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Sample records for carbonic acid solution

  1. Reduction of Plutonium in Acidic Solutions by Mesoporous Carbons

    DOE PAGESBeta

    Parsons-Moss, Tashi; Jones, Stephen; Wang, Jinxiu; Wu, Zhangxiong; Uribe, Eva; Zhao, Dongyuan; Nitsche, Heino

    2015-12-19

    Batch contact experiments with several porous carbon materials showed that carbon solids spontaneously reduce the oxidation state of plutonium in 1-1.5 M acid solutions, without significant adsorption. The final oxidation state and rate of Pu reduction varies with the solution matrix, and also depends on the surface chemistry and surface area of the carbon. It was demonstrated that acidic Pu(VI) solutions can be reduced to Pu(III) by passing through a column of porous carbon particles, offering an easy alternative to electrolysis with a potentiostat.

  2. Adsorption of organic acids from dilute aqueous solution onto activated carbon

    SciTech Connect

    Wang, S.W.

    1980-06-01

    The radioisotope technique was used to study the removal of organic acid contaminants from dilute aqueous solutions onto activated carbon. Acetic acid, propionic acid, n-butyric acid, n-hexanoic acid and n-heptanoic acid were studied at 278, 298, and 313/sup 0/K. Three bi-solute acid mixtures (acetic and propionic acids, acetic and butanoic acids, and propionic and butanoic acids) were studied at 278 and 298/sup 0/K. Isotherms of the single-solute systems were obtained at three different temperatures in the very dilute concentration region (less than 1% by weight). These data are very important in the prediction of bi-solute equilibrium data. A Polanyi-based competitive adsorption potential theory was used to predict the bi-solute equilibrium uptakes. Average errors between calculated and experimental data ranges from 4% to 14%. It was found that the competitive adsorption potential theory gives slightly better results than the ideal adsorbed solution theory.

  3. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson (Castro Valley, CA)

    2012-05-15

    A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

  4. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    SciTech Connect

    Rau, Gregory Hudson

    2014-07-01

    A system for forming metal hydroxide from a metal carbonate utilizes a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide.

  5. Extraction of palladium from acidic solutions with the use of carbon adsorbents

    SciTech Connect

    O.N. Kononova; N.G. Goryaeva; N.B. Dostovalova; S.V. Kachin; A.G. Kholmogorov

    2007-08-15

    We studied the sorption of palladium(II) on LKAU-4, LKAU-7, and BAU carbon adsorbents from model hydrochloric acid solutions and the solutions of spent palladium-containing catalysts. It was found that sorbents based on charcoal (BAU) and anthracite (LKAU-4) were characterized by high sorption capacities for palladium. The kinetics of the saturation of carbon adsorbents with palladium(II) ions was studied, and it was found that more than 60% of the initial amount of Pd(II) was recovered in a 1-h contact of an adsorbent with a model solution. This value for the solutions of spent catalysts was higher than 35%.

  6. Inhibition Effect of Dodecylamine on Carbon Steel Corrosion in Hydrochloric Acid Solution

    NASA Astrophysics Data System (ADS)

    Chen, Zhenyu; Huang, Ling; Qiu, Yubing; Guo, Xingpeng

    2012-12-01

    Dodecylamine spontaneously adsorbs on carbon steel via its polar group (-NH2) in hydrochloric acid solution. Furthermore, it forms a monolayer film on carbon steel surface. The inhibition mechanism of dodecylamine for carbon steel is geometric blocking effect. The adsorption of dodecylamine on carbon steel surface follows Arrhenius equation. The adsorption slightly increases activated energy, but greatly reduces pre-exponential factor value. Atomic force microscopy force curves indicate that at the area without adsorbed dodecylamine, no obvious adhere force occurs. At the area with adsorbed dodecylamine, however, an average 1.3 nN adhere force is observed.

  7. Collagen tissue treated with chitosan solutions in carbonic acid for improved biological prosthetic heart valves.

    PubMed

    Gallyamov, Marat O; Chaschin, Ivan S; Khokhlova, Marina A; Grigorev, Timofey E; Bakuleva, Natalia P; Lyutova, Irina G; Kondratenko, Janna E; Badun, Gennadii A; Chernysheva, Maria G; Khokhlov, Alexei R

    2014-04-01

    Calcification of bovine pericardium dramatically shortens typical lifetimes of biological prosthetic heart valves and thus precludes their choice for younger patients. The aim of the present work is to demonstrate that the calcification is to be mitigated by means of treatment of bovine pericardium in solutions of chitosan in carbonic acid, i.e. water saturated with carbon dioxide at high pressure. This acidic aqueous fluid unusually combines antimicrobial properties with absolute biocompatibility as far as at normal pressure it decomposes spontaneously and completely into H2O and CO2. Yet, at high pressures it can protonate and dissolve chitosan materials with different degrees of acetylation (in the range of 16-33%, at least) without any further pretreatment. Even exposure of the bovine pericardium in pure carbonic acid solution without chitosan already favours certain reduction in calcification, somewhat improved mechanical properties, complete biocompatibility and evident antimicrobial activity of the treated collagen tissue. The reason may be due to high extraction ability of this peculiar compressed fluidic mixture. Moreover, exposure of the bovine pericardium in solutions of chitosan in carbonic acid introduces even better mechanical properties and highly pronounced antimicrobial activity of the modified collagen tissue against adherence and biofilm formation of relevant Gram-positive and Gram-negative strains. Yet, the most important achievement is the detected dramatic reduction in calcification for such modified collagen tissues in spite of the fact that the amount of the thus introduced chitosan is rather small (typically ca. 1wt.%), which has been reliably detected using original tritium labelling method. We believe that these improved properties are achieved due to particularly deep and uniform impregnation of the collagen matrix with chitosan from its pressurised solutions in carbonic acid. PMID:24582232

  8. Interaction of organic acids with carbonate mineral surfaces in seawater and related solutions

    SciTech Connect

    Zullig, J.J.; Morse, J.W. )

    1988-06-01

    The adsorption of C{sub 4} to C{sub 18} fatty acid anion homologs from seawater and related solutions was examined on calcite, aragonite, dolomite and magnesite surfaces. Butyrate, octanoate and laurate did not adsorb, while myristate, palmitate and stearate absorbed on all carbonate surfaces. An increasing affinity for carbonate surfaces was found with increasing alkyl chain length for these fatty acids. Adsorption at low concentrations typical of marine waters is controlled by surface adsorption sites. At high concentration adsorption is governed by solution composition and limited by aqueous solubility. Adsorption-desorption reactions were characterized by a large resistant component that resulted in nonsingular isotherms. Myristate adsorption was enhanced in the presence of stearate cosorption. Orthophosphate in trace quantities was capable of displacing fatty acids from carbonate surfaces, but contrary to earlier studies, the authors found on major influence from magnesium ion on adsorption. The results of this study are interpreted in terms of a model based on the different types of forces which contribute to adsorption of these organic compounds. This model emphasizes the importance of organic aqueous solubility and the acid function as criteria controlling the adsorption of natural hydrophobic organics with carbonate mineral surfaces in aqueous fluids.

  9. [Studies on carbonization of saccharides by using aqueous solution of various acids].

    PubMed

    Zhang, Xin; He, An-Qi; Kang, Ting-Guo; Xia, Jin-Ming; Weng, Shi-Fu; Xu, Yi-Zhuang; Wu, Jin-Guang

    2014-09-01

    The authors tried to establish an approach to use acids to convert biomass into a fuel with higher carbon content and lower oxygen content in a zero-energy-consumption fashion. Considering that biomass is composed of monosaccharide, we used aqueous solutions of variation acids including hydrochloric acid, sulfuric acid and perchloric acid to treat 2-deoxy-ribose and fructose at ambient temperature and pressure. Black substances were produced after a period of time when 2-deoxy-ribose and fructose were mixed with aqueous solutions containing 8 mol L(-1) acids. The black substance was collected and characterized by using elemental analysis, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Elemental analysis results indicate that the contents of carbon increases significantly in the black substances in comparison with 2-deoxy-ribose and fructose. Moreover, XPS results indicate that the content of oxygen in the black substance undergoes a significant decrease compared with pure 2-deoxy-ribose and fructose. In the XPS spectra, the is peaks of 2-deoxy-ribose, strong sub peak at 286. 05 eV, which is assigned to carbon linked to oxygen directly, dominate in the C is peak envelop. After treatment by HClO4, the peak decreased dramatically. This result also supports the conclusion that the content of oxygen in mono-saccharide is significantly reduced after treatment by acids. In the FTIR spectra of the black substances, strong peaks can be observed around 1 600 cm(-1), indicating that C==C bond is formed in the product. The above results suggest that treatments with acids may be developed as a new zero-energy-consumption approach to convert biomass in a new fuel with improved energy output efficiency. PMID:25532323

  10. Adsorption equilibrium, kinetics and thermodynamics of dichloroacetic acid from aqueous solution using mesoporous carbon.

    PubMed

    Ding, Ying; Zhu, Jianzhong; Cao, Yang; Chen, Shenglu

    2014-08-01

    The presence of disinfection by-products, such as trihalomethanes and haloacetic acids in water, is believed to be harmful to human health. In this work, mesoporous carbon was synthesized with the evaporation-induced self-assembly method and employed to evaluate the effects of initial concentration, contact time, pH and temperature on the removal of dichloroacetic acid in batch experiments. Adsorption equilibrium was established in 480 min and the maximum adsorption (350mg/g) of dichloroacetic acid on the mesoporous carbon was observed to occur at 308 K and pH 3.0. Freundlich and Langmuir isotherms were used to analyse the equilibrium data at different temperatures; kinetic data were fitted to the pseudo-first-order and pseudo-second-order models and found that the adsorption capacity, mass transfer coefficient and diffusivity of dichloroacetic acid were directly affected by the physical and chemical parameters. In addition, the various thermodynamic parameters, such as Gibbs free energy (Delta G), enthalpy (Delta H = 54.35 kJmol-1) and entropy (Delta S = 258.36 Jmol-1 K-1) were calculated to analyse the adsorption process. The experimental results indicated that the mesoporous carbon was an excellent adsorbent for dichloroacetic acid removal from aqueous solutions. PMID:24956790

  11. Generation of soil solution acid-neutralizing capacity by addition of dissolved inorganic carbon

    SciTech Connect

    David, M.B.; Vance, G.F.

    1989-01-01

    A Spodosol B horizon (base saturation of 5.4%) collected at the Watershed Manipulation Project site at Lead Mountain, ME, was used to examine soil solution chemistry in response to increasing solution levels of dissolved inorganic carbon (DIC). Acid-neutralizing capacity (ANC), determined by Gran titration, increased from -5 to 163 mw equiv/L in response to increasing DIC, with a corresponding increase in base cations (Ca2+, Mg2+, K+, and Na+). For the negative ANC solutions, degassing increased solution pH (in equilibrium with atmospheric CO2) slightly from 4.94 to 5.14, whereas solutions with positive ANC showed large pH shifts (e.g., ANC of 69, pH shift from 4.73 to 6.81). Under equilibrium assumptions and log K(sub A1) determined from 2.66pH-pAl, measured values from ANC, sum of cations, pH, and degassed pH were found to be in agreement with predictions from a chemical equilibrium model.

  12. Reactivity of Hontomn carbonate rocks to acidic solution injection: reactive "push-pull" tracer tests results

    NASA Astrophysics Data System (ADS)

    De Gaspari, Francesca; Cabeza, Yoar; Luquot, Linda; Rtting, Tobias; Saaltink, Maarten W.; Carrera, Jesus

    2014-05-01

    Several field tests will be carried out in order to characterize the reservoir for CO2 injection in Hontomn (Burgos, Spain) as part of the Compostilla project of "Fundacin Ciudad de la Energa" (CIUDEN). Once injected, the dissolution of the CO2 in the resident brine will increase the acidity of the water and lead to the dissolution of the rocks, constituted mainly by carbonates. This mechanism will cause changes in the aquifer properties such as porosity and permeability. To reproduce the effect of the CO2 injection, a reactive solution with 2% of acetic acid is going to be injected in the reservoir and extracted from the same well (reactive "push-pull" tracer tests) to identify and quantify the geochemical reactions occurring into the aquifer. The reactivity of the rock will allow us also to evaluate the changes of its properties. Previously, theoretical calculations of Damkhler numbers were done to determine the acid concentrations and injection flow rates needed to generate ramified-wormholes patterns, during theses "push-pull" experiments. The aim of this work is to present the results and a preliminary interpretation of the field tests.

  13. Removal of boron from aqueous solution using magnetic carbon nanotube improved with tartaric acid

    PubMed Central

    2014-01-01

    Boron removal capacity of multi-walled carbon nanotubes (MWCNTs) modified with tartaric acid was investigated in this study. Modification of MWCNTs with tartaric acid was confirmed by Boehm surface chemistry method and fourier transform infra-red (FT-IR) spectroscopy. Experiments were performed to determine the adsorption isotherm and adsorption thermodynamic parameters of boron adsorption on tartaric acid modified MWCNTs (TA-MWCNTs). The effect of variables including initial pH, dosage of adsorbent, contact time and temperature was investigated. Analysis of data showed that adsorption equilibrium could be better described by Freundlich isotherm and the maximum adsorption capacities obtained at the pH of 6.0 was 1.97 mg/g. The estimated thermodynamic values of free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) indicated a spontaneous and an endothermic process. Furthermore, the TA-MWCNTs was magnetized for separation of boron-contaminated adsorbent from aqueous solution by applying magnetic field. The results showed that magnetic TA-MWCNTs particles were separated effectively after adsorption from contaminated water. PMID:24393401

  14. How Acidic Is Carbonic Acid?

    PubMed

    Pines, Dina; Ditkovich, Julia; Mukra, Tzach; Miller, Yifat; Kiefer, Philip M; Daschakraborty, Snehasis; Hynes, James T; Pines, Ehud

    2016-03-10

    Carbonic, lactic, and pyruvic acids have been generated in aqueous solution by the transient protonation of their corresponding conjugate bases by a tailor-made photoacid, the 6-hydroxy-1-sulfonate pyrene sodium salt molecule. A particular goal is to establish the pKa of carbonic acid H2CO3. The on-contact proton transfer (PT) reaction rate from the optically excited photoacid to the carboxylic bases was derived, with unprecedented precision, from time-correlated single-photon-counting measurements of the fluorescence lifetime of the photoacid in the presence of the proton acceptors. The time-dependent diffusion-assisted PT rate was analyzed using the Szabo-Collins-Kimball equation with a radiation boundary condition. The on-contact PT rates were found to follow the acidity order of the carboxylic acids: the stronger was the acid, the slower was the PT reaction to its conjugate base. The pKa of carbonic acid was found to be 3.49 ± 0.05 using both the Marcus and Kiefer-Hynes free energy correlations. This establishes H2CO3 as being 0.37 pKa units stronger and about 1 pKa unit weaker, respectively, than the physiologically important lactic and pyruvic acids. The considerable acid strength of intact carbonic acid indicates that it is an important protonation agent under physiological conditions. PMID:26862781

  15. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    PubMed

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to OH, electro-reduction of O3 to OH at the cathode, and O3 decomposition to OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process. PMID:25989593

  16. Reaction Mechanism for Direct Proton Transfer from Carbonic Acid to a Strong Base in Aqueous Solution I: Acid and Base Coordinate and Charge Dynamics.

    PubMed

    Daschakraborty, Snehasis; Kiefer, Philip M; Miller, Yifat; Motro, Yair; Pines, Dina; Pines, Ehud; Hynes, James T

    2016-03-10

    Protonation by carbonic acid H2CO3 of the strong base methylamine CH3NH2 in a neutral contact pair in aqueous solution is followed via Car-Parrinello molecular dynamics simulations. Proton transfer (PT) occurs to form an aqueous solvent-stabilized contact ion pair within 100 fs, a fast time scale associated with the compression of the acid-base hydrogen-bond (H-bond), a key reaction coordinate. This rapid barrierless PT is consistent with the carbonic acid-protonated base pKa difference that considerably favors the PT, and supports the view of intact carbonic acid as potentially important proton donor in assorted biological and environmental contexts. The charge redistribution within the H-bonded complex during PT supports a Mulliken picture of charge transfer from the nitrogen base to carbonic acid without altering the transferring hydrogen's charge from approximately midway between that of a hydrogen atom and that of a proton. PMID:26879554

  17. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA. PMID:26469934

  18. GENERATION OF SOIL SOLUTION ACID NEUTRALIZING CAPACITY BY ADDITION OF DISSOLVED INORGANIC CARBON

    EPA Science Inventory

    A Spodosol B horizon(base saturation of 5.4%) collected at the Watershed Manipulation Project site at Lead Mountain, ME, was used to examine soil solution chemistry in response to increasing solution levels of dissolved inorganic carbon (DIC). cid-neutralizing capacity (ANC), det...

  19. Carbonate acidizing

    SciTech Connect

    Daccord, G.; Touboul, E.; Lenormand, R.

    1989-02-01

    The authors present the first quantitative study and complete model of the wormholing phenomenon, leading to a means of predicting and optimizing carbonate acidizing treatments. Laboratory experiments on a gypsum model system and computer simulations show that for a given geometry, wormholes can be quantified by a unique parameter, their equivalent hydraulic length. The behavior of this quantifying parameter vs. all the system parameters is studied and allows the quantitative prediction of the efficiency of an acidizing treatment. This study highlights the fractal nature of the phenomenon, which is accounted for in the equations, and the strong effect of the sample geometry. Three types of etching can be obtained: compact, wormhole type, or homogeneous. The optimum conditions for achieving the best skin decrease correspond to the creation of wormholes and can then be defined in terms of fluid reactivity and injection rate.

  20. The adsorption of gold, palladium and platinum from acidic chloride solutions on mesoporous carbons.

    SciTech Connect

    Zalupski, Peter R.; McDowell, Rocklan; Dutech, Guy

    2014-08-05

    Studies on the adsorption characteristics of gold, palladium and platinum on mesoporous carbon (CMK-3) and sulfur-impregnated mesoporous carbon (CMK-3/S) evaluated the benefits/drawbacks of the presence of a layer of elemental sulfur inside mesoporous carbon structures. Adsorption isotherms collected for Au(III), Pd(II) and Pt(IV) on those materials suggest that sulfur does enhance the adsorption of those metal ions in mildly acidic environment (pH 3). The isotherms collected in 1 M HCl show that the benefit of sulfur disappears due to the competing influence of large concentration of hydrogen ions on the ion-exchanging mechanism of metal ions sorption on mesoporous carbon surfaces. The collected acid dependencies illustrate similar adsorption characteristics for CMK-3 and CMK-3/S in 1-5 M HCl concentration range. Sorption of metal ions from diluted aqueous acidic mixtures of actual leached electronic waste demonstrated the feasibility of recovery of gold from such liquors.

  1. The adsorption of gold, palladium and platinum from acidic chloride solutions on mesoporous carbons.

    DOE PAGESBeta

    Zalupski, Peter R.; McDowell, Rocklan; Dutech, Guy

    2014-08-05

    Studies on the adsorption characteristics of gold, palladium and platinum on mesoporous carbon (CMK-3) and sulfur-impregnated mesoporous carbon (CMK-3/S) evaluated the benefits/drawbacks of the presence of a layer of elemental sulfur inside mesoporous carbon structures. Adsorption isotherms collected for Au(III), Pd(II) and Pt(IV) on those materials suggest that sulfur does enhance the adsorption of those metal ions in mildly acidic environment (pH 3). The isotherms collected in 1 M HCl show that the benefit of sulfur disappears due to the competing influence of large concentration of hydrogen ions on the ion-exchanging mechanism of metal ions sorption on mesoporous carbon surfaces.more » The collected acid dependencies illustrate similar adsorption characteristics for CMK-3 and CMK-3/S in 1-5 M HCl concentration range. Sorption of metal ions from diluted aqueous acidic mixtures of actual leached electronic waste demonstrated the feasibility of recovery of gold from such liquors.« less

  2. The adsorption of gold, palladium and platinum from acidic chloride solutions on mesoporous carbons.

    SciTech Connect

    Peter Zalupski; Rocklan McDowell; Guy Dutech

    2014-10-01

    Studies on the adsorption characteristics of gold, palladium and platinum on mesoporous carbon (CMK-3) and sulfur-impregnated mesoporous carbon (CMK-3/S) evaluated the benefits/drawbacks of the presence of a layer of elemental sulfur inside mesoporous carbon structures. Adsorption isotherms collected for Au(III), Pd(II) and Pt(IV) on those materials suggest that sulfur does enhance the adsorption of those metal ions in mildly acidic environment (pH 3). The isotherms collected in 1 M HCl show that the benefit of sulfur disappears due to the competing influence of large concentration of hydrogen ions on the ion-exchanging mechanism of metal ions sorption on mesoporous carbon surfaces. The collected acid dependencies illustrate similar adsorption characteristics for CMK-3 and CMK-3/S in 1-5 M HCl concentration range. Sorption of metal ions from diluted aqueous acidic mixtures of actual leached electronic waste demonstrated the feasibility of recovery of gold from such liquors.

  3. CORROSION TESTING OF CARBON STEEL IN OXALIC ACID CHEMICAL CLEANING SOLUTIONS

    SciTech Connect

    Wiersma, B.; Mickalonis, J.; Subramanian, K.; Ketusky, E.

    2011-10-14

    Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid has been selected for this purpose because it is an effective chelating agent for the solids and is not as corrosive as other acids. Electrochemical and immersion studies were conducted to investigate the corrosion behavior of carbon steel in simulated chemical cleaning environments. The effects of temperature, agitation, and the presence of sludge solids in the oxalic acid on the corrosion rate and the likelihood of hydrogen evolution were determined. The testing showed that the corrosion rates decreased significantly in the presence of the sludge solids. Corrosion rates increased with agitation, however, the changes were less noticeable.

  4. ELECTROCHEMICAL STUDIES ON THE CORROSION OF CARBON STEEL IN OXALIC ACID CLEANING SOLUTIONS

    SciTech Connect

    Wiersma, B; John Mickalonis, J

    2007-10-08

    The Savannah River Site (SRS) will disperse or dissolve precipitated metal oxides as part of radioactive waste tank closure operations. Previously SRS has utilized oxalic acid to accomplish this task. Since the waste tanks are constructed of carbon steel, a significant amount of corrosion may occur. Although the total amount of corrosion may be insignificant for a short contact time, a significant amount of hydrogen may be generated due to the corrosion reaction. Linear polarization resistance and anodic/cathodic polarization tests were performed to investigate the corrosion behavior during the process. The effect of process variables such as temperature, agitation, aeration, sample orientation, light as well as surface finish on the corrosion behavior were evaluated. The results of the tests provided insight into the corrosion mechanism for the iron-oxalic acid system.

  5. Acceleration of suspending single-walled carbon nanotubes in BSA aqueous solution induced by amino acid molecules.

    PubMed

    Kato, Haruhisa; Nakamura, Ayako; Horie, Masanori

    2015-01-01

    Single-walled carbon nanotube (SWCNT) suspensions in aqueous media were prepared using bovine serum albumin (BSA) and amino acid molecules. It was found that the amino acid molecules clearly decreased the time required for suspending the SWCNTs in BSA aqueous solutions. Dynamic light scattering measurements revealed that the particle sizes of the SWCNTs suspended in aqueous media with and without amino acid molecules were approximately the same and stable for more than one week. The zeta potential values of the BSA molecules in pure water and amino acid aqueous solutions were different, and these values were also reflected in the surface potential of colloidal SWCNT particles in the corresponding aqueous media, thus inducing different dispersibility of SWCNTs in aqueous media. Pulsed field gradient nuclear magnetic resonance measurements showed that the interactions between the SWCNTs and the amino acid molecules are weak and comprise chemical exchange interactions and not bonding interactions. Amino acid molecules play a fascinating role in the preparation of SWCNT suspensions in BSA aqueous media by increasing electrostatic repulsive interactions between SWCNT colloidal particles and consequently enhancing the dispersion ability of the BSA molecules. PMID:25313479

  6. Effects of impurities on the electroreduction of carbon dioxide on platinum electrodes in acid solutions

    SciTech Connect

    Huang, H. )

    1992-02-01

    The electroreduction of carbon dioxide has been studied in this laboratory using electrochemical techniques and in situ Fourier transform infrared reflection absorption spectroscopy (FTIRRAS) on both polycrystalline and single-crystalline platinum electrodes in 0.1M HClO{sub 4} solution. On polycrystalline electrodes and two single-crystalline planes ((110) and (100)), the reduction reaction proceeds in the hydrogen absorption region and gives rise the polycrystalline electrode and Pt(110), and bridge-bonded Co on Pt(100). No. CO was detected on Pt(111). The introduction of CO{sub 2} in solution shows a similar effect on the Butterfly peaks of Pt(111) to that of specifically adsorbed anions, such as bisulfate. The has been attributed tentatively to the absorption of HCO{sub 3} in the potential region between the onset of the butterfly peaks and the formation of oxide. The IR absorption peak between 1418 and 1456 cm{sup {minus}1}, which is assigned to the absorbed HCO{sub 3}{sup {minus}}, shows a large positive shift with increasing potential (127 cm{sup {minus}1}/V). As part of the research on CO{sub 2} reduction, this paper examines the effects of impurities (Cl{sup {minus}}) and electrode rotation rates on Co{sub 2} reduction on polycrystalline Pt electrodes in 0.1M HClO{sub 4} solutions.

  7. Formation of Amino Acids on the Sonolysis of Aqueous Solutions Containing Acetic Acid, Methane, or Carbon Dioxide, in the Presence of Nitrogen Gas.

    PubMed

    Dharmarathne, Leena; Grieser, Franz

    2016-01-21

    The sonolysis of aqueous solutions containing acetic acid, methane, or carbon dioxide in the presence of nitrogen gas was found to produce a number of different amino acids at a rate of ?1 to 100 nM/min, using ultrasound at an operating power of 70 W and 355 kHz. Gas-phase elementary reactions are suggested, and discussed, to account for the formation of the complex biomolecules from the low molar mass solutes used. On the basis of the results, a new hypothesis is presented to explain the formation of amino acids under primitive atmospheric conditions and how their formation may be linked to the eventual abiotic genesis of life on Earth. PMID:26695890

  8. Enhanced removal of 8-quinolinecarboxylic acid in an activated carbon cloth by electroadsorption in aqueous solution.

    PubMed

    López-Bernabeu, S; Ruiz-Rosas, R; Quijada, C; Montilla, F; Morallón, E

    2016-02-01

    The effect of the electrochemical treatment (potentiostatic treatment in a filter-press electrochemical cell) on the adsorption capacity of an activated carbon cloth (ACC) was analyzed in relation with the removal of 8-quinolinecarboxylic acid pollutant from water. The adsorption capacity of an ACC is quantitatively improved in the presence of an electric field (electroadsorption process) reaching values of 96% in comparison to 55% in absence of applied potential. In addition, the cathodic treatment results in higher removal efficiencies than the anodic treatment. The enhanced adsorption capacity has been proved to be irreversible, since the removed compound remains adsorbed after switching the applied potential. The kinetics of the adsorption processes is also improved by the presence of an applied potential. PMID:26433936

  9. Adsorption removal of acid black 1 from aqueous solution using ordered mesoporous carbon

    NASA Astrophysics Data System (ADS)

    Peng, Xiaoming; Hu, Xijun; Fu, Dafang; Lam, Frank L. Y.

    2014-03-01

    A novel ordered mesoporous carbon CMK-3 and synthetic CMK-3 containing nitrogen functional groups by ammonia-treated were applied for acid black 1(AB1) dye adsorption. The ammonia-treated(chemical vapor deposition method) before and after CMK-3 were characterized by using a Micrometitics ASAP 2020 surface area analyzer (ASAP 2020), Fourier transform infrared spectrophotometer (FT-IR), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and equilibrium studies. This result indicates that the prepared CMK-3 and modified CMK-3 were almost uniform, as rope-like domains and their uniform mesopore with diameter centered at 3.2 nm and 3.7 nm. The FIIR analysis depicted that the presence of a variety of new basic functional groups on the modified CMK-3 surface. Several effect variables of pH, dye concentration and temperature were studied. The pseudo second-order model showed the fitter well to agree with the kinetic data. The experimental data were analyzed by the Langmuir and Freundlich models, with the latter found to closely the isotherm model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The results show that CMK-3 using ammonia gas modified by thermal treatment system is an effective method to improvement capacity as it shows the highest adsorption capacity of AB1, as compared to the unmodified CMK-3 and the bamboo-based carbon, respectively.

  10. The Inhibitory Effect of Some Bipyridine Derivatives on the Corrosion Behavior of N80 Carbon Steel in Sulphuric Acid Solutions

    NASA Astrophysics Data System (ADS)

    Liu, Xia; Okafor, Peter C.; Jiang, Bin; Hu, Hongxiang; Zheng, Yugui

    2015-11-01

    The corrosion inhibition characteristics of 2,2‧-bipyridine (BIPY) and 2,2‧-bipyridine-3,3‧-dicarboxylic acid (BIDA), on carbon steel in sulphuric acid solutions was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques at 20°C, 30°C and 40°C. The results indicate that the organic compounds inhibit the corrosion of mild steel in H2SO4 solutions and the extent of inhibition increases with inhibitor concentration and decreases with temperature. A mixed-inhibition mechanism is proposed for the inhibitive effects of the compounds. The order of inhibition efficiency obtained was BIDA>BIPY. There is a good correlation between the quantum chemical parameters and experimentally determined inhibition efficiency of the inhibitors. The adsorption characteristics of the inhibitor were approximated by Temkin isotherm. Morphological study of the carbon steel electrode surface was undertaken by scanning electron microscope (SEM) and the interfacial species formed on the surface in the presence of inhibitors analyzed by Infrared spectroscopy.

  11. Theoretical study of enzymatically catalyzed tautomerization of carbon acids in aqueous solution: quantum calculations and steered molecular dynamics simulations.

    PubMed

    Tolosa, Santiago; Hidalgo, Antonio; Sansn, Jorge A

    2016-02-01

    The thermodynamics and kinetics of enzymatically assisted reactions of carbon acids were studied theoretically in this work. Quantum electronic (QE) structure calculations and steered molecular dynamics (SMD) simulations were carried out. Three 3-butenal tautomerization reactions that proceed from the ?,?-unsaturated reactant (R) to the ?,?-unsaturated carbon acid product (P) and occur in two elementary steps through an intermediate (I) were studied, ignoring or including the surrounding aqueous medium in the calculations. The Gibbs free energies of activation of the R ? I enolization and I ? P ketonization steps were found to decrease considerably when residues simulating enzymes were introduced into these processes. Although the processes became slightly more favorable thermodynamically when the solution was included in the simulations, they became less favorable kinetically. The results from SMD simulations of these reactions were qualitatively consistent with the values we obtained using QE as well as those found by other authors in similar studies. Our simulations also allowed us to perform a detailed study of these reactions in solution. PMID:26815031

  12. Corrosion inhibition behavior of propyl phosphonic acid-Zn2+ system for carbon steel in aqueous solution

    NASA Astrophysics Data System (ADS)

    Prabakaran, M.; Venkatesh, M.; Ramesh, S.; Periasamy, V.

    2013-07-01

    The effectiveness of propyl phosphonic acid (PPA) as a corrosion inhibitor in association with a bivalent cation like Zn2+ has been studied. An eco-friendly inhibitor in controlling corrosion of carbon steel in neutral aqueous medium in the absence and presence of Zn2+ has been evaluated by gravimetric method. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous environment. Potentiodynamic polarization studies showed that the inhibitor is a mixed inhibitor. X-ray photoelectron spectroscopic analysis (XPS) of the protective film exhibited the presence of the elements viz., iron, phosphorus, oxygen, carbon and zinc. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of oxides/hydroxides of iron(III), Zn(OH)2 and [Fe(II)/(III)-Zn(II)-PPA] complex. Further, the surface analysis techniques viz., FT-IR, AFM and SEM studies confirm the formation of an adsorbed protective film on the carbon steel surface. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

  13. Solution blow spinning: parameters optimization and effects on the properties of nanofibers from poly(lactic) acid/ dimethyl carbonate solutions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solution blow spinning (SBS) is a process to produce non-woven fiber sheets with high porosity and an extremely large amount of surface area. In this study, a Box-Behnken experimental design (BBD) was used to optimize the processing parameters for the production of nanofibers from polymer solutions ...

  14. Removal of hexavalent chromium in carbonic acid solution by oxidizing slag discharged from steelmaking process in electric arc furnace

    NASA Astrophysics Data System (ADS)

    Yokoyama, Seiji; Okazaki, Kohei; Sasano, Junji; Izaki, Masanobu

    2014-02-01

    Hexavalent chromium (Cr(VI)) is well-known to be a strong oxidizer, and is recognized as a carcinogen. Therefore, it is regulated for drinking water, soil, groundwater and sea by the environmental quality standards all over the world. In this study, it was attempted to remove Cr(VI) ion in a carbonic acid solution by the oxidizing slag that was discharged from the normal steelmaking process in an electric arc furnace. After the addition of the slag into the aqueous solution contained Cr(VI) ion, concentrations of Cr(VI) ion and total chromium (Cr(VI) + trivalent chromium (Cr(III)) ions decreased to lower detection limit of them. Therefore, the used slag could reduce Cr(VI) and fix Cr(III) ion on the slag. While Cr(VI) ion existed in the solution, iron did not dissolve from the slag. From the relation between predicted dissolution amount of iron(II) ion and amount of decrease in Cr(VI) ion, the Cr(VI) ion did not react with iron(II) ion dissolved from the slag. Therefore, Cr(VI) ion was removed by the reductive reaction between Cr(VI) ion and the iron(II) oxide (FeO) in the slag. This reaction progressed on the newly appeared surface of iron(II) oxide due to the dissolution of phase composed of calcium etc., which existed around iron(II) oxide grain in the slag.

  15. Uptake of acetone, acetaldehyde and ethanol in cold sulfuric acid solutions containing organic material: Carbon accretion mechanisms

    NASA Astrophysics Data System (ADS)

    Williams, Margaret B.; Michelsen, Rebecca R. H.; Axson, Jessica L.; Iraci, Laura T.

    2010-03-01

    The solubilities of acetone, ethanol and acetaldehyde in cold ternary solutions composed of 38.4-75.0 wt% sulfuric acid in water with additional dissolved organic material have been measured over the temperature range 214.4-238.5 K using a Knudsen cell reactor. The solubility of acetaldehyde in H 2SO 4/H 2O is enhanced by an order of magnitude by the presence of ethanol or acetone. The reactive uptake of acetaldehyde is enhanced by the presence of formaldehyde in acid solution. No significant formation of acetals from ethanol with carbonyl partners was observed. The solubility of acetone is unaffected by the presence of ethanol in solution and vice versa. Only polymerization of small aldehydes offers a potentially significant route to the accretion of organic material into acidic particles in the upper troposphere. The acid-catalyzed polymerization of aldehydes, RC(H) dbnd O + R'C(H) dbnd O, proceeds through the hydrated forms of the aldehydes, is optimized at acidities around 40 wt% H 2SO 4, and can potentially accumulate significant amounts (>20%) of organic material by mass in upper tropospheric particles.

  16. Acid sorption regeneration process using carbon dioxide

    DOEpatents

    King, C. Judson (Kensington, CA); Husson, Scott M. (Anderson, SC)

    2001-01-01

    Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent in the presence of carbon dioxide under pressure. The acids are freed from the sorbent phase by a suitable regeneration method, one of which is treating them with an organic alkylamine solution thus forming an alkylamine-carboxylic acid complex which thermally decomposes to the desired carboxylic acid and the alkylamine.

  17. Characterization of the International Humic Substances Society standard and reference fulvic and humic acids by solution state carbon-13 (13C) and hydrogen-1 (1H) nuclear magnetic resonance spectrometry

    USGS Publications Warehouse

    Thorn, Kevin A.; Folan, Daniel W.; MacCarthy, Patrick

    1989-01-01

    Standard and reference samples of the International Humic Substances Society have been characterized by solution state carbon-13 and hydrogen-1 nuclear magnetic resonance (NMR) spectrometry. Samples included the Suwannee River, soil, and peat standard fulvic and humic acids, the Leonardite standard humic acid, the Nordic aquatic reference fulvic and humic acids, and the Summit Hill soil reference humic acid. Aqueous-solution carbon-13 NMR analyses included the measurement of spin-lattice relaxation times, measurement of nuclear Overhauser enhancement factors, measurement of quantitative carbon distributions, recording of attached proton test spectra, and recording of spectra under nonquantitative conditions. Distortionless enhancement by polarization transfer carbon-13 NMR spectra also were recorded on the Suwannee River fulvic acid in deuterated dimethyl sulfoxide. Hydrogen-1 NMR spectra were recorded on sodium salts of the samples in deuterium oxide. The carbon aromaticities of the samples ranged from 0.24 for the Suwannee River fulvic acid to 0.58 for the Leonardite humic acid.

  18. Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions

    USGS Publications Warehouse

    Iggy, Litaor M.; Thurman, E.M.

    1988-01-01

    Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

  19. Influence of activated carbon surface acidity on adsorption of heavy metal ions and aromatics from aqueous solution

    NASA Astrophysics Data System (ADS)

    Sato, Sanae; Yoshihara, Kazuya; Moriyama, Koji; Machida, Motoi; Tatsumoto, Hideki

    2007-08-01

    Adsorption of toxic heavy metal ions and aromatic compounds onto activated carbons of various amount of surface C-O complexes were examined to study the optimum surface conditions for adsorption in aqueous phase. Cadmium(II) and zinc(II) were used as heavy metal ions, and phenol and nitrobenzene as aromatic compounds, respectively. Activated carbon was de-ashed followed by oxidation with nitric acid, and then it was stepwise out-gassed in helium flow up to 1273 K to gradually remove C-O complexes introduced by the oxidation. The oxidized activated carbon exhibited superior adsorption for heavy metal ions but poor performance for aromatic compounds. Both heavy metal ions and aromatics can be removed to much extent by the out-gassed activated carbon at 1273 K. Removing C-O complexes, the adsorption mechanisms would be switched from ion exchange to C?-cation interaction for the heavy metals adsorption, and from some kind of oxygen-aromatics interaction to ?-? dispersion for the aromatics.

  20. Modeling of wormhole behavior in carbonate acidizing

    SciTech Connect

    Hung, K.M.

    1987-01-01

    A mathematical model that describes the growth and competition of wormholes during an acidizing treatment in a carbonate formation is developed. The purpose of the treatment is to remove any near wellbore permeability damage created by drilling or completion fluids so that the production of reservoir fluids is stimulated. Hydrochloric acid is commonly used for this purpose. Since the acid solution tends to flow into the less resistant areas, large pores on the rock surface receive most acid fluid. Pores are enlarged due to the reaction between acid solution and carbonates. The growth of large pores in the formation is referred to as wormholing. Results from the model show that wormholes are formed due to the heterogeneity of carbonate rock and the reaction kinetics between acid and carbonates. Formation of a dominant wormhole is controlled by fluid diffusivity and fluid loss. Model results have good agreement with the results from published papers.

  1. Sonolysis of Short-Chain Organic Dicarboxylic Acid Solutions

    NASA Astrophysics Data System (ADS)

    Naruke, Yukio; Harada, Hisashi

    2011-07-01

    Sonolyses of C4 (carbon number 4) dicarboxylic acids (succinic acid, maleic acid, and fumaric acid) were performed in aqueous solution. They changed one into the other during sonication, affording carbon-number-conserving transformations. Maleic acid and fumaric acid were produced from saccinic acid by dehydrogenation. Furthermore, malic acid and tartaric acid were obtained by hydroxylation. The sonochemical reaction processes are discussed in terms of the time dependences of products and the addition of radical scavengers. In addition, mutual isomerization of fumaric acid and maleic acid was observed during sonication without the use of mediators.

  2. Sequential study on reactive blue 29 dye removal from aqueous solution by peroxy acid and single wall carbon nanotubes: experiment and theory

    PubMed Central

    2013-01-01

    The majority of anthraquinone dye released to the environment come from antrapogenic sources. Several techniques are available for dyes' removal. In this study removal of reactive blue 29 (RB29) by an advanced oxidation process sequenced with single wall carbon nanotubes was investigated. Advanced oxidation process was optimized over a period of 60 minutes by changing the ratio of acetic acid to hydrogen peroxide, the compounds which form peroxy acid. Reduction of 20.2% -56.4% of reactive blue 29 was observed when the ratio of hydrogen peroxide/acetic acid/dye changed from 344/344/1 to 344/344/0.08 at different times (60, 120 and 180 min). The optimum ratio of acetic acid/hydrogen peroxide/dye was found to be 344/344/0.16 over 60 min. The resultant then was introduced for further removal by single wall carbon nanotubes(SWCNTs) as adsorbent. The adsorption of reactive blue 29 onto SWCNTs was also investigated. Langmuir, Freundlich and BET isotherms were determined and the results revealed that the adsorption of RB29 onto SWCNTs was well explained by BET model and changed to Freundlich isotherm when SWCNTs was used after the application of peroxy acid. Kinetic study showed that the equilibrium time for adsorption of RB 29 on to SWCNT is 4 h. Experiments were carried out to investigate adsorption kinetics, adsorbent capacity and the effect of solution pH on the removal of reactive blue29. The pseudo-second order kinetic equation could best describe the sorption kinetics. The most efficient pH for color removal (amongst pH=3, 5 and 8) was pH= 5. Further studies are needed to identify the peroxy acid degradation intermediates and to investigate their effects on SWCNTs. PMID:23369540

  3. Electrodeposition From Acidic Solutions of Nickel Bis(benzenedithiolate) Produces a Hydrogen-Evolving Ni-S Film on Glassy Carbon

    SciTech Connect

    Fang, Ming; Engelhard, Mark H.; Zhu, Zihua; Helm, Monte L.; Roberts, John A.

    2014-01-03

    Films electrodeposited onto glassy carbon electrodes from acidic acetonitrile solutions of [Bu4N][Ni(bdt)2] (bdt = 1,2-benzenedithiolate) are active toward electrocatalytic hydrogen production at potentials 0.2-0.4 V positive of untreated electrodes. This activity is preserved on rinsing the electrode and transfer to fresh acid solution. X-ray photoelectron spectra indicate that the deposited material contains Ni and S. Correlations between voltammetric and spectroscopic results indicate that the deposited material is active, i.e. that catalysis is heterogeneous rather than homogeneous. Control experiments establish that obtaining the observed catalytic response requires both Ni and the 1,2 benzenedithiolate ligand to be present during deposition. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. A portion of the research was performed using EMSL, a 17 national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  4. ORGANIC CARBON FRACTIONS IN O AND B HORIZON SOLUTIONS FROM A NEW ENGLAND SPODOSOL: EFFECTS OF ACID TREATMENT

    EPA Science Inventory

    We examined the effects of H2SO4 and HNO3 on dissolved organic carbon (DOC), pH, and DOC fractions in extracts from Spodosol O and B horizon samples of a forest soil from eastern Maine. reliminary work with HNO3 at pH=3(1 to 24h shaking, ionic strength adjustment with NaNO3 (I=0....

  5. Salinity, water hardness, and dissolved organic carbon modulate degradation of peracetic acid (PAA) compounds in aqueous solutions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is used in aquaculture under different conditions for disinfection purposes. However, there is a lack of information about its environmental fate, particularly its persistence in aquatic systems with different chemistries. Therefore, the impact of water hardness, salinity, and d...

  6. Dissolution of Spent Nuclear Fuel in Carbonate-Peroxide Solution

    SciTech Connect

    Soderquist, Chuck Z.; Hanson, Brady D.

    2010-01-31

    This study shows that spent UO2 fuel can be completely dissolved in a carbonate-peroxide solution apparently without attacking the metallic Mo-Tc-Ru-Rh-Pd fission product phase. Samples of spent nuclear fuel were pulverized and sieved to a uniform size, then duplicate aliquots were weighed into beakers for analysis. One set was dissolved in near-boiling 10M nitric acid, and the other set was dissolved in a solution of ammonium carbonate and hydrogen peroxide at room temperature. All the resulting fuel solutions were then analyzed for Sr-90, Tc-99, Cs-137, plutonium, and Am-241. For all the samples, the concentrations of Cs-137, Sr-90, plutonium, and Am-241 were the same for both the nitric acid dissolution and the ammonium carbonate-hydrogen peroxide dissolution, but the technetium concentration of the ammonium carbonate-hydrogen peroxide fuel solution was only about 25% of the same fuels dissolved in hot nitric acid.

  7. Reaction Mechanism for Direct Proton Transfer from Carbonic Acid to a Strong Base in Aqueous Solution II: Solvent Coordinate-Dependent Reaction Path.

    PubMed

    Daschakraborty, Snehasis; Kiefer, Philip M; Miller, Yifat; Motro, Yair; Pines, Dina; Pines, Ehud; Hynes, James T

    2016-03-10

    The protonation of methylamine base CH3NH2 by carbonic acid H2CO3 within a hydrogen (H)-bonded complex in aqueous solution was studied via Car-Parrinello dynamics in the preceding paper (Daschakraborty, S.; Kiefer, P. M.; Miller, Y.; Motro, Y.; Pines, D.; Pines, E.; Hynes, J. T. J. Phys. Chem. B 2016, DOI: 10.1021/acs.jpcb.5b12742 ). Here some important further details of the reaction path are presented, with specific emphasis on the water solvent's role. The overall reaction is barrierless and very rapid, on an ∼100 fs time scale, with the proton transfer (PT) event itself being very sudden (<10 fs). This transfer is preceded by the acid-base H-bond's compression, while the water solvent changes little until the actual PT occurrence; this results from the very strong driving force for the reaction, as indicated by the very favorable acid-protonated base ΔpKa difference. Further solvent rearrangement follows immediately the sudden PT's production of an incipient contact ion pair, stabilizing it by establishment of equilibrium solvation. The solvent water's short time scale ∼120 fs response to the incipient ion pair formation is primarily associated with librational modes and H-bond compression of water molecules around the carboxylate anion and the protonated base. This is consistent with this stabilization involving significant increase in H-bonding of hydration shell waters to the negatively charged carboxylate group oxygens' (especially the former H2CO3 donor oxygen) and the nitrogen of the positively charged protonated base's NH3(+). PMID:26876428

  8. Carbonic Acid Retreatment of Biomass

    SciTech Connect

    Baylor university

    2003-06-01

    This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. (1) Solidify the theoretical understanding of the binary CO{sub 2}/H{sub 2}O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. (2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. (3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. (4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. (5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for the use of carbonic acid compared to water alone. (6) Determine optimal conditions for carbonic acid pretreatment of aspen wood. Optimal severities appeared to be in the mid range tested. ASPEN-Plus modeling and economic analysis of the process indicate that the process could be cost competitive with sulfuric acid if the concentration of solids in the pretreatment is maintained very high ({approx}50%). Lower solids concentrations result in larger reactors that become expensive to construct for high pressure applications.

  9. Carbonic Acid Pretreatment of Biomass

    SciTech Connect

    G. Peter van Walsum; Kemantha Jayawardhana; Damon Yourchisin; Robert McWilliams; Vanessa Castleberry

    2003-05-31

    This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. 1) Solidify the theoretical understanding of the binary CO2/H2O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. 2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. 3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. 4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. 5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for the use of carbonic acid compared to water alone. 6) Determine optimal conditions for carbonic acid pretreatment of aspen wood. Optimal severities appeared to be in the mid range tested. ASPEN-Plus modeling and economic analysis of the process indicate that the process could be cost competitive with sulfuric acid if the concentration of solids in the pretreatment is maintained very high (~50%). Lower solids concentrations result in larger reactors that become expensive to construct for high pressure applications.

  10. Carbon dioxide sequestration by direct mineral carbonation with carbonic acid

    SciTech Connect

    O'Connor, W.K.; Dahlin, D.C.; Nilsen, D.N.; Walters, R.P.; Turner, P.C.

    2000-07-01

    The Albany Research Center (ARC) of the US Department of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite and member (mg{sub 2}SiO{sub 4})], or serpentine [Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}]. This slurry is reacted with supercritical carbon dioxide (CO{sub 2}) to produce magnesite (MgCO{sub 3}). The CO{sub 2} is dissolved in water to form carbonic acid (H{sub 2}CO{sub 3}), which dissociates to H{sup +} and HCO{sub 3}{sup {minus}}. The H{sup +} reacts with the mineral, liberating Mg{sup 2+} cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO{sub 2} pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185 C and a partial pressure of CO{sub 2} (P{sub CO{sub 2}}) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction conditions, have achieved roughly 83% conversion of heat treated serpentine and 84% conversion of olivine to the carbonate in 6 hours. The results from the current studies suggest that reaction kinetics can be improved by pretreatment of the mineral, catalysis of the reaction, or some combination of the two. Future tests are intended to examine a broader pressure/temperature regime, various pretreatment options, as well as other mineral groups.

  11. Carbon dioxide sequestration by direct mineral carbonation with carbonic acid

    SciTech Connect

    O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Walters, Richard P.; Turner, Paul C.

    2000-01-01

    The Albany Research Center (ARC) of the U.S. Dept. of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. Other participants in this Program include the Los Alamos National Laboratory, Arizona State University, Science Applications International Corporation, and the DOE National Energy Technology Laboratory. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. This slurry is reacted with supercritical carbon dioxide (CO2) to produce magnesite (MgCO3). The CO2 is dissolved in water to form carbonic acid (H2CO3), which dissociates to H+ and HCO3 -. The H+ reacts with the mineral, liberating Mg2+ cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO2 pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185?C and a partial pressure of CO2 (PCO2) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction conditions, have achieved roughly 83% conversion of heat treated serpentine and 84% conversion of olivine to the carbonate in 6 hours. The results from the current studies suggest that reaction kinetics can be improved by pretreatment of the mineral, catalysis of the reaction, or some combination of the two. Future tests are intended to examine a broader pressure/temperature regime, various pretreatment options, as well as other mineral groups.

  12. Ions in hyaluronic acid solutions

    NASA Astrophysics Data System (ADS)

    Horkay, Ferenc; Basser, Peter J.; Londono, David J.; Hecht, Anne-Marie; Geissler, Erik

    2009-11-01

    Hyaluronic acid (HA) is an anionic biopolymer that is almost ubiquitous in biological tissues. An attempt is made to determine the dominant features that account for both its abundance and its multifunctional role, and which set it apart from other types of biopolymers. A combination of osmotic and scattering techniques is employed to quantify its dynamic and static properties in near-physiological solution conditions, where it is exposed both to mono- and divalent counterions. An equation of state is derived for the osmotic pressure ? in the semidilute concentration region, in terms of two variables, the polymer concentration c and the ionic strength J of the added salt, according to which ? =1.4103c9/4/J3/4 kPa, where c and J are expressed in mole. Over the physiological ion concentration range, the effect of the sodium chloride and calcium chloride on the osmotic properties of HA solutions is fully accounted for by their contributions to the ionic strength. The absence of precipitation, even at high CaCl2 concentrations, distinguishes this molecule from other biopolymers such as DNA. Dynamic light scattering measurements reveal that the collective diffusion coefficient in HA solutions exceeds that in aqueous solutions of typical neutral polymers by a factor of approximately 5. This property ensures rapid adjustment to, and recovery from, stress applied to HA-containing tissue. Small angle x-ray scattering measurements confirm the absence of appreciable structural reorganization over the observed length scale range 10-1000 , as a result of calcium-sodium ion exchange. The scattered intensity in the transfer momentum range q >0.03 -1 varies as 1/q, indicating that the HA chain segments in semidilute solutions are linear over an extended concentration range. The osmotic compression modulus c ??/?c, a high value of which is a prerequisite in structural biopolymers, is several times greater than in typical neutral polymer solutions.

  13. Water treatment by H2O2 and/or UV affects carbon nanotube (CNT) properties and fate in water and tannic acid solution.

    PubMed

    Czech, Bo?ena; Oleszczuk, Patryk; Wi?cek, Agnieszka Ewa; Barczak, Mariusz

    2015-12-01

    The objective of the study was to estimate how water treatment (stimulation of real conditions) by H2O2 and/or UV affects carbon nanotube (CNT) properties and fate (stability/aggregation) in water and tannic acid solution. The processes studied had only a slight effect on SBET, porosity, and surface composition of CNTs. There was a change in the morphology of CNTs. After H2O2 and/or UV treatment, CNTs underwent shortening, opening up of their ends, and exfoliation. Treatment with H2O2 increased the content of oxygen in CNTs. A decrease was observed in the surface charge and in the mobility of CNTs, which caused an increase in their stability. UV irradiation of CNTs led to an increased incidence of defects that were manifested by both an increase of zeta potential and an increased mobility of CNT, whereas the presence of H2O2 during UV irradiation had only a slight effect on the parameters of the porous structure of nanotubes. PMID:26304806

  14. Reactive solute transport in acidic streams

    USGS Publications Warehouse

    Broshears, R.E.

    1996-01-01

    Spatial and temporal profiles of Ph and concentrations of toxic metals in streams affected by acid mine drainage are the result of the interplay of physical and biogeochemical processes. This paper describes a reactive solute transport model that provides a physically and thermodynamically quantitative interpretation of these profiles. The model combines a transport module that includes advection-dispersion and transient storage with a geochemical speciation module based on MINTEQA2. Input to the model includes stream hydrologic properties derived from tracer-dilution experiments, headwater and lateral inflow concentrations analyzed in field samples, and a thermodynamic database. Simulations reproduced the general features of steady-state patterns of observed pH and concentrations of aluminum and sulfate in St. Kevin Gulch, an acid mine drainage stream near Leadville, Colorado. These patterns were altered temporarily by injection of sodium carbonate into the stream. A transient simulation reproduced the observed effects of the base injection.

  15. Extraction of silicotungstic acid from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Sulimov, A. V.; Danov, S. M.; Balashov, A. L.; Ovcharova, A. V.

    2015-09-01

    Patterns in obtaining silicotungstic acid from aqueous solutions via extraction are studied. It is shown that processing a 30 wt % aqueous solution of silicotungstic acid with a mixed organic extractant (butanol-1 with benzene additive) allows the extraction of up to 55 wt % of silicotungstic acid from the aqueous phase. It is established that adding hydrochloric acid in amounts of 1.5-2.0% raises the degree of extraction to 98-99 wt % of the silicotungstic acid.

  16. Nitric acid recovery from waste solutions

    DOEpatents

    Wilson, A. S.

    1959-04-14

    The recovery of nitric acid from aqueous nitrate solutions containing fission products as impurities is described. It is desirable to subject such solutions to concentration by evaporation since nitric acid is regenerated thereby. A difficulty, however, is that the highly radioactive fission product ruthenium is volatilized together with the nitric acid. It has been found that by adding nitrous acid, ruthenium volatilization is suppressed and reduced to a negligible degree so that the distillate obtained is practically free of ruthenium.

  17. Standard Solutions and Titratable Acidity

    NASA Astrophysics Data System (ADS)

    Nielsen, S. Suzanne

    Many types of chemical analyses are made using a method in which a constituent is titrated with a solution of known strength to an indicator endpoint. Such a solution is referred to as a standard solution. From the volume and concentration of standard solution used in the titration, and the sample size, the concentration of the constituent in the sample can be calculated.

  18. ELECTROLYTIC REDUCTION OF NITRIC ACID SOLUTIONS

    DOEpatents

    Alter, H.W.; Barney, D.L.

    1958-09-30

    A process is presented for the treatment of radioactivc waste nitric acid solutions. The nitric acid solution is neutralized with an alkali metal hydroxide in an amount sufficient to precipitate insoluble hydroxides, and after separation of the precipitate the solution is electrolyzed to convert the alkali nitrate formed, to alkali hydroxide, gaseous ammonla and oxygen. The solution is then reusable after reducing the volume by evaporating the water and dissolved ammonia.

  19. Adsorption of lanthanides(III), uranium(VI) and thorium(IV) from nitric acid solutions by carbon inverse opals modified with tetraphenylmethylenediphospine dioxide.

    PubMed

    Turanov, A N; Karandashev, V K; Masalov, V M; Zhokhov, A A; Emelchenko, G A

    2013-09-01

    Carbon inverse opals (C-IOP) were noncovalently modified with tetraphenylmethylenediphospine dioxide (TPMDPDO). The distribution of TPMDPDO between C-IOP and aqueous HNO3 solutions has been studied. The effect of HNO3 concentration in the aqueous phase and that of the TPMDPDO concentration in the sorbent phase on the adsorption of microquantities of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, U, and Th nitrates from HNO3 solutions by C-IOP modified with TPMDPDO is considered. The stoichiometry of the sorbed complexes has been determined by the slope analysis method. The efficiency of lanthanide(III) adsorption from moderate-concentration HNO3 solutions decreases with increasing element atomic number. PMID:23786834

  20. Determination of the acidic sites of purified single-walled carbon nanotubes by acid base titration

    NASA Astrophysics Data System (ADS)

    Hu, H.; Bhowmik, P.; Zhao, B.; Hamon, M. A.; Itkis, M. E.; Haddon, R. C.

    2001-09-01

    We report the measurement of the acidic sites in three different samples of commercially available full-length purified single-walled carbon nanotubes (SWNTs) - as obtained from CarboLex (CLI), Carbon Solutions (CSI) and Tubes@Rice (TAR) - by simple acid-base titration methods. Titration of the purified SWNTs with NaOH and NaHCO 3 solutions was used to determine the total percentage of acidic sites and carboxylic acid groups, respectively. The total percentage of acidic sites in full length purified SWNTs from TAR, CLI and CSI are about 1-3%.

  1. Solution nonideality related to solute molecular characteristics of amino acids.

    PubMed Central

    Keener, C R; Fullerton, G D; Cameron, I L; Xiong, J

    1995-01-01

    By measuring the freezing-point depression for dilute, aqueous solutions of all water-soluble amino acids, we test the hypothesis that nonideality in aqueous solutions is due to solute-induced water structuring near hydrophobic surfaces and solute-induced water destructuring in the dipolar electric fields generated by the solute. Nonideality is expressed with a single solute/solvent interaction parameter I, calculated from experimental measure of delta T. A related parameter, I(n), gives a method of directly relating solute characteristics to solute-induced water structuring or destructuring. I(n)-values correlate directly with hydrophobic surface area and inversely with dipolar strength. By comparing the nonideality of amino acids with progressively larger hydrophobic side chains, structuring is shown to increase with hydrophobic surface area at a rate of one perturbed water molecule per 8.8 square angstroms, implying monolayer coverage. Destructuring is attributed to dielectric realignment as described by the Debye-Hckel theory, but with a constant separation of charges in the amino-carboxyl dipole. By using dimers and trimers of glycine and alanine, this destructuring is shown to increase with increasing dipole strength using increased separation of fixed dipolar charges. The capacity to predict nonideal solution behavior on the basis of amino acid characteristics will permit prediction of free energy of transfer to water, which may help predict the energetics of folding and unfolding of proteins based on the characteristics of constituent amino acids. Images FIGURE 6 PMID:7711253

  2. GC/MS method for determining carbon isotope enrichment and concentration of underivatized short-chain fatty acids by direct aqueous solution injection of biogas digester samples.

    PubMed

    Mulat, Daniel Girma; Feilberg, Anders

    2015-10-01

    In anaerobic digestion of organic matter, several metabolic pathways are involved during the simultaneous production and consumption of short-chain fatty acids (SCFA) in general and acetate in particular. Understanding the role of each pathway requires both the determination of the concentration and isotope enrichment of intermediates in conjunction with isotope labeled substrates. The objective of this study was to establish a rapid and simple GC/MS method for determining the isotope enrichment of acetate and concentration of underivatized short-chain fatty acids (SCFA) in biogas digester samples by direct liquid injection of acidified aqueous samples. Sample preparation involves only acidification, centrifugation and filtration of the aqueous solution followed by direct injection of the aqueous supernatant solution onto a polar column. With the sample preparation and GC/MS conditions employed, well-resolved and sharp peaks of underivatized SCFA were obtained in a reasonably short time. Good recovery (96.6-102.3%) as well as low detection (4-7 mol/L) and quantification limits (14-22 mol/L) were obtained for all the 6 SCFA studied. Good linearity was achieved for both concentration and isotope enrichment measurement with regression coefficients higher than 0.9978 and 0.9996, respectively. The method has a good intra- and inter-day precision with a relative standard deviation (RSD) below 6% for determining the tracer-to-tracee ratio (TTR) of both [2-(13)C]acetate and [U-(13)C]acetate. It has also a good intra- and inter-day precision with a RSD below 6% and 5% for determining the concentration of standard solution and biogas digester samples, respectively. Acidification of biogas digester samples with oxalic acid provided the low pH required for the protonation of SCFA and thus, allows the extraction of SCFA from the complex sample matrix. Moreover, oxalic acid was the source of formic acid which was produced in the injector set at high temperature. The produced formic acid prevented the adsorption of SCFA in the column, thereby eliminating peak tailing and ghost peaks. The applicability of the validated GC/MS method for determining the concentration of acetate and its (13)C isotope enrichment in anaerobic digester samples was tested and the results demonstrated the suitability of this method for identifying the metabolic pathways involved in degradation and production of acetate. PMID:26078128

  3. Electroreduction of carbon dioxide in aqueous solutions at metal electrodes

    SciTech Connect

    Augustynski, J.; Jermann, B.; Kedzierzawski, P.

    1996-12-31

    The quantities of carbon stored in the form of atmospheric carbon dioxide, CO{sub 2} in the hydrosphere and carbonates in the terrestrial environment substantially exceed those of fossil fuels. In spite of this the industrial use of carbon dioxide as a source of chemical carbon is presently limited to preparation of urea and certain carboxylic acids as well as organic carbonates and polycarbonates. However, the situation is expected to change in the future, if effective catalytic systems allowing to activate carbon dioxide will become available. In this connection, the electrochemical reduction of CO{sub 2}, requiring only an additional input of water and electrical energy, appears as an attractive possibility. For more than 100 years formic acid and formates of alkali metals were considered as the only significant products of the electroreduction of carbon dioxide in aqueous solutions. The highest current efficiencies, exceeding 90 %, were obtained either with mercury or with amalgam electrodes. The only comprehensive study regarding kinetics of CO{sub 2} reduction in aqueous solution has been performed by Eyring et al. using a mercury cathode. This paper describes electrolysis studies.

  4. Method for extracting lanthanides and actinides from acid solutions

    DOEpatents

    Horwitz, E. Philip (Naperville, IL); Kalina, Dale G. (Naperville, IL); Kaplan, Louis (Lombard, IL); Mason, George W. (Clarendon Hills, IL)

    1985-01-01

    A process for the recovery of actinide and lanthanide values from aqueous acidic solutions with an organic extractant having the formula: ##STR1## where .phi. is phenyl, R.sup.1 is a straight or branched alkyl or alkoxyalkyl containing from 6 to 12 carbon atoms and R.sup.2 is an alkyl containing from 3 to 6 carbon atoms. The process is suitable for the separation of actinide and lanthanide values from fission product values found together in high level nuclear reprocessing waste solutions.

  5. Degradation of ascorbic acid in ethanolic solutions.

    PubMed

    Hsu, Hsin-Yun; Tsai, Yi-Chin; Fu, Chi-Chang; Wu, James Swi-Bea

    2012-10-24

    Ascorbic acid occurs naturally in many wine-making fruits. The industry also uses ascorbic acid as an antioxidant and color stabilizer in the making of alcoholic beverages including white wine, wine cooler, alcopop, and fruit liqueur. However, the degradation of ascorbic acid itself may cause browning and the deterioration of color quality. This study was aimed to monitor the degradation of ascorbic acid, the formation of degradation products, and the browning in storage of ascorbic acid containing 0-40% (v/v) ethanolic solutions buffered at pH 3.2 as models of alcoholic beverages. The results show that ascorbic acid degradation in the ethanolic solutions during storage follows first-order reaction, that the degradation and browning rates increase with the increase of ethanol concentration, that the activation energy for the degradation of ascorbic acid is in the range 10.35-23.10 (kcal/mol), that 3-hydroxy-2-pyrone is an indicator and a major product of ascorbic acid degradation, and that aerobic degradation pathway dominants over anaerobic pathway in ascorbic acid degradation in ethanolic solutions. PMID:22994409

  6. Diffusion of sulfuric acid in concentrated solutions

    SciTech Connect

    Umino, S.; Newman, J. )

    1993-08-01

    Aqueous sulfuric acid is an economically important chemical reagent. It is one of the largest volume chemical commodities, finding uses in fertilizer production, petroleum refining, extraction of metals from their ores, production of inorganic pigments, pickling of iron and steel, synthesis of surface-active agents, and as a reactant in the lead-acid storage battery. The restricted diffusion method was used to measure the differential diffusion coefficient of sulfuric acid in water at 25 C for the concentration range from 0.3 to 7.5 molar. The concentration gradients of diffusing species were observed by Rayleigh interferometry. Experimental transport data are analyzed with concentrated solution theory of electrolytes in order to elucidate macroscopic transport characteristics of sulfuric acid in terms of specific binary interactions in solution. Results indicate that the transport properties of sulfuric acid are determined by the hydrogen ion-water molecule.

