Thermodynamic and structure-property study of liquid-vapor equilibrium for aroma compounds.

PubMed

Tromelin, Anne; Andriot, Isabelle; Kopjar, Mirela; Guichard, Elisabeth

2010-04-14

Thermodynamic parameters (T, DeltaH degrees , DeltaS degrees , K) were collected from the literature and/or calculated for five esters, four ketones, two aldehydes, and three alcohols, pure compounds and compounds in aqueous solution. Examination of correlations between these parameters and the range values of DeltaH degrees and DeltaS degrees puts forward the key roles of enthalpy for vaporization of pure compounds and of entropy in liquid-vapor equilibrium of compounds in aqueous solution. A structure-property relationship (SPR) study was performed using molecular descriptors on aroma compounds to better understand their vaporization behavior. In addition to the role of polarity for vapor-liquid equilibrium of compounds in aqueous solution, the structure-property study points out the role of chain length and branching, illustrated by the correlation between the connectivity index CHI-V-1 and the difference between T and log K for vaporization of pure compounds and compounds in aqueous solution. Moreover, examination of the esters' enthalpy values allowed a probable conformation adopted by ethyl octanoate in aqueous solution to be proposed.

Effect of solute nature on the polyamorphic transition in glassy polyol aqueous solutions.

PubMed

Suzuki, Yoshiharu

2017-08-14

I examined the polyamorphic behavior of glassy dilute aqueous solutions of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol) under pressure at low temperatures. Although the volume change of the glassy aqueous solution varied continuously against pressure, the rate of the volume change appeared to vary discontinuously at the onset pressure of the gradual polyamorphic transition. It is thought that low-density liquid-like solvent water and high-density liquid-like solvent water coexist during the transition. Moreover, the existence of a solute induces the shift of polyamorphic transition to the lower-pressure side. The effect of a solute on the polyamorphic transition becomes larger in the order ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol. Therefore, the solute can become a variable controlling the polyamorphic state of liquid water. This experimental result suggests that the metastable-equilibrium phase boundary between the low-density and the high-density amorphs for pure water is likely to be located at 0.22-0.23 GPa at about 150 K, which is slightly larger than the previously estimated pressure. Moreover, the solute-nature dependence on the polyamorphic transition seems to connect to that on the homogeneous nucleation temperature of polyol aqueous solution at ambient pressure. The region in which a low-density liquid appears coincides with the region in which the nucleus of ice Ih appears, suggesting that the formation of a low-density liquid is a precursory phenomenon of the nucleation of ice Ih.

Effect of solute nature on the polyamorphic transition in glassy polyol aqueous solutions

NASA Astrophysics Data System (ADS)

Suzuki, Yoshiharu

2017-08-01

I examined the polyamorphic behavior of glassy dilute aqueous solutions of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol) under pressure at low temperatures. Although the volume change of the glassy aqueous solution varied continuously against pressure, the rate of the volume change appeared to vary discontinuously at the onset pressure of the gradual polyamorphic transition. It is thought that low-density liquid-like solvent water and high-density liquid-like solvent water coexist during the transition. Moreover, the existence of a solute induces the shift of polyamorphic transition to the lower-pressure side. The effect of a solute on the polyamorphic transition becomes larger in the order ethylene glycol, glycerol, meso-erythritol, xylitol, and D-sorbitol. Therefore, the solute can become a variable controlling the polyamorphic state of liquid water. This experimental result suggests that the metastable-equilibrium phase boundary between the low-density and the high-density amorphs for pure water is likely to be located at 0.22-0.23 GPa at about 150 K, which is slightly larger than the previously estimated pressure. Moreover, the solute-nature dependence on the polyamorphic transition seems to connect to that on the homogeneous nucleation temperature of polyol aqueous solution at ambient pressure. The region in which a low-density liquid appears coincides with the region in which the nucleus of ice Ih appears, suggesting that the formation of a low-density liquid is a precursory phenomenon of the nucleation of ice Ih.

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.

[Anomalous Properties of Water and Aqueous Solutions at Low Temperatures].

PubMed

Matsumoto, Masakazu

2015-01-01

Water has many anomalous properties below the room temperature. The temperature range overlaps with that of the Earth's atmosphere and also with that natural life forms favor. We review the origin of the anomalous properties of water and aqueous solutions in association with the hypothetical second critical point and liquid-liquid phase separation of water hidden in the supercooled state of liquid water.

Electronic structure of aqueous solutions: Bridging the gap between theory and experiments.

PubMed

Pham, Tuan Anh; Govoni, Marco; Seidel, Robert; Bradforth, Stephen E; Schwegler, Eric; Galli, Giulia

2017-06-01

Predicting the electronic properties of aqueous liquids has been a long-standing challenge for quantum mechanical methods. However, it is a crucial step in understanding and predicting the key role played by aqueous solutions and electrolytes in a wide variety of emerging energy and environmental technologies, including battery and photoelectrochemical cell design. We propose an efficient and accurate approach to predict the electronic properties of aqueous solutions, on the basis of the combination of first-principles methods and experimental validation using state-of-the-art spectroscopic measurements. We present results of the photoelectron spectra of a broad range of solvated ions, showing that first-principles molecular dynamics simulations and electronic structure calculations using dielectric hybrid functionals provide a quantitative description of the electronic properties of the solvent and solutes, including excitation energies. The proposed computational framework is general and applicable to other liquids, thereby offering great promise in understanding and engineering solutions and liquid electrolytes for a variety of important energy technologies.

Electronic structure of aqueous solutions: Bridging the gap between theory and experiments

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

Pham, Tuan Anh; Govoni, Marco; Seidel, Robert

Predicting the electronic properties of aqueous liquids has been a long-standing challenge for quantum mechanical methods. However, it is a crucial step in understanding and predicting the key role played by aqueous solutions and electrolytes in a wide variety of emerging energy and environmental technologies, including battery and photoelectrochemical cell design. We propose an efficient and accurate approach to predict the electronic properties of aqueous solutions, on the basis of the combination of first-principles methods and experimental validation using state-of-the-art spectroscopic measurements. We present results of the photoelectron spectra of a broad range of solvated ions, showing that first-principles molecularmore » dynamics simulations and electronic structure calculations using dielectric hybrid functionals provide a quantitative description of the electronic properties of the solvent and solutes, including excitation energies. The proposed computational framework is general and applicable to other liquids, thereby offering great promise in understanding and engineering solutions and liquid electrolytes for a variety of important energy technologies.« less

PROCESS FOR SEPARATING PLUTONIUM BY REPEATED PRECIPITATION WITH AMPHOTERIC HYDROXIDE CARRIERS

DOEpatents

Faris, B.F.

1960-04-01

A multiple carrier precipitation method is described for separating and recovering plutonium from an aqueous solution. The hydroxide of an amphoteric metal is precipitated in an aqueous plutonium-containing solution. This precipitate, which carries plutonium, is then separated from the supernatant liquid and dissolved in an aqueous hydroxide solution, forming a second plutonium- containing solution. lons of an amphoteric metal which forms an insoluble hydroxide under the conditions existing in this second solution are added to the second solution. The precipitate which forms and which carries plutonium is separated from the supernatant liquid. Amphoteric metals which may be employed are aluminum, bibmuth, copper, cobalt, iron, lanthanum, nickel, and zirconium.

Freeze-thawing behaviour of highly concentrated aqueous alkali chloride-glucose systems.

PubMed

Kajiwara, K; Motegi, A; Murase, N

2001-01-01

The freeze-thawing behaviour of highly concentrated aqueous alkali chloride-glucose systems was investigated by differential scanning calorimetry (DSC). In the aqueous NaCl-glucose solution system, single or double glass transitions followed by the corresponding devitrification exotherms were observed during rewarming. In the aqueous KCl-glucose solution system, on the other hand, a single glass transition followed by an exotherm was observed during rewarming. The presence of double glass transitions observed for a certain composition of the aqueous NaCl-glucose solution was taken as an evidence for the liquid-liquid immiscibility at low temperatures. Two kinds of crystallisation accompanied by exotherms during rewarming were identified by X-ray diffraction as ice and ice/NaCl x 2H(2)O, or ice/KCl eutectic component.

Aqueous solutions of acidic ionic liquids for enhanced stability of polyoxometalate-carbon supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Hu, Chenchen; Zhao, Enbo; Nitta, Naoki; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

2016-09-01

Nanocomposites based on polyoxometalates (POMs) nanoconfined in microporous carbons have been synthesized and used as electrodes for supercapacitors. The addition of the pseudocapacitance from highly reversible redox reaction of POMs to the electric double-layer capacitance of carbon lead to an increase in specific capacitance of ∼90% at 1 mV s-1. However, high solubility of POM in traditional aqueous electrolytes leads to rapid capacity fading. Here we demonstrate that the use of aqueous solutions of protic ionic liquids (P-IL) as electrolyte instead of aqueous sulfuric acid solutions offers an opportunity to significantly improve POM cycling stability. Virtually no degradation in capacitance was observed in POM-based positive electrode after 10,000 cycles in an asymmetric capacitor with P-IL aqueous electrolyte. As such, POM-based carbon composites may now present a viable solution for enhancing energy density of electrical double layer capacitors (EDLC) based on pure carbon electrodes.

Investigation into the temporal stability of aqueous standard solutions of psilocin and psilocybin using high performance liquid chromatography.

PubMed

Anastos, N; Barnett, N W; Pfeffer, F M; Lewis, S W

2006-01-01

This paper reports an investigation into the temporal stability of aqueous solutions of psilocin and psilocybin reference drug standards over a period of fourteen days. This study was performed using high performance liquid chromatography utilising a (95:5% v/v) methanol: 10 mM ammonium formate, pH 3.5 mobile phase and absorption detection at 269 nm. It was found that the exclusion of light significantly prolonged the useful life of standards, with aqueous solutions of both psilocin and psilocybin being stable over a period of seven days.

Predicting the electronic properties of aqueous solutions from first-principles

NASA Astrophysics Data System (ADS)

Schwegler, Eric; Pham, Tuan Anh; Govoni, Marco; Seidel, Robert; Bradforth, Stephen; Galli, Giulia

Predicting the electronic properties of aqueous liquids has been a long-standing challenge for quantum-mechanical methods. Yet it is a crucial step in understanding and predicting the key role played by aqueous solutions and electrolytes in a wide variety of emerging energy and environmental technologies, including battery and photoelectrochemical cell design. Here we propose an efficient and accurate approach to predict the electronic properties of aqueous solutions, based on the combination of first-principles methods and experimental validation using state-of-the-art spectroscopic measurements. We present results for the photoelectron spectra of a broad range of solvated ions, showing that first-principles molecular dynamics simulations and electronic structure calculations using dielectric hybrid functionals provide a quantitative description of their electronic properties, including excitation energies, of the solvent and solutes. The proposed computational framework is general and applicable to other liquids, thereby offering great promise in understanding and engineering solutions and liquid electrolytes for a variety of important energy technologies. Part of this work was performed under the auspices of the U.S. Department of Energy at LLNL under Contract DE-AC52-07A27344.

Recovery of uranium values

DOEpatents

Brown, K. B.; Crouse, Jr., D. J.; Moore, J. G.

1959-03-10

A liquid-liquid extraction method is presented for recovering uranium values from an aqueous acidic solution by means of certain high molecular weight amine fn the amine classes of primary, secondary, heterocyclic secondary, tertiary, or heterocyclic tertiary. The uranium bearing aqueous acidic solution is contacted with the selected anine dissolved in a nonpolar waterimmiscible organfc solvent such as kerosene. The uranium which is substantially completely extracted by the organic phase may be stripped therefrom by water, and recovered from the aqueous phase by treatment into ammonia to precipitate ammonium diuranate.

RECOVERY OF URANIUM VALUES

DOEpatents

Brown, K.B.; Crouse, D.J. Jr.; Moore, J.G.

1959-03-10

A liquid-liquid extraction method is presented for recovering uranium values from an aqueous acidic solution by means of certain high molecular weight amine in the amine classes of primary, secondary, heterocyclic secondary, tertiary, or heterocyclic tertiary. The uranium bearing aqueous acidic solution is contacted with the selected amine dissolved in a nonpolar water-immiscible organic solvent such as kerosene. The uranium which is substantially completely exiracted by the organic phase may be stripped therefrom by waters and recovered from the aqueous phase by treatment into ammonia to precipitate ammonium diuranate.

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.

Unique role of ionic liquid [bmin][BF 4] during curcumin-surfactant association and micellization of cationic, anionic and non-ionic surfactant solutions

NASA Astrophysics Data System (ADS)

Patra, Digambara; Barakat, Christelle

2011-09-01

Hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroburate, modified the properties of aqueous surfactant solutions associated with curcumin. Because of potential pharmaceutical applications as an antioxidant, anti-inflammatory and anti-carcinogenic agent, curcumin has received ample attention as potential drug. The interaction of curcumin with various charged aqueous surfactant solutions showed it exists in deprotonated enol form in surfactant solutions. The nitro and hydroxyl groups of o-nitrophenol interact with the carbonyl and hydroxyl groups of the enol form of curcumin by forming ground state complex through hydrogen bonds and offered interesting information about the nature of the interactions between the aqueous surfactant solutions and curcumin depending on charge of head group of the surfactant. IL[bmin][BF 4] encouraged early formation of micelle in case of cationic and anionic aqueous surfactant solutions, but slightly prolonged micelle formation in the case of neutral aqueous surfactant solution. However, for curcumin IL [bmin][BF 4] favored strong association (7-fold increase) with neutral surfactant solution, marginally supported association with anionic surfactant solution and discouraged (˜2-fold decrease) association with cationic surfactant solution.

Solvation behaviour of L-leucine in aqueous ionic liquid at different temperatures: Volumetric approach

NASA Astrophysics Data System (ADS)

Sharma, Samriti; Sandarve, Sharma, Amit K.; Sharma, Meena

2018-05-01

For the investigation of interactions of L-leucine in aqueous solutions of an ionic liquid (1-butyl-3-methylimidazolium tetra fluoroborate [Bmim][BF4]) at atmospheric pressure over a temperature range of (293.15K to 313.16K), we use the volumetric approach. By using the density data we have calculated the apparent molar volume, VΦ, limiting apparent molar volume, V0Φ, the slope, Sv, partial molar volume of transfer, V0Φ,tr. The values of these acoustical parameters have been used for the interpretation of different interactions like hydrophilic-hydrophilic, hydrophilic-hydrophobic, ion hydrophilic, solute-solvent and solute-solute interactions in the amino acid and ionic liquid solutions.

Supported liquid inorganic membranes for nuclear waste separation

DOEpatents

Bhave, Ramesh R; DeBusk, Melanie M; DelCul, Guillermo D; Delmau, Laetitia H; Narula, Chaitanya K

2015-04-07

A system and method for the extraction of americium from radioactive waste solutions. The method includes the transfer of highly oxidized americium from an acidic aqueous feed solution through an immobilized liquid membrane to an organic receiving solvent, for example tributyl phosphate. The immobilized liquid membrane includes porous support and separating layers loaded with tributyl phosphate. The extracted solution is subsequently stripped of americium and recycled at the immobilized liquid membrane as neat tributyl phosphate for the continuous extraction of americium. The sequestered americium can be used as a nuclear fuel, a nuclear fuel component or a radiation source, and the remaining constituent elements in the aqueous feed solution can be stored in glassified waste forms substantially free of americium.

New model system in radiation cryochemistry:. hyperquenched glassy water

NASA Astrophysics Data System (ADS)

Bednarek, Janusz; Plonka, Andrzej; Hallbrucker, Andreas; Mayer, Erwin

1999-08-01

Radicals generated by high-energy irradiation of liquid water, short-lived at ambient temperature, can be studied at cryogenic temperatures after irradiating water and dilute aqueous solutions in their glassy states which can be obtained by so-called hyperquenching of the liquids at cooling rates of ˜10 6-10 7 K s -1. In the glassy states of hyperquenched dilute aqueous solutions there is no problem with phase separation and radiolysis of glassy water is quite distinct from radiolysis of polycrystalline ice obtained from liquid water on slow-cooling in liquid nitrogen.

Separations by supported liquid membrane cascades

DOEpatents

Danesi, Pier R.

1986-01-01

The invention describes a new separation technique which leads to multi-stage operations by the use of a series (a cascade) of alternated carrier-containing supported-liquid membranes. The membranes contain alternatively a liquid cation exchanger extractant and a liquid anion exchanger extractant (or a neutral extractant) as carrier. The membranes are spaced between alternated aqueous electrolytic solutions of different composition which alternatively provide positively charged extractable species and negatively charged (or zero charged) extractable species, of the chemical species to be separated. The alternated aqueous electrolytic solutions in addition to providing the driving force to the process, simultaneously function as a stripping solution from one type of membrane and as an extraction-promoting solution for the other type of membrane. The aqueous electrolytic solutions and the supported liquid membranes are arranged in such a way to provide a continuous process which leads to the continuous enrichment of the species which show the highest permeability coefficients. By virtue of the very high number of stages which can be arranged, even chemical species having very similar chemical behavior (and consequently very similar permeability coefficients) can be completely separated. The invention also provide a way to concentrate the separated species.

A reversible conductivity modulation of azobenzene-based ionic liquids in aqueous solutions using UV/vis light.

PubMed

Li, Zhiyong; Yuan, Xiaoqing; Feng, Ying; Chen, Yongkui; Zhao, Yuling; Wang, Huiyong; Xu, Qingli; Wang, Jianji

2018-05-09

Photo-induced conductivity modulation of stimuli-responsive materials is of great importance from the viewpoint of fundamental research and technology. In this work, 5 new kinds of azobenzene-based photo-responsive ionic liquids were synthesized and characterized, and UV/vis light modulation of their conductivity was investigated in an aqueous solution. The factors affecting the conductivity modulation of the photo-responsive fluids, such as photo-isomerization efficiency, photo-regulation aggregation, concentration and chemical structure of the ionic liquids, were examined systematically. It was found that the conductivity of the ionic liquids in water exhibited a significant increase upon UV light irradiation and the ionic liquids with a shorter alkyl spacer in the cation showed a more remarkable photo-induced conductivity enhancement with a maximum increase of 150%. In addition, the solution conductivity was restored (or very close) to the initial value upon an alternative irradiation with visible light. Thus, the solution conductivity can be modulated using alternative irradiation with UV and visible light. Although the reversible photo-isomerization of the azobenzene group under UV/vis irradiation is the origin of the conductivity modulation, the photo-regulated aggregation of the ionic liquid in water is indispensable for the maximum degree of conductivity modulation because UV irradiation can weaken, even break the aggregated cis-isomers of the ionic liquids in an aqueous solution.

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.

Performance of carbon-carbon supercapacitors based on organic, aqueous and ionic liquid electrolytes

NASA Astrophysics Data System (ADS)

Lewandowski, Andrzej; Olejniczak, Angelika; Galinski, Maciej; Stepniak, Izabela

Properties of capacitors working with the same carbon electrodes (activated carbon cloth) and three types of electrolytes: aqueous, organic and ionic liquids were compared. Capacitors filled with ionic liquids worked at a potential difference of 3.5 V, their solutions in AN and PC were charged up to the potential difference of 3 V, classical organic systems to 2.5 V and aqueous to 1 V. Cyclic voltammetry, galvanostatic charging/discharging and impedance spectroscopy were used to characterize these capacitors. The highest specific energy was recorded for the device working with ionic liquids, while the highest power is characteristic for the device filled with aqueous H 2SO 4 electrolyte. Aqueous electrolytes led to energy density an order of magnitude lower in comparison to that characteristic of ionic liquids.

Removal of chromium(III) from aqueous waste solution by liquid-liquid extraction in a circular microchannel.

PubMed

Luo, Jian Hong; Li, Jun; Guo, Lei; Zhu, Xin Hua; Dai, Shuang; Li, Xing

2017-11-01

A new circular microchannel device has been proposed for the removal of chromium(III) from aqueous waste solution by using kerosene as a diluent and (2-ethylhexyl) 2-ethylhexyl phosphonate as an extractant. The proposed device has several advantages such as a flexible and easily adaptable design, easy maintenance, and cheap setup without the requirement of microfabrication. To study the extraction efficiency and advantages of the circular microchannel device in the removal of chromium(III), the effects of various operating conditions such as the inner diameter of the channel, the total flow velocity, the phase ratio, the initial pH of aqueous waste solution, the reaction temperature and the initial concentration of extractant on the extraction efficiency are investigated and the optimal process conditions are obtained. The results show that chromium(III) in aqueous waste solution can be effectively removed with (2-ethylhexyl) 2-ethylhexyl phosphonate in the circular microchannel. Under optimized conditions, an extraction efficiency of chromium(III) of more than 99% can be attained and the aqueous waste solution can be discharged directly, which can meet the Chinese national emission standards.

Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water.

PubMed

Biddle, John W; Holten, Vincent; Anisimov, Mikhail A

2014-08-21

A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

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.

Theories of hydrophobic effects and the description of free volume in complex liquids

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

Pratt, L.R.; Garde, S.; Hummer, G.

1998-12-31

Recent progress on molecular theories of hydration of nonpolar solutes in liquid aqueous solution has lead to new ways to thinking about the old issue of free volume in liquids. This article surveys the principal new results with particular attention to the context of general issues of packing in liquids.

Removal of arsenic, vanadium, and/or nickel compounds from petroliferous liquids

DOEpatents

Fish, Richard H.

1986-01-01

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Metal separations using aqueous biphasic partitioning systems

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

Chaiko, D.J.; Zaslavsky, B.; Rollins, A.N.

1996-05-01

Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that the authors have studied are generated by combining an aqueous salt solution with an aqueous polymer solution. They have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. They have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this report they reviewmore » the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation.« less

Method and apparatus for measuring volatile compounds in an aqueous solution

DOEpatents

Gilmore, Tyler J [Pasco, WA; Cantrell, Kirk J [West Richland, WA

2002-07-16

The present invention is an improvement to the method and apparatus for measuring volatile compounds in an aqueous solution. The apparatus is a chamber with sides and two ends, where the first end is closed. The chamber contains a solution volume of the aqueous solution and a gas that is trapped within the first end of the chamber above the solution volume. The gas defines a head space within the chamber above the solution volume. The chamber may also be a cup with the second end. open and facing down and submerged in the aqueous solution so that the gas defines the head space within the cup above the solution volume. The cup can also be entirely submerged in the aqueous solution. The second end of the. chamber may be closed such that the chamber can be used while resting on a flat surface such as a bench. The improvement is a sparger for mixing the gas with the solution volume. The sparger can be a rotating element such as a propeller on a shaft or a cavitating impeller. The sparger can also be a pump and nozzle where the pump is a liquid pump and the nozzle is a liquid spray nozzle open, to the head space for spraying the solution volume into the head space of gas. The pump could also be a gas pump and the nozzle a gas nozzle submerged in the solution volume for spraying the head space gas into the solution volume.

Molecular dynamics simulation studies of the interactions between ionic liquids and amino acids in aqueous solution.

PubMed

Tomé, Luciana I N; Jorge, Miguel; Gomes, José R B; Coutinho, João A P

2012-02-16

Although the understanding of the influence of ionic liquids (ILs) on the solubility behavior of biomolecules in aqueous solutions is relevant for the design and optimization of novel biotechnological processes, the underlying molecular-level mechanisms are not yet consensual or clearly elucidated. In order to contribute to the understanding of the molecular interactions established between amino acids and ILs in aqueous media, classical molecular dynamics (MD) simulations were performed for aqueous solutions of five amino acids with different structural characteristics (glycine, alanine, valine, isoleucine, and glutamic acid) in the presence of 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl imide. The results from MD simulations enable to relate the properties of the amino acids, namely their hydrophobicity, to the type and strength of their interactions with ILs in aqueous solutions and provide an explanation for the direction and magnitude of the solubility phenomena observed in [IL + amino acid + water] systems by a mechanism governed by a balance between competitive interactions of the IL cation, IL anion, and water with the amino acids.

Forced Spreading of Aqueous Solutions on Zwitterionic Sulfobetaine Surfaces for Rapid Evaporation and Solute Separation.

PubMed

Wu, Cyuan-Jhang; Singh, Vickramjeet; Sheng, Yu-Jane; Tsao, Heng-Kwong

2017-08-01

Solute separation of aqueous mixtures is mainly dominated by water vaporization. The evaporation rate of an aqueous drop grows with increasing the liquid-gas interfacial area. The spontaneous spreading behavior of a water droplet on a total wetting surface provides huge liquid-gas interfacial area per unit volume; however, it is halted by the self-pinning phenomenon upon addition of nonvolatile solutes. In this work, it is shown that the solute-induced self-pinning can be overcome by gravity, leading to anisotropic spreading much faster than isotropic spreading. The evaporation rate of anisotropic spreading on a zwitterionic sulfobetaine surface is 25 times larger as that on a poly(methyl methacrylate) surface. Dramatic enhancement of evaporation is demonstrated by simultaneous formation of fog atop liquid film. During anisotropic spreading, the solutes are quickly precipitated out within 30 s, showing the rapid solute-water separation. After repeated spreading process for the dye-containing solution, the mean concentration of the collection is doubled, revealing the concentration efficiency as high as 100%. Gravity-enhanced spreading on total wetting surfaces at room temperature is easy to scale-up with less energy consumption, and thus it has great potentials for the applications of solute separation and concentration.

Applications of ionic liquids in biphasic separation: Aqueous biphasic systems and liquid-liquid equilibria.

PubMed

Shukla, Shashi Kant; Pandey, Shubha; Pandey, Siddharth

2018-07-20

Ionic liquids (ILs) have been receiving much attention in many fields of analytical chemistry because of their various interesting properties which distinguish them from volatile organic compounds. They offer both directional and non-directional forces towards a solute molecule and therefore act as excellent solvents for a wide range of polar and non-polar compounds. Because of the presence of various possible interactions, ILs easily undergo biphasic separation with water and other less polar/non-polar organic solvents. Their ability to create biphasic splitting makes them a promising candidate for liquid-liquid separation processes, such as aqueous biphasic systems and liquid-liquid equilibria. Various aspects of ILs in these separation methods are discussed in view of the origin of physical forces responsible for the biphasic interactions, the effect of structural components, temperature, pressure, pH and additives. The specific advantages of using ILs in aqueous biphasic systems and liquid-liquid equilibria in binary and ternary systems are discussed with a view to defining their future role in separation processes by giving major emphasis on developing non-toxic ILs with physical and solution properties tailored to the needs of specific sample preparation techniques. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

High density liquid structure enhancement in glass forming aqueous solution of LiCl.

PubMed

Camisasca, G; De Marzio, M; Rovere, M; Gallo, P

2018-06-14

We investigate using molecular dynamics simulations the dynamical and structural properties of LiCl:6H 2 O aqueous solution upon supercooling. This ionic solution is a glass forming liquid of relevant interest in connection with the study of the anomalies of supercooled water. The LiCl:6H 2 O solution is easily supercooled and the liquid state can be maintained over a large decreasing temperature range. We performed simulations from ambient to 200 K in order to investigate how the presence of the salt modifies the behavior of supercooled water. The study of the relaxation time of the self-density correlation function shows that the system follows the prediction of the mode coupling theory and behaves like a fragile liquid in all the range explored. The analysis of the changes in the water structure induced by the salt shows that while the salt preserves the water hydrogen bonds in the system, it strongly affects the tetrahedral hydrogen bond network. Following the interpretation of the anomalies of water in terms of a two-state model, the modifications of the oxygen radial distribution function and the angular distribution function of the hydrogen bonds in water indicate that LiCl has the role of enhancing the high density liquid component of water with respect to the low density component. This is in agreement with recent experiments on aqueous ionic solutions.

High density liquid structure enhancement in glass forming aqueous solution of LiCl

NASA Astrophysics Data System (ADS)

Camisasca, G.; De Marzio, M.; Rovere, M.; Gallo, P.

2018-06-01

We investigate using molecular dynamics simulations the dynamical and structural properties of LiCl:6H2O aqueous solution upon supercooling. This ionic solution is a glass forming liquid of relevant interest in connection with the study of the anomalies of supercooled water. The LiCl:6H2O solution is easily supercooled and the liquid state can be maintained over a large decreasing temperature range. We performed simulations from ambient to 200 K in order to investigate how the presence of the salt modifies the behavior of supercooled water. The study of the relaxation time of the self-density correlation function shows that the system follows the prediction of the mode coupling theory and behaves like a fragile liquid in all the range explored. The analysis of the changes in the water structure induced by the salt shows that while the salt preserves the water hydrogen bonds in the system, it strongly affects the tetrahedral hydrogen bond network. Following the interpretation of the anomalies of water in terms of a two-state model, the modifications of the oxygen radial distribution function and the angular distribution function of the hydrogen bonds in water indicate that LiCl has the role of enhancing the high density liquid component of water with respect to the low density component. This is in agreement with recent experiments on aqueous ionic solutions.

Self-Supporting, Hydrophobic, Ionic Liquid-Based Reference Electrodes Prepared by Polymerization-Induced Microphase Separation.

PubMed

Chopade, Sujay A; Anderson, Evan L; Schmidt, Peter W; Lodge, Timothy P; Hillmyer, Marc A; Bühlmann, Philippe

2017-10-27

Interfaces of ionic liquids and aqueous solutions exhibit stable electrical potentials over a wide range of aqueous electrolyte concentrations. This makes ionic liquids suitable as bridge materials that separate in electroanalytical measurements the reference electrode from samples with low and/or unknown ionic strengths. However, methods for the preparation of ionic liquid-based reference electrodes have not been explored widely. We have designed a convenient and reliable synthesis of ionic liquid-based reference electrodes by polymerization-induced microphase separation. This technique allows for a facile, single-pot synthesis of ready-to-use reference electrodes that incorporate ion conducting nanochannels filled with either 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-dodecyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide as ionic liquid, supported by a mechanically robust cross-linked polystyrene phase. This synthesis procedure allows for the straightforward design of various reference electrode geometries. These reference electrodes exhibit a low resistance as well as good reference potential stability and reproducibility when immersed into aqueous solutions varying from deionized, purified water to 100 mM KCl, while requiring no correction for liquid junction potentials.

Removal of arsenic compounds from petroliferous liquids

DOEpatents

Fish, R.H.

1984-04-06

The present invention in one aspect comprises a process for removing arsenic from petroliferous-derived liquids by contacting said liquid with a divinylbenzene-crosslinked polystyrene polymer (i.e. PS-DVB) having catechol ligands anchored to said polymer, said contacting being at an elevated temperature. In another aspect, the invention is a process for regenerating spent catecholated polystyrene polymer by removal of the arsenic bound to it from contacting petroliferous liquid in accordance with the aspect described above which regenerating process comprises: (a) treating said spent catecholated polystyrene polymer with an aqueous solution of at least one member selected from the group consisting of carbonates and bicarbonates of ammonium, alkali metals, and alkaline earth metals, said solution having a pH between about 8 and 10, and said treating being at a temperature in the range of about 20/sup 0/ to 100/sup 0/C; (b) separating the solids and liquids from each other. In a preferred embodiment the regeneration treatment is in two steps wherein step: (a) is carried out with an aqueous alcoholic carbonate solution which includes at least one lower alkyl alcohol, and, steps (c) and (d) are added. Steps (c) and (d) comprise: (c) treating the solids with an aqueous alcoholic solution of at least one ammonium, alkali or alkaline earth metal bicarbonate at a temperature in the range of about 20 to 100/sup 0/C; and (d) separating the solids from the liquids.

A practicable process for phenol removal with liquid surfactant membrane permeation column

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

Kataoka, Takeshi; Osaki, Katsuhiko; Nishiki, Tadaaki

1997-05-01

A practicable liquid surfactant membrane process for phenol removal is proposed with a stirred countercurrent column used as the liquid membrane contact equipment. The constituents of liquid membranes, such as internal aqueous phase and surfactant, the type of column, and the operating conditions for efficient and continuous performance of the liquid surfactant membrane process, have been examined. When NaOH solution was used as the internal aqueous phase and ECA4360J was used as the surfactant, the W/O emulsion was stable for the duration of column operation. More than 97% phenol could be removed from the feed solution. Nearly complete demulsification wasmore » also achieved by gentle agitation with an electrostatic demulsifier.« less

Photoelectron spectroscopy of aqueous solutions: Streaming potentials of NaX (X = Cl, Br, and I) solutions and electron binding energies of liquid water and X{sup −}

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

Kurahashi, Naoya; Horio, Takuya; Suzuki, Toshinori, E-mail: suzuki@kuchem.kyoto-u.ac.jp

2014-05-07

The streaming potentials of liquid beams of aqueous NaCl, NaBr, and NaI solutions are measured using soft X-ray, He(I), and laser multiphoton ionization photoelectron spectroscopy. Gaseous molecules are ionized in the vicinity of liquid beams and the photoelectron energy shifts are measured as a function of the distance between the ionization point and the liquid beam. The streaming potentials change their polarity with concentration of electrolytes, from which the singular points of concentration eliminating the streaming potentials are determined. The streaming currents measured in air also vanish at these concentrations. The electron binding energies of liquid water and I{sup −},more » Br{sup −}, and Cl{sup −} anions are revisited and determined more accurately than in previous studies.« less

Removal of arsenic compounds from petroliferous liquids

DOEpatents

Fish, Richard H.

1985-01-01

Described is a process for removing arsenic from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic bound to it from contacting petroliferous liquid as described above and involves: a. treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10 and, b. separating the solids and liquids from each other. Preferably the regeneration treatment is in two steps wherein step (a) is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, steps (a) and (b) are repeated using a bicarbonate.

Using Environment-Sensitive Fluorescent Probes to Characterize Liquid-Liquid Phase Separation in Supersaturated Solutions of Poorly Water Soluble Compounds.

PubMed

Raina, Shweta A; Alonzo, David E; Zhang, Geoff G Z; Gao, Yi; Taylor, Lynne S

2015-11-01

Highly supersaturated aqueous solutions of poorly soluble compounds can undergo liquid-liquid phase separation (LLPS) when the concentration exceeds the "amorphous solubility". This phenomenon has been widely observed during high throughput screening of new molecular entities as well as during the dissolution of amorphous solid dispersions. In this study, we have evaluated the use of environment-sensitive fluorescence probes to investigate the formation and properties of the non-crystalline drug-rich aggregates formed in aqueous solutions as a result of LLPS. Six different environment-sensitive fluorophores were employed to study LLPS in highly supersaturated solutions of several model compounds, all dihydropyridine derivatives. Each fluoroprobe exhibited a large hypsochromic shift with decreasing environment polarity. Upon drug aggregate formation, the probes partitioned into the drug-rich phase and exhibited changes in emission wavelength and intensity consistent with sensing a lower polarity environment. The LLPS onset concentrations determined using the fluorescence measurements were in good agreement with light scattering measurements as well as theoretically estimated amorphous solubility values. Environment-sensitive fluorescence probes are useful to help understand the phase behavior of highly supersaturated aqueous solutions, which in turn is important in the context of developing enabling formulations for poorly soluble compounds.

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

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

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One systemmore » operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.« less

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

DOEpatents

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-07-14

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

DOEpatents

Fish, R.H.

1987-04-21

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20 to 100 C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

DOEpatents

Fish, Richard H.

1987-01-01

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Dynamic Mass Transfer of Hemoglobin at the Aqueous/Ionic-Liquid Interface Monitored with Liquid Core Optical Waveguide.

PubMed

Chen, Xuwei; Yang, Xu; Zeng, Wanying; Wang, Jianhua

2015-08-04

Protein transfer from aqueous medium into ionic liquid is an important approach for the isolation of proteins of interest from complex biological samples. We hereby report a solid-cladding/liquid-core/liquid-cladding sandwich optical waveguide system for the purpose of monitoring the dynamic mass-transfer behaviors of hemoglobin (Hb) at the aqueous/ionic liquid interface. The optical waveguide system is fabricated by using a hydrophobic IL (1,3-dibutylimidazolium hexafluorophosphate, BBimPF6) as the core, and protein solution as one of the cladding layer. UV-vis spectra are recorded with a CCD spectrophotometer via optical fibers. The recorded spectra suggest that the mass transfer of Hb molecules between the aqueous and ionic liquid media involve accumulation of Hb on the aqueous/IL interface followed by dynamic extraction/transfer of Hb into the ionic liquid phase. A part of Hb molecules remain at the interface even after the accomplishment of the extraction/transfer process. Further investigations indicate that the mass transfer of Hb from aqueous medium into the ionic liquid phase is mainly driven by the coordination interaction between heme group of Hb and the cationic moiety of ionic liquid, for example, imidazolium cation in this particular case. In addition, hydrophobic interactions also contribute to the transfer of Hb.

Hollow-Fibre-Supported Dispersive Liquid-Liquid Microextraction for Determination of Atrazine and Triclosan in Aqueous Samples

PubMed Central

Letseka, Thabiso

2017-01-01

We report the application of the dispersive liquid-liquid microextraction coupled to hollow-fibre membrane-assisted liquid-phase microextraction and its application for extraction of atrazine and triclosan. Under optimum conditions, namely, 25 μL of a 1 : 4 chlorobenzene : ethyl acetate mixture dispersed in 1 mL of aqueous sample, 10% (m/v) NaCl, a magnetic stirrer speed at 600 rpm, and 10 minutes' extraction time with toluene-filled fibre as the acceptor phase, the method demonstrates sufficient figures of merit. These include linearity (R2 ≥ 0.9975), intravial precision (%RSD ≤ 7.6), enrichment factors (127 and 142), limits of detection (0.0081 and 0.0169 µg/mL), and recovery from river water and sewerage (96–101%). The relatively high detection limits are attributed to the flame ionization detector which is less preferred than a mass spectrometer in trace analyses. This is the first report of a homogenous mixture of the dispersed organic solvent in aqueous solutions and its employment in extraction of organic compounds from aqueous solutions. It therefore adds yet another candidate in the pool of miniaturised solvent microextraction techniques. PMID:29158736

Removal of arsenic, vanadium, and/or nickel compounds from petroliferous liquids

DOEpatents

Fish, R.H.

1985-05-17

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids (shale oil, SRC, etc.) by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20/sup 0/ to 100/sup 0/C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Glass-to-cryogenic-liquid transitions in aqueous solutions suggested by crack healing

PubMed Central

Kim, Chae Un; Tate, Mark W.; Gruner, Sol M.

2015-01-01

Observation of theorized glass-to-liquid transitions between low-density amorphous (LDA) and high-density amorphous (HDA) water states had been stymied by rapid crystallization below the homogeneous water nucleation temperature (∼235 K at 0.1 MPa). We report optical and X-ray observations suggestive of glass-to-liquid transitions in these states. Crack healing, indicative of liquid, occurs when LDA ice transforms to cubic ice at 160 K, and when HDA ice transforms to the LDA state at temperatures as low as 120 K. X-ray diffraction study of the HDA to LDA transition clearly shows the characteristics of a first-order transition. Study of the glass-to-liquid transitions in nanoconfined aqueous solutions shows them to be independent of the solute concentrations, suggesting that they represent an intrinsic property of water. These findings support theories that LDA and HDA ice are thermodynamically distinct and that they are continuously connected to two different liquid states of water. PMID:26351671

Effects of Ultrasonic Vibration on Heat Transfer Characteristics of Lithium Bromide Aqueous Solution under the Reduced Pressure

NASA Astrophysics Data System (ADS)

Yamashiro, Hikaru; Nakashima, Ryou

The effects of ultrasonic vibration on heat transfer characteristics of lithium bromide aqueous solution under the reduced pressures are studied experimentally. Pool boiling curves on horizontal smooth tube are obtained using distilled water and 50 % LiBr aqueous solution as test liquids. The system pressure p is varied from 12 to 101 kPa and the liquid subcooling ΔTsub ranges from 0 to 70 K. The frequency of ultrasonic vibration vi s set at 24 and 44 kHz, and the power input to the vibrator P is varied from 0 to 35 W. The wall superheat at the boiling incipience is found to decrease with increasing P, and the nucleate boiling curve shifts toward the lower wall temperature region. However, the effect of P is not found to be very significant in the high heat flux region, especially in the case of small liquid subcooling. Ultrasonic vibration is also found to improve the nucleate boiling heat transfer coefficient by up to a maximum of 3.5 times and to prevent crystallization of the solution and precipitation of additives.

Suppression of evaporation of hydrocarbon liquids and fuels by films containing aqueous film forming foam (AFFF) concentrate FC-196. Interim report

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

Leonard, J.T.; Burnett, J.C.

1974-12-31

Suppression of evaporation of hydrocarbon liquids and fuels by aqueous film containing a fluorocarbon surfactant has been examined as a function of film thickness, time, and hydrocarbon type. The hydrocarbon liquids included the homologous series of n-alkanes from pentane to dodecane, aromatic compounds, motor and aviation gasolines and jet fuels JP-4 and JP-5, and Navy distillate fuel. The surfactant solution used to form the films was a 6 percent solution of aqueous film forming foam (AFFF) concentrate FC-196. Films of the surfactant solution, ranging in thickness from 5 to 100 micrometers, were placed on the surface of the hydrocarbon liquidmore » to test the ability of the film to suppress evaporation over a 1-hr period. Results indicated that for the n-alkanes and the hydrocarbon fuels a certain critical thickness of surfactant solution was required for optimum vapor suppression. In comparison with the n-alkanes, it was considerably more difficult to suppress evaporation of the aromatic compounds. (GRA)« less

SOLVENT EXTRACTION PROCESS FOR PLUTONIUM

DOEpatents

Seaborg, G.T.

1959-04-14

The separation of plutonium from aqueous inorganic acid solutions by the use of a water immiscible organic extractant liquid is described. The plutonium must be in the oxidized state, and the solvents covered by the patent include nitromethane, nitroethane, nitropropane, and nitrobenzene. The use of a salting out agents such as ammonium nitrate in the case of an aqueous nitric acid solution is advantageous. After contacting the aqueous solution with the organic extractant, the resulting extract and raffinate phases are separated. The plutonium may be recovered by any suitable method.

Effects of Metal Ions on Viscosity of Aqueous Sodium Carboxylmethylcellulose Solution and Development of Dropping Ball Method on Viscosity

ERIC Educational Resources Information Center

Set, Seng; Ford, David; Kita, Masakazu

2015-01-01

This research revealed that metal ions with different charges could significantly affect the viscosity of aqueous sodium carboxylmethylcellulose (CMC) solution. On the basis of an Ostwald viscometer, an improvised apparatus using a dropping ball for examining the viscosity of liquids/solutions has been developed. The results indicate that the…

Development of a Compact and Efficient Ice Thermal Energy Storage Vessel

NASA Astrophysics Data System (ADS)

Sasaguchi, Kengo; Ishikawa, Masatoshi; Muta, Kenji; Yoshino, Kiyotaka; Hayashi, Hiroko; Baba, Yoshiyuki

In the present study, the authors propose the use of a low concentration aqueous solution as phase change material for static-type ice-storage-vessels, instead of pure water commonly used today. If an aqueous solution with low concentration is used, even when a large amount of solution (aqueous ethylene glycol in this study) is solidified and bridging of ice developed around cold tubes occurs, the pressure increase could be prevented by the existence of a continuous liquid phase in the solid-liquid two-phase layer (mushy layer) which opens to an air gap at the top of a vessel. Therefore, one can continue to solidify an aqueous solution after bridging, achieving a high ice packing factor (IPF). First, experiments using small-scale test cells have been conducted to confirm the present idea, and then we have performed experiments using a large vessel with an early practical size. It was seen that a large pressure increase is prevented for the initial concentration of the solution C0 of 1.0%, and IPF obtained using the solution is much greater than 0.65 using pure water for which the solidification must be stopped before the bridging.

Glass Transition Temperature of Saccharide Aqueous Solutions Estimated with the Free Volume/Percolation Model.

PubMed

Constantin, Julian Gelman; Schneider, Matthias; Corti, Horacio R

2016-06-09

The glass transition temperature of trehalose, sucrose, glucose, and fructose aqueous solutions has been predicted as a function of the water content by using the free volume/percolation model (FVPM). This model only requires the molar volume of water in the liquid and supercooled regimes, the molar volumes of the hypothetical pure liquid sugars at temperatures below their pure glass transition temperatures, and the molar volumes of the mixtures at the glass transition temperature. The model is simplified by assuming that the excess thermal expansion coefficient is negligible for saccharide-water mixtures, and this ideal FVPM becomes identical to the Gordon-Taylor model. It was found that the behavior of the water molar volume in trehalose-water mixtures at low temperatures can be obtained by assuming that the FVPM holds for this mixture. The temperature dependence of the water molar volume in the supercooled region of interest seems to be compatible with the recent hypothesis on the existence of two structure of liquid water, being the high density liquid water the state of water in the sugar solutions. The idealized FVPM describes the measured glass transition temperature of sucrose, glucose, and fructose aqueous solutions, with much better accuracy than both the Gordon-Taylor model based on an empirical kGT constant dependent on the saccharide glass transition temperature and the Couchman-Karasz model using experimental heat capacity changes of the components at the glass transition temperature. Thus, FVPM seems to be an excellent tool to predict the glass transition temperature of other aqueous saccharides and polyols solutions by resorting to volumetric information easily available.

Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: surfactant chain length dependence of the critical micelle concentration.

PubMed

Inoue, Tohru; Yamakawa, Haruka

2011-04-15

Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C(n)E(m)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)). Critical micelle concentration (cmc) was determined from the variation of (1)H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF(4) than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF(4) is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF(4) is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF(4) proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF(4) is much weaker than the hydrophobic effect. Copyright © 2011 Elsevier Inc. All rights reserved.

Continuous aqueous tritium monitor

DOEpatents

McManus, Gary J.; Weesner, Forrest J.

1989-05-30

An apparatus for a selective on-line determination of aqueous tritium concentration is disclosed. A moist air stream of the liquid solution being analyzed is passed through a permeation dryer where the tritium and moisture and selectively removed to a purge air stream. The purge air stream is then analyzed for tritium concentration, humidity, and temperature, which allows computation of liquid tritium concentration.

Removal of arsenic compounds from spent catecholated polymer

DOEpatents

Fish, Richard H.

1985-01-01

Described is a process for removing arsenic from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic bound to it from contacting petroliferous liquid as described above and involves: a. treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10 and, b. separating the solids and liquids from each other. Preferably the regeneration treatment is in two steps wherein step (a) is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, steps (a) and (b) are repeated using a bicarbonate.

Computational analysis of the solvation of coffee ingredients in aqueous ionic liquid mixtures.

PubMed

Zeindlhofer, Veronika; Khlan, Diana; Bica, Katharina; Schröder, Christian

2017-01-13

In this paper, we investigate the solvation of coffee ingredients including caffeine, gallic acid as representative for phenolic compounds and quercetin as representative for flavonoids in aqueous mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate [C 2 mim][OAc] at various concentrations. Due to the anisotropy of the solutes we show that classical Kirkwood-Buff theory is not appropriate to study solvation effects with increasing ionic liquid content. However, excess coordination numbers as well as the mean residence time of solvent molecules at the surface of the solutes can be determined by Voronoi tessellation. Since the volume of the hydration shells is also available by this method, solvation free energies will be discussed as a function of the ionic liquid concentration to yield a physical meaningful picture of solvation for the anisotropic solutes. Hydrogen bonding capabilities of the solutes and their relevance for experimental extraction yields from spent coffee grounds are also discussed.

Self-Supporting, Hydrophobic, Ionic Liquid-Based Reference Electrodes Prepared by Polymerization-Induced Microphase Separation

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

Chopade, Sujay A.; Anderson, Evan L.; Schmidt, Peter W.

Interfaces of ionic liquids and aqueous solutions exhibit stable electrical potentials over a wide range of aqueous electrolyte concentrations. This makes ionic liquids suitable as bridge materials that separate in electroanalytical measurements the reference electrode from samples with low and/or unknown ionic strengths. However, methods for the preparation of ionic liquid-based reference electrodes have not been explored widely. We have designed a convenient and reliable synthesis of ionic liquid-based reference electrodes by polymerization-induced microphase separation. This technique allows for a facile, single-pot synthesis of ready-to-use reference electrodes that incorporate ion conducting nanochannels filled with either 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-dodecyl-3-methylimidazolium bis(trifluoromethylmore » sulfonyl)imide as ionic liquid, supported by a mechanically robust cross-linked polystyrene phase. This synthesis procedure allows for the straightforward design of various reference electrode geometries. These reference electrodes exhibit a low resistance as well as good reference potential stability and reproducibility when immersed into aqueous solutions varying from deionized, purified water to 100 mM KCl, while requiring no correction for liquid junction potentials.« less

Population and size distribution of solute-rich mesospecies within mesostructured aqueous amino acid solutions.

PubMed

Jawor-Baczynska, Anna; Moore, Barry D; Lee, Han Seung; McCormick, Alon V; Sefcik, Jan

2013-01-01

Aqueous solutions of highly soluble substances such as small amino acids are usually assumed to be essentially homogenous systems with some degree of short range local structuring due to specific interactions on the sub-nanometre scale (e.g. molecular clusters, hydration shells), usually not exceeding several solute molecules. However, recent theoretical and experimental studies have indicated the presence of much larger supramolecular assemblies or mesospecies in solutions of small organic and inorganic molecules as well as proteins. We investigated both supersaturated and undersaturated aqueous solutions of two simple amino acids (glycine and DL-alanine) using Dynamic Light Scattering (DLS), Brownian Microscopy/Nanoparticles Tracking Analysis (NTA) and Cryogenic Transmission Electron Microscopy (Cryo-TEM). Colloidal scale mesospecies (nanodroplets) were previously reported in supersaturated solutions of these amino acids and were implicated as intermediate species on non-classical crystallization pathways. Surprisingly, we have found that the mesospecies are also present in significant numbers in undersaturated solutions even when the solute concentration is well below the solid-liquid equilibrium concentration (saturation limit). Thus, mesopecies can be observed with mean diameters ranging from 100 to 300 nm and a size distribution that broadens towards larger size with increasing solute concentration. We note that the mesospecies are not a separate phase and the system is better described as a thermodynamically stable mesostructured liquid containing solute-rich domains dispersed within bulk solute solution. At a given temperature, solute molecules in such a mesostructured liquid phase are subject to equilibrium distribution between solute-rich mesospecies and the surrounding bulk solution.

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.

Preconcentration of aqueous dyes through phase-transfer liquid-phase microextraction with a room-temperature ionic liquid.

PubMed

Chen, Hsiu-Liang; Chang, Shuo-Kai; Lee, Chia-Ying; Chuang, Li-Lin; Wei, Guor-Tzo

2012-09-12

In this study, we employed the room-temperature ionic liquid [bmim][PF(6)] as both ion-pair agent and an extractant in the phase-transfer liquid-phase microextraction (PTLPME) of aqueous dyes. In the PTLPME method, a dye solution was added to the extraction solution, comprising a small amount of [bmim][PF(6)] in a relatively large amount of CH(2)Cl(2), which serves as the disperser solvent to an extraction solution. Following extraction, CH(2)Cl(2) was evaporated from the extractant, resulting in the extracted dyes being concentrated in a small volume of the ionic liquid phase to increase the enrichment factor. The enrichment factors of for the dye Methylene Blue, Neutral Red, and Methyl Red were approximately 500, 550 and 400, respectively; their detection limits were 0.014, 0.43, and 0.02 μg L(-1), respectively, with relative standard deviations of 4.72%, 4.20%, and 6.10%, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Carbon nanotube scanning probe for imaging in aqueous environment

NASA Technical Reports Server (NTRS)

Stevens, Ramsey M.; Nguyen, Cattien V.; Meyyappan, M.

2004-01-01

Carbon nanotubes (CNTs) used as a probe for scanning probe microscopy has become one of the many potential usages of CNTs that is finding real applications in scientific research and industrial communities. It has been proposed that the unique mechanical buckling properties of the CNT would lessen the imaging force exerted on the sample and, thus, make CNT scanning probes ideal for imaging soft materials, including biological samples in liquid environments. The hydrophobic nature of the CNT graphitic sidewall is clearly chemically incompatible with the aqueous solution requirements in some biological imaging applications. In this paper, we present electron micrograph results demonstrating the instability of CNT scanning probes when submerged in aqueous solution. Moreover, we also introduce a novel approach to resolve this chemical incompatibility problem. By coating the CNT probe with ethylenediamine, thus rendering the CNT probe less hydrophobic, we demonstrate the liquid imaging capability of treated CNT probes. Experimental data for imaging in aqueous solutions are presented, which include an ultrathin Ir film and DNA molecules on a mica surface.

The role of ultrasound in controlling the liquid-liquid phase separation and nucleation of vanillin polymorphs I and II

NASA Astrophysics Data System (ADS)

Parimaladevi, P.; Supriya, S.; Srinivasan, K.

2018-02-01

The influence of ultrasound on liquid-liquid phase separation (LLPS) and polymorphism of vanillin in aqueous solution has been investigated for the first time by varying the ultrasonic parameters such as power, pulse rate and insonation time at ambient condition. Results reveal that the application of ultrasound controls the impact of LLPS and accelerates the nucleation of vanillin within a short period at lower levels of ultrasonic process parameters, and also enhances the quality of the nucleated crystals. Moreover, the application of ultrasound induces the nucleation of rare and metastable polymorph of vanillin Form II in aqueous solution. But, at higher levels of power, pulse rate and insonation time, the rate of LLPS is found increased and the quality of the crystals becomes deteriorated. Morphology of the nucleated polymorphs were identified through optical microscopy and confirmed by optical goniometry. The internal structure and thermal stability of the grown stable Form I and metastable Form II of vanillin were confirmed through powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses. Further, results suggest that the ultrasound has profound effect in controlling the LLPS and nucleation of vanillin polymorphs in aqueous solution.

Interaction between amphiphilic ionic liquid 1-butyl-3-methylimidazolium octyl sulfate and anionic polymer of sodium polystyrene sulfonate in aqueous medium

NASA Astrophysics Data System (ADS)

Barhoumi, Z.; Saini, M.; Amdouni, N.; Pal, A.

2016-09-01

The micellization of an aqueous solution of the surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium octylsufate (C4mim)(C8OSO3) and its interaction with an anionic polymer sodium polystyrene sulfonate, (NaPSS) were studied using conductimetry, tensiometry and fluorimetry. Surface tension profile shows a more dramatic increase in the value of surface tension of aqueous (C4mim)(C8OSO3) before the critical micelle concentration (cmc) of IL. The critical micelle concentration (cmc) value of this surfactant was found out from conductance measurements. The thermodynamic parameters, i.e., Gibb's free energy, enthalpy, and entropy of micellization of the IL in aqueous solution have been calculated. Behavior of fluorescence probe confirms the binding interactions between SAIL and the polyelectrolyte.

Air-assisted dispersive liquid-liquid microextraction based on a new hydrophobic deep eutectic solvent for the preconcentration of benzophenone-type UV filters from aqueous samples.

PubMed

Ge, Dandan; Zhang, Yi; Dai, Yixiu; Yang, Shumin

2018-04-01

Deep eutectic solvents are considered as new and green solvents that can be widely used in analytical chemistry such as microextraction. In the present work, a new dl-menthol-based hydrophobic deep eutectic solvent was synthesized and used as extraction solvents in an air-assisted dispersive liquid-liquid microextraction method for preconcentration and extraction of benzophenone-type UV filters from aqueous samples followed by high-performance liquid chromatography with diode array detection. In an experiment, the deep eutectic solvent formed by dl-menthol and decanoic acid was added to an aqueous solution containing the UV filters, and then the mixture was sucked up and injected five times by using a glass syringe, and a cloudy state was achieved. After extraction, the solution was centrifuged and the upper phase was subjected to high-performance liquid chromatography for analysis. Various parameters such as the type and volume of the deep eutectic solvent, number of pulling, and pushing cycles, solution pH and salt concentration were investigated and optimized. Under the optimum conditions, the developed method exhibited low limits of detection and limits of quantitation, good linearity, and precision. Finally, the proposed method was successfully applied to determine the benzophenone-type filters in environmental water samples with relative recoveries of 88.8-105.9%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Continuous aqueous tritium monitor

DOEpatents

McManus, G.J.; Weesner, F.J.

1987-10-19

An apparatus for a selective on-line determination of aqueous tritium concentration is disclosed. A moist air stream of the liquid solution being analyzed is passed through a permeation dryer where the tritium and moisture are selectively removed to a purge air stream. The purge air stream is then analyzed for tritium concentration, humidity, and temperature, which allows computation of liquid tritium concentration. 2 figs.

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...

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

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.

Extraction of steroidal glucosiduronic acids from aqueous solutions by anionic liquid ion-exchangers

PubMed Central

Mattox, Vernon R.; Litwiller, Robert D.; Goodrich, June E.

1972-01-01

A pilot study on the extraction of three steroidal glucosiduronic acids from water into organic solutions of liquid ion-exchangers is reported. A single extraction of a 0.5mm aqueous solution of either 11-deoxycorticosterone 21-glucosiduronic acid or cortisone 21-glucosiduronic acid with 0.1m-tetraheptylammonium chloride in chloroform took more than 99% of the conjugate into the organic phase; under the same conditions, the very polar conjugate, β-cortol 3-glucosiduronic acid, was extracted to the extent of 43%. The presence of a small amount of chloride, acetate, or sulphate ion in the aqueous phase inhibited extraction, but making the aqueous phase 4.0m with ammonium sulphate promoted extraction strongly. An increase in the concentration of ion-exchanger in the organic phase also promoted extraction. The amount of cortisone 21-glucosiduronic acid extracted by tetraheptylammonium chloride over the pH range of 3.9 to 10.7 was essentially constant. Chloroform solutions of a tertiary, a secondary, or a primary amine hydrochloride also will extract cortisone 21-glucosiduronic acid from water. The various liquid ion exchangers will extract steroidal glucosiduronic acid methyl esters from water into chloroform, although less completely than the corresponding free acids. The extraction of the glucosiduronic acids from water by tetraheptylammonium chloride occurs by an ion-exchange process; extraction of the esters does not involve ion exchange. PMID:5075264

Dielectric study of aqueous solutions of sodium dodecyl sulfate in the frequency span 20 Hz to 2 MHz

NASA Astrophysics Data System (ADS)

Kadve, A. M.; Vankar, H. P.; Rana, V. A.

2017-05-01

Dielectric measurements were carried out for aqueous solutions of Sodium Dodecyl Sulfate (SDS) in the frequency span of 20 Hz to 2 MHz at 300.15 K temperature using precision LCR meter. Also the refractive indices were measured for the solutions at 300.15 K temperature using Abbe's refractometer. The measurements were done for ten different concentrations of SDS in distilled water. Determined values of complex permittivity as a function of frequency were used to evaluate other parameters like loss tangent and electric modulus for the liquid samples. The permittivity at optical frequency were also calculated from the measured refractive indices for the aqueous solutions. The effect of concentration variation of SDS in the aqueous solutions on the determined parameters is discussed.

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

Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

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

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactantmore » fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.« less

Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

DOEpatents

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-08-11

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

Liquid electrode

DOEpatents

Ekechukwu, Amy A.

1994-01-01

A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

Complexation Enhancement Drives Water-to-Oil Ion Transport: A Simulation Study

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

Qiao, Baofu; Ferru, Geoffroy; Ellis, Ross J.

We address the structures and energetics of ion solvation in aqueous and organic solutions to understand liquid-liquid ion transport. Atomistic molecular dynamics (MD) simulations with polarizable force field are performed to study the coordination transformations driving lanthanide (Ln(III)) and nitrate ion transport between aqueous and an alkylamide-oil solution. An enhancement of the coordination behavior in the organic phase is achieved in contrast with the aqueous solution. In particular, the coordination number of Ce3+ increases from 8.9 in the aqueous to 9.9 in the organic solutions (from 8 in the aqueous to 8.8 in the organic systems for Yb3+). Moreover, themore » local coordination environ ment changes dramatically. Potential of mean force calculations show that the Ln(III)-ligand coordination interaction strengths follow the order of Ln(III-)nitrate> Ln(III)-water>Ln(III)-DMDBTDMA. They increase 2-fold in the lipophilic environment in comparison to the aqueous phase, and we attribute this to the shedding of the outer solvation shell. Our findings highlight the importance of outer sphere interactions on the competitive solvation energetics that cause ions to migrate between immiscible phases; an essential ingredient for advancing important applications such as rare earth metal separations. Some open questions in simulating the coordination behavior of heavy metals are also addressed.« less

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).

Measurements of thermodynamic and optical properties of selected aqueous organic and organic-inorganic mixtures of atmospheric relevance.

