lie between those of the fluid trapped by the tourmaline (externally derived) and the measured composition of a CO 2-bearing pegmatitic fluid, which indicates that the secondary fluids trapped in the border unit quartz were produced by late mixing.

Actinide extraction methods

DOEpatents

Peterman, Dean R [Idaho Falls, ID; Klaehn, John R [Idaho Falls, ID; Harrup, Mason K [Idaho Falls, ID; Tillotson, Richard D [Moore, ID; Law, Jack D [Pocatello, ID

2010-09-21

Methods of separating actinides from lanthanides are disclosed. A regio-specific/stereo-specific dithiophosphinic acid having organic moieties is provided in an organic solvent that is then contacted with an acidic medium containing an actinide and a lanthanide. The method can extend to separating actinides from one another. Actinides are extracted as a complex with the dithiophosphinic acid. Separation compositions include an aqueous phase, an organic phase, dithiophosphinic acid, and at least one actinide. The compositions may include additional actinides and/or lanthanides. A method of producing a dithiophosphinic acid comprising at least two organic moieties selected from aromatics and alkyls, each moiety having at least one functional group is also disclosed. A source of sulfur is reacted with a halophosphine. An ammonium salt of the dithiophosphinic acid product is precipitated out of the reaction mixture. The precipitated salt is dissolved in ether. The ether is removed to yield the dithiophosphinic acid.

Sol-gel synthesis, phase composition, morphological and structural characterization of Ca10(PO4)6(OH)2: XRD, FTIR, SEM, 3D SEM and solid-state NMR studies

NASA Astrophysics Data System (ADS)

Kareiva, Simonas; Klimavicius, Vytautas; Momot, Aleksandr; Kausteklis, Jonas; Prichodko, Aleksandra; Dagys, Laurynas; Ivanauskas, Feliksas; Sakirzanovas, Simas; Balevicius, Vytautas; Kareiva, Aivaras

2016-09-01

Aqueous sol-gel chemistry route based on ammonium-hydrogen phosphate as the phosphorus precursor, calcium acetate monohydrate as source of calcium ions, and 1,2-ethylendiaminetetraacetic acid (EDTA), or 1,2-diaminocyclohexanetetracetic acid (DCTA), or tartaric acid (TA), or ethylene glycol (EG), or glycerol (GL) as complexing agents have been used to prepare calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHAp). The phase transformations, composition, and structural changes in the polycrystalline samples were studied by infrared spectroscopy (FTIR), X-ray powder diffraction analysis (XRD), and scanning electron microscopy (SEM). The local short-range (nano- and mezo-) scale effects in CHAp were studied using solid-state NMR spectroscopy. The spatial 3D data from the SEM images of CHAp samples obtained by TA, EG and GL sol-gel routes were recovered for the first time to our knowledge.

Measurement of Biologically Available Naphthalene in Gas and Aqueous Phases by Use of a Pseudomonas putida Biosensor

PubMed Central

Werlen, Christoph; Jaspers, Marco C. M.; van der Meer, Jan Roelof

2004-01-01

Genetically constructed microbial biosensors for measuring organic pollutants are mostly applied in aqueous samples. Unfortunately, the detection limit of most biosensors is insufficient to detect pollutants at low but environmentally relevant concentrations. However, organic pollutants with low levels of water solubility often have significant gas-water partitioning coefficients, which in principle makes it possible to measure such compounds in the gas rather than the aqueous phase. Here we describe the first use of a microbial biosensor for measuring organic pollutants directly in the gas phase. For this purpose, we reconstructed a bioluminescent Pseudomonas putida naphthalene biosensor strain to carry the NAH7 plasmid and a chromosomally inserted gene fusion between the sal promoter and the luxAB genes. Specific calibration studies were performed with suspended and filter-immobilized biosensor cells, in aqueous solution and in the gas phase. Gas phase measurements with filter-immobilized biosensor cells in closed flasks, with a naphthalene-contaminated aqueous phase, showed that the biosensor cells can measure naphthalene effectively. The biosensor cells on the filter responded with increasing light output proportional to the naphthalene concentration added to the water phase, even though only a small proportion of the naphthalene was present in the gas phase. In fact, the biosensor cells could concentrate a larger proportion of naphthalene through the gas phase than in the aqueous suspension, probably due to faster transport of naphthalene to the cells in the gas phase. This led to a 10-fold lower detectable aqueous naphthalene concentration (50 nM instead of 0.5 μM). Thus, the use of bacterial biosensors for measuring organic pollutants in the gas phase is a valid method for increasing the sensitivity of these valuable biological devices. PMID:14711624

Polymer composites reinforced by locking-in a liquid-crystalline assembly of cellulose nanocrystallites.

PubMed

Tatsumi, Mio; Teramoto, Yoshikuni; Nishio, Yoshiyuki

2012-05-14

An attempt was made to synthesize novel composites comprising poly(2-hydroxyethyl methacrylate) (PHEMA) and cellulose nanocrystallites (CNC) (acid-treated cotton microfibrils) from suspensions of CNC in an aqueous 2-hydroxyethyl methacrylate (HEMA) monomer solution. The starting suspensions (∼5 wt % CNC) separated into an isotropic upper phase and an anisotropic bottom one in the course of quiescent standing. By way of polymerization of HEMA in different phase situations of the suspensions, we obtained films of three polymer composites, PHEMA-CNC(iso), PHEMA-CNC(aniso), and PHEMA-CNC(mix), coming from the isotropic phase, anisotropic phase, and embryonic nonseparating mixture, respectively. All the composites were transparent and, more or less, birefringent under a polarized optical microscope. A fingerprint texture typical of cholesteric liquid crystals of longer pitch spread widely in PHEMA-CNC(aniso) but rather locally appeared in PHEMA-CNC(iso). Any of the CNC incorporations into the PHEMA matrix improved the original thermal and mechanical properties of this amorphous polymer material. In dynamic mechanical measurements, the locking-in of the respective CNC assemblies gave rise to an increase in the glass-state modulus E' of PHEMA as well as a marked suppression of the E'-falling at temperatures higher than T(g) (≈ 110 °C) of the vinyl polymer. It was also observed for the composites that their modulus E' rerose in a range of about 150-190 °C, which was attributable to a secondary cross-linking formation between PHEMA chains mediated by the acidic CNC filler. The mechanical reinforcement effect of the CNC dispersions was ensured in a tensile test, whereby PHEMA-CNC(aniso) was found to surpass the other two composites in stiffness and strength.

Application of a surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for micro-volume based spectrophotometric determination of low level of Cr(VI) ions in aquatic samples.

PubMed

Sobhi, Hamid Reza; Azadikhah, Efat; Behbahani, Mohammad; Esrafili, Ali; Ghambarian, Mahnaz

2018-05-09

A fast, simple, low cost surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for the determination of low level of Cr(VI) ions in several aquatic samples has been developed. Initially, Cr(VI) ions present in the aqueous sample were readily reacted with 1,5‑diphenylcarbazide (DPC) in acidic medium through complexation. Sodium dodecyl sulfate (SDS), as an anionic surfactant, was then employed as an ion-pair agent to convert the cationic complex into the neutral one. Following on, the whole aqueous phase underwent a dispersive liquid-liquid microextraction (DLLME) leading to the transfer of the neutral complex into the fine droplet of organic extraction phase. A micro-volume spectrophotometer was used to determine Cr(VI) concentrations. Under the optimized conditions predicted by the statistical design, the limit of quantification (LOQ) obtained was reported to be 5.0 μg/L, and the calibration curve was linear over the concentration range of 5-100 μg/L. Finally, the method was successfully implemented for the determination of low levels of Cr(VI) ions in various real aquatic samples and the accuracies fell within the range of 83-102%, while the precision varied in the span of 1.7-5.2%. Copyright © 2018. Published by Elsevier B.V.

Plasma cholesterol homeostasis, HDL remodeling and function during the acute phase reaction.

PubMed

Zimetti, Francesca; De Vuono, Stefano; Gomaraschi, Monica; Adorni, Maria Pia; Favari, Elda; Ronda, Nicoletta; Ricci, Maria Anastasia; Veglia, Fabrizio; Calabresi, Laura; Lupattelli, Graziana

2017-10-01

Acute phase reaction (APR) is a systemic inflammation triggered by several conditions associated with lipid profile alterations. We evaluated whether APR also associates with changes in cholesterol synthesis and absorption, HDL structure, composition, and cholesterol efflux capacity (CEC). We analyzed 59 subjects with APR related to infections, oncologic causes, or autoimmune diseases and 39 controls. We detected no difference in markers of cholesterol synthesis and absorption. Conversely, a significant reduction of LpA-I- and LpAI:AII-containing HDL (-28% and -44.8%, respectively) and of medium-sized HDL (-10.5%) occurred in APR. Total HDL CEC was impaired in APR subjects (-18%). Evaluating specific CEC pathways, we found significant reductions in CEC by aqueous diffusion and by the transporters scavenger receptor B-I and ABCG1 (-25.5, -41.1 and -30.4%, respectively). ABCA1-mediated CEC was not affected. Analyses adjusted for age and gender provided similar results. In addition, correcting for HDL-cholesterol (HDL-C) levels, the differences in aqueous diffusion total and ABCG1-CEC remained significant. APR subjects displayed higher levels of HDL serum amyloid A (+20-folds; P = 0.003). In conclusion, APR does not associate with cholesterol synthesis and absorption changes but with alterations of HDL composition and a marked impairment of HDL CEC, partly independent of HDL-C serum level reduction. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

Aqueous oxidation of green leaf volatiles by hydroxyl radical as a source of SOA: Kinetics and SOA yields

NASA Astrophysics Data System (ADS)

Richards-Henderson, Nicole K.; Hansel, Amie K.; Valsaraj, Kalliat T.; Anastasio, Cort

2014-10-01

Green leaf volatiles (GLVs) are a class of oxygenated hydrocarbons released from vegetation, especially during mechanical stress or damage. The potential for GLVs to form secondary organic aerosol (SOA) via aqueous-phase reactions is not known. Fog events over vegetation will lead to the uptake of GLVs into water droplets, followed by aqueous-phase reactions with photooxidants such as the hydroxyl radical (OH). In order to determine if the aqueous oxidation of GLVs by OH can be a significant source of secondary organic aerosol, we studied the partitioning and reaction of five GLVs: cis-3-hexen-1-ol, cis-3-hexenyl acetate, methyl salicylate, methyl jasmonate, and 2-methyl-3-butene-2-ol. For each GLV we measured the kinetics of aqueous oxidation by OH, and the corresponding SOA mass yield. The second-order rate constants for GLVs with OH were all near diffusion controlled, (5.4-8.6) × 109 M-1 s-1 at 298 K, and showed a small temperature dependence, with an average activation energy of 9.3 kJ mol-1 Aqueous-phase SOA mass yields ranged from 10 to 88%, although some of the smaller values were not statistically different from zero. Methyl jasmonate was the most effective aqueous-phase SOA precursor due to its larger Henry's law constant and high SOA mass yield (68 ± 8%). While we calculate that the aqueous-phase SOA formation from the five GLVs is a minor source of aqueous-phase SOA, the availability of other GLVs, other oxidants, and interfacial reactions suggest that GLVs overall might be a significant source of SOA via aqueous reactions.

Study on Colloid Vibration Current in Aqueous Solution of Binary Surfactant Mixtures: Effects of Counterions and Hydrophobic Chains.

PubMed

Takata, Youichi; Hyono, Atsushi; Ohshima, Hiroyuki

2016-11-01

In order to elucidate an electroacoustic phenomenon of mixed micelles in an aqueous solution, we measured the colloid vibration current (CVI) in aqueous solutions of binary surfactant mixtures. Based on the thermodynamic treatment of critical micelle concentration (cmc) values determined by conductivity measurements, it was expected that dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium chloride (DTAC) molecules would mix ideally in the micelle. However, the micelle composition as evaluated from the CVI measurement, based on the linear dependence of the CVI value on the micelle composition, differed from the aforementioned ideality. Considering these observations, we concluded that the CVI measurement was more sensitive to the counterion distribution near the micelle surface, whereas the thermodynamically determined micelle composition included the counterions more loosely bound in the diffuse double layer due to the electroneutrality condition included in its assumption. On the other hand, the phase diagram illustrating micelle formation in the lithium dodecyl sulfate (LiDS) - lithium perfluorooctane sulfonate (LiFOS) mixture system showed a heteroazeotropic point arising from the stronger interactions between homologous surfactants than between heterologous ones. Although the concentration dependence of CVI values was expected to drastically change at a heteroazeotropic point due to the enormous variation in the density of the micelle core, the results showed a monotonous change, which suggests that the density of the micelle core varies continuously. By taking the partial molar volume of fluorocarbon compounds in the hydrocarbon compounds into account, the density of the micelle core was affected by the size of the micelle as well as its constituents.

[Preparation and biological properties of basidiomycete aqueous extracts and their mycelial compositions].

PubMed

Bukhman, V M; Treshchalina, E M; Krasnopol'skaia, L M; Isakova, E B; Sedakova, L A; Avtonomova, A V; Leont'eva, M I; Soboleva, N Iu; Belitskiĭ, I V; Bakanov, A V

2007-01-01

The basidiomycetes Ganoderma lucidum, Hericium erinaceus, Lentinus edodes and Trametes versicolor were used for preparation of aqueous extracts. A polysaccharide preparation (VPG) was isolated from the G. lucidum aqueous extracts. The mycelium was grown under submerged conditions according to an original procedure. Preliminary exposure of mice with tumors to cyclosphosphamide in a low dose for prolonged elimination of T-suppressors and rapid recovery of T-killers induced an increase in the efficacy of the H. erinaceus and L. edodes extracts. Investigation of the aqueous extracts and VPG on different tumor strain lines for the potential Modifiers of Biological Response (Ca755, s/c P388, s-180) demonstrated antitumor activity and satisfactory tolerabily after oral administration. Inhibition of the tumor growth by the H. erinaceus and T. versicolor extracts and VPG amounted to 88-99% and that of s-180 treated with the L. edodes aqueous extract amounted to 66-75%. Compositions 1, 2, 4 amd 5 were significantly more active by the duration and value of the effect on the animal tumor nodes as compared to the aqueous extracts and VPG included to the compositions and composition 4. Composition 5 (T. versicolor + H. erinaceus + G. Lucidum) proved to be the most efficient by all the criteria. The results of the design of the technologies for cultivation of the mycelum of the medicinal basidiomycetes, investigation of the antumor properties of the extracts and polysaccharide fraction of the mycelium and development of efficient compositions on their basis are summarized. Composition 5 proved to be the most promising for the clinical trials.

Miscibility and interaction between 1-alkanol and short-chain phosphocholine in the adsorbed film and micelles.

PubMed

Takajo, Yuichi; Matsuki, Hitoshi; Kaneshina, Shoji; Aratono, Makoto; Yamanaka, Michio

2007-09-01

The miscibility and interaction of 1-hexanol (C6OH) and 1-heptanol (C7OH) with 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) in the adsorbed films and micelles were investigated by measuring the surface tension of aqueous C6OH-DHPC and aqueous C7OH-DHPC solutions. The surface density, the mean molecular area, the composition of the adsorbed film, and the excess Gibbs energy of adsorption g(H,E), were estimated. Further, the critical micelle concentration of the mixtures was determined from the surface tension versus molality curves; the micellar composition was calculated. The miscibility of the 1-alkanols and DHPC molecules in the adsorbed film and micelles was examined using the phase diagram of adsorption (PDA) and that of micellization (PDM). The PDA and the composition dependence of g(H,E) indicated the non-ideal mixing of the 1-alkanols and DHPC molecules due to the attractive interaction between the molecules in the adsorbed film, while the PDM indicated that the 1-alkanol molecules were not incorporated in the micelles within DHPC rich region. The dependence of the mean molecular area of the mixtures on the surface composition suggested that the packing property of the adsorbed film depends on the chain length of 1-alkanol: C6OH expands the DHPC adsorbed film more than C7OH.

Ca-Fe and Alkali-Halide Alteration of an Allende Type B CAI: Aqueous Alteration in Nebular or Asteroidal Settings

NASA Technical Reports Server (NTRS)

Ross, D. K.; Simon, J. I.; Simon, S. B.; Grossman, L.

2012-01-01

Ca-Fe and alkali-halide alteration of CAIs is often attributed to aqueous alteration by fluids circulating on asteroidal parent bodies after the various chondritic components have been assembled, although debate continues about the roles of asteroidal vs. nebular modification processes [1-7]. Here we report de-tailed observations of alteration products in a large Type B2 CAI, TS4 from Allende, one of the oxidized subgroup of CV3s, and propose a speculative model for aqueous alteration of CAIs in a nebular setting. Ca-Fe alteration in this CAI consists predominantly of end-member hedenbergite, end-member andradite, and compositionally variable, magnesian high-Ca pyroxene. These phases are strongly concentrated in an unusual "nodule" enclosed within the interior of the CAI (Fig. 1). The Ca, Fe-rich nodule superficially resembles a clast that pre-dated and was engulfed by the CAI, but closer inspection shows that relic spinel grains are enclosed in the nodule, and corroded CAI primary phases interfinger with the Fe-rich phases at the nodule s margins. This CAI also contains abundant sodalite and nepheline (alkali-halide) alteration that occurs around the rims of the CAI, but also penetrates more deeply into the CAI. The two types of alteration (Ca-Fe and alkali-halide) are adjacent, and very fine-grained Fe-rich phases are associated with sodalite-rich regions. Both types of alteration appear to be replacive; if that is true, it would require substantial introduction of Fe, and transport of elements (Ti, Al and Mg) out of the nodule, and introduction of Na and Cl into alkali-halide rich zones. Parts of the CAI have been extensively metasomatized.

Process for radioisotope recovery and system for implementing same

DOEpatents

Meikrantz, David H [Idaho Falls, ID; Todd, Terry A [Aberdeen, ID; Tranter, Troy J [Idaho Falls, ID; Horwitz, E Philip [Naperville, IL

2009-10-06

A method of recovering daughter isotopes from a radioisotope mixture. The method comprises providing a radioisotope mixture solution comprising at least one parent isotope. The at least one parent isotope is extracted into an organic phase, which comprises an extractant and a solvent. The organic phase is substantially continuously contacted with an aqueous phase to extract at least one daughter isotope into the aqueous phase. The aqueous phase is separated from the organic phase, such as by using an annular centrifugal contactor. The at least one daughter isotope is purified from the aqueous phase, such as by ion exchange chromatography or extraction chromatography. The at least one daughter isotope may include actinium-225, radium-225, bismuth-213, or mixtures thereof. A liquid-liquid extraction system for recovering at least one daughter isotope from a source material is also disclosed.

Process for radioisotope recovery and system for implementing same

DOEpatents

Meikrantz, David H.; Todd, Terry A.; Tranter, Troy J.; Horwitz, E. Philip

2007-01-02

A method of recovering daughter isotopes from a radioisotope mixture. The method comprises providing a radioisotope mixture solution comprising at least one parent isotope. The at least one parent isotope is extracted into an organic phase, which comprises an extractant and a solvent. The organic phase is substantially continuously contacted with an aqueous phase to extract at least one daughter isotope into the aqueous phase. The aqueous phase is separated from the organic phase, such as by using an annular centrifugal contactor. The at least one daughter isotope is purified from the aqueous phase, such as by ion exchange chromatography or extraction chromatography. The at least one daughter isotope may include actinium-225, radium-225, bismuth-213, or mixtures thereof. A liquid-liquid extraction system for recovering at least one daughter isotope from a source material is also disclosed.

Three-dimensional molecular mapping of a multiple emulsion by means of CARS microscopy.

PubMed

Meyer, Tobias; Akimov, Denis; Tarcea, Nicolae; Chatzipapadopoulos, Susana; Muschiolik, Gerald; Kobow, Jens; Schmitt, Michael; Popp, Jürgen

2008-02-07

Multiple emulsions consisting of water droplets dispersed in an oil phase containing emulsifier which is emulsified in an outer water phase (W/O/W) are of great interest in pharmacology for developing new drugs, in the nutrition sciences for designing functional food, and in biology as model systems for cell organelles such as liposomes. In the food industry multiple emulsions with high sugar content in the aqueous phase can be used for the production of sweets, because the high sugar content prevents deterioration. However, for these emulsions the refractive indexes of oil and aqueous phase are very similar. This seriously impedes the analysis of these emulsions, e.g., for process monitoring, because microscopic techniques based on transmission or reflection do not provide sufficient contrast. We have characterized the inner dispersed phase of concentrated W/O/W emulsions with the same refractive index of the three phases by micro Raman spectroscopy and investigated the composition and molecular distribution in water-oil-water emulsions by means of three-dimensional laser scanning CARS (coherent anti-Stokes Raman scattering) microscopy. CARS microscopy has been used to study water droplets dispersed in oil droplets at different Raman resonances to visualize different molecular species. Water droplets with a diameter of about 700 nm could clearly be visualized. The advantages of CARS microscopy for studying this particular system are emphasized by comparing this microscopic technique with conventional confocal reflection and transmission microscopies.

Liquid-liquid extraction of ethanol from aqueous solutions with amyl acetate, benzyl alcohol, and methyl isobutyl ketone at 298. 15. Kappa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solimo, H.N.; Martinez, H.E.; Riggio, R.

1989-04-01

Experimental mutual solubility and tie-line data were determined for three ternary liquid-liquid systems containing water, ethanol, and amyl acetate, benzyl alcohol, and methyl isobutyl ketone at 298.15{Kappa} in order to obtain their complete phase diagrams and to determine which is the most suitable solvent for extraction of ethanol from aqueous solutions. Tie lines were determined correlating the density of the binodal curve as a function of composition and the plait points using the Othmer and Tobias method. The experimental data were also correlated with the UNIFAC group contribution method. A qualitative agreement was obtained. Experimental results show that amyl acetatemore » is a better solvent than methyl isobutyl ketone and benzyl alcohol.« less

Environmentally benign processing of YAG transparent wafers

NASA Astrophysics Data System (ADS)

Yang, Yan; Wu, Yiquan

2015-12-01

Transparent yttrium aluminum garnet (YAG) wafers were successfully produced via aqueous tape casting and vacuum sintering techniques using a new environmentally friendly binder, a copolymer of isobutylene and maleic anhydride with the commercial name ISOBAM (noted as ISOBAM). Aqueous YAG slurries were mixed by ball-milling, which was followed by de-gassing and tape casting of wafers. The final YAG green tapes were homogenous and flexible, and could be bent freely without cracking. After the drying and sintering processes, transparent YAG wafers were achieved. The microstructures of both the green tape and vacuum-sintered YAG ceramic were observed by scanning electronic microscopy (SEM). Phase compositions were examined by X-ray diffraction (XRD). Optical transmittance was measured in UV-VIS regions with the result that the transmittance is 82.6% at a wavelength of 800 nm.

Aqueous Alteration of Endeavour Crater Rim Apron Rocks

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Ming, Douglas W.; Gellert, Ralf; Clark, Benton C.; Morris, Richard V.; Yen, Albert S.; Arvidson, Raymond E.; Crumpler, Larry S.; Farrand, William H.; Grant, John A.;

Aqueous Alteration of Endeavour Crater Rim Apron Rocks

NASA Astrophysics Data System (ADS)

Ming, D. W.; Mittlefehldt, D. W.; Gellert, R.; Clark, B. C.; Morris, R. V.; Yen, A. S.; Arvidson, R. E.; Crumpler, L. S.; Farrand, W. H.; Grant, J. A., III; Jolliff, B. L.; Parker, T. J.; Peretyazhko, T.

2014-12-01

Mars Exploration Rover Opportunity is exploring Noachian age rocks of the rim of 22 km diameter Endeavour crater. Overlying the pre-impact lithologies and rim breccias is a thin apron of fine-grained sediments, the Grasberg fm, forming annuli on the lower slopes of rim segments. Hesperian Burns fm sandstones overly the Grasberg fm. Grasberg rocks have major element compositions that are distinct from Burns fm sandstones, especially when comparing interior compositions exposed by the Rock Abrasion Tool. Grasberg rocks are also different from Endeavour rim breccias, but have general compositional similarities to them. Grasberg sediments are plausibly fine-grained materials derived from the impact breccias. Veins of CaSO4 transect Grasberg fm rocks demonstrating post-formation aqueous alteration. Minor/trace elements show variations consistent with mobilization by aqueous fluids. Grasberg fm rocks have low Mn and high Fe/Mn ratios compared to the other lithologies. Manganese likely was mobilized and removed from the Grasberg host rock by redox reactions. We posit that Fe2+ from acidic solutions associated with formation of the Burns sulfate-rich sandstones acted as an electron donor to reduce more oxidized Mn to Mn2+. The Fe contents of Grasberg rocks are slightly higher than in other rocks suggesting precipitation of Fe phases in Grasberg materials. Pancam spectra show that Grasberg rocks have a higher fraction of ferric oxide minerals than other Endeavour rim rocks. Solutions transported Mn2+ into the Endeavour rim materials and oxidized and/or precipitated it in them. Grasberg has higher contents of the mobile elements K, Zn, Cl, and Br compared to the rim materials. Similar enrichments of mobile elements were measured by the Spirit APXS on West Spur and around Home Plate in Gusev crater. Enhancements in these elements are attributed to interactions of hydrothermal acidic fluids with the host rocks. Interactions of fluids with the Grasberg fm postdate the genesis of the Endeavour rim phyllosilicates. The aqueous alteration history of Endeavour rim rocks is complicated by different styles of alteration that have spanned the Noachian and Hesperian. Late stage acidic aqueous alteration of Grasberg fm materials is likely penecontemporaneous with the diagenesis of the sulfate-rich sediments of Meridiani Planum.

Secondary organic aerosol formation from isoprene photo-oxidation during cloud condensation-evaporation cycles (CUMULUS project)

NASA Astrophysics Data System (ADS)

Brégonzio-Rozier, Lola; Siekmann, Frank; Giorio, Chiara; Temime-Roussel, Brice; Pangui, Edouard; Morales, Sébastien; Gratien, Aline; Ravier, Sylvain; Monod, Anne; Doussin, Jean-Francois

2014-05-01

It is acknowledged that atmospheric photo-oxidation of Volatile Organic Compounds (VOC) leads to the formation of less volatile oxidized species. These compounds can undergo gas-to-particle conversion, leading to the formation of Secondary Organic Aerosols (SOA) in the atmosphere. Nevertheless, some of these oxidized species are water soluble and could also partition into cloud droplets. Higher molecular weight and less volatile compounds could be produced in the aqueous phase and remain in the particle phase after water evaporation (Ervens et al., 2011). The aim of the present work is to study SOA formation in the presence of cloud droplets during isoprene photo-oxidation. To this end, an original multiphase approach in a simulation chamber was set up in order to investigate the chemistry occurring in the gaseous, particulate and aqueous phases, and the exchange between these phases. Experiments were performed, within the CUMULUS project (CloUd MULtiphase chemistry of organic compoUndS in the troposphere), in the CESAM chamber (Wang et al., 2011). This chamber was designed to investigate multiphase processes under realistic actinic flux, and accurate control of both temperature and relative humidity. A specific protocol was set up to produce cloud events in the simulation chamber exhibiting a significant lifetime in the presence of light (10-12 minutes). By using this protocol, many clouds could be generated in a single experiment. In each experiment, around 800 ppb of isoprene was injected in the chamber together with HONO under dry conditions before irradiation. A Fourier Transform Infrared Spectrometer (FTIR), a Proton Transfer Reaction Mass Spectrometer (PTR-TOF-MS) and NOx and O3 analyzers were used to analyze gas-phase composition. Dried SOA size distributions and total concentrations were measured by a Scanning Mobility Particle Sizer (SMPS). An Aerodyne High Resolution Time-Of-Flight Aerosol Mass Spectrometer (HR-TOF-AMS) was also used to investigate aerosol composition. Cloud droplets size distributions were measured by a white light Optical Particle Counter (OPC). In all experiments, the dissolution of gaseous oxidation products into aqueous phase and SOA production have been observed during isoprene photo-oxidation in the presence of a cloud event. The overall results in additional SOA mass production and the dynamic of gaseous oxidation products and SOA mass concentrations will be presented. Ervens, B. et al. (2011). Atmospheric Chemistry and Physics 11(21): 11069-11102. Wang, J. et al. (2011). Atmospheric Measurement Techniques 4(11): 2465-2494.

Method and apparatus for the removal of bioconversion of constituents of organic liquids

DOEpatents

Scott, Timothy; Scott, Charles D.

1994-01-01

A method and apparatus for the removal or conversion of constituents from bulk organic liquids. A countercurrent biphasic bioreactor system is utilized to disperse and recoalesce a biocatalyst contained in the aqueous liquid phase into the organic liquid phase containing the constituent. Two transient, high-intensity electrical fields rupture the aqueous drops into a plurality of microdroplets and induce continuous coalescence and redispersion as the microdroplets travel through the organic phase, thus increasing surface area. As the aqueous microdroplets progress through the organic phase, the biocatalyst then reacts with the constituent to produce a product which is then removed from the bioreactor in the aqueous phase or retained in the organic phase. The organic liquid, now free of the original constituents, is ready for immediate use or further processing.

Method for separating water soluble organics from a process stream by aqueous biphasic extraction

DOEpatents

Chaiko, David J.; Mego, William A.

1999-01-01

A method for separating water-miscible organic species from a process stream by aqueous biphasic extraction is provided. An aqueous biphase system is generated by contacting a process stream comprised of water, salt, and organic species with an aqueous polymer solution. The organic species transfer from the salt-rich phase to the polymer-rich phase, and the phases are separated. Next, the polymer is recovered from the loaded polymer phase by selectively extracting the polymer into an organic phase at an elevated temperature, while the organic species remain in a substantially salt-free aqueous solution. Alternatively, the polymer is recovered from the loaded polymer by a temperature induced phase separation (cloud point extraction), whereby the polymer and the organic species separate into two distinct solutions. The method for separating water-miscible organic species is applicable to the treatment of industrial wastewater streams, including the extraction and recovery of complexed metal ions from salt solutions, organic contaminants from mineral processing streams, and colorants from spent dye baths.

Review of the impacts of leaking CO 2 gas and brine on groundwater quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qafoku, Nikolla P.; Lawter, Amanda R.; Bacon, Diana H.

2017-06-01

This review paper provides a synthetic view of the existing knowledge and summarizes data and findings of the recent literature on the subject of the potential leaking of CO2 from the deep subsurface storage reservoirs and the effects on aquifer quality. New ideas and concepts are developed and insights are also provided. The objectives of this paper are to: 1) present and discuss potential risks for groundwater degradation due to CO2 gas and brine exposure; 2) identify the set of geochemical data required to assess and predict aquifer responses to CO2 and brine leakage. Specifically, this paper will discuss themore » following issues: 1) Aquifer responses (such as changes in aqueous phase/groundwater chemical composition; changes in solid phase chemistry and mineralogy; changes in the extent and rate of reactions and processes and possible establishment of a new network of reactions and processes affecting or controlling overall mobility of major, minor, and trace elements; development of conceptual and reduced order models (ROMs) to describe and predict aquifer responses); 2) The degree of impact such as significant or insignificant changes in pH and major, minor, and trace element release that depend on the following controlling variables; the effect of leaking plume characteristics (gas composition, pure CO2 and/or CO2 -CH4 -H2S mixtures and brine concentration and composition (trace metals); aquifer properties [such as initial aqueous phase conditions and mineralogy: minerals controlling sediments’ response (e.g., calcite, Si bearing minerals, etc.)]; overview of relevant hydrogeological and geochemical processes related to the impact of CO2 gas and brine on groundwater quality; the fate of the elements released from sediments or transported with brine (such as precipitation/incorporation into minerals (calcite and other minerals), adsorption, electron transfer reactions, the role of natural attenuation; whether or not the release of metals following exposure to CO2 harmful (risk assessment).« less

Structural transformations, composition anomalies and a dramatic collapse of linear polymer chains in dilute ethanol-water mixtures.

PubMed

Banerjee, Saikat; Ghosh, Rikhia; Bagchi, Biman

2012-03-29

Water-ethanol mixtures exhibit many interesting anomalies, such as negative excess partial molar volume of ethanol, excess sound absorption coefficient at low concentrations, and positive deviation from Raoult's law for vapor pressure, to mention a few. These anomalies have been attributed to different, often contradictory origins, but a quantitative understanding is still lacking. We show by computer simulation and theoretical analyses that these anomalies arise from the sudden emergence of a bicontinuous phase that occurs at a relatively low ethanol concentration of x(eth) ≈ 0.06-0.10 (that amounts to a volume fraction of 0.17-0.26, which is a significant range!). The bicontinuous phase is formed by aggregation of ethanol molecules, resulting in a weak phase transition whose nature is elucidated. We find that the microheterogeneous structure of the mixture gives rise to a pronounced nonmonotonic composition dependence of local compressibility and nonmonotonic dependence in the peak value of the radial distribution function of ethyl groups. A multidimensional free energy surface of pair association is shown to provide a molecular explanation of the known negative excess partial volume of ethanol in terms of parallel orientation and hence better packing of the ethyl groups in the mixture due to hydrophobic interactions. The energy distribution of the ethanol molecules indicates additional energy decay channels that explain the excess sound attenuation coefficient in aqueous alcohol mixtures. We studied the dependence of the solvation of a linear polymer chain on the composition of the water-ethanol solvent. We find that there is a sudden collapse of the polymer at x(eth) ≈ 0.05-a phenomenon which we attribute to the formation of the microheterogeneous structures in the binary mixture at low ethanol concentrations. Together with recent single molecule pulling experiments, these results provide new insight into the behavior of polymer chain and foreign solutes, such as enzymes, in aqueous binary mixtures.

Anthropogenic and Biogenic Emissions, and their Contributions to Summertime Haze in the Southeast U.S.: Results from the NOAA SENEX Study in 2013

NASA Astrophysics Data System (ADS)

De Gouw, J. A.

2015-12-01

The NOAA Southeast Nexus of Air Quality and Climate Change (SENEX) study was focused on biogenic and anthropogenic emissions in the Southeast United States, their interactions to form oxidants and aerosol, and the implications of these processes for air quality and climate. For SENEX, the NOAA WP-3D research aircraft was deployed out of a regional airport in Smyrna, Tennessee during June and July of 2013. The aircraft carried an extensive suite of instruments to characterize the gas- and aerosol-phase composition of the atmosphere, as well as the climate-relevant properties of the aerosol. The SENEX study was performed in close collaboration with several other studies in the framework of the Southeast Atmosphere Study. Some highlights of the measurements will be presented with a particular focus on the processes by which anthropogenic and biogenic emissions interact to form secondary species including aerosol. The FLEXPART Lagrangian transport model was found to be a useful tool to quantify the relative contribution from anthropogenic and biogenic emissions to different trace species in the sampled air masses. Observations in power plant plumes provided constraints on the dependence of hydroxyl radical concentrations on nitrogen oxides (NOx). Oxidation rates were higher at enhanced concentrations of NOx, leading to faster production of products from biogenic volatile organic compounds (VOCs) in polluted conditions. Organic aerosol was formed from isoprene downwind from one power plant that had relatively high sulfur emissions. Nighttime flights were conducted to constrain organic aerosol formation from the reaction between biogenic VOCs and nitrate radicals. The volume of aerosol water depends on aerosol composition (e.g. sulfate versus organics), which has been proposed as a link between anthropogenic emissions and products of aqueous-phase chemistry. Vertical profiles of aerosol volume and composition provided evidence for aqueous-phase formation of sulfate aerosol, but formation of organic aerosol was not significant within the uncertainties of the analysis.

High Performance Graphene Oxide Based Rubber Composites

PubMed Central

Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

2013-01-01

In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

High performance graphene oxide based rubber composites.

PubMed

Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W; Zhang, Liqun; Liang, Yongri; Liu, Li

2013-01-01

In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

Magnetically assisted slip casting of bioinspired heterogeneous composites

NASA Astrophysics Data System (ADS)

Le Ferrand, Hortense; Bouville, Florian; Niebel, Tobias P.; Studart, André R.

2015-11-01

Natural composites are often heterogeneous to fulfil functional demands. Manufacturing analogous materials remains difficult, however, owing to the lack of adequate and easily accessible processing tools. Here, we report an additive manufacturing platform able to fabricate complex-shaped parts exhibiting bioinspired heterogeneous microstructures with locally tunable texture, composition and properties, as well as unprecedentedly high volume fractions of inorganic phase (up to 100%). The technology combines an aqueous-based slip-casting process with magnetically directed particle assembly to create programmed microstructural designs using anisotropic stiff platelets in a ceramic, metal or polymer functional matrix. Using quantitative tools to control the casting kinetics and the temporal pattern of the applied magnetic fields, we demonstrate that this approach is robust and can be exploited to design and fabricate heterogeneous composites with thus far inaccessible microstructures. Proof-of-concept examples include bulk composites with periodic patterns of microreinforcement orientation, and tooth-like bilayer parts with intricate shapes exhibiting site-specific composition and texture.

Dysprosium sorption by polymeric composite bead: robust parametric optimization using Taguchi method.

PubMed

Yadav, Kartikey K; Dasgupta, Kinshuk; Singh, Dhruva K; Varshney, Lalit; Singh, Harvinderpal

2015-03-06

Polyethersulfone-based beads encapsulating di-2-ethylhexyl phosphoric acid have been synthesized and evaluated for the recovery of rare earth values from the aqueous media. Percentage recovery and the sorption behavior of Dy(III) have been investigated under wide range of experimental parameters using these beads. Taguchi method utilizing L-18 orthogonal array has been adopted to identify the most influential process parameters responsible for higher degree of recovery with enhanced sorption of Dy(III) from chloride medium. Analysis of variance indicated that the feed concentration of Dy(III) is the most influential factor for equilibrium sorption capacity, whereas aqueous phase acidity influences the percentage recovery most. The presence of polyvinyl alcohol and multiwalled carbon nanotube modified the internal structure of the composite beads and resulted in uniform distribution of organic extractant inside polymeric matrix. The experiment performed under optimum process conditions as predicted by Taguchi method resulted in enhanced Dy(III) recovery and sorption capacity by polymeric beads with minimum standard deviation. Copyright © 2015 Elsevier B.V. All rights reserved.