  7. Reference electrode for strong oxidizing acid solutions

    DOEpatents

    Rigdon, Lester P. (Livermore, CA); Harrar, Jackson E. (Castro Valley, CA); Bullock, Sr., Jack C. (Pleasanton, CA); McGuire, Raymond R. (Brentwood, CA)

    1990-01-01

    A reference electrode for the measurement of the oxidation-reduction potentials of solutions is especially suitable for oxidizing solutions such as highly concentrated and fuming nitric acids, the solutions of nitrogen oxides, N.sub.2 O.sub.4 and N.sub.2 O.sub.5, in nitric acids. The reference electrode is fabricated of entirely inert materials, has a half cell of Pt/Ce(IV)/Ce(III)/70 wt. % HNO.sub.3, and includes a double-junction design with an intermediate solution of 70 wt. % HNO.sub.3. The liquid junctions are made from Corning No. 7930 glass for low resistance and negligible solution leakage.

  8. CATALYZED OXIDATION OF URANIUM IN CARBONATE SOLUTIONS

    DOEpatents

    Clifford, W.E.

    1962-05-29

    A process is given wherein carbonate solutions are employed to leach uranium from ores and the like containing lower valent uranium species by utilizing catalytic amounts of copper in the presence of ammonia therein and simultaneously supplying an oxidizing agent thereto. The catalysis accelerates rate of dissolution and increases recovery of uranium from the ore. (AEC)

  9. Nitric acid vapor removal by activated, impregnated carbons

    SciTech Connect

    Wood, G.O.

    1996-12-31

    Laboratory and industrial workers can be exposed to vapors of nitric acid, especially in accidents, such as spills. Nitric acid can also be a product of incineration for energy production or waste (e.g., CW agent) disposal. Activated carbons containing impregnants for enhancing vapor and gas removal have been tested for effectiveness in removing vapors of nitric acid from air. The nitric acid vapor was generated from concentrated acid solutions and detected by trapping in a water bubbler for pH measurements. Both low and moderate relative humidity conditions were used. All carbons were effective at vapor contact times representative of air-purifying respirator use. One surprising observation was the desorption of low levels of ammonia from impregnated carbons. This was apparently due to residual ammonia from the impregnation processes.

  10. ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

    EPA Science Inventory

    The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

  11. Aqueous solution dispersement of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  12. Alkaline earth cation extraction from acid solution

    DOEpatents

    Dietz, Mark; Horwitz, E. Philip

    2003-01-01

    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

  13. Synthesis and Characterization of Poly(glyceric Acid Carbonate): A Degradable Analogue of Poly(acrylic Acid).

    PubMed

    Zhang, Heng; Lin, Xinrong; Chin, Stacy; Grinstaff, Mark W

    2015-10-01

    The synthesis and characterization of a degradable version of poly(acrylic acid), poly(glyceric acid carbonate), are reported. Specifically, atactic and isotactic poly(benzyl glycidate carbonate)s are obtained via the ring-opening copolymerization of rac-/(R)-benzyl glycidate with CO2 using a bifunctional rac-/(S,S)-cobalt salen catalyst in high carbonate linkage selectivity (>99%) and polymer/cyclic carbonate selectivity (∼90%). Atactic poly(benzyl glycidate carbonate) is an amorphous material with a T(g) (glass transition temperature) of 44 °C, while its isotactic counterpart synthesized from enantiopure epoxide and catalyst is semicrystalline with a T(m) (melting temperature) = 87 °C. Hydrogenolysis of the resultant polymers affords the poly(glyceric acid carbonate). Poly(glyceric acid carbonate) exhibits an improved cell cytotoxicity profile compared to poly(acrylic acid). Poly(glyceric acid carbonate)s also degrade remarkably fast (t(1/2) ≈ 2 weeks) compared to poly(acrylic acid). Cross-linked hydrogels prepared from poly(glyceric acid carbonate) and poly(ethylene glycol) diaziridine show significant degradation in pH 8.4 aqueous buffer solution compared to similarly prepared hydrogels from poly(acrylic acid) and poly(ethylene glycol) diaziridine. PMID:26378624

  14. Acidities of Water and Methanol in Aqueous Solution and DMSO

    ERIC Educational Resources Information Center

    Gao, Daqing

    2009-01-01

    The relative acidities of water and methanol have been a nagging issue. In gas phase, methanol is more acidic than water by 36.0 kJ/mol; however, in aqueous solution, the acidities of methanol and water are almost identical. The acidity of an acid in solution is determined by both the intrinsic gas-phase ionization Gibbs energy and the solvent…

  15. Acidities of Water and Methanol in Aqueous Solution and DMSO

    ERIC Educational Resources Information Center

    Gao, Daqing

    2009-01-01

    The relative acidities of water and methanol have been a nagging issue. In gas phase, methanol is more acidic than water by 36.0 kJ/mol; however, in aqueous solution, the acidities of methanol and water are almost identical. The acidity of an acid in solution is determined by both the intrinsic gas-phase ionization Gibbs energy and the solvent

  16. Pictorial Analogies XI: Concentrations and Acidity of Solutions.

    ERIC Educational Resources Information Center

    Fortman, John J.

    1994-01-01

    Presents pictorial analogies of several concepts relating to solutions for chemistry students. These include concentration of solution, strength of solution, supersaturated solution, and conjugate acid-base pairs. Among the examples are comparison of acid strength to percentage of strong soldiers or making supersaturated solution analogous to a…

  17. Pictorial Analogies XI: Concentrations and Acidity of Solutions.

    ERIC Educational Resources Information Center

    Fortman, John J.

    1994-01-01

    Presents pictorial analogies of several concepts relating to solutions for chemistry students. These include concentration of solution, strength of solution, supersaturated solution, and conjugate acid-base pairs. Among the examples are comparison of acid strength to percentage of strong soldiers or making supersaturated solution analogous to a

  18. REACTIONS OF CHLORITE WITH ACTIVATED CARBON AND WITH VANILLIC ACID AND INDAN ADSORBED ON ACTIVATED CARBON

    EPA Science Inventory

    The reaction between chlorite (CO2(-1)) and vanillic acid, at pH 6.0 in the presence of granular activated carbon (GAC), yielded several reaction products identifiable by GC/MS; no products were found in the absence of GAC. Indan and ClO2 or ClO2(-1) reacted in aqueous solution a...

  19. Solution influence on biomolecular equilibria - Nucleic acid base associations

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Pratt, L. R.; Burt, S. K.; Macelroy, R. D.

    1984-01-01

    Various attempts to construct an understanding of the influence of solution environment on biomolecular equilibria at the molecular level using computer simulation are discussed. First, the application of the formal statistical thermodynamic program for investigating biomolecular equilibria in solution is presented, addressing modeling and conceptual simplications such as perturbative methods, long-range interaction approximations, surface thermodynamics, and hydration shell. Then, Monte Carlo calculations on the associations of nucleic acid bases in both polar and nonpolar solvents such as water and carbon tetrachloride are carried out. The solvent contribution to the enthalpy of base association is positive (destabilizing) in both polar and nonpolar solvents while negative enthalpies for stacked complexes are obtained only when the solute-solute in vacuo energy is added to the total energy. The release upon association of solvent molecules from the first hydration layer around a solute to the bulk is accompanied by an increase in solute-solvent energy and decrease in solvent-solvent energy. The techniques presented are expectd to displace less molecular and more heuristic modeling of biomolecular equilibria in solution.

  20. Rapid analysis of acid in etching and pickling solutions

    SciTech Connect

    Tumbina, V.P.; Chinokalov, V.Ya.

    1995-02-01

    A computational method for determining sulfuric and hydrochloric acids in two-component etching solutions has been proposed. The method makes use of linear relationships, assuming that the sum of free and bound acid in solution remains constant.

  1. Interaction of solid organic acids with carbon nanotube field effect transistors

    NASA Astrophysics Data System (ADS)

    Klinke, Christian; Afzali, Ali; Avouris, Phaedon

    2006-10-01

    A series of solid organic acids were used to p-dope carbon nanotubes. The extent of doping is shown to be dependent on the pKa value of the acids. Highly fluorinated carboxylic acids and sulfonic acids are very effective in shifting the threshold voltage and making carbon nanotube field effect transistors to be more p-type devices. Weaker acids like phosphonic or hydroxamic acids had less effect. The doping of the devices was accompanied by a reduction of the hysteresis in the transfer characteristics. In-solution doping survives standard fabrication processes and renders p-doped carbon nanotube field effect transistors with good transport characteristics.

  2. Solubilities of carbon dioxide in aqueous potassium carbonate solutions mixed with physical solvents

    SciTech Connect

    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 selected 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.

  3. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-06

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid. 4 figs.

  4. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1993-01-01

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid.

  5. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E. Philip (Naperville, IL); Dietz, Mark L. (Evanston, IL)

    1994-01-01

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid.

  6. Synthesis of carbon-13-labeled tetradecanoic acids.

    PubMed

    Sparrow, J T; Patel, K M; Morrisett, J D

    1983-07-01

    The synthesis of tetradecanoic acid enriched with 13C at carbons 1, 3, or 6 is described. The label at the carbonyl carbon was introduced by treating 1-bromotridecane with K13CN (90% enriched) to form the 13C-labeled nitrile, which upon hydrolysis yielded the desired acid. The [3-13C]tetradecanoic acid was synthesized by alkylation of diethyl sodio-malonate with [1-13C]1-bromododecane; the acid was obtained upon saponification and decarboxylation. The label at the 6 position was introduced by coupling the appropriately labeled alkylcadmium chloride with the half acid chloride methyl ester of the appropriate dioic acid, giving the corresponding oxo fatty acid ester. Formation of the tosylhydrazone of the oxo-ester followed by reduction with sodium cyanoborohydride gave the labeled methyl tetradecanoate which, upon hydrolysis, yielded the desired tetradecanoic acid. All tetradecanoic acids were identical to unlabeled analogs as evaluated by gas-liquid chromatography and infrared or NMR spectroscopy. These labeled fatty acids were used subsequently to prepare the correspondingly labeled diacyl phosphatidylcholines. PMID:6631228

  7. Toluene nitration in irradiated nitric acid and nitrite solution

    SciTech Connect

    Gracy Elias; Bruce J. Mincher; Stephen P. Mezyk; Jim Muller; Leigh R. Martin

    2011-04-01

    The kinetics, mechanisms, and stable products produced for the aryl alkyl mild ortho-para director - toluene, in irradiated nitric acid and neutral nitrite solutions were investigated using ?, and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection was primarily used to assess the stable reaction products. GC-MS and LC-MS were used to confirm the results from HPLC. Free-radical nitration reaction products were found in irradiated acidic and neutral media. In acidic medium, the ring substitution and side chain substitution and oxidation produced different nitro products. In ring substitution, nitrogen oxide radicals were added mainly to hydroxyl radical-produced cyclohexadienyl radical, and in side chain substitution they were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite toluene solution, radiolytic ring nitration products approached a statistically random distribution, suggesting a free-radical reaction involving addition of the NO2 radical.

  8. Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media.

    PubMed

    Moret, Séverine; Dyson, Paul J; Laurenczy, Gábor

    2014-01-01

    The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40 °C, 0.2 M formic acid can be obtained under 200 bar, however, in DMSO the same catalyst affords 1.9 M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes. PMID:24886955

  9. Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media

    PubMed Central

    Moret, Séverine; Dyson, Paul J.; Laurenczy, Gábor

    2014-01-01

    The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40 °C, 0.2 M formic acid can be obtained under 200 bar, however, in DMSO the same catalyst affords 1.9 M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes. PMID:24886955

  10. Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility

    NASA Technical Reports Server (NTRS)

    Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

    1990-01-01

    The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

  11. Methods of pretreating comminuted cellulosic material with carbonate-containing solutions

    DOEpatents

    Francis, Raymond

    2012-11-06

    Methods of pretreating comminuted cellulosic material with an acidic solution and then a carbonate-containing solution to produce a pretreated cellulosic material are provided. The pretreated material may then be further treated in a pulping process, for example, a soda-anthraquinone pulping process, to produce a cellulose pulp. The pretreatment solutions may be extracted from the pretreated cellulose material and selectively re-used, for example, with acid or alkali addition, for the pretreatment solutions. The resulting cellulose pulp is characterized by having reduced lignin content and increased yield compared to prior art treatment processes.

  12. Arterial Blood Carbonic Acid Inversely Determines Lactic and Organic Acids

    PubMed Central

    Aiken, Christopher Geoffrey Alexander

    2013-01-01

    Objective: To establish that arterial blood carbonic acid varies inversely with lactic acid in accordance with bicarbonate exchanging for lactate across cell membranes through the anion exchange mechanism to maintain the Gibbs-Donnan equilibrium. Study Design: Over 5 years, lactate was measured on all blood gases taken from neonatal admissions, as well as organic acid whenever electrolytes were required. Results: Arterial blood gases from 63 infants given high calcium TPN were analyzed. Twenty two needed continuous positive airways pressure (CPAP) only and 31 intermittent positive pressure ventilation (IPPV) and surfactant followed by CPAP to treat respiratory distress syndrome in 51 and meconium aspiration syndrome in 2. All survived and were free of infection. Excluded gases were those with high and falling lactate soon after delivery representing perinatal asphyxia, and those on dexamethasone. Strong inverse relations between carbonic and lactic acids were found at all gestational ages and, independent of glomerular filtration, between carbonic and organic acids. Lactate (mmol/L) = 62.53 X PCO2 -0.96(mmHg) r2 0.315, n 1232, p <0.001. Sixty divided by PCO2 is a convenient measure of physiological lactate at any given PCO2. In the first week, 9.13 2.57% of arterial gases from infants on IPPV had lactates above 120/PCO2, significantly more than 4.74 2.73% on CPAP (p<0.05) and 2.47 2.39% on no support. Conclusion: Changes in arterial blood carbonic acid cause immediate inverse changes in lactic acid, because their anions interchange across cell membranes according to the Gibbs Donnan equilibrium. Increasing PCO2 from 40 to 120 mmHg decreased lactate from 1.5 mmol/L to 0.5 mmol/L, so that the sum of carbonic and lactic acids increased from 2.72 mmol/L to only 4.17 mmol/L. This helps explain the neuroprotective effect of hypercapnoea and highlights the importance of avoiding any degree of hypocapnoea in infants on IPPV. PMID:24392387

  13. Solution-Processable Carbon Nanoelectrodes for Single-Molecule Investigations.

    PubMed

    Zhu, Jingyuan; McMorrow, Joseph; Crespo-Otero, Rachel; Ao, Geyou; Zheng, Ming; Gillin, William P; Palma, Matteo

    2016-03-01

    Here we present a solution-based assembly method for producing molecular transport junctions employing metallic single-walled carbon nanotubes as nanoelectrodes. The molecular junction conductance of a series of oligophenyls was successfully measured, highlighting the potential of an all-carbon based approach for the fabrication of solution-processable single-molecule junctions for molecular electronics. PMID:26854787

  14. pH-metric determination of ammonium carbonate and bicarbonate in solutions containing ammonium vanadate

    SciTech Connect

    Fofanov, Al.A.; Yuorenko, V.V.; Kharlampieva, T.I.; Potapov, V.I.

    1986-07-01

    Ammonium carbonate and bicarbonate and ammonium carbonate salts used in hydrometallurgy are characterized by low stability both in solid form and in solutions. The frequently used method of acid-base titration in the presence of a pH indicator is unsuitable in the presence of ions in solution that change color within the investigated pH range. The purpose of this paper is to develop a method of rapid determination of the concentration of ammonium carbonate and bicarbonate in solutions containing ammonium vanadate. The authors used a 0.1 M solution of hydrochloric acid, analytical grade ammonium vanadate, and ammonium carbonate salts, the composition of which approximates real technological solutions. An aliquot portion of the test solution (1-2 ml) is transferred to a 50-ml beaker, and 10 ml of distilled water is added. The electrodes of the pH meter are placed in the solution, and it is titrated with 0.1 M hydrochloric acid with constant mixing.

  15. Process for recovering uranium using an alkyl pyrophosphoric acid and alkaline stripping solution

    SciTech Connect

    Worthington, R.E.; Magdics, A.

    1987-03-24

    A process is described for stripping uranium from a pregnant organic extractant comprising an alkyl pyrophosphoric acid dissolved in a substantially water-immiscible organic diluent. The organic extractant contains tetravalent uranium and an alcohol or phenol modifier in a quantity sufficient to retain substantially all the unhydrolyzed alkyl pyrophosphoric acid in solution in the diluent during stripping. The process comprises adding an oxidizing agent to the organic extractant to and thereby oxidizing the tetravalent uranium to the +6 state in the organic extractant, and contacting the organic extractant containing the uranium in the +6 state with a stripping solution comprising an aqueous solution of an alkali metal or ammonium carbonate, nonsaturated in uranium. The uranium is stripped from, the organic extractant into the stripping solution, and the resulting barren organic extractant containing substantially all of the unhydrolyzed alkyl pyrophosphoric acid dissolved in the diluent is separated from the stripping solution containing the stripped uranium, the barren extractant being suitable for recycle.

  16. Process for recovering uranium using an alkyl pyrophosphoric acid and alkaline stripping solution

    SciTech Connect

    Worthington, R.E.; Magdics, A.

    1987-03-24

    A process is described for stripping uranium for a pregnant organic extractant comprising an alkyl pyrophosphoric acid dissolved in a substantially water-immiscible organic diluent. The organic extractant contains tetravalent uranium and an alcohol or phenol modifier in a quantity sufficient to retain substantially all the unhydrolyzed alkyl pyrophosphoric acid in solution in the diluent during stripping. The process comprises adding an oxidizing agent to the organic extractant and thereby oxidizing the tetravalent uranium to the +6 state in the organic extractant, and contacting the organic extractant containing the uranium in the +6 state with a stripping solution comprising an aqueous solution of an alkali metal or ammonium carbonate or hydroxide thereby stripping uranium from the organic extractant into the stripping solution. The resulting barren organic extractant containing substantially all of the unhydrolyzed alkyl pyrophosphoric acid dissolved in the diluent is separated from the stripping solution containing the stripped uranium, the barren extractant being suitable for recycle.

  17. Process for the recovery of strontium from acid solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1992-03-31

    The invention is a process for selectively extracting strontium and technetium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant is a macrocyclic polyether in a diluent which is insoluble in water, but which will itself dissolve a small amount of water. The process will extract strontium and technetium values from nitric acid solutions which are up to 6 molar in nitric acid. 5 figs.

  18. Process for the recovery of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip (Naperville, IL); Dietz, Mark L. (Evanston, IL)

    1992-01-01

    The invention is a process for selectively extracting strontium and technetium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant is a macrocyclic polyether in a diluent which is insoluble in water, but which will itself dissolve a small amount of water. The process will extract strontium and technetium values from nitric acid solutions which are up to 6 molar in nitric acid.

  19. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

    2014-04-01

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

  20. PERFORMANCE AND MODELING OF A HOT POTASSIUM CARBONATE ACID GAS REMOVAL SYSTEM IN TREATING COAL GAS

    EPA Science Inventory

    The report discusses the performance and modeling of a hot potassium carbonate (K2CO3) acid gas removal system (AGRS) in treating coal gas. Aqueous solutions of K2CO3, with and without amine additive, were used as the acid gas removal solvent in the Coal Gasification/Gas Cleaning...

  1. Picosecond Pulse Radiolysis of Highly Concentrated Carbonate Solutions.

    PubMed

    Ghalei, Mohammad; Ma, Jun; Schmidhammer, Uli; Vandenborre, Johan; Fattahi, Massoud; Mostafavi, Mehran

    2016-03-10

    Highly concentrated potassium carbonate aqueous solutions are studied by picosecond pulse radiolysis with the purpose of exploring the formation processes of carbonate radical CO3(•-). The transient absorption band of solvated electron produced by ionizing is markedly shifted from 715 to 600 nm when the solute concentration of K2CO3 is 5 mol L(-1). This spectral shift is even more important than that observed for the solvated electron in 10 mol L(-1) KOH solutions. The broad absorption band of solvated electron in K2CO3 solutions overlaps with that of carbonate radical CO3(•-) formed at ultrashort time. Nitrate ion is used to scavenge the solvated electron and to observe the contribution of carbonate radical CO3(•-). The analysis of the amplitude and the kinetics of carbonate radical formation in highly concentrated solutions shows that CO3(•-) is formed within the electron pulse (7 ps) by two parallel mechanisms: a direct effect on the solute and the oxidation of the solute by water radical hole H2O(•+). These two mechanisms are followed by an additional one, by reaction between the solute and OH(•) radical especially in lower concentration. The radiolytic yield of each process is discussed. PMID:26885876

  2. Titration of Monoprotic Acids with Sodium Hydroxide Contaminated by Sodium Carbonate.

    ERIC Educational Resources Information Center

    Michalowski, Tadeusz

    1988-01-01

    Discusses the effects of using carbon dioxide contaminated sodium hydroxide solution as a titrant for a solution of a weak monoprotic acid and the resulting distortion of the titration curve in comparison to one obtained when an uncontaminated titrant is used. (CW)

  3. In situ synthesis carbonated hydroxyapatite layers on enamel slices with acidic amino acids by a novel two-step method.

    PubMed

    Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke

    2015-09-01

    In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). PMID:26046278

  4. Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon.

    PubMed

    Rohwerder, Thore; Müller, Roland H

    2010-01-01

    Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE) in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB). This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source. PMID:20184738

  5. Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon

    PubMed Central

    2010-01-01

    Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE) in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB). This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source. PMID:20184738

  6. Method for liquid chromatographic extraction of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip (Naperville, IL); Dietz, Mark L. (Evanston, IL)

    1992-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  7. Reductive dechlorination of carbon tetrachloride using buffered alkaline ascorbic acid.

    PubMed

    Lin, Ya-Ting; Liang, Chenju

    2015-10-01

    Alkaline ascorbic acid (AA) was recently discovered as a novel in-situ chemical reduction (ISCR) reagent for remediating chlorinated solvents in the subsurface. For this ISCR process, the maintenance of an alkaline pH is essential. This study investigated the possibility of the reduction of carbon tetrachloride (CT) using alkaline AA solution buffered by phosphate and by NaOH. The results indicated that CT was reduced by AA, and chloroform (CF) was a major byproduct at a phosphate buffered pH of 12. However, CT was completely reduced by AA in 2M NaOH without CF formation. In the presence of iron/soil minerals, iron could be reduced by AA and Fe(2+) tends to precipitate on the mineral surface to accelerate CT degradation. A simultaneous transfer of hydrogenolysis and dichloroelimination would occur under phosphate buffered pH 12. This implies that a high alkaline environment is a crucial factor for maintaining the dominant pathway of two electron transfer from dianionic AA to dehydroascorbic acid, and to undergo dichloroelimination of CT. Moreover, threonic acid and oxalic acid were identified to be the major AA decomposition products in alkaline solutions. PMID:25912910

  8. Browning in ethanolic solutions of ascorbic acid and catechin.

    PubMed

    Chuang, Pei-Ting; Shen, Szu-Chuan; Wu, James Swi-Bea

    2011-07-27

    Nonenzymatic browning occurs readily in alcoholic beverages and degrades their color quality. Ascorbic acid degradation in the presence of phenolic compounds is a major browning pathway in alcoholic beverages with fruit or fruit juice as the raw material or an ingredient. In the present study ethanolic solutions of ascorbic acid and catechin were prepared to simulate the alcoholic beverages. Ascorbic acid degradation and browning in these model solutions were investigated. Glycerol solutions with the same water activity (A(w)) values as those of the ethanolic model solutions were used as controls in the evaluation of browning rate. Results showed that the aerobic degradation of ascorbic acid dominates over the anaerobic one in ethanolic solutions, that the browning rate decreases as the ethanol concentration increases, that the compound 3-hydroxy-2-pyrone may not be a good indicator of browning in ethanolic ascorbic acid-catechin solutions, and that A(w) is a major factor responsible for the difference in the browning rate among ascorbic acid-catechin solutions with different ethanol concentrations. PMID:21668002

  9. Nickel embedded in N-doped porous carbon for the hydrogenation of nitrobenzene to p-aminophenol in sulphuric acid.

    PubMed

    Wang, Tao; Dong, Zhen; Fu, Teng; Zhao, Yanchao; Wang, Tian; Wang, Yongzheng; Chen, Yi; Han, Baohang; Ding, Weiping

    2015-12-01

    An acid-resistant catalyst composed of nickel embedded in N-doped porous carbon is developed for the catalytic hydrogenation of nitrobenzene (NB) to p-aminophenol (PAP). The catalyst, due to a special electron donation from nickel to the N-doped porous carbon, shows an excellent catalytic performance and stability in sulphuric acid solution. PMID:26489366

  10. Isotope composition of carbon in amino acids of solid bitumens

    NASA Astrophysics Data System (ADS)

    Shanina, S. N.; Bushnev, D. A.

    2014-06-01

    Primary data are presented on the isotope composition of carbon in individual amino acids from solid bitumens and several biological objects. The amino acids of biological objects are characterized by wide variations of the isotope composition of carbon. This fact occurs owing to the difference in biochemical paths of metabolism resulting in the synthesis of individual amino acids. The ?13C values are somewhat decreased for individual amino acids in asphaltenes, varying from -7.7 to -31.7. The carbon of amino acids is weighted in kerits from Bad'el' compared to asphaltenes. All the natural bitumens retain the characteristic trend for natural substances: the isotopically heavy and light amino acids by carbon are glycine and leucine, respectively. The isotope composition of amino-acid carbon is lightened compared to natural bitumens in the samples formed under a pronounced thermal impact (asphalt-like crust and kirishite).

  11. SAVANNAH RIVER SITE TANK CLEANING: CORROSION RATE FOR ONE VERSUS EIGHT PERCENT OXALIC ACID SOLUTION

    SciTech Connect

    Ketusky, E.; Subramanian, K.

    2011-01-20

    Until recently, the use of oxalic acid for chemically cleaning the Savannah River Site (SRS) radioactive waste tanks focused on using concentrated 4 and 8-wt% solutions. Recent testing and research on applicable dissolution mechanisms have concluded that under appropriate conditions, dilute solutions of oxalic acid (i.e., 1-wt%) may be more effective. Based on the need to maximize cleaning effectiveness, coupled with the need to minimize downstream impacts, SRS is now developing plans for using a 1-wt% oxalic acid solution. A technology gap associated with using a 1-wt% oxalic acid solution was a dearth of suitable corrosion data. Assuming oxalic acid's passivation of carbon steel was proportional to the free oxalate concentration, the general corrosion rate (CR) from a 1-wt% solution may not be bound by those from 8-wt%. Therefore, after developing the test strategy and plan, the corrosion testing was performed. Starting with the envisioned process specific baseline solvent, a 1-wt% oxalic acid solution, with sludge (limited to Purex type sludge-simulant for this initial effort) at 75 C and agitated, the corrosion rate (CR) was determined from the measured weight loss of the exposed coupon. Environmental variations tested were: (a) Inclusion of sludge in the test vessel or assuming a pure oxalic acid solution; (b) acid solution temperature maintained at 75 or 45 C; and (c) agitation of the acid solution or stagnant. Application of select electrochemical testing (EC) explored the impact of each variation on the passivation mechanisms and confirmed the CR. The 1-wt% results were then compared to those from the 8-wt%. The immersion coupons showed that the maximum time averaged CR for a 1-wt% solution with sludge was less than 25-mils/yr for all conditions. For an agitated 8-wt% solution with sludge, the maximum time averaged CR was about 30-mils/yr at 50 C, and 86-mils/yr at 75 C. Both the 1-wt% and the 8-wt% testing demonstrated that if the sludge was removed from the testing, there would be a significant increase in the CR. Specifically, the CR for an agitated 1-wt% pure oxalic acid solution at 45 or 75 C was about 4 to 10 times greater than those for a 1-wt% solution with sludge. For 8-wt% at 50 C, the effect was even larger. The lower CRs suggest that the cathodic reactions were altered by the sludge. For both the 1-wt% and 8-wt% solution, increasing the temperature did not result in an increased CR. Although the CR for a 1-wt% acid with sludge was considered to be non-temperature dependent, a stagnant solution with sludge resulted in a CR that was greater at 45 C than at 75 C, suggesting that the oxalate film formed at a higher temperature was better in mitigating corrosion. For both a 1 and an 8-wt% solution, agitation typically resulted in a higher CR. Overall, the testing showed that the general CR to the SRS carbon steel tanks from 1-wt% oxalic acid solution will remain bounded by those from an 8-wt% oxalic acid solution.

  12. Nylon Dissolution in Nitric Acid Solutions

    SciTech Connect

    KESSINGER, GLENF.

    2004-06-16

    H Area Operations is planning to process Pu-contaminated uranium scrap in support of de-inventory efforts. Nylon bags will be used to hold materials to be dissolved in H-Canyon. Based on this set of twelve nylon dissolutions, it is concluded that (when other variables are held constant): increased acid concentration results in increased dissolution rates; increased acid concentration results in a lower dissolution onset temperature; little, if any, H plus is consumed during the depolymerization process; and 2.0-3.0 M HNO3, with 0.025 M KF and 2 g/L B, is satisfactory for the dissolution of nylon bag materials to be used during H-Canyon processing.

  13. Polymerization of β-amino Acids in Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Liu, Rihe; Orgel, Leslie E.

    1998-02-01

    We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged α- and β-amino acids in homogeneous aqueous solution. α-Amino acids can be oligomerized efficiently using CDI, but not by EDAC. β-Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an α- and β-dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.

  14. Polymerization of beta-amino acids in aqueous solution

    NASA Technical Reports Server (NTRS)

    Liu, R.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1998-01-01

    We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged alpha- and beta-amino acids in homogeneous aqueous solution. alpha-Amino acids can be oligomerized efficiently using CDI, but not by EDAC. beta-Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an alpha- and beta-dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.

  15. Raman spectra of amino acids and their aqueous solutions

    NASA Astrophysics Data System (ADS)

    Zhu, Guangyong; Zhu, Xian; Fan, Qi; Wan, Xueliang

    2011-03-01

    Amino acids are the basic "building blocks" that combine to form proteins and play an important physiological role in all life-forms. Amino acids can be used as models for the examination of the importance of intermolecular bonding in life processes. Raman spectra serve to obtain information regarding molecular conformation, giving valuable insights into the topology of more complex molecules (peptides and proteins). In this paper, amino acids and their aqueous solution have been studied by Raman spectroscopy. Comparisons of certain values for these frequencies in amino acids and their aqueous solutions are given. Spectra of solids when compared to those of the solute in solution are invariably much more complex and almost always sharper. We present a collection of Raman spectra of 18 kinds of amino acids ( L-alanine, L-arginine, L-aspartic acid, cystine, L-glutamic acid, L-glycine, L-histidine, L-isoluecine, L-leucine, L-lysine, L-phenylalanine, L-methionone, L-proline, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine) and their aqueous solutions that can serve as references for the interpretation of Raman spectra of proteins and biological materials.

  16. Vacuum-jacketed hydrofluoric acid solution calorimeter

    USGS Publications Warehouse

    Robie, R.A.

    1965-01-01

    A vacuum-jacketed metal calorimeter for determining heats of solution in aqueous HF was constructed. The reaction vessel was made of copper and was heavily gold plated. The calorimeter has a cooling constant of 0.6 cal-deg -1-min-1, approximately 1/4 that of the air-jacketed calorimeters most commonly used with HF. It reaches equilibrium within 10 min after turning off the heater current. Measurements of the heat of solution of reagent grade KCl(-100 mesh dried 2 h at 200??C) at a mole ratio of 1 KCl to 200 H2O gave ??H = 4198??11 cal at 25??C. ?? 1965 The American Institute of Physics.

  17. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, Gary A [Kennewick, WA; Smith, Jeffrey W [Lancaster, OH; Ihle, Nathan C [Walla Walla, WA

    1984-01-01

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH).sub.2 to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with portland cement to form concrete.

  18. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, G.A.; Smith, J.W.; Ihle, N.C.

    1982-07-08

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH)/sub 2/ to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with Portland cement to form concrete.

  19. Pulse radiolysis of pyridinecarboxylic acids in aqueous solution

    NASA Astrophysics Data System (ADS)

    Solar, S.; Getoff, N.; Sehested, K.; Holcman, J.

    The reactivity of OH, e -aq and H radicals towards aqueous carboxypyridines: picolinic acid (2-pyridinecarboxylic acid), PA; isonicotinic acid (4-pyridinecarboxylic acid), i-NA; 2,6-pyridinedicarboxylic acid, 2,6-PDCA; and 3,5-pyridinedicarboxylic acid, 3,5-PDCA was investigated in the pH-range 1-13.8. The absorption spectra of the OH-adducts, H-adducts and pyridinyl radicals are given as well as the formation and decay kinetics. In acid (but not in alkaline) solution, the reaction of H-atoms leads to the formation of two distinct products, namely H-adduct and pyridinyl radicals. The yields of pyridinyl radical are: 20% for PA, 75% for i-NA, 60% for 2,6-PDCA and 25% for 3,5-PDCA (a yield of 50% has been found earlier for nicotinic acid, NA).

  20. Hydrogen storage and delivery: the carbon dioxide - formic acid couple.

    PubMed

    Laurenczy, Gábor

    2011-01-01

    Carbon dioxide and the carbonates, the available natural C1 sources, can be easily hydrogenated into formic acid and formates in water; the rate of this reduction strongly depends on the pH of the solution. This reaction is catalysed by ruthenium(II) pre-catalyst complexes with a large variety of water-soluble phosphine ligands; high conversions and turnover numbers have been realised. Although ruthenium(II) is predominant in these reactions, the iron(II) - tris[(2-diphenylphosphino)-ethyl]phosphine (PP3) complex is also active, showing a new perspective to use abundant and inexpensive iron-based compounds in the CO2 reduction. In the catalytic hydrogenation cycles the in situ formed metal hydride complexes play a key role, their structures with several other intermediates have been proven by multinuclear NMR spectroscopy. In the other hand safe and convenient hydrogen storage and supply is the fundamental question for the further development of the hydrogen economy; and carbon dioxide has been recognised to be a viable H2 vector. Formic acid--containing 4.4 weight % of H2, that is 53 g hydrogen per litre--is suitable for H2 storage; we have shown that in aqueous solutions it can be selectively decomposed into CO-free (CO < 10 ppm) CO2 and H2. The reaction takes place under mild experimental conditions and it is able to generate high pressure H2 (up to 600 bar). The cleavage of HCOOH is catalysed by several hydrophilic Ru(II) phosphine complexes (meta-trisulfonated triphenylphosphine, mTPPTS, being the most efficient one), either in homogeneous systems or as immobilised catalysts. We have also shown that the iron(II)--hydrido tris[(2-diphenylphosphino)ethyl]phosphine complex catalyses with an exceptionally high rate and efficiency (turnover frequency, TOF = 9425 h(-1)mol(-1); turnover number, TON = 92400) the formic acid cleavage, in environmentally friendly propylene carbonate solution, opening the way to use cheap, non-noble metal based catalysts for this reaction, too. PMID:22026175

  1. Precipitation of plutonium from acidic solutions using magnesium oxide

    SciTech Connect

    Jones, S.A.

    1994-12-05

    Magnesium oxide will be used as a neutralizing agent for acidic plutonium-containing solutions. It is expected that as the magnesium oxide dissolves, the pH of the solution will rise, and plutonium will precipitate. The resulting solid will be tested for suitability to storage. The liquid is expected to contain plutonium levels that meet disposal limit requirements.

  2. Improved method for extracting lanthanides and actinides from acid solutions

    DOEpatents

    Horwitz, E.P.; Kalina, D.G.; Kaplan, L.; Mason, G.W.

    1983-07-26

    A process for the recovery of actinide and lanthanide values from aqueous acidic solutions uses a new series of neutral bi-functional extractants, the alkyl(phenyl)-N,N-dialkylcarbamoylmethylphosphine oxides. The process is suitable for the separation of actinide and lanthanide values from fission product values found together in high-level nuclear reprocessing waste solutions.

  3. Phosphorylation of glyceric acid in aqueous solution using trimetaphosphate.

    PubMed

    Kolb, V; Orgel, L E

    1996-02-01

    The phosphorylation of glyceric acid is an interesting prebiotic reaction because it converts a simple, potentially prebiotic organic molecule into phosphate derivatives that are central to carbohydrate metabolism. We find that 0.05 M glyceric acid in the presence of 0.5 M trimetaphosphate in alkaline solution gives a mixture of 2- and 3-phosphoglyceric acids in combined yields of up to 40%. PMID:11536746

  4. Phosphorylation of Glyceric Acid in Aqueous Solution Using Trimetaphosphate

    NASA Technical Reports Server (NTRS)

    Kolb, Vera; Orgel, Leslie E.

    1996-01-01

    The phosphorylation of glyceric acid is an interesting prebiotic reaction because it converts a simple, potentially prebiotic organic molecule into phosphate derivatives that are central to carbohydrate metabolism. We find that 0.05 M glyceric acid in the presence of 0.5 M trimetaphosphate in alkaline solution gives a mixture of 2- and 3-phosphoglyceric acids in combined yields of up to 40%.

  5. REMOVAL OF CHLORIDE FROM ACIDIC SOLUTIONS USING NO2

    SciTech Connect

    Visser, A; Robert Pierce, R; James Laurinat, J

    2006-08-22

    Chloride (Cl{sup -}) salt processing in strong acids is used to recycle plutonium (Pu) from pyrochemical residues. The Savannah River National Laboratory (SRNL) is studying the potential application of nitrogen dioxide (NO{sub 2}) gas to effectively convert dissolved pyrochemical salt solutions to chloride-free solutions and improve recovery operations. An NO{sub 2} sparge has been shown to effectively remove Cl{sup -} from solutions containing 6-8 M acid (H{sup +}) and up to 5 M Cl{sup -}. Chloride removal occurs as a result of the competition of at least two reactions, one which is acid-dependent. Below 4 M H+, NO2 reacts with Cl- to produce nitrosyl chloride (ClNO). Between 6 M and 8 M H{sup +}, the reaction of hydrochloric acid (HCl) with nitric acid (HNO{sub 3}), facilitated by the presence of NO{sub 2}, strongly affects the rate of Cl{sup -} removal. The effect of heating the acidic Cl{sup -} salt solution without pre-heating the NO{sub 2} gas has minimal effect on Cl{sup -} removal rates when the contact times between NO{sub 2} and the salt solution are on the order of seconds.

  6. Inhibition of nitrobenzene adsorption by water cluster formation at acidic oxygen functional groups on activated carbon.

    PubMed

    Kato, Yuichi; Machida, Motoi; Tatsumoto, Hideki

    2008-06-15

    The inhibition effect of nitrobenzene adsorption by water clusters formed at the acidic groups on activated carbon was examined in aqueous and n-hexane solution. The activated carbon was oxidized with nitric acid to introduce CO complexes and then outgassed in helium flow at 1273 K to remove them completely without changing the structural properties of the carbon as a reference adsorbent. The amounts of acidic functional groups were determined by applying Boehm titration. A relative humidity of 95% was used to adsorb water onto the carbon surface. Strong adsorption of water onto the oxidized carbon can be observed by thermogravimetric analysis. The adsorption kinetic rate was estimated to be controlled by diffusion from the kinetic analysis. Significant decline in both capacity and kinetic rate for nitrobenzene adsorption onto the oxidized carbon was also observed in n-hexane solution by preadsorption of water to the carbon surface, whereas it was not detected for the outgassed carbons. These results might reveal that water molecules forming clusters at the CO complexes inhibited the entrance of nitrobenzene into the interparticles of the carbon. PMID:18440013

  7. Electrochemical determination of tartaric acid at nano gold/nano carbon modified glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Song, Yang; Song, Yuanzhi; Xu, Jiang

    2012-09-01

    Nano gold/nano carbon coating the surface of glassy carbon electrode is prepared. Electrochemical behavior of tartaric acid at nano gold/graphene modified glassy carbon electrode is investigated. A simple, sensitive, and inexpensive method for determination of tartaric acid in drinks is proposed.

  8. Phase transition of carbonate solvent mixture solutions at low temperatures

    NASA Astrophysics Data System (ADS)

    Okumura, Takefumi; Horiba, Tatsuo

    2016-01-01

    The phase transition of carbonate solvent mixture solutions consisting of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and LiPF6 salt have been studied for improving the low temperature performance of lithium-ion batteries. The Li ion conductivity at 25 °C was maximum at x = 0.3 in a series of 1 M LiPF6 mixed carbonate solvents compositions consisting of ECxDMC0.5-0.5xEMC0.5-0.5x (x = 0 to 0.6), while the maximum tended to shift to x = 0.2 as the temperature lowered. The differential scanning calorimetry results showed that the freezing temperature depressions of EC in the 1 M LiPF6 solution were larger than those of the DMC or EMC. The chemical shift of 7Li nuclear magnetic resonance changed from a constant to increasing at around x = 0.3, which could be reasonably understood by focusing on the change in solvation energy calculated using Born equation. However, in the region of a high EC concentration of over x = 0.3 (EC/LiPF6 > 4) in the 1 M LiPF6 solution, the free EC from the solvation to the lithium ions seems to reduce the freezing temperature depression of the EC, and thus, decreases the ionic conductivity of the solution at low temperatures, due to the EC freezing.

  9. Modeling Corrosion Reactions of Steel in a Dilute Carbonate Solution

    NASA Astrophysics Data System (ADS)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2016-01-01

    This research models the corrosion reactions of a high-strength steel in an aerated, dilute, carbonate solution during a single-cycle voltammetry. Based on a previous study (Eliyan et al. in J Mater Eng Perform 24(6):1-8, 2015) and a literature survey, the corrosion reactions of the cathodic reduction, anodic dissolution, and passivation, as well as the interfacial interactions and the chemistry of the corrosion products are illustrated in schematics. The paper provides a visual guide on the corrosion reactions for steel in carbonate solutions based on the available mechanistic details that were reported and are still being investigated in literature.

  10. Modeling Corrosion Reactions of Steel in a Dilute Carbonate Solution

    NASA Astrophysics Data System (ADS)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2016-02-01

    This research models the corrosion reactions of a high-strength steel in an aerated, dilute, carbonate solution during a single-cycle voltammetry. Based on a previous study (Eliyan et al. in J Mater Eng Perform 24(6):1-8, 2015) and a literature survey, the corrosion reactions of the cathodic reduction, anodic dissolution, and passivation, as well as the interfacial interactions and the chemistry of the corrosion products are illustrated in schematics. The paper provides a visual guide on the corrosion reactions for steel in carbonate solutions based on the available mechanistic details that were reported and are still being investigated in literature.

  11. Solubility of small-chain carboxylic acids in supercritical carbon dioxide

    SciTech Connect

    Sparks, Darrell L.; Estevez, L. Antonio; Hernandez, Rafael; McEwen, Jason; French, Todd

    2010-07-08

    The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg • m-3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg • m-3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg • m-3 (T = 333.15 K, p = 10.0 MPa), while the highest solute concentration was (151 ± 2) kg • m-3 (T = 333.15 K, p = 26.7 MPa). In addition, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil's equation and other density-based models was evaluated for each fatty acid.

  12. Solubility of small-chain carboxylic acids in supercritical carbon dioxide

    DOE PAGESBeta

    Sparks, Darrell L.; Estevez, L. Antonio; Hernandez, Rafael; McEwen, Jason; French, Todd

    2010-07-08

    The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg • m-3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg • m-3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg • m-3 (T = 333.15 K, p = 10.0more » MPa), while the highest solute concentration was (151 ± 2) kg • m-3 (T = 333.15 K, p = 26.7 MPa). In addition, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil's equation and other density-based models was evaluated for each fatty acid.« less

  13. Influence of sulfuric acid impregnation on the carbonization of cellulose

    NASA Astrophysics Data System (ADS)

    Kang, Kyu-Young; Kim, Dae-Young

    2012-05-01

    That cellulose, as source of carbon materials, has a low char yield in pyrolysis can present serious difficulties. In this study, we focused on the effect of using sulfuric acid as a dehydration agent and examined the pyrolytic behavior of cellulose impregnated with sulfuric acid by using thermogravimetry and scanning electron microscopy. The mass yield of carbon after an 800 °C treatment in nitrogen was increased by 2-5 times with the addition of small amounts of sulfuric acid. Sample shrinkage during carbonization was also significantly reduced. These effects are interpreted as being the result of facilitated extraction of water from cellulose accompanied by development of extended carbon networks.

  14. Does Nitric Acid Dissociate at the Aqueous Solution Surface?

    SciTech Connect

    Lewis, Tanza; Winter, Berndt; Stern, Abraham C.; Baer, Marcel D.; Mundy, Christopher J.; Tobias, Douglas J.; Hemminger, J. C.

    2011-11-03

    Nitric acid is a prevalent component of atmospheric aerosols, and the extent of nitric acid dissociation at aqueous interfaces is relevant to its role in heterogeneous atmospheric chemistry. Several experimental and theoretical studies have suggested that the extent of dissociation of nitric acid near aqueous interfaces is less than in bulk solution. Here, dissociation of HNO3 at the surface of aqueous nitric acid is quantified using X-ray photoelectron spectroscopy of the nitrogen local electronic structure. The relative amounts of undissociated HNO3(aq) and dissociated NO3-(aq) are identified by the distinguishable N1s core-level photoelectron spectra of the two species, and we determine the degree of dissociation, ?int, in the interface (the first ~3 layers of solution) as a function of HNO3 concentration. Our measurements show that dissociation is decreased by approximately 20% near the solution interface compared with bulk, and furthermore that dissociation occurs even in the top-most solution layer. The experimental results are supported by first-principles MD simulations, which show that hydrogen-bonds between HNO3 and water molecules at the solution surface stabilize the molecular form at low concentration, in analogy to the stabilization of molecular HNO3 that occurs in bulk solution at high concentration. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

  15. Carbonic Acid from Decarboxylation by Malic Enzyme in Lactic Acid Bacteria

    PubMed Central

    Pilone, Gordon J.; Kunkee, Ralph E.

    1970-01-01

    Carbonic anhydrase studies were used to determine the primary form of carbonic acid produced from decarboxylation of l-malic acid by malic enzyme in malolactic strains of five different species of lactic acid bacteria. Addition of carbonic anhydrase to the reaction mixture containing crude bacterial extract and l-malic acid, at pH 7, in all five cases resulted in an increase (13 to 23%) in the rate of carbon dioxide evolution over the control. The results indicated that the primary form of carbonic acid released from malic enzyme was not anhydrous carbon dioxide as previously supposed and as has been shown for other decarboxylating enzymes. The standard free-energy changes of the malo-lactic reaction with the various forms of carbonic acid as the primary decarboxylation product were calculated. The reaction is less exergonic when carbonic acid, bicarbonate ion, or carbonate ion is the primary decarboxylation product compared to anhydrous carbon dioxide. The free-energy of the reaction is not biologically available to the bacteria; with carbon dioxide not the primary decarboxylation product, the potential energy lost in a malo-lactic fermentation is not as great as previously considered. Endogenous carbonic anhydrase activity was not found. PMID:4988241

  16. Color removal from acid and reactive dye solutions by electrocoagulation and electrocoagulation/adsorption processes.

    PubMed

    Bellebia, S; Kacha, S; Bouberka, Z; Bouyakoub, A Z; Derriche, Z

    2009-04-01

    In this study, electrocoagulation of Marine Blue Erionyl MR (acid dye) and electrocoagulation followed by adsorption of Brilliant Blue Levafix E-BRA (reactive dye) from aqueous solutions were investigated, using aluminum electrodes and granular activated carbon (GAC). In the electrocoagulation and adsorption of dyestuff solutions, the effects of current density, loading charge, pH, conductivity, stirring velocity, contact time, and GAC concentration were examined. The optimum conditions for the electrocoagulation process were identified as loading charges 7.46 and 1.49 F/m3, for a maximum abatement of 200 mg/L reactive and acid dye, respectively. The residual reactive dye concentration was completely removed with 700 mg/L GAC. The results of this investigation provide important data for the development of a combined process to remove significant concentrations of recalcitrant dyes from water, using moderate activated carbon energy and aluminum consumption, and thereby lowering the cost of treatment. PMID:19445327

  17. Dephosphorization of Steelmaking Slag by Leaching with Acidic Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Qiao, Yong; Diao, Jiang; Liu, Xuan; Li, Xiaosa; Zhang, Tao; Xie, Bing

    2015-12-01

    In the present paper, dephosphorization of steelmaking slag by leaching with acidic aqueous solution composed of citric acid, sodium hydroxide, hydrochloric acid and ion-exchanged water was investigated. The buffer solution of C6H8O7-NaOH-HCl system prevented changes in the pH values. Kinetic parameters including leaching temperature, slag particle size and pH values of the solution were optimized. The results showed that temperature has no obvious effect on the dissolution ratio of phosphorus. However, it has a significant effect on the dissolution ratio of iron. The dephosphorization rate increases with the decrease of slag particle size and the pH value of the solution. Over 90% of the phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30% below the optimal condition. Leaching kinetics of dephosphorization follow the unreacted shrinking core model with a rate controlled step by the solid diffusion layer, the corresponding apparent activation energy being 1.233 kJ mol-1. A semiempirical kinetic equation was established. After leaching, most of the nC2S-C3P solid solution in the steelmaking slag was selectively dissolved in the aqueous solution and the iron content in the solid residue was correspondingly enriched.

  18. γ-Irradiation of malic acid in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Negron-Mendoza, Alicia; Graff, Rebecca L.; Ponnamperuma, Cyril

    1980-12-01

    The γ-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 non-volatile products. Thin layer chromotography 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 γ-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.

  19. Oxidative desulfurization of askale coal by nitric acid solution

    SciTech Connect

    Guru, M.

    2007-07-01

    Efficient use of fossil fuels is of utmost importance in a world that depends on these for the greatest part of its energy needs. Although lignite is a widely used fossil fuel, its sulfur content limits its consumption. This study aims to capture combustible sulfur in the ash by oxidizing it with solution of nitric acid solution. Thus, the combustible sulfur in the coal was converted to sulfate form in the ash. Parameters affecting the conversion of sulfur were determined to be nitric acid concentration, reaction time and mean particle size at constant (near room) temperature and shaking rate. The maximum desulfurization efficiency reached was 38.7% of the original combustible sulfur with 0.3 M nitric acid solution, 16 h of reaction time and 0.1 mm mean particle size.

  20. Nature of paramagnetic centers in anodic aluminum oxide formed in a solution of tartaric acid

    NASA Astrophysics Data System (ADS)

    Chernyakova, K. V.; Ivanovskaya, M. I.; Azarko, I. I.; Vrublevskii, I. A.

    2012-10-01

    Films of anodic aluminum oxide, prepared in an aqueous solution of 0.4 M tartaric acid, are studied by means of electron paramagnetic resonance (EPR) before and after heating at 200-700C. The presence of a carbon radical is established in the films ( g factor, 2.0027 0.0002). The nature and conditions of its formation during the electrochemical oxidation of aluminum and the heat-treating of anodic aluminum oxide films are discussed.

  1. Dissolution of Simulated and Radioactive Savannah River Site High-Level Waste Sludges with Oxalic Acid & Citric Acid Solutions

    SciTech Connect

    STALLINGS, MARY

    2004-07-08

    This report presents findings from tests investigating the dissolution of simulated and radioactive Savannah River Site sludges with 4 per cent oxalic acid and mixtures of oxalic and citric acid previously recommended by a Russian team from the Khlopin Radium Institute and the Mining and Chemical Combine (MCC). Testing also included characterization of the simulated and radioactive waste sludges. Testing results showed the following: Dissolution of simulated HM and PUREX sludges with oxalic and citric acid mixtures at SRTC confirmed general trends reported previously by Russian testing. Unlike the previous Russian testing six sequential contacts of a mixture of oxalic acid citric acids at a 2:1 ratio (v/w) of acid to sludge did not produce complete dissolution of simulated HM and PUREX sludges. We observed that increased sludge dissolution occurred at a higher acid to sludge ratio, 50:1 (v/w), compared to the recommended ratio of 2:1 (v/w). We observed much lower dissolution of aluminum in a simulated HM sludge by sodium hydroxide leaching. We attribute the low aluminum dissolution in caustic to the high fraction of boehmite present in the simulated sludge. Dissolution of HLW sludges with 4 per cent oxalic acid and oxalic/citric acid followed general trends observed with simulated sludges. The limited testing suggests that a mixture of oxalic and citric acids is more efficient for dissolving HM and PUREX sludges and provides a more homogeneous dissolution of HM sludge than oxalic acid alone. Dissolution of HLW sludges in oxalic and oxalic/citric acid mixtures produced residual sludge solids that measured at higher neutron poison to equivalent 235U weight ratios than that in the untreated sludge solids. This finding suggests that residual solids do not present an increased nuclear criticality safety risk. Generally the neutron poison to equivalent 235U weight ratios of the acid solutions containing dissolved sludge components are lower than those in the untreated sludge solids. We recommend that these results be evaluated further to determine if these solutions contain sufficient neutron poisons. We observed low general corrosion rates in tests in which carbon steel coupons were contacted with solutions of oxalic acid, citric acid and mixtures of oxalic and citric acids. Wall thinning can be minimized by maintaining short contact times with these acid solutions. We recommend additional testing with oxalic and oxalic/citric acid mixtures to measure dissolution performance of sludges that have not been previously dried. This testing should include tests to clearly ascertain the effects of total acid strength and metal complexation on dissolution performance. Further work should also evaluate the downstream impacts of citric acid on the SRS High-Level Waste System (e.g., radiochemical separations in the Salt Waste Processing Facility and addition of organic carbon in the Saltstone and Defense Waste Processing facilities).

  2. Polymerization of Pu(IV) in aqueous nitric acid solutions

    SciTech Connect

    Toth, L.M.; Friedman, H.A.; Osborne, M.M.

    1980-10-01

    The polymerization of Pu(IV) in aqueous nitric acid solutions has been studied spectrophotometrically both to establish the influence of large UO{sub 2}(NO{sub 3}){sub 2} concentrations on the polymerization rates and, more generally, to review the influence of the major parameters on the polymer reaction. Typically, experiments have been performed at 50{sup 0}C and with 0.05 M Pu in nitric acid solutions that vary in acidity from 0.07 to 0.4 M. An induction period usually precedes the polymer growth stage during which time nucleation of primary hydrolysis products occurs. Uranyl nitrate retards the polymerization reaction by approximately 35% in spite of the counteracting influence of the nitrate ions associated with this solute. The rate of polymer formation, expressed as d(percent polymer)/dt, has been shown to depend on the total plutonium concentration in reactions where the Pu(IV) concentration remained constant; and it is therefore suggested that the polymer reaction rate is not first order with respect to the concentration of plutonium as was previously thought. It has been shown further that accurate acid determinations on stock reagents are essential in order to obtain reliable polymerization experiments. Satisfactory procedures for these analyses did not exist, so appropriate modifications to the iodate precipitation methods were developed. The most ideal plutonium reagent material has been shown to be crystalline Pu(IV) nitrate because it can be added directly to acid solutions without the occurrence of unintentional hydrolysis reactions.

  3. Radiolysis of aqueous solutions of 2-aminoethanethiosulfuric acid. [Gamma radiation

    SciTech Connect

    Grachev, S.A.; Koroleva, I.K.; Kropachev, E.V.; Litvyakova, G.I.

    1982-07-10

    In the radiolysis products of aerated and deaerated solutions of the 2-aminoethanethiosulfuric acid the authors have identified cystamine monoxide, cystamine, taurine, mercamine, the sulfate ion, the sulfite ion, and the dithionate ion. The yields of these products under different conditions have been determined. Results indicated that the sulfate ion is formed both from the divalent and the hexavalent sulfur atom of the 2-aminoethanethiosulfuric acid moelcule. A possible radiolysis mechanism is discussed.

  4. Method for extracting lanthanides and actinides from acid solutions by modification of purex solvent

    DOEpatents

    Horwitz, E. Philip (Naperville, IL); Kalina, Dale G. (Naperville, IL)

    1986-01-01

    A process for the recovery of actinide and lanthanide values from aqueous solutions with an extraction solution containing an organic extractant having the formula: ##STR1## where .phi. is phenyl, R.sup.1 is a straight or branched alkyl or alkoxyalkyl containing from 6 to 12 carbon atoms and R.sup.2 is an alkyl containing from 3 to 6 carbon atoms and phase modifiers in a water-immiscible hydrocarbon diluent. The addition of the extractant to the Purex process extractant, tri-n-butylphosphate in normal paraffin hydrocarbon diluent, will permit the extraction of multivalent lanthanide and actinide values from 0.1 to 12.0 molar acid solutions.

  5. Method for extracting lanthanides and actinides from acid solutions by modification of Purex solvent

    DOEpatents

    Horwitz, E.P.; Kalina, D.G.

    1986-03-04

    A process is described for the recovery of actinide and lanthanide values from aqueous solutions with an extraction solution containing an organic extractant having the formula as shown in a diagram where [phi] is phenyl, R[sup 1] is a straight or branched alkyl or alkoxyalkyl containing from 6 to 12 carbon atoms and R[sup 2] is an alkyl containing from 3 to 6 carbon atoms and phase modifiers in a water-immiscible hydrocarbon diluent. The addition of the extractant to the Purex process extractant, tri-n-butylphosphate in normal paraffin hydrocarbon diluent, will permit the extraction of multivalent lanthanide and actinide values from 0.1 to 12.0 molar acid solutions. 6 figs.

  6. Influence of Acidic and Alkaline Waste Solution Properties on Uranium Migration in Subsurface Sediments

    SciTech Connect

    Szecsody, James E.; Truex, Michael J.; Qafoku, Nikolla; Wellman, Dawn M.; Resch, Charles T.; Zhong, Lirong

    2013-08-01

    This study shows that acidic and alkaline wastes co-disposed with uranium into subsurface sediments has significant impact on changes in uranium retardation, concentration, and mass during downward migration. For uranium co-disposal with acidic wastes, significant rapid (i.e., hours) carbonate and slow (i.e., 100s of hours) clay dissolution resulted, releasing significant sediment-associated uranium, but the extent of uranium release and mobility change was controlled by the acid mass added relative to the sediment proton adsorption capacity. Mineral dissolution in acidic solutions (pH 2) resulted in a rapid (< 10 h) increase in aqueous carbonate (with Ca2+, Mg2+) and phosphate and a slow (100s of hours) increase in silica, Al3+, and K+, likely from 2:1 clay dissolution. Infiltration of uranium with a strong acid resulted in significant shallow uranium mineral dissolution and deeper uranium precipitation (likely as phosphates and carbonates) with downward uranium migration of three times greater mass at a faster velocity relative to uranium infiltration in pH neutral groundwater. In contrast, mineral dissolution in an alkaline environment (pH 13) resulted in a rapid (< 10 h) increase in carbonate, followed by a slow (10s to 100s of hours) increase in silica concentration, likely from montmorillonite, muscovite, and kaolinite dissolution. Infiltration of uranium with a strong base resulted in uranium-silicate precipitation (presumed Na-boltwoodite) but also desorption of natural uranium on the sediment due to the high ionic strength solution, or 60% greater mass with greater retardation compared with groundwater. Overall, these results show that acidic or alkaline co-contaminant disposal with uranium can result in complex depth- and time-dependent changes in uranium dissolution/precipitation reactions and uranium sorption, which alter the uranium migration mass, concentration, and velocity.

  7. Influence of acidic and alkaline waste solution properties on uranium migration in subsurface sediments

    NASA Astrophysics Data System (ADS)

    Szecsody, Jim E.; Truex, Mike J.; Qafoku, Nikolla P.; Wellman, Dawn M.; Resch, Tom; Zhong, Lirong

    2013-08-01

    This study shows that acidic and alkaline wastes co-disposed with uranium into subsurface sediments have significant impact on changes in uranium retardation, concentration, and mass during downward migration. For uranium co-disposal with acidic wastes, significant rapid (i.e., hours) carbonate and slow (i.e., 100 s of hours) clay dissolution resulted, releasing significant sediment-associated uranium, but the extent of uranium release and mobility change was controlled by the acid mass added relative to the sediment proton adsorption capacity. Mineral dissolution in acidic solutions (pH 2) resulted in a rapid (< 10 h) increase in aqueous carbonate (with Ca2 +, Mg2 +) and phosphate and a slow (100 s of hours) increase in silica, Al3 +, and K+, likely from 2:1 clay dissolution. Infiltration of uranium with a strong acid resulted in significant shallow uranium mineral dissolution and deeper uranium precipitation (likely as phosphates and carbonates) with downward uranium migration of three times greater mass at a faster velocity relative to uranium infiltration in pH neutral groundwater. In contrast, mineral dissolution in an alkaline environment (pH 13) resulted in a rapid (< 10 h) increase in carbonate, followed by a slow (10 s to 100 s of hours) increase in silica concentration, likely from montmorillonite, muscovite, and kaolinite dissolution. Infiltration of uranium with a strong base resulted in not only uranium-silicate precipitation (presumed Na-boltwoodite) but also desorption of natural uranium on the sediment due to the high ionic strength solution, or 60% greater mass with greater retardation compared with groundwater. Overall, these results show that acidic or alkaline co-contaminant disposal with uranium can result in complex depth- and time-dependent changes in uranium dissolution/precipitation reactions and uranium sorption, which alter the uranium migration mass, concentration, and velocity.

  8. Influence of acidic and alkaline waste solution properties on uranium migration in subsurface sediments.

    PubMed

    Szecsody, Jim E; Truex, Mike J; Qafoku, Nikolla P; Wellman, Dawn M; Resch, Tom; Zhong, Lirong

    2013-08-01

    This study shows that acidic and alkaline wastes co-disposed with uranium into subsurface sediments have significant impact on changes in uranium retardation, concentration, and mass during downward migration. For uranium co-disposal with acidic wastes, significant rapid (i.e., hours) carbonate and slow (i.e., 100 s of hours) clay dissolution resulted, releasing significant sediment-associated uranium, but the extent of uranium release and mobility change was controlled by the acid mass added relative to the sediment proton adsorption capacity. Mineral dissolution in acidic solutions (pH2) resulted in a rapid (<10 h) increase in aqueous carbonate (with Ca(2+), Mg(2+)) and phosphate and a slow (100 s of hours) increase in silica, Al(3+), and K(+), likely from 2:1 clay dissolution. Infiltration of uranium with a strong acid resulted in significant shallow uranium mineral dissolution and deeper uranium precipitation (likely as phosphates and carbonates) with downward uranium migration of three times greater mass at a faster velocity relative to uranium infiltration in pH neutral groundwater. In contrast, mineral dissolution in an alkaline environment (pH13) resulted in a rapid (<10h) increase in carbonate, followed by a slow (10 s to 100 s of hours) increase in silica concentration, likely from montmorillonite, muscovite, and kaolinite dissolution. Infiltration of uranium with a strong base resulted in not only uranium-silicate precipitation (presumed Na-boltwoodite) but also desorption of natural uranium on the sediment due to the high ionic strength solution, or 60% greater mass with greater retardation compared with groundwater. Overall, these results show that acidic or alkaline co-contaminant disposal with uranium can result in complex depth- and time-dependent changes in uranium dissolution/precipitation reactions and uranium sorption, which alter the uranium migration mass, concentration, and velocity. PMID:23851265

  9. The nature of the products of deprotonation of disulfonyl carbon acids in acetonitrile solvent

    NASA Astrophysics Data System (ADS)

    Binkowska, I.; Jarczewski, A.