PubMed

Lienhard, Daniel M; Bones, David L; Zuend, Andreas; Krieger, Ulrich K; Reid, Jonathan P; Peter, Thomas

2012-10-11

Atmospheric aerosol particles can exhibit liquid solution concentrations supersaturated with respect to the dissolved organic and inorganic species and supercooled with respect to ice. In this study, thermodynamic and optical properties of sub- and supersaturated aqueous solutions of atmospheric interest are presented. The density, refractive index, water activity, ice melting temperatures, and homogeneous ice freezing temperatures of binary aqueous solutions containing L(+)-tartaric acid, tannic acid, and levoglucosan and ternary aqueous solutions containing levoglucosan and one of the salts NH(4)HSO(4), (NH(4))(2)SO(4), and NH(4)NO(3) have been measured in the supersaturated concentration range for the first time. In addition, the density and refractive index of binary aqueous citric acid and raffinose solutions and the glass transition temperatures of binary aqueous L(+)-tartaric acid and levoglucosan solutions have been measured. The data presented here are derived from experiments on single levitated microdroplets and bulk solutions and should find application in thermodynamic and atmospheric aerosol models as well as in food science applications.

Selective separation of furfural and hydroxymethylfurfural from an aqueous solution using a supported hydrophobic deep eutectic solvent liquid membrane.

PubMed

Dietz, Carin H J T; Kroon, Maaike C; Di Stefano, Michela; van Sint Annaland, Martin; Gallucci, Fausto

2017-12-14

For the first time, 12 different supported deep eutectic solvent (DES) liquid membranes were prepared and characterized. These membranes consist of a polymeric support impregnated with a hydrophobic DES. First, the different membranes were characterized and their stability in water and air was determined. Subsequently, the supported DES liquid membranes were applied for the recovery of furfural (FF) and hydroxymethylfurfural (HMF) from aqueous solutions. The effects of substrate properties (e.g. pore size), DES properties (e.g. viscosity) and concentrations of FF and HMF in the feed phase on the observed diffusivities and permeabilities were assessed. It was found that the addition of DES enhances the transport of FF and HMF through the polymeric membrane support. In particular, the use of the DES consisting of thymol + lidocaine (in the molar ratio 2 : 1) impregnated in a polyethylene support resulted in enhanced transport for both FF and HMF, and is most interesting for (in situ) isolation of FF and HMF from aqueous solutions, e.g. in biorefinery processes.

Surface tensions of inorganic multicomponent aqueous electrolyte solutions and melts.

PubMed

Dutcher, Cari S; Wexler, Anthony S; Clegg, Simon L

2010-11-25

A semiempirical model is presented that predicts surface tensions (σ) of aqueous electrolyte solutions and their mixtures, for concentrations ranging from infinitely dilute solution to molten salt. The model requires, at most, only two temperature-dependent terms to represent surface tensions of either pure aqueous solutions, or aqueous or molten mixtures, over the entire composition range. A relationship was found for the coefficients of the equation σ = c(1) + c(2)T (where T (K) is temperature) for molten salts in terms of ion valency and radius, melting temperature, and salt molar volume. Hypothetical liquid surface tensions can thus be estimated for electrolytes for which there are no data, or which do not exist in molten form. Surface tensions of molten (single) salts, when extrapolated to normal temperatures, were found to be consistent with data for aqueous solutions. This allowed surface tensions of very concentrated, supersaturated, aqueous solutions to be estimated. The model has been applied to the following single electrolytes over the entire concentration range, using data for aqueous solutions over the temperature range 233-523 K, and extrapolated surface tensions of molten salts and pure liquid electrolytes: HCl, HNO(3), H(2)SO(4), NaCl, NaNO(3), Na(2)SO(4), NaHSO(4), Na(2)CO(3), NaHCO(3), NaOH, NH(4)Cl, NH(4)NO(3), (NH(4))(2)SO(4), NH(4)HCO(3), NH(4)OH, KCl, KNO(3), K(2)SO(4), K(2)CO(3), KHCO(3), KOH, CaCl(2), Ca(NO(3))(2), MgCl(2), Mg(NO(3))(2), and MgSO(4). The average absolute percentage error between calculated and experimental surface tensions is 0.80% (for 2389 data points). The model extrapolates smoothly to temperatures as low as 150 K. Also, the model successfully predicts surface tensions of ternary aqueous mixtures; the effect of salt-salt interactions in these calculations was explored.

Evolution of Spatial pH Distribution in Aqueous Solution induced by Atmospheric Pressure Plasma

NASA Astrophysics Data System (ADS)

Takahashi, Shigenori; Mano, Kakeru; Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu

2016-09-01

Discharge plasma at gas-liquid interface produces some active species, and then they affect chemical reactions in aqueous solution, where pH of aqueous solution is changed due to redox species. The pH change of aqueous solution is an important factor for chemical reactions. However, spatial pH distribution in a reactor during the discharge has not been clarified yet. Thus, this work focused on spatial pH distribution of aqueous solution when pulsed discharge plasma was generated from a copper electrode in gas phase to aqueous solution in a reactor. Experiments were conducted using positive unipolar pulsed power. The unipolar pulsed voltage at +8.0 kV was applied to the copper electrode and the bottom of the reactor was grounded. The size of the reactor was 80 mm wide, 10 mm deep, and 40 mm high. The electrode was set at distance of 2 mm from the solution surface. Anthocyanins were contained in the aqueous solution as a pH indicator. The change pH solution spread horizontally, and low pH region of 10 mm in depth was formed. After discharge for 10 minutes, the low pH region was diffused toward the bottom of the reactor. After discharge for 60 minutes, the pH of the whole solution decreased.

Honeycomb-like thin films of polystyrene-block-poly(2-vinylpyridine) embedded with gold or silver nanoparticles formed at the planer liquid/liquid interface.

PubMed

Wang, Di; Ma, Huihui; Chu, Chunxiao; Hao, Jingcheng; Liu, Hong-Guo

2013-07-15

Composite thin films of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) decorated with Au or Ag nanoclusters and nanoparticles were fabricated at the interfaces of chloroform solution of PS-b-P2VP and aqueous solutions of HAuCl4 or AgNO3. Transmission electron microscopy (TEM) investigations indicated that large area of a single-layer honeycomb structure was formed, which is composed of polygons (most of them are hexagons) whose walls look like spindles with the length of several hundreds of nanometers. Large amount of Au or Ag nanoparticles are embedded in the walls and the undersides of the honeycomb structures. The formation of these novel composite structures was attributed to the adsorption of block copolymer molecules and inorganic species of AuCl4(-) and Ag(+) ions at the liquid-liquid interface, the combination of the polymer molecules and the inorganic ions, and the self-assembly of the composite molecules. After UV-light irradiation and KBH4 aqueous solution treatment, the inorganic species were reduced completely, as confirmed by UV-vis spectra and X-ray photoelectron spectra. These composite films exhibited high catalytic activities for the reduction of 4-nitrophenol (4-NP) by KBH4 in aqueous solutions. Copyright © 2013 Elsevier Inc. All rights reserved.

SOLVENT EXTRACTION PROCESS FOR THE SEPARATION OF URANIUM AND THORIUM FROM PROTACTINIUM AND FISSION PRODUCTS

DOEpatents

Rainey, R.H.; Moore, J.G.

1962-08-14

A liquid-liquid extraction process was developed for recovering thorium and uranium values from a neutron irradiated thorium composition. They are separated from a solvent extraction system comprising a first end extraction stage for introducing an aqueous feed containing thorium and uranium into the system consisting of a plurality of intermediate extractiorr stages and a second end extractron stage for introducing an aqueous immiscible selective organic solvent for thorium and uranium in countercurrent contact therein with the aqueous feed. A nitrate iondeficient aqueous feed solution containing thorium and uranium was introduced into the first end extraction stage in countercurrent contact with the organic solvent entering the system from the second end extraction stage while intro ducing an aqueous solution of salting nitric acid into any one of the intermediate extraction stages of the system. The resultant thorium and uranium-laden organic solvent was removed at a point preceding the first end extraction stage of the system. (AEC)

Ditetraalkylammonium amino acid ionic liquids as CO₂ absorbents of high capacity.

PubMed

Ma, Jing-Wen; Zhou, Zheng; Zhang, Feng; Fang, Cheng-Gang; Wu, You-Ting; Zhang, Zhi-Bing; Li, Ai-Min

2011-12-15

By grafting butyl or ethyl onto tetramethylethylenediamine, quaternary ammonium salts with two positive charge centers were formed at the first step. Metathesis with Ag(2)O followed. Through neutralization with glycine, l-alanine, or valine, a series of new ditetraalkylammonium amino acid ionic liquids (DILs) for CO(2) capture were generated. The structures of DILs, as shown in Figure 1, were verified by using (1)H NMR and EA. These DILs were found to be of quite high viscosity which militated against their industrial application in CO(2) removal. Drawing on the experience of mixed amines' aqueous solutions, these DILs were blended with water or N-methyldiethanolamine (MDEA) aqueous solutions to act as special absorbents of CO(2). Using a Double-Tank Absorption System, the absorption performance of these DIL solutions was investigated in detail. The experimental results indicated that among the three aqueous solutions of DILs (20%, 40%, and 80 wt %), the solution of 40% DIL had a higher absorption rate of CO(2) than the other two, demonstrating the different effects of concentration and viscosity on the absorption. The solution of 40% DIL or the 15% DIL + 15% MDEA had much higher capacity for CO(2) than the corresponding monocation tetraalkylammonium AAILs, due to the special structure of the dication which could influence the solubility of CO(2) in the aqueous solution.

Crystal growth of sulfide materials from alkali polysulfide liquids

NASA Technical Reports Server (NTRS)

White, W. B.

1979-01-01

The fluids experiment system was designed for low temperature solution growth, nominally aqueous solution growth. The alkali polysulfides, compositions in the systems Na2S-S and K2S-S form liquids in the temperature range of 190 C to 400 C. These can be used as solvents for other important classes of materials such as transition metal and other sulfides which are not soluble in aqueous media. Among these materials are luminescent and electroluminescent crystals whose physical properties are sensitive functions of crystal perfection and which could, therefore, serve as test materials for perfection improvement under microgravity conditions.

Synthesis of unsymmetrical dimethylhydrazine oxalate from rejected liquid rocket propellant

NASA Astrophysics Data System (ADS)

Mu, Xiaogang; Yang, Jingjing; Zhang, Youzhi

2018-02-01

The rejected liquid propellant unsymmetrical dimethylhydrazine (UDMH) was converted to UDMH oxalate, which has commercial value. The UDMH oxalate structure and stability were investigated by the Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and ultraviolet-visible spectrophotometric analysis. The results indicate that UDMH oxalate has good thermal and aqueous solution stability, a melting point of 144 °C, an initial decomposition temperature of 180 °C, and a peak wavelength of UV in aqueous solution at λ = 204 nm. This disposal method of rejected UDMH is highly efficient and environmentally safe.

Development of structure in natural silk spinning and poly(vinyl alcohol) hydrogel formation

NASA Astrophysics Data System (ADS)

Willcox, Patricia Jeanene

This research involves the characterization of structure and structure formation in aqueous systems. Particularly, these studies investigate the effect of various processing variables on the structure formation that occurs upon conversion from aqueous solution to fiber or hydrogel. The two processes studied include natural silk fiber spinning and physical gelation of poly(vinyl alcohol), PVOH, in water. The techniques employed combine cryogenic technology for sample preparation and direct observation by transmission electron microscopy with electron diffraction, atomic force microscopy, optical rheometry, X-ray scattering and optical microscopy. In order to explore the full range of structure formation in natural silk spinning, studies are conducted in vivo and in vitro. In vivo structural investigations are accomplished through the cryogenic quenching and subsequent microtoming of live silk-spinning animals, Nephila clavipes (spider) and Bombyx mori (silkworm). Observations made using transmission electron microscopy, electron diffraction and atomic force microscopy indicate a cholesteric liquid crystalline mesophase of aqueous silk fibroin in both species. The mechanism of structure formation in solution is studied in vitro using optical rheometry on aqueous solutions made from regenerated Bombyx mori cocoon silk. Concentrated solutions exhibit birefringence under flow, with a wormlike conformation of the silk molecules in concentrated salt solution. Changes in salt concentration and pH of the aqueous silk solutions result in differing degrees of alignment and aggregation. These results suggest that structural control in the natural silk spinning process is accomplished by chemical manipulation of the electrostatic interactions and hydrogen bonding between chains. Application of cryogenic methods in transmission electron microscopy also provides a unique look at hydration-dependent structures in gels of poly(vinyl alcohol) produced by freeze-thaw processing. Morphologies ranging from circular pores to fibrillar networks are observed in gels formed from aqueous PVOH solutions subjected to cycles of freezing and thawing. These morphologies can be directly associated with the progressive nature of the mechanism of gelation as it proceeds from liquid-liquid phase separation to crystallization with increased cycling. A comparison of the structures produced by cycling and by aging suggests that there is a similarity in structural changes, but a superposition of the effects of cycling and aging is not possible.

Liquid electrode

DOEpatents

Ekechukwu, A.A.

1994-07-05

A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

Computational analysis of the solvation of coffee ingredients in aqueous ionic liquid mixtures† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6ra24736a Click here for additional data file.

PubMed Central

Zeindlhofer, Veronika; Khlan, Diana; Bica, Katharina

2017-01-01

In this paper, we investigate the solvation of coffee ingredients including caffeine, gallic acid as representative for phenolic compounds and quercetin as representative for flavonoids in aqueous mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate [C2mim][OAc] at various concentrations. Due to the anisotropy of the solutes we show that classical Kirkwood–Buff theory is not appropriate to study solvation effects with increasing ionic liquid content. However, excess coordination numbers as well as the mean residence time of solvent molecules at the surface of the solutes can be determined by Voronoi tessellation. Since the volume of the hydration shells is also available by this method, solvation free energies will be discussed as a function of the ionic liquid concentration to yield a physical meaningful picture of solvation for the anisotropic solutes. Hydrogen bonding capabilities of the solutes and their relevance for experimental extraction yields from spent coffee grounds are also discussed. PMID:28496974

Influence of Osmotic Drying with an Aqueous Poly(ethylene Glycol) Liquid Desiccant on Alumina Objects Gelcast with Gelatin

DOE PAGES

Hammel, E. C.; Campa, J. A.; Armbrister, C. E.; ...

2017-09-06

Gelcasting and liquid desiccant drying are novel forming and drying methods used to mitigate common issues associated with the fabrication of complex advanced ceramic objects. Here, the molecular weight and osmotic pressure of aqueous poly(ethylene glycol) (PEG) desiccant solutions were simultaneously varied to understand their influence on the net mass loss rates of gelcast alumina samples prepared using gelatin as a gelling agent. Additionally, the amount of PEG diffusion and water diffusion to and from the ceramic samples after 150 min of immersion in the liquid desiccant was correlated to the solution properties as was the final bulk density ofmore » the sintered samples. Furthermore, solutions with high molecular weight and low osmotic pressure resulted in low PEG gain and low water loss, while solutions with low molecular weight and high osmotic pressure resulted in high PEG gain and high water loss. In some cases, more than 40 wt% of the total water per sample was removed through the liquid desiccant drying process.« less

Influence of Osmotic Drying with an Aqueous Poly(ethylene Glycol) Liquid Desiccant on Alumina Objects Gelcast with Gelatin

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

Hammel, E. C.; Campa, J. A.; Armbrister, C. E.

Gelcasting and liquid desiccant drying are novel forming and drying methods used to mitigate common issues associated with the fabrication of complex advanced ceramic objects. Here, the molecular weight and osmotic pressure of aqueous poly(ethylene glycol) (PEG) desiccant solutions were simultaneously varied to understand their influence on the net mass loss rates of gelcast alumina samples prepared using gelatin as a gelling agent. Additionally, the amount of PEG diffusion and water diffusion to and from the ceramic samples after 150 min of immersion in the liquid desiccant was correlated to the solution properties as was the final bulk density ofmore » the sintered samples. Furthermore, solutions with high molecular weight and low osmotic pressure resulted in low PEG gain and low water loss, while solutions with low molecular weight and high osmotic pressure resulted in high PEG gain and high water loss. In some cases, more than 40 wt% of the total water per sample was removed through the liquid desiccant drying process.« less

Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

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

Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A., E-mail: anisimov@umd.edu

2014-08-21

A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid–liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid–liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H{sub 2}O-NaCl and H{sub 2}O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archermore » and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid–liquid transition. We elucidate the non-conserved nature of the order parameter (extent of “reaction” between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.« less

Ultrasensitive molecular detection using thermal conductance of a hydrophobic gold-water interface.

PubMed

Green, Andrew J; Alaulamie, Arwa A; Baral, Susil; Richardson, Hugh H

2013-09-11

The thermal conductance from a hydrophobic gold aqueous interface is measured with increasing solute concentration. A small amount of aqueous solute molecules (1 solute molecule in 550 water molecules) dramatically increases the heat dissipation into the surrounding liquid. This result is consistent with a thermal conductance that is limited by an interface interaction where minority aqueous components significantly alter the surface properties and heat transport through the interface. The increase in heat dissipation can be used to make an extremely sensitive molecular detector that can be scaled to give single molecule detection without amplification or utilizing fluorescence labels.

Liquid-liquid equilibria for water + ethanol + 2-methylpropyl ethanoate and water + ethanol + 1,2-dibromoethane at 298. 15 K

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

Solimo, H.N.; Barnes de Arreguez, N.G.

1994-01-01

Liquid-liquid equilibrium, distribution coefficients, and selectivities of the systems water + ethanol + 2-methylpropyl ethanoate or + 1,2-dibromoethane have been determined at 298.15 K in order to evaluate their suitability in preferentially extracting ethanol from aqueous solution. Tie-line data were satisfactorily correlated by the Othmer and Tobias method, and the plait point coordinates for the two systems were estimated. The experimental data was compared with the values calculated by the NRTL and UNIQUAC models. The water + ethanol + 2-methylpropyl ethanoate system was also compared with the values predicted by the UNIFAC model. Poor qualitative agreement was obtained with thesemore » models. From the experimental results, they can conclude that both solvents are inappropriate for ethanol extraction processes from aqueous solutions.« less

Water at Interfaces.

PubMed

Björneholm, Olle; Hansen, Martin H; Hodgson, Andrew; Liu, Li-Min; Limmer, David T; Michaelides, Angelos; Pedevilla, Philipp; Rossmeisl, Jan; Shen, Huaze; Tocci, Gabriele; Tyrode, Eric; Walz, Marie-Madeleine; Werner, Josephina; Bluhm, Hendrik

2016-07-13

The interfaces of neat water and aqueous solutions play a prominent role in many technological processes and in the environment. Examples of aqueous interfaces are ultrathin water films that cover most hydrophilic surfaces under ambient relative humidities, the liquid/solid interface which drives many electrochemical reactions, and the liquid/vapor interface, which governs the uptake and release of trace gases by the oceans and cloud droplets. In this article we review some of the recent experimental and theoretical advances in our knowledge of the properties of aqueous interfaces and discuss open questions and gaps in our understanding.

Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations.

PubMed

Pham, Tuan Anh; Ogitsu, Tadashi; Lau, Edmond Y; Schwegler, Eric

2016-10-21

Establishing an accurate and predictive computational framework for the description of complex aqueous solutions is an ongoing challenge for density functional theory based first-principles molecular dynamics (FPMD) simulations. In this context, important advances have been made in recent years, including the development of sophisticated exchange-correlation functionals. On the other hand, simulations based on simple generalized gradient approximation (GGA) functionals remain an active field, particularly in the study of complex aqueous solutions due to a good balance between the accuracy, computational expense, and the applicability to a wide range of systems. Such simulations are often performed at elevated temperatures to artificially "correct" for GGA inaccuracies in the description of liquid water; however, a detailed understanding of how the choice of temperature affects the structure and dynamics of other components, such as solvated ions, is largely unknown. To address this question, we carried out a series of FPMD simulations at temperatures ranging from 300 to 460 K for liquid water and three representative aqueous solutions containing solvated Na + , K + , and Cl - ions. We show that simulations at 390-400 K with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional yield water structure and dynamics in good agreement with experiments at ambient conditions. Simultaneously, this computational setup provides ion solvation structures and ion effects on water dynamics consistent with experiments. Our results suggest that an elevated temperature around 390-400 K with the PBE functional can be used for the description of structural and dynamical properties of liquid water and complex solutions with solvated ions at ambient conditions.

Influence of gold species (AuCl4(-) and AuCl2(-)) on self-assembly of PS-b-P2VP in solutions and morphology of composite thin films fabricated at the air/liquid interfaces.

PubMed

Zhao, Xingjuan; Wang, Qian; Zhang, Xiaokai; Lee, Yong-Ill; Liu, Hong-Guo

2016-01-21

Composite thin films doped with Au species were fabricated at an air/liquid interface via a series of steps, including the mass transfer of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) across the liquid/liquid interface between a DMF/CHCl3 solution and an aqueous solution containing either AuCl4(-) or AuCl2(-), self-assembly of PS-b-P2VP in a mixed DMF-water solution, and adsorption and further self-organization of the formed aggregates at the air/liquid interface. This is a new approach for fabricating composite polymer films and can be completed within a very short time. AuCl4(-) and AuCl2(-) ions were found to significantly influence the self-assembly behavior of the block copolymer and the morphologies of the composite films, leading to the formation of nanowire arrays and a foam structure at the air/liquid interface, respectively, which originated from rod-like micelles and microcapsules that had formed in the respective solutions. The effect of the metal complex was analyzed based on the packing parameters of the amphiphilic polymer molecules in different microenvironments and the interactions between the pyridine groups and the metal chloride anions. In addition, these composite thin films exhibited stable and durable performance as heterogeneous catalysts for the hydrogenation of nitroaromatics in aqueous solutions.

Degradation of α-Naphthol by Plasma in Aqueous Solution

NASA Astrophysics Data System (ADS)

Gao, Jin-zhang; Hu, Zhong-ai; Wang, Xiao-yan; Hou, Jing-guo; Lu, Xiao-quan; Kang, Jing-wan

2001-02-01

Degradation of α-naphthol induced by plasma in aqueous solution was investigated in different initial concentration with contact glow discharge electrolysis (CGDE). The results showed that the degradation of α-naphthol obeyed the first-rate law. Some of predominant products were analyzed by a high performance liquid chromatography (HPLC). A path of α-naphthol disappearance caused by plasma was proposed according to the detected intermediate products.

Polynuclear Speciation of Trivalent Cations near the Surface of an Electrolyte Solution

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

Bera, Mrinal K.; Antonio, Mark R.

Despite long-standing efforts, there is no agreed upon structural model for electrolyte solutions at air-liquid interfaces. We report the simultaneous detection of the near-surface and bulk coordination environments of a trivalent metal cation (europium) in an aqueous solution by use of X-ray absorption spectroscopy. Within the first few nanometers of the liquid surface, the cations exhibit oxygen coordination typical of inner-sphere hydration of an aquated Eu3+ cation. Beyond that, outer-sphere ion-ion correlations are observed that are otherwise not present in the bulk electrolyte. The combination of near-surface and bulk sensitivities to probe metal ion speciation in electrolyte solutions is achievedmore » by detecting electron-yield and X-ray fluorescence signals from an inverted pendant drop. The results provide new knowledge about the near-surface chemistry of aqueous solutions of relevance to aerosols and ion transport processes in chemical separations and biological systems.« less

Use of radiation in preparative chemistry

NASA Technical Reports Server (NTRS)

Philipp, W. H.; Marksik, S. J.; May, C. E.; Lad, R. A.

1971-01-01

A summary and updating of previous work on the use of radiation chemistry for the preparation of pure materials are presented. Work was chiefly concerned with the reduction of metal salts in solution to the free metal using 2 MeV electrons. Metals deposited from aqueous solution are copper, silver, zinc, cadmium, thallium, tin, lead, antimony, iron, nickel, cobalt, and palladium. Dry organic solvents were evaluated for the deposition of metals based on a study involving deposition of antimony from soltions of antimony (III) chloride. The use of organic liquids for the preparation of anhydrous metal halides is also presented. Reaction mechanisms for both organic liquids and aqueous system are discussed.

Dynamical properties in supercooling liquid of trehalose aqueous solution studied by Brillouin scattering

NASA Astrophysics Data System (ADS)

Shibata, Tomohiko; Tominaga, Ayane; Takayama, Haruki; Kojima, Seiji

2013-02-01

Brillouin scattering spectroscopy has been applied to study the dynamical properties of glass transition of trehalose aqueous solutions in a high-frequency gigahertz range and in the temperature range (-190°C ≤ T ≤ 100°C). The temperature variations of sound velocity and attenuation were accurately determined using the refractive index measured by a prism-coupling method. The temperature dependence of relaxation time of the structural relaxation process was determined by the Debye model. Its temperature dependence shows Arrhenius behavior in a liquid state. The parameters of Arrhenius law were also determined as a function of trehalose concentration.

Synergic effects in the extraction of paracetamol from aqueous NaCl solution by the binary mixtures of diethyl ether and low molecular weight primary alcohols

NASA Astrophysics Data System (ADS)

Nikolić, G. M.; Živković, J. V.; Atanasković, D. S.; Nikolić, M. G.

2013-12-01

Liquid-liquid extraction of paracetamol from aqueous NaCl solutions was performed with diethyl ether, 1-propanol, 1-butanol, isobutanol, 1-pentanol, and binary mixtures diethyl ether/1-propanol, diethyl ether/1-butanol, and diethyl ether/isobutanol. Among the pure solvents investigated in this study best extraction efficacy was obtained with 1-butanol. Synergic effects in the extraction with binary mixtures was investigated and compared with some other systems used for the extraction of poorly extractable compounds. Results obtained in this study may be of both fundamental and practical importance.

Liquid-Phase Adsorption Fundamentals.

ERIC Educational Resources Information Center

Cooney, David O.

1987-01-01

Describes an experiment developed and used in the unit operations laboratory course at the University of Wyoming. Involves the liquid-phase adsorption of an organic compound from aqueous solution on activated carbon, and is relevant to adsorption processes in general. (TW)

Superlubricity of a Mixed Aqueous Solution

NASA Astrophysics Data System (ADS)

Ma, Zhi-Zuo; Zhang, Chen-Hui; Luo, Jian-Bin; Lu, Xin-Chun; Wen, Shi-Zhu

2011-05-01

A super-low friction coefficient of 0.0028 is measured under a pressure of 300 MPa when the friction pair (the silicon nitride ball sliding on the silicate glass) is lubricated by the mixed aqueous solution of glycerol and boric acid. The morphorlogies of the hydroxylated glass plate are observed by an atomic force microscope (AFM) in deionized water, glycerol, boric acid and their mixed aqueous solution. Bonding peaks of the retained liquids adhered on the surface of the sliding track are detected by an infrared spectrum apparatus and a Raman spectrum apparatus. The mechanism of the superlubricity of the glycerol and boric acid mixed aqueous solution is discussed. It is deduced that the formation of the lubricant film has enough strength to support higher loads, the hydration effect offering the super lower shear resistance. Key words: superlubricity, water based lubricant, ultra-low friction

A liquid-phase microextraction method, combining a dual gauge microsyringe with a hollow fiber membrane, for the determination of organochlorine pesticides in aqueous solution by gas chromatography/ion trap mass spectrometry.

PubMed

Yan, Chih-Hao; Wu, Hui-Fen

2004-01-01

A liquid-phase microextraction (LPME) method has been demonstrated for the extraction and determination of organochlorine pesticides (OCPs) in aqueous solution. The method combines a dual gauge microsyringe with a hollow fiber membrane (LPME/DGM-HF) followed by detection by gas chromatography/ion trap mass spectrometry (GC/ITMS). The advantages include speed, low solvent and sample consumption, simplicity and ease of use. The extraction time, solvent selection, salt concentration and sample stirring rate have been investigated in order to optimize extraction efficiency. The viability is evaluated by measuring the linearity and detection limit of the five OCPs in aqueous solution. Detection linearity for the OCPs has been achieved over a range of concentrations between 1 and 500 microg/L (r2 > 0.930), with a detection limit of 0.1 microg/L for each OCP. Copyright 2004 John Wiley & Sons, Ltd.

Synthesis of 1,3-Dimethylimidazolium Chloride and Volumetric Property Investigations of Its Aqueous Solution

NASA Astrophysics Data System (ADS)

Dong, L.; Zheng, D. X.; Wei, Z.; Wu, X. H.

2009-10-01

By investigating the vapor pressure of the solvent and the affinity between ionic liquids (ILs) and the solvent, it is proposed that 1,3-dimethylimidazolium chloride ([Mmim]Cl) has the potential to be used as a novel absorbent species with the absorption cycle working fluid. Adopting a high-pressure reaction kettle, the method of gas-liquid phase reaction was used to synthesize [Mmim]Cl under the conditions of 348.15 K and 0.7 MPa. The densities of [Mmim]Cl aqueous solutions were measured for mass fractions in the range from 20% to 90% at 293.15 K, 298.15 K, 303.15 K, 308.15 K, 313.15 K, and 318.15 K with a digital vibrating-tube densimeter. The excess volume, the apparent molar volume, the partial molar volume, and the apparent molar expansibility of this system were investigated, and the influences of variations of the cation and anion on the density of several IL aqueous solutions are discussed.

A "by-productless" cellulose foaming agent for use in imidazolium ionic liquids.

PubMed

Scott, Janet L; Unali, Gianfranco; Perosa, Alvise

2011-03-14

Cellulose foams, or sponges, are produced from solutions in ionic liquids by the aqueous acid mediated decomposition of 1-alkyl-3-methylimidazolium-2-carboxylates, where the alkyl group and acid may be selected such that the by-product is the ionic liquid solvent: a by-productless foaming.

Method for removing trace pollutants from aqueous solutions

DOEpatents

Silver, G.L.

A method of substantially removing a trace metallic contaminant from a liquid containing the same comprises: adding an oxidizing agent to a liquid containing a trace amount of a metallic contaminant of a concentration of up to about 0.1 ppM, and separating the homogeneously precipitated product from the liquid.

Picoliter Drop-On-Demand Dispensing for Multiplex Liquid Cell Transmission Electron Microscopy

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

Patterson, Joseph P.; Parent, Lucas R.; Cantlon, Joshua

2016-05-03

Abstract Liquid cell transmission electron microscopy (LCTEM) provides a unique insight into the dynamics of nanomaterials in solution. Controlling the addition of multiple solutions to the liquid cell remains a key hurdle in our ability to increase throughput and to study processes dependent on solution mixing including chemical reactions. Here, we report that a piezo dispensing technique allows for mixing of multiple solutions directly within the viewing area. This technique permits deposition of 50 pL droplets of various aqueous solutions onto the liquid cell window, before assembly of the cell in a fully controlled manner. This proof-of-concept study highlights themore » great potential of picoliter dispensing in combination with LCTEM for observing nanoparticle mixing in the solution phase and the creation of chemical gradients.« less

Investigation of the Matrix Effect on the Accuracy of Quantitative Analysis of Trace Metals in Liquids Using Laser-Induced Breakdown Spectroscopy with Solid Substrates.

PubMed

Xiu, Junshan; Dong, Lili; Qin, Hua; Liu, Yunyan; Yu, Jin

2016-12-01

The detection limit of trace metals in liquids has been improved greatly by laser-induced breakdown spectroscopy (LIBS) using solid substrate. A paper substrate and a metallic substrate were used as a solid substrate for the detection of trace metals in aqueous solutions and viscous liquids (lubricating oils) respectively. The matrix effect on quantitative analysis of trace metals in two types of liquids was investigated. For trace metals in aqueous solutions using paper substrate, the calibration curves established for pure solutions and mixed solutions samples presented large variation on both the slope and the intercept for the Cu, Cd, and Cr. The matrix effects among the different elements in mixed solutions were observed. However, good agreement was obtained between the measured and known values in real wastewater. For trace metals in lubricating oils, the matrix effect between the different oils is relatively small and reasonably negligible under the conditions of our experiment. A universal calibration curve can be established for trace metals in different types of oils. The two approaches are verified that it is possible to develop a feasible and sensitive method with accuracy results for rapid detection of trace metals in industrial wastewater and viscous liquids by laser-induced breakdown spectroscopy. © The Author(s) 2016.

Plexcitonics: Coupled and Plasmon-Exciton Systems with Tailorable Properties

DTIC Science & Technology

2013-11-14

demonstrated efficient steam generation from aqueous nanoparticles solutions without heating the bulk volume of the liquid. Application in ethanol ...solutions without heating the bulk volume of the liquid. Applications in ethanol distillation and sanitation have been demonstrated. Key Accomplishments...nanoparticle surface. This state-selective population of adsorbate resonances could be exploited to prepare reactants in specific states on nanoparticle

Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations

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

Pham, Tuan Anh; Ogitsu, Tadashi; Lau, Edmond Y.

Establishing an accurate and predictive computational framework for the description of complex aqueous solutions is an ongoing challenge for density functional theory based first-principles molecular dynamics (FPMD) simulations. In this context, important advances have been made in recent years, including the development of sophisticated exchange-correlation functionals. On the other hand, simulations based on simple generalized gradient approximation (GGA) functionals remain an active field, particularly in the study of complex aqueous solutions due to a good balance between the accuracy, computational expense, and the applicability to a wide range of systems. In such simulations we often perform them at elevated temperaturesmore » to artificially “correct” for GGA inaccuracies in the description of liquid water; however, a detailed understanding of how the choice of temperature affects the structure and dynamics of other components, such as solvated ions, is largely unknown. In order to address this question, we carried out a series of FPMD simulations at temperatures ranging from 300 to 460 K for liquid water and three representative aqueous solutions containing solvated Na +, K +, and Cl - ions. We show that simulations at 390–400 K with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional yield water structure and dynamics in good agreement with experiments at ambient conditions. Simultaneously, this computational setup provides ion solvation structures and ion effects on water dynamics consistent with experiments. These results suggest that an elevated temperature around 390–400 K with the PBE functional can be used for the description of structural and dynamical properties of liquid water and complex solutions with solvated ions at ambient conditions.« less

Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations

DOE PAGES

Pham, Tuan Anh; Ogitsu, Tadashi; Lau, Edmond Y.; ...

2016-10-17

Establishing an accurate and predictive computational framework for the description of complex aqueous solutions is an ongoing challenge for density functional theory based first-principles molecular dynamics (FPMD) simulations. In this context, important advances have been made in recent years, including the development of sophisticated exchange-correlation functionals. On the other hand, simulations based on simple generalized gradient approximation (GGA) functionals remain an active field, particularly in the study of complex aqueous solutions due to a good balance between the accuracy, computational expense, and the applicability to a wide range of systems. In such simulations we often perform them at elevated temperaturesmore » to artificially “correct” for GGA inaccuracies in the description of liquid water; however, a detailed understanding of how the choice of temperature affects the structure and dynamics of other components, such as solvated ions, is largely unknown. In order to address this question, we carried out a series of FPMD simulations at temperatures ranging from 300 to 460 K for liquid water and three representative aqueous solutions containing solvated Na +, K +, and Cl - ions. We show that simulations at 390–400 K with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional yield water structure and dynamics in good agreement with experiments at ambient conditions. Simultaneously, this computational setup provides ion solvation structures and ion effects on water dynamics consistent with experiments. These results suggest that an elevated temperature around 390–400 K with the PBE functional can be used for the description of structural and dynamical properties of liquid water and complex solutions with solvated ions at ambient conditions.« less

Ionic liquid-anionic surfactant based aqueous two-phase extraction for determination of antibiotics in honey by high-performance liquid chromatography.

PubMed

Yang, Xiao; Zhang, Shaohua; Yu, Wei; Liu, Zhongling; Lei, Lei; Li, Na; Zhang, Hanqi; Yu, Yong

2014-06-01

An ionic liquid-anionic surfactant based aqueous two-phase extraction was developed and applied for the extraction of tetracycline, oxytetracycline and chloramphenicol in honey. The honey sample was mixed with Na2EDTA aqueous solution. The sodium dodecyl sulfate, ionic liquid 1-octyl-3-methylimidazolium bromide and sodium chloride were added in the mixture. After the resulting mixture was ultrasonically shaken and centrifuged, the aqueous two phase system was formed and analytes were extracted into the upper phase. The parameters affecting the extraction efficiency, such as the volume of ionic liquid, the category and amount of salts, sample pH value, extraction time and temperature were investigated. The limits of detection of tetracycline, oxytetracycline and chloramphenicol were 5.8, 8.2 and 4.2 μg kg(-1), respectively. When the present method was applied to the analysis of real honey samples, the recoveries of analytes ranged from 85.5 to 110.9% and relative standard deviations were lower than 6.9%. Copyright © 2014 Elsevier B.V. All rights reserved.

Melting of the precipitated ice IV in LiCl aqueous solution and polyamorphism of water.

PubMed

Mishima, Osamu

2011-12-08

Melting of the precipitated ice IV in supercooled LiCl-H(2)O solution was studied in the range of 0-0.6 MPa and 160-270 K. Emulsified solution was used to detect this metastable transition. Ice IV was precipitated from the aqueous solution of 2.0 mol % LiCl (or 4.8 mol % LiCl) in each emulsion particle at low-temperature and high-pressure conditions, and the emulsion was decompressed at different temperatures. The melting of ice IV was detected from the temperature change of the emulsified sample during the decompression. There was an apparently sudden change in the slope of the ice IV melting curve (liquidus) in the pressure-temperature diagram. At the high-pressure and high-temperature side of the change, the solute-induced freezing point depression was observed. At the low-pressure and low-temperature side, ice IV transformed into ice Ih on the decompression, and the transition was almost unrelated to the concentration of LiCl. These experimental results were roughly explained by the presumed existence of two kinds of liquid water (low-density liquid water and high-density liquid water), or polyamorphism in water, and by the simple assumption that LiCl dissolved maily in high-density liquid water. © 2011 American Chemical Society

Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods

NASA Astrophysics Data System (ADS)

Farahmand, Farnaz; Ghasemzadeh, Bahar; Naseri, Abdolhossein

2018-01-01

An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40 μg mL- 1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08 μg mL- 1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.

Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods.

PubMed

Farahmand, Farnaz; Ghasemzadeh, Bahar; Naseri, Abdolhossein

2018-01-05

An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40μg mL -1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08μg mL -1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct extraction of genomic DNA from maize with aqueous ionic liquid buffer systems for applications in genetically modified organisms analysis.

PubMed

Gonzalez García, Eric; Ressmann, Anna K; Gaertner, Peter; Zirbs, Ronald; Mach, Robert L; Krska, Rudolf; Bica, Katharina; Brunner, Kurt

2014-12-01

To date, the extraction of genomic DNA is considered a bottleneck in the process of genetically modified organisms (GMOs) detection. Conventional DNA isolation methods are associated with long extraction times and multiple pipetting and centrifugation steps, which makes the entire procedure not only tedious and complicated but also prone to sample cross-contamination. In recent times, ionic liquids have emerged as innovative solvents for biomass processing, due to their outstanding properties for dissolution of biomass and biopolymers. In this study, a novel, easily applicable, and time-efficient method for the direct extraction of genomic DNA from biomass based on aqueous-ionic liquid solutions was developed. The straightforward protocol relies on extraction of maize in a 10 % solution of ionic liquids in aqueous phosphate buffer for 5 min at room temperature, followed by a denaturation step at 95 °C for 10 min and a simple filtration to remove residual biopolymers. A set of 22 ionic liquids was tested in a buffer system and 1-ethyl-3-methylimidazolium dimethylphosphate, as well as the environmentally benign choline formate, were identified as ideal candidates. With this strategy, the quality of the genomic DNA extracted was significantly improved and the extraction protocol was notably simplified compared with a well-established method.

An automated system for liquid-liquid extraction in monosegmented flow analysis

PubMed Central

Facchin, Ileana; Pasquini, Celio

1997-01-01

An automated system to perform liquid-liquid extraction in monosegmented flow analysis is described. The system is controlled by a microcomputer that can track the localization of the aqueous monosegmented sample in the manifold. Optical switches are employed to sense the gas-liquid interface of the air bubbles that define the monosegment. The logical level changes, generated by the switches, are flagged by the computer through a home-made interface that also contains the analogue-to-digital converter for signal acquisition. The sequence of operations, necessary for a single extraction or for concentration of the analyte in the organic phase, is triggered by these logical transitions. The system was evaluated for extraction of Cd(II), Cu(II) and Zn(II) and concentration of Cd(II) from aqueous solutions at pH 9.9 (NH3/NH4Cl buffer) into chloroform containing PAN (1-(2-pyridylazo)-2-naphthol) . The results show a mean repeatability of 3% (rsd) for a 2.0 mg l-1 Cd(II) solution and a linear increase of the concentration factor for a 0.5mg l-1 Cd(II) solution observed for up to nine extraction cycles. PMID:18924792

Removal of actinide elements from liquid scintillation cocktail wastes using liquid-liquid extraction and demulsification techniques

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

Foltz, K.; Landsberger, S.; Srinivasan, B.

1994-12-31

For many years liquid scintillation cocktail (LSC) wastes have been generated and stored at Argonne National Laboratory (ANL). These wastes are stored in thousands of 10--20 m scintillation vials, many of which contain elements with Z > 88. Because storage space is limited, disposal of this waste is pressing. These wastes could be commercially incinerated if the radionuclides with Z>88 are reduced to sufficiently low levels. However, there is currently no deminimus level for these radionuclides, and separation techniques are still being tested. The University of Illinois is conducting experiments to separate radionuclides with Z > 88 from simulated LSCmore » wastes by using liquid-liquid extraction (LLX) and demulsification techniques. The actinide elements are removed from the LSC by extraction into an aqueous phase after the cocktail has been demulsified. The aqueous and organic phases are separated and the organic phase, now free from radionuclides with Z > 88, can be sent to a commercial incineration facility. The aqueous phase may be treated and disposed of using existing techniques. The LLX separation techniques used solutions of sodium oxalate, aluminum nitrate, and tetrasodium EDTA at varying concentrations. These extractants were mixed with the simulated waste in a 1:1 volume ratio. Using 1.0M Na{sub 4} EDTA salt solutions, decontamination ratios as high as 230 were achieved.« less

Calorimetric study of water's two glass transitions in the presence of LiCl

PubMed Central

Ruiz, Guadalupe N.; Amann-Winkel, Katrin; Bove, Livia E.; Corti, Horacio R.

2018-01-01

A DSC study of dilute glassy LiCl aqueous solutions in the water-dominated regime provides direct evidence of a glass-to-liquid transition in expanded high density amorphous (eHDA)-type solutions. Similarly, low density amorphous ice (LDA) exhibits a glass transition prior to crystallization to ice Ic. Both glass transition temperatures are independent of the salt concentration, whereas the magnitude of the heat capacity increase differs. By contrast to pure water, the glass transition endpoint for LDA can be accessed in LiCl aqueous solutions above 0.01 mole fraction. Furthermore, we also reveal the endpoint for HDA's glass transition, solving the question on the width of both glass transitions. This suggests that both equilibrated HDL and LDL can be accessed in dilute LiCl solutions, supporting the liquid–liquid transition scenario to understand water's anomalies. PMID:29442107

A shell-resolved analysis of preferential solvation of coffee ingredients in aqueous mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate

NASA Astrophysics Data System (ADS)

Zeindlhofer, Veronika; Berger, Magdalena; Steinhauser, Othmar; Schröder, Christian

2018-05-01

Ionic liquids increase the solubility of various coffee ingredients in aqueous solution but little is known about the underlying mechanism. Kirkwood-Buff integrals as well as the potential of mean force indicate that the imidazolium cations are accumulated at the surface of the solutes, removing water molecules from the solute surface. Although hydrogen bonding of the anions to hydroxy groups of the solutes can be detected, their concentration at the surface is less enhanced compared to the cations. The decomposition into solvation shells by Voronoi tessellation reveals that structural features are only observed in the first solvation shell. Nevertheless, the depletion of water and the excess concentration of the ions and, in particular, of the cations are visible in the next solvation shells as well. Therefore, classical arguments of hydrotropic theory fail to explain this behavior.

Lattice model for water-solute mixtures.

PubMed

Furlan, A P; Almarza, N G; Barbosa, M C

2016-10-14

A lattice model for the study of mixtures of associating liquids is proposed. Solvent and solute are modeled by adapting the associating lattice gas (ALG) model. The nature of interaction of solute/solvent is controlled by tuning the energy interactions between the patches of ALG model. We have studied three set of parameters, resulting in, hydrophilic, inert, and hydrophobic interactions. Extensive Monte Carlo simulations were carried out, and the behavior of pure components and the excess properties of the mixtures have been studied. The pure components, water (solvent) and solute, have quite similar phase diagrams, presenting gas, low density liquid, and high density liquid phases. In the case of solute, the regions of coexistence are substantially reduced when compared with both the water and the standard ALG models. A numerical procedure has been developed in order to attain series of results at constant pressure from simulations of the lattice gas model in the grand canonical ensemble. The excess properties of the mixtures, volume and enthalpy as the function of the solute fraction, have been studied for different interaction parameters of the model. Our model is able to reproduce qualitatively well the excess volume and enthalpy for different aqueous solutions. For the hydrophilic case, we show that the model is able to reproduce the excess volume and enthalpy of mixtures of small alcohols and amines. The inert case reproduces the behavior of large alcohols such as propanol, butanol, and pentanol. For the last case (hydrophobic), the excess properties reproduce the behavior of ionic liquids in aqueous solution.

Superposition of Translational and Rotational Motions under Self-Propulsion of Liquid Marbles Filled with Aqueous Solutions of Camphor.

PubMed

Bormashenko, Edward; Frenkel, Mark; Bormashenko, Yelena; Chaniel, Gilad; Valtsifer, Viktor; Binks, Bernard P

2017-11-21

Self-locomotion of liquid marbles, coated with lycopodium or fumed fluorosilica powder, filled with a saturated aqueous solution of camphor and placed on a water/vapor interface is reported. Self-propelled marbles demonstrated a complicated motion, representing a superposition of translational and rotational motions. Oscillations of the velocity of the center of mass and the angular velocity of marbles, occurring in the antiphase, were registered and explained qualitatively. Self-propulsion occurs because of the Marangoni solutocapillary flow inspired by the adsorption of camphor (evaporated from the liquid marble) by the water surface. Scaling laws describing translational and rotational motions are proposed and checked. The rotational motion of marbles arises from the asymmetry of the field of the Marangoni stresses because of the adsorption of camphor evaporated from marbles.

A Structural Study of Escherichia coli Cells Using an In Situ Liquid Chamber TEM Technology.

PubMed

Wang, Yibing; Chen, Xin; Cao, Hongliang; Deng, Chao; Cao, Xiaodan; Wang, Ping

2015-01-01

Studying cell microstructures and their behaviors under living conditions has been a challenging subject in microbiology. In this work, in situ liquid chamber TEM was used to study structures of Escherichia coli cells in aqueous solutions at a nanometer-scale resolution. Most of the cells remained intact under electron beam irradiation, and nanoscale structures were observed during the TEM imaging. The analysis revealed structures of pili surrounding the E. coli cells; the movements of the pili in the liquid were also observed during the in situ tests. This technology also allowed the observation of features of the nucleoid in the E. coli cells. Overall, in situ TEM can be applied as a valuable tool to study real-time microscopic structures and processes in microbial cells residing in native aqueous solutions.

Application of ionic liquids based enzyme-assisted extraction of chlorogenic acid from Eucommia ulmoides leaves.

PubMed

Liu, Tingting; Sui, Xiaoyu; Li, Li; Zhang, Jie; Liang, Xin; Li, Wenjing; Zhang, Honglian; Fu, Shuang

2016-01-15

A new approach for ionic liquid based enzyme-assisted extraction (ILEAE) of chlorogenic acid (CGA) from Eucommia ulmoides is presented in which enzyme pretreatment was used in ionic liquids aqueous media to enhance extraction yield. For this purpose, the solubility of CGA and the activity of cellulase were investigated in eight 1-alkyl-3-methylimidazolium ionic liquids. Cellulase in 0.5 M [C6mim]Br aqueous solution was found to provide better performance in extraction. The factors of ILEAE procedures including extraction time, extraction phase pH, extraction temperatures and enzyme concentrations were investigated. Moreover, the novel developed approach offered advantages in term of yield and efficiency compared with other conventional extraction techniques. Scanning electronic microscopy of plant samples indicated that cellulase treated cell wall in ionic liquid solution was subjected to extract, which led to more efficient extraction by reducing mass transfer barrier. The proposed ILEAE method would develope a continuous process for enzyme-assisted extraction including enzyme incubation and solvent extraction process. In this research, we propose a novel view for enzyme-assisted extraction of plant active component, besides concentrating on enzyme facilitated cell wall degradation, focusing on improvement of bad permeability of ionic liquids solutions. Copyright © 2015 Elsevier B.V. All rights reserved.

Shape-transformable liquid metal nanoparticles in aqueous solution† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc00057j Click here for additional data file.

PubMed Central

Lin, Yiliang; Liu, Yang

2017-01-01

Stable suspensions of eutectic gallium indium (EGaIn) liquid metal nanoparticles form by probe-sonicating the metal in an aqueous solution. Positively-charged molecular or macromolecular surfactants in the solution, such as cetrimonium bromide or lysozyme, respectively, stabilize the suspension by interacting with the negative charges of the surface oxide that forms on the metal. The liquid metal breaks up into nanospheres via sonication, yet can transform into rods of gallium oxide monohydroxide (GaOOH) via moderate heating in solution either during or after sonication. Whereas heating typically drives phase transitions from solid to liquid (via melting), here heating drives the transformation of particles from liquid to solid via oxidation. Interestingly, indium nanoparticles form during the process of shape transformation due to the selective removal of gallium. This dealloying provides a mechanism to create indium nanoparticles at temperatures well below the melting point of indium. To demonstrate the versatility, we show that it is possible to shape transform and dealloy other alloys of gallium including ternary liquid metal alloys. Scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS) mapping, and X-ray diffraction (XRD) confirm the dealloying and transformation mechanism. PMID:28580116

Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions.

PubMed

Walker, Rachel L; Searles, Keith; Willard, Jesse A; Michelsen, Rebecca R H

2013-12-28

Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphology allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.

Thermodynamic properties of potassium chloride aqueous solutions

NASA Astrophysics Data System (ADS)

Zezin, Denis; Driesner, Thomas

2017-04-01

Potassium chloride is a ubiquitous salt in natural fluids, being the second most abundant dissolved salt in many geological aqueous solutions after sodium chloride. It is a simple solute and strong electrolyte easily dissociating in water, however the thermodynamic properties of KCl aqueous solutions were never correlated with sufficient accuracy for a wide range of physicochemical conditions. In this communication we propose a set of parameters for a Pitzer-type model which allows calculation of all necessary thermodynamic properties of KCl solution, namely excess Gibbs free energy and derived activity coefficient, apparent molar enthalpy, heat capacity and volume, as well as osmotic coefficient and activity of water in solutions. The system KCl-water is one of the best studied aqueous systems containing electrolytes. Although extensive experimental data were collected for thermodynamic properties of these solutions over the years, the accurate volumetric data became available only recently, thus making possible a complete thermodynamic formulation including a pressure dependence of excess Gibbs free energy and derived properties of the KCl-water liquids. Our proposed model is intended for calculation of major thermodynamic properties of KCl aqueous solutions at temperatures ranging from freezing point of a solution to 623 K, pressures ranging from saturated water vapor up to 150 MPa, and concentrations up to the salt saturation. This parameterized model will be further implemented in geochemical software packages and can facilitate the calculation of aqueous equilibrium for reactive transport codes.

Continuous air agglomeration method for high carbon fly ash beneficiation

DOEpatents

Gray, McMahon L.; Champagne, Kenneth J.; Finseth, Dennis H.

2000-01-01

The carbon and mineral components of fly ash are effectively separated by a continuous air agglomeration method, resulting in a substantially carboree mineral stream and a highly concentrated carbon product. The method involves mixing the fly ash comprised of carbon and inorganic mineral matter with a liquid hydrocarbon to form a slurry, contacting the slurry with an aqueous solution, dispersing the hydrocarbon slurry into small droplets within the aqueous solution by mechanical mixing and/or aeration, concentrating the inorganic mineral matter in the aqueous solution, agglomerating the carbon and hydrocarbon in the form of droplets, collecting the droplets, separating the hydrocarbon from the concentrated carbon product, and recycling the hydrocarbon.

A Study of the Skin Absorption of Ethylbenzene in Man

PubMed Central

Dutkiewicz, Tadeusz; Tyras, Halina

1967-01-01

The absorption of ethylbenzene through the skin of the hand and the forearm in men was investigated experimentally. Both the absorption of liquid ethylbenzene and the absorption from aqueous solutions were studied. The rate of absorption of liquid ethylbenzene was 22 to 33 mg./cm.2/hr, and the rates from aqueous solutions were 118 and 215 μg./cm.2/hr from mean concentrations of 112 and 156 mg./litre. The mandelic acid excreted in urine was equivalent to about 4·6% of the absorbed dose—much less than after lung absorption. Urinary mandelic acid does not provide a reliable index of absorption when there is simultaneous skin and lung exposure. PMID:6073092

Process for the combined removal of SO.sub.2 and NO.sub.x from flue gas

DOEpatents

Chang, Shih-Ger; Liu, David K.; Griffiths, Elizabeth A.; Littlejohn, David

1988-01-01

The present invention in one aspect relates to a process for the simultaneous removal of NO.sub.x and SO.sub.2 from a fluid stream comprising mixtures thereof and in another aspect relates to the separation, use and/or regeneration of various chemicals contaminated or spent in the process and which includes the steps of: (A) contacting the fluid stream at a temperature of between about 105.degree. and 180.degree. C. with a liquid aqueous slurry or solution comprising an effective amount of an iron chelate of an amino acid moiety having at least one --SH group; (B) separating the fluid stream from the particulates formed in step (A) comprising the chelate of the amino acid moiety and fly ash; (C) washing and separating the particulates of step (B) with an aqueous solution having a pH value of between about 5 to 8; (D) subsequently washing and separating the particulates of step (C) with a strongly acidic aqueous solution having a pH value of between about 1 to 3; (E) washing and separating the particulates of step (D) with an basic aqueous solution having a pH value of between about 9 to 12; (F) optionally adding additional amino acid moiety, iron (II) and alkali to the aqueous liquid from step (D) to produce an aqueous solution or slurry similar to that in step (A) having a pH value of between about 4 to 12; and (G) recycling the aqueous slurry of step (F) to the contacting zone of step (A). Steps (D) and (E) can be carried out in the reverse sequence, however the preferred order is (D) and then (E). In another preferred embodiment the present invention provides a process for the removal of NO.sub.x, SO.sub.2 and particulates from a fluid stream which includes the steps of (A) injecting into a reaction zone an aqueous solution itself comprising (i) an amino acid moiety selected from those described above; (ii) iron (II) ion; and (iii) an alkali, wherein the aqueous solution has a pH of between about 4 and 11; followed by solids separation and washing as is described in steps (B), (C), (D) and (E) above. The overall process is useful to reduce acid rain components from combustion gas sources.

Simultaneous determination of bromhexine hydrochloride and methyl and propyl p-hydroxybenzoate and determination of dextromethorphan hydrobromide in cough-cold syrup by high-performance liquid chromatography.

PubMed

Rauha, J P; Salomies, H; Aalto, M

1996-11-01

Liquid chromatographic methods were developed for the determination of bromhexine hydrochloride, methyl p-hydroxybenzoate and propyl p-hydroxybenzoate (method A) and dextromethorphan hydrobromide (method B) in cough-cold syrup formulations. Reversed-phase analytical columns (150 mm x 3.9 mm i.d.) were used with (A) C18 and (B) phenyl as stationary phases and mixtures of (A) acetonitrile and aqueous 15 mM triethylamine solution (43:57) and (B) methanol and aqueous 3% ammonium formate buffer solution (53:47) as mobile phases at a flow rate of 1.0 ml min-1. Both aqueous components were adjusted to pH 3.9. UV detection of analytes was at (A) 245 nm and (B) 278 nm. In both methods, the time required for an HPLC run giving good separations and recoveries was less than 8 min.

Sorption of carboxylic acid from carboxylic salt solutions at PHS close to or above the pK.sub.a of the acid, with regeneration with an aqueous solution of ammonia or low-molecular-weight alkylamine

DOEpatents

King, C. Judson; Tung, Lisa A.

1992-01-01

Carboxylic acids are sorbed from aqueous feedstocks at pHs close to or above the acids' pH.sub.a into a strongly basic organic liquid phase or onto a basic solid adsorbent or moderately basic ion exchange resin. the acids are freed from the sorbent phase by treating it with aqueous alkylamine or ammonia thus forming an alkylammonium or ammonium carobxylate which dewatered and decomposed to the desired carboxylic acid and the alkylamine or ammonia.

An isotherm-based thermodynamic model of multicomponent aqueous solutions, applicable over the entire concentration range.

PubMed

Dutcher, Cari S; Ge, Xinlei; Wexler, Anthony S; Clegg, Simon L

2013-04-18

In previous studies (Dutcher et al. J. Phys. Chem. C 2011, 115, 16474-16487; 2012, 116, 1850-1864), we derived equations for the Gibbs energy, solvent and solute activities, and solute concentrations in multicomponent liquid mixtures, based upon expressions for adsorption isotherms that include arbitrary numbers of hydration layers on each solute. In this work, the long-range electrostatic interactions that dominate in dilute solutions are added to the Gibbs energy expression, thus extending the range of concentrations for which the model can be used from pure liquid solute(s) to infinite dilution in the solvent, water. An equation for the conversion of the reference state for solute activity coefficients to infinite dilution in water has been derived. A number of simplifications are identified, notably the equivalence of the sorption site parameters r and the stoichiometric coefficients of the solutes, resulting in a reduction in the number of model parameters. Solute concentrations in mixtures conform to a modified Zdanovskii-Stokes-Robinson mixing rule, and solute activity coefficients to a modified McKay-Perring relation, when the effects of the long-range (Debye-Hückel) term in the equations are taken into account. Practical applications of the equations to osmotic and activity coefficients of pure aqueous electrolyte solutions and mixtures show both satisfactory accuracy from low to high concentrations, together with a thermodynamically reasonable extrapolation (beyond the range of measurements) to extreme concentration and to the pure liquid solute(s).

Monte Carlo track-structure calculations for aqueous solutions containing biomolecules

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

Turner, J.E.; Hamm, R.N.; Ritchie, R.H.

1993-10-01

Detailed Monte Carlo calculations provide a powerful tool for understanding mechanisms of radiation damage to biological molecules irradiated in aqueous solution. This paper describes the computer codes, OREC and RADLYS, which have been developed for this purpose over a number of years. Some results are given for calculations of the irradiation of pure water. comparisons are presented between computations for liquid water and water vapor. Detailed calculations of the chemical yields of several products from X-irradiated, oxygen-free glycylglycine solutions have been performed as a function of solute concentration. Excellent agreement is obtained between calculated and measured yields. The Monte Carlomore » analysis provides a complete mechanistic picture of pathways to observed radiolytic products. This approach, successful with glycylglycine, will be extended to study the irradiation of oligonucleotides in aqueous solution.« less

Method for treating liquid wastes

DOEpatents

Katti, K.V.; Volkert, W.A.; Singh, P.; Ketring, A.R.

1995-12-26

The method of treating liquid waste in a media is accomplished by exposing the media to phosphinimines and sequestering {sup 99}Tc from the media by the phosphinimine (PN) functionalities. The system for treating the liquid waste in the media includes extraction of {sup 99}TcO{sub 4}{sup {minus}} from aqueous solutions into organic solvents or mixed organic/polar media, extraction of {sup 99}Tc from solutions on a solid matrix by using a container containing PN functionalities on solid matrices including an inlet and outlet for allowing flow of media through an immobilized phosphinimine ligand system contained within the container. Also, insoluble suspensions of phosphinimine functionalities on solid matrices in liquid solutions or present on supported liquid membranes (SLM) can be used to sequester {sup 99}Tc from those liquids. 6 figs.

Method for treating liquid wastes

DOEpatents

Katti, Kattesh V.; Volkert, Wynn A.; Singh, Prahlad; Ketring, Alan R.

1995-01-01

The method of treating liquid waste in a media is accomplished by exposing the media to phosphinimines and sequestering .sup.99 Tc from the media by the phosphinimine (PN) functionalities. The system for treating the liquid waste in the media includes extraction of .sup.99 TcO.sub.4.sup.- from aqueous solutions into organic solvents or mixed organic/polar media, extraction of .sup.99 Tc from solutions on a solid matrix by using a container containing PN functionalities on solid matrices including an inlet and outlet for allowing flow of media through an immobilized phosphinimine ligand system contained within the container. Also, insoluble suspensions of phosphinimine functionalities on solid matrices in liquid solutions or present on supported liquid membranes (SLM) can be used to sequester .sup.99 Tc from those liquids.

Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures.

