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Sample records for aqueous sulphuric acid

  1. Removal of Basic Violet 14 from aqueous solution using sulphuric acid activated materials.

    PubMed

    Suresh, S

    2016-01-01

    In this study the adsorption of Basic Violet, 14 from aqueous solution onto sulphuric acid activated materials prepared from Calophyllum inophyllum (CS) and Theobroma cacao (TS) shells were investigated. The experimental data were analysed by Langmuir, Freundlich and Temkin isotherm models. The results showed that CS has a superior adsorption capacity compared to the TS. The adsorption capacity was found to be 1416.43 mg/g for CS and 980.39 mg/g for TS. The kinetic data results at different concentrations were analysed using pseudo first-order and pseudo-second order model. Boyd plot indicates that the dye adsorption onto CS and TS is controlled by film diffusion. The adsorbents were characterised by scanning electron microscopy. The materials used in this study were economical waste products and hence can be an attractive alternative to costlier adsorbents for dye removal in industrial wastewater treatment processes. PMID:27330899

  2. Sulphur Kβ emission spectra reveal protonation states of aqueous sulfuric acid

    NASA Astrophysics Data System (ADS)

    Niskanen, Johannes; Sahle, Christoph J.; Ruotsalainen, Kari O.; Müller, Harald; Kavčič, Matjaž; Žitnik, Matjaž; Bučar, Klemen; Petric, Marko; Hakala, Mikko; Huotari, Simo

    2016-02-01

    In this paper we report an X-ray emission study of bulk aqueous sulfuric acid. Throughout the range of molarities from 1 M to 18 M the sulfur Kβ emission spectra from H2SO4 (aq) depend on the molar fractions and related deprotonation of H2SO4. We compare the experimental results with results from emission spectrum calculations based on atomic structures of single molecules and structures from ab initio molecular dynamics simulations. We show that the S Kβ emission spectrum is a sensitive probe of the protonation state of the acid molecules. Using non-negative matrix factorization we are able to extract the fractions of different protonation states in the spectra, and the results are in good agreement with the simulation for the higher part of the concentration range.

  3. Sulphur Kβ emission spectra reveal protonation states of aqueous sulfuric acid.

    PubMed

    Niskanen, Johannes; Sahle, Christoph J; Ruotsalainen, Kari O; Müller, Harald; Kavčič, Matjaž; Žitnik, Matjaž; Bučar, Klemen; Petric, Marko; Hakala, Mikko; Huotari, Simo

    2016-01-01

    In this paper we report an X-ray emission study of bulk aqueous sulfuric acid. Throughout the range of molarities from 1 M to 18 M the sulfur Kβ emission spectra from H2SO4 (aq) depend on the molar fractions and related deprotonation of H2SO4. We compare the experimental results with results from emission spectrum calculations based on atomic structures of single molecules and structures from ab initio molecular dynamics simulations. We show that the S Kβ emission spectrum is a sensitive probe of the protonation state of the acid molecules. Using non-negative matrix factorization we are able to extract the fractions of different protonation states in the spectra, and the results are in good agreement with the simulation for the higher part of the concentration range. PMID:26888159

  4. Sulphur Kβ emission spectra reveal protonation states of aqueous sulfuric acid

    PubMed Central

    Niskanen, Johannes; Sahle, Christoph J.; Ruotsalainen, Kari O.; Müller, Harald; Kavčič, Matjaž; Žitnik, Matjaž; Bučar, Klemen; Petric, Marko; Hakala, Mikko; Huotari, Simo

    2016-01-01

    In this paper we report an X-ray emission study of bulk aqueous sulfuric acid. Throughout the range of molarities from 1 M to 18 M the sulfur Kβ emission spectra from H2SO4 (aq) depend on the molar fractions and related deprotonation of H2SO4. We compare the experimental results with results from emission spectrum calculations based on atomic structures of single molecules and structures from ab initio molecular dynamics simulations. We show that the S Kβ emission spectrum is a sensitive probe of the protonation state of the acid molecules. Using non-negative matrix factorization we are able to extract the fractions of different protonation states in the spectra, and the results are in good agreement with the simulation for the higher part of the concentration range. PMID:26888159

  5. Diaromatic sulphur-containing 'naphthenic' acids in process waters.

    PubMed

    West, Charles E; Scarlett, Alan G; Tonkin, Andrew; O'Carroll-Fitzpatrick, Devon; Pureveen, Jos; Tegelaar, Erik; Gieleciak, Rafal; Hager, Darcy; Petersen, Karina; Tollefsen, Knut-Erik; Rowland, Steven J

    2014-03-15

    Polar organic compounds found in industrial process waters, particularly those originating from biodegraded petroleum residues, include 'naphthenic acids' (NA). Some NA have been shown to have acute toxicity to fish and also to produce sub-lethal effects. Whilst some of these toxic effects are produced by identifiable carboxylic acids, acids such as sulphur-containing acids, which have been detected, but not yet identified, may produce others. Therefore, in the present study, the sulphur-containing acids in oil sands process water were studied. A fraction (ca 12% by weight of the total NA containing ca 1.5% weight sulphur) was obtained by elution of methylated NA through an argentation solid phase extraction column with diethyl ether. This was examined by multidimensional comprehensive gas chromatography-mass spectrometry (GCxGC-MS) in both nominal and high resolution mass accuracy modes and by GCxGC-sulphur chemiluminescence detection (GCxGC-SCD). Interpretation of the mass spectra and retention behaviour of methyl esters of several synthesised sulphur acids and the unknowns allowed delimitation of the structures, but not complete identification. Diaromatic sulphur-containing alkanoic acids were suggested. Computer modelling of the toxicities of some of the possible acids suggested they would have similar toxicities to one another and to dehydroabietic acid. However, the sulphur-rich fraction was not toxic or estrogenic to trout hepatocytes, suggesting the concentrations of sulphur acids in this sample were too low to produce any such effects in vitro. Further samples should probably be examined for these compounds. PMID:24252453

  6. An isotopic analysis of ionising radiation as a source of sulphuric acid

    NASA Astrophysics Data System (ADS)

    Enghoff, M. B.; Bork, N.; Hattori, S.; Meusinger, C.; Nakagawa, M.; Pedersen, J. O. P.; Danielache, S.; Ueno, Y.; Johnson, M. S.; Yoshida, N.; Svensmark, H.

    2012-06-01

    Sulphuric acid is an important factor in aerosol nucleation and growth. It has been shown that ions enhance the formation of sulphuric acid aerosols, but the exact mechanism has remained undetermined. Furthermore some studies have found a deficiency in the sulphuric acid budget, suggesting a missing source. In this study the production of sulphuric acid from SO2 through a number of different pathways is investigated. The production methods are standard gas phase oxidation by OH radicals produced by ozone photolysis with UV light, liquid phase oxidation by ozone, and gas phase oxidation initiated by gamma rays. The distributions of stable sulphur isotopes in the products and substrate were measured using isotope ratio mass spectrometry. All methods produced sulphate enriched in 34S and we find an enrichment factor (δ34S) of 8.7 ± 0.4‰ (1 standard deviation) for the UV-initiated OH reaction. Only UV light (Hg emission at 253.65 nm) produced a clear non-mass-dependent excess of 33S. The pattern of isotopic enrichment produced by gamma rays is similar, but not equal, to that produced by aqueous oxidation of SO2 by ozone. This, combined with the relative yields of the experiments, suggests a mechanism in which ionising radiation may lead to hydrated ion clusters that serve as nanoreactors for S(IV) to S(VI) conversion.

  7. An isotope view on ionising radiation as a source of sulphuric acid

    NASA Astrophysics Data System (ADS)

    Enghoff, M. B.; Bork, N.; Hattori, S.; Meusinger, C.; Nakagawa, M.; Pedersen, J. O. P.; Danielache, S.; Ueno, Y.; Johnson, M. S.; Yoshida, N.; Svensmark, H.

    2012-02-01

    Sulphuric acid is an important factor in aerosol nucleation and growth. It has been shown that ions enhance the formation of sulphuric acid aerosols, but the exact mechanism has remained undetermined. Furthermore some studies have found a deficiency in the sulphuric acid budget, suggesting a missing source. In this study the production of sulphuric acid from SO2 through a number of different pathways is investigated. The production methods are standard gas phase oxidation by OH radicals produced by ozone photolysis with UV light, liquid phase oxidation by ozone, and gas phase oxidation initiated by gamma rays. The distributions of stable sulphur isotopes in the products and substrate were measured using isotope ratio mass spectrometry. All methods produced sulphate enriched in 34S and we find a δ34S value of 8.7 ± 0.4‰ (1 standard deviation) for the UV-initiated OH reaction. Only UV light (Hg emission at 253.65 nm) produced a clear non-mass-dependent excess of 33S. The pattern of isotopic enrichment produced by gamma rays is similar, but not equal, to that produced by aqueous oxidation of SO2 by ozone. This, combined with the relative yields of the experiments, suggests a mechanism in which ionising radiation may lead to hydrated ion clusters that serve as nanoreactors for S(IV) to S(VI) conversion.

  8. An isotopic view of ionising radiation as a source of sulphuric acid

    NASA Astrophysics Data System (ADS)

    Enghoff, M. B.; Bork, N.; Hattori, S.; Meusinger, C.; Nakagawa, M.; Pedersen, J. O. P.; Danielache, S. O.; Ueno, Y.; Johnson, M. S.; Yoshida, N.; Svensmark, H.

    2012-04-01

    Sulphuric acid is an important factor in aerosol nucleation and growth. It has been shown that ions enhance the formation of sulphuric acid aerosols, but the exact mechanism remains undetermined. Furthermore some studies have found a deficiency in the sulphuric acid budget, suggesting a missing source. In this study the production of sulphuric acid from SO2 through a number of different pathways is investigated. The production methods are standard gas phase oxidation by OH radicals produced by ozone photolysis with UV light, liquid phase oxidation by ozone, and gas phase oxidation initiated by gamma rays. The distributions of stable sulphur isotopes in the products and substrate were measured using isotope ratio mass spectrometry. All methods produced sulphate enriched in 34S and we find a d34S value of 8.7 ± 0.4 ‰ (1 standard deviation) for the UV-initiated OH reaction. Only UV light (Hg emission at 253.65 nm) produced a clear non-mass-dependent excess of 33S. The pattern of isotopic enrichment produced by gamma rays is similar, but not equal, to that produced by aqueous oxidation of SO2 by ozone. This, combined with the relative yields of the experiments, suggests a mechanism in which ionising radiation may lead to hydrated ion clusters that serve as nanoreactors for S(IV) to S(VI) conversion.

  9. Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

    NASA Astrophysics Data System (ADS)

    Hoyle, C. R.; Fuchs, C.; Järvinen, E.; Saathoff, H.; Dias, A.; El Haddad, I.; Gysel, M.; Coburn, S. C.; Tröstl, J.; Bernhammer, A.-K.; Bianchi, F.; Breitenlechner, M.; Corbin, J. C.; Craven, J.; Donahue, N. M.; Duplissy, J.; Ehrhart, S.; Frege, C.; Gordon, H.; Höppel, N.; Heinritzi, M.; Kristensen, T. B.; Molteni, U.; Nichman, L.; Pinterich, T.; Prévôt, A. S. H.; Simon, M.; Slowik, J. G.; Steiner, G.; Tomé, A.; Vogel, A. L.; Volkamer, R.; Wagner, A. C.; Wagner, R.; Wexler, A. S.; Williamson, C.; Winkler, P. M.; Yan, C.; Amorim, A.; Dommen, J.; Curtius, J.; Gallagher, M. W.; Flagan, R. C.; Hansel, A.; Kirkby, J.; Kulmala, M.; Möhler, O.; Stratmann, F.; Worsnop, D.; Baltensperger, U.

    2015-12-01

    The growth of aerosol due to the aqueous phase oxidation of SO2 by O3 was measured in laboratory generated clouds created in the CLOUD chamber at CERN. Experiments were performed at 10 and -10 °C, on acidic (sulphuric acid) and on partially to fully neutralised (ammonium sulphate) seed aerosol. Clouds were generated by performing an adiabatic expansion - pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted by oxidation rates previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and -10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in a dispersed aqueous system are well represented by accepted rates, based on bulk measurements. To the best of our knowledge, these are the first laboratory based measurements of aqueous phase oxidation in a dispersed, super-cooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rates to temperatures below 0 °C is correct.

  10. Electrochemical investigation of lead-calcium alloys in sulphuric acid

    NASA Astrophysics Data System (ADS)

    Bass, K.; Ellis, S. R.; Johnson, M.; Hampson, N. A.

    The hydrogen evolution reaction from, and the cycle life (Pb /ar PbSO 4) of, a series of lead-calcium alloys (0 - 0.2 wt.% Ca) in sulphuric acid hav The exchange current density and Tafel slope for the H.R.E. increase with Ca content up to 0.05 wt.% then decrease to a value approaching that of pure The observed results are explained by: (i) preferential adsorption of calcium ions at the electrode surface; (ii) incorporation of Ca, to form a supersaturated solution, with alloys containing < 0.075 wt.% Ca; (iii) formation of an insoluble, non-conducting layer of calcium sulphate on the high content alloy.

  11. Moving single bubble sonoluminescence in phosphoric acid and sulphuric acid solutions.

    PubMed

    Troia, A; Ripa, D Madonna; Spagnolo, R

    2006-04-01

    The phenomenon of sonoluminescence still presents some unsolved aspects. Recently [Y.T. Didenko, K. Suslick, Molecular Emission during Single Bubble Sonoluminescence, Nature 407 (2000) 877-879.], it was found that a single cavitating air bubble in polar aprotic liquids (including formamide and adiponitrile) can produce very strong sonoluminescence while undergoing macroscopic translation movements in the resonator, a condition known as moving single bubble sonoluminescing (MSBSL). Here we describe some experiments conducted in aqueous solutions of phosphoric and sulphuric acid. In these liquid media, it is possible to reproduce MSBSL and luminescence is emitted even if a trapped bubble is subjected to a strong shape instability, named in the literature "jittering phase". When a moving and luminescing bubble was present and the acoustic pressure gradually increased, we observed the generation of a discrete lattice of trapped bubbles. The bubbles in the lattice emit very intense light flashes and can change their position while maintaining the overall spatial distribution in time. Some preliminary results, obtained from Mie-scattering and measurements of relative light intensity, are reported. PMID:16309944

  12. 21. Public Works Department Drawing 461M8 (1943), 'Sulphuric Acid Storage ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Public Works Department Drawing 461-M-8 (1943), 'Sulphuric Acid Storage System-Storage Tank Details' - Mare Island Naval Shipyard, Acid Mixing Facility, California Avenue & E Street, Vallejo, Solano County, CA

  13. 20. Public Works Department Drawing 461M7 (1943), 'Sulphuric Acid Storage ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Public Works Department Drawing 461-M-7 (1943), 'Sulphuric Acid Storage System-Building 463 Details' - Mare Island Naval Shipyard, Acid Mixing Facility, California Avenue & E Street, Vallejo, Solano County, CA

  14. 29. Public Works Department Drawing 461S18 (1943), 'Sulphuric Acid Storage ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. Public Works Department Drawing 461-S-18 (1943), 'Sulphuric Acid Storage System-Details Of Tank Platform' - Mare Island Naval Shipyard, Acid Mixing Facility, California Avenue & E Street, Vallejo, Solano County, CA

  15. Morphology and evolution of sulphuric acid caves in South Italy

    NASA Astrophysics Data System (ADS)

    D'Angeli, Ilenia M.; De Waele, Jo; Galdenzi, Sandro; Madonia, Giuliana; Parise, Mario; Vattano, Marco

    2016-04-01

    Sulphuric acid speleogenesis (SAS) related to the upwelling of acid water enriched in H2S and CO2 represents an unusual way of cave development. Since meteoric infiltration waters are not necessarily involved in speleogenesis, caves can form without the typical associated karst expressions (i.e. dolines) at the surface. The main mechanism of sulphuric acid dissolution is the oxidation of H2S (Jones et al., 2015) which can be amplified by bacterial mediation (Engel et al., 2004). In these conditions, carbonate dissolution associated with gypsum replacement, is generally believed to be faster than the normal epigenic one (De Waele et al., 2016). In Italy several SAS caves have been identified, but only few systems have been studied in detail: Frasassi and Acquasanta Terme (Marche)(Galdenzi et al., 2010), Monte Cucco (Umbria) (Galdenzi & Menichetti, 1995), and Montecchio (Tuscany) (Piccini et al., 2015). Other preliminary studies have been carried out in Calabria (Galdenzi, 2007) and Sicily (De Waele et al., 2016). Several less studied SAS cave systems located in South Italy, and in particular in Apulia (Santa Cesarea Terme), Sicily (Acqua Fitusa, Acqua Mintina) and Calabria (Mt. Sellaro and Cassano allo Ionio) have been selected in the framework of a PhD thesis on SAS caves and their speleogenesis. Using both limestone tablet weight loss (Galdenzi et al., 2012) and micro erosion meter (MEM) (Furlani et al., 2010) methods the dissolution rate above and under water in the caves will be quantified. Geomorphological observations, landscape analysis using GIS tools, and the analysis of gypsum and other secondary minerals (alunite and jarosite) (stable isotopes and dating) will help to reconstruct the speleogenetic stages of cave formation. Preliminary microbiological analysis will determine the microbial diversity and ecology in the biofilms. References Engel S.A., Stern L.A., Bennett P.C., 2004 - Microbial contributions to cave formation: New insight into sulfuric acid

  16. Microbial ecology of a novel sulphur cycling consortia from AMD: implications for acid generation

    NASA Astrophysics Data System (ADS)

    Loiselle, L. M.; Norlund, K. L.; Hitchcock, A. P.; Warren, L. A.

    2009-05-01

    Recent work1 identified a novel microbial consortia consisting of two bacterial strains common to acid mine drainage (AMD) environments (autotrophic sulphur oxidizer Acidithiobacillus ferrooxidans and heterotrophic Acidiphilium spp.) in an environmental enrichment from a mine tailings lake. The two strains showed a specific spatial arrangement within an EPS macrostructure or "pod" allowing linked metabolic redox cycling of sulphur. Sulphur species characterisation of the pods using scanning transmission X-ray microscopy (STXM) indicated that autotrophic tetrathionate disproportionation by A. ferrooxidans producing colloidal elemental sulphur (S0) is coupled to heterotrophic S0 reduction by Acidiphilium spp. Geochemical modelling of the microbial sulphur reactions indicated that if they are widespread in AMD environments, then global AMD-driven CO2 liberation from mineral weathering have been overestimated by 40-90%1. Given the common co-occurrence of these two bacteria in AMD settings, the purpose of this study was to evaluate if these pods could be induced in the laboratory by pure strains and if so, whether their combined sulphur geochemistry mimicked the previous findings. Laboratory batch experiments assessed the development of pods with pure strain type cultures (A. ferrooxidans ATCC 19859 with mixotroph Acidiphilium acidophilum ATCC 738 or strict heterotroph Acp. cryptum ATCC 2158) using fluorescent in situ hybridization (FISH) imaging. The microbial sulphur geochemistry was characterized under autotrophic conditions identical to those used with the environmental AMD enrichment in which the pods were discovered. Results showed that the combined pure strain A. ferrooxidans and Acp. acidophilum form pods identical in structure to the AMD enrichment. To test the hypothesis that these pods form for mutual metabolic benefit, experiments were performed amending pure strain and AMD enrichment bacterial treatments with organic carbon and/or additional sulphur to

  17. Biofilter for generation of concentrated sulphuric acid from H2S.

    PubMed

    Rabbani, K A; Charles, W; Kayaalp, A; Cord-Ruwisch, R; Ho, G

    2016-08-01

    Biofilters are used for the conversion of odorous hydrogen sulphide to odourless sulphate in wastewater treatment plants under the right conditions of moisture and pH. One of the consequences of maintaining the suitable pH and moisture content is the production of large volumes of weakly acidic leachate. This paper presents a biofilter with a maximum H2S elimination capacity of 16.3 g m(-3) h(-1) and removal efficiency greater than 95 % which produces small volumes (1 mL of solution L(-1) of reactor day(-1)) of sulphuric acid with a concentration greater than 5.5 M after 150 days of continuous operation. The concentrated sulphuric acid was produced by intermittently trickling a minimum amount of nutrient solution down the upflow biofilter which created a moisture and pH gradient within the biofilter resulting in an environment at the top for the bacterial conversion of H2S, while sulphuric acid was accumulated at the base. Genetic diversity profiling of samples taken from different sections of the biofilter confirms that the upper sections of the biofilter had the best environment for the bacteria to convert H2S to sulphate. The formation of concentrated sulphuric acid presents an opportunity for the recovery of sulphur from the waste stream as a usable product. PMID:27189453

  18. Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

    NASA Astrophysics Data System (ADS)

    Hoyle, C. R.; Fuchs, C.; Järvinen, E.; Saathoff, H.; Dias, A.; El Haddad, I.; Gysel, M.; Coburn, S. C.; Tröstl, J.; Bernhammer, A.-K.; Bianchi, F.; Breitenlechner, M.; Corbin, J. C.; Craven, J.; Donahue, N. M.; Duplissy, J.; Ehrhart, S.; Frege, C.; Gordon, H.; Höppel, N.; Heinritzi, M.; Kristensen, T. B.; Molteni, U.; Nichman, L.; Pinterich, T.; Prévôt, A. S. H.; Simon, M.; Slowik, J. G.; Steiner, G.; Tomé, A.; Vogel, A. L.; Volkamer, R.; Wagner, A. C.; Wagner, R.; Wexler, A. S.; Williamson, C.; Winkler, P. M.; Yan, C.; Amorim, A.; Dommen, J.; Curtius, J.; Gallagher, M. W.; Flagan, R. C.; Hansel, A.; Kirkby, J.; Kulmala, M.; Möhler, O.; Stratmann, F.; Worsnop, D. R.; Baltensperger, U.

    2016-02-01

    The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and -10 °C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion - pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and -10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in a dispersed aqueous system can be well represented by using accepted rate constants, based on bulk measurements. To the best of our knowledge, these are the first laboratory-based measurements of aqueous phase oxidation in a dispersed, super-cooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rate constants to temperatures below 0 °C is correct.

  19. Sulphuric acid clouds on Venus: an improved nucleation parameterization and a new microphysical model

    NASA Astrophysics Data System (ADS)

    Määttänen, A.; Bekki, S.; Vehkamäki, H.; Julin, J.; Montmessin, F.; Ortega, I. K.; Lebonnois, S.

    2013-09-01

    Both the clouds of Venus and aerosols found in the Earth's stratosphere are mainly composed of sulphuric acid droplets. On the Earth, the sulphur in the stratosphere originates from surface emissions of long-lived sulphur species, transported to the stratosphere by the general circulation, and from volcanic eruptions that can inject material above the tropopause. On Venus, the source of sulphur is most likely volcanism, but the question is still open. The clouds on Venus are organised in three quite distinct layers with differing properties in terms of particle size distributions and possibly composition. Some early observations hint to species other than sulphuric acid present in the clouds, but recent missions have not been able to verify their existence. The clouds are optically very thick in the visible, inhibiting visual observation of the surface. The lowest cloud layers are very dynamic and the reason for the observed multimodal size distributions could be partly explained by mixing and distinct altitudes of nucleation. However, the possibility of mixed phase clouds and different chemical compositions of the droplets have not yet been excluded.

  20. Aqueous Photochemistry of Glyoxylic Acid.

    PubMed

    Eugene, Alexis J; Xia, Sha-Sha; Guzman, Marcelo I

    2016-06-01

    Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosols (SOA) from gas phase precursors is relatively well understood, studying aqueous chemical reactions contributing to the total SOA budget is the current focus of major attention. Field measurements have revealed that mono-, di-, and oxo-carboxylic acids are abundant species present in SOA and atmospheric waters. This work explores the fate of one of these 2-oxocarboxylic acids, glyoxylic acid, which can photogenerate reactive species under solar irradiation. Additionally, the dark thermal aging of photoproducts is studied by UV-visible and fluorescence spectroscopies to reveal that the optical properties are altered by the glyoxal produced. The optical properties display periodicity in the time domain of the UV-visible spectrum of chromophores with absorption enhancement (thermochromism) or loss (photobleaching) during nighttime and daytime cycles, respectively. During irradiation, excited state glyoxylic acid can undergo α-cleavage or participate in hydrogen abstractions. The use of (13)C nuclear magnetic resonance spectroscopy (NMR) analysis shows that glyoxal is an important intermediate produced during direct photolysis. Glyoxal quickly reaches a quasi-steady state as confirmed by UHPLC-MS analysis of its corresponding (E) and (Z) 2,4-dinitrophenylhydrazones. The homolytic cleavage of glyoxylic acid is proposed as a fundamental step for the production of glyoxal. Both carbon oxides, CO2(g) and CO(g) evolving to the gas-phase, are quantified by FTIR spectroscopy. Finally, formic acid, oxalic acid, and tartaric acid photoproducts are identified by ion chromatography (IC) with conductivity and electrospray (ESI) mass spectrometry (MS) detection and (1)H NMR spectroscopy. A reaction mechanism is proposed based on all experimental observations. PMID:27192089

  1. Isolation and fractionation of soil humin using alkaline urea and dimethylsulphoxide plus sulphuric acid.

    PubMed

    Song, Guixue; Hayes, Michael H B; Novotny, Etelvino H; Simpson, Andre J

    2011-01-01

    Humin, the most recalcitrant and abundant organic fraction of soils and of sediments, is a significant contributor to the stable carbon pool in soils and is important for the global carbon budget. It has significant resistance to transformations by microorganisms. Based on the classical operational definition, humin can include any humic-type substance that is not soluble in water at any pH. We demonstrate in this study how sequential exhaustive extractions with 0.1 M sodium hydroxide (NaOH) + 6 M urea, followed by dimethylsulphoxide (DMSO) + 6% (v/v) sulphuric acid (H(2)SO(4)) solvent systems, can extract 70-80% of the residual materials remaining after prior exhaustive extractions in neutral and aqueous basic media. Solid-state (13)C NMR spectra have shown that the components isolated in the base + urea system were compositionally similar to the humic and fulvic acid fractions isolated at pH 12.6 in the aqueous media. The NMR spectra indicated that the major components isolated in the DMSO + H(2)SO(4) medium had aliphatic hydrocarbon associated with carboxyl functionalities and with lesser amounts of carbohydrate and peptide and minor amounts of lignin-derived components. The major components will have significant contributions from long-chain fatty acids, waxes, to cuticular materials. The isolates in the DMSO + H(2)SO(4) medium were compositionally similar to the organic components that resisted solvation and remained associated with the soil clays. It is concluded that the base + urea system released humic and fulvic acids held by hydrogen bonding or by entrapment within the humin matrix. The recalcitrant humin materials extracted in DMSO + H(2)SO(4) are largely biological molecules (from plants and the soil microbial population) that are likely to be protected from degradation by their hydrophobic moieties and by sorption on the soil clays. Thus, the major components of humin do not satisfy the classical definitions for humic

  2. Isolation and fractionation of soil humin using alkaline urea and dimethylsulphoxide plus sulphuric acid

    NASA Astrophysics Data System (ADS)

    Song, Guixue; Hayes, Michael H. B.; Novotny, Etelvino H.; Simpson, Andre J.

    2011-01-01

    Humin, the most recalcitrant and abundant organic fraction of soils and of sediments, is a significant contributor to the stable carbon pool in soils and is important for the global carbon budget. It has significant resistance to transformations by microorganisms. Based on the classical operational definition, humin can include any humic-type substance that is not soluble in water at any pH. We demonstrate in this study how sequential exhaustive extractions with 0.1 M sodium hydroxide (NaOH) + 6 M urea, followed by dimethylsulphoxide (DMSO) + 6% ( v/ v) sulphuric acid (H2SO4) solvent systems, can extract 70-80% of the residual materials remaining after prior exhaustive extractions in neutral and aqueous basic media. Solid-state 13C NMR spectra have shown that the components isolated in the base + urea system were compositionally similar to the humic and fulvic acid fractions isolated at pH 12.6 in the aqueous media. The NMR spectra indicated that the major components isolated in the DMSO + H2SO4 medium had aliphatic hydrocarbon associated with carboxyl functionalities and with lesser amounts of carbohydrate and peptide and minor amounts of lignin-derived components. The major components will have significant contributions from long-chain fatty acids, waxes, to cuticular materials. The isolates in the DMSO + H2SO4 medium were compositionally similar to the organic components that resisted solvation and remained associated with the soil clays. It is concluded that the base + urea system released humic and fulvic acids held by hydrogen bonding or by entrapment within the humin matrix. The recalcitrant humin materials extracted in DMSO + H2SO4 are largely biological molecules (from plants and the soil microbial population) that are likely to be protected from degradation by their hydrophobic moieties and by sorption on the soil clays. Thus, the major components of humin do not satisfy the classical definitions for humic substances which emphasise that these arise from

  3. Estimation of glycated hemoglobin by 2,6-dimethylphenol: Sulphuric acid conventional method.

    PubMed

    Mallya, H M; Pattabiraman, T N

    2001-01-01

    Glycated hemoglobin levels in hemolysate of normal and diabetic patients were determined by the 2,6-dimethylphenol:57.5% sulphuric acid conventional method and the values were 0.39±025 and 0.69±0.21 moles of hydroxymethylfurfural(HMF)/mole of globin, respectively. The mean increase in glycated hemoglobin values in diabetics (1.8fold) was highly significant (p<0.001). A good correlation (r=0.95) was found between the glycated hemoglobin values obtained by this method and the phenol:sulphuric acid method. The values obtained by former method were about 1.2-1.4 times the values by the phenol:sulphuric acid method. This study indicates that conventional 2,6-dimethylphenol: 57.5% sulphuric acid method is more sensitive for the estimation of glycated hemoglobin than any other method based on the same principle. It is less time consuming, reliable and hence can be employed for the routine laboratory estimation of glycated hemoglobin for the assessment of glycemic control. PMID:23105290

  4. Effect of ions on the measurement of sulphuric acid in the CLOUD experiment at CERN

    NASA Astrophysics Data System (ADS)

    Rondo, L.; Kürten, A.; Ehrhart, S.; Schobesberger, S.; Franchin, A.; Junninen, H.; Petäjä, T.; Sipilä, M.; Worsnop, D. R.; Curtius, J.

    2014-07-01

    Ternary aerosol nucleation experiments were conducted in the CLOUD chamber at CERN in order to investigate the influence of ions on new particle formation. Neutral and ion-induced nucleation experiments, i.e., with and without the presence of ions, were carried out under precisely controlled conditions. The sulphuric acid concentration was measured with a Chemical Ionization Mass Spectrometer (CIMS) during the new particle formation experiments. The added ternary trace gases were ammonia (NH3), dimethylamine (DMA, C2H7N) or oxidised products of pinanediol (PD, C10H18O2). When pinanediol was introduced into the chamber, an increase in the mass spectrometric signal used to determine the sulphuric acid concentration (m/z 97, i.e., HSO4-) was observed due to ions from the CLOUD chamber. The enhancement was only observed during ion-induced nucleation measurements by using either galactic cosmic rays (GCR) or the proton synchrotron (PS) pion beam for the ion generation, respectively. The ion effect typically involved an increase in the apparent sulphuric acid concentration by a factor of ~2 to 3 and was qualitatively verified by the ion measurements by an Atmospheric Pressure interface-Time Of Flight (APi-TOF) mass spectrometer. By applying a high voltage (HV) clearing field inside the CLOUD chamber the ion effect on the CIMS measurement was completely eliminated since, under these conditions, small ions are swept from the chamber in about one second. In order to exclude the ion effect and to provide corrected sulphuric acid concentrations during the GCR and PS beam nucleation experiments, a parameterisation was derived that utilizes the trace gas concentrations and the UV light intensity as input parameters. Atmospheric sulphuric acid measurements with a CIMS showed an insignificant ion effect.

  5. Heterogeneous freezing of single sulphuric acid solution droplets: laboratory experiments utilising an acoustic levitator

    NASA Astrophysics Data System (ADS)

    Ettner, M.; Mitra, S. K.; Borrmann, S.

    2004-03-01

    The heterogeneous freezing temperatures of single binary sulphuric acid solution droplets were measured in dependency of acid concentration down to temperatures as low as -70°C. In order to avoid influence of supporting substrates on the freezing characteristics, the droplets were suspended by means of an acoustic levitator. The droplets contained immersed particles of graphite, kaolin or montmorillonite in order to study the influence of the presence of such contamination on the freezing temperature. The radii of the suspended droplets spanned the range between 0,4 and 1,1 mm and the concentration of the sulphuric acid solution varied between 5 and 25 weight percent. The presence of the particles in the solution raises the freezing temperature with respect to homogeneous freezing of these solution droplets. The pure solution droplets can be supercooled up to 40° below the ice-acid solution thermodynamic equilibrium curve. Depending on the concentration of sulphuric acid and the nature of the impurity the polluted droplets froze between -11°C and -35°C. The experimental set-up, combining a deep freezer with a movable ultrasonic levitator and suitable optics, proved to be a useful approach for such investigations on individual droplets.

  6. A classical reactive potential for molecular clusters of sulphuric acid and water

    NASA Astrophysics Data System (ADS)

    Stinson, Jake L.; Kathmann, Shawn M.; Ford, Ian J.

    2016-01-01

    We present a two-state empirical valence bond (EVB) potential describing interactions between sulphuric acid and water molecules and designed to model proton transfer between them within a classical dynamical framework. The potential has been developed in order to study the properties of molecular clusters of these species, which are thought to be relevant to atmospheric aerosol nucleation. The particle swarm optimisation method has been used to fit the parameters of the EVB model to density functional theory (DFT) calculations. Features of the parametrised model and DFT data are compared and found to be in satisfactory agreement. In particular, it is found that a single sulphuric acid molecule will donate a proton when clustered with four water molecules at 300 K and that this threshold is temperature dependent.