Determining the relative extent of alteration in CM chondrites

NASA Technical Reports Server (NTRS)

Browning, Lauren B.; Mcsween, Harry Y., Jr.; Zolensky, Michael

1993-01-01

The aqueous alteration of CM chondrites provides a record of the processes attending the earliest stages of parent body evolution. However, resolving the alteration pathways of chondritic evolution requires a means for distinguishing the relative extent of alteration that individual samples have experienced. Three new indices for gauging the relative degree of alteration in CM chondrites based on modal and compositional analyses of 7 CM falls were proposed. The proposed alteration parameters are consistent with the basic tenets of several previous models and correlate with additional indices to produce an integrated method for determining the relative extent of alteration. The model predicts the following order of progressive alteration: Murchison (MC) is less than or equal to Bells (BL) is less than Murray (MY) is less than Cochabamba (CC) is less than Mighei (MI) is less than Nogoya (NG) is less than or equal to Cold Bokkeveld (CB). The broad range of CM phyllosilicate compositions observed within individual meteorites is fundamental to the characterization of the aqueous alteration process. Chemical analyses of CM phyllosilicates suggest that these phases became systematically enriched in Mg and depleted in Fe with increasing alteration.

Nonequilibrium Thermodynamics of Hydrate Growth on a Gas-Liquid Interface.

PubMed

Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

2018-04-06

We develop a continuum-scale phase-field model to study gas-liquid-hydrate systems far from thermodynamic equilibrium. We design a Gibbs free energy functional for methane-water mixtures that recovers the isobaric temperature-composition phase diagram under thermodynamic equilibrium conditions. The proposed free energy is incorporated into a phase-field model to study the dynamics of hydrate formation on a gas-liquid interface. We elucidate the role of initial aqueous concentration in determining the direction of hydrate growth at the interface, in agreement with experimental observations. Our model also reveals two stages of hydrate growth at an interface-controlled by a crossover in how methane is supplied from the gas and liquid phases-which could explain the persistence of gas conduits in hydrate-bearing sediments and other nonequilibrium phenomena commonly observed in natural methane hydrate systems.

Development of tropine-salt aqueous two-phase systems and removal of hydrophilic ionic liquids from aqueous solution.

PubMed

Wu, Haoran; Yao, Shun; Qian, Guofei; Song, Hang

2016-08-26

A novel aqueous two-phase systems (ATPS) composed of a small molecule organic compound tropine and an organic or inorganic salt aqueous solution has been developed for the first time. The phase behavior of tropine-salt ATPS was systemically investigated and the phase equilibrium data were measured in different temperatures and concentrations and correlated by the Merchuk equation with satisfactory results. The detection of the conductivity and particle size proved the formation of micelle in the process of forming tropine-salt ATPS. The separation application of the ATPS was assessed with the removal of hydrophilic benzothiazolium-based ionic liquids (ILs) from aqueous solution. The result showed that ILs were effectively extracted into the top tropine-rich phase. Finally, ILs in the top tropine-rich phase were further separated by the means of adsorption-desorption with DM301 macroporous resin and ethanol. The method of novel tropine-salt ATPS combined with adsorption-desorption is demonstrated a promising alternative thought and approach for the removal or recovery of hydrophilic compounds from aqueous media and also could provide a potential application for bio-separation. Copyright © 2016. Published by Elsevier B.V.

Tube Radial Distribution Flow Separation in a Microchannel Using an Ionic Liquid Aqueous Two-Phase System Based on Phase Separation Multi-Phase Flow.

PubMed

Nagatani, Kosuke; Shihata, Yoshinori; Matsushita, Takahiro; Tsukagoshi, Kazuhiko

2016-01-01

Ionic liquid aqueous two-phase systems were delivered into a capillary tube to achieve tube radial distribution flow (TRDF) or annular flow in a microspace. The phase diagram, viscosity of the phases, and TRDF image of the 1-butyl-3-methylimidazolium chloride and NaOH system were examined. The TRDF was formed with inner ionic liquid-rich and outer ionic liquid-poor phases in the capillary tube. The phase configuration was explained using the viscous dissipation principle. We also examined the distribution of rhodamine B in a three-branched microchannel on a microchip with ionic liquid aqueous two-phase systems for the first time.

Manganese-calcium intermixing facilitates heteroepitaxial growth at the 10 1 ¯ 4 calcite-water interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Man; Riechers, Shawn L.; Ilton, Eugene S.

2017-10-01

In situ atomic force microscopy (AFM) measurements were performed to probe surface precipitates that formed on the (10-14) surface of calcite (CaCO3) single crystals following reaction with Mn2+-bearing aqueous solutions with a range of initial concentrations. Three-dimensional epitaxial islands were observed to precipitate and grow on the surfaces and in situ time-sequenced measurements demonstrated that their growth rates were commensurate with those obtained for epitaxial islands formed on calcite crystals reacted with Cd2+-bearing aqueous solutions of the same range in supersaturation with respect to the pure metal carbonate phase. This finding was unexpected as rhodochrosite (MnCO3) and calcite display amore » 10% lattice mismatch, based on the area of their (10-14) surface unit cells, whereas the lattice mismatch is only 4% for otavite (CdCO3) and calcite. Coatings of varying thicknesses were therefore synthesized by reacting calcite single crystals with calcite-equilibrated aqueous solutions with concentrations of up to 250 µM MnCl2 and analyzed to determine the composition of the surface precipitates. Ex situ X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectivity (XRR), and AFM measurements of the reacted crystals demonstrated the formation of an epitaxial (Mn,Ca)CO3 solid solution with a spatially complex composition atop the calcite surface, whereby the first few nanometers were rich in Ca and the Mn content increased with distance from the original calcite surface, culminating in a topmost region of almost pure MnCO3 for the thickest coatings. These findings explain the measured growth rates (the effective lattice mismatch was much smaller than nominal mismatch) and highlight the strong influence played by the substrate on the composition of surface precipitates in aqueous conditions.« less

Solubility relations in the system sodium chloride-ferrous chloride-water between 25 and 70.degree.C at 1 atm

USGS Publications Warehouse

Chou, I.-Ming; Phan, L.D.

1985-01-01

Solubility relations in the ternary system NaCl-FeCl2-H2O have been determined by the visual polythermal method at 1 atm from 20 to 85??C along six composition lines. These she composition lines are defined by mixing FeCl2??4H2O with six aqueous NaCl solutions containing 5, 10, 11, 15, 20, and 25 wt % of NaCl, respectively. The solid phases encountered in these experiments were NaCl and FeCl2??4H2O. The maximum uncertainties in these measurements are ??0.02 wt % NaCl and ??0.15??C. The data along each composition line were regressed to a smooth curve when only one solid phase was stable. When two solids were stable along a composition line, the data were regressed to two smooth curves, the intersection of which indicated the point where the two solids coexisted. The maximum deviation of the measured solubilities from the smoothed curves is 0.14 wt % FeCl2. Isothermal solubilities of halite and FeCl2??4H2O were calculated from these smoothed curves at 25, 50, and 70 ??C.

Influence of sintering temperature on the phases and photoelectric characteristics of BiOCl/ZnO composite powders

NASA Astrophysics Data System (ADS)

Chen, Song; Zhu, De-gui

2017-12-01

Zinc oxide is a typical functional oxide that has been widely researched for various industry applications due to its peculiar physical characteristics. However, to achieve its potential in promising applications, much work has been diligently performed to improve the physical properties of ZnO. In this work, an aqueous suspension route was used to prepare BiOCl/ZnO composite powders, and sintering processes were applied to investigate the influence of sintering temperature on the phase evolutions, microstructures, and photoelectric characteristics of BiOCl/ZnO composite powders. The results indicated that the photoelectric properties mainly depend on the relevant content of BiOCl in the composite powders and the sintering temperature. The photoelectric measurements in K2SO4 solutions show that the photoelectric properties of the samples with the appropriate BiOCl content (0.3mol% and 2.0mol%) are better than those of ZnO and commercial TiO2 (P25) powders, but the photoelectric measurements in NaOH solutions indicate that the photoelectric characteristics of the as-sintered samples are only better than those of P25.

Analysis and comparison of biomass pyrolysis/gasification condensates: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elliott, D.C.

1986-06-01

This report provides results of chemical and physical analysis of condensates from eleven biomass gasification and pyrolysis systems. The samples were representative of the various reactor configurations being researched within the Department of Energy, Biomass Thermochemical Conversion program. The condensates included tar phases and aqueous phases. The analyses included gross compositional analysis (elemental analysis, ash, moisture), physical characterization (pour point, viscosity, density, heat of combustion, distillation), specific chemical analysis (gas chromatography/mass spectrometry, infrared spectrophotometry, proton and carbon-13 nuclear magnetic resonance spectrometry) and biological activity (Ames assay and mouse skin tumorigenicity tests). These results are the first step of a longermore » term program to determine the properties, handling requirements, and utility of the condensates recovered from biomass gasification and pyrolysis. The analytical data demonstrates the wide range of chemical composition of the organics recovered in the condensates and suggests a direct relationship between operating temperature and chemical composition of the condensates. A continuous pathway of thermal degradation of the tar components as a function of temperature is proposed. Variations in the chemical composition of the organic components in the tars are reflected in the physical properties of tars and phase stability in relation to water in the condensate. The biological activity appears to be limited to the tars produced at high temperatures. 56 refs., 25 figs., 21 tabs.« less

The sensitivity of tropospheric chemistry to cloud interactions

NASA Technical Reports Server (NTRS)

Jonson, Jan E.; Isaksen, Ivar S. A.

1994-01-01

Clouds, although only occupying a relatively small fraction of the troposphere volume, can have a substantial impact on the chemistry of the troposphere. In newly formed clouds, or in clouds with air rapidly flowing through, the chemistry is expected to be far more active than in aged clouds with stagnant air. Thus, frequent cycling of air through shortlived clouds, i.e. cumulus clouds, is likely to be a much more efficient media for altering the composition of the atmosphere than an extensive cloud cover i.e. frontal cloud systems. The impact of clouds is tested out in a 2-D channel model encircling the globe in a latitudinal belt from 30 to 60 deg N. The model contains a detailed gas phase chemistry. In addition physiochemical interactions between the gas and aqueous phases are included. For species as H2O2, CH2O, O3, and SO2, Henry's law equilibria are assumed, whereas HNO3 and H2SO4 are regarded as completed dissolved in the aqueous phase. Absorption of HO2 and OH is assumed to be mass-transport limited. The chemistry of the aqueous phase is characterized by rapid cycling of odd hydrogen, (H2O2, HO2, and OH). O2(-) (produced through dissociation of HO2) reacting with dissolved O3 is a major source of OH in the aqueous phase. This reaction can be a significant sink for O3 in the troposphere. In the interstitial cloud air, odd hydrogen is depleted, whereas NO(x) remains in the gas phase, thus reducing ozone production due to the reaction between NO and HO2. Our calculations give markedly lower ozone levels when cloud interactions are included. This may in part explain the overpredictions of ozone levels often experienced in models neglecting cloud chemical interactions. In the present study, the existence of clouds, cloud types, and their lifetimes are modeled as pseudo random variables. Such pseudo random sequences are in reality deterministic and may, given the same starting values, be reproduced. The effects of cloud interactions on the overall chemistry of the troposphere are discussed. In particular, tests are performed to determine the sensitivity of cloud frequencies and cloud types.

Cell separations and the demixing of aqueous two phase polymer solutions in microgravity

NASA Technical Reports Server (NTRS)

Brooks, Donald E.; Bamberger, Stephan; Harris, J. M.; Van Alstine, James M.

1991-01-01

Partition in phase separated aqueous polymer solutions is a cell separation procedure thought to be adversely influenced by gravity. In preparation for performing cell partitioning experiments in space, and to provide general information concerning the demixing of immiscible liquids in low gravity, a series of phase separated aqueous polymer solutions have been flown on two shuttle flights. Fluorocarbon oil and water emulsions were also flown on the second flight. The aqueous polymer emulsions, which in one g demix largely by sedimentation and convection due to the density differences between the phases, demixed more slowly than on the ground and the final disposition of the phases was determined by the wetting of the container wall by the phases. The demixing behavior and kinetics were influenced by the phase volume ratio, physical properties of the systems and chamber wall interaction. The average domain size increased linearly with time as the systems demixed.

URANIUM DECONTAMINATION WITH RESPECT TO ZIRCONIUM

DOEpatents

Vogler, S.; Beederman, M.

1961-05-01

A process is given for separating uranium values from a nitric acid aqueous solution containing uranyl values, zirconium values and tetravalent plutonium values. The process comprises contacting said solution with a substantially water-immiscible liquid organic solvent containing alkyl phosphate, separating an organic extract phase containing the uranium, zirconium, and tetravalent plutonium values from an aqueous raffinate, contacting said organic extract phase with an aqueous solution 2M to 7M in nitric acid and also containing an oxalate ion-containing substance, and separating a uranium- containing organic raffinate from aqueous zirconium- and plutonium-containing extract phase.

Synthesis of complex oxides with garnet structure by spray drying of an aqueous salt solution

NASA Astrophysics Data System (ADS)

Makeenko, A. V.; Larionova, T. V.; Klimova-Korsmik, O. G.; Starykh, R. V.; Galkin, V. V.; Tolochko, O. V.

2017-04-01

The use of spray drying to obtain powders of complex oxides with a garnet structure has demonstrated. The processes occurring during heating of the synthesized oxide-salt product, leading to the formation of a material with a garnet structure, have been investigated using DTA, TGA, XPS, and XRD. It has been shown that a single-phase garnet structure of system (Y x Gd(3- x))3Al5O12 can be synthesized over the entire range of compositions.

Nanostructured LiMPO4 (M = Fe, Mn, Co, Ni) - carbon composites as cathode materials for Li-ion battery

NASA Astrophysics Data System (ADS)

Dimesso, L.; Spanheimer, C.; Nguyen, T. T. D.; Hausbrand, R.; Jaegermann, W.

2012-10-01

Nanostructured materials are considered to be strong candidates for fundamental advances in efficient storage and/or conversion. In nanostructured materials transport kinetics and surface processes play determining roles. This work describes recent developments in the synthesis and characterization of composites which consist of lithium metal phosphates (LiMPO4, M = Fe, Mn, Co, Ni) coated on nanostructured carbon supports (unordered nanofibers, foams). The composites have been prepared by coating the carbon structures in aqueous (or polyols) solutions containing lithium, metal ions and phosphates. After drying out, the composites have been thermally treated at different temperatures (between 600-780°C) for 5-12 hours under nitrogen. The formation of the olivine structured phase was confirmed by the X-ray diffraction analysis on powders prepared under very similar conditions. The surface investigation revealed the formation of an homogeneous coating of the olivine phase on the carbon structures. The electrochemical performance on the composites showed a dramatic improvement of the discharge specific capacity (measured at a discharge rate of C/25 and room temperature) compared to the prepared powders. The delivered values were 105 mAhg-1 for M = Fe, 100 mAhg-1 for M = Co, 70 mAhg-1 for M = Mn and 30 mAhg-1 for M = Ni respectively.

The influence of the surface composition of mixed monolayer films on the evaporation coefficient of water.

PubMed

Miles, Rachael E H; Davies, James F; Reid, Jonathan P

2016-07-20

We explore the dependence of the evaporation coefficient of water from aqueous droplets on the composition of a surface film, considering in particular the influence of monolayer mixed component films on the evaporative mass flux. Measurements with binary component films formed from long chain alcohols, specifically tridecanol (C13H27OH) and pentadecanol (C15H31OH), and tetradecanol (C14H29OH) and hexadecanol (C16H33OH), show that the evaporation coefficient is dependent on the mole fractions of the two components forming the monolayer film. Immediately at the point of film formation and commensurate reduction in droplet evaporation rate, the evaporation coefficient is equal to a mole fraction weighted average of the evaporation coefficients through the equivalent single component films. As a droplet continues to diminish in surface area with continued loss of water, the more-soluble, shorter alkyl chain component preferentially partitions into the droplet bulk with the evaporation coefficient tending towards that through a single component film formed simply from the less-soluble, longer chain alcohol. We also show that the addition of a long chain alcohol to an aqueous-sucrose droplet can facilitate control over the degree of dehydration achieved during evaporation. After undergoing rapid gas-phase diffusion limited water evaporation, binary aqueous-sucrose droplets show a continued slow evaporative flux that is limited by slow diffusional mass transport within the particle bulk due to the rapidly increasing particle viscosity and strong concentration gradients that are established. The addition of a long chain alcohol to the droplet is shown to slow the initial rate of water loss, leading to a droplet composition that remains more homogeneous for a longer period of time. When the sucrose concentration has achieved a sufficiently high value, and the diffusion constant of water has decreased accordingly so that bulk phase diffusion arrest occurs in the monolayer coated particle, the droplet is found to have lost a greater proportion of its initial water content. A greater degree of slowing in the evaporative flux can be achieved by increasing the chain length of the surface active alcohol, leading to a greater degree of dehydration.

Method and apparatus for the removal or bioconversion of constituents of organic liquids

DOEpatents

Scott, T.; Scott, C.D.

1994-10-25

A method and apparatus are disclosed for the removal or conversion of constituents from bulk organic liquids. A countercurrent biphasic bioreactor system is utilized to disperse and recoalesce a biocatalyst contained in the aqueous liquid phase into the organic liquid phase containing the constituent. Two transient, high-intensity electrical fields rupture the aqueous drops into a plurality of microdroplets and induce continuous coalescence and redispersion as the microdroplets travel through the organic phase, thus increasing surface area. As the aqueous microdroplets progress through the organic phase, the biocatalyst then reacts with the constituent to produce a product which is then removed from the bioreactor in the aqueous phase or retained in the organic phase. The organic liquid, now free of the original constituents, is ready for immediate use or further processing. 1 fig.

Impact of In-Cloud Aqueous Processes on the Chemistry and Transport of Biogenic Volatile Organic Compounds

NASA Astrophysics Data System (ADS)

Li, Yang; Barth, Mary C.; Patton, Edward G.; Steiner, Allison L.

2017-10-01

We investigate the impacts of cloud aqueous processes on the chemistry and transport of biogenic volatile organic compounds (BVOC) using the National Center for Atmospheric Research's large-eddy simulation code with an updated chemical mechanism that includes both gas- and aqueous-phase reactions. We simulate transport and chemistry for a meteorological case with a diurnal pattern of nonprecipitating cumulus clouds from the Baltimore-Washington area DISCOVER-AQ campaign. We evaluate two scenarios with and without aqueous-phase chemical reactions. In the cloud layer (2-3 km), the addition of aqueous phase reactions decreases HCHO by 18% over the domain due to its solubility and the fast depletion from aqueous reactions, resulting in a corresponding decrease in radical oxidants (e.g., 18% decrease in OH). The decrease of OH increases the mixing ratios of isoprene and methacrolein (MACR) (100% and 15%, respectively) in the cloud layer because the reaction rate is lower. Aqueous-phase reactions can modify the segregation between OH and BVOC by changing the sign of the segregation intensity, causing up to 55% reduction in the isoprene-OH reaction rate and 40% reduction for the MACR-OH reaction when clouds are present. Analysis of the isoprene-OH covariance budget shows the chemistry term is the primary driver of the strong segregation in clouds, triggered by the decrease in OH. All organic acids except acetic acid are formed only through aqueous-phase reactions. For acids formed in the aqueous phase, turbulence mixes these compounds on short time scales, with the near-surface mixing ratios of these acids reaching 20% of the mixing ratios in the cloud layer within 1 h of cloud formation.

In Situ Cross-Linking of Polyvinyl Alcohol Films

NASA Technical Reports Server (NTRS)

Philipp, W. H.; Shu, L. C.; May, C. E.

1984-01-01

Films or impregnated matrices readily made from aqueous polyvinyl alcohol solution. Controlled thickness films made by casting precise quantities of aqueous polymer solution on smooth surface, allowing water to evaporate and then removing film. Composite separators formed in similar fashion by impregnating cloth matrix with polyvinyl alcohol solution and drying composite. Insoluble thin hydrophilic membranes made from aqueous systems, and use of undesirable organic solvents not required.

Synthesis and Characterization of Functional Mesostructures Using Colloidal Crystal Templating

DTIC Science & Technology

2004-01-01

fluorescent probes in aqueous polymer solutions . Khoury and co-workers measured the diffusion coefficient of several fluorescein-labeled proteins in...diffraction naq refractive index of the aqueous solution phase xvii ni refractive index of component i ngel refractive index of the hydrogel...phase Tg glass transition temperature α angle of diffraction φaq volume fraction of the aqueous solution phase φi volume fraction of

The Biophysics and Cell Biology of Lipid Droplets

PubMed Central

Thiam, A. Rachid; Farese, Robert V.; Walther, Tobias C.

2015-01-01

Lipid droplets (LDs) are intracellular organelles that are found in most cells, where they have fundamental and dynamic roles in metabolism. Recent investigations showed the importance of basic biophysical principles of emulsions for LD biology. At their essence, LDs are the dispersed phase of an oil-in-water emulsion in the aqueous cytosol of cells. They function prominently in storing oil-based reserves of metabolic energy and components of membrane lipids. Because of their unique architecture, with an interface between the dispersed oil phase and the aqueous cytosol, LDs require specialized mechanisms for their formation, growth, and shrinkage. Such mechanisms enable cells to use emulsified oil in a controlled manner (e.g., when demands for metabolic energy or membrane synthesis increase). Regulation of the composition of the phospholipid surfactants at the LD surface is crucial for LD growth and catabolism and also modifies protein targeting to LD surfaces. Here, we review new insights into the cell biology of LDs, with an emphasis on concepts of emulsion science and biophysics that apply to this organelle. PMID:24220094

Effects of processing on the release profiles of matrix systems containing 5-aminosalicylic acid.

PubMed

Korbely, Anita; Kelemen, András; Kása, Péter; Pintye-Hódi, Klára

2012-12-01

The aim of this study was to investigate the influence of different processing methods on the profiles of 5-aminosalicylic acid dissolution from controlled-release matrix systems based on Eudragit® RL and Eudragit® RS water-insoluble polymers. The pure polymers and their mixtures were studied as matrix formers using different processing methods, i.e., direct compression, wet granulation of the active ingredient with the addition of polymer(s) to the external phase, wet granulation with water, and wet granulation with aqueous dispersions. In comparison with the directly compressed tablets, tablets made by wet granulation with water demonstrated a 6-19% increase in final drug dissolution, whereas when polymers were applied in the external phase during compression, a 0-13% decrease was observed in the amount of drug released. Wet granulation with aqueous polymer dispersions delayed the release of the drug; this was especially marked (a 54-56% decrease in drug release) in compositions, which contained a high amount of Eudragit RL 30D. The release profiles were mostly described by the Korsmeyer-Peppas model or the Hopfenberg model.

Dispersion and surface functionalization of oxide nanoparticles for transparent photocatalytic and UV-protecting coatings and sunscreens

NASA Astrophysics Data System (ADS)

Faure, Bertrand; Salazar-Alvarez, German; Ahniyaz, Anwar; Villaluenga, Irune; Berriozabal, Gemma; De Miguel, Yolanda R.; Bergström, Lennart

2013-04-01

This review describes recent efforts on the synthesis, dispersion and surface functionalization of the three dominating oxide nanoparticles used for photocatalytic, UV-blocking and sunscreen applications: titania, zinc oxide, and ceria. The gas phase and liquid phase synthesis is described briefly and examples are given of how weakly aggregated photocatalytic or UV-absorbing oxide nanoparticles with different composition, morphology and size can be generated. The principles of deagglomeration are reviewed and the specific challenges for nanoparticles highlighted. The stabilization of oxide nanoparticles in both aqueous and non-aqueous media requires a good understanding of the magnitude of the interparticle forces and the surface chemistry of the materials. Quantitative estimates of the Hamaker constants in various media and measurements of the isoelectric points for the different oxide nanoparticles are presented together with an overview of different additives used to prepare stable dispersions. The structural and chemical requirements and the various routes to produce transparent photocatalytic and nanoparticle-based UV-protecting coatings, and UV-blocking sunscreens are described and discussed.

Dispersion and surface functionalization of oxide nanoparticles for transparent photocatalytic and UV-protecting coatings and sunscreens

PubMed Central

Faure, Bertrand; Salazar-Alvarez, German; Ahniyaz, Anwar; Villaluenga, Irune; Berriozabal, Gemma; De Miguel, Yolanda R; Bergström, Lennart

2013-01-01

This review describes recent efforts on the synthesis, dispersion and surface functionalization of the three dominating oxide nanoparticles used for photocatalytic, UV-blocking and sunscreen applications: titania, zinc oxide, and ceria. The gas phase and liquid phase synthesis is described briefly and examples are given of how weakly aggregated photocatalytic or UV-absorbing oxide nanoparticles with different composition, morphology and size can be generated. The principles of deagglomeration are reviewed and the specific challenges for nanoparticles highlighted. The stabilization of oxide nanoparticles in both aqueous and non-aqueous media requires a good understanding of the magnitude of the interparticle forces and the surface chemistry of the materials. Quantitative estimates of the Hamaker constants in various media and measurements of the isoelectric points for the different oxide nanoparticles are presented together with an overview of different additives used to prepare stable dispersions. The structural and chemical requirements and the various routes to produce transparent photocatalytic and nanoparticle-based UV-protecting coatings, and UV-blocking sunscreens are described and discussed. PMID:27877568

Ca(2+) -complex stability of GAPAGPLIVPY peptide in gas and aqueous phase, investigated by affinity capillary electrophoresis and molecular dynamics simulations and compared to mass spectrometric results.

PubMed

Nachbar, Markus; El Deeb, Sami; Mozafari, Mona; Alhazmi, Hassan A; Preu, Lutz; Redweik, Sabine; Lehmann, Wolf Dieter; Wätzig, Hermann

2016-03-01

Strong, sequence-specific gas-phase bindings between proline-rich peptides and alkaline earth metal ions in nanoESI-MS experiments were reported by Lehmann et al. (Rapid Commun. Mass Spectrom. 2006, 20, 2404-2410), however its relevance for physiological-like aqueous phase is uncertain. Therefore, the complexes should also be studied in aqueous solution and the relevance of the MS method for binding studies be evaluated. A mobility shift ACE method was used for determining the binding between the small peptide GAPAGPLIVPY and various metal ions in aqueous solution. The findings were compared to the MS results and further explained using computational methods. While the MS data showed a strong alkaline earth ion binding, the ACE results showed nonsignificant binding. The proposed vacuum state complex also decomposed during a molecular dynamic simulation in aqueous solution. This study shows that the formed stable peptide-metal ion adducts in the gas phase by ESI-MS does not imply the existence of analogous adducts in the aqueous phase. Comparing peptide-metal ion interaction under the gaseous MS and aqueous ACE conditions showed huge difference in binding behavior. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of the monosaccharide composition of water-soluble polysaccharides from Sargassum fusiforme by high performance liquid chromatography/electrospray ionisation mass spectrometry.

PubMed

Wu, Xiaodan; Jiang, Wei; Lu, Jiajia; Yu, Ying; Wu, Bin

2014-02-15

Sargassum fusiforme (hijiki) is the well-known edible algae, whose polysaccharides have been proved to possess interesting bioactivities like antitumor, antioxidant, antimicrobial and immunomodulatory activities. A facile and sensitive method based on high-performance liquid chromatography method of pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone (PMP) coupled with electrospray ionisation mass spectrometry (HPLC/ESI-MS) has been established for the analysis of the monosaccharide composition of polysaccharides in S. fusiforme. Monosaccharides have been converted into PMP-labelled derivatives with aqueous ammonia as a catalyst at 70 °C for 30 min. The optimisation of the pre-column derivatization process was studied. The LODs of the monosaccharides were in the range from 0.01 to 0.02 nmol. PMP-labelled mixture of monosaccharides has been well separated by a reverse-phase HPLC and detected by on-line ESI-MS method under optimised conditions. The mobile phase of elution system was chosen as acetonitrile (solvent A) and 20mM aqueous ammonium acetate (solvent B) (pH 3.0) with Zorbax XDB-C18 column at 30 °C for the separation of the monosaccharide derivatives. Identification of the monosaccharides composition was carried out by analysis with mass spectral behaviour and chromatography characteristics of 1-phenyl-3-methyl-5-pyrazolone (PMP) labelled monosaccharides. All PMP-labelled derivatives display high chemical stabilities, whose regular MS fragmentation is specific for reducing labelled sugars. The result showed that the S. fusiforme polysaccharide consisted of mannose, glucose, galactose, xylose, fucose and glucuronic acid or galacturonic acid, or both uronic acids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Solidification and microstructures of binary ice-I/hydrate eutectic aggregates

USGS Publications Warehouse

McCarthy, C.; Cooper, R.F.; Kirby, S.H.; Rieck, K.D.; Stern, L.A.

2007-01-01

The microstructures of two-phase binary aggregates of ice-I + salt-hydrate, prepared by eutectic solidification, have been characterized by cryogenic scanning electron microscopy (CSEM). The specific binary systems studied were H2O-Na2SO4, H2O-MgSO4, H2O-NaCl, and H2O-H2SO4; these were selected based on their potential application to the study of tectonics on the Jovian moon Europa. Homogeneous liquid solutions of eutectic compositions were undercooled modestly (??T - 1-5 ??C); similarly cooled crystalline seeds of the same composition were added to circumvent the thermodynamic barrier to nucleation and to control eutectic growth under (approximately) isothermal conditions. CSEM revealed classic eutectic solidification microstructures with the hydrate phase forming continuous lamellae, discontinuous lamellae, or forming the matrix around rods of ice-I, depending on the volume fractions of the phases and their entropy of dissolving and forming a homogeneous aqueous solution. We quantify aspects of the solidification behavior and microstructures for each system and, with these data articulate anticipated effects of the microstructure on the mechanical responses of the materials.

Multiple stable oxygen isotopic studies of atmospheric sulfate: A new quantitative way to understand sulfate formation processes in the atmosphere

NASA Astrophysics Data System (ADS)

Lee, Charles Chi-Woo

2000-11-01

Sulfate is an important trace species in the Earth's atmosphere because of its roles in numerous atmospheric processes. In addition to its inherent light-scattering properties, sulfate can serve as cloud condensation nucleus (CCN), affecting cloud formation as well as microphysical properties of clouds. Consequently, atmospheric sulfate species influence the global radiative energy balance. Sulfate is known to increase acidity of rainwater with negative consequences in both natural and urban environments. In addition, aerosol sulfate (<=2.5 μm) is respirable and poses a threat to human health as a potential carrier of toxic pollutants through the respiratory tract. Despite intense investigative effort, uncertainty regarding the relative significance of gas and aqueous phase oxidation pathways still remains. Acquisition of such information is important because the lifetime and transport of S(IV) species and sulfate aerosols are influenced by the oxidative pathways. In addition, sulfate formation processes affect the aerosol size distribution, which ultimately influences radiative properties of atmospheric aerosols. Therefore, the budgetary information of the sulfur cycle, as well as the radiative effects of sulfate on global climate variation, can be attained from better quantitative understanding of in situ sulfate formation processes in the atmosphere. Multiple stable oxygen isotopic studies of atmospheric sulfate are presented as a new tool to better comprehend the atmospheric sulfate formation processes. Coupled with isotopic studies, 35S radioactivity measurements have been utilized to assess contribution of sulfate from high altitude air masses. Atmospheric sulfate (aerosols and rainwater) samples have been collected from diverse environments. Laboratory experiments of gas and aqueous phase S(IV) oxidation by various oxidants, as well as biomass burning experiments, have also been conducted. The main isotopic results from these studies are as follows: (1)Atmospheric (aerosol and rainwater) sulfate has a mass independent oxygen isotopic composition; (2)Aqueous phase S(IV) oxidation by atmospheric ozone and hydrogen peroxide are the source of the mass independent anomaly in atmospheric sulfate; (3)The mass independent oxygen isotopic anomaly appears to enhance with increasing altitude, suggesting a stratospheric contribution; (4)Primary sulfate from biomass burning has a mass dependent oxygen isotopic composition.

Organic containment separator

DOEpatents

Del Mar, Peter

1995-01-01

A process of sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium by (a) passing an initial aqueous medium including a minor amount of the organic contaminant through a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit the organic contaminant to adhere to the composite tube, (b) passing a solvent through the composite tube, said solvent capable of separating the adhered organic contaminant from the composite tube. Further, an extraction apparatus for sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium, said apparatus including a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit an organic contaminant contained within an aqueous medium passed therethrough to adhere to the composite tube is disclosed.

Organic contaminant separator

DOEpatents

Mar, Peter D.

1994-01-01

A process of sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium by (a) passing an initial aqueous medium including a minor amount of the organic contaminant through a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit the organic contaminant to adhere to the composite tube, (b) passing a solvent through the composite tube, said solvent capable of separating the adhered organic contaminant from the composite tube. Further, an extraction apparatus for sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium, said apparatus including a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit an organic contaminant contained within an aqueous medium passed therethrough to adhere to the composite tube is disclosed.

Anion-conducting polymer, composition, and membrane

DOEpatents

Pivovar, Bryan S [Los Alamos, NM; Thorn, David L [Los Alamos, NM

2011-11-22

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Anion-conducting polymer, composition, and membrane

DOEpatents

Pivovar, Bryan S [Los Alamos, NM; Thorn, David L [Los Alamos, NM

2009-09-01

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Anion-conducting polymer, composition, and membrane

DOEpatents

Pivovar, Bryan S.; Thorn, David L.

2010-12-07

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Anion-Conducting Polymer, Composition, and Membrane

DOEpatents

Pivovar, Bryan S.; Thorn, David L.

2008-10-21

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Anthracene and pyrene photolysis kinetics in aqueous, organic, and mixed aqueous-organic phases

NASA Astrophysics Data System (ADS)

Grossman, Jarod N.; Stern, Adam P.; Kirich, Makena L.; Kahan, Tara F.

2016-03-01

Condensed phases in the atmosphere, such as cloud droplets and aerosols, often contain both water and organic matter (OM). Reactivity can differ significantly between aqueous and organic phases. We have measured photolysis kinetics of the polycyclic aromatic hydrocarbons (PAHs) anthracene and pyrene in several organic solvents and in water, as well as in miscible and phase-separated aqueous-organic mixtures at atmospherically-relevant wavelengths. Photolysis rate constants generally increased with increasing solvent polarity; photolysis of both PAHs was more than ten times faster in water than in octanol. Local polarity had a much greater effect on PAH photolysis kinetics than changes in PAH absorptivity or singlet oxygen concentrations. Photolysis kinetics in homogeneous aqueous-organic mixtures varied monotonically with2 OM volume fraction. Kinetics in immiscible (phase-separated) solutions were more complex, with different dependences on OM content observed in stagnant and turbulent solutions. Our results suggest that OM could greatly affect the photochemical lifetimes of PAHs in atmospheric condensed phases such as aerosols, even if the OM does not itself absorb photons.

A CO2-Silica Geothermometer for Low Temperature Geothermal Resource Assessment, with Application to Resources in the Safford Basin, Arizona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witcher, James C.; Stone, Claudia

1983-11-01

Geothermics is the study of the earth's heat energy, it's affect on subsurface temperature distribution, it's physical and chemical sources, and it's role in dynamic geologic processes. The term, geothermometry, is applied to the determination of equilibrium temperatures of natural chemical systems, including rock, mineral, and liquid phases. An assemblage of minerals or a chemical system whose phase composition is a function of temperature and pressure can be used as a geothermometer. Thus a geothermometer is useful to determine the formation temperature of rock or the last equilibrium temperature of a flowing aqueous solution such as ground water and hydrothermalmore » fluids.« less

Kinetics, Mechanism, and Secondary Organic Aerosol Yield of Aqueous Phase Photo-oxidation of α-Pinene Oxidation Products.

PubMed

Aljawhary, Dana; Zhao, Ran; Lee, Alex K Y; Wang, Chen; Abbatt, Jonathan P D

2016-03-10

Formation of secondary organic aerosol (SOA) involves atmospheric oxidation of volatile organic compounds (VOCs), the majority of which are emitted from biogenic sources. Oxidation can occur not only in the gas-phase but also in atmospheric aqueous phases such as cloudwater and aerosol liquid water. This study explores for the first time the aqueous-phase OH oxidation chemistry of oxidation products of α-pinene, a major biogenic VOC species emitted to the atmosphere. The kinetics, reaction mechanisms, and formation of SOA compounds in the aqueous phase of two model compounds, cis-pinonic acid (PIN) and tricarballylic acid (TCA), were investigated in the laboratory; TCA was used as a surrogate for 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a known α-pinene oxidation product. Aerosol time-of-flight chemical ionization mass spectrometry (Aerosol-ToF-CIMS) was used to follow the kinetics and reaction mechanisms at the molecular level. Room-temperature second-order rate constants of PIN and TCA were determined to be 3.3 (± 0.5) × 10(9) and 3.1 (± 0.2) × 10(8) M(-1) s(-1), respectively, from which were estimated their condensed-phase atmospheric lifetimes. Aerosol-ToF-CIMS detected a large number of products leading to detailed reaction mechanisms for PIN and MBTCA. By monitoring the particle size distribution after drying, the amount of SOA material remaining in the particle phase was determined. An aqueous SOA yield of 40 to 60% was determined for PIN OH oxidation. Although recent laboratory studies have focused primarily on aqueous-phase processing of isoprene-related compounds, we demonstrate that aqueous formation of SOA materials also occurs from monoterpene oxidation products, thus representing an additional source of biogenically driven aerosol formation.

Determination of partition coefficients of biomolecules in a microfluidic aqueous two phase system platform using fluorescence microscopy.

PubMed

Silva, D F C; Azevedo, A M; Fernandes, P; Chu, V; Conde, J P; Aires-Barros, M R

2017-03-03

Aqueous two phase systems (ATPS) offer great potential for selective separation of a wide range of biomolecules by exploring differences in molecular solubility in each of the two immiscible phases. However, ATPS use has been limited due to the difficulty in predicting the behavior of a given biomolecule in the partition environment together with the empirical and time-consuming techniques that are used for the determination of partition and extraction parameters. In this work, a fast and novel technique based on a microfluidic platform and using fluorescence microscopy was developed to determine the partition coefficients of biomolecules in different ATPS. This method consists of using a microfluidic device with a single microchannel and three inlets. In two of the inlets, solutions containing the ATPS forming components were loaded while the third inlet was fed with the FITC tagged biomolecule of interest prepared in milli-Q water. Using fluorescence microscopy, it was possible to follow the location of the FITC-tagged biomolecule and, by simply varying the pumping rates of the solutions, to quickly test a wide variety of ATPS compositions. The ATPS system is allowed 4min for stabilization and fluorescence micrographs are used to determine the partition coefficient.The partition coefficients obtained were shown to be consistent with results from macroscale ATPS partition. This process allows for faster screening of partition coefficients using only a few microliters of material for each ATPS composition and is amenable to automation. The partitioning behavior of several biomolecules with molecular weights (MW) ranging from 5.8 to 150kDa, and isoelectric points (pI) ranging from 4.7 to 6.4 was investigated, as well as the effect of the molecular weight of the polymer ATPS component. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative analysis of nitrogen containing compounds in microalgae based bio-oils using comprehensive two-dimensional gas-chromatography coupled to nitrogen chemiluminescence detector and time of flight mass spectrometer.