PubMed

Ukpai, Gideon; Năstase, Gabriel; Șerban, Alexandru; Rubinsky, Boris

2017-01-01

Preservation of biological materials at subzero Centigrade temperatures, cryopreservation, is important for the field of tissue engineering and organ transplantation. Our group is studying the use of isochoric (constant volume) systems of aqueous solution for cryopreservation. Previous studies measured the pressure-temperature relations in aqueous isochoric systems in the temperature range from 0°C to - 20°C. The goal of this study is to expand the pressure-temperature measurement beyond the range reported in previous publications. To expand the pressure-temperature measurements beyond the previous range, we have developed a new isochoric device capable of withstanding liquid nitrogen temperatures and pressures of up to 413 MPa. The device is instrumented with a pressure transducer than can monitor and record the pressures in the isochoric chamber in real time. Measurements were made in a temperature range from - 5°C to liquid nitrogen temperatures for various solutions of pure water and Me2SO (a chemical additive used for protection of biological materials in a frozen state and for vitrification (glass formation) of biological matter). Undissolved gaseous are is carefully removed from the system. Temperature-pressure data from - 5°C to liquid nitrogen temperature for pure water and other solutions are presented in this study. Following are examples of some, temperature-pressure values, that were measured in an isochoric system containing pure water: (- 20°C, 187 MPa); (-25°C, 216 MPa); (- 30°C, 242.3 MPa); (-180°C, 124 MPa). The data is consistent with the literature, which reports that the pressure and temperature at the triple point, between ice I, ice III and water is, - 21.993°C and 209.9 MPa, respectively. It was surprising to find that the pressure in the isochoric system increases at temperatures below the triple point and remains high to liquid nitrogen temperatures. Measurements of pressure-temperature relations in solutions of pure water and Me2SO in different concentrations show that, for concentrations in which vitrification is predicted, no increase in pressure was measured during rapid cooling to liquid nitrogen temperatures. However, ice formation either during cooling or warming to and from liquid nitrogen temperatures produced an increase in pressure. The data obtained in this study can be used to aid in the design of isochoric cryopreservation protocols. The results suggest that the pressure measurement is important in the design of "constant volume" systems and can provide a simple means to gain information on the occurrence of vitrification and devitrification during cryopreservation processes of aqueous solutions in an isochoric system.

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.

Single and two-phase flows of shear-thinning media in safety valves.

PubMed

Moncalvo, D; Friedel, L

2009-09-15

This study is the first one in the scientific literature to investigate the liquid and two-phase flows of shear-thinning media, here aqueous solutions of polyvinylpyrrolidone, in a fully opened safety valve. In liquid flows the volume flux at the valve seat does not show any appreciable reduction when increasing the percental weight of polymer in the solution. This result may suggest that the viscous losses in the valve do not increase sensibly from the most aqueous to the most viscous solution. The authors explain it considering that in the region between the seat and the disk, where large pressure and velocity gradients occur, large shear rates are expected. On behalf of the rheological measurements, which show that both the pseudoplasticity and the zero-shear viscosity of the solutions increase with the polymer weight, the difference between the viscosities of the most viscous and those of the most aqueous solution is between the seat and the disk far less than that existing at zero-shear condition. Therefore, the effective viscous pressure drop of the safety valve, which occurs mostly in that region, must increase only modestly with the polymer percental weight in the solution. In two-phase flows the total mass flow rate at constant quality and constant relieving pressure increases remarkably with the polymer weight. The analogy with similar results in cocurrent pipe flows suggests that air entrainment causes large velocity gradients in the liquids and strains them to very large shear rates. It suggests also that a redistribution of the gas agglomerates within the liquid must be expected when increasing the polymer weight in the solutions. In fact, the gas agglomerates react to the larger viscous drag of the liquid by compressing their volume in order to exert a higher internal pressure. The reduction of the void fraction of the mixture at constant quality and constant relieving pressure imposes an increment in the total mass flow rate, since otherwise it would lead to a reduction in the momentum of the mixture and therefore to a drop in the relieving pressure.

Shear bond strength between resin cement and colored zirconia made with metal chlorides.

PubMed

Kim, Ga-Hyun; Park, Sang-Won; Lee, Kwangmin; Oh, Gye-Jeong; Lim, Hyun-Pil

2015-06-01

Although the application of zirconia in esthetic prostheses has increased, the shear bond strength (SBS) between colored zirconia and resin cement has not been investigated. The purpose of this study was to compare the SBS between resin cement and colored zirconia made with metal chlorides. Sixty-four zirconia specimens were divided into 2 groups: one in which the specimens were bonded with resin cement, including 4-META (4-methacryloxyethyl trimellitic anhydride), and one in which the specimens were bonded with resin cement (SEcure, Sun Medical) after being processed with zirconia primer (Zirconia Liner), including 4-META. Each group was then divided into 4 subgroups depending on the coloring liquid. The subgroups were noncolored (control), commercial coloring liquid VITA In-Ceram 2000 YZ LL1, aqueous chromium chloride solution 0.1 wt%, and aqueous molybdenum chloride solution 0.1 wt%. Composite resin cylinders (Filtek Z250, 3M ESPE) were fabricated and bonded to the surface of the zirconia specimen with resin cement (SEcure). All specimens were stored in 37°C distilled water for 24 hours, and the SBS was measured with a universal testing machine. All data were analyzed statistically with 2-way ANOVA and tested post hoc with the Tukey test (α=.05). Significant differences were observed among the SBS values of the colored zirconia depending on the coloring liquid (P<.001) and whether they were processed with zirconia primer (P<.001). The SBS between colored zirconia and resin cement was significantly higher than that of noncolored zirconia and resin cement in groups processed with zirconia primer (P<.05). Colored zirconia immersed in aqueous molybdenum chloride solution showed a significantly higher SBS. Coloring liquid enhanced the SBS between resin cement and zirconia processed with zirconia primer. In particular, colored zirconia immersed in aqueous molybdenum chloride solution showed the highest SBS. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Short-time microscopic dynamics of aqueous methanol solutions

NASA Astrophysics Data System (ADS)

Kalampounias, A. G.; Tsilomelekis, G.; Boghosian, S.

2012-12-01

In this paper we present the picosecond vibrational dynamics of a series of methanol aqueous solutions over a wide concentration range from dense to dilute solutions. We studied the vibrational dephasing and vibrational frequency modulation by calculating the time correlation functions of vibrational relaxation by fits in the frequency domain. This method is applied to aqueous methanol solutions xMeOH-(1 - x)H2O, where x = 0, 0.2, 0.4, 0.6, 0.8 and 1. The important finding is that the vibrational dynamics of the system become slower with increasing methanol concentration. The removal of many-body effects by having the molecules in less-crowded environments seems to be the key factor. The interpretation of the vibrational correlation function in the context of Kubo theory, which is based on the assumption that the environmental modulation arises from a single relaxation process and applied to simple liquids, is inadequate for all solutions studied. We found that the vibrational correlation functions of the solutions over the whole concentration range comply with the Rothschild approach, assuming that the environmental modulation is described by a stretched exponential decay. The evolution of the dispersion parameter α with dilution indicates the deviation of the solutions from the model simple liquid and the results are discussed in the framework of the current phenomenological status of the field.

Osmosis and solute-solvent drag: fluid transport and fluid exchange in animals and plants.

PubMed

Hammel, H T; Schlegel, Whitney M

2005-01-01

In 1903, George Hulett explained how solute alters water in an aqueous solution to lower the vapor pressure of its water. Hulett also explained how the same altered water causes osmosis and osmotic pressure when the solution is separated from liquid water by a membrane permeable to the water only. Hulett recognized that the solute molecules diffuse toward all boundaries of the solution containing the solute. Solute diffusion is stopped at all boundaries, at an open-unopposed surface of the solution, at a semipermeable membrane, at a container wall, or at the boundary of a solid or gaseous inclusion surrounded by solution but not dissolved in it. At each boundary of the solution, the solute molecules are reflected, they change momentum, and the change of momentum of all reflected molecules is a pressure, a solute pressure (i.e., a force on a unit area of reflecting boundary). When a boundary of the solution is open and unopposed, the solute pressure alters the internal tension in the force bonding the water in its liquid phase, namely, the hydrogen bond. All altered properties of the water in the solution are explained by the altered internal tension of the water in the solution. We acclaim Hulett's explanation of osmosis, osmotic pressure, and lowering of the vapor pressure of water in an aqueous solution. His explanation is self-evident. It is the necessary, sufficient, and inescapable explanation of all altered properties of the water in the solution relative to the same property of pure liquid water at the same externally applied pressure and the same temperature. We extend Hulett's explanation of osmosis to include the osmotic effects of solute diffusing through solvent and dragging on the solvent through which it diffuses. Therein lies the explanations of (1) the extravasation from and return of interstitial fluid to capillaries, (2) the return of luminal fluid in the proximal and distal convoluted tubules of a kidney nephron to their peritubular capillaries, (3) the return of interstitial fluid to the vasa recta, (4) return of aqueous humor to the episcleral veins, and (5) flow of phloem from source to sink in higher plants and many more examples of fluid transport and fluid exchange in animal and plant physiology. When a membrane is permeable to water only and when it separates differing aqueous solutions, the flow of water is from the solution with the lower osmotic pressure to the solution with the higher osmotic pressure.

Sequential injection ionic liquid dispersive liquid-liquid microextraction for thallium preconcentration and determination with flame atomic absorption spectrometry.

PubMed

Anthemidis, Aristidis N; Ioannou, Kallirroy-Ioanna G

2012-08-01

A novel, automatic on-line sequential injection dispersive liquid-liquid microextraction (SI-DLLME) method, based on 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]) ionic liquid as an extractant solvent was developed and demonstrated for trace thallium determination by flame atomic absorption spectrometry. The ionic liquid was on-line fully dispersed into the aqueous solution in a continuous flow format while the TlBr(4)(-) complex was easily migrated into the fine droplets of the extractant due to the huge contact area of them with the aqueous phase. Furthermore, the extractant was simply retained onto the surface of polyurethane foam packed into a microcolumn. No specific conditions like low temperature are required for extractant isolation. All analytical parameters of the proposed method were investigated and optimized. For 15 mL of sample solution, an enhancement factor of 290, a detection limit of 0.86 μg L(-1) and a precision (RSD) of 2.7% at 20.0 μg L(-1) Tl(I) concentration level, was obtained. The developed method was evaluated by analyzing certified reference materials while good recoveries from environmental and biological samples proved that present method was competitive in practical applications.

Plasma Induced Degradation of Benzidine in Aqueous Solution

NASA Astrophysics Data System (ADS)

Gao, Jinzhang; Gai, Ke; Yang, Wu; Dong, Yanjie

2003-10-01

The degradation of benzidine in aqueous solution by the low temperature plasma was examined. The results showed that the concentration of medium and the value of pH have an appreciable effect on the degradation of benzidine. What is more important is that iron ions acting as a catalyst play an important role in this reaction. For exploring the degradation mechanism of benzidine, some of the intermediate products were recorded by HPLC (high performance liquid chromatography).

Application of Molecular Dynamics Simulations in Molecular Property Prediction II: Diffusion Coefficient

PubMed Central

Wang, Junmei; Hou, Tingjun

2011-01-01

In this work, we have evaluated how well the General AMBER force field (GAFF) performs in studying the dynamic properties of liquids. Diffusion coefficients (D) have been predicted for 17 solvents, 5 organic compounds in aqueous solutions, 4 proteins in aqueous solutions, and 9 organic compounds in non-aqueous solutions. An efficient sampling strategy has been proposed and tested in the calculation of the diffusion coefficients of solutes in solutions. There are two major findings of this study. First of all, the diffusion coefficients of organic solutes in aqueous solution can be well predicted: the average unsigned error (AUE) and the root-mean-square error (RMSE) are 0.137 and 0.171 ×10−5 cm−2s−1, respectively. Second, although the absolute values of D cannot be predicted, good correlations have been achieved for 8 organic solvents with experimental data (R2 = 0.784), 4 proteins in aqueous solutions (R2 = 0.996) and 9 organic compounds in non-aqueous solutions (R2 = 0.834). The temperature dependent behaviors of three solvents, namely, TIP3P water, dimethyl sulfoxide (DMSO) and cyclohexane have been studied. The major MD settings, such as the sizes of simulation boxes and with/without wrapping the coordinates of MD snapshots into the primary simulation boxes have been explored. We have concluded that our sampling strategy that averaging the mean square displacement (MSD) collected in multiple short-MD simulations is efficient in predicting diffusion coefficients of solutes at infinite dilution. PMID:21953689

Intermolecular Interactions of Pyridine in Liquid Phase and Aqueous Solution Studied by Soft X-ray Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Nagasaka, Masanari; Yuzawa, Hayato; Kosugi, Nobuhiro

2018-05-01

Intermolecular interactions of pyridine in liquid and in aqueous solution are studied by using soft X-ray absorption spectroscopy (XAS) at the C, N, and O K-edges. XAS of liquid pyridine shows that the N 1s→π* peak is blue shifted and the C 1s→π* peak of the meta and para sites is red shifted, respectively, as compared with XAS of pyridine gas. These shifts in liquid are smaller than those in clusters, indicating that the intermolecular interaction of liquid pyridine is weaker than that of pyridine cluster, as supported by the combination of quantum chemical calculations of the core excitation and molecular dynamics simulations of the liquid structure. On the other hand, XAS spectra of aqueous pyridine solutions (C5H5N)x(H2O)1-x measured at different molar fractions show that in the pyridine rich region, x>0.7, the C and N 1s→π* peak energies are not so different from pure liquid pyridine (x=1.0). In this region, antiparallel displaced structures of pyridine molecules are dominant as in pure pyridine liquid. In the O K-edge XAS, the pre-edge peaks sensitive to the hydrogen bond (HB) network of water molecules show the red shift of -0.15 eV from that of bulk water, indicating that small water clusters with no large-scale HB network are formed in the gap space of structured pyridine molecules. In the water rich region, 0.7>x, the N 1s→π* peaks and the O 1s pre-edge peaks are blue shifted, and the C 1s→π* peaks of the meta and para sites are red-shifted by increasing molar fraction of water. The HB network of bulk water is dominant, but quantum chemical calculations indicate that small pyridine clusters with the HB interaction between the H atom in water and the N atom in pyridine are still existent even in very dilute pyridine solutions.

Molecular dynamics simulations of aqueous solutions of ethanolamines.

PubMed

López-Rendón, Roberto; Mora, Marco A; Alejandre, José; Tuckerman, Mark E

2006-08-03

We report on molecular dynamics simulations performed at constant temperature and pressure to study ethanolamines as pure components and in aqueous solutions. A new geometric integration algorithm that preserves the correct phase space volume is employed to study molecules having up to three ethanol chains. The most stable geometry, rotational barriers, and atomic charges were obtained by ab initio calculations in the gas phase. The calculated dipole moments agree well with available experimental data. The most stable conformation, due to intramolecular hydrogen bonding interactions, has a ringlike structure in one of the ethanol chains, leading to high molecular stability. All molecular dynamics simulations were performed in the liquid phase. The interaction parameters are the same for the atoms in the ethanol chains, reducing the number of variables in the potential model. Intermolecular hydrogen bonding is also analyzed, and it is shown that water associates at low water mole fractions. The force field reproduced (within 1%) the experimental liquid densities at different temperatures of pure components and aqueous solutions at 313 K. The excess and partial molar volumes are analyzed as a function of ethanolamine concentration.

Exploring Solute-Solvent Interactions of -Amino Acids in Aqueous [] Arrangements by Volumetric, Viscometric, Refractometric, and Acoustic Approach

NASA Astrophysics Data System (ADS)

Roy, Mahendra Nath; Roy, Milan Chandra; Basak, Saptarshi

2014-05-01

Qualitative and quantitative analysis of molecular interaction prevailing in glycine, l-alanine, l-valine, and aqueous solution of ionic liquid (IL) [1-ethylpyridinium tetrafluoroborate (] have been investigated by thermophysical properties. The apparent molar volume (), viscosity -coefficient, molal refraction (), and adiabatic compressibility ( of glycine, l-alanine, and l-valine have been studied in 0.001 mol , 0.003 mol , and 0.005 mol aqueous 1-ethylpyridinium tetrafluoroborate [] solutions at 298.15 K from the values of densities , viscosities (), refractive index (, and speed of sound , respectively. The extent of interaction, i.e., the solute-solvent interaction is expressed in terms of the limiting apparent molar volume (, viscosity -coefficient, and limiting apparent molar adiabatic compressibility (. The limiting apparent molar volumes (, experimental slopes ( derived from the Masson equation, and viscosity - and -coefficients using the Jones-Dole equation have been interpreted in terms of ion-ion and ion-solvent interactions, respectively. Molal refractions ( have been calculated with the help of the Lorentz-Lorenz equation. The role of the solvent (aqueous IL solution) and the contribution of solute-solute and solute-solvent interactions to the solution complexes have also been analyzed through the derived properties.

The isoelectric point/point-of zero-charge of interfaces formed by aqueous solutions and nonpolar solids, liquids, and gases.

PubMed

Healy, Thomas W; Fuerstenau, Douglas W

2007-05-01

From our previous work on the role of the electrostatic field strength in controlling the pH of the iso-electric point (iep)/point-of-zero-charge (pzc) of polar solids we have extended the analysis to predict that the pH of the iep/pzc of a nonpolar solid, liquid or gas-aqueous interface should occur at pH 1.0-3.0, dependent on the value assigned to water molecules or clusters at the interface. Consideration of a wide range of experimental results covering nonpolar solids such as molybdenite, stibnite, paraffin, etc. as well as hydrocarbon liquids such as xylene, decalin, and long chain (>C8) alkane oils, as well as nitrogen and hydrogen gases, all in various simple 1:1 electrolyte solutions confirm the general validity of the result. We further consider various models of the origin of the charge on nonpolar material-water interfaces.

Aqueous solubilities of alkylphenols and methoxyphenols at 25 C

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

Varhanickova, D.; Shiu, W.Y.; Mackay, D.

1995-03-01

The aqueous solubilities of 25 phenolic substances (2-methylphenol; 3-methylphenol; 4-methylphenol; 2,3-dimethylphenol; 2,4-dimethylphenol; 2,5-dimethylphenol; 2,6-dimethylphenol; 3,4-dimethylphenol; 3,5dimethylphenol; 2-ethylphenol: 4-ethylphenol; 2,3,5-trimethylphenol; 2,4,6-trimethylphenol; 3,4,5-trimethylphenol; 4-propylphenol; 2-isopropylphenol; 4-isopropylphenol; 4-butylphenol; 3-tert-butylphenol; 4-tert-butylphenol; 4-hexylphenol; 3,5-di-tert-butylphenol; 4-octylphenol; 3-methoxyphenol; and 4-methoxyphenol) were determined at 25 C, by a conventional shake-flask, batch contacting method with analysis by high-pressure liquid chromatography with LTV detection. Satisfactory agreement was obtained between measured and previously reported solubilities for 10 of these substances. The liquid or supercooled liquid solubilities are satisfactorily correlated with the solute`s LeBas molar volume and with first-order valence molecular connectivity, yielding structure-property relationships that may be useful for predictive purposes.

Evaluation of fatty acid oxidation by reactive oxygen species induced in liquids using atmospheric-pressure nonthermal plasma jets

NASA Astrophysics Data System (ADS)

Tani, Atsushi; Fukui, Satoshi; Ikawa, Satoshi; Kitano, Katsuhisa

2015-10-01

We investigated fatty acid oxidation by atmospheric-pressure nonthermal helium plasma using linoleic acid, an unsaturated fatty acid, together with evaluating active species induced in liquids. If the ambient gas contains oxygen, direct plasma such as plasma jets coming into contact with the liquid surface supplies various active species, such as singlet oxygen, ozone, and superoxide anion radicals, to the liquid. The direct plasma easily oxidizes linoleic acid, indicating that fatty acid oxidation will occur in the direct plasma. In contrast, afterglow flow, where the plasma is terminated in a glass tube and does not touch the surface of the liquid sample, supplies mainly superoxide anion radicals. The fact that there was no clear observation of linoleic acid oxidation using the afterglow reveals that it may not affect lipids, even in an atmosphere containing oxygen. The afterglow flow can potentially be used for the sterilization of aqueous solutions using the reduced pH method, in medical and dental applications, because it provides bactericidal activity in the aqueous solution despite containing a smaller amount of active species.

Shock Hugoniot and equations of states of water, castor oil, and aqueous solutions of sodium chloride, sucrose and gelatin

NASA Astrophysics Data System (ADS)

Gojani, A. B.; Ohtani, K.; Takayama, K.; Hosseini, S. H. R.

2016-01-01

This paper reports a result of experiments for the determination of reliable shock Hugoniot curves of liquids, in particular, at relatively low pressure region, which are needed to perform precise numerical simulations of shock wave/tissue interaction prior to the development of shock wave related therapeutic devices. Underwater shock waves were generated by explosions of laser ignited 10 mg silver azide pellets, which were temporally and spatially well controlled. Measuring temporal variation of shock velocities and over-pressures in caster oil, aqueous solutions of sodium chloride, sucrose and gelatin with various concentrations, we succeeded to determine shock Hugoniot curves of these liquids and hence parameters describing Tait type equations of state.

Molecular Dynamics Simulations of Strain-Induced Phase Transition of Poly(ethylene oxide) in Water.

PubMed

Donets, Sergii; Sommer, Jens-Uwe

2018-01-11

We study the dilute aqueous solutions of poly(ethylene oxide) (PEO) oligomers that are subject to an elongating force dipole acting on both chain ends using atomistic molecular dynamics. By increasing the force, liquid-liquid demixing can be observed at room temperature far below the lower critical solution temperature. For forces above 35 pN, fibrillar nanostructures are spontaneously formed related to a decrease in hydrogen bonding between PEO and water. Most notable is a rapid decrease in the bifurcated hydrogen bonds during stretching, which can also be observed for isolated single chains. The phase-segregated structures display signs of chain ordering, but a clear signature of the crystalline order is not obtained during the simulation time, indicating a liquid-liquid phase transition induced by chain stretching. Our results indicate that the solvent quality of the aqueous solution of PEO depends on the conformational state of the chains, which is most likely related to the specific hydrogen-bond-induced solvation of PEO in water. The strain-induced demixing of PEO opens the possibility to obtain polymer fibers with low energy costs because crystallization starts via the strain-induced demixing in the extended state only.

pH-Dependent Liquid-Liquid Phase Separation of Highly Supersaturated Solutions of Weakly Basic Drugs.

PubMed

Indulkar, Anura S; Box, Karl J; Taylor, Robert; Ruiz, Rebeca; Taylor, Lynne S

2015-07-06

Supersaturated solutions of poorly aqueous soluble drugs can be formed both in vivo and in vitro. For example, increases in pH during gastrointestinal transit can decrease the aqueous solubility of weakly basic drugs resulting in supersaturation, in particular when exiting the acidic stomach environment. Recently, it has been observed that highly supersaturated solutions of drugs with low aqueous solubility can undergo liquid-liquid phase separation (LLPS) prior to crystallization, forming a turbid solution such that the concentration of the drug in the continuous solution phase corresponds to the amorphous solubility while the colloidal phase is composed of a disordered drug-rich phase. Although it is well established that the equilibrium solubility of crystalline weakly basic drugs follows the Henderson-Hasselbalch relationship, the impact of pH on the LLPS phenomenon or the amorphous solubility has not been explored. In this work, the LLPS concentration of three weakly basic compounds-clotrimazole, nicardipine, and atazanavir-was determined as a function of pH using three different methods and was compared to the predicted amorphous solubility, which was calculated from the pH-dependent crystalline solubility and by estimating the free energy difference between the amorphous and crystalline forms. It was observed that, similar to crystalline solubility, the experimental amorphous solubility at any pH follows the Henderson-Hasselbalch relation and can be predicted if the amorphous solubility of the free base is known. Excellent agreement between the LLPS concentration and the predicted amorphous solubility was observed. Dissolution studies of amorphous drugs showed that the solution concentration can reach the corresponding LLPS concentration at that pH. Solid-state analysis of the precipitated material confirmed the amorphous nature. This work provides insight into the pH-dependent precipitation behavior of poorly water-soluble compounds and provides a fundamental basis with which to understand the performance of supersaturating dosage forms.

Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions

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

Walker, Rachel L.; Searles, Keith; Willard, Jesse A.

2013-12-28

Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphologymore » allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.« less

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

Simultaneous extraction and HPLC determination of 3-indole butyric acid and 3-indole acetic acid in pea plant by using ionic liquid-modified silica as sorbent.

PubMed

Sheikhian, Leila; Bina, Sedigheh

2016-01-15

In this study, ionic liquid-modified silica was used as sorbent for simultaneous extraction and preconcentration of 3-indole butyric acid and 3-indole acetic acid in pea plants. The effect of some parameters such as pH and ionic strength of sample solution, amount of sorbent, flow rate of aqueous sample solution and eluent solution, concentration of eluent solution, and temperature were studied for each hormone solution. Percent extraction of 3-indole butyric acid and 3-indole acetic acid was strongly affected by pH of aqueous sample solution. Ionic strength of aqueous phase and temperature showed no serious effects on extraction efficiency of studied plant hormones. Obtained breakthrough volume was 200mL for each of studied hormones. Preconcentration factor for spectroscopic and chromatographic determination of studied hormones was 100 and 4.0×10(3) respectively. Each solid sorbent phase was reusable for almost 10 times of extraction/stripping procedure. Relative standard deviations of extraction/stripping processes of 3-indole butyric acid and 3-indole acetic acid were 2.79% and 3.66% respectively. The calculated limit of detections for IBA and IAA were 9.1×10(-2)mgL(-1) and 1.6×10(-1)mgL(-1) respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of potentization in aqueous solutions.

PubMed

Schulte, J

1999-10-01

Over the past two decades, research into structure formation and structure conservation in water has created a significant interest among the homeopathy research community. The formation of sustained static and dynamic structures in aqueous solutions is thought to be synonymous with the possible storage of information in associated liquids. Prominent models and experiments considering this possibility are presented in this paper, and some of their subtleties, which were not given much room in the respective original publications, will be elucidated in more detail here.

Sorption of carboxylic acid from carboxylic salt solutions at pHs close to or above the pK[sub a] of the acid, with regeneration with an aqueous solution of ammonia or low-molecular-weight alkylamine

DOEpatents

King, C.J.; Tung, L.A.

1992-07-21

Carboxylic acids are sorbed from aqueous feedstocks at pHs close to or above the acids' pH[sub a] into a strongly basic organic liquid phase or onto a basic solid adsorbent or moderately basic ion exchange resin. The acids are freed from the sorbent phase by treating it with aqueous alkylamine or ammonia thus forming an alkylammonium or ammonium carboxylate which dewatered and decomposed to the desired carboxylic acid and the alkylamine or ammonia. 8 figs.

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.

Enhancement of conversion efficiency of extreme ultraviolet radiation from a liquid aqueous solution microjet target by use of dual laser pulses

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Dojyo, Naoto; Hamada, Masaya; Kawasaki, Keita; Sasaki, Wataru; Kubodera, Shoichi

2006-03-01

We demonstrated a debris-free, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO II) nano-particles. By using a low SnO II concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris.

Thermoresponsive Poly(Ionic Liquid)s in Aqueous Salt Solutions: Salting-Out Effect on Their Phase Behavior and Water Absorption/Desorption Properties.

PubMed

Okafuji, Akiyoshi; Kohno, Yuki; Ohno, Hiroyuki

2016-07-01

Here, a thermoresponsive phase behavior of polymerized ionic liquids (PILs) composed of poly([tri-n-alkyl(vinylbenzyl)phosphonium]chloride) (poly([Pnnn VB ]Cl) is reported, where n (the number of carbon atoms of an alkyl chain) = 4, 5, or 6 after mixing with aqueous sodium chloride solutions. Both monomeric [P555VB ]Cl and the resulting poly([P555VB ]Cl) linear homopolymer show a lower critical solution temperature (LCST)-type phase behavior in aq. NaCl solutions. The phase transition temperature of the PIL shifts to lower value by increasing concentration of NaCl. Also the swelling degree of cross-linked poly([P555VB ]Cl) gel decreases by increasing NaCl concentration, clearly suggesting the "salting-out" effect of NaCl results in a significant dehydration of the poly([P555VB ]Cl) gel. The absorbed water in the PIL gel is desorbed by moderate heating via the LCST behavior, and the absolute absorption/desorption amount is improved by copolymerization of [P555VB ]Cl with more hydrophilic [P444VB ]Cl monomer. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using the Binary Phase-Field Crystal Model to Describe Non-Classical Nucleation Pathways in Gold Nanoparticles

NASA Astrophysics Data System (ADS)

Smith, Nathan; Provatas, Nikolas

Recent experimental work has shown that gold nanoparticles can precipitate from an aqueous solution through a non-classical, multi-step nucleation process. This multi-step process begins with spinodal decomposition into solute-rich and solute-poor liquid domains followed by nucleation from within the solute-rich domains. We present a binary phase-field crystal theory that shows the same phenomology and examine various cross-over regimes in the growth and coarsening of liquid and solid domains. We'd like to the thank Canada Research Chairs (CRC) program for funding this work.

Simulating Osmotic Equilibria: A New Tool for Calculating Activity Coefficients in Concentrated Aqueous Salt Solutions.

PubMed

Bley, Michael; Duvail, Magali; Guilbaud, Philippe; Dufrêche, Jean-François

2017-10-19

Herein, a new theoretical method is presented for predicting osmotic equilibria and activities, where a bulk liquid and its corresponding vapor phase are simulated by means of molecular dynamics using explicit polarization. Calculated time-averaged number density profiles provide the amount of evaporated molecules present in the vapor phase and consequently the vapor-phase density. The activity of the solvent and the corresponding osmotic coefficient are determined by the vapor density at different solute concentrations with respect to the reference vapor density of the pure solvent. With the extended Debye-Hückel equation for the activity coefficient along with the corresponding Gibbs-Duhem relation, the activity coefficients of the solutes are calculated by fitting the osmotic coefficients. A simple model based on the combination of Poisson processes and Maxwell-Boltzmann velocity distributions is introduced to interpret statistical phenomena observed during the simulations, which are related to evaporation and recondensation. This method is applied to aqueous dysprosium nitrate [Dy(NO 3 ) 3 ] solutions at different concentrations. The obtained densities of the liquid bulk and the osmotic and activity coefficients are in good agreement with the experimental results for concentrated and saturated solutions. Density profiles of the liquid-vapor interface at different concentrations provide detailed insight into the spatial distributions of all compounds.

Singlet oxygen generation on porous superhydrophobic surfaces: effect of gas flow and sensitizer wetting on trapping efficiency.

PubMed

Zhao, Yuanyuan; Liu, Yang; Xu, Qianfeng; Barahman, Mark; Bartusik, Dorota; Greer, Alexander; Lyons, Alan M

2014-11-13

We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon-phthalocyanine (Pc) particles are immobilized. Singlet oxygen ((1)O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV-vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid-gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices.

Solubility of carbon dioxide in aqueous solutions of 2-amino-2-methyl-1-propanol and N-methyldiethanolamine and their mixtures in the temperature range of 313 to 353 K and pressures up to 2.7 MPa

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

Silkenbaeumer, D.; Lichtenthaler, R.N.; Rumpf, B.

1998-08-01

The solubility of carbon dioxide in aqueous solutions containing 2-amino-2-methyl-1-propanol (AMP) was measured in the temperature range from 313 to 353 K at total pressures up to 2.7 MPa using an analytical method. A model taking into account chemical reactions in the liquid phase as well as physical interactions is used to correlate the new data. To test the predictive capability of the model, the solubility of carbon dioxide in an aqueous solution containing AMP and N-methyldiethanolamine (MDEA) was measured at 313 K. Experimental results are reported and compared to literature data and calculations.

Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures

PubMed Central

Șerban, Alexandru; Rubinsky, Boris

2017-01-01

Objective Preservation of biological materials at subzero Centigrade temperatures, cryopreservation, is important for the field of tissue engineering and organ transplantation. Our group is studying the use of isochoric (constant volume) systems of aqueous solution for cryopreservation. Previous studies measured the pressure-temperature relations in aqueous isochoric systems in the temperature range from 0°C to – 20°C. The goal of this study is to expand the pressure-temperature measurement beyond the range reported in previous publications. Materials and methods To expand the pressure-temperature measurements beyond the previous range, we have developed a new isochoric device capable of withstanding liquid nitrogen temperatures and pressures of up to 413 MPa. The device is instrumented with a pressure transducer than can monitor and record the pressures in the isochoric chamber in real time. Measurements were made in a temperature range from – 5°C to liquid nitrogen temperatures for various solutions of pure water and Me2SO (a chemical additive used for protection of biological materials in a frozen state and for vitrification (glass formation) of biological matter). Undissolved gaseous are is carefully removed from the system. Results Temperature-pressure data from – 5°C to liquid nitrogen temperature for pure water and other solutions are presented in this study. Following are examples of some, temperature-pressure values, that were measured in an isochoric system containing pure water: (- 20°C, 187 MPa); (-25°C, 216 MPa); (- 30°C, 242.3 MPa); (-180°C, 124 MPa). The data is consistent with the literature, which reports that the pressure and temperature at the triple point, between ice I, ice III and water is, - 21.993°C and 209.9 MPa, respectively. It was surprising to find that the pressure in the isochoric system increases at temperatures below the triple point and remains high to liquid nitrogen temperatures. Measurements of pressure-temperature relations in solutions of pure water and Me2SO in different concentrations show that, for concentrations in which vitrification is predicted, no increase in pressure was measured during rapid cooling to liquid nitrogen temperatures. However, ice formation either during cooling or warming to and from liquid nitrogen temperatures produced an increase in pressure. Conclusions The data obtained in this study can be used to aid in the design of isochoric cryopreservation protocols. The results suggest that the pressure measurement is important in the design of “constant volume” systems and can provide a simple means to gain information on the occurrence of vitrification and devitrification during cryopreservation processes of aqueous solutions in an isochoric system. PMID:28817681

Shock wave emission from laser-induced cavitation bubbles in polymer solutions.

PubMed

Brujan, Emil-Alexandru

2008-09-01

The role of extensional viscosity on the acoustic emission from laser-induced cavitation bubbles in polymer solutions and near a rigid boundary is investigated by acoustic measurements. The polymer solutions consist of a 0.5% polyacrylamide (PAM) aqueous solution with a strong elastic component and a 0.5% carboxymethylcellulose (CMC) aqueous solution with a weak elastic component. A reduction of the maximum amplitude of the shock wave pressure and a prolongation of the oscillation period of the bubble were found in the elastic PAM solution. It might be caused by an increased resistance to extensional flow which is conferred upon the liquid by the polymer additive. In both polymer solutions, however, the shock pressure decays proportionally to r(-1) with increasing distance r from the emission centre.

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.

RECOVERY OF RUTHENIUM VALUES

DOEpatents

Grummitt, W.E.; Hardwick, W.H.

1961-01-01

A process is given for the recovery of ruthenium from its aqueous solutions by oxidizing the ruthenium to the octavalent state and subsequently extracting the ruthenium into a halogen-substituted liquid paraffin.

Liquid nitrogen-assisted synthesis of fluorescent carbon dots from Blueberry and their performance in Fe3+ detection

NASA Astrophysics Data System (ADS)

Aslandaş, Ayşe Merve; Balcı, Neslihan; Arık, Mustafa; Şakiroğlu, Halis; Onganer, Yavuz; Meral, Kadem

2015-11-01

Fluorescent carbon dots (C-dots) were synthesized by a facile method containing liquid N2 treatment and centrifuge processes. The photophysical properties of the C-dots in an aqueous solution were examined at various conditions such as concentration, temperature, pH and excitation wavelength by using UV-vis absorption, fluorescence and time-resolved fluorescence spectroscopies. The C-dots emitted a broad fluorescence between approximately 350-550 nm and their fluorescence was tuned by changing excitation wavelength. The as-prepared C-dots were applied to Fe3+ detection from aqueous solution. Spectroscopic data revealed that the as-prepared C-dots were used to detect Fe3+ in the range of 12.5 μM to 100 μM as a fluorescence sensor.

Recovery of hydrogen iodide

DOEpatents

Norman, John H.

1983-01-01

A method of extraction of HI from an aqueous solution of HI and I.sub.2. HBr is added to create a two-phase liquid mixture wherein a dry phase consists essentially of HBr, I and HI and is in equilibrium with a wet phase having a far greater HBr:HI ratio. Using a countercurrent extractor, two solutions can be obtained: a dry HBr--HI--I.sub.2 solution and a wet essentially HBr solution. The dry and wet phases are easily separable, and HI is recovered from the dry phase, after first separating I.sub.2, as by distillation. Alternatively, the HI-HBr liquid mixture is treated to catalytically decompose the HI. HBr is recovered from the wet phase by suitable treatment, including high-pressure distillation, to produce an H.sub.2 O--HBr azeotrope that is not more than 25 mole percent HBr. The azeotrope may be returned for use in an earlier step in the overall process which results in the production of the aqueous solution of HI and I.sub.2 without major detriment because of the presence of HBr.

Recovery of hydrogen iodide

DOEpatents

Norman, J.H.

1983-08-02

A method is described for extraction of HI from an aqueous solution of HI and I[sub 2]. HBr is added to create a two-phase liquid mixture wherein a dry phase consists essentially of HBr, I and HI and is in equilibrium with a wet phase having a far greater HBr:HI ratio. Using a countercurrent extractor, two solutions can be obtained: a dry HBr--HI--I[sub 2] solution and a wet essentially HBr solution. The dry and wet phases are easily separable, and HI is recovered from the dry phase, after first separating I[sub 2], as by distillation. Alternatively, the HI-HBr liquid mixture is treated to catalytically decompose the HI. HBr is recovered from the wet phase by suitable treatment, including high-pressure distillation, to produce an H[sub 2]O--HBr azeotrope that is not more than 25 mole percent HBr. The azeotrope may be returned for use in an earlier step in the overall process which results in the production of the aqueous solution of HI and I[sub 2] without major detriment because of the presence of HBr. 1 fig.

Microfludic Sensing Devices Employing In Situ-Formed Liquid Crystal Thin Film for Detection of Biochemical Interactions1†

PubMed Central

Liu, Ye; Cheng, Daming; Lin, I-Hsin; Abbott, Nicholas L.; Jiang, Hongrui

2012-01-01

Although biochemical sensing using liquid crystals (LC) has been demonstrated, relatively little attention has been paid towards the fabrication of in situ-formed LC sensing devices. Herein, we demonstrate a highly reproducible method to create uniform LC thin film on treated substrates, as needed, for LC sensing. We use shear forces generated by the laminar flow of aqueous liquid within a microfluidic channel to create LC thin films stabilized within microfabricated structures. The orientational response of the LC thin films to targeted analytes in aqueous phases was transduced and amplified by the optical birefringence of the LC thin films. The biochemical sensing capability of our sensing devices was demonstrated through experiments employing two chemical systems: dodecyl trimethylammonium bromide (DTAB) dissolved in an aqueous solution, and the hydrolysis of phospholipids by the enzyme phospholipase A2 (PLA2). PMID:22842797

Process of concentrating ethanol from dilute aqueous solutions thereof

DOEpatents

Oulman, C.S.; Chriswell, C.D.

1981-07-07

Relatively dilute aqueous solutions of ethanol are concentrated by passage through a bed of a crystalline silica polymorph, such as silicalite, to adsorb the ethanol with residual dilute feed in contact with the bed, which is displaced by passing concentrated aqueous ethanol through the bed without displacing the adsorbed ethanol. A product concentrate is then obtained by removing the adsorbed ethanol from the bed together with at least a portion of the concentrated aqueous ethanol used as the displacer liquid. This process permits ethanol to be concentrated from dilute fermentation beers, which may contain from 6 to 10% ethanol, to obtain a concentrate product at very low energy cost having an ethanol concentration in excess of 95%, such as a concentration of from 98 to 99.5%. 5 figs.

Process of concentrating ethanol from dilute aqueous solutions thereof

DOEpatents

Oulman, Charles S. [Ames, IA; Chriswell, Colin D. [Slater, IA

1981-07-07

Relatively dilute aqueous solutions of ethanol are concentrated by passage through a bed of a crystalline silica polymorph, such as silicalite, to adsorb the ethanol with residual dilute feed in contact with the bed, which is displaced by passing concentrated aqueous ethanol through the bed without displacing the adsorbed ethanol. A product concentrate is then obtained by removing the adsorbed ethanol from the bed together with at least a portion of the concentrated aqueous ethanol used as the displacer liquid. This process permits ethanol to be concentrated from dilute fermentation beers, which may contain from 6 to 10% ethanol, to obtain a concentrate product at very low energy cost having an ethanol concentration in excess of 95%, such as a concentration of from 98 to 99.5%.

METHOD FOR THE RECOVERY OF CESIUM VALUES

DOEpatents

Rimshaw, S.J.

1960-02-16

A method is given for recovering Cs/sup 137/ from radioactive waste solutions together with extraneous impurities. Ammonium alum is precipitated in the waste solution. The alum, which carries the cesium, is separated from the supernatant liquid and then dissolved in water. The resulting aqueous solution is then provided with a source of hydroxyl ions, which precipitates aluminum as the hydroxide, and the aluminum hydroxide is separated from the resulting liquid. This liquid, which contains anionic impurities together with ammonium and cesium, is passed through an anion exchange resin bed which removes the anionic impurities. The ammonium in the effluent is removed by destructive distiilation, leaving a substantiaily pure cesium salt in the effluent.

Microcapsules fabricated from liquid marbles stabilized with latex particles.

PubMed

Ueno, Kazuyuki; Hamasaki, Sho; Wanless, Erica J; Nakamura, Yoshinobu; Fujii, Syuji

2014-03-25

Millimeter- and centimeter-sized "liquid marbles" were readily prepared by rolling water droplets on a powder bed of dried submicrometer-sized polystyrene latex particles carrying poly[2-(diethylamino)ethyl methacrylate] hairs (PDEA-PS). Scanning electron microscopy studies indicated that flocs of the PDEA-PS particles were adsorbed at the surface of these water droplets, leading to stable spherical liquid marbles. The liquid marbles were deformed as a result of water evaporation to adopt a deflated spherical geometry, and the rate of water evaporation decreased with increasing atmospheric relative humidity. Conversely, liquid marbles formed using saturated aqueous LiCl solution led to atmospheric water absorption by the liquid marbles and a consequent mass increase. The liquid marbles can be transformed into polymeric capsules containing water by exposure to solvent vapor: the PDEA-PS particles were plasticized with the solvent vapor to form a polymer film at the air-water interface of the liquid marbles. The polymeric capsules with aqueous volumes of 250 μL or less kept their oblate ellipsoid/near spherical shape even after complete water evaporation, which confirmed that a rigid polymeric capsule was successfully formed. Both the rate of water evaporation from the pure water liquid marbles and the rate of water adsorption into the aqueous LiCl liquid marbles were reduced with an increase of solvent vapor treatment time. This suggests that the number and size of pores within the polymer particles/flocs on the liquid marble surface decreased due to film formation during exposure to organic solvent vapor. In addition, organic-inorganic composite capsules and colloidal crystal capsules were fabricated from liquid marbles containing aqueous SiO2 dispersions.

Density fluctuations in aqueous solution of ionic liquid with lower critical solution temperature: Mixture of tetrabutylphosphonium trifluoroacetate and water

NASA Astrophysics Data System (ADS)

Nitta, Ayako; Morita, Takeshi; Saita, Shohei; Kohno, Yuki; Ohno, Hiroyuki; Nishikawa, Keiko

2015-05-01

Aqueous solutions of tetrabutylphosphonium trifluoroacetate ([P4444]CF3COO) exhibit a LCST-type phase transition with the critical point near 0.025 in mole fraction of [P4444]CF3COO at T = 302 K. The phase behavior of [P4444]CF3COO-water mixtures was investigated by evaluating their density fluctuations, which provide quantitative descriptions of the mixing states of the solutions. The concentration dependence of the density fluctuations was investigated at 293 and 301 K for the mixtures without distinguishing the components and for the individual components ([P4444]CF3COO and water). A drastic change in the mixing state was observed for the solution when the critical point was approached.

Aroma volatility from aqueous sucrose solutions at low and subzero temperatures.

PubMed

Covarrubias-Cervantes, Marco; Champion, Dominique; Debeaufort, Frédéric; Voilley, Andrée

2004-11-17

The gas-liquid partition coefficients of ethyl acetate and ethyl hexanoate have been measured in water and aqueous sucrose solutions from 25 to -10 degrees C by dynamic headspace. Experiments were carried out on sucrose solutions at temperatures where no ice formation was possible. Results showed that when sucrose concentration increased, aroma volatility increased except for ethyl hexanoate and in the highest sucrose concentration solution (57.5%). A quasi-linear temperature decrease on aroma volatility was observed in sucrose solutions from 25 to around 4 and 0 degrees C. Then, from 0 to -10 degrees C, aroma volatility did not decrease: ethyl acetate volatility remained constant but that of ethyl hexanoate increased. Enthalpy of vaporization and activity coefficients of the aroma compounds were calculated.

Big Bubbles in Boiling Liquids: Students' Views

ERIC Educational Resources Information Center

Costu, Bayram

2008-01-01

The aim of this study was to elicit students' conceptions about big bubbles in boiling liquids (water, ethanol and aqueous CuSO[subscript 4] solution). The study is based on twenty-four students at different ages and grades. The clinical interviews technique was conducted to solicit students' conceptions and the interviews were analyzed to…

Electromechanical model to predict the movability of liquids in an electrowetting-on-dielectric microfluidic device

NASA Astrophysics Data System (ADS)

Torabinia, Matin; Farzbod, Ali; Moon, Hyejin

2018-04-01

In electrowetting-on-dielectric (EWOD) microfluidics, a motion of a fluid is created by a voltage applied to the fluid/surface interface. Water and aqueous solutions are the most frequently used fluids in EWOD devices. In order for EWOD microfluidics to be a versatile platform for various applications, however, movability of different types of fluids other than aqueous solutions should be understood. An electromechanical model using a simple RC circuit has been used to predict the mechanical force exerted on a liquid droplet upon voltage application. In this present study, two important features missed in previous works are addressed. Energy dissipation by contact line friction is considered in the new model as the form of resistor. The phase angle is taken into account in the analysis of the AC circuit. The new electromechanical model and computation results are validated with experimental measurements of forces on two different liquids. The model is then used to explain influences of contact angle hysteresis, surface tension, conductivity, and dielectric constant of fluids to the mechanical force on a liquid droplet.

Ringer tablet-based ionic liquid phase microextraction: Application in extraction and preconcentration of neonicotinoid insecticides from fruit juice and vegetable samples.

PubMed

Farajzadeh, Mir Ali; Bamorowat, Mahdi; Mogaddam, Mohammad Reza Afshar

2016-11-01

An efficient, reliable, sensitive, rapid, and green analytical method for the extraction and determination of neonicotinoid insecticides in aqueous samples has been developed using ionic liquid phase microextraction coupled with high performance liquid chromatography-diode array detector. In this method, a few microliters of 1-hexyl-3-methylimidazolium hexafluorophosphate (as an extractant) is added onto a ringer tablet and it is transferred into a conical test tube containing aqueous phase of the analytes. By manually shaking, the ringer tablet is dissolved and the extractant is released into the aqueous phase as very tiny droplets to provide a cloudy solution. After centrifuging the extracted analytes into ionic liquid are collected at the bottom of a conical test tube. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 0.12 and 0.33 and 0.41 and 1.11ngmL(-1), respectively. Extraction recoveries and enrichment factors were from 66% to 84% and 655% to 843%, respectively. Finally different aqueous samples were successfully analyzed using the proposed method. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecular species forming at the α-Fe2O3 nanoparticle-aqueous solution interface.

PubMed

Ali, Hebatallah; Seidel, Robert; Pohl, Marvin N; Winter, Bernd

2018-05-21

We report on electronic structure measurements of the interface between hematite nanoparticles (6 nm diameter) and aqueous solutions. Using soft X-ray photoelectron spectroscopy from a liquid microjet we detect valence and core-level photoelectrons as well as Auger electrons from liquid water, from the nanoparticle-water interface, and from the interior of the aqueous-phase nanoparticles. Most noteworthy, the method is shown to be sufficiently sensitive for the detection of adsorbed hydroxyl species, resulting from H 2 O dissociation at the nanoparticle surface in aqueous solution. We obtain signal from surface OH from resonant, non-resonant, and from so-called partial-electron-yield X-ray absorption (PEY-XA) spectra. In addition, we report resonant photoelectron measurements at the iron 2p excitation. The respective Fe iron 2p 3/2 edge (L 3 -edge) PEY-XA spectra exhibit two main absorption peaks with their energies being sensitive to the chemical environment of the Fe 3+ ions at the nanoparticle-solution interface. This manifests in the 10 D q value which is a measure of the ligand-field strength. Furthermore, an observed intensity variation of the pre-peak, when comparing the PEY-XA spectra for different iron Auger-decay channels, can be assigned to different extents of electron delocalization. From the experimental fraction of local versus non-local autoionization signals we then find a very fast, approximately 1 fs, charge transfer time from interfacial Fe 3+ into the environment. The present study, which is complementary to ambient-pressure photoemission studies on solid-electrolyte systems, also highlights the multiple aspects of photoemission that need to be explored for a full characterization of the transition-metal-oxide nanoparticle surface in aqueous phase.

Ionic liquid and aqueous two-phase extraction based on salting-out coupled with high-performance liquid chromatography for the determination of seven rare ginsenosides in Xue-Sai-Tong injection.

PubMed

Li, Lan-Jie; Jin, Yong-Ri; Wang, Xiao-Zhong; Liu, Ying; Wu, Qian; Shi, Xiao-Lei; Li, Xu-Wen

2015-09-01

A method of ionic liquid salt aqueous two-phase extraction coupled with high-performance liquid chromatography has been developed for the analysis of seven rare ginsenosides including Rg6 , F4 , 20(S)-Rg3 , 20(R)-Rg3 , Rk3 , Rk1 , and Rg5 in Xue-Sai-Tong injection. The injection was mixed with ionic liquid 1-butyl-3-methylimidazolium bromide aqueous solution, and a mixture was obtained. With the addition of sodium dodecyl sulfate and dipotassium phosphate into the mixture, the aqueous two-phase mixture was formed after ultrasonic treatment and centrifuged. Rare ginsenosides were extracted into the upper phase. To obtain a high extraction factors, various influences were considered systematically, such as the volume of ionic liquid, the category and amount of salts, the amount of sodium dodecyl sulfate, the pH value of system, and the time of ultrasonic treatment. Under the optimal condition, rare ginsenosides in Xue-Sai-Tong injection were enriched and detected, the recoveries of seven rare ginsenosides ranged from 90.05 to 112.55%, while relative standard deviations were lower than 2.50%. The developed method was reliable, rapid and sensitive for the determination of seven rare ginsenosides in the injections. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A process for the preparation of cysteine from cystine

DOEpatents

Chang, Shih-Ger; Liu, David K.; Griffiths, Elizabeth A.; Littlejohn, David

1989-01-01

The present invention in one aspect relates to a process for the simultaneous removal of NO.sub.x and SO.sub.2 from a fluid stream comprising mixtures thereof and in another aspect relates to the separation, use and/or regeneration of various chemicals contaminated or spent in the process and which includes the steps of: (A) contacting the fluid stream at a temperature of between about 105.degree. and 180.degree. C. with a liquid aqueous slurry or solution comprising an effective amount of an iron chelate of an amino acid moiety having at least one --SH group; (B) separating the fluid stream from the particulates formed in step (A) comprising the chelate of the amino acid moiety and fly ash; (C) washing and separating the particulates of step (B) with an aqeous solution having a pH value of between about 5 to 8; (D) subsequently washing and separating the particulates of step (C) with a strongly acidic aqueous solution having a pH value of between about 1 to 3; (E) washing and separating the particulates of step (D) with an basic aqueous solution having a pH value of between about 9 to 12; (F) optionally adding additional amino acid moiety, iron (II) and alkali to the aqueous liquid from step (D) to produce an aqueous solution or slurry similar to that in step (A) having a pH value of between about 4 to 12; and (G) recycling the aqueous slurry of step (F) to the contacting zone of step (A). Steps (D) and (E) can be carried out in the reverse sequence, however the preferred order is (D) and then (E). In a preferred embodiment the present invention provides an improved process for the preparation (regeneration) of cysteine from cystine, which includes reacting an aqueous solution of cystine at a pH of between about 9 to 13 with a reducing agent selected from hydrogen sulfide or alkali metal sulfides, sulfur dioxide, an alkali metal sulfite or mixtures thereof for a time and at a temperature effective to cleave and reduce the cystine to cysteine with subsequent recovery of the cysteine. In another preferred embodiment the present invention provides a process for the removal of NO.sub.x, SO.sub.2 and particulates from a fluid stream which includes the steps of (A) injecting into a reaction zone an aqueous solution itself comprising (i) an amino acid moiety selected from those described above; (ii) iron (II) ion; and (iii) an alkali, wherein the aqueous solution has a pH of between about 4 and 11; followed by solids separation and washing as is described in steps (B), (C), (D) and (E) above. The overall process is useful to reduce acid rain components from combustion gas sources.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of triazine and triazoles in mineral water samples.

PubMed

Bolzan, Cátia M; Caldas, Sergiane S; Guimarães, Bruno S; Primel, Ednei G

2016-09-01

A simple, rapid, and sensitive method for the determination of atrazine, simazine, cyproconazole, tebuconazole, and epoxiconazole in mineral water employing the dispersive liquid-liquid microextraction with solidification of a floating organic drop with determination by liquid chromatography tandem mass spectrometry has been developed. A mixed solution of 250 μL 1-dodecanol and 1250 μL methanol was injected rapidly into 10 mL aqueous solution (pH 7.0) with 2% w/v NaCl. After centrifugation for 5 min at 2000 rpm, the organic solvent droplets floated on the surface of the aqueous solution and the floating solvent solidified. The method limits of detection were between 3.75 and 37.5 ng/L and limits of quantification were between 12.5 and 125 ng/L. The recoveries ranged from 70 to 118% for repeatability and between 76 and 95% for intermediate precision with a relative standard deviation from 2 to 18% for all compounds. Low matrix effect was observed. The proposed method can be successfully applied in routine analysis for determination of pesticide residues in mineral water samples, allowing for monitoring of triazine and triazoles at levels below the regulatory limits set by international and national legislations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Production of pure metals

NASA Technical Reports Server (NTRS)

Philipp, W. H.; Marsik, S. J.; May, C. E. (Inventor)

1974-01-01

A process for depositing elements by irradiating liquids is reported. Ultra pure elements are precipitated from aqueous solutions or suspensions of compounds. A solution of a salt of a metal to be prepared is irradiated, and the insoluble reaction product settles out. Some chemical compounds may also be prepared in this manner.

Sulfuric Acid and Water: Paradoxes of Dilution

ERIC Educational Resources Information Center

Leenson, I. A.

2004-01-01

On equilibrium properties of aqueous solutions of sulfuric acid, Julius Thomsen has marked that the heat evolved on diluting liquid sulfuric acid with water is a continuous function of the water used, and excluded absolutely the acceptance of definite hydrates as existing in the solution. Information about thermochemical measurement, a discussion…

Method for producing catalysis from coal

DOEpatents

Farcasiu, Malvina; Derbyshire, Frank; Kaufman, Phillip B.; Jagtoyen, Marit

1998-01-01

A method for producing catalysts from coal is provided comprising mixing an aqueous alkali solution with the coal, heating the aqueous mixture to treat the coal, drying the now-heated aqueous mixture, reheating the mixture to form carbonized material, cooling the mixture, removing excess alkali from the carbonized material, and recovering the carbonized material, wherein the entire process is carried out in controlled atmospheres, and the carbonized material is a hydrocracking or hydrodehalogenation catalyst for liquid phase reactions. The invention also provides for a one-step method for producing catalysts from coal comprising mixing an aqueous alkali solution with the coal to create a mixture, heating the aqueous mixture from an ambient temperature to a predetermined temperature at a predetermined rate, cooling the mixture, and washing the mixture to remove excess alkali from the treated and carbonized material, wherein the entire process is carried out in a controlled atmosphere.

Method for producing catalysts from coal

DOEpatents

Farcasiu, M.; Derbyshire, F.; Kaufman, P.B.; Jagtoyen, M.

1998-02-24

A method for producing catalysts from coal is provided comprising mixing an aqueous alkali solution with the coal, heating the aqueous mixture to treat the coal, drying the now-heated aqueous mixture, reheating the mixture to form carbonized material, cooling the mixture, removing excess alkali from the carbonized material, and recovering the carbonized material, wherein the entire process is carried out in controlled atmospheres, and the carbonized material is a hydrocracking or hydrodehalogenation catalyst for liquid phase reactions. The invention also provides for a one-step method for producing catalysts from coal comprising mixing an aqueous alkali solution with the coal to create a mixture, heating the aqueous mixture from an ambient temperature to a predetermined temperature at a predetermined rate, cooling the mixture, and washing the mixture to remove excess alkali from the treated and carbonized material, wherein the entire process is carried out in a controlled atmosphere. 1 fig.

Separation of metals by supported liquid membrane

DOEpatents

Takigawa, Doreen Y.

1992-01-01

A supported liquid membrane system for the separation of a preselected chemical species within a feedstream, preferably an aqueous feedstream, includes a feed compartment containing a feed solution having at least one preselected chemical species therein, a stripping compartment containing a stripping solution therein, and a microporous polybenzimidazole membrane situated between the compartments, the microporous polybenzimidazole membrane containing an extractant mixture selective for the preselected chemical species within the membrane pores is disclosed along with a method of separating preselected chemical species from a feedstream with such a system, and a supported liquid membrane for use in such a system.

Adsorption of benzo(a)pyrene on to asbestos and manmade mineral fibres in an aqueous solution and in a biological model solution.

PubMed Central

Gerde, P; Scholander, P

1988-01-01

The adsorption of benzo(a)pyrene (BaP) on to three types of asbestos (chrysotile antophyllite, and amosite) and three types of manmade mineral fibres (MMMF) (rock wool, slag wool, and glass wool) in a physiological water solution was studied. Adsorption was determined from the decrease in the liquid concentration of BaP on the addition of the solid material. Results show that all the fibres weakly adsorb BaP, approximately within the same order of magnitude. The combined adsorption of BaP and phosphatidylcholine (PC) on to chrysotile and amosite asbestos and on to rock wool in aqueous solution was also studied. PC, one of the major constituents in lung surfactant, forms a separate lipid phase in water consisting of micellar liposomes or lipid bilayers. A decrease in the liquid concentration of PC was found when any of the three materials was added, indicating adsorption of the lipid phase on to the fibres. A coincident decrease in the liquid concentration of BaP was also found indicating that BaP is readily solubilised in PC and will accompany the adsorption of this compound on to the fibres. Owing to the high lipid aqueous partition coefficient of BaP, it is concluded that the direct adsorption of BaP on to the fibres will be negligible when PC is present in the system even at low concentrations. Phospholipid adsorption by the fibres and not their direct adsorption of aromatic hydrocarbons should therefore be the crucial parameter for this indirect interaction between fibres and aromatic hydrocarbons. PMID:3196662

Thermodynamic Modeling of Organic-Inorganic Aerosols with the Group-Contribution Model AIOMFAC

NASA Astrophysics Data System (ADS)

Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.

2009-04-01

Liquid aerosol particles are - from a physicochemical viewpoint - mixtures of inorganic salts, acids, water and a large variety of organic compounds (Rogge et al., 1993; Zhang et al., 2007). Molecular interactions between these aerosol components lead to deviations from ideal thermodynamic behavior. Strong non-ideality between organics and dissolved ions may influence the aerosol phases at equilibrium by means of liquid-liquid phase separations into a mainly polar (aqueous) and a less polar (organic) phase. A number of activity models exists to successfully describe the thermodynamic equilibrium of aqueous electrolyte solutions. However, the large number of different, often multi-functional, organic compounds in mixed organic-inorganic particles is a challenging problem for the development of thermodynamic models. The group-contribution concept as introduced in the UNIFAC model by Fredenslund et al. (1975), is a practical method to handle this difficulty and to add a certain predictability for unknown organic substances. We present the group-contribution model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients), which explicitly accounts for molecular interactions between solution constituents, both organic and inorganic, to calculate activities, chemical potentials and the total Gibbs energy of mixed systems (Zuend et al., 2008). This model enables the computation of vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria within one framework. Focusing on atmospheric applications we considered eight different cations, five anions and a wide range of alcohols/polyols as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are very well represented up to high ionic strength. We show that the semi-empirical middle-range parametrization of direct organic-inorganic interactions in alcohol-water-salt solutions enables accurate computations of vapor-liquid and liquid-liquid equilibria. References Fredenslund, A., Jones, R. L., and Prausnitz, J. M.: Group-Contribution Estimation of Activity Coefficients in Nonideal Liquid Mixtures, AIChE J., 21, 1086-1099, 1975. Rogge, W. F., Mazurek, M. A., Hildemann, L. M., Cass, G. R., and Simoneit, B. R. T.: Quantification of Urban Organic Aerosols at a Molecular Level: Identification, Abundance and Seasonal Variation, Atmos. Environ., 27, 1309-1330, 1993. Zhang, Q. et al.: Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically influenced Northern Hemisphere midlatitudes, Geophys. Res. Lett., 34, L13 801, 2007. Zuend, A., Marcolli, C., Luo, B. P., and Peter, T.: A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients, Atmos. Chem. Phys., 8, 4559-4593, 2008.