    2006-09-01

    The series of bis(ethylsulfonyl) and bis(benzylsulfonyl) activated carbon acids were synthesized and the products of the deprotonation of these carbon acids by strong, organic, cyclic bases such as: 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) in acetonitrile were characterized by conductance measurements. The values of p Ka in acetonitrile are in the range between 19.1 and 24.23 for disulfonyl carbon acids and 25.96 and 25.0 for TBD and MTBD appropriately. The conductometric titration of 0.001 M carbon acids solution in acetonitrile with 0.1 M TBD or 0.1 M MTBD in acetonitrile has been carried out. The dissociation constant values of the products of the reaction between studied carbon acids and TBD and MTBD bases in acetonitrile at 25 °C have been estimated. The results of the conductometric study for various disulfonyl carbon acids indicate convincingly that the products of the studied proton transfer reactions in acetonitrile occur as free ions or can exist also in the form of ion pairs in case of phenyl[bis(ethylsulfonyl)]methane.

  10. Adsorption of perfluoroalkyl acids by carbonaceous adsorbents: Effect of carbon surface chemistry.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2015-07-01

    Adsorption by carbonaceous sorbents is among the most feasible processes to remove perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) from drinking and ground waters. However, carbon surface chemistry, which has long been recognized essential for dictating performance of such sorbents, has never been considered for PFOS and PFOA adsorption. Thus, the role of surface chemistry was systematically investigated using sorbents with a wide range in precursor material, pore structure, and surface chemistry. Sorbent surface chemistry overwhelmed physical properties in controlling the extent of uptake. The adsorption affinity was positively correlated carbon surface basicity, suggesting that high acid neutralizing or anion exchange capacity was critical for substantial uptake of PFOS and PFOA. Carbon polarity or hydrophobicity had insignificant impact on the extent of adsorption. Synthetic polymer-based Ambersorb and activated carbon fibers were more effective than activated carbon made of natural materials in removing PFOS and PFOA from aqueous solutions. PMID:25827692

  11. Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Essin, A. M.; Golden, D. M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The global methanol budget is currently unbalanced, with source terms significantly larger than the sinks terms. To evaluate possible losses of gaseous methanol to sulfate aerosols, the solubility and reactivity of methanol in aqueous sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosols is under investigation. Methanol will partition into sulfate aerosols according to its Henry's law solubility. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H*, for cold (196 - 220 K) solutions ranging between 45 and 70 wt % H2SO4. We have found that methanol solubility ranges from approx. 10(exp 5) - 10(exp 7) M/atm for UT/LS conditions. Solubility increases with decreasing temperature and with increasing sulfuric acid content. Although methanol is slightly more soluble than are acetone and formaldehyde, current data indicate that uptake by clean aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These solubility measurements include uptake due to physical solvation and any rapid equilibria which are established in solution. Reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H is not significant over our experimental time scale for solutions below 80 wt % H2SO4. To confirm this directly, results obtained using a complementary equilibrium measurement technique will also be presented.

  12. Electrosorption of inorganic salts from aqueous solution using carbon aerogels.

    PubMed

    Gabelich, Christopher J; Tran, Tri D; Suffet, I H Mel

    2002-07-01

    Capacitive deionization (CDI) with carbon aerogels has been shown to remove various inorganic species from aqueous solutions, though no studies have shown the electrosorption behavior of multisolute systems in which ions compete for limited surface area. Several experiments were conducted to determine the ion removal capacity and selectivity of carbon aerogel electrodes, using both laboratory and natural waters. Although carbon aerogel electrodes have been treated as electrical double-layer capacitors, this study showed that ion sorption followed a Langmuir isotherm, indicating monolayer adsorption. The sorption capacity of carbon aerogel electrodes was approximately 1.0-2.0 x 10(-4) equiv/g aerogel, with ion selectivity being based on ionic hydrated radius. Monovalent ions (e.g., sodium) with smaller hydrated radii were preferentially removed from solution over multivalent ions (e.g., calcium) on a percent or molar basis. Because of the relatively small average pore size (4-9 nm) of the carbon aerogel material, only 14-42 m2/g aerogel surface area was available for ion sorption. Natural organic matter may foul the aerogel surface and limit CDI effectiveness in treating natural waters. PMID:12144279

  13. Simultaneous leaching and carbon sequestration in constrained aqueous solutions.

    PubMed

    Moon, Ji-Won; Cho, Kyu-Seong; Moberly, James G; Roh, Yul; Phelps, Tommy J

    2011-12-01

    The behavior of metal ions' leaching and precipitated mineral phases of metal-rich fly ash (FA) was examined in order to evaluate microbial impacts on carbon sequestration and metal immobilization. The leaching solutions consisted of aerobic deionized water (DW) and artificial eutrophic water (AEW) that was anaerobic, organic- and mineral-rich, and higher salinity as is typical of bottom water in eutrophic algae ponds. The Fe- and Ca-rich FAs were predominantly composed of quartz, mullite, portlandite, calcite, hannebachite, maghemite, and hematite. After 86 days, only Fe and Ca contents exhibited a decrease in leaching solutions while other major and trace elements showed increasing or steady trends in preference to the type of FA and leaching solution. Ca-rich FA showed strong carbon sequestration efficiency ranging up to 32.3 g CO(2)/kg FA after 86 days, corresponding to almost 65% of biotic carbon sequestration potential under some conditions. Variations in the properties of FAs such as chemical compositions, mineral constituents as well as the type of leaching solution impacted CO(2) capture. Even though the relative amount of calcite increased sixfold in the AEW and the relative amount of mineral phase reached 37.3 wt% using Ca-rich FA for 86 days, chemical sequestration did not accomplish simultaneous precipitation and sequestration of several heavy metals. PMID:21246259

  14. Simultaneous leaching and carbon sequestration in constrained aqueous solutions

    SciTech Connect

    Phelps, Tommy Joe; Moon, Ji Won; Roh, Yul; Cho, Kyu Seong

    2011-01-01

    The behavior of metal ions leaching and precipitated mineral phases of metal-rich fly ash (FA) was examined in order to evaluate microbial impacts on carbon sequestration and metal immobilization. The leaching solutions consisted of aerobic deionized water (DW) and artificial eutrophic water (AEW) that was anaerobic, organic- and mineral-rich, and higher salinity as is typical of bottom water in eutrophic algae ponds. The Fe- and Ca-rich FAs were predominantly composed of quartz, mullite, portlandite, calcite, hannebachite, maghemite, and hematite. After 86 days, only Fe and Ca contents exhibited a decrease in leaching solutions while other major and trace elements showed increasing or steady trends in preference to the type of FA and leaching solution. Ca-rich FA showed strong carbon sequestration efficiency ranging up to 32.3 g CO(2)/kg FA after 86 days, corresponding to almost 65% of biotic carbon sequestration potential under some conditions. Variations in the properties of FAs such as chemical compositions, mineral constituents as well as the type of leaching solution impacted CO(2) capture. Even though the relative amount of calcite increased sixfold in the AEW and the relative amount of mineral phase reached 37.3 wt% using Ca-rich FA for 86 days, chemical sequestration did not accomplish simultaneous precipitation and sequestration of several heavy metals.

  15. Reversible absorption of SO2 by amino acid aqueous solutions.

    PubMed

    Deng, Renpan; Jia, Lishan; Song, Qianqian; Su, Shuai; Tian, Zhongbiao

    2012-08-30

    Six water-soluble amino acids (glycine, l-?-alanine, dl-alanine, ?-alanine, proline and arginine) aqueous solutions were applied to remove SO(2) from SO(2)-N(2) system in this report. All the tested amino acids solutions were found to be excellent absorbents for SO(2) removal, and SO(2) saturation uptake of ?-alanine solution was the highest under the same experimental conditions. The effects of amino acid concentration, SO(2) concentration, absorption temperature, desorption temperature and initial pH value of the absorbent on the removal of SO(2) were investigated with ?-Ala solution. The experimental results showed that SO(2) saturation uptake increased with the increase in ?-alanine solution and SO(2) concentration. Room temperature (20-30C) was found to be optimal for SO(2) absorption. Additionally the SO(2) desorption capacity increased with increasing desorption temperature. The neutral environment pH value of 6.8 was found to be optimal for SO(2) removal. Ten continuous absorption-desorption cycles showed that the absorbent had an excellent regeneration performance. (13)C NMR and ultraviolet analyses offer ample evidence to speculate that the bonding between SO(2) and ?-alanine was not covalent but some weak interactive forces, such as dispersion force, induction force, dipole-dipole force and hydrogen bond. PMID:22763225

  16. Meldrum's acids and 5-alkylidene Meldrum's acids in catalytic carbon-carbon bond-forming processes.

    PubMed

    Dumas, Aaron M; Fillion, Eric

    2010-03-16

    Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione) is a molecule with a unique history, owing to its originally misassigned structure, as well as a unique place among acylating agents, owing to its high acidity and remarkable electrophilicity. In this Account, we outline the work of our group and others toward harnessing the reactivity of Meldrum's acid derivatives in catalytic C-C bond-forming reactions. Taking advantage of the ability of Meldrum's acid to decompose to CO(2) and acetone following acyl substitution, we have shown that intramolecular Friedel-Crafts acylations can be performed under mild Lewis acidic conditions to yield a variety of benzocyclic ketones. In a further expansion of this method, a domino Friedel-Crafts acylation/alpha-tert alkylation reaction was used to complete the first total synthesis of (+/-)-taiwaniaquinol B. The unique characteristics of Meldrum's acid extend to its alkylidene derivatives, which have also proven exceptionally useful for the development of new reactions not readily accessible from other unsaturated carbonyl electrophiles. By combining the electrophilicity and dienophilicity of alkylidene Meldrum's acid with our Friedel-Crafts chemistry, we have demonstrated new domino syntheses of coumarin derivatives and tetrahydrofluorenones by conjugate additions, Diels-Alder cycloadditions, and C-H functionalizations. Additionally, we have used these powerful acceptors to allow conjugate alkenylation with functionalized organostannanes, and conjugate allylation under very mild conditions. We have also shown that these molecules permit the asymmetric formation of all-carbon quaternary stereocenters via enantioselective conjugate additions. These reactions employ dialkylzinc nucleophiles, maximizing functional group compatibility, while the presence of a Meldrum's acid moiety in the product allows a variety of postaddition modifications. A full investigation of this reaction has determined the structural factors of the alkylidene that contribute to optimal enantioselectivity. We have also used these acceptors to form tertiary propargylic stereocenters in very high enantiomeric excess by an extremely mild, Rh(I)-catalyzed addition of TMS-acetylene. Overall, we demonstrate that Meldrum's acid and its derivatives provide access to a broad range of reactivities that, combined with their ease of handling and preparation, make them ideal electrophiles. PMID:20000793

  17. Radiolysis of aqueous solutions of acetic acid in the presence of Na-montmorillonite

    NASA Technical Reports Server (NTRS)

    Navarro-Gonzalez, R.; Negron-Mendoza, A.; Ramos, S.; Ponnamperuma, C.

    1990-01-01

    The gamma-irradiation of 0.8 mol dm-3 aqueous, oxygen-free acetic acid solutions was investigated in the presence or absence of Na-montmorillonite. H2, CH4, CO, CO2, and several polycarboxylic acids were formed in all systems. The primary characteristics observed in the latter system were: (1) Higher yield of the decomposition of acetic acid; (2) Lower yield of the formation of polycarboxylic acids; (3) No effect on the formation of methane; (4) Higher yield of the formation of carbon dioxide; and (5) The reduction of Fe3+ in the octahedral sites of Na-montmorillonite. A possible reaction scheme was proposed to account for the observed changes. The results are important in understanding heterogeneous processes in radiation catalysis and might be significant to prebiotic chemistry.

  18. Modeling Sucrose Hydrolysis in Dilute Sulfuric Acid Solutions at Pretreatment Conditions for Lignocellulosic Biomass

    SciTech Connect

    Bower, S.; Wickramasinghe, R.; Nagle, N. J.; Schell, D. J.

    2008-01-01

    Agricultural and herbaceous feedstocks may contain appreciable levels of sucrose. The goal of this study was to evaluate the survivability of sucrose and its hydrolysis products, fructose and glucose, during dilute sulfuric acid processing at conditions typically used to pretreat lignocellulose biomass. Solutions containing 25 g/l sucrose with 0.1-2.0% (w/w) sulfuric acid concentrations were treated at temperatures of 160-200 C for 3-12 min. Sucrose was observed to completely hydrolyze at all treatment conditions. However, appreciable concentrations of fructose and glucose were detected and glucose was found to be significantly more stable than fructose. Different mathematical approaches were used to fit the kinetic parameters for acid-catalyzed thermal degradation of these sugars. Since both sugars may survive dilute acid pretreatment, they could provide an additional carbon source for production of ethanol and other bio-based products.

  19. Sorption of cobalt on activated carbons from aqueous solutions

    SciTech Connect

    Paajanen, A.; Lehto, J.; Santapakka, T.; Morneau, J.P.

    1997-01-01

    The efficiencies of 15 commercially available activated carbons were tested for the separation of trace cobalt ({sup 60}Co) in buffer solutions at pH 5.0, 6.7, and 9.1. On the basis of the results four carbon products, Diahope-006, Eurocarb TN5, Hydraffin DG47, and Norit ROW Supra, were selected for further study. These carbons represented varying (low, medium and high) cobalt removal efficiencies and were prepared of three typical raw materials: peat, coconut shell, or coal. Study was made of the effects on sorption efficiencies of factors of interest in metal/radionuclide-bearing waste effluents. These factors were pH, sodium ions, borate, and citrate.

  20. Carbon-based strong solid acid for cornstarch hydrolysis

    NASA Astrophysics Data System (ADS)

    Nata, Iryanti Fatyasari; Irawan, Chairul; Mardina, Primata; Lee, Cheng-Kang

    2015-10-01

    Highly sulfonated carbonaceous spheres with diameter of 100-500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO3H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO3H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst.

  1. Insights into non-Fickian solute transport in carbonates

    PubMed Central

    Bijeljic, Branko; Mostaghimi, Peyman; Blunt, Martin J

    2013-01-01

    [1] We study and explain the origin of early breakthrough and long tailing plume behavior by simulating solute transport through 3-D X-ray images of six different carbonate rock samples, representing geological media with a high degree of pore-scale complexity. A Stokes solver is employed to compute the flow field, and the particles are then transported along streamlines to represent advection, while the random walk method is used to model diffusion. We compute the propagators (concentration versus displacement) for a range of Peclet numbers (Pe) and relate it to the velocity distribution obtained directly on the images. There is a very wide distribution of velocity that quantifies the impact of pore structure on transport. In samples with a relatively narrow spread of velocities, transport is characterized by a small immobile concentration peak, representing essentially stagnant portions of the pore space, and a dominant secondary peak of mobile solute moving at approximately the average flow speed. On the other hand, in carbonates with a wider velocity distribution, there is a significant immobile peak concentration and an elongated tail of moving fluid. An increase in Pe, decreasing the relative impact of diffusion, leads to the faster formation of secondary mobile peak(s). This behavior indicates highly anomalous transport. The implications for modeling field-scale transport are discussed. Citation: Bijeljic, B., P. Mostaghimi, and M. J. Blunt (2013), Insights into non-Fickian solute transport in carbonates, Water Resour. Res., 49, 27142728, doi:10.1002/wrcr.20238. PMID:24223444

  2. Carbon dioxide-sustained adsorption of lactic acid at pH > pK{sub a} of the acid

    SciTech Connect

    Husson, S.M.; King, C.J.

    1999-04-01

    Experimental data are presented for batch and fixed-bed adsorption of lactic acid from aqueous sodium lactate solutions onto the tertiary amine sorbents, Dowex MWA-1 and Amberlite IRA-35, in the presence of carbon dioxide. The effects of carbon dioxide pressure and sodium lactate concentration on lactate uptake capacity were measured. A simple complexation model, which includes chemical-equilibria and mass- and charge-balance equations, was developed to describe the system. There are no fitted parameters in the model. The model predictions compare well with batch adsorption data.

  3. Solution Preserves Nucleic Acids in Body-Fluid Specimens

    NASA Technical Reports Server (NTRS)

    Pierson, Duane L.; Stowe, Raymond P.

    2004-01-01

    A solution has been formulated to preserve deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in specimens of blood, saliva, and other bodily fluids. Specimens of this type are collected for diagnostic molecular pathology, which is becoming the method of choice for diagnosis of many diseases. The solution makes it possible to store such specimens at room temperature, without risk of decomposition, for subsequent analysis in a laboratory that could be remote from the sampling location. Thus, the solution could be a means to bring the benefits of diagnostic molecular pathology to geographic regions where refrigeration equipment and diagnostic laboratories are not available. The table lists the ingredients of the solution. The functions of the ingredients are the following: EDTA chelates divalent cations that are necessary cofactors for nuclease activity. In so doing, it functionally removes these cations and thereby retards the action of nucleases. EDTA also stabilizes the DNA helix. Tris serves as a buffering agent, which is needed because minor contaminants in an unbuffered solution can exert pronounced effects on pH and thereby cause spontaneous degradation of DNA. SDS is an ionic detergent that inhibits ribonuclease activity. SDS has been used in some lysis buffers and as a storage buffer for RNA after purification. The use of the solution is straightforward. For example, a sample of saliva is collected by placing a cotton roll around in the subject's mouth until it becomes saturated, then the cotton is placed in a collection tube. Next, 1.5 mL of the solution are injected directly into the cotton and the tube is capped for storage at room temperature. The effectiveness of the solution has been demonstrated in tests on specimens of saliva containing herpes simplex virus. In the tests, the viral DNA, as amplified by polymerase chain reaction, was detected even after storage for 120 days.

  4. The Strongest Acid: Protonation of Carbon Dioxide.

    PubMed

    Cummings, Steven; Hratchian, Hrant P; Reed, Christopher A

    2016-01-01

    The strongest carborane acid, H(CHB11 F11 ), protonates CO2 while traditional mixed Lewis/Brønsted superacids do not. The product is deduced from IR spectroscopy and calculation to be the proton disolvate, H(CO2 )2 (+) . The carborane acid H(CHB11 F11 ) is therefore the strongest known acid. The failure of traditional mixed superacids to protonate weak bases such as CO2 can be traced to a competition between the proton and the Lewis acid for the added base. The high protic acidity promised by large absolute values of the Hammett acidity function (H0 ) is not realized in practice because the basicity of an added base is suppressed by Lewis acid/base adduct formation. PMID:26663640

  5. Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2006-01-01

    We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approx.40 to approx.80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients ((gamma)) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approx.70 wt % and in dilute solutions colder than 220 K, the values approached approx.0.07. We also determined the effective solubility constant of ethanol in approx.40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.

  6. DC diaphragm discharge in water solutions of selected organic acids

    NASA Astrophysics Data System (ADS)

    Vyhnankova, Edita J.; Hammer, Malte U.; Reuter, Stephan; Krcma, Frantisek

    2015-07-01

    Effect of four simple organic acids water solution on a DC diaphragm discharge was studied. Efficiency of the discharge was quantified by the hydrogen peroxide production determined by UV-VIS spectrometry of a H2O2 complex formed with specific titanium reagent. Automatic titration was used to study the pH behaviour after the plasma treatment. Optical emission spectroscopy overview spectra were recorded and detailed spectra of OH band and Hβ line were used to calculate the rotational temperature and comparison of the line profile (reflecting electron concentration) in the acid solutions. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  7. Quantitative extraction and concentration of synthetic water-soluble acid dyes from aqueous media using a quinine-chloroform solution

    SciTech Connect

    Kobayashi, F.; Ozawa, N.; Hanai, J.; Isobe, M.; Watabe, T.

    1986-12-01

    Twenty-one water-soluble acid dyes, including eleven azo, five triphenylmethane four xanthene, one naphthol derivatives, used at practical concentrations for food coloration, were quantitatively extracted from water and various carbonated beverages into a 0.1 M quinine-chloroform solution in the presence of 0.5 M boric acid by brief shaking. Quantitative extraction of these dyes was also accomplished by the 0.1 M quinine-chloroform solution made conveniently from chloroform, quinine hydrochloride, and sodium hydroxide added successively to water or beverages containing boric acid. Quinine acted as a countercation on the dyes having sulfonic and/or carboxylic acid group(s) to form chloroform-soluble ion-pair complexes. The diacidic base alkaloid interacted with each acid group of mono-, di-, tri-, and tetrasulfonic acid dyes approximately in the ratio 0.8-0.9 to 1. The dyes in the chloroform solution were quantitatively concentrated into a small volume of sodium hydroxide solution also by brief shaking. The convenient quinine-chloroform method was applicable to the quantitative extraction of a mixture of 12 dyes from carbonated beverages, which are all currently used for food coloration. A high-pressure liquid chromatographic method is also presented for the systematic separation and determination of these 12 dyes following their concentration into the aqueous alkaline solution. The chromatogram was monitored by double-wavelength absorptiometry in the visible and ultraviolet ray regions.

  8. Efficient optical resolution of amino acid by alanine racemaze chiral analogue supported on mesoporous carbon

    NASA Astrophysics Data System (ADS)

    Jang, D.; Kim, K.; Park, D.; Kim, G.

    2012-09-01

    Optically pure D-amino acids are industrially important chiral building blocks for the synthesis of pharmaceuticals, food ingredients, and drug intermediates. Chemoenzymatic dynamic kinetic-resolution processes have recently been developed for deracemization of amino acids. S-ARCA would be a good candidate for the selective adsorption of D amino acid through the imine formation reaction. The organic phase containing S-ARCA adsorbent, TPPC or Ionic Liquid (as a phase transfer catalyst) in MC were coated on the surfaces of mesoporous carbon C-SBA-15(CMK). The aqueous solution of racemic D/L-amino acid and NaOH were added to the carbon support coated with ARCA. The D/L ratios on ARCA and in solution were determined with increasing reaction time. S-ARCA has a unique property for the selective adsorption of D- amino acid (up to 90% selcetivity) in the racemic mixture. The fixed bed reactor containing ARCA/carbon support was also adopted successfully for the selective separation of amino acid.

  9. Separation of glycols from dilute aqueous solutions via complexation with boronic acids

    SciTech Connect

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

    1991-07-01

    This work examines methods of separating low molecular weight glycols from dilute aqueous solution. Extraction into conventional solvents is generally not economical, since, in the literature reviewed, distribution ratios for the two- to four-carbon glycols are all less than one. Distribution ratios can be increased, however, by incorporating into the organic phase an extracting agent that will complex with the solute of interest. The extracting agent investigated in this work is 3-nitrophenylboronic acid (NPBA). NPBA, a boric acid derivative, reversibly complexes with many glycols. The literature on complexation of borate and related compounds with glycols, including mechanistic data, measurement techniques, and applications to separation processes, provides information valuable for designing experiments with NPBA and is reviewed herein. 88 refs., 15 figs., 24 tabs.

  10. Recovery of rhenium from sulfuric acid solutions with activated coals

    SciTech Connect

    Troshkina, I.D.; Naing, K.Z.; Ushanova, O.N.; P'o, V.; Abdusalomov, A.A.

    2006-09-15

    Equilibrium and kinetic characteristics of rhenium sorption from sulfuric acid solutions (pH 2) by activated coals produced from coal raw materials (China) were studied. Constants of the Henry equation describing isotherms of rhenium sorption by activated coals were calculated. The effective diffusion coefficients of rhenium in the coals were determined. The dynamic characteristics of rhenium sorption and desorption were determined for the activated coal with the best capacity and kinetic characteristics.

  11. Distribution of trace elements between carbonate minerals and aqueous solutions

    NASA Astrophysics Data System (ADS)

    Rimstidt, J. Donald; Balog, Anna; Webb, John

    1998-06-01

    The experimental distribution coefficients, K 'd, for trace elements in carbonate minerals show a systematic pattern of behavior that differs from that expected if the distribution were controlled by equilibrium thermodynamics. Regression of experimental distribution coefficients, K 'd, from the literature shows that they correlate well with the quotient of the solubility products of the trace element and host carbonate. However, the slope of the correlation line differs from that predicted by equilibrium theory in a way that suggests that the experiments are affected by a kinetic process, whereby the trace element is incorporated into the growing carbonate crystal at a rate that is either faster or slower than the incorporation of Ca. The correlations predict that the K 'd for elements that form rhombdohedral carbonates (e.g., Cd, Zn, Cu, Mn, etc.) is expressed by K 'd=1.6 K MCO3/K TrCO30.57 for calcite and K 'd=4.1 K MCO3/K TrCO30.57 for siderite. These correlations can be used to estimate the K 'd values for cases where no experimental data are available, including for other phases and other temperatures. Thus, the experimental K 'd values can be used to understand general trends in trace element behavior. Analysis of K 'd for calcite shows that this mineral can effectively sequester a variety of toxic cations (e.g., Pb, Cd, Cu, etc.) from solution, so precipitation of calcite from contaminated solutions may provide an effective method of environmental remediation. On the other hand, values of K 'd should be used with caution when interpreting ancient geochemical environments for carbonates, because K 'd values are strongly rate-dependent and the rates of mineral precipitation are seldom known.

  12. The Path of Carbon in Photosynthesis II. Amino Acids

    DOE R&D Accomplishments Database

    Stepka, W.; Benson, A. A.; Calvin, M.

    1948-05-25

    The radioactive amino acid's synthesized from C{sup 14}O{sub 2} by green algae both in the light and in the dark after CO{sub 2}-free preillumination have been separated and identified using paper chromatography and radioautography. The radioactive amino acids identified were aspartic acid, alanine and smaller amounts of 3- and 4-carbon amino acids. This finding as well as the total absence of radioactive glutamic acid substantiates the mechanism for reduction of CO{sub 2} previously postulated by members of this laboratory.

  13. Capacitance of a passive iron electrode in acidic solutions

    SciTech Connect

    Grilikhes, M.S.; Berezin, M.Yu.; Gorlin, A.V.; Sapelova, E.V.; Sokolov, M.A.; Sukhotin, A.M.

    1985-12-01

    In the present work the authors measured the capacitance of the electrical double layer on passive Armco iron in acidic solutions with the simultaneous recording of the potentiodynamic curves. The measurements were carried out on an apparatus which is based on the double-pulse variant of the galvanostatic method with a pulse lifetime of 2 microseconds, in which the influence of the faradic processes on the capacitance curves is negligibly small in the case of electrochemical systems with small exchange currents. The experiments were carried out at room temperature in 0.5 M sulfuric acid (pH 0.25) and 0.5 M tartaric acid H/sub 2/C/sub 4/H/sub 4/O/sub 6/ (pH 1.6).

  14. Methanol Uptake By Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    To evaluate the role of upper tropospheric and lower stratospheric aerosols in the global budget of methanol, the solubility and reactivity of CH3OH in aqueous sulfuric acid solutions are under investigation. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H(*), for methanol dissolution into 45 to 70 percent by weight H2SO4. We find that methanol solubility ranges from 10(exp 5) to 10(exp 8) M/atm and increases with decreasing temperature and with increasing sulfuric acid content. These solubility measurements include uptake due to physical solvation and all rapid equilibria which are established in solution. Our data indicate that simple uptake by aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These results differ from those recently reported in the literature, and an explanation of this disparity will be presented. In addition to solvation, reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H may proceed in the atmosphere but is not significant under our experimental conditions. Results obtained using a complementary equilibrium measurement technique confirm this directly. In addition, the extent of methanol sequestration via formation of mono- and dimethylsulfate will be evaluated under several atmospheric conditions.

  15. Development of poly(aspartic acid-co-malic acid) composites for calcium carbonate and sulphate scale inhibition.

    PubMed

    Mithil Kumar, N; Gupta, Sanjay Kumar; Jagadeesh, Dani; Kanny, K; Bux, F

    2015-01-01

    Polyaspartic acid (PSI) is suitable for the inhibition of inorganic scale deposition. To enhance its scale inhibition efficiency, PSI was modified by reacting aspartic acid with malic acid (MA) using thermal polycondensation polymerization. This reaction resulted in poly(aspartic acid-co-malic acid) (PSI-co-MA) dual polymer. The structural, chemical and thermal properties of the dual polymers were analysed by using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and gel permeation chromatography. The effectiveness of six different molar ratios of PSI-co-MA dual polymer for calcium carbonate and calcium sulphate scale inhibition at laboratory scale batch experiments was evaluated with synthetic brine solution at selected doses of polymer at 65-70C by the static scale test method. The performance of PSI-co-MA dual polymer for the inhibition of calcium carbonate and calcium sulphate precipitation was compared with that of a PSI single polymer. The PSI-co-MA exhibited excellent ability to control inorganic minerals, with approximately 85.36% calcium carbonate inhibition and 100% calcium sulphate inhibition at a level of 10?mg/L PSI-co-MA, respectively. Therefore, it may be reasonably concluded that PSI-co-MA is a highly effective scale inhibitor for cooling water treatment applications. PMID:25371160

  16. Characterization of carbon black modified by maleic acid

    NASA Astrophysics Data System (ADS)

    Asokan, Vijayshankar; Kosinski, Pawel; Skodvin, Tore; Myrseth, Velaug

    2013-09-01

    We present here a method for modifying the surface of carbon black (CB) using a simple heat treatment in the presence of a carboxylic acid as well as water or ethylene glycol as a solvent. CB was mixed with maleic acid and either water or ethylene glycol, and heated at 250C. Unlike the traditional surface modification processes which use heat treatment of carbon with mineral acids the present modification method using a carboxylic acid proved to be simple and time efficient. CB from two different vendors was used, and the modified samples were characterized by TGA, BET surface area measurement, XRD, particle size and zeta potential measurements, and FTIR. It was found that several material properties, including thermal stability and surface area, of the modified CB are significantly altered relative to the parental carbon samples. This method provides a rapid and simple route to tailor new materials with desired properties.

  17. The effect of electrolyzed strong acid aqueous solution on hemodialysis equipment.

    PubMed

    Tanaka, N; Fujisawa, T; Daimon, T; Fujiwara, K; Yamamoto, M; Abe, T

    1999-12-01

    We reported the high effectiveness of electrolyzed strong acid aqueous solution (ESAAS) in cleaning hemodialysis lines. Although ESAAS has a strong bactericidal action, one concern is its strong acidity. It has a pH of 2.3-2.7, more than 1,000 mV in oxidation-reduction potential (ORP), and 10-50 ppm of available chlorine. The possibility of metal corrosion, degradation of synthetic resins, chorine gas emission, or dissolving calcium carbonate (CaCO3) deposits due to ESAAS's acidity was tested using in vitro experiments. The bactericidal and antiviral effects of various ESAAS's were also tested. Metal corrosion and synthetic resin degradation, although they occurred, were not serious. There were no problems with chlorine gas emission and dissolving of CaCO3 deposits. Each type of ESAAS showed almost the same bactericidal and antiviral effect, but in some cases differences were observed. PMID:10619923

  18. Influence of dissolved organic carbon content on modelling natural organic matter acid-base properties.

    PubMed

    Garnier, Cdric; Mounier, Stphane; Benam, Jean Yves

    2004-10-01

    Natural organic matter (NOM) behaviour towards proton is an important parameter to understand NOM fate in the environment. Moreover, it is necessary to determine NOM acid-base properties before investigating trace metals complexation by natural organic matter. This work focuses on the possibility to determine these acid-base properties by accurate and simple titrations, even at low organic matter concentrations. So, the experiments were conducted on concentrated and diluted solutions of extracted humic and fulvic acid from Laurentian River, on concentrated and diluted model solutions of well-known simple molecules (acetic and phenolic acids), and on natural samples from the Seine river (France) which are not pre-concentrated. Titration experiments were modelled by a 6 acidic-sites discrete model, except for the model solutions. The modelling software used, called PROSECE (Programme d'Optimisation et de SpEciation Chimique dans l'Environnement), has been developed in our laboratory, is based on the mass balance equilibrium resolution. The results obtained on extracted organic matter and model solutions point out a threshold value for a confident determination of the studied organic matter acid-base properties. They also show an aberrant decreasing carboxylic/phenolic ratio with increasing sample dilution. This shift is neither due to any conformational effect, since it is also observed on model solutions, nor to ionic strength variations which is controlled during all experiments. On the other hand, it could be the result of an electrode troubleshooting occurring at basic pH values, which effect is amplified at low total concentration of acidic sites. So, in our conditions, the limit for a correct modelling of NOM acid-base properties is defined as 0.04 meq of total analysed acidic sites concentration. As for the analysed natural samples, due to their high acidic sites content, it is possible to model their behaviour despite the low organic carbon concentration. PMID:15350419

  19. Solution-processed soldering of carbon nanotubes for flexible electronics

    NASA Astrophysics Data System (ADS)

    Rao, K. D. M.; Radha, B.; Smith, K. C.; Fisher, T. S.; Kulkarni, G. U.

    2013-02-01

    We report a simple lithography-free, solution-based method of soldering of carbon nanotubes with Ohmic contacts, by taking specific examples of multi-walled carbon nanotubes (MWNTs). This is achieved by self-assembling a monolayer of soldering precursor, Pd2+ anchored to 1,10 decanedithiol, onto which MWNTs could be aligned across the gap electrodes via solvent evaporation. The nanosoldering was realized by thermal/electrical activation or by both in sequence. Electrical activation and the following step of washing ensure selective retention of MWNTs spanning across the gap electrodes. The soldered joints were robust enough to sustain strain caused during the bending of flexible substrates as well as during ultrasonication. The estimated temperature generated at the MWNT-Au interface using an electro-thermal model is 150?C, suggesting Joule heating as the primary mechanism of electrical activation. Further, the specific contact resistance is estimated from the transmission line model.

  20. carbonate solid solution at high pressures up to 55 GPa

    NASA Astrophysics Data System (ADS)

    Spivak, Anna; Solopova, Natalia; Cerantola, Valerio; Bykova, Elena; Zakharchenko, Egor; Dubrovinsky, Leonid; Litvin, Yuriy

    2014-09-01

    Magnesite, siderite and ferromagnesites Mg1- x Fe x CO3 ( x = 0.05, 0.09, 0.2, 0.4) were characterized using in situ Raman spectroscopy at high pressures up to 55 GPa. For the Mg-Fe-carbonates, the Raman peak positions of six modes (T, L, ?4, ?1, ?3 and 2?2) in the dependence of iron content in the carbonates at ambient conditions are presented. High-pressure Raman spectroscopy shows that siderite undergoes a spin transition at ~40 GPa. The examination of the solid solutions with compositions Mg0.6Fe0.4CO3, Mg0.8Fe0.2CO3, Mg0.91Fe0.09CO3 and Mg0.95Fe0.05CO3 indicates that with increase in the amount of the Fe spin transition pressure increases up to ~45 GPa.

  1. Rhodium-catalyzed hydrogenation of carbon dioxide to formic acid

    SciTech Connect

    Tsai, Jing-Cherng; Nicholas, K.M.

    1992-06-17

    The complex [Rh(NBD)(PMe{sub 2}Ph){sub 3}]BF{sub 4} (2; NBD = norbornadiene) has been found to serve as a precatalyst for the hydrogenation of carbon dioxide to formic acid at moderate temperatures in THF solution, with turnover numbers of 10-60/day. Water accelerates formic acid production, whereas PMe{sub 2}Ph is an inhibitor. Kinetic studies show that the rate of formic acid appearance in first order each in [2], pH{sub 2}, and p{sub CO2} in the range 50-300 psi (following prehydrogenation). In situ high-pressure IR and NMR experiments reveal that the addition of H{sub 2} to [Rh(NBD)(PMe{sub 2}Ph){sub 3}]BF{sub 4} (2) produces rhodium dihydride complexes [H{sub 2}Rh(PMe{sub 2}Ph){sub 3}(S)]BF{sub 4}(4, 5; S = H{sub 2}O, THF) and [H{sub 2}Rh(PMe{sub 2}Ph){sub 4}]BF{sub 4} (3). IR and NMR studies of the reaction of 3-5 with CO{sub 2} indicate that 3 is unreactive toward CO{sub 2} but that 4 and 5 insert CO{sub 2} to give species 6 and 7, formulated as formato complexes [HRh(S)(PMe{sub 2}Ph){sub 2}({eta}{sup 2}-OCHO)]BF{sub 4}, respectively; complexes 6 and 7 are also detected under catalytic conditions by IR spectroscopy. Aquo dihydride complex 4 has been found to insert CO{sub 2} more rapidly than the THF complex 5. [H{sub 2}Rh(PMe{sub 2}Ph){sub 3}(S)]BF{sub 4} (4, 5) also catalyze the decomposition of formic acid to CO{sub 2} and H{sub 2}. Combined kinetic and spectroscopic results suggest that reductive elimination of formic acid from the intermediate formato complexes is the rate-limiting step in the catalytic cycle. 30 refs., 11 figs., 1 tab.

  2. Effects of solution chemistry on the adsorption of ibuprofen and triclosan onto carbon nanotubes.

    PubMed

    Cho, Hyun-Hee; Huang, Haiou; Schwab, Kellogg

    2011-11-01

    Single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), and oxidized MWCNTs (O-MWCNTs) were studied for the adsorption of ibuprofen (IBU) and triclosan (TCS) as representative types of pharmaceutical and personal care products (PPCPs) under different chemical solution conditions. A good fitting of sorption isotherms was obtained using a Polanyi-Manes model (PMM). IBU and TCS sorption was stronger for SWCNTs than for MWCNTs due to higher specific surface area. The high oxygen content of O-MWCNT further depressed PPCP sorption. The sorption capacity of PPCPs was found to be pH-dependent, and more adsorption was observed at pHs below their pK(a) values. Ionic strength was also found to substantially affect TCS adsorption, with higher adsorption capacity observed for TCS at lower ionic strength. In the presence of a reference aquatic fulvic acid (FA), sorption of IBU and TCS was reduced due to the competitive sorption of FA on carbon nanotubes (CNTs). Sorption isotherm results with SWCNTs, MWCNTs and O-MWCNTs confirmed that the surface chemistry of CNTs, the chemical properties of PPCPs, and aqueous solution chemistry (pH, ionic strength, fulvic acid) all play an important role in PPCP adsorption onto CNTs. PMID:21913654

  3. Regiocontrolled intramolecular cyclizations of carboxylic acids to carbon-carbon triple bonds promoted by acid or base catalyst.

    PubMed

    Uchiyama, Masanobu; Ozawa, Hiroki; Takuma, Kazuya; Matsumoto, Yotaro; Yonehara, Mitsuhiro; Hiroya, Kou; Sakamoto, Takao

    2006-11-23

    We systematically investigated, for the first time, the relationship between regioselectivity and acid/base effects in the cyclization reactions between carboxylic acids and carbon-carbon triple bonds. We found novel acid- and base-promoted cyclizations to selectively give isocoumarin or pyran-2(2H)-one and phthalide or furan-2(5H)-one skeletons, respectively, and established a catalytic version of regioselective heterocyclic ring synthesis. Density functional theory calculations and application to a short route to thunberginol A were also described. [reaction: see text]. PMID:17107061

  4. Functionalization of Single Wall Carbon Nanotubes with Carboxylic Acids

    NASA Astrophysics Data System (ADS)

    Viswanathan, Sriram; Britt, Phillip F.; Ivanov, Ilia N.; Puretzky, Alex A.; Lance, Michael J.; Geohegan, David B.; Oak Ridge National Laboratory Collaboration

    2003-03-01

    The chemical functionalization of single-wall carbon nanotubes (SWNT) is necessary to solubilize the materials and to assist in the dispersion of the bundles for a variety of applications. One approach has been to derivatize the pendant carboxyl groups that are formed in the oxidative purification of the SWNT. Unfortunately, these carboxyl groups are found in low concentrations because the purification conditions also leads to decarboxylation. Thus, methods were investigated to increase the concentration of carboxylic acids on SWNT by chemical oxidation with a variety of reagents including potassium permanganate, sulfuric acid/nitric acid, and sulfuric acid/hydrogen peroxide. The concentration of carboxylic acids was analyzed by FTIR, and the samples were characterized by TGA, Raman spectroscopy, SEM, and TEM. Surprisingly, many of the oxidative methods lead to the formation of amorphous carbon and little if any increase in carboxyl content of the SWNT.

  5. Conversion of carbon dioxide to resorcylic acid under ultrasonication by Kolbe-Schmitt reaction.

    PubMed

    Shanthi, B; Palanivelu, K

    2015-11-01

    The present work focuses on a new approach for the synthesis of ?-resorcylic acid based on Kolbe-Schmitt reaction using carbon dioxide under ultrasonic and mild condition. The Kolbe-Schmitt reaction is a process for the synthesis of ?-resorcylic acid (2,4-dihydroxybenzoic acid) from resorcinol in aqueous potassium hydroxide solution with gaseous CO2. The influences of carbonation time, flow rate of CO2 and the molar ratio of resorcinol/potassium hydroxide on the yield percentage of resorcylic acid were investigated. The study was assessed with the conventional thermal method (non ultrasonic method) for Kolbe-Schmitt reaction and it was observed that applying ultrasound to save more than 95% and 38.6% energy as shown by energy consumption calculations in bath type and horn type sonicator respectively. ?-Resorcylic acid formed was characterized by (1)H NMR, (13)C NMR, DEPT NMR and FTIR spectroscopy. The amount of CO2 utilized in the reaction was evaluated from the yield percentage of ?-resorcylic acid yield. The maximum yield of resorcylic acid of 30% and 65% was obtained at the resorcinol/potassium hydroxide ratio of 1:3, carbonation time of 150 min and the CO2 flow rate of 2L/min in bath type and horn type ultrasonicator, respectively. The applicability of the research work was examined in two different positional isomers of resorcinol under optimum conditions. PMID:26186845

  6. Fragrance material review on carbonic acid, methyl phenylmethyl ester.

    PubMed

    McGinty, D; Letizia, C S; Api, A M

    2012-09-01

    A toxicologic and dermatologic review of carbonic acid, methyl phenylmethyl ester when used as a fragrance ingredient is presented. Carbonic acid, methyl phenylmethyl ester is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for carbonic acid, methyl phenylmethyl ester were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414647

  7. Organic amendments increase soil solution phosphate concentrations in an acid soil: A controlled environment study

    SciTech Connect

    Schefe, C.R.; Patti, A.F.; Clune, T.S.; Jackson, R.

    2008-04-15

    Soil acidification affects at least 4 million hectares of agricultural land in Victoria, Australia. Low soil pH can inhibit plant growth through increased soluble aluminum (Al) concentrations and decreased available phosphorus (P). The addition of organic amendments may increase P availability through competition for P binding sites, solubilization of poorly soluble P pools, and increased solution pH. The effect of two organic amendments (lignite and compost) on P solubility in an acid soil was determined through controlled environment (incubation) studies. Three days after the addition of lignite and compost, both treatments increased orthophosphate and total P measured in soil solution, with the compost treatments having the greatest positive effect. Increased incubation time (26 days) increased soil solution P concentrations in both untreated and amended soils, with the greatest effect seen in total P concentrations. The measured differences in solution P concentrations between the lignite- and compost-amended treatments were likely caused by differences in solution chemistry, predominantly solution pH and cation dynamics. Soil amendment with lignite or compost also increased microbial activity in the incubation systems, as measured by carbon dioxide respiration. Based on the results presented, it is proposed that the measured increase in soil solution P with amendment addition was likely caused by both chemical and biological processes, including biotic and abiotic P solubilization reactions, and the formation of soluble organic-metal complexes.

  8. Cryogenic-temperature electron microscopy direct imaging of carbon nanotubes and graphene solutions in superacids.

    PubMed

    Kleinerman, O; Parra-Vasquez, A Nicholas G; Green, M J; Behabtu, N; Schmidt, J; Kesselman, E; Young, C C; Cohen, Y; Pasquali, M; Talmon, Y

    2015-07-01

    Cryogenic electron microscopy (cryo-EM) is a powerful tool for imaging liquid and semiliquid systems. While cryogenic transmission electron microscopy (cryo-TEM) is a standard technique in many fields, cryogenic scanning electron microscopy (cryo-SEM) is still not that widely used and is far less developed. The vast majority of systems under investigation by cryo-EM involve either water or organic components. In this paper, we introduce the use of novel cryo-TEM and cryo-SEM specimen preparation and imaging methodologies, suitable for highly acidic and very reactive systems. Both preserve the native nanostructure in the system, while not harming the expensive equipment or the user. We present examples of direct imaging of single-walled, multiwalled carbon nanotubes and graphene, dissolved in chlorosulfonic acid and oleum. Moreover, we demonstrate the ability of these new cryo-TEM and cryo-SEM methodologies to follow phase transitions in carbon nanotube (CNT)/superacid systems, starting from dilute solutions up to the concentrated nematic liquid-crystalline CNT phases, used as the 'dope' for all-carbon-fibre spinning. Originally developed for direct imaging of CNTs and graphene dissolution and self-assembly in superacids, these methodologies can be implemented for a variety of highly acidic systems, paving a way for a new field of nonaqueous cryogenic electron microscopy. PMID:25818279

  9. Concentration-Purification of Uranium from an Acid Leaching Solution

    NASA Astrophysics Data System (ADS)

    Guettaf, H.; Becis, A.; Ferhat, K.; Hanou, K.; Bouchiha, D.; Yakoubi, K.; Ferrad, F.

    2009-11-01

    Chemical processes for the elaboration of uranium concentrate from uranium ore have been studied. This process is composed of successive units operations: crushing, milling, acid conventional leaching, filtration-washing, purification-concentration by ion exchange resins and uranium precipitation. The acid leaching operating conditions allow us to obtain a recovery uranium rate of 93%. The uranium concentration of the pregnant solution is approximately of 1.2 g/l. This value justifies the use of ion exchange resins to the concentration-purification of our pregnant solution. We have noticed that the pregnant solution contains a relatively high phosphate concentration which causes a premature uranium precipitation at pH=1.8. This pH value is in general, considered optimal to obtain the highest amount of fixed uranium by the anionic resin. To avoid the precipitation of uranium, the pH=1.5 has been fixed. We have obtained at this condition a good adsorption capacity. A 75% uranium concentrate have been elaborated, but the filtration of this concentrate has been very difficult. We have also noticed an excessive sulphate concentration. In order to improve this process, we have tested nitrates as eluant at different operating conditions.

  10. Removal of organic contaminants from aqueous solution by cattle manure compost (CMC) derived activated carbons

    NASA Astrophysics Data System (ADS)

    Qian, Qingrong; Chen, Qinghua; Machida, Motoi; Tatsumoto, Hideki; Mochidzuki, Kazuhiro; Sakoda, Akiyoshi

    2009-04-01

    The activated carbons (ACs) prepared from cattle manure compost (CMC) with various pore structure and surface chemistry were used to remove phenol and methylene blue (MB) from aqueous solutions. The adsorption equilibrium and kinetics of two organic contaminants onto the ACs were investigated and the schematic models for the adsorptive processes were proposed. The result shows that the removal of functional groups from ACs surface leads to decreasing both rate constants for phenol and MB adsorption. It also causes the decrement of MB adsorption capacity. However, the decrease of surface functional groups was found to result in the increase of phenol adsorption capacity. In our schematic model for adsorptive processes, the presence of acidic functional groups on the surface of carbon is assumed to act as channels for diffusion of adsorbate molecules onto small pores, therefore, promotes the adsorption rate of both phenol and MB. In phenol solution, water molecules firstly adsorb on surface oxygen groups by H-bonding and subsequently form water clusters, which cause partial blockage of the micropores, deduce electrons from the ?-electron system of the carbon basal planes, hence, impede or prevent phenol adsorption. On the contrary, in MB solution, the oxygen groups prefer to combine with MB + cations than water molecules, which lead to the increase of MB adsorption capacity.

  11. [Spectra studies on interaction of bovine serum albumin with acidic chrome blue K in acidic solution].

    PubMed

    Yu, Ying; Liao, Jian; Huang, Fa-de

    2002-12-01

    This paper investigated the interaction of acidic chrome blue K with bovine serum albumin (BSA). When BSA was added into acidic chrome blue K solution at pH 2.87 HCl-NaAc buffter, bathochromic effect and hypochromicity were observed. With the increase in BSA concentration, the absorption peak at 523 nm decreased. It was considered that the combination of BSA with acidic chrome blue K is due to static electricity forces. The interaction is in accord with model of phase distribution. It was discussed the effect of acidity, concentration of acidic chrome blue K, ion strength to apparent binding constant Kc, binding number n, Sandell constant. The reaction time, surfactant, work curve were studied. PMID:12914202

  12. Energetic changes in the surface of activated carbons and relationship with Ni(II) adsorption from aqueous solution

    NASA Astrophysics Data System (ADS)

    Rodrguez-Estupian, Paola; Giraldo, Liliana; Moreno-Pirajn, Juan Carlos

    2013-12-01

    This study investigated Ni(II) ion adsorption from aqueous solution on activated carbons obtained by chemically modifying the surface with the oxidizing agents nitric acid and hydrogen peroxide (CAGoxP and CAGoxN, respectively). The activated carbons were characterized by total acidity and basicity, pH at the point of charge zero determination and IR spectroscopy. Textural parameters such as the BET area and pore volumes were evaluated by gas adsorption. The BET area of the materials was between 816 and 876 m2 g-1. Additionally, the immersion enthalpies of the activated carbons in water and benzene were determined. The experimental results on adsorption in solution were adjusted to the Langmuir and Freundlich models, obtaining values for the monolayer capacity between 29.68 and 50.97 mg g-1, which indicates that the adsorption capacity depends largely on solid surface chemistry.

  13. Photocatalytic degradation of L-acid by TiO2 supported on the activated carbon.

    PubMed

    Wang, Yu-Ping; Wang, Lian-Jun; Peng, Pan-Ying

    2006-01-01

    TiO2 sol was prepared by sol-gel technique with tetrabutyl titanate as precursor. Supported TiO2 catalysts on activated carbon were prepared by soak and sintering method. The aggregation of nano-TiO2 particles can be effectively suppressed by added polyethylene glycol (PEG) as a surface modifier. The average particle diameter of TiO2, specific surface area and absorbability of catalyst can be modified. Based on characteristics of the TiO2 photocatalyst with XRD, specific surface area, adsorption valves of methylene blue and the amount of TiO2 supported on the activated carbon, the photocatalytic degradation of L-acid was studied. The effect of the factors, such as pH of the solution, the initial concentration of L-acid on the photocatalytic degradation of L-acid, were studied also. It was found that when the pH of the solution is 1.95, the amount of photocatalyst is 0.5 g, the concentration of the L-acid solution is 1.34 x 10(-3) mol/L and the illumination time is 7 h, the photocatalytic degradation efficiency of L-acid can reach 89.88%. The catalyst was reused 6 times and its degradation efficiency hardly changed. PMID:17294657

  14. Aquatic photolysis: photolytic redox reactions between goethite and adsorbed organic acids in aqueous solutions

    USGS Publications Warehouse

    Goldberg, M.C.; Cunningham, K.M.; Weiner, Eugene R.

    1993-01-01

    Photolysis of mono and di-carboxylic acids that are adsorbed onto the surface of the iron oxyhydroxide (goethite) results in an oxidation of the organic material and a reduction from Fe(III) to Fe(II) in the iron complex. There is a subsequent release of Fe2+ ions into solution. At constant light flux and constant solution light absorption, the factors responsible for the degree of photolytic reaction include: the number of lattice sites that are bonded by the organic acid; the rate of acid readsorption to the surface during photolysis; the conformation and structure of the organic acid; the degree of oxidation of the organic acid; the presence or absence of an ??-hydroxy group on the acid, the number of carbons in the di-acid chain and the conformation of the di-acid. The ability to liberate Fe(III) at pH 6.5 from the geothite lattice is described by the lyotropic series: tartrate>citrate> oxalate > glycolate > maleate > succinate > formate > fumarate > malonate > glutarate > benzoate = butanoate = control. Although a larger amount of iron is liberated, the series is almost the same at pH 5.5 except that oxalate > citrate and succinate > maleate. A set of rate equations are given that describe the release of iron from the goethite lattice. It was observed that the pH of the solution increases during photolysis if the solutions are not buffered. There is evidence to suggest the primary mechanism for all these reactions is an electron transfer from the organic ligand to the Fe(III) in the complex. Of all the iron-oxyhydroxide materials, crystalline goethite is the least soluble in water; yet, this study indicates that in an aqueous suspension, iron can be liberated from the goethite lattice. Further, it has been shown that photolysis can occur in a multiphase system at the sediment- water interface which results in an oxidation of the organic species and release of Fe2+ to solution where it becomes available for further reaction. ?? 1993.

  15. Oxidation of ferrous ions by ozone in acidic solutions

    SciTech Connect

    Loegager, T.; Holcman, J.; Sehested, K.; Pedersen, T. )

    1992-08-19

    In the aqueous phase of the atmosphere (aerosols, clouds, fog, etc.), where iron, acids, and ozone are simultaneously present, the oxidation of Fe{sup 2+} by O{sub 3} is very important as an ozone sink. The oxidation of ferrous ions by ozone in acidic solution of pH 0-2 was studied using a stopped-flow spectrophotometer. The reaction can be characterized as an oxygen atom transfer from O{sub 3} to Fe{sup 2+}. An intermediate product assigned to be the ferryl ion, FeO{sup 2+}, was found and its UV-vis spectrum measured. A reaction mechanism is proposed, which accounts for all the authors experimental results.

  16. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R.

    2012-02-22

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. For 6 M HNO{sub 3}, 10.5 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2 g/L and 0.25 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}.

  17. Systems solutions by lactic acid bacteria: from paradigms to practice.

    PubMed

    de Vos, Willem M

    2011-08-30

    Lactic acid bacteria are among the powerhouses of the food industry, colonize the surfaces of plants and animals, and contribute to our health and well-being. The genomic characterization of LAB has rocketed and presently over 100 complete or nearly complete genomes are available, many of which serve as scientific paradigms. Moreover, functional and comparative metagenomic studies are taking off and provide a wealth of insight in the activity of lactic acid bacteria used in a variety of applications, ranging from starters in complex fermentations to their marketing as probiotics. In this new era of high throughput analysis, biology has become big science. Hence, there is a need to systematically store the generated information, apply this in an intelligent way, and provide modalities for constructing self-learning systems that can be used for future improvements. This review addresses these systems solutions with a state of the art overview of the present paradigms that relate to the use of lactic acid bacteria in industrial applications. Moreover, an outlook is presented of the future developments that include the transition into practice as well as the use of lactic acid bacteria in synthetic biology and other next generation applications. PMID:21995776

  18. Systems solutions by lactic acid bacteria: from paradigms to practice

    PubMed Central

    2011-01-01

    Lactic acid bacteria are among the powerhouses of the food industry, colonize the surfaces of plants and animals, and contribute to our health and well-being. The genomic characterization of LAB has rocketed and presently over 100 complete or nearly complete genomes are available, many of which serve as scientific paradigms. Moreover, functional and comparative metagenomic studies are taking off and provide a wealth of insight in the activity of lactic acid bacteria used in a variety of applications, ranging from starters in complex fermentations to their marketing as probiotics. In this new era of high throughput analysis, biology has become big science. Hence, there is a need to systematically store the generated information, apply this in an intelligent way, and provide modalities for constructing self-learning systems that can be used for future improvements. This review addresses these systems solutions with a state of the art overview of the present paradigms that relate to the use of lactic acid bacteria in industrial applications. Moreover, an outlook is presented of the future developments that include the transition into practice as well as the use of lactic acid bacteria in synthetic biology and other next generation applications. PMID:21995776

  19. USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory


    We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

  20. Effects of acidic solutions on sexual reproduction of Pteridium aquilinum

    SciTech Connect

    Evans, L.S.; Conway, C.A.

    1980-01-01

    Experiments were performed to determine the effects of acidic solutions on spermatozoid motility and fertilization of gametophytes of Pteridium aquilinum. Buffered solutions (approx 0.0025 m) were used to simulate exposures to acidic precipitation for up to a 3.5 hr exposure. Experimental results suggest that the spermatozoid population can be subdivided into several groups with respect to pH sensitivity: About 25% spermatozoids are immobile one min after exposure to pH 6.1 buffer while about an equal percentage remain motile after 30 min exposure to buffer of pH 5.1. Between these two response extremes are two other subpopulations. One is quite sensitive to pH but shows some recovery if pH is between 5.6 and 6.1, while the second subpopulation does not seem to exhibit any motility recovery at all but is more resistant to acidity than the first subpopulation. To complement experiments that evaluate spermatozoid responses, experiments were performed to view the process of fertilization under controlled environmental conditions as well as under the canopy of a forest. Fertilization of gametophytes in uncovered petri dishes under a forest canopy was similar to results in aseptic culture after gametophytes were exposed to various pH levels and 86.6 micrometers sulfate. Fertilization at pH 4.5 and 3.6 was about one-half that occurring at pH 6.1. Fertilization in gametophytes exposed to pH 3.0 was about 10-20% of that occurring at pH 6.1. Addition of 86.6 micrometers sulfate decreased fertilization under all culture conditions. These experimental results suggest that fertilization in p. Aquilinum may be used as a bioindicator of contaminants in rainwater. The results demonstrate that spermatozoid motility (and the process of fertilization) is more acid sensitive than gametophytic and sporophytic tissues.

  1. Scavenging the Water Cation in Concentrated Acidic Solutions.

    PubMed

    Ma, Jun; LaVerne, Jay A; Mostafavi, Mehran

    2015-10-29

    Picosecond pulse radiolysis techniques were used to observe the kinetics of the SO4(•-), H2PO4(•), Cl2(•-), and Br2(•-) species formed in the fast oxidation of concentrated and highly acidic solutions of SO4(2-), PO4(3-), Cl(-), and Br(-). Experimental results were compared with model predictions to gain insight into the possible mechanisms occurring on the fast time scales. Simple kinetics involving the oxidizing OH(•) radical formed by radiolytic water decomposition could not account for the observed yields at the very short times (within the electron pulse ∼7 ps). Diffusion-kinetic simulations of the spur reactions induced by the incident electrons show that additional oxidation of the solutes must occur at very short times and involves their direct ionization along with scavenging of the highly oxidizing H2O(•+) radical formed in the initial ionization of the water medium. The fraction of H2O(•+) radicals scavenged varies as 0.26, 0.68, 0.92, and 0.97 for PO4(3-), SO4(2-), Cl(-), and Br(-) solutions, respectively. These studies represent the first semiquantitative estimation of the H2O(•+) radicals scavenging fractions for such a wide range of solutes. PMID:26449261

  2. Pseudo-capacitance on exfoliated carbon fiber in sulfuric acid electrolyte

    NASA Astrophysics Data System (ADS)

    Soneda, Y.; Yamashita, J.; Kodama, M.; Hatori, H.; Toyoda, M.; Inagaki, M.

    2006-03-01

    The specific capacitance of exfoliated carbon fibers (ExCF) which were synthesized from pitch-based carbon fibers showed a strong dependence with the concentration of sulfuric acid electrolyte and reached 1.4 F/m2 in 18 M H2SO4 solution. Since the capacitance value is quite large compared with the case of conventional activated carbons, faradic reactions (charge transfer reactions) are the cause of pseudo-capacitance. ExCF, however, gave a featureless cyclic voltammogram in 18 M H2SO4 solution. In the case of exfoliated natural graphite, the intercalation of H2SO4 molecules is evidenced by redox peaks observed in the voltammograms in the same conditions. Therefore, a strong interaction between the H2SO4 molecules and the ExCF surface might be the reason for the origin of pseudo-capacitance with ExCF in H2SO4 electrolyte.

  3. Solution and gas-phase acidities of all-trans (all-E) retinoic acid: an experimental and computational study.

    PubMed

    Abboud, José-Luis M; Koppel, Ilmar A; Uggerud, Einar; Leito, Ivo; Koppel, Ivar; Sekiguchi, Osamu; Kaupmees, Karl; Saame, Jaan; Kütt, Karl; Mishima, Masaaki

    2015-07-27

    Retinoic acid is of fundamental biological importance. Its acidity was determined in the gas phase and in acetonitrile solution by means of mass spectrometry and UV/Vis spectrophotometry, respectively. The intrinsic acidity is slightly higher than that of benzoic acid. In solution, the situation is opposite. The experimental systems were described theoretically applying quantum chemical methods (wave function theory and density functional theory). This allowed the determination of the molecular structure of the acid and its conjugate base, both in vacuo and in solution, and for computational estimates of its acidity in both phases. PMID:26186282

  4. Photosynthesis In Elodea canadensis Michx: Four-Carbon Acid Synthesis.

    PubMed

    Degroote, D; Kennedy, R A

    1977-06-01

    Experiments to determine the early labeled photosynthetic products in Elodea canadensis show that after 2 seconds of exposure to NaH(14)CO(3), 45% of the (14)C incorporated is located in malate and aspartate. Phosphoglyceric acid and sugars account for 27% of the label during similar exposures. Equivalent amounts of organic acids and C(3) cycle products are present after 8 seconds. Four-carbon acids remain relatively unchanged throughout the first 45 seconds of exposure, while sugars increase in a linear fashion. Enzyme assays indicate that ribulose diphosphate and phosphoenolpyruvate carboxylase enzymes are present in a ratio of approximately 2:1. It appears that E. canadensis is able to synthesize significant amounts of four-carbon acids via beta-carboxylation and this may play a role in maintaining a pH favorable for carboxylation in aquatic plants. PMID:16660008

  5. A mechanistic model of wormhole growth in carbonate matrix acidizing and acid fracturing

    SciTech Connect

    Hung, K.M.; Hill, A.D.; Sepehrnoorl, K.

    1989-01-01

    A mathematical model that describes the growth and competition of wormholes during ann acidizing treatment in a carbonate formation was developed. The model is initialized with the distribution of largest pores. Wormhole characteristics (size, length, and distribution) were found too be controlled by acid-injection, diffusion, and fluid-loss rates.

  6. Effects of dilute substitutional solutes on interstitial carbon in ?-Fe: Interactions and associated carbon diffusion from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Liu, Peitao; Xing, Weiwei; Cheng, Xiyue; Li, Dianzhong; Li, Yiyi; Chen, Xing-Qiu

    2014-07-01

    By means of first-principles calculations coupled with the kinetic Monte Carlo simulations, we have systematically investigated the effects of dilute substitutional solutes on the behaviors of carbon in ?-Fe. Our results uncover the following. (i) Without the Fe vacancy the interactions between most solutes and carbon are repulsive due to the strain relief, whereas Mn has a weak attractive interaction with its nearest-neighbor carbon due to the local ferromagnetic coupling effect. (ii) The presence of the Fe vacancy results in attractive interactions of all the solutes with carbon. In particular, the Mn-vacancy pair shows an exceptionally large binding energy of -0.81 eV with carbon. (iii) The alloying addition significantly impacts the atomic-scale concentration distributions and chemical potential of carbon in the Fe matrix. Among them, Mn and Cr increase the carbon chemical potential, whereas Al and Si reduce it. (iv) Within the dilute scale of the alloying solution, the solute concentration- and temperature-dependent carbon diffusivities demonstrate that Mn has a little impact on the carbon diffusion, whereas Cr (Al or Si) remarkably retards the carbon diffusion. Our results provide a certain implication for better understanding the experimental observations related with the carbon solubility limit, carbon microsegregation, and carbide precipitations in the ferritic steels.

  7. Muscle amino acid flux in patients receiving branched-chain amino acid solutions after surgery.

    PubMed

    Bonau, R A; Jeevanandam, M; Moldawer, L; Blackburn, G L; Daly, J M

    1987-04-01

    The metabolism and efficacy of branched-chain amino acids (BCAAs)-enriched parenteral solutions in patients after surgery are unclear. This prospective clinical study compared two groups of patients (n = 13) receiving either a 25% BCAA solution or a 45% BCAA solution at 30 kcal/kg/day and 1.5 gm protein/kg/day for 7 days after operation. Whole-body nitrogen balance and forearm muscle amino acid and ketoacid flux were measured. There were no significant differences between the two groups in mean cumulative nitrogen balance (+13.1 gm versus +18.0 gm) between the two groups. Patients receiving the 45% BCAA solution had significant mean uptake of total BCAA, leucine, and isoleucine compared with results in patients receiving the 25% BCAA solution. Despite this increased uptake of BCAA in the 45% BCAA group, there was no increased efflux of alanine, glutamine, or the BCAA ketoacids, ketoisocaproic, ketoisovaleric, or ketomethylvaleric. However, increased release of aspartate was noted in the 45% BCAA group compared with the 25% BCAA group. Thus use of a 45% BCAA-enriched solution infused in patients after surgery results in a significant increase in forearm muscle uptake of the BCAA that is not demonstrated in whole-body nitrogen economics. PMID:3563885

  8. The passivity of 304 stainless steel in propylene carbonate solutions

    SciTech Connect

    Shifler, D.A.; Kruger, J. ); Moran, P.J. )

    1992-01-01

    This paper reports that the passivation behavior of 304 stainless steel in anhydrous propylene carbonate (PC) containing 0.5M LiAsF{sub 6} or 0.5M LiClO{sub 4} was studied. The air-formed film on 304SS is stable up to the oxidation potential of PC (PC{sub ox}). Scratch tests show that the bared 304SS surface repassivates in the anhydrous PC solutions of either electrolyte by chemisorption of PC molecules below PC{sub ox}. In PC/0.5M LiAsF{sub 6} solutions, the 304SS is not passivated at potentials above PC{sub ox}. This is attributed to the formation of a thin metastable perchlorate salt film or an adsorbed layer of perchlorate anions. When the perchlorate anions oxidize, the passivation becomes unstable and pitting occurs. Small (3-8 volume percent) additions of PC/0.5M LiClO{sub 4} to PC/0.5M LiAsF{sub 6} solutions raised the passive range to the perchlorate oxidation potential. Small quantities of water, propylene glycol, and propylene oxide added to PC lightly improve the passive range of the 304 stainless steel.