PubMed

Toraman, Hilal E; Franz, Kristina; Ronsse, Frederik; Van Geem, Kevin M; Marin, Guy B

2016-08-19

Insight in the composition of the algae derived bio-oils is crucial for the development of efficient conversion processes and better upgrading strategies for microalgae. Comprehensive two-dimensional gas chromatography (GC×GC) coupled to nitrogen chemiluminescence detector (NCD) and time-of-flight mass spectrometer (TOF-MS) allows to obtain the detailed quantitative composition of the nitrogen containing compounds in the aqueous and the organic fraction of fast pyrolysis bio-oils from microalgae. Normal phase (apolar×mid-polar) and reverse phase column (polar×apolar) combination are investigated to optimize the separation of the detected nitrogen containing compounds. The reverse phase column combination gives the most detailed information in terms of the nitrogen containing compounds. The combined information from the GC×GC-TOF-MS (qualitative) and GC×GC-NCD (quantitative) with the use of a well-chosen internal standard, i.e. caprolactam, enables the identification and quantification of nitrogen containing compounds belonging to 13 different classes: amines, imidazoles, amides, imides, nitriles, pyrazines, pyridines, indoles, pyrazoles, pyrimidines, quinolines, pyrimidinediones and other nitrogen containing compounds which were not assigned to a specific class. The aqueous fraction mostly consists of amines (4.0wt%) and imidazoles (2.8wt%) corresponding to approximately 80wt% of the total identified nitrogen containing compounds. On the other hand, the organic fraction shows a more diverse distribution of nitrogen containing compounds with the majority of the compounds quantified as amides (3.0wt%), indoles (2.0wt%), amines (1.7wt%) and imides (1.3wt%) corresponding to approximately 65wt% of the total identified nitrogen containing compounds. Copyright © 2016 Elsevier B.V. All rights reserved.

Phase stability of Keplerate-type polyoxomolybdates controlled by added cationic surfactant.

PubMed

Fan, Dawei; Hao, Jingcheng

2009-05-15

Phase stability of two nanometer-scale Keplerate-type polyoxomolybdates, (NH(4))(42)[Mo(VI)(72)Mo(V)(60)O(372)(CH(3)COO)(30)(H(2)O)(72)]300H(2)O10CH(3)COONH(4) ({Mo(132)}) and Mo(VI)(72)Fe(III)(30)O(252)L(102)ca. 180H(2)O with L=H(2)O/CH(3)COO(-)/Mo(2)O(n-)(8/9) ({Mo(72)Fe(30)}), can be easily achieved by controlling the concentration of a cationic surfactant, tetradecyltrimethylammonium bromide (TTABr), in aqueous solution. Precipitates and floccules were observed when the stoichiometric ratios of rTTA+/{Mo132} and rTTA+/{Mo72Fe30} were 40:1 and 90:1, respectively, which were determined by zeta potential measurements. The surface charge properties and structure morphologies of {Mo(132)} and {Mo(72)Fe(30)} induced by controlling cationic TTABr in aqueous solution were determined by zeta potential measurements and transmission electron microscopy (TEM) observations. {Mo(132)} and {Mo(72)Fe(30)} can self-assemble into supramolecular "Blackberry" structures and exist at compositions less than the stoichiometric ratios of rTTA+/{Mo132} and rTTA+/{Mo72Fe30} in aqueous solution. Above the 1:1 stoichiometric ratio of TTABr/{Mo(132)} or TTABr/{Mo(72)Fe(30)}, the precipitates and floccules dissolve. Dynamic laser light scattering (DLS) measurements clearly demonstrated that the R(h) values have essentially no angular dependence at excess amounts of TTABr, suggesting the presence of spherically symmetric aggregates of {Mo(132)} and {Mo(72)Fe(30)}. Bilayer-like structures in aqueous solution were also demonstrated by TEM images. The interesting phase transition observed in our model systems of {Mo(132)} and {Mo(72)Fe(30)} macroanions with high chemical stability, similar shape, and masses could provide models for the understanding of more complex polyelectrolyte solutions and self-assembled soft magnetic materials and in bioapplications for highly selective adsorbents of proteins with different molecular sizes and charges.

Theoretical study on the dimerization of Si(OH) 4 in aqueous solution and its dependence on temperature and dielectric constant

NASA Astrophysics Data System (ADS)

Tossell, J. A.

2005-01-01

Energetics for the condensation dimerization reaction of monosilicic acid: 2Si(⇒SiOH+HO have been calculated quantum mechanically, in gas-phase and aqueous solution, over a range of temperatures and dielectric constants. The calculated gas phase energy, E g, for this reaction is -6.6 kcal/mol at the very accurate composite G2 level, but the vibrational, rotational and translational contributions to the free energy in the gas-phase, ΔG VRT, sum to + 2.5 kcal/mol and the hydration free energy contribution calculated with a polarizable continuum model, ΔΔG COSMO, for a dielectric constant of 78.5, is about + 6.2 kcal/mol. Thus, the free energy change for the reaction in aqueous solution at ambient conditions is about + 2.1 kcal/mol and the equilibrium constant is ˜10 -1.5, in reasonable agreement with experiment. As T increases, ΔG VRT increases slowly. As the dielectric constant decreases (for example, under high T and P conditions in the supercritical region), ΔΔG COSMO decreases substantially. Thus, at elevated T and P, if the effective dielectric constant of the aqueous fluid is 10 or less, the reaction becomes much more favorable, consistent with recent experimental observations. The PΔV contribution to the enthalpy is also considered, but cannot be accurately determined. We have also calculated 29Si-NMR shieldings and Raman frequencies for Si(OH) 4, Si 2O 7H 6 and some other oligomeric silicates. We correctly reproduce the separation of monomer and dimer peaks observed in the 29Si-NMR spectrra at ambient T and P. The Raman spectral data are somewhat ambiguous, and the new peaks seen at high T and P could arise either from the dimer or from a 3-ring trimer, which is calculated to be highly stabilized entropically at high T.

Aqueous-Phase Acetic Acid Ketonization over Monoclinic Zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Qiuxia; Lopez-Ruiz, Juan A.; Cooper, Alan R.

The effect of aqueous phase on the acetic acid ketonization over monoclinic zirconia has been investigated using first-principles based density functional theory (DFT) calculations. To capture the aqueous phase chemistry over the solid zirconia catalyst surface, the aqueous phase is represented by 111 explicit water molecules with a liquid water density of 0.93 g/cm3 and the monoclinic zirconia is modeled by the most stable surface structure . The dynamic nature of aqueous phase/ interface was studied using ab initio molecular dynamics simulation, indicating that nearly half of the surface Zr sites are occupied by either adsorbed water molecules or hydroxylmore » groups at 550 K. DFT calculations show that the adsorption process of acetic acid from the liquid water phase to the surface is nearly thermodynamically neutral with a Gibbs free energy of -2.3 kJ/mol although the adsorption strength of acetic acid on the surface in aqueous phase is much stronger than in vapor phase. Therefore it is expected that the adsorption of acetic acid will dramatically affects aqueous phase ketonization reactivity over the monoclinic zirconia catalyst. Using the same ketonization mechanism via the β-keto acid intermediate, we have compared acetic acid ketonization to acetone in both vapor and aqueous phases. Our DFT calculation results show although the rate-determining step of the β-keto acid formation via the C-C coupling is not pronouncedly affected, the presence of liquid water molecules will dramatically affect dehydrogenation and hydrogenation steps via proton transfer mechanism. This work was financially supported by the United States Department of Energy (DOE)’s Bioenergy Technologies Office (BETO) and performed at the Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program national laboratory operated for DOE by Battelle Memorial Institute. Computing time and advanced catalyst characterization use was granted by a user proposal at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research and located at PNNL.« less

Interactions of silicate glasses with aqueous environments under conditions of prolonged contact and flow

NASA Technical Reports Server (NTRS)

Barkatt, Aaron; Saad, E. E.; Adiga, R. B.; Sousanpour, W.; Barkatt, AL.; Feng, X.; O'Keefe, J. A.; Alterescu, S.

1988-01-01

This paper discusses mechanisms involving saturation and reactions that lead to the formation of altered phases in silicate glasses considered for use in geologic repositories for nuclear waste. It is shown that the rate of dissolution of silicate glasses exposed to a broad range of contact times, leachant compositions, and surface-to-volume ratios is strongly affected by the presence of reactive species such as Al, Mg, and Fe. The reactive materials may originate in the leachant or, under conditions of high surface-to-volume ratio, in the glass itself. The effects of glass composition on the course of the corrosion process can be viewed in terms of the formation of a surface layer on the leached glass; the type, composition, and structure of this layer control the dissolution behavior of the glass.

Composite Films Formed by Cellulose nanocrystals and Latex Nanoparticles: Optical, Structural, and Mechanical Properties

NASA Astrophysics Data System (ADS)

Vollick, Brandon McRae

This thesis describes the preparation of iridescent, birefringent, composite films composed of cellulose nanocrystals (CNCs), latex nanoparticles (NPs) and a NP crosslinker; hexanediamine (HDA). First, aqueous suspensions were prepared with varying quantities of CNCs, NPs and HDA before equilibrating for one week. The cholesteric (Ch) phase was then cast and dried into a film. The optical, structural and mechanical properties of the film was analyzed. Second, films with identical compositions of CNCs, NPs, and HDA were fabricated in three different ways to yield films of different morphology, (i) fast drying of an isotropic suspension, yielding an isotropic film, (ii) slow drying of an isotropic suspension, yielding a partially Ch films, (iii) slow drying of an equilibrated suspension, yielding a highly Ch film. The optical and mechanical properties of the films was analyzed.

Chemical consequences of the initial diffusional growth of cloud droplets - A clean marine case

NASA Technical Reports Server (NTRS)

Twohy, C. H.; Charlson, R. J.; Austin, P. H.

1989-01-01

A simple microphysical cloud parcel model and a simple representation of the background marine aerosol are used to predict the concentrations and compositions of droplets of various sizes near cloud base. The aerosol consists of an externally-mixed ammonium bisulfate accumulation mode and a sea-salt coarse particle mode. The difference in diffusional growth rates between the small and large droplets as well as the differences in composition between the two aerosol modes result in substantial differences in solute concentration and composition with size of droplets in the parcel. The chemistry of individual droplets is not, in general, representative of the bulk (volume-weighted mean) cloud water sample. These differences, calculated to occur early in the parcel's lifetime, should have important consequences for chemical reactions such as aqueous phase sulfate production.

HANFORD RIVER PROTECTION PROJECT ENHANCED MISSION PLANNING THROUGH INNOVATIVE TOOLS LIFECYCLE COST MODELING AND AQUEOUS THERMODYNAMIC MODELING - 12134

DOE Office of Scientific and Technical Information (OSTI.GOV)

PIERSON KL; MEINERT FL

2012-01-26

Two notable modeling efforts within the Hanford Tank Waste Operations Simulator (HTWOS) are currently underway to (1) increase the robustness of the underlying chemistry approximations through the development and implementation of an aqueous thermodynamic model, and (2) add enhanced planning capabilities to the HTWOS model through development and incorporation of the lifecycle cost model (LCM). Since even seemingly small changes in apparent waste composition or treatment parameters can result in large changes in quantities of high-level waste (HLW) and low-activity waste (LAW) glass, mission duration or lifecycle cost, a solubility model that more accurately depicts the phases and concentrations ofmore » constituents in tank waste is required. The LCM enables evaluation of the interactions of proposed changes on lifecycle mission costs, which is critical for decision makers.« less

REMOVAL OF CHLORIDE FROM AQUEOUS SOLUTIONS

DOEpatents

Schulz, W.W.

1959-08-01

The removal of chlorides from aqueons solutions is described. The process involves contacting the aqueous chloride containing solution with a benzene solution about 0.005 M in phenyl mercuric acetate whereby the chloride anions are taken up by the organic phase and separating the organic phase from the aqueous solutions.

A Thermodynamic Model for Predicting Mineral Reactivity in Supercritical Carbon Dioxide: I. Phase Behavior of Carbon Dioxide - Water - Chloride Salt Systems Across the H2O-Rich to the CO2-Rich Regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Springer, Ronald D.; Wang, Zheming; Anderko, Andre

Phase equilibria in mixtures containing carbon dioxide, water, and chloride salts have been investigated using a combination of solubility measurements and thermodynamic modeling. The solubility of water in the CO2-rich phase of ternary mixtures of CO2, H2O and NaCl or CaCl2 was determined, using near infrared spectroscopy, at 90 atm and 40 to 100 °C. These measurements fill a gap in the experimental database for CO2 water salt systems, for which phase composition data have been available only for the H2O-rich phases. A thermodynamic model for CO2 water salt systems has been constructed on the basis of the previously developedmore » Mixed-Solvent Electrolyte (MSE) framework, which is capable of modeling aqueous solutions over broad ranges of temperature and pressure, is valid to high electrolyte concentrations, treats mixed-phase systems (with both scCO2 and water present) and can predict the thermodynamic properties of dry and partially water-saturated supercritical CO2 over broad ranges of temperature and pressure. Within the MSE framework the standard-state properties are calculated from the Helgeson-Kirkham-Flowers equation of state whereas the excess Gibbs energy includes a long-range electrostatic interaction term expressed by a Pitzer-Debye-Hückel equation, a virial coefficient-type term for interactions between ions and a short-range term for interactions involving neutral molecules. The parameters of the MSE model have been evaluated using literature data for both the H2O-rich and CO2-rich phases in the CO2 - H2O binary and for the H2O-rich phase in the CO2 - H2O - NaCl / KCl / CaCl2 / MgCl2 ternary and multicompontent systems. The model accurately represents the properties of these systems at temperatures from 0°C to 300 °C and pressures up to ~4000 atm. Further, the solubilities of H2O in CO2-rich phases that are predicted by the model are in agreement with the new measurements for the CO2 - H2O - NaCl and CO2 - H2O - CaCl2 systems. Thus, the model can be used to predict the effect of various salts on the water content and water activity in CO2-rich phases on the basis of parameters determined from the properties of aqueous systems. Given the importance of water activity in CO2-rich phases for mineral reactivity, the model can be used as a foundation for predicting mineral transformations across the entire CO2/H2O composition range from aqueous solution to anhydrous scCO2. An example application using the model is presented which involves the transformation of forsterite to nesquehonite as a function of temperature and water content in the CO2-rich phase.« less

Oxygen, Magnesium, and Aluminum Isotopes in the Ivuna CAI: Re-Examining High-Temperature Fractionations in CI Chondrites

NASA Technical Reports Server (NTRS)

Frank, D. R.; Huss, G. R.; Nagashima, K.; Zolensky, M. E.; Le, L.

2017-01-01

CI chondrites are thought to approximate the bulk solar system composition since they closely match the composition of the solar photosphere. Thus, chemical differences between a planetary object and the CI composition are interpreted to result from fractionations of a CI starting composition. This interpretation is often made despite the secondary mineralogy of CI chondrites, which resulted from low-T aqueous alteration on the parent asteroid(s). Prevalent alteration and the relatively large uncertainties in the photospheric abundances (approx. +/-5-10%) permit chemical fractionation of CI chondrites from the bulk solar system, if primary chondrules and/or CAIs have been altered beyond recognition. Isolated olivine and pyroxene grains that range from approx. 5 microns to several hundred microns have been reported in CI chondrites, and acid residues of Orgueil were found to contain refractory oxides with oxygen isotopic compositions matching CAIs. However, the only CAI found to be unambiguously preserved in a CI chondrite was identified in Ivuna. The Ivuna CAI's primary mineralogy, small size (approx.170 microns), and fine-grained igneous texture classify it as a compact type A. Aqueous alteration infiltrated large portions of the CAI, but other regions remain pristine. The major primary phases are melilite (Ak 14-36 ), grossmanite (up to 20.8 wt.% TiO 2 ), and spinel. Both melilite and grossmanite have igneous textures and zoning patterns. An accretionary rim consists primarily of olivine (Fa 2-17 ) and low-Ca pyroxene (Fs 2-10 ), which could be either surviving CI2 material or a third lithology.

Arsenic interactions with a fullerene-like BN cage in the vacuum and aqueous phase.

PubMed

Beheshtian, Javad; Peyghan, Ali Ahmadi; Bagheri, Zargham

2013-02-01

Adsorption of arsenic ions, As (III and V), on the surface of fullerene-like B(12)N(12) cage has been explored in vacuum and aqueous phase using density functional theory in terms of Gibbs free energies, enthalpies, geometry, and density of state analysis. It was found that these ions can be strongly chemisorbed on the surface of the cluster in both vacuum and aqueous phase, resulting in significant changes in its electronic properties so that the cluster transforms from a semi-insulator to a semiconductor. The solvent significantly affects the geometry parameters and electronic properties of the As/B(12)N(12) complexes and the interaction between components is considerably weaker in the aqueous phase than that in the vacuum.

Manganese-calcium intermixing facilitates heteroepitaxial growth at the (1014) calcite-water interface

DOE PAGES

Xu, Man; Riechers, Shawn L.; Ilton, Eugene S.; ...

2017-09-05

For this research, in situ atomic force microscopy (AFM) measurements were performed to probe surface precipitates that formed on the (10more » $$\\bar{1}$$4) surface of calcite (CaCO 3) single crystals following reaction with Mn2 +-bearing aqueous solutions. Three-dimensional epitaxial islands were observed to precipitate and grow on the surfaces. In situ time-sequenced measurements demonstrated that the growth rates were commensurate with those obtained for epitaxial islands formed on calcite crystals reacted with Cd2 +-bearing aqueous solutions of the same range in supersaturation with respect to the pure metal carbonate phase. This finding was unexpected as rhodochrosite (MnCO 3) and calcite display a 10% lattice mismatch, based on the area of their (10$$\\bar{1}$$4) surface unit cells, whereas the lattice mismatch is only 4% for otavite (CdCO 3) and calcite. Coatings of varying thicknesses were therefore synthesized by reacting calcite single crystals in calcite-equilibrated aqueous solutions with up to 250 μM MnCl 2. Ex situ X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectivity (XRR), and AFM measurements of the reacted crystals demonstrated the formation of an epitaxial (Mn,Ca)CO 3 solid solution. The epitaxial solid solution had a spatially complex composition, whereby the first few nanometers were rich in Ca and the Mn content increased with distance from the original calcite surface, culminating in a topmost region of almost pure MnCO 3 for the thickest coatings. The effective lattice mismatch was therefore much smaller than the nominal mismatch thus explaining the measured growth rates. Lastly, these findings highlight the strong influence played by the substrate on the composition of surface precipitates in aqueous conditions.« less

Novel cellulose-based halochromic test strips for naked-eye detection of alkaline vapors and analytes.

PubMed

Abou-Yousef, Hussein; Khattab, Tawfik A; Youssef, Yehia A; Al-Balakocy, Naser; Kamel, Samir

2017-08-01

A simple, portable and highly sensitive naked-eye test strip is successfully prepared for optical detection of gaseous and aqueous alkaline analytes. Novel pH-sensory tricyanofuran-hydrazone (TCFH) disperse colorant containing a hydrazone recognition functional moiety is successfully synthesized via azo-coupling reaction between active methyl-containing tricyanofuran (TCF) heterocycle and diazonium salt of 4-aminobenzaldehyde followed by Knoevenagel condensation with malononitrile. UV-vis absorption spectra display solvatochromism and reversible color changes of the TCFH solution in dimethyl sulfoxide in response to pH variations. We investigate the preparation of hydrophobic cellulose/polyethylene terephthalate composites characterized by their high affinity for disperse dyes. Composite films made from CA, Cell/CA, PET/CA, and Cell/PET-CA are produced via solvent-casting procedure using 10-30% modified cellulose or modified polyethylene terephthalate. The mechanical properties and morphologies of these composite films are investigated. The prepared pH-sensory hydrazone-based disperse dye is then applied to dye the produced cellulose-based composite films employing the high temperature pressure dyeing procedure. The produced halochromic PET-CA-TCFH test strip provide an instant visible signal from orange to purple upon exposure to alkaline conditions as proved by the coloration measurements. The sensor strip exhibits high sensitivity and quick detection toward ammonia in both of aqueous and vapor phases by naked-eye observations at room temperature and atmospheric pressure. Copyright © 2017 Elsevier B.V. All rights reserved.

Photochemistry of aqueous pyruvic acid

PubMed Central

Griffith, Elizabeth C.; Carpenter, Barry K.; Shoemaker, Richard K.; Vaida, Veronica

2013-01-01

The study of organic chemistry in atmospheric aerosols and cloud formation is of interest in predictions of air quality and climate change. It is now known that aqueous phase chemistry is important in the formation of secondary organic aerosols. Here, the photoreactivity of pyruvic acid (PA; CH3COCOOH) is investigated in aqueous environments characteristic of atmospheric aerosols. PA is currently used as a proxy for α-dicarbonyls in atmospheric models and is abundant in both the gas phase and the aqueous phase (atmospheric aerosols, fog, and clouds) in the atmosphere. The photoreactivity of PA in these phases, however, is very different, thus prompting the need for a mechanistic understanding of its reactivity in different environments. Although the decarboxylation of aqueous phase PA through UV excitation has been studied for many years, its mechanism and products remain controversial. In this work, photolysis of aqueous PA is shown to produce acetoin (CH3CHOHCOCH3), lactic acid (CH3CHOHCOOH), acetic acid (CH3COOH), and oligomers, illustrating the progression from a three-carbon molecule to four-carbon and even six-carbon molecules through direct photolysis. These products are detected using vibrational and electronic spectroscopy, NMR, and MS, and a reaction mechanism is presented accounting for all products detected. The relevance of sunlight-initiated PA chemistry in aqueous environments is then discussed in the context of processes occurring on atmospheric aerosols. PMID:23821751

Direct NMR Monitoring of Phase Separation Behavior of Highly Supersaturated Nifedipine Solution Stabilized with Hypromellose Derivatives.

PubMed

Ueda, Keisuke; Higashi, Kenjirou; Moribe, Kunikazu

2017-07-03

We investigated the phase separation behavior and maintenance mechanism of the supersaturated state of poorly water-soluble nifedipine (NIF) in hypromellose (HPMC) derivative solutions. Highly supersaturated NIF formed NIF-rich nanodroplets through phase separation from aqueous solution containing HPMC derivative. Dissolvable NIF concentration in the bulk water phase was limited by the phase separation of NIF from the aqueous solution. HPMC derivatives stabilized the NIF-rich nanodroplets and maintained the NIF supersaturation with phase-separated NIF for several hours. The size of the NIF-rich phase was different depending on the HPMC derivatives dissolved in aqueous solution, although the droplet size had no correlation with the time for which NIF supersaturation was maintained without NIF crystallization. HPMC acetate and HPMC acetate succinate (HPMC-AS) effectively maintained the NIF supersaturation containing phase-separated NIF compared with HPMC. Furthermore, HPMC-AS stabilized NIF supersaturation more effectively in acidic conditions. Solution 1 H NMR measurements of NIF-supersaturated solution revealed that HPMC derivatives distributed into the NIF-rich phase during the phase separation of NIF from the aqueous solution. The hydrophobicity of HPMC derivative strongly affected its distribution into the NIF-rich phase. Moreover, the distribution of HPMC-AS into the NIF-rich phase was promoted at lower pH due to the lower aqueous solubility of HPMC-AS. The distribution of a large amount of HPMC derivatives into NIF-rich phase induced the strong inhibition of NIF crystallization from the NIF-rich phase. Polymer distribution into the drug-rich phase directly monitored by solution NMR technique can be a useful index for the stabilization efficiency of drug-supersaturated solution containing a drug-rich phase.

URANIUM SEPARATION PROCESS

DOEpatents

McVey, W.H.; Reas, W.H.

1959-03-10

The separation of uranium from an aqueous solution containing a water soluble uranyl salt is described. The process involves adding an alkali thiocyanate to the aqueous solution, contacting the resulting solution with methyl isobutyl ketons and separating the resulting aqueous and organic phase. The uranium is extracted in the organic phase as UO/sub 2/(SCN)/sub/.

Dissolution of barite for the analysis of strontium isotopes and other chemical and isotopic variations using aqueous sodium carbonate

USGS Publications Warehouse

Breit, G.N.; Simmons, E.C.; Goldhaber, M.B.

1985-01-01

A simple procedure for preparing barite samples for chemical and isotopic analysis is described. Sulfate ion, in barite, in the presence of high concentrations of aqueous sodium carbonate, is replaced by carbonate. This replacement forms insoluble carbonates with the cations commonly in barite: Ba, Sr, Ca and Pb. Sulfate is released into the solution by the carbonate replacement and is separated by filtration. The aqueous sulfate can then be reprecipitated for analysis of the sulfur and oxygen isotopes. The cations in the carbonate phase can be dissolved by acidifying the solid residue. Sr can be separated from the solution for Sr isotope analysis by ion-exchange chromatography. The sodium carbonate used contains amounts of Sr which will affect almost all barite 87Sr 86Sr ratios by less than 0.00001 at 1.95?? of the mean. The procedure is preferred over other techniques used for preparing barite samples for the determination of 87Sr 86Sr ratios because it is simple, rapid and enables simultaneous determination of many compositional parameters on the same material. ?? 1985.

Solution-phase electronegativity scale: insight into the chemical behaviors of metal ions in solution.

PubMed

Li, Keyan; Li, Min; Xue, Dongfeng

2012-04-26

By incorporating the solvent effect into the Born effective radius, we have proposed an electronegativity scale of metal ions in aqueous solution with the most common oxidation states and hydration coordination numbers in terms of the effective ionic electrostatic potential. It is found that the metal ions in aqueous solution are poorer electron acceptors compared to those in the gas phase. This solution-phase electronegativity scale shows its efficiency in predicting some important properties of metal ions in aqueous solution such as the aqueous acidities of the metal ions, the stability constants of metal complexes, and the solubility product constants of the metal hydroxides. We have elaborated that the standard reduction potential and the solution-phase electronegativity are two different quantities for describing the processes of metal ions in aqueous solution to soak up electrons with different final states. This work provides a new insight into the chemical behaviors of the metal ions in aqueous solution, indicating a potential application of this electronegativity scale to the design of solution reactions.

Cloud chemistry in eastern China: Observations from Mt. Tai

NASA Astrophysics Data System (ADS)

Collett, J. L.; Shen, X.; Lee, T.; Wang, X.; Li, Y.; Wang, W.; Wang, T.

2010-07-01

Until recently, studies of fog and cloud chemistry in China have been rare - even though the fate of China’s large sulfur dioxide emissions depends, in part, on the ability of regional clouds to support rapid aqueous oxidation to sulfate. Sulfur dioxide oxidized in regional clouds is more likely to be removed by wet deposition while sulfur dioxide that undergoes slower gas phase oxidation is expected to survive longer in the atmosphere and be transported over a much broader spatial scale. Two 2008 field campaigns conducted at Mt. Tai, an isolated peak on the NE China plain, provide insight into the chemical composition of regional clouds and the importance of various aqueous phase sulfur oxidation pathways. Single and two-stage Caltech Active Strand Cloudwater Collectors were used to collect bulk and drop size-resolved samples of cloudwater. Collected cloudwater was analyzed for key species that influence in-cloud sulfate production, including pH, S(IV), H2O2, Fe and Mn. Other major cloud solutes, including inorganic ions, total organic carbon (TOC), formaldehyde, and organic acids were also analyzed, as were gas phase concentrations of SO2, O3, and H2O2. A wide range of cloud pH was observed, from below 3 to above 6. High concentrations of cloudwater sulfate were consistent with abundant sulfur dioxide emissions in the region. Sampled clouds were also found to contain high concentrations of ammonium, nitrate, and organic carbon. Peak TOC concentrations reached approximately 200 ppmC, among the highest concentrations ever measured in cloudwater. Hydrogen peroxide was found to be the dominant aqueous phase S(IV) oxidant when cloud pH was less than approximately 5.4. Despite its fast reaction with sulfur dioxide in cloud droplets, high concentrations of residual hydrogen peroxide were measured in some clouds implying a substantial additional capacity for sulfate production. Ozone was found to be an important S(IV) oxidant when cloud pH was high. Oxidation of S(IV) by oxygen, catalyzed by Fe (III) and Mn(II) was generally the second or third fastest pathway for sulfate production. Differences between the pH and trace metal concentrations of small and large cloud droplets were observed, giving rise to aqueous phase sulfate production rates that were drop size-dependent for the ozone and metal-catalyzed pathways.

Studies of Physicochemical Processes in Atmospheric Particles and Acid Deposition.

NASA Astrophysics Data System (ADS)

Pandis, Spyros N.

A comprehensive chemical mechanism for aqueous -phase atmospheric chemistry was developed and its detailed sensitivity analysis was performed. The main aqueous-phase reaction pathways for the system are the oxidation of S(IV) to S(VI) by H_2O_2 , OH, O_2 (catalysed by Fe ^{3+} and Mn^ {2+}), O_3 and HSO_sp{5}{-}. The gas-phase concentrations of SO_2, H_2O_2, HO _2, OH, O_3 HCHO, NH_3, HNO_3 and HCl and the liquid water content of the cloud are of primary importance. The Lagrangian model predictions for temperature profile, fog development, liquid water content, gas-phase concentrations of SO_2 , HNO_3, and NH_3 , pH, aqueous-phase concentrations of SO _sp{4}{2-}, NH _sp{4}{+} and NO _sp{3}{-}, and finally deposition rates of the above ions match well the observed values. A third model was developed to study the distribution of acidity and solute concentration among the various droplet sizes in a fog or a cloud. Significant solute concentration differences can occur in aqueous droplets inside a fog or a cloud. Fogs in polluted environments have the potential to increase aerosol sulfate concentrations, but at the same time to cause reductions in the aerosol concentration of nitrate, chloride, ammonium and sodium as well as in the total aerosol mass concentration. The sulfate producd during fog episodes favors the aerosol particles that have access to most of the fog liquid water. Aerosol scavenging efficiencies of around 80% were calculated for urban fogs. Sampling and subsequent mixing of fog droplets of different sizes may result in measured concentrations that are not fully representative of the fogwater chemical composition. Isoprene and beta-pinene, at concentration levels ranging from a few ppb to a few ppm were reacted photochemically with NO_ {x} in the Caltech outdoor smog chamber facility. Aerosol formation from the isoprene photooxidation was found to be negligible even under extreme ambient conditions due to the relatively high vapor pressure of its condensable products. Aerosol carbon yield from the beta -pinene photooxidation is as high as 8% and depends strongly on the initial HC/NO_{x} ratio. Monoterpene photooxidation can be a significant source of secondary aerosol in rural environments and in urban areas with extended natural vegetation. (Abstract shortened with permission of author.).

Effect of lipophilization on the distribution and reactivity of ingredients in emulsions.

PubMed

Leong, Wai Fun; Berton-Carabin, Claire C; Elias, Ryan J; Lecomte, Jérôme; Villeneuve, Pierre; Zhao, Yu; Coupland, John N

2015-12-01

The reactivity of small molecules in emulsions is believed to depend on their partitioning between phases, yet this is hard to verify experimentally in situ. In the present work, we use electron paramagnetic resonance (EPR) spectroscopy to simultaneously measure the distribution and reactivity of a homologous series of lipophilized spin probes in an emulsion. 4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL) was derivatized with saturated fatty acids to create a series of spin probes with increasing lipophilicity (C4-, C8-, C12-, and C16-TEMPO). The probes were added to a 10 wt.% tetradecane-in water emulsions (d32∼190 nm) stabilized with sodium caseinate (1 wt.% in the aqueous phase, pH 7). The distribution of the probes between phases was measured by electron paramagnetic resonance (EPR) spectroscopy. TEMPOL partitioned into the aqueous phase, C4-TEMPO distributed between the lipid and aqueous phases (69% and 31% respectively) while the more lipophilic probes dissolved exclusively within the lipid droplets. Interestingly, the more lipophilic probes initially precipitated upon their addition to the emulsion, and only slowly redistributed to the droplets over hours or days, the rate of which was dependent on their carbon chain length. The reactivity of the probes with aqueous an aqueous phase reductant (ascorbate) generally depended on the proportion in the aqueous phase (i.e., TEMPOL>C4-TEMPO>C8-TEMPO∼C12-TEMPO∼C16-TEMPO). Copyright © 2015 Elsevier Inc. All rights reserved.

Summary report for the FY-2015 SACSESS Collaboration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterman, Dean Richard; Mincher, Bruce Jay

2015-09-01

During FY-2015, a collaborative research program was established by the Department of Energy-Nuclear Energy (DOE-NE) Material Recovery and Waste Form Development program and the European Union (EU) Safety of Actinide Separation Processes (SACSESS) program. One component of this collaboration was the evaluation of the radiolytic stability of a Selective ActiNide Extraction (SANEX) separation which utilized a TODGA-based organic solvent and an aqueous phase containing the hydrophilic complexing reagent, SO3-Ph-BTP. To best simulate process conditions, this experiment was irradiated in the radiolysis/hydrolysis test loop located at the Idaho National Laboratory. The effect of irradiation on a SACSESS program iSANEX formulation containingmore » a TODGA-based organic phase and a BTP-based aqueous phase was investigated using irradiations at INL in static and test loop modes. When irradiated in contact with only the acidic aqueous phase, the TODGA organic solution maintained excellent extraction performance of americium, cerium and europium to a maximum absorbed dose of nearly 0.9 MGy. When the aqueous phase was changed to that containing the aqueous soluble BTP, the irradiated aqueous phase showed a dramatic color change, but this does not appear to have adverse effects on solvent extraction performance. Only minor increases in distribution ratios for both the lanthanides and actinide were measured, and the separation factors were essentially unchanged to a maximum absorbed dose of 174 kGy. The determination of the americium, cerium, and europium distribution ratios for the remaining SACSESS test loop samples will be completed in the near future. The analysis of stable metals concentration in the the irradiated aqueous and organic phases will be completed shortly.« less

Investigation of sorption interactions between oil shale principal mineral phases and organic compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowen, J.M.

1988-09-01

The interactions between minerals representative of the bulk composition of oil shales and organic compounds that have been found in oil shale leachates were investigated. The method used to directly determine the type of interactions that could take place between organic compounds and oil shale mineral phases was Fourier transform infrared spectroscopy (FTIR) using several advanced detection methods, including diffuse reflectance (DRIFT) and photoacoustics (PAS). The minerals that were investigated include quartz, calcite, and dolomite, which are known to figure significantly in the composition of processed oil shales. The organic chemical compounds used were chosen from a list of compoundsmore » identified in spent oil shale leachates, and they include pyridine, phenol, p-cresol, and acetone. The sorption interactions for the study were prepared by exposing each of the minerals to the organic compounds by three different methods. These were vapor deposition, direct application, and immersion in an aqueous solution at pH 12. 41 refs., 3 figs., 4 tabs.« less

Nonequilibrium Thermodynamics of Hydrate Growth on a Gas-Liquid Interface

NASA Astrophysics Data System (ADS)

Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

2018-04-01

We develop a continuum-scale phase-field model to study gas-liquid-hydrate systems far from thermodynamic equilibrium. We design a Gibbs free energy functional for methane-water mixtures that recovers the isobaric temperature-composition phase diagram under thermodynamic equilibrium conditions. The proposed free energy is incorporated into a phase-field model to study the dynamics of hydrate formation on a gas-liquid interface. We elucidate the role of initial aqueous concentration in determining the direction of hydrate growth at the interface, in agreement with experimental observations. Our model also reveals two stages of hydrate growth at an interface—controlled by a crossover in how methane is supplied from the gas and liquid phases—which could explain the persistence of gas conduits in hydrate-bearing sediments and other nonequilibrium phenomena commonly observed in natural methane hydrate systems.

Phase-separable aqueous amide solutions as a thermal history indicator.

PubMed

Kitsunai, Makoto; Miyajima, Kentaro; Mikami, Yuzuru; Kim, Shokaku; Hirasawa, Akira; Chiba, Kazuhiro

2008-12-01

Aqueous solutions of several new amide compounds for use as simple thermal history indicators in the low-temperature transport of food and other products were synthesized. The phase transition temperatures of the aqueous solutions can be freely adjusted by changing the amide-water ratio in solution, the sodium chloride concentration of the water, and the type of amide compound. It is expected that these aqueous solutions can be applied as new thermal history indicators.

Chemical composition of an aqueous oxalato-/citrato-VO(2+) solution as determinant for vanadium oxide phase formation.

PubMed

Peys, Nick; Maurelli, Sara; Reekmans, Gunter; Adriaensens, Peter; De Gendt, Stefan; Hardy, An; Van Doorslaer, Sabine; Van Bael, Marlies K

2015-01-05

Aqueous solutions of oxalato- and citrato-VO(2+) complexes are prepared, and their ligand exchange reaction is investigated as a function of the amount of citrate present in the aqueous solution via continuous-wave electron paramagnetic resonance (CW EPR) and hyperfine sublevel correlation (HYSCORE) spectroscopy. With a low amount of citrate, monomeric cis-oxalato-VO(2+) complexes occur with a distorted square-pyramidal geometry. As the amount of citrate increases, oxalate is gradually exchanged for citrate. This leads to (i) an intermediate situation of monomeric VO(2+) complexes with a mix of oxalate/citrate ligands and (ii) a final situation of both monomeric and dimeric complexes with exclusively citrato ligands. The monomeric citrato-VO(2+) complexes dominate (abundance > 80%) and are characterized by a 6-fold chelation of the vanadium(IV) ion by 4 RCO2(-) ligands at the equatorial positions and a H2O/R-OH ligand at the axial position. The different redox stabilities of these complexes, relative to that of dissolved O2 in the aqueous solution, is analyzed via (51)V NMR. It is shown that the oxidation rate is the highest for the oxalato-VO(2+) complexes. In addition, the stability of the VO(2+) complexes can be drastically improved by evacuation of the dissolved O2 from the solution and subsequent storage in a N2 ambient atmosphere. The vanadium oxide phase formation process, starting with the chemical solution deposition of the aqueous solutions and continuing with subsequent processing in an ambient 0.1% O2 atmosphere, differs for the two complexes. The oxalato-VO(2+) complexes turn into the oxygen-deficient crystalline VO2 B at 400 °C, which then turns into crystalline V6O13 at 500 °C. In contrast, the citrato-VO(2+) complexes form an amorphous film at 400 °C that crystallizes into VO2 M1 and V6O13 at 500 °C.