  7. Chemical composition and minerals in pyrite ash of an abandoned sulphuric acid production plant.

    PubMed

    Oliveira, Marcos L S; Ward, Colin R; Izquierdo, Maria; Sampaio, Carlos H; de Brum, Irineu A S; Kautzmann, Rubens M; Sabedot, Sydney; Querol, Xavier; Silva, Luis F O

    2012-07-15

    The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of submicron, ultrafine and nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich submicron, ultrafine and nanoparticles within the ash may contain high proportions of toxic elements such as As, Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and submicron, ultrafine and nanominerals (e.g. oxides, sulphates, clays) in concentrations of up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials. PMID:22613465

  8. Molecular understanding of sulphuric acid-amine particle nucleation in the atmosphere.

    PubMed

    Almeida, João; Schobesberger, Siegfried; Kürten, Andreas; Ortega, Ismael K; Kupiainen-Määttä, Oona; Praplan, Arnaud P; Adamov, Alexey; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, André; Dommen, Josef; Donahue, Neil M; Downard, Andrew; Dunne, Eimear; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Guida, Roberto; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Henschel, Henning; Jokinen, Tuija; Junninen, Heikki; Kajos, Maija; Kangasluoma, Juha; Keskinen, Helmi; Kupc, Agnieszka; Kurtén, Theo; Kvashin, Alexander N; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Leppä, Johannes; Loukonen, Ville; Makhmutov, Vladimir; Mathot, Serge; McGrath, Matthew J; Nieminen, Tuomo; Olenius, Tinja; Onnela, Antti; Petäjä, Tuukka; Riccobono, Francesco; Riipinen, Ilona; Rissanen, Matti; Rondo, Linda; Ruuskanen, Taina; Santos, Filipe D; Sarnela, Nina; Schallhart, Simon; Schnitzhofer, Ralf; Seinfeld, John H; Simon, Mario; Sipilä, Mikko; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Vaattovaara, Petri; Viisanen, Yrjo; Virtanen, Annele; Vrtala, Aron; Wagner, Paul E; Weingartner, Ernest; Wex, Heike; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Yli-Juuti, Taina; Carslaw, Kenneth S; Kulmala, Markku; Curtius, Joachim; Baltensperger, Urs; Worsnop, Douglas R; Vehkamäki, Hanna; Kirkby, Jasper

    2013-10-17

    Nucleation of aerosol particles from trace atmospheric vapours is thought to provide up to half of global cloud condensation nuclei. Aerosols can cause a net cooling of climate by scattering sunlight and by leading to smaller but more numerous cloud droplets, which makes clouds brighter and extends their lifetimes. Atmospheric aerosols derived from human activities are thought to have compensated for a large fraction of the warming caused by greenhouse gases. However, despite its importance for climate, atmospheric nucleation is poorly understood. Recently, it has been shown that sulphuric acid and ammonia cannot explain particle formation rates observed in the lower atmosphere. It is thought that amines may enhance nucleation, but until now there has been no direct evidence for amine ternary nucleation under atmospheric conditions. Here we use the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN and find that dimethylamine above three parts per trillion by volume can enhance particle formation rates more than 1,000-fold compared with ammonia, sufficient to account for the particle formation rates observed in the atmosphere. Molecular analysis of the clusters reveals that the faster nucleation is explained by a base-stabilization mechanism involving acid-amine pairs, which strongly decrease evaporation. The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid-dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates. Our experimental measurements are well reproduced by a dynamical model based on quantum chemical calculations of binding energies of molecular clusters, without any fitted parameters. These results show that, in regions of the atmosphere near amine sources, both amines and sulphur dioxide should be considered when assessing the impact of anthropogenic activities on particle formation. PMID:24097350

  9. Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation.

    PubMed

    Kirkby, Jasper; Curtius, Joachim; Almeida, João; Dunne, Eimear; Duplissy, Jonathan; Ehrhart, Sebastian; Franchin, Alessandro; Gagné, Stéphanie; Ickes, Luisa; Kürten, Andreas; Kupc, Agnieszka; Metzger, Axel; Riccobono, Francesco; Rondo, Linda; Schobesberger, Siegfried; Tsagkogeorgas, Georgios; Wimmer, Daniela; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, André; Dommen, Josef; Downard, Andrew; Ehn, Mikael; Flagan, Richard C; Haider, Stefan; Hansel, Armin; Hauser, Daniel; Jud, Werner; Junninen, Heikki; Kreissl, Fabian; Kvashin, Alexander; Laaksonen, Ari; Lehtipalo, Katrianne; Lima, Jorge; Lovejoy, Edward R; Makhmutov, Vladimir; Mathot, Serge; Mikkilä, Jyri; Minginette, Pierre; Mogo, Sandra; Nieminen, Tuomo; Onnela, Antti; Pereira, Paulo; Petäjä, Tuukka; Schnitzhofer, Ralf; Seinfeld, John H; Sipilä, Mikko; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Vanhanen, Joonas; Viisanen, Yrjo; Vrtala, Aron; Wagner, Paul E; Walther, Hansueli; Weingartner, Ernest; Wex, Heike; Winkler, Paul M; Carslaw, Kenneth S; Worsnop, Douglas R; Baltensperger, Urs; Kulmala, Markku

    2011-08-25

    Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100-1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H(2)SO(4)-H(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation. PMID:21866156

  10. A chamber study of the influence of boreal BVOC emissions and sulphuric acid on nanoparticle formation rates at ambient concentrations

    NASA Astrophysics Data System (ADS)

    Dal Maso, M.; Liao, L.; Wildt, J.; Kiendler-Scharr, A.; Kleist, E.; Tillmann, R.; Sipilä, M.; Hakala, J.; Lehtipalo, K.; Ehn, M.; Kerminen, V.-M.; Kulmala, M.; Worsnop, D.; Mentel, T.

    2014-12-01

    Aerosol formation from biogenic and anthropogenic precursor trace gases in continental background areas affects climate via altering the amount of available cloud condensation nuclei. Significant uncertainty still exists regarding the agents controlling the formation of aerosol nanoparticles. We have performed experiments in the Jülich Plant-Atmosphere Simulation Chamber with instrumentation for the detection of sulphuric acid and nanoparticles, and present the first simultaneous chamber observations of nanoparticles, sulphuric acid, and realistic levels and mixtures of biogenic volatile compounds (BVOC). We present direct laboratory observations of nanoparticle formation from sulphuric acid and realistic BVOC precursor vapor mixtures performed at atmospherically relevant concentration levels. We directly measured particle formation rates separately from particle growth rates. From this, we established that in our experiments, the formation rate was proportional to the product of sulphuric acid and biogenic VOC emission strength. The formation rates were consistent with a mechanism in which nucleating BVOC oxidation products are rapidly formed and activate with sulphuric acid. The growth rate of nanoparticles immediately after birth was best correlated with estimated products resulting from BVOC ozonolysis.

  11. Sulphuric acid speleogenesis and landscape evolution: Montecchio cave, Albegna river valley (Southern Tuscany, Italy)

    NASA Astrophysics Data System (ADS)

    Piccini, Leonardo; De Waele, Jo; Galli, Ermanno; Polyak, Victor J.; Bernasconi, Stefano M.; Asmerom, Yemane

    2015-01-01

    Montecchio cave (Grosseto province, Tuscany, Italy) opens at 320 m asl, in a small outcrop of Jurassic limestone (Calcare Massiccio Fm.), close to the Albegna river. This area is characterised by the presence of several thermal springs and the outcropping of travertine deposits at different altitudes. The Montecchio cave, with passage length development of over 1700 m, is characterised by the presence of several sub-horizontal passages and many medium- and small-scale morphologies indicative of sulphuric acid speleogenesis (SAS). The thermal aquifer is intercepted at a depth of about 100 m below the entrance: the water temperature exceeds 30 °C and sulphate content is over 1300 mg l- 1. The cave hosts large gypsum deposits from 40 to 100 m below the entrance that are by-products of the reaction between sulphuric acid and the carbonate host rock. The lower part of the cave hosts over 1 m thick calcite cave raft deposits, which are evidence of long-standing, probably thermal, water in an evaporative environment related to significant air currents. Sulphur isotopes of gypsum have negative δ34S values (from - 28.3 to - 24.2‰), typical of SAS. Calcite cave rafts and speleogenetic gypsum both yield young U/Th ages varying from 68.5 ka to 2 ka BP, indicating a rapid phase of dewatering followed by gypsum precipitation in aerate environment. This fast water table lowering is related to a rapid incision of the nearby Albegna river, and was followed by a 20-30 m fluctuation of the thermal water table, as recorded in the calcite raft deposits and gypsum crusts.

  12. Sulphuric acid marketed in water bottle in India: A cause for fatal accidental poisoning in an adult.

    PubMed

    Behera, C; Chopra, Saurav; Garg, Aayushi; Kumar, Rajesh

    2016-06-01

    Corrosive acid ingestion is a rare but serious health hazard with fatal complications. Cases of suicidal and accidental acid ingestion have been documented in the scientific literature. Accidental acid poisoning due to a mistaken identity of the bottle containing sulphuric acid is a matter of grave concern especially in a household set-up. We hereby report a fatal case of accidental sulphuric acid ingestion in an adult, who unsuspectingly swallowed about 50 ml of 'toilet-cleaner' at his residence. The bottle containing the acid was recently purchased from a local vendor and placed with water bottles in the kitchen. The autopsy and toxicological findings of this case are discussed in this paper with discussion of medico-legal issues on the sale and use of such corrosive acids in illegal bottles and its subsequent health hazards in India. PMID:26837566

  13. Removing sulphur oxides from a fluid stream

    SciTech Connect

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

    2014-04-08

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

  14. Copper and cobalt recovery from pyrite ashes of a sulphuric acid plant.

    PubMed

    Erust, Ceren; Akcil, Ata

    2016-06-01

    The pyrite ashes formed as waste material during the calcination of concentrated pyrite ore used for producing sulphuric acid not only has a high iron content but also contains economically valuable metals. These wastes, which are currently landfilled or dumped into the sea, cause serious land and environmental pollution problems owing to the release of acids and toxic substances. In this study, physical (sulphation roasting) and hydrometallurgical methods were evaluated for their efficacy to recover non-iron metals with a high content in the pyrite ashes and to prevent pollution thereby. The preliminary enrichment tests performed via sulphation roasting were conducted at different roasting temperatures and with different acid amounts. The leaching tests investigated the impact of the variables, including different solvents, acid concentrations and leach temperatures on the copper and cobalt leaching efficiency. The experimental studies indicated that the pre-enrichment via sulphation roasting method has an effect on the leaching efficiencies of copper and cobalt, and that approximate recoveries of 80% copper and 70% cobalt were achieved in the H2O2-added H2SO4 leaching tests. PMID:26987736

  15. Equilibrium distribution of dissolved sulphur species in water at 25°C and 1 atm total pressure

    USGS Publications Warehouse

    Garrels, R.M.; Naeser, C.R.

    1958-01-01

    The Eh-pH diagrams for the equilibrium concentrations in aqueous solution at 25°C of native sulphur and all the various sulphur-containing ions and acids from which the ions are produced have been constructed for systems having a total sulphur concentration of 0.1 molar. The composite of these diagrams indicates that elemental sulphur, H2S, HS− HSO4− and SO4 are the species that predominate in the environments that might be found in nature. This indication is in agreement with the composition of all sulphur-containing minerals.

  16. Conductance Studies of Aqueous Succinic Acid

    NASA Astrophysics Data System (ADS)

    Apelblat, Alexander; Barthel, Josef

    1992-03-01

    Conductance measurements of aqueous solutions of succinic acid and of di-sodium succinate were performed from 278.15 to 308.15 K and the limiting conductances λ0 (1/2 Succ2- ) are reported. The Waiden product is independent of temperature: λ0(1/2 Succ2-)*η(T) = 0.503 ± 0.001. The salt conductances closely obey the Onsager limiting law. The evaluation of the equilibrium constants for the primary and secondary steps of dissociation, K1 and K2, and the limiting conductances of the hydrosuccinate ion, λ0(HSucc-), are discussed using the Quint and Viallard conductance equation

  17. Microstructural Models of Alumina Nanotubes and Anodic Porous Alumina Film Formed in Sulphuric Acid

    NASA Astrophysics Data System (ADS)

    Pu, Lin; Chen, Zhi-Qiang; Tan, Chao; Yang, Zheng; Zou, Jian-Ping; Bao, Xi-Mao; Feng, Duan; Shi, Yi; Zheng, You-Dou

    2002-03-01

    Electrochemical stepwise anodization of aluminium in dilute sulphuric acid results in the formation of alumina nanotubes (ANTs) due to the hexagonal split of the anodic porous alumina (APA) film along the cell boundaries containing many voids; that is, the ANTs are the completely detached cell of the APA film. The inner diameters of the ANTs are in the range of 10-20 nm, and the aspect ratio (inner diameter/length) of the ANTs can be about 80. The relations found for pore diameter, cell diameter and barrier layer thickness are around 1, 2.7 and 0.85 nm/V, respectively. Transmission electron microscopy (TEM) reveals that the ANT wall has a three-shell structure: an outer shell (metal/oxide interface) consisting of pure alumina oxide, a middle shell of the hydrated oxide or/and hydroxide and an inner shell (oxide/electrolyte interface) of anion incorporated oxide with the thickness ratio of 1:1:2. The structural change of ANTs induced by e-beam irradiation in TEM indicates that the thermal instability of the hydrated oxide or/and hydroxide within the cell wall might be an alternative origin contributing to the self-organization of the cells, leading to a densely packed triangular cell lattice of the APA film.

  18. Effects of gaseous sulphuric acid on diesel exhaust nanoparticle formation and characteristics.

    PubMed

    Rönkkö, Topi; Lähde, Tero; Heikkilä, Juha; Pirjola, Liisa; Bauschke, Ulrike; Arnold, Frank; Schlager, Hans; Rothe, Dieter; Yli-Ojanperä, Jaakko; Keskinen, Jorma

    2013-10-15

    Diesel exhaust gaseous sulphuric acid (GSA) concentrations and particle size distributions, concentrations, and volatility were studied at four driving conditions with a heavy duty diesel engine equipped with oxidative exhaust after-treatment. Low sulfur fuel and lubricant oil were used in the study. The concentration of the exhaust GSA was observed to vary depending on the engine driving history and load. The GSA affected the volatile particle fraction at high engine loads; higher GSA mole fraction was followed by an increase in volatile nucleation particle concentration and size as well as increase of size of particles possessing nonvolatile core. The GSA did not affect the number of nonvolatile particles. At low and medium loads, the exhaust GSA concentration was low and any GSA driven changes in particle population were not observed. Results show that during the exhaust cooling and dilution processes, besides critical in volatile nucleation particle formation, GSA can change the characteristics of all nucleation mode particles. Results show the dual nature of the nucleation mode particles so that the nucleation mode can include simultaneously volatile and nonvolatile particles, and fulfill the previous results for the nucleation mode formation, especially related to the role of GSA in formation processes. PMID:24044459

  19. Speciation in aqueous solutions of nitric acid.

    PubMed

    Hlushak, S; Simonin, J P; De Sio, S; Bernard, O; Ruas, A; Pochon, P; Jan, S; Moisy, P

    2013-02-28

    In this study, speciation in aqueous solutions of nitric acid at 25 °C was assessed in two independent ways. First, Raman experiments were carried out and interpreted in terms of free nitrate ions, ion pairs and neutral HNO(3) molecules. In parallel, a model was developed to account for the formation of these two kinds of pairs. It was based on an extension of the binding mean spherical approximation (BiMSA), or associative MSA (AMSA), in which the size and the charge of the ions in the chemical pair may differ from those of the free ions. A simultaneous fit of the osmotic coefficient and of the proportion of free ions (obtained from Raman spectroscopy experiments) led to an estimation of the speciation in nitric acid solutions. The result obtained using this procedure was compared with the estimation obtained from the Raman experiments. PMID:23258765

  20. Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water

    SciTech Connect

    Stinson, Jake L. Ford, Ian J.; Kathmann, Shawn M.

    2014-01-14

    The nucleation of particles from trace gases in the atmosphere is an important source of cloud condensation nuclei, and these are vital for the formation of clouds in view of the high supersaturations required for homogeneous water droplet nucleation. The methods of quantum chemistry have increasingly been employed to model nucleation due to their high accuracy and efficiency in calculating configurational energies; and nucleation rates can be obtained from the associated free energies of particle formation. However, even in such advanced approaches, it is typically assumed that the nuclei have a classical nature, which is questionable for some systems. The importance of zero-point motion (also known as quantum nuclear dynamics) in modelling small clusters of sulphuric acid and water is tested here using the path integral molecular dynamics method at the density functional level of theory. The general effect of zero-point motion is to distort the mean structure slightly, and to promote the extent of proton transfer with respect to classical behaviour. In a particular configuration of one sulphuric acid molecule with three waters, the range of positions explored by a proton between a sulphuric acid and a water molecule at 300 K (a broad range in contrast to the confinement suggested by geometry optimisation at 0 K) is clearly affected by the inclusion of zero point motion, and similar effects are observed for other configurations.

  1. RECOVERY OF ACTINIDES FROM AQUEOUS NITRIC ACID SOLUTIONS

    DOEpatents

    Ader, M.

    1963-11-19

    A process of recovering actinides is presented. Tetravalent actinides are extracted from rare earths in an aqueous nitric acid solution with a ketone and back-extracted from the ketone into an aqueous medium. The aqueous actinide solution thus obtained, prior to concentration by boiling, is sparged with steam to reduce its ketone to a maximum content of 3 grams per liter. (AEC)

  2. The amino acid sequence of protein SCMK-B2A from the high-sulphur fraction of wool keratin

    PubMed Central

    Elleman, T. C.

    1972-01-01

    1. The amino acid sequence of protein SCMK-B2A, a reduced and S-carboxymethylated protein from the high-sulphur fraction of wool, has been determined. 2. This protein of 171 amino acid residues displays both a high degree of internal homology and extensive external homology with other members of the SCMK-B2 group of proteins. 3. Evidence is presented which suggests that the SCMK-B2 group of proteins are produced by separate non-allelic genes. ImagesPLATE 1 PMID:4679226

  3. 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…

  4. PROCESS FOR RECOVERING URANIUM FROM AQUEOUS PHOSPHORIC ACID LIQUORS

    DOEpatents

    Schmitt, J.M.

    1962-09-01

    A liquid-liquid extraction method is given for recovering uranium values from aqueous solutions. An acidic aqueous solution containing uranium values is contacted with an organic phase comprising an organic diluent and the reaction product of phosphorous pentoxide and a substantially pure dialkylphosphoric acid. The uranium values are transferred to the organic phase even from aqueous solutions containing a high concentration of strong uranium complexing agents such as phosphate ions. (AEC)

  5. Species differences in the conjugation of 4-hydroxy-3-methoxyphenylethanol with glucuronic acid and sulphuric acid.

    PubMed

    Wong, K P

    1976-07-15

    The biosynthesis of the glucuronide and sulphate conjugates of 4-hydroxy-3-methoxyphenylethanol was demonstrated in vitro by using the high-speed supernatant and microsomal fractions of liver respectively. These two conjugates were also produced simultaneously by using the post-mitochondrial fraction of rat, rabbit or guinea-pig liver. In contrast only the glucuronide was synthesized by human liver and only the sulphate by mouse and cat livers. Neither of these conjugates was formed by the kidney or the small or large intestine of the rat. A high sulphate-conjugating activity was observed in mouse kidney; the rate of sulphation of 4-hydroxy-3-methoxyphenylethanol with kidney homogenate and high-speed supernatant preparations was 1.8 times greater than with liver preparations. The sulpho-conjugates of 4-hydroxy-3-methoxyphenylethanol and 4-hydroxy-3-methoxy-phenylglycol were also formed by enzyme preparations of rabbit adrenal and rat brain; the glycol was the better substrate in the latter system. Mouse brain did not possess any sulphotransferase activity. For the conjugation of 4-hydroxy-3-methoxyphenylethanol by rabbit liver, the Km for UDP-glucuronic acid was 0.22 mM and that for Na2SO4 was 3.45 mM. The sulphotransferase has a greater affinity for 4-hydroxy-3-methoxyphenyl-ethanol than has glucuronyltransferase, as indicated by their respective Km values of 0.036 and 1.3 mM. It was concluded that sulphate conjugation of 4-hydroxy-3-methoxyphenylethanol predominates in most species of animals. PMID:9078

  6. Studies on the high-sulphur proteins of reduced Merino wool. Amino acid sequence of protein SCMKB-IIIB4

    PubMed Central

    Swart, L. S.; Haylett, T.

    1971-01-01

    The complete amino acid sequence of protein SCMKB-IIIB4 is presented. It is closely related to the sequence of protein SCMKB-IIIB3 (Haylett, Swart & Parris, 1971) differing in only four positions. The peptic and thermolysin peptides of protein SCMKB-IIIB4 were analysed by the dansyl–Edman method (Gray, 1967) and by tritium-labelling of C-terminal residues (Matsuo, Fujimoto & Tatsuno, 1966). This protein is the third member of a group of high-sulphur wool proteins with molecular weight of about 11400. It consists of 98 residues and has acetylalanine and carboxymethylcysteine as N- and C-terminal residues respectively. PMID:4942536

  7. Optimization of the 3-Point Bending Failure of Anodized Aluminum Formed in Tartaric/Sulphuric Acid Using Doehlert Design

    NASA Astrophysics Data System (ADS)

    Bensalah, W.; Feki, M.; De-Petris Wery, M.; Ayedi, H. F.

    2015-02-01

    The bending failure of anodized aluminum in tartaric/sulphuric acid bath was modeled using Doehlert design. Bath temperature, anodic current density, sulphuric acid, and tartaric acid concentrations were retained as variables. Thickness measurements and 3-point bending experiments were conducted. The deflection at failure ( D f) and the maximum load ( F m) of each sample were, then, deducted from the corresponding flexural responses. The treatment of experimental results has established mathematical models of second degree reflecting the relation of cause and effect between the factors and the studied properties. The optimum path study of thickness, deflection at failure, and maximum load, showed that the three optima were opposite. Multicriteria optimization using the desirability function was achieved in order to maximize simultaneously the three responses. The optimum conditions were: C tar = 18.2 g L-1, T = 17.3 °C, J = 2.37 A dm-2, C sul = 191 g L-1, while the estimated response values were e = 57.7 µm, D f = 5.6 mm, and F m = 835 N. Using the established models, a mathematical correlation was found between deflection at failure and thickness of the anodic oxide layer. Before bending tests, aluminum oxide layer was examined by scanning electron microscopy (SEM) and atomic force microscopy. After tests, the morphology and the composition of the anodic oxide layer were inspected by SEM, optical microscopy, and glow-discharge optical emission spectroscopy.

  8. Hydrometallurgical process for zinc recovery from electric arc furnace dust (EAFD): part I: Characterization and leaching by diluted sulphuric acid.

    PubMed

    Oustadakis, P; Tsakiridis, P E; Katsiapi, A; Agatzini-Leonardou, S

    2010-07-15

    The present paper is the first of a series of two articles dealing with the development of an integrated process for the recovery of zinc from electric arc furnace dust (EAFD), a hazardous industrial waste generated in the collection of particulate material during steelmaking process via electric arc furnace. Part I presents the EAFD characterization and its leaching process by diluted sulphuric acid, whereas Part II deals with the purification of the leach liquor and the recovery of zinc by solvent extraction/electrowinning. The characterization of the examined electric arc furnace dust was carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The leaching process was based on the Zn extraction with diluted sulphuric acid from EAFD under atmospheric conditions and without using any preliminary treatment. Statistical design and analysis of experiments were used, in order to determine the main effects and interactions of the leaching process factors, which were: acid normality, temperature and solid to liquid ratio. The zinc recovery efficiency on the basis of EAFD weight reached 80%. X-ray diffraction and scanning electron microscopy were used for the characterization of the leached residues. PMID:20129730

  9. [Digestive burns by simultaneous oral and rectal self-administration of ingestion sulphuric acid: an unusual mode of suicide].

    PubMed

    Soro, Kountélé Gona; Attia, Koffi Alain; Coulibaly, Adama; Koffi, Gnangoran Marcelin; Yapo, Patrice; Ehua, Somian Francis; Miessan, Jean-Baptiste Kanga

    2008-01-01

    The authors report an unusual mode of suicide in two patients admitted to the Teaching Hospital of Yopougon. One 26-year-old woman swallowed sulphuric acid and then self-administered more of the same product rectally. She presented with abdominal pain, vomiting, bloody diarrhoea, without fever (T=37,9 degrees C). The abdomen did not appear to require surgery. Endoscopy showed erosive cesophagitis on day 5 (D5) and ulcerated bleeding inflammation of the entire colon and rectum on D26. She died on D30, during generalized convulsions. The second patient, a 31-year-old women, ingested sulphuric acid in the same way. She presented initially with diffuse abdominopelvic pains; clinical examination showed neither guarding nor contraction. Her temperature was 37,8 degrees C. Oesogastric endoscopy observed cesophagitis stage II B and III A and gastritis III A and III B. On D9, acute and generalized peritonitis was discovered, leading to surgical exploration. The patient died at the end of the operation. This unusual mode of suicide induces grave clinical presentations despite their apparent calm. The prognosis is worse because of the double localization of the lesions, the toxicity of the product, and the underestimation of its gravity. PMID:19810615

  10. Aqueous-phase source of formic acid in clouds

    NASA Technical Reports Server (NTRS)

    Chameides, W. L.; Davis, D. D.

    1983-01-01

    The coupled gas- and aqueous-phase cloud chemistry of HCOOH were examined for controlling factors in the acidity of cloud and rainwater. Attention was given to the aqueous OH/HO2 system that yields an OH species that is highly reactive with other species, notably SO2 and the formaldehyde/formic acid complex. A numerical model was developed to simulate the cloud chemistry in the remote troposphere, with considerations given to CH4-CO-NO(x)-O3-H(x)O(y) system. It was determined that aqueous phase OH radicals can produce and destroy formic acid droplets in daylight conditions, as well as control formic acid levels in rainwater. It is sugested that the same types of reactions may be involved in the control of acetic acid and other organic acids.

  11. Aqueous infrared carboxylate absorbances: Aliphatic di-acids

    USGS Publications Warehouse

    Cabaniss, S.E.; Leenheer, J.A.; McVey, I.F.

    1998-01-01

    Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to alkyl groups show increased intensity at higher pH. The asymmetric stretch of the HA- species is linearly related to the microscopic acidity constant of the H2A species, with ??pK 2 intervening atoms). The results suggest that aqueous ATR-FTIR may be able to estimate 'intrinsic' pKa values of carboxylic acids, in addition to providing quantitative estimates of ionization. ?? 1998 Elsevier Science B.V. All rights reserved.

  12. Laboratory studies of interaction between trace gases and sulphuric acid or sulphate aerosols using flow-tube reactors

    NASA Astrophysics Data System (ADS)

    Leu, Ming-Taun

    Stratospheric ozone provides a protective shield for humanity and the global biosphere from harmful ultraviolet solar radiation. In past decades, theoretical models for the calculation of ozone balance frequently used gas-phase reactions alone in their studies. Since the discovery of the Antarctic ozone hole in 1985, however, it has been demonstrated that knowledge of heterogeneous reactions is needed to understand this significant natural event owing to the anthropogenic emission of chlorofluorocarbons. In this review I will briefly discuss the experimental techniques for the research of heterogeneous chemistry carried out in our laboratory. These experimental instruments include flow-tube reactors, an electron-impact ionization mass spectrometer, a chemical ionization mass spectrometer and a scanning mobility particle spectrometer. Numerous measurements of uptake coefficient (or reaction probability) and solubility of trace gases in liquid sulphuric acid have been performed under the ambient conditions in the upper troposphere and lower stratosphere, mainly 190-250 K and 40-80 wt% of H

  13. Hydrofluoric-nitric-sulphuric-acid surface treatment of tungsten for carbon fibre-reinforced composite hybrids in space applications

    NASA Astrophysics Data System (ADS)

    Kanerva, M.; Johansson, L.-S.; Campbell, J. M.; Revitzer, H.; Sarlin, E.; Brander, T.; Saarela, O.

    2015-02-01

    Hybrid material systems, such as combinations of tungsten foils and carbon fibre-reinforced plastic (CFRP), are replacing metal alloy concepts in spacecraft enclosures. However, a good adhesion between the tungsten oxide scale and the epoxy resin used is required. Here, the effects of a hydrofluoric-nitric-sulphuric-acid (HFNS) treatment on tungsten oxides and subsequent adhesion to CFRP are analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fracture testing. The work shows that HFNS treatment results in decreased oxygen content, over 50% thinner tungsten trioxide (WO3) layer and increased nano-roughness on thin tungsten foils. Fracture testing established a 39% increase in the average critical strain for tungsten-CFRP specimens after HFNS treatment was carried out on tungsten. The effect of the oxide scale modification regarding the critical strain energy release rate was ΔGc≈ 8.4 J/m2.

  14. Decomposition Studies of Triphenylboron, Diphenylborinic Acid and Phenylboric Acid in Aqueous Alkaline Solutions Containing Copper

    SciTech Connect

    Crawford, C.L.; Peterson, R. A.

    1997-02-11

    This report documents the copper-catalyzed chemical kinetics of triphenylboron, diphenylborinic acid and phenylboric acid (3PB, 2PB and PBA) in aqueous alkaline solution contained in carbon-steel vessels between 40 and 70 degrees C.

  15. 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.

  16. Using isotope dilution mass spectrometry to determine aqueous trichloroacetic acid

    SciTech Connect

    Norwood, D.L.; Christman, R.F.; Johnson, J.D.; Hass, J.R.

    1986-01-01

    The development, verification, and application of a method based on isotope-dilution gas chromatography-mass spectrometry to determine aqueous trichloroacetic acid (TCAA) at the micrograms per litre level are described. The simultaneous determination of aqueous chloroform is also demonstrated. Trichloroacetic acid is shown to be a significant by-product of the chlorination of raw waters in the laboratory and to constitute a large fraction of the total organic halide (TOX) formed. Analysis of finished-water samples indicated that TCAA, like trihalomethanes is ubiquitous. Positive correlations exist between the levels of TCAA in laboratory-chlorinated raw waters and in finished waters and measured TOX.

  17. 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.

  18. 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.

  19. The amino acid sequence of protein SCMK-B2C from the high-sulphur fraction of wool keratin

    PubMed Central

    Elleman, T. C.

    1972-01-01

    1. The amino acid sequence of a protein from the reduced and carboxymethylated high-sulphur fraction of wool has been determined. 2. The sequence of this S-carboxymethylkerateine (SCMK-B2C) of 151 amino acid residues displays much internal homology and an unusual residue distribution. Thus a ten-residue sequence occurs four times near the N-terminus and five times near the C-terminus with few changes. These regions contain much of the molecule's half-cystine, whereas between them there is a region of 19 residues that are mainly small and devoid of cystine and proline. 3. Certain models of the wool fibre based on its mechanical and physical properties propose a matrix of small compact globular units linked together to form beaded chains. The unusual distribution of the component residues of protein SCMK-B2C suggests structures in the wool-fibre matrix compatible with certain features of the proposed models. PMID:4678578

  20. Complexes of Imidazole with Poly(ethylene glycol) as a Corrosion Inhibitor for Carbon Steel in Sulphuric Acid

    NASA Astrophysics Data System (ADS)

    Salimi, Saeed; Nasr-Esfahani, Mojtaba; Umoren, Saviour A.; Saebnoori, Ehsan

    2015-12-01

    The inhibiting action of polyethylene glycol and imidazole (PEG/IMZ)) complexes prepared by a simple deprotonation procedure on carbon steel corrosion in 0.5 mol/L sulphuric acid was evaluated using the weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques complemented by surface analysis using scanning electron microscopy. The inhibiting effect of the PEG/IMZ complexes on carbon steel corrosion was compared with the non-complex forms. Results obtained show that PEG/IMZ complex is a very effective corrosion inhibitor of carbon steel in the acid environment. The inhibition efficiency increased with the increase in the temperature and also with increasing percentage of imidazole in the complex. Corrosion inhibition occurs by virtue of adsorption of PEG/IMZ complexes on the steel surface which was found to follow the Temkin adsorption isotherm model. The PEG/IMZ complexes function as a mixed-type inhibitor. Results from all the methods employed are in a reasonably good agreement.

  1. Persistent Ion Pairing in Aqueous Hydrochloric Acid

    SciTech Connect

    Baer, Marcel D.; Fulton, John L.; Balasubramanian, Mahalingam; Schenter, Gregory K.; Mundy, Christopher J.

    2014-07-03

    For strong acids, like hydrochloric acid, the complete dissociation into an excess proton and conjugated base as well as the formation of independent solvated charged fragments is assumed. The existence of a chloride-Hyronium (Cl-H3O+) contact ion pairs even in moderate concentration hydrochloric acid (2.5 m) demonstrates that the counter ions do not behave merely as spectators. Through the use of modern extended X-ray absorption fine structure (EXAFS) measurements in conjunction with state-of-the-art density functional theory (DFT) simulations, we are able to obtain an unprecedented view into the molecular structure of medium to high concentrated electrolytes. Here we report that the Cl-H3O+ contact ion pair structure persists throughout the entire concentration range studied and that these structures differ significantly from moieties studied in micro-solvated hydrochloric acid clusters. Characterizing distinct populations of these ion pairs gives rise to a novel molecular level description of how to think about the activity of the proton that impacts our picture of the pH scale. Funding for CJM, GKS, and JLF was provided by DOE Office of Science, Office of Basic Energy Science, Division of Chemical Sciences, Geosciences, and Biosciences. Funding for MDB was provided throught the Laboratory Directed Research and Development program at Pacific Northwest National Laboratory. MB was funded through Argonne National Laboratory.

  2. Amino-acid contamination of aqueous hydrochloric acid.

    NASA Technical Reports Server (NTRS)

    Wolman, Y.; Miller, S. L.

    1971-01-01

    Considerable amino-acid contamination in commercially available analytical grade hydrochloric acid (37% HCl) was found. One bottle contained 8,300 nmol of amino-acids per liter. A bottle from another supplier contained 6,700 nmol per liter. The contaminants were mostly protein amino-acids and several unknowns. Data on the volatility of the amino-acids during HCl distillation were also obtained.

  3. Regional and global impacts of Criegee intermediates on atmospheric sulphuric acid concentrations and first steps of aerosol formation.