  9. Decontamination of adsorbed chemical warfare agents on activated carbon using hydrogen peroxide solutions.

    PubMed

    Osovsky, Ruth; Kaplan, Doron; Nir, Ido; Rotter, Hadar; Elisha, Shmuel; Columbus, Ishay

    2014-09-16

    Mild treatment with hydrogen peroxide solutions (3-30%) efficiently decomposes adsorbed chemical warfare agents (CWAs) on microporous activated carbons used in protective garments and air filters. Better than 95% decomposition of adsorbed sulfur mustard (HD), sarin, and VX was achieved at ambient temperatures within 1-24 h, depending on the H2O2 concentration. HD was oxidized to the nontoxic HD-sulfoxide. The nerve agents were perhydrolyzed to the respective nontoxic methylphosphonic acids. The relative rapidity of the oxidation and perhydrolysis under these conditions is attributed to the microenvironment of the micropores. Apparently, the reactions are favored due to basic sites on the carbon surface. Our findings suggest a potential environmentally friendly route for decontamination of adsorbed CWAs, using H2O2 without the need of cosolvents or activators. PMID:25133545

  10. The Estimation of Acidic Behavior of Wood by Treatment with Aqueous Na2HPO4 Solution

    PubMed Central

    Uar, Gne?; Balaban Uar, Mualla

    2012-01-01

    As a new approach, the acidity that wood exhibits under moderate conditions is assayed by stimulated dissociation of weak wood acids in lightly basic secondary phosphate solutions. To assure a sufficient dissociation of hardly soluble weak acids in the solution, the amount of wood suspended in Na2HPO4 solutions should be small but vary depending on the degree of acidity of wood species. However, the difficulties are associated with the titration of very dilute acids limiting the precision of the measurement. If the disintegrated wood is suspended in a secondary phosphate solution, the weak woods acids form the conjugate acid Na2HPO4 from secondary phosphate Na2HPO4 resulting in a pH fall of the solution. The decrease in the pH value in phosphate solution, which depends on the wood acidity, can be evaluated to estimate the acidity arising from wood under moderate conditions. PMID:22567561

  11. Electrocatalytic hydrogenation of 5-hydroxymethylfurfural in acidic solution.

    PubMed

    Kwon, Youngkook; Birdja, Yuvraj Y; Raoufmoghaddam, Saeed; Koper, Marc T M

    2015-05-22

    Electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) is studied on solid metal electrodes in acidic solution (0.5 M H2 SO4 ) by correlating voltammetry with on-line HPLC product analysis. Three soluble products from HMF hydrogenation are distinguished: 2,5-dihydroxymethylfuran (DHMF), 2,5-dihydroxymethyltetrahydrofuran (DHMTHF), and 2,5-dimethyl-2,3-dihydrofuran (DMDHF). Based on the dominant reaction products, the metal catalysts are divided into three groups: (1) metals mainly forming DHMF (Fe, Ni, Cu, and Pb), (2) metals forming DHMF and DMDHF depending on the applied potentials (Co, Ag, Au, Cd, Sb, and Bi), and (3) metals forming mainly DMDHF (Pd, Pt, Al, Zn, In, and Sb). Nickel and antimony are the most active catalysts for DHMF (0.95 mM cm(-2) at ca. -0.35 VRHE and -20 mA cm(-2) ) and DMDHF (0.7 mM cm(-2) at -0.6 VRHE and -5 mA cm(-2) ), respectively. The pH of the solution plays an important role in the hydrogenation of HMF: acidic condition lowers the activation energy for HMF hydro-genation and hydrogenates the furan ring further to tetrahydrofuran. PMID:25908308

  12. New insight of amino acid-based dialysis solutions.

    PubMed

    Park, M S; Choi, S R; Song, Y S; Yoon, S Y; Lee, S Y; Han, D S

    2006-11-01

    Malnutrition is a major complication of peritoneal dialysis (PD) and is associated with increased morbidity and mortality. Daily losses of proteins and amino acids (AAs) into dialysate contribute to this problem. Previous metabolic balance study demonstrated that treatment with 1.1% AA-based dialysis solution is safe and may improve protein malnutrition in continuous ambulatory peritoneal dialysis (CAPD) patients ingesting low protein intake. Other prospective studies also showed that AA solution can provide nutritional benefit for malnourished PD patients resulting in a significant improvement in some biochemical and/or anthropometric nutritional parameters. However, there are other studies showing no particular improvement in nutritional parameters after long-term use of AA solution. This may be related to the differences in the study design, sample size, methods used to assess nutritional status, and other factors such as dietary intake and comorbidities of study subjects. Published data will be reviewed to further emphasize the nutritional benefit of long-term use of AA solution in malnourished PD patients along with a brief discussion on the various reasons that may partly explain the different study results. We will also present the results of a longitudinal observational study evaluating changes in nutritional parameters following use of one exchange of 1.1% AA solution in malnourished Korean PD patients. A significant improvement of somatic protein status such as lean body mass (LBM) and hand grip strength was observed. No significant change in serum albumin level was noted. Patients with a positive estimated coefficient for LBM in the fitted regression model to the repeated observations over 1 year were classified as responders and patients with neutral or negative coefficient were considered as non-responders. Thirty-one out of 43 malnourished patients (72%) showed nutritional benefit based on the change of LBM. Hand grip strength and back lift strength were significantly higher in responders at baseline. Other baseline parameters did not differ between the two groups. PMID:17080099

  13. Infrared optical constants of H2O ice, amorphous nitric acid solutions, and nitric acid hydrates

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Koehler, Birgit G.; Middlebrook, Ann M.; Tolbert, Margaret A.; Jordon, Joseph

    1994-01-01

    We determined the infrared optical constants of nitric acid trihydrate, nitric acid dihydrate, nitric acid monohydrate, and solid amorphous nitric acid solutions which crystallize to form these hydrates. We have also found the infrared optical constants of H2O ice. We measured the transmission of infrared light throught thin films of varying thickness over the frequency range from about 7000 to 500/cm at temperatures below 200 K. We developed a theory for the transmission of light through a substrate that has thin films on both sides. We used an iterative Kramers-Kronig technique to determine the optical constants which gave the best match between measured transmission spectra and those calculated for a variety of films of different thickness. These optical constants should be useful for calculations of the infrared spectrum of polar stratospheric clouds.

  14. Effect of acid treatment on dissolved organic carbon retention by a spodic horizon

    SciTech Connect

    Vance, G.F.; David, M.B.

    1989-01-01

    Processes involving the movement of organic substances in forest soils are not well understood. The study was conducted to examine the role of acidic inputs on dissolved organic carbon (DOC) mobility, processes affecting the retention of DOC by a B horizon, and SO4(2-) adsorption. Using O and B horizon samples from a Spodosol collected in a forested watershed in Maine, acid solutions leached through O, B, and O over B(O/B) soils in small vacuum extractor columns were analyzed for DOC, DOC fractions, and anions. For the O and O/B columns, DOC in the leachates decreased (7550 to 3350 and 2380 to 850 micro mol C/L, respectively) with an increase in acidic inputs; for the B horizon, the reverse was the case (435 to 1570 micro mol C/L). The DOC in leachates from the O horizon was dominated by hydrophobic and hydrophilic acids (68 and 20% of DOC with no acid addition), which were altered by acidic inputs (46 and 36% of DOC at p(H(1+))=2). The hydrophobic acid percentage in leachates from O/B horizon columns decreased from 52 to 28%, whereas hydrophilic acids increased from 27 to 47% with H2O and p(H(1+))=2 treatments, respectively. Ionic strength adjustment (I=0.01) of treatment solutions reduced C solubilization in O and O/B horizon leachates, leading to lower DOC leaching.

  15. Anaerobic carbon metabolism by the tricarboxylic acid cycle

    SciTech Connect

    Vanlerberghe, G.C.; Horsey, A.K.; Weger, H.G.; Turpin, D.H. )

    1989-12-01

    Nitrogen-limited cells of Selenastrum minutum (Naeg.) Collins are able to assimilate NH{sub 4}{sup +} in the dark under anaerobic conditions. Addition of NH{sub 4}{sup +} to anaerobic cells results in a threefold increase in tricarboxylic acid cycle (TCAC) CO{sub 2} efflux and an eightfold increase in the rate of anaplerotic carbon fixation via phosphoenspyruvate carboxylase. Both of these observations are consistent with increased TCAC carbon flow to supply intermediates for amino acid biosynthesis. Addition of H{sup 14}CO{sub 3}{sup {minus}} to anaerobic cells assimilating NH{sub 4}{sup +} results in the incorporation of radiolabel into the {alpha}-carboxyl carbon of glutamic acid. Incorporation of radiolabel into glutamic acid is not simply a short-term phenomenon following NH{sub 4}{sup +} addition as the specific activity of glutamic acid increases over time. This indicates that this alga is able to maintain partial oxidative TCAC carbon flow while under anoxia to supply {alpha}ketoglutarate for glutamate production. During dark aerobic NH{sub 4}{sup +} assimilation, no radiolabel appears in fumarate or succinate and only a small amount occurs in malate. During anaerobic NH{sub 4}{sup +} assimilation, these metabolites contain a large proportion of the total radiolabel and radiolabel accumulates in succinate over time. Also, the ratio of dark carbon fixation to NH{sub 4}{sup +} assimilation is much higher under anaerobic than aerobic conditions. These observations suggest the operation of a partial reductive TCAC from oxaloacetic acid to malate, fumarate, and succinate. Such a pathway might contribute to redox balance in an anaerobic cell maintaining partial oxidative TCAC activity.

  16. Removal of arsenious acid from sulfuric acidic solution using ultrasound oxidation and goethite

    NASA Astrophysics Data System (ADS)

    Okawa, Hirokazu; Yoshikawa, Tomohiro; Hosokawa, Ryota; Hangui, Shinji; Kawamura, Youhei; Sugawara, Katsuyasu

    2015-07-01

    We investigated the properties of synthetic goethite for the adsorption of As from strongly acidic solutions in ambient atmosphere under ultrasound irradiation. The goethite was successfully synthesized from iron-containing sulfuric acidic solution (1271 ppm) using an autoclave apparatus for 1 h at 0.12 MPa and 121 °C. The ratio of the iron eluted from the synthetic goethite to the acidic solution was only 0.58% at pH 2.1. Ultrasound irradiation (200 kHz, 200 W) was applied to oxidize 10 ppm of As(III) to As(V) at pH 2.2 for 60 min under various atmospheric conditions. Remarkably, the oxidation ratio of As(III) to As(V) is quite high (89.7%) at pH 2.2 in ambient atmosphere and is close to those obtained for Ar (95.3%) and O2 (95.9%) atmospheres. The As(III) removal ratio reached 94.5% after 60 min of irradiation. Therefore, goethite is a promising material for As adsorption using ultrasound oxidation in the acidic region in ambient atmosphere.

  17. Surface characterisation of ethylene propylene diene rubber upon exposure to aqueous acidic solution

    NASA Astrophysics Data System (ADS)

    Mitra, Susanta; Ghanbari-Siahkali, Afshin; Kingshott, Peter; Hvilsted, Søren; Almdal, Kristoffer

    2006-07-01

    Two types of pure ethylene propylene diene rubbers were exposed to two different acids for varying period of time. Surface characterisation was carried out using X-ray photoelectron spectroscopy (XPS). Two EPDM rubbers selected for this study were comparable in co-monomer compositions but significantly different with respect to molar mass and the presence of long chain branching. Both rubbers contained 5-ethylidene-2-norbornene (ENB) as diene. Solution cast films of pure EPDM samples were exposed in two different acidic solutions, viz. chromosulphuric (Cr (VI)/H 2SO 4) and sulphuric acid (H 2SO 4) (20%, v/v) at ambient temperature from 1 to 12 weeks. XPS analysis indicated that several oxygenated species were formed on the surface of both rubbers after exposure. It was postulated from the XPS analyses that both aqueous acidic solutions attacked the olefinic double bonds (C dbnd C) of ENB. Furthermore, 20% Cr (VI)/H 2SO 4 also attacked the allylic carbon-hydrogen (C sbnd H) bonds of ENB resulting in more oxygenated species on the surface compared to 20% H 2SO 4 under identical conditions. Cr (VI) in the 20% Cr (VI)/H 2SO 4 was found to play an important role in alteration of surface chemistry. Studies using a model system consisting of EPDM mixed with Cr (VI) and Cr (III) salts revealed that the change of oxidation state from Cr (VI) to Cr (III) as a consequence of direct involvement of Cr (VI) in the chemical alteration of EPDM surfaces. Interestingly, the presence of long chain branching and molar mass did not significantly influence the chemical processes owing to the acid treatment.

  18. Conformation of poly(γ-glutamic acid) in aqueous solution.

    PubMed

    Muroga, Yoshio; Nakaya, Asami; Inoue, Atsuki; Itoh, Daiki; Abiru, Masaya; Wada, Kaori; Takada, Masako; Ikake, Hiroki; Shimizu, Shigeru

    2016-04-01

    Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε < ε(*) , however, ε dependence of their overall conformation is significantly differentiated from each other. PγDLGA tends to aggregate intramolecularly and/or intermolecularly with decreasing ε, but PγLGA still behaves as expanded random-coil. It is speculated that spatial arrangement of adjacent carboxyl groups along the backbone chain essentially affects the overall conformation of PγGA in acidic media. © 2015 Wiley Periodicals, Inc. Biopolymers 105: 191-198, 2016. PMID:26574908

  19. Adsorption of fluoranthene in surfactant solution on activated carbon: equilibrium, thermodynamic, kinetic studies.

    PubMed

    Liu, Jianfei; Chen, Jiajun; Jiang, Lin; Wang, Xingwei

    2014-02-01

    Adsorption of fluoranthene (FLA) in surfactant solution on activated carbon (AC) was investigated. Isotherm, thermodynamic, and kinetic attributes of FLA adsorption in the presence of the surfactant on AC were studied. Effects of AC dosage, initial concentration of TX100, initial concentration of FLA, and addition of fulvic acid on adsorption were studied. The experimental data of both TX100 and FLA fitted the Langmuir isotherm model and the pseudo-second-order kinetic model well. Positive enthalpy showed that adsorption of FLA on AC was endothermic. The efficiency of selective FLA removal generally increased with increasing initial surfactant concentration and decreasing fulvic acid concentration. The surface chemistry of AC may determine the removal of polycyclic aromatic hydrocarbons. The adsorption process may be controlled by the hydrophobic interaction between AC and the adsorbate. The microwave irradiation of AC may be a feasible method to reduce the cost of AC through its regeneration. PMID:23979852

  20. Carbon quantum dots with photo-generated proton property as efficient visible light controlled acid catalyst

    NASA Astrophysics Data System (ADS)

    Li, Haitao; Liu, Ruihua; Kong, Weiqian; Liu, Juan; Liu, Yang; Zhou, Lei; Zhang, Xing; Lee, Shuit-Tong; Kang, Zhenhui

    2013-12-01

    Developing light-driven acid catalyst will be very meaningful for the controlled-acid catalytic processes towards a green chemical industry. Here, based on scanning electrochemical microscopy (SECM) and ?pH testing, we demonstrate that the 5-10 nm carbon quantum dots (CQDs) synthesized by electrochemical ablation of graphite have strong light-induced proton properties under visible light in solution, which can be used as an acid catalyst. The 5-10 nm CQDs' catalytic activity is strongly dependent on the illumination intensity and the temperature of the reaction system. As an effective visible light driven and controlled acid-catalyst, 5-10 nm CQDs can catalyze a series of organic reactions (esterification, Beckmann rearrangement and aldol condensation) with high conversion (34.7-46.2%, respectively) in water solution under visible light, while the 1-4 nm CQDs and 10-2000 nm graphite do not have such excellent catalytic activity. The use of 5-10 nm CQDs as a light responsive and controllable photocatalyst is truly a novel application of carbon-based nanomaterials, which may significantly push research in the current catalytic industry, environmental pollution and energy issues.Developing light-driven acid catalyst will be very meaningful for the controlled-acid catalytic processes towards a green chemical industry. Here, based on scanning electrochemical microscopy (SECM) and ?pH testing, we demonstrate that the 5-10 nm carbon quantum dots (CQDs) synthesized by electrochemical ablation of graphite have strong light-induced proton properties under visible light in solution, which can be used as an acid catalyst. The 5-10 nm CQDs' catalytic activity is strongly dependent on the illumination intensity and the temperature of the reaction system. As an effective visible light driven and controlled acid-catalyst, 5-10 nm CQDs can catalyze a series of organic reactions (esterification, Beckmann rearrangement and aldol condensation) with high conversion (34.7-46.2%, respectively) in water solution under visible light, while the 1-4 nm CQDs and 10-2000 nm graphite do not have such excellent catalytic activity. The use of 5-10 nm CQDs as a light responsive and controllable photocatalyst is truly a novel application of carbon-based nanomaterials, which may significantly push research in the current catalytic industry, environmental pollution and energy issues. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03996j

  1. Precipitation of plutonium from acidic solutions using magnesium oxide

    SciTech Connect

    Jones, S.A.

    1994-09-06

    Plutonium (IV) is only marginally soluble in alkaline solution. Precipitation of plutonium using sodium or potassium hydroxide to neutralize acidic solutions produces a gelatinous solid that is difficult to filter and an endpoint that is difficult to control. If the pH of the solution is too high, additional species precipitate producing an increased volume of solids separated. The use of magnesium oxide as a reagent has advantages. It is added as a solid (volume of liquid waste produced is minimized), the pH is self-limiting (pH does not exceed about 8.5), and the solids precipitated are more granular (larger particle size) than those produced using KOH or NaOH. Following precipitation, the raffinate is expected to meet criteria for disposal to tank farms. The solid will be heated in a furnace to dry it and convert any hydroxide salts to the oxide form. The material will be cooled in a desiccator. The material is expected to meet vault storage criteria.

  2. Electrophoretic deposition of phthalocyanine in organic solutions containing trifluoroacetic acid.

    PubMed

    Shrestha, Nabeen K; Kohn, Hideki; Imamura, Mitsuharu; Irie, Kazunobu; Ogihara, Hitoshi; Saji, Tetsuo

    2010-11-16

    The absorption spectra of copper phthalocyanine (CuPc) 1,2-dichloroethane (DCE) solutions containing trifluoroacetic acid (TFAA) shows that the number of protons coordinating to the CuPc molecule was 1 and 2 for the first and second proton adducts, respectively, which indicates the formations of CuPcH(+) and CuPcH(2)(2+). This CuPc molecule may act as a catalyst to dissociate TFAA into trifluoroacetate anion (A(-)) and H(+) and form the proton adducts. The electrical conductivity dependence of the solution on CuPc concentration also supports this mechanism. A dense film of CuPc was deposited on an indium tin oxide cathode plate by electrophoresis of the solution. Similar dense films of a wide variety of phthalocyanines (MPc; M = Cu, H(2), Fe, Ni, Zn, Pb, VO) were also deposited using this method. Similar films of CuPc were also formed using dichloromethane (DCM) and 1,1,1-trichloroethane (TCE) in place of DCE. Depositions are ascribed to the migration of positively charged monomers (i.e., protonated MPc). Scanning electron microscopy revealed that these films are composed of fibrous crystallites, size of which was found to increase with the electrophoresis time, the strength of the applied electrical field and the concentration of CuPc in the bath. The influence of the dielectric constant of the organic solvent on the film growth is discussed. PMID:20886893

  3. INTERACTION OF AQUEOUS SOLUTIONS OF CHLORINE WITH MALIC ACID, TARTARIC ACID, AND VARIOUS FRUIT JUICES, A SOURCE OF MUTAGENS

    EPA Science Inventory

    The interactions of aqueous solutions of chlorine with some fruit acids (citric acid, DL-malic acid, and L-tartaric acid) at different pH values were studied. iethyl ether extraction followed by GC/MS analysis indicated that a number of mutagens (certain chlorinated propanones an...

  4. Sequential Mukaiyama-Michael reaction induced by carbon acids.

    PubMed

    Yanai, Hikaru; Kobayashi, Osamu; Takada, Kenji; Isono, Takuya; Satoh, Toshifumi; Matsumoto, Takashi

    2016-02-16

    In the presence of a strong carbon acid, the sequential Mukaiyama-Michael reaction using two different Michael acceptors proceeded and the reaction of ketene silyl acetal derived from EtOAc with α-pyrones as primal acceptors yielded the corresponding cyclic ketene silyl acetals, which were reactive enough to undergo the following reaction with second acceptors. PMID:26734829

  5. Oxidative photodegradation of herbicide fenuron in aqueous solution by natural iron oxide ?-Fe2O3, influence of polycarboxylic acids.

    PubMed

    Kribche, Mohamed El Amine; Mechakra, Hind; Sehili, Tahar; Brosillon, Stephan

    2016-01-01

    The photodegradation of the herbicide fenuron (1,1-dimethyl-3-phenylurea) by using a natural iron oxide (NIO), ?-Fe2O3, in aqueous solution at acidic pH has been undertaken. The NIO was characterized by the Raman spectroscopy method. The degradation pathways and the formation of degradation products were studied. A high-pressure mercury lamp and sunlight were employed as light source. Fenuron photodegradation using NIO with oxalic acid followed the pseudo-first-order kinetics, the optimal experimental conditions were [oxalic acid]0?=?10(-3) M and [NIO]?=?0.1?g?L(-1) at pH 3. A UVA/NIO/oxalic acid system led to a low fenuron half-life (60?min). The results were even better when solar light is used (30?min). The variables studied were the doses of iron oxide, of carboxylic acids, the solution pH and the effect of sunlight irradiation. The effects of four carboxylic acids, oxalic, citric, tartaric and malic acids, on the fenuron photodegradation with NIO have been investigated, oxalic acid was the most effective carboxylic acid used at pH 3. A similar trend was observed for the removal of total organic carbon (TOC), 75% of TOC was removed. The analytical study showed many aromatic intermediates, short-chain carboxylic acids and inorganic ion. PMID:26102217

  6. N-Co-O Triply Doped Highly Crystalline Porous Carbon: An Acid-Proof Nonprecious Metal Oxygen Evolution Catalyst.

    PubMed

    Yang, Shiliu; Zhan, Yi; Li, Jingfa; Lee, Jim Yang

    2016-02-10

    In comparison with nonaqueous Li-air batteries, aqueous Li-air batteries are kinetically more facile and there is more variety of non-noble metal catalysts available for oxygen electrocatalysis, especially in alkaline solution. The alkaline battery environment is however vulnerable to electrolyte carbonation by atmospheric CO2 resulting in capacity loss over time. The acid aqueous solution is immune to carbonation but is limited by the lack of effective non-noble metal catalysts for the oxygen evolution reaction (OER). This is contrary to the oxygen reduction reaction (ORR) in acid solution where a few good candidates exist. We report here the development of a N-Co-O triply doped carbon catalyst with substantial OER activity in acid solution by the thermal codecomposition of polyaniline, cobalt salt and cyanamide in nitrogen. Cyanamide and the type of cobalt precursor salt were found to determine the structure, crystallinity, surface area, extent of Co doping and consequently the OER activity of the final carbon catalyst in acid solution. We have also put forward some hypotheses about the active sites that may be useful for guiding further work. PMID:26795393

  7. Capture of carbon dioxide from ethanol fermentation by liquid absorption for use in biological production of succinic acid.

    PubMed

    Nghiem, Nhuan P; Senske, Gerard E

    2015-02-01

    Previously, it was shown that the gas produced in an ethanol fermentor using either corn or barley as feedstock could be sparged directly into an adjacent fermentor as a feedstock for succinic acid fermentation using Escherichia coli AFP184. In the present investigation, it was demonstrated that the CO2 produced in a corn ethanol fermentor could be absorbed in a base solution and the resultant carbonate solution used both for pH control and supply of the CO2 requirement in succinic acid fermentation. Thus, the CO2 produced in a 5-L corn mash containing 30 wt% total solids was absorbed in a packed column containing 2 L of either 5 M NaOH, 5 M KOH, or 15 wt% NH4OH, and the resultant carbonate solutions were used for pH control in a succinic acid fermentor. The results obtained indicated no significant differences between succinic acid production in these experiments and when 2.5 M solutions of Na2CO3, K2CO3, and (NH4)2CO3 from commercial sources were used. In a commercial setting, the demonstrated capture of CO2 in liquid form will allow transportation of the carbonate solutions to locations not in the immediate vicinity of the ethanol plant, and excess carbonate salts can also be recovered as value-added products. PMID:25448631

  8. Ozonation of activated carbons: Effect on the adsorption of selected phenolic compounds from aqueous solutions.

    PubMed

    Alvarez, P M; García-Araya, J F; Beltrán, F J; Masa, F J; Medina, F

    2005-03-15

    The impact of ozonation on textural and chemical surface characteristics of two granular activated carbons (GAC), namely F400 and AQ40, and their ability to adsorb phenol (P), p-nitrophenol (PNP), and p-chlorophenol (PCP) from aqueous solutions have been studied. The porous structure of the ozone-treated carbons remained practically unchanged with regard to the virgin GAC. However, important modifications of the chemical surface and hydrophobicity were observed from FTIR spectroscopy, pH titrations, and determination of pH(PZC). As a rule, the ozone treatment at either room temperature (i.e., about 25 degrees C) or 100 degrees C gave rise to acidic surface oxygen groups (SOG). At 25 degrees C primarily carboxylic acids were formed while a more homogeneous distribution of carboxylic, lactonic, hydroxyl, and carbonyl groups was obtained at 100 degrees C. The experimental isotherms for phenolic compounds on both GAC were analyzed using the Langmuir model. Dispersive interactions between pi electrons of the ring of the aromatics and those of the carbon basal planes were thought to be the primary forces responsible for the physical adsorption whereas oxidative coupling of phenolic compounds catalyzed by basic SOG was a major cause of irreversible adsorption. The exposure of both GAC to ozone at room temperature decreased their ability to adsorb P, PNP, and PCP. However, when ozone was applied at 100 degrees C adsorption was not prevented but in some cases (P and PNP on F400) the adsorption process was even enhanced. PMID:15721926

  9. The extraction of actinides from nitric acid solutions with diamides of dipicolinic acid

    NASA Astrophysics Data System (ADS)

    Lapka, Joseph L.; Paulenova, Alena; Alyapyshev, Mikhail Yu; Babain, Vasiliy A.; Law, Jack D.; Herbst, R. Scott

    2010-03-01

    Diamides of dipicolinic acid (N,N'-diethyl-N,N'-ditolyl-dipicolinamide, EtTDPA) were synthesized and evaluated for their extraction capability for actinides. In this work the extractions of neptunium(V), protactinium(V), and thorium(IV) with EtTDPA in a polar fluorinated diluent from nitric acid were investigated. EtTDPA shows a high affinity for Th(IV) even at millimolar concentrations. Np(V) and Pa(V) are both reasonably extractable with EtTDPA; however, near saturated solutions are required to achieve appreciable distribution ratios. A comparison with previously published actinide extraction data is given.

  10. The solvent effect on the acidities of haloacetic acids in aqueous solution. A RISM-SCF study

    NASA Astrophysics Data System (ADS)

    Kawata, Masaaki; Ten-no, Seiichiro; Kato, Shigeki; Hirata, Fumio

    1995-06-01

    The acidities of acetic, fluoracetic and chloroacetic acids in aqueous solution are calculated by means of the ab initio method combined with the reference interaction site method in the statistical mechanics of molecular liquids (the RISM-SCF method). The inversion in the order of acidities experimentally observed when a series of haloacetic acids is immersed into aqueous solution is reproduced. It is shown that the inversion is caused by competition between substitution and solvation effects. The solvation effect is discussed in molecular detail in terms of the charge distribution of the solute and the solute-solvent radial distribution functions.

  11. Preconcentration of f-elements from aqueous solution utilizing a modified carbon paste electrode.

    PubMed

    Schumacher, Paul D; Fitzgerald, Kelly A; Schenk, James O; Clark, Sue B

    2011-02-15

    An evaluation using paraffin oil based, Acheson 38 carbon paste electrodes modified with α-hydroxyisobutyric acid (HIBA) to preconcentrate f-elements cathodically is described. The modified paste was made by directly mixing solid HIBA into the carbon paste. A chemically reversible cyclic voltammogram for HIBA was observed on this modified carbon paste, which was found to be a non-Nerstian, single electron transfer process. Lanthanides (less promethium) were found to accumulate onto the electrode surface during a 30 s electrodeposition step at -0.4 V vs Ag/AgCl from 0.1 M LiCl. The elements were then stripped off into a 2% HNO(3) solution by an oxidative step at +0.8 V vs Ag/AgCl; quantitative removal from the electrode was confirmed by ICPMS. Ultratrace solutions with initial concentrations down to 5 parts per quadrillion (ppq) were preconcentrated in 5 min above our instrumental limit of detection (LOD) of around 1 ppt for lanthanides. PMID:21271692

  12. Polyelectrolyte and carbon nanotube multilayers made from ionic liquid solutions.

    PubMed

    Nakashima, Takuya; Zhu, Jian; Qin, Ming; Ho, Szushen; Kotov, Nicholas A

    2010-10-01

    The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best "green" processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 10(2) S m(-1) with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods. PMID:20931147

  13. Methods for estimation of long-term non-carbonate neutralisation of acid rock drainage.

    PubMed

    Miller, Stuart D; Stewart, Warwick S; Rusdinar, Yuni; Schumann, Russell E; Ciccarelli, Joseph M; Li, Jun; Smart, Roger St C

    2010-04-01

    In the long-term phase of an acid rock drainage (ARD) evolution profile, after any short-term neutralisation capacity provided by carbonate minerals is exhausted, the net acid release is a product of a declining acid generation rate (AGR) and a slower, long-term acid neutralisation rate mainly provided by gangue silicate minerals. At some point, the AGR and the non-carbonate acid neutralisation rate (ANRnc) will be similar. Matching of the AGR and ANRnc near 10mg H(2)SO(4)/kg/week is demonstrated in data from 10-year columns. This long-term neutralisation is not measured at present in any accepted assessment tests. Methods to estimate ANRnc, based on silicate mineralogy and solution assays from long-term column leach tests, are compared. Good agreement is demonstrated between rates measured from the solution assay data and those calculated from mineralogy using kinetic databases. More rigorous analysis of the leachate chemistry of selected long-term leach tests also suggests possible cover design criteria based on the maximum AGR that will maintain a pH>4 in leachate from ARD materials. The data show a distinct break at an AGR of 3mg H(2)SO(4)/kg/week, below which no leachate pH is less than 4. The results indicate that an AGR of 10t H(2)SO(4)/ha/year is conservative and a suitable cover design target for ARD control that would be matched by ANRnc. PMID:20097405

  14. Soil-solution partitioning of DOC in acid organic soils: Results from a UK field acidification and alkalization experiment

    NASA Astrophysics Data System (ADS)

    Oulehle, Filip; Jones, Timothy; Burden, Annette; Evans, Chris

    2013-04-01

    Dissolved organic carbon (DOC) is an important component of the global carbon (C) cycle and has profound impacts on water chemistry and metabolism in lakes and rivers. Reported increases of DOC concentration in surface waters across Europe and Northern America have been attributed to several drivers; from changing climate and land-use to eutrophication and declining acid deposition. The last of these suggests that acidic deposition suppressed the solubility of DOC, and that this historic suppression is now being reversed by reducing emissions of acidifying pollutants. We studied a set of four parallel acidification and alkalization experiments in organic rich soils which, after three years of manipulation, have shown clear soil solution DOC responses to acidity change. We tested whether these DOC concentration changes were related to changes in the acid/base properties of DOC. Based on laboratory determination of DOC site density (S.D. = amount of carboxylic groups per milligram DOC) and charge density (C.D. = organic acid anion concentration per milligram DOC) we found that the change in DOC soil-solution partitioning was tightly related to the change in degree of dissociation (α = C.D./S.D. ratio) of organic acids (R2=0.74, p<0.01). Carbon turnover in soil organic matter (SOM), determined by soil respiration and β-D-glucosidase enzyme activity measurements, also appears to have some impact on DOC leaching, via constraints on the actual supply of available DOC from SOM; when the turnover rate of C in SOM is low, the effect of α on DOC leaching is reduced. Thus, differences in the magnitude of DOC changes seen across different environments might be explained by interactions between physicochemical restrictions of DOC soil-solution partitioning, and SOM carbon turnover effects on DOC supply.

  15. Activated carbons from potato peels: The role of activation agent and carbonization temperature of biomass on their use as sorbents for bisphenol A uptake from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Arampatzidou, An; Deliyanni, Eleni A.

    2015-04-01

    Activated carbons prepared from potato peels, a solid waste by product, and activated with different activating chemicals, have been studied for the adsorption of an endocrine disruptor (Bisphenol-A) from aqueous solutions. The potato peels biomass was activated with phosphoric acid, KOH and ZnCl2. The different activating chemicals were tested in order the better activation agent to be found. The carbons were carbonized by pyrolysis, in one step procedure, at three different temperatures in order the role of the temperature of carbonization to be pointed out. The porous texture and the surface chemistry of the prepared activated carbons were characterized by Nitrogen adsorption (BET), Scanning Electron Microscope (SEM), thermal analysis (DTA) and Fourier Transform Infrared Spectroscopy (FTIR). Batch experiments were performed to investigate the effect of pH, the adsorbent dose, the initial bisphenol A concentration and temperature. Equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherms. The thermodynamic parameters such as the change of enthalpy (ΔH0), entropy (ΔS0) and Gibb's free energy (ΔG0) of adsorption systems were also evaluated. The adsorption capacity calculated from the Langmuir isotherm was found to be 450 mg g-1 at an initial pH 3 at 25 °C for the phosphoric acid activated carbon, that make the activated carbon a promising adsorbent material.

  16. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R. A.

    2012-03-12

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 °C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. At 25 °C, for 6 M HNO{sub 3}, 11 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2.5 g/L and 0.8 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}. The solubility of Gd in 4 M HNO{sub 3} with 0.15 M oxalate at 10 °C is about 1.5 g/L. For 6 M HNO{sub 3} with 0.15 M oxalate, the solubility of Gd at 10 °C is about 10 g/L. Gadolinium nitrate is very soluble in HNO{sub 3}. The solubility of Gd is linear as a function of HNO{sub 3} from 343 g/L Gd in 2.88 M HNO{sub 3} to 149 g/L in 8.16 M HNO{sub 3}. Below 2.88 M HNO{sub 3}, the solubility of Gd approaches a limit of about 360 g/L. However, there are no data available below 1.40 M HNO{sub 3}, which has a Gd solubility of 353 g/L.

  17. Radiolysis gases from nitric acid solutions containing HSA and HAN

    SciTech Connect

    Smith, J.R.

    1994-10-28

    The concentration of hydrogen (H{sub 2}) in the radiolytically produced off-gas from 2.76-4.25M HNO{sub 3}/PU solutions has been found to be greatly reduced in the presence of sulfamic acid (HSA) and hydroxylamine nitrate (HAN). The H{sub 2} concentration ([H{sub 2}]) is reduced from 35 percent to about 4 percent by dilution caused from an increase in the production rates of nitrogen (N{sub 2}), nitrous oxide (N{sub 2}O), and oxygen (O{sub 2}) gases. The generation rate of H{sub 2} was not affected by HSA or HAN giving a measured radiolytic yield, G(H{sub 2}), value of 0.201 molecules/100 eV for 2.765M NO{sub 3}{sup -} solution (a value of 0.213 is predicted from previous data). The G(H{sub 2}) values are dependent on the solution nitrate concentration ([NO{sub 3}{sup -}]). The generation rates of N{sub 2}, N{sub 2}O, and O{sub 2} are not dependent on the [NO{sub 3}{sup -}] in this narrow range, but are dependent on the presence of HSA and the concentration of HAN. The percentage [H{sub 2}] for the 2.5 to 3.0M NO{sub 3}{sup -} range expected in the off- from the FB-Line Pu{sup +3} Hold Tanks is conservatively estimated to be about 3.5 to 4.5 % for Pu + 3 solutions initially containing 0.023M HAN/0.165M HSA. The upper limit [H{sub 2}] may actually be about 4.1 % (4.3 % at 90 % confidence limits) but more {open_quotes}initial{close_quotes} off-gas rate data is needed at about 2.9M [NO{sub 3}{sup -}] in Pu{sup +3} solution for verification. Addition of ascorbic acid had no effect on the off-gas rate of Pu{sup +3} solutions containing HSA and NO{sub 3}{sup -} concentrations higher than those expected in the hold tanks. The maximum {open_quotes}hold time{close_quotes} for 50 grams/liter Pu{sup +3}/0.165M HSA/0.023M HAN/2.5-3.0M HNO{sub 3} solution is 20.3{+-}2.1 days. After this time the HSA initially present will become exhausted and the [H{sub 2}] will increase to 35 %. This hold time may be longer in [NO{sub 3}{sup -}] < 3.0M, but again more study is needed.

  18. Hydrogen chemisorption on Pt single crystal surfaces in acidic solutions

    NASA Astrophysics Data System (ADS)

    Ross, Philip N.

    1981-01-01

    Hydrogen chemisorption from dilute acidic solution onto Pt single crystal surfaces was examined using an electrochemical cell directly coupled to LEED/Auger analytical system. No pre-anodization was used prior to observing hydrogen adsorption by cyclic voltammetry so that clean surfaces having the ordered structures indicated by LEED were studied. The problem of contributions from non-ordered parts of the electrode like support wires and edges was solved by using a gold evaporation masking technique. The specific contribution of atomic imperfections to the voltammetry curve was deduced from the ordered and countable imperfections occurring on high Miller index single crystal surfaces that have a stepped structure. The H-Pt bond energy was found to be structure sensitive, and sensitive both to local site geometry and long range order in the surface. The bond strength was found to vary systematically: n(111) (100) > (100) > n(111) (111) > (110) > (111). Distinct states for hydrogen at steps versus hydrogen on terraces could be distinguished. The (110) surface is shown to be a (111) vicinal, probably the [3(111) 2(111)] microfacetted surface. The zero coverage heat of adsorption on the well-ordered (111) surface (48 {kJ}/{mol}) in solutions is the same as the value reported by Ertl and co-workers for adsorption on a (111) surface in vacuum. Adsorption isotherms for hydrogen on the (111) and (100) surfaces are adequately fit by the classical model for immobile adsorption at single sites with nearest neighbor repulsive interaction.

  19. Photochlorination of Polycyclic Aromatic Hydrocarbons in Acidic Brine Solution.

    PubMed

    Ohura, Takeshi; Miwa, Makoto

    2016-04-01

    The potential for the formation of chlorinated polycyclic aromatic hydrocarbons via photochlorination of PAHs has been investigated in milli-Q water/synthetic water containing NaCl and PAHs with either UV or visible light. The photochlorination of pyrene occurred under acidic conditions in the presence of both UV and visible light, resulting in 1-chloropyrene as the main product. Benzo[a]pyrene yielded 6-chlorobenzo[a]pyrene following visible light irradiation; however the reaction was dependent upon solution pH. The photochlorination of PAHs was proposed to proceed via a consecutive reaction model. The rate constants associated with the photochlorination and photodecay processes were determined with the observed and theoretical values displaying similar trends, whereas the observed values were approximately 50-1000 times lower than the theoretical values. The lower observed values could be due to undergo photodecay rather than photochlorination of PAHs. Therefore, as photochlorination of PAHs appears to be significantly affected by solution pH, this information may allow for minimizing the impact on the environment. PMID:26728279

  20. Solution structures of europium(III) complexes of ethylenediaminetetraacetic acid

    SciTech Connect

    Latva, M.; Kankara, J.; Haapakka, K.

    1996-04-01

    Coordination of ethylenediaminetetraacetic acid (EDTA) with europium(III) has been studied at different concentrations in solution using {sup 7}F{sub 0}{yields}{sup 5}D{sub 0} excitation spectroscopy and excited-state lifetime measurements. EDTA forms with Eu(III) ion three different species in equimolar solutions at room temperature. At low pH values EuEDTAH is formed and at higher pH values than 1.5 two EuEDTA{sup -} complexes, which differ from each other with one water molecule in the first coordination sphere of the Eu(III) ion, total coordination number and coordination geometry, are also formed. When the concentration of EDTA is higher than the concentration of Eu(III), an EuEDTA(EDTAH){sup 4-} species where the second EDTA is weakly coordinated to EuEDTA{sup -}, is formed. If the concentration of Eu(III) ion is higher than EDTA, the extra Eu(III) ions associate with EuEDTA{sup -} and link to one of the carboxylate groups of EDTA thus causing a shortening of the excited-state lifetime of the EuEDTA{sup -} complex.

  1. CARBON CONTRIBUTION AND CHARACTERISTICS OF HUMIC ACID, FULVIC ACID, PARTICULATE ORGANIC MATTER AND GLOMALIN IN DIVERSE ECOSYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Global climate change and soil carbon sequestration issues are entering the forefront of public policy, and emphasis is growing for research on carbon sinks and long-term terrestrial carbon stabilization. Humic acid (HA), fulvic acid (FA), humin and particulate organic matter (POM) have traditionall...

  2. Carbon Footprint of Telemedicine Solutions - Unexplored Opportunity for Reducing Carbon Emissions in the Health Sector

    PubMed Central

    Holmner, Åsa; Ebi, Kristie L.; Lazuardi, Lutfan; Nilsson, Maria

    2014-01-01

    Background The healthcare sector is a significant contributor to global carbon emissions, in part due to extensive travelling by patients and health workers. Objectives To evaluate the potential of telemedicine services based on videoconferencing technology to reduce travelling and thus carbon emissions in the healthcare sector. Methods A life cycle inventory was performed to evaluate the carbon reduction potential of telemedicine activities beyond a reduction in travel related emissions. The study included two rehabilitation units at Umeå University Hospital in Sweden. Carbon emissions generated during telemedicine appointments were compared with care-as-usual scenarios. Upper and lower bound emissions scenarios were created based on different teleconferencing solutions and thresholds for when telemedicine becomes favorable were estimated. Sensitivity analyses were performed to pinpoint the most important contributors to emissions for different set-ups and use cases. Results Replacing physical visits with telemedicine appointments resulted in a significant 40–70 times decrease in carbon emissions. Factors such as meeting duration, bandwidth and use rates influence emissions to various extents. According to the lower bound scenario, telemedicine becomes a greener choice at a distance of a few kilometers when the alternative is transport by car. Conclusions Telemedicine is a potent carbon reduction strategy in the health sector. But to contribute significantly to climate change mitigation, a paradigm shift might be required where telemedicine is regarded as an essential component of ordinary health care activities and not only considered to be a service to the few who lack access to care due to geography, isolation or other constraints. PMID:25188322

  3. Controlled exposures of volunteers to respirable carbon and sulfuric acid aerosols

    SciTech Connect

    Anderson, K.R.; Avol, E.L.; Edwards, S.A.; Shamoo, D.A.; Ruchuan Peng; Linn, W.S.; Hackney, J.D. )

    1992-06-01

    Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, the authors exposed 15 healthy and 15 asthmatic volunteers in a controlled-environment chamber to four test atmospheres: (1) clean air; (2) 0.5-{mu}m H{sub 2}SO{sub 4} aerosol at {approx}100 {mu}g/m{sup 3}, generated from water solution; (3) 0.5-{mu}m carbon aerosol at {approx}250 {mu}g/m{sup 3}, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (4) carbon as in (3) plus {approx}100 {mu}g/m{sup 3} of ultrafine H{sub 2}SO{sub 4} aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (4) became attached to carbon particle surfaces, and that most particles remained in the sub-{mu}m size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation {approx}50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at end-exposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H{sub 2}SO{sub 4} or carbon, separate or interactive, on health measures.

  4. Carbonate precipitation under bulk acidic conditions as a potential biosignature for searching life on Mars

    NASA Astrophysics Data System (ADS)

    Fernández-Remolar, David C.; Preston, Louisa J.; Sánchez-Román, Mónica; Izawa, Matthew R. M.; Huang, L.; Southam, Gordon; Banerjee, Neil R.; Osinski, Gordon R.; Flemming, Roberta; Gómez-Ortíz, David; Prieto Ballesteros, Olga; Rodríguez, Nuria; Amils, Ricardo; Darby Dyar, M.

    2012-10-01

    Recent observations of carbonate minerals in ancient Martian rocks have been interpreted as evidence for the former presence of circumneutral solutions optimal for carbonate precipitation. Sampling from surface and subsurface regions of the low-pH system of Río Tinto has shown, unexpectedly, that carbonates can form under diverse macroscopic physicochemical conditions ranging from very low to neutral pH (1.5-7.0). A multi-technique approach demonstrates that carbonate minerals are closely associated with microbial activity. Carbonates occur in the form of micron-size carbonate precipitates under bacterial biofilms, mineralization of subsurface colonies, and possible biogenic microstructures including globules, platelets and dumbbell morphologies. We propose that carbonate precipitation in the low-pH environment of Río Tinto is a process enabled by microbially-mediated neutralization driven by the reduction of ferric iron coupled to the oxidation of biomolecules in microbially-maintained circumneutral oases, where the local pH (at the scale of cells or cell colonies) can be much different than in the macroscopic environment. Acidic conditions were likely predominant in vast regions of Mars over the last four billion years of planetary evolution. Ancient Martian microbial life inhabiting low-pH environments could have precipitated carbonates similar to those observed at Río Tinto. Preservation of carbonates at Río Tinto over geologically significant timescales suggests that similarly-formed carbonate minerals could also be preserved on Mars. Such carbonates could soon be observed by the Mars Science Laboratory, and by future missions to the red planet.

  5. Carbonic acid ionization and the stability of sodium bicarbonate and carbonate ion pairs to 200 C - A potentiometric and spectrophotometric study

    NASA Astrophysics Data System (ADS)

    Stefnsson, Andri; Bnzeth, Pascale; Schott, Jacques

    2013-11-01

    Carbonic acid ionization and sodium bicarbonate and carbonate ion pair formation constants have been experimentally determined in dilute hydrothermal solutions to 200 C. Two experimental approaches were applied, potentiometric acid-base titrations at 10-60 C and spectrophotometric pH measurements using the pH indicators, 2-napthol and 4-nitrophenol, at 25-200 C. At a given temperature, the first and second ionization constants of carbonic acid (K1, K2) and the ion pair formation constants for NaHCO(aq)(K) and NaCO3-(aq)(K) were simultaneously fitted to the data. Results of this study compare well with previously determined values of K1 and K2. The NaHCO(aq) and NaCO3-(aq) ion pair formation constants vary between 25 and 200 C having values of logK=-0.18 to 0.58 and logK=1.01 to 2.21, respectively. These ion pairs are weak at low-temperatures but become increasingly important with increasing temperature under neutral to alkaline conditions in moderately dilute to concentrated NaCl solutions, with NaCO3-(aq) predominating over CO32-(aq) in ?0.1 M NaCl solution at temperatures above 100 C. The results demonstrate that NaCl cannot be considered as an inert (non-complexing) electrolyte in aqueous carbon dioxide containing solutions at elevated temperatures.

  6. Polyelectrolyte and carbon nanotube multilayers made from ionic liquid solutions

    NASA Astrophysics Data System (ADS)

    Nakashima, Takuya; Zhu, Jian; Qin, Ming; Ho, Szushen; Kotov, Nicholas A.

    2010-10-01

    The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods.The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods. Electronic supplementary information (ESI) available: Aggregation of PEI and PSS in [EMIm][EtSO4], detailed FTIR data, water-contact angle for (PEI/PSS)10 multilayers, and XPS survey spectra. See DOI: 10.1039/b9nr00333a

  7. Interaction of trace elements in acid mine drainage solution with humic acid.

    PubMed

    Suteerapataranon, Siripat; Bouby, Muriel; Geckeis, Horst; Fanghnel, Thomas; Grudpan, Kate

    2006-06-01

    The release of metal ions from a coal mining tailing area, Lamphun, Northern Thailand, is studied by leaching tests. Considerable amounts of Mn, Fe, Al, Ni and Co are dissolved in both simulated rain water (pH 4) and 10 mg L(-1) humic acid (HA) solution (Aldrich humic acid, pH 7). Due to the presence of oxidizing pyrite and sulfide minerals, the pH in both leachates decreases down to approximately 3 combined with high sulfate concentrations typical to acid mine drainage (AMD) water composition. Interaction of the acidic leachates upon mixing with ground- and surface water containing natural organic matter is simulated by subsequent dilution (1:100; 1:200; 1:300; 1:500) with a 10 mg L(-1) HA solution (ionic strength: 10(-3) mol L(-1)). Combining asymmetric flow field-flow fractionation (AsFlFFF) with UV/Vis and ICP-MS detection allows for the investigation of metal ion interaction with HA colloid and colloid size evolution. Formation of colloid aggregates is observed by filtration and AsFlFFF depending on the degree of the dilution. While the average HA size is initially found to be 2 nm, metal-HA complexes are always found to be larger. Such observation is attributed to a metal induced HA agglomeration, which is found even at low coverage of HA functional groups with metal ions. Increasing the metal ion to HA ratio, the HA bound metal ions and the HA entities are growing in size from <3 to >450 nm. At high metal ion to HA ratios, precipitation of FeOOH phases and HA agglomeration due to colloid charge neutralization by complete saturation of HA complexing sites are responsible for the fact that most of Fe and Al precipitate and are found in a size fraction >450 nm. In the more diluted solutions, HA is more relevant as a carrier for metal ion mobilization. PMID:16631855

  8. Adsorption of Acid Blue 193 from aqueous solutions onto Na-bentonite and DTMA-bentonite.

    PubMed

    Ozcan, A Safa; Erdem, Bilge; Ozcan, Adnan

    2004-12-01

    Dodecyltrimethylammonium bromide-modified bentonite (DTMA-bentonite) was prepared and tested as an adsorbent for an acid dye (Acid Blue 193, AB193) removal from aqueous solution in comparison with Na-bentonite. The effect of various experimental parameters was investigated using a batch adsorption technique. In this manner, the adsorption isotherms, adsorption kinetics, and temperature and pH effects upon Acid Blue 193 adsorption on Na-bentonite and DTMA-bentonite were thoroughly examined. Results show that a pH value of 1.5 is favorable for the adsorption of Acid Blue 193. The isothermal data could be well described by the Freundlich equation. The dynamical data fit well with the pseudo-second-order kinetic model. The adsorption capacity of DTMA-bentonite (740.5 mg g(-1)) was found to be around 11 times higher than that of Na-bentonite (67.1 mg g(-1)) at 20 degrees C. Thermodynamic parameters such as activation energy (E(a)) and change in the free energy (DeltaG(0)), the enthalpy (DeltaH(0)), and the entropy (DeltaS(0)) were also evaluated. The overall adsorption process was exothermic but it is only spontaneous at 20 degrees C. The results indicate that Na-bentonite and DTMA-bentonite could be employed as low-cost alternatives to activated carbon in wastewater treatment for the removal of color which comes from textile dyes. PMID:15476772

  9. Removal of fluoride in aqueous solution by adsorption on acid activated water treatment sludge

    NASA Astrophysics Data System (ADS)

    Vinitnantharat, Soydoa; Kositchaiyong, Sriwilai; Chiarakorn, Siriluk

    2010-06-01

    This paper reports the use of a pellet of adsorbent made from water treatment sludge (S) and acid activated water treatment sludge (SH) for removal of fluoride in the batch equilibration technique. The influence of pH, adsorbent dosage, temperature and effect of other ions were employed to find out the feasibility of acid activated adsorbent to remove fluoride to the permissible concentration of 0.7 mg/L. The results from the adsorption isotherm followed both Langmuir and Freundlich models and the highest fluoride removal was found for adsorbent activated with acetic acid at 2.0 mol/L. The optimum adsorbent dosage was found at 40 g/L, 0.01 mol/L acid activated adsorbent which was able to adsorb fluoride from 10 down to 0.11 mg/L. The adsorption capacity was decreased when the temperature increased. This revealed that the adsorption of fluoride on SH was exothermic. In the presence of nitrate and carbonate ions in the aqueous solution, fluoride removal efficiency of SH decreased from 94.4% to 86.6% and 90.8%, respectively. However, there is no significant effect in the presence of sulfate and chloride ions.

  10. Carbon honeycomb grids for advanced lead-acid batteries. Part I: Proof of concept

    NASA Astrophysics Data System (ADS)

    Kirchev, Angel; Kircheva, Nina; Perrin, Marion

    2011-10-01

    The carbon honeycomb grid is proposed as innovative solution for high energy density lead acid battery. The proof of concept is demonstrated, developing grids suitable for the small capacity, scale of valve-regulated lead acid batteries with 2.5-3 Ah plates. The manufacturing of the grids, includes fast, known and simple processes which can be rescaled for mass production with a minimum, investment costs. The most critical process of green composite carbonisation by heating in inert, atmosphere from 200 to 1000 C takes about 5 h, guaranteeing the low cost of the grids. An AGM-VRLA, cell with prototype positive plate based on the lead-2% tin electroplated carbon honeycomb grid and, conventional negative plates is cycled demonstrating 191 deep cycles. The impedance spectroscopy, measurements indicate the grid performance remains acceptable despite the evolution of the corrosion, processes during the cycling.

  11. Adsorption characteristics of a phenoxy acetic acid herbicide on activated carbon.

    PubMed

    Belmouden, M; Assabbane, A; Ichou, Y A

    2000-06-01

    The adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) by two powdered coal activated carbons was studied in aqueous solution. The modelling of the adsorption equilibrium showed that the adsorption of 2,4-D fitted a Langmuir isotherm. Adsorption was influenced by the activated carbon type, adsorbent concentration and solution characteristics. The adsorption was found to decrease with an increase in pH over the range 1.5-9. Maximum adsorption occurred at pH approximately 2.5, which corresponds to the 2,4-D pKa value. The amount of 2,4-D adsorbed was also found to depend on the NaCl concentration. PMID:11256709

  12. The erosion of carbonate stone by acid rain: Laboratory and field investigations

    USGS Publications Warehouse

    Baedecker, P.A.; Reddy, M.M.

    1993-01-01

    One of the goals of research on the effects of acidic deposition on carbonate stone surfaces is to define the incremental impact of acidic deposition relative to natural weathering processes on the rate of carbonate stone erosion. If rain that impacts carbonate stone surfaces is resident on the surface long enough to approach chemical equilibrium, the incremental effect of hydrogen ion is expected to be small (i.e., 6% for a rain of pH 4.0). Under nonequilibrium (i.e., high flow rate) conditions, kinetic considerations suggest that the incremental effect of hydrogen ion deposition could be quite significant. Field run-off experiments involving the chemical analysis of rain collected from inclined stone slabs have been used to evaluate stone dissolution processes under ambient conditions of wet and dry deposition of acidic species. The stoichiometry of the reaction of stone with hydrogen ion is difficult to define from the field data due to scatter in the data attributed to hydrodynamic effects. Laboratory run-off experiments show that the stoichiometry is best defined by a reaction with H+ in which CO2 is released from the system. The baseline effect caused by water in equilibrium with atmospheric CO2 is identical in the field and in laboratory simulation. The experiments show that the solutions are close enough to equilibrium for the incremental effect of hydrogen ion to be minor (i.e., 24% for marble for a rain of pH 4.0) relative to dissolution due to water and carbonic acid reactions. Stone erosion rates based on physical measurement are approximately double the recession rates that are due to dissolution (estimated from the observed calcium content of the run-off solutions). The difference may reflect the loss of granular material not included in recession estimates based on the run-off data. Neither the field nor the laboratory run-off experiments indicate a pH dependence for the grain-removal process.

  13. Release of nitrous acid and nitrogen dioxide from nitrate photolysis in acidic aqueous solutions.

    PubMed

    Scharko, Nicole K; Berke, Andrew E; Raff, Jonathan D

    2014-10-21

    Nitrate (NO3(-)) is an abundant component of aerosols, boundary layer surface films, and surface water. Photolysis of NO3(-) leads to NO2 and HONO, both of which play important roles in tropospheric ozone and OH production. Field and laboratory studies suggest that NO3¯ photochemistry is a more important source of HONO than once thought, although a mechanistic understanding of the variables controlling this process is lacking. We present results of cavity-enhanced absorption spectroscopy measurements of NO2 and HONO emitted during photodegradation of aqueous NO3(-) under acidic conditions. Nitrous acid is formed in higher quantities at pH 2-4 than expected based on consideration of primary photochemical channels alone. Both experimental and modeled results indicate that the additional HONO is not due to enhanced NO3(-) absorption cross sections or effective quantum yields, but rather to secondary reactions of NO2 in solution. We find that NO2 is more efficiently hydrolyzed in solution when it is generated in situ during NO3(-) photolysis than for the heterogeneous system where mass transfer of gaseous NO2 into bulk solution is prohibitively slow. The presence of nonchromophoric OH scavengers that are naturally present in the environment increases HONO production 4-fold, and therefore play an important role in enhancing daytime HONO formation from NO3(-) photochemistry. PMID:25271384

  14. Fixed bed adsorption of acid dyes onto activated carbon.

    PubMed

    Walker, G M; Weatherley, L R

    1998-01-01

    The context of the study here is the adsorption of acid dyes from wastewater arising from a nylon carpet printing plant which currently receives no treatment. Since nylon is a particularly difficult fibre to dye, acid dyes are required for successful coloration. However, their presence, in high concentrations, in aqueous effluent arising from the plant can create major problems with respect to disposal. A treatment method based on adsorption onto granular activated carbon (GAC F400) in a fixed column configuration is described and breakthrough data of the dyes determined. The breakthrough data were correlated using a model based on liquid and pore diffusion with a good fit of experimental results obtained. Trends in the effective diffusivity used in the model correlated with other authors. A slight decrease in effective diffusivity was found with decrease in particle size and was attributed to interactions between the relatively large molecular sized dye and the microspore structure found in granular activated carbon. PMID:15093338

  15. The Solubility Product of NaUO2PO4.xH2O Determined in Phosphate and Carbonate Solutions

    SciTech Connect

    Felmy, Andrew R.; Xia, Yuanxian; Wang, Zheming

    2005-07-01

    The solubility product of NaUO2PO4.xH2O was determined in phosphate containing solutions at low pCH+ values in the absence of carbonate and at higher pCH+ values in the presence of carbonate. NaUO2PO4.xH2O exhibited very low solubilities (~10-7 M in U) over a broad range of hydrogen ion concentrations, NaNO3 concentrations and in the absence of added carbonate. Time Resolved Laser Fluorescence Spectroscopy (TRLFS) analysis of non-carbonate solutions outside of the acidic region revealed the presence of complex mixtures of aqueous U(VI) hydroxyl or phosphate species and uranium phosphate nanoparticles. The presence of the nanoparticles made it impossible to accurately calculate a solubility product for NaUO2PO4.xH2O in the absence of carbonate and at higher pCH+ values. Therefore in order to increase the concentration of U(VI) in solution and thereby verify the solubility product calculated from the most acidic samples, we systematically introduced know concentrations of carbonate, which resulted in the formation of U(VI) carbonate complexes. Development of an accurate aqueous thermodynamic model for the aqueous U(VI) carbonate complexes then allowed calculation of a solubility product for NaUO2PO4.xH2O in the higher pH samples which was in good agreement with the values for the more acidic samples.

  16. Karstification without carbonic acid: bedrock dissolution by gypsum- driven dedolomitization

    USGS Publications Warehouse

    Bischoff, J.L.; Julia, R.; Shanks, Wayne C.; Rosenbauer, R.J.

    1994-01-01

    The primary karst-forming process at Lake Banyoles is dedolomitization of basement rocks driven by gypsum dissolution. Karstification takes place along the subsurface contact between the gypsiferous Beuda Formation and the dolomitic Perafita Formation. This process is here recognized for the first time to cause karstification on a large scale; this is significant because it proceeds without the addition of soil-generated carbonic acid. -from Authors

  17. Compatible solute influence on nucleic acids: Many questions but few answers

    PubMed Central

    Kurz, Matthias

    2008-01-01

    Compatible solutes are small organic osmolytes including but not limited to sugars, polyols, amino acids, and their derivatives. They are compatible with cell metabolism even at molar concentrations. A variety of organisms synthesize or take up compatible solutes for adaptation to extreme environments. In addition to their protective action on whole cells, compatible solutes display significant effects on biomolecules in vitro. These include stabilization of native protein and nucleic acid structures. They are used as additives in polymerase chain reactions to increase product yield and specificity, but also in other nucleic acid and protein applications. Interactions of compatible solutes with nucleic acids and protein-nucleic acid complexes are much less understood than the corresponding interactions of compatible solutes with proteins. Although we may begin to understand solute/nucleic acid interactions there are only few answers to the many questions we have. I summarize here the current state of knowledge and discuss possible molecular mechanisms and thermodynamics. PMID:18522725

  18. Carbon Isotope Ratios in Crassulacean Acid Metabolism Plants

    PubMed Central

    Szarek, Stan R.; Troughton, John H.

    1976-01-01

    A year round study of photosynthesis and carbon isotope fractionation was conducted with plants of Opuntia phaeacantha Engelm. and Yucca baccata Torr. occurring in natural stands at elevations of 525, 970, 1450 and 1900 m. Plant water potentials and the daytime pattern of 14CO2 photosynthesis were similar for all cacti along the elevational gradient, despite significant differences in temperature regime and soil water status. Carbon isotope ratios of total tissue and soluble extract fractions were relatively constant throughtout the entire year. Additionally, the ?13C values were similar in all plants of the same species along the elevational gradient, i.e. ?12.5 0.86 for O. phaeacantha and ?15.7 0.95 for Y. baccata. The results of this study indicate Crassulacean acid metabolism predominates as the major carbon pathway of these plants, which do not facultatively utilize the reductive pentose phosphate cycle of photosynthesis as the primary carboxylation reaction. PMID:16659680

  19. HYDROGEN CHEMISORPTION ON Pt SINGLE CRYSTAL SURFACES IN ACIDIC SOLUTIONS

    SciTech Connect

    Ross, Jr., Philip N.

    1980-04-01

    Hydrogen chemisorption from dilute acidic solution onto Pt single crystal surfaces was examined using an electrochemical cell directly coupled to LEED/Auger analytical system. No pre-anodization was used prior to observing hydrogen adsorption by cyclic voltammetry so that clean surfaces having the ordered structures indicated by LEED were studied. The problem of contributions from non-ordered parts of the electrode like support wires and edges was solved by using a gold evaporation masking technique. The specific contribution of atomic imperfections to the voltammetry curve was deduced from the ordered and countable imperfections occurring on high Miller index single crystal surfaces that have a stepped structure. The H-Pt bond energy Has found to be structure sensitive, and sensitive both to local site geometry and long range order in the surface. The bond strength was found to vary systematically: n(111)x(100) > (100) > n(111)x(111) > (110) > (111). Distinct states for hydrogen at steps versus hydrogen on terraces could be distinguished. The (110) surface is shown to be a (111) vicinal, probably the [3(111) x 2(111)] microfacetted surface. The zero coverage heat of adsorption on the well-ordered (111) surface (48 kJ/mol) in solutions is the same as the value reported by Ertl and co-workers for adsorption on a (111) surface in vacuum. Adsorption Isotherms for hydrogen on the (111) and (100) surfaces is adequately fit by the classical model for immobile adsorption at single sites with nearest neighbor repulsive interaction.