Antinociceptive properties of the aqueous and methanol extracts of the stem bark of Petersianthus macrocarpus (P. Beauv.) Liben (Lecythidaceae) in mice.

PubMed

Bomba, Francis Desire Tatsinkou; Wandji, Bibiane Aimee; Piegang, Basile Nganmegne; Awouafack, Maurice Ducret; Sriram, Dharmarajan; Yogeeswari, Perumal; Kamanyi, Albert; Nguelefack, Telesphore Benoit

2015-11-04

Aqueous maceration from the stem barks of Petersianthus macrocarpus (P. Beauv.) Liben (Lecythidaceae) is taken orally in the central Africa for the management of various ailments, including pain. This work was carried out to evaluate in mice, the antinociceptive effects of the aqueous and methanol extracts of the stem bark of P. macrocarpus. The chemical composition of the aqueous and methanol extracts prepared as cold macerations was determined by high performance liquid chromatography coupled with mass spectrometry (LCMS). The antinociceptive effects of these extracts administered orally at the doses of 100, 200 and 400 mg/kg were evaluated using behavioral pain model induced by acetic acid, formalin, hot-plate, capsaicin and glutamate. The rotarod test was also performed at the same doses. The oral acute toxicity of both extracts was studied at the doses of 800, 1600, 3200 and 6400 mg/kg in mice. The LCMS analysis revealed the presence of ellagic acid as the major constituent in the methanol extract. Both extracts of P. macrocarpus significantly and dose dependently reduced the time and number of writhing induced by acetic acid. They also significantly inhibited the two phases of formalin-induced pain. These effects were significantly inhibited by a pretreatment with naloxone, except for the analgesic activity of the methanol extract at the earlier phase. In addition, nociception induced by hot plate, intraplantar injection of capsaicin or glutamate was significantly inhibited by both extracts. Acute toxicity test showed no sign of toxicity. These results demonstrate that aqueous and methanol extracts of P. macrocarpus are none toxic substances with good central and peripheral antinociceptive effects that are at least partially due to the presence of ellagic acid. These extracts may induce their antinociceptive effect by interfering with opioid, capsaicin and excitatory amino acid pathways. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Key Role of Nitrate in Phase Transitions of Urban Particles: Implications of Important Reactive Surfaces for Secondary Aerosol Formation

NASA Astrophysics Data System (ADS)

Sun, Jiaxing; Liu, Lei; Xu, Liang; Wang, Yuanyuan; Wu, Zhijun; Hu, Min; Shi, Zongbo; Li, Yongjie; Zhang, Xiaoye; Chen, Jianmin; Li, Weijun

2018-01-01

Ammonium sulfate (AS) and ammonium nitrate (AN) are key components of urban fine particles. Both field and model studies showed that heterogeneous reactions of SO2, NO2, and NH3 on wet aerosols accelerated the haze formation in northern China. However, little is known on phase transitions of AS-AN containing haze particles. Here hygroscopic properties of laboratory-generated AS-AN particles and individual particles collected during haze events in an urban site were investigated using an individual particle hygroscopicity system. AS-AN particles showed a two-stage deliquescence at mutual deliquescence relative humidity (MDRH) and full deliquescence relative humidity (DRH) and three physical states: solid before MDRH, solid-aqueous between MDRH and DRH, and aqueous after DRH. During hydration, urban haze particles displayed a solid core and aqueous shell at RH = 60-80% and aqueous phase at RH > 80%. Most particles were in aqueous phase at RH > 50% during dehydration. Our results show that AS content in individual particles determines their DRH and AN content determines their MDRH. AN content increase can reduce MDRH, which indicates occurrence of aqueous shell at lower RH. The humidity-dependent phase transitions of nitrate-abundant urban particles are important to provide reactive surfaces of secondary aerosol formation in the polluted air.

Aqueous-phase mechanism for secondary organic aerosol formation from isoprene: application to the southeast United States and co-benefit of SO2 emission controls

EPA Science Inventory

Isoprene emitted by vegetation is an important precursor of secondary organic aerosol (SOA), but the mechanism and yields are uncertain. Aerosol is prevailingly aqueous under the humid conditions typical of isoprene-emitting regions. Here we develop an aqueous-phase mechanism for...

Efflorescence of ammonium sulfate and coated ammonium sulfate particles: evidence for surface nucleation.

PubMed

Ciobanu, V Gabriela; Marcolli, Claudia; Krieger, Ulrich K; Zuend, Andreas; Peter, Thomas

2010-09-09

Using optical microscopy, we investigated the efflorescence of ammonium sulfate (AS) in aqueous AS and in aqueous 1:1 and 8:1 (by dry weight) poly(ethylene glycol)-400 (PEG-400)/AS particles deposited on a hydrophobically coated slide. Aqueous PEG-400/AS particles exposed to decreasing relative humidity (RH) exhibit a liquid-liquid phase separation below approximately 90% RH with the PEG-400-rich phase surrounding the aqueous AS inner phase. Pure aqueous AS particles effloresced in the RH range from 36.3% to 43.7%, in agreement with literature data (31-48% RH). In contrast, aqueous 1:1 (by dry weight) PEG-400/AS particles with diameters of the AS phase from 7.2 to 19.2 mum effloresced between 26.8% and 33.9% RH and aqueous 8:1 (by dry weight) PEG-400/AS particles with diameters of the AS phase from 1.8 to 7.3 mum between 24.3% and 29.3% RH. Such low efflorescence relative humidity (ERH) values have never been reached before for AS particles of this size range. We show that these unprecedented low ERHs of AS in PEG-400/AS particles could not possibly be explained by the presence of low amounts of PEG-400 in the aqueous AS phase, by a potential inhibition of water evaporation via anomalously slow diffusion through the PEG coating, or by different time scales between various experimental techniques. High-speed photography of the efflorescence process allowed the development of the AS crystallization fronts within the particles to be monitored with millisecond time resolution. The nucleation sites were inferred from the initial crystal growth sites. Analysis of the probability distribution of initial sites of 31 and 19 efflorescence events for pure AS and 1:1 (by dry weight) PEG-400/AS particles, respectively, showed that the particle volume can be excluded as the preferred nucleation site in the case of pure AS particles. For aqueous 1:1 (by dry weight) PEG-400/AS particles preferential AS nucleation in the PEG phase and at the PEG/AS/substrate contact line can be excluded. On the basis of this probability analysis of efflorescence events together with the AS ERH values of pure aqueous AS and aqueous PEG-400/AS particles aforementioned, we suggest that in pure aqueous AS particles nucleation starts at the surface of the particles and attribute the lower ERH values observed for aqueous PEG-400/AS particles to the suppression of the surface-induced nucleation process. Our results suggest that surface-induced nucleation is likely to also occur during the efflorescence of atmospheric AS aerosol particles, possibly constituting the dominating nucleation pathway.

Arsenic removal from aqueous solutions using Fe3O4-HBC composite: effect of calcination on adsorbents performance.

PubMed

Baig, Shams Ali; Sheng, TianTian; Sun, Chen; Xue, XiaoQin; Tan, LiSha; Xu, XinHua

2014-01-01

The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C) and environment (air and nitrogen) were investigated for the adsorptive removal of As(V) and As(III) from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4) via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH) was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2)>Fe3O4-HBC (uncalcined)>Fe3O4-HBC-400°C(N2)>Fe3O4-HBC-400°C(air)>Fe3O4-HBC-1000°C(air) and the maximum As(V) and As(III) adsorption capacities were found to be about 3.35 mg g(-1) and 3.07 mg g(-1), respectively. The adsorption of As(V) and As(III) remained stable in a wider pH range (4-10) using Fe3O4-HBC-1000°C(N2). Additionally, adsorption data fitted well in pseudo-second-order (R2>0.99) rather than pseudo-first-order kinetics model. The adsorption of As(V) and As(III) onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher) strongly inhibited As(V) and As(III) removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water.

Arsenic Removal from Aqueous Solutions Using Fe3O4-HBC Composite: Effect of Calcination on Adsorbents Performance

PubMed Central

Baig, Shams Ali; Sheng, TianTian; Sun, Chen; Xue, XiaoQin; Tan, LiSha; Xu, XinHua

2014-01-01

The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C) and environment (air and nitrogen) were investigated for the adsorptive removal of As(V) and As(III) from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4) via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH) was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2)>Fe3O4-HBC (uncalcined)>Fe3O4-HBC-400°C(N2)>Fe3O4-HBC-400°C(air)>Fe3O4-HBC-1000°C(air) and the maximum As(V) and As(III) adsorption capacities were found to be about 3.35 mg g−1 and 3.07 mg g−1, respectively. The adsorption of As(V) and As(III) remained stable in a wider pH range (4–10) using Fe3O4-HBC-1000°C(N2). Additionally, adsorption data fitted well in pseudo-second-order (R 2>0.99) rather than pseudo-first-order kinetics model. The adsorption of As(V) and As(III) onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher) strongly inhibited As(V) and As(III) removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water. PMID:24967645

Methods for removing contaminants from algal oil

DOEpatents

Lupton, Francis Stephen

2016-09-27

Methods for removing contaminants from algal oil are provided. In an embodiment, a method comprises the steps of combining a sulfuric acid-aqueous solution that has a pH of about 1 or less with a contaminant-containing algal oil at treatment conditions effective to form an effluent. The effluent comprises a treated algal oil phase and contaminants in an acidic aqueous phase. The contaminants comprise metals, phosphorus, or combinations thereof. The acidic aqueous phase is removed from the effluent to form a contaminant-depleted algal oil.

Gibbs energy of the resolvation of glycylglycine and its anion in aqueous solutions of dimethylsulfoxide at 298.15 K

NASA Astrophysics Data System (ADS)

Naumov, V. V.; Isaeva, V. A.; Kuzina, E. N.; Sharnin, V. A.

2012-12-01

Gibbs energies for the transfer of glycylglycine and glycylglycinate ions from water to water-dimethylsulfoxide solvents are determined from the interface distribution of substances between immiscible phases in the composition range of 0.00 to 0.20 molar fractions of DMSO at 298.15 K. It is shown that with a rise in the concentration of nonaqueous components in solution, we observe the solvation of dipeptide and its anion, due mainly to the destabilization of the carboxyl group.

Molecular dynamics simulation study of hydrogen bonding in aqueous poly(ethylene oxide) solutions.

PubMed

Smith, G D; Bedrov, D; Borodin, O

2000-12-25

A molecular dynamics simulation study of hydrogen bonding in poly(ethylene oxide) (PEO)/water solutions was performed. PEO-water and water-water hydrogen bonding manifested complex dependence on both composition and temperature. Strong water clustering in concentrated solutions was seen. Saturation of hydrogen bonding at w(p) approximately equal to 0.5 and a dramatic decrease in PEO-water hydrogen bonding with increasing temperature, consistent with experimentally observed closed-loop phase behavior, were observed. Little tendency toward intermolecular bridging of PEO chains by water molecules was seen.

Gas-particle partitioning of atmospheric aerosols: interplay of physical state, non-ideal mixing and morphology.

PubMed

Shiraiwa, Manabu; Zuend, Andreas; Bertram, Allan K; Seinfeld, John H

2013-07-21

Atmospheric aerosols, comprising organic compounds and inorganic salts, play a key role in air quality and climate. Mounting evidence exists that these particles frequently exhibit phase separation into predominantly organic and aqueous electrolyte-rich phases. As well, the presence of amorphous semi-solid or glassy particle phases has been established. Using the canonical system of ammonium sulfate mixed with organics from the ozone oxidation of α-pinene, we illustrate theoretically the interplay of physical state, non-ideality, and particle morphology affecting aerosol mass concentration and the characteristic timescale of gas-particle mass transfer. Phase separation can significantly affect overall particle mass and chemical composition. Semi-solid or glassy phases can kinetically inhibit the partitioning of semivolatile components and hygroscopic growth, in contrast to the traditional assumption that organic compounds exist in quasi-instantaneous gas-particle equilibrium. These effects have significant implications for the interpretation of laboratory data and the development of improved atmospheric air quality and climate models.

Utilization of cross-linked chitosan/bentonite composite in the removal of methyl orange from aqueous solution.

PubMed

Huang, Ruihua; Liu, Qian; Zhang, Lujie; Yang, Bingchao

2015-01-01

A kind of biocomposite was prepared by the intercalation of chitosan in bentonite and the cross-linking reaction of chitosan with glutaraldehyde, which was referred to as cross-linked chitosan/bentonite (CCS/BT) composite. Adsorptive removal of methyl orange (MO) from aqueous solutions was investigated by batch method. The adsorption of MO onto CCS/BT composite was affected by the ratio of chitosan to BT and contact time. pH value had only a minor impact on MO adsorption in a wide pH range. Adsorption kinetics was mainly controlled by the pseudo-second-order kinetic model. The adsorption of MO onto CCS/BT composite followed the Langmuir isotherm model, and the maximum adsorption capacity of CCS/BT composite calculated by the Langmuir model was 224.8 mg/g. Experimental results indicated that this adsorbent had a potential for the removal of MO from aqueous solutions.

SEPARATION OF HAFNIUM FROM ZIRCONIUM

DOEpatents

Overholser, L.B.; Barton, C.J. Sr.; Ramsey, J.W.

1960-05-31

The separation of hafnium impurities from zirconium can be accomplished by means of organic solvent extraction. The hafnium-containing zirconium feed material is dissolved in an aqueous chloride solution and the resulting solution is contacted with an organic hexone phase, with at least one of the phases containing thiocyanate. The hafnium is extracted into the organic phase while zirconium remains in the aqueous phase. Further recovery of zirconium is effected by stripping the onganic phase with a hydrochloric acid solution and commingling the resulting strip solution with the aqueous feed solution. Hexone is recovered and recycled by means of scrubbing the onganic phase with a sulfuric acid solution to remove the hafnium, and thiocyanate is recovered and recycled by means of neutralizing the effluent streams to obtain ammonium thiocyanate.

Fluid inclusions in vadose cement with consistent vapor to liquid ratios, Pleistocene Miami Limestone, southeastern Florida

USGS Publications Warehouse

Barker, C.E.; Halley, R.B.

1988-01-01

Vadose cements in the Late Pleistocene Miami Limestone contain regions with two-phase aqueous fluid inclusions that have consistent vapor to liquid (V-L) ratios. When heated, these seemingly primary inclusions homogenize to a liquid phase in a range between 75??C and 130??C (mean = 100??C) and have final melting temperatures between -0.3?? and 0.0??C. The original distribution of Th was broadened during measurements because of fluid inclusion reequilibration. The narrow range of Th in these fluid inclusions suggest unusually consistent V-L ratios. They occur with small, obscure, single phase liquid-filled inclusions, which infer a low temperature origin (less than 60??C), and contradict the higher temperature origin implied by the two phase inclusions. The diagenetic environment producing these seemingly primary fluid inclusions can be inferred from the origin of the host calcite enclosing them. The ??18O composition of these cements (-4 to-5.5%., PDB) and the fresh water in the fluid inclusions are consistent with precipitation from low-temperature meteoric water. The carbon-isotope composition of the vadose cements that contain only rare two-phase fluid inclusions are comparable to the host rock matrix (??13C between 0 and +4%., PDB). Cements that contain common two-phase fluid-inclusions have a distinctly lighter carbon isotopic composition of -3 to -5%.. The carbon isotope composition of cements that contain common two-phase inclusions are about 6%. lighter than those of other vadose cements; models of early meteoric diagenesis indicate that this is the result of precipitation from water that has been influenced by soil gas CO2. Our hypothesis is that the primary fluid inclusions, those with consistent V-L ratios and the single-phase liquid inclusions, form at near-surface temperature (25??C) and pressure when consistent proportions of soil gas and meteoric water percolating through the vadose zone are trapped within elongate vacuoles. This study corroborates that Th measurements on two phase inclusions in vadose cements can be misleading evidence of thermal diagenesis, even if the measurements are well grouped. ?? 1988.

A COMPOSITE HOLLOW FIBER MEMBRANE-BASED PERVAPORATION PROCESS FOR SEPARATION OF VOCS FROM AQUEOUS SURFACTANT SOLUTIONS. (R825511C027)

EPA Science Inventory

The separation and recovery of VOCs from surfactant-containing aqueous solutions by a composite hollow fiber membrane-based pervaporation process has been studied. The process employed hydrophobic microporous polypropylene hollow fibers having a thin plasma polymerized silicon...

Zircon solubility and of Zr species in subduction zone fluids

NASA Astrophysics Data System (ADS)

Wilke, M.; Schmidt, C.; Rickers, K.; Pascarelli, S.; Manning, C. E.; Stechern, A.

2009-12-01

The geochemical signature of igneous rocks at convergent plate margins is thought to result from complex melt formation processes involving aqueous solutions derived from dehydration of the subducted slab. In these processes, the depletion of high-field-strength elements (HFSE) may be controlled by the presence of accessory phases such as zircon and rutile, which can strongly fractionate these elements; however, the stability and solubility of these phases depends strongly on the fluid composition, including concentration and stoichiometry of Na-Al silicate components. Here we present new data on the influence of the fluid composition on zircon solubility as well as data on the Zr complexation in these fluids at P&T. Experiments were conducted using a modified hydrothermal diamond-anvil cell (HDAC). Zr contents at P&T were determined using SR-µXRF spectra. Zr K-edge X-ray Absorption Fine Structure (XAFS) spectra were acquired to investigate the Zr complexation in-situ at P&T. A grain of synthetic crystalline zircon was equilibrated with an aqueous fluid containing Na2Si2O5 or Na2Si2O5 + Al2O3 components. XAFS and SR-µXRF spectra were taken at the dispersive beamline ID24 of the ESRF, Grenoble, France. Some additional SR-µXRF spectra were taken at HASYLAB, Hamburg, beamline L. The observed Zr concentrations in fluids containing 7-33 wt% Na2Si2O5 and variable Al contents were between 75 and 720 ppm at 500 to 750°C and ~300 MPa to ~700 MPa. These values match expected solubilities calculated from linear interpolation of the maximum solubility in pure H2O (from the detection limit) and the solubility in the most alkaline high-silica melts reported by Ellison and Hess (1986, CMP, 94, 343). The high Zr solubility in sodium silicate-bearing solutions signifies that aqueous fluids with alkali silicates offer an efficient mechanism for HFSE transport. This can be explained by complexation of HFSE with Si, Na, and perhaps also Al, via formation of polymerized solutes. The XAFS results show clear differences between spectra of Zr in an HCl solution and in H2O-Na2Si2O5 (±Al2O3) aqueous fluid, implying considerable differences in Zr complexation. The latter spectra display similarities to spectra of Zr in Na2Si2O5 glass. This may indicate a similar structural environment for the two examined states, and thus point to Zr in (alumino)-silicate-based polymeric units in the aqueous solutions.

[Determination of sennosides and degraded products in the process of sennoside metabolism by HPLC].

PubMed

Sun, Yan; Li, Xuetuo; Yu, Xingju

2004-01-01

A method for the separation and determination of sennosides A and B and the main composition (sennidins A and B) in degraded products of sennosides by linear gradient high performance liquid chromatography has been developed. Separation conditions were as follows: column, a Spherisorb C18 column (250 mm x 4.6 mm i.d., 10 microm); column temperature, 40 degrees C; detection wavelength, 360 nm; mobile phase A, 1.25% acetic acid aqueous solution; mobile phase B, methanol; linear gradient, 100% A --> (20 min) 100% B. The method is effective, quick, accurate and reproducible. The satisfactory results show that this new method has certain practical values as an approach of real-time analysis in the process of sennoside metabolism.

Rationale for two phase polymer system microgravity separation experiments

NASA Technical Reports Server (NTRS)

Brooks, D. E.; Bamberger, S. B.; Harris, J. M.; Vanalstine, J.

1984-01-01

The two-phase systems that result when aqueous solutions of dextran and poly(ethylene glycol) are mixed at concentrations above a few percent are discussed. They provide useful media for the partition and isolation of macromolecules and cell subpopulations. By manipulating their composition, separations based on a variety of molecular and surface properties are achieved, including membrane hydrophobic properties, cell surface charge, and membrane antigenicity. Work on the mechanism of cell partition shows there is a randomizing, nonthermal energy present which reduces separation resolution. This stochastic energy is probably associated with hydrodynamic interactions present during separation. Because such factors should be markedly reduced in microgravity, a series of shuttle experiments to indicate approaches to increasing the resolution of the procedure are planned.

Preparative crystallization of a single chain antibody using an aqueous two-phase system.

PubMed

Huettmann, Hauke; Berkemeyer, Matthias; Buchinger, Wolfgang; Jungbauer, Alois

2014-11-01

A simultaneous crystallization and aqueous two-phase extraction of a single chain antibody was developed, demonstrating process integration. The process conditions were designed to form an aqueous two-phase system, and to favor crystallization, using sodium sulfate and PEG-2000. At sufficiently high concentrations of PEG, a second phase was generated in which the protein crystallization occurred simultaneously. The single chain antibody crystals were partitioned to the top, polyethylene glycol-rich phase. The crystal nucleation took place in the sodium sulfate-rich phase and at the phase boundary, whereas crystal growth was progressing mainly in the polyethylene glycol-rich phase. The crystals in the polyethylene glycol-rich phase grew to a size of >50 µm. Additionally, polyethylene glycol acted as an anti-solvent, thus, it influenced the crystallization yield. A phase diagram with an undersaturation zone, crystallization area, and amorphous precipitation zone was established. Only small differences in polyethylene glycol concentration caused significant shifts of the crystallization yield. An increase of the polyethylene glycol content from 2% (w/v) to 4% (w/v) increased the yield from approximately 63-87%, respectively. Our results show that crystallization in aqueous two-phase systems is an opportunity to foster process integration. © 2014 Wiley Periodicals, Inc.

Corrosion of low alloy steel containing 0.5% chromium in supercritical CO2-saturated brine and water-saturated supercritical CO2 environments

NASA Astrophysics Data System (ADS)

Wei, Liang; Gao, Kewei; Li, Qian

2018-05-01

The corrosion behavior of P110 low-Cr alloy steel in supercritical CO2-saturated brine (aqueous phase) and water-saturated supercritical CO2 (SC CO2 phase) was investigated. The results show that P110 steel primarily suffered general corrosion in the aqueous phase, while severe localized corrosion occurred in the SC CO2 phase. The formation of corrosion product scale on P110 steel in the aqueous phase divided into three stages: formation of the initial corrosion layer containing amorphous Cr(OH)3, FeCO3 and a small amount of Fe3C; transformation of initial corrosion layer to mixed layer, which consisted of FeCO3 and a small amount of Cr(OH)3 and Fe3C; growth and dissolution of the mixed layer. Finally, only a single mixed layer covered on the steel in the aqueous phase. However, the scale formed in SC CO2 phase consisted of two layers: the inner mixed layer and the dense outer FeCO3 crystalline layer.

Removal of xylenol orange from its aqueous solution using SDS self-microemulsifying systems: optimization by Box-Behnken statistical design.

PubMed

Shakeel, Faiyaz; Haq, Nazrul; Alanazi, Fars K; Alsarra, Ibrahim A

2014-04-01

The aim of present study was to develop and evaluate sodium dodecyl sulfate (SDS) self-microemulsifying systems (SMES) for the removal of an anionic dye xylenol orange (XO) from its bulk aqueous media via liquid-liquid adsorption. The composition of SDS SMES was optimized by Box-Behnken statistical design for the maximum removal of XO from its aqueous solution. Various SDS formulations were prepared by spontaneous emulsification method and characterized for thermodynamic stability, self-microemulsification efficiency, droplet size, and viscosity. Adsorption studies were conducted at 8, 16, and 24 h by mixing small amounts of SDS formulations with relatively large amounts of bulk aqueous solution of XO. Droplet size and viscosity of SDS formulations were significantly influenced by oil phase concentration (triacetin), while surfactant concentration had little impact on droplet size and viscosity. However, the percentage of removal of XO was influenced by triacetin concentration, surfactant concentration, and adsorption time. Based on lowest droplet size (35.97 nm), lowest viscosity (29.62 cp), and highest percentage of removal efficiency (89.77 %), formulation F14, containing 2 % w/w of triacetin and 40 % w/w of surfactant mixture (20 % w/w of SDS and 20 % w/w of polyethylene glycol 400), was selected as an optimized formulation for the removal of XO from its bulk aqueous media after 16 h. These results indicated that SDS SMES could be suitable alternates of solid-liquid adsorption for the removal of toxic dyes such as XO from its aqueous solution through liquid-liquid adsorption.

Producing Zirconium Diboride Components with Complex, Near-Net Shape Geometries by Aqueous Room-Temperature Injection Molding

NASA Technical Reports Server (NTRS)

Wiesner, Valerie L.; Youngblood, Jeffrey; Trice, Rodney

2014-01-01

Room-temperature injection molding is proposed as a novel, low-cost and more energy efficient manufacturing process capable of forming complex-shaped zirconium diboride (ZrB2) parts. This innovative processing method utilized aqueous suspensions with high powder loading and a minimal amount (5 vol.) of water-soluble polyvinylpyrrolidone (PVP), which was used as a viscosity modifier. Rheological characterization was performed to evaluate the room-temperature flow properties of ZrB2-PVP suspensions. ZrB2 specimens were fabricated with high green body strength and were machinable prior to binder removal despite their low polymer content. After binder burnout and pressureless sintering, the bulk density and microstructure of specimens were characterized using Archimedes technique and scanning electron microscopy. X-Ray Diffraction was used to determine the phase compositions present in sintered specimens. Ultimate strength of sintered specimens will be determined using ASTM C1323-10 compressive C-ring test.

Nanoparticle monolayers under stress: mechanically forced desorption from a fluid-fluid interface

NASA Astrophysics Data System (ADS)

Garbin, Valeria; Crocker, John C.; Stebe, Kathleen J.

2011-11-01

Nanoparticle-laden interfaces are studied for applications to materials with tunable electronic and optical properties, as emulsion stabilizers, and in catalysis. The mechanical response of nanoparticle monolayers under applied stress is of emerging interest since it impacts the success of these applications. Here we focus on the response of nanoparticle-laden interfaces to compression. A monolayer of nanoparticles is allowed to spontaneously form by adsorption from an aqueous suspension onto a pendant drop of oil. The effective surface pressure Π of the composite interface is monitored by pendant drop tensiometry. As the drop is compressed, the nanoparticles are mechanically forced out of the interface into the aqueous phase. A new optical method is developed to measure the nanoparticle area density in situ. We show that desorption occurs at a coverage that corresponds to close packing of the ligand-capped particles, suggesting that ligand-induced repulsion plays a crucial role in the desorption process.

Solubility of methanol in low-temperature aqueous sulfuric acid and implications for atmospheric particle composition

NASA Technical Reports Server (NTRS)

Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

Using traditional Knudsen cell techniques, we find well-behaved Henry's law uptake of methanol in aqueous 45 - 70 wt% H2SO4 solutions at temperatures between 197 and 231 K. Solubility of methanol increases with decreasing temperature and increasing acidity, with an effective Henry's law coefficient ranging from 10(exp 5) - 10(exp 8) M/atm. Equilibrium uptake of methanol into sulfuric acid aerosol particles in the upper troposphere and lower stratosphere will not appreciably alter gas-phase concentrations of methanol. The observed room temperature reaction between methanol and sulfuric acid is too slow to provide a sink for gaseous methanol at the temperatures of the upper troposphere and lower stratosphere. It is also too slow to produce sufficient quantities of soluble reaction products to explain the large amount of unidentified organic material seen in particles of the upper troposphere.

Theoretical Investigation of the Structural Stabilities of Ceria Surfaces and Supported Metal Nanocluster in Vapor and Aqueous Phases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Zhibo; Liu, Ning; Chen, Biaohua

Understanding the structural stability and dynamics at the interface between the solid metal oxide and aqueous phase is significant in a variety of industrial applications including heterogeneous catalysis and environmental remediation. In the present work, the stabilities of three low-index ceria (CeO2) surfaces, i.e., (111), (110) and (100) in vapor and aqueous phases were studied using ab initio molecular dynamics simulations and density functional theory (DFT) calculations. Gibbs surface free energies as a function of temperature, water partial pressure, and water coverages were calculated using DFT based atomistic thermodynamic approach. On the basis of surface free energies, the morphology andmore » exposed surface structures of the CeO2 nanoparticle were predicted using Wulff construction principle. It is found that the partially hydroxylated (111) and (100) are two major surface structures of CeO2 nanoparticles in vapor phase at ambient temperature (300 K). As the temperature increases, the fully dehydrated (111) surface gradually becomes the most dominant surface structure. While in aqueous phase, the exposed surface of the CeO2 nanoparticle is dominated by the hydroxylated (110) structure at 393 K. Finally, the morphology and stability of a cuboctahedron Pt13 nanocluster supported on CeO2 surfaces in both gas and aqueous phases were investigated. In gas phase, the supported Pt13 nanocluster has the tendency to wetting the CeO2 surface due to the strong metal-support interaction. The calculated interaction energies suggest the CeO2(110) surface provides the best stability for the Pt13 nanocluster. The CeO2 supported Pt13 nanoclusters are oxidized. Compared to the gas phase, the morphology of the CeO2 supported Pt13 nanocluster is less distorted due to the solvation effect provided by surrounding water molecules in aqueous phase. More electrons are transferred from the Pt13 nanocluster to the CeO2 support, implying the supported Pt13 nanocluster is further oxidized in aqueous phase.« less

A novel composite material based on antimony(III) oxide and amorphous silica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zemnukhova, Ludmila A.; Panasenko, Alexander E., E-mail: panasenko@ich.dvo.ru

2013-05-01

The composite material nSb₂O₃·mSiO₂·xH₂O was prepared by hydrolysis of SbCl₃ and Na₂SiO₃ in an aqueous medium. It has been shown that the composition of the material is influenced by the ratio of the initial components and the acidity of the reaction medium. The morphology of the material particles and its specific surface area have been determined. The thermal and optic properties were also investigated. - Graphical abstract: Novel composite material containing amorphous silica and crystal antimony(III) oxide has been synthesized by hydrolysis of SbCl₃ and Na₂SiO₃ in an aqueous medium. Highlights: • The composite material nSb₂O₃·mSiO₂·xH₂O was prepared in anmore » aqueous medium. • The composition of the material is controllable by a synthesis conditions. • The morphology of the material and its optic properties have been determined.« less

Vibrational Studies of Saccharide-Induced Lipid Film Reorganization at Aqueous/Air Interfaces

DOE PAGES

Link, Katie A.; Hsieh, Chia -Yun; Tuladhar, Aashish; ...

2018-02-09

Vibrational sum frequency generation (VSFG) and surface tension experiments were used to examine the effects of aqueous phase soluble saccharides on the structure and organization of insoluble lipid monolayers adsorbed to aqueous-air interfaces. Changes in dipalmitoylphosphocholine (DPPC) chain structure as a function of aqueous phase saccharide concentration and pH are reported. Complementary differential scanning calorimetry (DSC) measurements performed on solutions containing soluble saccharides and DPPC vesicles measured the effects of the saccharides on the lipid membrane phase behavior. Here, data show that the saccharides glucosamine and glucuronic acid induce a higher degree of organization in compressed DPPC monolayers regardless ofmore » the saccharide’s charge.« less

Vibrational Studies of Saccharide-Induced Lipid Film Reorganization at Aqueous/Air Interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Link, Katie A.; Hsieh, Chia -Yun; Tuladhar, Aashish

Vibrational sum frequency generation (VSFG) and surface tension experiments were used to examine the effects of aqueous phase soluble saccharides on the structure and organization of insoluble lipid monolayers adsorbed to aqueous-air interfaces. Changes in dipalmitoylphosphocholine (DPPC) chain structure as a function of aqueous phase saccharide concentration and pH are reported. Complementary differential scanning calorimetry (DSC) measurements performed on solutions containing soluble saccharides and DPPC vesicles measured the effects of the saccharides on the lipid membrane phase behavior. Here, data show that the saccharides glucosamine and glucuronic acid induce a higher degree of organization in compressed DPPC monolayers regardless ofmore » the saccharide’s charge.« less

Traditional Portland cement and MgO-based cement: a promising combination?

NASA Astrophysics Data System (ADS)

Tonelli, Monica; Martini, Francesca; Calucci, Lucia; Geppi, Marco; Borsacchi, Silvia; Ridi, Francesca

2017-06-01

MgO/SiO2 cements are materials potentially very useful for radioactive waste disposal, but knowledge about their physico-chemical properties is still lacking. In this paper we investigated the hydration kinetics of cementitious formulations prepared by mixing MgO/SiO2 and Portland cement in different proportions and the structural properties of the hydrated phases formed in the first month of hydration. In particular, the hydration kinetics was investigated by measuring the free water index on pastes by means of differential scanning calorimetry, while the structural characterization was carried out by combining thermal (DTA), diffractometric (XRD), and spectroscopic (FTIR, 29Si solid state NMR) techniques. It was found that calcium silicate hydrate (C-S-H) and magnesium silicate hydrate (M-S-H) gels mainly form as separate phases, their relative amount and structural characteristics depending on the composition of the hydrated mixture. Moreover, the composition of the mixtures strongly affects the kinetics of hydration and the pH of the aqueous phase in contact with the cementitious materials. The results here reported show that suitable mixtures of Portland cement and MgO/SiO2 could be used to modify the properties of hydrated phases with potential application in the storage of nuclear waste in clayey disposal.

Calorimetric Determination of Thermodynamic Stability of MAX and MXene Phases

DOE PAGES

Sharma, Geetu; Naguib, Michael; Feng, Dawei; ...

2016-11-19

MXenes are layered two dimensional materials with exciting properties useful to a wide range of energy applications. They are derived from ceramics (MAX phases) by leaching and their properties reflect their resulting complex compositions which include intercalating cations and anions and water. Their thermodynamic stability is likely linked to these functional groups but has not yet been addressed by quantitative experimental measurements. We report enthalpies of formation from the elements at 25 °C measured using high temperature oxide melt solution calorimetry for a layered Ti-Al-C MAX phase, and the corresponding Ti-C based MXene. The thermodynamic stability of the Ti 3Cmore » 2T x MXene (Tx stands for anionic surface moieties, and intercalated cations) was assessed by calculating the enthalpy of reaction of the MAX phase (ideal composition Ti 3AlC 2) to form MXene, The very exothermic enthalpy of reaction confirms the stability of MXene in an aqueous environment. The surface terminations (O, OH and F) and cations (Li) chemisorbed on the surface and intercalated in the interlayers play a major role in the thermodynamic stabilization of MXene. These findings help to understand and potentially improve properties and performance by characterizing the energetics of species binding to MXene surfaces during synthesis and in energy storage, water desalination and other applications.« less

Modeling radium and radon transport through soil and vegetation

USGS Publications Warehouse

Kozak, J.A.; Reeves, H.W.; Lewis, B.A.

2003-01-01

A one-dimensional flow and transport model was developed to describe the movement of two fluid phases, gas and water, within a porous medium and the transport of 226Ra and 222Rn within and between these two phases. Included in this model is the vegetative uptake of water and aqueous 226Ra and 222Rn that can be extracted from the soil via the transpiration stream. The mathematical model is formulated through a set of phase balance equations and a set of species balance equations. Mass exchange, sink terms and the dependence of physical properties upon phase composition couple the two sets of equations. Numerical solution of each set, with iteration between the sets, is carried out leading to a set-iterative compositional model. The Petrov-Galerkin finite element approach is used to allow for upstream weighting if required for a given simulation. Mass lumping improves solution convergence and stability behavior. The resulting numerical model was applied to four problems and was found to produce accurate, mass conservative solutions when compared to published experimental and numerical results and theoretical column experiments. Preliminary results suggest that the model can be used as an investigative tool to determine the feasibility of phytoremediating radium and radon-contaminated soil. ?? 2003 Elsevier Science B.V. All rights reserved.

Solid/liquid phase diagram of the ammonium sulfate/glutaric acid/water system.

PubMed

Beyer, Keith D; Pearson, Christian S; Henningfield, Drew S

2013-05-02

We have studied the low temperature phase diagram and water activities of the ammonium sulfate/glutaric acid/water system using differential scanning calorimetry, infrared spectroscopy of thin films, and a new technique: differential scanning calorimetry-video microscopy. Using these techniques, we have determined that there is a temperature-dependent kinetic effect to the dissolution of glutaric acid in aqueous solution. We have mapped the solid/liquid ternary phase diagram, determined the water activities based on the freezing point depression, and determined the ice/glutaric acid phase boundary as well as the ternary eutectic composition and temperature. We have also modified our glutaric acid/water binary phase diagram previously published based on these new results. We compare our results for the ternary system to the predictions of the Extended AIM Aerosol Thermodynamics Model (E-AIM), and find good agreement for the ice melting points in the ice primary phase field of this system; however, significant differences were found with respect to phase boundaries, concentration and temperature of the ternary eutectic, and glutaric acid dissolution.

Chemical Thermodynamics of Aqueous Atmospheric Aerosols: Modeling and Microfluidic Measurements

NASA Astrophysics Data System (ADS)

Nandy, L.; Dutcher, C. S.

2017-12-01

Accurate predictions of gas-liquid-solid equilibrium phase partitioning of atmospheric aerosols by thermodynamic modeling and measurements is critical for determining particle composition and internal structure at conditions relevant to the atmosphere. Organic acids that originate from biomass burning, and direct biogenic emission make up a significant fraction of the organic mass in atmospheric aerosol particles. In addition, inorganic compounds like ammonium sulfate and sea salt also exist in atmospheric aerosols, that results in a mixture of single, double or triple charged ions, and non-dissociated and partially dissociated organic acids. Statistical mechanics based on a multilayer adsorption isotherm model can be applied to these complex aqueous environments for predictions of thermodynamic properties. In this work, thermodynamic analytic predictive models are developed for multicomponent aqueous solutions (consisting of partially dissociating organic and inorganic acids, fully dissociating symmetric and asymmetric electrolytes, and neutral organic compounds) over the entire relative humidity range, that represent a significant advancement towards a fully predictive model. The model is also developed at varied temperatures for electrolytes and organic compounds the data for which are available at different temperatures. In addition to the modeling approach, water loss of multicomponent aerosol particles is measured by microfluidic experiments to parameterize and validate the model. In the experimental microfluidic measurements, atmospheric aerosol droplet chemical mimics (organic acids and secondary organic aerosol (SOA) samples) are generated in microfluidic channels and stored and imaged in passive traps until dehydration to study the influence of relative humidity and water loss on phase behavior.