    PubMed

    Percival, Carl J; Welz, Oliver; Eskola, Arkke J; Savee, John D; Osborn, David L; Topping, David O; Lowe, Douglas; Utembe, Steven R; Bacak, Asan; McFiggans, Gordon; Cooke, Michael C; Xiao, Ping; Archibald, Alexander T; Jenkin, Michael E; Derwent, Richard G; Riipinen, Ilona; Mok, Daniel W K; Lee, Edmond P F; Dyke, John M; Taatjes, Craig A; Shallcross, Dudley E

    2013-01-01

    Carbonyl oxides ("Criegee intermediates"), formed in the ozonolysis of alkenes, are key species in tropospheric oxidation of organic molecules and their decomposition provides a non-photolytic source of OH in the atmosphere (Johnson and Marston, Chem. Soc. Rev., 2008, 37, 699, Harrison et al, Sci, Total Environ., 2006, 360, 5, Gäb et al., Nature, 1985, 316, 535, ref. 1-3). Recently it was shown that small Criegee intermediates, C.I.'s, react far more rapidly with SO2 than typically represented in tropospheric models, (Welz, Science, 2012, 335, 204, ref. 4) which suggested that carbonyl oxides could have a substantial influence on the atmospheric oxidation of SO2. Oxidation of 502 is the main atmospheric source of sulphuric acid (H2SO4), which is a critical contributor to aerosol formation, although questions remain about the fundamental nucleation mechanism (Sipilä et al., Science, 2010, 327, 1243, Metzger et al., Proc. Natl. Acad. Sci. U. S. A., 2010 107, 6646, Kirkby et al., Nature, 2011, 476, 429, ref. 5-7). Non-absorbing atmospheric aerosols, by scattering incoming solar radiation and acting as cloud condensation nuclei, have a cooling effect on climate (Intergovernmental Panel on Climate Change (IPCC), Climate Change 2007: The Physical Science Basis, Cambridge University Press, 2007, ref. 8). Here we explore the effect of the Criegees on atmospheric chemistry, and demonstrate that ozonolysis of alkenes via the reaction of Criegee intermediates potentially has a large impact on atmospheric sulphuric acid concentrations and consequently the first steps in aerosol production. Reactions of Criegee intermediates with SO2 will compete with and in places dominate over the reaction of OH with SO2 (the only other known gas-phase source of H2SO4) in many areas of the Earth's surface. In the case that the products of Criegee intermediate reactions predominantly result in H2SO4 formation, modelled particle nucleation rates can be substantially increased by the improved

  4. Conductance Studies on Aqueous Citric Acid

    NASA Astrophysics Data System (ADS)

    Apelblat, Alexander; Barthel, Josef

    1991-02-01

    Conductance measurements of citric acid and neutral citrates (tri-lithium citrate, tri-sodium citrate and tri-potassium citrate) were performed in water at 278.15 to 308.15 K. The equilibrium constants for the primary and secondary steps of dissociation, Kx and K2, and the limiting conductances, λ0(H2Cit-), λ°(1/2 HCit2-), and λ0(1/3 Cit3-) are reported as a function of temperature. They are obtained by application of the Quint and Viallard conductance equation. The enthalpies of dissociation are estimated.

  5. 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.

  6. Agronomic effectiveness of biofertilizers with phosphate rock, sulphur and Acidithiobacillus for yam bean grown on a Brazilian tableland acidic soil.

    PubMed

    Stamford, N P; Santos, P R; Santos, C E S; Freitas, A D S; Dias, S H L; Lira, M A

    2007-04-01

    Phosphate rocks have low available P and soluble P fertilizers have been preferably used in plant crop production, although economic and effective P sources are needed. Experiments were carried out on a Brazilian Typic Fragiudult soil with low available P to evaluate the agronomic effectiveness of phosphate rock (PR) compared with soluble phosphate fertilizer. Yam bean (Pachyrhizus erosus) inoculated with rhizobia (strains NFB 747 and NFB 748) or not inoculated was the test crop. Biofertilizers were produced in field furrows by mixing phosphate rock (PR) and sulphur inoculated with Acidithiobacillus (S+Ac) in different rates (50, 100, 150 and 200 g S kg(-1) PR), with 60 days of incubation. Treatments were carried out with PR; biofertilizers B(50), B(100), B(150), B(200); triple super phosphate (TSP); B(200) without Acidithiobacillus and a control treatment without P application (P(0)). TSP and biofertilizers plus S inoculated with Acidithiobacillus increased plant growth. Soil acidity and available P increased when biofertilizers B(150) and B(200) were applied. We conclude that biofertilizers may be used as P source; however, long term use will reduce soil pH and potentially reduce crop growth. PMID:16815009

  7. Empirical Modeling of Iron Oxide Dissolution in Sulphuric and Hydrochloric Acid

    NASA Astrophysics Data System (ADS)

    Hemmelmann, Jan C.; Xu, Hao; Krumm, Wolfgang

    2013-10-01

    A new approach is presented to an empirical modeling of chemical pickling processes, based on the activation energy of oxide dissolution in hydrochloric acid (HCl) and sulfuric acid (H2SO4). The model allows us to calculate pickling times as a function of definite parameters. The main oxide layers on hot-rolled materials are magnetite (Fe3O4), hematite (Fe2O3), and wustite (FeO). On the laboratory scale, the activation energy of each oxide has been determined. FeO is a metastable oxide and has been produced based on magnetite powder in a H2/H2O atmosphere. The oxide powders used for the experimental procedure have been analyzed by X-ray powder diffraction to insure the proper stoichiometry and composition. The model allows us to calculate the time of oxide dissolution based on the parameters temperature, acid concentration, and the composition of the oxide layer. Calculated values are verified by surface potential measurement on industrial oxide layers. The hot-rolled material used for verification is low carbon steel. A comparison between calculated pickling times and experimental data will be presented.

  8. Investigation of acyl migration in mono- and dicaffeoylquinic acids under aqueous basic, aqueous acidic, and dry roasting conditions.

    PubMed

    Deshpande, Sagar; Jaiswal, Rakesh; Matei, Marius Febi; Kuhnert, Nikolai

    2014-09-17

    Acyl migration in chlorogenic acids describes the process of migration of cinnamoyl moieties from one quinic acid alcohol group to another, thus interconverting chlorogenic acid regioisomers. It therefore constitutes a special case of transesterification reaction. Acyl migration constitutes an important reaction pathway in both coffee roasting and brewing, altering the structure of chlorogenic acid initially present in the green coffee bean. In this contribution we describe detailed and comprehensive mechanistic studies comparing inter- and intramolecular acyl migration involving the seven most common chlorogenic acids in coffee. We employe aqueous acidic and basic conditions mimicking the brewing of coffee along with dry roasting conditions. We show that under aqueous basic conditions intramolecular acyl migration is fully reversible with basic hydrolysis competing with acyl migration. 3-Caffeoylquinic acid was shown to be most labile to basic hydrolysis. We additionally show that the acyl migration process is strongly pH dependent with increased transesterification taking place at basic pH. Under dry roasting conditions acyl migration competes with dehydration to form lactones. We argue that acyl migration precedes lactonization, with 3-caffeoylquinic acid lactone being the predominant product. PMID:25116442

  9. Solubility of chlorine in aqueous hydrochloric acid solutions.

    PubMed

    Alkan, Mahir; Oktay, Münir; Kocakerim, M Muhtar; Copur, Mehmet

    2005-03-17

    The solubility of chlorine in aqueous hydrochloric acid solutions was studied. The effects of HCl concentration and temperature on the solubility were evaluated, and the thermodynamic parameters of the dissolution were calculated. It was found that the solubility isotherms had a minimum at about 0.5M HCl concentration at all the temperatures studied and that solubility decreased with the increase of temperature at all the HCl concentration range investigated. PMID:15752843

  10. Inhibition of iron corrosion in 0.5 M sulphuric acid by metal cations

    NASA Astrophysics Data System (ADS)

    Sathiyanarayanan, S.; Jeyaprabha, C.; Muralidharan, S.; Venkatachari, G.

    2006-09-01

    Corrosion inhibitors are widely used in acid solutions during pickling and descaling. Mostly organic compounds containing N, O, and S groups are employed as inhibitors. In this study, the inhibition performance of metal cations such as Zn 2+, Mn 2+ and Ce 4+ ions in the concentration range 1-10 × 10 -3 M has been found out. The corrosion behaviour of iron in 0.5 M H 2SO 4 in the presence of metal cations is studied using polarization and impedance methods. It is found that the addition of these metal cations inhibits the corrosion markedly. The inhibition effect is in the following order Ce 4+ ≫ Mn 2+ > Zn 2+.

  11. Spectrophotometric determination of the oxygen to uranium ratio in uranium oxides based on dissolution in sulphuric acid.

    PubMed

    Murty, B N; Yadav, R B; Ramamurthy, C K; Syamundar, S

    1991-11-01

    The oxygen to uranium ratio in uranium oxides such as U(3)O(8), UO(2+x) powders and UO(2) fuel pellets has been determined by a new spectrophotometric method. The method can be used for determination of O/U ratio in UO(2) pellets and powders on a routine basis. In the described method, uranium oxides in the powder form are dissolved in 2M sulphuric acid containing a few drops of HF. The concentrations of U(IV) and U(VI) are directly determined by means of the absorbances of these species at different wavelengths. For determination of the O/U ratio in U(3)O(8) powder samples, 630 and 310 nm are the wavelengths chosen for U(IV) and U(VI), respectively. For UO(2+x) powder, where the O/U ratio lies between 2.04 to 2.15, U(IV) and U(VI) are determined at 630 and 300 nm respectively, whereas for UO(2) fuel pellets, where the O/U ratio is less than 2.01, 535 and 285 nm are used. The molar absorptivity of U(IV) at 630 and 535 nm is 21.4 and 6.8 l.mole(-1).cm(-1) and that of U(VI) at 310, 300 and 285 nm is 178.1, 278.6 and 585 l.mole(-1).cm(-1), respectively. Standard deviations of +/-0.002 O/U ratio units for pellets and +/-0.004 O/U ratio units for powders have been achieved. PMID:18965306

  12. 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.

  13. 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.

  14. 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.

  15. Signatures of Autotrophic and Heterotrophic Metabolic Activity in Enrichment Cultures from a Sulphur Oxidizing Acid Mine Site

    NASA Astrophysics Data System (ADS)

    Slater, G. F.; Bernier, L.; Cowie, B. R.; Warren, L. A.

    2006-12-01

    Delineating the role of microorganisms in geochemical processes of interest in natural environments requires the development of tools that provide the ability to distinguish amongst microbial activity associated with different metabolic guilds. The gap between phylogenetic characterization and phenotypic understanding remains, underscoring the need to consider alternative methods. Compound specific analysis of cellular components has the potential to differentiate between active metabolic processes supporting microbial communities and may be especially useful in extreme environments. The goal of this study was to determine whether the phospholipids fatty acid (PLFA) distribution and isotopic signatures associated with autotrophs and heterotrophs enriched from an acid mine drainage (AMD) system differed, and further whether natural consortial autotrophic isolates showed similar signatures to autotrophic pure strains of Acidithiobacillus ferrooxidans and A. thiooxidans. Two distinct initial enrichments with tetrathionate and CO2 yielded primarily autotrophic (95%) Acidithiobaccillus spp. sulphur oxidizing communities. The remaining microbial members of theses enrichments (<5%) were morphologically distinct and heterotrophic, as subculture of the consortial isolates in a medium amended with glucose but without tetrathionate selectively resulted in their visible growth. PLFA profiles and δ13C signatures from autotrophic (1) natural enrichments, pure cultures of (2) A. ferrooxidans and (3) A. thiooxidans were similar, but collectively differed from those of the natural heterotrophic enrichment cultures. The PLFA profiles for the heterotrophic communities were made up of primarily (88-99%) C16:0 and two isomers of C18:1. In contrast, the autotrophic communities had high proportions of C16:1 (up to 18%) as well as cyclo C17 and cyclo C19 PLFA that combined comprised 18 to 58% of the observed PLFA. The δ13C signatures of the PLFA also differed strongly between the two

  16. 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.

  17. Fermentation of aqueous plant seed extracts by lactic acid bacteria

    SciTech Connect

    Schafner, D.W.; Beuchat, R.L.

    1986-05-01

    The effects of lactic acid bacterial fermentation on chemical and physical changes in aqueous extracts of cowpea (Vigna unguiculata), peanut (Arachis hypogea), soybean (Glycine max), and sorghum (Sorghum vulgare) were studied. The bacteria investigated were Lactobacillus helveticus, L. delbrueckii, L. casei, L. bulgaricus, L. acidophilus, and Streptococcus thermophilus. Organisms were inoculated individually into all of the seed extracts; L. bulgaricus and S. thermophilus were also evaluated together as inocula for fermenting the legume extracts. During fermentation, bacterial population and changes in titratable acidity, pH, viscosity, and color were measured over a 72 h period at 37 degrees C. Maximum bacterial populations, titratable acidity, pH, and viscosity varied depending upon the type of extract and bacterial strain. The maximum population of each organism was influenced by fermentable carbohydrates, which, in turn, influenced acid production and change in pH. Change in viscosity was correlated with the amount of protein and titratable acidity of products. Color was affected by pasteurization treatment and fermentation as well as the source of extract. In the extracts inoculated simultaneously with L. bulgaricus and S. thermophilus, a synergistic effect resulted in increased bacterial populations, titratable acidity, and viscosity, and decreased pH in all the legume extracts when compared to the extracts fermented with either of these organisms individually. Fermented extracts offer potential as substitutes for cultured dairy products. 24 references.

  18. Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water

    SciTech Connect

    Stinson, Jake L.; Kathmann, Shawn M.; Ford, Ian J.

    2014-01-14

    The nucleation of particles from trace gases in the atmosphere is an important source of cloud condensation nuclei (CCN), and these are vital for the formation of clouds in view of the high supersaturations required for homogeneous water droplet nucleation. The methods of quantum chemistry have increasingly been employed to model nucleation due to their high accuracy and efficiency in calculating configurational energies; and nucleation rates can be obtained from the associated free energies of particle formation. However, even in such advanced approaches, it is typically assumed that the nuclei have a classical nature, which is questionable for some systems. The importance of zero-point motion (also known as quantum nuclear dynamics) in modelling small clusters of sulphuric acid and water is tested here using the path integral molecular dynamics (PIMD) method at the density functional theory (DFT) level of theory. We observe a small zero-point effect on the the equilibrium structures of certain clusters. One configuration is found to display a bimodal behaviour at 300 K in contrast to the stable ionised state suggested from a zero temperature classical geometry optimisation. The general effect of zero-point motion is to promote the extent of proton transfer with respect to classical behaviour. We thank Prof. Angelos Michaelides and his group in University College London (UCL) for practical advice and helpful discussions. This work benefited from interactions with the Thomas Young Centre through seminar and discussions involving the PIMD method. SMK was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. JLS and IJF were supported by the IMPACT scheme at UCL and by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. We are grateful for use of the UCL Legion High Performance Computing Facility and the

  19. 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.

  20. Accumulation of PrLeg, a Perilla legumin protein in potato tuber results in enhanced level of sulphur-containing amino acids.

    PubMed

    Goo, Young-Min; Kim, Tae-Won; Lee, Min-Kyung; Lee, Shin-Woo

    2013-09-01

    Potato is the fourth staple food in the world, following rice, wheat, and maize, whereas tubers contain high quality of starch, relatively high amounts of vitamin C and many other important substances. It also contains relatively good quality of protein (about 3 to 6% of the dried weight) and patatin, and 11S globulin is a major storage protein with high level of lysine. However, tuber protein contains relatively low amounts of sulphur-containing amino acids, which may result in low nutritional value. Recently, we cloned a gene encoding PrLeg polypeptide, a seed storage protein from Perilla, which contains relatively higher levels of sulphur-containing amino acids. We transformed PrLeg cDNA into a potato plant to over-express under the direction of the tuber-specific promoter, patatin. Most of the transgenic lines identified through PCR and RT-PCR analyses were able to accumulate high amount of prLeg transcript in their tuber tissue, while very little or no transcript that were detected in their leaf tissues. The level of methionine content was elevated up to three-fold compared to non-transgenic parental line, without any significant changes in other amino acids, suggesting that further research is required to get a deeper insight into their nutritional value. PMID:24161240

  1. Effects of different sulphur amino acids and dietary electrolyte balance levels on performance, jejunal morphology, and immunocompetence of broiler chicks.

    PubMed

    Nikoofard, V; Mahdavi, A H; Samie, A H; Jahanian, E

    2016-02-01

    As alterations of dietary electrolyte balance (DEB) can influence amino acid metabolism via changes the ions incur in their configurations, performance and immunological responses of broiler chicks might be affected. So, the current study was carried out to investigate the effects of different levels of sulphur amino acids (SAA) and DEB on performance, jejunal morphology and immunocompetence of broiler chicks. A total of 360 1-day-old male Ross 308 broiler chicks were randomly assigned to nine experimental treatments with four replicates of 10 birds each. Experimental treatments consisted of three levels of SAA (100, 110, and 120% of NRC recommendation, provided by methionine supplementation in diets with the same cysteine level) and three levels of DEB (150, 250, and 350 mEq/kg) that were fed during the entire of trial in a 3 × 3 factorial arrangement. Results showed that the relative weights of intestine and abdominal fat were decreased markedly (p < 0.001) with increasing levels of SAA and DEB respectively. Antibody titre against sheep red blood cell was neither individually nor in combination influenced by supplementation of SAA or DEB. Nevertheless, a decrease in DEB level led to a suppression in heterophile (p < 0.05) and an increase in lymphocyte counts (p = 0.06); consequently, heterophile to lymphocyte ratio was significantly decreased (p < 0.05) by decremental levels of DEB. Albumin to globulin ratio was increased after inclusion of at least 10% SAA (p < 0.001) and 150 mEq DEB/kg in the diet (p = 0.11). Although feeding high-DEB level led to a remarkable decrease in villus height (p < 0.01) and goblet cell numbers (p < 0.001), supplementing the highest level of SAA improved the height of jejunal villus. During the entire trial period, average daily feed intake (ADFI) was increased by incremental SAA levels (p < 0.05). However, inclusion of 150 mEq/kg led to not only a remarkable increase (p < 0.0001) in both ADFI and average daily

  2. 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. PMID:26574908

  3. Surface oxide growth on platinum electrode in aqueous trifluoromethanesulfonic acid.

    PubMed

    Furuya, Yoshihisa; Mashio, Tetsuya; Ohma, Atsushi; Dale, Nilesh; Oshihara, Kenzo; Jerkiewicz, Gregory

    2014-10-28

    Platinum in the form of nanoparticles is the key and most expensive component of polymer electrolyte membrane fuel cells, while trifluoromethanesulfonic acid (CF3SO3H) is the smallest fluorinated sulfonic acid. Nafion, which acts as both electrolyte and separator in fuel cells, contains -CF2SO3H groups. Consequently, research on the electrochemical behaviour of Pt in aqueous CF3SO3H solutions creates important background knowledge that can benefit fuel cell development. In this contribution, Pt electro-oxidation is studied in 0.1 M aqueous CF3SO3H as a function of the polarization potential (E(p), 1.10 ≤ E(p) ≤ 1.50 V), polarization time (t(p), 10(0) ≤ t(p) ≤ 10(4) s), and temperature (T, 278 ≤ T ≤ 333 K). The critical thicknesses (X1), which determines the applicability of oxide growth theories, is determined and related to the oxide thickness (d(ox)). Because X1 > d(ox) for the entire range of E(p), t(p), and T values, the formation of Pt surface oxide follows the interfacial place-exchange or the metal cation escape mechanism. The mechanism of Pt electro-oxidation is revised and expanded by taking into account possible interactions of cations, anions, and water molecules with Pt. A modified kinetic equation for the interfacial place exchange is proposed. The application of the interfacial place-exchange and metal cation escape mechanisms leads to an estimation of the Pt(δ+)-O(δ-) surface dipole (μ(PtO)), and the potential drop (V(ox)) and electric field (E(ox)) within the oxide. The Pt-anion interactions affect the oxidation kinetics by indirectly influencing the electric field within the double layer and the surface oxide. PMID:25362330

  4. Surface oxide growth on platinum electrode in aqueous trifluoromethanesulfonic acid

    NASA Astrophysics Data System (ADS)

    Furuya, Yoshihisa; Mashio, Tetsuya; Ohma, Atsushi; Dale, Nilesh; Oshihara, Kenzo; Jerkiewicz, Gregory

    2014-10-01

    Platinum in the form of nanoparticles is the key and most expensive component of polymer electrolyte membrane fuel cells, while trifluoromethanesulfonic acid (CF3SO3H) is the smallest fluorinated sulfonic acid. Nafion, which acts as both electrolyte and separator in fuel cells, contains -CF2SO3H groups. Consequently, research on the electrochemical behaviour of Pt in aqueous CF3SO3H solutions creates important background knowledge that can benefit fuel cell development. In this contribution, Pt electro-oxidation is studied in 0.1 M aqueous CF3SO3H as a function of the polarization potential (Ep, 1.10 ≤ Ep ≤ 1.50 V), polarization time (tp, 100 ≤ tp ≤ 104 s), and temperature (T, 278 ≤ T ≤ 333 K). The critical thicknesses (X1), which determines the applicability of oxide growth theories, is determined and related to the oxide thickness (dox). Because X1 > dox for the entire range of Ep, tp, and T values, the formation of Pt surface oxide follows the interfacial place-exchange or the metal cation escape mechanism. The mechanism of Pt electro-oxidation is revised and expanded by taking into account possible interactions of cations, anions, and water molecules with Pt. A modified kinetic equation for the interfacial place exchange is proposed. The application of the interfacial place-exchange and metal cation escape mechanisms leads to an estimation of the Ptδ+-Oδ- surface dipole (μPtO), and the potential drop (Vox) and electric field (Eox) within the oxide. The Pt-anion interactions affect the oxidation kinetics by indirectly influencing the electric field within the double layer and the surface oxide.

  5. 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...

  6. Sulphur condensation influence in Claus catalyst performance.

    PubMed

    Mora, R L

    2000-12-01

    The Claus process is an efficient way of removing H(2)S from acid gas streams and this is widely practised in industries such as natural gas processing, oil refining and metal smelting. Increasingly strict pollution control regulations require maximum sulphur recovery from the Claus unit in order to minimise sulphur-containing effluent. The most widely used Claus catalyst in sulphur recovery units is non-promoted spherical activated alumina. Properties associated with optimum non-promoted Claus catalyst performance include high surface area, appropriate pore size distribution and enhanced physical properties. The objective of this paper is to outline a procedure in order to estimate Claus catalyst effectiveness after pore plugging due to sulphur condensation. Catalyst deactivation due to pore plugging by sulphur is modelled employing a Bethe lattice and its corresponding performance is described by means of a modified effectiveness factor. Model results show an improvement in the modified effectiveness factor due to modifications in catalyst porous structure. PMID:11040389

  7. The action of mono- and di-functional sulphur mustards on the ribonucleic acid-containing bacteriophage μ2

    PubMed Central

    Shooter, K. V.; Edwards, P. A.; Lawley, P. D.

    1971-01-01

    Bacteriophage μ2 is inactivated by both mono- and di-functional sulphur mustards at relatively low extents of alkylation. No degradation of alkylated RNA was detected. Cross-linking of RNA to protein was observed with the difunctional agent, but this reaction was only a minor contribution to the inactivation. Analyses of the reaction products in bacteriophage RNA showed that, at the mean lethal doses, more than one mono-alkylation of guanine had occurred but the sum total of other types of RNA alkylation was close to a single event. The results therefore suggest that inactivation results from the mono-alkylation of adenine or cytosine. In experiments with the difunctional agent cross-linking of RNA bases or of RNA to protein also prevented replication, the existence of these reactions accounting for the greater sensitivity of the bacteriophage to this agent. PMID:5145907

  8. Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium.

    PubMed

    Donaldson, E M

    1970-07-01

    A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid medium containing excess of ammonium persulphate as oxidant. The molar absorptivity of the complex is 428 l.mole(-1).mm(-5) at 475 nm, the wavelength of maximum absorption. Interference from chromium(VI) and cerium(IV) is eliminated by reduction with iron(II). Common ions, including large amounts of titanium, zirconium, molybdenum and tungsten, do not interfere. PMID:18960775

  9. Optical properties of chitosan in aqueous solution of L- and D-ascorbic acids

    NASA Astrophysics Data System (ADS)

    Malinkina, Olga N.; Shipovskaya, Anna B.; Kazmicheva, Olga F.

    2016-04-01

    The optical properties of aqueous chitosan solutions in L- and D-ascorbic acids were studied by optical rotatory dispersion and spectrophotometry. The specific optical rotation [α] of all chitosan solutions tested was positive, in contrast to aqueous solutions of the ascorbic acid enantiomers, which exhibit an inverse relationship of [α] values. Significant differences in the absolute values of [α] of the chitosan solutions at polymer-acid ratios exceeding the equimolar one were found.

  10. Acid-base properties of aqueous illite surfaces

    SciTech Connect

    Du, Q.; Sun, Z.; Forsling, W.; Tang, H.

    1997-03-01

    In this paper, the acid-base properties of illite/water suspensions are examined using the constant capacitance surface complexation model. On the basis of results of potentiometric titrations and solubility experiments, the authors conclude that the proton reactions in the supernatants of illite suspensions can be successfully represented by proton reactions of Al(H{sub 2}O){sub 6}{sup 3+} and Si(OH){sub 4} in water solutions. For illustrating the acidic characteristics of aqueous illite surfaces, two surface protonation models are proposed: (1) one site-one pK{sub a} model, {triple_bond}SOH {r_reversible} {triple_bond}SO{sup {minus}} + H{sup +}, pK{sub a}{sup int} = 4.12-4.23; (2) two sites-two pK{sub a}s model, {triple_bond}S{sub 1}OH {r_reversible} {triple_bond}S{sup 1}O{sup {minus}} + H{sup +}, pK{sub a{sub I}} = 4.17-4.44, and {triple_bond}S{sub II}OH {r_reversible} {triple_bond}S{sub II}O{sup {minus}} + H{sup +}, pK{sub a{sub II}}{sup int} = 6.35-7.74. Evaluation of these two models indicates that both of them can give good descriptions of the experimental data of systems with different illite concentrations and ionic strengths and that the one site-one pK{sub a} model can be considered as a simplification of the two sites-two pK{sub a}s model. Since both models assume only deprotonation reactions at the illite surfaces, they suggest that the surface behavior of the illite is similar to that of amorphous SiO{sub 2}. Model assumptions, experimental procedures, and evaluative criteria are detailed in the paper.

  11. Activation of Carbonyl-Containing Molecules with Solid Lewis Acids in Aqueous Media

    SciTech Connect

    Román-Leshkov, Yuriy; Davis, Mark E.

    2011-09-28

    Current interest in reacting carbonyl-containing molecules in aqueous media is primarily due to the growing emphasis on conversion of biomass to fuels and chemicals. Recently, solid Lewis acids have been shown to perform catalytic reactions with carbonyl-containing molecules such as sugars in aqueous media. Here, catalysis mediated by Lewis acids is briefly discussed, Lewis acid solids that perform catalysis in aqueous media are then described, and the review is concluded with a few comments on the outlook for the future.

  12. New crystallization of fatty acids from aqueous ethanol solution combined with liquid-liquid extraction

    SciTech Connect

    Maeda, Kouji; Nomura, Yoshihisa; Tai, Kimihiko; Ueno, Yoshitaka; Fukui, Keisuke; Hirota, Syouji

    1999-06-01

    A new separation process of saturated fatty acids (lauric acid-myristic acid) using crystallization from an aqueous ethanol solution has been examined. There were two vessels in this separation process: an extraction vessel and a crystallization vessel. The fatty acids in the aqueous phase were first extracted from their organic phase (melt) in the extraction vessel. The fatty acids in the aqueous phase were continuously introduced to the crystallization vessel, and then the fatty acids were crystallized there. The crystals of the fatty acids were collected continuously above the aqueous phase in the crystallization vessel. In this process, the yield and the purity of the crystals over time were measured, and it was found that the purity of lauric acid increased unsteadily up to 0.98 mole fraction of lauric acid with an increase in the yield of the low yield range. The mole fraction of ethanol in the aqueous phase could be significant to control the relationship between the yield and the purity of the crystals. Three different mole fractions of lauric acid in the organic phase were used to be separated in this process. Moreover, the authors have considered the effective separations of this process, and the maximum yield and purity of the crystals have been estimated by a simple mass balance.

  13. Multiple Glass Transitions and Freezing Events of Aqueous Citric Acid

    PubMed Central

    2014-01-01

    Calorimetric and optical cryo-microscope measurements of 10–64 wt % citric acid (CA) solutions subjected to moderate (3 K/min) and slow (0.5 and 0.1 K/min) cooling/warming rates and also to quenching/moderate warming between 320 and 133 K are presented. Depending on solution concentration and cooling rate, the obtained thermograms show one freezing event and from one to three liquid–glass transitions upon cooling and from one to six liquid–glass and reverse glass–liquid transitions, one or two freezing events, and one melting event upon warming of frozen/glassy CA/H2O. The multiple freezing events and glass transitions pertain to the mother CA/H2O solution itself and two freeze-concentrated solution regions, FCS1 and FCS2, of different concentrations. The FCS1 and FCS2 (or FCS22) are formed during the freezing of CA/H2O upon cooling and/or during the freezing upon warming of partly glassy or entirely glassy mother CA/H2O. The formation of two FCS1 and FCS22 regions during the freezing upon warming to our best knowledge has never been reported before. Using an optical cryo-microscope, we are able to observe the formation of a continuous ice framework (IF) and its morphology and reciprocal distribution of IF/(FCS1 + FCS2). Our results provide a new look at the freezing and glass transition behavior of aqueous solutions and can be used for the optimization of lyophilization and freezing of foods and biopharmaceutical formulations, among many other applications where freezing plays a crucial role. PMID:25482069

  14. 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.

  15. Structural and vibrational studies of the molecular crystals formed by 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridino) phenolate with nitric and sulphuric acids

    NASA Astrophysics Data System (ADS)

    Baran, J.; Barnes, A. J.; Drozd, M.; Janczak, J.; Ratajczak, H.; limitSˈled limitzˈ, M.

    2001-12-01

    The crystal structure of 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridino) phenol-nitrate-water has been found to belong to the P2 1/ n space group of the monoclinic system, with Z=4, a=12.498(2) Å, b=19.223(4) Å, c=14.025(3) Å, and β=90.25(3)°. The 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridino) phenol-hydrogen sulphate crystal has a similar structure, with Z=4, a=13.139(3) Å, b=18.926(4) Å, c=13.406(3) Å, and β=92.68(3)°. In the nitric acid complex, two water molecules and two nitrate ions are linked by a network of hydrogen bonds, with each water molecule also accepting a hydrogen bond from the phenolic OH group and each nitrate ion additionally involved in a short C-H…O contact. Similarly in the sulphuric acid complex, two hydrogen sulphate ions form a hydrogen-bonded cyclic dimer, with each hydrogen sulphate ion also accepting a hydrogen bond from the phenolic OH group and additionally involved in a short C-H…O contact. The observed infrared and Raman spectra are in accordance with these structures.

  16. 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.

  17. 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.

  18. The IUPAC aqueous and non-aqueous experimental pKa data repositories of organic acids and bases.

    PubMed

    Slater, Anthony Michael

    2014-10-01

    Accurate and well-curated experimental pKa data of organic acids and bases in both aqueous and non-aqueous media are invaluable in many areas of chemical research, including pharmaceutical, agrochemical, specialty chemical and property prediction research. In pharmaceutical research, pKa data are relevant in ligand design, protein binding, absorption, distribution, metabolism, elimination as well as solubility and dissolution rate. The pKa data compilations of the International Union of Pure and Applied Chemistry, originally in book form, have been carefully converted into computer-readable form, with value being added in the process, in the form of ionisation assignments and tautomer enumeration. These compilations offer a broad range of chemistry in both aqueous and non-aqueous media and the experimental conditions and original reference for all pKa determinations are supplied. The statistics for these compilations are presented and the utility of the computer-readable form of these compilations is examined in comparison to other pKa compilations. Finally, information is provided about how to access these databases. PMID:24952470

  19. Siro(haem)amide in Allochromatium vinosum and relevance of DsrL and DsrN, a homolog of cobyrinic acid a,c-diamide synthase, for sulphur oxidation.

    PubMed

    Lübbe, Yvonne J; Youn, Hyung-Sun; Timkovich, Russell; Dahl, Christiane

    2006-08-01

    In the purple sulphur bacterium Allochromatium vinosum, the prosthetic group of dissimilatory sulphite reductase (DsrAB) was identified as siroamide, an amidated form of the classical sirohaem. The genes dsrAB are the first two of a large cluster of genes necessary for the oxidation of sulphur globules stored intracellularly during growth on sulphide and thiosulphate. DsrN is homologous to cobyrinic acid a,c diamide synthase and may therefore catalyze glutamine-dependent amidation of sirohaem. Indeed, an A. vinosumDeltadsrN in frame deletion mutant showed a significantly reduced sulphur oxidation rate that was fully restored upon complementation with dsrN in trans. Sulphite reductase was still present in the DeltadsrN mutant. DsrL is a homolog of the small subunits of bacterial glutamate synthases and was proposed to deliver glutamine for sirohaem amidation. However, recombinant DsrL does not exhibit glutamate synthase activity nor does the gene complement a glutamate synthase-deficient Escherichia coli strain. Deletion of dsrL showed that the encoded protein is absolutely essential for sulphur oxidation in A. vinosum. PMID:16907720

  20. Distribution of sulphuric acid aerosols in the clouds and upper haze of Venus using Venus Express VAST and VeRa temperature profiles

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher D.; Gao, Peter; Schulte, Rick; Bougher, Stephen W.; Yung, Yuk L.; Bardeen, Charles G.; Wilquet, Valérie; Vandaele, Ann Carine; Mahieux, Arnaud; Tellmann, Silvia; Pätzold, Martin

    2015-08-01

    Observations from Pioneer Venus and from SPICAV/SOIR aboard Venus Express (VEx) have shown the upper haze (UH) of Venus to be highly spatially and temporally variable, and populated by multiple particle size modes. Previous models of this system (e.g., Gao et al., 2014. Icarus 231, 83-98), using a typical temperature profile representative of the atmosphere (viz., equatorial VIRA profile), did not investigate the effect of temperature on the UH particle distributions. We show that the inclusion of latitude-dependent temperature profiles for both the morning and evening terminators of Venus helps to explain how the atmospheric aerosol distributions vary spatially. In this work we use temperature profiles obtained by two instruments onboard VEx, VeRa and SPICAV/SOIR, to represent the latitudinal temperature dependence. We find that there are no significant differences between results for the morning and evening terminators at any latitude and that the cloud base moves downwards as the latitude increases due to decreasing temperatures. The UH is not affected much by varying the temperature profiles; however, the haze does show some periodic differences, and is slightly thicker at the poles than at the equator. We also find that the sulphuric acid "rain" seen in previous models may be restricted to the equatorial regions of Venus, such that the particle size distribution is relatively stable at higher latitudes and at the poles.

  1. Method of inhibiting crosslinking of aqueous xanthan gums in the presence of ferric acid ions

    SciTech Connect

    Crowe, C.W.

    1982-03-02

    The cross linking of aqueous xanthan gums in the presence of ferric ions is inhibited or prevented by adding a soluble alkanoic and/or alkenoic acid having at least 4 carbon atoms and bearing at least 2 hydroxyl groups per molecule, and/or a soluble salt of ..gamma..-lactone. This combination of ingredients forms gelled acid compositions which are useful in acidizing treatments of wells. The gelled acid compositions are viscous fluids which have increased stability against shear and thermal degradation and other properties which result in retarded reaction rates and reduced fluid leak-off during acidizing treatments of subterranean formations surrounding well bores. The aqueous gelled acids have the further advantage of inhibiting or preventing the formation of insoluble compounds, such as ferric hydroxide, during such acidizing treatments. 13 claims.