Biotoxicity of Mars soils: 2. Survival of Bacillus subtilis and Enterococcus faecalis in aqueous extracts derived from six Mars analog soils

NASA Astrophysics Data System (ADS)

Schuerger, Andrew C.; Ming, Doug W.; Golden, D. C.

2017-07-01

The search for an extant microbiota on Mars depends on exploring sites that contain transient or permanent liquid water near the surface. Examples of possible sites for liquid water may be active recurring slope lineae (RSL) and fluid inclusions in ice or salt deposits. The presence of saline fluids on Mars will act to depress the freezing points of liquid water to as low as ‒60 °C, potentially permitting the metabolism and growth of halophilic microorganisms to temperatures significantly below the freezing point of pure water at 0 °C. In order to predict the potential risks of forward contamination by Earth microorganisms to subsurface sites on Mars with liquid brines, experiments were designed to characterize the short-term survival of two bacteria in aqueous soil solutions from six analog soils. The term ''soil'' is used here to denote any loose, unconsolidated matrix with no implications for the presence or absence of organics or biology. The analog soils were previously described (Schuerger et al., 2012, Planetary Space Sci., 72, 91-101), and represented crushed Basalt (benign control), Salt, Acid, Alkaline, Aeolian, and Phoenix analogs on Mars. The survival rates of spores of Bacillus subtilis and vegetative cells of Enterococcus faecalis were tested in soil solutions from each analog at 24, 0, or ‒70 °C for time periods up to 28 d. Survival of dormant spores of B. subtilis were mostly unaffected by incubation in the aqueous extracts of all six Mars analogs. In contrast, survival rates of E. faecalis cells were suppressed by all soil solutions when incubated at 24 °C but improved at 0 and ‒70 °C, except for assays in the Salt and Acid soil solutions in which most cells were killed. Results suggest that Earth microorganisms that form spores may persist in liquid brines on Mars better than non-spore forming species, and thus, spore-forming species may pose a potential forward contamination risk to sites with liquid brines.

The Electrostatic Screening Length in Concentrated Electrolytes Increases with Concentration.

PubMed

Smith, Alexander M; Lee, Alpha A; Perkin, Susan

2016-06-16

According to classical electrolyte theories interactions in dilute (low ion density) electrolytes decay exponentially with distance, with the Debye screening length the characteristic length scale. This decay length decreases monotonically with increasing ion concentration due to effective screening of charges over short distances. Thus, within the Debye model no long-range forces are expected in concentrated electrolytes. Here we reveal, using experimental detection of the interaction between two planar charged surfaces across a wide range of electrolytes, that beyond the dilute (Debye-Hückel) regime the screening length increases with increasing concentration. The screening lengths for all electrolytes studied-including aqueous NaCl solutions, ionic liquids diluted with propylene carbonate, and pure ionic liquids-collapse onto a single curve when scaled by the dielectric constant. This nonmonotonic variation of the screening length with concentration, and its generality across ionic liquids and aqueous salt solutions, demonstrates an important characteristic of concentrated electrolytes of substantial relevance from biology to energy storage.

Thermal method for cleaning polymer quenching media

NASA Astrophysics Data System (ADS)

Sverdlin, A. V.; Blackwood, R.; Totten, G. E.

1996-06-01

Aqueous solutions of polymers are used for heat treatment, mainly for quenching steels. The most popular and universally used are quenching liquids of the UCON A, E, XT types based on various polyalkylene glycols. In the course of operation these liquids are contaminated by salts retained on the surface of the parts after their heating in salt baths, by ions of heavy metals present in the solution, etc. The paper is devoted to the most popular method for cleaning polymer quenching media, namely, the method of thermal separation.

Room temperature electrodeposition of actinides from ionic solutions

DOEpatents

Hatchett, David W.; Czerwinski, Kenneth R.; Droessler, Janelle; Kinyanjui, John

2017-04-25

Uranic and transuranic metals and metal oxides are first dissolved in ozone compositions. The resulting solution in ozone can be further dissolved in ionic liquids to form a second solution. The metals in the second solution are then electrochemically deposited from the second solutions as room temperature ionic liquid (RTIL), tri-methyl-n-butyl ammonium n-bis(trifluoromethansulfonylimide) [Me.sub.3N.sup.nBu][TFSI] providing an alternative non-aqueous system for the extraction and reclamation of actinides from reprocessed fuel materials. Deposition of U metal is achieved using TFSI complexes of U(III) and U(IV) containing the anion common to the RTIL. TFSI complexes of uranium were produced to ensure solubility of the species in the ionic liquid. The methods provide a first measure of the thermodynamic properties of U metal deposition using Uranium complexes with different oxidation states from RTIL solution at room temperature.

40 CFR 409.31 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... AND STANDARDS SUGAR PROCESSING POINT SOURCE CATEGORY Liquid Cane Sugar Refining Subcategory § 409.31... (raw sugar) contained within aqueous solution at the beginning of the process for production of refined cane sugar. ...

A Designer Fluid for Aluminum Phase Change Devices, Vol. 1 of 3: General Inorganic Aqueous Solution (IAS) Chemistry

DTIC Science & Technology

2016-11-17

region, in which liquid is disconnected with the electrochemical cycle and hydrogen gas will be generated. In addition, with Q increasing, all the...179  5.3.  Importance of a Continuous Liquid Back Flow...used IAS; (c) condensed liquid from the vapor of IAS .................. 49  Figure 25: Contact angle comparison between smooth and IAS treated metal

Application of a thiourea-containing task-specific ionic liquid for the solid-phase extraction cleanup of lead ions from red lipstick, pine leaves, and water samples.

PubMed

Saljooqi, Asma; Shamspur, Tayebeh; Mohamadi, Maryam; Mostafavi, Ali

2014-07-01

Here, task-specific ionic liquid solid-phase extraction is proposed for the first time. In this approach, a thiourea-functionalized ionic liquid is immobilized on the solid sorbent, multiwalled carbon nanotubes. These modified nanotubes packed into a solid-phase extraction column are used for the selective extraction and preconcentration of ultra-trace amounts of lead(II) from aqueous samples prior to electrothermal atomic absorption spectroscopy determination. The thiourea functional groups act as chelating agents for lead ions retaining them and so, give the selectivity to the sorbent. Elution of the retained ions can be performed using an acidic thiourea solution. The effects of experimental parameters including pH of the aqueous solution, type and amount of eluent, and the flow rates of sample and eluent solutions on the separation efficiency are investigated. The linear dependence of absorbance of lead on its concentration in the initial solution is in the range of 0.5-40.0 ng/mL with the detection limit of 0.13 ng/mL (3(Sb)/m, n = 10). The proposed method is applicable to the analysis of red lipstick, pine leaves, and water samples for their lead contents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In-situ ionic liquid dispersive liquid-liquid microextraction using a new anion-exchange reagent combined Fe3O4 magnetic nanoparticles for determination of pyrethroid pesticides in water samples.

PubMed

Fan, Chen; Liang, You; Dong, Hongqiang; Ding, Guanglong; Zhang, Wenbing; Tang, Gang; Yang, Jiale; Kong, Dandan; Wang, Deng; Cao, Yongsong

2017-07-04

In this work, in-situ ionic liquid dispersive liquid-liquid microextraction combined ultrasmall Fe 3 O 4 magnetic nanoparticles was developed as a kind of pretreatment method to detect pyrethroid pesticides in water samples. New anion-exchange reagents including Na[DDTC] and Na[N(CN) 2 ] were optimized for in-situ extraction pyrethroids, which showed enhanced microextraction performance. Pyrethroids were enriched by hydrophilic ionic liquid [P 4448 ][Br] (aqueous solution, 200 μL, 0.2 mmol mL -1 ) reaction in-situ with anion-exchange reagent Na[N(CN) 2 ] (aqueous solution, 300 μL, 0.2 mmol mL -1 ) forming hydrophobic ionic liquid as extraction agent in water sample (10 mL). Ultrasmall superparamagnetic iron oxide nanoparticles (30 mg) were used to collect the mixture of ionic liquid and pyrethroids followed by elution with acetonitrile. The extraction of ionic liquid strategies was unique and efficiently fulfilled with high enrichment factors (176-213) and good recoveries (80.20-117.31%). The method was successively applied to the determination of pyrethroid pesticides in different kinds of water samples with the limits of detection ranged from 0.16 to 0.21 μg L -1 . The proposed method is actually nanometer-level microextraction (average size 80 nm) with the advantages of simplicity, rapidity, and sensitivity. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification of a BrOOO- intermediate species in the ozonolysis of bromide at the liquid/vapor interface from liquid jet XPS

NASA Astrophysics Data System (ADS)

Chen, Shuzhen; Artiglia, Luca; Orlando, Fabrizio; Corral-Arroyo, Pablo; Edebeli, Jacinta; Ammann, Markus

2017-04-01

Oxidation of bromide by gas phase ozone (O3) in the absence of photochemistry is believed to be one of the important dark reactions to produce HOBr as the starting point of the multiphase cycling reaction mechanisms that release bromide out of sea water, sea spray or marine aerosols from aqueous solution that later drive O3 depleting chemistry in the troposphere [1]. The reaction of bromide with O3 occurs through an acid catalyzed mechanism involving a BrOOO- complex as an intermediate [2]. Slow oxidation of bromide by O3 in the bulk aqueous phase is of limited relevance; previous kinetic experiments have suspected the reaction to be enhanced at the surface of aqueous solutions. Thus, identifying BrOOO- at the interface would be a major step to understanding the multiphase oxidation of bromide with O3. Here, we provide a direct experimental evidence for the formation of a BrOOO- reaction intermediate at the surface by investigating the reaction of aqueous solutions NaBr with gas phase O3 after millisecond time scale exposure using the surface sensitive in situ liquid jet X-ray photoelectron spectroscopy (XPS) at the Swiss Light Source (SLS). We acquired Br 3d core level spectra of 0.125 M NaBr solution in presence and absence of ozone in the gas phase. We found a new feature with a peak position shifted towards higher binding energy (by ˜0.7 eV) compared to Br-, which was clearly different from the Br 3d core levels spectra of hypobromite and bromate measured with reference solutions. Our results suggest the appearance of the formation of the BrOOO- reaction intermediate as a new component, in agreement with theoretical calculations of the Br- ozonolysis mechanism [3]. Additionally, by varying the photoelectron kinetic energy and thus probe depth via variation of the probing photon energy, the new feature appears to be present near the liquid/vapor interface. Besides, kinetic experiments for the reaction of O3 with bromide are ongoing to investigate the dependence on the temperature, ozone concentration, which may give further information such as the relative oxidation rate at the liquid/vapor interface versus that in the bulk phase. [1] S. Wang, et al., Proceedings of the National Academy of Sciences, 2015, 112, 9281-9286. [2] Q. Liu, et al., Inorganic Chemistry, 2001, 40, 4436-4442. [3] I. Gladich, et al., The Journal of Physical Chemistry A, 2015, 119, 4482-4488.

Ice growth from supercooled aqueous solutions of benzene, naphthalene, and phenanthrene.

PubMed

Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

2012-08-23

Classical molecular dynamics (MD) were performed to investigate the growth of ice from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene. The main objective of this study is to explore the fate of those aromatic molecules after freezing of the supercooled aqueous solutions, i.e., if these molecules become trapped inside the ice lattice or if they are displaced to the QLL or to the interface with air. Ice growth from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene result in the formation of quasi-liquid layers (QLLs) at the air/ice interface that are thicker than those observed when pure supercooled water freezes. Naphthalene and phenanthrene molecules in the supercooled aqueous solutions are displaced to the air/ice interface during the freezing process at both 270 and 260 K; no incorporation of these aromatics into the ice lattice is observed throughout the freezing process. Similar trends were observed during freezing of supercooled aqueous solutions of benzene at 270 K. In contrast, a fraction of the benzene molecules become trapped inside the ice lattice during the freezing process at 260 K, with the rest of the benzene molecules being displaced to the air/ice interface. These results suggest that the size of the aromatic molecule in the supercooled aqueous solution is an important parameter in determining whether these molecules become trapped inside the ice crystals. Finally, we also report potential of mean force (PMF) calculations aimed at studying the adsorption of gas-phase benzene and phenanthrene on atmospheric air/ice interfaces. Our PMF calculations indicate the presence of deep free energy minima for both benzene and phenanthrene at the air/ice interface, with these molecules adopting a flat orientation at the air/ice interface.

Preliminary study on the photoproduction of hydroxyl radicals in aqueous solution with Aldrich humic acid, algae and Fe(III) under high-pressure mercury lamp irradiation.

PubMed

Liu, Xianli; Xu, Dong; Wu, Feng; Liao, Zhenhuan; Liu, Jiantong; Deng, Nansheng

2004-03-01

Under a high-pressure mercury lamp (HPML) and using an exposure time of 4 h, the photoproduction of hydroxyl radicals (*OH) could be induced in an aqueous solution containing humic acid (HA). Hydroxyl radicals were determined by high-performance liquid chromatography using benzene as a probe. The results showed that *OH photoproduction increased from 1.80 to 2.74 microM by increasing the HA concentration from 10 to 40 mg L(-1) at an exposure time of 4 h (pH 6.5). Hydroxyl radical photoproduction in aqueous solutions of HA containing algae was greater than that in the aqueous solutions of HA without algae. The photoproduction of *OH in the HA solution with Fe(III) was greater than that of the solution without Fe(III) at pH ranging from 4.0 to 8.0. The photoproduction of *OH in HA solution with algae with or without Fe(III) under a 250 W HPML was greater than that under a 125 W HPML. The photoproduction of *OH in irradiated samples was influenced by the pH. The results showed that HPML exposure for 4 h in the 4-8 pH range led to the highest *OH photoproduction at pH 4.0.

Cloud point extraction: an alternative to traditional liquid-liquid extraction for lanthanides(III) separation.

PubMed

Favre-Réguillon, Alain; Draye, Micheline; Lebuzit, Gérard; Thomas, Sylvie; Foos, Jacques; Cote, Gérard; Guy, Alain

2004-06-17

Cloud point extraction (CPE) was used to extract and separate lanthanum(III) and gadolinium(III) nitrate from an aqueous solution. The methodology used is based on the formation of lanthanide(III)-8-hydroxyquinoline (8-HQ) complexes soluble in a micellar phase of non-ionic surfactant. The lanthanide(III) complexes are then extracted into the surfactant-rich phase at a temperature above the cloud point temperature (CPT). The structure of the non-ionic surfactant, and the chelating agent-metal molar ratio are identified as factors determining the extraction efficiency and selectivity. In an aqueous solution containing equimolar concentrations of La(III) and Gd(III), extraction efficiency for Gd(III) can reach 96% with a Gd(III)/La(III) selectivity higher than 30 using Triton X-114. Under those conditions, a Gd(III) decontamination factor of 50 is obtained.

The effect of shear and extensional viscosity on atomization in medical inhaler.

PubMed

Broniarz-Press, L; Ochowiak, M; Matuszak, M; Włodarczak, S

2014-07-01

The paper contains the results of experimental studies of water, aqueous solutions of glycerol and aqueous solutions of glycerol-polyethylene oxide (PEO) atomization process in a medical inhaler obtained by the use of the digital microphotography method. The effect of the shear and extensional viscosity on the drop size, drop size histogram and mean drop diameter has been analyzed. The obtained results have shown that the drop size increases with the increase in shear and extensional viscosity of liquid atomized. Extensional viscosity has a greater impact on the spraying process. It has been shown that the change in liquid viscosity leads to significant changes in drop size distribution. The correlation for Sauter mean diameter as function of the shear and extensional viscosity was proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of electrolytes on bubble coalescence in columns observed with visualization techniques.

PubMed

Aguilera, María Eugenia; Ojeda, Antonieta; Rondón, Carolina; López De Ramos, Aura

2002-10-01

Bubble coalescence and the effect of electrolytes on this phenomenon have been previously studied. This interfacial phenomenon has attracted attention for reactor design/operation and enhanced oil recovery. Predicting bubble coalescence may help prevent low yields in reactors and predict crude oil recovery. Because of the importance of bubble coalescence, the objectives of this work were to improve the accuracy of measuring the percentage of coalescing bubbles and to observe the interfacial gas-liquid behavior. An experimental setup was designed and constructed. Bubble interactions were monitored with a visualization setup. The percentage of air bubble coalescence was 100% in distilled water, about 50% in 0.1 M sodium chloride (NaCl) aqueous solution, and 0% in 0.145 M NaCl aqueous solution. A reduction of the contact gas-liquid area was observed in distillate water. The volume of the resulting bubble was the sum of the original bubble volumes. Repulsion of bubbles was observed in NaCl solutions exceeding 0.07 M. The percentage of bubble coalescence diminishes as the concentration of NaCl chloride increases. High-speed video recording is an accurate technique to measure the percentage of bubble coalescence, and represents an important advance in gas-liquid interfacial studies.

Gas-liquid hybrid discharge-induced degradation of diuron in aqueous solution.

PubMed

Feng, Jingwei; Zheng, Zheng; Luan, Jingfei; Li, Kunquan; Wang, Lianhong; Feng, Jianfang

2009-05-30

Degradation of diuron in aqueous solution by gas-liquid hybrid discharge was investigated for the first time. The effect of output power intensity, pH value, Fe(2+) concentration, Cu(2+) concentration, initial conductivity and air flow rate on the degradation efficiency of diuron was examined. The results showed that the degradation efficiency of diuron increased with increasing output power intensity and increased with decreasing pH values. In the presence of Fe(2+), the degradation efficiency of diuron increased with increasing Fe(2+) concentration. The degradation efficiency of diuron was decreased during the first 4 min and increased during the last 10 min with adding of Cu(2+). Decreasing the initial conductivity and increasing the air flow rate were favorable for the degradation of diuron. Degradation of diuron by gas-liquid hybrid discharge fitted first-order kinetics. The pH value of the solution decreased during the reaction process. Total organic carbon removal rate increased in the presence of Fe(2+) or Cu(2+). The generated Cl(-1), NH(4)(+), NO(3)(-), oxalic acid, acetic acid and formic acid during the degradation process were also detected. Based on the detected Cl(-1) and other intermediates, a possible degradation pathway of diuron was proposed.

On irreversible adsorption of electron-donating compounds in aqueous solution

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

Tamon, Hajime; Atsushi, Masanori; Okazaki, Morio

Activated carbons and synthetic adsorbents have been used for liquid purification and wastewater treatment. The feasibility of an adsorption process depends greatly on the cost of regeneration of spent adsorbents. If irreversible adsorption occurs, regeneration of spent adsorbent is very difficult. Hence, it is very important to understand why irreversible adsorption appears in aqueous solution. In the adsorption of electron-donating compounds such as phenol, aniline, L-phenylalanine, and L-tyrosine from aqueous solution, irreversibility was observed on activated carbon and graphite. The compounds, except L-tyrosine, were reversibly adsorbed on a synthetic adsorbent. In the case where the carbonaceous adsorbents contacted the aqueousmore » solution containing electron-donating compounds for a long time, the irreversible amount adsorbed increased with the contact time. A two-state adsorption model was used to explain why the irreversible adsorption of electron-donating compound appears in aqueous solution. First, the compound is adsorbed in the precursor state for irreversible adsorption, and then moves into its irreversible state over a potential energy barrier after a long contact time. The appearance of irreversible adsorption was qualitatively explained by the two-state adsorption model.« less

Henry Taube and Coordination Chemistry

Science.gov Websites

Shifts Caused by Cr++ in Aqueous Solutions, DOE Technical Report, 1962 Reactions of Solvated Ions Final Report, DOE Technical Report, 1962 Isotopic Discrimination of Some Solutes in Liquid Ammonia, DOE Technical Report, 1966 Final Technical Report of Research, DOE Technical Report, 1972 Top Additional Web

Pretreatment of dried distillers grains with solubles by soaking in aqueous ammonia and subsequent enzymatic/dilute acid hydrolysis to produce fermentable sugars

USDA-ARS?s Scientific Manuscript database

Dried distillers grains with solubles (DDGS), a co-product of corn ethanol production in the dry-grind process, was pretreated by soaking in aqueous ammonia (SAA) using a 15% w/w NH4OH solution at a solid:liquid ratio of 1:10. The effect of pretreatment on subsequent enzymatic hydrolysis was studied...

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.

Free radical generation by ultrasound in aqueous and nonaqueous solutions.

PubMed Central

Riesz, P; Berdahl, D; Christman, C L

1985-01-01

The physical principles underlying the oscillatory behavior of minute gas bubbles in liquids exposed to ultrasound are reviewed. Results from mathematical analyses suggest that these oscillations sometimes become unstable leading to transient cavitation in which a bubble violently collapses during a single acoustic half-cycle producing high temperatures and pressures. The role that micronuclei, resonant bubble size, and rectified diffusion play in the initiation of transient cavitation is explained. Evidence to support these theoretical predictions is presented with particular emphasis on sonoluminescence which provides some non-chemical evidence for the formation of free radicals. Acoustic methods for conducting sonochemical investigations are discussed. In aqueous solutions transient cavitation initially generates hydrogen atoms and hydroxyl radicals which may recombine to form hydrogen and hydrogen peroxide or may react with solutes in the gas phase, at the gas-liquid boundary or in the bulk of the solution. The analogies and differences between sonochemistry and ionizing radiation chemistry are explored. The use of spin trapping and electron spin resonance to identify hydrogen atoms and hydroxyl radicals conclusively and to detect transient cavitation produced by continuous wave and by pulsed ultrasound is described in detail. The study of the chemical effects of cavitation in organic liquids is a relatively unexplored area which has recently become the subject of renewed interest. Examples of the decomposition of solvent and solute, of ultrasonically initiated free-radical polymerization and polymer degradation are presented. Spin trapping has been used to identify radicals in organic liquids, in polymer degradation and in the decomposition of organometallic compounds. PMID:3007091

Surrogate Immiscible Liquid Solution Pairs with Refractive Indexes Matchable Over a Wide Range of Density and Viscosity Ratios

NASA Astrophysics Data System (ADS)

Saksena, Rajat; Christensen, Kenneth T.; Pearlstein, Arne J.

2014-11-01

Use of laser diagnostics in liquid-liquid flows is limited by refractive index mismatch. This can be avoided using a surrogate pair of immiscible index-matched liquids, with density and viscosity ratios matching those of the original liquid pair. We demonstrate that a wide range of density and viscosity ratios is accessible using aqueous solutions of 1,2-propanediol and CsBr (for which index, density, and viscosity are available), and solutions of light and heavy silicone oils and 1-bromooctane (for which we measured the same properties at 119 compositions). For each liquid phase, polynomials in the composition variables were fitted to index and density and to the logarithm of kinematic viscosity, and the fits were used to determine accessible density and viscosity ratios for each matchable index. Index-matched solution pairs can be prepared with density and viscosity ratios equal to those for water-liquid CO2 at 0oC over a range of pressure, and for water-crude oil and water-trichloroethylene, each over a range of temperature. For representative index-matched solutions, equilibration changes index, density, and viscosity only slightly, and chemical analysis show that no component of either solution has significant interphase solubility. Partially supported by Intl. Inst. for Carbon-Neutral Energy Research.

Extraction of dye from aqueous solution in rotating packed bed.

PubMed

Modak, Jayant B; Bhowal, Avijit; Datta, Siddhartha

2016-03-05

The influence of centrifugal acceleration on mass transfer rates in liquid-liquid extraction was investigated experimentally in rotating packed bed (RPB) contactor. The extraction of methyl red using xylene was studied in the equipment. The effect of rotational speed (300-900rpm), flow rate of the aqueous (4.17-20.8×10(-6)m(3)/s), and organic phase (0.83-2.5×10(-6)m(3)/s) on the mass transfer performance was examined. The maximum stage efficiency attained was ∼0.98 at aqueous to organic flow rate ratio of 10. The results suggest that contactor volume required to carry out a given separation can be reduced by an order of magnitude with RPB in comparison to conventional extractors. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of Electric Field on the Wetting Behavior of Eutectic Gallium-Indium Alloys in Aqueous Environment

NASA Astrophysics Data System (ADS)

Yuan, Bo; He, Zhi-Zhu; Liu, Jing

2018-02-01

Room-temperature liquid metals have many intriguing properties that have not previously been fully understood. Among them, surface tension behaviors of such metals are especially critical in a group of newly emerging areas such as printed electronics, functional materials and soft machines, etc. This study is dedicated to clarifying the wettability of liquid metals on various substrate surfaces with varied roughness immersed in solutions when subject to an electric field. The contact angles of Ga75.5In24.5 in several typical liquids were comprehensively measured and interpreted, and were revealed to be affected by the components and concentration of the environmental solution. Meanwhile, the roughness of the substrates is also revealed to be an important parameter dominating the process. The dynamic wetting behaviors of liquid metal in aqueous environment under an electric field were quantified. The contact angle values of eutectic gallium-indium alloys (eGaIn) on titanium substrates with different roughness would lead to better electrowetting performances on rougher surfaces. In particular, using an electrical field to control the wetting status of liquid metal with the matching substrate have been illustrated, which would offer a practical way to flexibly control liquid metal-based functional devices working in an aqueous environment. Furthermore, Lippmann-Young's equation reveals the relationship between contact angle and applied voltage, explaining the excellent electrowetting property of eGaIn. The power law, R = αt β , was adopted to characterize the two-stage wetting process of eGaIn under different voltages. In the initial process, β ≈ 1/2 represents the complete wetting law, while the later one, β ≈ 1/10, meets with Tanner's law of a drop spontaneously spreading on a smooth surface.

Organic aerogel microspheres

DOEpatents

Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

1999-06-01

Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Organic aerogel microspheres

DOEpatents

Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

1999-01-01

Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Organic aerogel microspheres and fabrication method therefor

DOEpatents

Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

1996-04-16

Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Organic aerogel microspheres and fabrication method therefor

DOEpatents

Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

1996-01-01

Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

Cloud point phenomena for POE-type nonionic surfactants in a model room temperature ionic liquid.

PubMed

Inoue, Tohru; Misono, Takeshi

2008-10-15

The cloud point phenomenon has been investigated for the solutions of polyoxyethylene (POE)-type nonionic surfactants (C(12)E(5), C(12)E(6), C(12)E(7), C(10)E(6), and C(14)E(6)) in 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), a typical room temperature ionic liquid (RTIL). The cloud point, T(c), increases with the elongation of the POE chain, while decreases with the increase in the hydrocarbon chain length. This demonstrates that the solvophilicity/solvophobicity of the surfactants in RTIL comes from POE chain/hydrocarbon chain. When compared with an aqueous system, the chain length dependence of T(c) is larger for the RTIL system regarding both POE and hydrocarbon chains; in particular, hydrocarbon chain length affects T(c) much more strongly in the RTIL system than in equivalent aqueous systems. In a similar fashion to the much-studied aqueous systems, the micellar growth is also observed in this RTIL solvent as the temperature approaches T(c). The cloud point curves have been analyzed using a Flory-Huggins-type model based on phase separation in polymer solutions.

Multiple pathways of crystal nucleation in an extremely supersaturated aqueous potassium dihydrogen phosphate (KDP) solution droplet

PubMed Central

Lee, Sooheyong; Wi, Haeng Sub; Jo, Wonhyuk; Cho, Yong Chan; Lee, Hyun Hwi; Jeong, Se-Young; Kim, Yong-Il; Lee, Geun Woo

2016-01-01

Solution studies have proposed that crystal nucleation can take more complex pathways than previously expected in classical nucleation theory, such as formation of prenucleation clusters or densified amorphous/liquid phases. These findings show that it is possible to separate fluctuations in the different order parameters governing crystal nucleation, that is, density and structure. However, a direct observation of the multipathways from aqueous solutions remains a great challenge because heterogeneous nucleation sites, such as container walls, can prevent these paths. Here, we demonstrate the existence of multiple pathways of nucleation in highly supersaturated aqueous KH2PO4 (KDP) solution using the combination of a containerless device (electrostatic levitation), and in situ micro-Raman and synchrotron X-ray scattering. Specifically, we find that, at an unprecedentedly deep level of supersaturation, a high-concentration KDP solution first transforms into a metastable crystal before reaching stability at room temperature. However, a low-concentration solution, with different local structures, directly transforms into the stable crystal phase. These apparent multiple pathways of crystallization depend on the degree of supersaturation. PMID:27791068

Multiple pathways of crystal nucleation in an extremely supersaturated aqueous potassium dihydrogen phosphate (KDP) solution droplet.

PubMed

Lee, Sooheyong; Wi, Haeng Sub; Jo, Wonhyuk; Cho, Yong Chan; Lee, Hyun Hwi; Jeong, Se-Young; Kim, Yong-Il; Lee, Geun Woo

2016-11-29

Solution studies have proposed that crystal nucleation can take more complex pathways than previously expected in classical nucleation theory, such as formation of prenucleation clusters or densified amorphous/liquid phases. These findings show that it is possible to separate fluctuations in the different order parameters governing crystal nucleation, that is, density and structure. However, a direct observation of the multipathways from aqueous solutions remains a great challenge because heterogeneous nucleation sites, such as container walls, can prevent these paths. Here, we demonstrate the existence of multiple pathways of nucleation in highly supersaturated aqueous KH 2 PO 4 (KDP) solution using the combination of a containerless device (electrostatic levitation), and in situ micro-Raman and synchrotron X-ray scattering. Specifically, we find that, at an unprecedentedly deep level of supersaturation, a high-concentration KDP solution first transforms into a metastable crystal before reaching stability at room temperature. However, a low-concentration solution, with different local structures, directly transforms into the stable crystal phase. These apparent multiple pathways of crystallization depend on the degree of supersaturation.

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

NASA Astrophysics Data System (ADS)

Suchomel, Eric J.; Ramsburg, C. Andrew; Pennell, Kurt D.

2007-12-01

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween® 80) and sodium dihexyl sulfosuccinate (Aerosol® MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl 2 yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (> 30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR = 1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (< 5%) occurring when the total trapping number exceeded 2 × 10 - 5 . These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.

Long-living nanobubbles of dissolved gas in aqueous solutions of salts and erythrocyte suspensions.

PubMed

Bunkin, Nikolai F; Ninham, Barry W; Ignatiev, Pavel S; Kozlov, Valery A; Shkirin, Alexey V; Starosvetskij, Artem V

2011-03-01

Results of experiments combining laser modulation interference microscopy and Mueller matrix scatterometry show that macroscopic scatterers of light are present in liquids free of external solid impurities. Experimental data on distilled water and aqueous NaCl solutions of various concentrations as well as physiological saline solution are reported. The experimental data can be interpreted by using a model of micron-scale clusters composed of polydisperse air nanobubbles having effective radii of 70-100 nm. Their concentration increases with the growth of ionic content. We hypothesize that under certain conditions those clusters of nanobubbles can affect the erythrocyte structure. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aqueous penetration and biological activity of moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% solution in cataract surgery patients.

PubMed

Kim, Dianne H; Stark, Walter J; O'Brien, Terrence P; Dick, James D

2005-11-01

To measure the achievable perioperative aqueous concentration of the commercially available topically administered fourth generation fluoroquinolones, moxifloxacin 0.5% ophthalmic solution, and gatifloxacin 0.3% ophthalmic solution, and to correlate this concentration with the agents' biological efficacy in the aqueous humor of patients undergoing routine cataract surgery. Prospective, randomized, parallel, double-masked, clinical trial. Fifty patients undergoing cataract extraction. Patients (n = 25) were given perioperative topical moxifloxacin 0.5% or topical gatifloxacin 0.3% (n = 25). One drop of antibiotic was administered every 10 minutes for 4 doses beginning 1 hour prior to surgery. Aqueous humor was sampled via paracentesis and antibiotic concentrations were determined using validated high performance liquid chromatography (HPLC) procedures. Dilution analyses were performed to determine the biological efficacy of the agents in the aqueous against Staphylococcus epidermidis, the most common cause of postcataract endophthalmitis. Aqueous humor antibiotic concentrations were measured using HPLC and microdilution bioassay techniques. Biological activity was measured as minimal inhibitory dilution and minimal bactericidal dilution. Aqueous humor concentrations for moxifloxacin via HPLC analysis were 1.80 (+/-1.21) microg/ml, whereas those for gatifloxacin were 0.48 (+/-0.34) microg/ml. This 3.8-fold difference in aqueous humor antibiotic concentrations was statistically significant (P = 0.00003). Similarly, the biological dilution analysis of the aqueous humor samples showed that moxifloxacin attained an estimated activity of 2.1 microg/ml, whereas the gatifloxacin activity was approximately 0.4 mug/ml, which represented a 4.9-fold difference. This study demonstrated that after topically administered perioperative antibiotics with cataract surgery, moxifloxacin 0.5% ophthalmic solution achieved a statistically significantly higher concentration in aqueous humor compared with gatifloxacin (P = 0.00003). Results from the broth dilution analysis showed that moxifloxacin 0.5% was biologically more active against S. epidermidis than gatifloxacin 0.3% in aqueous humor after topical application. There were no adverse events reported, and incision wounds healed quickly and as expected.

An ex vivo human aqueous humor-concentration comparison of two commercial bromfenac formulations

PubMed Central

Walters, Thomas R; Smyth-Medina, Robert J; Cockrum, Paul C

2018-01-01

Purpose The purpose of this study was to quantify the concentration of bromfenac in the aqueous humor utilizing high-performance liquid chromatography mass spectrometry between two commercial nonsteroidal anti-inflammatory drugs, using aqueous humor concentrations to characterize pharmacokinetic proportional differences between 0.075% bromfenac ophthalmic solution in DuraSite (BromSite®) and 0.09% bromfenac ophthalmic solution (Bromday®). Methods In this multicenter, randomized, double-masked, two-arm, parallel-group, comparative, Phase II clinical trial, subjects were assigned to receive bromfenac in DuraSite or bromfenac ophthalmic solution in a 1:1 ratio. One drop of the masked test article was instilled into the study eye once a day for 2 days prior to and 3 hours prior (last instillation) to the subject’s cataract surgery. Aqueous humor samples were collected upon initial cataract incision for analysis of bromfenac levels. The primary end point was aqueous humor concentration of bromfenac at Day 3, at the initiation of cataract surgery. Aqueous humor samples were collected and analyzed for bromfenac levels. Results A total of 60 subjects completed the study, 30 in each group. The mean bromfenac aqueous humor concentration in subjects who received bromfenac in DuraSite was more than twice (49.33±41.87 ng/mL, P=0.004) that of subjects who received bromfenac ophthalmic solution (23.65±16.31 ng/mL) after three doses. Conclusion Mean bromfenac aqueous humor concentration in subjects receiving the DuraSite-containing bromfenac in DuraSite (0.075%) was significantly higher compared to subjects receiving bromfenac ophthalmic solution (0.09%) after 3 days of dosing. PMID:29849449

An improved model for the calculation of CO2 solubility in aqueous solutions containing Na+, K+, Ca2+, Mg2+, Cl-, and SO42-

USGS Publications Warehouse

Duan, Zhenhao; Sun, R.; Zhu, Chen; Chou, I.-Ming

2006-01-01

An improved model is presented for the calculation of the solubility of carbon dioxide in aqueous solutions containing Na+, K+, Ca2+, Mg2+, Cl-, and SO42- in a wide temperature-pressure-ionic strength range (from 273 to 533 K, from 0 to 2000 bar, and from 0 to 4.5 molality of salts) with experimental accuracy. The improvements over the previous model [Duan, Z. and Sun, R., 2003. An improved model calculating CO2 solubility in pure water and aqueous NaCl solutions from 273 to 533K and from 0 to 2000 bar. Chemical Geology, 193: 257-271] include: (1) By developing a non-iterative equation to replace the original equation of state in the calculation of CO 2 fugacity coefficients, the new model is at least twenty times computationally faster and can be easily adapted to numerical reaction-flow simulator for such applications as CO2 sequestration and (2) By fitting to the new solubility data, the new model improved the accuracy below 288 K from 6% to about 3% of uncertainty but still retains the high accuracy of the original model above 288 K. We comprehensively evaluate all experimental CO2 solubility data. Compared with these data, this model not only reproduces all the reliable data used for the parameterization but also predicts the data that were not used in the parameterization. In order to facilitate the application to CO2 sequestration, we also predicted CO2 solubility in seawater at two-phase coexistence (vapor-liquid or liquid-liquid) and at three-phase coexistence (CO2 hydrate-liquid water-vapor CO2 [or liquid CO2]). The improved model is programmed and can be downloaded from the website http://www.geochem-model.org/programs.htm. ?? 2005 Elsevier B.V. All rights reserved.

Experimental investigation of the phase equilibria in the carbon dioxide-propane-3 M MDEA system

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

Jou, F.Y.; Mather, A.E.; Otto, F.D.

1995-07-01

The treating of liquefied petroleum gas (LPG) to remove carbon dioxide and hydrogen sulfide using aqueous alkanolamine solutions is an important aspect of gas processing. One of the amines used in the natural gas industry is methyldiethanolamine (MDEA). Measurements of the phase equilibria in the carbon dioxide-propane-3 M MDEA system have been made at 25 and 40 C at pressures up to 15.5 MPa. Vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibria were determined. The vapor-liquid equilibrium data were compared with the model of Deshmukh and Mather.

Measurements of liquid film thickness, concentration, and temperature of aqueous urea solution by NIR absorption spectroscopy

NASA Astrophysics Data System (ADS)

Pan, R.; Jeffries, J. B.; Dreier, T.; Schulz, C.

2016-01-01

A multi-wavelength near-infrared (NIR) diode laser absorption sensor has been developed and demonstrated for real-time monitoring of the thickness, solute concentration, and temperature of thin films of urea-water solutions. The sensor monitors the transmittance of three near-infrared diode lasers through the thin liquid film. Film thickness, urea mass fraction, and liquid temperature were determined from measured transmittance ratios of suitable combinations of lasers. Available laser wavelengths were selected depending on the variation of the NIR absorption spectrum of the solution with temperature and solute concentration. The spectral database was measured by a Fourier transform infrared spectrometer in the range 5500-8000 cm-1 for urea solutions between 5 and 40 wt% and temperatures between 298 and 338 K. A prototype sensor was constructed, and the sensor concept was first validated with measurements using a calibration cell providing liquid layers of variable thickness (200-1500 µm), urea mass fraction (5-40 wt%) and temperature (298-318 K). Temporal variations of film thickness and urea concentration were captured during the constant-temperature evaporation of a liquid film deposited on an optically polished heated quartz flat.

Lignin transformations and reactivity upon ozonation in aqueous media

NASA Astrophysics Data System (ADS)

Khudoshin, A. G.; Mitrofanova, A. N.; Lunin, V. V.

2012-03-01

The reaction of ozone with lignin in aqueous acidic solutions is investigated. The Danckwerst model is used to describe the kinetics of gas/liquid processes occurring in a bubble reactor. The efficient ozonation rate of a soluble lignin analog, sodium lignosulfate, is determined. The main lines of the reaction between ozone and lignin are revealed on the basis of kinetic analysis results and IR and UV spectroscopy data.

Liquid junction schottky barrier solar cell

DOEpatents

Williams, Richard

1980-01-01

A mixture of ceric ions (Ce.sup.+4) and cerous ions (Ce.sup.+3) in an aqueous electrolyte solution forms a Schottky barrier at the interface between an active region of silicon and the electrolyte solution. The barrier height obtained for hydrogenated amorphous silicon using the Ce.sup.+4 /Ce.sup.+3 redox couple is about 1.7 eV.

Components of released liquid from ultrasonic waste activated sludge disintegration.

PubMed

Wang, Fen; Lu, Shan; Ji, Min

2006-05-01

Ultrasound can be applied as a pretreatment to disintegrate sludge. In this paper, by observing the solution concentration of polysaccharide, protein, DNA, Ca and Mg before and after disintegration, the main components in the released liquid are analyzed. It has been found that the predominant component of the released liquid in this research is protein. Ultrasound can destroy the extracellular polymeric substances (EPS), which is important to the sludge flocs structure. Ca2+ and Mg2+, which play a key role in binding the EPS are released into the aqueous phase. As a result, the sludge flocs are loosened. Under the effect of the hydraulic shear force, the sludge is disintegrated. Then the hydraulic shear forces destroy the cell walls, the substances inside the cells are released into the aqueous phase.

Inclusion complex formation of ionic liquids with 4-sulfonatocalixarenes studied by competitive binding of berberine alkaloid fluorescent probe

NASA Astrophysics Data System (ADS)

Miskolczy, Zsombor; Biczók, László

2009-07-01

A clinically important natural isoquinoline alkaloid, berberine, was used as a fluorescent probe to study the encapsulation of 1-alkyl-3-methylimidazolium (C nMIm +) type ionic liquids in 4-sulfonato-substituted calix[4]arene (SCX4) and calix[6]arene (SCX6) at pH 2. Addition of ionic liquids to the aqueous solution of berberine-SCXn inclusion complexes brought about considerable fluorescence intensity diminution due to the extrusion of berberine from the macrocycle into the aqueous phase by the competitive inclusion of C nMIm + cation. The lengthening of the aliphatic side chain of the imidazolium moiety diminished the equilibrium constant of complexation with SCX4, but enhanced the stability of SCX6 complexes. Larger binding strength was found for SCX4.

Thermal analysis of a growing crystal in an aqueous solution

NASA Astrophysics Data System (ADS)

Shiomi, Yuji; Kuroda, Toshio; Ogawa, Tomoya

1980-10-01

The temperature profiles around growing crystals in aqueous solutions of Rochelle salt were measured with accuracy of 0.005°C in a two-dimensional cell which was used for elimination of thermal convection current in the cell. The temperature distribution became stationary after 2 h from injection of the mother liquid, but the concentration distribution did not become stationary because the diffusion constant of solute in the solution was much smaller than the thermal diffusivity of the solution. The growth rate was linearly proportional to the temperature gradient at every growing interface. Since crystal growth is a typical interaction process between thermal and material flow, the experimental results were analysed by such an interaction model. The analysis confirms that the material flow is limited by diffusion within a layer width of about a few hundreds micrometers on the growing interface.

Interaction of a sodium ion with the water liquid-vapor interface

NASA Technical Reports Server (NTRS)

Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)

1989-01-01

Molecular dynamics results are presented for the density profile of a sodium ion near the water liquid-vapor interface at 320 K. These results are compared with the predictions of a simple dielectric model for the interaction of a monovalent ion with this interface. The interfacial region described by the model profile is too narrow and the profile decreases too abruptly near the solution interface. Thus, the simple model does not provide a satisfactory description of the molecular dynamics results for ion positions within two molecular diameters from the solution interface where appreciable ion concentrations are observed. These results suggest that surfaces associated with dielectric models of ionic processes at aqueous solution interfaces should be located at least two molecular diameters inside the liquid phase. A free energy expense of about 2 kcal/mol is required to move the ion within two molecular layers of the free water liquid-vapor interface.

A liquid-liquid transition in supercooled aqueous solution related to the HDA-LDA transition

NASA Astrophysics Data System (ADS)

Woutersen, Sander; Ensing, Bernd; Hilbers, Michiel; Zhao, Zuofeng; Angell, C. Austen

2018-03-01

Simulations and theory suggest that the thermodynamic anomalies of water may be related to a phase transition between two supercooled liquid states, but so far this phase transition has not been observed experimentally because of preemptive ice crystallization. We used calorimetry, infrared spectroscopy, and molecular dynamics simulations to investigate a water-rich hydrazinium trifluoroacetate solution in which the local hydrogen bond structure surrounding a water molecule resembles that in neat water at elevated pressure, but which does not crystallize upon cooling. Instead, this solution underwent a sharp, reversible phase transition between two homogeneous liquid states. The hydrogen-bond structures of these two states are similar to those established for high- and low-density amorphous (HDA and LDA) water. Such structural similarity supports theories that predict a similar sharp transition in pure water under pressure if ice crystallization could be suppressed.

Imaging trypsin activity through changes in the orientation of liquid crystals coupled to the interactions between a polyelectrolyte and a phospholipid layer.

PubMed

Hu, Qiong-Zheng; Jang, Chang-Hyun

2012-03-01

In this study, we developed a new type of liquid crystal (LC)-based sensor for the real-time and label-free monitoring of enzymatic activity through changes in the orientation of LCs coupled to the interactions between polyelectrolyte and phospholipid. The LCs changed from dark to bright after an aqueous solution of poly-l-lysine (PLL) was transferred onto a self-assembled monolayer of the phospholipid, dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DOPG), at the aqueous/LC interface. Interactions between the positively charged PLL and the negatively charged DOPG drove the reorganization of the phospholipid membrane, which induced an orientational transition in the LCs from a homeotropic to planar state. Since the serine endopeptidase trypsin can enzymatically catalyze the hydrolysis of PLL, the dark-to-bright shift in the optical response was not observed after transferring a mixed solution of PLL and trypsin onto the DOPG-decorated LC interface, indicating that no orientational transitions in the LCs occurred. However, the optical response from dark to bright was observed when the mixture in the optical cell was replaced by an aqueous solution of PLL. Control experiments with trypsin or an aqueous mixture of PLL and deactivated trypsin further confirmed the feasibility of this approach. The detection limit of trypsin was determined to be ~1 μg/mL. This approach holds great promise for use in the development of LC-based sensors for the detection of enzymatic reactions in cases where the biological polyelectrolyte substrates of enzymes could disrupt the organization of the membrane and induce orientational transitions of LCs at the aqueous/LC interface. © 2012 American Chemical Society

Ionic liquids modified graphene oxide composites: a high efficient adsorbent for phthalates from aqueous solution

PubMed Central

Zhou, Xinguang; Zhang, Yinglu; Huang, Zuteng; Lu, Dingkun; Zhu, Anwei; Shi, Guoyue

2016-01-01

In 2015, more than 30% of erasers were found to contain a PAE content that exceeded the 0.1% limit established by the Quality and Technology Supervision Bureau of Jiangsu Province in China. Thus, strengthening the supervision and regulation of the PAE content in foods and supplies, in particular, remains necessary. Graphene oxide (GO) and its composites have drawn great interests as promising adsorbents for polar and nonpolar compounds. However, GO-based adsorbents are typically restricted by the difficult separation after treatment because of the high pressure in filtration and low density in centrifugation. Herein, a series of novel ionic liquids modified graphene oxide composites (GO-ILs) were prepared as adsorbents for phthalates (PAEs) in eraser samples, which overcame the conventional drawbacks. These novel composites have a combination of the high surface area of graphene oxide and the tunability of the ionic liquids. It is expected that the GO-ILs composites can be used as efficient adsorbents for PAEs from aqueous solution. This work also demonstrated a new technique for GO-based materials applied in sample preparation. PMID:27910926

Adsorption of malachite green from aqueous solution by using novel chitosan ionic liquid beads.

PubMed

Naseeruteen, Faizah; Hamid, Nur Shahirah Abdul; Suah, Faiz Bukhari Mohd; Ngah, Wan Saime Wan; Mehamod, Faizatul Shimal

2018-02-01

Chitosan ionic liquid beads were prepared from chitosan and 1-butyl-3-methylimidazolium based ionic liquids to remove Malachite Green (MG) from aqueous solutions. Batch adsorption experiments were carried out as a function of initial pH, adsorbent dosage, agitation time and initial MG concentration. The optimum conditions were obtained at pH 4.0, 0.008g of adsorbent dosage and 20min of agitation time were utilized in the kinetic and isotherm studies. Three kinetic models were applied to analyze the kinetic data and pseudo-second order was found to be the best fitted model with R 2 >0.999. In order to determine the adsorption capacity, the sorption data were analyzed using the linear form of Langmuir, Freundlich and Temkin equations. The isotherm was best fitted by Langmuir isotherm model. The maximum adsorption capacity (q max ) obtained from Langmuir isotherm for two chitosan beads 1-butyl-3-methylimidazolium acetate A and 1-butyl-3-methylimidazolium B are 8.07mgg -1 and 0.24mgg -1 respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Ionic liquids modified graphene oxide composites: a high efficient adsorbent for phthalates from aqueous solution

NASA Astrophysics Data System (ADS)

Zhou, Xinguang; Zhang, Yinglu; Huang, Zuteng; Lu, Dingkun; Zhu, Anwei; Shi, Guoyue

2016-12-01

In 2015, more than 30% of erasers were found to contain a PAE content that exceeded the 0.1% limit established by the Quality and Technology Supervision Bureau of Jiangsu Province in China. Thus, strengthening the supervision and regulation of the PAE content in foods and supplies, in particular, remains necessary. Graphene oxide (GO) and its composites have drawn great interests as promising adsorbents for polar and nonpolar compounds. However, GO-based adsorbents are typically restricted by the difficult separation after treatment because of the high pressure in filtration and low density in centrifugation. Herein, a series of novel ionic liquids modified graphene oxide composites (GO-ILs) were prepared as adsorbents for phthalates (PAEs) in eraser samples, which overcame the conventional drawbacks. These novel composites have a combination of the high surface area of graphene oxide and the tunability of the ionic liquids. It is expected that the GO-ILs composites can be used as efficient adsorbents for PAEs from aqueous solution. This work also demonstrated a new technique for GO-based materials applied in sample preparation.

The development of a novel wound healing material, silk-elastin sponge.

PubMed

Kawabata, Shingo; Kawai, Katsuya; Somamoto, Satoshi; Noda, Kazuo; Matsuura, Yoshitaka; Nakamura, Yoko; Suzuki, Shigehiko

2017-12-01

Silk-elastin is a recombinant protein polymer with repeating units of silk and elastin blocks. This novel wound healing promoting material has the ability to self-assemble from a liquid to a gel. We have already reported that an aqueous solution of silk-elastin has the potential to accelerate wound healing; however, there are several problems in applying silk-elastin in the clinical setting. To solve these problems, we developed a silk-elastin sponge that is easy to use in the clinical setting. In the present study, we examined whether the wound healing effect of the silk-elastin sponge is equal to the aqueous solution of silk-elastin in vivo. The granulation tissue formation promoting effect of the silk-elastin sponge was equal to that of the aqueous solution the silk-elastin, as after application to the wound surface, the sponge was absorbed and dissolved by the exudate. At body temperature the silk-elastin then formed temperature gel. The silk-elastin gel that was obtained contained abundant cytokines from the exudate. We believe that silk-elastin sponge can be applied to various wounds that are difficult to treat with the aqueous solution.

High energy supercapattery with an ionic liquid solution of LiClO4.

PubMed

Yu, Linpo; Chen, George Z

2016-08-15

A supercapattery combining an ideally polarized capacitor-like electrode and a battery-like electrode is demonstrated theoretically and practically using an ionic liquid electrolyte containing 1-butyl-1-methylpyrrolidinium tri(pentafluoroethyl)trifluorophosphate (BMPyrrFAP), gamma-butyrolactone (γ-GBL) and LiClO4. The electrochemical deposition and dissolution of lithium metal on a platinum and glass carbon electrode were investigated in this ionic liquid solution. The CVs showed that the fresh electrochemically deposited lithium metal was stable in the electrolyte, which encouraged the investigation of this ionic liquid solution in a supercapattery with a lithium battery negative electrode. The active material counted specific energy of the supercapattery based on a lithium negative electrode and an activated carbon (Act-C) positive electrode could reach 230 W h kg(-1) under a galvanostatic charge-discharge current density of 1 mA cm(-2). The positive electrode material (Act-C) was also investigated by CV, AC impedance, SEM and BET. The non-uniform particle size and micropores dominated porous structure of the Act-C enabled its electric double layer capacitor (EDLC) behavior in the ionic liquid solution. The measured specific capacitance of the Act-C in this ionic liquid solution is higher than the same Act-C in aqueous solution, which indicates the Act-C can also perform well in the ionic liquid electrolyte.

Method for removing trace pollutants from aqueous solutions

DOEpatents

Silver, Gary L.

1986-01-01

A method of substantially removing a trace metallic contaminant from a liquid containing the same comprises, adding an oxidizing agent to a liquid containing a trace amount of a metallic contaminant of a concentration of up to about 10.sup.-1 ppm, the oxidizing agent being one which oxidizes the contaminant to form an oxidized product which is insoluble in the liquid and precipitates therefrom, and the conditions of the addition being selected to ensure that the precipitation of the oxidized product is homogeneous, and separating the homogeneously precipitated product from the liquid.

Micro- and Nano-Liquid Phases Coexistent with Ice as Separation and Reaction Media.

PubMed

Okada, Tetsuo

2017-04-01

Ice has a variety of scientifically interesting features, some of which have not been reasonably interpreted despite substantial efforts by researchers. Most chemical studies of ice have focused on the elucidation of its physicochemical nature and its roles in the natural environment. Ice often contains impurities, such as salts, and in such cases, a liquid phase coexists with solid ice over a wide temperature range. This impure ice also acts as a cryoreactor, governing the circulation of chemical species of environmental importance. Reactions and phenomena occurring in this liquid phase show features different from those seen in normal bulk aqueous solutions. In the present account, we discuss the chemical characteristics of the liquid phase that develops in a frozen aqueous phase and show how novel analytical systems can be designed based on he features of the liquid phase which are predictable in some cases but unpredictable in others. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultra-preconcentration and determination of selected pharmaceutical and personal care products in different water matrices by solid-phase extraction combined with dispersive liquid-liquid microextraction prior to ultra high pressure liquid chromatography tandem mass spectrometry analysis.

PubMed

Celano, Rita; Piccinelli, Anna Lisa; Campone, Luca; Rastrelli, Luca

2014-08-15

Pharmaceutical and personal care products (PPCPs) are one of the most important classes of emerging contaminants. The potential of ecological and environmental impacts associated with PPCPs are of particular concern because they continually penetrate the aquatic environment. This work describes a novel ultra-preconcentration technique for the rapid and highly sensitive analysis of selected PPCPs in environmental water matrices at ppt levels. Selected PPCPs were rapidly extracted and concentrated from large volumes of aqueous solutions (500 and 250mL) by solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) and then analyzed using UHPLC-MS/MS. Experimental parameters were carefully investigated and optimized to achieve the best SPE-DLLME efficiency and higher enrichment factors. The best results were obtained using the ternary mixture acetonitrile/methanol/dichloromethane 3:3:4, v/v/v, both as SPE eluent and DLLME extractant/dispersive mixture. DLLME aqueous solution (5% NaCl, 10mgL(-1) TBAB) was also modified to improve the extraction efficiency of more hydrophilic PPCPs. Under the optimal conditions, an exhaustive extraction for most of the investigated analytes (recoveries >70%), with a precision (RSD <10%) and very high enrichment factors were attained for different aqueous matrices (drinking, sea, river and wastewater). Method detection and quantification limits were at very low ppt levels and below 1 and 3ngL(-1), respectively, for 15 of selected PPCPs. The proposed analytical procedure offers numerous advantages such as the simplicity of operation, rapidity, a high enrichment factor and sensitivity. So it is suitable for monitoring and studies of occurrence of PPCPs in different environmental compartments. Copyright © 2014 Elsevier B.V. All rights reserved.

Removing sulphur oxides from a fluid stream

DOEpatents

Katz, Torsten; Riemann, Christian; Bartling, Karsten; Rigby, Sean Taylor; Coleman, Luke James Ivor; Lail, Marty Alan

2014-04-08

A process for removing sulphur oxides from a fluid stream, such as flue gas, comprising: providing a non-aqueous absorption liquid containing at least one hydrophobic amine, the liquid being incompletely miscible with water; treating the fluid stream in an absorption zone with the non-aqueous absorption liquid to transfer at least part of the sulphur oxides into the non-aqueous absorption liquid and to form a sulphur oxide-hydrophobic amine-complex; causing the non-aqueous absorption liquid to be in liquid-liquid contact with an aqueous liquid whereby at least part of the sulphur oxide-hydrophobic amine-complex is hydrolyzed to release the hydrophobic amine and sulphurous hydrolysis products, and at least part of the sulphurous hydrolysis products is transferred into the aqueous liquid; separating the aqueous liquid from the non-aqueous absorption liquid. The process mitigates absorbent degradation problems caused by sulphur dioxide and oxygen in flue gas.

Various nanoparticle morphologies and surface properties of waterborne polyurethane controlled by water

PubMed Central

Zhou, Xing; Fang, Changqing; Lei, Wanqing; Du, Jie; Huang, Tingyi; Li, Yan; Cheng, Youliang

2016-01-01

Water plays important roles in organic reactions such as polyurethane synthesis, and the aqueous solution environment affects polymer morphology and other properties. This paper focuses on the morphology and surface properties of waterborne polyurethane resulting from the organic reaction in water involving different forms (solid and liquid), temperatures and aqueous solutions. We provide evidence from TEM observations that the appearance of polyurethane nanoparticles in aqueous solutions presents diverse forms, including imperfect spheres, perfect spheres, perfect and homogenous spheres and tubes. Based on the results on FTIR, GPC, AFM and XRD experiments, we suggest that the shape of the nanoparticles may be decided by the crimp degree (i.e., the degree of polyurethane chains intertangling in the water environment) and order degree, which are determined by the molecular weight (Mn) and hydrogen bonds. Meanwhile, solid water and high-temperature water can both reduce hard segments that gather on the polyurethane film surface to reduce hydrophilic groups and produce a soft surface. Our findings show that water may play key roles in aqueous polymer formation and bring order to molecular chains. PMID:27687001

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand.

PubMed

Seipp, Charles A; Williams, Neil J; Custelcean, Radu

2016-09-08

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, 1,4-benzene-bis(iminoguanidinium) (BBIG), is demonstrated. The ligand is synthesized as the chloride salt (BBIG-Cl) by in situ imine condensation of terephthalaldehyde with aminoguanidinium chloride in water, followed by crystallization as the sulfate salt (BBIG-SO4). Alternatively, BBIG-Cl is synthesized ex situ in larger scale from ethanol. The sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. The ligand can be recycled by neutralization of BBIG-SO4 with aqueous NaOH and crystallization of the neutral bis-iminoguanidine, which can be converted back into BBIG-Cl with aqueous HCl and reused in another separation cycle. Finally, (35)S-labeled sulfate and β liquid scintillation counting are employed for monitoring the sulfate concentration in solution. Overall, this protocol will instruct the user in the necessary skills to synthesize a ligand, employ it in the selective crystallization of sulfate from aqueous solutions, and quantify the separation efficiency.

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand

DOE PAGES

Seipp, Charles A.; Williams, Neil J.; Custelcean, Radu

2016-01-01

One simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, 1,4-benzene-bis(iminoguanidinium) (BBIG), is demonstrated. The ligand is synthesized as the chloride salt (BBIG-Cl) by in situ imine condensation of terephthalaldehyde with aminoguanidinium chloride in water, followed by crystallization as the sulfate salt (BBIG-SO4). Alternatively, BBIG-Cl is synthesized ex situ in larger scale from ethanol. Furthermore, the sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. These ligands can then be recycled by neutralization of BBIG-SO4 with aqueous NaOH and crystallization of the neutralmore » bis-iminoguanidine, which can be converted back into BBIG-Cl with aqueous HCl and reused in another separation cycle. Finally, 35S-labeled sulfate and β liquid scintillation counting are employed for monitoring the sulfate concentration in solution. Overall, this protocol will instruct the user in the necessary skills to synthesize a ligand, employ it in the selective crystallization of sulfate from aqueous solutions, and quantify the separation efficiency.« less

Efficient removal of caesium ions from aqueous solution using a calix crown ether in ionic liquids: mechanism and radiation effect.

PubMed

Xu, Chao; Yuan, Liyong; Shen, Xinghai; Zhai, Maolin

2010-04-28

The removal of radioactive (137)Cs from nuclear waste is of great importance for both the environment and energy saving. Herein, we report a study on the removal of Cs(+) using a calix crown ether bis(2-propyloxy)calix[4]crown-6 (BPC6) in ionic liquids [C(n)mim][NTf(2)], where [C(n)mim](+) is 1-alkyl-3-methylimidazolium and [NTf(2)](-) is bis(trifluoromethylsulfonyl)imide. The BPC6/[C(n)mim][NTf(2)] system is highly efficient in removing Cs(+) from aqueous solution, even at a low concentration of BPC6. HNO(3) and metal ions such as Na(+), Al(3+) in the aqueous phase interfered with the extraction of Cs(+) by competitive interaction with BPC6 and/or salting-out effect. UV analysis confirmed that the extraction of Cs(+) by the BPC6/[C(n)mim][NTf(2)] system involves a dual extraction mechanism, i.e., via exchange of BPC6.Cs(+) complex or Cs(+) by [C(n)mim](+). Irradiation of [C(4)mim][NTf(2)] dramatically decreases Cs(+) partitioning in the ionic liquid phase by the competitive interaction of radiation-generated H(+) with BPC6, while irradiation of BPC6/[C(4)mim][NTf(2)] decreases Cs(+) partitioning more markedly due to the radiolysis of BPC6.

Lateral movements in Rayleigh-Taylor instabilities due to frontiers. Experimental study

NASA Astrophysics Data System (ADS)

Binda, L.; Fernández, D.; El Hasi, C.; Zalts, A.; D'Onofrio, A.