Influence of propylene glycol on aqueous silica dispersions and particle-stabilized emulsions.

PubMed

Binks, Bernard P; Fletcher, Paul D I; Thompson, Michael A; Elliott, Russell P

2013-05-14

We have studied the influence of adding propylene glycol to both aqueous dispersions of fumed silica nanoparticles and emulsions of paraffin liquid and water stabilized by the same particles. In the absence of oil, aerating mixtures of aqueous propylene glycol and particles yields either stable dispersions, aqueous foams, climbing particle films, or liquid marbles depending on the glycol content and particle hydrophobicity. The presence of glycol in water promotes particles to behave as if they are more hydrophilic. Calculations of their contact angle at the air-aqueous propylene glycol surface are in agreement with these findings. In the presence of oil, particle-stabilized emulsions invert from water-in-oil to oil-in-water upon increasing either the inherent hydrophilicity of the particles or the glycol content in the aqueous phase. Stable multiple emulsions occur around phase inversion in systems of low glycol content, and completely stable, waterless oil-in-propylene glycol emulsions can also be prepared. Accounting for the surface energies at the respective interfaces allows estimation of the contact angle at the oil-polar phase interface; reasonable agreement between measured and calculated phase inversion conditions is found assuming no glycol adsorption on particle surfaces.

Cloud Point and Liquid-Liquid Equilibrium Behavior of Thermosensitive Polymer L61 and Salt Aqueous Two-Phase System.

PubMed

Rao, Wenwei; Wang, Yun; Han, Juan; Wang, Lei; Chen, Tong; Liu, Yan; Ni, Liang

2015-06-25

The cloud point of thermosensitive triblock polymer L61, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), was determined in the presence of various electrolytes (K2HPO4, (NH4)3C6H5O7, and K3C6H5O7). The cloud point of L61 was lowered by the addition of electrolytes, and the cloud point of L61 decreased linearly with increasing electrolyte concentration. The efficacy of electrolytes on reducing cloud point followed the order: K3C6H5O7 > (NH4)3C6H5O7 > K2HPO4. With the increase in salt concentration, aqueous two-phase systems exhibited a phase inversion. In addition, increasing the temperature reduced the concentration of salt needed that could promote phase inversion. The phase diagrams and liquid-liquid equilibrium data of the L61-K2HPO4/(NH4)3C6H5O7/K3C6H5O7 aqueous two-phase systems (before the phase inversion but also after phase inversion) were determined at T = (25, 30, and 35) °C. Phase diagrams of aqueous two-phase systems were fitted to a four-parameter empirical nonlinear expression. Moreover, the slopes of the tie-lines and the area of two-phase region in the diagram have a tendency to rise with increasing temperature. The capacity of different salts to induce aqueous two-phase system formation was the same order as the ability of salts to reduce the cloud point.

Phase relations among K-feldspar, muscovite and H2O at 1.0 GPa and 800°C: Implications for metasediment dissolution and melting at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Fineman, D.; Manning, C. E.

2016-12-01

Melting and solubility of K-feldspar (ksp) and muscovite (mus) were investigated in the system KSi3O6.5 -Al2O3 - H2O at 1.0 GPa and 800 °C with rapid-quench piston-cylinder techniques. Equilibrium assemblages of ksp, mus, silicate liquid (L) and aqueous fluid (V) were deduced from optical and scanning electron microscopy. Quenched silicate liquids and aqueous fluids were distinguished using the methodology of Burnham and Jahns (1962, Am J Sci, 260, 721) and Makhluf et al. (2016, CMP, in press). Experiments on a range of bulk compositions constrain the locations of the V, ksp+V, ms+V, and ksp+L+V fields. This allowed geometrical constraints to be placed on additional phase boundaries in the ternary system. The results show that ksp dissolves incongruently in H2O, with residual liquid or ms depending on the fluid-rock ratio. In contrast, ms dissolves congruently in H2O and KSi3O6.5 -H2O solutions with up to 25 wt% KSi3O6.5. Results indicate that stable hydrous liquid at these conditions has an Al content intermediate between ksp and ms. There is no stable liquid along the ksp-H2O join, consistent with results of Goldsmith and Peterson (1990, Am Min, 75, 1362). All data are consistent with the stability of a supercritical fluid on the KAlSi3O8 -H2O join, with 5-10 wt% dissolved Al2O3. Compositional constraints imply that the liquid phase contains 25 wt% H2O and coexists with a V phase containing 25 wt% dissolved solutes. This in turn implies critical mixing of the fluid phases at higher temperature, which is similar to the systems NaAlSi3O8-H2O and simple granite-H2O. Our results help constrain the conditions of production of supercritical granitic-H2O fluids systems in deep crustal and subduction zone settings.

Aqueous two-phase partition applied to the isolation of plasma membranes and Golgi apparatus from cultured mammalian cells.

PubMed

Morré, D M; Morre, D J

2000-06-23

Partitioning in dextran-poly(ethylene)glycol (PEG) aqueous-aqueous phase systems represents a mature technology with many applications to separations of cells and to the preparation of membranes from mammalian cells. Most applications to membrane isolation and purification have focused on plasma membranes, plasma membrane domains and separation of right side-out and inside-out plasma membrane vesicles. The method exploits a combination of membrane properties, including charge and hydrophobicity. Purification is based upon differential distributions of the constituents in a sample between the two principal compartments of the two phases (upper and lower) and at the interface. The order of affinity of animal cell membranes for the upper phase is: endoplasmic reticulum

Aqueous two-phase partition applied to the isolation of plasma membranes and Golgi apparatus from cultured mammalian cells

NASA Technical Reports Server (NTRS)

Morre, D. M.; Morre, D. J.

2000-01-01

Partitioning in dextran-poly(ethylene)glycol (PEG) aqueous-aqueous phase systems represents a mature technology with many applications to separations of cells and to the preparation of membranes from mammalian cells. Most applications to membrane isolation and purification have focused on plasma membranes, plasma membrane domains and separation of right side-out and inside-out plasma membrane vesicles. The method exploits a combination of membrane properties, including charge and hydrophobicity. Purification is based upon differential distributions of the constituents in a sample between the two principal compartments of the two phases (upper and lower) and at the interface. The order of affinity of animal cell membranes for the upper phase is: endoplasmic reticulum

Expanded separation technique for chlorophyll metabolites in Oriental tobacco leaf using non aqueous reversed phase chromatography.

PubMed

Ishida, Naoyuki

2011-08-26

An improved separation method for chlorophyll metabolites in Oriental tobacco leaf was developed. While Oriental leaf still gives the green color even after the curing process, little attention has been paid to the detailed composition of the remaining green pigments. This study aimed to identify the green pigments using non aqueous reversed phase chromatography (NARPC). To this end, liquid chromatograph (LC) equipped with a photo diode array detector (DAD) and an atmospheric pressure chemical ionization/mass spectrometer (APCI/MSD) was selected, because it is useful for detecting low polar non-volatile compounds giving green color such as pheophytin a. Identification was based on the wavelength spectrum, mass spectrum and retention time, comparing the analytes in Oriental leaf with the commercially available and synthesized components. Consequently, several chlorophyll metabolites such as hydroxypheophytin a, solanesyl pheophorbide a and solanesyl hydroxypheophorbide a were newly identified, in addition to typical green pigments such as chlorophyll a and pheophytin a. Chlorophyll metabolites bound to solanesol were considered the tobacco specific components. NARPC expanded the number of detectable low polar chlorophyll metabolites in Oriental tobacco leaf. Copyright © 2011 Elsevier B.V. All rights reserved.

Translating Thermal Response of Triblock Copolymer Assemblies in Dilute Solution to Macroscopic Gelation and Phase Separation

DOE PAGES

Sun, Zhe; Tian, Ye; Hom, Wendy L.; ...

2016-12-28

The thermal response of semi-dilute solutions (5 w/w%) of two amphiphilic thermoresponsive poly(ethylene oxide)-b-poly(N,N-diethylacrylamide)-b-poly(N,N-dibutylacrylamide) (PEO 45-PDEAm x-PDBAm 12) triblock copolymers, which differ only in the size of the central responsive block, in water was examined in this paper. Aqueous PEO45-PDEAm41-PDBAm12 solutions, which undergo a thermally induced sphere-to-worm transition in dilute solution, were found to reversibly form soft (G'≈10 Pa) free-standing physical gels after 10 min at 55 °C. PEO 45-PDEAm 89-PDBAm 12 copolymer solutions, which undergo a thermally induced transition from spheres to large compound micelles (LCM) in dilute solution, underwent phase separation after heating at 55 °C for 10more » min owing to sedimentation of LCMs. The reversibility of LCM formation was investigated as a non-specific method for removal of a water-soluble dye from aqueous solution. Finally, the composition and size of the central responsive block in these polymers dictate the microscopic and macroscopic response of the polymer solutions as well as the rates of transition between assemblies.« less

Comparative study of the synthesis of layered transition metal molybdates

NASA Astrophysics Data System (ADS)

Mitchell, S.; Gómez-Avilés, A.; Gardner, C.; Jones, W.

2010-01-01

Mixed metal oxides (MMOs) prepared by the mild thermal decomposition of layered double hydroxides (LDHs) differ in their reactivity on exposure to aqueous molybdate containing solutions. In this study, we investigate the reactivity of some T-Al containing MMOs ( T=Co, Ni, Cu or Zn) towards the formation of layered transition metal molybdates (LTMs) possessing the general formula AT2(OH)(MoO 4) 2·H 2O, where A=NH 4+, Na + or K +. The phase selectivity of the reaction was studied with respect to the source of molybdate, the ratio of T to Mo and the reaction pH. LTMs were obtained on reaction of Cu-Al and Zn-Al containing MMOs with aqueous solutions of ammonium heptamolybdate. Rehydration of these oxides in the presence of sodium or potassium molybdate yielded a rehydrated LDH phase as the only crystalline product. The LTM products obtained by the rehydration of MMO precursors were compared with LTMs prepared by direct precipitation from the metal salts in order to study the influence of preparative route on their chemical and physical properties. Differences were noted in the composition, morphology and thermal properties of the resulting products.

Scale-up of recombinant cutinase recovery by whole broth extraction with PEG-phosphate aqueous two-phase.

PubMed

Costa, M J; Cunha, M T; Cabral, J M; Aires-Barros, M R

2000-01-01

A whole broth extraction using an aqueous two-phase system (ATPS) composed by 5% (w/w) PEG 3350 and 15% (w/w) phosphate was used for the scale-up extraction and isolation of a recombinant Fusarium solani pisi cutinase, an extracellular mutant enzyme expressed in Saccharomyces cerevisiae, containing a fusion peptide (WP)4. The experiments were carried out at three different scales (10 ml, 1 l and 30 l). Mixing time and stirrer speed were evaluated at lab scale (1 l) with two different system compositions. Stirrer speed between 400 and 800 rpm and mixing time between 2 and 5 min led to the highest recoveries of cutinase. In all cases, inclusive of pilot scale (30 l), the equilibrium was reached after a few minutes. The performance of ATPS was reproducible within the scale range of 0.010-30 l and provided a standard deviation of the yield lower than 8%, leading to (i) a partition coefficient over 50, (ii) a yield over 95% and (iii) a concentration factor over 5. The fusion of the peptide (WP)4 to the cutinase protein enabled a 400 increase of the partition coefficient relative to the wild-type strain.

Hydrogels with a Memory: Dual-Responsive, Organometallic Poly(ionic liquid)s with Hysteretic Volume-Phase Transition

PubMed Central

2017-01-01

We report on the synthesis and structure–property relations of a novel, dual-responsive organometallic poly(ionic liquid) (PIL), consisting of a poly(ferrocenylsilane) backbone of alternating redox-active, silane-bridged ferrocene units and tetraalkylphosphonium sulfonate moieties in the side groups. This PIL is redox responsive due to the presence of ferrocene in the backbone and also exhibits a lower critical solution temperature (LCST)-type thermal responsive behavior. The LCST phase transition originates from the interaction between water molecules and the ionic substituents and shows a concentration-dependent, tunable transition temperature in aqueous solution. The PIL’s LCST-type transition temperature can also be influenced by varying the redox state of ferrocene in the polymer main chain. As the polymer can be readily cross-linked and is easily converted into hydrogels, it represents a new dual-responsive materials platform. Interestingly, the as-formed hydrogels display an unusual, strongly hysteretic volume-phase transition indicating useful thermal memory properties. By employing the dispersing abilities of this cationic PIL, CNT-hydrogel composites were successfully prepared. These hybrid conductive composite hydrogels showed bi-stable states and tunable resistance in heating–cooling cycles. PMID:28654756

Synthesis of TiO2 NRs - ZnO Composite for Dye Sensitized Solar Cell Photoanodes

NASA Astrophysics Data System (ADS)

Wahyuningsih, S.; Ramelan, A. H.; Hidayat, R.; Fadillah, G.; Munawaroh, H.; Saputri, L. N. M. Z.

2017-07-01

Composite of TiO2 NRs - ZnO were synthesized for DSSCs photoanode materials. TiO2 NRs was synthesized from TiO2 anatase by mechanochemical technique using ball milling process with agitation speed of 1000 rpm. While, the further hydrothermal refluxing process was conducted at 120°C under various concentration of NaOH in aqueous solution. The starting material of ZnO was prepared from ZnSO4.7H2O as a precursor. The hydrothermal treated TiO2 was added to the ZnO powder in a certain composition of 1:1, 1:2 and 2:1 (w/w), and the mixtures were then annealed at 400°C. The resulting material was characterized by X-ray diffraction (XRD), Surface area analyzer (SAA), Transmission electron microscopy (TEM), and Thermogravimetry/Differential thermal analysis (TG/DTA). The TiO2 revolution occurs from anatase phase into brookite phase. Rutile TiO2 phase was increasing when the NaOH was added at about 12 M. Nanograf of TEM showed the optimum condition for the formation of TiO2 NRs was obtained when 12 M NaOH was used. Structural transformation to 1D nanorods of TiO2 capable increase surface area up to 79 m2/g. TiO2 NRs-ZnO composite was prepared from TiO2 NRs and ZnO using comparation of TiO2 NRs: ZnO = 1:1, 1:2, dan 2:1. Anatase phase TiO2 as a single phase TiO2 was obtained in the TiO2-ZnO composite (1:1 w/w) upon heating the sample until 400°C. Difference TiO2 NRs-ZnO composite materials were investigated as good photovoltaic materials. Evaluation of the performance of DSSCs was conducted by I-V Keithley 2602A measurement indicate that photoanode built of TiO2 NRs - ZnO thin film has a higher solar cell efficiency than that of TiO2 thin film photoanode.

In situ stabilization of NAPL contaminant source-zones as a remediation technique to reduce mass discharge and flux to groundwater.

PubMed

Mateas, Douglas J; Tick, Geoffrey R; Carroll, Kenneth C

2017-09-01

Widely used flushing and in-situ destruction based remediation techniques (i.e. pump-and treat, enhanced-solubilization, and chemical oxidation/reduction) for sites contaminated by nonaqueous phase liquid (NAPL) contaminant sources have been shown to be ineffective at complete mass removal and reducing aqueous-phase contaminant of concern (COC) concentrations to levels suitable for site closure. A remediation method was developed to reduce the aqueous solubility and mass-flux of COCs within NAPL through the in-situ creation of a NAPL mixture source-zone. In contrast to remediation techniques that rely on the rapid removal of contaminant mass, this technique relies on the stabilization of difficult-to-access NAPL sources to reduce COC mass flux to groundwater. A specific amount (volume) of relatively insoluble n-hexadecane (HEXDEC) or vegetable oil (VO) was injected into a trichloroethene (TCE) contaminant source-zone through a bench-scale flow cell port (i.e. well) to form a NAPL mixture of targeted mole fraction (TCE:HEXDEC or TCE:VO). NAPL-aqueous phase batch tests were conducted prior to the flow-cell experiments to evaluate the effects of various NAPL mixture ratios on equilibrium aqueous-phase concentrations of TCE to design optimal NAPL (HEXDEC or VO) injection volumes for the flow-cell experiments. The NAPL-stabilization flow-cell experiments initiated and sustained significant reductions in COC concentration and mass flux due to a combination of both reduced relative permeability (increased NAPL-saturation) and via modification of NAPL composition (decreased TCE mole fraction). Variations in remediation performance (i.e. impacts on TCE concentration and mass flux reduction) between the different HEXDEC injection volumes were relatively minor, and therefore inconsistent with Raoult's Law predictions. This phenomenon likely resulted from non-uniform mixing of the injected HEXDEC with TCE in the source-zone. VO injection caused TCE concentrations and mass-flux to decrease more rapidly than with HEXDEC injections. This phenomenon occurred because the injected VO was observed to mix more uniformly with TCE in the source-zone due to a lower mobilization potential. The relative lower density differences (buoyancy effects) between VO and the flushing solution (water) was the primary factor contributing to the lower mobilization potential for VO. Overall, this study indicated that the delivery of HEXDEC or VO into the toxic TCE source-zone was effective in significantly reducing contaminant aqueous-phase concentration and mass-flux. However, the effectiveness of this in-situ NAPL stabilization technique depends on source delivery, uniform mixing of amendment, and that the amendment remains immobilized within and around the NAPL contaminant source. Copyright © 2017 Elsevier B.V. All rights reserved.

Solid-phase microextraction based on an agarose-chitosan-multiwalled carbon nanotube composite film combined with HPLC-UV for the determination of non-steroidal anti-inflammatory drugs in aqueous samples.

PubMed

Wan Ibrahim, Wan Nazihah; Sanagi, Mohd Marsin; Mohamad Hanapi, Nor Suhaila; Kamaruzaman, Sazlinda; Yahaya, Noorfatimah; Wan Ibrahim, Wan Aini

2018-06-07

We describe the preparation, characterization and application of a composite film adsorbent based on blended agarose-chitosan-multi-walled carbon nanotubes for the preconcentration of selected non-steroidal anti-inflammatory drugs in aqueous samples before determination by high-performance liquid chromatography with UV detection. The composite film showed high surface area (4.0258 m 2 /g) and strong hydrogen bonding between multi-walled carbon nanotubes and agarose/chitosan matrix, which prevent adsorbent deactivation and ensure long-term stability. Several parameters, namely, sample pH, addition of salt, extraction time, desorption solvent and concentration of multi-walled carbon nanotubes in the composite film were optimized using a one-factor-at-time approach. The optimum extraction conditions obtained were as follows: isopropanol as conditioning solvent, 10 mL of sample solution at pH 2, extraction time of 30 min, stirring speed of 600 rpm, 100 μL of isopropanol as desorption solvent, desorption time of 5 min under ultrasonication, and 0.4% w/v of composite film. Under optimized conditions, the calibration curved showed good linearity in the range of 1-500 ng/mL (r 2  = 0.997-0.999), good limits of detection (0.89-8.05 ng/mL) were obtained with good relative standard deviations of < 4.59% (n = 3) for the determination of naproxen, diclofenac sodium salt and mefenamic acid drugs. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Identifying precursors and aqueous organic aerosol formation pathways during the SOAS campaign

NASA Astrophysics Data System (ADS)

Sareen, Neha; Carlton, Annmarie G.; Surratt, Jason D.; Gold, Avram; Lee, Ben; Lopez-Hilfiker, Felipe D.; Mohr, Claudia; Thornton, Joel A.; Zhang, Zhenfa; Lim, Yong B.; Turpin, Barbara J.

2016-11-01

Aqueous multiphase chemistry in the atmosphere can lead to rapid transformation of organic compounds, forming highly oxidized, low-volatility organic aerosol and, in some cases, light-absorbing (brown) carbon. Because liquid water is globally abundant, this chemistry could substantially impact climate, air quality, and health. Gas-phase precursors released from biogenic and anthropogenic sources are oxidized and fragmented, forming water-soluble gases that can undergo reactions in the aqueous phase (in clouds, fogs, and wet aerosols), leading to the formation of secondary organic aerosol (SOAAQ). Recent studies have highlighted the role of certain precursors like glyoxal, methylglyoxal, glycolaldehyde, acetic acid, acetone, and epoxides in the formation of SOAAQ. The goal of this work is to identify additional precursors and products that may be atmospherically important. In this study, ambient mixtures of water-soluble gases were scrubbed from the atmosphere into water at Brent, Alabama, during the 2013 Southern Oxidant and Aerosol Study (SOAS). Hydroxyl (OH⚫) radical oxidation experiments were conducted with the aqueous mixtures collected from SOAS to better understand the formation of SOA through gas-phase followed by aqueous-phase chemistry. Total aqueous-phase organic carbon concentrations for these mixtures ranged from 92 to 179 µM-C, relevant for cloud and fog waters. Aqueous OH-reactive compounds were primarily observed as odd ions in the positive ion mode by electrospray ionization mass spectrometry (ESI-MS). Ultra high-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) spectra and tandem MS (MS-MS) fragmentation of these ions were consistent with the presence of carbonyls and tetrols. Products were observed in the negative ion mode and included pyruvate and oxalate, which were confirmed by ion chromatography. Pyruvate and oxalate have been found in the particle phase in many locations (as salts and complexes). Thus, formation of pyruvate/oxalate suggests the potential for aqueous processing of these ambient mixtures to form SOAAQ.

Transfer Kinetics at the Aqueous/Non-Aqueous Phase Liquid Interface. A Statistical Mechanic Approach

NASA Astrophysics Data System (ADS)

Doss, S. K.; Ezzedine, S.; Ezzedine, S.; Ziagos, J. P.; Hoffman, F.; Gelinas, R. J.

2001-05-01

Many modeling efforts in the literature use a first-order, linear-driving-force model to represent the chemical dissolution process at the non-aqueous/aqueous phase liquid (NAPL/APL) interface. In other words, NAPL to APL phase flux is assumed to be equal to the difference between the solubility limit and the "bulk aqueous solution" concentrations times a mass transfer coefficient. Under such assumptions, a few questions are raised: where, in relation to a region of pure NAPL, does the "bulk aqueous solution" regime begin and how does it behave? The answers are assumed to be associated with an arbitrary, predetermined boundary layer, which separates the NAPL from the surrounding solution. The mass transfer rate is considered to be, primarily, limited by diffusion of the component through the boundary layer. In fact, compositional models of interphase mass transfer usually assume that a local equilibrium is reached between phases. Representing mass flux as a rate-limiting process is equivalent to assuming diffusion through a stationary boundary layer with an instantaneous local equilibrium and linear concentration profile. Some environmental researchers have enjoyed success explaining their data using chemical engineering-based correlations. Correlations are strongly dependent on the experimental conditions employed. A universally applicable theory for NAPL dissolution in natural systems does not exist. These correlations are usually expressed in terms of the modified Sherwood number as a function of Reynolds, Peclet, and Schmidt numbers. The Sherwood number may be interpreted as the ratio between the grain size and the thickness of the Nernst stagnant film. In the present study, we show that transfer kinetics at the NAPL/APL interface under equilibrium conditions disagree with approaches based on the Nernst stagnant film concept. It is unclear whether local equilibrium assumptions used in current models are suitable for all situations.A statistical mechanic framework has been chosen to study the transfer kinetic processes at the microscale level. The rationale for our approach is based on both the activation energy of transfer of an ion and its velocity across the NAPL/APL interface. There are four major energies controlling the interfacial NAPL dissolution kinetics: (de)solvation energy, interfacial tension energy, electrostatic energy, and thermal fluctuation energy. Transfer of an ion across the NAPL/APL interface is accelerated by the viscous forces which can be described using the averaged Langevin master equation. The resulting energies and viscous forces were combined using the Boltzmann probability distribution. Asymptotic time limits of the resulting kinetics lead to instantaneous local equilibrium conditions that contradict the Nernst equilibrium equation. The NAPL/APL interface is not an ideal one: it does not conserve energy and heat. In our case the interface is treated as a thin film or slush zone that alters the thermodynamic variables. Such added zone, between the two phases, is itself a phase, and, therefore, the equilibrium does not occur between two phases but rather three. All these findings led us to develop a new non-linearly coupled flow and transport system of equations which is able to account for specific chemical dissolution processes and precludes the need for empirical mass-transfer parameters. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

PROCESS OF SEPARATING URANIUM FROM AQUEOUS SOLUTION BY SOLVENT EXTRACTION

DOEpatents

Warf, J.C.

1958-08-19

A process is described for separating uranium values from aqueous uranyl nitrate solutions. The process consists in contacting the uramium bearing solution with an organic solvent, tributyl phosphate, preferably diluted with a less viscous organic liquida whereby the uranyl nitrate is extracted into the organic solvent phase. The uranvl nitrate may be recovered from the solvent phase bv back extracting with an aqueous mediuin.

Adsorption of As(III), As(V) and Cu(II) on zirconium oxide immobilized alginate beads in aqueous phase.

PubMed

Kwon, Oh-Hun; Kim, Jong-Oh; Cho, Dong-Wan; Kumar, Rahul; Baek, Seung Han; Kurade, Mayur B; Jeon, Byong-Hun

2016-10-01

A composite adsorbent to remove arsenite [As(III)], arsenate [As(V)], and copper [Cu(II)] from aqueous phase was synthesized by immobilizing zirconium oxide on alginate beads (ZOAB). The composition (wt%) of ZOAB (Zr-34.0; O-32.7; C-21.3; Ca-1.0) was confirmed by energy dispersive X-ray (EDX) analysis. Sorption studies were conducted on single and binary sorbate systems, and the effects of contact time, initial adsorbate concentration, and pH on the adsorption performance of ZOAB (pHPZC = 4.3) were monitored. The sorption process for As(III)/As(V) and Cu(II) reached an equilibrium state within 240 h and 24 h, respectively, with maximum sorption capacities of 32.3, 28.5, and 69.9 mg g(-1), respectively. The addition of Cu(II) was favorable for As(V) sorption in contrast to As(III). In the presence of 48.6 mg L(-1) Cu(II), the sorption capacity of As(V) increased from 1.5 to 3.8 mg g(-1) after 240 h. The sorption data for As(III)/As(V) and Cu(II) conformed the Freundlich and Langmuir isotherm models, respectively. The adsorption of As(III), As(V), and Cu(II) followed pseudo second order kinetics. The effect of arsenic species on Cu(II) sorption was insignificant. The results of present study demonstrated that the synthesized sorbent could be useful for the simultaneous removal of both anionic and cationic contaminants from wastewaters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determination of Carvedilol Enantiomers in Pharmaceutical Dosages by SBSE-HPLC Based on Diastereomer Formation.

PubMed

Taraji, Maryam; Talebpour, Zahra; Adib, Nuoshin; Karimi, Shima; Haghighi, Farideh; Aboul-Enein, Hassan Y

2015-09-01

A sensitive, selective and simple method for the simultaneous determination of carvedilol enantiomers in aqueous solution has been developed using stir bar sorptive extraction (SBSE) followed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. This method is based on the reaction of carvedilol enantiomers with (-)-menthyl chloroformate (MCF) after extraction by the SBSE method to produce diastereomeric derivatives. The separation was achieved by use of a C18 analytical column and the influence of mobile phase composition on the enantioseparation of carvedilol was studied. The applicability of two sorptive phases, poly(methyl methacrylate/ethyleneglycol dimethacrylate) (PA-EG) and polydimethylsiloxane, were tested for extraction of carvedilol enantiomers from aqueous samples. The obtained results showed excellent linear dynamic ranges and precisions for each of them. The least limit of detection for (S)- and (R)-carvedilol obtained 8 and 11 µg L(-1), respectively, using the PA-EG sorptive phase. Inter- and intra-mean recoveries were also satisfactory, ranging from 98 to 103%, with coefficient of variation in the range of 1-5% at three fortified levels using a PA-EG coated stir bar. The proposed SBSE (PA-EG)-MCF derivatization-HPLC-UV method was successfully applied to enantioselective analysis of carvedilol in water and pharmaceutical dosages, confirming the application of this method. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Theoretical Treatment of Ion Transfers in Two Polarizable Interface Systems When the Analyte Has Access to Both Interfaces.

PubMed

Olmos, José Manuel; Molina, Ángela; Laborda, Eduardo; Millán-Barrios, Enrique; Ortuño, Joaquín Ángel

2018-02-06

A new theory is presented to tackle the study of transfer processes of hydrophilic ions in two polarizable interface systems when the analyte is initially present in both aqueous phases. The treatment is applied to macrointerfaces (linear diffusion) and microholes (highly convergent diffusion), obtaining analytical equations for the current response in any voltammetric technique. The novel equations predict two signals in the current-potential curves that are symmetric when the compositions of the aqueous phases are identical while asymmetries appear otherwise. The theoretical results show good agreement with the experimental behavior of the "double transfer voltammograms" reported by Dryfe et al. in cyclic voltammetry (CV) ( Anal. Chem. 2014 , 86 , 435 - 442 ) as well as with cyclic square wave voltammetry (cSWV) experiments performed in the current work. The theoretical treatment is also extended to the situation where the target ion is lipophilic and initially present in the organic phase. The theory predicts an opposite effect of the lipophilicity of the ion on the shape of the voltammograms, which is validated experimentally via both CV and cSWV. For the above two cases, simple and manageable expressions and diagnosis criteria are derived for the qualitative and quantitative study of ion lipophilicity. The ion-transfer potentials can be easily quantified from the separation between the two signals making use of explicit analytical equations.

Fabrication of polyaniline-coated halloysite nanotubes by in situ chemical polymerization as a solid-phase microextraction coating for the analysis of volatile organic compounds in aqueous solutions.

PubMed

Abolghasemi, Mir Mahdi; Arsalani, Naser; Yousefi, Vahid; Arsalani, Mahmood; Piryaei, Marzieh

2016-03-01

We have synthesized an organic-inorganic polyaniline-halloysite nanotube composite by an in situ polymerization method. This nanocomposite is immobilized on a stainless-steel wire and can be used as a fiber coating for solid-phase microextraction. It was found that our new solid-phase microextraction fiber is an excellent adsorbent for the extraction of some volatile organic compounds in aqueous samples in combination with gas chromatography and mass spectrometry. The coating can be prepared easily, is mechanically stable, and exhibits relatively high thermal stability. It is capable of extracting phenolic compounds from water samples. Following thermal desorption, the phenols were quantified by gas chromatography with mass spectrometry. The effects of extraction temperature, extraction time, sample ionic strength, stirring rate, pH, desorption temperature and desorption time were studied. Under optimal conditions, the repeatability for one fiber (n = 5), expressed as the relative standard deviation, is between 6.2 and 9.1%. The detection limits range from 0.005 to 4 ng/mL. The method offers the advantage of being simple to use, with a shorter analysis time, lower cost of equipment and higher thermal stability of the fiber in comparison to conventional methods of analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of mixing, concentration and temperature on the formation of mesostructured solutions and their role in the nucleation of DL-valine crystals.

PubMed

Jawor-Baczynska, Anna; Moore, Barry D; Sefcik, Jan

2015-01-01

We report investigations on the formation of mesostructured solutions in DL-valine-water-2-propanol mixtures, and the crystallization of DL-valine from these solutions. Mesostructured liquid phases, similar to those previously observed in aqueous solutions of glycine and DL-alanine, were observed using Dynamic Light Scattering and Brownian microscopy, in both undersaturated and supersaturated solutions below a certain transition temperature. Careful experimentation was used to demonstrate that the optically clear mesostructured liquid phase, comprising colloidal mesoscale clusters dispersed within bulk solution, is thermodynamically stable and present in equilibrium with the solid phase at saturation conditions. Solutions prepared by slow cooling contained mesoscale clusters with a narrow size distribution and a mean hydrodynamic diameter of around 200 nm. Solutions of identical composition prepared by rapid isothermal mixing of valine aqueous solutions with 2-propanol contained mesoscale clusters which were significantly larger than those observed in slowly cooled solutions. The presence of larger mesoscale clusters was found to correspond to faster nucleation. Observed induction times were strongly dependent on the rapid initial mixing step, although solutions were left undisturbed afterwards and the induction times observed were up to two orders of magnitude longer than the initial mixing period. We propose that mesoscale clusters above a certain critical size are likely to be the location of productive nucleation events.

Facile synthesis of Fe3O4/C composites for broadband microwave absorption properties

NASA Astrophysics Data System (ADS)

Liu, Xiang; Ma, Yating; Zhang, Qinfu; Zheng, Zhiming; Wang, Lai-Sen; Peng, Dong-Liang

2018-07-01

Rod-like and flower-like Fe3O4/C composites were successfully synthesized via a facile approach in aqueous phase. The morphologies, structures and static magnetic properties of as-prepared rod-like and flower-like Fe3O4/C composites were characterized thoroughly. The relative complex permittivity and permeability of Fe3O4/C/paraffin composites were recorded by a vector network analyzer (VNA) in the range of 1-18 GHz. The resonant-antiresonant electromagnetic behavior was observed simultaneously in both rod-like and flower-like Fe3O4/C composites. Moreover, the resonant-antiresonant behavior was explained using displacement current lag at the "core/shell" interface. The flower-like Fe3O4/C/paraffin composites show superior microwave absorption performance with minimum reflection loss (RL) of up to -18.73 dB at 15.37 GHz. Comparatively, the rod-like Fe3O4/C/paraffin composites have uncommon continuous trinal absorption peaks at a thickness of 2.5 mm that effectively broadens the absorption bandwidth which is from 8.0 to 13.4 GHz. Furthermore, the microwave absorption mechanism has been discussed to provide a novel design for microwave absorption materials.

PCE DNAPL degradation using ferrous iron solid mixture (ISM).

PubMed

Lee, Hong-Kyun; Do, Si-Hyun; Batchelor, Bill; Jo, Young-Hoon; Kong, Sung-Ho

2009-08-01

Ferrous iron solid mixture (ISM) containing Fe(II), Fe(III), and Cl was synthesized for degradation of tetrachloroethene (PCE) as a dense non-aqueous phase liquid (DNAPL), and an extraction procedure was developed to measure concentrations of PCE in both the aqueous and non-aqueous phases. This procedure included adding methanol along with hexane in order to achieve the high extraction efficiency, particularly when solids were present. When PCE was present as DNAPL, dechlorination of PCE was observed to decrease linearly with respect to the total PCE concentration (aqueous and non-aqueous phases) and the concentration of PCE in the aqueous phase was observed to be approximately constant. In the absence of DNAPL, the rate of PCE degradation was observed to be the first-order with respect to the concentration in the aqueous phase. A kinetic model was developed to describe these observations and it was able to fit experimental data well. Increasing the concentration of Fe(II) in ISM increased the values of rate constants, while increasing the concentration of PCE DNAPL did not affect the value of the rate constant. The reactivity of ISM for PCE dechlorination might be close to that of Friedel's salt, and the accumulation of trichloroethylene (TCE) might imply the lower reactivity of ISM for degradation of TCE or the necessity of large amount of Fe(II) in ISM. TCE (the major chlorinated intermediate), ethene (the major non-chlorinated compound), acetylene and ethane were detected, which implied that both hydrogenolysis and beta-elimination were pathways of PCE DNAPL degradation on ISM.

Triton X-114 based cloud point extraction: a thermoreversible approach for separation/concentration and dispersion of nanomaterials in the aqueous phase.

PubMed

Liu, Jing-fu; Liu, Rui; Yin, Yong-guang; Jiang, Gui-bin

2009-03-28

Capable of preserving the sizes and shapes of nanomaterials during the phase transferring, Triton X-114 based cloud point extraction provides a general, simple, and cost-effective route for reversible concentration/separation or dispersion of various nanomaterials in the aqueous phase.

Anomalistic Self-Assembled Phase Behavior of Block Copolymer Blended with Organic Derivative Depending on Temperature

DOE PAGES

Kim, Tae-Hwan; Kim, Eunhye; Do, Changwoo; ...

2016-08-16

Amphiphilic Pluronic block copolymers have attracted great attention in a broad spectrum of potential applications due to the excellent phase behaviors in an aqueous solution, and many efforts have been made to investigate their phase behaviors under various external conditions. With a variety of external conditions, however, the closed looplike phase behaviors of a Pluronic block copolymer in an aqueous solution have not been reported yet. Herein, we report the closed looplike (CLL) phase behavior of a Pluronic P65 triblock copolymer blended with an organic derivative, 5-methylsalicylic acid (5mS), in aqueous solution, which is very unique for block copolymers. Asmore » the 5mS concentration increases, the isotropic to ordered phase or back to isotropic phase transition temperature is decreased while the number of closed loops is increased to two. To the best of our knowledge, this is the first demonstration of a CLL phase transition of a Pluronic block copolymer in an aqueous solution, which is readily applicable to optical devices such as optical sensors or optoelectronics, and nanotemplates for a highly ordered superlattice. Additionally, this provides new insight into the understanding on the phase behavior of a Pluronic block copolymer blended with additives.« less

Anomalistic Self-Assembled Phase Behavior of Block Copolymer Blended with Organic Derivative Depending on Temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Tae-Hwan; Kim, Eunhye; Do, Changwoo

Amphiphilic Pluronic block copolymers have attracted great attention in a broad spectrum of potential applications due to the excellent phase behaviors in an aqueous solution, and many efforts have been made to investigate their phase behaviors under various external conditions. With a variety of external conditions, however, the closed looplike phase behaviors of a Pluronic block copolymer in an aqueous solution have not been reported yet. Herein, we report the closed looplike (CLL) phase behavior of a Pluronic P65 triblock copolymer blended with an organic derivative, 5-methylsalicylic acid (5mS), in aqueous solution, which is very unique for block copolymers. Asmore » the 5mS concentration increases, the isotropic to ordered phase or back to isotropic phase transition temperature is decreased while the number of closed loops is increased to two. To the best of our knowledge, this is the first demonstration of a CLL phase transition of a Pluronic block copolymer in an aqueous solution, which is readily applicable to optical devices such as optical sensors or optoelectronics, and nanotemplates for a highly ordered superlattice. Additionally, this provides new insight into the understanding on the phase behavior of a Pluronic block copolymer blended with additives.« less

Cryogelation of molecularly imprinted nanoparticles: a macroporous structure as affinity chromatography column for removal of β-blockers from complex samples.