  20. Adsorption of naphthenic acids on high surface area activated carbons.

    PubMed

    Iranmanesh, Sobhan; Harding, Thomas; Abedi, Jalal; Seyedeyn-Azad, Fakhry; Layzell, David B

    2014-01-01

    In oil sands mining extraction, water is an essential component; however, the processed water becomes contaminated through contact with the bitumen at high temperature, and a portion of it cannot be recycled and ends up in tailing ponds. The removal of naphthenic acids (NAs) from tailing pond water is crucial, as they are corrosive and toxic and provide a substrate for microbial activity that can give rise to methane, which is a potent greenhouse gas. In this study, the conversion of sawdust into an activated carbon (AC) that could be used to remove NAs from tailings water was studied. After producing biochar from sawdust by a slow-pyrolysis process, the biochar was physically activated using carbon dioxide (CO2) over a range of temperatures or prior to producing biochar, and the sawdust was chemically activated using phosphoric acid (H3PO4). The physically activated carbon had a lower surface area per gram than the chemically activated carbon. The physically produced ACs had a lower surface area per gram than chemically produced AC. In the adsorption tests with NAs, up to 35mg of NAs was removed from the water per gram of AC. The chemically treated ACs showed better uptake, which can be attributed to its higher surface area and increased mesopore size when compared with the physically treated AC. Both the chemically produced and physically produced AC provided better uptake than the commercially AC. PMID:24766592

  1. EXAFS Study on the Reactions Between Iron And Fulvic Acid in Acid Aqueous Solutions

    SciTech Connect

    Schaik, J.W.J.van; Persson, I.; Kleja, D.B.; Gustafsson, J.P.

    2009-05-26

    Iron(III) competes with trace metals for binding sites on organic ligands. We used X-ray absorption fine structure (EXAFS) spectroscopy to determine the binding mode and oxidation state of iron in solutions initially containing only iron(III) and fulvic acid at pHs 2 and 4. EXAFS spectra were recorded at different times after sample preparation. Iron was octahedrally configured with inner-sphere Fe-O interactions at 1.98-2.10 {angstrom}, depending on the oxidation state of iron. Iron(III) formed complexes with fulvic acid within 15 min. Iron(III) was reduced to iron(II) with time at pH 2, whereas no significant reduction occurred at pH 4. No signs of dimeric/trimeric hydrolysis products were found in any of the solution samples (<0.45 {mu}m). However, the isolated precipitate of the pH 2 sample (>0.45 {mu}m) showed Fe{hor_ellipsis}Fe distances, indicating the presence of tightly packed iron(III) trimers and/or clusters of corner-sharing octahedra. It is suggested that the binding mode of iron(III) to fulvic acid at low pH may be phase-dependent: in solution mononuclear complexes predominate, whereas in the solid phase hydrolyzed polynuclear iron(III) complexes form, even at very low pH values. The observed pH dependence of iron(III) reduction was consistent with expected results based on thermodynamic calculations for model ligands.

  2. Large-scale production of anhydrous nitric acid and nitric acid solutions of dinitrogen pentoxide

    DOEpatents

    Harrar, Jackson E. (Castro Valley, CA); Quong, Roland (Oakland, CA); Rigdon, Lester P. (Livermore, CA); McGuire, Raymond R. (Brentwood, CA)

    2001-01-01

    A method and apparatus are disclosed for a large scale, electrochemical production of anhydrous nitric acid and N.sub.2 O.sub.5. The method includes oxidizing a solution of N.sub.2 O.sub.4 /aqueous-HNO.sub.3 at the anode, while reducing aqueous HNO.sub.3 at the cathode, in a flow electrolyzer constructed of special materials. N.sub.2 O.sub.4 is produced at the cathode and may be separated and recycled as a feedstock for use in the anolyte. The process is controlled by regulating the electrolysis current until the desired products are obtained. The chemical compositions of the anolyte and catholyte are monitored by measurement of the solution density and the concentrations of N.sub.2 O.sub.4.

  3. Removal of nickel(II) from aqueous solution using Citrus Limettioides peel and seed carbon.

    PubMed

    Sudha, R; Srinivasan, K; Premkumar, P

    2015-07-01

    The agricultural wastes like Citrus Limettioides peel and seed to be suitable precursor for the preparation of carbon [Citrus Limettioides peel carbon (CLPC) and seed carbon (CLSC)] has been explored in the present work, utilizing sulfuric acid as the activating agent. Adsorption studies were performed by varying contact time, solution pH, adsorbent dose and temperature. The equilibrium time for Ni(II) ions was determined as 4h and optimal pH was 4-7. Surface morphology and functionality of the CLPC and CLSC were characterized by SEM, EDX and FT-IR. The experimental data were analysed using the Freundlich, Langmuir, Temkin, Redlich-Peterson, Sips and Dubinin-Radushkevich adsorption isotherm equations using nonlinear regression analysis. Equilibrium data were found to fit well in the Langmuir isotherm, which confirmed the monolayer coverage of Ni(II) ions. The Langmuir monolayer adsorption capacity of CLPC and CLSC was found to be 38.46 and 35.54 mg/g. The thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic in nature. The kinetic data followed pseudo-second order model with film diffusion process. The adsorbents were tested with Ni(II) plating wastewater in connection with the reuse and selectivity of the adsorbents. PMID:25841067

  4. Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Michelsen, Rebecca R.; Ashbourn, Samatha F. M.; Rammer, Thomas A.; Golden, David M.

    2005-01-01

    Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

  5. On the black carbon problem and its solutions

    NASA Astrophysics Data System (ADS)

    Jacobson, M. Z.

    2010-12-01

    Black carbon (BC) warms air temperatures in at least seven major ways: (a) directly absorbing downward solar radiation, (b) absorbing upward reflected solar radiation when it is situated above bright surfaces, such as snow, sea ice, and clouds, (c) absorbing some infrared radiation, (d) absorbing additional solar and infrared radiation upon obtaining a coating, (e) absorbing radiation multiply reflected within clouds when situated interstitially between cloud drops, (f) absorbing additional radiation when serving as CCN or scavenged inclusions within cloud drops, and (g) absorbing solar radiation when deposited on snow and sea ice, reducing the albedos of both. Modeling of the climate effects of BC requires treatment of all these processes in detail. In particular, treatment of BC absorption interstitially between cloud drops and from multiply-dispersed cloud drop BC inclusions must be treated simultaneously with treatment of cloud indirect effects to determine the net effects of BC on cloud properties. Here, results from several simulations of the effects of BC from fossil fuel and biofuel sources on global and regional climate and air pollution health are summarized. The simulations account for all the processes mentioned. Results are found to be statistically significant relative to chaotic variability in the climate system. Over time and in steady state, fossil-fuel soot plus biofuel soot are found to enhance warming more than methane. The sum of the soots causes less steady-state warming but more short term warming than does carbon dioxide. Thus eliminating soot emissions from both sources may be the fastest method of reducing rapid climate warming and possibly the only method of saving the Arctic ice. Eliminating such emissions may also reduce over 1.5 million deaths worldwide, particularly in developing countries. Short term mitigation options include the targeting of fossil-fuel and biofuel BC sources with particle traps, new stove technologies, and rural electrification. However, the real solution, to be implemented over a 20-40 year period is complete conversion of the combustion infrastructure to electricity and electrolytic hydrogen, where the electricity is all produced by near-zero emitting wind, water, and solar (WWS) based energy technologies. Such a conversion would reduce BC and greenhouse gases simultaneously with cooling aerosol particles. This would ramp down the presence of both warming and cooling agents, but still cause net reduction of global warming, while reducing devastating health impacts that are occurring from both warming and cooling aerosols.

  6. Method to detect minimal amounts of calcium dissolved in acidic solutions.

    PubMed

    Attin, T; Becker, K; Hannig, C; Buchalla, W; Hilgers, R

    2005-01-01

    The study describes the application of the Arsenazo III method for detection of minimal amounts of calcium 12.4-49.4 micromol/l in different acidic solutions (hydrochloric acid, oxalic acid, maleic acid, phosphoric acid, tartaric acid, citric acid, lactic acid and acetic acid) adjusted to pH 2.0, 2.3 and 3.0. A mixture of the respective calcium concentrations with distilled water served as control. The experiments were run with ten repeats in series. Assessment of intra- and interassay coefficient of variation, and lower limit of quantification revealed that depending on the acid used, the Arsenazo III method is a reliable tool to quantify minimal calcium contents in acidic solutions. PMID:16110217

  7. Suitability of a malachite green procedure to detect minimal amounts of phosphate dissolved in acidic solutions.

    PubMed

    Attin, T; Becker, K; Hannig, C; Buchalla, W; Wiegand, A

    2005-09-01

    The study describes the suitability of a colorimetric method (malachite green procedure) for detection of minimal amounts of phosphate (7.3-29.1 micromol/L) in different acidic solutions (hydrochloric acid, oxalic acid, maleic acid, perchloric acid, tartaric acid, citric acid, lactic acid and acetic acid) adjusted to pH 2.0. A mixture of the respective phosphate concentrations with distilled water served as control. The experiments were run with ten repeats in series. Assessment of intra- and interassay coefficient of variation and lower limit of quantification revealed that depending on the acid used, the applied method is a reliable and suitable tool to detect and quantify minimal phosphate contents in small samples of acidic solutions that have the potential to cause erosive dental lesions. PMID:15912408

  8. Photosensitized Reduction of Carbon Dioxide in Solution Using Noble-Metal Clusters for Electron Transfer

    NASA Astrophysics Data System (ADS)

    Toshima, Naoki; Yamaji, Yumi; Teranishi, Toshiharu; Yonezawa, Tetsu

    1995-03-01

    Carbon dioxide was reduced to methane by visible-light irradiation of a solution composed of tris(bipyridine)ruthenium(III) as photosensitizer, ethylenediaminetetraacetic acid disodium salt as sacrificial reagent, methyl viologen as electron relay, and a colloidal dispersion of polymer-protected noble-metal clusters, prepared by alcohol-reduction, as catalyst. Among the noble-metal clusters examined, Pt clusters showed the highest activity for the formation of methane as well as hydrogen. In order to improve the activity, oxidized clusters and bimetallic clusters were also applied. For example, the CH4 yield in 3-h irradiation increased from 51 x 10-3 ?mol with unoxidized Pt clusters to 72 x 10-3 ?mol with partially oxidized ones. In the case of Pt/Ru bimetalic systems, the improvement of the catalytic activity by air treatment was much greater than in case of monometallic clusters.

  9. Amino acids of the Murchison meteorite. II - Five carbon acyclic primary beta-, gamma-, and delta-amino alkanoic acids

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Pizzarello, S.; Yuen, G. U.

    1985-01-01

    The five-carbon acyclic primary beta, gamma, and delta amino alkanoic acids of the Murchison meteorite are studied using gas chromatography-mass spectrometry and ion exchange chromatography. The chromatograms reveal that alpha is the most abundant monoamino alkanoic acid followed by gamma and beta, and an exponential increase in the amount of amino acid is observed as the carbon number increases in the homologous series. The influence of frictional heating, spontaneous thermal decomposition, and radiation of the synthesis of amino acids is examined. The data obtained support an amino acid synthesis process involving random combination of single-carbon precursors.

  10. Poly(lactic acid)/Carbon Nanotube Fibers as Novel Platforms for Glucose Biosensors

    PubMed Central

    Oliveira, Juliano Elvis; Mattoso, Luiz Henrique Capparelli; Medeiros, Eliton Souto; Zucolotto, Valtencir

    2012-01-01

    The focus of this paper is the development and investigation of properties of new nanostructured architecture for biosensors applications. Highly porous nanocomposite fibers were developed for use as active materials in biosensors. The nanocomposites comprised poly(lactic acid)(PLA)/multi-walled carbon nanotube (MWCNT) fibers obtained via solution-blow spinning onto indium tin oxide (ITO) electrodes. The electrocatalytic properties of nanocomposite-modified ITO electrodes were investigated toward hydrogen peroxide (H2O2) detection. We investigated the effect of carbon nanotube concentration and the time deposition of fibers on the sensors properties, viz., sensitivity and limit of detection. Cyclic voltammetry experiments revealed that the nanocomposite-modified electrodes displayed enhanced activity in the electrochemical reduction of H2O2, which offers a number of attractive features to be explored in development of an amperometric biosensor. Glucose oxidase (GOD) was further immobilized by drop coating on an optimized ITO electrode covered by poly(lactic acid)/carbon nanotube nanofibrous mats. The optimum biosensor response was linear up to 800 mM of glucose with a sensitivity of 358 nAmM?1 and a Michaelis-Menten constant (KM) of 4.3 mM. These results demonstrate that the solution blow spun nanocomposite fibers have great potential for application as amperometric biosensors due to their high surface to volume ratio, high porosity and permeability of the substrate. The latter features may significantly enhance the field of glucose biosensors. PMID:25585633

  11. Uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide.

    PubMed

    Liu, Ze; Ge, Maofa; Wang, Weigang

    2012-01-01

    Multiphase acid-catalyzed oxidation by hydrogen peroxide has been suggested to be a potential route to secondary organic aerosol formation from isoprene and its gas-phase oxidation products, but the lack of kinetics data significantly limited the evaluation of this process in the atmosphere. Here we report the first measurement of the uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide. Isoprene cannot readily partition into the solution because of its high volatility and low solubility, which hinders its further liquid-phase oxidation. Both methacrylic acid and methyl methacrylate can enter the solutions and be oxidized by hydrogen peroxide, and steady-state uptake was observed with the acidity of solution above 30 wt.% and 70 wt.%, respectively. The steady-state uptake coefficient of methacrylic acid is much larger than that of methyl methacrylate for a solution with same acidity. These observations can be explained by the different reactivity of these two compounds caused by the different electron-withdrawing conjugation between carboxyl and ester groups. The atmospheric lifetimes were estimated based on the calculated steady-state uptake coefficients. These results demonstrate that the multiphase acid-catalyzed oxidation of methacrylic acid plays a role in secondary organic aerosol formation, but for isoprene and methyl methacrylate, this process is not important in the troposphere. PMID:23534228

  12. Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons

    PubMed Central

    Moreno-Pirajn, Juan Carlos; Blanco, Diego; Giraldo, Liliana

    2012-01-01

    An activated carbon, CarbochemTMPS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 Jg?1 for catechol aqueous solutions in a range of 20 at 1500 mgL?1. PMID:22312237

  13. Organic compounds in olive mill wastewater and in solutions resulting from hydrothermal carbonization of the wastewater.

    PubMed

    Poerschmann, J; Weiner, B; Baskyr, I

    2013-09-01

    Organic components in olive mill wastewater (OMW) were analyzed by exhaustive solvent extraction of the lyophilisate followed by pre-chromatographic derivatization techniques and GC/MS-analysis of the extracts. Simple biophenols including tyrosol (Tyr), hydroxytyrosol (OH-Tyr) and homovanillic alcohol as well as complex biophenols including decarbomethoxy ligostride aglycon and decarbomethoxy oleuropein aglycon proved most abundant analytes. Hydroxylated benzoic and cinnamic acids are less abundant, which may indicate a humification process to have occurred. The pattern of organic components obtained from native OMW was compared with that obtained from hydrothermal carbonization (HTC) of the waste product. Former results provided strong evidence that HTC of OMW at 220C for 14h results in an almost complete hydrolysis of complex aglycons. However, simple biophenols were not decomposed on hydrothermal treatment any further. Phenol and benzenediols as well as low molecular weight organic acids proved most abundant analytes which were generated due to HTC. Similarly to aglycons, lipids including most abundant acylglycerines and less abundant wax esters were subjected almost quantitatively to hydrolysis under hydrothermal conditions. Fatty acids (FAs) released from lipids were further decomposed. The pathways of volatile analytes in both native OMW and aqueous HTC solutions were studied by solventless headspace-Solid Phase Micro Extraction. Basically, a wide array low molecular alcohols and ketones occurring in native OMW survived the HTC process. PMID:23648325

  14. Hydrothermal Carbonization: a feasible solution to convert biomass to soil?

    NASA Astrophysics Data System (ADS)

    Tesch, Walter; Tesch, Petra; Pfeifer, Christoph

    2013-04-01

    The erosion of fertile soil is a severe problem arising right after peak oil (Myers 1996). That this issue is not only a problem of arid countries is shown by the fact that even the European Commission defined certain milestones to address the problem of soil erosion in Europe (European Commission 2011). The application of bio-char produced by torrefaction or pyrolysis for the remediation, revegetation and restoration of depleted soils started to gain momentum recently (Rillig 2010, Lehmann 2011, Beesley 2011). Hydrothermal carbonization (HTC) is a promising thermo-chemical process that can be applied to convert organic feedstock into fertile soil and water, two resources which are of high value in regions being vulnerable to erosion. The great advantage of HTC is that organic feedstock (e.g. organic waste) can be used without any special pretreatment (e.g. drying) and so far no restrictions have been found regarding the composition of the organic matter. By applying HTC the organic material is processed along a defined pathway in the Van Krevelen plot (Behrendt 2006). By stopping the process at an early stage a nutritious rich material can be obtained, which is known to be similar to terra preta. Considering that HTC-coal is rich in functional groups and can be derived from the process under "wet" conditions, it can be expected that it shall allow soil bacteria to settle more easily compared to the bio-char derived by torrefaction or pyrolysis. In addition, up to 10 tons process water per ton organic waste can be gained (Vorlop 2009). Thus, as organic waste, loss of fertile soil and water scarcity becomes a serious issue within the European Union, hydrothermal carbonization can provide a feasible solution to address these issues of our near future. The presentation reviews the different types of feedstock investigated for the HTC-Process so far and gives an overview on the current stage of development of this technology. References Beesley L., Moreno-Jimnez E., Gomez-Eyles J.L., Harris H., Robinson B., Sizmur T.: A review of biochars' potential role in the remediation, revegetation and restoration of contaminated soils. Environmental Pollution (159), p. 3269 - 3282, 2011. Behrendt F.: Direktverflssigung von Biomasse - Reaktionsmechanismen und Produktverteilungen Institut fr Energietechnik, Technische Universitt Berlin Studie im Auftrag der Bundesanstalt fr Landwirtschaft und Ernhrung; Projektnummer 114-50-10-0337/05-B, 2006. European Commission: "Roadmap to a Resource Efficient Europe", COM(2011) 571. Lehmann J., Rillig M.C., Thies J., Masiello C.A., Hockaday W.C., Crowley D.: Biochar effects on soil biota - A review, Soil Biology & Biochemistry, p. 1-25, 2011. Myers Norman: "Environmental services of biodiversity", Proc. Natl. Acad. Sci. USA Vol 93, pp. 2764 - 2769, 1996. Rillig M.C., Wagner M., Salem M., Antunes P.M., George C., Ramke H.G., Titirici M.M., Antonietti M.: Material derived from hydrothermal carbonization: effects on plant growth and arbuscular mycorrhiza. Applied Soil Ecology (45), p. 238 - 242, 2010. Vorlop K.D., Schuchardt F., Pre U.: Hydrothermale Carbonisierung Analyse und Ausblicke. FNR-Fachgesprch, Berlin, 2009.

  15. Structure of electrolyte solutions sorbed in carbon nanospaces, studied by the replica RISM theory.

    PubMed

    Tanimura, A; Kovalenko, A; Hirata, F

    2007-01-30

    The replica RISM theory is used to investigate the structure of electrolyte solutions confined in carbonized polyvinylidene chloride (PVDC) nanoporous material, compared to bulk electrolyte solution. Comparisons are made between the models of electrolyte solution sorbed in the carbonized PVDC material and a single carbon nanosphere in bulk electrolyte solution. Particular attention is paid to the chemical potential balance between the species of the sorbed electrolyte solution and the bulk solution in contact with the nanoporous material. As a result of the strong hydrophobicity of the carbonized PVDC material in the absence of activating chemical groups, the densities of water and ions sorbed in the material are remarkably low compared to those in the ambient bulk solution. The interaction between water molecules and cations becomes strong in nanospaces. It turns out that, in carbon nanopores, a cation adsorbed at the carbon surface is fully surrounded by the hydration shell of water molecules which separates the cation and the surface. Distinctively, an anion is adsorbed in direct contact with the carbon surface, which squeezes a part of its hydration shell out. The tendency increases toward smaller cations, which are characterized as "positive hydration" ions. In the bulk, cations are not hydrated so strongly and behave similarly to anions. The results suggest that the specific capacitance of an electric double-layer supercapacitor with nanoporous electrodes is intimately related to the solvation structure of electrolyte solution sorbed in nanopores, which is affected by the microscopic structure of the nanoporous electrode. PMID:17241081

  16. Effect of solution conductivity and electrode shape on the deposition of carbon nanotubes from solution using dielectrophoresis.

    PubMed

    Naieni, A Kashefian; Nojeh, A

    2012-12-14

    Dielectrophoresis (DEP) is a popular technique for fabricating carbon nanotube (CNT) devices. The electric current passing through the solution during DEP creates a temperature gradient, which results in electrothermal fluid flow because of the presence of the electric field. CNT solutions prepared with various methods can have different conductivities and the motion of the solution because of the electrothermal phenomenon can affect the DEP deposition differently in each case. We investigated the effect of this movement in solutions with various levels of conductivity through experiments as well as numerical modeling. Our results show that electrothermal motion in the solution can alter the deposition pattern of the nanotubes drastically for high conductivity solutions, while DEP remains the dominant force when a low conductivity (surfactant-free) solution is used. The extent of effectiveness of each force is discussed in the various cases and the fluid movement model is investigated using two- and three-dimensional finite element simulations. PMID:23165429

  17. Raman spectroscopic study of the conformation of dicarboxylic acid salts in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Fukushima, Kunio; Watanabe, Toshiaki; Umemura, Matome

    1986-08-01

    It is already known that the molecules of long chain monocarboxylic acid salts have a tendency to form micelles in aqueous solutions, the molecular chain taking the all- trans zigzag structure. However it is considered difficult for dicarboxylic acid salts to adopt the same structure as the monocarboxylic acid salts as they have two carboxyl groups, one on each end of the molecular chain. Therefore, a special structure is expected to exist for dicarboxylic acid salts in aqueous solution. In order to examine this, Raman spectra of suberic acid salt and azelaic acid salt in aqueous solution were measured and the normal vibrational calculation carried out, showing that dicarboxylic acid salts have a helical structure in aqueous solution.

  18. Isothermal heat measurements of TBP-nitric acid solutions

    SciTech Connect

    Smith, J.R.; Cavin, W.S.

    1994-12-16

    Net heats of reaction were measured in an isothermal calorimeter for both single phase (organic) and two phase (organic and aqueous) TBP/HNO{sub 3} reacting solutions at temperatures above 100 C. The oxidation rate constant was determined to be 5.4E-4 min{sup {minus}1} at 110 C for an open ``vented`` system as compared to 1.33 E-3 min{sup {minus}1} in the closed system. The heat released per unit material oxidized was also reduced. The oxidation in both phases was found to be first order in nitric acid and pseudo-zero order in butylnitrate and water. The hydrolysis (esterification) rate constant determined by Nichols` (1.33E-3 min{sup {minus}1}) fit the experimental data from this work well. Forced evaporation of the volatile components by the product gases from oxidation resulted in a cooling mechanism which more than balanced the heat from the oxidation reaction in the two-phased systems. Rate expressions were derived and rate constants determined for both the single and two phase systems. An approximating mathematical model was developed to fit the experimental data and to extrapolate beyond the experimental conditions. This model shows that one foot of ``reacting`` 14.3M HNO{sub 3} aqueous phase solution at 121 C will transport sufficient water to the organic phase to replace evaporative losses, maintaining endothermicity, for organic layers up to 12.2 + 6.0 feet deep. If the pressure in a reacting system is allowed to increase due to insufficient venting the temperature of the organic phase would increase in temperature to reach a new equilibrium. The rate of oxidation would increase not only due to the increase in temperature but also from the increased concentration of dissolved HNO{sub 3} reduction products. Another important factor is that the cooling system described in this work becomes less effective as the total pressure increases. These factors probably contributed to the explosion at Tomsk.

  19. Carbon dioxide generated from carbonates and acids for sampling blood-feeding arthropods.

    PubMed

    Burkett-Cadena, Nathan D; Blosser, Erik M; Young, Ryan M; To, Laurent D; Unnasch, Thomas R

    2015-09-01

    Carbon dioxide (CO2) is utilized to attract mosquitoes and other blood-feeding arthropods to traps around the world. Commercial forms of CO2 (e.g., dry ice and compressed gas) are often unavailable or extremely expensive in developing nations, where vector surveillance is essential to make life-saving decisions. We developed and tested inexpensive and reproducible methods of CO2 production from the combination of acids and carbonates, ranging from very basic (crushed seashells and vinegar) to relatively elaborate (a device that controls the timing of the acid-carbonate reaction and extends the reaction over several hours). When utilized with mosquito traps in Florida, USA and black fly traps in Region des Cascades, Burkina Faso, these carbonate-acid CO2 sources attracted significantly greater numbers of both vector groups, than did unbaited traps. CO2 was generated for more than four hours at levels sufficient to attract vectors over the entire period. The utility of this simple methodology in developing nations should be further evaluated. PMID:26103427

  20. Ozonation of naphthalenesulphonic acid in the aqueous phase in the presence of basic activated carbons.

    PubMed

    Rivera-Utrilla, J; Snchez-Polo, M

    2004-10-12

    The present study aimed to explore the possibility of increasing the purification efficacy of ozone in the removal of high-toxicity contaminants by using carbons of basic character and to analyze the mechanism involved in this process. These carbons were prepared by treating a commercial activated carbon (Witco, W) with ammonia (W-A), ammonium carbonate (W-C), or urea (W-U), under high pressure and temperature. The ammonia and carbonate treatments slightly increased the mesoporosity and, to a greater degree, the macroporosity of carbon W, whereas the urea treatment produced an increase in the porosity across the whole range of pore sizes. In addition, treatment of the activated carbon with these nitrogenating agents produced a marked change in the chemical nature of its surface. Thus, according to the pH of the point of zero charge (pHPZC) values obtained for each sample, carbon W was neutral (pHPZC = 7.12), but the treated carbons were basic, especially carbon W-U (pHPZC = 8.85). This basicity results from an increased concentration of basic oxygenated and nitrogenated surface functional groups, as confirmed by the results of elemental and XPS analyses. An increase in the degradation of 1,3,6-naphthalenetrisulfonic acid was observed when the activated carbon samples were added to the system. This degradation was especially enhanced in the presence of carbon W-U. The increased NTS degradation rate in the presence of the activated carbon is due to an increased concentration of highly reactive radicals in the system. When the catalytic activity of the activated carbon samples was related to their chemical and textural characteristics, it was found that: (i) The catalytic activity increased with an increase in the surface basicity. Interestingly, in the sample with greatest catalytic activity in NTS ozonation, carbon W-U, most of the nitrogenated surface groups introduced were pyrrol groups. These groups increase the electronic density of the basal plane of the activated carbon, thereby enhancing the reduction of ozone on the surface and the generation of highly reactive radicals in the system. (ii) The greater catalytic activity of carbon W-U may also be partly related to its greater surface area and higher volume of mesopores and macropores; these large pores facilitate access of the ozone to the surface active centers of the carbon, increasing its catalytic activity. The presence of the activated carbon samples during NTS ozonation also favored the removal of total organic carbon present in the solution, due to (a) transformation of organic matter into CO2 through the generation of highly reactive species catalyzed by the presence of the activated carbons (catalytic contribution) and (b) adsorption of NTS oxidation byproducts on the activated carbon (adsorptive contribution). The results obtained show that activated carbons treated with nitrogenating agents are very promising catalysts for application in the ozonation of aromatic compounds. PMID:15461509

  1. Preparation of intercalation compounds of carbon fibers through electrolysis using phosphoric acid electrolyte and their exfoliation

    NASA Astrophysics Data System (ADS)

    Toyoda, Masahiro; Yoshinaga, Aya; Amao, Yutaka; Takagi, Hideyuki; Soneda, Yasushi; Inagaki, Michio

    2006-05-01

    Preparation of intercalation compounds using H3PO4 electrolyte solution in mesophase-pitch-based carbon fibers successfully carried out by electrolysis in less than 10 mol/dm3 of its electrolyte solution. Structural changes with preparation of intercalation compounds of carbon fibers were confirmed by a peak appeared around 2?=8 observed after electrolysis, which corresponds to an interlayer spacing of about 0.9 nm through XRD pattern (anticathode: Cu K?). This new peak was reasonably supposed to be due to the intercalation into interspacing of carbon layers. Suitable synthesis condition of the intercalation compounds was determined to be the concentration of electrolyte of 5 mol/dm3 at the electrolysis. It was also confirmed by morphology changes through SEM, that is carbon fibers, which treated low electrolyte concentration synthesized the intercalation compounds easily, and then it revealed markedly morphology changes such as fibrils. It could become exfoliation as well as them treated by other acid treatment through rapid heat-treatment. The formation of graphite oxide was suggested when the kind of intercalate was analyzed with elementary and TPD analysis.

  2. Colloidal methods for the fabrication of carbon nanotube-manganese dioxide and carbon nanotube-polypyrrole composites using bile acids.

    PubMed

    Ata, M S; Zhitomirsky, I

    2015-09-15

    Nature inspired strategies have been developed for the colloidal processing of advanced composites for supercapacitor applications. New approach was based on the use of commercially available bile acid salts, such as sodium cholate (ChNa) and taurocholic acid sodium salt (TChNa). It was demonstrated that cholic acid (ChH) films can be obtained by electrophoretic deposition (EPD) from ChNa solutions. The analysis of deposition yield, quartz crystal microbalance and cyclic voltammetry data provided an insight into the anodic deposition mechanism. The outstanding suspension stability of multiwalled carbon nanotubes (MWCNT), achieved using bile acids as anionic dispersants, allowed the fabrication of MWCNT films by EPD. The use of ChNa for EPD offered advantages of binding and film forming properties of this material. Composite MnO2-MWCNT films, prepared using ChNa as a dispersant and film forming agent for EPD, showed promising capacitive behavior. In another colloidal strategy, TChNa was used as a dispersant for MWCNT for the fabrication of polypyrrole (PPy) coated MWCNT. The use of PPy coated MWCNT allowed the fabrication of electrodes with high active mass loading, high capacitance and excellent capacitance retention at high charge-discharge rates. PMID:26001135

  3. Maintenance Carbon Cycle in Crassulacean Acid Metabolism Plant Leaves 1

    PubMed Central

    Kenyon, William H.; Severson, Ray F.; Black, Clanton C.

    1985-01-01

    The reciprocal relationship between diurnal changes in organic acid and storage carbohydrate was examined in the leaves of three Crassulacean acid metabolism plants. It was found that depletion of leaf hexoses at night was sufficient to account quantitatively for increase in malate in Ananas comosus but not in Sedum telephium or Kalancho daigremontiana. Fructose and to a lesser extent glucose underwent the largest changes. Glucose levels in S. telephium leaves oscillated diurnally but were not reciprocally related to malate fluctuations. Analysis of isolated protoplasts and vacuoles from leaves of A. comosus and S. telephium revealed that vacuoles contain a large percentage (>50%) of the protoplast glucose, fructose and malate, citrate, isocitrate, ascorbate and succinate. Sucrose, a major constituent of intact leaves, was not detectable or was at extremely low levels in protoplasts and vacuoles from both plants. In isolated vacuoles from both A. comosus and S. telephium, hexose levels decreased at night at the same time malate increased. Only in A. comosus, however, could hexose metabolism account for a significant amount of the nocturnal increase in malate. We conclude that, in A. comosus, soluble sugars are part of the daily maintenance carbon cycle and that the vacuole plays a dynamic role in the diurnal carbon assimilation cycle of this Crassulacean acid metabolism plant. PMID:16664005

  4. Activated carbon enhanced ozonation of oxalate attributed to HO oxidation in bulk solution and surface oxidation: effect of activated carbon dosage and pH.

    PubMed

    Xing, Linlin; Xie, Yongbing; Minakata, Daisuke; Cao, Hongbin; Xiao, Jiadong; Zhang, Yi; Crittenden, John C

    2014-10-01

    Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon (AC) in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals (HO) in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol (tBA) with low dosages of AC, while it was hardly affected by tBA when the AC dosage was greater than 0.3g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05g/L, but it did not work when the AC dosage was no less than 0.1g/L. These observations indicate that HO in bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HO oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HO oxidation in basic bulk solution. A mechanism involving both HO oxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate. PMID:25288554

  5. Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

    PubMed Central

    Wang, Huiying; Liu, Mingyue; Hu, Xinxi; Li, Mei; Xiong, Xingyao

    2013-01-01

    A versatile strategy for electrochemical determination of glycoalkaloids (GAs) was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA) modified glassy carbon electrode. PBA reacts with ?-solanine and ?-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 ?M to 28 ?M and the detection limit was 0.3 ?M. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors. PMID:24287539

  6. 49 CFR 173.229 - Chloric acid solution or chlorine dioxide hydrate, frozen.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Chloric acid solution or chlorine dioxide hydrate, frozen. 173.229 Section 173.229 Transportation Other Regulations Relating to Transportation PIPELINE AND... Than Class 1 and Class 7 173.229 Chloric acid solution or chlorine dioxide hydrate, frozen. When...

  7. 49 CFR 173.229 - Chloric acid solution or chlorine dioxide hydrate, frozen.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Chloric acid solution or chlorine dioxide hydrate, frozen. 173.229 Section 173.229 Transportation Other Regulations Relating to Transportation PIPELINE AND... Than Class 1 and Class 7 173.229 Chloric acid solution or chlorine dioxide hydrate, frozen. When...

  8. 49 CFR 173.229 - Chloric acid solution or chlorine dioxide hydrate, frozen.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Chloric acid solution or chlorine dioxide hydrate, frozen. 173.229 Section 173.229 Transportation Other Regulations Relating to Transportation PIPELINE AND... Than Class 1 and Class 7 173.229 Chloric acid solution or chlorine dioxide hydrate, frozen. When...

  9. 49 CFR 173.229 - Chloric acid solution or chlorine dioxide hydrate, frozen.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Chloric acid solution or chlorine dioxide hydrate, frozen. 173.229 Section 173.229 Transportation Other Regulations Relating to Transportation PIPELINE AND... Than Class 1 and Class 7 173.229 Chloric acid solution or chlorine dioxide hydrate, frozen. When...

  10. Hydrogen Generation During the Corrosion of Carbon Steel in Oxalic Acid

    SciTech Connect

    WIERSMA, BRUCEJ.

    2004-08-01

    A literature review of the corrosion mechanism for carbon steel in oxalic acid was performed to determine the ratio of moles of iron corroded to moles of hydrogen evolved during the corrosion of iron in oxalic acid. The theory of corrosion of carbon steel in oxalic acid and experimental work were reviewed. It was concluded that the maximum ratio of moles of hydrogen evolved to moles of iron corroded is 1:1. This ratio would be observed in a de-aerated environment. If oxygen or other oxidizing species are present, the ratio could be much less than 1:1. Testing would be necessary to determine how much less than 1:1 the ratio might be. Although the ratio of hydrogen evolution to iron corroded will not exceed 1:1, the total amount of hydrogen evolved can be influenced by such things as a decrease in the exposed surface area, suppression of hydrogen generation by gamma radiation, the presence of corrosion products on steel surface, etc. These and other variables present during chemical cleaning operations of the waste tank have not been examined by the tests reported in the literature i.e., the tests have focused on clean corrosion coupons in oxalic acid solutions. It is expected that most of these variables would reduce the total amount of hydrogen evolved. Further testing would need to be performed to quantify the reduction in hydrogen generation rate associated with these variables.

  11. Elusive Carbonic Acid: A Determination of its Vapor Pressures and Enthalpy of Sublimation for Mars and Beyond

    NASA Astrophysics Data System (ADS)

    Lewis, Ariel S.; Hudson, R. L.; Moore, M. H.; Cooper, P. D.

    2007-10-01

    Solid H2O and CO2 are present on Mars, some Galilean satellites, comets, and interstellar ices. Laboratory work on frozen H2O-CO2 mixtures shows that they produce H2CO3, carbonic acid, when exposed to either high-energy radiation (keV, MeV) or vacuum-UV photons (eV). While this molecule readily dissociates at 298 K, its stability below about 250 K suggests that it should exist in extraterrestrial environments. Unfortunately, little is known of solid-phase carbonic acid at temperatures relevant to planetary science. Recently we have studied some of the thermodynamic properties of carbonic acid. To synthesize this compound, we first injected a KHCO3 solution onto a substrate, pre-cooled to 15 K, to make a thin icy film. On top of this, an HBr solution was injected to make a second icy film. The substrate then was heated to about 200 K to initiate an acid-base reaction between KHCO3 and HBr, and to sublime the water present into a vacuum chamber. The resulting formation of carbonic acid was confirmed by recording infrared (IR) spectra of the samples before and after warming. The ices then were further heated to 240 - 255 K, and spectra recorded over time. Decreases in carbonic acid's IR bands near 1300 and 1500 cm-1 allowed the vapor pressure of the compound to be measured at several temperatures, from which an enthalpy of sublimation was determined. Comparisons were made to the heats of sublimation for formic and acetic acids, both those measured by us and those already in the literature. This work was supported by the Mars Fundamental Research Program and Goddard Center for Astrobiology. The first author was supported by an award from the Summer Undergraduate Internship in Astrobiology program.

  12. Fabrication and processing of high-strength densely packed carbon nanotube yarns without solution processes.

    PubMed

    Liu, Kai; Zhu, Feng; Liu, Liang; Sun, Yinghui; Fan, Shoushan; Jiang, Kaili

    2012-06-01

    Defects of carbon nanotubes, weak tube-tube interactions, and weak carbon nanotube joints are bottlenecks for obtaining high-strength carbon nanotube yarns. Some solution processes are usually required to overcome these drawbacks. Here we fabricate ultra-long and densely packed pure carbon nanotube yarns by a two-rotator twisting setup with the aid of some tensioning rods. The densely packed structure enhances the tube-tube interactions, thus making high tensile strengths of carbon nanotube yarns up to 1.6 GPa. We further use a sweeping laser to thermally treat as-produced yarns for recovering defects of carbon nanotubes and possibly welding carbon nanotube joints, which improves their Young's modulus by up to ?70%. The spinning and laser sweeping processes are solution-free and capable of being assembled together to produce high-strength yarns continuously as desired. PMID:22538869

  13. THE SOLAR NEBULA ON FIRE: A SOLUTION TO THE CARBON DEFICIT IN THE INNER SOLAR SYSTEM

    SciTech Connect

    Lee, Jeong-Eun; Bergin, Edwin A.; Nomura, Hideko E-mail: ebergin@umich.edu

    2010-02-10

    Despite a surface dominated by carbon-based life, the bulk composition of the Earth is dramatically carbon poor when compared to the material available at formation. Bulk carbon deficiency extends into the asteroid belt representing a fossil record of the conditions under which planets are born. The initial steps of planet formation involve the growth of primitive sub-micron silicate and carbon grains in the Solar Nebula. We present a solution wherein primordial carbon grains are preferentially destroyed by oxygen atoms ignited by heating due to stellar accretion at radii <5 AU. This solution can account for the bulk carbon deficiency in the Earth and meteorites, the compositional gradient within the asteroid belt, and for growing evidence for similar carbon deficiency in rocks surrounding other stars.

  14. Corrosion Behavior of Alloy 22 in Chloride Solutions Containing Organic Acids

    SciTech Connect

    Carranza, R M; Giordano, C M; Rodr?guez, M A; Rebak, R B

    2005-11-04

    Alloy 22 (N06022) is a nickel based alloy containing alloying elements such as chromium, molybdenum and tungsten. It is highly corrosion resistant both under reducing and under oxidizing conditions. Electrochemical studies such as electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. Tests were also carried out in NaCl solutions containing oxalic acid or acetic acid. It is shown that the corrosion rate of Alloy 22 was higher in a solution containing oxalic acid than in a solution of the same pH acidified with HCl. Acetic acid was not corrosive to Alloy 22. The corrosivity of oxalic acid was attributed to its capacity to form stable complex species with metallic cations from Alloy 22.

  15. Chemical evaluation of soil-solution in acid forest soils

    USGS Publications Warehouse

    Lawrence, G.B.; David, M.B.

    1996-01-01

    Soil-solution chemistry is commonly studied in forests through the use of soil lysimeters.This approach is impractical for regional survey studies, however, because lysimeter installation and operation is expensive and time consuming. To address these problems, a new technique was developed to compare soil-solution chemistry among red spruce stands in New York, Vermont, New Hampshire, Maine. Soil solutions were expelled by positive air pressure from soil that had been placed in a sealed cylinder. Before the air pressure was applied, a solution chemically similar to throughfall was added to the soil to bring it to approximate field capacity. After the solution sample was expelled, the soil was removed from the cylinder and chemically analyzed. The method was tested with homogenized Oa and Bs horizon soils collected from a red spruce stand in the Adirondack Mountains of New York, a red spruce stand in east-central Vermont, and a mixed hardwood stand in the Catskill Mountains of New York. Reproducibility, effects of varying the reaction time between adding throughfall and expelling soil solution (5-65 minutes) and effects of varying the chemical composition of added throughfall, were evaluated. In general, results showed that (i) the method was reproducible (coefficients of variation were generally < 15%), (ii) variations in the length of reaction-time did not affect expelled solution concentrations, and (iii) adding and expelling solution did not cause detectable changes in soil exchange chemistry. Concentrations of expelled solutions varied with the concentrations of added throughfall; the lower the CEC, the more sensitive expelled solution concentrations were to the chemical concentrations of added throughfall. Addition of a tracer (NaBr) showed that the expelled solution was a mixture of added solution and solution that preexisted in the soil. Comparisons of expelled solution concentrations with concentrations of soil solutions collected by zero-tension and tension lysimetry indicated that expelled solution concentrations were higher than those obtained with either type of lysimeter, although there was less difference with tension lysimeters than zero-tension lysimeters. The method used for collection of soil solution should be taken into consideration whenever soil solution data are being interpreted.

  16. Leaching of a silicate and carbonate copper ore with heterotrophic fungi and bacteria, producing organic acids.

    PubMed

    Kiel, H; Schwartz, W

    1980-01-01

    Leaching of metals with carbon-heterotrophic microorganisms and organic acids as active agents has been performed with Timna copper ore containing 1.1% copper as carbonates and silicate and with some other metal oxides. Aspergillus niger surface cultures on a 14% sucrose fermentation medium yeilded 87.3% of total copper from 10% suspension within 2 weeks of leaching. On sulfite liquor as an industrial waste product A. niger solubilized 73.8% Cu within 4 weeks. In percolators with 14% sucrose medium up to 1780 ppm copper were found in solution. In leaching experiments with a sea water medium containing 7% sucrose only 684 ppm Cu were soluble. Leaching with lactobacilli containing whey yielded 83.4% of the total copper in 4 weeks. PMID:7222743

  17. Microwave Effect for Glycosylation Promoted by Solid Super Acid in Supercritical Carbon Dioxide

    PubMed Central

    Hinou, Hiroshi; Saito, Naohiro; Ogawa, Masato; Maeda, Takahiko; Nishimura, Shin-Ichiro

    2009-01-01

    The effects of microwave irradiation (2.45 GHz, 200 W) on glycosylation promoted by a solid super acid in supercritical carbon dioxide was investigated with particular attention paid to the structure of the acceptor substrate. Because of the symmetrical structure and high diffusive property of supercritical carbon dioxide, microwave irradiation did not alter the temperature of the reaction solution, but enhanced reaction yield when aliphatic acceptors are employed. Interestingly, the use of a phenolic acceptor under the same reaction conditions did not show these promoting effects due to microwave irradiation. In the case of aliphatic diol acceptors, the yield seemed to be dependent on the symmetrical properties of the acceptors. The results suggest that microwave irradiation do not affect the reactivity of the donor nor promoter independently. We conclude that the effect of acceptor structure on glycosylation yield is due to electric delocalization of hydroxyl group and dielectrically symmetric structure of whole molecule. PMID:20054471

  18. Biosorption of acidic textile dyestuffs from aqueous solution by Paecilomyces sp. isolated from acidic mine drainage.

    PubMed

    abuk, Ahmet; Aytar, P?nar; Gedikli, Serap; zel, Yasemin Kevser; Kocab?y?k, Erin

    2013-07-01

    Removal of textile dyestuffs from aqueous solution by biosorption onto a dead fungal biomass isolated from acidic mine drainage in the anakkale Region of Turkey was investigated. The fungus was found to be a promising biosorbent and identified as Paecilomyces sp. The optimal conditions for bioremediation were as follows: pH, 2.0; initial dyestuff concentration, 50 mg?l(-1) for Reactive Yellow 85 and Reactive Orange 12, and 75 mg?l(-1) for Reactive Black 8; biomass dosage, 2 g?l(-1) for Reactive Yellow 85, 3 g?l(-1) for Reactive Orange 12, 4 g?l(-1) for Reactive Black 8; temperature, 25 C; and agitation rate, 100 rpm. Zeta potential measurements indicated an electrostatic interaction between the binding sites and dye anions. Fourier transform infrared spectroscopy showed that amine, hydroxyl, carbonyl, and amide bonds were involved in the dyestuff biosorption. A toxicity investigation was also carried out before and after the biosorption process. These results showed that the toxicities for the reactive dyestuffs in aqueous solutions after biosorption studies decreased. The Freundlich and Langmuir adsorption models were used for the mathematical description of the biosorption equilibrium, and isotherm constants were evaluated for each dyestuff. Equilibrium data of biosorption of RY85 and RO12 dyestuffs fitted well to both models at the studied concentration and temperature. PMID:23263759

  19. Oxalic acid complexes: promising draw solutes for forward osmosis (FO) in protein enrichment.

    PubMed

    Ge, Qingchun; Chung, Tai-Shung

    2015-03-21

    Highly soluble oxalic acid complexes (OACs) were synthesized through a one-pot reaction. The OACs exhibit excellent performance as draw solutes in FO processes with high water fluxes and negligible reverse solute fluxes. Efficient protein enrichment was achieved. The diluted OACs can be recycled via nanofiltration and are promising as draw solutes. PMID:25697506

  20. Predicting total soil lead from an acetic acid-sodium acetate buffered solution

    SciTech Connect

    Nicklow, C.W.; Norvell, W.A.; Spittler, T.

    1981-01-01

    Total soil lead was predicted satisfactorily from the lead extracted by the Standard Morgan soil testing solution (sodium acetate with acetic acid, pH 4.8). A modified Morgan solution, utilizing EDTA as a chelating agent, extracted greater than 3 times as much lead as the regular Morgan's solution, but was no better in predicting total lead.

  1. l-Lactic acid production from glycerol coupled with acetic acid metabolism by Enterococcus faecalis without carbon loss.

    PubMed

    Murakami, Nao; Oba, Mana; Iwamoto, Mariko; Tashiro, Yukihiro; Noguchi, Takuya; Bonkohara, Kaori; Abdel-Rahman, Mohamed Ali; Zendo, Takeshi; Shimoda, Mitsuya; Sakai, Kenji; Sonomoto, Kenji

    2016-01-01

    Glycerol is a by-product in the biodiesel production process and considered as one of the prospective carbon sources for microbial fermentation including lactic acid fermentation, which has received considerable interest due to its potential application. Enterococcus faecalis isolated in our laboratory produced optically pure l-lactic acid from glycerol in the presence of acetic acid. Gas chromatography-mass spectrometry analysis using [1, 2-(13)C2] acetic acid proved that the E. faecalis strain QU 11 was capable of converting acetic acid to ethanol during lactic acid fermentation of glycerol. This indicated that strain QU 11 restored the redox balance by oxidizing excess NADH though acetic acid metabolism, during ethanol production, which resulted in lactic acid production from glycerol. The effects of pH control and substrate concentration on lactic acid fermentation were also investigated. Glycerol and acetic acid concentrations of 30 g/L and 10 g/L, respectively, were expected to be appropriate for lactic acid fermentation of glycerol by strain QU 11 at a pH of 6.5. Furthermore, fed-batch fermentation with 30 g/L glycerol and 10 g/L acetic acid wholly exhibited the best performance including lactic acid production (55.3 g/L), lactic acid yield (0.991 mol-lactic acid/mol-glycerol), total yield [1.08 mol-(lactic acid and ethanol)]/mol-(glycerol and acetic acid)], and total carbon yield [1.06 C-mol-(lactic acid and ethanol)/C-mol-(glycerol and acetic acid)] of lactic acid and ethanol. In summary, the strain QU 11 successfully produced lactic acid from glycerol with acetic acid metabolism, and an efficient fermentation system was established without carbon loss. PMID:26168904

  2. Activated carbon passes tests for acid-gas cleanup

    SciTech Connect

    Harruff, L.G.; Bushkuhl, S.J.

    1996-06-24

    Use of activated carbon to remove hydrocarbon contaminants from the acid-gas feed to Claus sulfur-recovery units has been successfully pilot tested in Saudi Arabia. Pilot plant results are discussed here along with issues involved in scale-up to commercial size. Heavy hydrocarbons, particularly benzene, toluene, and xylene (BTX) have been linked to coke formation and catalyst deactivation in Claus converters. This deactivation results in reduced sulfur recovery and increased sulfur emissions from these plants. This clean-up process was proven to be capable of removing 95% of the BTX and other C{sub 6}+s from acid gas over a wide range of actual plant conditions. Following the adsorption step, the activated carbon was easily regenerated by use of low-pressure steam. A post-regeneration drying step using plant fuel gas also proved beneficial. The paper discusses feed contaminants, vapor-phase cleanup, testing design, test parameters and results, bed drying after regeneration, regeneration conditions, basic flow, system control, and full-scale installation.

  3. DETERMINATION OF HYDROCYANIC ACID AND FREE CYANIDE IN AQUEOUS SOLUTION

    EPA Science Inventory

    Microgram-per-liter concentrations of HCN in aqueous solutions were determined directly by two methods: bubbling compressed air through a solution to displace a small quantity of HCN, which was collected in a glass bead concentration column, or allowing some HCN to diffuse from a...

  4. Delayed fracture of Ni-Ti superelastic alloys in acidic and neutral fluoride solutions.

    PubMed

    Yokoyama, Ken'ichi; Kaneko, Kazuyuki; Moriyama, Keiji; Asaoka, Kenzo; Sakai, Jun'ichi; Nagumo, Michihiko

    2004-04-01

    Hydrogen-related degradation of the mechanical properties of a Ni-Ti superelastic alloy has been examined by means of delayed fracture tests in acidic and neutral fluoride solutions and hydrogen thermal desorption analysis. Delayed fracture took place in both solutions; the time to fracture was shorter in the acidic solutions than in the neutral solutions with the same fluoride concentration. The time to fracture was reduced in both solutions when applied stress exceeded the critical stress for martensite transformation. In the acidic solutions, Ni-Ti superelastic alloy underwent general corrosion and absorbed substantial amounts of hydrogen. Fractographic features suggested that the delayed fracture in the acidic solutions was attributable to hydrogen embrittlement, whereas in the neutral solutions, a different fracture mode appeared associated with localized corrosion only in the vicinity of the fracture initiation area. In the neutral solutions, the amount of absorbed hydrogen was much less than that in the acidic solutions, and the delayed fracture was likely to be induced by active path corrosion accompanying hydrogen absorption. The results of the present study imply that the hydrogen-related degradation of performance of Ni-Ti superelastic alloys occurs in the presence of fluoride. PMID:14999757

  5. Carbon nanofiber supported bimetallic PdAu nanoparticles for formic acid electrooxidation

    NASA Astrophysics Data System (ADS)

    Qin, Yuan-Hang; Jiang, Yue; Niu, Dong-Fang; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2012-10-01

    Carbon nanofiber (CNF) supported PdAu nanoparticles are synthesized with sodium citrate as the stabilizing agent and sodium borohydride as the reducing agent. High resolution transmission electron microscopy (HRTEM) characterization indicates that the synthesized PdAu particles are well dispersed on the CNF surface and X-ray diffraction (XRD) characterization indicates that the alloying degree of the synthesized PdAu nanoparticles can be improved by adding tetrahydrofuran to the synthesis solution. The results of electrochemical characterization indicate that the addition of Au can promote the electrocatalytic activity of Pd/C catalyst for formic acid oxidation and the CNF supported high-alloying PdAu catalyst possesses better electrocatalytic activity and stability for formic acid oxidation than either the CNF supported low-alloying PdAu catalyst or the CNF supported Pd catalyst.

  6. Corrosion Behavior of Mild Carbon Steel in Ethanolic Solutions

    NASA Astrophysics Data System (ADS)

    Bhola, Shaily M.; Bhola, Rahul; Jain, Luke; Mishra, Brajendra; Olson, David L.

    2011-04-01

    Electrochemical evaluation of ASTM A36 steel was performed in ethanolic solutions containing small concentrations of water ranging from 0 to 10 vol.%. Electrochemical techniques such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization were utilized to analyze corrosion parameters. A fixed concentration of chloride, as per the ASTM specification for fuel grade ethanol, was added to increase the conductivity of the solutions. The effects of water and oxygen on the corrosion behavior of steel in these solutions have been discussed. Pitting corrosion of the steel specimens in these solutions was evaluated using scanning electron microscopy (SEM) and pitting analysis. This investigation was performed to establish a baseline for the microbiologically influenced corrosion (MIC) of steel in ethanolic solutions.

  7. Surface heterogeneity effects of activated carbons on the kinetics of paracetamol removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Ruiz, B.; Cabrita, I.; Mestre, A. S.; Parra, J. B.; Pires, J.; Carvalho, A. P.; Ania, C. O.

    2010-06-01

    The removal of a compound with therapeutic activity (paracetamol) from aqueous solutions using chemically modified activated carbons has been investigated. The chemical nature of the activated carbon material was modified by wet oxidation, so as to study the effect of the carbon surface chemistry and composition on the removal of paracetamol. The surface heterogeneity of the carbon created upon oxidation was found to be a determinant in the adsorption capability of the modified adsorbents, as well as in the rate of paracetamol removal. The experimental kinetic data were fitted to the pseudo-second order and intraparticle diffusion models. The parameters obtained were linked to the textural and chemical features of the activated carbons. After oxidation the wettability of the carbon is enhanced, which favors the transfer of paracetamol molecules to the carbon pores (smaller boundary layer thickness). At the same time the overall adsorption rate and removal efficiency are reduced in the oxidized carbon due to the competitive effect of water molecules.

  8. Chemical equilibrium of minced turkey meat in organic acid solutions.

    PubMed

    Goli, T; Abi Nakhoul, P; Zakhia-Rozis, N; Trystram, G; Bohuon, P

    2007-02-01

    The distribution of acid (HA), anions (A(-)), free protons (H(3)O(+)) and bound protons (H(b)), in homogenized turkey meat was evaluated at various meat/water mass ratios of (1/4-1/10) during titration with acetic acid (0.25N) or lactic acid (0.2N). H(b) concentration was determined by titration with hydrochloric acid (0.075N) and a correlation for [H(b)]=f(pH) was proposed. A procedure was used to calculate the fractions of the various species in equilibrium, starting from an initial acid concentration in a meat/water system and assuming the accuracy of the pK(a) value of the pure weak acids despite the chemical complexity of meat. Calculated results were in very good agreement (0.15) with experimental pH values, whatever the acid, meat batch or meat/water mass ratios used. Less than 1% of the total protons were free (H(3)O(+)) and determined the meat pH. PMID:22063663

  9. Thermodynamic properties of carbon in b.c.c. and f.c.c. iron-silicon-carbon solid solutions.

    NASA Technical Reports Server (NTRS)

    Chraska, P.; Mclellan, R. B.

    1971-01-01

    The equilibrium between hydrogen-methane gas mixtures and Fe-Si-C solid solutions has been investigated both as a function of temperature and carburizing gas composition. The thermodynamic properties of the carbon atoms in both b.c.c. and f.c.c. solid solution have been derived from the equilibrium measurements. The results found have been compared with those of earlier investigations and with the predictions of recent theoretical models on ternary solid solutions containing both substitutional and interstitial solute atoms.

  10. Amino acids of the Murchison meteorite. I - Six carbon acyclic primary alpha-amino alkanoic acids

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Gandy, W. E.; Pizzarello, S.

    1981-01-01

    Six of the seven chain isomers of six-carbon acyclic primary alpha-amino alkanoic acids (leucine isomers) have been either identified or confirmed in hot-water extracts of the Murchison meteorite using combined gas chromatography-mass spectrometry (GC-MS) and ion exchange chromatography. 2-Amino-2-ethylbutyric acid, 2-amino-2,3-dimethylbutyric acid, pseudoleucine, and 2-methylnorvaline were positively identified by GC-MS. These amino acids have not been previously reported to occur in natural materials and may be uniquely meteoritic in origin. The presence of leucine and isoleucine (including the diastereoisomer, alloisoleucine) was confirmed. Peaks corresponding to norleucine were seen by ion-exchange and gas chromatography but characteristic mass spectra were not obtained. The alpha-branched chain isomers in this series are quantitatively the most significant. These results are compared with literature data on amino acid synthesis by electrical discharge and Fischer-Tropsch-type catalysis. Neither model system produces an amino acid suite that is completely comparable to that found in the Murchison meteorite.

  11. Acid-base equilibrium in aqueous solutions of 1,3-dimethylbarbituric acid as studied by 13C NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Gryff-Keller, A.; Kraska-Dziadecka, A.

    2011-12-01

    13C NMR spectra of 1,3-dimethylbarbituric acid in aqueous solutions of various acidities and for various solute concentrations have been recorded and interpreted. The spectra recorded at pH = 2 and below contain the signals of the neutral solute molecule exclusively, while the ones recorded at pH = 7 and above only the signals of the appropriate anion, which has been confirmed by theoretical GIAO-DFT calculations. The signals in the spectra recorded for solutions of pH < 7 show dynamic broadenings. The lineshape analysis of these signals has provided information on the kinetics of the processes running in the dynamic acid-base equilibrium. The kinetic data determined this way have been used to clarify the mechanisms of these processes. The numerical analysis has shown that under the investigated conditions deprotonation of the neutral solute molecules undergoes not only via a simple transfer of the C-H proton to water molecules but also through a process with participation of the barbiturate anions. Moreover, the importance of tautomerism, or association, or both these phenomena for the kinetics of the acid-base transformations in the investigated system has been shown. Qualitatively similar changes of 13C NMR spectra with the solution pH variation have been observed for the parent barbituric acid.

  12. GIAO-DFT isotropic magnetic shielding constants and spin-spin coupling of tartaric acid in water solution

    NASA Astrophysics Data System (ADS)

    Fideles, Bruna; Oliveira, Leonardo B. A.; Colherinhas, Guilherme

    2016-01-01

    We investigate the nuclear isotropic shielding constants and spin-spin coupling for oxygen and carbons atoms of isomers of tartaric acid in gas phase and in water solutions by Monte Carlo simulation and quantum mechanics calculations using the GIAO-B3LYP approach. Solute polarization effects are included iteratively and play an important role in the quantitative determination of shielding constants. Our MP2/aug-cc-pVTZ results show substantial increases of the dipole moment in solution as compared with the gas phase results (61-221%). The solvent effects on the ?(13O) values are in general small. More appreciable solvent effects can be seen on the ?(17O) and J(Csbnd O).

  13. The comparison of fluorescent spectra on acetic acid and ethanol solutions

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Lan, Xiufeng; Gao, Shumei; Shen, Zhonghua; Lu, Jian; Ni, Xiao-Wu

    2003-12-01

    Acetic acid and ethanol solutions can emit fluorescence when induced by 253.7nm UV-light. In this paper, fluorescence spectral characteristics of acetic acid and ethanol solutions are analyzed and studied in theory and in experiment. The results indicate that both acetic acid and ethanol can emit two fluorescence spectral bands, one is from 330nm to 493nm and the other is from 534nm to 665nm. The emitting fluorescence intensity is very sensitive to the solutions concentrations, and fluorescence quenching occurs in some solutions of the two samples. Furthermore, the physical mechanism of fluorescence emission of acetic acid and ethanol molecules is analyzed based on the theory of molecule orbital structure, and the quenching mechanism are studied by the dynamic process. Investigation on the native fluorescence spectrum of the two solvent and their characteristics will contribute to the study of the fluorescence spectra when they serve as solute, hydrolysis catalyst and food additive.

  14. Removal of radium from acidic solutions containing same by adsorption on coal fly ash

    DOEpatents

    Scheitlin, Frank M.

    1984-01-01

    The invention is a process for the removal of radium from acidic aqueous solutions. In one aspect, the invention is a process for removing radium from an inorganic-acid solution. The process comprises contacting the solution with coal fly ash to effect adsorption of the radium on the ash. The radium-containing ash then is separated from the solution. The process is simple, comparatively inexpensive, and efficient. High radium-distribution coefficients are obtained even at room temperature. Coal fly ash is an inexpensive, acid-resistant, high-surface-area material which is available in large quantities throughout the United States. The invention is applicable, for example, to the recovery of .sup.226 Ra from nitric acid solutions which have been used to leach radium from uranium-mill tailings.

  15. Process for the removal of radium from acidic solutions containing same

    DOEpatents

    Scheitlin, F.M.

    The invention is a process for the removal of radium from acidic aqueous solutions. In one aspect, the invention is a process for removing radium from an inorganic-acid solution. The process comprises contacting the solution with coal fly ash to effect adsorption of the radium on the ash. The radium-containing ash then is separated from the solution. The process is simple, comparatively inexpensive, and efficient. High radium-distribution coefficients are obtained even at room temperature. Coal fly ash is an inexpensive, acid-resistant, high-surface-area material which is available in large quantities throughout the United States. The invention is applicable, for example, to the recovery of /sup 226/Ra from nitric acid solutions which have been used to leach radium from uranium-mill tailings.

  16. Titanium Implant Osseointegration Problems with Alternate Solutions Using Epoxy/Carbon-Fiber-Reinforced Composite

    PubMed Central

    Petersen, Richard C.

    2014-01-01

    The aim of the article is to present recent developments in material research with bisphenyl-polymer/carbon-fiber-reinforced composite that have produced highly influential results toward improving upon current titanium bone implant clinical osseointegration success. Titanium is now the standard intra-oral tooth root/bone implant material with biocompatible interface relationships that confer potential osseointegration. Titanium produces a TiO2 oxide surface layer reactively that can provide chemical bonding through various electron interactions as a possible explanation for biocompatibility. Nevertheless, titanium alloy implants produce corrosion particles and fail by mechanisms generally related to surface interaction on bone to promote an inflammation with fibrous aseptic loosening or infection that can require implant removal. Further, lowered oxygen concentrations from poor vasculature at a foreign metal surface interface promote a build-up of host-cell-related electrons as free radicals and proton acid that can encourage infection and inflammation to greatly influence implant failure. To provide improved osseointegration many different coating processes and alternate polymer matrix composite (PMC) solutions have been considered that supply new designing potential to possibly overcome problems with titanium bone implants. Now for important consideration, PMCs have decisive biofunctional fabrication possibilities while maintaining mechanical properties from addition of high-strengthening varied fiber-reinforcement and complex fillers/additives to include hydroxyapatite or antimicrobial incorporation through thermoset polymers that cure at low temperatures. Topics/issues reviewed in this manuscript include titanium corrosion, implant infection, coatings and the new epoxy/carbon-fiber implant results discussing osseointegration with biocompatibility related to nonpolar molecular attractions with secondary bonding, carbon fiber in vivo properties, electrical semiconductors, stress transfer, additives with low thermal PMC processing and new coating possibilities. PMID:25635227

  17. The influence of dissolved organic carbon on pH measurements of low solute content waters

    NASA Astrophysics Data System (ADS)

    Metcalf, Richard C.; Peck, David V.; Lori, Arent J.

    1989-04-01

    This study has thoroughly examined the concern that dissolved organic carbon (DOC) interferes with pH electrode measurements of low solute content waters. Using Ross pH combination electrodes according to protocols of the U.S. Environmental Protection Agency's National Surface Water Survey (NSWS), our laboratory pH measurements of 10 -4 N H 2SO 4 standards (spiked from 0 to 100 mg L -1 DOC with potassium hydrogen ortho-phthalate, humic acid, or the surfactant Tergitol 15-S-9) showed little or no evidence of DOC interference, within the 0.05 (2s) pH unit measurement precision. Concern with DOC-induced pH measurement errors prompted previous researchers to advocate using a calculated pH value, based on measurements of dissolved inorganic carbon (DIC), P co 2, water temperature, and the appropriate carbonate equilibria. CO 2-equilibrated pH measurements from the Eastern Lake Survey Phase-I showed no significant difference with calculated pH values based on the above model. A limited sensitivity analysis of the errors associated with direct pH electrode measurements compared to calculated pH values indicates that, for a regional survey taking place over weeks or months, potentiometric determinations are more precise at present. All of this evidence suggests that the pH measurements for the NSWS (as well as a long series of prior regional studies) are unaffected by DOC-induced pH measurement errors, although reference electrode junction errors still deserve greater attention in many studies.