  2. Rosmarinic acid content in antidiabetic aqueous extract of Ocimum canum Sims grown in Ghana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rosmarinic acid (RA) is an important polyphenol that is found in a variety of herbs including Ocimum canum sims (locally called eme or akokobesa in Ghana). Aqueous extracts from the leaves of O.canum are used as an antidiabetic herbal medicine in Ghana. Interestingly, rosmarinic acid content and p...

  3. KINETIC ASPECTS OF CATION-ENHANCED AGGREGATION IN AQUEOUS HUMIC ACIDS. (R822832)

    EPA Science Inventory

    The cation-enhanced formation of hydrophobic domains in aqueous humic acids has been shown to be a slow process, consistent with the evolution and disintegration of humic acid configurations over periods lasting from days to weeks. After the addition of a magnesium salt to a humi...

  4. ADIPIC ACID DEGRADATION MECHANISM IN AQUEOUS FGD (FLUE GAS DESULFURIZATION) SYSTEMS

    EPA Science Inventory

    The report gives results of a field and laboratory study of the adipic acid degradation mechanism in aqueous flue gas desulfurization (FGD) systems. (Adding adipic acid to limestone-based, SO2 wet scrubbers increases SO2 removal and limestone utilization. However, as much as 80% ...

  5. Coulometric titration of acids in non-aqueous solvents.

    PubMed

    Fritz, J S; Gainer, F E

    1968-09-01

    Coulometric titrations of mineral acids, sulphonic acids, carboxylic acids, enols, imides and phenols have been carried out in t-butanol or in acetone with electrically generated tetrabutylammonium hydroxide. Either a potentiometric titration or a visual indicator end-point may be used. The amount of acid titrated ranges from 10 to 60 muequiv, and the precision and accuracy of the method are excellent. PMID:18960387

  6. Improvement in Aqueous Solubility of Retinoic Acid Receptor (RAR) Agonists by Bending the Molecular Structure.

    PubMed

    Hiramatsu, Michiaki; Ichikawa, Yuki; Tomoshige, Shusuke; Makishima, Makoto; Muranaka, Atsuya; Uchiyama, Masanobu; Yamaguchi, Takao; Hashimoto, Yuichi; Ishikawa, Minoru

    2016-08-01

    Aqueous solubility is a key requirement for many functional molecules, e. g., drug candidates. Decrease of the partition coefficient (log P) by chemical modification, i.e., introduction of hydrophilic group(s) into molecules, is a classical strategy for improving aqueous solubility. We have been investigating alternative strategies for improving the aqueous solubility of pharmaceutical compounds by disrupting intermolecular interactions. Here, we show that introducing a bend into the molecular structure of retinoic acid receptor (RAR) agonists by changing the substitution pattern from para to meta or ortho dramatically enhances aqueous solubility by up to 890-fold. We found that meta analogs exhibit similar hydrophobicity to the parent para compound, and have lower melting points, supporting the idea that the increase of aqueous solubility was due to decreased intermolecular interactions in the solid state as a result of the structural changes. PMID:27378357

  7. Effects of organic acids, amino acids and ethanol on the radio-degradation of patulin in an aqueous model system

    NASA Astrophysics Data System (ADS)

    Yun, Hyejeong; Lim, Sangyong; Jo, Cheorun; Chung, Jinwoo; Kim, Soohyun; Kwon, Joong-Ho; Kim, Dongho

    2008-06-01

    The effects of organic acids, amino acids, and ethanol on the radio-degradation of patulin by gamma irradiation in an aqueous model system were investigated. The patulin, dissolved in distilled water at a concentration of 50 ppm, was practically degraded by the gamma irradiation at the dose of 1.0 kGy, while 33% of the patulin remained in apple juice. In the aqueous model system, the radio-degradation of patulin was partially inhibited by the addition of organic acids, amino acids, and ethanol. The proportions of remaining patulin after irradiation with the dose of 1.0 kGy in the 1% solution of malic acid, citric acid, lactic acid, acetic acid, ascorbic acid, and ethanol were 31.4%, 2.3%, 31.2%, 6.1%, 50.8%, and 12.5%, respectively. During 30 days of storage, the remaining patulin was reduced gradually in the solution of ascorbic acid and malic acid compared to being stable in other samples. The amino acids, serine, threonine, and histidine, inhibited the radio-degradation of patulin. In conclusion, it was suggested that 1 kGy of gamma irradiation (recommended radiation doses for radicidation and/or quarantine in fruits) is effective for the reduction of patulin, but the nutritional elements should be considered because the radio-degradation effects are environment dependent.

  8. Silver-Catalyzed Decarboxylative Allylation of Aliphatic Carboxylic Acids in Aqueous Solution.

    PubMed

    Cui, Lei; Chen, He; Liu, Chao; Li, Chaozhong

    2016-05-01

    Direct decarboxylative radical allylation of aliphatic carboxylic acids is described. With K2S2O8 as the oxidant and AgNO3 as the catalyst, the reactions of aliphatic carboxylic acids with allyl sulfones in aqueous CH3CN solution gave the corresponding alkenes in satisfactory yields under mild conditions. This site-specific allylation method is applicable to all primary, secondary, and tertiary alkyl acids and exhibits wide functional group compatibility. PMID:27065060

  9. 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%.

  10. 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

  11. Diglycolamic acid modified silica gel for the separation of hazardous trivalent metal ions from aqueous solution.

    PubMed

    Suneesh, A S; Syamala, K V; Venkatesan, K A; Antony, M P; Vasudeva Rao, P R

    2015-01-15

    The surface of the silica gel was modified with diglycolamic acid moieties and the product (Si-DGAH) was characterized by elemental analysis, TG-DTA, (1)H and (29)Si NMR and scanning electron microscopy (SEM). The adsorption behavior of hazardous americium (III) and europium (III) in Si-DGAH was studied from aqueous nitric acid medium to examine the feasibility using the modified silica for the separation of Am(III) and Eu(III) from aqueous wastes. In this context, the effect of various parameters such as the duration of equilibration, and concentrations of europium, nitric acid, sodium nitrate and diethylenetriaminepentaacetic acid (DTPA) in aqueous phase, on the distribution coefficient (K(d)) of Am(III) and Eu(III) was investigated. The distribution coefficient of ∼10(3) mL/g (>99.9% extraction) was obtained for both Am(III) and Eu(III) at pH 3, and the K(d) values decreased with increase in the concentration of nitric acid. Rapid kinetics of extraction in the initial stages of equilibration, followed by the establishment of equilibrium occurred within 30 min. The extraction data were fitted into Langmuir adsorption model and the apparent europium extraction capacity was determined. Europium loading capacity of the sorbent was determined at various feed pH by column method. The study indicated the possibility of using diglycolamic acid-modified silica for the separation of Eu(III) and Am(III) from aqueous wastes. PMID:25454425

  12. Photocatalytic Oxidation of Sulfurous Acid in an Aqueous Medium

    ERIC Educational Resources Information Center

    Romero, Alicia; Hernandez, Willie; Suarez, Marco F.

    2005-01-01

    The effect of some parameters on sulfurous acid and sulfur oxidation kinetics such as initial concentration of sulfurous acid, oxygen, TiO[2] crystalline concentration, the power of black light, and quantity of TiO[2] is investigated. The experiments can be performed in an undergraduate physical chemistry laboratory with an inexpensive…

  13. Composition and process for separating cesium ions from an acidic aqueous solution also containing other ions

    DOEpatents

    Dietz, Mark L.; Horwitz, E. Philip; Bartsch, Richard A.; Barrans, Jr., Richard E.; Rausch, David

    1999-01-01

    A crown ether cesium ion extractant is disclosed as is its synthesis. The crown ether cesium ion extractant is useful for the selective purification of cesium ions from aqueous acidic media, and more particularly useful for the isolation of radioactive cesium-137 from nuclear waste streams. Processes for isolating cesium ions from aqueous acidic media using the crown ether cesium extractant are disclosed as are processes for recycling the crown ether cesium extractant and processes for recovering cesium from a crown ether cesium extractant solution.

  14. Composition and process for separating cesium ions from an acidic aqueous solution also containing other ions

    DOEpatents

    Dietz, M.L.; Horwitz, E.P.; Bartsch, R.A.; Barrans, R.E. Jr.; Rausch, D.

    1999-03-30

    A crown ether cesium ion extractant is disclosed as is its synthesis. The crown ether cesium ion extractant is useful for the selective purification of cesium ions from aqueous acidic media, and more particularly useful for the isolation of radioactive cesium-137 from nuclear waste streams. Processes for isolating cesium ions from aqueous acidic media using the crown ether cesium extractant are disclosed as are processes for recycling the crown ether cesium extractant and processes for recovering cesium from a crown ether cesium extractant solution. 4 figs.

  15. 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.

  16. Dissolution state of cellulose in aqueous systems. 2. Acidic solvents.

    PubMed

    Alves, Luis; Medronho, Bruno; Antunes, Filipe E; Topgaard, Daniel; Lindman, Björn

    2016-10-20

    Cellulose is insoluble in water but can be dissolved in strong acidic or alkaline conditions. How well dissolved cellulose is in solution and how it organizes are key questions often neglected in literature. The typical low pH required for dissolving cellulose in acidic solvents limits the use of typical characterization techniques. In this respect, Polarization Transfer Solid State NMR (PT ssNMR) emerges as a reliable alternative. In this work, combining PT ssNMR, microscopic techniques and X-ray diffraction, a set of different acidic systems (phosphoric acid/water, sulfuric acid/glycerol and zinc chloride/water) is investigated. The studied solvent systems are capable to efficiently dissolve cellulose, although degradation occurs to some extent. PT ssNMR is capable to identify the liquid and solid fractions of cellulose, the degradation products and it is also sensitive to gelation. The materials regenerated from the acidic dopes were found to be highly sensitive to the solvent system and to the presence of amphiphilic additives in solution. PMID:27474617

  17. Histological effects of aqueous acids and gaseous hydrogen chloride on bean leaves

    SciTech Connect

    Swiecki, T.J.; Endress, A.G.; Taylor, O.C.

    1982-01-01

    Primary leaves of Phaseoulus vulgaris L. (pinto bean), 9 or 12 days from sowing, were exposed to aqueous acids, chloride salts, or hydrogen chloride gas. Leaves were examined for the presence and severity of resultant visible injury and samples for light and scanning electron microscopy. Exposure to 0.06 N HCl, HNO/sub 3/, H/sub 2/SO/sub 4/ or 14.5-19.0 mg m/sup -3/ gaseous HCl for 20 min evoked similar foliar injury including glazing and necrosis of the laminas. This injury appeared to result initially from plasmolysis and collapse of the epidermis and subsequently of the underlying mesophyll. Cellular injury was accompanied by various cytoplasmic alterations. Microscopic symptoms observed in leaves exposed to gaseous HCl or aqueous acids included vesicles and particulates within the larger vacuoles. Similar symptoms were present in leaves exposed to polyethylene glycol 6000. Differential effects included formation of necrotic pits and preferential injury to paravascular tissues in leaves treated with aqueous acids and crystalline chloroplast inclusions in gaseous HCl-treated and water-stressed leaves. The visible and microscopic appearances of leaves exposed to aqueous acids or gaseous HCl were compared and related to injury stemming from acid precipitation and a possible mechanism of action for gaseous HCl phytotoxicity.

  18. Acid gas absorption in aqueous solutions of mixed amines

    SciTech Connect

    Rinker, E.B.; Ashour, S.S.; Sandall, O.C.

    1996-12-31

    A mass transfer model has been developed to describe the rate of absorption (or desorption) of H{sub 2}S and CO{sub 2} in aqueous blends of a tertiary and a secondary or a primary amine. The model is based on penetration theory, and all significant chemical reactions are incorporated in the model. The reactions are taken to be reversible, with reactions involving only a proton transfer considered to be at equilibrium. The particular amines studied in this research were methyldiethanolamine (MDEA), a tertiary amine, and diethanolamine (DEA), a secondary amine. Key physicochemical data needed in the model, such as diffusion coefficients, kinetic rate constants, and gas solubilities, were measured. Experimental absorption rates of CO{sub 2} and H{sub 2}S were measured in a model gas-liquid contacting device and were compared with model predictions. Experiments were carried out for single amine solutions (both MDEA and DEA) and for amine blends.

  19. Acid gas treating by aqueous alkanolamines. Annual report, January-December 1994

    SciTech Connect

    Sandall, O.C.; Rinker, E.B.; Ashour, S.

    1994-12-01

    The objective of this work is to investigate the simulateneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed this year the authors have measured the density, viscosity and surface tension of pure MDEA and DEA over a range in temperatures. The diffusivity of N2O was measured in aqueous blends of MDEA and DEA at 50 wt% total amine for various ratios of DEA to MDEA over the temperature range 20 to 80 deg. C. A theoretically-based model has been developed for the correlation of the physical solubility of N2O in aqueous amine solutions. A penetration theory type model which was developed to describe acid gas absorption in aqueous amine solutions was used to carry out a sensitivity analysis for the various parameters affecting the rate of absorption of CO2 in MDEA solutions.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  1. Sulphur mustard degradation on zirconium doped Ti-Fe oxides.

    PubMed

    Štengla, Václav; Grygar, Tomáš Matys; Opluštil, František; Němec, Tomáš

    2011-09-15

    Zirconium doped mixed nanodispersive oxides of Ti and Fe were prepared by homogeneous hydrolysis of sulphate salts with urea in aqueous solutions. Synthesized nanodispersive metal oxide hydroxides were characterised as the Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) microanalysis, and acid-base titration. These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (chemical warfare agent HD or bis(2-chloroethyl)sulphide). The presence of Zr(4+) dopant tends to increase both the surface area and the surface hydroxylation of the resulting doped oxides in such a manner that it can contribute to enabling the substrate adsorption at the oxide surface and thus accelerate the rate of degradation of warfare agents. The addition of Zr(4+) to the hydrolysis of ferric sulphate with urea shifts the reaction route and promotes formation of goethite at the expense of ferrihydrite. We discovered that Zr(4+) doped oxo-hydroxides of Ti and Fe exhibit a higher degradation activity towards sulphur mustard than any other yet reported reactive sorbents. The reaction rate constant of the slower parallel reaction of the most efficient reactive sorbents is increased with the increasing amount of surface base sites. PMID:21775058

  2. STABILITY OF MFI ZEOLITE-FILLED PDMS MEMBRANES DURING PERVAPORATIVE ETHANOL RECOVERY FROM AQUEOUS MIXTURES CONTAINING ACETIC ACID

    EPA Science Inventory

    Pervaporation is a potential process for recovering bioethanol produced from biomass fermentation. Fermentation broths contain ethanol, water, and a variety of other compounds, often including carboxylic acids. The effects of acetic acid on long-term pervaporation of aqueous et...

  3. Sulphur geodynamic cycle

    PubMed Central

    Kagoshima, Takanori; Sano, Yuji; Takahata, Naoto; Maruoka, Teruyuki; Fischer, Tobias P.; Hattori, Keiko

    2015-01-01

    Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucidate the geochemical cycle of sulphur and the evolution of ocean chemistry. This paper presents S/3He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur flux of 100 Gmol/y at MOR. The S/3He ratios of high-temperature volcanic gases show sulphur flux of 720 Gmol/y at arc volcanoes (ARC) with a contribution from the mantle of 2.9%, which is calculated as 21 Gmol/y. The C/S flux ratio of 12 from the mantle at MOR and ARC is comparable to the C/S ratio in the surface inventory, which suggests that these elements in the surface environments originated from the upper mantle. PMID:25660256

  4. Sulphur geodynamic cycle

    NASA Astrophysics Data System (ADS)

    Kagoshima, Takanori; Sano, Yuji; Takahata, Naoto; Maruoka, Teruyuki; Fischer, Tobias P.; Hattori, Keiko

    2015-02-01

    Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucidate the geochemical cycle of sulphur and the evolution of ocean chemistry. This paper presents S/3He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur flux of 100 Gmol/y at MOR. The S/3He ratios of high-temperature volcanic gases show sulphur flux of 720 Gmol/y at arc volcanoes (ARC) with a contribution from the mantle of 2.9%, which is calculated as 21 Gmol/y. The C/S flux ratio of 12 from the mantle at MOR and ARC is comparable to the C/S ratio in the surface inventory, which suggests that these elements in the surface environments originated from the upper mantle.

  5. Sulphur geodynamic cycle.

    PubMed

    Kagoshima, Takanori; Sano, Yuji; Takahata, Naoto; Maruoka, Teruyuki; Fischer, Tobias P; Hattori, Keiko

    2015-01-01

    Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucidate the geochemical cycle of sulphur and the evolution of ocean chemistry. This paper presents S/(3)He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur flux of 100 Gmol/y at MOR. The S/(3)He ratios of high-temperature volcanic gases show sulphur flux of 720 Gmol/y at arc volcanoes (ARC) with a contribution from the mantle of 2.9%, which is calculated as 21 Gmol/y. The C/S flux ratio of 12 from the mantle at MOR and ARC is comparable to the C/S ratio in the surface inventory, which suggests that these elements in the surface environments originated from the upper mantle. PMID:25660256

  6. 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.

  7. Hydrogen-Deuterium Exchange of Meteoritic Dicarboxylic Acids During Aqueous Extraction

    NASA Technical Reports Server (NTRS)

    Fuller, M.; Huang, Y.

    2002-01-01

    This study examines the extent of hydrogen-deuterium exchange on dicarboxylic acids during aqueous extraction. Deuterium enrichment was observed to be a function of diacid structure as well as delta-D. Additional information is contained in the original extended abstract.

  8. CHEMICAL TRANSFORMATION MODULES FOR EULERIAN ACID DEPOSITION MODELS. VOLUME 2. THE AQUEOUS-PHASE CHEMISTRY

    EPA Science Inventory

    This study focuses on the review and evaluation of mechanistic and kinetic data for aqueous-phase reactions that lead to the production of acidic substances in the environment. The intent of this research is to provide a framework that can be used to develop a state-of-the-art aq...

  9. POLYSTYRENE SULFONIC ACID CATALYZED GREENER SYNTHESIS OF HYDRAZONES IN AQUEOUS MEDIUM USING MICROWAVES

    EPA Science Inventory

    An environmentally benign aqueous protocol for the synthesis of cyclic, bi-cyclic, and heterocyclic hydrazones using polystyrene sulfonic acid (PSSA) as a catalyst has been developed; the simple reaction proceeds efficiently in water in the absence of any organic solvent under mi...

  10. Rosmarinic acid content in antidiabetic aqueous extract from ocimum canum sims in Ghana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rosmarinic acid (RA) is an important polyphenol that is found in a variety of herbs including Ocimum canum sims (locally called eme or akokobesa in Ghana). Aqueous extracts from the leaves of O. canum are used as an antidiabetic herbal medicine in Ghana. Analytical TLC was used to examine the compos...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. SOLVENT EXTRACTION PROCESS FOR SEPARATING URANIUM AND PLUTONIUM FROM AQUEOUS ACIDIC SOLUTIONS OF NEUTRON IRRADIATED URANIUM

    DOEpatents

    Bruce, F.R.

    1962-07-24

    A solvent extraction process was developed for separating actinide elements including plutonium and uranium from fission products. By this method the ion content of the acidic aqueous solution is adjusted so that it contains more equivalents of total metal ions than equivalents of nitrate ions. Under these conditions the extractability of fission products is greatly decreased. (AEC)

  17. THE ROLE OF SELECTED CATIONS IN THE FORMATION OF PSEUDOMICELLES IN AQUEOUS HUMIC ACID (R822832)

    EPA Science Inventory

    The fluorescence intensity enhancement of a pyrene probe in aqueous humic acid solutions was assessed in terms of added lanthanide and thorium cations. Among the trivalent ions it was found that size played a role, with the small Lu3+ ion producing the greatest increase in pyrene...

  18. Standard enthalpies of formation of α-aminobutyric acid and products of its dissociation in an aqueous solution

    NASA Astrophysics Data System (ADS)

    Lytkin, A. I.; Chernikov, V. V.; Krutova, O. N.

    2016-08-01

    Heats of solution of crystalline α-aminobutyric acid in water and in aqueous solutions of potassium hydroxide at 298.15 K are measured by means of direct calorimetry. Standard enthalpies of formation of the amino acid and products of its dissociation in an aqueous solution are calculated.

  19. Salt and mesophase formation in aqueous suspensions of lauric acid.

    PubMed

    Smith, S W; Anderson, B D

    1993-10-01

    The solubility and solution behavior of lauric acid (LA) and its 1:1 acid soap (potassium hydrogen dilaurate) were investigated at 32 degrees C over a pH range of 2.5-8.5 and at varying KCl concentrations to examine the self-association of this long-chain carboxylic acid under these conditions. LA's solubility in water exhibited the classical pH dependence of a monocarboxylic acid with no evidence of self-association. In 0.1 M KCl between pH 6.3 and pH 7.3, filtered samples were turbid, suggesting the presence of high molecular weight aggregates (mesophase), which could be removed by ultrafiltration. The apparent LA solubility vs pH profile in ultrafiltered samples was consistent with a solid phase consisting of either the free acid (pH < 6.5) or potassium hydrogen dilaurate (pH > 6.5), again with no evidence of self-association to form low molecular weight species (dimers, etc.). Quasi-elastic light scattering (QLS) studies and mannitol trapping experiments indicated that vesicles were present in samples containing mesophase. The mesophase composition was characterized and a mass-action law for mesophase formation was developed to describe the apparent LA solubility versus pH in the mesophase region in terms of three parameters. The index of cooperativity, theta, indicated that the mesophase consists of approximately 25 molecules of LA with an acid:anion ratio, rho, of 1.7. The standard free energy of mesophase formation per mole of monomer was determined to be -6.3 kcal/mol. The aggregate size determined thermodynamically is several orders of magnitude less than that of the mesophase particle size determined by QLS measurements, suggesting that the LA monomer concentration in equilibrium with mesophase may be governed by a small unit domain of the vesicle. These observations may have a bearing on the thermodynamics of self-assembly of lipid bilayer membranes. PMID:8272419

  20. Emergency cooling experiments with aqueous boric acid solution in the REWET-II facility

    SciTech Connect

    Kervinen, T.; Tuunanen, J.

    1987-01-01

    Although boron is widely used as soluble neutron poison in nuclear reactors (boric acid in pressurized water reactors, sodium pentaborate in boiling water reactors), there is a lack of experimental data about aqueous boron solution behavior during loss-of-coolant accidents. The main aims of the REWET boric acid experiments were to study the behavior of aqueous boric acid solution during long-term cooling of a nuclear reactor and to find out the circumstances in which boric acid crystallization takes place. In the experiments, carried out in the facility of a 19-fuel-rod simulator bundle, boric acid crystallization caused the uncovering of the bundle, which always occurred on the water surface. However, crossflows and backflows in a reactor presumably make the concentrations uniform and thus retard crystallization. Therefore, experimental investigations of aqueous boric acid solution behavior will be carried out for the next 2 yr in a larger scale experimental facility. The new facility will be a simulator of the Loviisa VVER-440 reactor with a scaling factor of 1:349 for power and volumes and 1:1 for elevations. The facility will contain a full-scale rod bundle.

  1. Reduction of hexavalent chromium by ascorbic acid in aqueous solutions.

    PubMed

    Xu, Xiang-Rong; Li, Hua-Bin; Li, Xiao-Yan; Gu, Ji-Dong

    2004-11-01

    Hexavalent chromium is a priority pollutant in the USA and many other countries. Reduction of Cr(VI) to Cr(III) is environmentally favorable as the latter species is not toxic to most living organisms and also has a low mobility and bioavailability. Reduction of Cr(VI) by ascorbic acid (vitamin C) as a reductant was studied using potassium dichromate solution as the model pollutant. Effects of concentration of vitamin C, pH, temperature, irradiation and reaction time on the reduction of Cr(VI) were examined. Cr(VI) might be reduced by vitamin C not only in acidic conditions but also in weakly alkaline solutions. The reduction of Cr(VI) by vitamin C might occur not only under irradiation but also in the dark. Vitamin C is an important biological reductant in humans and animals, and not toxic. It is water-soluble and can easily permeate through various types of soils. The results indicate that vitamin C could be used in effective remediation of Cr(VI)-contaminated soils and groundwater in a wide range of pH, with or without sunlight. PMID:15488923

  2. Aminocarbonyloxymethyl ester prodrugs of flufenamic acid and diclofenac: suppressing the rearrangement pathway in aqueous media.

    PubMed

    Ribeiro, Lina; Silva, Nuno; Iley, Jim; Rautio, Jarkko; Järvinen, Tomi; Mota-Filipe, Hélder; Moreira, Rui; Mendes, Eduarda

    2007-01-01

    Aminocarbonyloxymethyl ester prodrugs are known to undergo rearrangement in aqueous solutions to form the corresponding N-acylamine side product via an O-->N intramolecular acyl transfer from the carbamate conjugate base. Novel aminocarbonyloxymethyl esters of diclofenac and flufenamic acid containing amino acid amide carriers were synthesized and evaluated as potential prodrugs displaying less ability to undergo rearrangement. These compounds were prepared in reasonable yield by a four-step synthetic method that uses the appropriate N-Boc-protected amino acid N-hydroxysuccinimide ester and secondary amine and chloromethyl chloroformate as key reactants. Their reactivity in pH 7.4 buffer and 80% human plasma at 37 degrees C was assessed by RP-HPLC. The aminocarbonyloxymethyl esters containing a secondary carbamate group derived from amino acids such as glycine or phenylalanine were hydrolyzed quantitatively to the parent drug both in non-enzymatic and enzymatic conditions, with no rearrangement product being detected. The oral bioavailability in rats was determined for selected diclofenac derivatives. These derivatives displayed a bioavailability of 25 to 68% relative to that of diclofenac, probably due to their poor aqueous solubility and lipophilicity. These results suggest that further optimization of aminocarbonyloxymethyl esters as potential prodrugs for non-steroidal anti-inflammatory drugs require the use of amino acid carriers with ionizable groups to improve aqueous solubility. PMID:17206608

  3. Regeneration of an aqueous solution from an acid gas absorption process by matrix stripping

    DOEpatents

    Rochelle, Gary T.; Oyenekan, Babatunde A.

    2011-03-08

    Carbon dioxide and other acid gases are removed from gaseous streams using aqueous absorption and stripping processes. By replacing the conventional stripper used to regenerate the aqueous solvent and capture the acid gas with a matrix stripping configuration, less energy is consumed. The matrix stripping configuration uses two or more reboiled strippers at different pressures. The rich feed from the absorption equipment is split among the strippers, and partially regenerated solvent from the highest pressure stripper flows to the middle of sequentially lower pressure strippers in a "matrix" pattern. By selecting certain parameters of the matrix stripping configuration such that the total energy required by the strippers to achieve a desired percentage of acid gas removal from the gaseous stream is minimized, further energy savings can be realized.

  4. Analysis of the amino acids of soy globulins by AOT reverse micelles and aqueous buffer.

    PubMed

    Zhao, Xiaoyan; Chen, Jun; Lu, Zhifang; Ling, Xiangqing; Deng, Peng; Zhu, Qingjun; Du, Fangling

    2011-10-01

    The 7S and 11S globulins from soybean proteins using reverse micelle and aqueous buffer extraction methods were characterized by using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscope (SEM), and their amino acid compositions were also evaluated. SDS-PAGE did not show electrophoretic differences between 7S and 11S globulin subunits with two extraction methods. SEM analysis showed that the AOT reverse micelle processing of 7S and 11S globulins induced a reduction of droplet size. Some individual amino acid contents of 7S and 11S globulins using two extraction methods were different, some were similar. In all the samples, the glutamic acid, aspartic acid, and leucine were the dominant amino acids while the cystine and methionine were the first-limiting amino acids. The proportion of essential amino acids to the total amino acids (E/T) of the 7S globulin from aqueous buffer and reverse micelles was similar. While significant differences were obtained in the proportion of E/T of the 11S globulin. PMID:21647686

  5. 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.

  6. Conversion of Aqueous Ammonia-Treated Corn Stover to Lactic Acid by Simultaneous Saccharification and Cofermentation

    NASA Astrophysics Data System (ADS)

    Zhu, Yongming; Lee, Y. Y.; Elander, Richard T.

    Treatment of corn stover with aqueous ammonia removes most of the structural lignin, whereas retaining the majority of the carbohydrates in the solids. After treatment, both the cellulose and hemicellulose in corn stover become highly susceptible to enzymatic digestion. In this study, corn stover treated by aqueous ammonia was investigated as the substrate for lactic acid production by simultaneous saccharification and cofermentation (SSCF). A commercial cellulase (Spezyme-CP) and Lactobacillus pentosus American Type Culture Collection (ATCC) 8041 (Spanish Type Culture Collection [CECT]-4023) were used for hydrolysis and fermentation, respectively. In batch SSCF operation, the carbohydrates in the treated corn stover were converted to lactic acid with high yields, the maximum lactic acid yield reaching 92% of the stoichiometric maximum based on total fermentable carbohydrates (glucose, xylose, and arabinose). A small amount of acetic acid was also produced from pentoses through the phosphoketolase pathway. Among the major process variables for batch SSCF, enzyme loading and the amount of yeast extract were found to be the key factors affecting lactic acid production. Further tests on nutrients indicated that corn steep liquor could be substituted for yeast extract as a nitrogen source to achieve the same lactic acid yield. Fed-batch operation of the SSCF was beneficial in raising the concentration of lactic acid to a maximum value of 75.0 g/L.

  7. A method for determining thermophysical properties of organic material in aqueous solutions: Succinic acid

    NASA Astrophysics Data System (ADS)

    Riipinen, I.; Svenningsson, B.; Bilde, M.; Gaman, A.; Lehtinen, K. E. J.; Kulmala, M.

    2006-12-01

    A method for determining evaporation rates and thermodynamic properties of aqueous solution droplets is introduced. The method combines evaporation rate measurements using modified TDMA technique with data evaluation using an accurate evaporation model. The first set of data has been collected and evaluated for succinic acid aqueous solution droplets. Evaporation rates of succinic acid solution droplets have been measured using a TDMA system at controlled relative humidity (65%) and temperature (298 K). A temperature-dependent expression for the saturation vapour pressure of pure liquid phase succinic acid at atmospheric temperatures has been derived by analysing the evaporation rate data with a numerical model. The obtained saturation vapour pressure of liquid phase succinic acid is ln( p) = 118.41 - 16204.8/ T - 12.452ln( T). The vapour pressure is in unit of Pascal and the temperature in Kelvin. A linear expression for the enthalpy of vaporization for liquid state succinic acid is also presented. According to the results presented in the following, a literature expression for the vapour pressure of liquid phase succinic acid defined for temperatures higher than 461 K [Yaws, C.L., 2003. Yaws' Handbook of Thermodynamic and Physical Properties of Chemical Compounds, Knovel] can be extrapolated to atmospheric temperatures with very good accuracy. The results also suggest that at 298 K the mass accommodation coefficient of succinic acid is unity or very close to unity.

  8. Electrochemiluminescence of Tris(2,2'-bipyridyl)ruthenium(II) with Ascorbic Acid and Dehydroascorbic Acid in Aqueous and Non-aqueous Solutions.

    PubMed

    Takahashi, Fumiki; Hattori, Kaoru; Matsuoka, Masanori; Jin, Jiye

    2016-01-01

    The electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3(2+)) is studied in non-aqueous media using dehydroascorbic acid (DHA) as coreactant to validate the evidence for the mechanism of the ascorbic acid (H2A)/Ru(bpy)3(2+) ECL system in an aqueous media. DHA is electrochemically reduced around -1.2 V vs. Ag/Ag(+) in pure acetonitrile to generate the ascorbyl radical anion (A(•-)), which is confirmed by in-situ UV-visible absorption measurements using a thin-layer spectroelectrochemical cell. The ECL of the DHA/Ru(bpy)3(2+) system in non-aqueous media is not observed in the potential range from 0 to +1.4 V in anodic potential sweep mode; however, distinct ECL is detected using double potential step electrolysis from -1.2 to +1.4 V vs. Ag/Ag(+). The ECL may be generated by a homogeneous charge-transfer process between A(•-) produced during the first pulse potential step (-1.2 V) and Ru(bpy)3(3+) generated during the second pulse potential step (+1.4 V). The calculated standard enthalpy (-ΔH°) for the charge-transfer reaction between A(•-) and Ru(bpy)3(3+) is 2.29 eV, which is larger than the lowest excited singlet state energy of Ru(bpy)3(2+) (*Ru(bpy)3(2+); 2.03 eV, 610 nm). It is determined that the generated intermediate A(•-) is crucial in the Ru(bpy)3(2+) ECL reaction. PMID:27063718

  9. Pretreatment of rice straw with combined process using dilute sulfuric acid and aqueous ammonia

    PubMed Central

    2013-01-01

    Background Use of lignocellulosic biomass has received attention lately because it can be converted into various versatile chemical compounds by biological processes. In this study, a two-step pretreatment with dilute sulfuric acid and aqueous ammonia was performed efficiently on rice straw to obtain fermentable sugar. The soaking in aqueous ammonia process was also optimized by a statistical method. Results Response surface methodology was employed. The determination coefficient (R2) value was found to be 0.9607 and the coefficient of variance was 6.77. The optimal pretreatment conditions were a temperature of 42.75°C, an aqueous ammonia concentration of 20.93%, and a reaction time of 48 h. The optimal enzyme concentration for saccharification was 30 filter paper units. The crystallinity index was approximately 60.23% and the Fourier transform infrared results showed the distinct peaks of glucan. Ethanol production using Saccharomyces cerevisiae K35 was performed to verify whether the glucose saccharified from rice straw was fermentable. Conclusions The combined pretreatment using dilute sulfuric acid and aqueous ammonia on rice straw efficiently yielded fermentable sugar and achieved almost the same crystallinity index as that of α-cellulose. PMID:23898802

  10. Crystallization and immersion freezing ability of oxalic and succinic acid in multicomponent aqueous organic aerosol particles

    NASA Astrophysics Data System (ADS)

    Wagner, Robert; Höhler, Kristina; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin

    2015-04-01

    This study reports on heterogeneous ice nucleation efficiency of immersed oxalic and succinic acid crystals in the temperature range from 245 to 215 K, as investigated with expansion cooling experiments using suspended particles. In contrast to previous laboratory work with emulsified solution droplets where the precipitation of solid inclusions required a preceding freezing/evaporation cycle, we show that immersed solids readily form by homogeneous crystallization within aqueous solution droplets of multicomponent organic mixtures, which have noneutonic compositions with an excess of oxalic or succinic acid. Whereas succinic acid crystals did not act as heterogeneous ice nuclei, immersion freezing by oxalic acid dihydrate crystals led to a reduction of the ice saturation ratio at freezing onset by 0.066-0.072 compared to homogeneous freezing, which is by a factor of 2 higher than previously reported laboratory data. These observations emphasize the importance of oxalic acid in heterogeneous ice nucleation.