2018-01-01

Lateral movements of the fingers in Rayleigh-Taylor hydrodynamic instabilities at the interface between two fluids are studied. We show that transverse movements appear when a physical boundary is present; these phenomena have not been explained until now. The boundary prevents one of the fluids from crossing it. Such frontiers can be buoyancy driven as, for example, the frontier to the passage of a less dense solution through a denser solution or when different aggregation states coexist (liquid and gaseous phases). An experimental study of the lateral movement velocity of the fingers was performed for different Rayleigh numbers (Ra), and when oscillations were detected, their amplitudes were studied. Liquid-liquid (L-L) and gas-liquid (G-L) systems were analysed. Aqueous HCl and Bromocresol Green (sodium salt, NaBCG) solutions were used in L-L experiments, and CO2 (gas) and aqueous NaOH, NaHCO3, and CaCl2 solutions were employed for the G-L studies. We observed that the lateral movement of the fingers and finger collapses near the interface are more notorious when Ra increases. The consequences of this, for each experience, are a decrease in the number of fingers and an increase in the velocity of the lateral finger movement close to the interface as time evolves. We found that the amplitude of the oscillations did not vary significantly within the considered Ra range. These results have an important implication when determining the wave number of instabilities in an evolving system. The wave number could be strongly diminished if there is a boundary.

Impact of sodium chloride on the expansion of a liquid-liquid miscibility gap in an API/water system. Case study of Brivaracetam.

PubMed

Couvrat, Nicolas; Mahieux, Julien; Fours, Baptiste; Cartigny, Yohann; Schenkel, Eric; Aerts, Luc; Quéré, Luc; Coquerel, Gérard

2016-12-30

Brivaracetam, or (2S)-2-[(4R)-2-oxo-4-propyl-pyrrolidin-1-yl] butanamide, is an active pharmaceutical ingredient designed for the treatment of epilepsy. During the development of the IV administration mode, a liquid-liquid miscibility gap has been observed with pure water, isotonic and hypertonic solutions (vehicle at 0.9% w/w and 5%w/w NaCl respectively). The study reveals that the NaCl concentration has a direct impact on the extent of the demixing domain; from a sub-micronic demixing in pure water towards a macroscopic miscibility gap in hypertonic aqueous solutions. The thorough exploration of these heterogeneous equilibria led to define experimental parameters for safe IV injections without risk of liquid - liquid miscibility gap at 37°C. Copyright © 2016 Elsevier B.V. All rights reserved.

Design of functional guanidinium ionic liquid aqueous two-phase systems for the efficient purification of protein.

PubMed

Ding, Xueqin; Wang, Yuzhi; Zeng, Qun; Chen, Jing; Huang, Yanhua; Xu, Kaijia

2014-03-07

A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been devised and synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids (ILs) were confirmed by (1)H nuclear magnetic resonance ((1)H NMR) and 13C nuclear magnetic resonance (13C NMR) and the production yields were all above 90%. Functional guanidinium ionic liquid aqueous two-phase systems (FGIL-ATPSs) have been first designed with these functional guanidinium ILs and phosphate solution for the purification of protein. After phase separation, proteins had transferred into the IL-rich phase and the concentrations of proteins were determined by measuring the absorbance at 278 nm using an ultra violet visible (UV-vis) spectrophotometer. The advantages of FGIL-ATPSs were compared with ordinary ionic liquid aqueous two-phase systems (IL-ATPSs). The proposed FGIL-ATPS has been applied to purify lysozyme, trypsin, ovalbumin and bovine serum albumin. Single factor experiments were used to research the effects of the process, such as the amount of ionic liquid (IL), the concentration of salt solution, temperature and the amount of protein. The purification efficiency reaches to 97.05%. The secondary structure of protein during the experimental process was observed upon investigation using UV-vis spectrophotometer, Fourier-transform infrared spectroscopy (FT-IR) and circular dichroism spectrum (CD spectrum). The precision, stability and repeatability of the process were investigated. The mechanisms of purification were researched by dynamic light scattering (DLS), determination of the conductivity and transmission electron microscopy (TEM). It was suggested that aggregation and embrace phenomenon play a significant role in the purification of proteins. All the results show that FGIL-ATPSs have huge potential to offer new possibility in the purification of proteins. Copyright © 2014 Elsevier B.V. All rights reserved.

Extraction and Chromatographic Determination of Shikimic Acid in Chinese Conifer Needles with 1-Benzyl-3-methylimidazolium Bromide Ionic Liquid Aqueous Solutions

PubMed Central

Chen, Fengli; Hou, Kexin; Li, Shuangyang; Zu, Yuangang; Yang, Lei

2014-01-01

An ionic liquids-based ultrasound-assisted extraction (ILUAE) method was successfully developed for extracting shikimic acid from conifer needles. Eleven 1-alkyl-3-methylimidazolium ionic liquids with different cations and anions were investigated and 1-benzyl-3-methylimidazolium bromide solution was selected as the solvent. The conditions for ILUAE, including the ionic liquid concentration, ultrasound power, ultrasound time, and liquid-solid ratio, were optimized. The proposed method had good recovery (99.37%–100.11%) and reproducibility (RSD, n = 6; 3.6%). ILUAE was an efficient, rapid, and simple sample preparation technique that showed high reproducibility. Based on the results, a number of plant species, namely, Picea koraiensis, Picea meyeri, Pinus elliottii, and Pinus banksiana, were identified as among the best resources of shikimic acid. PMID:24782942

Non-uniform binding of single-stranded DNA binding proteins to hybrids of single-stranded DNA and single-walled carbon nanotubes observed by atomic force microscopy in air and in liquid

NASA Astrophysics Data System (ADS)

Umemura, Kazuo; Ishizaka, Kei; Nii, Daisuke; Izumi, Katsuki

2016-12-01

Using atomic force spectroscopy (AFM), we observed hybrids of single-stranded DNA (ssDNA) and single-walled carbon nanotubes (SWNTs) with or without protein molecules in air and in an aqueous solution. This is the first report of ssDNA-SWNT hybrids with proteins in solution analyzed by AFM. In the absence of protein, the height of the ssDNA-SWNT hybrids was 1.1 ± 0.3 nm and 2.4 ± 0.6 nm in air and liquid, respectively, suggesting that the ssDNA molecules adopted a flexible structure on the SWNT surface. In the presence of single-stranded DNA binding (SSB) proteins, the heights of the hybrids in air and liquid increased to 6.4 ± 3.1 nm and 10.0 ± 4.5 nm, respectively. The AFM images clearly showed binding of the SSB proteins to the ssDNA-SWNT hybrids. The morphology of the SSB-ssDNA-SWNT hybrids was non-uniform, particularly in aqueous solution. The variance of hybrid height was quantitatively estimated by cross-section analysis along the long-axis of each hybrid. The SSB-ssDNA-SWNT hybrids showed much larger variance than the ssDNA-SWNT hybrids.

On the Relationship of the Fractal Dimension of Structure with the State of Drying Drops of Crystallizing Solutions (Thermodynamic and Experimental Modeling)

NASA Astrophysics Data System (ADS)

Golovanova, O. A.; Chikanova, E. S.; Fedoseev, V. B.

2018-05-01

The processes occurring in aqueous salt solutions have been investigated based on thermodynamic and experimental modeling. The self-organization in a drying drop of dehydrated liquids is analyzed using the fractal theory, due to which the quantitative characteristics of the crystallization processes in a small volume are obtained.

Application of laser-induced breakdown spectroscopy to zirconium in aqueous solution

NASA Astrophysics Data System (ADS)

Ruas, Alexandre; Matsumoto, Ayumu; Ohba, Hironori; Akaoka, Katsuaki; Wakaida, Ikuo

2017-05-01

In the context of the Fukushima Dai-ichi Nuclear Power Plant (F1-NPP) decommissioning process, laser-induced breakdown spectroscopy (LIBS) has many advantages. The purpose of the present work is to demonstrate the on-line monitoring capability of the LIBS coupled with the ultra-thin liquid jet sampling method. The study focuses on zirconium in aqueous solution, considering that it is a major element in the F1-NPP fuel debris that has been subject to only a few LIBS studies in the past. The methodology of data acquisition and processing are described. In particular, two regions of interest with many high intensity zirconium lines have been observed around 350 nm in the case of the ionic lines and 478 nm in the case of atomic lines. The best analytical conditions for zirconium are different depending on the analysis of ionic lines or atomic lines. A low LOD of about 4 mg L- 1 could be obtained, showing that LIBS coupled with the ultra-thin liquid jet sampling technique is a promising alternative for more complex solutions found in the F1-NPP, namely mixtures containing zirconium.

Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids.

PubMed

Byers, Joshua C; Paulose Nadappuram, Binoy; Perry, David; McKelvey, Kim; Colburn, Alex W; Unwin, Patrick R

2015-10-20

Single molecule electrochemical detection (SMED) is an extremely challenging aspect of electroanalytical chemistry, requiring unconventional electrochemical cells and measurements. Here, SMED is reported using a "quad-probe" (four-channel probe) pipet cell, fabricated by depositing carbon pyrolytically into two diagonally opposite barrels of a laser-pulled quartz quadruple-barreled pipet and filling the open channels with electrolyte solution, and quasi-reference counter electrodes. A meniscus forms at the end of the probe covering the two working electrodes and is brought into contact with a substrate working electrode surface. In this way, a nanogap cell is produced whereby the two carbon electrodes in the pipet can be used to promote redox cycling of an individual molecule with the substrate. Anticorrelated currents generated at the substrate and tip electrodes, at particular distances (typically tens of nanometers), are consistent with the detection of single molecules. The low background noise realized in this droplet format opens up new opportunities in single molecule electrochemistry, including the use of ionic liquids, as well as aqueous solution, and the quantitative assessment and analysis of factors influencing redox cycling currents, due to a precisely known gap size.

Characteristics of gas-liquid diaphragm discharge and its application on decolorization of brilliant red B in aqueous solution

NASA Astrophysics Data System (ADS)

Qingsong, GAO; Yongjun, LIU; Bing, SUN

2017-11-01

A simple gas-liquid diaphragm discharge reactor was designed and characteristics of the discharge and its application on decolorization of brilliant red B in an aqueous solution were investigated. The results showed that strong oxidizing agents such as ·OH and ·O radicals were generated. Average electron temperature of the discharge was 0.72 eV, 1.15 eV and 0.83 eV with air, oxygen and argon as the discharge gas, respectively. Solution pH and conductivity changed little when oxygen or argon was used as the discharge gas; however, these two parameters changed significantly when the discharge was performed in air. During the discharge treatment, the characteristic absorption peaks of brilliant red B gradually decreased where the decolorization followed the first-order kinetics. With 10 min of discharge, the decolorization of brilliant red B (30 mg L-1) can reach 96%, 81% and 62% in the cases of oxygen, argon and air, respectively. The analysis of by-products showed that the brilliant red B molecule can be effectively destroyed in this discharge mode.

Momentum, heat, and neutral mass transport in convective atmospheric pressure plasma-liquid systems and implications for aqueous targets

NASA Astrophysics Data System (ADS)

Lindsay, Alexander; Anderson, Carly; Slikboer, Elmar; Shannon, Steven; Graves, David

2015-10-01

There is a growing interest in the study of plasma-liquid interactions with application to biomedicine, chemical disinfection, agriculture, and other fields. This work models the momentum, heat, and neutral species mass transfer between gas and aqueous phases in the context of a streamer discharge; the qualitative conclusions are generally applicable to plasma-liquid systems. The problem domain is discretized using the finite element method. The most interesting and relevant model result for application purposes is the steep gradients in reactive species at the interface. At the center of where the reactive gas stream impinges on the water surface, the aqueous concentrations of OH and ONOOH decrease by roughly 9 and 4 orders of magnitude respectively within 50 μ m of the interface. Recognizing the limited penetration of reactive plasma species into the aqueous phase is critical to discussions about the therapeutic mechanisms for direct plasma treatment of biological solutions. Other interesting results from this study include the presence of a 10 K temperature drop in the gas boundary layer adjacent to the interface that arises from convective cooling. Though the temperature magnitudes may vary among atmospheric discharge types (different amounts of plasma-gas heating), this relative difference between gas and liquid bulk temperatures is expected to be present for any system in which convection is significant. Accounting for the resulting difference between gas and liquid bulk temperatures has a significant impact on reaction kinetics; factor of two changes in terminal aqueous species concentrations like H2O2, NO2- , and NO3- are observed in this study if the effect of evaporative cooling is not included.

Spectral Induced Polarization Response of Unconsolidated Saturated Sand and Surfactant Solutions

EPA Science Inventory

Dense non-aqueous phase liquids (DNAPL), such as chlorinated solvents, are common groundwater contaminants. Traditional pump-and-treat methods are often not effective at removing residual DNAPL from the subsurface. Surfactant-enhanced aquifer remediation is a promising remediatio...

Modelling of ceramide interactions with porous graphite carbon in non-aqueous liquid chromatography.

PubMed

West, C; Cilpa, G; Gaudin, K; Chaminade, P; Lesellier, E

2005-09-16

Interactions of solutes on porous graphitic carbon (PGC) with non-aqueous mobile phases are studied by the linear solvation energy relationship (LSER). Studies have been carried out with eight binary mixtures composed of a weak solvent (acetonitrile or methanol) and a strong solvent (tetrahydrofuran, n-butanol, CH2Cl2, 1,1,2-trichloro-2,2,1-trifluoroethane). The systematic analysis of a set of test compounds was performed for each solvent mixture in isocratic mode (50:50). The results were compared to those obtained on PGC with hydro-organic liquids and supercritical fluids. They were then correlated with the observed retention behaviour of lipid compounds, more particularly ceramides.

Single-reactor process for producing liquid-phase organic compounds from biomass

DOEpatents

Dumesic, James A.; Simonetti, Dante A.; Kunkes, Edward L.

2015-12-08

Disclosed is a method for preparing liquid fuel and chemical intermediates from biomass-derived oxygenated hydrocarbons. The method includes the steps of reacting in a single reactor an aqueous solution of a biomass-derived, water-soluble oxygenated hydrocarbon reactant, in the presence of a catalyst comprising a metal selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Mo, Tc, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt, and Au, at a temperature, and a pressure, and for a time sufficient to yield a self-separating, three-phase product stream comprising a vapor phase, an organic phase containing linear and/or cyclic mono-oxygenated hydrocarbons, and an aqueous phase.

Single-reactor process for producing liquid-phase organic compounds from biomass

DOEpatents

Dumesic, James A [Verona, WI; Simonetti, Dante A [Middleton, WI; Kunkes, Edward L [Madison, WI

2011-12-13

Disclosed is a method for preparing liquid fuel and chemical intermediates from biomass-derived oxygenated hydrocarbons. The method includes the steps of reacting in a single reactor an aqueous solution of a biomass-derived, water-soluble oxygenated hydrocarbon reactant, in the presence of a catalyst comprising a metal selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Mo, Tc, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt, and Au, at a temperature, and a pressure, and for a time sufficient to yield a self-separating, three-phase product stream comprising a vapor phase, an organic phase containing linear and/or cyclic mono-oxygenated hydrocarbons, and an aqueous phase.

Drowning-out crystallisation of sodium sulphate using aqueous two-phase systems.

PubMed

Taboada, M E; Graber, T A; Asenjo, J A; Andrews, B A

2000-06-23

A novel method to obtain crystals of pure, anhydrous salt, using aqueous two-phase systems was studied. A concentrated salt solution is mixed with polyethylene glycol (PEG), upon which three phases are formed: salt crystals, a PEG-rich liquid and a salt-rich liquid. After removal of the solid salt, a two-phase system is obtained. Both liquid phases are recycled, allowing the design of a continuous process, which could be exploited industrially. The phase diagram of the system water-Na2SO4-PEG 3350 at 28 degrees C was used. Several process alternatives are proposed and their economic potential is discussed. The process steps needed to produce sodium sulphate crystals include mixing, crystallisation, settling and, optionally, evaporation of water. The yield of sodium sulphate increases dramatically if an evaporation step is used.

Application of molecular dynamics simulations in molecular property prediction II: diffusion coefficient.

PubMed

Wang, Junmei; Hou, Tingjun

2011-12-01

In this work, we have evaluated how well the general assisted model building with energy refinement (AMBER) force field performs in studying the dynamic properties of liquids. Diffusion coefficients (D) have been predicted for 17 solvents, five organic compounds in aqueous solutions, four proteins in aqueous solutions, and nine organic compounds in nonaqueous solutions. An efficient sampling strategy has been proposed and tested in the calculation of the diffusion coefficients of solutes in solutions. There are two major findings of this study. First of all, the diffusion coefficients of organic solutes in aqueous solution can be well predicted: the average unsigned errors and the root mean square errors are 0.137 and 0.171 × 10(-5) cm(-2) s(-1), respectively. Second, although the absolute values of D cannot be predicted, good correlations have been achieved for eight organic solvents with experimental data (R(2) = 0.784), four proteins in aqueous solutions (R(2) = 0.996), and nine organic compounds in nonaqueous solutions (R(2) = 0.834). The temperature dependent behaviors of three solvents, namely, TIP3P water, dimethyl sulfoxide, and cyclohexane have been studied. The major molecular dynamics (MD) settings, such as the sizes of simulation boxes and with/without wrapping the coordinates of MD snapshots into the primary simulation boxes have been explored. We have concluded that our sampling strategy that averaging the mean square displacement collected in multiple short-MD simulations is efficient in predicting diffusion coefficients of solutes at infinite dilution. Copyright © 2011 Wiley Periodicals, Inc.

High-performance liquid chromatographic analysis of methadone hydrochloride oral solution.

PubMed

Beasley, T H; Ziegler, H W

1977-12-01

A direct and rapid high-performance liquid chromatographic assay for methadone hydrochloride in a flavored oral solution dosage form is described. A syrup sample, one part diluted with three parts of water, is introduced onto a column packed with octadecylsilane bonded on 10 micrometer porous silica gel (reversed phase). A formic acid-ammonium formate-buffered mobile phase is linear programmed with acetonitrile. The absorbance is monitored continuously at 280 or 254 nm, using a flow-through, UV, double-beam photometer. An aqueous methadone hydrochloride solution is used for external standardization. The relative standard deviation was not more than 1.0%. Drug recovery from a syrup base was better than 99.8%.

Rapid structural analysis of nanomaterials in aqueous solutions

NASA Astrophysics Data System (ADS)

Ryuzaki, Sou; Tsutsui, Makusu; He, Yuhui; Yokota, Kazumichi; Arima, Akihide; Morikawa, Takanori; Taniguchi, Masateru; Kawai, Tomoji

2017-04-01

Rapid structural analysis of nanoscale matter in a liquid environment represents innovative technologies that reveal the identities and functions of biologically important molecules. However, there is currently no method with high spatio-temporal resolution that can scan individual particles in solutions to gain structural information. Here we report the development of a nanopore platform realizing quantitative structural analysis for suspended nanomaterials in solutions with a high z-axis and xy-plane spatial resolution of 35.8 ± 1.1 and 12 nm, respectively. We used a low thickness-to-diameter aspect ratio pore architecture for achieving cross sectional areas of analyte (i.e. tomograms). Combining this with multiphysics simulation methods to translate ionic current data into tomograms, we demonstrated rapid structural analysis of single polystyrene (Pst) beads and single dumbbell-like Pst beads in aqueous solutions.

Facile functionalized of SBA-15 via a biomimetic coating and its application in efficient removal of uranium ions from aqueous solution.

PubMed

Gao, Jun-Kai; Hou, Li-An; Zhang, Guang-Hui; Gu, Ping

2015-04-09

A novel dopamine-functionalized mesoporous silica (DMS), synthesized by grafting dopamine onto a mesoporous molecular sieve (SBA-15), was developed as a sorbent to extract U(VI) from aqueous solution. The method used to modify SBA-15 was simple, facile and cost-effective. The DMS was characterized by SEM, TEM, XRD and BET, showing that the material had an ordered mesoporous structure and a large surface area. The effect of contact time, pH, ionic strength, temperature, and solid-liquid ratio on the sorption process was investigated. It was demonstrated that the adsorption of U(VI) by DMS was fast and that it can be described by the pseudo-second order-equation where the equilibrium time was 20 min. Additionally, the adsorption isotherm data were fitted well by the Langmuir model with the maximum adsorption capacity of DMS of 196 mg/g at pH 6.0. Furthermore, the influence of the K(+) and Na(+) concentrations and solid-to-liquid ratio on the sorption was very weak, and the values of the thermodynamic parameters revealed that the sorption process was exothermic and spontaneous. All the results suggested that the DMS could be used as an excellent adsorbent to remove U(VI) from aqueous solution. Copyright © 2014 Elsevier B.V. All rights reserved.

Studying localized corrosion using liquid cell transmission electron microscopy

DOE PAGES

Chee, See Wee; Pratt, Sarah H.; Hattar, Khalid; ...

2014-11-07

Using liquid cell transmission electron microscopy (LCTEM), localized corrosion of Cu and Al thin films immersed in aqueous NaCl solutions was studied. We demonstrate that potentiostatic control can be used to initiate pitting and that local compositional changes, due to focused ion beam implantation of Au + ions, can modify the corrosion susceptibility of Al films. Likewise, a discussion on strategies to control the onset of pitting is also presented.

AFM Structural Characterization of Drinking Water Biofilm ...

EPA Pesticide Factsheets

Due to the complexity of mixed culture drinking water biofilm, direct visual observation under in situ conditions has been challenging. In this study, atomic force microscopy (AFM) revealed the three dimensional morphology and arrangement of drinking water relevant biofilm in air and aqueous solution. Operating parameters were optimized to improve imaging of structural details for a mature biofilm in liquid. By using a soft cantilever (0.03 N/m) and slow scan rate (0.5 Hz), biofilm and individual bacterial cell’s structural topography were resolved and continuously imaged in liquid without loss of spatial resolution or sample damage. The developed methodology will allow future in situ investigations to temporally monitor mixed culture drinking water biofilm structural changes during disinfection treatments. Due to the complexity of mixed culture drinking water biofilm, direct visual observation under in situ conditions has been challenging. In this study, atomic force microscopy (AFM) revealed the three dimensional morphology and arrangement of drinking water relevant biofilm in air and aqueous solution. Operating parameters were optimized to improve imaging of structural details for a mature biofilm in liquid. By using a soft cantilever (0.03 N/m) and slow scan rate (0.5 Hz), biofilm and individual bacterial cell’s structural topography were resolved and continuously imaged in liquid without loss of spatial resolution or sample damage. The developed methodo

Effect of Concentration on the Interfacial and Bulk Structure of Ionic Liquids in Aqueous Solution.

PubMed

Cheng, H-W; Weiss, H; Stock, P; Chen, Y-J; Reinecke, C R; Dienemann, J-N; Mezger, M; Valtiner, M

2018-02-27

Bio and aqueous applications of ionic liquids (IL) such as catalysis in micelles formed in aqueous IL solutions or extraction of chemicals from biologic materials rely on surface-active and self-assembly properties of ILs. Here, we discuss qualitative relations of the interfacial and bulk structuring of a water-soluble surface-active IL ([C 8 MIm][Cl]) on chemically controlled surfaces over a wide range of water concentrations using both force probe and X-ray scattering experiments. Our data indicate that IL structuring evolves from surfactant-like surface adsorption at low IL concentrations, to micellar bulk structure adsorption above the critical micelle concentration, to planar bilayer formation in ILs with <1 wt % of water and at high charging of the surface. Interfacial structuring is controlled by mesoscopic bulk structuring at high water concentrations. Surface chemistry and surface charges decisively steer interfacial ordering of ions if the water concentration is low and/or the surface charge is high. We also demonstrate that controlling the interfacial forces by using self-assembled monolayer chemistry allows tuning of interfacial structures. Both the ratio of the head group size to the hydrophobic tail volume as well as the surface charging trigger the bulk structure and offer a tool for predicting interfacial structures. Based on the applied techniques and analyses, a qualitative prediction of molecular layering of ILs in aqueous systems is possible.

DEMONSTRATION OF BULLETIN: DISC TUBE™ MODULE TECHNOLOGY ROCHEM SEPARATION SYSTEMS, INC.

EPA Science Inventory

The Rochem Disc Tube™ Module System uses membrane separation to treat aqueous solutions ranging from seawater to leachate contaminated with organic solvents. The system uses reverse osmosis through a semipermeable membrane to separate purified water from contaminated liquids. Osm...

Use of Pseudophase TLC in Teaching Laboratories.

ERIC Educational Resources Information Center

Armstrong, Daniel W.; And Others

1984-01-01

Suggests that pseudophase liquid chromatography, which uses aqueous surfactant solutions instead of organic solvents for the mobile phase, can be substituted for thin-layer chromatography in the introductory organic course. Outlines the method as it applies to common separations in the laboratory. (JN)

Physical and chemical interactions at the interface between atmospheric pressure plasmas and aqueous solutions

NASA Astrophysics Data System (ADS)

Lindsay, Alexander; Byrns, Brandon; Knappe, Detlef; Graves, David; Shannon, Steven

2014-10-01

Transport and reactions of charged species, neutrals, and photons at the interface between plasmas and liquids must be better quantified. The work presented here combines theoretical and experimental investigations of conditions in the gas and liquid phases in proximity to the interface for various discharges. OES is used to determine rotational and vibrational temperatures of OH, NO, and N2+; the relationship between these temperatures that characterize the distribution of internal energy states and gas and electron kinetic temperatures is considered. The deviation of OH rotational states from equilibrium under high humidity conditions is also presented. In contradiction with findings of other groups, high energy rotational states appear to become underpopulated with increasing humidity. In the aqueous phase, concentrations of longer-lived species such as nitrate, nitrite, hydrogen peroxide, and ozone are determined using ion chromatography and colorimetric methods. Spin-traps and electron paramagnetic resonance (EPR) are investigated for characterization of short-lived aqueous radicals like OH, O2-, NO, and ONOO-. Finally, experimental results are compared to a numerical model which couples transport and reactions within and between the bulk gas and liquid phases.

Measurement of interactions between solid particles, liquid droplets, and/or gas bubbles in a liquid using an integrated thin film drainage apparatus.

PubMed

Wang, Louxiang; Sharp, David; Masliyah, Jacob; Xu, Zhenghe

2013-03-19

A novel device was designed to measure drainage dynamics of thin liquid films confined between a solid particle, an immiscible liquid droplet, and/or gas bubble. Equipped with a bimorph force sensor, a computer-interfaced video capture, and a data acquisition system, the newly designed integrated thin film drainage apparatus (ITFDA) allows for the direct and simultaneous measurements of force barrier, true film drainage time, and bubble/droplet deformation under a well-controlled external force, receding and advancing contact angles, capillary force, and adhesion (detachment) force between an air bubble or oil droplet and a solid, a liquid, or an air bubble in an immiscible liquid. Using the diaphragm of a high-frequency speaker as the drive mechanism for the air bubble or oil droplet attached to a capillary tube, this newly designed device is capable of measuring forces over a wide range of hydrodynamic conditions, including bubble approach and retract velocities up to 50 mm/s and displacement range up to 1 mm. The results showed that the ITFDA was capable of measuring hydrodynamic resistance, film drainage time, and other important physical parameters between air bubbles and solid particles in aqueous solutions. As an example of illustrating the versatility, the ITFDA was also applied to other important systems such as interactions between air bubble and oil droplet, two air bubbles, and two oil droplets in an aqueous solution.

Determination of atranol and chloroatranol in perfumes using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

PubMed

López-Nogueroles, Marina; Chisvert, Alberto; Salvador, Amparo

2014-05-15

A new analytical method based on simultaneous derivatization and dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS), for the determination of the allergenic compounds atranol and chloroatranol in perfumes, is presented. Derivatization of the target analytes by means of acetylation with anhydride acetic in carbonate buffer was carried out. Thereby volatility and detectability were increased for improved GC-MS sensitivity. In addition, extractability by DLLME was also enhanced due to a less polar character of the solutes. A liquid-liquid extraction was performed before DLLME to clean up the sample and to obtain an aqueous sample solution, free of the low polar matrix from the essential oils, as donor phase. Different parameters, such as the nature and volume of both the extraction and disperser solvents, the ionic strength of the aqueous donor phase or the effect of the derivatization reagent volume, were optimized. Under the selected conditions (injection of a mixture of 750μL of acetone as disperser solvent, 100μL of chloroform as extraction solvent and 100μL of anhydride acetic as derivatization reagent) the figures of merit of the proposed method were evaluated. Limits of detection in the low ngmL(-1) range were obtained. Matrix effect was observed in real perfume samples and thus, standard addition calibration is recommended. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaporation of a sessile water drop and a drop of aqueous salt solution.

PubMed

Misyura, S Y

2017-11-07

The influence of various factors on the evaporation of drops of water and aqueous salt solution has been experimentally studied. Typically, in the studies of drop evaporation, only the diffusive vapor transfer, radiation and the molecular heat conduction are taken into account. However, vapor-gas convection plays an important role at droplet evaporation. In the absence of droplet boiling, the influence of gas convection turns out to be the prevailing factor. At nucleate boiling, a prevailing role is played by bubbles generation and vapor jet discharge at a bubble collapse. The gas convection behavior for water and aqueous salt solution is substantially different. With a growth of salt concentration over time, the influence of the convective component first increases, reaches an extremum and then significantly decreases. At nucleate boiling in a salt solution it is incorrect to simulate the droplet evaporation and the heat transfer in quasi-stationary approximation. The evaporation at nucleate boiling in a liquid drop is divided into several characteristic time intervals. Each of these intervals is characterized by a noticeable change in both the evaporation rate and the convection role.

Gold nanoparticles prepared by electro-exploding wire technique in aqueous solutions

NASA Astrophysics Data System (ADS)

Kumar, Lalit; Kapoor, Akanksha; Meghwal, Mayank; Annapoorni, S.

2016-05-01

This article presents an effective approach for the synthesis of Au nanoparticles via an environmentally benevolent electro-exploding wire (EEW) technique. In this process, Au nanoparticles evolve through the plasma generated from the parent Au metal. Compared to other typical chemical methods, electro-exploding wire technique is a simple and economical technique which normally operates in water or organic liquids under ambient conditions. Efficient size control was achieved using different aqueous medium like (1mM) NaCl, deionized water and aqueous solution of sodium hydroxide (NaOH, pH 9.5) using identical electro-exploding conditions. The gold nanoparticles exhibited the UV-vis absorption spectrum with a maximum absorption band at 530 nm, similar to that of gold nanoparticles chemically prepared in a solution. The mechanism of size variation of Au nanoparticles is also proposed. The results obtained help to develop methodologies for the control of EEW based nanoparticle growth and the functionalization of nanoparticle surfaces by specific interactions.

Glass-liquid phase separation in highly supersaturated aqueous solutions of telaprevir.

PubMed

Mosquera-Giraldo, Laura I; Taylor, Lynne S

2015-02-02

Amorphous solid dispersions are of great current interest because they can improve the delivery of poorly water-soluble compounds. It has been recently noted that the highly supersaturated solutions generated by dissolution of some ASDs can undergo a phase transition to a colloidal, disordered, drug-rich phase when the concentration exceeds the "amorphous solubility" of the drug. The purpose of this study was to investigate the phase behavior of supersaturated solutions of telaprevir, which is formulated as an amorphous solid dispersion in the commercial product. Different analytical techniques including proton nuclear magnetic resonance spectroscopy (NMR), ultraviolet spectroscopy (UV), fluorescence spectroscopy and flux measurements were used to evaluate the properties of aqueous supersaturated solutions of telaprevir. It was found that highly supersaturated solutions of telaprevir underwent glass-liquid phase separation (GLPS) when the concentration exceeded 90 μg/mL, forming a water-saturated colloidal, amorphous drug-rich phase with a glass transition temperature of 52 °C. From flux measurements, it was observed that the "free" drug concentration reached a maximum at the concentration where GLPS occurred, and did not increase further as the concentration was increased. This phase behavior, which results in a precipitate and a metastable equilibrium between a supersaturated solution and a drug-rich phase, is obviously important in the context of evaluating amorphous solid dispersion formulations and their crystallization routes.

Investigation of factors affecting the synthesis of nano-cadmium sulfide by pulsed laser ablation in liquid environment

NASA Astrophysics Data System (ADS)

Darwish, Ayman M.; Eisa, Wael H.; Shabaka, Ali A.; Talaat, Mohamed H.

2016-01-01

Pulsed laser ablation in a liquid medium is a promising technique as compared to the other synthetic methods to synthesize different materials in nanoscale form. The laser parameters (e.g., wavelength, pulse width, fluence, and repetition frequency) and liquid medium (e.g., aqueous/nonaqueous liquid or solution with surfactant) were tightly controlled during and after the ablation process. By optimizing these parameters, the particle size and distribution of materials can be adjusted. The UV-vis absorption spectra and weight changes of targets were used for the characterization and comparison of products.

Dielectric spectroscopy in aqueous solutions of paracetamol over the frequency range of 20 Hz to 2 MHz at 293.15 K temperature

NASA Astrophysics Data System (ADS)

Pandit, T. R.; Rana, V. A.

2018-05-01

Frequency domain dielectric relaxation spectroscopy plays an important role in the study of pharmaceutical drug molecules. The complex relative dielectric permittivity ɛ*(ω) = ɛ' - j ɛ" of aqueous solutions of paracetamol in the frequency range of 20 Hz to 2 MHz at a temperature range of 293.15 K are measured with the help of Agilent precision LCR meter E4980A along with four terminal liquid test fixture Agilent 16452A. Data of complex relative permittivity are used to calculate loss tangent for all concentrations of paracetamol in distilled water. Electrode polarization relaxation time has been calculated for all solutions. Effect of variation of concentrations of paracetamol in distilled water on these dielectric parameters is discussed.

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.

Thermodynamic model for polyelectrolyte hydrogels.

PubMed

Arndt, Markus C; Sadowski, Gabriele

2014-09-04

The composition and swelling behavior of hydrogels may be dramatically influenced by external stimuli. Polyelectrolyte hydrogels consisting of charged polymers are particularly well-known for a high sensitivity to the presence of ionic species. For a thermodynamic description of such systems, the polyelectrolyte Perturbed-Chain Statistical Association Fluid Theory (pePC-SAFT) equation of state was augmented and merged with an extension of the modeling of hydrogels. This combined approach allowed for two effects to be taken into account: first, charges along the polymer chain and their interaction with mobile ions of the same or opposite charge in aqueous solutions and, second, the elastic interactions of swellable networks and their effect on Helmholtz energy and pressure. Thus, predictions of the degree of counterion condensation on the polymer chains could be made both for vapor-liquid equilibria of aqueous polyelectrolyte solutions and for polyelectrolyte hydrogels in aqueous salt solutions. The influence of temperature and molecular weight thereon was predicted successfully, and the impact of the degree of neutralization and the effect of additional salts were examined in comparison to literature data. With the inclusion of the influence of the Donnan potential, our model gave good predictions of swellable polyelectrolyte hydrogel systems in salt solutions. Poly(acrylic acid) and poly(methacrylic acid) gels were studied along with their corresponding sodium salts. Their swelling behavior in aqueous NaCl and NaNO3 solutions was examined.

Efficient removal of tetracycline with KOH-activated graphene from aqueous solution

PubMed Central

Sun, Yiran; Yu, Fei

2017-01-01

Activated graphene absorbents with high specific surface area (SSA) were prepared by an easy KOH-activated method, and were applied in absorbing antibiotics, such as tetracycline (TC). After activation, many micropores were introduced to graphene oxide sheets, leading to higher SSA and many new oxygen-containing functional groups, which gave KOH-activated graphene excellent adsorption capacity (approx. 532.59 mg g−1) of TC. Further study on the adsorption mechanism showed that the Langmuir isotherm model and the pseudo-second-order kinetic model fitted with experiment data. To further understand the adsorption process, the effects of solid–liquid ratio, pH, ionic strength and coexisting ions were also investigated. The results revealed that, compared with pH and ionic strength, solid–liquid ratio and coexisting ions (Cu2+, CrO42−) had more significant influence over the adsorption performance. The findings provide guidance for application of KOH-activated graphene as a promising alternative adsorbent for antibiotics removal from aqueous solutions. PMID:29291064

Comparison of free radicals formation induced by cold atmospheric plasma, ultrasound, and ionizing radiation.

PubMed

Rehman, Mati Ur; Jawaid, Paras; Uchiyama, Hidefumi; Kondo, Takashi

2016-09-01

Plasma medicine is increasingly recognized interdisciplinary field combining engineering, physics, biochemistry and life sciences. Plasma is classified into two categories based on the temperature applied, namely "thermal" and "non-thermal" (i.e., cold atmospheric plasma). Non-thermal or cold atmospheric plasma (CAP) is produced by applying high voltage electric field at low pressures and power. The chemical effects of cold atmospheric plasma in aqueous solution are attributed to high voltage discharge and gas flow, which is transported rapidly on the liquid surface. The argon-cold atmospheric plasma (Ar-CAP) induces efficient reactive oxygen species (ROS) in aqueous solutions without thermal decomposition. Their formation has been confirmed by electron paramagnetic resonance (EPR) spin trapping, which is reviewed here. The similarities and differences between the plasma chemistry, sonochemistry, and radiation chemistry are explained. Further, the evidence for free radical formation in the liquid phase and their role in the biological effects induced by cold atmospheric plasma, ultrasound and ionizing radiation are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Application of elevated temperature-dispersive liquid-liquid microextraction for determination of organophosphorus pesticides residues in aqueous samples followed by gas chromatography-flame ionization detection.

PubMed

Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Rezaee Aghdam, Samaneh; Nouri, Nina; Bamorrowat, Mahdi

2016-12-01

In the present study, an elevated temperature, dispersive, liquid-liquid microextraction/gas chromatography-flame ionization detection was investigated for the determination, pre-concentration, and extraction of six organophosphorus pesticides (malathion, phosalone, dichlorvos, diazinon, profenofos, and chlorpyrifos) residues in fruit juice and aqueous samples. A mixture of 1,2-dibromoethane (extraction solvent) and dimethyl sulfoxide (disperser solvent) was injected rapidly into the sample solution heated at an elevated temperature. Analytical parameters, including enrichment factors (1600-2075), linearity (r>0.994), limits of detection (0.82-2.72ngmL(-1)) and quantification (2.60-7.36ngmL(-1)), relative standard deviations (<7%) and extraction recoveries (64-83%), showed the high efficiency of the method developed for analysis of the target analytes. The proposed procedure was used effectively to analyse selected analytes in river water and fruit juice, and diazinon was found at ngmL(-1) concentrations in apple juice. Copyright © 2016 Elsevier Ltd. All rights reserved.

A liquid-liquid transition in supercooled aqueous solution related to the HDA-LDA transition.

PubMed

Woutersen, Sander; Ensing, Bernd; Hilbers, Michiel; Zhao, Zuofeng; Angell, C Austen

2018-03-09

Simulations and theory suggest that the thermodynamic anomalies of water may be related to a phase transition between two supercooled liquid states, but so far this phase transition has not been observed experimentally because of preemptive ice crystallization. We used calorimetry, infrared spectroscopy, and molecular dynamics simulations to investigate a water-rich hydrazinium trifluoroacetate solution in which the local hydrogen bond structure surrounding a water molecule resembles that in neat water at elevated pressure, but which does not crystallize upon cooling. Instead, this solution underwent a sharp, reversible phase transition between two homogeneous liquid states. The hydrogen-bond structures of these two states are similar to those established for high- and low-density amorphous (HDA and LDA) water. Such structural similarity supports theories that predict a similar sharp transition in pure water under pressure if ice crystallization could be suppressed. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

The solvation structures of cellulose microfibrils in ionic liquids.

PubMed

Mostofian, Barmak; Smith, Jeremy C; Cheng, Xiaolin

2011-12-01

The use of ionic liquids for non-derivatized cellulose dissolution promises an alternative method for the thermochemical pretreatment of biomass that may be more efficient and environmentally acceptable than more conventional techniques in aqueous solution. Here, we performed equilibrium MD simulations of a cellulose microfibril in the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) and compared the solute structure and the solute-solvent interactions at the interface with those from corresponding simulations in water. The results indicate a higher occurrence of solvent-exposed orientations of cellulose surface hydroxymethyl groups in BmimCl than in water. Moreover, spatial and radial distribution functions indicate that hydrophilic surfaces are a preferred site of interaction between cellulose and the ionic liquid. In particular, hydroxymethyl groups on the hydrophilic fiber surface adopt a different conformation from their counterparts oriented towards the fiber's core. Furthermore, the glucose units with these solvent-oriented hydroxymethyls are surrounded by the heterocyclic organic cation in a preferred parallel orientation, suggesting a direct and distinct interaction scheme between cellulose and BmimCl.

Laboratory studies of the low-temperature deliquescence of calcium chloride salts: Relevance to aqueous solutions on Mars and in the Antarctic Dry Valleys

NASA Astrophysics Data System (ADS)

Gough, R. V.; Chevrier, V.; Tolbert, M. A.

2013-12-01

There is significant interest in the possible existence of liquid water on current Mars. This water would likely exist as a brine in order to be stable on Mars today. It has been proposed that soil salts could form aqueous solutions through either the melting of ice by low-eutectic salts, or by the deliquescence of hygroscopic salts present in the Martian soil. The focus thus far has largely been on perchlorate species, which can melt ice at temperatures as low as 206 K and can deliquesce at relative humidity values as low as 38% RH. A Mars-relevant salt that has been neglected thus far is calcium chloride (CaCl2). Calcium has been reported to be an abundant cation at the Phoenix landing site and Mars Science Laboratory instruments have recently identified calcium as well. Simulations suggest subsurface CaCl2 is an ideal candidate to produce brines with seasonality consistent with observed recurring slope lineae (RSL) (Chevrier et al., 2012). Finally, the only terrestrial site where RSL-like features have been observed (near Don Juan Pond in the Antarctic Dry Valleys) contains abundant CaCl2. These seasonal slope streaks are thought to form when CaCl2 in the soil deliquesces due to contact with atmospheric water vapor (Dickson et al., 2013). It is important to understand how this CaCl2 interacts with water vapor at low temperatures relevant to Mars and the Martian analog sites. Here we use a Raman microscope and environmental cell to monitor the low-temperature (223 - 273 K) deliquescence (solid to aqueous phase transition) and efflorescence (aqueous to solid phase transition) of three hydration states of CaCl2 (dihydrate, tetrahydrate, hexahydrate). We have found that the deliquescence relative humidity (DRH) increases with increasing hydration state, which is an expected result. Average DRH values over the temperature range studied are 20.0 × 2.6% RH for the dihydrate, 31.8 × 6.3% RH for the tetrahydrate and 60.7 × 1.6% RH for the hexahydrate. Once the aqueous solution has formed, efflorescence (recrystallization) of the salt is kinetically hindered and supersaturated solutions can exist at humidities far below the DRH. Regardless of temperature or initial hydration state of the solid salt, we do not observe efflorescence of the aqueous solutions to occur until single digit RH values are reached. We show here that calcium chloride is at least as deliquescent as many perchlorate salts, and that solutions of calcium chloride are even more difficult to recrystallize once a brine solution has formed. These experimental results will assist with interpretation of observations of deliquescence in the Antarctic Dry Valleys and will help us understand potential liquid water formation on Mars. In addition to formation of brines through melting, deliquescence of salts such as CaCl2 is a reasonable mechanism for formation of aqueous solutions on current Mars.

Models of globular proteins in aqueous solutions

NASA Astrophysics Data System (ADS)

Wentzel, Nathaniel James

Protein crystallization is a continuing area of research. Currently, there is no universal theory for the conditions required to crystallize proteins. A better understanding of protein crystallization will be helpful in determining protein structure and preventing and treating certain diseases. In this thesis, we will extend the understanding of globular proteins in aqueous solutions by analyzing various models for protein interactions. Experiments have shown that the liquid-liquid phase separation curves for lysozyme in solution with salt depend on salt type and salt concentration. We analyze a simple square well model for this system whose well depth depends on salt type and salt concentration, to determine the phase coexistence surfaces from experimental data. The surfaces, calculated from a single Monte Carlo simulation and a simple scaling argument, are shown as a function of temperature, salt concentration and protein concentration for two typical salts. Urate Oxidase from Asperigillus flavus is a protein used for studying the effects of polymers on the crystallization of large proteins. Experiments have determined some aspects of the phase diagram. We use Monte Carlo techniques and perturbation theory to predict the phase diagram for a model of urate oxidase in solution with PEG. The model used includes an electrostatic interaction, van der Waals attraction, and a polymerinduced depletion interaction. The results agree quantitatively with experiments. Anisotropy plays a role in globular protein interactions, including the formation of hemoglobin fibers in sickle cell disease. Also, the solvent conditions have been shown to play a strong role in the phase behavior of some aqueous protein solutions. Each has previously been treated separately in theoretical studies. Here we propose and analyze a simple, combined model that treats both anisotropy and solvent effects. We find that this model qualitatively explains some phase behavior, including the existence of a lower critical point under certain conditions.

Extraction of organic compounds with room temperature ionic liquids.

PubMed

Poole, Colin F; Poole, Salwa K

2010-04-16

Room temperature ionic liquids are novel solvents with a rather specific blend of physical and solution properties that makes them of interest for applications in separation science. They are good solvents for a wide range of compounds in which they behave as polar solvents. Their physical properties of note that distinguish them from conventional organic solvents are a negligible vapor pressure, high thermal stability, and relatively high viscosity. They can form biphasic systems with water or low polarity organic solvents and gases suitable for use in liquid-liquid and gas-liquid partition systems. An analysis of partition coefficients for varied compounds in these systems allows characterization of solvent selectivity using the solvation parameter model, which together with spectroscopic studies of solvent effects on probe substances, results in a detailed picture of solvent behavior. These studies indicate that the solution properties of ionic liquids are similar to those of polar organic solvents. Practical applications of ionic liquids in sample preparation include extractive distillation, aqueous biphasic systems, liquid-liquid extraction, liquid-phase microextraction, supported liquid membrane extraction, matrix solvents for headspace analysis, and micellar extraction. The specific advantages and limitations of ionic liquids in these studies is discussed with a view to defining future uses and the need not to neglect the identification of new room temperature ionic liquids with physical and solution properties tailored to the needs of specific sample preparation techniques. The defining feature of the special nature of ionic liquids is not their solution or physical properties viewed separately but their unique combinations when taken together compared with traditional organic solvents. Copyright 2009 Elsevier B.V. All rights reserved.

Effect of polyethylene glycol on the liquid–liquid phase transition in aqueous protein solutions

PubMed Central

Annunziata, Onofrio; Asherie, Neer; Lomakin, Aleksey; Pande, Jayanti; Ogun, Olutayo; Benedek, George B.

2002-01-01

We have studied the effect of polyethylene glycol (PEG) on the liquid–liquid phase separation (LLPS) of aqueous solutions of bovine γD-crystallin (γD), a protein in the eye lens. We observe that the phase separation temperature increases with both PEG concentration and PEG molecular weight. PEG partitioning, which is the difference between the PEG concentration in the two coexisting phases, has been measured experimentally and observed to increase with PEG molecular weight. The measurements of both LLPS temperature and PEG partitioning in the ternary γD-PEG-water systems are used to successfully predict the location of the liquid–liquid phase boundary of the binary γD-water system. We show that our LLPS measurements can be also used to estimate the protein solubility as a function of the concentration of crystallizing agents. Moreover, the slope of the tie-lines and the dependence of LLPS temperature on polymer concentration provide a powerful and sensitive check of the validity of excluded volume models. Finally, we show that the increase of the LLPS temperature with PEG concentration is due to attractive protein–protein interactions. PMID:12391331

Hexadecyltrimethylammonium bromide (CTA-Br) and 1-butyl-3-methylimidazolium tetrafluoroborate (bmim-BF4) in aqueous solution: An ephemeral binary system.

PubMed

Comelles, Francesc; Ribosa, Isabel; Gonzalez, Juan José; Garcia, M Teresa

2017-03-15

Mixtures of the cationic surfactant hexadecyltrimethylammonium bromide (CTA-Br) and the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (bmim-BF 4 ) in aqueous solutions are expected to behave as typical binary cationic surfactant system taking into account the surface activity displayed by the ionic liquid, instead of considering the IL as a water cosolvent. Surface tension and conductivity measurements have been conducted as a function of the total concentration of the mixtures at different surfactant mole fraction (α CTA-Br ) to investigate the surface active properties. Turbidity immediately appearing when the compounds are mixed in water suggests the spontaneous formation of the low soluble compound hexadecyltrimethylammonium tetrafluoroborate (CTA-BF 4 ), together with the salt formed by the respective counterions bmim + and Br - in solution. For α CTA-Br ≠0.5, furthermore of the mentioned compounds, the spare bmim-BF 4 (for α CTA-Br <0.5) or CTA-Br (for α CTA-Br >0.5), are also present in the aqueous solution. Systems containing excess of bmim-BF 4 show a low critical aggregate concentration (cac), but an unexpected high surface tension at cac (γ cac ≈53-56mN/m), as pure CTA-BF 4 . For systems containing excess of CTA-Br, cac increases but γ cac decreases up to 36mN/m. Mixtures of pure CTA-BF 4 and bmim-BF 4 or CTA-Br behave as typical binary surfactant systems. Copyright © 2016 Elsevier Inc. All rights reserved.

[Influences of ion-suppressors on retention behaviors of nine food additives in reversed-phase high performance liquid chromatographic separation].

PubMed

Zhao, Yonggang; Chen, Xiaohong; Li, Xiaoping; Yao, Shanshan; Jin, Micong

2011-10-01

The influences of ion-suppressors on retention behaviors of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in reversed-phase high performance liquid chromatographic (RP-HPLC) separation were investigated. The organic modification effects of acids, i. e. , trifluoroacetic acid (TFA) and buffer salts, i. e. , TFA-ammonium acetate (AmAc) were studied emphatically. The relationships between retention factors of solutes and volume percentages of ion-suppressors in the mobile phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, separately. The separation of nine food additives was completed by a gradient elution with acetonitrile-TFA (0.01%, v/v)-AmAc (2. 5 mmol/L) aqueous solution as the mobile phases. An RP-HPLC method was established for the simultaneous determination of nine food additives in red wine. In the range of 10. 0 - 100. 0 mg/L, nine food additives showed good linearity with the correlation coefficients ( r2 ) larger than 0. 999 1. The limits of detection (LODs) were in the range of 0. 33 - 2. 36 mg/L and the limits of quantification (LOQs) were in the range of 1. 11 - 7. 80 mg/L. The spiked recoveries were between 87. 61% and 108. 4% with the relative standard deviations (RSDs) of 2. 2% -9. 4%. These results are of referential significance for the rapid establishment and accu- rate optimization of RP-HPLC separation for the simultaneous determination of food additives in other foods.

Analysis of nine food additives in red wine by ion-suppression reversed-phase high-performance liquid chromatography using trifluoroacetic acid and ammonium acetate as ion-suppressors.

PubMed

Zhao, Yong-Gang; Chen, Xiao-Hong; Yao, Shan-Shan; Pan, Sheng-Dong; Li, Xiao-Ping; Jin, Mi-Cong

2012-01-01

A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in red wine. The effects of ion-suppressors, i.e., trifluoroacetic acid (TFA) and ammonium acetate (AmAc) on retention behavior of nine food additives in RP-HPLC separation were discussed in detail. The relationships between retention factors of solutes and volume percent of ion-suppressors in the mobile-phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, respectively. The results showed that the ion suppressors had not only an ion suppression effect, but also an organic modification effect on the acidic analytes. The baseline separation of nine food additives was completed by a gradient elution with acetonitrile-TFA(0.01%, v/v)-AmAc(2.5 mmol L(-1)) aqueous solution as the mobile phase. The recoveries were between 80.2 - 99.5% for all analytes with RSDs in the range of 1.5 - 8.9%. The linearities were in the range of 0.2 - 100.0 mg L(-1) with determination coefficients (r(2)) higher than 0.9991 for all analytes. The limits of quantification (LOQs) were between 0.53 - 0.99 mg L(-1). The applicability of the proposed method to detect and quantify food additives has been demonstrated in the analysis of 30 real samples.

Dynamic control of gold nanoparticle morphology in a microchannel flow reactor by glucose reduction in aqueous sodium hydroxide solution.

PubMed

Ishizaka, Takayuki; Ishigaki, Atsushi; Kawanami, Hajime; Suzuki, Akira; Suzuki, Toshishige M

2012-02-01

Continuous flow synthesis of gold nanoparticles was demonstrated using a microchannel reactor with glucose reduction in aqueous alkaline medium. Particle size, morphology, and visual/optical properties of the dispersion liquid were controlled dynamically by tuning of the rate of NaOH addition. Characteristic star-like nanoparticles formed spontaneously as a quasi-stable state, but they changed the morphology to round shape and showed spectral change over time. Copyright © 2011 Elsevier Inc. All rights reserved.

Kinetics of insulin aggregation in aqueous solutions upon agitation in the presence of hydrophobic surfaces.

PubMed Central

Sluzky, V; Tamada, J A; Klibanov, A M; Langer, R

1991-01-01

The stability of protein-based pharmaceuticals (e.g., insulin) is important for their production, storage, and delivery. To gain an understanding of insulin's aggregation mechanism in aqueous solutions, the effects of agitation rate, interfacial interactions, and insulin concentration on the overall aggregation rate were examined. Ultraviolet absorption spectroscopy, high-performance liquid chromatography, and quasielastic light scattering analyses were used to monitor the aggregation reaction and identify intermediate species. The reaction proceeded in two stages; insulin stability was enhanced at higher concentration. Mathematical modeling of proposed kinetic schemes was employed to identify possible reaction pathways and to explain greater stability at higher insulin concentration. Images PMID:1946348

Determination of redox reaction rates and orders by in situ liquid cell electron microscopy of Pd and Au solution growth.

PubMed

Sutter, Eli A; Sutter, Peter W

2014-12-03

In-situ liquid cell transmission and scanning transmission electron microscopy (TEM/STEM) experiments are important, as they provide direct insight into processes in liquids, such as solution growth of nanoparticles, among others. In liquid cell TEM/STEM redox reaction experiments, the hydrated electrons e(-)aq created by the electron beam are responsible for the reduction of metal-ion complexes. Here we investigate the rate equation of redox reactions involving reduction by e(-)aq generated by the electron beam during in situ liquid TEM/STEM. Specifically we consider the growth of Pd on Au seeds in aqueous solutions containing Pd-chloro complexes. From the quantification of the rate of Pd deposition at different electron beam currents and as a function of distance from a stationary, nanometer-sized exciting beam, we determine that the reaction is first order with respect to the concentration of hydrated electrons, [e(-)aq]. By comparing Pd- and Au-deposition, we further demonstrate that measurements of the local deposition rate on nanoparticles in the solution via real-time imaging can be used to measure not only [e(-)aq] but also the rate of reduction of a metal-ion complex to zerovalent metal atoms in solution.

Determination of redox reaction rates and orders by in situ liquid cell electron microscopy of Pd and Au solution growth

DOE PAGES

Sutter, Eli A.; Sutter, Peter W.

2014-11-19

In-situ liquid cell transmission and scanning transmission electron microscopy (TEM/STEM) experiments are important as they provide direct insight into processes in liquids, such as solution growth of nanoparticles among others. In liquid cell TEM/STEM redox reaction experiments the hydrated electrons e⁻ aq created by the electron beam are responsible for the reduction of metal-ion complexes. Here we investigate the rate equation of redox reactions involving reduction by e⁻ aq generated by the electron beam during in-situ liquid TEM/STEM. Specifically we consider the growth of Pd on Au seeds in aqueous solutions containing Pd-chloro complexes. From the quantification of the ratemore » of Pd deposition at different electron beam currents and as a function of distance from a stationary, nanometer-sized exciting beam, we determine that the reaction is first order with respect to the concentration of hydrated electrons, [e⁻ aq]. In addition, by comparing Pd- and Au-deposition, we further demonstrate that measurements of the local deposition rate on nanoparticles in the solution via real-time imaging can be used to measure not only [e⁻ aq] but also the rate of reduction of a metal-ion complex to zero-valent metal atoms in solution.« less

Deep eutectic solvent based gas-assisted dispersive liquid-phase microextraction combined with gas chromatography and flame ionization detection for the determination of some pesticide residues in fruit and vegetable samples.

PubMed

Farajzadeh, Mir Ali; Sattari Dabbagh, Masoumeh; Yadeghari, Adeleh

2017-05-01

In this study, a gas-assisted dispersive liquid-phase microextraction method using a deep eutectic solvent as the extraction solvent combined with gas chromatography and flame ionization detection was developed for the extraction and determination of some pesticide residues in vegetable and fruit juice samples. In this method, choline chloride and 4-chlorophenol at a molar ratio of 1:2 were mixed. By heating and vortexing, a clear, water-immiscible, and homogeneous liquid was formed. The obtained deep eutectic solvent was added to an aqueous solution of the analytes in a conical test tube. Air was bubbled into the aqueous solution and a cloudy solution was obtained. During this step, the analytes were extracted into the fine droplets of the extraction solvent. After centrifugation, an aliquot of the settled phase was injected into the separation system. Under the optimum extraction conditions, enrichment factors, and extraction recoveries were obtained in the ranges of 247-355 and 49-71%, respectively. The obtained values for the limits of detection and quantification were in the ranges of 0.24-1.4 and 0.71-4.2 μg/L, respectively. The proposed method is simple, fast, efficient, and inexpensive. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liquid Viscosity and Density Measurement with Flexural-Plate-Wave Sensors

DTIC Science & Technology

1996-04-01

capillary-viscometer-measured viscosity in Fig. 4. "The data from solutions of poly(ethylene glycol), having average molecular weights 3350 and 15,000...have seen similar results for the FPW-measured viscosity of salmon-sperm DNA solutions. 25 glycerol WA " PEG 3,350 H-4 . e! 2 PEG 15,000 IK- ,,,," HEC...number of aqueous solutions of the polymers poly(ethylene glycol) ( PEG ) and hydroxyethyl cellulose (HEC). The response of the FPW sensor (vertical axis

The relationship between dielectrophoretic and impedance response of dielectric particles immersed in aqueous media

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

Bahaj, A.E.; Bailey, A.G.

1985-09-01

Dielectrophoretic force measurements on isolated 50-..mu..m diameter particles of divinylbenzene (DVB) suspended in aqueous solutions show that force is dependent on relaxation mechanisms present at the particle-liquid interface. Measurements on single particles have been extended to measurements on populations of particles. The impedance of aqueous suspensions of particles contained in a gold-plated electrode test cell has been measured over a range of frequency. Data are presented in the form of Cole-Cole plots. It is shown that the dielectrophoretic response of single particles can be related to the frequency-dependent impedance behavior of suspensions of similar particles.

40 CFR 409.31 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... STANDARDS SUGAR PROCESSING POINT SOURCE CATEGORY Liquid Cane Sugar Refining Subcategory § 409.31 Specialized... shall mean the addition of pollutants. (c) Melt shall mean that amount of raw material (raw sugar) contained within aqueous solution at the beginning of the process for production of refined cane sugar. ...

40 CFR 409.31 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... STANDARDS SUGAR PROCESSING POINT SOURCE CATEGORY Liquid Cane Sugar Refining Subcategory § 409.31 Specialized... shall mean the addition of pollutants. (c) Melt shall mean that amount of raw material (raw sugar) contained within aqueous solution at the beginning of the process for production of refined cane sugar. ...

40 CFR 409.31 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... STANDARDS SUGAR PROCESSING POINT SOURCE CATEGORY Liquid Cane Sugar Refining Subcategory § 409.31 Specialized... shall mean the addition of pollutants. (c) Melt shall mean that amount of raw material (raw sugar) contained within aqueous solution at the beginning of the process for production of refined cane sugar. ...

40 CFR 409.31 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... STANDARDS SUGAR PROCESSING POINT SOURCE CATEGORY Liquid Cane Sugar Refining Subcategory § 409.31 Specialized... shall mean the addition of pollutants. (c) Melt shall mean that amount of raw material (raw sugar) contained within aqueous solution at the beginning of the process for production of refined cane sugar. ...

Keggin-type polyoxometalate nanosheets: synthesis and characterization via scanning transmission electron microscopy.

PubMed

Hiyoshi, Norihito

2018-05-17

Polyoxometalate nanosheets were synthesized at the gas/liquid interface of an aqueous solution of Keggin-type silicotungstic acid, cesium chloride, and n-octylamine. The structure of the nanosheets was elucidated via aberration-corrected scanning transmission electron microscopy at the atomic and molecular levels.

Freezing-induced self-assembly of amphiphilic molecules

NASA Astrophysics Data System (ADS)

Albouy, P. A.; Deville, S.; Fulkar, A.; Hakouk, K.; Impéror-Clerc, M.; Klotz, M.; Liu, Q.; Marcellini, M.; Perez, J.

The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0{\\deg}C.

Freezing-induced self-assembly of amphiphilic molecules.

PubMed

Albouy, P A; Deville, S; Fulkar, A; Hakouk, K; Impéror-Clerc, M; Klotz, M; Liu, Q; Marcellini, M; Perez, J

2017-03-01

The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0 °C.