PubMed

Hajizadeh, Solmaz; Xu, Changgang; Kirsebom, Harald; Ye, Lei; Mattiasson, Bo

2013-01-25

In this work, a new macroporous molecularly imprinted cryogel (MIP composite cryogel) was synthesized by glutaraldehyde cross-linking reaction of poly(vinyl alcohol) (PVA) particles and amino-modified molecularly imprinted core-shell nanoparticles. The MIP core-shell nanoparticles were prepared using propranolol as a template by one-pot precipitation polymerization with sequential monomer addition. The characteristics of the MIP composite cryogel were studied by scanning electron microscopy (SEM) and texture analyzer. The macroporous structure of the composite (with the pore size varying from a few micrometers to 100 μm) enabled high mass transfer of particulate-containing fluids. In a solid phase extraction (SPE) process, the efficiency and selectivity of the MIP composite cryogel were investigated, where the cryogel was used as an affinity matrix to remove propranolol from aqueous solution as well as from complex plasma sample without prior protein precipitation. The MIP composite cryogel maintained high selectivity and stability and could be used repeatedly after regeneration. Copyright © 2012 Elsevier B.V. All rights reserved.

SEPARATION OF POLONIUM, PROTACTINIUM OR MIXTURES THEREOF IN AQUEOUS SOLUTION FROM BISMUTH, LEAD, ZIRCONIUM AND/OR COLUMBIUM VALUES

DOEpatents

Van Winkle, Q.; Kraus, K.A.

1959-10-27

A process is presented for separating polonium, protactinium, or mixtures thereof in aqueous solution from bismuth, zirconium, lead, and niobium values contained in the solution. The method comprises providing hydrochloric acid in the solution in a concentration of at least 5N. contacting the aqueous solution with a substantially waterimmiscible organic solvent such as diisopropyl ketone, and separating the aqueous phase containing the bismuth, zirconium, lead, and niobium from the organic extract phase containing the polonium, protactinium, or mixture thereof.

Process for recovering chaotropic anions from an aqueous solution also containing other ions

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1999-01-01

A solid/liquid process for the separation and recovery of chaotropic anions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the chaotropic anions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt (lyotrope). A solid/liquid phase admixture of separation particles containing bound chaotropic anions in such an aqueous solution is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture.

Process for recovering chaotropic anions from an aqueous solution also containing other ions

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1999-03-30

A solid/liquid process for the separation and recovery of chaotropic anions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the chaotropic anions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt (lyotrope). A solid/liquid phase admixture of separation particles containing bound chaotropic anions in such an aqueous solution is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture. 19 figs.

Adsorptive removal of phthalate ester (Di-ethyl phthalate) from aqueous phase by activated carbon: a kinetic study.

PubMed

Venkata Mohan, S; Shailaja, S; Rama Krishna, M; Sarma, P N

2007-07-19

Adsorptive studies were carried out on Di-ethyl phthalate (DEP) removal from aqueous phase onto activated carbon. Batch sorption studies were performed and the results revealed that activated carbon demonstrated ability to adsorb DEP. Influence of varying experimental conditions such as DEP concentration, pH of aqueous solution, and dosage of adsorbent were investigated on the adsorption process. Sorption interaction of DEP onto activated carbon obeyed the pseudo second order rate equation. Experimental data showed good fit with both the Langmuir and Freundlich adsorption isotherm models. DEP sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at acidic pH.

SE-72/AS-72 generator system based on Se extraction/ As reextraction

DOEpatents

Fassbender, Michael Ernst; Ballard, Beau D

2013-09-10

The preparation of a .sup.72Se/.sup.72As radioisotope generator involves forming an acidic aqueous solution of an irradiated alkali bromide target such as a NaBr target, oxidizing soluble bromide in the solution to elemental bromine, removing the elemental bromine, evaporating the resulting solution to a residue, removing hydrogen chloride from the residue, forming an acidic aqueous solution of the residue, adding a chelator that selectively forms a chelation complex with selenium, and extracting the chelation complex from the acidic aqueous solution into an organic phase. As the .sup.72Se generates .sup.72As in the organic phase, the .sup.72As may be extracted repeatedly from the organic phase with an aqueous acid solution.

Large scale synthesis of nanostructured zirconia-based compounds from freeze-dried precursors

NASA Astrophysics Data System (ADS)

Gómez, A.; Villanueva, R.; Vie, D.; Murcia-Mascaros, S.; Martínez, E.; Beltrán, A.; Sapiña, F.; Vicent, M.; Sánchez, E.

2013-01-01

Nanocrystalline zirconia powders have been obtained at the multigram scale by thermal decomposition of precursors resulting from the freeze-drying of aqueous acetic solutions. This technique has equally made possible to synthesize a variety of nanostructured yttria or scandia doped zirconia compositions. SEM images, as well as the analysis of the XRD patterns, show the nanoparticulated character of those solids obtained at low temperature, with typical particle size in the 10-15 nm range when prepared at 673 K. The presence of the monoclinic, the tetragonal or both phases depends on the temperature of the thermal treatment, the doping concentration and the nature of the dopant. In addition, Rietveld refinement of the XRD profiles of selected samples allows detecting the coexistence of the tetragonal and the cubic phases for high doping concentration and high thermal treatment temperatures. Raman experiments suggest the presence of both phases also at relatively low treatment temperatures.

Aqueous biphasic systems formed by deep eutectic solvent and new-type salts for the high-performance extraction of pigments.

PubMed

Zhang, Hongmei; Wang, Yuzhi; Zhou, Yigang; Chen, Jing; Wei, Xiaoxiao; Xu, Panli

2018-05-01

Deep eutectic solvent (DES) composed of polypropylene glycol 400 (PPG 400) and tetrabutylammonium bromide (TBAB) was combined with a series of new-type salts such as quaternary ammonium salts, amino acid and polyols to form Aqueous Biphasic Systems (ABSs). Phase-forming ability of the salts was investigated firstly. The results showed that polyols had a relatively weak power to produce phases within studied scopes. And the shorter of carbon chain length of salts, the easier to obtain phase-splitting. Then partitioning of three pigments in PPG 400/betaine-based ABSs was addressed to investigate the effect of pigments' hydrophobicity on extraction efficiency. It was found that an increase in hydrophobicity contributed to the migration of pigments in the DES-rich phase. On the other hand, with a decline in phase-forming ability of salts, the extraction efficiency of the whole systems started to go down gradually. Based on the results, selective separation experiment was conducted successfully in the PPG 400/betaine-based systems, including more than 93.00% Sudan Ⅲ in the top phase and about 80.00% sunset yellow FCF/amaranth in the bottom phase. Additionally, ABSs constructed by DES/betaine for partitioning amaranth were further utilized to explore the performances of influence factors and back extraction. It can be concluded that after the optimization above 98.00% amaranth was transferred into the top phase. And 67.98% amaranth can be transferred into the bottom phase in back-extraction experiment. At last, dynamic light scattering (DLS) and transmission electron microscope (TEM) were applied to probe into extraction mechanism. The results demonstrated that hydrophobicity played an important role in the separation process of pigments. Through combining with new-type DES, this work was devoted to introducing plentiful salts as novel compositions of ABSs and providing an eco-friendly extraction way for partitioning pigments, which boosted development of ABSs in the monitoring food safety field. Copyright © 2018 Elsevier B.V. All rights reserved.

Extraction and characterization of polysaccharides from Semen Cassiae by microwave-assisted aqueous two-phase extraction coupled with spectroscopy and HPLC.

PubMed

Chen, Zhi; Zhang, Wei; Tang, Xunyou; Fan, Huajun; Xie, Xiujuan; Wan, Qiang; Wu, Xuehao; Tang, James Z

2016-06-25

A novel and rapid method for simultaneous extraction and separation of the different polysaccharides from Semen Cassiae (SC) was developed by microwave-assisted aqueous two-phase extraction (MAATPE) in a one-step procedure. Using ethanol/ammonium sulfate system as a multiphase solvent, the effects of MAATPE on the extraction of polysaccharides from SC such as the composition of the ATPS, extraction time, temperature and solvent-to-material ratio were investigated by UV-vis analysis. Under the optimum conditions, the yields of polysaccharides were 4.49% for the top phase, 8.80% for the bottom phase and 13.29% for total polysaccharides, respectively. Compared with heating solvent extraction and ultrasonic assisted extraction, MAATPE exhibited the higher extraction yields in shorter time. Fourier-transform infrared spectra showed that two polysaccharides extracted from SC to the top and bottom phases by MAATPE were different from each other in their chemical structures. Through acid hydrolysis and PMP derivatization prior to HPLC, analytical results by indicated that a polysaccharide of the top phases was a relatively homogeneous homepolysaccharide composed of dominant gucose glucose while that of the bottom phase was a water-soluble heteropolysaccharide with multiple components of glucose, xylose, arabinose, galactose, mannose and glucuronic acid. Molar ratios of monosaccharides were 95.13:4.27:0.60 of glucose: arabinose: galactose for the polysaccharide from the top phase and 62.96:14.07:6.67: 6.67:5.19:4.44 of glucose: xylose: arabinose: galactose: mannose: glucuronic acid for that from the bottom phase, respectively. The mechanism for MAATPE process was also discussed in detail. MAATPE with the aid of microwave and the selectivity of the ATPS not only improved yields of the extraction, but also obtained a variety of polysaccharides. Hence, it was proved as a green, efficient and promising alternative to simultaneous extraction of polysaccharides from SC. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of Recombinant Human Growth Hormone (rhGH) sustained-release microspheres by a low temperature aqueous phase/aqueous phase emulsion method.

PubMed

Kang, Jian; Wu, Fei; Cai, Yunpeng; Xu, Mingxin; He, Mu; Yuan, Weien

2014-10-01

A novel method has been developed to protect Recombinant Human Growth Hormone (rhGH) in poly (lactic-co-glycolic acid) (PLGA) microspheres using an aqueous phase/aqueous phase emulsion and S/O/W multi-emulsion method. This method develops a novel rhGH sustained-release system, which is based on the combination of rhGH-loaded dextran microparticles and PLGA microspheres. The process to fabricate rhGH-loaded dextran microparticles involves an aqueous phase/aqueous phase emulsion system formed at the reduced temperature. RhGH was first dissolved in water together with dextran and polyethylene glycol, followed by stirring at the speed of 2000 rpm for 20-30s at 0°C, and then a freezing process could enable the dextran phase to separate from the continuous PEG phase and rhGH could preferentially be loaded with dextran. The sample after freezing and phase separation was then lyophilized to powder and washed with dichloromethane to remove the PEG. Once loaded in the dextran microparticles (1-4 μm in diameter), rhGH gained resistance to interface tensions and was encapsulated into PLGA microspheres without aggregation thereafter. RhGH released from PLGA microspheres was in a sustained manner with minimal burst and maximally reduced incomplete release in vitro. Single subcutaneous injection of rhGH-loaded PLGA microspheres to rats resulted in a stable plasma concentration for 30 days avoiding the drug concentration fluctuations after multiple injections of protein solutions. In a hypophysectomized rat model, the IGF-1 and bodyweight results showed that there were higher than the levels obtained for the sustained release formulation by W/O/W for 40 days. These results suggest that the microsphere delivery system had the potential to be an injectable depot for sustained-release of the biocompatible protein of rhGH. Copyright © 2014 Elsevier B.V. All rights reserved.

Separation of four flavonol glycosides from Solanum rostratum Dunal using aqueous two-phase flotation followed by preparative high-performance liquid chromatography.

PubMed

Chang, Lin; Shao, Qian; Xi, Xingjun; Chu, Qiao; Wei, Yun

2017-02-01

Aqueous two-phase flotation followed by preparative high-performance liquid chromatography was used to separate four flavonol glycosides from Solanum rostratum Dunal. In the aqueous two-phase flotation section, the effects of sublation solvent, solution pH, (NH 4 ) 2 SO 4 concentration in aqueous solution, cosolvent, N 2 flow rate, flotation time, and volumes of the polyethylene glycol phase on the recovery were investigated in detail, and the optimal conditions were selected: 50 wt% polyethylene glycol 1000 ethanol solvent as the flotation solvent, pH 4, 350 g/L of (NH 4 ) 2 SO 4 concentration in aqueous phase, 40 mL/min of N 2 flow rate, 30 min of flotation time, 10.0 mL of flotation solvent volume, and two times. After aqueous two-phase flotation concentration, the flotation products were purified by preparative high-performance liquid chromatography. The purities of the final products A and B were 98.1 and 99.0%. Product B was the mixture of three compounds based on the analysis of high-performance liquid chromatography at the temperature of 10°C, while product A was hyperoside after the identification by nuclear magnetic resonance. Astragalin, 3'-O-methylquercetin 3-O-β-d-galactopyranoside, and 3'-O-methylquercetin 3-O-β-d-glucopyranoside were obtained with the purity of 93.8, 97.1, and 99.2%, respectively, after the further separation of product B using preparative high-performance liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Three-dimensional mapping of crystalline ceramic waste form materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cocco, Alex P.; DeGostin, Matthew B.; Wrubel, Jacob A.

Here, we demonstrate the use of synchrotron-based, transmission X-ray microscopy (TXM) and scanning electron microscopy to image the 3-D morphologies and spatial distributions of Ga-doped phases within model, single- and two-phase waste form material systems. Gallium doping levels consistent with those commonly used for nuclear waste immobilization (e.g., Ba 1.04Cs 0.24Ga 2.32Ti 5.68O 16) could be readily imaged. This analysis suggests that a minority phase with different stoichiometry/composition from the primary hollandite phase can be formed by the solid-state ceramic processing route with varying morphology (globular vs. cylindrical) as a function of Cs content. Our results represent a crucial stepmore » in developing the tools necessary to gain an improved understanding of the microstructural and chemical properties of waste form materials that influence their resistance to aqueous corrosion. This understanding will aid in the future design of higher durability waste form materials.« less

Three-dimensional mapping of crystalline ceramic waste form materials

DOE PAGES

Cocco, Alex P.; DeGostin, Matthew B.; Wrubel, Jacob A.; ...

2017-04-21

Here, we demonstrate the use of synchrotron-based, transmission X-ray microscopy (TXM) and scanning electron microscopy to image the 3-D morphologies and spatial distributions of Ga-doped phases within model, single- and two-phase waste form material systems. Gallium doping levels consistent with those commonly used for nuclear waste immobilization (e.g., Ba 1.04Cs 0.24Ga 2.32Ti 5.68O 16) could be readily imaged. This analysis suggests that a minority phase with different stoichiometry/composition from the primary hollandite phase can be formed by the solid-state ceramic processing route with varying morphology (globular vs. cylindrical) as a function of Cs content. Our results represent a crucial stepmore » in developing the tools necessary to gain an improved understanding of the microstructural and chemical properties of waste form materials that influence their resistance to aqueous corrosion. This understanding will aid in the future design of higher durability waste form materials.« less

Comparison of adsorption coefficient (K[sub oc]) for soils and HPLC retention factors of aromatic hydrocarbons using a chemically immobilized humic acid column in RP-HPLC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szabo, G.; Bulman, R.A.

The determination of soil adsorption coefficients (K[sub oc]) via HPLC capacity factors (k[prime]) has been studied, including the effect of column type and mobile phase composition on the correlation between log K[sub oc] and log k[prime]. K[sub oc] values obtained by procedures other than HPLC correlate well with HPLC capacity factors determined on a chemically immobilized humic acid stationary phase, and it is suggested that this phase is a better model for the sorption onto soil or sediment than the octadecyl-, phenyl- and ethylsilica phases. By using log k[prime][sub w] a theoretical capacity factor has been obtained by extrapolation ofmore » the retention data in a binary solvent system to pure aqueous eluent. There is a better correlation between log K[sub oc] and log k[prime][sub w] than the correlation between log K[sub oc] and log k[prime].« less

Effect of oil concentration and residence time on the biodegradation of α-pinene vapours in two-liquid phase suspended-growth bioreactors.

PubMed

Montes, María; Veiga, María C; Kennes, Christian

2012-02-20

Recently, research on the use of binary aqueous-organic liquid phase systems for the treatment of polluted air has significantly increased. This paper reports the removal of α-pinene from a waste air stream in a continuous stirred tank bioreactor (CSTB), using either a single-liquid aqueous phase or a mixed aqueous-organic liquid phase. The influence of gas flow rate, load and pollutant concentration was evaluated as well as the effect of the organic to aqueous phase ratio. Continuous experiments were carried out at different inlet α-pinene concentrations, ranging between 0.03 and 25.1 g m⁻³ and at four different flow rates, corresponding to residence times (RTs) of 120 s, 60 s, 36 s and 26 s. The maximum elimination capacities (ECs) reached in the CSTB were 382 g m⁻³ h⁻¹ (without silicone oil) and 608 g m⁻³ h⁻¹ (with 5%v/v silicone oil), corresponding to a 1.6-fold improvement using an aqueous-organic liquid phase. During shock-loads experiments, the performance and stability of the CSTB were enhanced with 5% silicone oil, quickly recovering almost 100% removal efficiency (RE), when pre-shock conditions were restored. The addition of silicone oil acted as a buffer for high α-pinene loads, showing a more stable behaviour in the case of two-liquid-phase systems. Copyright © 2011 Elsevier B.V. All rights reserved.

Formation of uniform carrot-like Cu31S16-CuInS2 heteronanostructures assisted by citric acid at the oil/aqueous interface.

PubMed

Li, Yongjie; Tang, Aiwei; Liu, Zhenyang; Peng, Lan; Yuan, Yi; Shi, Xifeng; Yang, Chunhe; Teng, Feng

2018-01-07

A simple two-phase strategy was developed to prepare Cu 31 S 16 -CuInS 2 heterostructures (HNS) at the oil/aqueous interface, in which the In(OH) 3 phase was often obtained in the products due to the reaction between indium ions and hydroxyl ions in the aqueous phase. To prevent the formation of the In(OH) 3 phase, citric acid was incorporated into the aqueous phase to assist in the synthesis of uniform carrot-like Cu 31 S 16 -CuInS 2 semiconductor HNS at the oil/aqueous interface for the first time. By manipulating the dosage of citric acid and Cu/In precursor ratios, the morphology of the Cu 31 S 16 -CuInS 2 HNS could be tailored from mushroom to carrot-like, and the presence of citric acid played a critical role in the synthesis of high-quality Cu 31 S 16 -CuInS 2 HNS, which inhibited the formation of the In(OH) 3 phase due to the formation of the indium(iii)-citric acid complex. The formation mechanism was studied by monitoring the morphology and phase evolution of the Cu 31 S 16 -CuInS 2 HNS with reaction time, which revealed that the Cu 31 S 16 seeds were first formed and then the cation-exchange reaction directed the subsequent anisotropic growth of the Cu 31 S 16 -CuInS 2 HNS.

Separation of switchgrass bio-oil by water/organic solvent addition and pH adjustment

DOE PAGES

Park, Lydia Kyoung-Eun; Ren, Shoujie; Yiacoumi, Sotira; ...

2016-01-29

Applications of bio-oil are limited by its challenging properties including high moisture content, low pH, high viscosity, high oxygen content, and low heating value. Separation of switchgrass bio-oil components by adding water, organic solvents (hexadecane and octane), and sodium hydroxide may help to overcome these issues. Acetic acid and phenolic compounds were extracted in aqueous and organic phases, respectively. Polar chemicals, such as acetic acid, did not partition in the organic solvent phase. Acetic acid in the aqueous phase after extraction is beneficial for a microbial-electrolysis-cell application to produce hydrogen as an energy source for further hydrodeoxygenation of bio-oil. Organicmore » solvents extracted more chemicals from bio-oil in combined than in sequential extraction; however, organic solvents partitioned into the aqueous phase in combined extraction. When sodium hydroxide was added to adjust the pH of aqueous bio-oil, organic-phase precipitation occurred. As the pH was increased, a biphasic aqueous/organic dispersion was formed, and phase separation was optimized at approximately pH 6. The neutralized organic bio-oil had approximately 37% less oxygen and 100% increased heating value than the initial centrifuged bio-oil. In conclusion, the less oxygen content and increased heating value indicated a significant improvement of the bio-oil quality through neutralization.« less

Separation of switchgrass bio-oil by water/organic solvent addition and pH adjustment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Lydia Kyoung-Eun; Ren, Shoujie; Yiacoumi, Sotira

Applications of bio-oil are limited by its challenging properties including high moisture content, low pH, high viscosity, high oxygen content, and low heating value. Separation of switchgrass bio-oil components by adding water, organic solvents (hexadecane and octane), and sodium hydroxide may help to overcome these issues. Acetic acid and phenolic compounds were extracted in aqueous and organic phases, respectively. Polar chemicals, such as acetic acid, did not partition in the organic solvent phase. Acetic acid in the aqueous phase after extraction is beneficial for a microbial-electrolysis-cell application to produce hydrogen as an energy source for further hydrodeoxygenation of bio-oil. Organicmore » solvents extracted more chemicals from bio-oil in combined than in sequential extraction; however, organic solvents partitioned into the aqueous phase in combined extraction. When sodium hydroxide was added to adjust the pH of aqueous bio-oil, organic-phase precipitation occurred. As the pH was increased, a biphasic aqueous/organic dispersion was formed, and phase separation was optimized at approximately pH 6. The neutralized organic bio-oil had approximately 37% less oxygen and 100% increased heating value than the initial centrifuged bio-oil. In conclusion, the less oxygen content and increased heating value indicated a significant improvement of the bio-oil quality through neutralization.« less

Retention of ionisable compounds on high-performance liquid chromatography XVII. Estimation of the pH variation of aqueous buffers with the change of the methanol fraction of the mobile phase.

PubMed

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2007-01-05

The use of methanol-aqueous buffer mobile phases in HPLC is a common election when performing chromatographic separations of ionisable analytes. The addition of methanol to the aqueous buffer to prepare such a mobile phase changes the buffer capacity and the pH of the solution. In the present work, the variation of these buffer properties is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-hydrogencitrate-citrate, and ammonium-ammonia buffers. It is well established that the pH change of the buffers depends on the initial concentration and aqueous pH of the buffer, on the percentage of methanol added, and on the particular buffer used. The proposed equations allow the pH estimation of methanol-water buffered mobile phases up to 80% in volume of organic modifier from initial aqueous buffer pH and buffer concentration (before adding methanol) between 0.001 and 0.01 mol L(-1). From both the estimated pH values of the mobile phase and the estimated pKa of the ionisable analytes, it is possible to predict the degree of ionisation of the analytes and therefore, the interpretation of acid-base analytes behaviour in a particular methanol-water buffered mobile phase.

The prediction of the flash point for binary aqueous-organic solutions.

PubMed

Liaw, Horng-Jang; Chiu, Yi-Yu

2003-07-18

A mathematical model, which may be used for predicting the flash point of aqueous-organic solutions, has been proposed and subsequently verified by experimentally-derived data. The results reveal that this model is able to precisely predict the flash point over the entire composition range of binary aqueous-organic solutions by way of utilizing the flash point data pertaining to the flammable component. The derivative of flash point with respect to composition (solution composition effect upon flash point) can be applied to process safety design/operation in order to identify as to whether the dilution of a flammable liquid solution with water is effective in reducing the fire and explosion hazard of the solution at a specified composition. Such a derivative equation was thus derived based upon the flash point prediction model referred to above and then verified by the application of experimentally-derived data.

Removal of Congo red dye from aqueous solutions using a halloysite-magnetite-based composite.

PubMed

Ferrarini, F; Bonetto, L R; Crespo, Janaina S; Giovanela, M

2016-01-01

Adsorption has been considered as one of the most effective methods to remove dyes from aqueous solutions due to its ease of operation, high efficiency and wide adaptability. In view of all these aspects, this study aimed to evaluate the adsorption capacity of a halloysite-magnetite-based composite in the removal of Congo red dye from aqueous solutions. The effects of stirring rate, pH, initial dye concentration and contact time were investigated. The results revealed that the adsorption kinetics followed the pseudo-second-order model, and equilibrium was well represented by the Brunauer-Emmett-Teller isotherm. The thermodynamic data showed that dye adsorption onto the composite was spontaneous and endothermic and occurred by physisorption. Finally, the composite could also be regenerated at least four times by calcination and was shown to be a promising adsorbent for the removal of this dye.

A resolution approach of racemic phenylalanine with aqueous two-phase systems of chiral tropine ionic liquids.

PubMed

Wu, Haoran; Yao, Shun; Qian, Guofei; Yao, Tian; Song, Hang

2015-10-30

Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu(2+) based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance. Copyright © 2015. Published by Elsevier B.V.

Non-aqueous phase cold vapor generation and determination of trace cadmium by atomic fluorescence spectrometry.

PubMed

Lei, Zirong; Chen, Luqiong; Hu, Kan; Yang, Shengchun; Wen, Xiaodong

2018-06-05

Cold vapor generation (CVG) of cadmium was firstly accomplished in non-aqueous media by using solid reductant of potassium borohydride (KBH 4 ) as a derivation reagent. The mixture of surfactant Triton X-114 micelle and octanol was innovatively used as the non-aqueous media for the CVG and atomic fluorescence spectrometry (AFS) was used for the elemental determination. The analyte ions were firstly extracted into the non-aqueous media from the bulk aqueous phase of analyte/sample solution via a novelly established ultrasound-assisted rapidly synergistic cloud point extraction (UARS-CPE) process and then directly mixed with the solid redcutant KBH 4 to generate volatile elemental state cadmium in a specially designed reactor, which was then rapidly transported to a commercial atomic fluorescence spectrometer for detection. Under the optimal conditions, the limit of detection (LOD) for cadmium was 0.004 μg L -1 . Compared to conventional hydride generation (HG)-AFS, the efficiency of non-aqueous phase CVG and the analytical performance of the developed system was considerably improved. Copyright © 2018 Elsevier B.V. All rights reserved.

Temperature dependent kinetic measurements of isoprene oxidation products exposed to OH, NO3 and SO4- in aqueous solution.

NASA Astrophysics Data System (ADS)

Schöne, L.; Hoffmann, D.; Herrmann, H.

2010-07-01

The troposphere contains a complex mixture of numerous gases, liquid water and diverse solid particles which undergo intricate processes. Volatile organic compound (VOC) emissions from anthropogenic and biogenic sources are very important for the tropospheric chemistry and other processes such as secondary organic particle mass formation. Emissions of biogenic volatile organic compounds (BVOCs) exceed those VOCs coming from human activity by a factor of 10 [1]. Isoprene (2-methyl-1,3-butadiene, C5H8) emissions represent approximately 40% of the emitted BVOCs, leading to an estimated source strength of 500-750Tgyr-1 [2]. As isoprene has a small Henry coefficient, its oxidation occurs solely in the gas phase. The formed first oxidation products methacrolein (MACR), methyl vinyl ketone (MVK), methacrylic acid (MAA) and acrylic acid (ACA) are therefore firstly located in that phase. Even if the Henry coefficients of the main isoprene oxidation products MACR and MVK are already higher than those of isoprene partitioning of theses compounds into the aqueous phase of rain, fog and cloud droplets and particles was neglected. Correspondingly, aqueous phase oxidation processes of MACR and MVK were sparsely investigated in the past. A recent study [3], however, reports much higher aqueous phase concentrations of MACR and MVK than expected from their Henry coefficients. To evaluate the importance of liquid phase reactions of early isoprene oxidation products for the organic particle mass production, kinetic studies are necessary. Therefore, this work investigated the temperature dependence of methacrolein, methyl vinyl ketone, methacrylic acid and acrylic acid exposed to NO3, SO4- and OH radicals in the range of 278K to 318K in the aqueous phase. Furthermore, the effect of the acid-base equilibrium on the reactivity of the two acids was studied by measuring the kinetics of the dissociated and undissociated acids. The measurements were performed using a laser-photolysis laser long path absorption (LP-LLPA) technique. The measurements’ analysis confirmed in all cases the much higher reactivity of the hydroxyl radical (k~10^9M-1s-1) in comparison to the sulfate (k~108 M-1s-1) and the nitrate (k~10^7M-1s-1) radical, with methacrylic acid showing steadily the highest reactivity among the investigated substances. The temperature dependence of the measured rate constants is most distinct for nitrate radical reactions and weakest for those with sulfate radicals. Referred to the two different considered pH-values of the acids, the protonated form reacts slightly faster than the unprotonated form and shows a less distinct temperature dependence. [1] Guenther et al., 1995: Global-model of natural volatile organic-compound emissions. Journal of Geophysical Research - Atmosphere, 100(D5), 8873-8892. [2] Guenther et al. 2006: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature). Atmospheric Chemical Physics, 6, 3181-3210. [3] van Pinxteren et al., 2005: Schmücke hill cap cloud and valley stations aerosol chemical composition during FEBUKO (II): Organic compounds. Atmospheric Environment, 39, 4305-4320.

Aqueous Alteration on Mars: Evidence from Landed Missions

NASA Technical Reports Server (NTRS)

Ming, Douglas W.; Morris, Richard V.; Clark, Benton C., III; Yen, Albert S.; Gellert, Ralf

2015-01-01

Mineralogical and geochemical data returned by orbiters and landers over the past 15 years have substantially enhanced our understanding of the history of aqueous alteration on Mars. Here, we summarize aqueous processes that have been implied from data collected by landed missions. Mars is a basaltic planet. The geochemistry of most materials has not been “extensively” altered by open-system aqueous processes and have average Mars crustal compositions. There are few examples of open-system alteration, such as Gale crater’s Pahrump Hills mudstone. Types of aqueous alteration include (1) acid-sulfate and (2) hydrolytic (circum-neutral/alkaline pH) with varying water-to-rock ratios. Several hypotheses have been suggested for acid-sulfate alteration including (1) oxidative weathering of ultramafic igneous rocks containing sulfides; (2) sulfuric acid weathering of basaltic materials; (3) acid fog weathering of basaltic materials; and (4) near-neutral pH subsurface solutions rich in Fe (sup 2 plus) that rapidly oxidized to Fe (sup 3 plus) producing excess acidity. Meridiani Planum’s sulfate-rich sedimentary deposit containing jarosite is the most “famous” acid-sulfate environment visited on Mars, although ferric sulfate-rich soils are common in Gusev crater’s Columbia Hills and jarosite was recently discovered in the Pahrump Hills. An example of aqueous alteration under circum-neutral pH conditions is the formation of Fe-saponite with magnetite in situ via aqueous alteration of olivine in Gale crater’s Sheepbed mudstone. Circum-neutral pH, hydrothermal conditions were likely required for the formation of Mg-Fe carbonate in the Columbia Hills. Diagenetic features (e.g., spherules, fracture filled veins) indicate multiple episodes of aqueous alteration/diagenesis in most sedimentary deposits. However, low water-to-rock ratios are prominent at most sites visited by landed missions (e.g., limited water for reaction to form crystalline phases possibly resulting in large amounts of short-range ordered materials and little physical separation of primary and secondary materials). Most of the aqueous alteration appears to have occurred early in the planet’s history; however, minor aqueous alteration may be occurring at the surface today (e.g., thin films of water forming carbonates akin to those discovered by Phoenix).

Visible Light Assisted Photocatalytic Hydrogen Generation by Ta 2O 5/Bi 2O 3, TaON/Bi 2O 3, and Ta 3N 5/Bi 2O 3 Composites

DOE PAGES

Adhikari, Shiba; Hood, Zachary D.; More, Karren Leslie; ...

2015-06-15

Composites comprised of two semiconducting materials with suitable band gaps and band positions have been reported to be effective at enhancing photocatalytic activity in the visible light region of the electromagnetic spectrum. Here, we report the synthesis, complete structural and physical characterizations, and photocatalytic performance of a series of semiconducting oxide composites. UV light active tantalum oxide (Ta2O5) and visible light active tantalum oxynitride (TaON) and tantalum nitride (Ta 3N 5) were synthesized, and their composites with Bi 2O 3 were prepared in situ using benzyl alcohol as solvent. The composite prepared using equimolar amounts of Bi 2O 3 andmore » Ta 2O 5 leads to the formation of the ternary oxide, bismuth tantalate (BiTaO 4) upon calcination at 1000 °C. The composites and single phase bismuth tantalate formed were characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) surface area measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy, and photoluminescence. The photocatalytic activities of the catalysts were evaluated for generation of hydrogen using aqueous methanol solution under visible light irradiation (λ ≥ 420 nm). The results show that as-prepared composite photocatalysts extend the light absorption range and restrict photogenerated charge-carrier recombination, resulting in enhanced photocatalytic activity compared to individual phases. The mechanism for the enhanced photocatalytic activity for the heterostructured composites is elucidated based on observed activity, band positions calculations, and photoluminescence data.« less

ILLUMINATING THE ROLE OF AGGLOMERATES ON CRITICAL PHYSICOCHEMICAL PROPERTIES OF AMORPHOUS CALCIUM PHOSPHATE COMPOSITES

PubMed Central

O’Donnell, J.N.R.; Antonucci, J.M.; Skrtic, D.

2009-01-01

Water sorption (WS), mechanical strength, and ion release of polymeric composites formulated with 40 % as-made or milled amorphous calcium phosphate (ACP) are compared after 1, 2 and 3 months of aqueous exposure. Ethoxylated bisphenol A dimethacrylate, triethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate and methacryloxyethyl phthalate comprised the resin. The WS (mass %) peaked at 3 months. WS of as-made ACP composites was significantly higher than WS of milled ACP composites and copolymers. Both composite groups experienced decreases in biaxial flexural strength (BFS) with water aging, with milled ACP composites retaining a significantly higher BFS throughout immersion. Ion release was moderately reduced in milled ACP composites, though they remained superior to as-made ACP composites due to significantly lower WS and higher BFS after prolonged aqueous exposure. PMID:19774100

The pH Dependence of Brown Carbon Formation in Maillard Chemistry

NASA Astrophysics Data System (ADS)

Hawkins, L. N.; Welsh, H.; Alexander, M. V.

2017-12-01

Secondary organic aerosol (SOA) composes a non-negligible fraction of brown carbon (BrC), and typically appears as small, nitrated aromatics or larger, highly functionalized humic-like substances (HULIS). Both nitrated aromatics and HULIS contain nitrogen, indicating the importance of nitrogen to light-absorbing aerosol. It is therefore unsurprising that BrC, when generated in aqueous phase reactions (aqBrC) between amines and small aldehydes, often resembles atmospheric HULIS. The effects of pH and aqueous phase oxidation on absorptivity and composition were simulated using bulk (microliter) samples under a variety of experimental conditions, including evaporation. The system of amines and small aldehydes included methylamine, ammonium sulfate, glyoxal, and methylglyoxal. Chemical composition of these products was characterized using an Aerosol Chemical Speciation Monitor (ACSM) and a desorption-based atmospheric pressure chemical ionization (APCI) spectrometer. The results of this study indicate that methylamine and methylglyoxal form the most absorptive BrC, cloud processing serves to increase BrC absorptivity, and the generated BrC is highly persistent to oxidative and photodegradation. Lowering the pH to values below 6 reduces absorptivity at shorter wavelengths, but produces a new shoulder beyond 400 nm indicating new chromophore formation. Results of this research also show that evaporation increased formation of large molecular fragments (m/z > 100). Furthermore, the mass spectra showed significant formation of these larger fragments in methylamine systems with little evidence for similar compounds in ammonium sulfate systems. Systems with methylglyoxal had higher absorptivity than all other systems, although in both methylamine and ammonium sulfate systems, glyoxal appeared to result in a higher percentage of large fragments than methylglyoxal. Lastly, hydroxyl radical degradation seemed to have a minimal effect on absorptivity and composition, although longer reaction time may produce a larger effect on both properties. These results may simplify some aspects of atmospheric models (like negligible degradation) but may complicate others (highly variable absorptivity between glyoxal and methylglyoxal).

Near-threshold fatigue behavior of copper alloys in air and aqueous environments: A high cyclic frequency study

NASA Astrophysics Data System (ADS)

Ahmed, Tawfik M.

The near-threshold fatigue crack propagation behavior of alpha-phase copper alloys in desiccated air and several aqueous environments has been investigated. Three commercial alloys of nominal composition Cu-30Ni (Cu-Ni), Cu-30Zn (Cu-Zn) and 90Cu-7Al-3Fe (Cu-Al) were tested. Fatigue tests were conducted using standard prefatigued single edged notched (SEN) specimens loaded in tension at a high frequency of ˜100 Hz. Different R-ratios were employed, mostly at R-ratios of 0.5. Low loading levels were used that corresponded to the threshold and near-threshold regions where Delta Kth ≤ DeltaK ≤ 11 MPa√m. Fatigue tests in the aqueous solutions showed that the effect of different corrosive environments during high frequency testing (˜100 Hz) was not as pronounced as was expected when compared relative to air. Further testing revealed that environmental effects were present and fatigue crack growth rates were influenced by the fluid-induced closure effects which are generally reported in the fatigue literature to be operative only in viscous liquids, not in aqueous solutions. It was concluded that high frequency testing in aqueous environments consistently decreased crack growth rates in a manner similar to crack retardation effects in viscous fluids. Several theoretical models reported in the literature have underestimated, if not failed, to adequately predict the fluid induced closure in aqueous solutions. Results from the desiccated air tests confirmed that, under closure-free conditions (high R-ratios), both threshold values and fatigue crack growth rate of stage II can be related to Young's modulus, in agreement with results from the literature. The role of different mechanical and environmental variables on fatigue behavior becomes most visible in the low R -ratio regime, and contribute to various closure processes.

Apparatus and method for the desulfurization of petroleum by bacteria

DOEpatents

Lizama, H.M.; Scott, T.C.; Scott, C.D.

1995-10-17

A method is described for treating petroleum with anaerobic microorganisms acting as biocatalysts that can remove sulfur atoms from hydrocarbon molecules, under anaerobic conditions, and then convert the sulfur atoms to hydrogen sulfide. The microorganisms utilized are from the family known as the ``Sulfate Reducing Bacteria``. These bacteria generate metabolic energy from the oxidation of organic compounds, but use oxidized forms of sulfur as an electron acceptor. Because the biocatalyst is present in the form of bacteria in an aqueous suspension, whereas the reacting substrate consists of hydrocarbon molecules in an organic phase, the actual desulfurization reaction takes place at the aqueous-organic interphase. To ensure adequate interfacial contacting and mass transfer, a biphasic electrostatic bioreactor system is utilized. The bioreactor is utilized to disperse and recoalesce a biocatalyst contained in the aqueous liquid phase into the organic liquid phase containing the sulfur. High-intensity electrical fields rupture the aqueous drops into a plurality of microdroplets and induce continuous coalescence and redispersion as the microdroplets travel through the organic phase, thus increasing surface area. As the aqueous microdroplets progress through the organic phase, the biocatalyst then reacts with the sulfur to produce hydrogen sulfide which is then removed from the bioreactor. The organic liquid, now free of the sulfur, is ready for immediate use or further processing. 5 figs.