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

    PubMed Central

    2013-01-01

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

  12. Effective Removal of Tetracycline from Aqueous Solution by Organic Acid-Coated Magnetic Nanoparticles.

    PubMed

    Guo, Liang; Liang, Yuyan; Chen, Xuelan; Xu, Wei; Wu, Kesheng; Wei, Hua; Xiong, Yonghua

    2016-03-01

    Self-assembled iron oxide nanocomposites are good magnetic nano-adsorbents that can be prepared using simple methods. Four types of organic acid-functionalised (oleic acid, undecenoic acid, caprylic acid or hexanoic acid) magnetic nanoparticles (MNPs) were synthesised through a one-pot chemisorption method for the removal of tetracycline (TC) from aqueous solution. The undecenoic acid-coated MNPs (UA-MNPs) exhibited the highest adsorption efficiency and can be easily retrieved with a low-gradient magnetic separator (0.4 Tesla) at pH 5.0 aqueous solution. The TC adsorption process on the UA-MNPs followed the Langmuir isotherm and the maximum adsorption capacities increased from 86.96 mg g(-1) to 222.2 mg g(-1) with the increase in temperature from 288 K to 318 K. The kinetics of adsorption fits pseudo-second-order model perfectly with a rate constant, 5.946 g mg(-1) min(-1) at 298 K. The positive values of the enthalpy (AH) and the negative value of the free energy (AG) indicated an endothermic and spontaneous adsorption process of TC on the UA-MNPs. Moreover, the UA-MNPs possessed excellent ability to adsorb the other three major types of TC antibiotics, including chlortetracycline, oxytetracycline and doxycycline. PMID:27455621

  13. Sequence of morphological transitions in two-dimensional pattern growth from aqueous ascorbic Acid solutions.

    PubMed

    Paranjpe, A S

    2002-08-12

    A sequence of morphological transitions in two-dimensional dehydration patterns of aqueous solutions of ascorbic acid is observed with humidity as a control parameter. Change in morphology occurs due to humidity induced variation in the concentration of the metastable supersaturated solution phase formed after initial solvent evaporation. As percent humidity is varied from 40 to 80, patterns change from compact circular --> radial --> density modulated radial (a new morphology) --> density modulated circular --> density modulated dendritic (a new morphology) --> dense branching. PMID:12190528

  14. Removal of transition metals from dilute aqueous solution by carboxylic acid group containing absorbent polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin has Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin to ...

  15. Sulfate Mineral Formation from Acid-Weathered Phyllosilicates: Implications for the Aqueous History of Mars

    NASA Technical Reports Server (NTRS)

    Craig, P. I.; Ming, D. W.; Rampe, E. B.; Morris, R. V.

    2015-01-01

    Phyllosilicates on Mars are thought to have formed under neutral to alkaline conditions during Mars' earliest Noachian geologic era (approx. 4.1-3.7 Gya). Sulfate formation, on the other hand, requires more acidic conditions which are thought to have occurred later during Mars' Hesperian era (approx. 3.7-3.0 Gya). Therefore, regions on Mars where phyllosilicates and sulfates are found in close proximity to each other provide evidence for the geologic and aqueous conditions during this global transition. Both phyllosilicates and sulfates form in the presence of water and thus give clues to the aqueous history of Mars and its potential for habitability. Phyllosilicates that formed during the Noachian era may have been weathered by the prevailing acidic conditions that characterize the Hesperian. Therefore, the purpose of this study is to characterize the alteration products resulting from acid-sulfate weathered phyllosilicates in laboratory experiments. This study focuses on two phyllosilicates commonly identified with sulfates on Mars: nontronite and saponite. We also compare our results to observations of phyllosilicates and sulfates on Mars to better understand the formation process of sulfates in close proximity to phyllosilicates on Mars and constrain the aqueous conditions of these regions on Mars.

  16. Insights Into the Aqueous History of Mars from Acid-Sulfate Weathered Phyllosilicates

    NASA Technical Reports Server (NTRS)

    Craig, P. I.; Ming, D. W.; Rampe, E. B.; Morris, R. V.

    2016-01-01

    Phyllosilicates on Mars are thought to have formed during Mars' earliest Noachian geologic era (approx. 4.1-3.7 Ga). Sulfate formation, on the other hand, requires more acidic conditions which are thought to have occurred later during Mars' Hesperian era (approx. 3.7-3.0 Ga). Therefore, regions on Mars where phyllosilicates and sulfates are found in close proximity to each other provide evidence for the aqueous conditions during this global transition. Both phyllosilicates and sulfates form in the presence of water and thus give clues to the aqueous history of Mars and its potential for habitability. Phyllosilicates that formed during the Noachian era would have been weathered by the prevailing acidic conditions that define the Hesperian. Therefore, the purpose of this study is to characterize the alteration products of acid-sulfate weathered phyllosilicates in laboratory experiments, focusing on the Fe/Mg-smectites commonly identified on Mars. We also compare our results to observations of phyllosilicates and sulfates on Mars in regions such as Endeavour Crater and Mawrth Vallis to understand the formation process of sulfates and constrain the aqueous history of these regions.

  17. Micellization properties of zwitterionic surfactants derived from nicotinic acid in aqueous solutions

    SciTech Connect

    Wiederkehr, N.A.; Kalyanasundaram, K.; Graetzel, M. ); Viscardi, G.; Savarino, P.; Barni, E. )

    1991-01-01

    Various properties of monomeric and micellar (aggregated) forms of a series of zwitterionic surfactants based on nicotinic acid (N-alkylnicotinic acids), R-NA (R = C{sub 8}, C{sub 10}, C{sub 12}, C{sub 14}, and C{sub 16}) have been determined in aqueous solution by utilization of a number of physical methods (visible light absorption, fluorescence probe analysis, surfactant tension measurements, and low-angle light scattering): protonation equilibria, extent of counterion adsorption, critical micellar temperature, critical micellar concentration, and micellar aggregation number.

  18. 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.

  19. Statistical Thermodynamic Model for Surface Tension of Aqueous Organic Acids with Consideration of Partial Dissociation.

    PubMed

    Boyer, Hallie C; Dutcher, Cari S

    2016-06-30

    With statistical mechanics, an isotherm-based surface tension model for single solute aqueous solutions was derived previously (Wexler et al. J. Phys. Chem. Lett. 2013) for the entire concentration range, from infinite dilution to pure liquid solute, as a function of solute activity. In recent work (Boyer et al. J. Phys. Chem. Lett. 2015), empirical model parameters were reduced through physicochemical interpretations of both electrolyte and organic solutes, enabling surface tension predictions for systems where there is little or no data. The prior binary model is extended in the current work for the first time to treat multicomponent systems to predict surface tensions of partially dissociating organic acids (acetic, butyric, citric, formic, glutaric, maleic, malic, malonic, oxalic, propionic, and succinic acids). These organic acids are especially applicable to the study of atmospheric aqueous aerosols, due to their abundance in the atmosphere. In the model developed here, surface tension depends explicitly on activities of both the neutral organic and deprotonated components of the acid. The relative concentrations of the nondissociated and dissociated mole fractions are found using known dissociation constants. Model parameters strongly depend on molecular size, number of functional groups, O:C ratio, and number of carbons. For all organic acids in this study, fully predictive modeling of surface tensions is demonstrated. PMID:27219322

  20. The Solubility of Xenon in Simple Organic Solvents and in Aqueous Amino Acid Solutions.

    NASA Astrophysics Data System (ADS)

    Himm, Jeffrey Frank

    We have measured the Ostwald solubility (L) of ('133)Xe in a variety of liquids, including normal alkanes, normal alkanols, and aqueous solutions of amino acids, NaCl, and sucrose. For the alkanes and alkanols, measurements were made in the temperature range from 10-50(DEGREES)C. Values of L were found to decrease with increasing temperature, and also with increasing chain length, for both series of solvents. Thermodynamic properties of solution (enthalpy and entropy of solution) are calculated using both mole fraction and number density scales. Results are interpreted using Uhlig's model of the solvation process. Measurements of L in aqueous amino acid solutions were made at 25(DEGREES)C. Concentrations of amino acids in solution varied from near saturation for each of the amino acids studied to pure water. In all solutions, except those with NaCl, L decreases linearly with increasing solution molarity. Hydration numbers (H), the mean number of water molecules associated with each solute molecule, were determined for each amino acid, for NaCl, and for sucrose. Values of H obtained ranged from near zero (arginine, H = 0.2 (+OR-) 0.5) to about 16 (NaCl, H = 16.25 (+OR-) 0.3).

  1. Aqueous Phase Photo-Oxidation of Succinic Acid: Changes in Hygroscopic Properties and Reaction Products

    NASA Astrophysics Data System (ADS)

    Hudson, P. K.; Ninokawa, A.; Hofstra, J.; de Lijser, P.

    2013-12-01

    Atmospheric aerosol particles have been identified as important factors in understanding climate change. The extent to which aerosols affect climate is determined, in part, by hygroscopic properties which can change as a result of atmospheric processing. Dicarboxylic acids, components of atmospheric aerosol, have a wide range of hygroscopic properties and can undergo oxidation and photolysis reactions in the atmosphere. In this study, the hygroscopic properties of succinic acid aerosol, a non-hygroscopic four carbon dicarboxylic acid, were measured with a humidified tandem differential mobility analyzer (HTDMA) and compared to reaction products resulting from the aqueous phase photo-oxidation reaction of hydrogen peroxide and succinic acid. Reaction products were determined and quantified using gas chromatography-flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS) as a function of hydrogen peroxide:succinic acid concentration ratio and photolysis time. Although reaction products include larger non-hygroscopic dicarboxylic acids (e.g. adipic acid) and smaller hygroscopic dicarboxylic acids (e.g. malonic and oxalic acids), comparison of hygroscopic growth curves to Zdanovskii-Stokes-Robinson (ZSR) predictions suggests that the hygroscopic properties of many of the product mixtures are largely independent of the hygroscopicity of the individual components. This study provides a framework for future investigations to fully understand and predict the role of chemical reactions in altering atmospheric conditions that affect climate.

  2. 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.

  3. [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

  4. INFLUENCE OF AQUEOUS ALUMINUM AND ORGANIC ACIDS ON MEASUREMENT OF ACID NEUTRALIZING CAPACITY IN SURFACE WATERS

    EPA Science Inventory

    Acid neutralizing capacity (ANC) is used to quantify the acid-base status of surface waters. Acidic waters have bean defined as having ANC values less than zero, and acidification is often quantified by decreases in ANC. Measured and calculated values of ANC generally agree, exce...

  5. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution

    PubMed Central

    Zhou, Renwu; Zhou, Rusen; Zhuang, Jinxing; Zong, Zichao; Zhang, Xianhui; Liu, Dongping; Bazaka, Kateryna; Ostrikov, Kostya

    2016-01-01

    Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma. PMID:27183129

  6. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution.

    PubMed

    Zhou, Renwu; Zhou, Rusen; Zhuang, Jinxing; Zong, Zichao; Zhang, Xianhui; Liu, Dongping; Bazaka, Kateryna; Ostrikov, Kostya

    2016-01-01

    Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma. PMID:27183129

  7. 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.

  8. Influence of Acidity on Uranyl Nitrate Association in Aqueous Solutions: A Molecular Dynamics Simulation Study

    SciTech Connect

    de Almeida, Valmor F; Cui, Shengting; Khomami, Bamin; Ye, Xianggui; Smith, Rodney Bryan

    2010-01-01

    Uranyl ion complexation with water and nitrate is a key aspect of the uranium/plutonium extraction process. We have carried out a molecular dynamics simulation study to investigate this complexation process, including the molecular composition of the various complex species, the corresponding structure, and the equilibrium distribution of the complexes. The observed structures of the complexes suggest that in aqueous solution, uranyls are generally hydrated by 5 water molecules in the equatorial plane. When associating with nitrate ions, a water molecule is replaced by a nitrate ion, preserving the five-fold coordination and planar symmetry. Analysis of the pair correlation function between uranyl and nitrate suggests that nitrates bind to uranyl in aqueous solution mainly in a monodentate mode, although a small portion of bidentates occur. Dynamic association and dissociation between uranyls and nitrates take place in aqueous solution with a substantial amount of fluctuation in the number of various uranyl nitrate species. The average number of the uranyl mononitrate complexes shows a dependence on acid concentration consistent with equilibrium-constant analysis, namely, the concentration of [UO2NO3]+ increases with nitric acid concentration.

  9. The infrared optical constants of sulfuric acid at 250 K. [spectral reflectance measurement of aqueous solutions

    NASA Technical Reports Server (NTRS)

    Pinkley, L. W.; Williams, D.

    1976-01-01

    Results are presented for measurements of the IR spectral reflectance at near-normal incidence of aqueous solutions of sulfuric acid with acid concentrations of 75% and 95.6% by weight. Kramers-Kronig analyses of the reflectance data are employed to obtain values of the optical constants n(nu) and k(nu) in the spectral range from 400 to 6000 cm to the -1 power. The optical constants of these solutions at 250 K and 300 K are compared. It is found that in spectral regions remote from strong absorption bands, the values of the n(nu) indices obtained at 250 K agree with the values given by Lorentz-Lorenz correction of the same indices at 300 K. All absorption bands observed at 300 K are found to be present at 250 K with slight shifts in frequency and with significant differences in the k(nu) indices at the band maxima. Based on these results, it is concluded that the clouds of Venus probably consist of droplets of aqueous solutions of sulfuric acid with acid concentrations of about 75% by weight.

  10. Sorption of basic and acid dyes from aqueous solutions onto oxihumolite.

    PubMed

    Janos, Pavel; Sedivý, Pavel; Rýznarová, Milena; Grötschelová, Sylvie

    2005-05-01

    Naturally occurring kind of weathered and oxidised young brown coal called oxihumolite was used for an adsorptive removal of basic (Methylene Blue, Malachite Green) as well as acid (Egacid Orange, Midlon Black) dyes from waters. It was shown that both kinds of dyes can be sorbed onto oxihumolite. The maximum sorption capacities determined from the parameters of Langmuir isotherms ranged from 0.070 mmol g-1 (for Midlon Black) to 0.278 mmol g-1 (for Malachite Green) and did not differ significantly for basic and acid dyes. The dye sorption (except of Midlon Black) increased in the presence of inorganic salt. Non-ionic surfactants, and surfactants bearing the same charge as the dye exhibited only a minor effect on the dye sorption, whereas oppositely charged surfactants enhanced the dye sorption to a certain extent. The pH value of the aqueous phase exhibited rather pronounced effect on the sorption of acid dyes causing a suppression of the sorption with increasing pH. The sorption of basic dyes, on the other hand, remained almost unchanged in the examined pH range. Oxihumolite is recommended for the treatment of acid wastewaters because of its limited stability in alkaline aqueous solutions. PMID:15811417

  11. SMED - Sulphur MEditerranean Dispersion

    NASA Astrophysics Data System (ADS)

    Salerno, Giuseppe G.; Sellitto, Pasquale; Corradini, Stefano; Di Sarra, Alcide Giorgio; Merucci, Luca; Caltabiano, Tommaso; La Spina, Alessandro

    2016-04-01

    Emissions of volcanic gases and particles can have profound impacts on terrestrial environment, atmospheric composition, climate forcing, and then on human health at various temporal and spatial scales. Volcanic emissions have been identified as one of the largest sources of uncertainty in our understanding of recent climate change trends. In particular, a primary role is acted by sulphur dioxide emission due to its conversion to volcanic sulphate aerosol via atmospheric oxidation. Aerosols may play a key role in the radiative budget and then in photochemistry and tropospheric composition. Mt. Etna is one of the most prodigious and persistent emitters of gasses and particles on Earth, accounting for about 10% of global average volcanic emission of CO2 and SO2. Its sulphur emissions stand for 0.7 × 106 t S/yr9 and then about 10 times bigger than anthropogenic sulphur emissions in the Mediterranean area. Centrepiece of the SMED project is to advance the understanding of volcanogenic sulphur dioxide and sulphate aerosol particles dispersion and radiative impact on the downwind Mediterranean region by an integrated approach between ground- and space-based observations and modelling. Research is addressed by exploring the potential relationship between proximal SO2 flux and aerosol measured remotely in the volcanic plume of Mt. Etna between 2000 and 2014 and distal aerosol ground-based measurements in Lampedusa, Greece, and Malta from AERONET network. Ground data are combined with satellite multispectral polar and geostationary imagers able to detect and retrieve volcanic ash and SO2. The high repetition time of SEVIRI (15 minutes) will ensure the potential opportunity to follow the entire evolution of the volcanic cloud, while, the higher spatial resolution of MODIS (1x1 km2), are exploited for investigating the probability to retrieve volcanic SO2 abundances from passive degassing. Ground and space observations are complemented with atmospheric Lagrangian model

  12. Yeast fermentation of carboxylic acids obtained from pyrolytic aqueous phases for lipid production.

    PubMed

    Lian, Jieni; Garcia-Perez, Manuel; Coates, Ralph; Wu, Hongwei; Chen, Shulin

    2012-08-01

    The presence of very reactive C1-C4 molecules adversely affects the quality bio-oils produced from the pyrolysis of lignocellulosic materials. In this paper a scheme to produce lipids with Cryptococcus curvatus from the carboxylic acids in the pyrolytic aqueous phase collected in fractional condensers is proposed. The capacities of three oleaginous yeasts C. curvatus, Rhodotorula glutinis, Lipomyces starkeyi to ferment acetate, formate, hydroxylacat-aldehyde, phenol and acetol were investigated. While acetate could be a good carbon source for lipid production, formate provides additional energy and contributes to yeast growth and lipid production as auxiliary energy resource. Acetol could slightly support yeast growth, but it inhibits lipid accumulation. Hydroxyacetaldehyde and phenols showed high yeast growth and lipid accumulation inhibition. A pyrolytic aqueous phase with 20 g/L acetate was fermented with C. curvatus, after neutralization and detoxification to produce 6.9 g/L dry biomass and 2.2 g/L lipid. PMID:22705522

  13. Sulphur dioxide emissions in Europe 1880 1991 and their effect on sulphur concentrations and depositions

    NASA Astrophysics Data System (ADS)

    Mylona, Sophia

    1996-11-01

    A historical emission inventory for sulphur dioxide has been compiled for Europe covering the period 1880 1991. The estimated emissions have been used as input to the sulphur module of the EMEP/MSC-W acid deposition model. The aim was to show the way and the extent to which the historical development of anthropogenic sulphur dioxide emissions alone has affected the concentration and deposition fields of oxidised sulphur in Europe. Although acknowledged, effects exerted by the meteorological variability and the changing oxidising capacity of the atmosphere over the years have not been taken into consideration. Long-term emission estimates reveal that combustion of coal was the dominant emission source before World War II in all countries and combustion of liquid fuels thereafter in most. Releases from industrial processes were relatively small. National sulphur dioxide emissions peaked mainly in the 1960s and 1970s, whilst emission control measures resulted in gradual reductions in most countries in the 1980s. In Europe as a whole, coal combustion remained the major emission source throughout the century. Total anthropogenic releases increased by a factor of 10 between the 1880 s and 1970s when they peaked at approximately 55 million tonnes of sulphur dioxide, followed by a 30% decline in the 1980s. Uncertainties in national emission estimates due to uncertain sulphur contents in fossil fuels are within ± 30% for 22 out of 28 countries and ± 45% for the rest. The location of emission sources in Europe has shown over the years a progressive detachment from the coalfields towards a widespread distribution, accompanied in the last decades by considerable emission reductions over north-western and parts of central Europe and substantial increases in the south and south-east. Modelled air concentrations and depositions reflect to a great extent the emission pattern, revealing two- to six-fold increases between the 1880 s and 1970s. Maximum sulphur loadings are confined

  14. Experimental Shock Chemistry of Aqueous Amino Acid Solutions and the Cometary Delivery of Prebiotic Compounds

    NASA Astrophysics Data System (ADS)

    Blank, Jennifer G.; Miller, Gregory H.; Ahrens, Michael J.; Winans, Randall E.

    2001-02-01

    A series of shock experiments were conducted to assess the feasibility of the delivery of organic compounds to the Earth via cometary impacts. Aqueous solutions containing near-saturation levels of amino acids (lysine, norvaline, aminobutyric acid, proline, and phenylalanine) were sealed inside stainless steel capsules and shocked by ballistic impact with a steel projectile plate accelerated along a 12-m-long gun barrel to velocities of 0.5-1.9 km sec^-1. Pressure-temperature-time histories of the shocked fluids were calculated using 1D hydrodynamical simulations. Maximum conditions experienced by the solutions lasted 0.85-2.7 μs and ranged from 5.1-21 GPa and 412-870 K. Recovered sample capsules were milled open and liquid was extracted. Samples were analyzed using high performance liquid chromatography (HPLC) and mass spectrometry (MS). In all experiments, a large fraction of the amino acids survived. We observed differences in kinetic behavior and the degree of survivability among the amino acids. Aminobutyric acid appeared to be the least reactive, and phenylalanine appeared to be the most reactive of the amino acids. The impact process resulted in the formation of peptide bonds; new compounds included amino acid dimers and cyclic diketopiperazines. In our experiments, and in certain naturally occurring impacts, pressure has a greater influence than temperature in determining reaction pathways. Our results support the hypothesis that significant concentrations of organic material could survive a natural impact process.

  15. Experimental shock chemistry of aqueous amino acid solutions and the cometary delivery of prebiotic compounds.

    PubMed

    Blank, J G; Miller, G H; Ahrens, M J; Winans, R E

    2001-01-01

    A series of shock experiments were conducted to assess the feasibility of the delivery of organic compounds to the Earth via cometary impacts. Aqueous solutions containing near-saturation levels of amino acids (lysine, norvaline, aminobutyric acid, proline, and phenylalanine) were sealed inside stainless steel capsules and shocked by ballistic impact with a steel projectile plate accelerated along a 12-m-long gun barrel to velocities of 0.5-1.9 km sec-1. Pressure-temperature-time histories of the shocked fluids were calculated using 1D hydrodynamical simulations. Maximum conditions experienced by the solutions lasted 0.85-2.7 microseconds and ranged from 5.1-21 GPa and 412-870 K. Recovered sample capsules were milled open and liquid was extracted. Samples were analyzed using high performance liquid chromatography (HPLC) and mass spectrometry (MS). In all experiments, a large fraction of the amino acids survived. We observed differences in kinetic behavior and the degree of survivability among the amino acids. Aminobutyric acid appeared to be the least reactive, and phenylalanine appeared to be the most reactive of the amino acids. The impact process resulted in the formation of peptide bonds; new compounds included amino acid dimers and cyclic diketopiperazines. In our experiments, and in certain naturally occurring impacts, pressure has a greater influence than temperature in determining reaction pathways. Our results support the hypothesis that significant concentrations of organic material could survive a natural impact process. PMID:11296518

  16. Thermosensitivity of bile acid-based oligo(ethylene glycol) stars in aqueous solutions.

    PubMed

    Strandman, Satu; Le Dévédec, Frantz; Zhu, X X

    2011-08-01

    Amphiphilic star-shaped oligo(ethylene glycol)s with a hydrophobic bile acid core and varying number of hydrophilic arms have been made. Their thermal behavior in aqueous solutions depends on the number rather than the length of the arms. The two-armed lithocholate derivative showed the strongest tendency for association and exhibited the lowest cloud point (79 °C) of the oligomers made, as well as another phase separation at a lower temperature (31 °C). The "double thermosensitivity" arising both from the salt-dependent LCST of the oligo(ethylene glycol) segments and the temperature-responsive self-assembly of amphiphilic bile acid derivative provides an interesting path in the design of bile acid-based smart materials. PMID:21661073

  17. Solid supported in situ derivatization extraction of acidic degradation products of nerve agents from aqueous samples.

    PubMed

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

    2014-09-12

    This study deals with the solid supported in situ derivatization extraction of acidic degradation products of nerve agents present in aqueous samples. Target analytes were alkyl alkylphosphonic acids and alkylphosphonic acids, which are important environmental signatures of nerve agents. The method involved tert-butyldimethylchlorosilane mediated in situ silylation of analytes on commercially available diatomaceous solid phase extraction cartridges. Various parameters such as derivatizing reagent, its concentration, reaction time, temperature and eluting solvent were optimized. Recoveries of the analytes were determined by GC-MS which ranged from 60% to 86%. The limits of detection (LOD) and limit of quantification (LOQ) with selected analytes were achieved down to 78 and 213ngmL(-1) respectively, in selected ion monitoring mode. The successful applicability of method was also demonstrated on samples of biological origin such as plasma and to the samples received in 34th official proficiency test conducted by the Organization for Prohibition the of Chemical Weapons. PMID:25103280

  18. Solubility of methanol in low-temperature aqueous sulfuric acid and implications for atmospheric particle composition

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    Using traditional Knudsen cell techniques, we find well-behaved Henry's law uptake of methanol in aqueous 45 - 70 wt% H2SO4 solutions at temperatures between 197 and 231 K. Solubility of methanol increases with decreasing temperature and increasing acidity, with an effective Henry's law coefficient ranging from 10(exp 5) - 10(exp 8) M/atm. Equilibrium uptake of methanol into sulfuric acid aerosol particles in the upper troposphere and lower stratosphere will not appreciably alter gas-phase concentrations of methanol. The observed room temperature reaction between methanol and sulfuric acid is too slow to provide a sink for gaseous methanol at the temperatures of the upper troposphere and lower stratosphere. It is also too slow to produce sufficient quantities of soluble reaction products to explain the large amount of unidentified organic material seen in particles of the upper troposphere.

  19. Studies on the adsorption of americium on alumina from aqueous nitric acid-oxalic acid solutions

    SciTech Connect

    Subba Rao, M.; Gaikwad, A.M.; Rao, V.K.; Natarajan, P.R.

    1985-01-01

    This paper reports a study on the adsorption of Am(III) on alumina from oxalic acid-nitric acid solutions. Distribution coefficients for Am(III) on alumina at different oxalic acid-nitric acid concentrations have been determined and optimum conditions for loading and elution of Am from alumina columns have been established. Separation of Am from Pu and the effects of other ions, such as U(VI) and Fe(III), have also been studied. Am and Pu recoveries better than 99.5% were obtained. 3 references, 2 figures, 5 tables.

  20. Reactivity of aminophosphonic acids. Oxidative dephosphonylation of 1-aminoalkylphosphonic acids by aqueous halogens.

    PubMed

    Drabowicz, Józef; Jordan, Frank; Kudzin, Marcin H; Kudzin, Zbigniew H; Stevens, Christian V; Urbaniak, Paweł

    2016-02-01

    The reactions of 1-aminoalkylphosphonic acids with bromine-water, chlorine-water and iodine-water were investigated. The formation of phosphoric(v) acid, as a result of a halogen-promoted cleavage of the Cα-P bond, accompanied by nitrogen release, was observed. The dephosphonylation of 1-aminoalkylphosphonic acids was found to occur quantitatively. In the reactions of 1-aminoalkylphosphonic acids with other halogen-water reagents investigated by (31)P NMR, scission of the Cα-P bond was also observed, the reaction rates being comparable for bromine and chlorine, but much slower for iodine. PMID:26631424

  1. Vine-shoot waste aqueous extract applied as foliar fertilizer to grapevines: Effect on amino acids and fermentative volatile content.

    PubMed

    Sánchez-Gómez, R; Garde-Cerdán, T; Zalacain, A; Garcia, R; Cabrita, M J; Salinas, M R

    2016-04-15

    The aim of this work was to study the influence of foliar applications of different wood aqueous extracts on the amino acid content of musts and wines from Airén variety; and to study their relationship with the volatile compounds formed during alcoholic fermentation. For this purpose, the foliar treatments proposed were a vine-shoot aqueous extract applied in one and two times, and an oak extract which was only applied once. Results obtained show the potential of Airén vine-shoot waste aqueous extracts to be used as foliar fertilizer, enhancing the wine amino acid content especially when they were applied once. Similar results were observed with the aqueous oak extract. Regarding wine fermentative volatile compounds, there is a close relationship between musts and their wines amino acid content allowing us to discuss about the role of proline during the alcoholic fermentation and the generation of certain volatiles. PMID:26616933

  2. ''Pulling'' Nanoparticles into Water: Phase Transfer of Oleic Acid Stabilized Monodisperse Nanoparticles into Aqueous Solutions of alpha-Cyclodextrin

    SciTech Connect

    Wang, Y.; Wong, J.F.; Teng, X.; Lin, X.Z.; Yang, H.

    2003-10-18

    (B204)This paper describes a general method to drastically improve the disparity of oleic acid stabilized nanoparticles in aqueous solutions. We use oleic acid stabilized monodisperse nanoparticles of iron oxides and silver as model systems, and have modified the surface properties of these nanoparticles through the formation of an inclusion complex between surface-bound surfactant molecules and alpha-cyclodextrin (alpha-CD). After the modification, the nanoparticles of both iron oxide and Ag can transfer from hydrophobic solvents, such as hexane, to alpha-CD aqueous phase. The efficiency of the phase transfer to the aqueous solutions depend son the initial alpha-CD concentration. The alpha-CD/oleic acid complex stabilized nanoparticles can be stable for long periods of time in aqueous phase under ambient atmospheric conditions. Transmission electron microscopy (TME), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy, and colorimetric methods have been used in the characterization of these nanoparticles.

  3. Isolation and separation of transplutonium elements from other actinides on ion exchange resins from aqueous and aqueous ethanol solutions of sulfuric acid

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1987-11-01

    The behavior of Am, Cm, Bk, Cf, Es, and other actinides, as well as Zr, on an anion exchange resin and a cation exchange resin in aqueous and aqueous alcohol solutions of sulfuric acid was investigated as a function of the concentration of various components of the solution. It was found that the presence of alcohol in sulfuric acid solutions leads to an increase in the distribution coefficients both on cation exchange resins and on anion exchange resins. The possibility of using ion exchange resins for the concentration and separation of transplutonium elements from U, Np, Pu, Zr, and other elements that form strong complexes with sulfate ions in a wide range of sulfuric acid concentrations was demonstrated.

  4. Sulfate Mineral Formation from Acid-weathered Phyllosilicates: Implications for the Aqueous History of Mars

    NASA Astrophysics Data System (ADS)

    Craig, Patricia; Ming, Douglas; Rampe, Elizabeth

    2014-11-01

    Phyllosilicates on Mars are common in Noachian terrains whereas sulfates are found in the younger Hesperian terrains and suggest alteration under more acidic conditions. Phyllosilicates that formed during the Noachian era would have been exposed to the prevailing acidic conditions during the Hesperian. The purpose of this project is to characterize the effects of acid-weathering on phyllosilicates to better understand the aqueous history of Mars. Nontronite, montmorillonite, and saponite were exposed to H2SO4 solutions at water-rock (WR) ratios of 50 and 25.X-ray diffraction (XRD) patterns of all three acid-treated minerals showed progressive collapse of the phyllosilicate basal spacing with increasing acid concentration. Bassanite formed as an intermediate phase in weathered nontronite and montmorillonite from extracted interlayer Ca. The octahedral cation determined which sulfate formed at high acid concentration: rhomboclase from nontronite, alunogen from montmorillonite, hexahydrite and kieserite from saponite. Gypsum and anhydrite also formed as intermediate phases in nontronite treated at WR=25, showing a change in sulfate hydration state with changing acid concentration (i.e. water activity). Scanning electron microscopy analyses detected phases not identified by XRD. Al-sulfate was found in nontronite weathered at WR=25 and Ca-sulfate in weathered saponite. Near-infrared reflectance spectra of the weathered samples showed decreasing intensity of the hydration/hydroxylation bands and a change or disappearance of metal-OH bands indicating dehydration and dissociation of the interlayers and octahedral layers, respectively, with increased acid weathering.Sulfate mineral formation from acid-weathered phyllosilicates may explain the presence of phyllosilicates and sulfates in close proximity to each other on Mars, such as in Gale Crater. The CheMin XRD instrument on Curiosity may find evidence for acid-weathered phyllosilicates in Mt. Sharp by comparing the 001

  5. Aqueous extracts of Mozambican plants as alternative and environmentally safe acid-base indicators.

    PubMed

    Macuvele, Domingos Lusitaneo Pier; Sithole, Gerre Zebedias Samo; Cesca, Karina; Macuvele, Suzana Lília Pinare; Matsinhe, Jonas Valente

    2016-06-01

    Indicators are substances that change color as the pH of the medium. Many of these substances are dyes of synthetic origin. The mulala plant (Euclea natalensis), which roots are commonly used by rural communities for their oral hygiene, and roseira (Hibiscus rosa-sinensis), an ornamental plant, are abundant in Mozambique. Currently, synthetic acid-base indicators are most commonly used but have environmental implications and, on the other hand, are expensive products, so the demand for natural indicators started. This study investigated the applicability of aqueous extracts of H. rosa-sinensis and E. natalensis as acid-base indicators. Ground on this work, the extracts can be used as acid-base indicators. On the basis of the absorption spectroscopy in both the UV-Vis region and previous studies, it was possible to preliminarily pinpoint anthocyanins and naphthoquinones as responsible for the shifting of colors depending on the pH range of aqueous extracts of H. rosa-sinensis and E. natalensis. These natural indicators are easily accessible, inexpensive, easy to extract, environmentally safe, and locally available. PMID:26936478

  6. Inhibition of gastric acid secretion by the aqueous extract and purified extracts of Stachytarpheta cayennensis.

    PubMed

    Vela, S M; Souccar, C; Lima-Landman, M T; Lapa, A J

    1997-02-01

    Stachytarpheta cayennensis Schauer (Verbenaceae) is used in folk medicine to treat gastric and intestinal disturbances. The freeze-dried aqueous extract of the whole plant tested to rodents up to the dose of 2 g kg-1, p.o., did not produce signs of toxicity. The extract (0.5-2 g kg-1, p.o.) increased the intestinal motility and protected mice against ulcers induced by restraintin-cold, ethanol or indomethacin. Injected into the duodenal lumen the extract inhibited the basal acid secretion as well as that induced by histamine and bethanecol in pylorus-ligated mice. Partition of the aqueous extract in organic solvents yielded semipurified fractions whose antiacid activity guided further chemical purification. All the fractions were chromatographically characterized, the main substances in the active extract being flavonoids and amines; some substances were revealed only under UV light. The most purified active fraction obtained presented a specific activity 5-10 times higher than that detected in the original extract. Data from pharmacological studies indicate that the antiulcer activity of S. cayennensis is related to a specific inhibition of gastric acid secretion. Cholinergic and histaminergic stimulation of acid secretion were similarly reduced by the extracts suggesting inhibition of common steps in both pathways, possibly at the level of histamine release/H2 receptor interaction, or at the proton pump. Whatever the mechanisms involved, the present data confirm the plant effectiveness as antiacid/antiulcer and laxative. PMID:9063095

  7. Thermodynamics of aqueous sodium sulfate from the temperatures 273 K to 373 K and mixtures of aqueous sodium sulfate and sulfuric acid at 298. 15 K

    SciTech Connect

    Hovey, J.K.; Pitzer, K.S. ); Rard, J.A. )

    1991-07-01

    New isopiestic vapor-pressure measurements on the aqueous system {l brace}(1{minus}y)H{sub 2}SO{sub 4}+yNA{sub 2}SO{sub 4}{r brace} along with earlier experimental investigations that span the range from y=0 to y=1 and infinitely dilute to supersaturated molalities have been analyzed in terms of the Pitzer ion-interaction model. Refined ion-interaction parameters for aqueous sodium sulfate valid over the temperature range 273 K to 373 K have been calculated and used for analyzing results for mixtures containing sulfuric acid and sodium sulfate at 298.15 K. Analysis of experimental results for these aqueous mixtures required explicit consideration of the dissociation reaction of bisulfate ion. Previous treatments of aqueous sulfuric acid and subsequently the bisulfate dissociation equilibrium valid in the range 273 K to 343 K were employed as a first approximation in representing the mixed solutions. Two sets of Pitzer ion-interaction parameters are presented for (sodium sulfate + sulfuric acid). The validity of the first set is limited in ionic strength and molality to saturated solutions of pure aqueous sodium sulfate (4 mol{center dot}kg{sup {minus}1}). The second set of parameters corresponds to a slightly less precise representation but is valid over the entire range of experimental results considered. Both sets of parameters provide a more complete description of pure sulfuric acid solutions because of the removal of various redundancies of ion-interaction parameters. The specific ion-interaction terms used and the overall fitting procedure are described as well as selected examples of relevant thermodynamic calculations in the mixed system Na{sub 2}SO{sub 4}-H{sub 2}SO{sub 4}-H{sub 2}O. 33 refs., 6 figs., 5 tabs.