An SFG study of interfacial amino acids at the hydrophilic SiO2 and hydrophobic deuterated polystyrene surfaces.

PubMed

Holinga, George J; York, Roger L; Onorato, Robert M; Thompson, Christopher M; Webb, Nic E; Yoon, Alfred P; Somorjai, Gabor A

2011-04-27

Sum frequency generation (SFG) vibrational spectroscopy was employed to characterize the interfacial structure of eight individual amino acids--L-phenylalanine, L-leucine, glycine, L-lysine, L-arginine, L-cysteine, L-alanine, and L-proline--in aqueous solution adsorbed at model hydrophilic and hydrophobic surfaces. Specifically, SFG vibrational spectra were obtained for the amino acids at the solid-liquid interface between both hydrophobic d(8)-polystyrene (d(8)-PS) and SiO(2) model surfaces and phosphate buffered saline (PBS) at pH 7.4. At the hydrophobic d(8)-PS surface, seven of the amino acids solutions investigated showed clear and identifiable C-H vibrational modes, with the exception being l-alanine. In the SFG spectra obtained at the hydrophilic SiO(2) surface, no C-H vibrational modes were observed from any of the amino acids studied. However, it was confirmed by quartz crystal microbalance that amino acids do adsorb to the SiO(2) interface, and the amino acid solutions were found to have a detectable and widely varying influence on the magnitude of SFG signal from water at the SiO(2)/PBS interface. This study provides the first known SFG spectra of several individual amino acids in aqueous solution at the solid-liquid interface and under physiological conditions.

Self-aggregation of bio-surfactants within ionic liquid 1-ethyl-3-methylimidazolium bromide: A comparative study and potential application in antidepressants drug aggregation

NASA Astrophysics Data System (ADS)

Banjare, Manoj Kumar; Behera, Kamalakanta; Kurrey, Ramsingh; Banjare, Ramesh Kumar; Satnami, Manmohan L.; Pandey, Siddharth; Ghosh, Kallol K.

2018-06-01

Aggregation behavior of bio-surfactants (BS) sodium cholate (NaC) and sodium deoxycholate (NaDC) within aqueous solution of ionic liquid (IL) 1-ethyl-3-methylimidazolium bromide [Emim][Br] has been investigated using surface tension, conductivity, steady state fluorescence, FT-IR and dynamic light scattering (DLS) techniques. Various interfacial and thermodynamic parameters are determined in the presence of different wt% of IL [Emim][Br]. Information regarding the local microenvironment and size of the aggregates is obtained from fluorescence and DLS, respectively. FT-IR spectral response is used to reveal the interactions taking place within aqueous NaC/NaDC micellar solutions. It is noteworthy to mention that increasing wt% of [Emim][Br] results in an increase in the spontaneity of micelle formation and the hydrophilic IL shows more affinity for NaC as compared to NaDC. Further, the micellar solutions of BS-[Emim][Br] are utilized for studying the aggregation of antidepressants drug promazine hydrochloride (pH). UV-vis spectroscopic investigation reveals interesting outcomes and the results show changes in spectral absorbance of PH drug on the addition of micellar solution (BS-[Emim][Br]). Highest binding affinity and most promising activity are shown for NaC as compared to NaDC.

Electrically assisted liquid-phase microextraction combined with capillary electrophoresis for quantification of propranolol enantiomers in human body fluids.

PubMed

Tabani, Hadi; Fakhari, Ali Reza; Shahsavani, Abolfath; Gharari Alibabaou, Hossein

2014-05-01

In this study, electromembrane extraction (EME) combined with cyclodextrin (CD)-modified capillary electrophoresis (CE) was applied for the extraction, separation, and quantification of propranolol (PRO) enantiomers from biological samples. The PRO enantiomers were extracted from aqueous donor solutions, through a supported liquid membrane (SLM) consisting of 2-nitrophenyl octyl ether (NPOE) impregnated on the wall of the hollow fiber, and into a 20-μL acidic aqueous acceptor solution into the lumen of hollow fiber. Important parameters affecting EME efficiency such as extraction voltage, extraction time, pH of the donor and acceptor solutions were optimized using a Box-Behnken design (BBD). Then, under these optimized conditions, the acceptor solution was analyzed using an optimized CD-modified CE. Several types of CD were evaluated and best results were obtained using a fused-silica capillary with ammonium acetate (80 mM, pH 2.5) containing 8 mM hydroxypropyl-β-CD as a chiral selector, applied voltage of 18 kV, and temperature of 20°C. The relative recoveries were obtained in the range of 78-95%. Finally, the performance of the present method was evaluated for the extraction and determination of PRO enantiomers in real biological samples. © 2014 Wiley Periodicals, Inc.

Extraction of anionic dye from aqueous solutions by emulsion liquid membrane.

PubMed

Dâas, Attef; Hamdaoui, Oualid

2010-06-15

In this work, the extraction of Congo red (CR), an anionic disazo direct dye, from aqueous solutions by emulsion liquid membrane (ELM) was investigated. The important operational parameters governing emulsion stability and extraction behavior of dye were studied. The extraction of CR was influenced by a number of variables such as surfactant concentration, stirring speed, acid concentration in the feed solution and volume ratios of internal phase to organic phase and of emulsion to feed solution. Under most favorable conditions, practically all the CR molecules present in the feed phase were extracted even in the presence of salt (NaCl). At the optimum experimental conditions, total removal of antharaquinonic dye Acid Blue 25 was attained after only 10 min. Influence of sodium carbonate concentration as internal receiving phase on the stripping efficiency of CR was examined. The best sodium carbonate concentration in the internal phase that conducted to excellent stripping efficiency (>99%) and emulsion stability was 0.1N. The membrane recovery was total and the permeation of CR was not decreased up to seven runs. ELM process is a promising alternative to conventional methods and should increase awareness of the potential for recovery of anionic dyes. Copyright 2010 Elsevier B.V. All rights reserved.

Organic crystal-binding peptides: morphology control and one-pot formation of protein-displaying organic crystals

NASA Astrophysics Data System (ADS)

Niide, Teppei; Ozawa, Kyohei; Nakazawa, Hikaru; Oliveira, Daniel; Kasai, Hitoshi; Onodera, Mari; Asano, Ryutaro; Kumagai, Izumi; Umetsu, Mitsuo

2015-11-01

Crystalline assemblies of fluorescent molecules have different functional properties than the constituent monomers, as well as unique optical characteristics that depend on the structure, size, and morphological homogeneity of the crystal particles. In this study, we selected peptides with affinity for the surface of perylene crystal particles by exposing a peptide-displaying phage library in aqueous solution to perylene crystals, eluting the surface-bound phages by means of acidic desorption or liquid-liquid extraction, and amplifying the obtained phages in Escherichia coli. One of the perylene-binding peptides, PeryBPb1: VQHNTKYSVVIR, selected by this biopanning procedure induced perylene molecules to form homogenous planar crystal nanoparticles by means of a poor solvent method, and fusion of the peptide to a fluorescent protein enabled one-pot formation of protein-immobilized crystalline nanoparticles. The nanoparticles were well-dispersed in aqueous solution, and Förster resonance energy transfer from the perylene crystals to the fluorescent protein was observed. Our results show that the crystal-binding peptide could be used for simultaneous control of perylene crystal morphology and dispersion and protein immobilization on the crystals.Crystalline assemblies of fluorescent molecules have different functional properties than the constituent monomers, as well as unique optical characteristics that depend on the structure, size, and morphological homogeneity of the crystal particles. In this study, we selected peptides with affinity for the surface of perylene crystal particles by exposing a peptide-displaying phage library in aqueous solution to perylene crystals, eluting the surface-bound phages by means of acidic desorption or liquid-liquid extraction, and amplifying the obtained phages in Escherichia coli. One of the perylene-binding peptides, PeryBPb1: VQHNTKYSVVIR, selected by this biopanning procedure induced perylene molecules to form homogenous planar crystal nanoparticles by means of a poor solvent method, and fusion of the peptide to a fluorescent protein enabled one-pot formation of protein-immobilized crystalline nanoparticles. The nanoparticles were well-dispersed in aqueous solution, and Förster resonance energy transfer from the perylene crystals to the fluorescent protein was observed. Our results show that the crystal-binding peptide could be used for simultaneous control of perylene crystal morphology and dispersion and protein immobilization on the crystals. Electronic supplementary information (ESI) available: Schematic representation of PeryBPb1-fused DsRed-Monomer, fluorescence spectra of perylene crystals and DsRed-Monomer, and emission spectra of DsRed-Monomer at various excitation wavelengths. See DOI: 10.1039/c5nr06471f

Lyotropic Phase Behavior of Polybutadiene-Poly(ethylene oxide) Diblock Copolymers in Ionic Liquids

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

Simone, Peter M.; Lodge, Timothy P.

2008-08-26

The lyotropic phase behavior of three poly(1,2-butadiene-b-ethylene oxide) diblock copolymers (PB-PEO) with different monomer volume fractions has been studied in two different ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF{sub 6}]), across the complete concentration range. The ordered microstructures present in the solutions were characterized via small-angle X-ray scattering (SAXS). The phase diagrams for the PB-PEO/ionic liquid solutions include regions corresponding to the classical copolymer microstructures: body-centered-cubic lattices of spheres, hexagonally ordered cylinders, and lamellae. Additionally, the phase diagrams also include wide regions of coexisting microstructures and regions apparently corresponding to a disordered network microstructure. The phase behavior ofmore » the PB-PEO copolymers in both ionic liquids was comparable to their previously reported aqueous solution behavior. The temperature dependence of the phase diagrams was very modest, indicative of a highly segregated system. The level of solvent selectivity was also investigated via cryogenic transmission electron microscopy (cryo-TEM) on dilute solutions. On the basis of the morphology of the dilute solution copolymer aggregate structures in the ionic liquid solvents, and on the structural length scales of the concentrated solutions, it was concluded that for PB-PEO [BMI][PF{sub 6}] behaves as a more selective solvent than [EMI][TFSI].« less

Aqueous Silicate Polymers: An Alternative to `Supercritical' Fluids as Transport Agents in Subduction Zones

NASA Astrophysics Data System (ADS)

Mannig, C. E.

2005-12-01

The chemistry of subduction-zone fluids is complicated by melt-vapor miscibility and the existence of critical end-points in rock-H2O systems. It is commonly assumed that fluids in subduction zones attain properties intermediate in composition between hydrous silicate liquid and H2O, and that such fluids possess enhanced material transport capabilities. However, the relevance of supercritical, intermediate fluids to subduction zones presents four problems. (1) Albite-H2O is typically used as an analogue system, but the favorable position of its critical curve is not representative; critical curves for polymineralic subduction-zone lithologies lie at substantially higher P. (2) Even if albite-H2O is relevant, jadeite may interfere because of its different solubility and the positive clapeyron slope of its solidus, which points to liquid-structure changes that could cause reappearance of the liquid+vapor field. (3) Critical curves are features of very H2O-rich compositions; low-porosity, H2O-poor natural systems will coexist with intermediate fluids only over a narrow PT interval. (4) Intermediate fluids are expected only over short length scales because their migration will likely result in compositional shifts via reaction and mineral precipitation in the mantle wedge. Although supercritical, intermediate fluids are probably relatively unimportant in subduction zones, they reflect a chemical process that may hold the key to understanding high- P mass transfer. Miscibility in melt-vapor systems is a consequence of polymerization of dissolved components, primarily Si ± Al, Na and Ca. This behavior yields, e.g., aqueous Si-Si, Si-Al, Si-Na-Al, and Si-Ca oxide dimers and other multimers of varying stoichiometry (silicate polymers), even in subcritical, dilute, H2O-rich vapor. Silicate polymers in subcritical aqueous solutions have been inferred from high- P mineral-solubility experiments. The abundance of these species at high P shows that the chemistry of aqueous fluids in subduction-zones differs fundamentally from the more familiar ionic solutions of the upper crust. This has important consequences for minor element transport. Measurements of Fe, phosphorous and Ti solubility reveal that dissolved concentrations rise with increased aqueous albite content at fixed P and T, with maximum enhancements exceeding 10X at melt saturation. Subcritical silicate polymerization thus permits transport of low solubility components via their substitution into sites on aqueous multimers constructed of "polymer formers" such as Na, Al, and Si, even in dilute solutions. The partitioning of elements between the bulk fluid, the polymer network, and the rock matrix likely controls the overall compositional evolution of subduction-zone fluids. Because they form over a wider PT and bulk X range, subcritical silicate polymers in dilute solutions are likely responsible for more mass transfer in subduction zones than intermediate, supercritical fluids.

Liquid Superlubricity of Polyethylene Glycol Aqueous Solution Achieved with Boric Acid Additive.

PubMed

Ge, Xiangyu; Li, Jinjin; Zhang, Chenhui; Luo, Jianbin

2018-03-27

Boric acid is a weak acid and has been used as a lubrication additive because of its special structure. In this study, we report that boric acid could achieve a robust superlubricity (μ < 0.01) as an additive in polyethylene glycol (PEG) aqueous solution at the Si 3 N 4 /SiO 2 interfaces. The superlow and steady friction coefficient of approximately 0.004-0.006 could be achieved with boric acid under neutral conditions (pH of approximately 6.4), which is different from the acidic conditions leading to superlubricity. The influence of various factors, including boric acid concentration, sliding speed, applied load, PEG molecular weight, and the volume of lubricant on the superlubricity, were investigated. The results reveal that the PEG aqueous solution with the boric acid additive could achieve superlubricity under a wide range of conditions. The surface composition analysis shows that the synergy effect between boric acid and PEG provides sufficient H + ions to realize the running-in process. Moreover, a composite tribochemical film composed of silica and ammonia-containing compounds were formed on the ball surface, contributing to the superlubricity. The film thickness calculation shows that superlubricity was achieved in a mixed lubrication region, and therefore, the superlubricity state was dominated by both the composite tribochemical film formed via the tribochemical reaction on the contact surfaces and the hydrodynamic lubricating film between the contact surfaces. Such a liquid superlubricity achieved under neutral conditions is of importance for both scientific understanding and engineering applications.

Investigation of Liquid Surface Rheology of Surfactant Solutions by Droplet Shape Oscillations: Experiments

PubMed

Tian; Holt; Apfel

1997-03-01

The experimental results of droplet shape oscillations are reported and applied to the analysis of surface rheological properties of surfactant solutions. An acoustic levitation technique is used to suspend the test drop in air and excite it into quadrupole shape oscillations. The equilibrium surface tension, Gibbs elasticity, and surface dilatational viscosity are determined from the measurements of droplet static shape under different levitation sound pressure, oscillation frequency, and free damping constant. Aqueous solutions of sodium dodecyl sulfate, dodecyltrimethylammonium bromide, and n-octyl beta-d-glucopyranoside are tested with this system. The concentrations of the solutions are below the critical micelle concentration. For these solutions it is found that the surface Gibbs elasticity approaches a maximum at a moderate concentration, and its value is less than that directly calculated from the state equation of a static liquid surface. The surface dilatational viscosity is found to be in a range around 0.1 cps.

Effect of Fe 3+ concentration on MWCNTs formation in liquid arcing method

NASA Astrophysics Data System (ADS)

Shervin, Sh.; Gheytani, S.; Simchi, A.

2010-10-01

The formation of multi-walled carbon nanotubes (MWCNTs) during arc discharge in aqueous solutions of Fe 2(SO 4) 3 and FeCl 3 was studied. The concentration of iron ions changed from zero (deionized water) to 0.25 M and the cathodic products were examined by transmission electron microscopy, Raman spectrometry, and thermal gravimetric analysis. The experimental results showed that the crystallinity of MWCNTs is improved by increasing the concentration of iron ions. Nevertheless, the process yield and overall quality of the produced CNTs were significantly affected by iron concentration in the aqueous solution. This observation suggested that there should be an optimum iron concentration at which the formation of MWCNTs is favored. As compared with the sulfate solution, a higher process yield is obtained in the presence of chloride ions in agreement with previous reports.

Activity of Cu-activated carbon fiber catalyst in wet oxidation of ammonia solution.

PubMed

Hung, Chang-Mao

2009-07-30

Aqueous solutions of 200-1000 mg/L of ammonia were oxidized in a trickle-bed reactor using Cu-activated carbon fiber (ACF) catalysts, which were prepared by incipient wet impregnation with aqueous solutions of copper nitrate that was deposited on ACF substrates. The results reveal that the conversion of ammonia by wet oxidation in the presence of Cu-ACF catalysts was a function of the metal loading weight ratio of the catalyst. The total conversion efficiency of ammonia was 95% during wet oxidation over the catalyst at 463 K at an oxygen partial pressure of 3.0 MPa. Moreover, the effect of the initial concentration of ammonia and the reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid space velocity of less than 3.0 h(-1).

Comparative study of urea and betaine solutions by dielectric spectroscopy: liquid structures of a protein denaturant and stabilizer.

PubMed

Hayashi, Yoshihito; Katsumoto, Yoichi; Oshige, Ikuya; Omori, Shinji; Yasuda, Akio

2007-10-11

We performed dielectric spectroscopy measurements on aqueous solutions of glycine betaine (N,N,N-trimethylglycine), which is known to be a strong stabilizer of globular proteins, over a wide concentration range (3-62 wt %) and compared the results with our previously published data for aqueous solutions of urea, a representative protein denaturant. The hydration number of betaine (9), calculated on the basis of the reduction in the dielectric relaxation strength of bulk water with addition of betaine, is significantly larger than that of urea (2). Furthermore, the dielectric relaxation time increased with betaine concentration, while that remained nearly constant for the urea-water system over a wide concentration range. This difference between urea and betaine is probably related to their opposite effects on the protein stabilization.

Experimental evidence for excess entropy discontinuities in glass-forming solutions.

PubMed

Lienhard, Daniel M; Zobrist, Bernhard; Zuend, Andreas; Krieger, Ulrich K; Peter, Thomas

2012-02-21

Glass transition temperatures T(g) are investigated in aqueous binary and multi-component solutions consisting of citric acid, calcium nitrate (Ca(NO(3))(2)), malonic acid, raffinose, and ammonium bisulfate (NH(4)HSO(4)) using a differential scanning calorimeter. Based on measured glass transition temperatures of binary aqueous mixtures and fitted binary coefficients, the T(g) of multi-component systems can be predicted using mixing rules. However, the experimentally observed T(g) in multi-component solutions show considerable deviations from two theoretical approaches considered. The deviations from these predictions are explained in terms of the molar excess mixing entropy difference between the supercooled liquid and glassy state at T(g). The multi-component mixtures involve contributions to these excess mixing entropies that the mixing rules do not take into account. © 2012 American Institute of Physics

The Use of Index-Matched Beads in Optical Particle Counters

PubMed Central

Hu, Zhishang; Ripple, Dean C

2014-01-01

In this paper, we demonstrate the use of 2-pyridinemethanol (2P) aqueous solutions as a refractive index matching liquid. The high refractive index and low viscosity of 2P-water mixtures enables refractive index matching of beads that cannot be index matched with glycerol-water or sucrose-water solutions, such as silica beads that have the refractive index of bulk fused silica or of polymethylmethacrylate beads. Suspensions of beads in a nearly index-matching liquid are a useful tool to understand the response of particle counting instruments to particles of low optical contrast, such as aggregated protein particles. Data from flow imaging and light obscuration instruments are presented for bead diameters ranging from 6 µm to 69 µm, in a matrix liquid spanning the point of matched refractive index. PMID:26601049

MERCURY(II) PARTITIONING FROM AQUEOUS SOLUTIONS WITH A NEW, HYDROPHOBIC ETHYLENE-GLYCOL FUNCTIONALIZED BIS(METHYLIMIDAZOLIUM) IONIC LIQUID. (R828257)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

ION CHROMATOGRAPHIC DETERMINATION OF PERCHLORATE ION: ANALYSIS OF FERTILIZERS AND RELATED MATERIALS

EPA Science Inventory

A solid fertilizer sample is dissolved or leached to solutilize the perchlorate as the aqueous anion. If needed, the liquid is filtered or centrifuged. The rsulting solution is subjected to ion chromatography using an adaptation of EPA Method 314.0. Preliminary screenng is requir...

21 CFR 184.1585 - Papain.

Code of Federal Regulations, 2014 CFR

2014-04-01

....1585 Papain. (a) Papain (CAS Reg. No. 9001-73-4) is a proteolytic enzyme derived from Carica papaya L. Crude latex containing the enzyme is collected from slashed unripe papaya. The food-grade product is... an aqueous solution of latex. The resulting enzyme preparation may be used in a liquid or dry form...

Surfactant-based ionic liquids for extraction of phenolic compounds combined with rapid quantification using capillary electrophoresis.

PubMed

Huang, Fangzhi; Berton, Paula; Lu, Chengfei; Siraj, Noureen; Wang, Chun; Magut, Paul K S; Warner, Isiah M

2014-09-01

A rapid liquid phase extraction employing a novel hydrophobic surfactant-based room temperature ionic liquid (RTIL), tetrabutylphosphonium dioctyl sulfosuccinate ([4C4 P][AOT]), coupled with capillary electrophoretic-UV (CE-UV) detection is developed for removal and determination of phenolic compounds. The long-carbon-chain RTIL used is sparingly soluble in most solvents and can be used to replace volatile organic solvents. This fact, in combination with functional-surfactant-anions, is proposed to reduce the interfacial energy of the two immiscible liquid phases, resulting in highly efficient extraction of analytes. Several parameters that influence the extraction efficiencies, such as extraction time, RTIL type, pH value, and ionic strength of aqueous solutions, were investigated. It was found that, under acidic conditions, most of the investigated phenols were extracted from aqueous solution into the RTIL phase within 12 min. Good linearity was observed over the concentration range of 0.1-80.0 μg/mL for all phenols investigated. The precision of this method, expressed as RSD, was determined to be within 3.4-5.3% range. The LODs (S/N = 3) of the method were in the range of 0.047-0.257 μg/mL. The proposed methodology was successfully applied to determination of phenols in real water samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Achieving accurate compound concentration in cell-based screening: validation of acoustic droplet ejection technology.

PubMed

Grant, Richard John; Roberts, Karen; Pointon, Carly; Hodgson, Clare; Womersley, Lynsey; Jones, Darren Craig; Tang, Eric

2009-06-01

Compound handling is a fundamental and critical step in compound screening throughout the drug discovery process. Although most compound-handling processes within compound management facilities use 100% DMSO solvent, conventional methods of manual or robotic liquid-handling systems in screening workflows often perform dilutions in aqueous solutions to maintain solvent tolerance of the biological assay. However, the use of aqueous media in these applications can lead to suboptimal data quality due to compound carryover or precipitation during the dilution steps. In cell-based assays, this effect is worsened by the unpredictable physical characteristics of compounds and the low DMSO tolerance within the assay. In some cases, the conventional approaches using manual or automated liquid handling resulted in variable IC(50) dose responses. This study examines the cause of this variability and evaluates the accuracy of screening data in these case studies. A number of liquid-handling options have been explored to address the issues and establish a generic compound-handling workflow to support cell-based screening across our screening functions. The authors discuss the validation of the Labcyte Echo reformatter as an effective noncontact solution for generic compound-handling applications against diverse compound classes using triple-quad liquid chromatography/mass spectrometry. The successful validation and implementation challenges of this technology for direct dosing onto cells in cell-based screening is discussed.

The effect of plasma on shear bond strength between resin cement and colored zirconia

PubMed Central

2017-01-01

PURPOSE To investigate the effect of non-thermal atmospheric pressure plasma (NTAPP) treatment on shear bond strength (SBS) between resin cement and colored zirconia made with metal chlorides. MATERIALS AND METHODS 60 zirconia specimens were divided into 3 groups using coloring liquid. Each group was divided again into 2 sub-groups using plasma treatment; the experimental group was treated with plasma, and the control group was untreated. The sub-groups were: N (non-colored), C (0.1 wt% aqueous chromium chloride solution), M (0.1 wt% aqueous molybdenum chloride solution), NP (non-colored with plasma), CP (0.1 wt% aqueous chromium chloride solution with plasma), and MP (0.1 wt% aqueous molybdenum chloride solution with plasma). Composite resin cylinders were bonded to zirconia specimens with MDP-based resin cement, and SBS was measured using a universal testing machine. All data was analyzed statistically using a 2-way ANOVA test and a Tukey test. RESULTS SBS significantly increased when specimens were treated with NTAPP regardless of coloring (P<.001). Colored zirconia containing molybdenum showed the highest value of SBS, regardless of NTAPP. The molybdenum group showed the highest SBS, whereas the chromium group showed the lowest. CONCLUSION NTAPP may increase the SBS of colored zirconia and resin cement. The NTAPP effect on SBS is not influenced by the presence of zirconia coloring. PMID:28435621

Chain Conformation of Phosphorycholine-based Zwitterionic Polymer Brushes in Aqueous Solutions

NASA Astrophysics Data System (ADS)

Mao, Jun; Yu, Jing; Lee, Sungsik; Yuan, Guangcui; Satija, Sushil; Chen, Wei; Tirrell, Matthew

Polyzwitterionic brushes are resistant to nonspecific accumulation of proteins and microorganisms, making them excellent candidates for antifouling applications. It is well-known that polyzwitterions exhibit the so-called antipolyelectrolyte effect: Polyzwitterionic brushes would adopt a collapsed conformation at a low ionic strength due to the electrostatic inter/intra-chain association; whereas at a high ionic strength, they would exhibit an extended conformation because the electrostatic inter/intra-chain dipole-dipole interaction is weakened. However, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) is a unique member in polyzwitterionic families. Its ultrahigh affinity to water leads to no detectable shrinks in aqueous solutions even at low ionic strengths. In this study, we synthesized highly dense PMPC brushes via surface initiated radical polymerization and systematically investigate their conformational behaviors at solid-liquid interfaces in the presence of multivalent counterions, combining X-ray and neutron scattering and force measurements. We have demonstrated that despite no obvious changes of the entire lengths of extended PMPC brushes in aqueous solutions, the chain conformations including, but not limited to, polyzwitterion distribution and charge correlation, varied, dependent on salt types, ionic strengths and ion valences.

Note: A novel technique for analysis of aqueous solutions by laser-induced breakdown spectroscopy

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

Rusak, D. A.; Bell, Z. T.; Anthony, T. P.

2015-11-15

Surface-enhanced Raman spectroscopy (SERS) substrates typically consist of gold or silver nanoparticles deposited on a non-conductive substrate. In Raman spectroscopy, the nanoparticles produce an enhancement of the electromagnetic field which, in turn, leads to greater electronic excitation of molecules in the local environment. Here, we show that these same surfaces can be used to enhance the signal-to-noise ratio obtained in laser-induced breakdown spectroscopy of aqueous solutions. In this case, the SERS substrates not only lower breakdown thresholds and lead to more efficient plasma initiation but also provide an appropriately wettable surface for the deposition of the liquid. We refer tomore » this technique as surface-enhanced laser-induced breakdown spectroscopy.« less

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

Roscioli-Johnson, Kristyn M.; Zarzana, Christopher A.; Groenewold, Gary S.

In this paper, solutions of N,N-didodecyl-N',N'-dioctyldiglycolamide in n-dodecane were subjected to γ-irradiation in the presence and absence of both an aqueous nitric acid phase and air sparging. The solutions were analyzed using ultra-high-performance liquid chromatography-electrospray ionization-mass spectrometry (UHPLC-ESI-MS) to determine the rates of radiolytic decay of the extractant as well as to identify radiolysis products. The DGA concentration decreased exponentially with increasing dose, and the measured degradation rate constants were uninfluenced by the presence or absence of acidic aqueous phase, or by air sparging. Finally, the identified radiolysis products suggest that the bonds most vulnerable to radiolytic attack are thosemore » in the diglycolamide center of these molecules and not in the side chains.« less

Fundamental Characteristics of Bioprint on Calcium Alginate Gel

NASA Astrophysics Data System (ADS)

Umezu, Shinjiro; Hatta, Tatsuru; Ohmori, Hitoshi

2013-05-01

The goal of this study is to fabricate precision three-dimensional (3D) biodevices those are micro fluidics and artificial organs utilizing digital fabrication. Digital fabrication is fabrication method utilizing inkjet technologies. Electrostatic inkjet is one of the inkjet technologies. The electrostatic inkjet method has following two merits; those are high resolution to print and ability to eject highly viscous liquid. These characteristics are suitable to print biomaterials precisely. We are now applying for bioprint. In this paper, the electrostatic inkjet method is applied for fabrication of 3D biodevices that has cave like blood vessel. When aqueous solution of sodium alginate is printed to aqueous solution of calcium chloride, calcium alginate is produced. 3D biodevices are fabricated in case that calcium alginate is piled.

Initial stages of aggregation in aqueous solutions of ionic liquids: molecular dynamics studies.

PubMed

Bhargava, B L; Klein, Michael L

2009-07-16

Structures formed by 1-alkyl-3-methylimidazolium bromide aqueous solutions with decyl, dodecyl, tetradecyl, and hexadecyl chains have been studied using molecular dynamics (MD) simulations. Spontaneous self-assembly of the amphiphilic cations to form quasi-spherical polydisperse aggregates has been observed in all of the systems, with the size and nature of the aggregates varying with chain length. In all systems, the cation alkyl tails are buried deep inside the aggregates with the polar imidazolium group exposed to exploit the favorable interactions with water. Aggregation numbers steadily increase with the chain length. The hexadecyl aggregates have the most ordered internal structure of the systems studied, and the alkyl chains in these cations show the least number of gauche defects.

Chemical fate and changes in mutagenic activity of antibiotics nitrofurazone and furazolidone during aqueous chlorination.

PubMed

Nakamura, Hitomi; Kawakami, Tsuyoshi; Niino, Tatsuhiro; Takahashi, Yasuo; Onodera, Sukeo

2008-12-01

Reactions of nitrofuran antibiotics (nitrofurazone (NFZ) and frazolidone (FZD)) with hypochlorite in aqueous solution were investigated under the conditions that simulate wastewater disinfection. The chlorination byproducts were determined by high performance liquid chromatography. At the levels of 5 microM, NFZ reacted rapidly with free chlorine in neutral pH (7.0), while the FZD-hypochlorite reaction was reasonably slow under the same pH. Nevertheless, the strong mutagenic parents disappeared completely after the hypochlorite reactions, and the chlorination byproducts were observed to exert a weak mutagenic effect on Salmonella typhimurium TA100 without S9-mix. The extent of the reactions depended on the chlorine dose, solution pH and compound structures.

Removal of uranium (VI) from aqueous systems by nanoscale zero-valent iron particles suspended in carboxy-methyl cellulose

NASA Astrophysics Data System (ADS)

Popescu (Hoştuc), Ioana-Carmen; Filip, Petru; Humelnicu, Doina; Humelnicu, Ionel; Scott, Thomas Bligh; Crane, Richard Andrew

2013-11-01

Carboxy-methyl-cellulose (CMC), a common "delivery vehicle" for the subsurface deployment of iron nanoparticles (INP) has been tested in the current work for the removal of aqueous uranium from synthetic water samples. A comparison of the removal of aqueous uranium from solutions using carboxy-methyl-cellulose with and without iron nanoparticles (CMC-INP and CMC, respectively) was tested over a 48 h reaction period. Analysis of liquid samples using spectrophotometry determined a maximum sorption capacity of uranium, Qmax, of 185.18 mg/g and 322.58 mg/g for CMC and CMC-INP respectively, providing strong evidence of an independent aqueous uranium removal ability exhibited by CMC. The results point out that CMC provides an additional capacity for aqueous uranium removal. Further tests are required to determine whether similar behaviour will be observed for other aqueous contaminant species and if the presence of CMC within a INP slurry inhibits or aids the reactivity, reductive capacity and affinity of INP for aqueous contaminant removal.

Enhanced removal of NAPL constituent from aquifer during surfactant flushing with aqueous hydraulic barriers of high viscosity.

PubMed

Ahn, Dayoung; Choi, Jae-Kyeong; Kim, Heonki

2017-06-07

This study examines the effect of controlled groundwater flow paths induced by hydraulic barriers on the removal of NAPL constituent. An aqueous solution of thickener [0.05% (w/v) sodium carboxymethyl cellulose, SCMC] was continuously injected into a horizontally set two-dimensional physical model (sand-packed), forming aqueous plume(s) of high viscosity. The water flux at the down gradient of the model was measured using a flux tracer (n-octanol) and passive flux meter (PFM, packs of granular activated carbon). A non-reactive tracer (pentafluorobenzoic acid, PFBA) was used to identify the plume of high viscosity (hydraulic barrier) and ambient groundwater. When the barrier of high viscosity was formed, the plume was separated from the background water with little mixing, which was confirmed by the concentration profile of PFBA; whereas, the measured flux of ambient groundwater showed a distinctive distribution, due to the hydraulic barrier. When two barriers were set, the ambient water flux was enhanced in the middle, and the removal rate of PCE from the non-aqueous phase liquid (NAPL), measured by PFM, was found to improve by 26% during three hours of water flushing. When an aqueous solution of surfactant [0.37% (w/v), sodium dodecyl sulfate, SDS] was applied instead of water into the domain with two barriers set around the NAPL-contaminated spot, the removal of PCE from the NAPL increased by 101% for a three-hour time period. Based on the observations made in this study, hydraulic barriers formed by continuous injection of thickener solution change the flow direction of groundwater, and may increase the flux of groundwater (or aqueous solution of remediation agent) through a NAPL-contaminated region, improving the removal of NAPL.

In situ study of mass transfer in aqueous solutions under high pressures via Raman spectroscopy: A new method for the determination of diffusion coefficients of methane in water near hydrate formation conditions

USGS Publications Warehouse

Lu, W.J.; Chou, I.-Ming; Burruss, R.C.; Yang, M.Z.

2006-01-01

A new method was developed for in situ study of the diffusive transfer of methane in aqueous solution under high pressures near hydrate formation conditions within an optical capillary cell. Time-dependent Raman spectra of the solution at several different spots along the one-dimensional diffusion path were collected and thus the varying composition profile of the solution was monitored. Diffusion coefficients were estimated by the least squares method based on the variations in methane concentration data in space and time in the cell. The measured diffusion coefficients of methane in water at the liquid (L)-vapor (V) stable region and L-V metastable region are close to previously reported values determined at lower pressure and similar temperature. This in situ monitoring method was demonstrated to be suitable for the study of mass transfer in aqueous solution under high pressure and at various temperature conditions and will be applied to the study of nucleation and dissolution kinetics of methane hydrate in a hydrate-water system where the interaction of methane and water would be more complicated than that presented here for the L-V metastable condition. ?? 2006 Society for Applied Spectroscopy.

A new solution to emulsion liquid membrane problems by non-Newtonian conversion

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

Skelland, A.H.P.; Meng, X.

1996-02-01

Surfactant-stabilized emulsion liquid membrane processes constitute an emerging separation technology that has repeatedly been shown to be highly suited for such diverse separation processes as metal recovery or removal from dilute aqueous solutions; separations in the food industry; removal of organic bases and acids from water; and separation of hydrocarbons. Emulsion liquid membrane separation processes remain excessively vulnerable to one or more of four major problems. Difficulties lie in developing liquid membranes that combine high levels of both stability and permeability with acceptably low levels of swelling and ease of subsequent demulsification for membrane and solute recovery. This article providesmore » a new technique for simultaneously overcoming the first three problems, while identifying physical indications that the proposed solution may have little adverse effect on the fourth problem (demulsification) and may even alleviate it. Numerous benefits of optimized conversion of the membrane phase into suitable non-Newtonian form are identified, their mechanisms outlined, and experimental verifications provided. These include increased stability, retained (or enhanced) permeability, reduced swelling, increased internal phase volume, and increased stirrer speeds. The highly favorable responsiveness of both aliphatic and aromatic membranes to the new technique is demonstrated.« less

Method and apparatus for destroying organic contaminants in aqueous liquids

DOEpatents

Donaldson, T.L.; Wilson, J.H.

1993-09-21

A method and apparatus for destroying organic contaminants, such as trichloroethylene, in aqueous liquids, such as groundwater, utilizing steam stripping integrated with biodegradation. The contaminated aqueous liquid is fed into a steam stripper causing the volatilization of essentially all of the organic contaminants and a portion of the aqueous liquid. The majority of the aqueous liquid is discharged from the steam stripper. The volatilized vapors are then condensed to the liquid phase and introduced into a bioreactor. The bioreactor contains methanotrophic microorganisms which convert the organic contaminants into mainly carbon dioxide. The effluent from the bioreactor is then recycled back to the steam stripper for further processing. 2 figures.

Method and apparatus for destroying organic contaminants in aqueous liquids

DOEpatents

Donaldson, Terrence L.; Wilson, James H.

1993-01-01

A method and apparatus for destroying organic contaminants, such as trichloroethylene, in aqueous liquids, such as groundwater, utilizing steam stripping integrated with biodegradation. The contaminated aqueous liquid is fed into a steam stripper causing the volatilization of essentially all of the organic contaminants and a portion of the aqueous liquid. The majority of the aqueous liquid is discharged from the steam stripper. The volatilized vapors are then condensed to the liquid phase and introduced into a bioreactor. The bioreactor contains methanotrophic microorganisms which convert the organic contaminants into mainly carbon dioxide. The effluent from the bioreactor is then recycled back to the steam stripper for further processing.

Electroresponsive Aqueous Silk Protein As “Smart” Mechanical Damping Fluid

PubMed Central

2015-01-01

Here we demonstrate the effectiveness of an electroresponsive aqueous silk protein polymer as a smart mechanical damping fluid. The aqueous polymer solution is liquid under ambient conditions, but is reversibly converted into a gel once subjected to an electric current, thereby increasing or decreasing in viscosity. This nontoxic, biodegradable, reversible, edible fluid also bonds to device surfaces and is demonstrated to reduce friction and provide striking wear protection. The friction and mechanical damping coefficients are shown to modulate with electric field exposure time and/or intensity. Damping coefficient can be modulated electrically, and then preserved without continued power for longer time scales than conventional “smart” fluid dampers. PMID:24750065

Foaming volume and foam stability

NASA Technical Reports Server (NTRS)

Ross, Sydney

1947-01-01

A method of measuring foaming volume is described and investigated to establish the critical factors in its operation. Data on foaming volumes and foam stabilities are given for a series of hydrocarbons and for a range of concentrations of aqueous ethylene-glycol solutions. It is shown that the amount of foam formed depends on the machinery of its production as well as on properties of the liquid, whereas the stability of the foam produced, within specified mechanical limitations, is primarily a function of the liquid.

Time- and angle-resolved photoemission spectroscopy of hydrated electrons near a liquid water surface.

PubMed

Yamamoto, Yo-ichi; Suzuki, Yoshi-Ichi; Tomasello, Gaia; Horio, Takuya; Karashima, Shutaro; Mitríc, Roland; Suzuki, Toshinori

2014-05-09

We present time- and angle-resolved photoemission spectroscopy of trapped electrons near liquid surfaces. Photoemission from the ground state of a hydrated electron at 260 nm is found to be isotropic, while anisotropic photoemission is observed for the excited states of 1,4-diazabicyclo[2,2,2]octane and I- in aqueous solutions. Our results indicate that surface and subsurface species create hydrated electrons in the bulk side. No signature of a surface-bound electron has been observed.

Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma.

PubMed

Ask, Kristine Skoglund; Bardakci, Turgay; Parmer, Marthe Petrine; Halvorsen, Trine Grønhaug; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig; Gjelstad, Astrid

2016-09-10

Generic Parallel Artificial Liquid Membrane Extraction (PALME) methods for non-polar basic and non-polar acidic drugs from human plasma were investigated with respect to phospholipid removal. In both cases, extractions in 96-well format were performed from plasma (125μL), through 4μL organic solvent used as supported liquid membranes (SLMs), and into 50μL aqueous acceptor solutions. The acceptor solutions were subsequently analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using in-source fragmentation and monitoring the m/z 184→184 transition for investigation of phosphatidylcholines (PC), sphingomyelins (SM), and lysophosphatidylcholines (Lyso-PC). In both generic methods, no phospholipids were detected in the acceptor solutions. Thus, PALME appeared to be highly efficient for phospholipid removal. To further support this, qualitative (post-column infusion) and quantitative matrix effects were investigated with fluoxetine, fluvoxamine, and quetiapine as model analytes. No signs of matrix effects were observed. Finally, PALME was evaluated for the aforementioned drug substances, and data were in accordance with European Medicines Agency (EMA) guidelines. Copyright © 2016 Elsevier B.V. All rights reserved.

Coarsening of firefighting foams containing fluorinated hydrocarbon surfactants

NASA Astrophysics Data System (ADS)

Kennedy, Matthew J.; Dougherty, John A.; Otto, Nicholas; Conroy, Michael W.; Williams, Bradley A.; Ananth, Ramagopal; Fleming, James W.

2013-03-01

Diffusion of gas between bubbles in foam causes growth of large bubbles at the expense of small bubbles and leads to increasing mean bubble size with time thereby affecting drainage. Experimental data shows that the effective diffusivity of nitrogen gas in aqueous film forming foam (AFFF), which is widely used in firefighting against burning liquids, is several times smaller than in 1% sodium dodecyl sulfate (SDS) foam based on time-series photographs of bubble size and weighing scale recordings of liquid drainage. Differences in foam structure arising from foam production might contribute to the apparent difference in the rates of coarsening. AFFF solution produces wetter foam with initially smaller bubbles than SDS solution due in part to the lower gas-liquid surface tension provided by the fluorosurfactants present in AFFF. Present method of foam production generates microbubble foam by high-speed co-injection of surfactant solution and gas into a tube of 3-mm diameter. These results contribute to our growing understanding of the coupling between foam liquid fraction, bubble size, surfactant chemistry, and coarsening. NRC Resident Research Associate at NRL

Electrokinetic migration across artificial liquid membranes Tuning the membrane chemistry to different types of drug substances.

PubMed

Gjelstad, Astrid; Rasmussen, Knut Einar; Pedersen-Bjergaard, Stig

2006-08-18

Twenty different basic drugs were electrokinetically extracted across a thin artificial organic liquid membrane with a 300 V d.c. electrical potential difference as the driving force. From a 300 microl aqueous sample (acidified corresponding to 10mM HCl), the drugs were extracted for 5 min through a 200 microm artificial liquid membrane of a water immiscible organic solvent immobilized in the pores of a polypropylene hollow fiber, and into a 30 microl aqueous acceptor solution of 10mM HCl inside the lumen of the hollow fiber. Hydrophobic basic drugs (logP>1.7) were effectively isolated utilizing 2-nitrophenyl octyl ether (NPOE) as the artificial liquid membrane, with recoveries up to 83%. For more hydrophilic basic drugs (logP<1.0), a mixture of NPOE and 25% (w/w) di-(2-ethylhexyl) phosphate (DEHP) was required to ensure efficient extraction, resulting in recoveries up to 75%. DEHP was expected to act as an ion-pair reagent ion-pairing the protonated hydrophilic drugs at the interface between the sample and the membrane, resulting in permeation of the interface.

Towards High-Performance Aqueous Sodium-Ion Batteries: Stabilizing the Solid/Liquid Interface for NASICON-Type Na2 VTi(PO4 )3 using Concentrated Electrolytes.

PubMed

Zhang, Huang; Jeong, Sangsik; Qin, Bingsheng; Vieira Carvalho, Diogo; Buchholz, Daniel; Passerini, Stefano

2018-04-25

Aqueous Na-ion batteries may offer a solution to the cost and safety issues of high-energy batteries. However, substantial challenges remain in the development of electrode materials and electrolytes enabling high performance and long cycle life. Herein, we report the characterization of a symmetric Na-ion battery with a NASICON-type Na 2 VTi(PO 4 ) 3 electrode material in conventional aqueous and "water-in-salt" electrolytes. Extremely stable cycling performance for 1000 cycles at a high rate (20 C) is found with the highly concentrated aqueous electrolytes owing to the formation of a resistive but protective interphase between the electrode and electrolyte. These results provide important insight for the development of aqueous Na-ion batteries with stable long-term cycling performance for large-scale energy storage. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid Vapor Stripping-Vapor Permeation Process for Recovery and Dehydration of 1-Butanol and Acetone/Butanol/Ethanol from Dilute Aqueous Solutions. Part 1. Process Simulations

EPA Science Inventory

BACKGROUND: Fermentative production of butanol is limited to low concentrations, typically less than 2 wt% solvent, due to product inhibition. The result is high separation energy demand by conventional distillation approaches, despite favorable vapor-liquid equilibrium and parti...

46 CFR 151.50-23 - Phosphoric acid.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions of...

46 CFR 151.50-23 - Phosphoric acid.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions of...

Enhanced Amendment Delivery to Subsurface Using Shear Thinning Fluid and Aqueous Foam for Metal, Radionuclide, and NAPL Remediation

NASA Astrophysics Data System (ADS)

Zhong, L.; Szecsody, J.; Li, X.; Oostrom, M.; Truex, M.

2010-12-01

In many contamination sites, removal of contaminants by any active remediation efforts is not practical due to the high cost and technological limitations. Alternatively, in situ remediation is expected to be the most important remediation strategy. Delivery of reactive amendment to the contamination zone is essential for the reactions between the contaminants and remedial amendments to proceed in situ. It is a challenge to effectively deliver remedial amendment to the subsurface contamination source areas in both aquifer and vadose zone. In aquifer, heterogeneity induces fluid bypassing the low-permeability zones, resulting in certain contaminated areas inaccessible to the remedial amendment delivered by water injection, thus inhibiting the success of remedial operations. In vadose zone in situ remediation, conventional solution injection and infiltration for amendment delivery have difficulties to achieve successful lateral spreading and uniform distribution of the reactive media. These approaches also tend to displace highly mobile metal and radionuclide contaminants such as hexavalent chromium [Cr(VI)] and technetium (Tc-99), causing spreading of contaminations. Shear thinning fluid and aqueous foam can be applied to enhance the amendment delivery and improve in situ subsurface remediation efficiency under aquifer and vadose zone conditions, respectively. Column and 2-D flow cell experiments were conducted to demonstrate the enhanced delivery and improved remediation achieved by the application of shear thinning fluid and foam injection at the laboratory scale. Solutions of biopolymer xanthan gum were used as the shear thinning delivering fluids. Surfactant sodium lauryl ether sulfate (STEOL CS-330) was the foaming agent. The shear thinning fluid delivery (STFD) considerably improved the sweeping efficiency over a heterogeneous system and enhanced the non-aqueous liquid phase (NAPL) removal. The delivery of amendment into low-perm zones (LPZs) by STFD also increased the persistence of amendment solution in the LPZs after injection. Immobilization of Tc-99 was improved when a reductant was delivered by foam versus by water-based solution to contaminated vadose zone sediments. Foam delivery remarkably improved the lateral distribution of fluids compared to direct liquid injection. In heterogeneous vadose zone formation, foam injection increased the liquid flow in the high permeable zones into which very limited fluid was distributed during liquid infiltration, demonstrating improved amendment distribution uniformity in the heterogeneous system by foam delivery.

Effect of surfactant on kinetics of thinning of capillary bridges

NASA Astrophysics Data System (ADS)

Nowak, Emilia; Kovalchuk, Nina; Simmons, Mark

2015-11-01

Kinetics of thinning of capillary bridges is of great scientific and industrial interest being of vital importance for example in various emulsification and microfluidic processes. It is well known that the rate of bridge thinning is proportional to the interfacial tension. Therefore it is expected that the process should slow down by addition of surfactant. The kinetics of capillary bridges in the presence of surfactant was studied by the dripping of liquid from a capillary tip under conditions of nearly zero flow rate (We << 1). The tested liquids were aqueous solutions of sodium lauryl ether sulphate (SLES), which is broadly used in personal care products. The viscosity, surfactant activity and adsorption kinetics have been controlled by addition of glycerol and sodium chloride. The study has shown that the kinetics of capillary bridges are determined by dynamic surface tension rather than by its equilibrium value. In particular, the kinetics of the bridge thinning for the 0.1 g L-1 aqueous SLES solution is practically the same as that of pure water despite twice lower equilibrium surface tension. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

Complex Behavior of Aqueous α-Cyclodextrin Solutions. Interfacial Morphologies Resulting from Bulk Aggregation.

PubMed

Hernandez-Pascacio, Jorge; Piñeiro, Ángel; Ruso, Juan M; Hassan, Natalia; Campbell, Richard A; Campos-Terán, José; Costas, Miguel

2016-07-05

The spontaneous aggregation of α-cyclodextrin (α-CD) molecules in the bulk aqueous solution and the interactions of the resulting aggregates at the liquid/air interface have been studied at 283 K using a battery of techniques: transmission electron microscopy, dynamic light scattering, dynamic surface tensiometry, Brewster angle microscopy, neutron reflectometry, and ellipsometry. We show that α-CD molecules spontaneously form aggregates in the bulk that grow in size with time. These aggregates adsorb to the liquid/air interface with their size in the bulk determining the adsorption rate. The material that reaches the interface coalesces laterally to form two-dimensional domains on the micrometer scale with a layer thickness on the nanometer scale. These processes are affected by the ages of both the bulk and the interface. The interfacial layer formed is not in fast dynamic equilibrium with the subphase as the resulting morphology is locked in a kinetically trapped state. These results reveal a surprising complexity of the parallel physical processes taking place in the bulk and at the interface of what might have seemed initially like a simple system.

Solvent effects on the polar network of ionic liquid solutions

NASA Astrophysics Data System (ADS)

Bernardes, Carlos E. S.; Shimizu, Karina; Canongia Lopes, José N.

2015-05-01

Molecular dynamics simulations were used to probe mixtures of ionic liquids (ILs) with common molecular solvents. Four types of systems were considered: (i) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide plus benzene, hexafluorobenzene or 1,2-difluorobenzene mixtures; (ii) choline-based ILs plus ether mixtures (iii) choline-based ILs plus n-alkanol mixtures; and (iv) 1-butyl-3-methylimidazolium nitrate and 1-ethyl-3-methylimidazolium ethyl sulfate aqueous mixtures. The results produced a wealth of structural and aggregation information that highlight the resilience of the polar network of the ILs (formed by clusters of alternating ions and counter-ions) to the addition of different types of molecular solvent. The analysis of the MD data also shows that the intricate balance between different types of interaction (electrostatic, van der Waals, H-bond-like) between the different species present in the mixtures has a profound effect on the morphology of the mixtures at a mesoscopic scale. In the case of the IL aqueous solutions, the present results suggest an alternative interpretation for very recently published x-ray and neutron diffraction data on similar systems.

Adsorption of gentian violet dyes in aqueous solution on microporous AlPOs molecular sieves synthesized by ionothermal method

NASA Astrophysics Data System (ADS)

Fortas, W.; Djelad, A.; Hasnaoui, M. A.; Sassi, M.; Bengueddach, A.

2018-02-01

In this work, AlPO-34, like-chabazite (CHA) zeolite, was ionothermally prepared using the ionic liquid (IL), 1-ethyl-3-methylimidazolium chloride [EMIMCl], as solvent. The solids obtained were characterized by x-ray powder diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FTIR), thermal analysis (TG) and nitrogen adsorption/desorption at 77.3 K. The results show that the ionic liquid is occluded in the AlPO-34 framework and consequently it acts also as a structure-directing agent. The variation of chemical composition led to AlPO-34 materials with different crystal sizes and morphologies. The well crystallized AlPO-34 material was used as adsorbent for Crystal Violet (CV) dye removal from aqueous solutions. The effect of adsorption parameters such as pH and initial concentration were investigated. It was found that adsorption dyes is favorable at pH = 6. The adsorption isotherm data follow the Langmuir equation in which parameters are calculated. The selected AlPO-34 sample exhibited a high crystal violet dye removal of 46.08 mg g-1 at pH = 6.

Iron oxide and hydroxide precipitation from ferrous solutions and its relevance to Martian surface mineralogy

NASA Technical Reports Server (NTRS)

Posey-Dowty, J.; Moskowitz, B.; Crerar, D.; Hargraves, R.; Tanenbaum, L.

1986-01-01

Experiments were performed to examine if the ubiquitousness of a weak magnetic component in all Martian surface fines tested with the Viking Landers can be attributed to ferric iron precipitation in aqueous solution under oxidizing conditions at neutral pH. Ferrous solutions were mixed in deionized water and various minerals were added to separate liquid samples. The iron-bearing additives included hematite, goethite, magnetite, maghemite, lepidocrocite and potassium bromide blank at varying concentrations. IR spectroscopic scans were made to identify any precipitates resulting from bubbling oxygen throughout the solutions; the magnetic properties of the precipitates were also examined. The data indicated that the lepidocrocite may have been preferentially precipitated, then aged to maghemite. The process would account for the presumed thin residue of maghemite on the present Martian surface, long after abundant liquid water on the Martian surface vanished.

Magnetomigration of rare-earth ions in inhomogeneous magnetic fields.

PubMed

Franczak, Agnieszka; Binnemans, Koen; Jan Fransaer

2016-10-05

The effects of external inhomogenous (gradient) magnetic fields on the movement of the rare-earth ions: Dy 3+ , Gd 3+ and Y 3+ , in initially homogeneous aqueous solutions have been investigated. Differences in the migration of rare-earth ions in gradient magnetic fields were observed, depending on the magnetic character of the ions: paramagnetic ions of Dy 3+ and Gd 3+ move towards regions of the sample where the magnetic field gradient is the strongest, while diamagnetic ions of Y 3+ move in the opposite direction. It has been showed that the low magnetic field gradients, such the ones generated by permanent magnets, are sufficient to observe the magnetomigration effects of the ions in solution. The present work clearly establishes the behavior of magnetically different ions in initially homogeneous aqueous solutions exposed to magnetic field gradients. To this avail, a methodology for measuring the local concentration differences of metal ions in liquid samples was developed.

SEPARATION OF AMERICIUM FROM PROMETHIUM

DOEpatents

Pressly, R.E.

1959-07-01

Promethium-147 is separated from americium in acidic aqueous solution by adding fluosilicic acid to the solution, heating the solution to form a promethium precipitate and separating the precipitate from solution. The precipitate is then re-dissolved by ihe addition of boric acid and nitric acid, and re-precipitated by the addition of fluosilicic acid. This procedure is repeated six or more times to obtain a relatively americium-free promeihium precipitate. Americium may be separately recovered from the supernatant liquids. This process is applicable to the recovery of promethium from fission-product solutions which have been allowed to decay for a period of two to four years.

A new tunable dispersive liquid-liquid micro extraction method developed for the simultaneous preconcentration of lead and cadmium from lakes water: a multivariate study

NASA Astrophysics Data System (ADS)

Bilal, Muhammad; Kazi, Tasneem Gul; Afridi, Hassan Imran; Ali, Jamshed; Baig, Jameel Ahmed; Arain, Mohammad Balal; Khan, Mustafa

2017-08-01

A green tunable dispersive liquid-liquid micro extraction (TDLLME) technique was established for the simultaneous enrichment of lead (Pb) and cadmium (Cd) from different lakes water before analysis by flame atomic absorption spectrometry (FAAS). A solvent known as tunable polarity solvent (TPS), mixture of 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and 1-decanol, has been employed as extractant in aqueous medium. In first step this mixture can be made polar by slowly bubbling the antisolvent trigger (CO2) through the solution, which makes a monophasic solution. During this step hydrophobic complexes of the metals with 8-hydroxy quinoline (8-HQ) were extracted by TPS. Then the mixture was switched back to hydrophobic one by heating and/or bubbling nitrogen, turning the mixture into two phases again. In second phase the metals were leached out from the complexes entrapped in TPS, by treating with a solution of nitric acid and exposing the mixture to CO2, which switched the mixture into single phase. Then N2 purging and/or heating again turned the mixture into two phases. The acidic aqueous phase containing the metals was introduced to FAAS for analysis, whereas TPS was recycled for next experiment. Different parameters, affecting the efficiency the technique, were optimized by multivariate approach. The method was applied to certified reference material of water and to a real sample spiked with standards of known concentration, to confirm its validity and accuracy. LOD obtained for Pb and Cd were 0.560 and 0.056 μg L- 1 respectively. The developed method was applied successfully to the real water samples of two lakes of Sindh, Pakistan.

Degradation of aqueous phenol solutions by coaxial DBD reactor

NASA Astrophysics Data System (ADS)

Dojcinovic, B. P.; Manojlovic, D.; Roglic, G. M.; Obradovic, B. M.; Kuraica, M. M.; Puric, J.

2008-07-01

Solutions of 2-chlorophenol, 4-chlorophenol and 2,6-dichlorophenol in bidistilled and water from the river Danube were treated in plasma reactor. In this reactor, based on coaxial dielectric barrier discharge at atmospheric pressure, plasma is formed over a thin layer of treated water. After one pass through the reactor, starting chlorophenols concentration of 20 mg/l was diminished up to 95 %. Kinetics of the chlorophenols degradation was monitored by High Pressure Liquid Chromatography method (HPLC).

Self-aggregation of bio-surfactants within ionic liquid 1-ethyl-3-methylimidazolium bromide: A comparative study and potential application in antidepressants drug aggregation.

PubMed

Banjare, Manoj Kumar; Behera, Kamalakanta; Kurrey, Ramsingh; Banjare, Ramesh Kumar; Satnami, Manmohan L; Pandey, Siddharth; Ghosh, Kallol K

2018-06-15

Aggregation behavior of bio-surfactants (BS) sodium cholate (NaC) and sodium deoxycholate (NaDC) within aqueous solution of ionic liquid (IL) 1-ethyl-3-methylimidazolium bromide [Emim][Br] has been investigated using surface tension, conductivity, steady state fluorescence, FT-IR and dynamic light scattering (DLS) techniques. Various interfacial and thermodynamic parameters are determined in the presence of different wt% of IL [Emim][Br]. Information regarding the local microenvironment and size of the aggregates is obtained from fluorescence and DLS, respectively. FT-IR spectral response is used to reveal the interactions taking place within aqueous NaC/NaDC micellar solutions. It is noteworthy to mention that increasing wt% of [Emim][Br] results in an increase in the spontaneity of micelle formation and the hydrophilic IL shows more affinity for NaC as compared to NaDC. Further, the micellar solutions of BS-[Emim][Br] are utilized for studying the aggregation of antidepressants drug promazine hydrochloride (pH). UV-vis spectroscopic investigation reveals interesting outcomes and the results show changes in spectral absorbance of PH drug on the addition of micellar solution (BS-[Emim][Br]). Highest binding affinity and most promising activity are shown for NaC as compared to NaDC. Copyright © 2018 Elsevier B.V. All rights reserved.

Engineering ionic liquid-tolerant cellulases for biofuels production.

PubMed

Wolski, Paul W; Dana, Craig M; Clark, Douglas S; Blanch, Harvey W

2016-04-01

Dissolution of lignocellulosic biomass in certain ionic liquids (ILs) can provide an effective pretreatment prior to enzymatic saccharification of cellulose for biofuels production. Toward the goal of combining pretreatment and enzymatic hydrolysis, we evolved enzyme variants of Talaromyces emersonii Cel7A to be more active and stable than wild-type T. emersonii Cel7A or Trichoderma reesei Cel7A in aqueous-IL solutions (up to 43% (w/w) 1,3-dimethylimdazolium dimethylphosphate and 20% (w/w) 1-ethyl-3-methylimidazolium acetate). In general, greater enzyme stability in buffer at elevated temperature corresponded to greater stability in aqueous-ILs. Post-translational modification of the N-terminal glutamine residue to pyroglutamate via glutaminyl cyclase enhanced the stability of T. emersonii Cel7A and variants. Differential scanning calorimetry revealed an increase in melting temperature of 1.9-3.9°C for the variant 1M10 over the wild-type T. emersonii Cel7A in aqueous buffer and in an IL-aqueous mixture. We observed this increase both with and without glutaminyl cyclase treatment of the enzymes. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Electrochemical ion transfer across liquid/liquid interfaces confined within solid-state micropore arrays--simulations and experiments.

PubMed

Strutwolf, Jörg; Scanlon, Micheál D; Arrigan, Damien W M

2009-01-01

Miniaturised liquid/liquid interfaces provide benefits for bioanalytical detection with electrochemical methods. In this work, microporous silicon membranes which can be used for interface miniaturisation were characterized by simulations and experiments. The microporous membranes possessed hexagonal arrays of pores with radii between 10 and 25 microm, a pore depth of 100 microm and pore centre-to-centre separations between 99 and 986 microm. Cyclic voltammetry was used to monitor ion transfer across arrays of micro-interfaces between two immiscible electrolyte solutions (microITIES) formed at these membranes, with the organic phase present as an organogel. The results were compared to computational simulations taking into account mass transport by diffusion and encompassing diffusion to recessed interfaces and overlapped diffusion zones. The simulation and experimental data were both consistent with the situation where the location of the liquid/liquid (l/l) interface was on the aqueous side of the silicon membrane and the pores were filled with the organic phase. While the current for the forward potential scan (transfer of the ion from the aqueous phase to the organic phase) was strongly dependent on the location of the l/l interface, the current peak during the reverse scan (transfer of the ion from the organic phase to the aqueous phase) was influenced by the ratio of the transferring ion's diffusion coefficients in both phases. The diffusion coefficient of the transferring ion in the gelified organic phase was ca. nine times smaller than in the aqueous phase. Asymmetric cyclic voltammogram shapes were caused by the combined effect of non-symmetrical diffusion (spherical and linear) and by the inequality of the diffusion coefficient in both phases. Overlapping diffusion zones were responsible for the observation of current peaks instead of steady-state currents during the forward scan. The characterisation of the diffusion behaviour is an important requirement for application of these silicon membranes in electroanalytical chemistry.