Apparatus and method for the desulfurization of petroleum by bacteria

DOEpatents

Lizama, Hector M.; Scott, Timothy C.; Scott, Charles D.

1995-01-01

A method for treating petroleum with anaerobic microorganisms acting as biocatalysts that can remove sulfur atoms from hydrocarbon molecules, under anaerobic conditions, and then convert the sulfur atoms to hydrogen sulfide. The microorganisms utilized are from the family known as the "Sulfate Reducing Bacteria." These bacteria generate metabolic energy from the oxidation of organic compounds, but use oxidized forms of sulfur as an electron acceptor. Because the biocatalyst is present in the form of bacteria in an aqueous suspension, whereas the reacting substrate consists of hydrocarbon molecules in an organic phase, the actual desulfurization reaction takes place at the aqueous-organic interphase. To ensure adequate interfacial contacting and mass transfer, a biphasic electrostatic bioreactor system is utilized. The bioreactor is utilized to disperse and recoalesce a biocatalyst contained in the aqueous liquid phase into the organic liquid phase containing the sulfur. High-intensity electrical fields rupture the aqueous drops into a plurality of microdroplets and induce continuous coalescence and redispersion as the microdroplets travel through the organic phase, thus increasing surface area. As the aqueous microdroplets progress through the organic phase, the biocatalyst then reacts with the sulfur to produce hydrogen sulfide which is then removed from the bioreactor. The organic liquid, now free of the sulfur, is ready for immediate use or further processing.

Development of an auto-phase separable and reusable graphene oxide-potato starch based cross-linked bio-composite adsorbent for removal of methylene blue dye.

PubMed

Bhattacharyya, Amartya; Banerjee, Bhaskar; Ghorai, Soumitra; Rana, Dipak; Roy, Indranil; Sarkar, Gunjan; Saha, Nayan Ranjan; De, Sriparna; Ghosh, Tapas Kumar; Sadhukhan, Sourav; Chattopadhyay, Dipankar

2018-05-15

In this work, we report the development of a cross-linked bio-composite consisting of graphene oxide, potato starch, cross-linker glutaraldehyde and its application to adsorption of the industrial dye, methylene blue, from aqueous solution. The inexpensiveness, non-hazardous nature and easy bio-degradability are the major reasons for the selection of starch material as one of the components of the bio-composite. The bio-composite has been characterized by FTIR, SEM, XRD, particle size and zeta potential analysis. The FTIR analysis reveals the nature of the binding sites and surface morphology of the bio-composite can be understood through SEM. The auto-phase separability of the adsorbent i.e., the precipitation of the adsorbent without any mechanical means is another factor which makes this particular material very attractive as an adsorbent. Parameters like adsorbent dosage, pH, temperature, rotation speed and salt concentration have been varied to find out the suitable dye adsorption conditions. Furthermore, the time dependence of adsorption process has been analyzed using pseudo-first and pseudo-second order kinetics. The adsorption isotherms have been constructed to suggest convincing mechanistic pathway for this adsorption process. Finally, desorption studies have been successfully performed in 3 cycles, establishing the reusability of the material, which should allow the adsorbent to be economically promising for practical application in wastewater treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

Aqueous-phase source of formic acid in clouds

NASA Technical Reports Server (NTRS)

Chameides, W. L.; Davis, D. D.

1983-01-01

The coupled gas- and aqueous-phase cloud chemistry of HCOOH were examined for controlling factors in the acidity of cloud and rainwater. Attention was given to the aqueous OH/HO2 system that yields an OH species that is highly reactive with other species, notably SO2 and the formaldehyde/formic acid complex. A numerical model was developed to simulate the cloud chemistry in the remote troposphere, with considerations given to CH4-CO-NO(x)-O3-H(x)O(y) system. It was determined that aqueous phase OH radicals can produce and destroy formic acid droplets in daylight conditions, as well as control formic acid levels in rainwater. It is sugested that the same types of reactions may be involved in the control of acetic acid and other organic acids.

Metallomesogenic stationary phase for open-tubular capillary electrochromatography.

PubMed

Chen, Jian-Lian

2006-02-01

A synthetic coppermesogenic polymer is prepared and then covalently bonded to the siloxane-based deactivated column as the stationary phases of open-tubular CEC with essentially high phase ratio. The EOF generated from the modified phase is surveyed through conventional aqueous buffers and hydroorganic mobile phases. Zeta potentials, which are computed from the EOF data and the ratio of dielectric constant to viscosity, are plotted as a function of pH, ionic molarity, and compositional range. These plots responsible for the electroosmotic characteristic of the bonded phases are found to be like those of bare fused-silica or deactivated columns through decreasing or increasing the ACN content in the mobile phase, respectively. This two-phase characteristic is basically derived from the polymeric configuration with carboxylato ligands attached onto the polysiloxane backbone. Phthalates and amino acids are suitable probes to examine the two phenomena, more-polar and less-polar mediums, respectively, and to judge whether the chromatographic retention is the major source of separation mechanism. With the mixing modes of Lewis acid-base interaction, dispersive force, and shape discrimination, the chromatographic partition adequately accomplishes the uneasily resolved separations by only CZE mode, although the electrophoretic migration is truly somewhat involved.

Investigation of novel material for effective photodegradation of bezafibrate in aqueous samples.

PubMed

Regulska, Elżbieta; Karpińska, Joanna

2014-04-01

A novel composite with an enhanced photocatalytic activity was prepared and applied to study the removal of bezafibrate (BZF), a hypolypemic pharmaceutical, from an aqueous environment. For the enhancement of titanium dioxide photoactivity a fullerene derivative, 2-(ferrocenyl) fulleropyrrolidine (FcC60), was synthesized and applied. Obtained composite was found to show a higher catalytic activity than pristine TiO2. Therefore, high hopes are set in composites that are based on carbonaceous nanomaterials and TiO2 as a new efficient photocatalysts.

Trivalent Lanthanide/Actinide Separation Using Aqueous-Modified TALSPEAK Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Travis S. Grimes; Richard D. Tillotson; Leigh R. Martin

TALSPEAK is a liquid/liquid extraction process designed to separate trivalent lanthanides (Ln3+) from minor actinides (MAs) Am3+ and Cm3+. Traditional TALSPEAK organic phase is comprised of a monoacidic dialkyl bis(2-ethylhexyl)phosphoric acid extractant (HDEHP) in diisopropyl benzene (DIPB). The aqueous phase contains a soluble aminopolycarboxylate diethylenetriamine-N,N,N’,N”,N”-pentaacetic acid (DTPA) in a concentrated (1.0-2.0 M) lactic acid (HL) buffer with the aqueous acidity typically adjusted to pH 3.0. TALSPEAK balances the selective complexation of the actinides by DTPA against the electrostatic attraction of the lanthanides by the HDEHP extractant to achieve the desired trivalent lanthanide/actinide group separation. Although TALSPEAK is considered a successfulmore » separations scheme, recent fundamental studies have highlighted complex chemical interactions occurring in the aqueous and organic phases during the extraction process. Previous attempts to model the system have shown thermodynamic models do not accurately predict the observed extraction trends in the p[H+] range 2.5-4.8. In this study, the aqueous phase is modified by replacing the lactic acid buffer with a variety of simple and longer-chain amino acid buffers. The results show successful trivalent lanthanide/actinide group separation with the aqueous-modified TALSPEAK process at pH 2. The amino acid buffer concentrations were reduced to 0.5 M (at pH 2) and separations were performed without any effect on phase transfer kinetics. Successful modeling of the aqueous-modified TALSPEAK process (p[H+] 1.6-3.1) using a simplified thermodynamic model and an internally consistent set of thermodynamic data is presented.« less

Chemical characterization of some aerobic liquids in CELSS

NASA Technical Reports Server (NTRS)

Madsen, Brooks C.

1993-01-01

Untreated aqueous soybean and wheat leachate and aerobically treated wheat leachate prepared from crop residues that are produced as a component of the Controlled Ecological Life Support System program designed to support long duration space missions were compared, and a general chemical characterization was accomplished. Solid phase extraction and high performance liquid chromatography were used to accomplish comparisons based on chromatographic and ultraviolet absorption properties of the components that are present. Specific compounds were not identified; however, general composition related to the initial presence of phenol-like compounds and their disappearance during aerobic treatment was explored.

A New Parameterization of H2SO4/H2O Aerosol Composition: Atmospheric Implications

NASA Technical Reports Server (NTRS)

Tabazadeh, Azadeh; Toon, Owen B.; Clegg, Simon L.; Hamill, Patrick

1997-01-01

Recent results from a thermodynamic model of aqueous sulfuric acid are used to derive a new parameterization for the variation of sulfuric acid aerosol composition with temperature and relative humidity. This formulation is valid for relative humidities above 1 % in the temperature range of 185 to 260 K. An expression for calculating the vapor pressure of supercooled liquid water, consistent with the sulfuric acid model, is also presented. We show that the Steele and Hamill [1981] formulation underestimates the water partial pressure over aqueous H2SOI solutions by up to 12% at low temperatures. This difference results in a corresponding underestimate of the H2SO4 concentration in the aerosol by about 6 % of the weight percent at approximately 190 K. In addition, the relation commonly used for estimating the vapor pressure of H2O over supercooled liquid water differs by up to 10 % from our derived expression. The combined error can result in a 20 % underestimation of water activity over a H2SO4 solution droplet in the stratosphere, which has implications for the parameterization of heterogeneous reaction rates in stratospheric sulfuric acid aerosols. The influence of aerosol composition on the rate of homogeneous ice nucleation from a H2SO4 solution droplet is also discussed. This parameterization can also be used for homogeneous gas phase nucleation calculations of H2SO4 solution droplets under various environmental conditions such as in aircraft exhaust or in volcanic plumes.

SOLVENT EXTRACTION PROCESS FOR SEPARATING ACTINIDE AND LANTHANIDE METAL VALUES

DOEpatents

Hildebrandt, R.A.; Hyman, H.H.; Vogler, S.

1962-08-14

A process of countercurrently extracting an aqueous mineral acid feed solution for the separation of actinides from lanthanides dissolved therern is described. The feed solution is made acid-defrcient with alkali metal hydroxide prior to.contact with acid extractant; during extraction, however, acid is transferred from organic to aqueous solution and the aqueous solution gradually becomes acid. The acid-deficient phase ' of the process promotes the extraction of the actinides, while the latter acid phase'' of the process improves retention of the lanthanides in the aqueous solution. This provides for an improved separation. (AEC)

Separation of uranium from technetium in recovery of spent nuclear fuel

DOEpatents

Pruett, D.J.; McTaggart, D.R.

1983-08-31

Uranium and technetium in the product stream of the Purex process for recovery of uranium in spent nuclear fuel are separated by (1) contacting the aqueous Purex product stream with hydrazine to reduce Tc/sup +7/ therein to a reduced species, and (2) contacting said aqueous stream with an organic phase containing tributyl phosphate and an organic diluent to extract uranium from said aqueous stream into said organic phase.

Separation of uranium from technetium in recovery of spent nuclear fuel

DOEpatents

Pruett, David J.; McTaggart, Donald R.

1984-01-01

Uranium and technetium in the product stream of the Purex process for recovery of uranium in spent nuclear fuel are separated by (1) contacting the aqueous Purex product stream with hydrazine to reduce Tc.sup.+7 therein to a reduced species, and (2) contacting said aqueous stream with an organic phase containing tributyl phosphate and an organic diluent to extract uranium from said aqueous stream into said organic phase.

EXTRACTION OF URANYL NITRATE FROM AQUEOUS SOLUTIONS

DOEpatents

Furman, N.H.; Mundy, R.J.

1957-12-10

An improvement in the process is described for extracting aqueous uranyl nitrate solutions with an organic solvent such as ether. It has been found that the organic phase will extract a larger quantity of uranyl nitrate if the aqueous phase contains in addition to the uranyl nitrate, a quantity of some other soluble nitrate to act as a salting out agent. Mentioned as suitable are the nitrates of lithium, calcium, zinc, bivalent copper, and trivalent iron.

[Phase transfer catalyzed bioconversion of penicillin G to 6-APA by immobilized penicillin acylase in recyclable aqueous two-phase systems with light/pH sensitive copolymers].

PubMed

Jin, Ke-ming; Cao, Xue-jun; Su, Jin; Ma, Li; Zhuang, Ying-ping; Chu, Ju; Zhang, Si-liang

2008-03-01

Immobilized penicillin acylase was used for bioconversion of penicillin PG into 6-APA in aqueous two-phase systems consisting of a light-sensitive polymer PNBC and a pH-sensitive polymer PADB. Partition coefficients of 6-APA was found to be about 5.78 in the presence of 1% NaCl. Enzyme kinetics showed that the reaction reached equilibrium at roughly 7 h. The 6-APA mole yields were 85.3% (pH 7.8, 20 degrees C), with about 20% increment as compared with the reaction of single aqueous phase buffer. The partition coefficient of PG (Na) varied scarcely, while that of the product, 6-APA and phenylacetic acid (PA) significantly varied due to Donnan effect of the phase systems and hydrophobicity of the products. The variation of the partition coefficients of the products also affected the bioconversion yield of the products. In the aqueous two-phase systems, the substrate, PG, the products of 6-APA and PA were biased in the top phase, while immobilized penicillin acylase at completely partitioned at the bottom. The substrate and PG entered the bottom phase, where it was catalyzed into 6-APA and PA and entered the top phase. Inhibition of the substrate and products was removed to result in improvement of the product yield, and the immobilized enzyme showed higher efficiency than the immobilized cells and occupied smaller volume. Compared with the free enzyme, immobilized enzyme had greater stability, longer life-time, and was completely partitioned in the bottom phase and recycle. Bioconversion in two-phase systems using immobilized penicillin acylase showed outstanding advantage. The light-sensitive copolymer forming aqueous two-phase systems could be recovered by laser radiation at 488 nm or filtered 450 nm light, while pH-sensitive polymer PADB could be recovered at the isoelectric point (pH 4.1). The recovery of the two copolymers was between 95% and 99%.

The role of hydrothermally prepared supported photocatalytic composite in organic micro-pollutants removal from the water.

PubMed

Shivaraju, H P; Byrappa, K

2012-07-01

This work deals with the non-biodegradable micro-pollutants degradation by supported photocatalyst based heterogeneous photocatalytic reaction. TiO2 based supported photocatalyst was prepared by the hydrothermal technique to improve the photocatalytic performance along with easy recovery of suspended photocatalyst from aqueous medium after photoreaction. TO2 deposited calcium alumino-silicate beads (CASB) supports were prepared under mild hydrothermal conditions (Temparature-200 degrees C, Duration-24 h). In the present study, industrial dyes such as Amaranth and Brilliant Yellow were used as model micro-pollutants in aqueous solution. A real time pesticide industrial effluent was tested for its photocatalytic removal of organic pollutants using TO2 deposited CASB supported photocatalytic composite as an effective photocatalyst. Photocatalytic degradation of micro-pollutants present in aqueous medium was carried out in a batch photoreactor, at atmospheric pressure and temperature (28 degrees C). The influence of different light sources, irradiation time, catalyst load and catalytic performance is discussed. The photocatalytic degradation of micro-pollutants in aqueous medium was evaluated by determination of COD and %T. Easy separation and recovery of suspended photocatalysts from aqueous solution is the major advantage of hydrothermally prepared supported photocatalytic composite.

Characteristics of biochar: Microchemical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amonette, James E.; Joseph, Stephen

2009-03-13

Biochars, being derived from a variety of biological feedstocks that have been thermally degraded under a range of conditions, exhibit a correspondingly large range in composition and chemistry. Due in part to the somewhat chaotic nature of the thermal process itself, this chemical heterogeneity extends to the microscopic scale even within a single biochar. Thus, in the strictest sense, each biochar made under a particular feedstock/process combination presents a unique mixture of phases and microenvironments that gives rise to a unique set of chemical properties. In some respects, the chemical complexity of biochars rivals that of incipient soils. In thismore » chapter we focus on the chemical complexity of biochar as manifested primarily at a microscopic and molecular scale. We start by describing the biochar-formation process and how this influences the composition and nature of the solid phases, entrained oils, and their organization at the microscopic level. We then proceed to discuss the range of surface chemistries exhibited by biochars in terms of functional groups and electrochemical properties. We conclude with a discussion of the influence of these properties on the sorption of aqueous species at biochar surfaces.« less

Dense Nonaqueous Phase Liquids at Former Manufactured Gas Plants: Challenges to Modeling and Remediation

PubMed Central

Birak, P.S.; Miller, C.T.

2008-01-01

The remediation of dense non-aqueous phase liquids (DNAPLs) in porous media continues to be one of the most challenging problems facing environmental scientists and engineers. Of all the environmentally relevant DNAPLs, tars in the subsurface at former manufactured gas plants (FMGP’s) pose one of the biggest challenges due to their complex chemical composition and tendency to alter wettability. To further our understanding of these complex materials, we consulted historic documentation to evaluate the impact of gas manufacturing on the composition and physicochemical nature of the resulting tars. In the recent literature, most work to date has been focused in a relatively narrow portion of the expected range of tar materials, which has yielded a bias toward samples of relatively low viscosity and density. In this work, we consider the dissolution and movement of tars in the subsurface, models used to predict these phenomena, and approaches used for remediation. We also explore the open issues and detail important gaps in our fundamental understanding of these extraordinarily complex systems that must be resolved to reach a mature level of understanding. PMID:19176266

An approach for upgrading biomass and pyrolysis product quality using a combination of aqueous phase bio-oil washing and torrefaction pretreatment.

PubMed

Chen, Dengyu; Cen, Kehui; Jing, Xichun; Gao, Jinghui; Li, Chen; Ma, Zhongqing

2017-06-01

Bio-oil undergoes phase separation because of poor stability. Practical application of aqueous phase bio-oil is challenging. In this study, a novel approach that combines aqueous phase bio-oil washing and torrefaction pretreatment was used to upgrade the biomass and pyrolysis product quality. The effects of individual and combined pretreatments on cotton stalk pyrolysis were studied using TG-FTIR and a fixed bed reactor. The results showed that the aqueous phase bio-oil washing pretreatment removed metals and resolved the two pyrolysis peaks in the DTG curve. Importantly, it increased the bio-oil yield and improved the pyrolysis product quality. For example, the water and acid content of bio-oil decreased significantly along with an increase in phenol formation, and the heating value of non-condensable gases improved, and these were more pronounced when combined with torrefaction pretreatment. Therefore, the combined pretreatment is a promising method, which would contribute to the development of polygeneration pyrolysis technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Management of the diffusion of 4-methylumbelliferone across phases in microdroplet-based systems for in vitro protein evolution.

PubMed

Wu, Nan; Courtois, Fabienne; Zhu, Yonggang; Oakeshott, John; Easton, Chris; Abell, Chris

2010-09-01

Fluorongenic reagents based on 4-methylumbelliferone (4-MU) have been widely used for the detection of phosphatase, sulfatase, esterase, lipase and glycosidase activities in conventionally formatted enzyme assay systems. However, the sensitivity of assays based on these substrates is also potentially very useful in the microdroplet formats now being developed for high throughput in vitro evolution experiments. In this article, we report the investigation of diffusion of 4-MU as a model dye from water-in-oil droplets and the internal aqueous phase of water-in-oil-in-water droplets in microfluidics. The effect of BSA in the aqueous phase on the diffusion of 4-MU is also discussed. Based on these results, we provided here proof-of-concept of the reaction of the enzyme OpdA with the substrate coumaphos in water-in-oil-in-water droplets. In this double-emulsion system, the reaction of OpdA and coumaphos was achieved by allowing coumaphos to diffuse from the continuous aqueous phase across the oil phase into the internal aqueous droplets.

Recovery of Picloram and 2,4-Dichlorophenoxyacetic Acid from Aqueous Samples by Reversed-Phase Solid-Phase Extraction

Treesearch

Martha J.M. Wells; Jerry L. Michael

1987-01-01

Extensive preparation of samples before chromatographic analysis is usually the most time-consuming process in the determination of many organic compounds in environmental matrices. In the past, removal of some organic from aqueous solution was commonly done by liquid/liquid extraction. However, the introduction of stable, covalently bonded reversed-phase sorbents now...

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1998-01-01

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casella, Amanda J.; Hylden, Laura R.; Campbell, Emily L.

Knowledge of real-time solution properties and composition is a necessity for any spent nuclear fuel reprocessing method. Metal-ligand speciation in aqueous solutions derived from the dissolved commercial spent fuel is highly dependent upon the acid concentration/pH, which influences extraction efficiency and the resulting speciation in the organic phase. Spectroscopic process monitoring capabilities, incorporated in a counter current centrifugal contactor bank, provide a pathway for on-line real-time measurement of solution pH. The spectroscopic techniques are process-friendly and can be easily configured for on-line applications, while classic potentiometric pH measurements require frequent calibration/maintenance and have poor long-term stability in aggressive chemical andmore » radiation environments. Our research is focused on developing a general method for on-line determination of pH of aqueous solutions through chemometric analysis of Raman spectra. Interpretive quantitative models have been developed and validated under the range of chemical composition and pH using a lactic acid/lactate buffer system. The developed model was applied to spectra obtained on-line during solvent extractions performed in a centrifugal contactor bank. The model predicted the pH within 11% for pH > 2, thus demonstrating that this technique could provide the capability of monitoring pH on-line in applications such as nuclear fuel reprocessing.« less

Phytochemical Composition, Antioxidant Activity, and the Effect of the Aqueous Extract of Coffee (Coffea arabica L.) Bean Residual Press Cake on the Skin Wound Healing.

PubMed

Affonso, Regina Celis Lopes; Voytena, Ana Paula Lorenzen; Fanan, Simone; Pitz, Heloísa; Coelho, Daniela Sousa; Horstmann, Ana Luiza; Pereira, Aline; Uarrota, Virgílio Gavicho; Hillmann, Maria Clara; Varela, Lucas Andre Calbusch; Ribeiro-do-Valle, Rosa Maria; Maraschin, Marcelo

2016-01-01

The world coffee consumption has been growing for its appreciated taste and its beneficial effects on health. The residual biomass of coffee, originated in the food industry after oil extraction from coffee beans, called coffee beans residual press cake, has attracted interest as a source of compounds with antioxidant activity. This study investigated the chemical composition of aqueous extracts of coffee beans residual press cake (AE), their antioxidant activity, and the effect of topical application on the skin wound healing, in animal model, of hydrogels containing the AE, chlorogenic acid (CGA), allantoin (positive control), and carbopol (negative control). The treatments' performance was compared by measuring the reduction of the wound area, with superior result ( p < 0.05) for the green coffee AE (78.20%) with respect to roasted coffee AE (53.71%), allantoin (70.83%), and carbopol (23.56%). CGA hydrogels reduced significantly the wound area size on the inflammatory phase, which may be associated with the well known antioxidant and anti-inflammatory actions of that compound. The topic use of the coffee AE studied improved the skin wound healing and points to an interesting biotechnological application of the coffee bean residual press cake.

Phytochemical Composition, Antioxidant Activity, and the Effect of the Aqueous Extract of Coffee (Coffea arabica L.) Bean Residual Press Cake on the Skin Wound Healing

PubMed Central

Voytena, Ana Paula Lorenzen; Fanan, Simone; Pitz, Heloísa; Coelho, Daniela Sousa; Horstmann, Ana Luiza; Pereira, Aline; Uarrota, Virgílio Gavicho; Hillmann, Maria Clara; Varela, Lucas Andre Calbusch; Ribeiro-do-Valle, Rosa Maria; Maraschin, Marcelo

2016-01-01

The world coffee consumption has been growing for its appreciated taste and its beneficial effects on health. The residual biomass of coffee, originated in the food industry after oil extraction from coffee beans, called coffee beans residual press cake, has attracted interest as a source of compounds with antioxidant activity. This study investigated the chemical composition of aqueous extracts of coffee beans residual press cake (AE), their antioxidant activity, and the effect of topical application on the skin wound healing, in animal model, of hydrogels containing the AE, chlorogenic acid (CGA), allantoin (positive control), and carbopol (negative control). The treatments' performance was compared by measuring the reduction of the wound area, with superior result (p < 0.05) for the green coffee AE (78.20%) with respect to roasted coffee AE (53.71%), allantoin (70.83%), and carbopol (23.56%). CGA hydrogels reduced significantly the wound area size on the inflammatory phase, which may be associated with the well known antioxidant and anti-inflammatory actions of that compound. The topic use of the coffee AE studied improved the skin wound healing and points to an interesting biotechnological application of the coffee bean residual press cake. PMID:27965732

Electrospray surface-enhanced Raman spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles

NASA Astrophysics Data System (ADS)

Gen, Masao; Chan, Chak K.

2017-11-01

We present electrospray surface-enhanced Raman spectroscopy (ES-SERS) as a new approach to measuring the surface chemical compositions of atmospherically relevant particles. The surface-sensitive SERS is realized by electrospraying Ag nanoparticle aerosols over analyte particles. Spectral features at v(SO42-), v(C-H) and v(O-H) modes were observed from the normal Raman and SERS measurements of laboratory-generated supermicron particles of ammonium sulfate (AS), AS mixed with succinic acid (AS / SA) and AS mixed with sucrose (AS / sucrose). SERS measurements showed strong interaction (or chemisorption) between Ag nanoparticles and surface aqueous sulfate [SO42-] with [SO42-]AS / sucrose > [SO42-]AS / SA > [SO42-]AS. Enhanced spectra of the solid AS and AS / SA particles revealed the formation of surface-adsorbed water on their surfaces at 60 % relative humidity. These observations of surface aqueous sulfate and adsorbed water demonstrate a possible role of surface-adsorbed water in facilitating the dissolution of sulfate from the bulk phase into its water layer(s). Submicron ambient aerosol particles collected in Hong Kong exhibited non-enhanced features of black carbon and enhanced features of sulfate and organic matter (carbonyl group), indicating an enrichment of sulfate and organic matter on the particle surface.

Functional and surface-active membranes from poly(vinylidene fluoride)-graft-poly(acrylic acid) prepared via RAFT-mediated graft copolymerization.

PubMed

Ying, L; Yu, W H; Kang, E T; Neoh, K G

2004-07-06

Poly (vinylidene fluoride) (PVDF) with "living" poly (acrylic acid) (PAAc) side chains (PVDF-g-PAAc) was prepared by reversible addition-fragmentation chain transfer (RAFT)-mediated graft copolymerization of acrylic acid (AAc) with the ozone-pretreated PVDF. The chemical composition and structure of the copolymers were characterized by elemental analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The copolymer could be readily cast into pH-sensitive microfiltration (MF) membranes with enriched living PAAc graft chains on the surface (including the pore surfaces) by phase inversion in an aqueous medium. The surface composition of the membranes was determined by X-ray photoelectron spectroscopy. The morphology of the membranes was characterized by scanning electron microscopy. The pore size distribution of the membranes was found to be much more uniform than that of the corresponding membranes cast from PVDF-g-PAAc prepared by the "conventional" free-radical graft copolymerization process. Most important of all, the MF membranes with surface-tethered PAAc macro chain transfer agents, or the living membrane surfaces, could be further functionalized via surface-initiated block copolymerization with N-isopropylacrylamide (NIPAAM) to obtain the PVDF-g-PAAc-b-PNIPAAM MF membranes, which exhibited both pH- and temperature-dependent permeability to aqueous media.

Development of continuous dispersive liquid-liquid microextraction performed in home-made device for extraction and preconcentration of aryloxyphenoxy-propionate herbicides from aqueous samples followed by gas chromatography-flame ionization detection.

PubMed

Farajzadeh, Mir Ali; Mohebbi, Ali; Feriduni, Behruz

2016-05-12

In this study, a rapid, simple, and efficient sample preparation method based on continuous dispersive liquid-liquid microextraction has been developed for the extraction and preconcentration of aryloxyphenoxy-propionate herbicides from aqueous samples prior to their analysis by gas chromatography-flame ionization detection. In this method, two parallel glass tubes with different diameters are connected with a teflon stopcock and used as an extraction device. A mixture of disperser and extraction solvents is transferred into one side (narrow tube) of the extraction device and an aqueous phase containing the analytes is filled into the other side (wide tube). Then the stopcock is opened and the mixture of disperser and extraction solvents mixes with the aqueous phase. By this action, the extraction solvent is dispersed continuously as fine droplets into the aqueous sample and the target analytes are extracted into the fine droplets of the extraction solvent. The fine droplets move up through the aqueous phase due to its low density compared to aqueous phase and collect on the surface of the aqueous phase as an organic layer. Finally an aliquot of the organic phase is removed and injected into the separation system for analysis. Several parameters that can affect extraction efficiency including type and volume of extraction and disperser solvents, sample pH, and ionic strength were investigated and optimized. Under the optimum extraction conditions, the extraction recoveries and enrichment factors ranged from 49 to 74% and 1633 to 2466, respectively. Relative standard deviations were in the ranges of 3-6% (n = 6, C = 30 μg L(-1)) for intra-day and 4-7% (n = 4, C = 30 μg L(-1)) for inter-day precisions. The limits of detection were in the range of 0.20-0.86 μg L(-1). Finally the proposed method was successfully applied to determine the target herbicides in fruit juice and vegetable samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of carbon nanotubes modified with a Keggin polyoxometalate as a new sorbent for the hollow-fiber micro-solid-phase extraction of trace naproxen in hair samples with fluorescence spectrophotometry using factorial experimental design.

PubMed

Naddaf, Ezzat; Ebrahimi, Mahmoud; Es'haghi, Zarrin; Bamoharram, Fatemeh Farrash

2015-07-01

A sensitive technique to determinate naproxen in hair samples was developed using hollow-fiber micro-solid-phase combined with fluorescence spectrophotometry. The incorporation of multi-walled carbon nanotubes modified with a Keggin polyoxometalate into a silica matrix prepared by the sol-gel method was reported. In this research, the Keggin carbon nanotubes /silica composite was used in the pores and lumen of a hollow fiber as the hollow-fiber micro-solid-phase extraction device. The device was used for the microextraction of the analyte from hair and water samples under the optimized conditions. An orthogonal array experimental design with an OA24 (4(6) ) matrix was employed to optimize the conditions. The effect of six factors influencing the extraction efficiency was investigated: pH, salt, volume of donor and desorption phase, extraction and desorption time. The effect of each factor was estimated using individual contributions as response functions in the screening process. Analysis of variance was employed for estimating the main significant factors and their contributions in the extraction. Calibration curve plot displayed linearity over a range of 0.2-10 ng/mL with detection limits of 0.072 and 0.08 ng/mL for hair and aqueous samples, respectively. The relative recoveries in the hair and aqueous matrices ranged from 103-95%. The relative standard deviation for fiber-to-fiber repeatability was 3.9%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diffusion-based process for carbon dioxide uptake and isoprene emission in gaseous/aqueous two-phase photobioreactors by photosynthetic microorganisms.

PubMed

Bentley, Fiona K; Melis, Anastasios

2012-01-01

Photosynthesis for the generation of fuels and chemicals from cyanobacteria and microalgae offers the promise of a single host organism acting both as photocatalyst and processor, performing sunlight absorption and utilization, as well as CO(2) assimilation and conversion into product. However, there is a need to develop methods for generating, sequestering, and trapping such bio-products in an efficient and cost-effective manner that is suitable for industrial scale-up and exploitation. A sealed gaseous/aqueous two-phase photobioreactor was designed and applied for the photosynthetic generation of volatile isoprene (C(5)H(8)) hydrocarbons, which operates on the principle of spontaneous diffusion of CO(2) from the gaseous headspace into the microalgal or cyanobacterial-containing aqueous phase, followed by photosynthetic CO(2) assimilation and isoprene production by the transgenic microorganisms. Volatile isoprene hydrocarbons were emitted from the aqueous phase and were sequestered into the gaseous headspace. Periodic replacement (flushing) of the isoprene (C(5)H(8)) and oxygen (O(2)) content of the gaseous headspace with CO(2) allowed for the simultaneous harvesting of the photoproducts and replenishment of the CO(2) supply in the gaseous headspace. Reduction in practice of the gaseous/aqueous two-phase photobioreactor is offered in this work with a fed-batch and a semi-continuous culturing system using Synechocystis sp. PCC 6803 heterologously expressing the Pueraria montana (kudzu) isoprene synthase (IspS) gene. Constitutive isoprene production was observed over 192 h of experimentation, coupled with cyanobacterial biomass accumulation. The diffusion-based process in gaseous/aqueous two-phase photobioreactors has the potential to be applied to other high-value photosynthetically derived volatile molecules, emanating from a variety of photosynthetic microorganisms. Copyright © 2011 Wiley Periodicals, Inc.

Sherwood correlation for dissolution of pooled NAPL in porous media

NASA Astrophysics Data System (ADS)

Aydin Sarikurt, Derya; Gokdemir, Cagri; Copty, Nadim K.

2017-11-01

The rate of interphase mass transfer from non-aqueous phase liquids (NAPLs) entrapped in the subsurface into the surrounding mobile aqueous phase is commonly expressed in terms of Sherwood (Sh) correlations that are expressed as a function of flow and porous media properties. Because of the lack of precise methods for the estimation of the interfacial area separating the NAPL and aqueous phases, most studies have opted to use modified Sherwood expressions that lump the interfacial area into the interphase mass transfer coefficient. To date, there are only two studies in the literature that have developed non-lumped Sherwood correlations; however, these correlations have undergone limited validation. In this paper controlled dissolution experiments from pooled NAPL were conducted. The immobile NAPL mass is placed at the bottom of a flow cell filled with porous media with water flowing horizontally on top. Effluent aqueous phase concentrations were measured for a wide range of aqueous phase velocities and for two different porous media. To interpret the experimental results, a two-dimensional pore network model of the NAPL dissolution kinetics and aqueous phase transport was developed. The observed effluent concentrations were then used to compute best-fit mass transfer coefficients. Comparison of the effluent concentrations computed with the two-dimensional pore network model to those estimated with one-dimensional analytical solutions indicates that the analytical model which ignores the transport in the lateral direction can lead to under-estimation of the mass transfer coefficient. Based on system parameters and the estimated mass transfer coefficients, non-lumped Sherwood correlations were developed and compared to previously published data. The developed correlations, which are a significant improvement over currently available correlations that are associated with large uncertainties, can be incorporated into future modeling studies requiring non-lumped Sh expressions.

Oxidation of Organic Compoundsin the Atmospheric Aqueous Phase: Development of a New Explicit Oxidation Mechanism

NASA Astrophysics Data System (ADS)

Mouchel-Vallon, C.; Bregonzio-Rozier, L.; Monod, A.; Leriche, M.; Doussin, J. F.; Chaumerliac, N. M.; Deguillaume, L.

2014-12-01

Current 3D models tend to underestimate the production of secondary organic aerosol (SOA) in the atmosphere (Volkamer et al., 2006). Recent studies argue that aqueous chemistry in clouds could be responsible for a significant production of SOA (Ervens et al., 2011; Carlton and Turpin, 2013) through oxidative and non-oxidative processes. Aqueous phase reactivity of organic compounds needs to be thoroughly described in models to identify organic molecules available to contribute to SOA mass. Recently, new empirical methods have been developed to allow the estimate of HO·reaction rates in the aqueous phase (Doussin and Monod, 2013, Minakata et al., 2009). These methods provide global rate constants together with branching ratios for HO·abstraction and addition on organic compounds of atmospheric interests. Current cloud chemistry mechanisms do not take the different possible pathways into account. Based on these structure-activity relationships, a new detailed aqueous phase mechanism describing the oxidation of hydrosoluble organic compounds resulting from isoprene oxidation is proposed. This new aqueous phase mechanism is coupled with the detailed gas phase mechanism MCM v3.2 (Jenkin et al., 1997; Saunders et al., 2003) through a kinetic of mass transfer parameterization for the exchange between gas phase and aqueous phase. The GROMHE SAR (Raventos-Duran et al., 2010) allows the evaluation of Henry's law constants for organic compounds. Variable photolysis in both phases using the TUV 4.5 radiative transfer model (Madronich and Flocke, 1997) is also calculated. The resulting multiphase mechanism has been implemented in a cloud chemistry model. Focusing on oxygenated compounds produced from the isoprene oxidation, sensitivity tests and comparisons with multiphase experiments performed in the framework of the CUMULUS project in the CESAM atmospheric simulation chamber (Wang et al., 2011) will be presented. Volkamer et al., GRL, 33, L17811, 2006. Carlton and Turpin, ACP, 13, 10203-10214, 2013. Ervens et al., ACP, 11069-11102, 2011. Doussin and Monod, ACP, 13, 11625-11641, 2013. Minakata et al., EST, 45, 3479-3486, 2009. Jenkin et al., AE, 31, 81, 1997. Saunders et al., ACP, 3, 161, 2003. Raventos-Duran et al., ACP, 10, 7643-7654, 2010. Madronich and Flocke, 1997. Wang et al., AMT, 4, 2465-2494,2011.

A rapid and sensitive assay of perfluorocarboxylic acids in aqueous matrices by headspace solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry.

PubMed

Monteleone, Marcello; Naccarato, Attilio; Sindona, Giovanni; Tagarelli, Antonio

2012-08-17

The work aims at developing a rapid and sensitive method for the quantification of perfluorocarboxylic acids in aqueous matrices. The proposed analytical approach is based on the use of solid phase microextraction in headspace mode after a fast derivatization of the carboxylate function by propylchloroformate/propanol mixture. Several fibers were evaluated and the optimization of the parameters affecting the SPME process was carried out using a central composite design. The optimum working conditions in terms of response values were achieved by performing analysis with CAR/PDMS fiber at room temperature, without addition of NaCl, with a sample volume of 6 ml and an extraction time of 10 min. Assay of PFCAs was performed by using a gas chromatography-triple quadrupole mass spectrometry (GC-QqQ MS) system in negative chemical ionization mode with ammonia as reagent gas. An overall evaluation of all analytical parameters shows that the proposed method provides satisfactory results. In particular, the observed accuracies, ranging from 84.4% to 116.8%, and the RSD values in the range 0.4% and 14.5% confirm the effectiveness of the developed protocol in the assay of PFCAs content in aqueous matrices. Moreover, LOD and LOQ values ranging from 0.08 to 6.6 ng l(-1) and from 0.17 to 14.3 ng l(-1), respectively, can be considered very satisfactory. None of the compounds were detected in six samples of river collected in Calabria. Copyright © 2012 Elsevier B.V. All rights reserved.

pH Neutralization of Aqueous Bio-Oil from Switchgrass Intermediate Pyrolysis Using Process Intensification Devices

DOE PAGES

Park, Lydia Kyoung-Eun; Ren, Shoujie; Yiacoumi, Sotira; ...