  8. Thermodynamics of aqueous sodium sulfate from the temperatures 273 K to 373 K and mixtures of aqueous sodium sulfate and sulfuric acid at 298.15 K

    SciTech Connect

    Hovey, J.K.; Pitzer, K.S.; Rard, J.A.

    1991-07-01

    New isopiestic vapor-pressure measurements on the aqueous system {l_brace}(1{minus}y)H{sub 2}SO{sub 4}+yNA{sub 2}SO{sub 4}{r_brace} along with earlier experimental investigations that span the range from y=0 to y=1 and infinitely dilute to supersaturated molalities have been analyzed in terms of the Pitzer ion-interaction model. Refined ion-interaction parameters for aqueous sodium sulfate valid over the temperature range 273 K to 373 K have been calculated and used for analyzing results for mixtures containing sulfuric acid and sodium sulfate at 298.15 K. Analysis of experimental results for these aqueous mixtures required explicit consideration of the dissociation reaction of bisulfate ion. Previous treatments of aqueous sulfuric acid and subsequently the bisulfate dissociation equilibrium valid in the range 273 K to 343 K were employed as a first approximation in representing the mixed solutions. Two sets of Pitzer ion-interaction parameters are presented for (sodium sulfate + sulfuric acid). The validity of the first set is limited in ionic strength and molality to saturated solutions of pure aqueous sodium sulfate (4 mol{center_dot}kg{sup {minus}1}). The second set of parameters corresponds to a slightly less precise representation but is valid over the entire range of experimental results considered. Both sets of parameters provide a more complete description of pure sulfuric acid solutions because of the removal of various redundancies of ion-interaction parameters. The specific ion-interaction terms used and the overall fitting procedure are described as well as selected examples of relevant thermodynamic calculations in the mixed system Na{sub 2}SO{sub 4}-H{sub 2}SO{sub 4}-H{sub 2}O. 33 refs., 6 figs., 5 tabs.

  9. ESTIMATION OF HYDROLYSIS RATE CONSTANTS OF CARBOXYLIC ACID ESTER AND PHOSPHATE ESTER COMPOUNDS IN AQUEOUS SYSTEMS FROM MOLECULAR STRUCTURE BY SPARC

    EPA Science Inventory

    SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid ester and phosphate ester compounds in aqueous non- aqueous and systems strictly from molecular structure. The energy diffe...

  10. The dissolution of calcite in aqueous acid: The influence of humic species

    SciTech Connect

    Compton, R.G.; Sanders, G.H.W. )

    1993-07-01

    The kinetics of proton-induced calcite dissolution in aqueous solution in the presence of humic acids and their sodium salts are reported. In equilibrated acid solutions (pH <4) there is no inhibition by humic material and dissolution proceeds at a rate simply determined by the solution pH. Contrastingly the sodium salts of humic acids were found to have a significant inhibitory effect on the acid catalyzed dissolution. This was quantified using a novel channel flow cell experiment which employed two electrodes, the upstream of which was used to inject protons into a neutral solution, which also contained sodium salts of humic acid, via electrolytic oxidation of dissolved hydroquinone. The two electrodes were located immediately upstream and downstream of a calcite crystal so that the proton injection served to dissolve the calcite in the (inhibiting) presence of humic salts unequilibrated with the solution pH. The amount of H[sup +] which survived passage to the downstream detector'' electrode was used to quantify the rate of dissolution and hence the inhibitory effects of the humic acid. The latter were found to operate in a manner not inconsistent with Langmuirian adsorption.

  11. Adsorption of naphthalene from aqueous solution onto fatty acid modified walnut shells.

    PubMed

    Zhu, Mijia; Yao, Jun; Dong, Lifu; Sun, Jingjing

    2016-02-01

    The removal of polycyclic aromatic hydrocarbons (PAHs) from aqueous solution is challenging to environmental technologists. Agricultural waste is apparently the most attractive materials in removing PAHs because of its abundance, renewability, and economic advantage. The adsorption of PAHs (e.g., naphthalene) onto walnut shell (WNS) and its fatty acid (e.g., capric acid, lauric acid, palmitic acid, and oleic acid)-modified equivalent were investigated in this work to develop low-cost biosorbents for hydrophobic organic compounds. Compared with other modified sorbents, oleic acid graftted walnut shell (OWNS) showed the maximum partition coefficient (4330 ± 8.8 L kg(-1)) because of its lowest polarity and highest aromaticity. The adsorption capacity (7210 μg g(-1)) of OWNS at the temperature of 298 K was observed for an initial naphthalene concentration of 25 mg L(-1) with contact time of 40 h, sorbent dosage of 1 g L(-1), and in neutral condition. Furthermore, the regeneration capability of OWNS implied that it was a promising biosorbent for naphthalene removal. PMID:26517393

  12. Stability of rare-earth complexes with acetylacetone and methaccrylic acid in aqueous solution

    SciTech Connect

    Panyushkin, V.T.; Akhrimenko, N.V.

    1995-09-01

    The stability constants for lanthanide (Ln) complexes with methacrylic acid (HL) (log{beta}{sub LnL}{sup Ln}), acetylacetone (HAA) (log{beta}{sub Ln(AA){sub 3}}{sup Ln}), and mixed-ligand complexes (log{beta}{sub LnL(AA){sub 2}}{sup Ln}), [Ln(III)=La, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Yb, Lu] in aqueous solution are determined by potentiometric titration at 25{degrees}C and {mu}=0.1 (KCl). A nonmonotonous change in the stability constants with an increase in the atomic number number of the rare-earth metal is found to occur.

  13. Acridine-based complex as amino acid anion fluorescent sensor in aqueous solution

    NASA Astrophysics Data System (ADS)

    Dai, Yanpeng; Xu, Kuoxi; Li, Qian; Wang, Chaoyu; Liu, Xiaoyan; Wang, Peng

    2016-03-01

    Novel acridine-based fluorescence sensors containing alaninol ligands, L1 and D1, were designed and synthesized. The structure of the compound was characterized by IR, 1H NMR, 13C NMR, MS spectra. L1 and D1 possess efficient Cu2 + cation ON-OFF selective signaling behavior based on ligand-to-metal binding mechanism at physiological pH condition. Additionally, the L1-Cu(II) and D1-Cu(II) complexes could further serve as reversible OFF-ON signaling sensing ensemble to allow ratiometric response to amino acid anion in aqueous solution.

  14. Laboratory photochemical processing of aqueous aerosols: formation and degradation of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Pavuluri, C. M.; Kawamura, K.; Mihalopoulos, N.; Swaminathan, T.

    2015-07-01

    To better understand the photochemical processing of dicarboxylic acids and related polar compounds, we conducted batch UV irradiation experiments on two types of aerosol samples collected from India, which represent anthropogenic (AA) and biogenic (BA) aerosols, for time periods of 0.5 to 120 h. The irradiated samples were analyzed for molecular compositions of diacids, oxoacids and α-dicarbonyls. The results show that photochemical degradation of oxalic (C2), malonic (C3) and other C8-C12 diacids overwhelmed their production in aqueous aerosols, whereas succinic acid (C4) and C5-C7 diacids showed a significant increase (ca. 10 times) during the course of irradiation experiments. The photochemical formation of oxoacids and α-dicarbonyls overwhelmed their degradation during the early stages of experiment except for ω-oxooctanoic acid (ωC8), which showed a similar pattern to that of C4. We also found a gradual decrease in the relative abundance of C2 to total diacids and an increase in the relative abundance of C4 during prolonged experiment. Based on the changes in concentrations and mass ratios of selected species with the irradiation time, we hypothesize that iron-catalyzed photolysis of C2 and C3 diacids controls their concentrations in Fe-rich atmospheric waters, whereas photochemical formation of C4 diacid (via ωC8) is enhanced with photochemical processing of aqueous aerosols in the atmosphere. This study demonstrates that the ambient aerosols contain abundant precursors that produce diacids, oxoacids and α-dicarbonyls, although some species such as oxalic acid decompose extensively during an early stage of photochemical processing.

  15. The effect of fatty acid surfactants on the uptake of ozone to aqueous halogenide particles

    NASA Astrophysics Data System (ADS)

    Rouvière, A.; Ammann, M.

    2010-12-01

    The reactive uptake of ozone to deliquesced potassium iodide aerosol particles coated with linear saturated fatty acids (C9, C12, C15, C18 and C20) was studied. The experiments were performed in an aerosol flow tube at 293 K and atmospheric pressure. The uptake coefficient on pure deliquesced KI aerosol was γ = (1.10±0.20)×10-2 at 72-75% relative humidity. In presence of organic coatings, the uptake coefficient decreased significantly for long straight chain surfactants (≥C15), while it was only slightly reduced for the short ones (C9, C12). We linked the kinetic results to the monolayer properties of the surfactants, and specifically to the expected phase state of the monolayer formed (liquid expanded or liquid condensed state). The results showed a decrease of the uptake coefficient by 30% for C12, 85% for C15 and 50% for C18 in presence of a monolayer of a fatty acid at the equilibrium spreading pressure at the air/water interface. The variation among C12, C15 and C18 follows the density of the monolayer at equilibrium spreading pressure, which is highest for the C15 fatty acid. We also investigated the effect of organic films to mixed deliquesced aerosol composed of a variable mixture of KI and NaCl, which allowed determining the resistance exerted to O3 at the aqueous surface by the two longer chained surfactants pentadecanoic acid (C15) and stearic acid (C18). For these, the probability that a molecule hitting the surface is actually transferred to the aqueous phase underneath was βC15=6.8×10-4 and βC18 = 3.3×10-4, respectively. Finally, the effect of two-component coatings, consisting of a mixture of long and short chained surfactants, was studied qualitatively.

  16. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part I. Regeneration of Amine-Carboxylic Acid Extracts

    SciTech Connect

    Poole, L.J.; King, C.J.

    1990-03-01

    Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, succinic acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility of lactic acid and the tendency of the acid to self-associate. The separate recovery of ammonia and acid gases from sour waters can be achieved by combining steam-stripping of the acid gases with simultaneous removal of ammonia by extraction with a liquid cation exchanger. The use of di-2,4,4-trimethylpentyl phosphinic acid as the liquid cation exchanger is explored in this work. Batch extraction experiments were carried out to measure the equilibrium distribution ratio of ammonia between an aqueous buffer solution and an organic solution of the phosphinic acid (0.2N) in Norpar 12. The concentration

  17. Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution

    NASA Astrophysics Data System (ADS)

    Wang, Le; Mu, Wen-ning; Shen, Hong-tao; Liu, Shao-ming; Zhai, Yu-chun

    2015-05-01

    A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaCl2 aqueous solution, liquid-to-solid (L/S) ratio, leaching temperature, and leaching time, were investigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min-1, a CaCl2 aqueous solution concentration of 400 g·L-1, a liquid-to-solid mass ratio of 7:1, a leaching temperature of 80°C, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.

  18. Formation of isomers of anionic hemiesters of sugars and carbonic acid in aqueous medium.

    PubMed

    Dos Santos, Vagner B; Vidal, Denis T R; Francisco, Kelliton J M; Ducati, Lucas C; do Lago, Claudimir L

    2016-06-16

    Hemiesters of carbonic acid can be freely formed in aqueous media containing HCO3(-)/CO2 and mono- or poly-hydroxy compounds. Herein, (13)C NMR spectroscopy was used to identify isomers formed in aqueous solutions of glycerol (a prototype compound) and seven carbohydrates, as well as to estimate the equilibrium constant of formation (Keq). Although both isomers are formed, glycerol 1-carbonate corresponds to 90% of the product. While fructose and ribose form an indistinct mixture of isomers, the anomers of d-glucopyranose 6-carbonate correspond to 74% of the eight isomers of glucose carbonate that were detected. The values of Keq for the disaccharides sucrose (4.3) and maltose (4.2) are about twice the values for the monosaccharides glucose (2.0) and fructose (2.3). Ribose (Keq = 0.89)-the only sugar without a significant concentration of a species containing a -CH2OH group in an aqueous solution-resulted in the smallest Keq. On the basis of the Keq value and the concentrations of HCO3(-) and glucose in blood, one can anticipate a concentration of 2-4 µmol L(-1) for glucose 6-carbonate, which corresponds to ca. of 10% of its phosphate counterpart (glucose 6-phosphate). PMID:27111726

  19. [Changes in the collagen amino acid composition of calf skin after gamma-irradiation in an aqueous solution].

    PubMed

    Duzhenkova, N A; Savich, A V

    1983-01-01

    A study was made of the amino acid composition of calf skin collagen after gamma-irradiation (60Co) of 2.5 X 10(-6) M aerated aqueous protein solution within the dose range from 30 to 2000 Gy. The radiosensitivity of amino acid residues was compared. PMID:6657935

  20. Competitive adsorption of boric acid and chromate onto alumina in aqueous solutions.

    PubMed

    Demetriou, A; Pashalidis, I

    2014-01-01

    The competitive adsorption of boric acid and chromate from aqueous solutions by alumina has been investigated by spectrophotometry at pH 8, ionic strength = 0.0, 0.1 and 1.0 M NaClO4, T = 22 ± 3 °C and under normal atmospheric conditions. The experimental data show that addition of excess boric acid in the system leads to the increase of Cr(VI) concentration in solution, indicating the replacement of adsorbed chromate by boron on the alumina surface. Data evaluation results in the determination of the competition reaction constant and the formation constant of the Cr(VI) surface complexes, which are logKCr(VI)-B(III) = -3.5 ± 0.2 and logβ*Cr = 7.6 ± 0.3, respectively. PMID:24473309

  1. 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.

  2. Electrochemistry of poly(vinylferrocene) modified electrodes in aqueous acidic media

    NASA Astrophysics Data System (ADS)

    Issa, Touma B.; Singh, Pritam; Baker, Murray V.

    A cyclic voltammetric study of the electrochemistry and chemical stability of the poly(vinylferrocene) (PVFc) redox couple, coated on a gold substrate, in aqueous solutions of H 2SO 4, HClO 4 and HCl was carried out. It was found that the anodic peak potential ( Epa) did not depend on the acid concentration in the range (1.0 × 10 -2 to 1.0 × 10 -7 mol L -1). However, the Epa values shifted linearly to less positive potentials when investigated in more concentrated acid solutions in the range 1-5 mol L -1. The slope of the Epa versus acid concentration graph was found to be in the order H 2SO 4 > HCl > HClO 4. In this regard PVFc behaved very similar to 1,1'-bis(11-mercaptoundecyl)ferrocene (Fc(C 11SH) 2) except for its chemical stability. In H 2SO 4 media the PVFc was found to be much less stable than 1,1'-Fc(C 11SH) 2. The dependence of Epa on acid concentration could be used to monitor state of charge of lead-acid batteries. However, for this application Fc(C 11SH) 2 would be a better choice because of its superior chemical stability.

  3. Influence of charge exchange in acidic aqueous and alcoholic titania dispersions on viscosity.

    PubMed

    Rosenholm, Jarl B; Dahlsten, Per

    2015-12-01

    Charging effects resulting from adsorption of acid, acid anions, and protons on titania (anatase) surfaces in anhydrous or mixed alcohol-water dispersions is summarized. The suddenly enhanced conductivity as compared to titania-free solutions has previously been modeled and explained as surface-induced electrolytic dissociation (SIED) of weak acids. This model and recently published results identifying concurrent surface-induced liquid (solvent) dissociation (SILD) are evaluated with experimentally determined conductivity and pH of solutions, zeta-potential of particles, and viscosity of dispersions. Titania (0-25wt%)-alcohol (methanol, ethanol, and propanol) dispersions mixed with (0-100wt%) water were acidified with oxalic, phosphoric, and sulfuric acids. It was found that the experimental results could in many cases be condensed to master curves representing extensive experimental results. These curves reveal that major properties of the systems appear within three concentration regions were different mechanisms (SILD, surface-induced liquid dissociation; SIAD, surface-induced acid dissociation) and charge rearrangement were found to be simultaneously active. In particular, zeta-potential - pH and viscosity - pH curves are in acidified non-polar solvents mirror images to those dependencies observed in aqueous dispersions to which hydroxyl is added. The results suggest that multiple dispersion and adsorption equilibria should be considered in order to characterize the presented exceptionally extensive and complex experimental results. PMID:26520241

  4. Stable Isotope Characteristics of Jarosite: The Acidic Aqueous History of Mars

    NASA Technical Reports Server (NTRS)

    Earl, Lyndsey D.

    2005-01-01

    The Mars Rover Opportunity found jarosite (Na(+) or K(+))Fe3SO4(OH)6 at the Meridiani Planum site. This mineral forms from the evaporation of an aqueous acidic sulfate brine. Oxygen isotope compositions may characterize formation conditions but subsequent isotope exchange may have occurred between the sulfate and hydroxide of jarosite and water. The rate of oxygen isotope exchange depends on the acidity and temperature of the brine, but it has not been investigated in detail. We performed laboratory experiments to determine the rate of oxygen isotope exchange under varying acidities and temperatures to learn more about this process. Barium sulfate samples were precipitated weekly from acidic sodium sulfate brines. The oxygen isotope composition of the precipitated sulfate was obtained using a Finnigan MAT253 Isotope Ratio Mass-Spectrometer. The results show that water was trapped in barium sulfate during precipitation. Trapped water may exchange with sulfate when exposed to high temperatures, thus changing the isotope composition of sulfate and the observed fractionation factor of oxygen isotope exchange between sulfate and water. The results of our research will contribute to the understanding of oxygen isotope exchange rates between water and sulfate under acidic conditions and provide experimental knowledge for the dehydration of barium sulfate samples.

  5. Sulfate Formation From Acid-Weathered Phylosilicates: Implications for the Aqueous History of Mars

    NASA Technical Reports Server (NTRS)

    Craig, P. I.; Ming, D. W.; Rampe, E. B.

    2014-01-01

    Most phyllosilicates on Mars are thought to have formed during the planet's earliest Noachian era, then Mars underwent a global change making the planet's surface more acidic [e.g. 1]. Prevailing acidic conditions may have affected the already existing phyllosilicates, resulting in the formation of sulfates. Both sulfates and phyllosilicates have been identified on Mars in a variety of geologic settings [2] but only in a handful of sites are these minerals found in close spatial proximity to each other, including Mawrth Vallis [3,4] and Gale Crater [5]. While sulfate formation from the acidic weathering of basalts is well documented in the literature [6,7], few experimental studies investigate sulfate formation from acid-weathered phyllosilicates [8-10]. The purpose of this study is to characterize the al-teration products of acid-weathered phyllosilicates in laboratory experiments. We focus on three commonly identified phyllosilicates on Mars: nontronite (Fe-smectite), saponite (Mg-smectite), and montmorillonite (Al-smectite) [1, and references therein]. This information will help constrain the formation processes of sulfates observed in close association with phyllosilicates on Mars and provide a better understanding of the aqueous history of such regions as well as the planet as a whole.

  6. Dissolution of nickel ferrite in aqueous solutions containing oxalic acid and ferrous salts

    SciTech Connect

    Figueroa, C.A.; Sileo, E.E.; Morando, P.J.; Blesa, M.A.

    2000-05-15

    The dissolution of nickel ferrite in oxalic acid and in ferrous oxalate-oxalic acid aqueous solution was studied. Nickel ferrite was synthesized by thermal decomposition of a mixed tartrate; the particles were shown to be coated with a thin ferric oxide layer. Dissolution takes place in two stages, the first one corresponding to the dissolution of the ferric oxide outer layer and the second one being the dissolution of Ni{sub 1.06}Fe{sub 1.96}O{sub 4}. The kinetics of dissolution during this first stage is typical of ferric oxides: in oxalic acid, both a ligand-assisted and a redox mechanism operates, whereas in the presence of ferrous ions, redox catalysis leads to a faster dissolution. The rate dependence on both oxalic acid and on ferrous ion is described by the Langmuir-Hinshelwood equation. In the second stage, Langmuir-Hinshelwood kinetics also describes the dissolution of iron and nickel from nickel ferrite. It may be concluded that oxalic acid operates to dissolve iron, and the ensuing disruption of the solid framework accelerates the release of nickel.

  7. Sunlight-initiated Chemistry of Aqueous Pyruvic Acid: Building Complexity in the Origin of Life

    NASA Astrophysics Data System (ADS)

    Griffith, Elizabeth C.; Shoemaker, Richard K.; Vaida, Veronica

    2013-10-01

    Coupling chemical reactions to an energy source is a necessary step in the origin of life. Here, we utilize UV photons provided by a simulated sun to activate aqueous pyruvic acid and subsequently prompt chemical reactions mimicking some of the functions of modern metabolism. Pyruvic acid is interesting in a prebiotic context due to its prevalence in modern metabolism and its abiotic availability on early Earth. Here, pyruvic acid (CH3COCOOH, a C3 molecule) photochemically reacts to produce more complex molecules containing four or more carbon atoms. Acetoin (CH3CHOHCOCH3), a C4 molecule and a modern bacterial metabolite, is produced in this chemistry as well as lactic acid (CH3CHOHCOOH), a molecule which, when coupled with other abiotic chemical reaction pathways, can provide a regeneration pathway for pyruvic acid. This chemistry is discussed in the context of plausible environments on early Earth such as near the ocean surface and atmospheric aerosol particles. These environments allow for combination and exchange of reactants and products of other reaction environments (such as shallow hydrothermal vents). The result could be a contribution to the steady increase in chemical complexity requisite in the origin of life.

  8. Ulcer healing activity of Mumijo aqueous extract against acetic acid induced gastric ulcer in rats

    PubMed Central

    Shahrokhi, Nader; Keshavarzi, Zakieh; Khaksari, Mohammad

    2015-01-01

    Objective: Gastric ulcer is an important clinical problem, chiefly due to extensive use of some drugs. The aim was to assess the activity of Mumijo extract (which is used in traditional medicine) against acetic acid induced gastric ulcer in rats. Materials and Methods: The aqueous extract of Mumijo was prepared. Animals were randomly (n = 10) divided into four groups: Control, sham-operated group (received 0.2 ml of acetic acid to induce gastric ulcer), Mumijo (100 mg/kg/daily) were given for 4 days postacetic acid administration, and ranitidine group (20 mg/kg). The assessed parameters were pH and pepsin levels (by Anson method) of gastric contents and gastric histopathology. Ranitidine was used as reference anti-ulcer drug. Results: The extract (100 mg/kg/daily, p.o.) inhibited acid acetic-induced gastric ulceration by elevating its pH versus sham group (P < 0.01) and decreasing the pepsin levels compared to standard drug, ranitidine (P < 0.05). The histopathology data showed that the treatment with Mumijo extract had a significant protection against all mucosal damages. Conclusion: Mumijo extract has potent antiulcer activity. Its anti-ulcer property probably acts via a reduction in gastric acid secretion and pepsin levels. The obtained results support the use of this herbal material in folk medicine. PMID:25709338

  9. Adsorption of Crystal violet on raw and acid-treated montmorillonite, K10, in aqueous suspension.

    PubMed

    Sarma, Gautam Kumar; Sen Gupta, Susmita; Bhattacharyya, Krishna G

    2016-04-15

    Crystal violet is used as a dye in cotton and silk textiles, paints and printing ink. The dye is hazardous and exposure to it may cause permanent injury to the cornea and conjunctiva including permanent blindness, and in severe cases, may lead to respiratory and kidney failure. The present work describes removal of Crystal violet from aqueous solution by adsorption on raw and acid-treated montmorillonite, K10. The clay mineral was treated with 0.25 and 0.50 M sulfuric acid and the resulting materials were characterized by XRD, zeta potential, SEM, FTIR, cation exchange capacity, BET surface area and pore volume measurements. The influences of pH, interaction time, adsorbent amount, and temperature on adsorption were monitored and explained on the basis of physico-chemical characteristics of the materials. Basic pH generally favors adsorption but considerable removal was possible even under neutral conditions. Adsorption was very rapid and equilibrium could be attained in 180 min. The kinetics conformed to second order model. Langmuir monolayer adsorption capacity of raw montmorillonite K10 was 370.37 mg g(-1) whereas 0.25 M and 0.50 M acid treated montmorillonite K10 had capacities of 384.62 and 400.0 mg g(-1) respectively at 303 K. Adsorption was exothermic and decreased in the temperature range of 293-323 K. Thermodynamically, the process was spontaneous with Gibbs energy decreasing with rise in temperature. The results suggest that montmorillonite K10 and its acid treated forms would be suitable for removing Crystal violet from aqueous solution. PMID:26866669

  10. Bile acid-surfactant interactions at the liquid crystal/aqueous interface.

    PubMed

    He, Sihui; Liang, Wenlang; Cheng, Kung-Lung; Fang, Jiyu; Wu, Shin-Tson

    2014-07-14

    The interaction between bile acids and surfactants at interfaces plays an important role in fat digestion. In this paper, we study the competitive adsorption of cholic acid (CA) at the sodium dodecyl sulfate (SDS)-laden liquid crystal (LC)/aqueous interface formed with cyanobiphenyl (nCB, n = 5-8) and the mixture of 5CB with 4-(4-pentylcyclohexyl)benzonitrile (5PCH). We find that the critical concentration of CA required to displace SDS from the interface linearly decreases from 160 μM to 16 μM by reducing the alkyl chain length of nCB from n = 8 to n = 5 and from 16 μM to 1.5 μM by increasing the 5PCH concentration from 0 wt% to 19 wt% in the 5PCH-5CB binary mixture. Our results clearly demonstrate that the sensitivity of 5PCH-5CB mixtures for monitoring the interaction between CA and SDS at the LC/aqueous interface can be increased by one order of magnitude, compared to 5CB. PMID:24825535

  11. EXAFS study of the speciation of protactinium(V) in aqueous hydrofluoric acid solutions.

    PubMed

    De Sio, Stéphanie M; Wilson, Richard E

    2014-12-01

    The speciation of protactinium(V) in hydrofluoric acid (HF) solutions was studied using X-ray absorption spectroscopy. Extended X-ray absorption fine structure measurements were performed on an aqueous solution of 0.05 M protactinium(V) with various HF concentrations ranging from 0.5 to 27 M in order to probe the protactinium coordination sphere with respect to the identity and number of coordinating ligands. The resulting fits to the spectra suggest the presence of an eight-coordinate homoleptic fluoro complex in highly concentrated fluoride solutions (27 M), with equilibrium between seven- and eight-coordinate fluoro complexes at moderate acidities, and in more dilute solutions, results indicate that one water molecule is likely to replace a fluoride in the first coordination sphere, at a distance of 2.54-2.57 Å. Comparisons of this chemistry with group V metals, niobium and tantalum, are presented, and the potential implications for these results on the hydrolytic behavior of protactinium in aqueous systems are discussed. PMID:25389749

  12. 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.

  13. Extraction and isolation of TPE from other elements on ion exchangers in aqueous and aqueous-organic solutions of phosphoric acid

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1988-07-01

    The behavior of Am-Es and other actinides on anion and cation exchange resins in aqueous and aqueous-organic solutions of phosphoric acid has been studied in a wide range of concentration of various components of the solution. The sorptivity of transplutonium elements (TPE) on anion exchangers from dilute H/sub 3/PO/sub 4/ with a concentration less than or equal to 1 M in presence of organic solvents (alcohols, ketones, etc.) and on cation exchangers from concentrated H/sub 3/PO/sub 4/ has been found to be significant. The possibility of use of phosphoric acid solutions for isolation of TPE from Th, Pa, U, Np, Pu, and Zr and separation of TPE in different oxidation states in presence of a high-purity oxidant has been shown.

  14. Permeability of acetic acid through organic films at the air-aqueous interface.

    PubMed

    Gilman, Jessica B; Vaida, Veronica

    2006-06-22

    Recent field studies of collected aerosol particles, both marine and continental, show that the outermost layers contain long-chain (C >or= 18) organics. The presence of these long-chain organics could impede the transport of gases and other volatile species across the interface. This could effect the particle's composition, lifetime, and heterogeneous chemistry. In this study, the uptake rate of acetic acid vapor across a clean interface and through films of long-chain organics into an aqueous subphase solution containing an acid-base indicator (bromocresol green) was measured under ambient conditions using visible absorption spectroscopy. Acetic acid is a volatile organic compound (VOC) and is an atmospherically relevant organic acid. The uptake of acetic acid through single-component organic films of 1-octadecanol (C(18)H(38)O), 1-triacontanol (C(30)H(62)O), cis-9-octadecen-1-ol (C(18)H(36)O), and nonacosane (C(29)H(60)) in addition to two mixed films containing equimolar 1-triacontanol/nonacosane and equimolar 1-triacontanol/cis-9-octadecen-1-ol was determined. These species represent long-chain organic compounds that reside at the air-aqueous interface of atmospheric aerosols. The cis-9-octadecen-1-ol film had little effect on the net uptake rate of acetic acid vapor into solution; however, the uptake rate was reduced by almost one-half by an interfacial film of 1-triacontanol. The measured uptake rates were used to calculate the permeability of acetic acid through the various films which ranged from 1.5 x 10(-3) cm s(-1) for 1-triacontanol, the least permeable film, to 2.5 x 10(-2) cm s(-1) for cis-9-octadecen-1-ol, the most permeable film. Both mixed films had permeabilities that were between that of the single-component films comprising the mixture. This shows that the permeability of a mixed film may not be solely determined by the most permeable species in the mixture. The permeabilities of all the films studied here are discussed in relation to their

  15. Sulphur-doped silica fibres

    SciTech Connect

    Gerasimova, V I; Rybaltovskii, A O; Chernov, P V; Mashinsky, V M; Sazhin, O D; Medvedkov, O I; Rybaltovsky, A A; Khrapko, R R

    2003-01-31

    An optical fibre with low optical losses is manufactured from a sulphur-doped quartz glass. Optical absorption spectra are measured for various parts of the fibre core. Most of the bands of these spectra are assigned to oxygen-deficient centres and colour centres containing sulphur atoms. The photosensitivity of glasses exposed to laser radiation at wavelengths of 193 and 244 nm is investigated to estimate the possibility of their application for producing photorefracting devices. A Bragg grating of the refractive index with {Delta}n = 7.8 x 10{sup -4} is written in a sulphur-doped silica fibre. (fibre optics)

  16. Reactivity of alanylalanine diastereoisomers in neutral and acid aqueous solutions: a versatile stereoselectivity.

    PubMed

    Plasson, Raphaël; Tsuji, Maika; Kamata, Masazumi; Asakura, Kouichi

    2011-10-01

    A good comprehension of the reactivity of peptides in aqueous solution is fundamental in prebiotic chemistry, namely for understanding their stability and behavior in primitive oceans. Relying on the stereoselectivity of the involved reactions, there is a huge interest in amino acid derivatives for explaining the spontaneous emergence of homochirality on primitive Earth. The corresponding kinetic and thermodynamic parameters are however still poorly known in the literature. We studied the reactivity of alanylalanine in acidic to neutral conditions as a model system. The hydrolysis into amino acids, the epimerization of the N-terminal residue, and the cyclization into diketopiperazine could be successfully identified and studied. This kinetic investigation highlighted interesting behaviors. Complex mechanisms were observed in very acidic conditions. The relative kinetic stability of the diastereoisomers of the dipeptide is highly dependent of the pH, with the possibility to dynamically destabilize the thermodynamically more stable diastereoisomers. The existence of the cyclization of dipeptides adds complexity to the system. On one hand it brings additional stereoselectivities; on the other hand fast racemization of heterochiral dipeptides is obtained. PMID:21562847

  17. Effects of precursor concentration and acidic sulfate in aqueous glyoxal-OH radical oxidation and implications for secondary organic aerosol.