Generation and characterization of ultrathin free-flowing liquid sheets

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

Koralek, Jake D.; Kim, Jongjin B.; Bruza, Petr

The physics and chemistry of liquid solutions play a central role in science, and our understanding of life on Earth. Unfortunately, key tools for interrogating aqueous systems, such as infrared and soft X-ray spectroscopy, cannot readily be applied because of strong absorption in water. Here we use gas-dynamic forces to generate free-flowing, sub-micron, liquid sheets which are two orders of magnitude thinner than anything previously reported. Optical, infrared, and X-ray spectroscopies are used to characterize the sheets, which are found to be tunable in thickness from over 1 μm down to less than 20 nm, which corresponds to fewer thanmore » 100 water molecules thick. At this thickness, aqueous sheets can readily transmit photons across the spectrum, leading to potentially transformative applications in infrared, X-ray, electron spectroscopies and beyond. Lastly, the ultrathin sheets are stable for days in vacuum, and we demonstrate their use at free-electron laser and synchrotron light sources.« less

Aqueous ionic liquids and their effects on protein structures: an overview on recent theoretical and experimental results

NASA Astrophysics Data System (ADS)

Smiatek, Jens

2017-06-01

Ionic liquids (ILs) are used in a variety of technological and biological applications. Recent experimental and simulation results reveal the influence of aqueous ionic liquids on the stability of protein and enzyme structures. Depending on different parameters like the concentration and the ion composition, one can observe distinct stabilization or denaturation mechanisms for various ILs. In this review, we summarize the main findings and discuss the implications with regard to molecular theories of solutions and specific ion effects. A preferential binding model is introduced in order to discuss protein-IL effects from a statistical mechanics perspective. The value of the preferential binding coefficient determines the strength of the ion influence and indicates a shift of the chemical equilibrium either to the native or the denatured state of the protein. We highlight the role of water in order to explain the self-association behavior of the IL species and discuss recent experimental and simulation results in the light of the observed binding effects.

Generation and characterization of ultrathin free-flowing liquid sheets

DOE PAGES

Koralek, Jake D.; Kim, Jongjin B.; Bruza, Petr; ...

2018-04-10

The physics and chemistry of liquid solutions play a central role in science, and our understanding of life on Earth. Unfortunately, key tools for interrogating aqueous systems, such as infrared and soft X-ray spectroscopy, cannot readily be applied because of strong absorption in water. Here we use gas-dynamic forces to generate free-flowing, sub-micron, liquid sheets which are two orders of magnitude thinner than anything previously reported. Optical, infrared, and X-ray spectroscopies are used to characterize the sheets, which are found to be tunable in thickness from over 1 μm down to less than 20 nm, which corresponds to fewer thanmore » 100 water molecules thick. At this thickness, aqueous sheets can readily transmit photons across the spectrum, leading to potentially transformative applications in infrared, X-ray, electron spectroscopies and beyond. Lastly, the ultrathin sheets are stable for days in vacuum, and we demonstrate their use at free-electron laser and synchrotron light sources.« 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.

Photochemical degradation of the carbapenem antibiotics imipenem and meropenem in aqueous solutions under solar radiation.

PubMed

Reina, Alejandro Cabrera; Martínez-Piernas, Ana B; Bertakis, Yannis; Brebou, Christina; Xekoukoulotakis, Nikolaos P; Agüera, Ana; Sánchez Pérez, José Antonio

2018-01-01

This paper deals with the photochemical fate of two representative carbapenem antibiotics, namely imipenem and meropenem, in aqueous solutions under solar radiation. The analytical method employed for the determination of the target compounds in various aqueous matrices, such as ultrapure water, municipal wastewater treatment plant effluents, and river water, at environmentally relevant concentrations, was liquid chromatography coupled with hybrid triple quadrupole-linear ion trap-mass spectrometry. The absorption spectra of both compounds were measured in aqueous solutions at pH values from 6 to 8, and both compounds showed a rather strong absorption band centered at about 300 nm, while their molar absorption coefficient was in the order from 9 × 10 3 -10 4  L mol -1  cm -1 . The kinetics of the photochemical degradation of the target compounds was studied in aqueous solutions under natural solar radiation in a solar reactor with compound parabolic collectors. It was found that the photochemical degradation of both compounds at environmentally relevant concentrations follows first order kinetics and the quantum yield was in the order of 10 -3  mol einsten -1 . Several parameters were studied, such as solution pH, the presence of nitrate ions and humic acids, and the effect of water matrix. In all cases, it was found that the presence of various organic and inorganic constituents in the aqueous matrices do not contribute significantly, either positively or negatively, to the photochemical degradation of both compounds under natural solar radiation. In a final set of photolysis experiments, the effect of the level of irradiance was studied under simulated solar radiation and it was found that the quantum yield for the direct photodegradation of both compounds remained practically constant by changing the incident solar irradiance from 28 to 50 W m -2 . Copyright © 2017 Elsevier Ltd. All rights reserved.

On-line coupling of counter-current chromatography and macroporous resin chromatography for continuous isolation of arctiin from the fruit of Arctium lappa L.

PubMed

Guo, Mengzhe; Liang, Junling; Wu, Shihua

2010-08-13

In this work, we have developed a novel hybrid two-dimensional counter-current chromatography and liquid chromatography (2D CCC x LC) system for the continuous purification of arctiin from crude extract of Arctium lappa. The first dimensional CCC column has been designed to fractionalize crude complex extract into pure arctiin effluent using a one-component organic/salt-containing system, and the second dimensional LC column has been packed with macroporous resin for on-line adsorption, desalination and desorption of arctiin which was effluent purified from the first CCC dimension. Thus, the crude arctiin mixture has been purified efficiently and conveniently by on-line CCC x LC in spite of the use of a salt-containing solvent system in CCC separation. As a result, high purity (more than 97%) of arctiin has been isolated by repeated injections both using the ethyl acetate-8% sodium chloride aqueous solution and butanol-1% sodium chloride aqueous solution. By contrast with the traditional CCC processes using multi-component organic/aqueous solvent systems, the present on-line CCC x LC process only used a one-component organic solvent and thus the solvent is easier to recover and regenerate. All of used solvents such as ethyl acetate, n-butanol and NaCl aqueous solution are low toxicity and environment-friendly. Moreover, the lower phase of salt-containing aqueous solution used as mobile phase, only contained minor organic solvent, which will save much organic solvent in continuous separation. In summary, our results indicated that the on-line hybrid 2D CCC x LC system using one-component organic/salt-containing aqueous solution is very promising and powerful tool for high-throughput purification of arctiin from fruits of A. lappa. 2010 Elsevier B.V. All rights reserved.

Experimental confirmation of liquid brines on Mars

NASA Astrophysics Data System (ADS)

Fischer, E.; Renno, N. O.; Martinez, G.

2015-12-01

The discovery of water ice and perchlorates in the shallow subsurface of Mars [1,2] is interesting because they could produce aqueous liquid solutions under Mars' present-day environmental conditions. We used the Michigan Mars Environmental Chamber [3] to simulate the pressure, temperature and relative humidity during the full diurnal cycle of sol 19 at the Phoenix landing site. Sol 19 was chosen because on this sol ice found in a shallow trench (Dodo-Goldilocks) at a depth of ~5 cm was removed with little effort [4], suggesting that it was a frozen brine (softer than freshwater ice), and because oblate spheroids found on a strut of the lander, possibly a saline mud, were observed to grow and darken (suggesting liquefaction) [4]. The results of our simulations show that early in the mission the frozen brine likely found in the Dodo-Goldilocks trench could melt in the morning, temporarily forming aqueous liquid solutions when the temperature in the trench was above the eutectic temperature of the Ca(ClO4)2 salt (~199 K). In addition, the results of our simulations indicate that the spheroids observed on a strut of the Phoenix lander were most likely droplets of liquid brines. Since halophilic terrestrial bacteria thrive in brines [5], our results suggest that Mars' polar region could potentially be a habitat for microorganisms. In addition, it has been suggested that frost could form on fine-grained terrains at Gale crater during the winter [6]. If this frost gets in contact with perchlorate salts, it could melt temporarily forming liquid brines.

Effect of Rheological Properties on Liquid Curtain Coating

NASA Astrophysics Data System (ADS)

Mohammad Karim, Alireza; Suszynski, Wieslaw; Griffith, William; Pujari, Saswati; Carvalho, Marcio; Francis, Lorraine; Dow Chemical Company Collaboration; PUC-Rio Collaboration

2017-11-01

Curtain coating is one of the preferred methods for high-speed precision application of single-layer and multi-layer coatings in technology. However, uniform coatings are only obtained in a certain range of operating parameters, called coating window. The two main physical mechanisms that limit successful curtain coating are liquid curtain breakup and air entrainment. The rheological properties of the liquid play an important role on these mechanisms, but the fundamental understanding of these relations is still not complete. The effect of rate-dependent shear and extensional viscosities on the stability of viscoelastic and shear thinning liquid curtains were explored by high-speed visualization. Aqueous solutions of polyethylene oxide (PEO) and polyethylene glycol (PEG) were used as viscoelastic liquids. Xanthan Gum in water and glycerol solutions with a range of compositions were used as shear thinning liquids. The critical condition was determined by examining flow rate below which curtain broke. In this work, we also analyze relative importance of rate-dependent shear and extensional viscosity on both curtain breakup and air entrainment. We would like to acknowledge the financial support from the Dow Chemical Company.

Sonochemical and photosonochemical degradation of 4-chlorophenol in aqueous media.

PubMed

Hamdaoui, Oualid; Naffrechoux, Emmanuel

2008-09-01

The degradation of 4-chlorophenol (4-CP) in aqueous media by 516 kHz ultrasonic irradiation was investigated in order to clarify the degradation mechanism. The degradation of concentrated 4-CP solution by means of ultrasound, UV irradiation and their combined application was also studied. The obtained results indicate that *OH radical are the primary reactive species responsible for 4-CP ultrasonic degradation. Very little 4-CP degradation occurs if the sonolysis is carried out in the presence of the *OH radical scavenger tert-butyl alcohol, also indicating that little or no pyrolysis of the compound occurs. The dominant degradation mechanism is the reaction of substrate with *OH radicals at the gas bubble-liquid interface rather than high temperature direct pyrolysis in ultrasonic cavities. This mechanism can explain the lower degradation rate of the ionic form of 4-CP that is partly due to the rapid dissociation of *OH radicals in alkaline solutions. The sonochemical destruction of concentrated 4-CP aqueous solution is obtained with low rate. Coupling photolysis with ultrasound irradiation results in increased efficiency compared to the individual processes operating at common conditions. Interestingly, the photosonochemical decomposition rate constant is greater than the additive rate constants of the two processes. This may be the result of three different oxidative processes direct photochemical action, high frequency sonochemistry and reaction with ozone produced by UV irradiation of air, dissolved in liquid phase because of the geyser effect of ultrasound streaming. Additionally, the photodecomposition, at 254 nm, of hydrogen peroxide produced by ultrasound generating *OH radical can partly explain the destruction enhancement.

Atmospheric pressure laser desorption/ionization using a 6-7 µm-band mid-infrared tunable laser and liquid water matrix.

PubMed

Hiraguchi, Ryuji; Hazama, Hisanao; Masuda, Katsuyoshi; Awazu, Kunio

2015-01-01

Due to the characteristic absorption peaks in the IR region, various molecules can be used as a matrix for infrared matrix-assisted laser desorption/ionization (IR-MALDI). Especially in the 6-7 µm-band IR region, solvents used as the mobile phase for liquid chromatography have absorption peaks that correspond to their functional groups, such as O-H, C=O, and CH3. Additionally, atmospheric pressure (AP) IR-MALDI, which is applicable to liquid-state samples, is a promising technique to directly analyze untreated samples. Herein we perform AP-IR-MALDI mass spectrometry of a peptide, angiotensin II, using a mid-IR tunable laser with a tunable wavelength range of 5.50-10.00 µm and several different matrices. The wavelength dependences of the ion signal intensity of [M + H](+) of the peptide are measured using a conventional solid matrix, α-cyano-4-hydroxycinnamic acid (CHCA) and a liquid matrix composed of CHCA and 3-aminoquinoline. Other than the O-H stretching and bending vibration modes, the characteristic absorption peaks are useful for AP-IR-MALDI. Peptide ions are also observed from an aqueous solution of the peptide without an additional matrix, and the highest peak intensity of [M + H](+) is at 6.00 µm, which is somewhat shorter than the absorption peak wavelength of liquid water corresponding to the O-H bending vibration mode. Moreover, long-lasting and stable ion signals are obtained from the aqueous solution. AP-IR-MALDI using a 6-7 µm-band IR tunable laser and solvents as the matrix may provide a novel on-line interface between liquid chromatography and mass spectrometry. Copyright © 2015 John Wiley & Sons, Ltd.

Process for removing sulfate anions from waste water

DOEpatents

Nilsen, David N.; Galvan, Gloria J.; Hundley, Gary L.; Wright, John B.

1997-01-01

A liquid emulsion membrane process for removing sulfate anions from waste water is disclosed. The liquid emulsion membrane process includes the steps of: (a) providing a liquid emulsion formed from an aqueous strip solution and an organic phase that contains an extractant capable of removing sulfate anions from waste water; (b) dispersing the liquid emulsion in globule form into a quantity of waste water containing sulfate anions to allow the organic phase in each globule of the emulsion to extract and absorb sulfate anions from the waste water and (c) separating the emulsion including its organic phase and absorbed sulfate anions from the waste water to provide waste water containing substantially no sulfate anions.

Formation of liquid water at low temperatures via the deliquescence of calcium chloride: Implications for Antarctica and Mars

NASA Astrophysics Data System (ADS)

Gough, R. V.; Chevrier, V. F.; Tolbert, M. A.

2016-10-01

There is significant interest in the potential existence of even small amounts of liquid brine on current Mars. It has been proposed that aqueous solutions could form on Mars via the deliquescence of hygroscopic salts in contact with atmospheric water vapor, and these hygroscopic salts have recently been detected in recurring slope linae (RSL). While past work has largely focused on perchlorate species, another Mars-relevant salt that has a low eutectic temperature and may be deliquescent is calcium chloride, CaCl2. This salt may be linked to RSL formation on Mars, and deliquescence of CaCl2 is also known to be responsible for the only terrestrial RSL analog features known thus far: water tracks in the McMurdo Dry Valleys. Here we use Raman microscopy to monitor the low-temperature (223-273 K) deliquescence (solid to aqueous phase transition) and efflorescence (aqueous to solid phase transition) of two hydration states of CaCl2, the dihydrate and the hexahydrate. We find the deliquescence relative humidity (DRH) decreases with decreasing hydration state and with increasing temperature. Average DRH values over the temperature range studied are 15.8±3.5% RH for the dihydrate and 63.3±12.5% RH for the hexahydrate, making this salt at least as deliquescent as many perchlorate salts. A remarkable property of CaCl2 is its ability to persist as metastable, supersaturated brine. Once an aqueous solution was formed, efflorescence (recrystallization) of the liquid did not occur until single-digit RH values were reached (3.9±2.4% RH on average). We show that temperature and relative humidity conditions in the martian subsurface are sufficient to allow deliquescence of CaCl2, and the resulting brines may persist for over half of a martian sol. Therefore, this salt could play a role in RSL formation, the martian water cycle, and have implications for the potential habitability of Mars.

Capillary liquid chromatography combined with pressurized liquid extraction and dispersive liquid-liquid microextraction for the determination of vitamin E in cosmetic products.

PubMed

Viñas, Pilar; Pastor-Belda, Marta; Campillo, Natalia; Bravo-Bravo, María; Hernández-Córdoba, Manuel

2014-06-01

Capillary liquid chromatography (LC) is used for the determination of tocopherols and tocotrienols in cosmetic products. Dispersive liquid-liquid microextraction (DLLME) allows the analytes to be preconcentrated into a very small volume of organic solvent which is then injected into the chromatograph running at a very low flow rate. Pressurized liquid extraction (PLE) at a high temperature and pressure was used to isolate vitamin E forms from cosmetics. The Taguchi experimental method was used to optimize the factors affecting DLLME. The parameters selected were 2mL of acetonitrile (disperser solvent), 100μL carbon tetrachloride (extraction solvent) and 10mL aqueous solution. A volume of 5μL of the organic phase was injected into the reversed-phase capillary LC system equipped with a diode array detector and using an isocratic mobile phase composed of an 95:5 (v/v) methanol:water mixture at a flow-rate of 20μLmin(-1). Quantification was carried out using aqueous standards and detection limits were in the range 0.1-0.5ngmL(-1), corresponding to 3-15ngg(-1) in the cosmetic sample. The recoveries were in the 87-105% range, with RSDs lower than 7.8%. The method was validated according to international guidelines and using a certified reference material. Copyright © 2014 Elsevier B.V. All rights reserved.

Surrogate immiscible liquid pairs with refractive indexes matchable over a wide range of density and viscosity ratios

NASA Astrophysics Data System (ADS)

Saksena, Rajat; Christensen, Kenneth T.; Pearlstein, Arne J.

2015-08-01

In liquid-liquid flows, use of optical diagnostics is limited by interphase refractive index mismatch, which leads to optical distortion and complicates data interpretation, and sometimes also by opacity. Both problems can be eliminated using a surrogate pair of immiscible index-matched transparent liquids, whose density and viscosity ratios match corresponding ratios for the original liquid pair. We show that a wide range of density and viscosity ratios is accessible using aqueous solutions of 1,2-propanediol and CsBr (for which index, density, and viscosity are available), and solutions of light and heavy silicone oils and 1-bromooctane (for which we measured the same properties at 119 compositions). For each liquid phase, polynomials in the composition variables, least-squares fitted to index and density and to the logarithm of kinematic viscosity, were used to determine accessible density and viscosity ratios for each matchable index. Index-matched solution pairs can be prepared with density and viscosity ratios equal to those for water-liquid CO2 at 0 °C over a range of pressure (allowing water-liquid CO2 behavior at inconveniently high pressure to be simulated by 1-bar experiments), and for water-crude oil and water-trichloroethylene (avoiding opacity and toxicity problems, respectively), each over a range of temperature. For representative index-matched solutions, equilibration changes index, density, and viscosity only slightly, and mass spectrometry and elemental analysis show that no component of either phase has significant interphase solubility. Finally, procedures are described for iteratively reducing the residual index mismatch in surrogate solution pairs prepared on the basis of approximate polynomial fits to experimental data, and for systematically dealing with nonzero interphase solubility.

Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System

PubMed Central

Hoogerstraete, Tom Vander; Onghena, Bieke; Binnemans, Koen

2013-01-01

Several fundamental extraction parameters such as the kinetics and loading were studied for a new type of metal solvent extraction system with ionic liquids. The binary mixture of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water shows thermomorphic behavior with an upper critical solution temperature (UCST), which can be used to avoid the slower mass transfer due to the generally higher viscosity of ionic liquids. A less viscous homogeneous phase and mixing on a molecular scale are obtained when the mixture is heated up above 55 °C. The influence of the temperature, the heating and cooling times, were studied for the extraction of neodymium(III) with betaine. A plausible and equal extraction mechanism is proposed in bis(trifluoromethylsulfonyl)imide, nitrate, and chloride media. After stripping of the metals from the ionic liquid phase, a higher recovery of the ionic liquid was obtained by salting-out of the ionic liquid fraction lost by dissolution in the aqueous phase. The change of the upper critical solution temperature by the addition of HCl or betaine was investigated. In addition, the viscosity was measured below and above the UCST as a function of the temperature. PMID:24169434

Dilute and Semidilute Solutions of a Nonionic, Rigid, Water-soluble Polymer

NASA Astrophysics Data System (ADS)

Russo, Paul; Huberty, Wayne; Zhang, Donghui; Water-Soluble Rodlike Polymer Team Collaboration

2014-03-01

The solution physics of random polymer chains was established largely on the behavior of commercial polymers such as polystyrene for organic solvents or nonionic poly(ethyleneoxide) for aqueous solvents. Not only are these materials widely available for industrial use, they can be synthesized to be essentially monodisperse. When it comes to stiff polymers, good choices are few and less prone to be used in industrial applications. Much was learned from polypeptides such as poly(benzylglutamate) or poly(stearylglutamate) in polar organic solvents and nonpolar organic solvents, respectively, but aqueous systems generally require charge. Poly(Nɛ-2-[2-(2-Methoxyethoxy) ethoxy]acetyl-L-Lysine) a.k.a. PEGL was pioneered by Deming and coworkers. In principle, PEGL provides a convenient platform from which to study stiff polymer behavior--phase relations, dynamics, liquid crystal formation and gelation--all with good molecular weight control and uniformity and without electrical charge. Still, a large gap in knowledge exists between PEGL and traditional rodlike polymer systems. To narrow this gap, dynamic and static scattering, circular dichroism, and viscosity measurements have been made in dilute and semidilute solutions as necessary preliminaries for lyotropic liquid crystalline and gel phases. Supported by NSF DMR 1306262. Department of Chemistry and Macromolecular Studies Group. Current address: Georgia Institute of Technology, School of Materials Science and Engineering.

Steady-state solidification of aqueous ammonium chloride

NASA Astrophysics Data System (ADS)

Peppin, S. S. L.; Huppert, Herbert E.; Worster, M. Grae

We report on a series of experiments in which a Hele-Shaw cell containing aqueous solutions of NH4Cl was translated at prescribed rates through a steady temperature gradient. The salt formed the primary solid phase of a mushy layer as the solution solidified, with the salt-depleted residual fluid driving buoyancy-driven convection and the development of chimneys in the mushy layer. Depending on the operating conditions, several morphological transitions occurred. A regime diagram is presented quantifying these transitions as a function of freezing rate and the initial concentration of the solution. In general, for a given concentration, increasing the freezing rate caused the steady-state system to change from a convecting mushy layer with chimneys to a non-convecting mushy layer below a relatively quiescent liquid, and then to a much thinner mushy layer separated from the liquid by a region of active secondary nucleation. At higher initial concentrations the second of these states did not occur. At lower concentrations, but still above the eutectic, the mushy layer disappeared. A simple mathematical model of the system is developed which compares well with the experimental measurements of the intermediate, non-convecting state and serves as a benchmark against which to understand some of the effects of convection. Movies are available with the online version of the paper.

Structure, stability and behaviour of nucleic acids in ionic liquids

PubMed Central

Tateishi-Karimata, Hisae; Sugimoto, Naoki

2014-01-01

Nucleic acids have become a powerful tool in nanotechnology because of their conformational polymorphism. However, lack of a medium in which nucleic acid structures exhibit long-term stability has been a bottleneck. Ionic liquids (ILs) are potential solvents in the nanotechnology field. Hydrated ILs, such as choline dihydrogen phosphate (choline dhp) and deep eutectic solvent (DES) prepared from choline chloride and urea, are ‘green’ solvents that ensure long-term stability of biomolecules. An understanding of the behaviour of nucleic acids in hydrated ILs is necessary for developing DNA materials. We here review current knowledge about the structures and stabilities of nucleic acids in choline dhp and DES. Interestingly, in choline dhp, A–T base pairs are more stable than G–C base pairs, the reverse of the situation in buffered NaCl solution. Moreover, DNA triplex formation is markedly stabilized in hydrated ILs compared with aqueous solution. In choline dhp, the stability of Hoogsteen base pairs is comparable to that of Watson–Crick base pairs. Moreover, the parallel form of the G-quadruplex is stabilized in DES compared with aqueous solution. The behaviours of various DNA molecules in ILs detailed here should be useful for designing oligonucleotides for the development of nanomaterials and nanodevices. PMID:25013178

Subsurface solute transport with one-, two-, and three-dimensional arbitrary shape sources

NASA Astrophysics Data System (ADS)

Chen, Kewei; Zhan, Hongbin; Zhou, Renjie

2016-07-01

Solutions with one-, two-, and three-dimensional arbitrary shape source geometries will be very helpful tools for investigating a variety of contaminant transport problems in the geological media. This study proposed a general method to develop new solutions for solute transport in a saturated, homogeneous aquifer (confined or unconfined) with a constant, unilateral groundwater flow velocity. Several typical source geometries, such as arbitrary line sources, vertical and horizontal patch sources, circular and volumetric sources, were considered. The sources can sit on the upper or lower aquifer boundary to simulate light non-aqueous-phase-liquids (LNAPLs) or dense non-aqueous-phase-liquids (DNAPLs), respectively, or can be located anywhere inside the aquifer. The developed new solutions were tested against previous benchmark solutions under special circumstances and were shown to be robust and accurate. Such solutions can also be used as a starting point for the inverse problem of source zone and source geometry identification in the future. The following findings can be obtained from analyzing the solutions. The source geometry, including shape and orientation, generally played an important role for the concentration profile through the entire transport process. When comparing the inclined line sources with the horizontal line sources, the concentration contours expanded considerably along the vertical direction, and shrank considerably along the groundwater flow direction. A planar source sitting on the upper aquifer boundary (such as a LNAPL pool) would lead to significantly different concentration profiles compared to a planar source positioned in a vertical plane perpendicular to the flow direction. For a volumetric source, its dimension along the groundwater flow direction became less important compared to its other two dimensions.

Effect of water and ionic liquids on biomolecules.

PubMed

Saha, Debasis; Mukherjee, Arnab

2018-02-08

The remarkable progress in the field of ionic liquids (ILs) in the last two decades has involved investigations on different aspects of ILs in various conditions. The nontoxic and biocompatible nature of ILs makes them a suitable substance for the storage and application of biomolecules. In this regard, the aqueous IL solutions have attracted a large number of studies to comprehend the role of water in modulating various properties of biomolecules. Here, we review some of the recent studies on aqueous ILs that concern the role of water in altering the behavior of ILs in general and in case of biomolecules solvated in ILs. The different structural and dynamic effects caused by water have been highlighted. We discuss the different modes of IL interaction that are responsible for stabilization and destabilization of proteins and enzymes followed by examples of water effect on this. The role of water in the case of nucleic acid storage in ILs, an area which has mostly been underrated, also has been emphasized. Our discussions highlight the fact that the effects of water on IL behavior are not general and are highly dependent on the nature of the IL under consideration. Overall, we aim to draw attention to the significance of water dynamics in the aqueous IL solutions, a better understanding of which can help in developing superior storage materials for application purposes.

Anti-Adhesive Behaviors between Solid Hydrate and Liquid Aqueous Phase Induced by Hydrophobic Silica Nanoparticles.

PubMed

Min, Juwon; Baek, Seungjun; Somasundaran, P; Lee, Jae W

2016-09-20

This study introduces an "anti-adhesive force" at the interface of solid hydrate and liquid solution phases. The force was induced by the presence of hydrophobic silica nanoparticles or one of the common anti-agglomerants (AAs), sorbitan monolaurate (Span 20), at the interface. The anti-adhesive force, which is defined as the maximum pushing force that does not induce the formation of a capillary bridge between the cyclopentane (CP) hydrate particle and the aqueous solution, was measured using a microbalance. Both hydrophobic silica nanoparticles and Span 20 can inhibit adhesion between the CP hydrate probe and the aqueous phase because silica nanoparticles have an aggregative property at the interface, and Span 20 enables the hydrate surface to be wetted with oil. Adding water-soluble sodium dodecyl sulfate (SDS) to the nanoparticle system cannot affect the aggregative property or the distribution of silica nanoparticles at the interface and, thus, cannot change the anti-adhesive effect. However, the combined system of Span 20 and SDS dramatically reduces the interfacial tension: emulsion drops were formed at the interface without any energy input and were adsorbed on the CP hydrate surface, which can cause the growth of hydrate particles. Silica nanoparticles have a good anti-adhesive performance with a relatively smaller dosage and are less influenced by the presence of molecular surfactants; consequently, these nanoparticles may have a good potential for hydrate inhibition as AAs.

Impulsive Stimulated Light Scattering Studies of the Liquid-Glass Transition: on the Experimental Verification of Mode-Coupling Theory Predictions.

NASA Astrophysics Data System (ADS)

Halalay, Ion C.

A study of the structural glass transition trough impulsive stimulated light scattering experiments has been carried out in concentrated aqueous lithium chloride solutions, at temperatures ranging from ambient to cryogenic. A specially designed sample cell made it possible to cover the whole temperature interval from simple liquid, to viscoelastic supercooled liquid, to glass. It is shown that a phenomenological description of the results of these experiments in terms of a spectrum of relaxation times through the use of a Kohlrausch-Williams-Watts relaxation function is inadequate. Based on predictions of mode-coupling theory of the liquid-glass transition, an alternative approach to data interpretation is proposed. It is shown that for an aqueous lithium chloride solution, the prediction of simple scaling and identical scaling for mechanical and electrical susceptibilities seems to be valid. However, another prediction of theory is called into question: instead of a power-law behavior on temperature difference, it is found experimentally that the behavior of the susceptibility spectrum minimum is exponential. Similar disagreements are found for other two materials, triphenyl phosphite and polypropylene oxide. The causes for these discrepancies are discussed and it is concluded that additional experimentation is necessary to verify theoretical claims. Experiments are proposed which can test these predictions and serve as guide for the construction of theoretical models for the glass transition in real systems. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Improved procedure for determination of flucytosine in human blood plasma by high-pressure liquid chromatography.

PubMed Central

Schwertschlag, U; Nakata, L M; Gal, J

1984-01-01

Several high-pressure liquid chromatography procedures for the determination of flucytosine in serum or plasma have appeared. Some of these suffer from significant disadvantages, and none was applicable in our routine clinical therapeutic-drug-monitoring laboratory. A new high-pressure liquid chromatography assay for flucytosine was therefore developed. A 100-microliter sample of plasma was treated with an aqueous 5-iodocytosine internal-standard solution, and the mixture was deproteinized with trichloroacetic acid. A portion of the protein-free supernatant was diluted with 0.1 M ammonium phosphate, and an aliquot of the resulting solution was injected into the high-pressure liquid chromatography system. Chromatography was performed on a strong-cation-exchange column with a mobile phase containing aqueous ammonium phosphate, phosphoric acid, methanol, and acetonitrile. Detection was at 254 nm. The assay was shown to be linear in the 10 to 200-micrograms/ml drug-concentration range. Forty other drugs were tested for potential interference with the assay, and none was found. For routine use, a single-point working standard containing 75 micrograms of flucytosine per ml was used, giving intraassay coefficients of variation at 50 and 150 micrograms/ml of 1.8 and 2.3% respectively, whereas the day-to-day coefficient of variation at 50 micrograms/ml was 10.0%. Advantages of the procedure include the small sample size, the use of a convenient and reliable internal standard, speed, and simplicity. The assay is highly suitable for routine clinical drug-analysis laboratories. PMID:6508261

Flow drag and heat transfer characteristics of drag-reducing nanofluids with CuO nanoparticles

NASA Astrophysics Data System (ADS)

Wang, Ping-Yang; Wang, Xue-Jiao; Liu, Zhen-Hua

2017-02-01

A new kind of aqueous CuO nanofluid with drag-reducing performance was developed. The new working fluid was an aqueous CTAC (cetyltrimethyl ammonium chloride) solution with CuO nanoparticles added and has both special effects of drag-reducing and heat transfer enhancement. An experiment was carried out to investigate the forced convective flow and heat transfer characteristics of conventional drag reducing fluid (aqueous CTAC solution) and the new drag-reducing nanofluid in a test tube with an inner diameter of 25.6 mm. Results indicated that there were no obvious differences of the drag-reducing characteristics between conventional drag reducing fluid and new drag-reducing nanofluid. However, their heat transfer characteristics were obvious different. The heat transfer characteristics of the new drag-reducing nanofluid significantly depend on the liquid temperature, the nanoparticle concentration and the CTAC concentration. The heat transfer enhancement technology of nanofluid could be applied to solve the problem of heat transfer deterioration for conventional drag-reducing fluids.

A Carbon Dioxide Bubble-Induced Vortex Triggers Co-Assembly of Nanotubes with Controlled Chirality.

PubMed

Zhang, Ling; Zhou, Laicheng; Xu, Na; Ouyang, Zhenjie

2017-07-03

It is challenging to prepare co-organized nanotube systems with controlled nanoscale chirality in an aqueous liquid flow field. Such systems are responsive to a bubbled external gas. A liquid vortex induced by bubbling carbon dioxide (CO 2 ) gas was used to stimulate the formation of nanotubes with controlled chirality; two kinds of achiral cationic building blocks were co-assembled in aqueous solution. CO 2 -triggered nanotube formation occurs by formation of metastable intermediate structures (short helical ribbons and short tubules) and by transition from short tubules to long tubules in response to chirality matching self-assembly. Interestingly, the chirality sign of these assemblies can be selected for by the circulation direction of the CO 2 bubble-induced vortex during the co-assembly process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A microfluidic study of liquid-liquid extraction mediated by carbon dioxide.

PubMed

Lestari, Gabriella; Salari, Alinaghi; Abolhasani, Milad; Kumacheva, Eugenia

2016-07-05

Liquid-liquid extraction is an important separation and purification method; however, it faces a challenge in reducing the energy consumption and the environmental impact of solvent (extractant) recovery. The reversible chemical reactions of switchable solvents (nitrogenous bases) with carbon dioxide (CO2) can be implemented in reactive liquid-liquid extraction to significantly reduce the cost and energy requirements of solvent recovery. The development of new effective switchable solvents reacting with CO2 and the optimization of extraction conditions rely on the ability to evaluate and screen the performance of switchable solvents in extraction processes. We report a microfluidic strategy for time- and labour-efficient studies of CO2-mediated solvent extraction. The platform utilizes a liquid segment containing an aqueous extractant droplet and a droplet of a solution of a switchable solvent in a non-polar liquid, with gaseous CO2 supplied to the segment from both sides. Following the reaction of the switchable solvent with CO2, the solvent becomes hydrophilic and transfers from the non-polar solvent to the aqueous droplet. By monitoring the time-dependent variation in droplet volumes, we determined the efficiency and extraction time for the CO2-mediated extraction of different nitrogenous bases in a broad experimental parameter space. The platform enables a significant reduction in the amount of switchable solvents used in these studies, provides accurate temporal characterization of the liquid-liquid extraction process, and offers the capability of high-throughput screening of switchable solvents.

Analyses of factors affecting nickel ferrite nanoparticles synthesis in ultrasound-assisted aqueous solution ball milling.

PubMed

Yuan, Zhuang; Chen, Zhen-hua; Chen, Ding; Kang, Zhi-tao

2015-01-01

Ball milling experiments were conducted with and without ultrasound wave assistance in deionized water using NiCO3·2Ni(OH)2·4H2O as raw materials. In the reaction process of NiFe2O4 prepared by ultrasound-assisted aqueous solution ball milling, some influencing factors including raw materials, ultrasonic frequency, ball to powder ratio and liquid level were changed. Samples were characterized by X-ray diffraction, fluorescence measurements and electroconductivity detections. The results indicate that more hydroxyl radicals and ions can be generated under the coupling effect of ultrasonic and ball milling. The fluorescence measurements and electroconductivity detections also reflect the reaction speed, allowing for optimal parameters to be determined. Copyright © 2014 Elsevier B.V. All rights reserved.

Ionic depletion at the crystalline Gibbs layer of PEG-capped gold nanoparticle brushes at aqueous surfaces

NASA Astrophysics Data System (ADS)

Wang, Wenjie; Zhang, Honghu; Mallapragada, Surya; Travesset, Alex; Vaknin, David

2017-12-01

In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolated-polyethylene-glycol-capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs2SO4 ) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray scattering. By taking advantage of element specificity with the GIXFS method, we find that the cation Cs+ concentration at the crystalline film is significantly reduced in parts of the PEG-AuNP film compared with that in the bulk.

Determination of Gibbs energies of formation in aqueous solution using chemical engineering tools.

PubMed

Toure, Oumar; Dussap, Claude-Gilles

2016-08-01

Standard Gibbs energies of formation are of primary importance in the field of biothermodynamics. In the absence of any directly measured values, thermodynamic calculations are required to determine the missing data. For several biochemical species, this study shows that the knowledge of the standard Gibbs energy of formation of the pure compounds (in the gaseous, solid or liquid states) enables to determine the corresponding standard Gibbs energies of formation in aqueous solutions. To do so, using chemical engineering tools (thermodynamic tables and a model enabling to predict activity coefficients, solvation Gibbs energies and pKa data), it becomes possible to determine the partial chemical potential of neutral and charged components in real metabolic conditions, even in concentrated mixtures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Application of fluorescent dyes for some problems of bioelectromagnetics

NASA Astrophysics Data System (ADS)

Babich, Danylo; Kylsky, Alexandr; Pobiedina, Valentina; Yakunov, Andrey

2016-04-01

Fluorescent organic dyes solutions are used for non-contact measurement of the millimeter wave absorption in liquids simulating biological tissue. There is still not any certain idea of the physical mechanism describing this process despite the widespread technology of microwave radiation in the food industry, biotechnology and medicine. For creating adequate physical model one requires an accurate command of knowledge concerning to the relation between millimeter waves and irradiated object. There were three H-bonded liquids selected as the samples with different coefficients of absorption in the millimeter range like water (strong absorption), glycerol (medium absorption) and ethylene glycol (light absorption). The measurements showed that the greatest response to the action of microwaves occurs for glycerol solutions: R6G (building-up luminescence) and RC (fading luminescence). For aqueous solutions the signal is lower due to lower quantum efficiency of luminescence, and for ethylene glycol — due to the low absorption of microwaves. In the area of exposure a local increase of temperature was estimated. For aqueous solutions of both dyes the maximum temperature increase is about 7° C caused with millimeter waves absorption, which coincides with the direct radio physical measurements and confirmed by theoretical calculations. However, for glycerol solution R6G temperature equivalent for building-up luminescence is around 9° C, and for the solution of ethylene glycol it's about 15°. It is assumed the possibility of non-thermal effect of microwaves on the different processes and substances. The application of this non-contact temperature sensing is a simple and novel method to detect temperature change in small biological objects.

Dynamics of water in LiCl and CaCl 2 aqueous solutions confined in silica matrices: A backscattering neutron spectroscopy study

NASA Astrophysics Data System (ADS)

Mamontov, E.; Cole, D. R.; Dai, S.; Pawel, M. D.; Liang, C. D.; Jenkins, T.; Gasparovic, G.; Kintzel, E.

2008-09-01

Backscattering neutron spectroscopy was used to probe the dynamics of water molecules in LiCl and CaCl 2 aqueous solutions confined in 2.7, 1.9, and 1.4 nm diameter pores of various silica matrices. The pore size of 2.7 nm was found to be sufficiently large for the confined liquids to exhibit characteristic traits of bulk behavior, such as a freezing-melting transition and a phase separation. On the other hand, none of the fluids in the 1.4 nm pores exhibited a clear freezing-melting transition; instead, their dynamics at low temperatures gradually became too slow for the nanosecond resolution of the experiment. The greatest suppression of water mobility was observed in the CaCl 2 solutions, which suggests that cation charge and perhaps the cation hydration environment have a profound influence on the dynamics of the water molecules. Quasielastic neutron scattering measurements of pure H 2O and 1 m LiCl-H 2O solution confined in 1.9 nm pores revealed a dynamic transition in both liquids at practically the same temperature of 225-226 K, even though the dynamics of the solution at room temperature appeared to slow down by more than an order of magnitude compared to the pure water. The observation of the dynamic transition in the solution suggests that this transition may be a universal feature of water governed by processes acting on the local scale, such as a change in the hydrogen bonding.

Perrhenate complexation by uranyl in traditional solvents and in ionic liquids: a joint molecular dynamics/spectroscopic study.

PubMed

Chaumont, Alain; Klimchuk, Olga; Gaillard, Clotilde; Billard, Isabelle; Ouadi, Ali; Hennig, Christoph; Wipff, Georges

2012-03-15

The complexation of perrhenate (ReO(4)(-)) anions by the uranyl (UO(2)(2+)) cation has been investigated by joint molecular dynamics simulations and spectroscopic (UV-vis, TRLFS, and EXAFS) studies in aqueous solution, acetonitrile, and three ionic liquids (ILs), namely, [Bmi][Tf(2)N], [Me(3)BuN][Tf(2)N], and [Bu(3)MeN][Tf(2)N] that are based on the same Tf(2)N(-) anion (bis(trifluoromethylsulfonyl)imide) and either Bmi(+) (1-butyl,3-methylimidazolium), Me(3)BuN(+), or Bu(3)MeN(+) cations. They show that ReO(4)(-) behaves as a weak ligand in aqueous solution and as a strong ligand in acetonitrile and in the ILs. According to MD simulations in aqueous solution, the UO(2)(ReO(4))(2) complex quickly dissociates to form UO(2)(H(2)O)(5)(2+), while in acetonitrile, a stable UO(2)(ReO(4))(5)(3-) species forms from dissociated ions. In the ILs, the UO(2)(ReO(4))(n)(2-n) complexes (n = 1 to 5) remained stable along the dynamics, and to assess their relative stabilities, we computed the free energy profiles for stepwise ReO(4)(-) complexation to uranyl. In the two studied ILs, complexation is favored, leading to the UO(2)(ReO(4))(5)(3-) species in [Bmi][Tf(2)N] and to UO(2)(ReO(4))(4)(2-) in [Bu(3)MeN][Tf(2)N]. Furthermore, in both acetonitrile and [Bmi][Tf(2)N] solutions, MD and PMF simulations support the formation of dimeric uranyl complexes [UO(2)(ReO(4))(4)](2)(4-) with two bridging ReO(4)(-) ligands. The simulation results are qualitatively consistent with spectroscopic observations in the different solvents, without firmly concluding, however, on the precise composition and structure of the complexes in the solutions. © 2012 American Chemical Society

Polysaccharide-thickened aqueous fluoride solutions for rapid destruction of the nerve agent VX. Introducing the opportunity for extensive decontamination scenarios.

PubMed

Elias, Shlomi; Saphier, Sigal; Columbus, Ishay; Zafrani, Yossi

2014-01-01

Among the chemical warfare agents, the extremely toxic nerve agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) is a target of high importance in the development of decontamination methods, due to its indefinite persistence on common environmental surfaces. Liquid decontaminants are mostly characterized by high corrosivity, usually offer poor coverage, and tend to flow and accumulate in low areas. Therefore, the development of a noncorrosive decontaminant, sufficiently viscous to resist dripping from the contaminated surface, is necessary. In the present paper we studied different polysaccharides-thickened fluoride aqueous solutions as noncorrosive decontaminants for rapid and efficient VX degradation to the nontoxic product EMPA (ethyl methylphosphonic acid). Polysaccharides are environmentally benign, natural, and inexpensive. Other known decontaminants cannot be thickened by polysaccharides, due to the sensitivity of the latter toward basic or oxidizing agents. We found that the efficiency of VX degradation in these viscous solutions in terms of kinetics and product identity is similar to that of KF aqueous solutions. Guar gum (1.5 wt %) with 4 wt % KF was chosen for further evaluation. The benign nature, rheological properties, adhering capabilities to different surfaces, and decontamination from a porous matrix were examined. This formulation showed promising properties for implementation as a spray decontaminant for common and sensitive environmental surfaces.

Surface Charge Effects on the Electro-Orientation of Insulating Nanotubes in Aqueous Electrolytes

NASA Astrophysics Data System (ADS)

Cetindag, Semih; Tiwari, Bishnu; Zhang, Dongyan; Yap, Yoke Khin; Kim, Sangil; Shan, Jerry W.

2017-11-01

While the alignment of electrically conductive nanowires and nanotubes by electric fields in liquid solution has been well studied, much less is known about the electro-orientation of insulating 1D particles, such as boron-nitride nanotubes (BNNTs). Here, we demonstrate for the first time the electro-orientation of individual insulating BNNTs in aqueous KCl solutions under AC fields. Comparison to theory indicates that the observed frequency response is not related to the crossover for Maxwell-Wagner interfacial polarization. Instead, the cross-over frequency in the low-frequency regime scales as the square root of solution conductivity, indicating that alignment is associated with the formation and motion of an electrical double layer (EDL), much like induced-charge electro-osmosis for a conducting particle. However, the mechanism for the formation of the EDL is presumably different for insulating particles like BNNTs as compared to conductors. By varying the surface charge of the particle by changing pH, we show that the alignment rate increases with increasing surface charge, and is likely a result of counter-ion migration and EDL polarization under the influence of applied electric field. Thus, particle surface charge (large Dukhin number) is believed to play a vital role in the electro-orientation of insulating particles in aqueous solutions. NSF CBET-1604931 and NSF DMR-1261910.

Displacement-dispersive liquid-liquid microextraction based on solidification of floating organic drop of trace amounts of palladium in water and road dust samples prior to graphite furnace atomic absorption spectrometry determination.

PubMed

Ghanbarian, Maryam; Afzali, Daryoush; Mostafavi, Ali; Fathirad, Fariba

2013-01-01

A new displacement-dispersive liquid-liquid microextraction method based on the solidification of floating organic drop was developed for separation and preconcentration of Pd(ll) in road dust and aqueous samples. This method involves two steps of dispersive liquid-liquid microextraction based on solidification. In Step 1, Cu ions react with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which is extracted by dispersive liquid-liquid microextraction based on a solidification procedure using 1-undecanol (extraction solvent) and ethanol (dispersive solvent). In Step 2, the extracted complex is first dispersed using ethanol in a sample solution containing Pd ions, then a dispersive liquid-liquid microextraction based on a solidification procedure is performed creating an organic drop. In this step, Pd(ll) replaces Cu(ll) from the pre-extracted Cu-DDTC complex and goes into the extraction solvent phase. Finally, the Pd(ll)-containing drop is introduced into a graphite furnace using a microsyringe, and Pd(ll) is determined using atomic absorption spectrometry. Several factors that influence the extraction efficiency of Pd and its subsequent determination, such as extraction and dispersive solvent type and volume, pH of sample solution, centrifugation time, and concentration of DDTC, are optimized.

Influence of liquid structure on diffusive isotope separation in molten silicates and aqueous solutions

NASA Astrophysics Data System (ADS)

Watkins, James M.; DePaolo, Donald J.; Ryerson, Frederick J.; Peterson, Brook T.

2011-06-01

Molecular diffusion in natural volcanic liquids discriminates between isotopes of major ions (e.g., Fe, Mg, Ca, and Li). Although isotope separation by diffusion is expected on theoretical grounds, the dependence on mass is highly variable for different elements and in different media. Silicate liquid diffusion experiments using simple liquid compositions were carried out to further probe the compositional dependence of diffusive isotopic discrimination and its relationship to liquid structure. Two diffusion couples consisting of the mineral constituents anorthite (CaAl 2Si 2O 8; denoted AN), albite (NaAlSi 3O 8; denoted AB), and diopside (CaMgSi 2O 6; denoted DI) were held at 1450 °C for 2 h and then quenched to ambient pressure and temperature. Major-element as well as Ca and Mg isotope profiles were measured on the recovered quenched glasses. In both experiments, Ca diffuses rapidly with respect to Si. In the AB-AN experiment, D Ca/ D Si ≈ 20 and the efficiency of isotope separation for Ca is much greater than in natural liquid experiments where D Ca/ D Si ≈ 1. In the AB-DI experiment, D Ca/ D Si ≈ 6 and the efficiency of isotope separation is between that of the natural liquid experiments and the AB-AN experiment. In the AB-DI experiment, D Mg/ D Si ≈ 1 and the efficiency of isotope separation for Mg is smaller than it is for Ca yet similar to that observed for Mg in natural liquids. The results from the experiments reported here, in combination with results from natural volcanic liquids, show clearly that the efficiency of diffusive separation of Ca isotopes is systematically related to the solvent-normalized diffusivity - the ratio of the diffusivity of the cation ( D Ca) to the diffusivity of silicon ( D Si). The results on Ca isotopes are consistent with available data on Fe, Li, and Mg isotopes in silicate liquids, when considered in terms of the parameter D cation/ D Si. Cations diffusing in aqueous solutions display a similar relationship between isotopic separation efficiency and Dcation/D, although the efficiencies are smaller than in silicate liquids. Our empirical relationship provides a tool for predicting the magnitude of diffusive isotopic effects in many geologic environments and a basis for a more comprehensive theory of isotope separation in liquid solutions. We present a conceptual model for the relationship between diffusivity and liquid structure that is consistent with available data.

Vacuum Ultraviolet Photoelectron Emission Spectroscopy of Water and Aqueous Solutions.

DTIC Science & Technology

1980-02-01

Siegbahn, Nouv. J. Chim. 1, 191 (1977). 26T. Shibaguchi, H . Onuki and R. Onaka, J. Phys. Soc. Japan 42, 152 (1977). 27I. Abbati, L. Braicovich and B. De...application of the Brodsky- Tsarevsky theory of photoelectronemtssion by solutions: 8.7, 7.9. 7.2, 8.4 eV, respectively, for CIT. Brr. V. H ions. The...externally cooled nitrogen gas flowed. The temperature of the liquid was monitored with thermistor H and kept constant at 1.50C by controlling the cooled gas

In situ measurement of contact angles and surface tensions of interfacial nanobubbles in ethanol aqueous solutions.

PubMed

Zhao, Binyu; Wang, Xingya; Wang, Shuo; Tai, Renzhong; Zhang, Lijuan; Hu, Jun

2016-04-14

The astonishing long lifetime and large contact angles of interfacial nanobubbles are still in hot debate despite numerous experimental and theoretical studies. One hypothesis to reconcile the two abnormalities of interfacial nanobubbles is that they have low surface tensions. However, few studies have been reported to measure the surface tensions of nanobubbles due to the lack of effective measurements. Herein, we investigate the in situ contact angles and surface tensions of individual interfacial nanobubbles immersed in different ethanol aqueous solutions using quantitative nanomechanical atomic force microscopy (AFM). The results showed that the contact angles of nanobubbles in the studied ethanol solutions were also much larger than the corresponding macroscopic counterparts on the same substrate, and they decreased with increasing ethanol concentrations. More significantly, the surface tensions calculated were much lower than those of the gas-liquid interfaces of the solutions at the macroscopic scale but have similar tendencies with increasing ethanol concentrations. Those results are expected to be helpful in further understanding the stability of interfacial nanobubbles in complex solutions.

Mesoporous carbons and polymers

DOEpatents

Bell, William; Dietz, Steven

2001-01-01

A mesoporous material prepared by polymerizing a resorcinol/formaldehyde system from an aqueous solution containing resorcinol, formaldehyde and a surfactant and optionally pyrolyzing the polymer to form a primarily carbonaceous solid. The material has an average pore size between 4 and 75 nm and is suitable for use in liquid-phase surface limited applications, including sorbent, catalytic, and electrical applications.

Recent Advances in High-Performance Direct Methanol Fuel Cells

NASA Technical Reports Server (NTRS)

Narayanan, S. R.; Chun, W.; Valdez, T. I.; Jeffries-Nakamura, B.; Frank, H.; Surumpudi, S.; Halpert, G.; Kosek, J.; Cropley, C.; La Conti, A. B.;

Hyperbaric hydrothermal atomic force microscope

DOEpatents

Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

2002-01-01

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

Hyperbaric Hydrothermal Atomic Force Microscope

DOEpatents

Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

2003-07-01

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

Susceptibility cancellation of a microcoil wound with a paramagnetic-liquid-filled copper capillary

NASA Astrophysics Data System (ADS)

Takeda, Kazuyuki; Takasaki, Tomoya; Takegoshi, K.

2015-09-01

Even though microcoils improve the sensitivity of NMR measurement of tiny samples, magnetic-field inhomogeneity due to the bulk susceptibility effect of the coil material can cause serious resonance-line broadening. Here, we propose to fabricate the microcoil using a thin, hollow copper capillary instead of a wire and fill paramagnetic liquid inside the capillary, so as to cancel the diamagnetic contribution of the copper. Susceptibility cancellation is demonstrated using aqueous solution of NiSO4. In addition, the paramagnetic liquid serves as coolant when it is circulated through the copper capillary, effectively transferring the heat generated by radiofrequency pulses.

Determination of preservatives in cosmetics, cleaning agents and pharmaceuticals using fast liquid chromatography.

PubMed

Baranowska, Irena; Wojciechowska, Iwona; Solarz, Natalia; Krutysza, Ewa

2014-01-01

This paper reports the development of a method for simultaneously determining five preservatives in cosmetics, cleaning agents and pharmaceuticals by fast liquid chromatography. Methylisothiazolinone, methylchloroisothiazolinone, benzyl alcohol, sodium benzoate and methylparaben were separated on a Chromolith Fast Gradient reversed-phase 18e column using gradient elution with acetonitrile and a 0.1% aqueous solution of formic acid, with a run time of 3 min. The preparation of solid and liquid samples included ultrasonic extraction with methanol with recoveries ranging from 69 to 119%. The developed method was used to analyze samples of cosmetics (66 samples), cleaning agents (five samples) and pharmaceutical industry products (17 samples).

Liquid-filled hollow core microstructured polymer optical fiber.

PubMed

Cox, F M; Argyros, A; Large, M C J

2006-05-01

Guidance in a liquid core is possible with microstructured optical fibers, opening up many possibilities for chemical and biochemical fiber-optic sensing. In this work we demonstrate how the bandgaps of a hollow core microstructured polymer optical fiber scale with the refractive index of liquid introduced into the holes of the microstructure. Such a fiber is then filled with an aqueous solution of (-)-fructose, and the resulting optical rotation measured. Hence, we show that hollow core microstructured polymer optical fibers can be used for sensing, whilst also fabricating a chiral optical fiber based on material chirality, which has many applications in its own right.

Highly Efficient Extraction of Phenolic Compounds by Use of Magnetic Room Temperature Ionic Liquids for Environmental Remediation

PubMed Central

Deng, Ning; Li, Min; Zhao, Lijie; Lu, Chengfei; de Rooy, Sergio L.; Warner, Isiah M.

2011-01-01

A hydrophobic magnetic room temperature ionic liquid (MRTIL), trihexyltetradecylphosphonium tetrachloroferrate(III) ([3C6PC14][FeCl4]), was synthesized from trihexyltetradecylphosphonium chloride and FeCl3·6H2O. This MRTIL was investigated as a possible separation agent for solvent extraction of phenolic compounds from aqueous solution. Due to its strong paramagnetism, [3C6PC14][FeCl4] responds to an external neodymium magnet, which was employed in the design of a novel magnetic extraction technique. The conditions for extraction, including extraction time, volume ratio between MRTIL and aqueous phase, pH of aqueous solution, and structures of phenolic compounds were investigated and optimized. The magnetic extraction of phenols achieved equilibrium in 20 min and the phenolic compounds were found to have higher distribution ratios under acidic conditions. In addition, it was observed that phenols containing a greater number of chlorine or nitro substitutents exhibited higher distribution ratios. For example, the distribution ratio of phenol (DPh) was 107. In contrast, 3,5-dichlorophenol distribution ratio (D3,5-DCP) had a much higher value of 6372 under identical extraction conditions. When compared with four selected traditional non-magnetic room temperature ionic liquids, our [3C6PC14][FeCl4] exhibited significantly higher extraction efficiency under the same experimental conditions used in this work. Pentachlorophenol, a major component in the contaminated soil sample obtained from a superfund site, was successfully extracted and removed by use of [3C6PC14][FeCl4] with high extraction efficiency. Pentachlorophenol concentration was dramatically reduced from 7.8 μg.mL−1 to 0.2 μg.mL−1 after the magnetic extraction by use of [3C6PC14][FeCl4]. PMID:21783320

Magnetic iron oxide nanoparticles for the collection and direct measurement of adsorbed alpha-emitting radionuclides from environmental waters by liquid scintillation analysis

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

O'Hara, Matthew J.; Addleman, R. Shane

Radioactive contamination in the environment, be it from accidental or intentional release, can create an urgent need to assess water and food supplies, the environment, and monitor human health. Alpha-emitting radionuclides represent the most ionizing, and therefore the most damaging, form of radiation when internalized. Additionally, because of its ease of energy attenuation in solids or liquids, alpha emissions cannot be reliably monitored using non-destructive means. In the event of such an emergency, rapid and efficient methods will be needed to screen scores of samples (food, water, and human excreta) within a short time window. Unfortunately, the assay of alpha-emittingmore » radionuclides using traditional radioanalytical methods is typically labor intensive and time consuming. The creation of analytical counting sources typically requires a series of chemical treatment steps to achieve well performing counting sources. In an effort to devise radioanalytical methods that are fast, require little labor, and minimize the use of toxic or corrosive agents, researchers at PNNL have evaluated magnetite (Fe3O4) nanoparticles as extracting agents for alpha-emitting radionuclides from chemically unmodified aqueous systems. It is demonstrated that bare magnetic nanoparticles exhibit high affinity for representative α-emitting radionuclides (241Am and 210Po) from representative aqueous matrices: river and ground water. Furthermore, use of the magnetic properties of these materials to concentrate the sorbed analyte from the bulk aqueous solution has been demonstrated. The nanoparticle concentrate can be either directly dispensed into scintillation cocktail, or first dissolved and then added to scintillation cocktail as a solution for alpha emission assay by liquid scintillation analysis. Despite the extreme quench caused by the metal oxide suspensions, the authors have demonstrated that quench correction features available on modern liquid scintillation analyzers can be employed to assure that quench-induced analytical biases can be avoided.« less

Dissociation of biomolecules in liquid environments during fast heavy-ion irradiation

NASA Astrophysics Data System (ADS)

Nomura, Shinji; Tsuchida, Hidetsugu; Kajiwara, Akihiro; Yoshida, Shintaro; Majima, Takuya; Saito, Manabu

2017-12-01

The effect of aqueous environment on fast heavy-ion radiation damage of biomolecules was studied by comparative experiments using liquid- and gas-phase amino acid targets. Three types of amino acids with different chemical structures were used: glycine, proline, and hydroxyproline. Ion-induced reaction products were analyzed by time-of-flight secondary-ion mass spectrometry. The results showed that fragments from the amino acids resulting from the C—Cα bond cleavage were the major products for both types of targets. For liquid-phase targets, specific products originating from chemical reactions in solutions were observed. Interestingly, multiple dissociated atomic fragments were negligible for the liquid-phase targets. We found that the ratio of multifragment to total fragment ion yields was approximately half of that for gas-phase targets. This finding agreed with the results of other studies on biomolecular cluster targets. It is concluded that the suppression of molecular multifragmentation is caused by the energy dispersion to numerous water molecules surrounding the biomolecular solutes.

Microcapsule and methods of making and using microcapsules

DOEpatents

Okawa, David C.; Pastine, Stefan J.; Zettl, Alexander K.; Frechet, Jean M.J.

2014-09-02

An embodiment of a microcapsule includes a shell surrounding a space, a liquid within the shell, and a light absorbing material within the liquid. An embodiment of a method of making microcapsules includes forming a mixture of a light absorbing material and an organic solution. An emulsion of the mixture and an aqueous solution is then formed. A polymerization agent is added to the emulsion, which causes microcapsules to be formed. Each microcapsule includes a shell surrounding a space, a liquid within the shell, and light absorbing material within the liquid. An embodiment of a method of using microcapsules includes providing phototriggerable microcapsules within a bulk material. Each of the phototriggerable microcapsules includes a shell surrounding a space, a chemically reactive material within the shell, and a light absorbing material within the shell. At least some of the phototriggerable microcapsules are exposed to light, which causes the chemically reactive material to release from the shell and to come into contact with bulk material.

Experimental Study of Heating of a Liquid Cathode and Transfer of Its Components into the Gas Phase under the Action of a DC Discharge

NASA Astrophysics Data System (ADS)

Sirotkin, N. A.; Titov, V. A.

2018-04-01

An atmospheric-pressure dc discharge in air ( i = 10-50 mA) with metal and liquid electrolyte electrodes was studied experimentally. An aqueous solution of sodium chloride (0.5 mol/L) was used as the cathode or anode. The electric field strength in the plasma and the cathode (anode) voltage drops were obtained from the measured dependences of the discharge voltage on the electrode gap length. The gas temperature was deduced from the spectral distribution of nitrogen emission in the band N2( C 3Π u → B 3Π g , 0-2). The time dependences of the temperatures of the liquid electrolyte electrodes during the discharge and in its afterglow, as well as the evaporation rate of the solution, were determined experimentally. The contributions of ion bombardment and heat flux from the plasma to the heating of the liquid electrode and transfer of solvent (water) into the gas phase are discussed using the experimental data obtained.

Photodegradation of the novel fungicide fluopyram in aqueous solution: kinetics, transformation products, and toxicity evolvement.