  18. Separation of ions in acidic solution by capillary electrophoresis

    SciTech Connect

    Thornton, M.

    1997-10-08

    Capillary electrophoresis (CE) is an effective method for separating ionic species according to differences in their electrophoretic mobilities. CE separations of amino acids by direct detection are difficult due to their similar electrophoretic mobilities and low absorbances. However, native amino acids can be separated by CE as cations at a low pH by adding an alkanesulfonic acid to the electrolyte carrier which imparts selectivity to the system. Derivatization is unnecessary when direct UV detection is used at 185 nm. Simultaneous speciation of metal cations such as vanadium (IV) and vanadium (V) can easily be performed without complexation prior to analysis. An indirect UV detection scheme for acidic conditions was also developed using guanidine as the background carrier electrolyte (BCE) for the indirect detection of metal cations. Three chapters have been removed for separate processing. This report contains introductory material, references, and general conclusions. 80 refs.

  19. PROCESS FOR RECOVERY OF URANIUM AND VANADIUM FROM CARBONATE SOLUTIONS BY REDUCTION-PRECIPITATION

    DOEpatents

    Ellis, D.A.; Lindblom, R.O.

    1957-09-24

    A process employing carbonate leaching of ores and an advantageous methcd of recovering the uranium and vanadium from the leach solution is described. The uranium and vanadium can be precipitated from carbonate leach solutions by reaction with sodium amalgam leaving the leach solution in such a condition that it is economical to replenish for recycling. Such a carbonate leach solution is treated with a dilute sodium amalgam having a sodium concentration within a range of about 0.01 to 0.5% of sodium. Efficiency of the treatment is dependent on at least three additional factors, intimacy of contact of the amalgam with the leach solution, rate of addition of the amalgam and exclusion of oxygen (air).

  20. Hydropyrolysis as a preparative method for the compound-specific carbon isotope analysis of fatty acids.

    PubMed

    Sephton, Mark A; Meredith, Will; Sun, Cheng-Gong; Snape, Colin E

    2005-01-01

    Compound-specific stable carbon isotope analysis by gas chromatography/combustion/isotope ratio mass spectrometry is an effective and risk-free means of investigating fatty acid metabolism. Straightforward analysis, however, leads to poor chromatographic resolution, while derivatization adds carbon thereby corrupting the starting stable isotopic composition. Hydropyrolysis is a new approach which defunctionalizes fatty acids to yield the corresponding n-alkanes thus retaining the carbon skeleton intact and improving chromatography, allowing the faithful measurement of carbon isotope ratios. PMID:15645412

  1. Comparison of CO2 and oxygen DC submerged thermal plasmas for decomposition of carboxylic acid in aqueous solution

    NASA Astrophysics Data System (ADS)

    Safa, S.; Hekmat-Ardakan, A.; Soucy, G.

    2014-11-01

    The feasibility of the carboxylic acid decomposition with two different direct current (DC) thermal plasma torches was investigated. An oxygen DC submerged thermal plasma torch and a newly designed submerged DC plasma torch operating with a mixture of carbon dioxide and methane (CO2/CH4) were used. Sebacic acid was selected as a representative of pollutants in the most wastewater produced by chemical process industries. The effect of different operational conditions including treatment time, the reactor pressure as well as the role of oxidizing agents such as (H2O2) were investigated on the decomposition rate of sebacic acid. Concentration of sebacic acid was quantified by Ion Chromatography/Mass Spectrometry (IC/MS). The oxygen plasma showed higher decomposition rate in basic medium. Adding H2O2 into aqueous solution enhanced the sebacic acid decomposition rate with the CO2/CH4 plasma up to the same decomposition rate of the oxygen plasma. Increasing the pressure also increased the decomposition rate for both plasmas with an increase twice higher for the CO2/CH4 plasma than that of the oxygen plasma. This work therefore presents the conditions in which these plasmas can provide the same decomposition rate for contaminants in aqueous solution.

  2. Picosecond Pulse Radiolysis of Highly Concentrated Phosphoric Acid Solutions: Mechanism of Phosphate Radical Formation.

    PubMed

    Ma, Jun; Schmidhammer, Uli; Mostafavi, Mehran

    2015-06-18

    Eight solutions containing phosphoric acid with concentrations ranging from 2 mol L(-1) to neat acid have been studied by picosecond pulse radiolysis. The absorbance of the secondary radical H2PO4() formed within 7 ps of the electron pulse is observed using pulse-probe method in the visible. Kinetic analysis shows that the radicals of phosphoric acid are formed via two mechanisms: direct electron detachment and oxidation by the radical cation of water, H2O(+). On the basis of molar extinction coefficient value of 1850 L mol(-1) cm(-1), at 15 ps the radiolytic yield of H2PO4() formation by direct energy absorption is 3.7 0.1 10(-7) mol J(-1) in neat phosphoric acid. In highly concentrated phosphoric acid solutions, the total yield of phosphate radical at 15 ps exhibits an additional contribution that can be explained by electron transfer from phosphoric acid to H2O(+). The efficiency of the electron transfer to this strongly oxidizing species in phosphoric acid solutions is lower compared with the one in sulfuric acid solutions. Two explanations are given to account for a relatively low efficiency of H2O(+) scavenging in concentrated phosphoric acid solutions. PMID:25176139

  3. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

    NASA Astrophysics Data System (ADS)

    Prasek, Jan; Huska, Dalibor; Jasek, Ondrej; Zajickova, Lenka; Trnkova, Libuse; Adam, Vojtech; Kizek, Rene; Hubalek, Jaromir

    2011-05-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode.

  4. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids.

    PubMed

    Prasek, Jan; Huska, Dalibor; Jasek, Ondrej; Zajickova, Lenka; Trnkova, Libuse; Adam, Vojtech; Kizek, Rene; Hubalek, Jaromir

    2011-01-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

  5. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

    PubMed Central

    2011-01-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

  6. Effect of activated carbon surface oxygen- and/or nitrogen-containing groups on adsorption of copper(II) ions from aqueous solution

    SciTech Connect

    Biniak, S.; Pakula, M.; Szymanski, G.S.; Swiatkowski, A.

    1999-08-31

    The adsorption properties of a modified activated carbon with various oxygen-and/or nitrogen-containing surface groups toward copper ions was studied. Previously de-ashed and chemically modified commercial activated carbon D-43/1 (carbo-Tech, Essen, Germany) was used. The chemical properties of the modified carbon surface were estimated by standard neutralization titration with HCl, NaOH, and HaOC{sub 2}{sub 5}. The adsorption of Cu{sup 2+} ions on three modified activated carbons from aqueous CuSO{sub 4} solution of various pH was measured. The carbon samples with adsorbed Cu{sup 2+} ions were analyzed by spectroscopic methods (X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy). In addition, an electrochemical measurement (cyclic voltammetry) was performed using powdered activated carbon electrodes. While the modification procedures employed alter the surface only slightly, they strongly influence the surface chemical structure. Basic groups are predominant in the heat-treated samples; acidic functional groups are predominant in the oxidized sample. Both the copper cation adsorption studies and the spectral and electrochemical measurements show that adsorbed ions interact with the carbon surface in different ways. The number of adsorbed ions depends on the nature and quantity of surface acid-base functionalities and on the pH equilibrium in the aqueous solution. The possible mechanisms of interactions between metal ions and carbon surface functionalities are summarized and discussed.

  7. Reprocessing system with nuclide separation based on chromatography in hydrochloric acid solution

    SciTech Connect

    Suzuki, Tatsuya; Tachibana, Yu; Koyama, Shi-ichi

    2013-07-01

    We have proposed the reprocessing system with nuclide separation processes based on the chromatographic technique in the hydrochloric acid solution system. Our proposed system consists of the dissolution process, the reprocessing process, the minor actinide separation process, and nuclide separation processes. In the reprocessing and separation processes, the pyridine resin is used as a main separation media. It was confirmed that the dissolution in the hydrochloric acid solution is easily achieved by the plasma voloxidation and by the addition of oxygen peroxide into the hydrochloric acid solution.

  8. A Simple Demonstration of Carbon Dioxide Fixation and Acid Production in CAM Plants

    ERIC Educational Resources Information Center

    Walker, John R. L.; McWha, James A.

    1976-01-01

    Described is an experiment investigating carbon dioxide fixation in the dark and the diurnal rhythm of acid production in plants exhibiting Crassulacean Acid Metabolism. Included are suggestions for four further investigations. (SL)

  9. Carbon composite membranes: A solution to adverse humidity effects

    SciTech Connect

    Jones, C.W.; Koros, W.J. )

    1995-01-01

    While the separation properties of carbon molecular sieving membranes are superior to those of other materials, a significant drawback has been their vulnerability to adverse effects from exposure to water vapor. Since significant membrane function is maintained at low levels of exposure, efforts were focused on devising a means to lower the water activity at the carbon surface. This was successfully accomplished with the development of carbon composite membranes. These membranes consist of a hollow fiber carbon membrane coated with a thin layer of certain unique polymeric materials. The polymers are highly hydrophobic but do not prohibitively reduce the flux of other permeating species, and the resulting composite membranes are much more resistant to water vapor effects. The performance of the composite membranes is analyzed in terms of the series resistance model. While small losses in selectivity and productivity occur as a result of the resistance added by the polymer layer, the composite membranes are still very attractive as compared to conventional polymer membranes. The polymer barrier type and thickness and the resulting degree of protection are variables that can be tailored in a controlled manner for specific applications.

  10. Dispersion of multiwalled carbon nanotubes in aqueous silk fibroin solutions.

    PubMed

    Kim, Hyunsuk; Kim, Hun-Sik; Lee, Heon Sang; Chin, In-Joo; Jin, Hyoung-Joon

    2008-10-01

    A simple method was developed to densely assemble multiwalled carbon nanotubes (MWCNTs) onto single native spider silk and silkworm silk fibers in aqueous system. The interactions between the MWCNTs and the silk fibroin were investigated using scanning electron microscopy and transmission electron microscopy. Furthermore, the role of pure silk fibroin in dispersing MWCNTs in aqueous systems was also assessed. PMID:19198494

  11. Multiple-acid equilibria in adsorption of carboxylic acids from dilute aqueous solution

    SciTech Connect

    Husson, S.M.; King, C.J.

    1999-02-01

    Equilibria were measured for adsorption of carboxylic acids from aqueous, binary-acid mixtures of lactic and succinic acids and acetic and formic acids onto basic polymeric sorbents. The experimentally determined adsorption isotherms compared well with model predictions, confirming that simple extensions from adsorption of individual acids apply. Fixed-bed studies were carried out that establish the efficacy of chromatographic fractionation of lactic and succinic acids using basic polymeric sorbents. Finally, sequential thermal and solvent regeneration of lactic and acetic acid-laden sorbents was investigated as a method to fractionate among coadsorbed volatile and nonvolatile acids. Essentially complete removal of the acetic acid from the acid-laden sorbent was achieved by vaporization under the conditions used; a small amount of loss of lactic acid (about 11%) was observed.

  12. Basic solutions to carbon/carbon oxidation: Science and technology. Annual technical report, 15 April 1993-14 April 1994

    SciTech Connect

    Harrison, T.R.; Chung, T.; Radovic, L.; Pantano, C.; Thrower, P.A.

    1994-05-13

    The attached report addresses the first year of a program aimed at developing basic solutions to carbon/carbon composite oxidation. In particular, one primary thrust is the development of boron containing carbons through pyrolysis of boron containing polymers. Additionally, a basic understanding of the oxidation mechanisms in carbons and boron containing carbons is being sought. Several new boron containing precursors have been synthesized, which can be converted to B/C materials after pyrolysis. In particular, polyacrylonitrile (PAN) has been copolymerized with a boron-containing monomer (vinylcatecholborane.) Approximately 68% of the original boron is retained after pyrolysis yielding a product with 3.4% boron. 1,4-polybutadiene (PBD) has been hydroborated to contain large amounts of boron. Model compounds have been used to prepare polydiyne with considerable amounts of boron. In the latter two cases, direct analysis for % boron is not yet available. Preliminary TGA data suggests that PBD containing boron results in a more stable structure.

  13. Reaction of CO2 and Carbonate Mineral in Seawater for Mitigation of CO2 and Ocean Acidity

    NASA Astrophysics Data System (ADS)

    Rau, G. H.

    2010-12-01

    A lab-scale seawater/mineral carbonate gas scrubber was found to remove up to 97% of CO2 in a simulated flue gas stream at ambient temperature and pressure, with a large fraction of this carbon ultimately converted to dissolved calcium bicarbonate. Contrary to predictions based on classical carbonate chemistry, up to 85% of the captured carbon was retained in solution, i.e., it did not degas or precipitate, even after full equilibration with air. This is because abiotic precipitation of CaCO3 from seawater is chemically inhibited up to dissolved concentrations approaching 20X supersaturation. Thus, above-ground CO2 hydration with seawater, reaction with mineral carbonate, and conversion to dissolved Ca(HCO3)2 may provide a relatively simple point-source CO2 capture and storage scheme at coastal locations. This approach is analogous to wet limestone scrubbing of flue gas that is commonly used for SO2 removal. Such low-tech CO2 mitigation could be especially relevant for retrofitting to existing coastal power plants and for deployment in the developing world, the primary source of future CO2 emissions. An electrochemically powered version of the preceding has been demonstrated for air capture of CO2. In any case, the addition of the resulting alkaline solution to the ocean would benefit marine ecosystems that are currently challenged by acidification. This is indicated by the widespread use of miniature CO2/carbonate mineral/seawater reactors in saltwater aquaria to generate alkalinity for preserving or enhancing coral and shellfish growth. Large-scale applications would thus allow use of the planet’s largest saline reservoir, the ocean, to safely and effectively store anthropogenic carbon in a form other than molecular CO2 or carbonic acid. This approach in essence hastens Nature's own very effective but slow CO2 mitigation process; carbonate mineral weathering is a major consumer of excess atmospheric CO2 and ocean acidity on geologic times scales.

  14. Visible light caffeic acid degradation by carbon-doped titanium dioxide.

    PubMed

    Venditti, Francesco; Cuomo, Francesca; Ceglie, Andrea; Avino, Pasquale; Russo, Mario Vincenzo; Lopez, Francesco

    2015-03-31

    The removal of the phenolic compound, caffeic acid, by photodegradation has been investigated using carbon-doped titanium dioxide particles as a photocatalyst under visible light. UV-vis absorption spectroscopy and gas chromatography-ion trap mass spectrometry analyses revealed a substrate concentration dependence of the removal of caffeic acid from a water solution. The k2 and t(0.5) parameters of each reaction were calculated by fitting kinetics data to a second-order kinetic adsorption model. To evaluate the photodegradation event, the effect of the adsorption process on the whole degradation was also monitored in the absence of light. Adsorption isotherm studies supported by ? potential and scanning electron microscopy data demonstrated the pivotal role of the absorption mechanism. It was found that the whole photodegradation process is governed by a synergic mechanism in which adsorption and photodegradation are involved. This study, centered on the removal of caffeic acid from aqueous solutions, highlights the potential application of this technology for the elimination of phenolic compounds from olive mill wastewater, a fundamental goal in both the agronomical and environmental fields. PMID:25763603

  15. Effects of taste solutions, carbonation, and cold stimulus on the power frequency content of swallowing submental surface electromyography.

    PubMed

    Miura, Yutaka; Morita, Yuji; Koizumi, Hideki; Shingai, Tomio

    2009-05-01

    This study explored the effects of 5 taste solutions (citric acid, sucrose, sodium chloride, caffeine, and sodium glutamate) versus water on the power frequency content of swallowing submental surface electromyography (sEMG). Healthy subjects were presented with 5 ml of each of 5 tastants and water. Data were collected in 3 trials of the 5 tastants and water by using submental sEMG, which was then subjected to spectral analysis. Sour and salt taste solutions increased the spectrum-integrated values of the total power components. The spectrum-integrated values of low-frequency power (below 10 Hz) in the salt taste trial significantly increased, whereas those of high-frequency power (above 10 Hz) in the sour taste trial tended to increase. Neither pleasantness nor intensity of taste was related to these changes. This study also explored the effects of carbonation and cold stimulus on the power frequency content of continuous swallowing sEMG for 60-ml solutions. Carbonation significantly increased the spectrum-integrated value of the total power components by significantly increasing the high-frequency content. Cold stimulus significantly decreased the low-frequency content. In summary, this study reveals that taste, carbonation, and cold stimulus have qualitatively different influences on the power frequency content of swallowing sEMG. PMID:19221127

  16. Inhibitive effects of palm kernel oil on carbon steel corrosion by alkaline solution

    NASA Astrophysics Data System (ADS)

    Zulkafli, M. Y.; Othman, N. K.; Lazim, A. M.; Jalar, A.

    2013-11-01

    The behavior of carbon steel SAE 1045 in 1 M NaOH solution containing different concentrations of palm kernel oil (PKO) has been studied by weight loss and polarization measurement. Results showed that the corrosion of carbon steel in NaOH solution was considerably reduced in presence of such inhibitors. The inhibition efficiency increases when concentration of inhibitor increase. Maximum inhibition efficiency (≈ 96.67%) is obtained at PKO concentration 8 v/v %. This result revealed that palm kernel oil can act as a corrosion inhibitor in an alkaline medium. Corrosion rates of carbon steel decrease as the concentration of inhibitor is increased.

  17. Sorption of 4-carboxyquinoline derivatives from aqueous acetonitrile solutions on the surface of porous graphitized carbon

    NASA Astrophysics Data System (ADS)

    Savchenkova, A. S.; Buryak, A. K.; Kurbatova, S. V.

    2015-09-01

    The sorption of 4-carboxyquinoline derivatives from aqueous acetonitrile solutions on porous graphitized carbon was studied. The effect of the structure of analyte molecules and the eluent composition on the characteristics of retention under the conditions of RP HPLC was analyzed. The effect of pH of the eluent on the shift of equilibrium in aqueous acetonitrile solutions was investigated.

  18. Mechanistic studies of nitrations and oxidations in solutions of dinitrogen pentaoxide in nitric acid

    SciTech Connect

    Willmer, R.F.

    1992-01-01

    Mechanisms of nitrations in solutions of dinitrogen pentaoxide in nitric acid of 1,2,4-trichloro-5-nitrobenzene and 1,2-dichloro-4-nitrobenzene have been proposed. The kinetics and products of the nitration, in the title medium, of substantially deactivated benzoic acids and benzaldehydes have been investigated. Kinetics of nitration of some substituted benzoic acids in nitric acid solutions containing dinitrogen pentaoxide or nitronium trifluoro-methanesulphonate (nitronium triflate) have been compared. Rate coefficients for reactions in dinitrogen pentaoxide solutions were generally similar to those from nitronium triflate solutions of the same estimated nitronium ion concentration. Yields of aromatic products of nitration of some benzoic acid derivatives in the nitric acid solutions have been determined. Nitrodecarboxylation of 4-fluorobenzoic acid occurs as a result of nitronium ion attach at C(1). The competition between oxidation to the corresponding benzoic acid and nitration in the aromatic ring of some substituted benzaldehydes has been probed by kinetic and product studies. 4-Carboxybenzaldehyde is nitrated but more deactivated substrates are predominantly oxidized. Rapid reversible gem-dinitrate formation occurs in concentrated dinitrogen pentaoxide solutions. The equilibrium extent of formation of [alpha]-deuterio-(4-nitropheny)-dinitratomethane from [alpha]-deuterio-4-nitrobenzaldehyde is reported. 4-nitrobenzaldehyde and the gem-dinitrate are oxidized in processes in which [alpha]-hydrogen loss is at least partially rate determining. The relative rates of oxidation in nitronium triflate solutions suggest that the [alpha]-hydrogen is removed as a hydride ion in that medium. There is evidence for the intrusion of a radical mechanism of nitration in concentrated solutions of dinitrogen pentaoxide. (4-Nitrophenyl)dinitratomethane was produced on the addition of 4-nitrobenzaldehyde to a solution of dinitrogen pentaoxide in dichloromethane.

  19. Solution processable carbon nanotube network thin-film transistors operated in electrolytic solutions at various pH

    NASA Astrophysics Data System (ADS)

    Haeberle, Tobias; Mnzer, Alexandra M.; Buth, Felix; Antonio Garrido, Jose; Abdellah, Alaa; Fabel, Bernhard; Lugli, Paolo; Scarpa, Giuseppe

    2012-11-01

    We investigate the electronic properties of solution-gated carbon nanotube (CNT) thin-film transistors, where the active layer consists of a randomly distributed single-walled CNT network of >90% semiconducting nanotubes, deposited from an aqueous solution by spin-coating. The devices are characterized in different electrolytic solutions, where a reference electrode immersed in the liquid is used to apply the gate potential. We observe a gate-potential shift in the transfer characteristic when the pH and/or ionic strength of the electrolytic solution is changed with a pH sensitivity of ?19 mV/pH. This sensitivity is attributed to a surface charging effect at the CNT/electrolyte interface.

  20. Synthesis of calcium carbonate in a pure ethanol and aqueous ethanol solution as the solvent

    NASA Astrophysics Data System (ADS)

    Seo, Kang-Seok; Han, Choon; Wee, Jung-Ho; Park, Jin-Koo; Ahn, Ji-Whan

    2005-04-01

    The possibility of formation of precipitated calcium carbonate (PCC) in pure ethanol, not as small additives, but as the main solvent, was investigated by precipitating a variety of PCC via a carbonation reaction. During the carbonation in a slaked lime-pure ethanol suspension, three morphology types of CaCO 3 were also precipitated, including calcite, which was the only type of PCC precipitated in the pure water system, and aragonite and vaterite, which were also precipitated without leaving Ca(OH) 2 as the reactants. Their particle size was half of those from pure water. In a pure ethanol system, calcite was first precipitated from the carbonation in bulk solution as in the pure water system, while the aragonite and vaterite might be synthesized via other local carbonation routes occurring in the surface of the Ca(OH) 2 grain following the bulk carbonation in the solution. In this local carbonation, there was little variation of electrical conductivity and pH. In the aqueous solution of less than 40 mol% ethanol, the PCC is all calcite; therefore, water has dominant effect as the solvent. On the other hand, in the solution of more than 60 mol% ethanol, the solvent acts as the pure ethanol and calcite, aragonite and vaterite can be precipitated.

  1. [The subacute toxicity of glucosylthiazolidine-4-carbonic acid in rats].

    PubMed

    Lewerenz, H J; Plass, R; Bleyl, D W; Macholz, R; Zeise, S; Kroh, L

    1990-01-01

    Glucosylthiazolidine-4-carbonic acid, an intermediate of the Maillard reaction between D-glucose and L-cysteine, was given in doses of 0, 25, 50 or 100 mg/kg b.w. by oral intubation to male and female rats for 21 days. General appearance, growth, food consumption, haematology, urine analysis and serum chemistry including determinations of enzyme activities, organ weights and macroscopic and microscopic pathology were used as criteria for adverse effects. Effects on the kidneys were indicated by oliguria and decreased specific gravity of the urine in males and histopathological changes of the proximal tubules in females. The no-effect dose established from this study is 25 mg/kg b.w. PMID:2089262

  2. Alkaline solution absorption of carbon dioxide method and apparatus

    DOEpatents

    Hobbs, D.T.

    1991-01-01

    Disclosed is a method for measuring the concentration of hydroxides (or pH) in alkaline solutions, using the tendency of hydroxides to adsorb CO{sub 2}. The method comprises passing CO{sub 2} over the surface of an alkaline solution in a remote tank before and after measurements of the CO{sub 2} concentration. Comparison of the measurements yields the adsorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to adsorption fraction. A schematic is given of a process system according to a preferred embodiment of the invention. 2 figs.

  3. Adsorption of naphthalene from aqueous solution on activated carbons obtained from bean pods.

    PubMed

    Cabal, Belen; Budinova, Temenuzhka; Ania, Conchi O; Tsyntsarski, Boyko; Parra, Jos B; Petrova, Bilyana

    2009-01-30

    The preparation of activated carbons from bean pods waste by chemical (K(2)CO(3)) and physical (water vapor) activation was investigated. The carbon prepared by chemical activation presented a more developed porous structure (surface area 1580 m(2) g(-1) and pore volume 0.809 cm(3) g(-1)) than the one obtained by water vapor activation (258 m(2) g(-1) and 0.206 cm(3) g(-1)). These carbons were explored as adsorbents for the adsorption of naphthalene from water solutions at low concentration and room temperature and their properties are compared with those of commercial activated carbons. Naphthalene adsorption on the carbons obtained from agricultural waste was stronger than that of carbon adsorbents reported in the literature. This seems to be due to the presence of large amounts of basic groups on the bean-pod-based carbons. The adsorption capacity evaluated from Freundlich equation was found to depend on both the textural and chemical properties of the carbons. Naphthalene uptake on biomass-derived carbons was 300 and 85 mg g(-1) for the carbon prepared by chemical and physical activation, respectively. Moreover, when the uptake is normalized per unit area of adsorbent, the least porous carbon displays enhanced naphthalene removal. The results suggest an important role of the carbon composition including mineral matter in naphthalene retention. This issue remains under investigation. PMID:18541368

  4. Long-term carbon stabilization through sorption of dissolved aromatic acids to reactive particles (Invited)

    NASA Astrophysics Data System (ADS)

    Kramer, M. G.; Sanderman, J.; Chadwick, O.; Chorover, J.; Vitousek, P.

    2010-12-01

    Short-range order minerals are highly reactive soil constituents that are found in all soils and in particularly high quantities in volcanic soils. They retain large quantities of soil carbon, thereby acting as a long-term sink for carbon dioxide, but the main source for this carbon accumulation in soil is not yet known. We evaluated the biochemistry of solid and dissolved organic carbon in horizons containing differing short-range ordered mineral concentrations using solid-state 13C nuclear magnetic resonance spectroscopy, stable isotope measurements and soil column leaching experiments across a well-constrained chronosequence of volcanic soils in Hawai’i. Molecular mixing model results, isotopic and elemental measurements, indicate that the oldest and most persistent C stores across the chronosequence are comprised not of highly microbially processed organic matter (e.g. proteins or lipids), but rather of partially oxidized aromatic plant compounds (up to 62% of the total soil C) preserved through chemical bonding to reactive soil minerals via carboxyl-rich functionalities. NMR spectra obtained from deep soil horizons containing an abundance of SRO minerals, showed strong chemical resemblance to that of DOM derived from plant litter. Solublization and high production rates of recalcitrant DOM controlled substantially by microbial activity were observed in the soil column leaching experiments. When the DOM-rich solution derived from organic horizons was leached through mineral soil horizons, the quantity of DOM sorbed was dependent on the abundance of SRO minerals present in the soil. These results suggest that microbial-driven DOM formation derived from plant litter and the subsequent binding of the aromatic acids in the DOM to reactive mineral surfaces is a dominant source for long-term soil carbon stabilization in these soils. This potentially globally significant carbon sink may be unresponsive to climate change over decadal to centennial timescales due to strong particle sorption via carboxyl-rich functionalities.

  5. Thermodynamics of the complexation of arabinogalactan with salicylic and p-aminobenzoic acids in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Mudarisova, R. Kh.; Badykova, L. A.

    2016-03-01

    The thermodynamics of complexation of arabinogalactan with salicylic and p-aminobenzoic acids in aqueous solutions is studied by means spectroscopy. The standard thermodynamic characteristics (Δ H°; Δ G°; Δ S°) of complexation are calculated.

  6. Effect of citric acid on the acidification of artificial pepsin solution for metacercariae isolation from fish.

    PubMed

    Kim, Min-Ki; Pyo, Kyoung-Ho; Hwang, Young-Sang; Chun, Hyang Sook; Park, Ki Hwan; Ko, Seong-Hee; Chai, Jong-Yil; Shin, Eun-Hee

    2013-11-15

    Artificial digestive solution based on pepsin is essential for collecting metacercariae from fish. To promote the enzymatic reactivity of pepsin, the pH of the solution has to be adjusted to pH 1.0-2.0. Hydrochloride (HCl) is usually used for this purpose, but the use of HCl raises safety concerns. The aim of this work was to address the usefulness of citric acid as an alternative for HCl for the acidification of pepsin solution, and to examine its potential to damage metacercariae during in vitro digestion as compared with HCl. Changes in pH after adding 1-9% of citric acid (m/v) to pepsin solution were compared to a 1% HCl (v/v) addition. Digestion of fish muscle was evaluated by measuring released protein concentrations by spectrophotometry. In addition, survival rates of metacercariae in pepsin solution were determined at different citric acid concentrations and were compared that of with 1% HCl. The present study shows that addition of citric acid reduced the pH of pepsin solutions to the required level. Addition of more than 5% of citric acid resulted in the effective digestion of fish muscle over 3h in vitro, and 5% citric acid was less lethal to metacercariae than 1% HCl in pepsin solution. Pepsin solution containing 5% citric acid had digestive capacity superior to pepsin solution containing 1% HCl after 3h incubation with released protein concentrations of 12.0 ng/ml for 5% citric acid and 9.6 ng/ml for 1% HCl. Accordingly, the present study suggests that the addition of 5% citric acid to pepsin solution is a good alternative to 1% HCl in infection studies because citric acid is a stable at room temperature and has a good safety profile. In addition, we suggest that the use of citric acid enables the preparation of commercial digestive solutions for the detection of microorganisms in fish and other vertebrate muscle tissue. PMID:23993798

  7. Fabrication of carbon nanowires by pyrolysis of aqueous solution of sugar within asbestos nanofibers

    NASA Astrophysics Data System (ADS)

    Butko, V. Yu.; Fokin, A. V.; Nevedomskii, V. N.; Kumzerov, Yu. A.

    2015-05-01

    Carbon nanowires have been fabricated by pyrolysis of an aqueous solution of sugar in nanochannels of asbestos fibers. Electron microscopy demonstrates that the diameter of these nanochannels corresponds to the diameter of the thinnest of the carbon nanowires obtained. Some of these nanowires have a graphite crystal lattice and internal pores. After asbestos is etched out, the carbon nanowires can retain the original shape of the asbestos fibers. Heating in an inert atmosphere reduces the electrical resistivity of the carbon nanowires to ˜0.035 Ω cm.

  8. Thermodynamic and Ultrasonic Properties of Ascorbic Acid in Aqueous Protic Ionic Liquid Solutions

    PubMed Central

    Singh, Vickramjeet; Sharma, Gyanendra; Gardas, Ramesh L.

    2015-01-01

    In this work, we report the thermodynamic and ultrasonic properties of ascorbic acid (vitamin C) in water and in presence of newly synthesized ammonium based protic ionic liquid (diethylethanolammonium propionate) as a function of concentration and temperature. Apparent molar volume and apparent molar isentropic compression, which characterize the solvation state of ascorbic acid (AA) in presence of protic ionic liquid (PIL) has been determined from precise density and speed of sound measurements at temperatures (293.15 to 328.15) K with 5 K interval. The strength of molecular interactions prevailing in ternary solutions has been discussed on the basis of infinite dilution partial molar volume and partial molar isentropic compression, corresponding volume of transfer and interaction coefficients. Result has been discussed in terms of solute-solute and solute-solvent interactions occurring between ascorbic acid and PIL in ternary solutions (AA + water + PIL). PMID:26009887

  9. Thermodynamic and ultrasonic properties of ascorbic Acid in aqueous protic ionic liquid solutions.

    PubMed

    Singh, Vickramjeet; Sharma, Gyanendra; Gardas, Ramesh L

    2015-01-01

    In this work, we report the thermodynamic and ultrasonic properties of ascorbic acid (vitamin C) in water and in presence of newly synthesized ammonium based protic ionic liquid (diethylethanolammonium propionate) as a function of concentration and temperature. Apparent molar volume and apparent molar isentropic compression, which characterize the solvation state of ascorbic acid (AA) in presence of protic ionic liquid (PIL) has been determined from precise density and speed of sound measurements at temperatures (293.15 to 328.15) K with 5 K interval. The strength of molecular interactions prevailing in ternary solutions has been discussed on the basis of infinite dilution partial molar volume and partial molar isentropic compression, corresponding volume of transfer and interaction coefficients. Result has been discussed in terms of solute-solute and solute-solvent interactions occurring between ascorbic acid and PIL in ternary solutions (AA + water + PIL). PMID:26009887

  10. Behaviors of acrylamide/itaconic acid hydrogels in uptake of uranyl ions from aqueous solutions

    SciTech Connect

    Karadag, E.; Saraydin, D.; Gueven, O.

    1995-12-01

    In this study, adsorptions of uranyl ions from two different aqueous uranyl solutions by acrylamide-itaconic acid hydrogels were investigated by a spectroscopic method. The hydrogels were prepared by irradiating with {gamma}-radiation. In the experiment of uranyl ions adsorption, Type II adsorption was found. One gram of acrylamide-itaconic acid hydrogels sorbed 178-219 mg uranyl ions from the solutions of uranyl acetate, 42-76 mg uranyl ions from the aqueous solutions of uranyl nitrate, while acrylamide hydrogel did not sorb any uranyl ion. For the hydrogel containing 40 mg of itaconic acid and irradiated to 3.73 kGy, swelling of the hydrogels was observed in water (1660%), in the aqueous solution of uranyl acetate (730%), and in the aqueous solution of uranyl nitrate (580%). Diffusions of water onto hydrogels were a non-Fickian type of diffusion, whereas diffusions of uranyl ions were a Fickian type of diffusion.

  11. Branched chain amino acid-enriched solutions in the septic patient. A randomized, prospective trial.

    PubMed Central

    Bower, R H; Muggia-Sullam, M; Vallgren, S; Hurst, J M; Kern, K A; LaFrance, R; Fischer, J E

    1986-01-01

    A prospective, randomized trial was undertaken to compare the nutritional efficacy in surgical stress of a standard amino acid solution and two branched chain-enriched amino acid solutions: one enriched primarily with valine, the other with leucine. The study comprised 37 patients in the surgical intensive care unit who received isocaloric, isonitrogenous parenteral nutrition started within 24 hours of the onset of major operation, injury, or sepsis. Nitrogen retention was marginally but statistically significantly better on days 5, 7, and 10 in both groups of patients receiving the branched chain-enriched solutions, but differences in cumulative nitrogen balance were not statistically significant. Amino acid composition appeared to be important in that the group receiving the leucine-enriched solution appeared to maintain hepatic protein synthesis better (as manifest by higher short-turnover plasma protein concentrations) and required less exogenous insulin to maintain euglycemia. Improved outcome was not seen in the groups receiving the branched chain-enriched solutions. PMID:3079994

  12. Habit modification of calcium carbonate in the presence of malic acid

    SciTech Connect

    Mao Zhaofeng; Huang Jianhua

    2007-02-15

    The ability of malic acid to control calcium carbonate morphology has been investigated by aging calcium chloride solution in the presence of urea in a 90 deg. C bath. Malic acid favors the formation of calcite. A transition from single block to aggregate with special morphology occurs upon increasing malic acid concentration. The morphological development of CaCO{sub 3} crystal obviously depends on the starting pH. CaCO{sub 3} crystal grows from spindle seed to dumbbell in the pH regime from 7 to 11; while it evolves from spindle seed, through peanut, to sphere at pH=11.5. Both dumbbell and sphere consist of rods that are elongated along c-axis and capped with three smooth, well-defined rhombic {l_brace}1 0 4{r_brace} faces. A tentative growth mechanism is proposed based on the fractal model suggested by R. Kniep and S. Busch [Angew. Chem. Int. Ed. Engl. 35 (1996) 2624]. - Graphical abstract: Dumbbell-like CaCO{sub 3} particles obtained in the presence of malic acid.

  13. Perlwapin, an Abalone Nacre Protein with Three Four-Disulfide Core (Whey Acidic Protein) Domains, Inhibits the Growth of Calcium Carbonate Crystals

    PubMed Central

    Treccani, Laura; Mann, Karlheinz; Heinemann, Fabian; Fritz, Monika

    2006-01-01

    We have isolated a new protein from the nacreous layer of the shell of the sea snail Haliotis laevigata (abalone). Amino acid sequence analysis showed the protein to consist of 134 amino acids and to contain three sequence repeats of ?40 amino acids which were very similar to the well-known whey acidic protein domains of other proteins. The new protein was therefore named perlwapin. In addition to the major sequence, we identified several minor variants. Atomic force microscopy was used to explore the interaction of perlwapin with calcite crystals. Monomolecular layers of calcite crystals dissolve very slowly in deionized water and recrystallize in supersaturated calcium carbonate solution. When perlwapin was dissolved in the supersaturated calcium carbonate solution, growth of the crystal was inhibited immediately. Perlwapin molecules bound tightly to distinct step edges, preventing the crystal layers from growing. Using lower concentrations of perlwapin in a saturated calcium carbonate solution, we could distinguish native, active perlwapin molecules from denaturated ones. These observations showed that perlwapin can act as a growth inhibitor for calcium carbonate crystals in saturated calcium carbonate solution. The function of perlwapin in nacre growth may be to inhibit the growth of certain crystallographic planes in the mineral phase of the polymer/mineral composite nacre. PMID:16861275

  14. A comparative investigation on adsorption performances of mesoporous activated carbon prepared from waste rubber tire and activated carbon for a hazardous azo dye--Acid Blue 113.

    PubMed

    Gupta, V K; Gupta, Bina; Rastogi, Arshi; Agarwal, Shilpi; Nayak, Arunima

    2011-02-15

    A mesoporous carbon developed from waste tire rubber, characterized by chemical analysis, FTIR, and SEM studies, was used as an adsorbent for the removal and recovery of a hazardous azo dye, Acid Blue 113. Surface area, porosity, and density were determined. The adsorption of the dye over the prepared adsorbent and a commercial activated carbon was achieved under different pH, adsorbate concentration, sieve size, adsorbent dosage, contact time and temperature conditions. Langmuir and Freundlich adsorption isotherm models were applied and thermodynamic parameters were calculated. Kinetic studies indicated that the adsorption process follow first order kinetics and particle diffusion mechanisms are operative. By percolating the dye solution through fixed-bed columns the bulk removal of the Acid Blue 113 was carried out and necessary parameters were determined to find out the percentage saturation of both the columns. Recovery of the dye was made by eluting 0.1 M NaOH through the column. PMID:21163571

  15. Vapor-liquid equilibria for nitric acid-water and plutonium nitrate-nitric acid-water solutions

    SciTech Connect

    Maimoni, A.

    1980-01-01

    The liquid-vapor equilibrium data for nitric acid and nitric acid-plutnonium nitrate-water solutions were examined to develop correlations covering the range of conditions encountered in nuclear fuel reprocessing. The scanty available data for plutonium nitrate solutions are of poor quality but allow an order of magnitude estimate to be made. A formal thermodynamic analysis was attempted initially but was not successful due to the poor quality of the data as well as the complex chemical equilibria involved in the nitric acid and in the plutonium nitrate solutions. Thus, while there was no difficulty in correlating activity coefficients for nitric acid solutions over relatively narrow temperature ranges, attempts to extend the correlations over the range 25/sup 0/C to the boiling point were not successful. The available data were then analyzed using empirical correlations from which normal boiling points and relative volatilities can be obtained over the concentration ranges 0 to 700 g/l Pu, 0 to 13 M nitric acid. Activity coefficients are required, however, if estimates of individual component vapor pressures are needed. The required ternary activity coefficients can be approximated from the correlations.

  16. Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants

    PubMed Central

    PRADO, Maíra; da SILVA, Emmanuel João Nogueira Leal; DUQUE, Thais Mageste; ZAIA, Alexandre Augusto; FERRAZ, Caio Cezar Randi; de ALMEIDA, José Flávio Affonso; GOMES, Brenda Paula Figueiredo de Almeida

    2015-01-01

    Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. Objectives : The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. Material and Methods : The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Results : Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Conclusion : Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution). PMID:26018307

  17. Extraction of actinides into aqueous polyethylene glycol solutions from carbonate media in the presence of alizarin complexone

    SciTech Connect

    Molochnikova, N.P.; Frenkel', V.Ya.; Myasoedov, B.F.; Shkinev, V.M.; Spivakov, B.Ya.; Zolotov, Yu.A.

    1987-01-01

    Actinide extraction in a two-phase aqueous system based on polyethylene glycol from carbonate solutions of various compositions in presence of alizarin complexone is studied. It is shown that the nature of the alkali metals affects actinide extraction into the polyethylene glycol phase. Tri- and tetravalent actinides are extracted maximally from sodium carbonate solutions. Separation of actinides in different oxidation states is more effective in potassium carbonate solutions. The behavior of americium in different oxidation states in the system carbonate-polyethylene glycol-complexone is studied. The possibility of extraction separation of microamount of americium(V) from curium in carbonate solutions in presence of alizarin complexone is shown.

  18. Photoinduced crystallization of calcium carbonate from a homogeneous precursor solution in the presence of partially hydrolyzed poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Nishio, Takashi; Naka, Kensuke

    2015-04-01

    Photoinduced crystallization of calcium carbonate (CaCO3) was demonstrated by the photodecarboxylation of ketoprofen (KP, 2-(3-benzoylphenyl)propionic acid) under alkaline conditions (pH 10). In this method, a homogeneous solution comprising KP, calcium chloride, ammonia, and partially hydrolyzed poly(vinyl alcohol) (PVAPS, degree of saponification: 86.5-89.0 mol %) was used as the precursor solution and was exposed to ultraviolet (UV) irradiation for different time periods. Thermogravimetric analysis of the obtained xerogels showed that increasing the UV irradiation time increased the amount of CaCO3 formed and the complete conversion of calcium ions to calcite was achieved after 50 min of UV irradiation. Furthermore, solid phase analyses suggested that nanometer-to-micron-sized calcite crystals were formed and dispersed in the obtained PVAPS matrix. Photoinduced crystallization of CaCO3 from homogenous solution was demonstrated. 2-(3-benzoylphenyl)propionic acid was used as a photoreactive CO2 generator. Partially hydrolyzed poly(vinyl alcohol) worked as a stabilizer in the solution. Complete conversion of Ca2+ to CaCO3 was achieved by UV irradiation for 50 min. Nanometer-to-micron-sized calcites dispersed in the poly(vinyl alcohol) matrix.

  19. Simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid using polybromothymol blue film-modified glassy carbon electrode.

    PubMed

    Xu, Xiongwei; Lin, Qihuang; Liu, Ailin; Chen, Wei; Weng, Xiuhua; Wang, Changlian; Lin, Xinhua

    2010-06-01

    A sensitive and selective electrochemical method for simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) using an electropolymerized bromothymol blue (BTB)-modified glassy carbon electrode (GCE) was developed. The electrochemically synthesized film was investigated using electrochemical impedance spectroscopy and voltammetric methods. The electrochemical behavior of the polymer-modified electrode depends on film thickness, i.e., the electropolymyerization time. The poly-BTB-modified GCE shows excellent electrocatalytic activity toward the oxidation of AA, DA, and UA in phosphate buffer solution (pH 5.0). The voltametric peak separations of AA/DA, DA/UA, and AA/UA on this modified electrode are 118 mV, 298 mV, and 455 mV, respectively. Therefore the voltammetric responses of these three compounds can be resolved well on the polymer-modified electrode, and simultaneous determination of these three compounds can be achieved. In addition, this modified electrode can be successfully applied to determine AA and DA in injection and UA in urine samples without interference. PMID:20522988

  20. Interfacial structures of acidic and basic aqueous solutions

    SciTech Connect

    Tian, C.; Ji, N.; Waychunas, G.; Shen, Y.R.

    2008-10-20

    Phase-sensitive sum-frequency vibrational spectroscopy was used to study water/vapor interfaces of HCl, HI, and NaOH solutions. The measured imaginary part of the surface spectral responses provided direct characterization of OH stretch vibrations and information about net polar orientations of water species contributing to different regions of the spectrum. We found clear evidence that hydronium ions prefer to emerge at interfaces. Their OH stretches contribute to the 'ice-like' band in the spectrum. Their charges create a positive surface field that tends to reorient water molecules more loosely bonded to the topmost water layer with oxygen toward the interface, and thus enhances significantly the 'liquid-like' band in the spectrum. Iodine ions in solution also like to appear at the interface and alter the positive surface field by forming a narrow double-charge layer with hydronium ions. In NaOH solution, the observed weak change of the 'liquid-like' band and disappearance of the 'ice-like' band in the spectrum indicates that OH{sup -} ions must also have excess at the interface. How they are incorporated in the interfacial water structure is however not clear.

  1. USE OF STABLE CARBON ISOTOPE RATIOS OF FATTY ACIDS TO EVALUATE MICROBIAL CARBON SOURCES IN TERRESTRIAL ENVIRONMENTS

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (D 13C) of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels and microbial carbon source. We found that intensive sugar cane cultivation leads to ...

  2. USE OF THE COMPOSITION AND STABLE CARBON ISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (Gamma 13C) of individual microbial phospholipid fatty acids (PLFAS) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SO...

  3. Solution-reactor-produced Mo-99 using activated carbon to remore I-131

    SciTech Connect

    Kitten, S.; Cappiello, C.

    1998-06-01

    The production of {sup 99}Mo in a solution reactor was explored. Activated charcoal was used to filter the {sup 131}I contaminant from an irradiated fuel solution. Gamma spectroscopy confirmed that the activated carbon trapped a significant amount of {sup 131}I, as well as notable amounts of {sup 133}Xe, {sup 105}Rb, and {sup 140}Ba; the carbon trapped a diminutive amount of {sup 99}Mo. The results promote the idea of solution-reactor-produced {sup 99}Mo. Solution reactors are favorable both energetically and environmentally. A solution reactor could provide enough {sup 99}Mo/{sup 99m}Te to support both the current and future radiopharmaceutical needs of the U.S.

  4. 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, ?-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

  5. Corrosion Testing of Carbon Steel in Oxalic Acid that Contains Dissolved Iron

    SciTech Connect

    Wiersma, Bruce J.; Mickalonis, John I.; Subramanian, Karthik H.

    2012-10-11

    Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid (OA) will be used to chemically clean the tanks after waste retrieval is completed. The waste tanks at SRS were constructed from carbon steel materials and thus are vulnerable to corrosion in acidic media. In addition to structural impacts, the impact of corrosion on the hydrogen generated during the process must be assessed. Electrochemical and coupon immersion tests were used to investigate the corrosion mechanism at anticipated process conditions. The testing showed that the corrosion rates were dependent upon the reduction of the iron species that had dissolved in solution. Initial corrosion rates were elevated due to the reduction of the ferric species to ferrous species. At later times, as the ferric species depleted, the corrosion rate decreased. On the other hand, the hydrogen evolution reaction became more dominant.

  6. Fate of microbial nitrogen, carbon, hydrolysable amino acids, monosaccharides, and fatty acids in sediment

    NASA Astrophysics Data System (ADS)

    Veuger, Bart; van Oevelen, Dick; Middelburg, Jack J.

    2012-04-01

    The fate of microbial carbon, nitrogen, hydrolysable amino acids (HAAs), monosaccharides, and fatty acids in sediment was investigated experimentally. The microbial community of a tidal flat sediment was labeled with 13C-enriched glucose and 15N-enriched ammonium, and sediment was incubated for up to 371 days. Analysis of total concentrations and 13C- and 15N content of bulk sediment, hydrolysable amino acids (including D-alanine), monosaccharides, total fatty acids (TFAs), and phospholipid-derived fatty acids (PLFAs) allowed us to trace the fate of microbial biomass and -detritus and the major biochemical groups therein (proteins, carbohydrates, and lipids) over intermediate time scales (weeks-months). Moreover, the unidentified fraction of the labeled material (i.e. not analyzed as HAA, FA, or carbohydrate) provided information on the formation and fate of molecularly uncharacterizable organic matter. Loss of 13C and 15N from the sediment was slow (half live of 433 days) which may have been due to the permanently anoxic conditions in the experiment. Loss rates for the different biochemical groups were also low with the following order of loss rate constants: PLFA > TFA > HAA > monosaccharides. The unidentified 13C-pool was rapidly formed (within days) and then decreased relatively slowly, resulting in a gradual relative accumulation of this pool over time. Degradation and microbial reworking of the labeled material resulted in subtle, yet consistent, diagenetic changes within the different biochemical groups. In the HAA pool, glycine, lysine, and proline were lost relatively slowly (i.e. best preserved) while there was no accumulation of D-alanine relative to L-alanine, indicating no relative accumulation of bacterial macromolecules rich in D-alanine. In the fatty acid pool, there was very little difference between PLFAs and TFAs, indicating a very similar lability of these pools. Differences between individual fatty acids included a relatively slow loss of i15:0, ai15:0 and 18:1?7c which likely resulted from production of these bacterial fatty acids during bacterial reworking of the organic matter. Differences between loss rate constants for individual monosaccharides were not significant. An exception was ribose that was produced and lost relatively rapidly, which may be related to ribose being an important component of RNA. Losses of bulk 13C and 15N were closely coupled despite partly being present in different biochemicals and partly being derived from different microbial sources, indicating no selective preservation of either C or N during organic matter diagenesis.

  7. Method for extracting lanthanides and actinides from acid solutions by modification of Purex solvent

    DOEpatents

    Horwitz, E.P.; Kalina, D.G.

    1984-05-21

    A process has been developed for the extraction of multivalent lanthanide and actinide values from acidic waste solutions, and for the separation of these values from fission product and other values, which utilizes a new series of neutral bi-functional extractants, the alkyl(phenyl)-N, N-dialkylcarbamoylmethylphosphine oxides, in combination with a phase modifier to form an extraction solution. The addition of the extractant to the Purex process extractant, tri-n-butylphosphate in normal paraffin hydrocarbon diluent, will permit the extraction of multivalent lanthanide and actinide values from 0.1 to 12.0 molar acid solutions.

  8. The amino acid's backup bone - storage solutions for proteomics facilities.

    PubMed

    Meckel, Hagen; Stephan, Christian; Bunse, Christian; Krafzik, Michael; Reher, Christopher; Kohl, Michael; Meyer, Helmut Erich; Eisenacher, Martin

    2014-01-01

    Proteomics methods, especially high-throughput mass spectrometry analysis have been continually developed and improved over the years. The analysis of complex biological samples produces large volumes of raw data. Data storage and recovery management pose substantial challenges to biomedical or proteomic facilities regarding backup and archiving concepts as well as hardware requirements. In this article we describe differences between the terms backup and archive with regard to manual and automatic approaches. We also introduce different storage concepts and technologies from transportable media to professional solutions such as redundant array of independent disks (RAID) systems, network attached storages (NAS) and storage area network (SAN). Moreover, we present a software solution, which we developed for the purpose of long-term preservation of large mass spectrometry raw data files on an object storage device (OSD) archiving system. Finally, advantages, disadvantages, and experiences from routine operations of the presented concepts and technologies are evaluated and discussed. This article is part of a Special Issue entitled: Computational Proteomics in the Post-Identification Era. Guest Editors: Martin Eisenacher and Christian Stephan. PMID:23722089

  9. A pharmaceutical product as corrosion inhibitor for carbon steel in acidic environments.

    PubMed

    Samide, Adriana

    2013-01-01

    A pharmaceutical product, Trimethoprim (TMP), IUPAC name: 5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine was investigated, as inhibitor to prevent carbon steel corrosion in acidic environments. The study was performed using weight loss and electrochemical measurements, in temperatures ranging between 25-55C. The surface morphology before and after corrosion of carbon steel in 1.0M HCl solution in the presence and absence of TMP was evaluated using scanning electron microscopy (SEM). The inhibition efficiency (IE) increased with the increasing of the inhibitor concentration, reaching a maximum value of 92% at 25C and 0.9mM TMP, and decreased with increasing temperature. The inhibition of carbon steel corrosion by TMP can be attributed to the adsorption ability of inhibitor molecules onto the reactive sites of the metal surface. The adsorption is spontaneous and it is best described by the Langmuir isotherm. The apparent activation energy (E(a)) for the corrosion process in the absence and presence of TMP was evaluated from Arrhenius equation, to elucidate its inhibitive properties. PMID:23043337

  10. Super acid processing of Single walled carbon nanotube (SWNT): effect of SWNT aspect Ratio on Macroscopic properties

    NASA Astrophysics Data System (ADS)

    Behabtu, Natnael; Ma, Anson; Tsentalovich, Dmitri; Young, Colin; Pasquli, Matteo

    2011-03-01

    Single walled carbon nanotubes are exceptional building blocks that combine great mechanical, electrical and thermal properties with low density. A number of processing techniques have been proposed to manufacture macroscopic articles made purely of carbon nanotubes. Superacid processing is the most flexible and promising of all since it allows dissolution of a wide range of carbon nanotube materials, including hundreds of micron long carpets. Here we show how SWNT aspect ratio influences the rheology (both shear and extensional) of SWNT/super acid solution. The longest SWNT (~ 10 microns as measured by cryo-TEM) are able to form stable, highly aligned fibrils under elongational flow. Fibrils thus made can be recovered and further characterized. These fibrils have some of the lowest resistivity of SWNT based material to date (160 ? m-cm). These materials can also be processed into conducting and transparent films via dip coating and vacuum filtration. Films made with the longest SWNT gave a sheet resistance of 150 Ohm/sq at 90% transparency. We have also mixed long SWNT at high concentration (10 wt%) and, as expected, they form liquid crystalline solution. Surprisingly, we find that the viscosity of highly concentrated solution is not a function of the aspect ratio of the constitutive molecules (unlike dilute solutions). This allows for the high concentration solutions to be successfully spun into neat SWNT fibers.

  11. Reductive dehalogenation of hexachloroethane, carbon tetrachloride, and bromoform by anthrahydroquinone disulfonate and humic acid

    USGS Publications Warehouse

    Curtis, G.P.; Reinhard, M.

    1994-01-01

    The reductive dehalogenation of hexachloroethane (C2Cl6), carbon tetrachloride (CCl4), and bromoform (CHBr3) was examined at 50??C in aqueous solutions containing either (1) 500 ??M of 2,6-anthrahydroquinone disulfonate (AHQDS), (2) 250 ??M Fe2+, or (3) 250 ??M HS-. The pH ranged from 4.5 to 11.5 for AHQDS solutions and was 7.2 in the Fe2+ solutions and 7.8 in the HS- solutions. The observed disappearance of C2Cl6 in the presence of AHQDS was pseudo-first-order and fit k??ccl4 = k0[A(OH)2] + k1[A(OH)O-] + k2[A(O)22-] where A(OH)2, A(OH)O-, and A(O)22- represent the concentrations of the three forms of the AHQDS in solution. The values of k0, k1, and k2 were ???0,0.031, and 0.24 M-1 s-1, respectively. The addition of 25 mg of C/L of humic acid or organic matter extracted from Borden aquifer solids to aqueous solutions containing 250 ??M HS- or Fe2+ increased the reduction rate by factors of up to 10. The logarithms of the rate constants for the disappearance of C2Cl6 and CCl4 in seven different experimental systems were significantly correlated; log k???ccl4 = 0-64 log k??? c2cl6 - 0.83 with r2 = 0.80. The observed trend in reaction rates of C2Cl6 > CCl4 > CHBr3 is consistent with a decreasing trend in one-electron reduction potentials. ?? 1994 American Chemical Society.

  12. Time dependent inhibition of xanthine oxidase in irradiated solutions of folic acid, aminopterin and methotrexate

    SciTech Connect

    Robinson, K.; Pilot, T.F.; Meany, J.E. )

    1990-01-01

    The xanthine oxidase catalyzed oxidation of hypoxanthine was followed by monitoring the formation of uric acid at 290 nm. Inhibition of xanthine oxidase occurs in aqueous solutions of folic acid methotrexate and aminopterin. These compounds are known to dissociate upon exposure to ultraviolet light resulting in the formation of their respective 6-formylpteridine derivatives. The relative rates of dissociation were monitored spectrophotometrically by determining the absorbance of their 2,4-dinitrophenylhydrazine derivatives at 500 nm. When aqueous solutions of folic acid, aminopterin and methotrexate were exposed to uv light, a direct correlation was observed between the concentrations of the 6-formylpteridine derivatives existing in solution and the ability of these solutions to inhibit xanthine oxidase. The relative potency of the respective photolysis products were estimated.

  13. Growth behavior of anodic porous alumina formed in malic acid solution

    NASA Astrophysics Data System (ADS)

    Kikuchi, Tatsuya; Yamamoto, Tsuyoshi; Suzuki, Ryosuke O.

    2013-11-01

    The growth behavior of anodic porous alumina formed on aluminum by anodizing in malic acid solutions was investigated. High-purity aluminum plates were electropolished in CH3COOH/HClO4 solutions and then anodized in 0.5 M malic acid solutions at 293 K and constant cell voltages of 200-350 V. The anodic porous alumina grew on the aluminum substrate at voltages of 200-250 V, and a black, burned oxide film was formed at higher voltages. The nanopores of the anodic oxide were only formed at grain boundaries of the aluminum substrate during the initial stage of anodizing, and then the growth region extended to the entire aluminum surface as the anodizing time increased. The anodic porous alumina with several defects was formed by anodizing in malic acid solution at 250 V, and oxide cells were approximately 300-800 nm in diameter.

  14. Galvanic Corrosion of a Carbon Steel-Stainless Steel Couple in Sulfide Solutions

    NASA Astrophysics Data System (ADS)

    Dong, C. F.; Xiao, K.; Li, X. G.; Cheng, Y. F.

    2011-12-01

    The galvanic corrosion behavior of carbon steel-stainless steel couples with various cathode/anode area ratios was investigated in S 2--containing solutions, which were in equilibrium with air, by electrochemical measurements, immersion test, and surface characterization. It is found that the galvanic corrosion effect on carbon steel anode increases with the cathode/anode area ratios, and decreases with the increasing concentration of S2- in the solution. A layer of sulfide film is formed on carbon steel surface, which protects it from corrosion. When the cathode/anode area ratio is 1:1, the potentiodynamic polarization curve measurement and the weight-loss determination give the identical measurement of the galvanic corrosion effect. With the increase of the cathode/anode area ratio, the electrochemical method may not be accurate to determine the galvanic effect. The anodic dissolution current density of carbon steel cannot be approximated simply with the galvanic current density.

  15. Optoelectronic ally automated system for carbon nanotubes synthesis via arc-discharge in solution

    SciTech Connect

    Bera, Debasis; Brinley, Erik; Kuiry, Suresh C.; McCutchen, Matthew; Seal, Sudipta; Heinrich, Helge; Kabes, Bradley

    2005-03-01

    The method of arc discharge in the solution is unique and inexpensive route for synthesis of the carbon nanotubes (CNTs), carbon onions, and other carbon nanostructures. Such a method can be used for in situ synthesis of CNTs decorated with nanoparticles. Herein, we report a simple and inexpensive optoelectronically automated system for arc discharge in solution synthesis of CNTs. The optoelectronic system maintains a constant gap between the two electrodes allowing a continuous synthesis of the carbon nanostructures. The system operates in a feedback loop consisting of an electrode-gap detector and an analog electronic unit, as controller. This computerized feeding system of the anode was used for in situ nanoparticles incorporated CNTs. For example, we have successfully decorated CNTs with ceria, silica, and palladium nanoparticles. Characterizations of nanostructures are performed using high-resolution transmission electron microscopy, scanning transmission electron microscopy, energy dispersive spectroscopy, and scanning electron microscopy.

  16. Carbonized material adsorbents for the removal of mercury from aqueous solutions

    SciTech Connect

    Ishihara, S.; Pulido, L.L.; Kajimoto, T.

    1996-12-31

    Although wood has essentially been excluded as a starting material for the production of granular activated carbon because of the poor strength and friability of the products, powdered wood based activated carbons are still being used in water treatment and other liquid phase applications. However, the capability of powdered wood-based charcoal which in itself porous has not been fully known. Few studies have been conducted in harnessing its potential for adsorption purposes especially in water treatment. This study was conducted to investigate the possibility of using wood based carbonized materials from Sugi (Cryptomeria japonica D. Don) as adsorption materials in aqueous solutions of heavy metals like mercury, zinc, lead, cadmium and arsenic. However, of all the heavy metals investigated, mercury is considered to be the most toxic so this paper describes only the adsorption ability of the carbonized materials in adsorbing this metal from aqueous solutions of different concentrations.

  17. The effects of acidic fluoride solutions on early enamel erosion in vivo.

    PubMed

    Hjortsjö, C; Jonski, G; Thrane, P S; Saxegaard, E; Young, A

    2009-01-01

    Acidic fluoride solutions may reduce dental erosion. The aim of this study was to compare the effect of different acidic fluoride solutions on enamel dissolution using an established in vivo model. When possible 4 anterior teeth (255 teeth in a total of 67 subjects) were isolated and exposed to 0.01 M citric acid. The acid was collected in test tubes before (etch I) and 5 min after (etch II) application of test fluoride preparations. Acidic fluoride solutions (pH range 1.5-2.9), i.e. SnF(2), TiF(4) and hydrogen fluoride (HF) (all approx. 0.1 M F), HF (0.027, 0.055, 0.082 M F) and neutral NaF solution (0.1 M F) as control were applied to the labial surfaces of the teeth for 1 min (6 ml/min). Enamel dissolution was examined by chemical analysis of calcium content in the citric acid etch solutions using atom absorption spectrometry. The change in calcium concentration (DeltaCa) and the percentage of mean calcium reduction were calculated from the difference in calcium loss between etch I and etch II. Statistical analysis was carried out using the Wilcoxon signed rank test and Kruskal-Wallis tests with Dunn's multiple comparison. Results showed a mean DeltaCa of 0.671 mg/l (SD 0.625) for SnF(2), and ranged from 0.233 mg/l (SD 0.248) for the weakest HF solution to 0.373 mg/l (SD 0.310) for the strongest HF solution. This represented a 67% reduction in enamel dissolution for SnF(2) and a 40-76% reduction for the HF solutions. No reduction was observed for TiF(4) or NaF. The types of metal, pH and fluoride concentration are all important for the in vivo effect. PMID:19321990

  18. Solute-enhanced production of gamma-valerolactone (GVL) from aqueous solutions of levulinic acid

    DOEpatents

    Dumesic, James A; Wettstein, Stephanie G; Alonso, David Martin; Gurbuz, Elif Ispir

    2015-02-24

    A method to produce levulinic acid (LA) and gamma-valerolactone (GVL) from biomass-derived cellulose or lignocellulose by selective extraction of LA using GVL and optionally converting the LA so isolated into GVL, with no purifications steps required to yield the GVL.

  19. Sorption of perfluorooctanoic acid, perfluorooctane sulfonate and perfluoroheptanoic acid on granular activated carbon.