    PubMed

    Tan, Yi; Perri, Mark J; Seitzinger, Sybil P; Turpin, Barbara J

    2009-11-01

    Previous experiments demonstrated that aqueous OH radical oxidation of glyoxal yields low-volatility compounds. When this chemistry takes place in clouds and fogs, followed by droplet evaporation (or if it occurs in aerosol water), the products are expected to remain partially in the particle phase, forming secondary organic aerosol (SOA). Acidic sulfate exists ubiquitously in atmospheric water and has been shown to enhance SOA formation through aerosol phase reactions. In this work, we investigate how starting concentrations of glyoxal (30-3000 microM) and the presence of acidic sulfate (0-840 microM) affect product formation in the aqueous reaction between glyoxal and OH radical. The oxalic acid yield decreased with increasing precursor concentrations, and the presence of sulfuric acid did not alter oxalic acid concentrations significantly. A dilute aqueous chemistry model successfully reproduced oxalic acid concentrations, when the experiment was performed at cloud-relevant concentrations (glyoxal <300 microM), but predictions deviated from measurements at increasing concentrations. Results elucidate similarities and differences in aqueous glyoxal chemistry in clouds and in wet aerosols. They validate for the first time the accuracy of model predictions at cloud-relevant concentrations. These results suggest that cloud processing of glyoxal could be an important source of SOA. PMID:19924930

  18. Degradation of hydroxycinnamic acid mixtures in aqueous sucrose solutions by the Fenton process.

    PubMed

    Nguyen, Danny M T; Zhang, Zhanying; Doherty, William O S

    2015-02-11

    The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA), and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) were studied by the Fenton oxidation process. Central composite design and multiresponse surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was a <0.01% loss of sucrose in all reactions. The optimal values of the process parameters for a 200 mg/L HCA mixture in water (pH 4.73, 25.15 °C) and sucrose solution (13 mass %, pH 5.39, 35.98 °C) were 77% and 57%, respectively. Regression analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose and coprecipitated with lepidocrocite, an iron oxyhydroxide. PMID:25585639

  19. Sulphur tales from the early Archean world

    NASA Astrophysics Data System (ADS)

    Montinaro, A.; Strauss, H.

    2016-07-01

    Sedimentary and magmatic rocks and their distinct sulphur isotopic signatures indicate the sources and processes of sulphur cycling, in particular through the analysis of all four stable sulphur isotopes (32S, 33S, 34S and 36S). Research over the past 15 years has substantially advanced our understanding of sulphur cycling on the early Earth, most notably through the discovery of mass-independently fractionated sulphur isotopic signatures. A strong atmospheric influence on the early Archean global sulphur cycle is apparent, much in contrast to the modern world. Diverse microbially driven sulphur cycling is clearly discernible, but its importance for Earth surface environments remains to be quantified.

  20. Marine sulphur emissions

    PubMed Central

    Liss, P. S.; Hatton, A. D.; Malin, G.; Nightingale, P. D.; Turner, S. M.

    1997-01-01

    The principal volatile sulphur species found in seawater are dimethyl sulphide (DMS), carbonyl sulphide (COS) and carbon disulphide (CS2. Of these, DMS is the most abundant and widespread in its distribution. The predominant oceanic source of DMS is dimethylsulphonioproprionate (DMSP), a compatible solute synthesized by phytoplankton for osmoregulation and/or cryoprotection. Not all species have the same ability to form DMSP; for example, diatoms generally produce little, whereas prymnesiophytes and some dinoflagellates make significantly larger amounts. Much of the release of DMSP and DMS to the water occurs on death or through predation of the plankton. Our recent field data strongly suggest that oxidation of DMS to dimethyl sulphoxide (DMSO) is an important process in the water column, and it is clear that considerable internal cycling in the DMSP/DMS/DMSO system occurs in the euphotic zone. A fraction of the DMS crosses the sea surface and enters the atmosphere where it is oxidized by radicals such OH and NO3 to form products such as methanesulphonate (MSA), DMSO and non-sea salt sulphate (NSSS) particles. These particles are the main source of cloud condensation nuclei (CCN) over oceanic areas remote from land.

  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. Volatility and oxidative aging of aqueous maleic acid aerosol droplets and the dependence on relative humidity.

    PubMed

    Dennis-Smither, Benjamin J; Marshall, Frances H; Miles, Rachael E H; Preston, Thomas C; Reid, Jonathan P

    2014-07-31

    The microphysical structure and heterogeneous oxidation by ozone of single aerosol particles containing maleic acid (MA) has been studied using aerosol optical tweezers and cavity enhanced Raman spectroscopy. The evaporation rate of MA from aqueous droplets has been measured over a range of relative humidities and the pure component vapor pressure determined to be (1.7 ± 0.2) × 10(-3) Pa. Variation in the refractive index (RI) of an aqueous MA droplet with relative humidity (RH) allowed the subcooled liquid RI of MA to be estimated as 1.481 ± 0.001. Measurements of the hygroscopic growth are shown to be consistent with equilibrium model predictions from previous studies. Simultaneous measurements of the droplet composition, size, and refractive index have been made during ozonolysis at RHs in the range 50-80%, providing insight into the volatility of organic products, changes in the droplet hygroscopicity, and optical properties. Exposure of the aqueous droplets to ozone leads to the formation of products with a wide range of volatilities spanning from involatile to volatile. Reactive uptake coefficients show a weak dependence on ozone concentration, but no dependence on RH or salt concentration. The time evolving RI depends significantly on the RH at which the oxidation proceeds and can even show opposing trends; while the RI increases with ozone exposure at low relative humidity, the RI decreases when the oxidation proceeds at high relative humidity. The variations in RI are broadly consistent with a framework for predicting RIs for organic components published by Cappa et al. ( J. Geophys. Res. 2011 , 116 , D15204 ). Once oxidized, particles are shown to form amorphous phases on drying rather than crystallization, with slow evaporation kinetics of residual water. PMID:25003240

  3. Extraction of nitric acid, uranyl nitrate, and bismuth nitrate from aqueous nitric acid solutions with CMPO

    SciTech Connect

    Spencer, B.B.

    1995-08-01

    DOE sponsored development of the transuranium extraction (TRUEX) process for removing actinides from radioactive wastes. The solvent is a mixture of CMPO and TBP. Since the extraction characteristics of CMPO are not as well understood as those of TBP, the extraction of nitric acid, uranyl nitrate, and bismuth nitrate with CMPO (dissolved in n-dodecane) were studied. Results indicate that CMPO extracts nitric acid with a 1:1 stoichiometry; equilibrium constant is 2. 660{plus_minus}0.092 at 25 C, and extraction enthalpy is -5. 46{plus_minus}0.46 kcal/mol. Slope analysis indicates that uranyl nitrate extracts with a mixed equilibria of 1:1 and 2:1 stoichiometries in nearly equal proportion. Equil. constant of the 2: 1 extraction was 1.213 {times} 10{sup 6}{plus_minus}3.56 {times} 10{sup 4} at 25 C; reaction enthalpy was -9.610{plus_minus}0.594 kcal/mol. Nitration complexation constant is 8.412{plus_minus}0.579, with an enthalpy of -10.72{plus_minus}1.87 kcal/mol. Bismuth nitrate also extracts with a mixed equilibria of (perhaps) 1:1 and 2:1 stoichiometries. A 2:1 extraction equilibrium and a nitrate complexation adequately model the data. Kinetics and enthalpies were also measured.

  4. Dissolution of PZT 52/48 in aqueous sulfuric acid environments

    NASA Astrophysics Data System (ADS)

    Calebrese, Steven

    With the recent interest for PZT use as a self-powered nanonsensor in extreme environments, such as an oil well, it is important to ensure the stability of the material under these conditions. Oil wells are known for being extremely caustic, with high temperature, low pH and high pressures. It has been shown that in the presence of sulfuric acid PZT is subject to chemical attack. This study attempts to identify the effects that pH and temperature have on the rate of the reaction. Sulfuric acid was used as a proxy for the H2S environment found in oil wells. Exposure of bulk PZT and thin film specimens to H2S was studied. PZT 52/48 thin films were fabricated via the sol gel process. PZT was exposed to both single drops of aqueous sulfuric acid and submerged in a bath of solution. During bath exposure potential on the substrate surface of thin film samples was recorded using a voltmeter vs. and Ag/AgCl reference electrode. Thin Film samples were exposed to a single drop of 0.1 N and 1 N aqueous sulfuric acid solutions at temperatures between 25° C and 92° C. It was optically observed that a white filmed appeared on the surface as a reaction product. At both concentrations, increases in temperature lead to an increase in reaction rate for droplet exposed samples. These reactions were found to follow Arrhenius behavior. The 1 N solution activation energy of film appearance was found to be 69100 J, and for 0.1 N solution was found to be 48300 J. It was expected that an increase in concentration would lead to an increase in reaction rate as well. However for single droplet exposure it was found that lower concentrations resulted in increased reaction rate. This may be due to the difference in interfacial energy between the solution and PZT surface as a result of the concentration of sulfuric acid. The potential on the substrate during bath exposure was between -0.22 V and 0.1 V. As a ferroelectric, PZT is expected to spontaneously polarize and variations in potential

  5. Aqueous chlorination of mefenamic acid: kinetics, transformation by-products and ecotoxicity assessment.

    PubMed

    Adira Wan Khalit, Wan Nor; Tay, Kheng Soo

    2016-05-18

    Mefenamic acid (Mfe) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the environment. This study investigated the kinetics and the transformation by-products of Mfe during aqueous chlorination. The potential ecotoxicity of the transformation by-products was also evaluated. In the kinetic study, the second-order rate constant (kapp) for the reaction between Mfe and free available chlorine (FAC) was determined at 25 ± 0.1 °C. The result indicated that the degradation of Mfe by FAC is highly pH-dependent. When the pH was increased from 6 to 8, it was found that the kapp for the reaction between Mfe and FAC was decreased from 16.44 to 4.4 M(-1) s(-1). Characterization of the transformation by-products formed during the chlorination of Mfe was carried out using liquid chromatography-quadrupole time-of-flight accurate mass spectrometry. Four major transformation by-products were identified. These transformation by-products were mainly formed through hydroxylation, chlorination and oxidation reactions. Ecotoxicity assessment revealed that transformation by-products, particularly monohydroxylated Mfe which is more toxic than Mfe, can be formed during aqueous chlorination. PMID:27062128

  6. Aqueous phase hydration and hydrate acidity of perfluoroalkyl and n:2 fluorotelomer aldehydes.

    PubMed

    Rayne, Sierra; Forest, Kaya

    2016-01-01

    The SPARC software program and comparative density functional theory (DFT) calculations were used to investigate the aqueous phase hydration equilibrium constants (Khyd) of perfluoroalkyl aldehydes (PFAlds) and n:2 fluorotelomer aldehydes (FTAlds). Both classes are degradation products of known industrial compounds and environmental contaminants such as fluorotelomer alcohols, iodides, acrylates, phosphate esters, and other derivatives, as well as hydrofluorocarbons and hydrochlorofluorocarbons. Prior studies have generally failed to consider the hydration, and subsequent potential hydrate acidity, of these compounds, resulting in incomplete and erroneous predictions as to their environmental behavior. In the current work, DFT calculations suggest that all PFAlds will be dominantly present as the hydrated form in aqueous solution. Both SPARC and DFT calculations suggest that FTAlds will not likely be substantially hydrated in aquatic systems or in vivo. PFAld hydrates are expected to have pKa values in the range of phenols (ca. 9 to 10), whereas n:2 FTAld hydrates are expected to have pKa values ca. 2 to 3 units higher (ca. 12 to 13). In order to avoid spurious modeling predictions and a fundamental misunderstanding of their fate, the molecular and/or dissociated hydrate forms of PFAlds and FTAlds need to be explicitly considered in environmental, toxicological, and waste treatment investigations. The results of the current study will facilitate a more complete examination of the environmental fate of PFAlds and FTAlds. PMID:26980678

  7. Dissociation quotient of benzoic acid in aqueous sodium chloride media to 250{degrees}C

    SciTech Connect

    Kettler, R.M.; Palmer, D.A.; Wesolowski, D.J.

    1995-04-01

    The dissociation quotient of benzoic acid was determined potentiometrically in a concentration cell fitted with hydrogen electrodes. The hydrogen ion molality of benzoic acid/benzoate solutions was measured relative to a standard aqueous HCl solution at seven temperatures from 5 to 250{degrees}C and at seven ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The molal dissociation quotients and selected literature data were fitted in the isocoulombic (all anionic) form by a six-term equation. This treatment yielded the following thermodynamic quantities for the acid dissociation equilibrium at 25{degrees}C and 1 bar: logK{sub a} = -4.206{+-}0.006, {Delta}H{sub a}{sup 0} = 0.3{+-}0.3 kJ-mol{sup {minus}1}, {Delta}S{sub a}{sup 0} = -79.6{+-}1.0 J-mol{sup {minus}1}-K{sup {minus}1}, and {Delta}C{sub p;a}{sup 0} = -207{+-}5 J-mol{sup {minus}1}-K{sup {minus}1}. A five-term equation derived to describe the dependence of the dissociation constant on solvent density is accurate to 250{degrees}C and 200 MPa.

  8. An ATR-FTIR study of different phosphonic acids in aqueous solution.

    PubMed

    Zenobi, María C; Luengo, Carina V; Avena, Marcelo J; Rueda, Elsa H

    2008-07-01

    An ATR-FIR study of the vibrational spectra of 1-hydroxyethane-1,1'-diphosphonic acid (HEDP), nitrilotris(methylenephosphonic acid) (NTMP) and N,N-bis(2-hydroxyethyl)aminomethylphosphonic acid (BHAMP) in aqueous solution is presented. The study was performed in the range of pH from 5 to 9, and bands assignments are given in the 2000-890 cm(-1) range. However, as phosphonates display bands due to the PO stretching vibration mainly in the 900-1200 cm(-1) range, the study is focused in this midinfrared region, which shows important changes as the pH changes, specially the nu(POH) at approximately 925 cm(-1) and nu(PO(3)(2-)) at approximately 970 cm(-1) vibrations. IR analyses give also evidences for the zwitterionic nature of BHAMP and NTMP in solution with a strong indication that the zwitterion in both compounds remains intact throughout the pH range investigated. The successive protonation steps with the decrease of pH were evidenced in the IR spectra of the three studied phosphonates. PMID:17826311

  9. An ATR-FTIR study of different phosphonic acids in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zenobi, María C.; Luengo, Carina V.; Avena, Marcelo J.; Rueda, Elsa H.

    2008-07-01

    An ATR-FIR study of the vibrational spectra of 1-hydroxyethane-1,1'-diphosphonic acid (HEDP), nitrilotris(methylenephosphonic acid) (NTMP) and N, N-bis(2-hydroxyethyl)aminomethylphosphonic acid (BHAMP) in aqueous solution is presented. The study was performed in the range of pH from 5 to 9, and bands assignments are given in the 2000-890 cm -1 range. However, as phosphonates display bands due to the P sbnd O stretching vibration mainly in the 900-1200 cm -1 range, the study is focused in this midinfrared region, which shows important changes as the pH changes, specially the ν(P sbnd OH) at ˜925 cm -1 and ν(PO 32-) at ˜970 cm -1 vibrations. IR analyses give also evidences for the zwitterionic nature of BHAMP and NTMP in solution with a strong indication that the zwitterion in both compounds remains intact throughout the pH range investigated. The successive protonation steps with the decrease of pH were evidenced in the IR spectra of the three studied phosphonates.

  10. 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

  11. The adsorption of cationic dye from aqueous solution onto acid-activated andesite.

    PubMed

    Tsai, Wen-Tien; Hsu, Hsin-Chieh; Su, Ting-Yi; Lin, Keng-Yu; Lin, Chien-Ming; Dai, Tzong-Hung

    2007-08-25

    The adsorption of cationic dye (i.e., methylene blue) onto acid-activated andesite in aqueous solution was studied in a batch system with respect to its kinetics as a function of agitation speed, initial adsorbate concentration, pH, and adsorbent mass. It was found that the resulting acid-activated adsorbent possessed a mesoporous structure with BET surface areas at around 60m(2)/g. The surface characterization of acid-activated andesite was also performed using the zeta-potential measurements, indicating that the charge sign on the surface of the andesite should be negative in a wide pH range (i.e., 3-11). Furthermore, a simplified kinetic model, pseudo-second-order, was tested to investigate the adsorption behaviors of methylene blue onto the clay samples treated under different process conditions. It was found that the adsorption process could be well described with the model. The adsorption capacity parameter of the model obtained in the present work was significantly in line with the process parameters. PMID:17363150

  12. The effect of fatty acid surfactants on the uptake of ozone to aqueous halogenide particles

    NASA Astrophysics Data System (ADS)

    Rouvière, A.; Ammann, M.

    2010-06-01

    The reactive uptake of ozone to deliquesced potassium iodide aerosol particles coated with linear saturated fatty acids (C9, C12, C15, C18 and C20) as surfactants was studied. The experiments were performed in an aerosol flow tube at 293 K and atmospheric pressure. The uptake coefficient on pure deliquesced KI aerosol was γ=(1.10±0.20)×10-2 at 72-75% relative humidity. In presence of organic coatings, the uptake coefficient decreased significantly for long straight chain surfactants (>C15), while it was only slightly reduced for the short ones (C9, C12). We linked the kinetic results to the monolayer properties of the surfactants, and specifically to the phase state of the monolayer formed (liquid expanded or liquid condensed state). We also investigated the effect of organic films to mixed deliquesced aerosol composed of a variable mixture of KI and NaCl, which allowed determining the resistance exerted to O3 at the aqueous surface by the two longer chained surfactants pentadecanoic acid (C15) and stearic acid (C18). Finally, the effect of two-component coatings, consisting of a mixture of long and short chained surfactants, was also studied.

  13. Effects of ultrasonic processing on degradation of salvianolic acid B in aqueous solution.

    PubMed

    Guo, Y X; Zhang, L; Lu, L; Liu, E H; Shi, C Z

    2016-09-10

    To evaluate the stability of salvianolic acid B (Sal B) under ultrasound-assisted extraction in the pharmaceutical industry, degradation of Sal B under ultrasonic irradiation was investigated as the function of buffer concentration, pH, and temperature. With regard to Sal-B concentration, a first-order degradation process was determined, with 10% change in assay from its initial concentration as t90=4.81h, under maximum stability acidic conditions (pH 2.0) and at 25°C. The logkpH-pH profile described by specific acid-base catalysis and water molecules supported the experimental results. Liquid chromatography-mass spectrometry (LC-MS) analyses revealed 7 major degradation products whose structures were characterized by electrospray ionization/mass spectrometry. A primary degradation pathway involved cleavage of the ester bond and ring-opening of benzofuran in Sal B was proposed. The complete degradation pathway of Sal B was also proposed. Results showed that ultrasonic irradiation leads to degradation of Sal B in aqueous solution. PMID:27442887

  14. Equilibrium phase diagrams and water absorption properties of aqueous mixtures of malonic acid and inorganic salts.

    NASA Astrophysics Data System (ADS)

    Salcedo, D.; Salgado-Olea, G.

    2006-12-01

    Tropospheric aerosols are usually complex mixtures of inorganic and organic components. Although the thermodynamic properties of inorganic aerosols have been widely studied, the effect of organics on such properties is still under discussion. Solubility in water, water activity of aqueous solutions, deliquescence relative humidity (DRH), eutonic composition, and eutonic DRH were determined for bulk mixtures of malonic acid with ammonium sulfate, ammonium bisulfate, and ammonium nitrate at 25oC over the full range of composition (from 0 wt% to the solubility limit of the mixture components). The data was used to construct equilibrium phase diagrams, which show the phase of the mixtures as a function of total composition, dry mixture composition, water content, and ambient relative humidity. Measured water activity of liquid solutions was compared with an extended Zdanovskii-Stokes-Robinson (ZSR) expression, which then was used to predict water absorption of the mixtures.

  15. Fixed bed adsorption of 2-naphthalenesulfonic acid from aqueous solution by composite resin.

    PubMed

    Jia, Dong M; Li, Ya P; Li, Yue J; Li, Yong G; Li, Chang H

    2014-02-01

    Adsorption behavior of the iron impregnated, weakly basic resin D301 (Fe-D301) for removal of 2-naphthalenesulfonic acid (2-NSA) from aqueous solution was studied by using a fixed-bed column. The effects of process variables such as bed height, flow rate, and coexisting ions were investigated. The results indicated that the breakpoint and exhaustion point increased with increasing bed height and decreased with increasing 2-NSA flowrate. Experimental data showed a strong fit to the Bed Depth Service Time model. The coexisting ions in the 2-NSA solution had a clear effect on the breakthrough volume. The high extent of recovery of 2-NSA with good reproducibility provided an effective method for the separation of 2-NSA by the adsorbent Fe-D301. PMID:24645539

  16. Optical properties of colloidal aqueous synthesized 3 mercaptopropionic acid stabilized CdS quantum dots

    NASA Astrophysics Data System (ADS)

    Sumanth Kumar, D.; Jai Kumar, B.; Mahesh H., M.

    2016-05-01

    We have explored an easiest and simplest aqueous route to synthesize bright green luminescent CdS QDs using 3-Mercaptopropionic acid (MPA) as a stabilizer in air ambient for solar cell applications. The CdS quantum dots showed a strong quantum confinement effect with good stability, size and excellent photoluminescence. MPA Capping on CdS QDs was confirmed through FTIR. The Optical absorption spectrum revealed the CdS quantum dots are highly transparent in the visible region with absorption peak at 380 nm, confirming the quantum confinement. Photoluminescence showed an emission peak at 525 nm wavelength. The optical band gap energy was found to be 3.19 eV and CdS quantum dots radius calculated using Brus equation is 1.5 nm. The results are presented and discussed in detail.

  17. Prompt formation of organic acids in pulse ozonation of terpenes on aqueous surfaces

    NASA Astrophysics Data System (ADS)

    Hoffmann, M. R.; Colussi, A. J.; Enami, S.

    2010-12-01

    A major atmospheric process, the gas-phase ozonation of terpenes yields suites of products via a cascade of chemically activated intermediates that ranges from primary ozonides to dioxiranes. If a similar mechanism operated in water, as it is generally assumed, such intermediates would be deactivated within picoseconds and, henceforth, unable to produce carboxylic acids in microseconds. Herein we report the online electrospray mass spectrometric detection of (M + 2O - H+) and (M + 3O - H+) carboxylates on the surface of aqueous β-caryophyllene (C15H24, M = 204 Da) microjets exposed to a few ppmv O3(g) for < 10 μs. Since neither species is formed on dry solvent microjets, and both incorporate deuterium from D2O, we infer that carboxylates ensue from the interaction of nascent intermediates with interfacial water via a heretofore unreported mechanism. These interfacial events proceed much faster than in bulk liquids saturated with ozone.

  18. Cementation and Aqueous Alteration of a Sandstone Unit Under Acidic Conditions in Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Yen, A. S.; Blake, D. F.; Ming, D. W.; Morris, R. V.; Gellert, R.; Clark, B.; Vaniman, D. T.; Chipera, S. J.; Thompson, L. M.; Bristow, T. F.; Rampe, E. B.; Crisp, J. A.

    2016-01-01

    The Curiosity rover landed on Mars in August 2012 to explore the sedimentary history and to assess the habitability of Gale Crater. After 1200 sols of surface operations and over 12 km of traverse distance, the mineralogy of 10 samples has been determined by the CheMin X-ray diffractometer (XRD) and the chemical composition of nearly 300 targets has been established by the Alpha Particle X-ray Spectrometer (APXS). Light-toned fracture zones containing elevated concentrations of silica have been studied by Curiosity's instruments to determine the nature of the fluids that resulted in the enrichment of SiO2. Multiple fluid exposures are evident, and the chemistry and mineralogy data indicate at least two aqueous episodes may have occurred under acidic conditions.

  19. Microfluidic study on CNT dispersion during breakup of aqueous alginic acid drop in continuous PDMS phase

    NASA Astrophysics Data System (ADS)

    Choi, Jae Hong; Nam, Young Woo; Hong, Joung Sook

    2013-02-01

    Microfluidic study is performed to investigate how multi-walled carbon nanotube (CNTs) aggregates disperse in blend system during morphology evolution. As the dispersed phase, a drop containing CNT is generated at the flow focusing and it deforms through a contraction channel (gap and width of contraction ˜ 100 μm). When an aqueous polymeric drop (2 wt% alginic acid) with CNT (0.05 wt% or 0.5 wt%) is stretched through a 4:1 contraction channel, CNT aggregates enhances breakup of the stretched drop. Also, small droplets including CNTs are pinched off during relaxation of the stretched drop. Based on these observations, it is found that CNTs disperse in a multiphase system by repetitive breakup process during mixing rather than migration driven by chemical affinity.

  20. The aqueous photolysis of α-pinene in solution with humic acid

    NASA Astrophysics Data System (ADS)

    Goldberg, Marvin C.; Cunningham, Kirkwood M.; Aiken, George R.; Weiner, Eugene R.

    1992-01-01

    Terpenes are produced abundantly by environmental processes but are found in very low concentrations in natural waters. Aqueous photolysis of solutions containing α-pinene, a representative terpene, in the presence of humic acid resulted in degradation of the pinene. Comparison of this reaction to photolysis of α-pinene in the presence of methylene blue leads to the conclusion that the reactive pathway for the abiotic degradation of α-pinene is due to reaction with singlet oxygen produced by irradiation of the humic material. The initial product of single oxygen and α-pinene is a hydroperoxide. Since humic materials are prevalent in most natural waters, this mechanism of photodecomposition for α-pinene probably also applies to other terpenes in surface waters and may be reasonably considered to contribute to their low environmental concentration.

  1. 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.

  2. Chemistry in the Venus clouds: Sulfuric acid reactions and freezing behavior of aqueous liquid droplets

    NASA Astrophysics Data System (ADS)

    Delitsky, M. L.; Baines, K. H.

    2015-11-01

    Venus has a thick cloud deck at 40-70 km altitude consisting of liquid droplets and solid particles surrounded by atmospheric gases. The liquid droplets are highly concentrated aqueous solutions of sulfuric acid ranging in concentration from 70-99 wt%. Weight percent drops off with altitude (Imamura and Hashimoto 2001). There will be uptake of atmospheric gases into the droplet solutions and the ratios of gas-phase to liquid-phase species will depend on the Henry’s Law constant for those solutions. Reactions of sulfuric acid with these gases will form products with differing solubilities. For example, uptake of HCl by H2SO4/H2O droplets yields chlorosulfonic acid, ClSO3H (Robinson et al 1998) in solution. This may eventually decompose to thionyl- or sulfuryl chlorides, which have UV absorbances. HF will also uptake, creating fluorosulfonic acid, FSO3H, which has a greater solubility than the chloro- acid. As uptake continues, there will be many dissolved species in the cloudwaters. Baines and Delitsky (2013) showed that uptake will have a maximum at ~62 km and this is very close to the reported altitude for the mystery UV absorber in the Venus atmosphere. In addition, at very strong concentrations in lower altitude clouds, sulfuric acid will form hydrates such as H2SO4.H2O and H2SO4.4H2O which will have very different freezing behavior than sulfuric acid, with much higher freezing temperatures (Carslaw et al, 1997). Using temperature data from Venus Express from Tellmann et al (2009), and changes in H2SO4 concentrations as a function of altitude (James et al 1997), we calculate that freezing out of sulfuric acid hydrates can be significant down to as low as 56 km altitude. As a result, balloons, aircraft or other probes in the Venus atmosphere may be limited to flying below certain altitudes. Any craft flying at altitudes above ~55 km may suffer icing on the wings, propellers, balloons and instruments which could cause possible detrimental effects (thermal

  3. Electrochemical treatment of acidic aqueous ferrous sulfate and copper sulfate as models for acid mine drainage.

    PubMed

    Bunce, N J; Chartrand, M; Keech, P

    2001-12-01

    Acid mine drainage (AMD) is a serious environmental problem in the mining industry. The present work describes electrolytic reduction of solutions of synthetic AMD, comprising FeSO4/H2SO4 and CuSO4/H2SO4, in flow-through cells whose anode and cathode compartments were separated using ion exchange membranes. In the case of FeSO4/H2SO4 at constant flow rate, the pH of the effluent from the catholyte increased progressively with current at a variety of cathodes, due to electrolytic reduction of H+ ions to elemental hydrogen. Near-quantitative removal of iron was achieved by sparging air into the catholyte effluent, thereby precipitating iron outside the electrochemical cell, and avoiding fouling of the electrodes. The anode reaction was the oxidation of water to O2, a proton-releasing process. Using cation exchange membranes and sodium sulfate as the supporting electrolyte in the anode compartment, the efficiency of the process was compromised at high currents by transport of H+ competitively with Na+ from the anode to the cathode compartments. Higher efficiencies were obtained when anion exchange membranes were used, and in this case no additional supporting electrolyte other than dilute H2SO4 was needed, the net reaction being the electrochemically driven transfer of the elements of H2SO4 from the cathode to the anode compartments. Current efficiencies approximately 50% were achieved, the loss of efficiency being accounted for by ohmic heating of the solutions. In the case of CuSO4/H2SO4 and anion exchange membranes at high currents, reduction of Cu2+ and H+ ions and transport of SO4(2-) ions out of the catholyte caused unacceptably high potentials to be generated. PMID:11763043

  4. A GREEN CHEMISTRY APPROACH TO PREPARATION OF CORE (FE OR CU)-SHELL (NOBLE METALS) NANOCOMPOSITES USING AQUEOUS ASCORBIC ACID

    EPA Science Inventory

    A greener method to fabricate novel core (Fe or Cu)-shell (noble metals) nanocomposites of transition metals such as Fe and Cu and noble metals such as Au, Pt, Pd, and Ag using aqueous ascorbic acid is described. Transition metal salts such as Cu and Fe were reduced using ascor...

  5. Specific staining of nuclei with aqueous solutions of celestin blue B and gallocyanine.

    PubMed

    Dutt, M K

    1982-09-01

    This paper presents methods for specific staining of nuclei with aqueous solutions of celestin blue B and gallocyanine in tissue sections from which RNA has been extracted selectively with concentrated phosphoric acid at 5 degrees C for 20 min or by hydrolysis in 6 N HCl at 28 degrees C for 15 min. It has been found that pH of the freshly prepared celestin blue B dye solution is 3.0 and that of an aqueous solution of gallocyanine is 2.8. These pHs can be lowered to 1.5 with concentrated sulphuric or nitric acid and at this pH staining of the nuclei is possible. But with concentrated sulphuric or nitric acid and at this pH staining of the nuclei is possible. But if the pHs are lowered with concentrated hydrochloric or phosphoric acid, effective use of these dyes is not possible. It has been suggested that some dispersion of the two dyes takes place with concentrated sulphuric or nitric acid which are used to lower the pH. Staining of the nuclei is also possible with an aqueous solution of celestin blue B at pH 3.0 but the same is not possible with gallocyanine at pH 2.8. The absorption spectra of nuclei stained with an aqueous solution of celestin blue B at pH 1.5 and 3.0 are fairly identical, the peak of maximum absorption being at 620 nm. Those of nuclei stained with an aqueous solution of gallocyanine reveal irregular peaks. Possible implications of these findings have been discussed. PMID:6183561

  6. Biosorption of methyl blue onto tartaric acid modified wheat bran from aqueous solution

    PubMed Central

    2012-01-01

    Tartaric acid modified wheat bran was utilized as adsorbent to remove methyl blue, a basic dye from aqueous solution. Batch experiments were carried out to study the effect of various experimental parameters such as initial solution pH, contact time, initial dye concentration and adsorbent dosage, on dye adsorption. The results showed that the modification of wheat bran by tartaric acid significantly improved its adsorption capacity, and made this material a suitable adsorbent to remove methyl blue. The adsorption capacity of modified wheat bran was about 1.6 times higher than that of unmodified one. The amount of methyl blue adsorbed was found to vary with initial solution pH, adsorbent dosage, contact time and initial methyl blue concentration. Kinetics study showed that the overall adsorption rate of methyl blue was illustrated by pseudo-second-order kinetic model. The applicability of the Langmuir and Freundlich models for the data was tested. Both models adequately described the experimental data of the biosorption of methyl blue. The maximum adsorption capacity for methyl blue calculated from Langmuir model was 25.18 mg/g. The study has shown the effectiveness of modified wheat bran in the removal of methyl blue, and that it can be considered as an attractive alternative to the more expensive technologies used in wastewater treatment. PMID:23369295

  7. HCN, Formamidic Acid, and Formamide in Aqueous Solution: A Free-Energy Map.

    PubMed

    Kua, Jeremy; Thrush, Kyra L

    2016-08-25

    What chemical species might be found if water or ammonia reacts with HCN in aqueous solution under neutral conditions? Is it energetically favorable for formamidic acid, the first hydration product of HCN, to tautomerize into formamide under standard conditions? Do these molecules form stable oligomers in solution? To answer these questions, we constructed a Gibbs free-energy map of the molecules that might be present to evaluate their relative thermodynamic and kinetic stability. Our protocol utilizes density functional theory calculations, Poisson-Boltzmann implicit solvent, and thermodynamic corrections. We find that for C1 species, formamide is indeed the thermodynamic sink, although the initial barrier to hydration is ∼30 kcal/mol. Molecules with one carbon and three heteroatoms are less stable. We also find that for HCN trimerization, although the planar sp(2) six-membered ring is more stable compared to its monomers, the reverse is true for the nonplanar sp(3) six-membered rings formed by trimerization of formamidic acid or formamide. PMID:27016454

  8. Preparation of aqueous alpha-lipoic acid dispersions with octenylsuccinylated high amylose starch.

    PubMed

    Li, Yi-Xuan; Lim, Seung-Taik

    2016-04-20

    Aqueous dispersions prepared with OSA-modified high amylose starch were investigated in comparison with native high amylose starch and beta-cyclodextrin using alpha-lipoic acid as a model substance. Alpha-lipoic acid (ALA), a lipophilic antioxidant essential for energy metabolism in human, was dispersed in gelatinized starch solutions (1.0% w/v) at different temperatures (50-90°C) and times (3-12h). High amylose starch modified with 3% OSA (dry starch base) was most favored in maximizing the dispersibility of ALA (84% recovery) under mild heating (70°C for 3h). The optimally prepared dispersion was milky white and contained particles with a narrow size distribution (200-300nm). The precipitate isolated from the dispersion contained crystalline V-complexes of ALA and amylose while the supernatant contained free ALA accounting for 1/3 of total ALA, indicating OSA-modified high amylose starch stabilized ALA either by complexing with amylose or by retarding aggregation of ALA. PMID:26876852

  9. Biosorption of methyl blue onto tartaric acid modified wheat bran from aqueous solution.

    PubMed

    Yao, Shuhua; Lai, Hong; Shi, Zhongliang

    2012-01-01

    Tartaric acid modified wheat bran was utilized as adsorbent to remove methyl blue, a basic dye from aqueous solution. Batch experiments were carried out to study the effect of various experimental parameters such as initial solution pH, contact time, initial dye concentration and adsorbent dosage, on dye adsorption. The results showed that the modification of wheat bran by tartaric acid significantly improved its adsorption capacity, and made this material a suitable adsorbent to remove methyl blue. The adsorption capacity of modified wheat bran was about 1.6 times higher than that of unmodified one. The amount of methyl blue adsorbed was found to vary with initial solution pH, adsorbent dosage, contact time and initial methyl blue concentration. Kinetics study showed that the overall adsorption rate of methyl blue was illustrated by pseudo-second-order kinetic model. The applicability of the Langmuir and Freundlich models for the data was tested. Both models adequately described the experimental data of the biosorption of methyl blue. The maximum adsorption capacity for methyl blue calculated from Langmuir model was 25.18 mg/g. The study has shown the effectiveness of modified wheat bran in the removal of methyl blue, and that it can be considered as an attractive alternative to the more expensive technologies used in wastewater treatment. PMID:23369295

  10. Removal of aqueous perfluorooctanoic acid (PFOA) using starch-stabilized magnetite nanoparticles.

    PubMed

    Gong, Yanyan; Wang, Lin; Liu, Juncheng; Tang, Jingchun; Zhao, Dongye

    2016-08-15

    Fully stabilized magnetite (Fe3O4) nanoparticles were prepared with a water-soluble starch as a stabilizer and tested for removal of aqueous perfluorooctanoic acid (PFOA). The presence of starch at ≥0.2wt% can fully stabilize 0.1g/L as Fe of the Fe3O4 nanoparticles. The particle stabilization technique resulted in 2.4 times higher PFOA uptake. Fourier transform infrared spectra suggested that the main PFOA removal mechanism was inner-sphere complexation. Batch kinetic experiments revealed that the starch-stabilized nanoparticles facilitated a rapid PFOA uptake with a sorption equilibrium time of 30min, and the sorption process followed a pseudo-second-order kinetic model. The Langmuir model was able to well interpret the adsorption isotherm, with a maximum adsorption capacity of 62.5mg/g. Increasing pH from 4.7 to 9.6 led to a sharp increase (by 2.6 times) in PFOA uptake. The presence of 12mg/L humic acid inhibited PFOA uptake by 96%, while effect of ionic strength (CaCl2=0-2mmol/L) was negligible. The nanoparticles significantly reduced the biological toxicity of PFOA. The results demonstrated promise of starch-stabilized Fe3O4 nanoparticles as a "green" adsorbent for effective removal of PFOA in soil and groundwater. PMID:27100000

  11. A chemiluminescence-based continuous flow aqueous ozone analyzer using photoactivated chromotropic acid.

    PubMed

    Takayanagi, Toshio; Dasgupta, Purnendu K

    2005-05-15

    Ozone has become the oxidant of choice for water disinfection, especially in large water treatment facilities. This paper describes a fast and sensitive method for the determination of ozone content by reaction with photoactivated chromotropic acid (CA, 4,5-dihydroxynaphthalene-2,7-disulfonic acid), which results in intense chemiluminescence (CL). Freshly ozonated water from a recirculating ozonizer/reservoir is injected into a carrier stream of deionized water in the flow-injection mode. This flow mixes with a stream of photoactivated CA solution in a spiral cell placed directly on top of an inexpensive miniature (8mm diameter active area) photomultiplier tube (PMT). Alkaline CA is photoactivated by passing it through a FEP-Teflon((R)) coil (residence time approximately 50s) wrapped around a 1W UV lamp emitting at 254nm; without photoactivation, the signal is approximately 70-fold lower. The S/N=3 limit of detection for aqueous ozone is 3mugl(-1) and good response slope is obtained up to an ozone concentration of 1.4mgl(-1), the highest that could be made in this study. The response obeyed a quadratic equation with r(2)=0.9984. No interference from permanganate ion is observed. The proposed system was applied to the monitoring of ozonation status of a playa lake water that exhibited significant ozone demand. PMID:18970059

  12. Ultrasonic absorption in aqueous solutions of amino acids at neutral pH

    NASA Astrophysics Data System (ADS)

    Nishikawa, S.; Ohno, T.; Huang, H.; Yoshizuka, K.; Jordan, F.