PubMed

Dong, Bizhang; Hu, Jiye

2016-10-01

The aqueous photodegradation of fluopyram was investigated under UV light (λ ≥ 200 nm) and simulated sunlight irradiation (λ ≥ 290 nm). The effect of solution pH, fulvic acids (FA), nitrate (NO3 (-)), Fe (III) ions, and titanium dioxide (TiO2) on direct photolysis of fluopyram was explored. The results showed that fluopyram photodegradation was faster in neutral solution than that in acidic and alkaline solutions. The presence of FA, NO3 (-), Fe (III), and TiO2 slightly affected the photodegradation of fluopyram under UV irradiation, whereas the photodegradation rates of fluopyram with 5 mg L(-1) Fe (III) and 500 mg L(-1) TiO2 were about 7-fold and 13-fold faster than that without Fe (III) and TiO2 under simulated sunlight irradiation, respectively. Three typical products for direct photolysis of fluopyram have been isolated and characterized by liquid chromatography tandem mass spectrometry. These products resulted from the intramolecular elimination of HCl, hydroxyl-substitution, and hydrogen extraction. Based on the identified transformation products and evolution profile, a plausible degradation pathway for the direct photolysis of fluopyram in aqueous solution was proposed. In addition, acute toxicity assays using the Vibrio fischeri bacteria test indicated that the transformation products were more toxic than the parent compound.

A classical view on nonclassical nucleation.

PubMed

Smeets, Paul J M; Finney, Aaron R; Habraken, Wouter J E M; Nudelman, Fabio; Friedrich, Heiner; Laven, Jozua; De Yoreo, James J; Rodger, P Mark; Sommerdijk, Nico A J M

2017-09-19

Understanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO 3 ) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO 3 nucleation is still a topic of intense discussion, with new pathways for its growth from ions in solution proposed in recent years. These new pathways include the so-called nonclassical nucleation mechanism via the assembly of thermodynamically stable prenucleation clusters, as well as the formation of a dense liquid precursor phase via liquid-liquid phase separation. Here, we present results from a combined experimental and computational investigation on the precipitation of CaCO 3 in dilute aqueous solutions. We propose that a dense liquid phase (containing 4-7 H 2 O per CaCO 3 unit) forms in supersaturated solutions through the association of ions and ion pairs without significant participation of larger ion clusters. This liquid acts as the precursor for the formation of solid CaCO 3 in the form of vaterite, which grows via a net transfer of ions from solution according to z Ca 2+ + z CO 3 2- → z CaCO 3 The results show that all steps in this process can be explained according to classical concepts of crystal nucleation and growth, and that long-standing physical concepts of nucleation can describe multistep, multiphase growth mechanisms.

Effect of stirring on the safety of flammable liquid mixtures.

PubMed

Liaw, Horng-Jang; Gerbaud, Vincent; Chen, Chan-Cheng; Shu, Chi-Min

2010-05-15

Flash point is the most important variable employed to characterize fire and explosion hazard of liquids. The models developed for predicting the flash point of partially miscible mixtures in the literature to date are all based on the assumption of liquid-liquid equilibrium. In real-world environments, however, the liquid-liquid equilibrium assumption does not always hold, such as the collection or accumulation of waste solvents without stirring, where complete stirring for a period of time is usually used to ensure the liquid phases being in equilibrium. This study investigated the effect of stirring on the flash-point behavior of binary partially miscible mixtures. Two series of partially miscible binary mixtures were employed to elucidate the effect of stirring. The first series was aqueous-organic mixtures, including water+1-butanol, water+2-butanol, water+isobutanol, water+1-pentanol, and water+octane; the second series was the mixtures of two flammable solvents, which included methanol+decane, methanol+2,2,4-trimethylpentane, and methanol+octane. Results reveal that for binary aqueous-organic solutions the flash-point values of unstirred mixtures were located between those of the completely stirred mixtures and those of the flammable component. Therefore, risk assessment could be done based on the flammable component flash-point value. However, for the assurance of safety, it is suggested to completely stir those mixtures before handling to reduce the risk. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Kinetics and models of hydrogenation of phenylhydroxylamine and azobenzene on nickel catalysts in aqueous 2-propanol solutions

NASA Astrophysics Data System (ADS)

Romanenko, Yu. E.; Merkin, A. A.; Komarov, A. A.; Lefedova, O. V.

2014-08-01

The kinetics of the hydrogenation of intermediates in the reduction of nitrobenzene in aqueous 2-propanol with acetic acid and sodium hydroxide additions on nickel catalysts was studied. A kinetic description of liquid-phase hydrogenation of azobenzene and phenylhydroxylamine was suggested. A kinetic model was developed. The dependences that characterize the variation of the amounts of the starting compound, reaction product, and absorbed hydrogen during the reaction were calculated. The calculated values were shown to be in satisfactory agreement with the experimental values under different reaction conditions.

Raman Spectroscopic Observations of the Ion Association between Mg(2+) and SO4(2-) in MgSO4-Saturated Droplets at Temperatures of ≤380 °C.

PubMed

Wan, Ye; Wang, Xiaolin; Hu, Wenxuan; Chou, I-Ming

2015-08-27

Liquid–liquid phase separation was observed in aqueous MgSO4 solutions with excess H2SO4 at elevated temperatures; the aqueous MgSO4/H2SO4 solutions separated into MgSO4-rich droplets (fluid F1) and a MgSO4-poor phase (fluid F2) during heating. The phase separation temperature increases with SO4(2–)/Mg2+ ratio at a constant MgSO4 concentration. At a MgSO4/H2SO4 ratio of 5, the liquid–liquid phase separation temperature decreases with an increase in MgSO4 concentration up to ∼1.0 mol/kg and then increases at higher concentrations, showing a typical macroscale property of polymer solutions with a lower critical solution temperature (LCST) of ∼271.4 °C. In situ Raman spectroscopic analyses show that the MgSO4 concentration in fluid F1 increases with an increase in temperature, whereas that in fluid F2 decreases with an increase in temperature. In addition, HSO4(–), which does not readily form complexes with Mg(2+), tends to accumulate in fluid F2. Analyses of the v1(SO4(2–)) bands confirmed the presence of four-sulfate species of unassociated SO4(2–) (∼980 cm(–1)), contact ion pairs (CIPs; ∼995 cm(–1)), and triple ion pairs (TIPs; ∼1005 cm(–1)) in aqueous solution, and more complex ion pair chain structure (∼1020 cm(–1)) in fluid F1. Comparison of the sulfate species in fluids F1 and F2 at 280 °C suggests that SO4(2–) in fluid F2 is less associated with Mg(2+). On the basis of in situ visual and Raman spectroscopic observations, we suggest that the formation of the complex Mg(2+)–SO4(2–) ion association might be responsible for the liquid–liquid phase separation. In addition, Raman spectroscopic analyses of the OH stretching bands indicate that the hydrogen bonding in fluid F1 is stronger than that in fluid F2, which might be ascribed to the increasing probability of collision of H2O with Mg(2+) and SO4(2–) in fluid F1.

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.

Method of removing oxides of sulfur and oxides of nitrogen from exhaust gases

DOEpatents

Walker, Richard J.

1986-01-01

A continuous method is presented for removing both oxides of sulfur and oxides of nitrogen from combustion or exhaust gases with the regeneration of the absorbent. Exhaust gas is cleaned of particulates and HCl by a water scrub prior to contact with a liquid absorbent that includes an aqueous solution of bisulfite and sulfite ions along with a metal chelate, such as, an iron or zinc aminopolycarboxylic acid. Following contact with the combustion gases the spent absorbent is subjected to electrodialysis to transfer bisulfite ions into a sulfuric acid solution while splitting water with hydroxide and hydrogen ion migration to equalize electrical charge. The electrodialysis stack includes alternate layers of anion selective and bipolar membranes. Oxides of nitrogen are removed from the liquid absorbent by air stripping at an elevated temperature and the regenerated liquid absorbent is returned to contact with exhaust gases for removal of sulfur oxides and nitrogen oxides.

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

Controlling the Formation of Ionic-Liquid-based Aqueous Biphasic Systems by Changing the Hydrogen-Bonding Ability of Polyethylene Glycol End Groups.

PubMed

Pereira, Jorge F B; Kurnia, Kiki A; Freire, Mara G; Coutinho, João A P; Rogers, Robin D

2015-07-20

The formation of aqueous biphasic systems (ABS) when mixing aqueous solutions of polyethylene glycol (PEG) and an ionic liquid (IL) can be controlled by modifying the hydrogen-bond-donating/-accepting ability of the polymer end groups. It is shown that the miscibility/immiscibility in these systems stems from both the solvation of the ether groups in the oxygen chain and the ability of the PEG terminal groups to preferably hydrogen bond with water or the anion of the salt. The removal of even one hydrogen bond in PEG can noticeably affect the phase behavior, especially in the region of the phase diagram in which all the ethylene oxide (EO) units of the polymeric chain are completely solvated. In this region, removing or weakening the hydrogen-bond-donating ability of PEG results in greater immiscibility, and thus, in a higher ability to form ABS, as a result of the much weaker interactions between the IL anion and the PEG end groups. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Capacitive behaviour of MnF2 and CoF2 submicro/nanoparticles synthesized via a mild ionic liquid-assisted route

NASA Astrophysics Data System (ADS)

Ma, Ruguang; Zhou, Yao; Yao, Lin; Liu, Guanghui; Zhou, Zhenzhen; Lee, Jong-Min; Wang, Jiacheng; Liu, Qian

2016-01-01

Submicro-/nano-sized MnF2 rods and hierarchical CoF2 cuboids are respectively synthesized via a facile precipitation method assisted by ionic liquid under a mild condition. The as-prepared MF2 (M = Mn, Co) submicro/nanoparticles exhibit impressive specific capacitance in 1.0 M KOH aqueous solution, especially at relatively high current densities, e.g. 91.2, 68.7 and 56.4 F g-1 for MnF2, and 81.7, 70.6 and 63.0 F g-1 for CoF2 at 5, 8 and 10 A g-1, respectively. The mechanism of striking capacitance of MF2 is clarified on the basis of analysing the cycled electrodes by different characterization techniques. Such remarkable capacitance is ascribed to the redox reactions between MF2 and MOOH in aqueous alkaline electrolytes, which can not be obtained in aqueous neutral electrolytes. This study for the first time provides direct evidences on the pseudocapacitance mechanism of MF2 in alkaline electrolytes and paves the way of application of transition metal fluorides as electrodes in supercapacitors.

Fluid inclusion study of some Sarrabus fluorite deposits, Sardinia, Italy.

USGS Publications Warehouse

Belkin, H.E.; de Vivo, B.; Valera, R.

1984-01-01

Fluid inclusions in six deposits of fluorite fracture fillings associated with Hercynian (Carboniferous) cycle magmatism were studied by microthermometric techniques. All the inclusions were liquid dominated, aqueous, and homogenized in the liquid phase. One-phase (liquid), two-phase (liquid + vapour) and three-phase (liquid, vapour, and solid NaCl daughter mineral) fluid inclusions were noted. This study indicates that five of the fluorite deposits formed from 95o-125oC fluids with approx 15 wt.% NaCl. One other deposit appears to have been formed by very dilute solutions at approx 125oC. It is suggested that the local fluorite-forming process was the formation of fracture-localized hydrothermal systems in which magmatic water interaction with some other fluid-connate, meteoric, or marine.-G.J.N.

Experimental studies of contact angle hysteresis phenomena on polymer surfaces – Toward the understanding and control of wettability for different applications.

PubMed

Grundke, K; Pöschel, K; Synytska, A; Frenzel, R; Drechsler, A; Nitschke, M; Cordeiro, A L; Uhlmann, P; Welzel, P B

2015-08-01

Contact angle hysteresis phenomena on polymer surfaces have been studied by contact angle measurements using sessile liquid droplets and captive air bubbles in conjunction with a drop shape method known as Axisymmetric Drop Shape Analysis - Profile (ADSA-P). In addition, commercially available sessile drop goniometer techniques were used. The polymer surfaces were characterized with respect to their surface structure (morphology, roughness, swelling) and surface chemistry (elemental surface composition, acid-base characteristics) by scanning electron microscopy (SEM), scanning force microscopy (SFM), ellipsometry, X-ray photoelectron spectroscopy (XPS) and streaming potential measurements. Heterogeneous polymer surfaces with controlled roughness and chemical composition were prepared by different routes using plasma etching and subsequent dip coating or grafting of polymer brushes, anodic oxidation of aluminium substrates coated with thin polymer films, deposition techniques to create regular patterned and rough fractal surfaces from core-shell particles, and block copolymers. To reveal the effects of swelling and reorientation at the solid/liquid interface contact angle hysteresis phenomena on polyimide surfaces, cellulose membranes, and thermo-responsive hydrogels have been studied. The effect of different solutes in the liquid (electrolytes, surfactants) and their impact on contact angle hysteresis were characterized for solid polymers without and with ionizable functional surface groups in aqueous electrolyte solutions of different ion concentrations and pH and for photoresist surfaces in cationic aqueous surfactant solutions. The work is an attempt toward the understanding of contact angle hysteresis phenomena on polymer surfaces aimed at the control of wettability for different applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Gas-liquid chromatographic determination of 3-trifluoromethyl-4-nitrophenol residues in fish

USGS Publications Warehouse

Allen, J.L.; Sills, J.B.

1974-01-01

A procedure for the determination of 3-mftuormethyl-4-nitrophenol (TFM) in fish tissues is described. Homogenized tissues are extracted with hexane-ethyl ether; the extract is cleaned up by partitioning the TFM from the extracting solvent into O.IN NaOB, acidifying the aqueous solution, and partitioning again with hexaneethyl ether. The TFM is methylated with diazomethane and analyzed by gas-liquid chromatography, using electron capture detection. Recoveries ranged from 75 to 1000/., from fish muscles that were spiked with 0.01-2.00 JA#g TFM/g.

Reactions of Ions with Ionic Liquid Vapors by Selected-Ion Flow Tube Mass Spectrometry

DTIC Science & Technology

2011-03-29

Emel’yanenko, V. N.; Verevkin, S. P.; Heintz, A.; Corfield, J.-A.; Deyko, A.; Lovelock , K. R. J.; Licence, P.; Jones, R. G. Pyrrolidinium- Based Ionic...112, 11734–11742. (2) Lovelock , K. R. J.; Deyko, A.; Licence, P.; Jones, R. G. Vaporisa- tion of an Ionic Liquid Near Room Temperature. Phys. Chem...Relevance of pKa from Aqueous Solutions. J. Am. Chem. Soc. 2003, 125, 15411–15419. (15) Armstrong, J. P.; Hurst, C.; Jones, R. G.; Licence, P.; Lovelock , K

Application of ionic liquid-based dispersive liquid phase microextraction for highly sensitive simultaneous determination of three endocrine disrupting compounds in food packaging.

PubMed

Wang, Lingling; Zhang, Danfeng; Xu, Xu; Zhang, Lei

2016-04-15

Ionic liquid (IL) dispersive liquid-liquid microextraction (DLLME) method was successfully developed for extracting three endocrine disrupting compounds (EDCs) (bisphenol A, bisphenol AF and bisphenol AP) from the food packaging. 1-Octyl-3-methylimidazoliumhexafluorophosphate ([C8MIM][PF6]) was selected as extraction solution. The extraction procedure did not require a dispersive solvent. Three EDCs extraction kinetics were found to be very fast and the equilibrium was attained within 3.0 min following the pseudo-first-order model. The H-bonding and hydrophobic interactions play an important role in the partitioning of EDCs into IL from aqueous solution. The recovered IL could be reused for three runs without significant loss of extraction efficiencies. The spiked recoveries of three targets in food packaging were in the range of 97.8-103.1%. The limits of detection ranged from 0.50 to 1.50 ng mL(-1) (S/N=3). As a result, this method has been successfully applied for the sensitive detection of three EDCs in real samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Laser capillary spectrophotometric acquisition of bivariate drop size and concentration data for liquid-liquid dispersion

DOEpatents

Tavlarides, Lawrence L.; Bae, Jae-Heum

1991-01-01

A laser capillary spectrophotometric technique measures real time or near real time bivariate drop size and concentration distribution for a reactive liquid-liquid dispersion system. The dispersion is drawn into a precision-bore glass capillary and an appropriate light source is used to distinguish the aqueous phase from slugs of the organic phase at two points along the capillary whose separation is precisely known. The suction velocity is measured, as is the length of each slug from which the drop free diameter is calculated. For each drop, the absorptivity at a given wavelength is related to the molar concentration of a solute of interest, and the concentration of given drops of the organic phase is derived from pulse heights of the detected light. This technique permits on-line monitoring and control of liquid-liquid dispersion processes.

Effect of gatifloxacin ophthalmic solution 0.3% on human corneal endothelial cell density and aqueous humor gatifloxacin concentration.

PubMed

Price, Marianne O; Quillin, Clorissa; Price, Francis W

2005-07-01

To evaluate the effect of gatifloxacin ophthalmic solution 0.3% (Zymar, Allergan, Inc., Irvine, CA, USA) on corneal endothelial cell density and morphology and to measure gatifloxacin penetration into aqueous humor. This was a single-center, open-label clinical study. Ten patients undergoing standard cataract surgery and 20 nonsurgical subjects instilled gatifloxacin 0.3% four times per day for 2 days, then every 10 min for 1 hr on the third day (the surgery day for the cataract patients). Corneal endothelial cells were counted using noncontact specular microscopy. Anterior chamber fluid was withdrawn from the surgical patients, and the gatifloxacin concentration was quantified by high-pressure liquid chromatography. Baseline endothelial cell counts (mean +/- SD) were 2400 +/- 442 in the surgical group and 2520 +/- 212 in the nonsurgical group. The mean differences from baseline 1 hr after the last dose of gatifloxacin 0.3% were -51 +/- 213 (p = 0.23) in the surgical group and -7 +/- 150 (p = 0.42) in the nonsurgical group. In the nonsurgical group, the mean difference from baseline 3 weeks after the last dose was 18 +/- 147 (p = 0.71). The mean concentration (+/- SD) of gatifloxacin in aqueous humor was 1.26 +/- 0.55 microg/ml. A preoperative, prophylactic course of gatifloxacin 0.3% ophthalmic solution did not significantly affect endothelial cell density or morphology, while meaningful drug concentration was achieved in the aqueous humor.

Development of solid-phase microextraction coupled with liquid chromatography for analysis of tramadol in brain tissue using its molecularly imprinted polymer.

PubMed

Habibi-Khorasani, Monireh; Mohammadpour, Amir Hooshang; Mohajeri, Seyed Ahmad

2017-02-01

In this work, performance of a molecularly imprinted polymer (MIP) as a selective solid-phase microextraction sorbent for the extraction and enrichment of tramadol in aqueous solution and rabbit brain tissue, is described. Binding properties of MIPs were studied in comparison with their nonimprinted polymer (NIP). Ten milligrams of the optimized MIP was then evaluated as a sorbent, for preconcentration, in molecularly imprinted solid-phase microextraction (MISPME) of tramadol from aqueous solution and rabbit brain tissue. The analytical method was calibrated in the range of 0.004 ppm (4 ng mL -1 ) and 10 ppm (10 μg mL -1 ) in aqueous media and in the ranges of 0.01 and 10 ppm in rabbit brain tissue, respectively. The results indicated significantly higher binding affinity of MIPs to tramadol, in comparison with NIP. The MISPME procedure was developed and optimized with a recovery of 81.12-107.54% in aqueous solution and 76.16-91.20% in rabbit brain tissue. The inter- and intra-day variation values were <8.24 and 5.06%, respectively. Finally the calibrated method was applied for determination of tramadol in real rabbit brain tissue samples after administration of a lethal dose. Our data demonstrated the potential of MISPME for rapid, sensitive and cost-effective sample analysis. Copyright © 2016 John Wiley & Sons, Ltd.

Characterization of electrochemically deposited films from aqueous and ionic liquid cobalt precursors toward hydrogen evolution reactions

NASA Astrophysics Data System (ADS)

Dushatinski, Thomas; Huff, Clay; Abdel-Fattah, Tarek M.

2016-11-01

Electrodepositions of cobalt films were achieved using an aqueous or an ethylene glycol based non-aqueous solution containing choline chloride (vitamin B4) with cobalt chloride hexahydrate precursor toward hydrogen evolution reactions from sodium borohydride (NaBH4) as solid hydrogen feedstock (SHF). The resulting cobalt films had reflectivity at 550 nm of 2.2% for aqueously deposited films (ACoF) and 1.3% for non-aqueously deposited films (NCoF). Surface morphology studied by scanning electron microscopy showed a positive correlation between particle size and thickness. The film thicknesses were tunable between >100 μm and <300 μm for each film. The roughness (Ra) value measurements by Dektak surface profiling showed that the NCoF (Ra = 165 nm) was smoother than the ACoF (Ra = 418 nm). The NCoFs and ACoFs contained only α phase (FCC) crystallites. The NCoFs were crystalline while the ACoFs were largely amorphous from X-ray diffraction analysis. The NCoF had an average Vickers hardness value of 84 MPa as compared to 176 MPa for ACoF. The aqueous precursor has a single absorption maximum at 510 nm and the non-aqueous precursor had three absorption maxima at 630, 670, and 695 nm. The hydrogen evolution reactions over a 1 cm2 catalytic surface with aqueous NaBH4 solutions generated rate constants (K) = equal to 4.9 × 10-3 min-1, 4.6 × 10-3 min-1, and 3.3 × 10-3 min-1 for ACoF, NCoF, and copper substrate respectively.

Water-Assisted Production of Thermoplastic Nanocomposites: A Review.

PubMed

Karger-Kocsis, József; Kmetty, Ákos; Lendvai, László; Drakopoulos, Stavros X; Bárány, Tamás

2014-12-29

Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basically a combination of solution-assisted and traditional melt mixing methods. It is an emerging technique to overcome several disadvantages of the above two. Water or aqueous liquids with additives, do not work merely as temporary carrier materials of suitable nanofillers. During batchwise and continuous compounding, these liquids are fully or partly evaporated. In the latter case, the residual liquid is working as a plasticizer. This processing technique contributes to a better dispersion of the nanofillers and affects markedly the morphology and properties of the resulting nanocomposites. A survey is given below on the present praxis and possible future developments of water-assisted melt mixing techniques for the production of thermoplastic nanocomposites.

Water-Assisted Production of Thermoplastic Nanocomposites: A Review

PubMed Central

Karger-Kocsis, József; Kmetty, Ákos; Lendvai, László; Drakopoulos, Stavros X.; Bárány, Tamás

2014-01-01

Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basically a combination of solution-assisted and traditional melt mixing methods. It is an emerging technique to overcome several disadvantages of the above two. Water or aqueous liquids with additives, do not work merely as temporary carrier materials of suitable nanofillers. During batchwise and continuous compounding, these liquids are fully or partly evaporated. In the latter case, the residual liquid is working as a plasticizer. This processing technique contributes to a better dispersion of the nanofillers and affects markedly the morphology and properties of the resulting nanocomposites. A survey is given below on the present praxis and possible future developments of water-assisted melt mixing techniques for the production of thermoplastic nanocomposites. PMID:28787925

Effect of salts on the solubility of ionic liquids in water: experimental and electrolyte Perturbed-Chain Statistical Associating Fluid Theory†

PubMed Central

Mohammad, Sultan; Schleinitz, Miko; Coutinhoa, João A. P.; Freire, Mara G.

2016-01-01

Due to scarce available experimental data, as well as due to the absence of predictive models, the influence of salts on the solubility of ionic liquids (ILs) in water is still poorly understood. To this end, this work addresses the solubility of the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4C1im][NTf2]), at 298.15 K and 0.1 MPa, in aqueous salt solutions (from 0.1 to 1.5 mol kg−1). At salt molalities higher than 0.2 mol kg−1, all salts caused salting-out of [C4C1im][NTf2] from aqueous solution with their strength decreasing in the following order: Al2(SO4)3 > ZnSO4 > K3C6H5O7 > KNaC4H4O6 > K3PO4 > Mg(CH3CO2)2 > K2HPO4 > MgSO4 > KH2PO4 > KCH3CO2. Some of these salts lead however to the salting-in of [C4C1im][NTf2] in aqueous medium at salt molalities lower than 0.20 mol kg−1. To attempt the development of a model able to describe the salt effects, comprising both the salting-in and salting-out phenomena observed, the electrolyte Perturbed-Chain Statistical Associating Fluid Theory (ePC-SAFT) was applied using ion-specific parameters. The gathered experimental data was modelled using ePC-SAFT parameters complemented by fitting a single binary parameter between K+ and the IL-ions to the IL solubility in K3PO4 aqueous solutions. Based on this approach, the description of anion-specific salting-out effects of the remaining potassium salts was found to be in good agreement with experimental data. Remarkably, ePC-SAFT is even able to predict the salting-in effect induced by K2HPO4, based on the single K+/IL-ions binary parameter which was fitted to an exclusively salting-out effect promoted by K3PO4. Finally, ePC-SAFT was applied to predict the influence of other sodium salts on the [C4C1im][NTf2] solubility in water, with experimental data taken from literature, leading to an excellent description of the liquid–liquid phase behaviour. PMID:26575280

Dispersive liquid-liquid microextraction method based on solidification of floating organic droplet for the determination of thiamphenicol and florfenicol in environmental water samples.

PubMed

Peng, Guilong; He, Qiang; Al-Hamadani, Sulala M Z F; Zhou, Guangming; Liu, Mengzi; Zhu, Hui; Chen, Junhua

2015-05-01

Dispersive liquid-liquid microextraction with solidification of a floating organic droplet (DLLME-SFO) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was applied for the determination of thiamphenicol (TAP), florfenicol (FF) in water samples. 1-Undecanol was used as the extraction solvent which has lower density than water, low toxicity, and low melting point (19°C). A mixture of 800mL acetone (disperser solvent) and 80µL of 1-undecanol (extraction solvent) was injected into 20mL of aqueous solution. After 5min, 0.6g of NaCl was added and the sample vial was shaken. After 5min, the sample was centrifuged at 3500rpm for 3min, and then placed in an ice bath. When the extraction solvent floating on the aqueous solution had solidified, it was transferred into another conical vial where it was melted quickly at room temperature, and was diluted with methanol to 1mL, and analyzed by HPLC-UV detection. Parameters influencing the extraction efficiency were thoroughly examined and optimized. The extraction recoveries (ER) and the enrichment factors (EF) ranged from 67% to 72% and 223 to 241, respectively. The limits of detection (LODs) (S/N=3) were 0.33 and 0.56µgL(-1) for TAP and FF, respectively. Linear dynamic range (LDR) was in the range of 1.0-550µgL(-1) for TAP and 1.5-700µgL(-1) for FF, the relative standard deviations (RSDs) were in the range of 2.6-3.5% and the recoveries of spiked samples ranged from 94% to 106%. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

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.

Removal and recovery of metals and other materials by supported liquid membranes with strip dispersion.

PubMed

Ho, W S Winston

2003-03-01

This paper reviews recent advances in supported liquid membranes (SLMs) with strip dispersion for removal and recovery of metals including chromium, copper, zinc, and strontium; it also discusses potential applications of SLMs for removal and recovery of other materials, including cobalt and penicillin G. The technology for chromium that we developed, not only removes the Cr(VI) from about 100-1,000 ppm to less than 0.05 ppm in the treated effluent allowable for discharge or recycle, but also recovers the chromium product at a high concentration of about 20% Cr(VI) (62.3% Na(2)CrO(4)) suitable for resale or reuse. In other words, we have achieved the goals of zero discharge and no sludge. The stability of the SLM is ensured by a modified SLM with strip dispersion, where the aqueous strip solution is dispersed in the organic membrane solution in a mixer. The strip dispersion formed is circulated from the mixer to the membrane module to provide a constant supply of the organic solution to the membrane pores. The copper SLM system that we have identified, not only removed the copper from 150 ppm in the inlet feed to less than 0.15 ppm in the treated feed, but also recovered the copper at a high concentration of greater than 10,000 ppm in the strip solution. For the zinc SLM system identified, zinc at an inlet feed concentration of 550 ppm was removed to less than 0.3 ppm in the treated feed, whereas a high zinc concentration of more than 17,000 ppm was recovered in the strip solution. For strontium removal, we synthesized a family of new extractants, alkyl phenylphosphonic acids. The SLM removed radioactive (90)Sr to the target of 8 pCi/L or lower from feed solutions of 300-1,000 pCi/L. The SLM removed cobalt from about 525 ppm to 0.7 ppm in the treated feed solution, concentrating it to at least 30,000 ppm in the aqueous strip solution. Concerning penicillin G recovery, the SLM removed penicillin G from a feed of 8,840 ppm and concentrated it to a high concentration of 41,011 ppm in the aqueous strip solution with a high recovery of about 93%.

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.

Surface-bubble-modulated liquid chromatography: a new approach for manipulation of chromatographic retention and investigation of solute distribution at water/hydrophobic interfaces.

PubMed

Nakamura, Keisuke; Nakamura, Hiroki; Saito, Shingo; Shibukawa, Masami

2015-01-20

In this paper, we present a new chromatographic method termed surface-bubble-modulated liquid chromatography (SBMLC), that has a hybrid separation medium incorporated with surface nanobubbles. Nanobubbles or nanoscale gas phases can be fixed at the interface between water and a hydrophobic material by delivering water into a dry column packed with a nanoporous material. The incorporation of a gas phase at the hydrophobic surface leads to the formation of the hybrid separation system consisting of the gas phase, hydrophobic moieties, and the water/hydrophobic interface or the interfacial water. One can change the volume of the gas phase by pressure applied to the column, which in turn alters the area of water/hydrophobic interface or the volume of the interfacial water, while the amount of the hydrophobic moiety remains constant. Therefore, this strategy provides a novel technique not only for manipulating the separation selectivity by pressure but also for elucidating the mechanism of accumulation or retention of solute compounds in aqueous solutions by a hydrophobic material. We evaluate the contributions of the interfacial water at the surface of an octadecyl bonded silica and the bonded layer itself to the retention of various solute compounds in aqueous solutions on the column packed with the material by SBMLC. The results show that the interfacial water formed at the hydrophobic surface has a key role in retention even though its volume is rather small. The manipulation of the separation selectivity of SBMLC for some organic compounds by pressure is demonstrated.

Cryopreservation of Proteins Using Ionic Liquids: A Case Study of Cytochrome c.

PubMed

Takekiyo, Takahiro; Ishikawa, Yuka; Yoshimura, Yukihiro

2017-08-17

Aqueous ionic liquid (IL) solutions form a glassy state at 77 K over a wide concentration of ILs. They have potential as novel cryopreservation/refolding solvents for proteins. However, even if proteins in glass-forming concentrations of ILs are preserved at 77 K, the recovery of activity and the structure of the proteins after cryopreservation are still unclear. To achieve high recovery of protein activity and structure by removal of ILs after cryopreservation at 77 K, we studied the recovery of activity and structural stability after cryopreservation of bovine heart cytochrome c in aqueous solutions with ILs, including ethylammonium nitrate (EAN) and 1-butyl-3-methylimidazolium thiocyanate ([bmim][SCN]) over wide IL concentrations using UV-vis, Fourier transform infrared (FTIR), and circular dichroism (CD) spectroscopy. On the whole, although the addition of both ILs induced a decrease of activity and unfolding of the secondary structure of cytochrome c before and after cooling to 77 K, EAN, a weak denaturant, showed a reduction in protein damage (decrease of activity and unfolding of secondary structure) during the reheating process from 77 K (protection ability). In contrast, [bmim][SCN], a strong denaturant, did not have this protective ability. A remarkable result is that although the addition of both ILs caused cytochrome c denaturation, > 90% of activity and structure after cryopreservation (X > 10 mol %IL) was recovered after the removal of both ILs by dialysis. These recoveries after the removal of ILs are slightly higher than the results for dimethyl disulfide (DMSO), another cryoprotectant. The present results indicate that concentrated aqueous IL solutions have potential as one-pot (i.e., solubilization/preservation/refolding) solvents for proteins, which easily aggregate after purification, with comparable results to DMSO.

Oil-soluble and water-soluble BTPhens and their europium complexes in octanol/water solutions: interface crossing studied by MD and PMF simulations.

PubMed

Benay, G; Wipff, G

2013-01-31

Bistriazinyl-phenantroline "BTPhen" ligands L display the remarkable feature to complex trivalent lanthanide and actinide ions, with a marked selectivity for the latter. We report on molecular dynamics studies of tetrasubstituted X(4)BTPhens: L(4+) (X = (+)Et(3)NCH(2)-), L(4-) (X = (-)SO(3)Ph-), and L(0) (X = CyMe(4)) and their complexes with Eu(III) in binary octanol/water solutions. Changes in free energies upon interface crossing are also calculated for typical solutes by potential of mean force PMF simulations. The ligands and their complexes partition, as expected, to either the aqueous or the oil phase, depending on the "solubilizing" group X. Furthermore, most of them are found to be surface active. The water-soluble L(4+) and L(4-) ligands and their (L)Eu(NO(3))(3) complexes adsorb at the aqueous side of the interface, more with L(4-) than with L(4+). The oil soluble ligand L(0) is not surface active in its endo-endo form but adsorbs on the oil side of the interface in its most polar endo-exo form, as well as in its protonated L(0)H(+) and complexed (L(0))Eu(NO(3))(3) states. Furthermore, comparing PMFs of the Eu(III) complexes with and without nitric acid shows that acidifying the aqueous phase has different effects, depending on the ligand charge. In particular, acid promotes the Eu(III) extraction by L(0) via the (L(0))(2)Eu(NO(3))(2+) complex, as observed experimentally. Overall, the results point to the importance of interfacial adsorption for the liquid-liquid extraction of trivalent lanthanide and actinide cations by BTPhens and analogues.

Prediction the concentration of graphite direct exfoliation by liquid solution with solubility parameters map

NASA Astrophysics Data System (ADS)

Liang, Ko-Yuan; Yang, Wein-Duo

2018-01-01

This study is to discuss solvent selection with graphene dispersion concentration of directly exfoliation graphite. That limiting boundaries of fractional cohesion parameters will be draw on the triangular diagram to prediction and estimate. It is based on the literature of data and check with experimental or other literature results, include organic solution, aqueous solution and ionic liquid. In this work, we found that estimated the graphene dispersion concentration by distance (Ra) of Hansen solubility parameters (HSP) between graphene and solvent, the lower Ra; the higher concentration, some case the lower Ra; the lower dispersion concentration (such as acetone). It is compatible with the graphene dispersion concentration on the Hansen space or Triangular fractional cohesion parameters dispersion diagram. From Triangular fractional cohesion parameters dispersion diagram, 2D maps are more convenient for researchers than 3D maps of Hansen space and quickly to find the appropriate combination of solvents for different application.

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.

Determination of the solubility of inorganic salts by headspace gas chromatography.

PubMed

Chai, X S; Zhu, J Y

2003-05-09

This work reports a novel method for determination of salt solubility using headspace gas chromatography. A very small amount of volatile compound (such as methanol) is added in the studied solution. Due to the molecular interaction in the solution, the vapor-liquid equilibrium (VLE) partitioning coefficient of the volatile species will change with different salt contents in the solution. Therefore, the concentration of volatile species in the vapor phase is proportional to the salt concentration in the liquid phase, which can be easily determined by headspace gas chromatography. Until the salt concentration in the solution is saturated, the concentration of volatile compound in the vapor phase will continue to increase further and a breakpoint will appear on the VLE curve. The solubility of the salts can be determined by the identification of the breakpoint. It was found that the measured solubility of sodium carbonate and sodium sulfate in aqueous solutions is slightly higher (about 6-7%) than those reported in the literature method. The present method can be easily applied to industrial solution systems.

Ionic depletion at the crystalline Gibbs layer of PEG-capped gold nanoparticle brushes at aqueous surfaces

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

Wang, Wenjie; Zhang, Honghu; Mallapragada, Surya

In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolated-polyethylene-glycol–capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs 2SO 4) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray scattering. In conclusion, by taking advantage of element specificity with the GIXFS method, we find that the cation Cs + concentration at the crystalline film is significantly reduced in parts of the PEG-AuNP film comparedmore » with that in the bulk.« less

Removal of Congo Red from Aqueous Solution by Anion Exchange Membrane (EBTAC): Adsorption Kinetics and Themodynamics.

PubMed

Khan, Muhammad Imran; Akhtar, Shahbaz; Zafar, Shagufta; Shaheen, Aqeela; Khan, Muhammad Ali; Luque, Rafael; Rehman, Aziz Ur

2015-07-08

The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid film diffusion and Elovich models as well as Bangham and modified freundlich Equations, were employed to evaluate the experimental results. Parameters such as adsorption capacities, rate constant and related correlation coefficients for every model were calculated and discussed. The adsorption of CR on anion exchange membranes followed pseudo-second-order Kinetics. Thermodynamic parameters, namely changes in Gibbs free energy ( ∆G° ), enthalpy ( ∆H° ) and entropy ( ∆S° ) were calculated for the adsorption of congo red, indicating an exothermic process.

Removal of Congo Red from Aqueous Solution by Anion Exchange Membrane (EBTAC): Adsorption Kinetics and Themodynamics

PubMed Central

Khan, Muhammad Imran; Akhtar, Shahbaz; Zafar, Shagufta; Shaheen, Aqeela; Khan, Muhammad Ali; Luque, Rafael; ur Rehman, Aziz

2015-01-01

The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid film diffusion and Elovich models as well as Bangham and modified freundlich Equations, were employed to evaluate the experimental results. Parameters such as adsorption capacities, rate constant and related correlation coefficients for every model were calculated and discussed. The adsorption of CR on anion exchange membranes followed pseudo-second-order Kinetics. Thermodynamic parameters, namely changes in Gibbs free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) were calculated for the adsorption of congo red, indicating an exothermic process. PMID:28793430

Delay in the Freezing of Supercooled Water Drops on Superhydrophobic Surfaces of Silicone Rubber at Negative Temperatures

NASA Astrophysics Data System (ADS)

Bezdomnikov, A. A.; Emel'yanenko, A. M.; Emel'yanenko, K. A.; Boinovich, L. B.

2018-01-01

A method is proposed for fabricating textured superhydrophobic surfaces of silicone rubber with mechanical resistance toward liquid or freezing aqueous solutions. The anti-icing characteristics of silicone rubber samples that differ in the wetting characteristics and mechanical stability of their micro- and nanotextures are derived by analyzing the delays in the freezing of supercooled sessile water drops deposited on the sample surface. The longest delay in freezings are observed for sessile water drops on superhydrophobic surfaces prepared by laser texturing with subsequent application of a layer of a hydrophobic agent to consolidate the textural elements. Delay in freezings can be as long as tens of hours on such surfaces at T = -18°C. The prepared superhydrophobic surfaces exhibit greater anti-icing ability with respect to aqueous salt solutions than to deionized water.

Removal of hexavalent chromium by biosorption process in rotating packed bed.

PubMed

Panda, M; Bhowal, A; Datta, S

2011-10-01

Removal of hexavalent chromium ions from an aqueous solution by crude tamarind (Tamarindus indica) fruit shell was examined in a rotating packed bed contactor by continuously recirculating a given volume of solution through the bed. Reduction of Cr(VI) to Cr(III) within the biosorbent appeared to be the removal mechanism. Depletion rate of Cr(VI) from, and release of reduced Cr(III) ions into the aqueous phase, was influenced by mass transfer resistance besides pH and packing depth. A mathematical model considering the reduction reaction to be irreversible and incorporating intraparticle and external phase mass transfer resistances represented the experimental data adequately. The study indicated that the limitations of fixed bed contactor operating under terrestrial gravity in intensifying mass transfer rates for this system can be overcome with rotating packed bed due to liquid flow under centrifugal acceleration.

A new technique for collection, concentration and determination of gaseous tropospheric formaldehyde

NASA Astrophysics Data System (ADS)

Cofer, Wesley R.; Edahl, Robert A.

This article describes an improved technique for making in situ measurements of gaseous tropospheric formaldehyde (CH 2O). The new technique is based on nebulization/reflux principles that have proved very effective in quantitatively scrubbing water soluble trace gases (e.g. CH 2O) into aqueous mediums, which are subsequently analyzed. Atmospheric formaldehyde extractions and analyses have been performed with the nebulization/reflux concentrator using an acidified dinitrophenylhydrazine solution that indicate that quantitative analysis of CH 2O at global background levels (˜ 0.1 ppbv) is feasible with 20-min extractions. Analysis of CH 2O, once concentrated, is accomplished using high performance liquid chromatography (HPLC) with ultraviolet photometric detection. The CH 2O-hydrazone derivative, produced by the reaction of 2,4-dinitrophenylhydrazine in H 2SO 4 acidified aqueous solution, is detected as CH 2O.

Ionic depletion at the crystalline Gibbs layer of PEG-capped gold nanoparticle brushes at aqueous surfaces

DOE PAGES

Wang, Wenjie; Zhang, Honghu; Mallapragada, Surya; ...

2017-12-14

In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolated-polyethylene-glycol–capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs 2SO 4) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray scattering. In conclusion, by taking advantage of element specificity with the GIXFS method, we find that the cation Cs + concentration at the crystalline film is significantly reduced in parts of the PEG-AuNP film comparedmore » with that in the bulk.« less

Gamma-irradiation of malic acid in aqueous solutions. [prebiotic significance

NASA Technical Reports Server (NTRS)

Negron-Mendoza, A.; Graff, R. L.; Ponnamperuma, C.

1980-01-01

The gamma-irradiation of malic acid in aqueous solutions was studied under initially oxygenated and oxygen-free conditions in an attempt to determine the possible interconversion of malic acid into other carboxylic acids, specifically those associated with Krebs cycle. The effect of dose on product formation of the system was investigated. Gas-liquid chromatography combined with mass spectrometry was used as the principal means of identification of the nonvolatile products. Thin layer chromatography and direct probe mass spectroscopy were also employed. The findings show that a variety of carboxylic acids are formed, with malonic and succinic acids in greatest abundance. These products have all been identified as being formed in the gamma-irradiation of acetic acid, suggesting a common intermediary. Since these molecules fit into a metabolic cycle, it is strongly suggestive that prebiotic pathways provided the basis for biological systems.

Water Interfaces, Solvation, and Spectroscopy

NASA Astrophysics Data System (ADS)

Geissler, Phillip L.

2013-04-01

Liquid water consistently expands our appreciation of the rich statistical mechanics that can emerge from simple molecular constituents. Here I review several interrelated areas of recent work on aqueous systems that aim to explore and explain this richness by revealing molecular arrangements, their thermodynamic origins, and the timescales on which they change. Vibrational spectroscopy of OH stretching features prominently in these discussions, with an emphasis on efforts to establish connections between spectroscopic signals and statistics of intermolecular structure. For bulk solutions, the results of these efforts largely verify and enrich existing physical pictures of hydrogen-bond network connectivity, dynamics, and response. For water at interfaces, such pictures are still emerging. As an important example I discuss the solvation of small ions at the air-water interface, whose surface propensities challenge a basic understanding of how aqueous fluctuations accommodate solutes in heterogeneous environments.

A new technique for collection, concentration and determination of gaseous tropospheric formaldehyde

NASA Technical Reports Server (NTRS)

Cofer, W. R., III; Edahl, R. A., Jr.

1986-01-01

This article describes an improved technique for making in situ measurements of gaseous tropospheric formaldehyde (CH2O). The new technique is based on nebulization/reflux principles that have proved very effective in quantitatively scrubbing water soluble trace gases (e.g., CH2O) into aqueous mediums, which are subsequently analyzed. Atmospheric formaldehyde extractions and analyses have been performed with the nebulization/reflux concentrator using an acidified dinitrophenylhydrazine solution that indicate that quantitative analysis of CH2O at global background levels (about 0.1 ppbv) is feasible with 20-min extractions. Analysis of CH2O, once concentrated, is accomplished using high performance liquid chromatography with ultraviolet photometric detection. The CH2O-hydrazone derivative, produced by the reaction of 2,4-dinitrophenylhydrazine in H2SO4 acidified aqueous solution, is detected as CH2O.

Naked Gold Nanoparticles and hot Electrons in Water.

PubMed

Ghandi, Khashayar; Wang, Furong; Landry, Cody; Mostafavi, Mehran

2018-05-08

The ionizing radiation in aqueous solutions of gold nanoparticles, stabilized by electrostatic non-covalent intermolecular forces and steric interactions, with antimicrobial compounds, are investigated with picosecond pulse radiolysis techniques. Upon pulse radiolysis of an aqueous solution containing very low concentrations of gold nanoparticles with naked surfaces available in water (not obstructed by chemical bonds), a change to Cerenkov spectrum over a large range of wavelengths are observed and pre-solvated electrons are captured by gold nanoparticles exclusively (not by ionic liquid surfactants used to stabilize the nanoparticles). The solvated electrons are also found to decay rapidly compared with the decay kinetics in water. These very fast reactions with electrons in water could provide an enhanced oxidizing zone around gold nanoparticles and this could be the reason for radio sensitizing behavior of gold nanoparticles in radiation therapy.

A Study of the γ-Radiolysis of N,N-Didodecyl-N',N'-Dioctyldiglycolamide Using UHPLC-ESI-MS Analysis

DOE PAGES

Roscioli-Johnson, Kristyn M.; Zarzana, Christopher A.; Groenewold, Gary S.; ...

2016-07-12

In this paper, solutions of N,N-didodecyl-N',N'-dioctyldiglycolamide in n-dodecane were subjected to γ-irradiation in the presence and absence of both an aqueous nitric acid phase and air sparging. The solutions were analyzed using ultra-high-performance liquid chromatography-electrospray ionization-mass spectrometry (UHPLC-ESI-MS) to determine the rates of radiolytic decay of the extractant as well as to identify radiolysis products. The DGA concentration decreased exponentially with increasing dose, and the measured degradation rate constants were uninfluenced by the presence or absence of acidic aqueous phase, or by air sparging. Finally, the identified radiolysis products suggest that the bonds most vulnerable to radiolytic attack are thosemore » in the diglycolamide center of these molecules and not in the side chains.« less

Degradation of atrazine by microwave-assisted electrodeless discharge mercury lamp in aqueous solution.

PubMed

Ta, Na; Hong, Jun; Liu, Tingfeng; Sun, Cheng

2006-11-02

The present study investigates the degradation of atrazine (2-chloro-4-(ethyl amino)-6-isopropyl amino-s-triazine) in aqueous solution by a developed new method, namely by means of a microwave-assisted electrodeless discharge mercury lamp (MW-EDML). An experimental design was conducted to assess the influence of various parameters: pH value, initial concentration, amount of EDML, initial volume and coexisted solvent. Atrazine was degraded completely by EDML in a relatively short time (i.e. t(1/2)=1.2 min for 10 mg/l). Additionally, the identification of main degradation products during atrazine degradation process was conducted by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). This study proposes the degradation mechanism including four possible pathways for atrazine degradation according to the degradation products.

Control of aqueous droplets using magnetic and electrostatic forces.

PubMed

Ohashi, Tetsuo; Kuyama, Hiroki; Suzuki, Koichi; Nakamura, Shin

2008-04-07

Basic control operations were successfully performed on an aqueous droplet using both magnetic and electrostatic forces. In our droplet-based microfluidics, magnetic beads were incorporated in an aqueous droplet as a force mediator. This report describes droplet anchoring and separation of the beads from the droplet using a combination of magnetic and electrostatic forces. When an aqueous droplet is placed in an oil-filled reservoir, the droplet sinks to the bottom, under which an electrode had been placed. The droplet was adsorbed (or anchored) to the bottom surface on the electrode when a DC voltage was applied to the electrode. The magnetic beads were removed with magnetic force after the droplet had been anchored. Surfactant addition into droplet solution was very effective for the elimination of electric charge, which resulted in the stable adsorption of a droplet to hydrophobic substrate under an applied voltage of DC 0.5-3 kV. In a sequential process, small volume of aqueous liquid was successfully transferred using both magnetic and electrostatic forces.

Fabrication of ionic liquid electrodeposited Cu--Sn--Zn--S--Se thin films and method of making

DOEpatents

Bhattacharya, Raghu Nath

2016-01-12

A semiconductor thin-film and method for producing a semiconductor thin-films comprising a metallic salt, an ionic compound in a non-aqueous solution mixed with a solvent and processing the stacked layer in chalcogen that results in a CZTS/CZTSS thin films that may be deposited on a substrate is disclosed.

New formaldehyde base disinfectants.

NASA Technical Reports Server (NTRS)

Trujillo, R.; Lindell, K. F.

1973-01-01

Preparations of formaldehyde in various organic liquids - ethylene glycol, glycerol, and propylene glycol - serve as effective disinfectants towards microbial vegetative cells and spores. This disinfection is a temperature-dependent process and is manifest when these formaldehyde base disinfectants are dissolved in water. The irritating vapors associated with formaldehyde disinfection are not present in either of these new formaldehyde base disinfectants or in aqueous solutions of them.

Milliscale Self-Integration of Megamolecule Biopolymers on a Drying Gas-Aqueous Liquid Crystalline Interface.

PubMed

Okeyoshi, Kosuke; Okajima, Maiko K; Kaneko, Tatsuo

2016-06-13

A drying environment is always a proposition faced by dynamic living organisms using water, which are driven by biopolymer-based micro- and macrostructures. Here, we introduce a drying process for aqueous liquid crystalline (LC) solutions composed of biopolymer with extremely high molecular weight components such as polysaccharides, cytoskeletal proteins, and DNA. On controlling the mobility of the LC microdomain, the solutions showed milliscale self-integration starting from the unstable gas-LC interface during drying. In particular, we first identified giant rod-like microdomains (∼1 μm diameter and more than 20 μm length) of the mega-molecular polysaccharide, sacran, which is remarkably larger than other polysaccharides. These microdomains led to the formation of a single milliscale macrodomain on the interface. In addition, the dried polymer films on a solid substrate also revealed that such integration depends on the size of the microdomain. We envision that this simple drying method will be useful not only for understanding the biopolymer hierarchization at the macroscale level but also for preparation of surfaces with direction controllability, as seen in living organisms, for use in various fields such as diffusion, mechanics, and photonics.

Solubilities of carbon dioxide in aqueous potassium carbonate solutions mixed with physical solvents

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

Park, S.B.; Lee, H.; Lee, K.H.

1998-09-01

The removal of acidic gases such as CO{sub 2}, H{sub 2}S, and COS from gas streams is a very important operation for petrochemical, oil refineries, ammonia manufacture, coal gasification, and natural gas purification plants. Here, the solubilities of carbon dioxide in aqueous potassium carbonate (K{sub 2}CO{sub 3}) solutions mixed with physical solvents were measured at 298.2 and 323.2 K with a CO{sub 2} partial-pressure range of 5 kPa to 2 MPa. 1,2-propanediol and propylene carbonate were selected as physical solvents. The aqueous solutions treated in this study were 5 mass% K{sub 2}CO{sub 3}-15 mass% 1,2-propanediol and propylene carbonate were selectedmore » as physical solvents. The aqueous solutions treated in this study were 5 mass% K{sub 2}CO{sub 3}-15 mass% propylene carbonate. The experimental solubility results were presented by the mole ratio of CO{sub 2} and K{sub 2}CO{sub 3} contained in the liquid mixture. The addition of 1,2-propanediol to 5 mass% K{sub 2}CO{sub 3} solution lowered the solubility of CO{sub 2} at constant temperature and pressure conditions when CO{sub 2} partial-pressure range of 5 kPa to 2 MPa. In the case of propylene carbonate the addition of propylene carbonate increased the experimental solubilities in the region of low CO{sub 2} partial pressures and decreased as the CO{sub 2} partial pressure was increased above atmospheric. The solubilities of CO{sub 2} decreased with increasing temperature in the range of 298.2 to 323.2 K.« less

The effect of the corneal epithelium on the intraocular penetration of fluoroquinolone ophthalmic solution.

PubMed

Fukuda, Masamichi; Inoue, Amane; Sasaki, Kazuyuki; Takahashi, Nobuo

2004-01-01

Pharmacokinetic studies of antibacterial agents for infectious eye diseases have usually been performed on normal rabbit eyes. In this study, the intraocular penetration of fluoroquinolone ophthalmic solutions was determined in normal rabbit eyes and in rabbit eyes that had the corneal epithelium intentionally removed. We determined the intraocular penetration of ofloxacin (OFLX), levofloxacin (LVFX), and norfloxacin (NFLX), fluoroquinolone ophthalmic solutions that are already on the market and undergoing clinical studies, by injecting 50 microl of each solution into the cul-de-sacs of rabbit eyes three times at 15-min intervals. The drug concentration at 10, 30, 60, 120, and 240 min after final instillation was determined by high-performance liquid chromatography. The maximum concentration in the aqueous humor of normal rabbit eyes was 2.09 +/- 1.56 microg/ml (60 min, OFLX), 2.57 +/- 1.00 microg/ml (30 min, LVFX), and 0.42 +/- 0.12 microg/ml (120 min, NFLX). The drug concentration in the aqueous humor of eyes with intentionally removed corneal epithelium was 12.50 +/- 5.62 microg/ml (30 min, OFLX), 9.02 +/- 2.45 microg/ml (60 min, LVFX), and 8.54 +/- 5.17 microg/ml (30 min, NFLX). The drug penetration of the eye drops into eyes with removed corneal epithelium was around 6 times (OFLX), 3.5 times (LVFX), and 20 times (NFLX) higher than the penetration into the eye with normal cornea. Among the pharmacokinetic parameters of the three ophthalmic solutions according to the one-compartment model, the maximum concentration in the aqueous and the area under the concentration-time curve in the aqueous tended to be higher in the eyes with intentionally removed corneal epithelia than in those with normal corneas.

Quantitative interpretation of molecular dynamics simulations for X-ray photoelectron spectroscopy of aqueous solutions

NASA Astrophysics Data System (ADS)

Olivieri, Giorgia; Parry, Krista M.; Powell, Cedric J.; Tobias, Douglas J.; Brown, Matthew A.

2016-04-01

Over the past decade, energy-dependent ambient pressure X-ray photoelectron spectroscopy (XPS) has emerged as a powerful analytical probe of the ion spatial distributions at the vapor (vacuum)-aqueous electrolyte interface. These experiments are often paired with complementary molecular dynamics (MD) simulations in an attempt to provide a complete description of the liquid interface. There is, however, no systematic protocol that permits a straightforward comparison of the two sets of results. XPS is an integrated technique that averages signals from multiple layers in a solution even at the lowest photoelectron kinetic energies routinely employed, whereas MD simulations provide a microscopic layer-by-layer description of the solution composition near the interface. Here, we use the National Institute of Standards and Technology database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to quantitatively interpret atom-density profiles from MD simulations for XPS signal intensities using sodium and potassium iodide solutions as examples. We show that electron inelastic mean free paths calculated from a semi-empirical formula depend strongly on solution composition, varying by up to 30% between pure water and concentrated NaI. The XPS signal thus arises from different information depths in different solutions for a fixed photoelectron kinetic energy. XPS signal intensities are calculated using SESSA as a function of photoelectron kinetic energy (probe depth) and compared with a widely employed ad hoc method. SESSA simulations illustrate the importance of accounting for elastic-scattering events at low photoelectron kinetic energies (<300 eV) where the ad hoc method systematically underestimates the preferential enhancement of anions over cations. Finally, some technical aspects of applying SESSA to liquid interfaces are discussed.

Development of a new microextraction method based on elevated temperature dispersive liquid-liquid microextraction for determination of triazole pesticides residues in honey by gas chromatography-nitrogen phosphorus detection.

PubMed

Farajzadeh, Mir Ali; Mogaddam, Mohammad Reza Afshar; Ghorbanpour, Houshang

2014-06-20

In the present study, a rapid, highly efficient, and reliable sample preparation method named "elevated temperature dispersive liquid-liquid microextraction" followed by gas chromatography-nitrogen-phosphorus detection was developed for the extraction, preconcentration, and determination of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, and difenoconazole) in honey samples. In this method the temperature of high-volume aqueous phase was adjusted at an elevated temperature and then a disperser solvent containing an extraction solvent was rapidly injected into the aqueous phase. After cooling to room temperature, the phase separation was accelerated by centrifugation. Various parameters affecting the extraction efficiency such as type and volume of the extraction and disperser solvents, temperature, salt addition, and pH were evaluated. Under the optimum extraction conditions, the method resulted in low limits of detection and quantification within the range 0.05-0.21ngg(-1) in honey (15-70ngL(-1) in solution) and 0.15-1.1ngg(-1) in honey (45-210ngL(-1) in solution), respectively. Enrichment factors and extraction recoveries were in the ranges of 1943-1994 and 97-100%, respectively. The method precision was evaluated at 1.5ngg(-1) of each analyte, and the relative standard deviations were found to be less than 4% for intra-day (n=6) and less than 6% for inter-days. The method was successfully applied to the analysis of honey samples and difenoconazole was determined at ngg(-1) levels. Copyright © 2014 Elsevier B.V. All rights reserved.

An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation.

PubMed

Gorbanev, Yury; Soriano, Robert; O'Connell, Deborah; Chechik, Victor

2016-11-03

Non-thermal atmospheric pressure ('cold') plasmas have received increased attention in recent years due to their significant biomedical potential. The reactions of cold plasma with the surrounding atmosphere yield a variety of reactive species, which can define its effectiveness. While efficient development of cold plasma therapy requires kinetic models, model benchmarking needs empirical data. Experimental studies of the source of reactive species detected in aqueous solutions exposed to plasma are still scarce. Biomedical plasma is often operated with He or Ar feed gas, and a specific interest lies in investigation of the reactive species generated by plasma with various gas admixtures (O2, N2, air, H2O vapor, etc.) Such investigations are very complex due to difficulties in controlling the ambient atmosphere in contact with the plasma effluent. In this work, we addressed common issues of 'high' voltage kHz frequency driven plasma jet experimental studies. A reactor was developed allowing the exclusion of ambient atmosphere from the plasma-liquid system. The system thus comprised the feed gas with admixtures and the components of the liquid sample. This controlled atmosphere allowed the investigation of the source of the reactive oxygen species induced in aqueous solutions by He-water vapor plasma. The use of isotopically labelled water allowed distinguishing between the species originating in the gas phase and those formed in the liquid. The plasma equipment was contained inside a Faraday cage to eliminate possible influence of any external field. The setup is versatile and can aid in further understanding the cold plasma-liquid interactions chemistry.

An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation

PubMed Central

Gorbanev, Yury; Soriano, Robert; O'Connell, Deborah; Chechik, Victor

2016-01-01

Non-thermal atmospheric pressure ('cold') plasmas have received increased attention in recent years due to their significant biomedical potential. The reactions of cold plasma with the surrounding atmosphere yield a variety of reactive species, which can define its effectiveness. While efficient development of cold plasma therapy requires kinetic models, model benchmarking needs empirical data. Experimental studies of the source of reactive species detected in aqueous solutions exposed to plasma are still scarce. Biomedical plasma is often operated with He or Ar feed gas, and a specific interest lies in investigation of the reactive species generated by plasma with various gas admixtures (O2, N2, air, H2O vapor, etc.) Such investigations are very complex due to difficulties in controlling the ambient atmosphere in contact with the plasma effluent. In this work, we addressed common issues of 'high' voltage kHz frequency driven plasma jet experimental studies. A reactor was developed allowing the exclusion of ambient atmosphere from the plasma-liquid system. The system thus comprised the feed gas with admixtures and the components of the liquid sample. This controlled atmosphere allowed the investigation of the source of the reactive oxygen species induced in aqueous solutions by He-water vapor plasma. The use of isotopically labelled water allowed distinguishing between the species originating in the gas phase and those formed in the liquid. The plasma equipment was contained inside a Faraday cage to eliminate possible influence of any external field. The setup is versatile and can aid in further understanding the cold plasma-liquid interactions chemistry. PMID:27842375

Quantum dots and ionic liquid-sensitized effect as an efficient and green catalyst for the sensitive determination of glucose.

PubMed

Azizi, Seyed Naser; Chaichi, Mohammad Javad; Shakeri, Parmis; Bekhradnia, Ahmadreza

2015-07-05

A novel fluorescence (FL) method using water-soluble CdSe quantum dots (QDs) is proposed for the fluorometric determination of hydrogen peroxide and glucose. Water-soluble CdSe QDs were synthesized by using thioglycolic acid as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy, photoluminescence (PL) emission spectroscopy and transmission electron microscope (TEM). Ionic liquid-sensitized effect in aqueous solution was then investigated. In the presence of ionic liquid as catalyst, H2O2 was decomposed into radical that could quench the fluorescence of CdSe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdSe QDs by H2O2 producer with ionic liquid catalyst, which can be used to detect glucose. Therefore, a new FL analysis system was developed for the determination of glucose. Under the optimum conditions, there is a good linear relationship between the relative PL emission intensity and the concentration of glucose in the range of 5.0×10(-7)-1.0×10(-4) M of glucose with a correlation coefficient (R(2)) of 0.9973. The limit of detection of this system was found to be 1.0×10(-7) M. This method is not only simple, sensitive and low cost, but also reliable for practical applications. Copyright © 2015. Published by Elsevier B.V.