    PubMed

    Zhang, Di; Luo, Qi; Gao, Bin; Chiang, Sheau-Yun Dora; Woodward, David; Huang, Qingguo

    2016-02-01

    The sorption of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluoroheptanoic acid (PFHpA) on granular activated carbon (GAC) was characterized and compared to explore the underlying mechanisms. Sorption of the three perfluoroalkyl acids (PFAAs) on GAC appeared to be a rapid intra-particle diffusion process, which were well represented by the pseudo-second-order rate model with the sorption rate following the order PFOS > PFOA > PFHpA. Sorption isotherm data were well fitted by the Freundlich model with the sorption capacity (Kf) of PFOS, PFOA and PFHpA being 4.45, 2.42 and 1.66 respectively. This suggests that the hydrophilic head group on PFAAs, i.e. sulfonate vs carboxylic, has a strong influence on their sorption. Comparison between PFOA and PFHpA revealed that hydrophobicity could also play a role in the sorption of PFAAs on GAC when the fluorocarbon chain length is different. Analyses using Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR) spectroscopy suggested possible formation of a negative charge-assisted H-bond between PFAAs and the functionalities on GAC surfaces, including non-aromatic ketones, sulfides, and halogenated hydrocarbons. PMID:26606188

  20. Metabolic engineering of yeast to produce fatty acid-derived biofuels: bottlenecks and solutions

    PubMed Central

    Sheng, Jiayuan; Feng, Xueyang

    2015-01-01

    Fatty acid-derived biofuels can be a better solution than bioethanol to replace petroleum fuel, since they have similar energy content and combustion properties as current transportation fuels. The environmentally friendly microbial fermentation process has been used to synthesize advanced biofuels from renewable feedstock. Due to their robustness as well as the high tolerance to fermentation inhibitors and phage contamination, yeast strains such as Saccharomyces cerevisiae and Yarrowia lipolytica have attracted tremendous attention in recent studies regarding the production of fatty acid-derived biofuels, including fatty acids, fatty acid ethyl esters, fatty alcohols, and fatty alkanes. However, the native yeast strains cannot produce fatty acids and fatty acid-derived biofuels in large quantities. To this end, we have summarized recent publications in this review on metabolic engineering of yeast strains to improve the production of fatty acid-derived biofuels, identified the bottlenecks that limit the productivity of biofuels, and categorized the appropriate approaches to overcome these obstacles. PMID:26106371

  1. Electrochemical Determination of Uric Acid at CdTe Quantum Dot Modified Glassy Carbon Electrodes.

    PubMed

    Pan, Deng; Rong, Shengzhong; Zhang, Guangteng; Zhang, Yannan; Zhou, Qiang; Liu, Fenghai; Li, Miaojing; Chang, Dong; Pan, Hongzhi

    2015-01-01

    Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of uric acid (UA) at a CdTe quantum dot (QD) modified the glassy carbon electrode (GCE). CdTe QDs, as new semiconductor nanocrystals, can greatly improve the peak current of UA. The anodic peak current of UA was linear with its concentration between 1.010(-6) and 4.010(-4) M in 0.1 M pH 5.0 phosphate buffer solution. The LOD for UA at the CdTe electrode (1.010(-7) M) was superior to that of the GCE. In addition, we also determined the effects of scan rate, pH, and interferences of UA for the voltammetric behavior and detection. The results indicated that modified electrode possessed excellent reproducibility and stability. Finally, a new and efficient electrochemical sensor for detecting UA was developed. PMID:26525244

  2. Removal of copper and cadmium from the aqueous solutions by activated carbon derived from Ceiba pentandra hulls.

    PubMed

    Rao, M Madhava; Ramesh, A; Rao, G Purna Chandra; Seshaiah, K

    2006-02-28

    Activated carbon prepared from Ceiba pentandra hulls, an agricultural solid waste by-product, for the removal of copper and cadmium from aqueous solutions has been studied. Parameters such as equilibrium time, effect of pH and adsorbent dose on removal were studied. The adsorbent exhibited good sorption potential for copper and cadmium at pH 6.0. C=O and S=O functional groups present on the carbon surface were the adsorption sites to remove metal ions from solution. The experimental data was analysed by both Freundlich and Langmuir isotherm models. The maximum adsorption capacity of copper and cadmium was calculated from Langmuir isotherm and found to be 20.8 and 19.5 mg/g, respectively. The sorption kinetics of the copper and cadmium have been analysed by Lagergren pseudo-first-order and pseudo-second-order kinetic models. The desorption studies were carried out using dilute hydrochloric acid solution and the effect of HCl concentration on desorption was also studied. Maximum desorption of 90% for copper and 88% for cadmium occurred with 0.2 M HCl. PMID:16191464

  3. Ultrasonic Studies of 4-Aminobutyric Acid in Aqueous Metformin Hydrochloride Solutions at Different Temperatures

    NASA Astrophysics Data System (ADS)

    Rajagopal, K.; Jayabalakrishnan, S. S.

    2010-12-01

    Ultrasonic speeds and density data of 4-aminobutyric acid in 0.05 M, 0.10 M, and 0.15 M aqueous metformin hydrochloride (MFHCl) solutions are measured at 308.15 K, 313.15 K, and 318.15 K. The isentropic compressibility ( k S ), the change in isentropic compressibility (? k S ), the relative change in isentropic compressibility ({? k_S/k_S^0}), the apparent molal compressibility ({k_?}), the limiting apparent molal compressibility ({k_?^0 }), the transfer limiting apparent molal compressibility ({? k_?^0}), the hydration number ( n H), and the pair and triplet interaction parameters ( k AH, k AHH) are estimated. The above parameters are used to interpret the solute-solute and solute-solvent interactions of 4-aminobutyric acid in aqueous MFHCl solutions.

  4. Comparison of XAD macroporous resins for the concentration of fulvic acid from aqueous solution

    USGS Publications Warehouse

    Aiken, G.R.

    1979-01-01

    Five macroreticular, nonlonlc AmberlHe XAD resins were evaluated for concentration and Isolation of fulvlc acid from aqueous solution. The capacity of each resin for fulvlc acid was measured by both batch and column techniques. Elution efficiencies were determined by desorptlon with 0.1 N NaOH. Highest recoveries were obtained with the acrylic ester resins which proved to be most efficient for both adsorption and elution of fulvlc acid. Compared to the acrylic ester resins, usefulness of the styrene dvlnybenzene resins to remove fulvlc acid is limited because of slow diffusion-controlled adsorption and formation of charge-transfer complexes, which hinders elution. ?? 1979 American Chemical Society.

  5. Novel Petal Effect of Hafnia Films Prepared in an Aqueous Solution and Containing Hydroxy Acids

    NASA Astrophysics Data System (ADS)

    Tonosaki, Aki; Nishide, Toshikazu

    2010-12-01

    Transparent hafnia films containing glycolic acid or lactic acid as a hydroxy acid were successfully prepared in aqueous solutions. The films showed not only hydrophobicity but also high adhesive force to water droplets. The contact angles of the water droplets were 90-94. Droplets on the surface maintained their shapes even when the films were turned upside down. It is concluded that the water droplets were bonded to the surface by the hydrogen bonding force of the COOH and OH groups of glycolic acid on the hydrophobic hafnia films, resulting in a novel petal effect because of the flat film surface.

  6. Effects of solution chemistry and flow on the corrosion of carbon steel in sweet production

    SciTech Connect

    Herce, J.A.; Wright, E.J.; Efird, K.D.; Boros, J.A.; Hailey, T.G.

    1995-10-01

    The corrosion rate of AISI 1018 carbon steel was measured over a range of temperatures, CO{sub 2} partial pressures, flow rates, and solution chemistry under turbulent pipe flow conditions. The combined effects of CO{sub 2} partial pressure, ionic strength, temperature, and initial bicarbonate ion concentration, i.e., solution chemistry, may be described by a single variable, pH. The effects of flow can be combined with pH to form a new variable, hydrogen ion flux, to describe the overall effect of solution chemistry and flow on the sweet corrosion of a film free carbon steel surface. Sweet corrosion rates are directly proportional to hydrogen ion flux over a wide range of temperatures and solution pH`s. Finally, the separate effects of dissolved iron and chloride ion concentration are described.

  7. Precipitation pathways for ferrihydrite formation in acidic solutions

    DOE PAGESBeta

    Zhu, Mengqiang; Khalid, Syed; Frandsen, Cathrine; Wallace, Adam F.; Legg, Benjamin; Zhang, Hengzhong; Morup, Steen; Banfield, Jillian F.; Waychunas, Glenn A.

    2015-10-03

    In this study, iron oxides and oxyhydroxides form via Fe3+ hydrolysis and polymerization in many aqueous environments, but the pathway from Fe3+ monomers to oligomers and then to solid phase nuclei is unknown. In this work, using combined X-ray, UV–vis, and Mössbauer spectroscopic approaches, we were able to identify and quantify the long-time sought ferric speciation over time during ferric oxyhydroxide formation in partially-neutralized ferric nitrate solutions ([Fe3+] = 0.2 M, 1.8 < pH < 3). Results demonstrate that Fe exists mainly as Fe(H2O)63+, μ-oxo aquo dimers and ferrihydrite, and that with time, the μ-oxo dimer decreases while the othermore » two species increase in their concentrations. No larger Fe oligomers were detected. Given that the structure of the μ-oxo dimer is incompatible with those of all Fe oxides and oxyhydroxides, our results suggest that reconfiguration of the μ-oxo dimer structure occurs prior to further condensation leading up to the nucleation of ferrihydrite. The structural reconfiguration is likely the rate-limiting step involved in the nucleation process.« less

  8. Precipitation pathways for ferrihydrite formation in acidic solutions

    NASA Astrophysics Data System (ADS)

    Zhu, Mengqiang; Frandsen, Cathrine; Wallace, Adam F.; Legg, Benjamin; Khalid, Syed; Zhang, Hengzhong; Mørup, Steen; Banfield, Jillian F.; Waychunas, Glenn A.

    2016-01-01

    Iron oxides and oxyhydroxides form via Fe3+ hydrolysis and polymerization in many aqueous environments, but the pathway from Fe3+ monomers to oligomers and then to solid phase nuclei is unknown. In this work, using combined X-ray, UV-vis, and Mössbauer spectroscopic approaches, we were able to identify and quantify the long-time sought ferric speciation over time during ferric oxyhydroxide formation in partially-neutralized ferric nitrate solutions ([Fe3+] = 0.2 M, 1.8 < pH < 3). Results demonstrate that Fe exists mainly as Fe(H2O)63+, μ-oxo aquo dimers and ferrihydrite, and that with time, the μ-oxo dimer decreases while the other two species increase in their concentrations. No larger Fe oligomers were detected. Given that the structure of the μ-oxo dimer is incompatible with those of all Fe oxides and oxyhydroxides, our results suggest that reconfiguration of the μ-oxo dimer structure occurs prior to further condensation leading up to the nucleation of ferrihydrite. The structural reconfiguration is likely the rate-limiting step involved in the nucleation process.

  9. Precipitation pathways for ferrihydrite formation in acidic solutions

    SciTech Connect

    Zhu, Mengqiang; Khalid, Syed; Frandsen, Cathrine; Wallace, Adam F.; Legg, Benjamin; Zhang, Hengzhong; Morup, Steen; Banfield, Jillian F.; Waychunas, Glenn A.

    2015-10-03

    In this study, iron oxides and oxyhydroxides form via Fe3+ hydrolysis and polymerization in many aqueous environments, but the pathway from Fe3+ monomers to oligomers and then to solid phase nuclei is unknown. In this work, using combined X-ray, UV–vis, and Mössbauer spectroscopic approaches, we were able to identify and quantify the long-time sought ferric speciation over time during ferric oxyhydroxide formation in partially-neutralized ferric nitrate solutions ([Fe3+] = 0.2 M, 1.8 < pH < 3). Results demonstrate that Fe exists mainly as Fe(H2O)63+, μ-oxo aquo dimers and ferrihydrite, and that with time, the μ-oxo dimer decreases while the other two species increase in their concentrations. No larger Fe oligomers were detected. Given that the structure of the μ-oxo dimer is incompatible with those of all Fe oxides and oxyhydroxides, our results suggest that reconfiguration of the μ-oxo dimer structure occurs prior to further condensation leading up to the nucleation of ferrihydrite. The structural reconfiguration is likely the rate-limiting step involved in the nucleation process.

  10. A comparison of water solubility enhancements of organic solutes by aquatic humic materials and commercial humic acids

    USGS Publications Warehouse

    Chlou, C.T.; Kile, D.E.; Brinton, T.I.; Malcolm, R.L.; Leenheer, J.A.; MacCarthy, P.

    1987-01-01

    Water solubility enhancements of 1,1-bis(p-chloro-phenyl)-2,2,2-trichloroethane (p,p???-DDT), 2,4,5,2???,5???-pentachlorobiphenyl (2,4,5,2???,5???-PCB), and 2,4,4???-tri-chlorobiphenyl (2,4,4???-PCB) by dissolved organic matter have been studied with the following samples: (1) acidic water samples from the Suwannee River, Georgia, and the Sopchoppy River, Florida; (2) a humic extract of a nearly neutral pH water from the Calcasieu River, Louisiana; (3) commercial humic acids from the Aldrich Chemical Co. and Fluka-Tridom Chemical Corp. The calculated partition coefficients on a dissolved organic carbon basis (Kdoc) for organic solutes with water samples and aquatic humic extracts from this and earlier studies indicate that the enhancement effect varies with the molecular composition of the aquatic humic materials. The Kdoc values with water and aquatic humic samples are, however, far less than the observed Kdoc values obtained with the two commercial samples, by factors of about 4-20. In view of this finding, one should be cautious in interpreting the effects of the dissolved organic matter on solubility enhancement of organic solutes on the basis of the use of commercial humic acids.

  11. Solution and shock-induced exsolution of argon in vitreous carbon

    NASA Technical Reports Server (NTRS)

    Gazis, Carey; Ahrens, Thomas J.

    1991-01-01

    To add to the knowledge of noble gas solution and exsolution in carbonaceus material, experiments were performed on vitreous carbon. Ar-rich vitreous carbon samples were prepared under vapor-saturated conditions using argon as the pressurizing medium. Solubility data were obtained for temperatures of 773 to 973 K and pressures of 250 to 1500 bars. Up to 7 wt pct Ar was dissolved in the carbon. The solubility data were compared to a thermodynamic model of argon atoms dissolving into a fixed population of 'holes' in the carbon. Two variations of the model yielded estimates of the enthalpy of solution of Ar in vitreous carbon equal to about -4700 cal/mole. Preliminary shock experiments showed that 28 percent of the total argon was released by driving 4 GPa shocks into the argon-rich carbon. It was demonstrated that shock-induced argon loss is not simply caused by the impact-induced diminution of grain size. The present value of shock pressure required for partial impact devolatilization of Ar from carbon is below the range (5-30 GPa) at which H2O is released from phyllosilicates.

  12. Dynamic Rheological Studies of Poly(p-phenyleneterephthalamide) and Carbon Nanotube Blends in Sulfuric Acid

    PubMed Central

    Cao, Yutong; Liu, Zhaofeng; Gao, Xianghua; Yu, Junrong; Hu, Zuming; Liang, Ziqi

    2010-01-01

    We have studied the dynamic scanning of liquid-crystalline (LC) poly(p-phenyleneterephthalamide) sulfuric acid (PPTA-H2SO4) solution, and its blend with single-walled carbon nanotubes (SWNTs), by using a flat plate rotational rheometer. The effects of weight concentration and molecular weight of PPTA, as well as operating temperature, on dynamic viscoelasticity of the PPTA-H2SO4 LC solution system are discussed. The transition from a biphasic system to a single-phase LC occurs in the weight concentration range of SWNTs from 0.1% to 0.2%, in which complex viscosity reaches the maximum at 0.2 wt% and the minimum at 0.1 wt%, respectively, of SWNTs. With increasing SWNT weight concentration, the endothermic peak temperature increases from 73.6 to 79.9 °C. The PPTA/SWNT/H2SO4 solution is in its plateau zone and storage modulus (G′) is a dominant factor within the frequency (ω) range of 0.1–10 rad/s. As ω increases, the G′ rises slightly, in direct proportion to the ω. The loss modulus (G″) does not rise as a function of ω when ω < 1 s−1, then when ω > 1 s−1 G″ increases faster than G′, yet not in any proportion to the ω. PMID:20480024

  13. Evaluation of Hemostatic Effects of Carbonized Hair-Loaded Poly(L-Lactic) Acid Nanofabrics.

    PubMed

    Zhu, Yuanyuan; Qiu, Yan; Liao, Lianming

    2015-06-01

    Carbonized human hair is used to stop bleeding in traditional Chinese medicine. The present study was aimed to prepare a novel nanofiber containing carbonized human hair and evaluate its hemostatic effect. Carbonized human hair-loaded poly(L-lactic) acid nanofiber was prepared by electrospinning. The hemostatic efficacies of dressings composed of either carbonized human hair, carbonized human hair-loaded poly(L-lactic) acid nanofiber, Yunnan White Drug power or poly(L-lactic) acid nanofiber were investigated in several swine arterial and venous bleeding models. Blood loss and bleeding time were measured. In vitro, carbonized human hair, carbonized human hair-loaded nanofiber and Yunnan White Drug Powder significantly shortened the clotting time in comparison with the nanofiber control group. The hemostatic effects of the carbonized human hair-load nanofiber on liver and spleen traumatic wounds were better than those of carbonized human hair and Yunnan White Drug Powder in terms of blood loss and bleeding time. Similar effects were observed in swine femoral artery wound model. In the swine femoral vein wound model, bleeding could not be stopped in the control animals. In the carbonized human hair group, Yunnan White Drug Powder group and carbonized human hair-load nanofiber group, bleeding was stopped in 83.3%, 83.3% and 100% of the animals, respectively. In conclusion, dressing using carbonized human hair-load nanofibers is effective in controlling severe, uncontrolled bleeding. This dressing may offer a cheap alternative to dressings composed of coagulation proteins. PMID:26369029

  14. Basic solutions to carbon/carbon oxidation: Science and technology. Final report, 15 April 1993--14 April 1998

    SciTech Connect

    Harrison, I.R.; Chung, T.; Pantano, C.; Radovic, L.; Thrower, P.

    1998-04-14

    The goal of this study was to gain a fundamental understanding of the role of boron in carbon oxidation. Boron-doped carbons were synthesized via CVD, ion implantation and high temperature doping are subsequently characterized. It was found that high temperature doped HOPG carbons were ideal for oxidation studies because their surface could be reproduced, their surface structures were determined and they were able to be characterized by XPS, AFM and SEM. The direct analysis of the chemical structures and atomic arrangements in boron- doped carbon or carbon surfaces by these techniques was critical in determining the effect of boron on carbon oxidation. XPS was utilized in this work to determine the local bonding environment of boron in carbon before an after oxidation. It was necessary to obtain an accurate calibration of the B1s binding energy scale which was accomplished by obtaining photoemission spectra of boron-doped carbons with known structures (local boron bonding environments), such as boron oxide, boron carbide, triphenylboroxine, tourmaline, boric acid, danburite and high temperature boron-doped graphite. All of the aforementioned standards contain boron in a unique bonding environment and thus their spectra formulated a complete conversion of B1s binding energies to boron chemical environments which has not been reported in the past. It was clearly established that a chemical shift for substitutional boron in graphite exists at 186.5 eV with a FWHM of 1.2. The chemical structures of the boron in the standards were related to the binding energy using a Pauling charge distribution model and a modification of the Sanderson electronegativity method. This approach was used to determine whether the B1s binding energy would change depending upon the specific location of boron in the graphite or graphite surface.

  15. Infrared optical constants of H{sub 2}O ice, amorphous nitric acid solutions, and nitric acid hydrates

    SciTech Connect

    Toon, O.B.; Tolbert, M.A.; Koehler, B.G.

    1994-12-20

    The authors determined the infrared optical constants of nitric acid trihydrate, nitric acid dihydrate, nitric acid monohydrate, and solid amorphous nitric acid solutions which crystallize to form these hydrates. They have also found the infrared optical constants of H{sub 2}O ice. They measured the transmission of infrared light through thin films of varying thickness over the frequency range from about 7000 to 500 cm {sub {minus}1} at temperatures below 200 K. The authors developed a theory for the transmission of light through a substrate that has thin films on both sides. They used an iterative Kramers-Kronig technique to determine the optical constants which gave the best match between measured transmission spectra and those calculated for a variety of films of different thickness. These optical constants should be useful for calculations of the infrared spectrum of polar stratospheric clouds. 24 refs., 10 figs., 10 tabs.

  16. The effect of a new branched chain--enriched amino acid solution on postoperative catabolism.

    PubMed

    Kern, K A; Bower, R H; Atamian, S; Matarese, L E; Ghory, M J; Fischer, J E

    1982-10-01

    Branched-chain amino acids (BCAAs) may regulate muscle amino acid flux. Metabolic studies of both experimental animals and humans utilizing comparatively large amounts of BCAAs infused with hypocaloric glucose have shown that catabolism and proteolysis can be blunted. These studies suggested that the nitrogen-sparing properties of amino acid solutions used in postoperative trauma or sepsis might be improved by increasing the amount of BCAAs. This hypothesis was tested on ten patients undergoing operations of moderate severity utilizing a peripheral amino acid mixture with a branched-chain:non-branched-chain ratio of 45:55% given in 5% dextrose. The patients received 1.7 gm of protein equivalent/kg of ideal body weight in 5% dextrose-crystalloid solution with a concentration of 3.5% amino acids for the first 5 postoperative days. Nitrogen balance, 3-methylhistidine excretion, blood chemistries, and plasma amino acid profile tests were done daily. The results showed that nitrogen equilibrium was maintained for 5 postoperative days without any untoward effects on patients, their surgical wounds, or hepatic function. Plasma amino acids showed no significant changes from baseline with the exception of elevations of the BCAAs. We conclude that this 45% BCAA-enriched solution may be safely administered to patients with postoperative traumatic injury and results in nitrogen equilibrium over a 5-day period. PMID:6812232

  17. Effect of surface acidic oxides of activated carbon on adsorption of ammonia.

    PubMed

    Huang, Chen-Chia; Li, Hong-Song; Chen, Chien-Hung

    2008-11-30

    The influence of surface acidity of activated carbon (AC) was experimentally studied on adsorption of ammonia (NH(3)). Coconut shell-based AC was modified by various acids at different concentrations. There were five different acids employed to modified AC, which included nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid. Acidic functional groups on the surface of ACs were determined by a Fourier transform infrared spectrograph (FTIR) and by the Boehm titration method. Specific surface area and pore volume of the ACs were measured by a nitrogen adsorption apparatus. Adsorption amounts of NH(3) onto the ACs were measured by a dynamic adsorption system at room temperature according to the principle of the ASTM standard test method. The concentration of NH(3) in the effluent stream was monitored by a gas-detecting tube technique. Experimental results showed that adsorption amounts of NH(3) on the modified ACs were all enhanced. The ammonia adsorption amounts on various activated carbons modified by different acids are in the following order: nitric acid>sulfuric acid>acetic acid approximately phosphoric acid>hydrochloric acid. It is worth to note that the breakthrough capacity of NH(3) is linearly proportional to the amount of acidic functional groups of the ACs. PMID:18403110

  18. Changes in the Morphology and Proliferation of Astrocytes Induced by Two Modalities of Chemically Functionalized Single-Walled Carbon Nanotubes are Differentially Mediated by Glial Fibrillary Acidic Protein

    PubMed Central

    2015-01-01

    Alterations in glial fibrillary acidic protein (GFAP) levels accompany the changes in the morphology and proliferation of astrocytes induced by colloidal solutes and films of carbon nanotubes (CNTs). To determine if GFAP is required for the effects of CNTs on astrocytes, we used astrocytes isolated from GFAP null mice. We find that selected astrocytic changes induced by CNTs are mediated by GFAP, i.e., perimeter, shape, and cell death for solutes, and proliferation for films. PMID:24875845

  19. 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.

  20. Thermal transformation of trans-5-O-caffeoylquinic acid (trans-5-CQA) in alcoholic solutions.

    PubMed

    Dawidowicz, Andrzej L; Typek, Rafal

    2015-01-15

    Chlorogenic acid (CQA), the ester of caffeic acid with quinic acid supplied to human organisms mainly with coffee, tea, fruit and vegetables, has been one of the most studied polyphenols. It is potentially useful in pharmaceuticals, food additives, and cosmetics due to its recently discovered biomedical activity, which revived interest in its properties, isomers and natural occurrence. We found that the heating of the alcoholic solution of trans-5-O-caffeoylquinic acid produced at least twenty compounds (chlorogenic acid derivatives and its reaction products with water and alcohol). The formation of three of them (methoxy, ethoxy and propoxy adducts) has not been reported yet. No reports exist either on methoxy adducts of 3- and 4-O-caffeoylquinic acid appearing in buffered methanol/water mixtures at pH exceeding 7. We observed that the amount of each formed component depended on the heating time, type of alcohol, its concentration in alcoholic/water mixture, and pH. PMID:25148959

  1. Formation of amino acids by cobalt-60 irradiation of hydrogen cyanide solutions

    NASA Technical Reports Server (NTRS)

    Sweeney, M. A.; Toste, A. P.; Ponnamperuma, C.

    1976-01-01

    Experiments were conducted to study the pathway for the prebiotic origin of amino acids from hydrogen cyanide (HCN) under the action of ionizing radiation considered as an effective source of energy on the primitive earth. The irradiations were performed in a cobalt-60 source with a dose rate of 200,000 rad/hr. Seven naturally occurring amino acids are identified among the products formed by the hydrolysis of gamma-irradiated solutions of HCN: glycine, alanine, valine, serine, threonine, aspartic acid, and glutamic acid. The identity of these amino acids is established by gas chromatography and mass spectrometry. Control experiments provided evidence that the amino acids are not the result of contamination.

  2. Effect of Mineral Admixtures on Resistance to Sulfuric Acid Solution of Mortars with Quaternary Binders

    NASA Astrophysics Data System (ADS)

    Makhloufi, Zoubir; Bederina, Madani; Bouhicha, Mohamed; Kadri, El-Hadj

    This research consists to study the synergistic action of three mineral additions simultaneously added to the cement. This synergistic effect has a positive effect on the sustainability of limestone mortars. Tests were performed on mortars based on crushed limestone sand and manufactured by five quaternary binders (ordinary Portland cement and CPO mixed simultaneously with filler limestone, blast-furnace and natural pozzolan). The purpose of this research was to identify the resistance of five different mortars to the solution of sulfuric acid. Changes in weight loss and compressive strength measured at 30, 60, 90, 120 and 180 days for each acid solution were studied. We followed up on the change in pH of the sulfuric acid solution at the end of each month up to 180 days.

  3. The Formation and Stability of Carbonic Acid on Outer Solar System Bodies

    NASA Technical Reports Server (NTRS)

    Peeters, Z.; Hudson, R. L.; Moore, M. H.; Lewis, Ariel

    2009-01-01

    The radiation chemistry, thermal stability, and vapor pressure of solid-phase carbonic acid (H2CO3) have been studied with mid-infrared spectroscopy. A new procedure for measuring this molecule's radiation stability has been used to obtain intrinsic IR band strengths and half-lives for radiolytic destruction. Results are compared to literature values. We report, for the first time, measurements of carbonic acid's vapor pressure and its heat of sublimation. We also report the first observation of a chemical reaction involving solid-phase carbonic acid. Possible applications of these findings are discussed, with an emphasis on the outer Solar System.

  4. Carbon-13 NMR characterization of actinyl(VI) carbonate complexes in aqueous solution

    SciTech Connect

    Clark, D.L.; Hobart, D.E.; Palmer, P.D.; Sullivan, J.C.; Stout, B.E.

    1992-07-01

    The uranyl(VI) carbonate system has been re-examined using {sup 13}C NMR of 99.9% {sup 13}C-enriched U{sup VI}O{sub 2} ({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} in millimolar concentrations. By careful control of carbonate ion concentration, we have confirmed the existence of the trimer, and observed dynamic equilibrium between the monomer and the timer. In addition, the ligand exchange reaction between free and coordinated carbonate on Pu{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} and Am{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} systems has been examined by variable temperature {sup 13}C NMR line-broadening techniques {sup 13}C NMR line-broadening techniques. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was written to allow for experimental determination of ligand exchange parameters for paramagnetic actinide complexes. Preliminary Eyring analysis has provided activation parameters of {Delta}G{sup {double_dagger}}{sub 295} = 56 kJ/M, {Delta}H{sup {double_dagger}} = 38 kJ/M, and {Delta}S{sup {double_dagger}} = {minus}60 J/M-K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl (VI) carbonate complex self-exchange reaction. Experiments for determination of the activation parameters for the americium (VI) carbonate system are in progress.

  5. Synthesis of nanostructured carbon through ionothermal carbonization of common organic solvents and solutions.

    PubMed

    Chang, Yuanqin; Antonietti, Markus; Fellinger, Tim-Patrick

    2015-04-27

    A combination of ionothermal synthesis and hot-injection techniques leads to novel nanocarbons made from organic solvents. Controlled addition of commonly used organic solvents into a hot ZnCl2 melt gives rise to spherical, sheetlike, and branched nanofibrous carbon nanoparticles with surprisingly high carbon efficiency. When heteroatom-containing solvents were used, the doping levels reach up to 14?wt.?% nitrogen and 13?wt.?% sulfur. Materials with high surface areas and large pore volumes of solvent carbons as high as 1666?m(2) ?g(-1) and 2.80?cm(3) ?g(-1) in addition to CO2 adsorption capacities of 4.13?mmol?g(-1) at 273?K and 1?bar can be obtained. The new method works not only for pure carbon materials, but was also extended for the synthesis of carbon/inorganic nanocomposites. ZnS@C, Ni@C, and Co@C were successfully prepared with this straightforward procedure. The obtained Ni@C nanocomposites perform well in the electrocatalytic water oxidation, comparable with commercial noble-metal catalysts. PMID:25740456

  6. Studies on adsorption of mercury from aqueous solution on activated carbons prepared from walnut shell.

    PubMed

    Zabihi, M; Haghighi Asl, A; Ahmadpour, A

    2010-02-15

    The adsorption ability of a powdered activated carbons (PAC) derived from walnut shell was investigated in an attempt to produce more economic and effective sorbents for the control of Hg(II) ion from industrial liquid streams. Carbonaceous sorbents derived from local walnut shell, were prepared by chemical activation methods using ZnCl(2) as activating reagents. Adsorption of Hg(II) from aqueous solutions was carried out under different experimental conditions by varying treatment time, metal ion concentration, pH and solution temperature. It was shown that Hg(II) uptake decreases with increasing pH of the solution. The proper choice of preparation conditions were resulted in microporous activated carbons with different BET surface areas of 780 (Carbon A, 1:0.5 ZnCl(2)) and 803 (Carbon B, 1:1 ZnCl(2))m(2)/g BET surface area. The monolayer adsorption capacity of these particular adsorbents were obtained as 151.5 and 100.9 mg/g for carbons A and B, respectively. It was determined that Hg(II) adsorption follows both Langmuir and Freundlich isotherms as well as pseudo-second-order kinetics. PMID:19833433

  7. An analysis of electrical conductances of aqueous solutions of polybasic organic acids. Benzenehexacarboxylic (mellitic) acid and its neutral and acidic salts.

    PubMed

    Apelblat, Alexander; Bester-Rogac, Marija; Barthel, Josef; Neueder, Roland

    2006-05-01

    A general approach is proposed to analyze electrical conductivities in aqueous solutions of polybasic organic acids. Experimental conductivities are examined in the context of dissociation and hydrolysis reactions by applying the Quint-Viallard conductivity equations and the Debye-Hckel equations for activity coefficients. The proposed numerical procedure is illustrated by the case of benzenehexacarboxylic (mellitic) acid and its neutral and acidic salts. From conductivity measurements of mellitic acid and its salts, performed in dilute aqueous solutions in the 278.15-308.15 K temperature range, the limiting conductances of mellitic anions, lambda(0)(1/jH(6-j)Mel(-j), T), j = 1, 2, 3, 4, 5, 6 are determined. PMID:16640450

  8. Effect of Acid Oxidation on the Dispersion Property of Multiwalled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Goh, P. S.; Ismail, A. F.; Aziz, M.

    2009-06-01

    A means of dispersion of multiwalled carbon nanotube (MWCNT) via mixed acid (HNO3 and H2SO4) oxidation with different treatment durations was investigated through the solubility study of the treated carbon nanotubes in some common solvents. Fourier transformed infrared (FTIR) characterization of the reaction products revealed that the surface of MWCNTs was successfully functionalized with surface acidic groups. The acid-base titration demonstrated that the amount of surface acidic groups increased in parallel with the refluxing duration. The acid modified MWCNTs were found to be well dispersed in polar solvents, such as ethanol and water due to the presence of the hydrophilic acid functional groups on the surface of raw MWCNTs. Such chemical modification of carbon nanotube properties will pave the way towards the realistic applications in the nanotechnology world.

  9. Radiolysis of Bicarbonate and Carbonate Aqueous Solutions: Product Analysis and Simulation of Radiolytic Processes

    SciTech Connect

    Cai Zhongli; Li Xifeng; Katsumura, Yosuke; Urabe, Osamu

    2001-11-15

    An understanding of the radiation-induced effects in groundwater is essential to evaluate the safe geological disposal of spent fuel. In groundwater, the bicarbonate ion is the predominant and common anion; this work investigated radiation-induced chemical reactions of (bi)carbonate aqueous solutions with steady-state irradiation and pulse radiolysis methods. Aqueous solutions of sodium (bi)carbonate as high as 50 mmol.dm{sup -3} were used. The formation of formate, oxalate, and H{sub 2}O{sub 2} were measured under different conditions. A complete set of reaction steps and reliable kinetic data for the radiolysis of (bi)carbonate aqueous solutions at ionic strength close to the groundwater were proposed. Kinetic calculations were completed based on the proposed reaction steps and the kinetic data obtained in the present work. The results from the calculation are in good agreement with the experimental results. With these proposed reaction steps and kinetic data, computer simulation can be performed to predict the yield of radiolytic products of (bi)carbonate aqueous solutions as a function of irradiation time and used to evaluate the safety of geological disposal options of spent fuel.

  10. Sorption of metal ions from multicomponent aqueous solutions by activated carbons produced from waste

    SciTech Connect

    Tikhonova, L.P.; Goba, V.E.; Kovtun, M.F.; Tarasenko, Y.A.; Khavryuchenko, V.D.; Lyubchik, S.B.; Boiko, A.N.

    2008-08-15

    Activated carbons produced by thermal treatment of a mixture of sunflower husks, low-grade coal, and refinery waste were studied as adsorbents of transition ion metals from aqueous solutions of various compositions. The optimal conditions and the mechanism of sorption, as well as the structure of the sorbents, were studied.

  11. Chemical modification of amino acids by atmospheric-pressure cold plasma in aqueous solution

    NASA Astrophysics Data System (ADS)

    Takai, Eisuke; Kitamura, Tsuyoshi; Kuwabara, Junpei; Ikawa, Satoshi; Yoshizawa, Shunsuke; Shiraki, Kentaro; Kawasaki, Hideya; Arakawa, Ryuichi; Kitano, Katsuhisa

    2014-07-01

    Plasma medicine is an attractive new research area, but the principles of plasma modification of biomolecules in aqueous solution remain elusive. In this study, we investigated the chemical effects of atmospheric-pressure cold plasma on 20 naturally occurring amino acids in aqueous solution. High-resolution mass spectrometry revealed that chemical modifications of 14 amino acids were observed after plasma treatment: (i) hydroxylation and nitration of aromatic rings in tyrosine, phenylalanine and tryptophan; (ii) sulfonation and disulfide linkage formation of thiol groups in cysteine; (iii) sulfoxidation of methionine and (iv) amidation and ring-opening of five-membered rings in histidine and proline. A competitive reaction experiment using 20 amino acids demonstrated that sulfur-containing and aromatic amino acids were preferentially decreased by the plasma treatment. These data provide fundamental information for elucidating the mechanism of protein inactivation for biomedical plasma applications.

  12. CO2 adsorption on modified carbon coated monolith: effect of surface modification by using alkaline solutions

    NASA Astrophysics Data System (ADS)

    Hosseini, Soraya; Marahel, Ehsan; Bayesti, Iman; Abbasi, Ali; Chuah Abdullah, L.; Choong, Thomas S. Y.

    2015-01-01

    A monolithic column was used to study the feasibility of modified carbon-coated monolith for recovery of CO2 from gaseous mixtures (He/CO2) in a variety of operating conditions. Carbon-coated monolith was prepared by dip-coating method and modified by two alkaline solutions, i.e. NH3 and KOH. The surface properties of the carbon-coated monolith were altered by functional groups via KOH and NH3 treatments. The comparative study of CO2 uptake by two different adsorbents, i.e. unmodified and modified carbon-coated monolith, demonstrated that the applied modification process had improved CO2 adsorption. The presence of nitrogen- and oxygen-containing functional groups on the surface of the carbon led to an improved level of microporosity on the synthesized carbon-coated monolith. The physical parameters such as higher surface area, lower pore diameter, and larger micropore volume of modified monoliths indicated direct influence on the adsorbed amount of CO2. In the present study, the Deactivation Model is applied to analyze the breakthrough curves. The adsorption capacity increased with an increase in pressure and concentration, while a reduction of CO2 adsorption capacity was occurred with increase in temperature. Ammonia (NH3) and potassium hydroxide (KOH)-modified carbon-coated monolith showed an increase of approximately 12 and 27% in CO2 adsorption, respectively, as compared to unmodified carbon-coated monolith.

  13. Radiation-induced degradation of cyclohexanebutyric acid in aqueous solutions by gamma ray irradiation

    NASA Astrophysics Data System (ADS)

    Jia, Wenbao; He, Yanquan; Ling, Yongsheng; Hei, Daqian; Shan, Qing; Zhang, Yan; Li, Jiatong

    2015-04-01

    The radiation-induced degradation of cyclohexanebutyric acid under gamma ray irradiation was investigated. Degradation experiments were performed with 100 mL sealed Pyrex glass vessels loaded with 80 mL of cyclohexanebutyric acid solutions at various initial concentrations of 10, 20, and 40 mg L-1. The absorbed doses were controlled at 0, 0.65, 1.95, 3.25, 6.5, 9.75, and 13 kGy. The results showed that gamma ray irradiation could effectively degrade cyclohexanebutyric acid in aqueous solutions. The removal rate of cyclohexanebutyric acid increased significantly with the increase of absorbed dose and the decrease of its initial concentration. At the same time, the removal of chemical oxygen demand (COD) was as effective as that of cyclohexanebutyric acid. The kinetic studies showed that the degradation of cyclohexanebutyric acid followed pseudo first-order reaction. Above all, the proposed mechanism obtained when NaNO2, NaNO3 and tert-butanol were added showed that the OH radical played a major role in the gamma degradation process of cyclohexanebutyric acid, while H and eaq- played a minor role in the gamma degradation process. The degradation products were identified by Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS) during cyclohexanebutyric acid degradation.

  14. Feldspar dissolution in acidic and organic solutions: Compositional and pH dependence of dissolution rate

    SciTech Connect

    Welch, S.A.; Ullman, W.J.

    1996-08-01

    The steady-state dissolution rates of plagioclase feldspars into inorganic acid solutions in a flow-through reactor increased with Al content of the mineral from 1.4 {circ} 10{sup {minus}11} mol Si/m{sup 2}/s for albite to 5.6 {circ} 10{sup -9} mol Si/m{sup 2}/s for bytownite. A similar trend was observed for minerals dissolved in neutral solutions although the rates were lower. The results of these experiments are used to develop a simple empirical equation to describe the dissolution of tectosilicates (quartz + feldspars): R{sub H} = k{sub H}a{sup nH}{sub H+} where R{sub H} is the dissolution rate of tectosilicates in acid solution, a{sub H+} is the activity of H{sup +} ion, and k{sub H} and n{sub H} are dependent on the aluminum fraction in the tectosilicate framework [Al/Al + Si] : log k{sub H} = -11.24 + 25.98 * [Al/Al + Si]{sup 2} and n{sub H} = -0.052 + 4.23 * [Al/Al + Si]{sup 2}. This model, with its strong dependence on Al fraction, suggests that tectosilicate dissolution in acid solution results primarily from attack at Al sites at the mineral surface. In acidic oxalate solutions the steady-state dissolution rates were, in some cases, up to a factor of 10 higher than dissolution rates in inorganic solutions at the same pH and appeared to have a similar dependence on pH and mineral composition, at least away from the extremes in aluminum fraction (quartz and bytownite). The strong dependence of dissolution rate in acidic organic solutions on aluminum fraction indicates that both protons and ligands attack the mineral surface at the same, presumably Al, sites. 45 refs., 5 figs., 2 tabs.

  15. Phase equilibria in a system of aqueous arginine with an octane solution of sulfonic acid

    NASA Astrophysics Data System (ADS)

    Kuvaeva, Z. I.; Koval'chuk, I. V.; Vodop'yanova, L. A.; Soldatov, V. S.

    2013-05-01

    The extraction of arginine (Arg) from aqueous salt (0.1 M NaCl) solutions with a sulfo extractant in a wide range of pH values and amino acid concentrations was studied. The 0.1 M solution of dinonylnaphthalenesulfonic acid (HD) in octane was used as an extractant. The degree of extraction was found to be high at pH 0.8-9.0. This can be explained by the effect of additional intermolecular interactions in the extractant phase involving the guanidine group of Arg.

  16. 1,10,-phenanthroline as corrosion inhibitor for mild steel in sulfuric acid solution

    SciTech Connect

    Banerjee, S.N.; Misra, S. )

    1989-09-01

    This paper reports on 1,10,-Phenanthroline (Phen) examined as a corrosion inhibitor for mild steel in 1 N H{sub 2}SO{sub 4} acid solution by weight-loss and gasometric methods. Studies have also been made in 1 N HCl solution to compare the efficiency of the inhibitor in both acids. Activation energy in the presence and in the absence of the inhibitor has been evaluated. Galvanostatic polarization data indicate that the compound is predominantly a cathodic inhibitor.

  17. Stability of antimicrobial activity of peracetic acid solutions used in the final disinfection process.

    PubMed

    Costa, Solange Alves da Silva; Paula, Olívia Ferreira Pereira de; Silva, Célia Regina Gonçalves E; Leão, Mariella Vieira Pereira; Santos, Silvana Soléo Ferreira dos

    2015-01-01

    The instruments and materials used in health establishments are frequently exposed to microorganism contamination, and chemical products are used before sterilization to reduce occupational infection. We evaluated the antimicrobial effectiveness, physical stability, and corrosiveness of two commercial formulations of peracetic acid on experimentally contaminated specimens. Stainless steel specimens were contaminated with Staphylococcus aureus, Escherichia coli, Candida albicans, blood, and saliva and then immersed in a ready peracetic acid solution: 2% Sekusept Aktiv (SA) or 0.25% Proxitane Alpha (PA), for different times. Then, washes of these instruments were plated in culture medium and colony-forming units counted. This procedure was repeated six times per day over 24 non-consecutive days. The corrosion capacity was assessed with the mass loss test, and the concentration of peracetic acid and pH of the solutions were measured with indicator tapes. Both SA and PA significantly eliminated microorganisms; however, the SA solution was stable for only 4 days, whereas PA remained stable throughout the experiment. The concentration of peracetic acid in the SA solutions decreased over time until the chemical was undetectable, although the pH remained at 5. The PA solution had a concentration of 500-400 mg/L and a pH of 2-3. Neither formulation induced corrosion and both reduced the number of microorganisms (p = 0.0001). However, the differences observed in the performance of each product highlight the necessity of establishing a protocol for optimizing the use of each one. PMID:25715037

  18. An HPLC chromatographic framework to analyze the ?-cyclodextrin/solute complexation mechanism using a carbon nanotube stationary phase.

    PubMed

    Aljhni, Rania; Andre, Claire; Lethier, Lydie; Guillaume, Yves Claude

    2015-11-01

    A carbon nanotube (CNT) stationary phase was used for the first time to study the ?-cyclodextrin (?-CD) solute complexation mechanism using high performance liquid chromatography (HPLC). For this, the ?-CD was added at various concentrations in the mobile phase and the effect of column temperature was studied on both the retention of a series of aniline and benzoic acid derivatives with the CNT stationary phase and their complexation mechanism with ?-CD. A decrease in the solute retention factor was observed for all the studied molecules without change in the retention order. The apparent formation constant KF of the inclusion complex ?-CD/solute was determined at various temperatures. Our results showed that the interaction of ?-CD with both the mobile phase and the stationary phase interfered in the complex formation. The enthalpy and entropy of the complex formation (?HF and ?SF) between the solute molecule and CD were determined using a thermodynamic approach. Negative enthalpies and entropies indicated that the inclusion process of the studied molecule in the CD cavity was enthalpically driven and that the hydrogen bonds between carboxylic or aniline groups and the functional groups on the ?-CD rim play an important role in the complex formation. PMID:26452814

  19. Precipitation of calcium carbonate in aqueous solutions in presence of ethylene glycol and dodecane.

    NASA Astrophysics Data System (ADS)

    Natsi, Panagiota D.; Rokidi, Stamatia; Koutsoukos, Petros G.

    2015-04-01

    The formation of calcium carbonate (CaCO3) in aqueous supersaturated solutions has been intensively studied over the past decades, because of its significance for a number of processes of industrial and environmental interest. In the oil and gas production industry the deposition of calcium carbonate affects adversely the productivity of the wells. Calcium carbonate scale deposits formation causes serious problems in water desalination, CO2 sequestration in subsoil wells, in geothermal systems and in heat exchangers because of the low thermal coefficient of the salt. Amelioration of the operational conditions is possible only when the mechanisms underlying nucleation and crystal growth of calcium carbonate in the aqueous fluids is clarified. Given the fact that in oil production processes water miscible and immiscible hydrocarbons are present the changes of the dielectric constant of the fluid phase has serious impact in the kinetics of calcium carbonate precipitation, which remains largely unknown. The problem becomes even more complicated if polymorphism exhibited by calcium carbonate is also taken into consideration. In the present work, the stability of aqueous solutions supersaturated with respect to all calcium carbonate polymorphs and the subsequent kinetics of calcium carbonate precipitation were measured. The measurements included aqueous solutions and solutions in the presence of water miscible (ethylene glycol, MEG) and water immiscible organics (n-dodecane). All measurements were done at conditions of sustained supersaturation using the glass/ Ag/AgCl combination electrode as a probe of the precipitation and pH as the master variable for the addition of titrant solutions with appropriate concentration needed to maintenance the solution supersaturation. Initially, the metastable zone width was determined from measurements of the effect of the solution supersaturation on the induction time preceding the onset of precipitation at free-drift conditions. The rates of crystal growth were measured as a function of the solution supersaturation using the highly accurate and reproducible methodology of constant supersaturation. The dependence of the rates of crystal growth on supersaturation suggested surface diffusion controlled mechanism. At constant supersaturation it was possible to extend the time period for the growth of the initially forming polymorph, in a way that sufficient amount is precipitated for characterization with X-ray diffraction (XRD). Moreover, scanning electron microscopy (SEM) was used for the characterization of the morphology of the precipitated solid. In all cases and depending on the solution supersaturation vaterite formed first from solutions of high supersaturation while at low supersaturations calcite formed exclusively. The presence of dodecane reduced the stability of the supersaturated solutions with the crystals forming at the oil-water interface. The presence of ethylene glycol (concentrations between 10-80%) also affected the stability and the kinetics of calcium carbonate precipitation. The morphology of the formed crystals showed habit modifications: Spherical formations consisting of aggregated nanocrystals and calcite crystals with profound pits on the faces were the characteristic feature in the presence of dodecane. ACKNOWLEDGMENT This research was partially funded by the European Union (European Social Fund-ESF) and Greek National Funds through the Operational program Education and Lifelong Learning under the action Aristeia II( Code No 4420).

  20. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

    NASA Astrophysics Data System (ADS)

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-02-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA.

  1. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid.

    PubMed

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-01-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA. PMID:26924080

  2. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

    PubMed Central

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-01-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA. PMID:26924080

  3. Synthesis of finely divided molybdenum sulfide nanoparticles in propylene carbonate solution

    SciTech Connect

    Afanasiev, Pavel

    2014-05-01

    Molybdenum sulfide nanoparticles have been prepared from the reflux solution reaction involving ammonium heptamolybdate and elemental sulfur in propylene carbonate. Addition to the reaction mixture of starch as a natural capping agent leads to lesser agglomeration and smaller size of the particles. Nanoparticles of MoS{sub x} (x≈4) of 10–30 nm size are highly divided and form stable colloidal suspensions in organic solvents. Mo K edge EXAFS of the amorphous materials shows rapid exchange of oxygen to sulfur in the molybdenum coordination sphere during the solution reaction. Thermal treatment of the amorphous sulfides MoS{sub x} under nitrogen or hydrogen flow at 400 °C allows obtaining mesoporous MoS{sub 2} materials with very high pore volume and specific surface area, up to 0.45 cm{sup 3}/g and 190 m{sup 2}/g, respectively. The new materials show good potential for the application as unsupported hydrotreating catalysts. - Graphical abstract: Solution reaction in propylene carbonate allows preparing weakly agglomerated molybdenum sulfide with particle size 20 nm and advantageous catalytic properties. - Highlights: • Solution reaction in propylene carbonate yields MoS{sub x} particles near 20 nm size. • Addition of starch as capping agent reduces particles size and hinder agglomeration. • EXAFS at Mo K edge shows rapid oxygen to sulfur exchange in the solution. • Thermal treatment leads to MoS{sub 2} with very high porosity and surface area.

  4. Energetic stability of solute-carbon-vacancy complexes in bcc iron

    NASA Astrophysics Data System (ADS)

    Bakaev, Alexander; Terentyev, Dmitry; Zhurkin, Evgeny E.; Van Neck, Dimitri

    2015-06-01

    The strong binding between a vacancy and carbon in bcc iron plays an important role in the evolution of radiation-induced microstructure. Our previous ab initio study points to the fact that the vacancy-carbon (V-C) pair can serve as a nucleus for the solute-rich clusters. Here, we continue the ab initio study by considering the interaction of mixed solute clusters (Mn, Ni and Si) with the V-C pair, and the interaction of typical alloying elements of Fe-based steels (i.e., Mn, Ni, Cu, Si, Cr and P) with di-carbon-vacancy pair (V-C2). We have identified the sequence of growth of Ni, Si and Mn solute-rich clusters nucleating on the V-C pair. The mixed-solute-V-C configurations are found to be less stable clusters than pure-solute-V-C clusters with the energy difference up to 0.22 eV per four atoms. The V-C2 pair is found to be as strong nucleation site for the solute-rich clusters as the V-C pair. Only Si solute atom stands out from the trend showing a weaker affinity to the V-C2 complex by 0.09 eV compared to the attraction to the V-C pair. The overall results point to the importance of taking into account the existence of both V-C and V-C2 complexes in studying the formation of solute-rich clusters in Fe-based steels for nuclear applications.

  5. Adsorption of carbon dioxide by solution-plasma-synthesized heteroatom-doped carbon nanospheres

    NASA Astrophysics Data System (ADS)

    Thongwichit, Nanthiya; Li, Oi Lun Helena; Yaowarat, Wattanachai; Saito, Nagahiro; Suriyapraphadilok, Uthaiporn

    2016-01-01

    Porous carbon nanospheres (CNSs) synthesized by a plasma-in-liquid technique were applied as an adsorbent for CO2 adsorption. Two different types of aromatic solvents, benzene and pyridine, were used as precursors to generate CNSs. The prepared CNSs were carbonized and then activated with CO2 to obtain carbon materials with a suitable porous structure for CO2 adsorption. To improve CO2 adsorption capacity, activated CNSs were then chemically modified using different approaches of surface treatment, namely, HNO3 oxidation, amination without HNO3 preoxidation, and amination with HNO3 preoxidation. The CO2 adsorption capacities of the samples were investigated at 1 atm and 40 °C using a simultaneous thermal analyzer. It was found that the CO2 adsorption of CNSs was enhanced through the development of textural properties. All of the surface treatment approaches led to the increase in CO2 adsorption capacity of the activated CNSs owing to the presence of nitrogen or oxygen functional groups introduced onto the carbon surface during the treatment.

  6. Selective removal of cadmium from mixed metal solution by carbonate infusion

    SciTech Connect

    Cho, S.H.; Young, K.K. )

    1991-01-01

    The purpose of this study is to develop the technology of selective precipitation of a single metal from a mixed solution by carbonate infusion. Experiments were conducted in Pyrex reactors and jar testers. Synthetic wastewater of cadmium and copper mixed solution was used in this study. Initial cadmium and copper concentrations were 10{sup {minus}5}, 10{sup {minus}4}, 10{sup {minus}3} M, which are the concentrations commonly occurring in electroplating rinsewater. The effects of pH, carbonate concentration, and mixing rate on copper and cadmium hydrolysis were investigated. The optimum conditions of selective precipitation for the cadmium form mixed solutions were around pH 9, and the mixing rate was 100 rpm.

  7. Activated carbon fibers/poly(lactic-co-glycolic) acid composite scaffolds: preparation and characterizations.

    PubMed

    Shi, Yanni; Han, Hao; Quan, Haiyu; Zang, Yongju; Wang, Ning; Ren, Guizhi; Xing, Melcolm; Wu, Qilin

    2014-10-01

    The present work is a first trial to introduce activated carbon fibers (ACF) with high adsorption capacity into poly(lactic-co-glycolic) acid (PLGA), resulting in a novel kind of scaffolds for tissue engineering applications. ACF, prepared via high-temperature processing of carbon fibers, are considered to possess bioactivity and biocompatibility. The ACF/PLGA composite scaffolds are prepared by solvent casting/particulate leaching method. Increments in both pore quantity and quality over the surface of ACF as well as a robust combination between ACF and PLGA matrix are observed via scanning electron microscopy (SEM). The high adsorption capacity of ACF is confirmed by methylene blue solution absorbency test. The surfaces of ACF are affiliated with many hydrophilic groups and characterized by Fourier transform infrared spectroscopy. Furthermore, the SEM images show that cells possess a favorable spreading morphology on the ACF/PLGA scaffolds. Besides, vivo experiments are also carried out to evaluate the histocompatibility of the composite scaffolds. The results show that ACF have the potential to become one of the most promising materials in biological fields. PMID:25175194

  8. Photodegradation of Mercaptopropionic Acid- and Thioglycollic Acid-Capped CdTe Quantum Dots in Buffer Solutions.

    PubMed

    Miao, Yanping; Yang, Ping; Zhao, Jie; Du, Yingying; He, Haiyan; Liu, Yunshi

    2015-06-01

    CdTe quantum dots (QDs) were synthesized by 3-mercaptopropionic acid (MPA) and thioglycollic acid (TGA) as capping agents. It is confirmed that TGA and MPA molecules were attached on the surface of the QDs using Fourier transform infrared (FT-IR) spectra. The movement of the QDs in agarose gel electrophoresis indicated that MPA-capped CdTe QDs had small hydrodynamic diameter. The photoluminescence (PL) intensity of TGA-capped QDs is higher than that of MPA-capped QDs at same QD concentration because of the surface passivation of TGA. To systemically investigate the photodegradation, CdTe QDs with various PL peak wavelengths were dispersed in phosphate buffered saline (PBS) and Tris-borate-ethylenediaminetetraacetic acid (TBE) buffer solutions. It was found that the PL intensity of the QDs in PBS decreased with time. The PL peak wavelengths of the QDs in PBS solutions remained unchanged. As for TGA-capped CdTe QDs, the results of PL peak wavelengths in TBE buffer solutions indicated that S(2-) released by TGA attached to Cd(2+) and formed CdS-like clusters layer on the surface of aqueous CdTe QDs. In addition, the number of TGA on the CdTe QDs surface was more than that of MPA. When the QDs were added to buffer solutions, agents were removed from the surface of CdTe QDs, which decreased the passivation of agents thus resulted in photodegradation of CdTe QDs in buffer solutions. PMID:26369066

  9. Molten Carbonate and Phosphoric Acid Stationary Fuel Cells: Overview and Gap Analysis

    SciTech Connect

    Remick, R.; Wheeler, D.

    2010-09-01

    This report describes the technical and cost gap analysis performed to identify pathways for reducing the costs of molten carbonate fuel cell (MCFC) and phosphoric acid fuel cell (PAFC) stationary fuel cell power plants.

  10. First Molecular Dynamics simulation insight into the mechanism of organics adsorption from aqueous solutions on microporous carbons

    NASA Astrophysics Data System (ADS)

    Terzyk, Artur P.; Gauden, Piotr A.; Zieliński, Wojciech; Furmaniak, Sylwester; Wesołowski, Radosław P.; Klimek, Kamil K.

    2011-10-01

    The results of 84 MD simulations showing the influence of porosity and carbon surface oxidation on adsorption of three organic compounds from aqueous solutions on carbons are reported. Based on a model of 'soft' activated carbon, three carbon structures with gradually changed microporosity were created. Next, different number of surface oxygen groups was introduced. We observe quantitative agreement between simulation and experiment i.e. the decrease in adsorption from benzene down to paracetamol. Simulation results clearly demonstrate that the balance between porosity and carbon surface chemical composition in organics adsorption on carbons, and the pore blocking determine adsorption properties of carbons.

  11. Structural and functional characterization of solute binding proteins for aromatic compounds derived from lignin: p-coumaric acid and related aromatic acids

    PubMed Central

    Tan, Kemin; Chang, Changsoo; Cuff, Marianne; Osipiuk, Jerzy; Landorf, Elizabeth; Mack, Jamey C.; Zerbs, Sarah; Joachimiak, Andrzej; Collart, Frank R.

    2013-01-01

    Lignin comprises 15.25% of plant biomass and represents a major environmental carbon source for utilization by soil microorganisms. Access to this energy resource requires the action of fungal and bacterial enzymes to break down the lignin polymer into a complex assortment of aromatic compounds that can be transported into the cells. To improve our understanding of the utilization of lignin by microorganisms, we characterized the molecular properties of solute binding proteins of ATP.binding cassette transporter proteins that interact with these compounds. A combination of functional screens and structural studies characterized the binding specificity of the solute binding proteins for aromatic compounds derived from lignin such as p-coumarate, 3-phenylpropionic acid and compounds with more complex ring substitutions. A ligand screen based on thermal stabilization identified several binding protein clusters that exhibit preferences based on the size or number of aromatic ring substituents. Multiple X-ray crystal structures of protein-ligand complexes for these clusters identified the molecular basis of the binding specificity for the lignin-derived aromatic compounds. The screens and structural data provide new functional assignments for these solute.binding proteins which can be used to infer their transport specificity. This knowledge of the functional roles and molecular binding specificity of these proteins will support the identification of the specific enzymes and regulatory proteins of peripheral pathways that funnel these compounds to central metabolic pathways and will improve the predictive power of sequence-based functional annotation methods for this family of proteins. PMID:23606130

  12. Laboratory evaluation of limestone and lime neutralization of acidic uranium mill tailings solution. Progress report

    SciTech Connect

    Opitz, B.E.; Dodson, M.E.; Serne, R.J.

    1984-02-01

    Experiments were conducted to evaluate a two-step neutralization scheme for treatment of acidic uranium mill tailings solutions. Tailings solutions from the Lucky Mc Mill and Exxon Highland Mill, both in Wyoming, were neutralized with limestone, CaCO/sub 3/, to an intermediate pH of 4.0 or 5.0, followed by lime, Ca(OH)/sub 2/, neutralization to pH 7.3. The combination limestone/lime treatment methods, CaCO/sub 3/ neutralization to pH 4 followed by neutralization with Ca(OH)/sub 2/ to pH 7.3 resulted in the highest quality effluent solution with respect to EPA's water quality guidelines. The combination method is the most cost-effective treatment procedure tested in our studies. Neutralization experiments to evaluate the optimum solution pH for contaminant removal were performed on the same two tailings solutions using only lime Ca(OH)/sub 2/ as the neutralizing agent. The data indicate solution neutralization above pH 7.3 does not significantly increase removal of pH dependent contaminants from solution. Column leaching experiments were performed on the neutralized sludge material (the precipitated solid material which forms as the acidic tailings solutions are neutralized to pH 4 or above). The sludges were contacted with laboratory prepared synthetic ground water until several effluent pore volumes were collected. Effluent solutions were analyzed for macro ions, trace metals and radionuclides in an effort to evaluate the long term effectiveness of attenuating contaminants in sludges formed during solution neutralization. Neutralized sludge leaching experiments indicate that Ca, Na, Mg, Se, Cl, and SO/sub 4/ are the only constituents which show solution concentrations significantly higher than the synthetic ground water in the early pore volumes of long-term leaching studies.

  13. Direct analysis of oxidizing agents in aqueous solution with attenuated total reflectance mid-infrared spectroscopy and diamond-like carbon protected waveguides.

    PubMed

    Janotta, Markus; Vogt, Frank; Voraberger, Hannes-Stefan; Waldhauser, Wolfgang; Lackner, Jrgen M; Stotter, Christoph; Beutl, Michael; Mizaikoff, Boris

    2004-01-15

    A novel approach for the direct detection of oxidizing agents in aqueous solution is presented using diamond-like carbon (DLC) protected waveguides in combination with attenuated total reflectance (ATR) mid-infrared spectroscopy. Pulsed laser deposition was applied to produce high-quality DLC thin films on ZnSe ATR crystals with thicknesses of a few 100 nm. Scanning electron microscopy and X-ray photoelectron spectroscopy has been used to investigate the surface properties of the DLC films including the sp(3)/sp(2) hybridization ratio of the carbon bonds. Beside excellent adhesion of the DLC coatings to ZnSe crystals, these films show high chemical stability against strongly oxidizing agents. IR microscopy was utilized to compare differences in the chemical surface modification of bare and protected ATR waveguides when exposed to hydrogen peroxide, peracetic acid, and peroxydisulfuric acid. The feasibility of DLC protected waveguides for real-time concentration monitoring of these oxidizing agents was demonstrated by measuring calibration sets in a concentration range of 0.2-10%. Additionally, principal component regression has been applied to analyze multicomponent mixtures of hydrogen peroxide, acetic acid, and peracetic acid in aqueous solution. Due to high chemical stability and accurate monitoring capabilities, DLC protected waveguides represent a novel approach for directly detecting oxidizing agents in aqueous solution with promising potential for industrial process analysis. PMID:14719887

  14. Adipic and malonic acid aqueous solutions: surface tensions and saturation vapor pressures.

    PubMed

    Riipinen, Ilona; Koponen, Ismo K; Frank, Gran P; Hyvrinen, Antti-Pekka; Vanhanen, Joonas; Lihavainen, Heikki; Lehtinen, Kari E J; Bilde, Merete; Kulmala, Markku

    2007-12-20

    The surface tension of adipic aqueous solutions was measured as a function of temperature (T=278-313 K) and adipic acid mole fraction (X=0.000-0.003) using the Wilhelmy plate method. A parametrization fitted to these data is presented. The evaporation rates of binary water-malonic and water-adipic acid droplets were measured with a TDMA technique at different temperatures (T=293-300 K) and relative humidities (58-80%), and the saturation vapor pressures of subcooled liquid malonic and adipic acids were derived from the data using a binary evaporation model. The temperature dependence of the vapor pressures was obtained as least-squares fits to the derived vapor pressures: ln(Psat,l) (Pa)=220.2389-22634.96/T (K)-26.66767 ln T (K) for malonic acid and ln(Psat,l) (Pa)=140.6704-18230.97/T (K)-15.48011 ln T (K) for adipic acid. PMID:18044850

  15. Approximate Solutions for a Self-Folding Problem of Carbon Nanotubes

    SciTech Connect

    Y Mikata

    2006-08-22

    This paper treats approximate solutions for a self-folding problem of carbon nanotubes. It has been observed in the molecular dynamics calculations [1] that a carbon nanotube with a large aspect ratio can self-fold due to van der Waals force between the parts of the same carbon nanotube. The main issue in the self-folding problem is to determine the minimum threshold length of the carbon nanotube at which it becomes possible for the carbon nanotube to self-fold due to the van der Waals force. An approximate mathematical model based on the force method is constructed for the self-folding problem of carbon nanotubes, and it is solved exactly as an elastica problem using elliptic functions. Additionally, three other mathematical models are constructed based on the energy method. As a particular example, the lower and upper estimates for the critical threshold (minimum) length are determined based on both methods for the (5,5) armchair carbon nanotube.

  16. Effects of acidic deposition on the erosion of carbonate stone - experimental results from the U.S. National Acid Precipitation Assessment Program (NAPAP)

    USGS Publications Warehouse

    Baedecker, P.A.; Reddy, M.M.; Reimann, K.J.; Sciammarella, C.A.

    1992-01-01

    One of the goals of NAPAP-sponsored research on the effects of acidic deposition on carbonate stone has been to quantify the incremental effects of wet and dry deposition of hydrogen ion, sulfur dioxide and nitrogen oxides on stone erosion. Test briquettes and slabs of freshly quarried Indiana limestone and Vermont marble have been exposed to ambient environmental conditions in a long-term exposure program. Physical measurements of the recession of test stones exposed to ambient conditions at an angle of 30?? to horizontal at the five NAPAP materials exposure sites range from ~15 to ~30?? ??m yr-1 for marble, and from ~25 to ~45 ??m yr -1 for limestone, and are approximately double the recession estimates based on the observed calcium content of run-off solutions from test slabs. The difference between the physical and chemical recession measurements is attributed to the loss of mineral grains from the stone surfaces that are not measured in the run-off experiments. The erosion due to grain loss does not appear to be influenced by rainfall acidity, however, preliminary evidence suggests that grain loss may be influenced by dry deposition of sulfur dioxide between rainfall events. Chemical analyses of the run-off solutions and associated rainfall blanks suggest that ~30% of erosion by dissolution can be attributed to the wet deposition of hydrogen ion and the dry deposition of sulfur dioxide and nitric acid between rain events. The remaining ~70% of erosion by dissolution is accounted for by the solubility of carbonate stone in rain that is in equilibrium with atmospheric carbon dioxide ('clean rain'). These results are for marble and limestone slabs exposed at an angle of 30?? from horizontal. The relative contribution of sulfur dioxide to chemical erosion is significantly enhanced for stone slabs having an inclination of 60?? or 85??. The dry deposition of alkaline particulate material has a mitigating effect at the two urban field exposure sites at Washington, DC, and Steubenville, OH.