2017-07-20

Despite the potential carbon-neutrality of switchgrass bio-oil, its high acidity and diverse chemical composition limit its utilization. The objectives of this research are to investigate pH neutralization of bio-oil by adding various alkali solutions in a batch system and then perform neutralization using process intensification devices, including a static mixer and a centrifugal contactor. The results indicate that sodium hydroxide and potassium hydroxide are more appropriate bases for pH neutralization of bio-oil than calcium hydroxide due to the limited solubility of calcium hydroxide in aqueous bio-oil. Mass and total acid number (TAN) balances were performed for both batch and continuous-flowmore » systems. Upon pH neutralization of bio-oil, the TAN values of the system increased after accounting the addition of alkali solution. A bio-oil heating experiment showed that the heat generated during pH neutralization did not cause a significant increase in the acidity of bio-oil. The formation of phenolic compounds during neutralization was initially suspected of increasing the system’s overall TAN value because some of these compounds (e.g., vanillic acid) act as polyprotic acids and have a stronger influence on the TAN value than monoprotic acids (e.g., acetic acid). The amount of phenolics in separated bio-oil phases, however, did not change significantly after pH neutralization. In conclusion, process intensification devices provided sufficient mixing and separation of the organic and aqueous phases, suggesting a scale-up route for the bio-oil pH neutralization process.« less

pH Neutralization of Aqueous Bio-Oil from Switchgrass Intermediate Pyrolysis Using Process Intensification Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Lydia Kyoung-Eun; Ren, Shoujie; Yiacoumi, Sotira

Despite the potential carbon-neutrality of switchgrass bio-oil, its high acidity and diverse chemical composition limit its utilization. The objectives of this research are to investigate pH neutralization of bio-oil by adding various alkali solutions in a batch system and then perform neutralization using process intensification devices, including a static mixer and a centrifugal contactor. The results indicate that sodium hydroxide and potassium hydroxide are more appropriate bases for pH neutralization of bio-oil than calcium hydroxide due to the limited solubility of calcium hydroxide in aqueous bio-oil. Mass and total acid number (TAN) balances were performed for both batch and continuous-flowmore » systems. Upon pH neutralization of bio-oil, the TAN values of the system increased after accounting the addition of alkali solution. A bio-oil heating experiment showed that the heat generated during pH neutralization did not cause a significant increase in the acidity of bio-oil. The formation of phenolic compounds during neutralization was initially suspected of increasing the system’s overall TAN value because some of these compounds (e.g., vanillic acid) act as polyprotic acids and have a stronger influence on the TAN value than monoprotic acids (e.g., acetic acid). The amount of phenolics in separated bio-oil phases, however, did not change significantly after pH neutralization. In conclusion, process intensification devices provided sufficient mixing and separation of the organic and aqueous phases, suggesting a scale-up route for the bio-oil pH neutralization process.« less

Secondary Organic Aerosol Produced from Aqueous Reactions of Phenols in Fog Drops and Deliquesced Particles

NASA Astrophysics Data System (ADS)

Smith, J.; Anastasio, C.

2014-12-01

The formation and evolution of secondary organic aerosol (SOA) in atmospheric condensed phases (i.e., aqueous SOA) can proceed rapidly, but relatively little is known of the important aqueous SOA precursors or their reaction pathways. In our work we are studying the aqueous SOA formed from reactions of phenols (phenol, guaiacol, and syringol), benzene-diols (catechol, resorcinol, and hydroquinone), and phenolic carbonyls (e.g., vanillin and syringaldehyde). These species are potentially important aqueous SOA precursors because they are released in large quantities from biomass burning, have high Henry's Law constants (KH = 103 -109 M-1 atm-1) and are rapidly oxidized. To evaluate the importance of aqueous reactions of phenols as a source of SOA, we first quantified the kinetics and SOA mass yields for 11 phenols reacting via direct photodegradation, hydroxyl radical (•OH), and with an excited organic triplet state (3C*). In the second step, which is the focus of this work, we use these laboratory results in a simple model of fog chemistry using conditions during a previously reported heavy biomass burning event in Bakersfield, CA. Our calculations indicate that under aqueous aerosol conditions (i.e., a liquid water content of 100 μg m-3) the rate of aqueous SOA production (RSOA(aq)) from phenols is similar to the rate in the gas phase. In contrast, under fog/cloud conditions the aqueous RSOA from phenols is 10 times higher than the rate in the gas phase. In both of these cases aqueous RSOA is dominated by the oxidation of phenols by 3C*, followed by direct photodegradation of phenolic carbonyls, and then •OH oxidation. Our results suggest that aqueous oxidation of phenols is a significant source of SOA during fog events and also during times when deliquesced aerosols are present.

Design of Phosphonium-Type Zwitterion as an Additive to Improve Saturated Water Content of Phase-Separated Ionic Liquid from Aqueous Phase toward Reversible Extraction of Proteins

PubMed Central

Ito, Yoritsugu; Kohno, Yuki; Nakamura, Nobuhumi; Ohno, Hiroyuki

2013-01-01

We designed phosphonium-type zwitterion (ZI) to control the saturated water content of separated ionic liquid (IL) phase in the hydrophobic IL/water biphasic systems. The saturated water content of separated IL phase, 1-butyl-3-methyimidazolium bis(trifluoromethanesulfonyl)imide, was considerably improved from 0.4 wt% to 62.8 wt% by adding N,N,N-tripentyl-4-sulfonyl-1-butanephosphonium-type ZI (P555C4S). In addition, the maximum water content decreased from 62.8 wt% to 34.1 wt% by increasing KH2PO4/K2HPO4 salt content in upper aqueous phosphate buffer phase. Horse heart cytochrome c (cyt.c) was dissolved selectively in IL phase by improving the water content of IL phase, and spectroscopic analysis revealed that the dissolved cyt.c retained its higher ordered structure. Furthermore, cyt. c dissolved in IL phase was re-extracted again from IL phase to aqueous phase by increasing the concentration of inorganic salts of the buffer solution. PMID:24013379

Spectral changes induced by pH variation of aqueous extracts derived from biomass burning aerosols: Under dark and in presence of simulated sunlight irradiation

NASA Astrophysics Data System (ADS)

Cai, Jing; Zhi, Guorui; Yu, Zhiqiang; Nie, Peng; Gligorovski, Sasho; Zhang, Yuzhe; Zhu, Like; Guo, Xixiang; Li, Pei; He, Tan; He, Youjiang; Sun, Jianzhong; Zhang, Yang

2018-07-01

Water soluble organic carbon (WSOC) can significantly influence the aerosol optical properties and the aqueous phase chemistry in cloudwater, fogwater and aerosol liquid water. Here, we examine how the changing pH (in acidic range) affects the absorption spectra of aqueous extracts from field biomass burning aerosols, under dark conditions and in presence of simulated sunlight illumination. The observation under dark conditions indicates that pH variation from 2 to 5 induces significantly enhanced light absorbance in the wavelength ranges of 235-270 nm and 300-550 nm, whereas the light absorbance decreased in the range of 270-300 nm, which might be partially ascribed to the deprotonation of carboxylic acids and phenols. During the extract photolysis, light absorption exhibits photo-bleaching below 380 nm and photo-enhancement above 380 nm, indicating that at acidic levels (pH = 2-5), the particle extracts could undergo a significant composition evolution leading to a modification of absorptive properties. Meanwhile, after 12 h-photolysis, the acidity ([H+]) normalized by WSOC concentration in aqueous extracts ([WSOCae]) increased with a variation of Δ[H+]/[WSOCae]=(3.7 ± 0.7) × 10-7 mol mgC-1 (mean ± standard deviation), suggesting the formation of new acidic substances. Although these findings were acquired in aqueous solutions more relevant to cloud and fog water, the similar evolution likely occurs in wetted aerosols. This calls more attention to the effect of acidity on the wetted aerosols in order to better estimate the aerosol radiative forcing.

Molecular Dynamics Study of the Solution Structure, Clustering, and Diffusion of Four Aqueous Alkanolamines.

PubMed

Melnikov, Sergey M; Stein, Matthias

2018-03-15

CO 2 sequestration from anthropogenic resources is a challenge to the design of environmental processes at a large scale. Reversible chemical absorption by amine-based solvents is one of the most efficient methods of CO 2 removal. Molecular simulation techniques are very useful tools to investigate CO 2 binding by aqueous alkanolamine molecules for further technological application. In the present work, we have performed detailed atomistic molecular dynamics simulations of aqueous solutions of three prototype amines: monoethanolamine (MEA) as a standard, 3-aminopropanol (MPA), 2-methylaminoethanol (MMEA), and 4-diethylamino-2-butanol (DEAB) as potential novel CO 2 absorptive solvents. Solvent densities, radial distribution functions, cluster size distributions, hydrogen-bonding statistics, and diffusion coefficients for a full range of mixture compositions have been obtained. The solvent densities and diffusion coefficients from simulations are in good agreement with those in the experiment. In aqueous solution, MEA, MPA, and MMEA molecules prefer to be fully solvated by water molecules, whereas DEAB molecules tend to self-aggregate. In a range from 30/70-50/50 (w/w) alkanolamine/water mixtures, they form a bicontinuous phase (both alkanolamine and water are organized in two mutually percolating clusters). Among the studied aqueous alkanolamine solutions, the diffusion coefficients decrease in the following order MEA > MPA = MMEA > DEAB. With an increase of water content, the diffusion coefficients increase for all studied alkanolamines. The presented results are a first step for process-scale simulation and provide important qualitative and quantitative information for the design and engineering of efficient new CO 2 removal processes.

Optimizing Low-Concentration Mercury Removal from Aqueous Solutions by Reduced Graphene Oxide-Supported Fe3O4 Composites with the Aid of an Artificial Neural Network and Genetic Algorithm

PubMed Central

Cao, Rensheng; Hu, Jiwei; Ruan, Wenqian; Xiong, Kangning; Wei, Xionghui

2017-01-01

Reduced graphene oxide-supported Fe3O4 (Fe3O4/rGO) composites were applied in this study to remove low-concentration mercury from aqueous solutions with the aid of an artificial neural network (ANN) modeling and genetic algorithm (GA) optimization. The Fe3O4/rGO composites were prepared by the solvothermal method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), N2-sorption, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and superconduction quantum interference device (SQUID). Response surface methodology (RSM) and ANN were employed to model the effects of different operating conditions (temperature, initial pH, initial Hg ion concentration and contact time) on the removal of the low-concentration mercury from aqueous solutions by the Fe3O4/rGO composites. The ANN-GA model results (with a prediction error below 5%) show better agreement with the experimental data than the RSM model results (with a prediction error below 10%). The removal process of the low-concentration mercury obeyed the Freudlich isotherm and the pseudo-second-order kinetic model. In addition, a regeneration experiment of the Fe3O4/rGO composites demonstrated that these composites can be reused for the removal of low-concentration mercury from aqueous solutions. PMID:29112141

Tamoxifen-loaded lecithin organogel (LO) for topical application: Development, optimization and characterization.

PubMed

Bhatia, Amit; Singh, Bhupinder; Raza, Kaisar; Wadhwa, Sheetu; Katare, Om Prakash

2013-02-28

Lecithin organogels (LOs) are semi-solid systems with immobilized organic liquid phase in 3-D network of self-assembled gelators. This paper attempts to study the various attributes of LOs, starting from selection of materials, optimization of influential components to LO specific characterization. After screening of various components (type of gelators, organic and aqueous phase) and construction of phase diagrams, a D-optimal mixture design was employed for the systematic optimization of the LO composition. The response surface plots were constructed for various response variables, viz. viscosity, gel strength, spreadability and consistency index. The optimized LO composition was searched employing overlay plots. Subsequent validation of the optimization study employing check-point formulations, located using grid search, indicated high degree of prognostic ability of the experimental design. The optimized formulation was characterized for morphology, drug content, rheology, spreadability, pH, phase transition temperatures, and physical and chemical stability. The outcomes of the study were interesting showing high dependence of LO attributes on the type and amount of phospholipid, Poloxamer™, auxillary gelators and organic solvent. The optimized LO was found to be quite stable, easily applicable and biocompatible. The findings of the study can be utilized for the development of LO systems of other drugs for the safer and effective topical delivery. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

OPTIMIZING MODEL PERFORMANCE: VARIABLE SIZE RESOLUTION IN CLOUD CHEMISTRY MODELING. (R826371C005)

EPA Science Inventory

Under many conditions size-resolved aqueous-phase chemistry models predict higher sulfate production rates than comparable bulk aqueous-phase models. However, there are special circumstances under which bulk and size-resolved models offer similar predictions. These special con...

Jacob Kruger | NREL

Science.gov Websites

Jacob.Kruger@nrel.gov | 303-275-4081 Research Interests Algal growth systems targeting high-efficiency Hydrotalcite Catalysts," ACS Catalysis (2016) "Aqueous-Phase Fructose Dehydration Using Brønsted ) "Elucidating the Roles of Zeolite H-BEA in Aqueous-Phase Fructose Dehydration and HMF Rehydration

EVALUATION OF TECHNOLOGIES FOR IN SITU CLEANUP OF DNAPL CONTAMINATED SITES

EPA Science Inventory

Ground water contamination by non-aqueous phase liquids poses one of the greatest remedial challenges in the field of environmental engineering. Denser-than-water non-aqueous phase liquids (DNAPLs) are especially problematic due to their low water solubility, high density, an...

Separation by solvent extraction

DOEpatents

Holt, Jr., Charles H.

1976-04-06

17. A process for separating fission product values from uranium and plutonium values contained in an aqueous solution, comprising adding an oxidizing agent to said solution to secure uranium and plutonium in their hexavalent state; contacting said aqueous solution with a substantially water-immiscible organic solvent while agitating and maintaining the temperature at from -1.degree. to -2.degree. C. until the major part of the water present is frozen; continuously separating a solid ice phase as it is formed; separating a remaining aqueous liquid phase containing fission product values and a solvent phase containing plutonium and uranium values from each other; melting at least the last obtained part of said ice phase and adding it to said separated liquid phase; and treating the resulting liquid with a new supply of solvent whereby it is practically depleted of uranium and plutonium.

Impact of biochemical composition on susceptibility of algal biomass to acid-catalyzed pretreatment for sugar and lipid recovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Tao; Van Wychen, Stefanie; Nagle, Nick

One of the major challenges associated with algal biofuels production in a biorefinery-type setting is improving biomass utilization in its entirety, increasing the process energetic yields and providing economically viable and scalable co-product concepts. We focus on the impact of compositional characteristics of biomass on the susceptibility to pretreatment in order to maximize the valorization of algal biomass conversion for biofuels and bioproducts. The release of monomeric carbohydrates in the aqueous phase and extractability of the lipid fraction was measured based a response surface methodology to find significant explanatory variables and interaction terms. We studied the effect of harvest timingmore » on the conversion yields, using three algal strains; Chlorella vulgaris and Scenedesmus acutus and Nannochloropsis granulata representing three different nutritional metabolic phases. Four cultivation conditions of high (≥ 90 gallon gasoline equivalent/ton biomass) value for a combined sugar- and lipid-based biofuels process were identified. These four conditions represent either mid or late stage harvest cultivation regimes. Lastly, the results indicate that acid pretreatment has potential to be applicable for a vast range of biomass samples to obtain high energy yields, but that the exact conditions and optima are dependent on the strain and likely the starting composition of the biomass.« less

Impact of biochemical composition on susceptibility of algal biomass to acid-catalyzed pretreatment for sugar and lipid recovery

DOE PAGES

Dong, Tao; Van Wychen, Stefanie; Nagle, Nick; ...

2016-06-11

One of the major challenges associated with algal biofuels production in a biorefinery-type setting is improving biomass utilization in its entirety, increasing the process energetic yields and providing economically viable and scalable co-product concepts. We focus on the impact of compositional characteristics of biomass on the susceptibility to pretreatment in order to maximize the valorization of algal biomass conversion for biofuels and bioproducts. The release of monomeric carbohydrates in the aqueous phase and extractability of the lipid fraction was measured based a response surface methodology to find significant explanatory variables and interaction terms. We studied the effect of harvest timingmore » on the conversion yields, using three algal strains; Chlorella vulgaris and Scenedesmus acutus and Nannochloropsis granulata representing three different nutritional metabolic phases. Four cultivation conditions of high (≥ 90 gallon gasoline equivalent/ton biomass) value for a combined sugar- and lipid-based biofuels process were identified. These four conditions represent either mid or late stage harvest cultivation regimes. Lastly, the results indicate that acid pretreatment has potential to be applicable for a vast range of biomass samples to obtain high energy yields, but that the exact conditions and optima are dependent on the strain and likely the starting composition of the biomass.« less

Partitioning phase preference for secondary organic aerosol in an urban atmosphere

NASA Astrophysics Data System (ADS)

Chang, Wayne Li-Wen

Secondary organic aerosol (SOA) comprises a significant portion of atmospheric particular matter (PM). The impact of PM on both human health and global climate has long been recognized. Despite its importance, there are still many unanswered questions regarding the formation and evolution of SOA in the atmosphere. This study uses a modeling approach to understand the preferred partitioning behavior of SOA species into aqueous or organic condensed phases. More specifically, this work uses statistical analyses of approximately 24,000 data values for each variable from a state-of-the-art 3-D airshed model. Spatial and temporal distributions of fractions of SOA residing in the aqueous phase (fAQ) in the South Coast Air Basin of California are presented. Typical values of fAQ within the basin near the surface range from 5 to 80%. Results show that the distribution of fAQ values is inversely proportional to the total SOA loading. Further analysis accounting for various meteorological parameters indicates that large fAQ values are the results of aqueous-phase SOA insensitivity to the ambient conditions; while organic-phase SOA concentrations are dramatically reduced under unfavorable SOA formation conditions, aqueous-phase SOA level remains relatively unchanged, thus increasing fAQ at low SOA loading. Diurnal variations of fAQ near the surface are also observed: it tends to be larger during daytime hours than nighttime hours. When examining the vertical gradient of fAQ, largest values are found at heights above the surface layer. In summary, one must consider SOA in both organic and aqueous phases for proper regional and global SOA budget estimation.

SALICYLATE PROCESS FOR THORIUM SEPARATION FROM RARE EARTHS

DOEpatents

Cowan, G.A.

1959-08-25

The separation of thorium from rare earths is accomplished by forming an aqueous solution of salts of thorium and rare earths and sufficient acetate buffer to provide a pH of between 2 and 5, adding an ammonium salicylate to the aqueous buffered solution, contacting the resultant solution with a substantially water-immiscible organic solvent mixture of an ether and an ester, and separating the solvent extract phase containing thorium salicylate from the aqueous phase containing the rare earths.

Variation in pH of Model Secondary Organic Aerosol during Liquid-Liquid Phase Separation.

PubMed

Dallemagne, Magda A; Huang, Xiau Ya; Eddingsaas, Nathan C

2016-05-12

The majority of atmospheric aerosols consist of both organic and inorganic components. At intermediate relative humidity (RH), atmospheric aerosol can undergo liquid-liquid phase separation (LLPS) in which the organic and inorganic fractions segregate from each other. We have extended the study of LLPS to the effect that phase separation has on the pH of the overall aerosols and the pH of the individual phases. Using confocal microscopy and pH sensitive dyes, the pH of internally mixed model aerosols consisting of polyethylene glycol 400 and ammonium sulfate as well as the pH of the organic fraction during LLPS have been directly measured. During LLPS, the pH of the organic fraction was observed to increase to 4.2 ± 0.2 from 3.8 ± 0.1 under high RH when the aerosol was internally mixed. In addition, the high spatial resolution of the confocal microscope allowed us to characterize the composition of each of the phases, and we have observed that during LLPS the organic shell still contains large quantities of water and should be characterized as an aqueous organic-rich phase rather than simply an organic phase.

Rutile solubility in NaF–NaCl–KCl-bearing aqueous fluids at 0.5–2.79GPa and 250–650°C

DOE PAGES

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; ...

2016-01-14

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nbmore » and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 degrees C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at similar to 300 degrees C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 degrees C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log D-Zr similar to 10(-25) m(2)/s at 650 degrees C and similar to 10(-30) m(2)/s at 250 degrees C) with diffusion length-scales of <0.2 mu m in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

Rutile solubility in NaF-NaCl-KCl-bearing aqueous fluids at 0.5-2.79 GPa and 250-650 °C

NASA Astrophysics Data System (ADS)

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; Chow, Paul; Xiao, Yuming; Hanchar, John M.; Tschauner, Oliver; Shen, Guoyin

2016-03-01

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nb and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 °C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at ∼300 °C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 °C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log DZr ∼10-25 m2/s at 650 °C and ∼10-30 m2/s at 250 °C) with diffusion length-scales of <0.2 μm in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility.

Field-scale multi-phase LNAPL remediation: Validating a new computational framework against sequential field pilot trials.

PubMed

Sookhak Lari, Kaveh; Johnston, Colin D; Rayner, John L; Davis, Greg B

2018-03-05

Remediation of subsurface systems, including groundwater, soil and soil gas, contaminated with light non-aqueous phase liquids (LNAPLs) is challenging. Field-scale pilot trials of multi-phase remediation were undertaken at a site to determine the effectiveness of recovery options. Sequential LNAPL skimming and vacuum-enhanced skimming, with and without water table drawdown were trialled over 78days; in total extracting over 5m 3 of LNAPL. For the first time, a multi-component simulation framework (including the multi-phase multi-component code TMVOC-MP and processing codes) was developed and applied to simulate the broad range of multi-phase remediation and recovery methods used in the field trials. This framework was validated against the sequential pilot trials by comparing predicted and measured LNAPL mass removal rates and compositional changes. The framework was tested on both a Cray supercomputer and a cluster. Simulations mimicked trends in LNAPL recovery rates (from 0.14 to 3mL/s) across all remediation techniques each operating over periods of 4-14days over the 78day trial. The code also approximated order of magnitude compositional changes of hazardous chemical concentrations in extracted gas during vacuum-enhanced recovery. The verified framework enables longer term prediction of the effectiveness of remediation approaches allowing better determination of remediation endpoints and long-term risks. Copyright © 2017 Commonwealth Scientific and Industrial Research Organisation. Published by Elsevier B.V. All rights reserved.

Pore-scale interfacial dynamics during gas-supersaturated water injection in porous media - on nucleation, growth and advection of disconnected fluid phases (Invited)

NASA Astrophysics Data System (ADS)

Or, D.; Ioannidis, M.

2010-12-01

Degassing and in situ development of a mobile gas bubbles occur when injecting supersaturated aqueous phase into water-saturated porous media. Supersaturated water injection (SWI) has potentially significant applications in remediation of soils contaminated by non-aqueous phase liquids and in enhanced oil recovery. Pore network simulations indicate the formation of a region near the injection boundary where gas phase nuclei are activated and grow by mass transfer from the flowing supersaturated aqueous phase. Ramified clusters of gas-filled pores develop which, owing to the low prevailing Bond number, grow laterally to a significant extent prior to the onset of mobilization, and are thus likely to coalesce. Gas cluster mobilization invariably results in fragmentation and stranding, such that a macroscopic region containing few tenuously connected large gas clusters is established. Beyond this region, gas phase nucleation and mass transfer from the aqueous phase are limited by diminishing supply of dissolved gas. New insights into SWI dynamics are obtained using rapid micro-visualization in transparent glass micromodels. Using high-speed imaging, we observe the nucleation, initial growth and subsequent fate (mobilization, fragmentation, collision, coalescence and stranding) of CO2 bubbles and clusters of gas-filled pores and analyze cluster population statistics. We find significant support for the development of invasion-percolation-like patterns, but also report on hitherto unaccounted for gas bubble behavior. Additionally, we report for the first time on the acoustic emission signature of SWI in porous media and relate it to the dynamics of bubble nucleation and growth. Finally, we identify the pore-scale mechanisms associated with the mobilization and subsequent recovery of a residual non-aqueous phase liquid due to gas bubble dynamics during SWI.

Experimental measurements of U60 nanocluster stability in aqueous solution

NASA Astrophysics Data System (ADS)

Flynn, Shannon L.; Szymanowski, Jennifer E. S.; Gao, Yunyi; Liu, Tianbo; Burns, Peter C.; Fein, Jeremy B.

2015-05-01

In this study, the aqueous behavior of isolated U60 nanoclusters (K16Li25[UO2(O2)OH]60)-19 was studied under several pH conditions and nanocluster concentrations to determine if the nanoclusters exhibit solid phase buffering behavior or if they exhibit behavior more like aqueous complexes. U60 is a cage cluster consisting of 60 (UO2)(O2)2(OH)2 uranyl polyhedral which share OH and O2 groups with their neighboring uranyl polyhedral, resulting in negatively charged cage clusters whose charge is at least partially offset by K+ and Li+ in the aqueous phase. Batch experiments to monitor nanocluster stability were conducted for 16 days at pH 7.5, 8.0 and 8.5 at nanocluster suspension concentrations of 1.4, 2.8 and 6.0 g/L. The aqueous concentrations of U, Li, and K, determined after 10 kDa molecular weight filtration, achieved steady-state with the nanoclusters within 24 h. The steady-state aqueous U, Li, and K concentrations were independent of solution pH, however they increased with increasing nanocluster concentration, indicating that the nanoclusters do not buffer the aqueous activities as a bulk solid phase would, but exhibit behavior that is more characteristic of dissolved aqueous complexes. The ion activity product (I.A.P.) value was calculated using two approaches: (1) treating the nanoclusters as a solid phase with an activity of one, and (2) treating the nanoclusters as aqueous complexes with a non-unit activity equal to their concentration in solution. The I.A.P. values that were calculated with non-unit activity for the nanoclusters exhibited significantly less variation as a function of nanocluster concentration compared to the I.A.P. values calculated with a nanocluster activity of one. The results yield a calculated log dissociation constant for the U60 nanoclusters of 9.2 + 0.2/-0.3 (1σ). Our findings provide a better understanding of the thermodynamic stability and behavior of U60 nanoclusters in aqueous systems, and can be used to estimate the dissociation behavior of nanoclusters under a range of aqueous conditions.

Syngas fermentation to biofuel: evaluation of carbon monoxide mass transfer and analytical modeling using a composite hollow fiber (CHF) membrane bioreactor.

PubMed

Munasinghe, Pradeep Chaminda; Khanal, Samir Kumar

2012-10-01

In this study, the volumetric mass transfer coefficients (Ka) for CO were examined in a composite hollow fiber (CHF) membrane bioreactor. The mass transfer experiments were conducted at various inlet gas pressures (from 5 to 30 psig (34.5-206.8 kPa(g))) and recirculation flow rates (300, 600, 900, 1200 and 1500 mL/min) through CHF module. The highest Ka value of 946.6 1/h was observed at a recirculation rate of 1500 mL/min and at an inlet gas pressure of 30 psig(206.8 kPa(g)). The findings of this study confirm that the use of CHF membranes is effective and improves the efficiency CO mass transfer into the aqueous phase. Copyright © 2012 Elsevier Ltd. All rights reserved.

Energetics of small molecule and water complexation in hydrophobic calixarene cavities.

PubMed

Notestein, Justin M; Katz, Alexander; Iglesia, Enrique

2006-04-25

Calixarenes grafted on silica are energetically uniform hosts that bind aromatic guests with 1:1 stoichiometry, as shown by binding energies that depend upon the calixarene upper rim composition but not on their grafted surface density (0.02-0.23 nm(-2)). These materials are unique in maintaining a hydrophilic silica surface, as probed by H2O physisorption measurements, while possessing a high density of hydrophobic binding sites that are orthogonal to the silica surface below them. The covalently enforced cone-shaped cavities and complete accessibility of these rigidly grafted calixarenes allow the first unambiguous measurements of the thermodynamics of guest interaction with the same calixarene cavities in aqueous solution and vapor phase. Similar to adsorption into nonpolar protein cavities, adsorption into these hydrophobic cavities from aqueous solution is enthalpy-driven, which is in contrast to entropy-driven adsorption into water-soluble hydrophobic hosts such as beta cyclodextrin. The adsorption thermodynamics of several substituted aromatics from vapor and liquid are compared by (i) describing guest chemical potentials relative to pure guest, which removes differences among guests because of aqueous solvation and van der Waals contacts in the pure condensed phase, and (ii) passivating residual guest binding sites on exposed silica, titrated by water during adsorption from aqueous solution, using inorganic salts before vapor adsorption. Adsorption isotherms depend only upon the saturation vapor pressure of each guest, indicating that guest binding from aqueous or vapor media is controlled by van der Waals contacts with hydrophobic calixarene cavities acting as covalently assembled condensation nuclei, without apparent contributions from CH-pi or other directional interactions. These data also provide the first direct quantification of free energies for interactions of water with the calixarene cavity interior. The calixarene-water interface is stabilized by approximately 20 kJ/mol relative to the water-vapor interface, indicating that water significantly competes with the aromatic guests for adsorption at these ostensibly hydrophobic cavities. This result is useful for understanding models of water interactions with other concave hydrophobic surfaces, including those commonly observed within proteins.

Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: Competition among oligomerization, functionalization, and fragmentation

DOE PAGES

Yu, Lu; Smith, Jeremy; Laskin, Alexander; ...

2016-04-13

Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water) through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosols and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA) formed during reactions of phenolic compounds with two oxidants – the triplet excited state of an aromatic carbonyl ( 3C *) and hydroxyl radical ( • OH). Changes in themore » molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS) whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OS C) are monitored using an online aerosol mass spectrometer (AMS). Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ~2 h irradiation under midday winter solstice sunlight in Northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule) and fragmentation (i.e., breaking of covalent bonds) become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OS C values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated ring-opening molecules with carbon numbers ( n C) below 6. The average n C of phenolic aqSOA decreases while average OS C increases over the course of photochemical aging. In addition, the saturation vapor pressures ( C *) of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of C * values is observed, varying from < 10 –20 µg m –3 for functionalized phenolic oligomers to > 10 µg m –3 for small open-ring species. Furthermore, the detection of abundant extremely low-volatile organic compounds (ELVOC) indicates that aqueous reactions of phenolic compounds are likely an important source of ELVOC in the atmosphere.« less

Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: Competition among oligomerization, functionalization, and fragmentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Lu; Smith, Jeremy; Laskin, Alexander

Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water) through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosols and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA) formed during reactions of phenolic compounds with two oxidants – the triplet excited state of an aromatic carbonyl ( 3C *) and hydroxyl radical ( • OH). Changes in themore » molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS) whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OS C) are monitored using an online aerosol mass spectrometer (AMS). Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ~2 h irradiation under midday winter solstice sunlight in Northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule) and fragmentation (i.e., breaking of covalent bonds) become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OS C values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated ring-opening molecules with carbon numbers ( n C) below 6. The average n C of phenolic aqSOA decreases while average OS C increases over the course of photochemical aging. In addition, the saturation vapor pressures ( C *) of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of C * values is observed, varying from < 10 –20 µg m –3 for functionalized phenolic oligomers to > 10 µg m –3 for small open-ring species. Furthermore, the detection of abundant extremely low-volatile organic compounds (ELVOC) indicates that aqueous reactions of phenolic compounds are likely an important source of ELVOC in the atmosphere.« less

Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: competition among oligomerization, functionalization, and fragmentation

NASA Astrophysics Data System (ADS)

Yu, L.; Smith, J.; Laskin, A.; George, K. M.; Anastasio, C.; Laskin, J.; Dillner, A. M.; Zhang, Q.

2015-10-01

Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water) through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosols and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA) formed during reactions of phenolic compounds with two oxidants - the triplet excited state of an aromatic carbonyl (3C*) and hydroxyl radical (•OH). Changes in the molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS) whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OSC) are monitored using an online aerosol mass spectrometer (AMS). Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ∼ 2 h irradiation under midday, winter solstice sunlight in northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule) and fragmentation (i.e., breaking of covalent bonds) become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OSC values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated open-ring molecules with carbon numbers (nC) below 6. The average nC of phenolic aqSOA decreases while average OSC increases over the course of photochemical aging. In addition, the saturation vapor pressures C*) of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of C* values is observed, varying from < 10-20 μg m-3 for functionalized phenolic oligomers to > 10 μg m-3 for small open-ring species. The detection of abundant extremely low volatile organic compounds (ELVOC) indicates that aqueous reactions of phenolic compounds are likely an important source of ELVOC in the atmosphere.

Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: competition among oligomerization, functionalization, and fragmentation

NASA Astrophysics Data System (ADS)

Yu, Lu; Smith, Jeremy; Laskin, Alexander; George, Katheryn M.; Anastasio, Cort; Laskin, Julia; Dillner, Ann M.; Zhang, Qi

2016-04-01

Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water) through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosols and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA) formed during reactions of phenolic compounds with two oxidants - the triplet excited state of an aromatic carbonyl (3C∗) and hydroxyl radical (•OH). Changes in the molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS) whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OSC) are monitored using an online aerosol mass spectrometer (AMS). Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ˜ 2 h irradiation under midday winter solstice sunlight in Northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule) and fragmentation (i.e., breaking of covalent bonds) become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OSC values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated ring-opening molecules with carbon numbers (nC) below 6. The average nC of phenolic aqSOA decreases while average OSC increases over the course of photochemical aging. In addition, the saturation vapor pressures (C∗) of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of C∗ values is observed, varying from < 10-20 µg m-3 for functionalized phenolic oligomers to > 10 µg m-3 for small open-ring species. The detection of abundant extremely low-volatile organic compounds (ELVOC) indicates that aqueous reactions of phenolic compounds are likely an important source of ELVOC in the atmosphere.

Effect of heterogeneous aqueous reactions on the secondary formation of inorganic aerosols during haze events

DOE PAGES

Quan, Jiannong; Liu, Yangang; Liu, Quan; ...

2015-09-30

In this study, the effect of heterogeneous aqueous reactions on the secondary formation of inorganic aerosols during haze events was investigated by analysis of comprehensive measurements of aerosol composition and concentrations [e.g., particular matters (PM 2.5), nitrate (NO 3), sulfate (SO 4), ammonium (NH 4)], gas-phase precursors [e.g., nitrogen oxides (NOx), sulfur dioxide (SO 2), and ozone (O 3)], and relevant meteorological parameters [e.g., visibility and relative humidity (RH)]. The measurements were conducted in Beijing, China from Sep. 07, 2012 to Jan. 16, 2013. The results show that the conversion ratios of N from NOx to nitrate (N ratio) andmore » S from SO 2 to sulfate (S ratio) both significantly increased in haze events, suggesting enhanced conversions from NOx and SO 2 to their corresponding particle phases in the late haze period. Further analysis shows that N ratio and S ratio increased with increasing RH, with N ratio and S ratio being only 0.04 and 0.03, respectively, when RH < 40%, and increasing up to 0.16 and 0.12 when RH reached 60–80%, respectively. The enhanced conversion ratios of N and S in the late haze period is likely due to heterogeneous aqueous reactions, because solar radiation and thus the photochemical capacity are reduced by the increases in aerosols and RH. This point was further affirmed by the relationships of N ratio and S ratio to O 3: the conversion ratios increase with decreasing O 3 concentration when O 3 concentration is lower than <15 ppb but increased with increasing O 3 when O 3 concentration is higher than 15 ppb. The results suggest that heterogeneous aqueous reactions likely changed aerosols and their precursors during the haze events: in the beginning of haze events, the precursor gases accumulated quickly due to high emission and low reaction rate; the occurrence of heterogeneous aqueous reactions in the late haze period, together with the accumulated high concentrations of precursor gases such as SO 2 and NOx, accelerated the formation of secondary inorganic aerosols, and led to rapid increase of the PM 2.5 concentration.« less

Modeling the partitioning of organic chemical species in cloud phases with CLEPS (1.1)

NASA Astrophysics Data System (ADS)

Rose, Clémence; Chaumerliac, Nadine; Deguillaume, Laurent; Perroux, Hélène; Mouchel-Vallon, Camille; Leriche, Maud; Patryl, Luc; Armand, Patrick

2018-02-01

The new detailed aqueous-phase mechanism Cloud Explicit Physico-chemical Scheme (CLEPS 1.0), which describes the oxidation of isoprene-derived water-soluble organic compounds, is coupled with a warm microphysical module simulating the activation of aerosol particles into cloud droplets. CLEPS 1.0 was then extended to CLEPS 1.1 to include the chemistry of the newly added dicarboxylic acids dissolved from the particulate phase. The resulting coupled model allows the prediction of the aqueous-phase concentrations of chemical compounds originating from particle scavenging, mass transfer from the gas-phase and in-cloud aqueous chemical reactivity. The aim of the present study was more particularly to investigate the effect of particle scavenging on cloud chemistry. Several simulations were performed to assess the influence of various parameters on model predictions and to interpret long-term measurements conducted at the top of Puy de Dôme (PUY, France) in marine air masses. Specific attention was paid to carboxylic acids, whose predicted concentrations are on average in the lower range of the observations, with the exception of formic acid, which is rather overestimated in the model. The different sensitivity runs highlight the fact that formic and acetic acids mainly originate from the gas phase and have highly variable aqueous-phase reactivity depending on the cloud acidity, whereas C3-C4 carboxylic acids mainly originate from the particulate phase and are supersaturated in the cloud.

Bacterial RNA isolation.

PubMed

Ares, Manuel

2012-09-01

In this bacterial RNA isolation protocol, an "RNA-protective" treatment is followed by lysozyme digestion of the peptidoglycan component of the cell wall. EDTA promotes the loss of the outer membrane of Gram-negative bacteria and allows the lysozyme better access to the peptidoglycan. Cells begin to lyse during digestion in hypotonic lysozyme buffer and lysis is completed by sodium dodecyl sulfate (SDS) and hot phenol:chloroform:isoamyl alcohol (PCA) extraction. SDS and hot phenol disrupt membranes, denature protein (including RNase), and strip proteins from RNA. The separation of the organic phase from the aqueous phase is achieved using Phase Lock Gel, an inert material with a density intermediate between the organic and aqueous samples. The sample is split into three phases: from bottom to top, these are phenol and chloroform (organic phase), the inert gel with the interface material, and the aqueous phase with the RNA. The gel acts as a physical barrier between the sample and the organic phase plus interface. Following organic extraction, the RNA is concentrated by ethanol precipitation.