  17. A Functional Tricarboxylic Acid Cycle Operates during Growth of Bordetella pertussis on Amino Acid Mixtures as Sole Carbon Substrates

    PubMed Central

    Garnier, Dominique; Speck, Denis

    2015-01-01

    It has been claimed that citrate synthase, aconitase and isocitrate dehydrogenase activities are non-functional in Bordetella pertussis and that this might explain why this bacterium’s growth is sometimes associated with accumulation of polyhydroxybutyrate (PHB) and/or free fatty acids. However, the sequenced genome includes the entire citric acid pathway genes. Furthermore, these genes were expressed and the corresponding enzyme activities detected at high levels for the pathway when grown on a defined medium imitating the amino acid content of complex media often used for growth of this pathogenic microorganism. In addition, no significant PHB or fatty acids could be detected. Analysis of the carbon balance and stoichiometric flux analysis based on specific rates of amino acid consumption, and estimated biomass requirements coherent with the observed growth rate, clearly indicate that a fully functional tricarboxylic acid cycle operates in contrast to previous reports. PMID:26684737

  18. A Functional Tricarboxylic Acid Cycle Operates during Growth of Bordetella pertussis on Amino Acid Mixtures as Sole Carbon Substrates.

    PubMed

    Izac, Marie; Garnier, Dominique; Speck, Denis; Lindley, Nic D

    2015-01-01

    It has been claimed that citrate synthase, aconitase and isocitrate dehydrogenase activities are non-functional in Bordetella pertussis and that this might explain why this bacterium's growth is sometimes associated with accumulation of polyhydroxybutyrate (PHB) and/or free fatty acids. However, the sequenced genome includes the entire citric acid pathway genes. Furthermore, these genes were expressed and the corresponding enzyme activities detected at high levels for the pathway when grown on a defined medium imitating the amino acid content of complex media often used for growth of this pathogenic microorganism. In addition, no significant PHB or fatty acids could be detected. Analysis of the carbon balance and stoichiometric flux analysis based on specific rates of amino acid consumption, and estimated biomass requirements coherent with the observed growth rate, clearly indicate that a fully functional tricarboxylic acid cycle operates in contrast to previous reports. PMID:26684737

  19. Performance evaluation of trimethylamine-carbon dioxide thermolytic draw solution for engineered osmosis

    SciTech Connect

    Boo, C; Khalil, YF; Elimelech, M

    2015-01-01

    We evaluated the performance of trimethylamine-carbon dioxide (TMA-CO2) as a potential thermolytic draw solution for engineered osmosis. Water flux and reverse solute flux with TMA-CO2 draw solution were measured in forward osmosis (FO) and pressure retarded osmosis (PRO) modes using thin-film composite (TFC) and cellulose triacetate (CTA) FO membranes. Water flux with the TMA-CO2 draw solution was comparable to that obtained with the more common ammonia-carbon dioxide (NH3-CO2) thermolytic draw solution at similar (1 M) concentration. Using a TFC-FO membrane, the water fluxes produced by 1 M TMA-CO2 and NH3-CO2 draw solutions with a DI water feed were, respectively, 33.4 and 35.6 L m(-2) h(-1) in PRO mode and 14.5 and 152 L m(-2) h(-1) in FO mode. Reverse draw permeation of TMA-CO2 was relatively low compared to NH3-CO2, ranging from 0.1 to 0.2 mol m(-2) h(-1) in all experiments, due to the larger molecular size of TMA. Thermal separation and recovery efficiency for TMA-CO2 was compared to NH3-CO2 by modeling low-temperature vacuum distillation utilizing low-grade heat sources. We also discuss possible challenges in the use TMA-CO2, including potential adverse impact on human health and environments. (C) 2014 Elsevier B.V. All rights reserved.

  20. Citric Acid-Modified Fenton's Reaction for the Oxidation of Chlorinated Ethylenes in Soil Solution Systems

    SciTech Connect

    Seol, Yongkoo; Javandel, Iraj

    2008-03-15

    Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in-situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varying H{sub 2}O{sub 2} concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H{sub 2}O{sub 2} relative to iron catalysts (Fe{sup 2+}/H{sub 2}O{sub 2} < 1/330) would result in lowering the efficiency of contaminant removal by iron chelations in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.

  1. Controls of carbonate mineralogy and solid-solution of Mg in calcite: evidence from spelean systems

    SciTech Connect

    Gonzalez, L.A.; Lohmann, K.C.

    1985-01-01

    Precipitation of carbonate minerals in spelean systems occurs under a wide range of fluid chemistry, Mg-Ca ratios, alkalinities, pH and temperatures; thus, spelean systems provide ideal settings to determine factors controlling the mineralogy of precipitated carbonates and solid-solution of Mg in calcite. Cave waters and actively-precipitating carbonate speleothems were collected from Carlsbad Caverns National Park, New Mexico and the Mammoth-Flint Cave System, Kentucky. Carbonate mineralogy of precipitated phases was determined by x-ray diffraction, and major and minor element composition of waters and accompanying minerals were determined by Atomic Absorption Spectrophotometry. Results demonstrate that at a constant CO3 concentration the precipitation threshold for calcite to aragonite is controlled dominantly by the Mg/Ca ratio of the ambient fluid. Aragonite precipitation is favored by high Mg/Ca ratios. Conversely, with increasing CO3 concentration at constant fluid Mg/Ca ratios, calcite is preferentially precipitated. Solid-solution of Mg in calcite is positively correlated with both increased Mg/Ca ratios and CO3 concentrations. These data suggest that Mg contents of calcite can not be defined solely in terms of a homogeneous distribution coefficient. Rather, Mg concentrations can be also be affected by the CO3 concentration and degree of calcite saturation, suggesting that the rate of crystal growth also plays and important role in Mg solid-solution in calcites.

  2. Optimizing surfactant concentrations for dispersion of single-walled carbon nanotubes in aqueous solution.

    PubMed

    Blanch, Adam J; Lenehan, Claire E; Quinton, Jamie S

    2010-08-01

    The sonication-centrifugation technique is commonly used for dispersing single-walled carbon nanotubes (SWCNTs) in aqueous surfactant solutions. However, the methodologies and materials used for this purpose are widely varied, and few dispersive agents have been studied systematically. This work describes a systematic study into the ability of some well-known (and some less common) surfactants and polymers to disperse SWCNTs fabricated by two different techniques. UV-vis-NIR absorbance spectra of their supernatant solutions showed that the smaller ionic surfactants were generally more effective dispersants, with larger polymer and surfactant molecules exhibiting a reduced performance for ensembles of carbon nanotubes of smaller average diameter. Optimal surfactant concentrations were established for dispersions of carbon nanotubes produced by the electric arc method in aqueous solutions of sodium dodecylbenzene sulfonate, sodium deoxycholate, Triton X-405, Brij S-100, Pluronic F-127, and polyvinylpyrrolidone. This optimum value was determined as the point at which the relative concentration of nanotubes dispersed is maximized, before flocculation-inducing attractive depletion interactions begin to dominate. The aggregation state of carbon nanotubes dispersed in sodium dodecylbenzene sulfonate was probed by AFM at different stages of rebundling, showing the length dependence of these effects. PMID:20666522

  3. Study on superhydrophobic hybrids fabricated from multiwalled carbon nanotubes and stearic acid.

    PubMed

    Wu, Tongfei; Pan, Yongzheng; Li, Lin

    2010-08-01

    A waterproof biomaterial, stearic acid (STA), which is one of components of the wax present on the lotus leaf surface, was used as the material with low surface energy to fabricate superhydrophobic multiwalled carbon nanotube (MWCNT) hybrids through a solution method. This method involved preparation of a sodium stearate (SST)-stabilized MWCNT dispersion, followed by a precipitating process. STA was assembled on the MWCNT-SST hybrid surface by a reaction of SST with acetic acid. The rough surface with multiscale protuberances was revealed by scanning electron microscopy (SEM). The effect of SST/MWCNT weight ratio on water contact angle (CA) and the temperature dependence and alkali resistance of superhydrophobicity of MWCNT hybrids have been investigated. With increasing the SST/MWCNT weight ratio, the water CA of MWCNT hybrid increased and then decreased after a maximum value of 163 degrees at the ratio of 1/1. It was interesting that the wetting property of MWCNT hybrids (SST/MWCNT=0.5/1 and 1/1) was tunable between superhydrophobicity and superhydrophilicity by changing temperature. Potential applications of these superhydrophobic materials to make large-area superhydrophobic coatings have been proposed. PMID:20427047

  4. Application of Lactobacillus immobilized by Activated Carbon Fiber in Fermentation of Lactic Acid in Starch Wastewater

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Wang, Peng; Chi, Guoda; Huang, Chenyong

    2010-11-01

    Activated carbon fibers (ACF) as the carrier of Lactobacillus was introduced into fermenting system, and a method of modifying the surface of ACF by HNO3-Fe (III) was established. Factors that affect ACF carrier's effect on immobilization of Lactobacillus were studied. HCl, H2SO4, HNO3 and FeCl3 solutions were respectively used to modify the surface properties of ACF. The amount of Fe (III) carried on ACF surface was 0.1563 mol/kg after ACF surface was modified by HNO3 for 5 h and then by 0.1 mol/L FeCl3 for 4 h, when the thickness of Lactobacillus on a single silk of carrier reached 40 ?m. When ACF modified by HNO3-Fe (III) was applied in the fermentation of lactic acid in starch industry wastewater, the fermentation period reduced by 8 h and the output of L-lactic acid was 65.5 g/L, which was 3.3% more than that fermented without the carrier.

  5. Regeneration of Acid Orange 7 Exhausted Granular Activated Carbon Using Pulsed Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Huijuan; Guo, He; Liu, Yongjie; Yi, Chengwu

    2015-10-01

    In this paper, a pulsed discharge plasma (PDP) system with a multi-needle-to-plate electrodes geometry was set up to investigate the regeneration of acid orange 7 (AO7) exhausted granular activated carbon (GAC). Regeneration of GAC was studied under different conditions of peak pulse discharge voltage and water pH, as well as the modification effect of GAC by the pulse discharge process, to figure out the regeneration efficiency and the change of the GAC structure by the PDP treatment. The obtained results showed that there was an appropriate peak pulse voltage and an optimal initial pH value of the solution for GAC regeneration. Analyses of scanning electron microscope (SEM), Boehm titration, Brunauer-Emmett-Teller (BET), Horvath-Kawazoe (HK), and X-ray Diffraction (XRD) showed that there were more mesopore and macropore in the regenerated GAC and the structure turned smoother with the increase of discharge voltage; the amount of acidic functional groups on the GAC surface increased while the amount of basic functional groups decreased after the regeneration process. From the result of the XRD analysis, there were no new substances produced on the GAC after PDP treatment. supported by National Natural Science Foundation of China (No. 21207052), China Postdoctoral Science Foundation (No. 20110491353) and Jiangsu Planned Projects for Postdoctoral Research Funds, China (No. 1102116C)

  6. Effect of L (+) ascorbic acid and monosodium glutamate concentration on the morphology of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Saraya, Mohamed El-shahte Ismaiel

    2015-11-01

    In this study, monosodium glutamate and ascorbic acid were used as crystal and growth modifiers to control the crystallization of CaCO3. Calcium carbonate prepared by reacting a mixed solution of Na2CO3 with CaCl2 at ambient temperature, (25 C), constant Ca++CO3-- molar ratio and pH with stirring. The polymorph and morphology of the crystals were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results indicate that rhombohedral calcite was only formed in water without organic additives, and both calcite and spherical vaterite with various morphologies were produced in the presence of monosodium glutamate. The content of vaterite increased as the monosodium glutamate increased. In addition, spherical vaterite was obtained in the presence of different concentrations of ascorbic acid. The spherical vaterite posses an aggregate shape composed of nano-particles, ranging from 30 to 50 nm as demonstrated by the SEM and TEM analyses. Therefore, the ascorbic stabilizes vaterite and result in nano-particles compared to monosodium glutamate.

  7. The use of coiled tubing during matrix acidizing of carbonate reservoirs

    SciTech Connect

    Thomas, R.L.; Milne, A.

    1995-10-01

    A laboratory and field study directed at improved well performance of horizontal wells is discussed. During the study, several wells were matrix acidized using bullhead and coiled tubing placement techniques. The study performed in carbonate reservoirs indicates acid placed with coiled tubing diverted with foam provides excellent zone coverage and damage removal. Conventional bullhead techniques do not result in effective damage removal. The study emphasizes the evaluation of the treatment results and the development of improved acidizing techniques. Laboratory simulations of matrix acidizing indicate proper placement techniques are essential. This observation is supported by field data in oil wells completed in carbonate reservoirs. The key to successful damage removal is (1) the placement of acid via coiled tubing and (2) proper diversion. Production logging and well performance data support this claim. The proposed treatment is applicable in both horizontal and vertical wells completed in carbonate reservoirs.

  8. In situ biodecolorization kinetics of Acid Red 66 in aqueous solutions by Trametes versicolor.

    PubMed

    Sukumar, M; Sivasamy, A; Swaminathan, G

    2009-08-15

    The biological decolorization methodology and the mechanism involved in the degradation of Acid Red 66 was chosen as a model of azo dye using the white rot fungi Trametes versicolor was studied. Biodecolorization of Acid Red 66 using white rot fungi T. versicolor was demonstrated by the decolorization of the culture medium, the extent of which was determined by monitoring the decrease in absorbance at 506 nm. The biodecolorization kinetics of Acid Red 66 (100 ppm) was found to be first order and the degradation rate coefficient is 1.312 x 10(-2)min(-1) (R=0.96683, n=8) at 30 degrees C. The effects of independent variables such as carbon sources, nitrogen sources pH, and temperature on the biodecolorization of Acid Red 66 was also investigated. PMID:19201090

  9. Solution blow spun Poly(lactic acid)/Hydroxypropyl methylcellulose nanofibers with antimicrobial properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid) (PLA) nanofibers containing hydroxypropyl methylcellulose (HPMC) and tetracycline hydrochloride (THC) were solution blow spun from two different solvents, chloroform/acetone (CA, 80:20 v/v) and 2,2,2-triflouroethanol (TFE). The diameter distribution, chemical, thermal, thermal stab...

  10. Effect of acid solutions on plants studied by the optical beam deflection method.

    PubMed

    Nie, Liangjiao; Kuboda, Mitsutoshi; Inoue, Tomomi; Wu, Xingzheng

    2013-12-01

    The optical beam deflection method was applied to study the effects of acid solution on both a terrestial and aquatic plants Egeria and Cerastium, which are common aquatic plant and terrestial weed respectively. A probe beam from a He-Ne laser was passed through a vicinity of a leaf of the plants, which were put in culture dishes filled with acid solutions. Deflection signals of the probe beam were monitored and compared for acid solutions with different pH values. The results of Egria showed that the deflection signals changed dramatically when pH values of acid solutions were 2.0 and 3.0, while little at pH of 4.0 and 5.0. For Cerastium when pH were below 3.0, deflection signals changed greatly with time at the begining. After a certain period of time, deflection signals changed little with time. When pH value was above 4.0, deflection signals of Cerastium were still changing with time even after 20 hours. The results suggested that the damage threshold of pH was between 3.0 and 4.0 for both the land and aquatic plants. PMID:25078849

  11. Modification of vital wheat gluten with phosphoric acid to produce high free-solution capacity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat gluten reacts with phosphoric acid to produce natural superabsorbent gels. The gel properties are defined by Fourier Transform Infra-red (FTIR) spectroscopy, 2-dimensional gel electrophoresis (2DE), and uptake of water, salt solutions, and aqueous ethanol. Temperatures above 120'C and dry cond...

  12. Use of peptide nucleic acids (PNAs) for genotyping by solution and surface methods.

    PubMed

    Sforza, Stefano; Tedeschi, Tullia; Bencivenni, Mariangela; Tonelli, Alessandro; Corradini, Roberto; Marchelli, Rosangela

    2014-01-01

    Peptide nucleic acids (PNAs) are synthetic oligonucleotide analogues based on a pseudopeptide backbone that bind complementary DNA or RNA with high affinity and specificity. In this chapter, three PNA-based genotyping assays are described: PCR clamping, fluorescence-based recognition, and microarray platform. The first two methods are performed in solution, while the microarray method uses a solid surface. PMID:24297357

  13. 49 CFR 173.195 - Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Hydrogen cyanide, anhydrous, stabilized... Hazardous Materials Other Than Class 1 and Class 7 § 173.195 Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution). (a) Hydrogen cyanide, anhydrous, stabilized, must be packed...

  14. 49 CFR 173.195 - Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Hydrogen cyanide, anhydrous, stabilized... Hazardous Materials Other Than Class 1 and Class 7 § 173.195 Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution). (a) Hydrogen cyanide, anhydrous, stabilized, must be packed...

  15. 49 CFR 173.195 - Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Hydrogen cyanide, anhydrous, stabilized... Hazardous Materials Other Than Class 1 and Class 7 § 173.195 Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution). (a) Hydrogen cyanide, anhydrous, stabilized, must be packed...

  16. 49 CFR 173.195 - Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Hydrogen cyanide, anhydrous, stabilized... Hazardous Materials Other Than Class 1 and Class 7 § 173.195 Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution). (a) Hydrogen cyanide, anhydrous, stabilized, must be packed...

  17. 49 CFR 173.195 - Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrogen cyanide, anhydrous, stabilized... Hazardous Materials Other Than Class 1 and Class 7 § 173.195 Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution). (a) Hydrogen cyanide, anhydrous, stabilized, must be packed...

  18. Improved process for the production of cellulose sulfate using sulfuric acid/ethanol solution.

    PubMed

    Chen, Guo; Zhang, Bin; Zhao, Jun; Chen, Hongwen

    2013-06-01

    An improved process for production of cellulose sulfate (CS) was developed by using sulfuric acid/ethanol solution as sulfonating agent and Na2SO4 as water absorbent. The FTIR, SEM and TG analysis were used to characterize the CS prepared. The total degree of substitution and viscosity of the product solution (2%, w/v) were ranging from 0.28 to 0.77 and from 115 to 907 mPa s, respectively, by changing the process parameters such as the amount of Na2SO4, the reaction time, the temperature, the sulfuric acid/alcohol ratio and liquid/solid ratio. The results indicated that the product with DS (0.28-0.77) and ?2% (115-907) mPa s could be produced by using this improved process and more cellulose sulfate could be produced when cellulose was sulfonated for 3-4 h at -2 C in sulfuric acid/ethanol (1.4-1.6) solution with addition of 0.8 g Na2SO4. The (13)C NMR indicated that the sulfate group of CS produced using sulfuric acid/ethanol solution was at C6 position. PMID:23618277

  19. PHYSICAL SOLUTIONS FOR ACID ROCK DRAINAGE AT REMOTE SITES DEMONSTRATION PROJECT

    EPA Science Inventory

    This report summarizes the results of Mine Waste Technology Program, Activity III, Project 42, Physical Solutions for Acid Rock Drainage at Remote Sites, funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S. Department of Energy. A...

  20. Long-term stability of earthen materials in contact with acidic tailings solutions

    SciTech Connect

    Peterson, S.R.; Erikson, R.L.; Gee, G.W.

    1982-11-01

    The objectives of the studies documented in this report were to use experimental and geochemical computer modeling tools to assess the long-term environmental impact of leachate movement from acidic uranium mill tailings. Liner failure (i.e., an increase in the permeability of the liner material) was not found to be a problem when various acidic tailings solutions leached through liner materials for periods up to 3 years. On the contrary, materials that contained over 30% clay showed a decrease in permeability with time in the laboratory columns. The high clay materials tested appear suitable for lining tailings impoundment ponds. The decreases in permeability are attributed to pore plugging resulting from the precipitation of minerals and solids. This precipitation takes place due to the increase in pH of the tailings solution brought about by the buffering capacity of the soil. Geochemical modeling predicts, and x-ray characterization confirms, that precipitation of solids from solution is occurring in the acidic tailings solution/liner interactions studied. In conclusion the same mineralogical changes and contaminant reactions predicted by geochemical modeling and observed in laboratory studies were found at a drained evaporation pond (Lucky Mc in Wyoming) with a 4 year history of acid attack.

  1. Spray washing carcasses with alkaline solutions of lauric acid to reduce bacterial contamination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of lauric acid (LA)-potassium hydroxide (KOH) solutions to reduce carcass bacterial contamination was examined. Skin of carcasses was inoculated with a cecal paste containing antibiotic resistant strains of Escherichia coli, Salmonella Typhimirum, and Campylobacter coli. In one trial, in...

  2. Cesium absorption from acidic solutions using ammonium molybdophosphate on a polyacrylonitrile support (AMP-PAN)

    SciTech Connect

    Miller, C.J.; Olson, A.L.; Johnson, C.K.

    1995-12-01

    Recent efforts at the Idaho Chemical Processing Plant (ICPP) have included evaluation of cesium removal technologies as applied to ICPP acidic radioactive waste streams. Ammonium molybdophosphate (AMP) immobilized on a polyacrylonitrile support (AMP-PAN) has been studied as an ion exchange agent for cesium removal from acidic waste solutions. Capacities, distribution coefficients, elutability, and kinetics of cesium-extraction have been evaluated. Exchange breakthrough curves using small columns have been determined from 1M HNO{sub 3} and simulated waste solutions. The theoretical capacity of AMP is 213 g Cs/kg AMP. The average experimental capacity in batch contacts with various acidic solutions was 150 g Cs/kg AMP. The measured cesium distribution coefficients from actual waste solutions were 3287 mL/g for dissolved zirconia calcines, and 2679 mL/g for sodium-bearing waste. The cesium in the dissolved alumina calcines was analyzed for; however, the concentration was below analytical detectable limits resulting in inconclusive results. The reaction kinetics are very rapid (2-10 minutes). Cesium absorption appears to be independent of acid concentration over the range tested (0.1 M to 5 M HNO{sub 3}).

  3. Room temperature synthesis of nano-carbons using an electrochemical technique of organic solution

    NASA Astrophysics Data System (ADS)

    Yokomichi, H.; Sakai, F.; Ichihara, M.; Kishimoto, N.

    2005-08-01

    Room temperature synthesis of nano-carbons, i.e., whiskers, wires, onions and tubes, has been achieved by an electrochemical process under a liquid phase of organic solution with a metal catalyst. The electrochemical method supplies athermal energy to the reactants contrary to ordinary methods, i.e., this method creates nano-carbons directly transferring electrons at the electrode in the condensed phase, and the temperature does not increase during the synthesis. The nano-carbons with various structures were obtained by using C2H5OH with \\mathrm {Ni}(\\mathrm {NO}_{3})_{n}{\\bdot }\\mathrm {mH}_{2}\\mathrm {O} solution under a high electric field. The metal catalyst plays an important role in the nano-carbon growth in the present method, in a similar way to the usual methods. By virtue of the low temperature synthesis, this technique has great advantages in nano-scale interconnections and large area field emission cathodes of nano-carbons in next-generation devices on a thermally unstable substrate.

  4. SIMULTANEOUS INHIBITION OF CARBON AND NITROGEN MINERALIZATION IN A FOREST SOIL BY SIMULATED ACID PRECIPITATION

    EPA Science Inventory

    Acid Precipitation may alter the rates of microbial processes in soil that are important for forest productivity. Acidification of soil can result in a depression of carbon mineralization. The present study was designed to determine whether the inhibition of carbon mineralization...

  5. USE OF THE COMPOSITION AND STABLE CARBONIISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (*13C) of individual microbial phospholipid fatty acids (PLFAs) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SOM) cy...

  6. Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

    NASA Astrophysics Data System (ADS)

    Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

    2015-10-01

    "Clumped-isotope" thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope "clumps"). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals. We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3- and CO32-. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two types of experiments yielded statistically indistinguishable results, and these measurements yield a calibration that overlaps with our theoretical predictions for calcite at equilibrium. The slow-growing Devils Hole calcite exhibits Δ47 and δ18O values consistent with lattice equilibrium. Factors influencing DIC speciation (pH, salinity) and the timescale for DIC equilibration, as well as reactions at the mineral-solution interface, have the potential to influence clumped-isotope signatures and the δ18O of carbonate minerals. In fast-growing carbonate minerals, solution chemistry may be an important factor, particularly over extremes of pH and salinity. If a crystal grows too rapidly to reach an internal equilibrium (i.e., achieve the value for the temperature-dependent mineral lattice equilibrium), it may record the clumped-isotope signature of a DIC species (e.g., the temperature-dependent equilibrium of HCO3-) or a mixture of DIC species, and hence record a disequilibrium mineral composition. For extremely slow-growing crystals, and for rapidly-grown samples grown at a pH where HCO3- dominates the DIC pool at equilibrium, effects of solution chemistry are likely to be relatively small or negligible. In summary, growth environment, solution chemistry, surface equilibria, and precipitation rate may all play a role in dictating whether a crystal achieves equilibrium or disequilibrium clumped-isotope signatures.

  7. Carbonic Acid as a Reserve of Carbon Dioxide on Icy Moons: The Formation of Carbon Dioxide (CO2) in a Polar Environment

    NASA Astrophysics Data System (ADS)

    Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

    2014-06-01

    Carbon dioxide (CO2) has been detected on the surface of several icy moons of Jupiter and Saturn via observation of the ?3 band with the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft and the Visible-Infrared Mapping Spectrometer on board the Cassini spacecraft. Interestingly, the CO2 band for several of these moons exhibits a blueshift along with a broader profile than that seen in laboratory studies and other astrophysical environments. As such, numerous attempts have been made in order to clarify this abnormal behavior; however, it currently lacks an acceptable physical or chemical explanation. We present a rather surprising result pertaining to the synthesis of carbon dioxide in a polar environment. Here, carbonic acid was synthesized in a water (H2O)-carbon dioxide (CO2) (1:5) ice mixture exposed to ionizing radiation in the form of 5 keV electrons. The irradiated ice mixture was then annealed, producing pure carbonic acid which was then subsequently irradiated, recycling water and carbon dioxide. However, the observed carbon dioxide ?3 band matches almost exactly with that observed on Callisto; subsequent temperature program desorption studies reveal that carbon dioxide synthesized under these conditions remains in solid form until 160 K, i.e., the sublimation temperature of water. Consequently, our results suggest that carbon dioxide on Callisto as well as other icy moons is indeed complexed with water rationalizing the shift in peak frequency, broad profile, and the solid state existence on these relatively warm moons.

  8. Solution and precipitation hardening in carbon-doped two-phase {gamma}-titanium aluminides

    SciTech Connect

    Appel, F.; Christoph, U.; Wagner, R.

    1997-12-31

    A two-phase titanium aluminide alloy was systematically doped with carbon to improve its high temperature strength. Solid solutions and precipitates of carbon were formed by different thermal treatments. A fine dispersion of perovskite precipitates was found to be very effective for improving the high temperature strength and creep resistance of the material. The strengthening mechanisms were characterized by flow stresses and activation parameters. The investigations were accompanied by electron microscope observation of the defect structure which was generated during deformation. Special attention was paid on the interaction mechanisms of perfect and twinning dislocations with the carbide precipitates.

  9. RADIATION CHEMISTRY OF HIGH ENERGY CARBON, NEON AND ARGON IONS: INTEGRAL YIELDS FROM FERROUS SULFATE SOLUTIONS

    SciTech Connect

    Christman, E.A.; Appleby, A.; Jayko, M.

    1980-07-01

    Chemical yields of Fe{sup 3+} have been measured from FeSO{sub 4} solutions irradiated in the presence and absence of oxygen with carbon, neon, and argon ions from the Berkeley Bevalac facility. G(Fe{sup 3+}) decreases with increasing beam penetration and with increasing atomic number of the incident ion. The results are compared with current theoretical expectations of the behavior of these particles in an aqueous absorber. The chemical yields are consistently higher than theoretically predicted, by amounts varying from <6.2% (carbon ions) to <13.2% (argon ions). The additional yields are possibly attributable to fragmentation of the primary particle beams.

  10. Applications of Propargyl Esters of Amino Acids in Solution-Phase Peptide Synthesis

    PubMed Central

    Ramapanicker, Ramesh; Gupta, Rohit; Megha, Rajendran; Chandrasekaran, Srinivasan

    2011-01-01

    Propargyl esters are employed as effective protecting groups for the carboxyl group during solution-phase peptide synthesis. The propargyl ester groups can be introduced onto free amino acids by treating them with propargyl alcohol saturated with HCl. The reaction between propargyl groups and tetrathiomolybdate is exploited to deblock the propargyl esters. The removal of the propargyl group with the neutral reagent tetrathiomolybdate ensures that most of the other protecting groups used in peptide synthesis are untouched. Both acid labile and base labile protecting groups can be removed in the presence of a propargyl ester. Amino acids protected as propargyl esters are employed to synthesize di- to tetrapeptides in solution-phase demonstrating the possible synthetic utilities of the methodology. The methodology described here could be a valuable addition to currently available strategies for peptide synthesis. PMID:21760822

  11. Spectrophotometric determination of uranium and plutonium present together in nitric acid solutions

    SciTech Connect

    Levakov, B.I.; Mishenev, V.B.; Nezgovorov, N.Yu.; Ryazanova, G.K.; Timofeev, G.A.

    1987-07-01

    A method is described for the spectrophotometric determination of uranium(VI) and plutonium(IV) in nitric acid solutions. Uranium is determined as a light-absorbing complex with arsenazo III in 0.05 M nitric acid at lambda = 654 nm, plutonium as a light-absorbing complex with xylenol orange in 0.1 M nitric acid at lambda = 540 nm. For the determination of uranium, DTPA is introduced into the photometric solution to mask the plutonium together with the tetravalent, and some trivalent, elements. The relative mean-square deviation of the results does not exceed 0.03 in the concentration ranges 0.5-5 ..mu..g U/ml, 1-3 ..mu..g Pu/ml.

  12. Corrosion behavior of niobium coated 304 stainless steel in acid solution

    NASA Astrophysics Data System (ADS)

    Pan, T. J.; Chen, Y.; Zhang, B.; Hu, J.; Li, C.

    2016-04-01

    The niobium coating is fabricated on the surface of AISI Type 304 stainless steel (304SS) by using a high energy micro arc alloying technique in order to improvecorrosion resistance of the steel against acidic environments. The electrochemical corrosion resistance of the niobium coating in 0.7 M sulfuric acid solutions is evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and the open circuit potential versus time. Electrochemical measurements indicate that the niobium coating increases the free corrosion potential of the substrate by 110 mV and a reduction in the corrosion rate by two orders of magnitude compared to the substrate alone. The niobium coating maintains large impedance and effectively offers good protection for the substrate during the long-term exposure tests, which is mainly ascribed to the niobium coating acting inhibiting permeation of corrosive species. Finally, the corresponding electrochemical impedance models are proposed to elucidate the corrosion resistance behavior of the niobium coating in acid solutions.

  13. Method for separating constituents from solution employing a recyclable Lewis acid metal-hydroxy gel

    SciTech Connect

    Alexander, D.H.

    1995-12-31

    This invention permits radionuclides, heavy metals, and organics to be extracted from solution by scavenging them with an amorphous gel. In the preferred embodiment, a contaminated solution (e.g. from soil washing, decontamination, or groundwater pumping) is transferred to a reaction vessel. The contaminated solution is contacted by the sequestering reagent which might contain for example, aluminate and EDTA anions in a 2.5 M NaOH solution. The pH of the reagent bearing solution is lowered on contact with the contaminated solution, or for example by bubbling carbon dioxide through it, causing an aluminum hydroxide gel to precipitate as the solution drops below the range of 1.8 to 2.5 molar NaOH (less than pH 14). This precipitating gel scavenges waste contaminants as it settles through solution leaving a clean supernatant which is then separated from the gel residue by physical means such as centrifugation, or simple settling. The gel residue containing concentrated contaminants is then redissolved releasing contaminants for separations and processing. This is a critical point: the stabilized gel used in this invention is readily re-dissolved by merely increasing the pH above the gels phase transition to aqueous anions. Thus, concentrated contaminants trapped in the gel can be released for convenient separation from the sequestering reagent, and said reagent can then be recycled.

  14. Sorption performance and mechanism of a sludge-derived char as porous carbon-based hybrid adsorbent for benzene derivatives in aqueous solution.

    PubMed

    Kong, Lingjun; Xiong, Ya; Sun, Lianpeng; Tian, Shuanghong; Xu, Xianyan; Zhao, Cunyuan; Luo, Rongshu; Yang, Xin; Shih, Kaimin; Liu, Haiyang

    2014-06-15

    A porous sludge-derived char was prepared by a new one-step pyrolytic process with citric acid-ZnCl2 mixed fabricating-pore agents. The sludge-derived char was confirmed to be a hierarchically porous hybrid adsorbent containing-elemental carbon, -highly carbonized organic species and -inorganic ash with a great surface area of 792.4m(2)g(-1). It was used as a carbon-based hybrid adsorbent for four benzene derivatives including 4-chlorophenol, phenol, benzoic acid and 4-hydroxylbenzoic acid in aqueous solution. Results showed that their sorption isotherms were nonlinear at low concentrations and linear at high concentrations. The sorption performance could be described by a multiple sorption model (QT=QA+KPCe). The order of these partition sorption coefficients (KP) of these benzene derivatives was consistent with their octanol-water partition coefficients (logKow), but those saturated amounts (QA) were inconsistent with their logKow. The inconstancy was found to be considerably dependent on the preferential interaction of benzoic acid with SiO2 in the sludge-derived char. Quantum theoretical calculation confirmed that the preferential interaction was attributed to the formation of hydrogen bonds (1.61 and 1.69?) and new Si-O bonds (1.83 and 1.87?) between the carboxyl of benzoic acid and the SiO2 surface in the sorption process. PMID:24793296

  15. Detergent-assisted self assembly of fatty acid layers on mica in solution

    NASA Astrophysics Data System (ADS)

    Hand, Sean; Yang, Jie

    1997-03-01

    Fatty acids are well known for their ability to form monolayers at air-water interfaces. The conventional method to coat a solid surface with mono or multi layers of fatty acids uses a Langmuir trough, via X- or Y- type coatings. The major advantage of the Langmuir trough is the ability to control the monolayer pressure. The limiting factors are, however, the restricted size of the substrate, the physical size of the Langmuir trough, and the coating procedure. To circumvent some of these drawbacks, we have developed a method to cover a solid mica substrate with fatty acids by detergent assisted self assembly in aqueous solutions. It has been found that a molecular layer of fatty acids, possibly complexed with some detergent, are self-assembled on the mica surface. Thickness measurements of these self-assembled layers suggest that the layer is composed of two monolayers of fatty acids in a bilayer arrangement. The presence of cations in the solution has some effect on the assembly of the molecular layer, and may alter the orientation of individual fatty acids in the layer. Structural characteristics of such self assembled molecular layers are studied with atomic force microscopy. Details of the method of the detergent assisted self assembly and some structural features of the assembled molecular layers will be presented.

  16. Study of the decomposition pathway of 12-molybdophosphoric acid in aqueous solutions by micro Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bajuk-Bogdanović, D.; Uskoković-Marković, S.; Hercigonja, R.; Popa, A.; Holclajtner-Antunović, I.

    2016-01-01

    Micro Raman spectroscopy was applied to investigate the speciation of heteropoly and isopoly molybdates in 0.05 and 0.005 M aqueous solutions of 12-molybdophosphoric acid at pH values between 1 and 6. For comparative purposes, 31P NMR spectroscopy was applied too. It is shown that stability of Keggin anion is influenced both by pH and concentration of solution. The Keggin structure is stable in acidic solutions (pH < 1.6) while defective Keggin structures are formed with further alkalization (up to pH 5.6). Monolacunary anion PMo11O397 - is the main component in the pH region from 1.6 to 3.4. Further removal of molybdenyl species causes the appearance of other vacant Keggin structures such as PMo9O31(OH)36 - and PMo6O259 - at about pH 4. At pH 5.0, anion PMo6O259 - is the main species. In solutions with pH greater than 5.0, heteropolymolybdates disappear completely and isopolymolybdates Mo7O246 - and MoO42 - are formed in higher amounts. In more diluted solution of 0.005 M, the decomposition scheme of 12-molybdophosphoric acid solution with increasing of pH takes place without observation of significant amounts of Mo7O246 - species. If alkalinization is performed with 0.5 M instead of 5 M NaOH, there are no significant changes in the Raman spectra of solutions. It is shown that the spectra of evaporated samples may be used for the identification of molecular species in corresponding concentrated solutions. However, Raman spectra of dry residues of more diluted solutions differ from spectra of corresponding solutions due to the reactions performed during the process of drying and cannot be used for unambiguous identification of species in solution. Acidification of 0.05 M solution of Na2MoO4 shows that at pH > 5.6, molybdate anion MoO42 - dominates, while in the pH range between 5.6 and 1, heptamolybdate anion Mo7O246 - is preferentially formed.

  17. Study of the decomposition pathway of 12-molybdophosphoric acid in aqueous solutions by micro Raman spectroscopy.

    PubMed

    Bajuk-Bogdanovi?, D; Uskokovi?-Markovi?, S; Hercigonja, R; Popa, A; Holclajtner-Antunovi?, I

    2016-01-15

    Micro Raman spectroscopy was applied to investigate the speciation of heteropoly and isopoly molybdates in 0.05 and 0.005M aqueous solutions of 12-molybdophosphoric acid at pH values between 1 and 6. For comparative purposes, (31)P NMR spectroscopy was applied too. It is shown that stability of Keggin anion is influenced both by pH and concentration of solution. The Keggin structure is stable in acidic solutions (pH<1.6) while defective Keggin structures are formed with further alkalization (up to pH5.6). Monolacunary anion PMo11O39(7-) is the main component in the pH region from 1.6 to 3.4. Further removal of molybdenyl species causes the appearance of other vacant Keggin structures such as PMo9O31(OH)3(6-) and PMo6O25(9-) at about pH4. At pH5.0, anion PMo6O25(9-) is the main species. In solutions with pH greater than 5.0, heteropolymolybdates disappear completely and isopolymolybdates Mo7O24(6-) and MoO4(2-) are formed in higher amounts. In more diluted solution of 0.005M, the decomposition scheme of 12-molybdophosphoric acid solution with increasing of pH takes place without observation of significant amounts of Mo7O24(6-) species. If alkalinization is performed with 0.5M instead of 5M NaOH, there are no significant changes in the Raman spectra of solutions. It is shown that the spectra of evaporated samples may be used for the identification of molecular species in corresponding concentrated solutions. However, Raman spectra of dry residues of more diluted solutions differ from spectra of corresponding solutions due to the reactions performed during the process of drying and cannot be used for unambiguous identification of species in solution. Acidification of 0.05M solution of Na2MoO4 shows that at pH>5.6, molybdate anion MoO4(2-) dominates, while in the pH range between 5.6 and 1, heptamolybdate anion Mo7O24(6-) is preferentially formed. PMID:26301540

  18. Carbon Isotope Compositions of Fatty Acids in Mussels from Newfoundland Estuaries

    NASA Astrophysics Data System (ADS)

    Murphy, Dena E.; Abrajano, Teofilo A.

    1994-09-01

    This paper examines the carbon isotopic compositions of free fatty acids of two species of mussels (i.e. Mytilus edulis and Modiolus modiolus) from two estuarine environments around Newfoundland. Gas chromatography and conventional isotope ratio mass spectrometry were employed to characterize bulk fatty acids and gas chromatography/combustion/isotope ratio mass spectrometry was utilized to characterize the carbon isotope compositions of individual fatty acids. The bulk fatty acid distribution (dominance of 16:0, 20:5n3, 22:6n3 and 16:1) and carbon isotopic compositions (-273 to -258 per mil) indicate a dominant marine phytoplankton dietary source for the mussels. In contrast to the narrow range of bulk fatty acid ? 13C values, up to 7 per mil variation in ? 13C of individual fatty acids was observed. In general, saturated fatty acids are isotopically heavier than corresponding mono- and polyunsaturates, consistent with previously suggested kinetic isotope effect associated with de novo desaturation reactions. The depletion of 13 C in 18:4n3 compared with 22:6n3 and 20:5n3 indicates a distinct dietary source for 18:4n3. The present study shows the potential for detailed assessment of carbon flow in benthic ecosystems using fatty acids and other compound classes by gas chromatography/combustion/isotope ratio mass spectrometry.

  19. Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System

    PubMed Central

    Fujioka, Kouki; Futamura, Yasuhiro; Shiohara, Tomoo; Hoshino, Akiyoshi; Kanaya, Fumihide; Manome, Yoshinobu; Yamamoto, Kenji

    2009-01-01

    Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of lifes origin. PMID:19582225

  20. Amino acid synthesis in a supercritical carbon dioxide - water system.

    PubMed

    Fujioka, Kouki; Futamura, Yasuhiro; Shiohara, Tomoo; Hoshino, Akiyoshi; Kanaya, Fumihide; Manome, Yoshinobu; Yamamoto, Kenji

    2009-06-01

    Mars is a CO(2)-abundant planet, whereas early Earth is thought to be also CO(2)-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO(2)/liquid H(2)O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life's origin. PMID:19582225

  1. Adsorptions of some heavy metal ions in aqueous solutions by acrylamide/maleic acid hydrogels

    SciTech Connect

    Saraydin, D.; Karadag, E.; Gueven, O.

    1995-10-01

    In this study, acrylamide-maleic acid (AAm/MA) hydrogels in the form of rod have been prepared by {gamma}-radiation. They have been used for adsorption of some heavy metal ions such as uranium, iron, and copper. For the hydrogel containing 40 mg of maleic acid and irradiated at 3.73 kGy, maximum and minimum swellings in the aqueous solutions of the heavy metal ions have been observed with water (1480%) and the aqueous solution of iron(III) nitrate (410%), respectively. Diffusions of water and heavy metal ions onto hydrogels have been found to be of the non-Fickian type of diffusion. In experiments of uranyl ions adsorption, Type II adsorption has been found. One gram of AAa/MA hydrogels sorbed 14-86 mg uranyl ions from solutions of uranyl acetate, 14-90 mg uranyl ions from solutions of uranyl nitrate, 16-39 mg iron ions from solutions of iron(IV) nitrate, and 28-81 mg copper ions from solutions of copper acetate, while acrylamide hydrogel did not sorb any heavy metals ions.

  2. Determination of electronic states of individually dissolved ( n, m) single-walled carbon nanotubes in solution

    NASA Astrophysics Data System (ADS)

    Tanaka, Yasuhiko; Hirayama, Kohei; Niidome, Yasuro; Nakashima, Naotoshi

    2009-11-01

    Solution redox chemistry is useful to understand the chirality-dependent electronic properties of single-walled carbon nanotubes (SWNTs). We have found that the electron transfer reactions of sodium dithionite with SWNTs cause photoluminescence (PL) quenching processes of 14 individually dissolved SWNTs in an aqueous micellar solution. Based on the analysis using the Nernst equation for the PL change, we have determined the conduction band ( c1) levels of the 14 isolated SWNTs. We have also estimated the valence band ( ?1) levels as well as the Fermi levels of the SWNTs using the reported bandgap values of the corresponding isolated SWNTs.

  3. Acid-base behavior of the gaspeite (NiCO3(s)) surface in NaCl solutions.

    PubMed

    Villegas-Jimnez, Adrin; Mucci, Alfonso; Pokrovsky, Oleg S; Schott, Jacques

    2010-08-01

    Gaspeite is a low reactivity, rhombohedral carbonate mineral and a suitable surrogate to investigate the surface properties of other more ubiquitous carbonate minerals, such as calcite, in aqueous solutions. In this study, the acid-base properties of the gaspeite surface were investigated over a pH range of 5 to 10 in NaCl solutions (0.001, 0.01, and 0.1 M) at near ambient conditions (25 +/- 3 degrees C and 1 atm) by means of conventional acidimetric and alkalimetric titration techniques and microelectrophoresis. Over the entire experimental pH range, surface protonation and electrokinetic mobility are strongly affected by the background electrolyte, leading to a significant decrease of the pH of zero net proton charge (PZNPC) and the pH of isoelectric point (pH(iep)) at increasing NaCl concentrations. This challenges the conventional idea that carbonate mineral surfaces are chemically inert to background electrolyte ions. Multiple sets of surface complexation reactions (i.e., ionization and ion adsorption) were formulated within the framework of three electrostatic models (CCM, BSM, and TLM) and their ability to simulate proton adsorption and electrokinetic data was evaluated. A one-site, 3-pK, constant capacitance surface complexation model (SCM) reproduces the proton adsorption data at all ionic strengths and qualitatively predicts the electrokinetic behavior of gaspeite suspensions. Nevertheless, the strong ionic strength dependence exhibited by the optimized SCM parameters reveals that the influence of the background electrolyte on the surface reactivity of gaspeite is not fully accounted for by conventional electrostatic and surface complexation models and suggests that future refinements to the underlying theories are warranted. PMID:20590111

  4. Infusion of Branched-chain Enriched Amino Acid Solution in Patients with Hepatic Encephalopathy

    PubMed Central

    Freund, Herbert; Dienstag, Jules; Lehrich, James; Yoshimura, Norman; Bradford, Ronald R.; Rosen, Harvey; Atamian, Susan; Slemmer, Elizabeth; Holroyde, Jane; Fischer, Josef E.

    1982-01-01

    Hospitalized patients with hepatic insufficiency often suffer from severe catabolic states and are in urgent need of nutritional support during their acute illness. Protein intolerence, however, remains a significant problem with respect to the provision of adequate nutrition, either enterally or parenterally. The following report is an anecdotal series of 63 consecutive patients in a large urban hospital treated prospectively with nutritional support using a prototype high branched-chain amino acid solution (FO80) given by technique of total parenteral nutrition by the subclavian or internal jugular route with hypertonic dextrose. Sixty-three patients, of which 42 had chronic liver disease (cirrhosis) with acute decompensation and 17 with acute hepatic injury as well as four with hepatorenal syndrome, are the subject of this report. All required intravenous nutritional support and were either intolerant to commercially available parenteral nutrition solutions or were in hepatic encephalopathy at the time they were initially seen. The cirrhotic patients had been hospitalized for a mean of 14.5 1.9 days before therapy, had a mean bilirubin of 13 mg/100 ml, and had been in coma for 4.8 0.7 days despite standard therapy. Patients with acute hepatitis had been in the hospital for 16.2 4.1 days before therapy, had a mean bilirubin of 25 mg/100 ml, and had been in coma 5.2 1.6 days before therapy. Routine tests of liver function, blood chemistries, amino acids, EEGs, and complex neurological testing including Reitan trailmaking tests were used in the evaluation of these patients. Up to 120 grams of synthetic amino acid solution with hypertonic dextrose was tolerated in these patients with improvement noted in encephalopathy of at least one grade in 87% of the patients with cirrhosis and 75% of the patients with hepatitis. Nitrogen balance was achieved when 75 to 80 grams of synthetic amino acids were administered. Survival was 45% in the cirrhotic group and 47% in the acute hepatitis group. Encephalopathy appeared to correlate with individual amino acids differentially in the various groups and with the ratio between the aromatic and the branched-chain amino acids. Ammonia did not correlate with either the degree of encephalopathy or improvement therefrom. In 24 Patients therapy for hepatic encephalopathy was limited to infusion of the branched-chain enriched amino acid solution only, with wake-up in 66% of this group. The results strongly suggest that in protein intolerant patients requiring nutritional support, infusion with branchedchain enriched amino acid solutions is well tolerated with either no worsening of or improvement in hepatic encephalopathy coincident with the achievement of nitrogen equilibrium and adequate nutritional support. PMID:6284073

  5. Viscometric study of chitosan solutions in acetic acid/sodium acetate and acetic acid/sodium chloride.

    PubMed

    Costa, Cristiane N; Teixeira, Viviane G; Delpech, Marcia C; Souza, Josefa Virginia S; Costa, Marcos A S

    2015-11-20

    A viscometric study was carried out at 25C to assess the physical-chemical behavior in solution and the mean viscometric molar mass (Mv) of chitosan solutions with different deacetylation degrees, in two solvent mixtures: medium 1-acetic acid 0.3mol/L and sodium acetate 0.2mol/L; and medium 2-acetic acid 0.1mol/L and sodium chloride 0.2mol/L. Different equations were employed, by graphical extrapolation, to calculate the intrinsic viscosities [?] and the viscometric constants, to reveal the solvent's quality: Huggins (H), Kraemer (K) and Schulz-Blaschke (SB). For single-point determination, the equations used were SB, Solomon-Ciuta (SC) and Deb-Chanterjee (DC), resulting in a faster form of analysis. The values of ?Mv were calculated by applying the equation of Mark-Houwink-Sakurada. The SB and SC equations were most suitable for single-point determination of [?] and ?Mv and the Schulz-Blachke constant (kSB), equal to 0.28, already utilized for various systems, can also be employed to analyze chitosan solutions under the conditions studied. PMID:26344278

  6. Vapor pressure data for potassium carbonate-potassium bicarbonate solutions for application to multiuse power cycles

    NASA Astrophysics Data System (ADS)

    Hosler, E. R.; Ghandeharioun, S.

    A novel method of generating electric power based on a gas absorption cycle, rather than a normal Rankine steam power cycle, has been developed. This cycle uses carbon dioxide as the working fluid in the turbine and potassium carbonate solutions as the carrier fluid for the absorption part of the cycle. Thermodynamic calculations for typical operating parameters show a cycle efficiency of about 30 percent compared to a Carnot efficiency of about 40 percent and a Rankine cycle efficiency of about 20 percent for the same temperature limits. Thus, the cycle offers a significant thermal efficiency advantage compared to a Rankine cycle. Vapor pressure data have been obtained for various carrier solution concentrations in the high temperature, high pressure region where no previous data existed. This paper summarized these data. The data support the hypothesis that the gas absorption power cycle offers thermal efficiency benefits compared to a conventional steam power cycle.

  7. Precipitation studies of ammonium uranyl carbonate from UO 2F 2 solutions

    NASA Astrophysics Data System (ADS)

    Kan-Sen, Chou; Ding-Yi, Lin; Mu-Chang, Shieh

    1989-05-01

    The precipitation of ammonium uranyl carbonate (AUC) from UO 2F 2 solutions is investigated in this report. An intermediate product, identified as (NH 4) 3UO 2F 5 (AUF), was found preceding the formation of normal AUC precipitates. It dissolves only slowly in the ammonia carbonate solution. Methods of experimental design were adopted here to decide the relative importance of several parameters with respect to either uranium recovery or fluorine content. Our results suggest that the aging temperature is the most important parameter within the ranges of studies affecting the recovery of uranium in this precipitation process. While, on the other hand, the titration rate of (NH 4) 2CO 3 is the only parameter that affects the fluorine content independently. The inclusion of additional NH 4OH in the precipitant can improve the recovery of uranium but unfortunately it increases the fluorine contents as well. Other changes in the characteristics of the precipitate occur undoubtedly.

  8. Separation of surfactant functionalized single-walled carbon nanotubes via free solution electrophoresis method

    NASA Astrophysics Data System (ADS)

    Scheibe, Blazej; Rümmeli, Mark H.; Borowiak-Palen, Ewa; Kalenczuk, Ryszard J.

    2011-04-01

    This work presents the application of the free solution electrophoresis method (FSE) in the metallic / semiconductive (M/S) separation process of the surfactant functionalized single-walled carbon nanotubes (SWCNTs). The SWCNTs synthesized via laser ablation were purified through high vacuum annealing and subsequent refluxing processes in aqua regia solution. The purified and annealed material was divided into six batches. First three batches were dispersed in anionic surfactants: sodium dodecyl sulfate (SDS), sodium cholate (SC) and sodium deoxycholate (DOC). The next three batches were dispersed in cationic surfactants: cetrimonium bromide (CTAB), benzalkonium chloride (BKC) and cetylpyridinium chloride (CPC). All the prepared SWCNTs samples were subjected to FSE separation process. The fractionated samples were recovered from control and electrode areas and annealed in order to remove the adsorbed surfactants on carbon nanotubes (CNTs) surface. The changes of the van Hove singularities (vHS) present in SWCNTs spectra were investigated via UV-Vis-NIR optical absorption spectroscopy (OAS).

  9. [Efficient killing of anthrax spores using aqueous and alcoholic peracetic acid solutions].

    PubMed

    Nattermann, H; Becker, S; Jacob, D; Klee, S R; Schwebke, I; Appel, B

    2005-08-01

    We analysed the sporicidal effect of different concentrations of aqueous and alcoholic peracetic acid (PAA) solutions on anthrax spores in suspension and germ carrier tests. In activation of anthrax spores in suspension assays was achieved in less than 2 min using 1% PAA solution and in less than 3 min using 0.5% PAA solution, respectively. In contrast, in germ carrier as says, a test under practical conditions, spores on 38% of the germ carriers survived treatment with 1% PAA solution for 15 min. The use of PAA in 80% ethyl alcohol outclassed the sporicidal effect of aqueous PAA solutions in both suspension and germ carrier assays. Anthrax spores on 14% of germ carriers tested survived 30 min of treatment with a 1% aqueous PAA solution. In contrast anthrax spores were reliably inactivated under the same test procedure using a 1% alcoholic PAA solution for 30 min. The proven enhancement of the sporicidal effect of alcoholic PAA solutions should be kept in mind when using disinfectants in practice. In further surveys we will optimise the test conditions. PMID:16086206

  10. Infrared spectra of phthalic acid, the hydrogen phthalate ion, and the phthalate ion in aqueous solution

    NASA Astrophysics Data System (ADS)

    Loring, John S.; Karlsson, Magnus; Fawcett, W. Ronald; Casey, William H.

    2001-07-01

    The infrared spectra of a series of aqueous solutions containing phthalic acid (1,2-benzenedicarboxylic acid) and varying pH were examined using attenuated total reflection Fourier transform infrared spectroscopy and potentiometry. The basis spectra of phthalic acid, the hydrogen phthalate ion, and the phthalate ion were isolated using a factor analysis in which the absorbance of these species varies with pH and total phthalate concentration according to equilibrium and mass balance relations. Assignments of these basis spectra were made by comparison with spectra calculated ab initio. The conditional formation constants of phthalic acid and the hydrogen phthalate ion were determined at 25.00.1C in 0.6 M NaCl ionic media using infrared spectroscopy and in 1.5 M NaCl ionic media using both infrared spectroscopy and potentiometry.

  11. Highly ordered three dimensional macroporous carbon spheres and their acid catalytic properties

    NASA Astrophysics Data System (ADS)

    Huang, Hui; Zhang, Jianming; Zhang, Yuxiao; Lian, Suoyuan; Liu, Yang

    2013-10-01

    Highly ordered three dimensional macroporous carbon spheres bearing sulfonic acid groups (MPCS-SO3H) were prepared by incomplete carbonization of glucose in silica crystal bead template, followed by sulfonation and removal of the template. The composition and porous structure of the obtained carbon spheres were investigated by physical adsorption of nitrogen, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. The catalytic properties of the MPCS-SO3H were evaluated by esterification of ethanol with acetic acid, indicating that MPCS-SO3H possess remarkable catalytic performance (high stability and acid catalytic ability) for the esterification.

  12. Computational and experimental studies of the interaction between single-walled carbon nanotubes and folic acid

    NASA Astrophysics Data System (ADS)

    Castillo, John J.; Rozo, Ciro E.; Castillo-Len, Jaime; Rindzevicius, Tomas; Svendsen, Winnie E.; Rozlosnik, Noemi; Boisen, Anja; Martnez, Fernando

    2013-03-01

    This Letter involved the preparation of a conjugate between single-walled carbon nanotubes and folic acid that was obtained without covalent chemical functionalization using a simple 'one pot' synthesis method. Subsequently, the conjugate was investigated by a computational hybrid method: our own N-layered Integrated Molecular Orbital and Molecular Mechanics (B3LYP(6-31G(d):UFF)). The results confirmed that the interaction occurred via hydrogen bonding between protons of the glutamic moiety from folic acid and ? electrons from the carbon nanotubes. The single-walled carbon nanotube-folic acid conjugate presented herein is believed to lead the way to new potential applications as carbon nanotube-based drug delivery systems.

  13. Photochemical functionalization of diamond films using a short carbon chain acid

    NASA Astrophysics Data System (ADS)

    Wang, Chun; Huang, Nan; Zhuang, Hao; Yang, Bing; Zhai, Zhaofeng; Jiang, Xin

    2016-02-01

    Diamond is recognized as a promising semiconductor material for biological applications, because of its high chemical stability and biocompatibility. Here, we report an acid with only three carbon chain, acrylic acid (AA), for the functionalization of H-terminated diamond film via photochemical method. The successfully modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy and contact angle analyzer. Our functionalization approach was proven to be simple and facile, which shows a new potential opportunity for the photochemical modification of diamond surface with short carbon chain acid.

  14. X-ray microtomography of hydrochloric acid propagation in carbonate rocks.

    PubMed

    Machado, A C; Oliveira, T J L; Cruz, F B; Lopes, R T; Lima, I

    2015-02-01

    Acid treatments are used in the oil and gas industry, to increase the permeability of the carbonate reservoirs by creating preferential channels, called wormholes. Channels formation is strongly influenced by acid type and injection rate. The aim of this study is to evaluate some characteristics of the microporous system of carbonate rocks, before and after acidizing. For that purpose X-ray high-resolution microtomography was used. The results show that this technique can be used as a reliable method to analyze microstructural characteristics of the wormholes. PMID:25485884

  15. Changing fluxes of carbon and other solutes from the Mekong River

    NASA Astrophysics Data System (ADS)

    Li, Siyue; Bush, Richard T.

    2015-11-01

    Rivers are an important aquatic conduit that connects terrestrial sources of dissolved inorganic carbon (DIC) and other elements with oceanic reservoirs. The Mekong River, one of the world’s largest rivers, is firstly examined to explore inter-annual fluxes of dissolved and particulate constituents during 1923–2011 and their associated natural or anthropogenic controls. Over this period, inter-annual fluxes of dissolved and particulate constituents decrease, while anthropogenic activities have doubled the relative abundance of SO42‑, Cl‑ and Na+. The estimated fluxes of solutes from the Mekong decrease as follows (Mt/y): TDS (40.4) > HCO3‑ (23.4) > Ca2+ (6.4) > SO42‑ (3.8) > Cl‑ (1.74)~Na+ (1.7) ~ Si (1.67) > Mg2+ (1.2) > K+ (0.5). The runoff, land cover and lithological composition significantly contribute to dissolved and particulate yields globally. HCO3‑ and TDS yields are readily predicted by runoff and percent of carbonate, while TSS yield by runoff and population density. The Himalayan Rivers, including the Mekong, are a disproportionally high contributor to global riverine carbon and other solute budgets, and are of course underlined. The estimated global riverine HCO3‑ flux (Himalayan Rivers included) is 34014 × 109 mol/y (0.41 Pg C/y), 3915 Mt/y for solute load, including HCO3‑, and 13553 Mt/y for TSS. Thereby this study illustrates the importance of riverine solute delivery in global carbon cycling.

  16. Mechanism of Pitting Corrosion Prevention by Nitrite in Carbon Steel Exposed to Dilute Salt Solutions

    SciTech Connect

    Philip E. Zapp; John W. Van Zee

    2002-02-01

    The research has developed a broad fundamental understanding of the inhibition action of nitrite ions in preventing nitrate pitting corrosion of carbon steel tanks containing high-level radioactive waste. This fundamental understanding can be applied to specific situations during waste removal for permanent disposition and waste tank closure to ensure that the tanks are maintained safely. The results of the research provide the insight necessary to develop solutions that prevent further degradation.

  17. Changing fluxes of carbon and other solutes from the Mekong River

    PubMed Central

    Li, Siyue; Bush, Richard T.

    2015-01-01

    Rivers are an important aquatic conduit that connects terrestrial sources of dissolved inorganic carbon (DIC) and other elements with oceanic reservoirs. The Mekong River, one of the world’s largest rivers, is firstly examined to explore inter-annual fluxes of dissolved and particulate constituents during 1923–2011 and their associated natural or anthropogenic controls. Over this period, inter-annual fluxes of dissolved and particulate constituents decrease, while anthropogenic activities have doubled the relative abundance of SO42−, Cl− and Na+. The estimated fluxes of solutes from the Mekong decrease as follows (Mt/y): TDS (40.4) > HCO3− (23.4) > Ca2+ (6.4) > SO42− (3.8) > Cl− (1.74)~Na+ (1.7) ~ Si (1.67) > Mg2+ (1.2) > K+ (0.5). The runoff, land cover and lithological composition significantly contribute to dissolved and particulate yields globally. HCO3− and TDS yields are readily predicted by runoff and percent of carbonate, while TSS yield by runoff and population density. The Himalayan Rivers, including the Mekong, are a disproportionally high contributor to global riverine carbon and other solute budgets, and are of course underlined. The estimated global riverine HCO3− flux (Himalayan Rivers included) is 34014 × 109 mol/y (0.41 Pg C/y), 3915 Mt/y for solute load, including HCO3−, and 13553 Mt/y for TSS. Thereby this study illustrates the importance of riverine solute delivery in global carbon cycling. PMID:26522820

  18. Changing fluxes of carbon and other solutes from the Mekong River.

    PubMed

    Li, Siyue; Bush, Richard T

    2015-01-01

    Rivers are an important aquatic conduit that connects terrestrial sources of dissolved inorganic carbon (DIC) and other elements with oceanic reservoirs. The Mekong River, one of the world's largest rivers, is firstly examined to explore inter-annual fluxes of dissolved and particulate constituents during 1923-2011 and their associated natural or anthropogenic controls. Over this period, inter-annual fluxes of dissolved and particulate constituents decrease, while anthropogenic activities have doubled the relative abundance of SO4(2-), Cl(-) and Na(+). The estimated fluxes of solutes from the Mekong decrease as follows (Mt/y): TDS (40.4)?>?HCO3(-) (23.4)?>?Ca(2+) (6.4)?>?SO4(2-) (3.8)?>?Cl(-) (1.74)~Na(+) (1.7)?~?Si (1.67)?>?Mg(2+) (1.2)?>?K(+ 0.5). The runoff, land cover and lithological composition significantly contribute to dissolved and particulate yields globally. HCO3(-) and TDS yields are readily predicted by runoff and percent of carbonate, while TSS yield by runoff and population density. The Himalayan Rivers, including the Mekong, are a disproportionally high contributor to global riverine carbon and other solute budgets, and are of course underlined. The estimated global riverine HCO3(-) flux (Himalayan Rivers included) is 34,014??10(9) mol/y (0.41 Pg C/y), 3915?Mt/y for solute load, including HCO3(-), and 13,553?Mt/y for TSS. Thereby this study illustrates the importance of riverine solute delivery in global carbon cycling. PMID:26522820

  19. FILM FORMATION ON LITHIUM IN PROPYLENE CARBONATE SOLUTIONS UNDER OPEN CIRCUIT CONDITIONS

    SciTech Connect

    Geronov, Y.; Schwager, F.; Muller, R.H.

    1980-06-01

    The nature of protective surface layers formed on lithium in propylene carbonate solutions of LiClO{sub 4} and LiAsF{sub 6} at open circuit has been investigated by electrochemical pulse measurements. The results are consistent with the fastformation of a compact thin layer resulting from the reaction with residual water. This layer acts as a solid ionicconductor. Slow corrosion or decomposition processes produce a thicker porous overlayer.

  20. Electrochemical studies of the film formation on lithium in propylene carbonate solutions under open circuit conditions

    SciTech Connect

    Geronov, Y.; Schwager, F.; Muller, R.H.

    1981-04-01

    The nature of protective surface layers formed on lithium in propylene carbonate solutions of LiClO/sub 4/ and LiAsF/sub 6/ at open circuit has been investigated by electrochemical pulse measurements and other techniques. The results are consistent with the fast formation of a compact thin layer of Li/sub 2/O by reaction with residual water. This layer acts as a solid ionic conductor. Slow corrosion processes produce a thicker porous overlayer.