    2003-05-01

    Ultrasonic absorption coefficients in aqueous solutions of glycine, L-alanine, imidazole, L-phenylalanine, L-histidine and L-tryptophan at neutral pH were measured in the range from 0.8 to 220 MHz at 25 °C. A characteristic ultrasonic relaxation phenomenon was observed only in the solution of L-histidine with a relaxation frequency at around 2 MHz at neutral pH. It was proposed from the concentration independent relaxation frequency and the linear concentration dependence of the maximum absorption per wavelength that the relaxation mechanism was associated with a perturbation of the rotational isomeric equilibrium of the L-histidine molecule. The existence of two rotational isomeric forms of L-histidine in water was examined by semiempirical quantum chemical methods, in order to determine the free energy difference between the two states. The forward and backward rate constants were determined from the relaxation frequency and the energy change. Also, the standard volume change of the reaction was estimated from the concentration dependence of the maximum absorption per wavelength. It was speculated that L-histidine fulfills a specific function among amino acids because of the rotational motion in the molecule, in addition to its well-established acid-base properties.

  13. Photochemical oxidation of chloride ion by ozone in acid aqueous solution.

    PubMed

    Levanov, Alexander V; Isaykina, Oksana Ya; Amirova, Nazrin K; Antipenko, Ewald E; Lunin, Valerii V

    2015-11-01

    The experimental investigation of chloride ion oxidation under the action of ozone and ultraviolet radiation with wavelength 254 nm in the bulk of acid aqueous solution at pH 0-2 has been performed. Processes of chloride oxidation in these conditions are the same as the chemical reactions in the system O3 - OH - Cl(-)(aq). Despite its importance in the environment and for ozone-based water treatment, this reaction system has not been previously investigated in the bulk solution. The end products are chlorate ion ClO3(-) and molecular chlorine Cl2. The ions of trivalent iron have been shown to be catalysts of Cl(-) oxidation. The dependencies of the products formation rates on the concentrations of O3 and H(+) have been studied. The chemical mechanism of Cl(-) oxidation and Cl2 emission and ClO3(-) formation has been proposed. According to the mechanism, the dominant primary process of chloride oxidation represents the complex interaction with hydroxyl radical OH with the formation of Cl2(-) anion-radical intermediate. OH radical is generated on ozone photolysis in aqueous solution. The key subsequent processes are the reactions Cl2(-) + O3 → ClO + O2 + Cl(-) and ClO + H2O2 → HOCl + HO2. Until the present time, they have not been taken into consideration on mechanistic description and modelling of Cl(-) oxidation. The final products are formed via the reactions 2ClO → Cl2O2, Cl2O2 + H2O → 2H(+) + Cl(-) + ClO3(-) and HOCl + H(+) + Cl(-) ⇄ H2O + Cl2. Some portion of chloride is oxidized directly by O3 molecule with the formation of molecular chlorine in the end. PMID:26077317

  14. Poorly crystalline hydroxyapatite: A novel adsorbent for enhanced fulvic acid removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Yang, Lei; Zhong, Wenhui; Cui, Jing; Wei, Zhenggui

    2015-03-01

    In this study, poorly crystalline hydroxyapatite (HAP) was developed as an efficient adsorbent for the removal of fulvic acid (FA) from aqueous solution. Surface functionality, crystallinity, and morphology of the synthetic adsorbent were studied by Fourier-transformation infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of various parameters such as crystallinity of adsorbent, contact time, adsorbent dosage, pH, initial adsorbate concentration, temperature, ionic strength and the presence of alkaline earth metal ions on FA adsorption were investigated. Results indicated that the nanosized HAP calcined at lower temperature was poorly crystalline (Xc = 0.23) and had better adsorption capacity for FA than those (Xc = 0.52, 0.86) calcined at higher temperature. FA removal was increased with increases of adsorbent dosage, temperature, ionic strength and the presence of alkali earth metal ions, but decreased as the pH increased. Kinetic studies showed that pseudo-second-order kinetic model better described the adsorption process. Equilibrium data were best described by Sips models, and the estimated maximum adsorption capacity of poorly crystalline HAP was 90.20 mg/g at 318 K, displaying higher efficiency for FA removal than previously reported adsorbents. FT-IR results revealed that FA adsorption over the adsorbent could be attributed to the surface complexation between the oxygen atom of functional groups of FA and calcium ions of HAP. Regeneration studies indicated that HAP could be recyclable for a long term. Findings of the present work highlight the potential for using poorly crystalline HAP nanoparticles as an effective and recyclable adsorbent for FA removal from aqueous solution.

  15. Photochemical Control of the Distribution of Water and Sulphuric Acid Aerosols in the Clouds and Upper Haze of Venus with Comparison to Venus Express SOIR Observations

    NASA Astrophysics Data System (ADS)

    Parkinson, C. D.; Gao, P.; Yung, Y. L.; Bougher, S. W.; Bardeen, C.

    2014-12-01

    Observations of the middle and lower cloud layers of Venus has established the water vapour mixing ratio there as ~ 30-35 ppm (Ignatiev et al. 1997), while more recent data suggests that the water vapor mixing ratio of the upper haze of Venus is ~ 1 ppm (Bertaux et al. 2007). The transition region between these two regimes, the upper cloud, is an active site of photochemistry and production of sulfuric acid, which occurs through the formation of SO3 from the oxidation of SO2, and subsequent reactions between SO3 and water. These reactions have been shown by Parkinson et al. (2014a, submitted) as capable of causing an order of magnitude decrease of the water vapor mixing ratio in the upper cloud and upper haze if the SO2 mixing ratio at the upper cloud base were increased by only ~20%, as the resulting high SO3 concentrations rapidly react with any available water to form sulfuric acid. The opposite is true when water is in high abundance. This is likely to have profound effects on the sulfuric acid clouds and hazes themselves, as 1) the depletion of either species will decrease the production rate of sulfuric acid and 2) the saturation vapor pressure of the cloud droplets increases with decreasing water fraction, and thus a "drying" of the clouds may result in decreased cloud thickness. In this work we will use the Venus microphysical cloud models of Gao et al. (2014) and Parkinson et al. (2014b, submitted) to simulate the sulfuric acid clouds and hazes of Venus from 40 to 100 km altitude and evaluate how their structure and particle sizes depend on the background water vapor profile and sulfuric acid production rate as determined by Parkinson et al. (2014a, submitted). We also show how they respond to transient episodes of increased/decreased SO2/H2O mixing ratios and discuss the plausibility of possible causes, such as volcanic activity.

  16. The sodium/sulphur battery

    NASA Astrophysics Data System (ADS)

    Sudworth, J. L.

    1984-02-01

    Problems encountered in the design and development of a practical sodium/sulphur battery are reviewed and several solutions are offered. Consideration is given to the degradation of the solid electrolyte, beta alumina; problems with the sodium electrode associated with the sodium/beta alumina interface; and the loss of capacity identified with the sulphur electrode. Attention is also given to the search for corrosion-resistant materials for use as the current collector and to the geometry of the cell design. Criteria for a successful road vehicle battery are discussed.

  17. Experimental and Theoretical Studies of the Acid-Catalyzed Conversion of Furfuryl Alcohol to Levulinic Acid in Aqueous Solution

    SciTech Connect

    Gonzalez Maldonado, Gretchen M.; Assary, Rajeev S.; Dumesic, James A.; Curtiss, Larry A.

    2012-02-14

    The conversion of furfuryl alcohol (FAL) to levulinic acid over Amberlyst TM 15 in aqueous media was investigated using a combination of liquid chromatography-mass spectrometry (LC-MS) measurements, isotopic labeling studies, nuclear magnetic resonance (NMR) spectroscopy, and ab initio quantum chemical calculations using the G4MP2 method. The results of these combined studies showed that one of the major reaction pathways takes place via a geminal diol species (4,5,5- trihydroxypentan-2-one, denoted as intermediate A), formed by the addition of two water molecules to FAL, where two of the oxygen atoms from FAL are retained. This geminal diol species can also be produced from another intermediate found to be a dimer-like species, denoted as intermediate B. This dimer-like species is formed at the early stages of reaction, and it can also be converted to intermediate A, indicating that intermediate B is the product of the reaction of FAL with another early intermediate. Quantum chemical calculations suggested this to be a protonated acyclic species. Reaction of this early intermediate with water produces intermediate A, while reaction with FAL produces intermediate B.

  18. Theoretical insights into the properties of amino acid ionic liquids in aqueous solution.

    PubMed

    Zhu, Xueying; Ai, Hongqi

    2016-07-01

    This report presents a systematic investigation of the interactions of water molecule(s) with a series of amino acid cations (Gly(+), Ala(+), Val(+), and Leu(+)), halogen anions (Cl(-), Br(-), BF4 (-), and PF6 (-)), and clusters (GlyCl) n (n = 1-5). The results reveal that H-bonds between amino acid ionic liquids (AAILs) and water molecules are crucial to the properties of aqueous solution of AAILs. The properties of AAIL in water solution depend on the alkyl chain of the amino acid cation, the size of the halogen anion, and the number of water molecules, which provides a certain theoretical basis for the design and application of new AAILs. A series of calculations for some different models showed that quadruple-GlyCl hydrate represents a basic unit for the Gly-water binary system, and can be employed as the simplest model for studying an AAIL-water cluster. On the basis of this model, the effects of water on the hygroscopicity, speed of solubility, viscosity, density, solution enthalpy, and polarity of the AAIL were also predicted. Most importantly, unlike traditional ILs, the novel GlyCl-type AAIL favors interaction of its cationic part, rather than its anionic part, with surrounding water molecules, thus amino acid cationic ILs expand the types of IL available, increasing the choice of ILs for different purposes. We hope that the application of this AAIL in many fields will lead to optimization of this class of compound and be of benefit to the environment. Graphical Abstract Quadruple-GlyCl hydrate represents the basic unit for a GlyCl-water binary system, which can be employed as the simplest model for studying an amino acid ionic liquid (AAIL)-water cluster. The effects of available water on some properties of AAIL are predicted. GlyCl-type AAIL is a novel IL, which prefers its cationic part over its anionic part for interaction with surrounding water molecules. The properties of AAIL in water solution can be adjusted by varying the ion used and the

  19. Lewis Acid Pairs for the Activation of Biomass-derived Oxygenates in Aqueous Media

    SciTech Connect

    Roman, Yuriy

    2015-09-14

    The objective of this project is to understand the mechanistic aspects behind the cooperative activation of oxygenates by catalytic pairs in aqueous media. Specifically, we will investigate how the reactivity of a solid Lewis acid can be modulated by pairing the active site with other catalytic sites at the molecular level, with the ultimate goal of enhancing activation of targeted functional groups. Although unusual catalytic properties have been attributed to the cooperative effects promoted by such catalytic pairs, virtually no studies exist detailing the use heterogeneous water-tolerant Lewis pairs. A main goal of this work is to devise rational pathways for the synthesis of porous heterogeneous catalysts featuring isolated Lewis pairs that are active in the transformation of biomass-derived oxygenates in the presence of bulk water. Achieving this technical goal will require closely linking advanced synthesis techniques; detailed kinetic and mechanistic investigations; strict thermodynamic arguments; and comprehensive characterization studies of both materials and reaction intermediates. For the last performance period (2014-2015), two technical aims were pursued: 1) C-C coupling using Lewis acid and base pairs in Lewis acidic zeolites. Tin-, zirconium-, and hafnium containing zeolites (e.g., Sn-, Zr-, and Hf-Beta) are versatile solid Lewis acids that selectively activate carbonyl functional groups. In this aim, we demonstrate that these zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions. 2) One-pot synthesis of MWW zeolite nanosheets for activation of bulky substrates. Through

  20. Photocatalytic CO2 reduction to formic acid using a Ru(II)-Re(I) supramolecular complex in an aqueous solution.

    PubMed

    Nakada, Akinobu; Koike, Kazuhide; Nakashima, Takuya; Morimoto, Tatsuki; Ishitani, Osamu

    2015-02-16

    In an aqueous solution, photophysical, photochemical, and photocatalytic abilities of a Ru(II)-Re(I) binuclear complex (RuReCl), of which Ru(II) photosensitizer and Re(I) catalyst units were connected with a bridging ligand, have been investigated in details. RuReCl could photocatalyze CO2 reduction using ascorbate as an electron donor, even in an aqueous solution. The main product of the photocatalytic reaction was formic acid in the aqueous solution; this is very different in product distribution from that in a dimethylformamide (DMF) and triethanolamine (TEOA) mixed solution in which the main product was CO. A (13)CO2 labeling experiment clearly showed that formic acid was produced from CO2. The turnover number and selectivity of the formic acid production were 25 and 83%, respectively. The quantum yield of the formic acid formation was 0.2%, which was much lower, compared to that in the DMF-TEOA mixed solution. Detail studies of the photochemical electron-transfer process showed back-electron transfer from the one-electron-reduced species (OERS) of the photosensitizer unit to an oxidized ascorbate efficiently proceeded, and this should be one of the main reasons why the photocatalytic efficiency was lower in the aqueous solution. In the aqueous solution, ligand substitution of the Ru(II) photosensitizer unit proceeded during the photocatalytic reaction, which was a main deactivation process of the photocatalytic reaction. The product of the ligand substitution was a Ru(II) bisdiimine complex or complexes with ascorbate as a ligand or ligands. PMID:25654586

  1. Geochemistry: Sulphur from heaven and hell

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas

    2013-09-01

    Fingerprints of sulphur isotopes in rocks from the ridge beneath the Atlantic Ocean suggest that a substantial fraction of sulphur at Earth's surface is left over from the formation of the planet's core. See Letter p.208

  2. The cleaning and disinfecting of hemodialysis equipment using electrolyzed strong acid aqueous solution.

    PubMed

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

    1999-04-01

    In general, sodium hypochlorite, formalin, and Dialox (Teijin Gambro Medical, Ltd., Tokyo, Japan [main ingredients: H2O2, CH3CHOOOH, CH3COOH, H2O]) are used to clean and disinfect hemodialysis pipelines. In this study, the suitability of electrolyzed strong acid aqueous solution (ESAAS), which has attracted considerable interest in Japan because of its strong disinfecting properties, was examined. The crossover method was used to investigate the effectiveness of ESAAS in disinfecting the dialysis pipelines in comparison to that of sodium hypochlorite (200 ppm) used alternately with 1% acetic acid. The number of bacteria and the concentration of endotoxin (Et) were measured over an approximately 3 year period, starting in September 1994. Until then, 200 ppm sodium hypochlorite had been used alternately with 1% acetic acid, and the contamination of the pipeline had been marked. However, after switching to the ESAAS disinfection method, the dialysis pipelines very rapidly became cleaner. Therefore, the decision to develop an automated ESAAS cleaning system for long-term use was made. During the development period, the original disinfectants (200 ppm sodium hypochlorite used alternately with 1% acetic acid) were used as a stopgap. After confirmation of its performance and safety, the automated ESAAS cleaning system was introduced. To find out whether the decrease in bacteria secondarily caused a decrease in the Et concentration or whether the ESAAS directly inactivated the Et, an in vitro experiment was carried out. Highly concentrated Et, which had been left in the reverse osmosis (RO) drainage pipeline, was used as a sample to investigate the effects of ESAAS on Et at various concentrations and temperatures and on the recovery test. The results showed that ESAAS directly inactivated Et. This paper reports the results of the crossover test. The results of parallel tests carried out over an approximately 4 year period have already been reported. No significant problems

  3. Adsorption of Benzoic Acid in Aqueous Solution by Bagasse Fly Ash

    NASA Astrophysics Data System (ADS)

    Suresh, S.

    2012-09-01

    This paper reports the studies on the benzoic acid (BA) onto bagasse fly ash (BFA) was studied in aqueous solution in a batch system. Physico-chemical properties including surface area, surface texture of the GAC before and after BA adsorption onto BFA were analysed using X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The optimum initial pH for the adsorption of BA was found to be 5.56. The adsorbent dose was 10 g/l for BFA and the equilibrium time 8 h of reaction. Pseudo first and second order models were used to find the adsorption kinetics. It was found that intraparticle diffusion played important role in the adsorption mechanisms of BA and the adsorption kinetics followed pseudo-second order kinetic model rather than the pseudo first order kinetic model. Isotherm data were generated for BA solution having initial concentrations of BA in the range of 10-200 mg/l for the BFA dosage of 10 g/l at temperatures of 288, 303, and 318 K. The adsorption of BA onto BFA was favorably influenced by an increase in temperature. Equilibrium data were well represented by the Redlich-Peterson isotherm model. Values of the change in entropy ( ΔS 0), heat of adsorption ( ΔH 0) for adsorption of BA on BFA was found to be 120.10 and 19.61 kJ/mol respectively. The adsorption of BA onto BFA was an endothermic reaction. Desorption of BA from BFA was studied by various solvents method. Acetic acid was found to be a better eluant for desorption of BA with a maximum desorption efficiency of 55.2 %. Owing to its heating value, spent BFA can be used as a co-fuel for the production of heat in boiler furnaces.

  4. Zirconium(IV) tetramer/octamer hydrolysis equilibrium in aqueous hydrochloric acid solution

    SciTech Connect

    Singhal, A.; Toth, L.M.; Lin, J.S.; Affholter, K.

    1996-11-20

    Small-angle X-ray scattering measurements were performed on zirconium acidic aqueous solutions to investigate the structure and the size of polynuclear species larger than the previously identified tetrameric species. Solutions with [H{sup +}]{sub added} and [OH{sup -}]{sub added} ranging from 0.0 to 1.0 M and 0.0 to 0.02 M, respectively, were analyzed. This study demonstrates that an octameric species, Zr{sub 8}(OH){sub 20}(H{sub 2}O){sub 24}Cl{sub 12}, exists in equilibrium with the tetrameric species, Zr{sub 4}(OH){sub 8}(H{sub 2} O){sub 16}Cl{sub 6}{sup 2+}, such that, for 0.05 M Zr(IV) in highly acidic solutions ([H{sup +}]{sub added} = 0.6 M), the tetramer in the dominant species; and at conditions with [H{sup +}] added =0.05 M, the octameric species becomes predominant. The estimated value of the equilibrium quotient obtained for the tetramer/octamer equilibrium is 0.20 {+-} 0.05 M{sup 3}. The tetramer and octamer have radii of gyration of 3.8 and 5.1 {+-} 0.2 A and a hydrolysis ratio of 2.0 and 2.5, respectively. The octamer forms by stacking two tetramers on top of each other. At conditions where small amounts of NaOH are added, unidentified polymeric Zr(IV) species larger in size than the octameric species appear. 26 refs., 7 figs.

  5. Aqueous Growth of Gold Clusters with Tunable Fluorescence Using Photochemically Modified Lipoic Acid-Based Ligands.

    PubMed

    Mishra, Dinesh; Aldeek, Fadi; Lochner, Eric; Palui, Goutam; Zeng, Birong; Mackowski, Sebastian; Mattoussi, Hedi

    2016-06-28

    We report a one-phase aqueous growth of fluorescent gold nanoclusters (AuNCs) with tunable emission in the visible spectrum, using a ligand scaffold that is made of poly(ethylene glycol) segment appended with a metal coordinating lipoic acid at one end and a functional group at the other end. This synthetic scheme exploits the ability of the UV-induced photochemical transformation of LA-based ligands to provide DHLA and other thiol byproducts that exhibit great affinity to metal nanoparticles, obviating the need for chemical reduction of the dithiolane ring using classical reducing agents. The influence of various experimental conditions, including the photoirradiation time, gold precursor-to-ligand molar ratios, time of reaction, temperature, and the medium pH, on the growth of AuNCs has been systematically investigated. The photophysical properties, size, and structural characterization were carried out using UV-vis absorption and fluorescence spectroscopy, TEM, DOSY-NMR, and X-ray photoelectron spectroscopy. The hydrodynamic size (RH) obtained by DOSY-NMR indicates that the size of these clusters follows the trend anticipated from the absorption and PL data, with RH(red) > RH(yellow) > RH(blue). The tunable emission and size of these gold nanoclusters combined with their high biocompatibility would make them greatly promising for potential use in imaging and sensing applications. PMID:27254320

  6. Near-Infrared Electrogenerated Chemiluminescence from Aqueous Soluble Lipoic Acid Au Nanoclusters.

    PubMed

    Wang, Tanyu; Wang, Dengchao; Padelford, Jonathan W; Jiang, Jie; Wang, Gangli

    2016-05-25

    Strong electrogenerated chemiluminescence (ECL) is detected from dithiolate Au nanoclusters (AuNCs) in aqueous solution under ambient conditions. A novel mechanism to drastically enhance the ECL is established by covalent attachment of coreactants N,N-diethylethylenediamine (DEDA) onto lipoic acid stabilized Au (Au-LA) clusters with matching redox activities. The materials design reduces the complication of mass transport between the reactants during the lifetime of radical intermediates involved in conventional ECL generation pathway. The intracluster reactions are highly advantageous for applications by eliminating additional and high excess coreactants otherwise needed. The enhanced ECL efficiency also benefits uniquely from the multiple energy states per Au cluster and multiple DEDA ligands in the monolayer. Potential step and sweeping experiments reveal an onset potential of 0.78 V for oxidative-reduction ECL generation. Multifolds higher efficiency is found for the Au clusters alone in reference to the standard Rubpy with high excess TPrA. The ECL in near-IR region (beyond 700 nm) is highly advantageous with drastically reduced interference signals over visible ones. The features of ECL intensity responsive to electrode potential and solution pH under ambient conditions make Au-LA-DEDA clusters promising ECL reagents for broad applications. The strategy to attach coreactants on Au clusters is generalizable for other nanomaterials. PMID:27172252

  7. Preparation and characterization of aqueous dispersions of high amylose starch and conjugated linoleic acid complex.

    PubMed

    Seo, Tae-Rang; Kim, Hee-Young; Lim, Seung-Taik

    2016-11-15

    Crystalline starch-CLA complexes were prepared by blending an alcoholic solution of conjugated linoleic acid (CLA) in an aqueous high-amylose maize starch dispersion. Recovery yield of CLA in the precipitates obtained by centrifuging the dispersion was dependent on reaction conditions such as temperature, time and pH. The CLA recovery reached a maximum when the reaction was performed at 90°C for 6h at neutral pH, with 67.7% of the initial CLA being co-precipitated with starch. The precipitates contained amylose-CLA complex exhibiting a V6I-type crystalline structure under X-ray diffraction analysis and a type II polymorph under DSC analysis. Ultrasonic treatment for the re-dispersed starch-CLA complex in water resulted in the reduction of hydrodynamic diameter of the complex particles to 201.5nm. The dispersion exhibited a zeta potential of -27.0mV and remained stable in an ambient storage without forming precipitates for more than 4weeks. PMID:27283663

  8. Molecular Modeling of Ammonium, Calcium, Sulfur, and Sodium Lignosulphonates in Acid and Basic Aqueous Environments

    NASA Astrophysics Data System (ADS)

    Salazar Valencia, P. J.; Bolívar Marinez, L. E.; Pérez Merchancano, S. T.

    2015-12-01

    Lignosulphonates (LS), also known as lignin sulfonates or sulfite lignin, are lignins in sulfonated forms, obtained from the "sulfite liquors," a residue of the wood pulp extraction process. Their main utility lies in its wide range of properties, they can be used as additives, dispersants, binders, fluxing, binder agents, etc. in fields ranging from food to fertilizer manufacture and even as agents in the preparation of ion exchange membranes. Since they can be manufactured relatively easy and quickly, and that its molecular size can be manipulated to obtain fragments of very low molecular weight, they are used as transport agents in the food industry, cosmetics, pharmaceutical and drug development, and as molecular elements for the treatment of health problems. In this paper, we study the electronic structural and optical characteristics of LS incorporating ammonium, sulfur, calcium, and sodium ions in acidic and basic aqueous media in order to gain a better understanding of their behavior and the very interesting properties exhibit. The studies were performed using the molecular modeling program HyperChem 5 using the semiempirical method PM3 of the NDO Family (neglect of differential overlap), to calculate the structural properties. We calculated the electronic and optical properties using the semiempirical method ZINDO / CI.

  9. Removal of acid blue 062 on aqueous solution using calcinated colemanite ore waste.

    PubMed

    Atar, Necip; Olgun, Asim

    2007-07-19

    Colemanite ore waste (CW) has been employed as adsorbent for the removal of acid blue 062 anionic dye (AB 062) from aqueous solution. The adsorption of AB 062 onto CW was examined with respect to contact time, calcination temperature, particle size, pH, adsorbent dosage and temperature. The physical and chemical properties of the CW, such as particle sizes and calcinations temperature, play important roles in dye adsorption. The dye adsorption largely depends on the initial pH of the solution with maximum uptake occurring at pH 1. Three simplified kinetics models, namely, pseudo-first order, pseudo-second order, and intraparticle diffusion models were tested to investigate the adsorption mechanisms. The kinetic adsorption of AB 062 on CW follows a pseudo-second order equation. The adsorption data have been analyzed using Langmuir and Freundlich isotherms. The results indicate that the Langmuir model provides the best correlation of the experimental data. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of the adsorption of dye onto CW. PMID:17197077

  10. Aqueous solution deposition kinetics of iron oxyhydroxide on sulfonic acid terminated self-assembled monolayers

    SciTech Connect

    Rieke, P.C.; Marsh, B.D.; Wood, L.L.; Tarasevich, B.J.; Liu, J.; Song, L.; Fryxell, G.E. )

    1995-01-01

    The deposition kinetics of iron oxyhydroxide on sulfonic acid terminated self-assembled monolayers were studied. The thin films of FeOOH were formed on the substrates by thermal hydrolysis of millimolar aqueous solutions of Fe(NO[sub 3])[sub 3] at a pH of approximately 2.0. The thickness of the films was measured ellipsometrically at various times. Both Fe(NO[sub 3])[sub 3] and HNO[sub 3] concentrations were independently varied to provide varying degrees of solution supersaturation. Depending on these concentrations, an induction time was observed before film growth commenced. The correlation between supersaturation and induction time was modeled using classical nucleation theory. Very good agreement was observed regardless of whether supersaturation was varied via the concentration of Fe(NO[sub 3])[sub 3] or HNO[sub 3]. From these results an interfacial free energy for nucleation of 148 mJ/m[sup 2] was calculated. The critical nucleus species was identified as a tetrameric iron species by considering the order of nucleation. 49 refs., 11 figs., 1 tab.

  11. Complete mineralization of perfluorooctanoic acid (PFOA) by γ-irradiation in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhang, Ze; Chen, Jie-Jie; Lyu, Xian-Jin; Yin, Hao; Sheng, Guo-Ping

    2014-12-01

    Decomposition of perfluorooctanoic acid (C7F15COOH, PFOA) has been gaining increasing interests because it is a ubiquitous environmental contaminant and resistant to the most conventional treatment processes. In this work, the rapid and complete mineralization of PFOA and simultaneous defluorination were achieved by γ-ray irradiation with a 60Co source. The degradation rate of PFOA by γ-ray irradiation would be high, and a pseudo-first-order kinetic rate constant of 0.67 h-1 could be achieved in the N2 satured condition at pH 13.0. The experimental results and quantum chemical calculation confirmed that two radicals, i.e., hydroxyl radical (.OH) and aqueous electrons (eaq-), were responsible for the degradation of PFOA, while only either eaq- or .OH might not be able to accomplish complete mineralization of PFOA. The synergistic effects of .OH and eaq- involved in the cleavage of C-C and C-F bonds, and therefore complete mineralization of PFOA were achieved. The intermediate products were identified and the degradation pathway was also proposed. The results of this study may offer a useful, high-efficient approach for complete mineralizing fluorochemicals and other persistent pollutants.

  12. [Mechanism of action of combined extremely weak magnetic field on aqueous solution of amino acid].

    PubMed

    Zhadin, M N; Bakharev, B V; Bobkova, N V

    2014-01-01

    The fundamental physical mechanisms of resonance action of an extremely weak (40 nT) alternating magnetic field at the cyclotron frequency combined with a weak (40 μT) static magnetic field, on living systems are analyzed in the present work. The experimental effects of such sort of magnetic fields were described in different papers: the very narrow resonant peaks in electrical conductivity of the aqueous solutions in the in vitro experiments and the biomedical in vivo effects on living animals of magnetic fields with frequencies tuned to some amino acids. The existing experimental in vitro data had a good repeatability in different laboratories and countries. Unfortunately, for free ions such sort of effects are absolutely impossible because the dimensions of an ion rotation radius should be measured by meters at room temperature and at very low static magnetic fields used in all the above experiments. Even for bound ions these effects should be also absolutely impossible from the positions of classic physics because of rather high viscosity of biological liquid media (blood plasma, cerebrospinal liquid, cytoplasm). Only modern quantum electrodynamics of condensed media opens the new ways for solving these problems. The proposed article is devoted to analysis of quantum mechanisms of these effects. PMID:25707253

  13. Complete mineralization of perfluorooctanoic acid (PFOA) by γ-irradiation in aqueous solution

    PubMed Central

    Zhang, Ze; Chen, Jie-Jie; Lyu, Xian-Jin; Yin, Hao; Sheng, Guo-Ping

    2014-01-01

    Decomposition of perfluorooctanoic acid (C7F15COOH, PFOA) has been gaining increasing interests because it is a ubiquitous environmental contaminant and resistant to the most conventional treatment processes. In this work, the rapid and complete mineralization of PFOA and simultaneous defluorination were achieved by γ-ray irradiation with a 60Co source. The degradation rate of PFOA by γ-ray irradiation would be high, and a pseudo-first-order kinetic rate constant of 0.67 h−1 could be achieved in the N2 satured condition at pH 13.0. The experimental results and quantum chemical calculation confirmed that two radicals, i.e., hydroxyl radical (·OH) and aqueous electrons (eaq−), were responsible for the degradation of PFOA, while only either eaq− or ·OH might not be able to accomplish complete mineralization of PFOA. The synergistic effects of ·OH and eaq− involved in the cleavage of C-C and C-F bonds, and therefore complete mineralization of PFOA were achieved. The intermediate products were identified and the degradation pathway was also proposed. The results of this study may offer a useful, high-efficient approach for complete mineralizing fluorochemicals and other persistent pollutants. PMID:25492109

  14. Lipase in biphasic alginate beads as a biocatalyst for esterification of butyric acid and butanol in aqueous media.

    PubMed

    Ng, Choong Hey; Yang, Kun-Lin

    2016-01-01

    Esterification of organic acids and alcohols in aqueous media is very inefficient due to thermodynamic constraints. However, fermentation processes used to produce organic acids and alcohols are often conducted in aqueous media. To produce esters in aqueous media, biphasic alginate beads with immobilized lipase are developed for in situ esterification of butanol and butyric acid. The biphasic beads contain a solid matrix of calcium alginate and hexadecane together with 5 mg/mL of lipase as the biocatalyst. Hexadecane in the biphasic beads serves as an organic phase to facilitate the esterification reaction. Under optimized conditions, the beads are able to catalyze the production of 0.16 mmol of butyl butyrate from 0.5 mmol of butyric acid and 1.5 mmol of butanol. In contrast, when monophasic beads (without hexadecane) are used, only trace amount of butyl butyrate is produced. One main application of biphasic beads is in simultaneous fermentation and esterification (SFE) because the organic phase inside the beads is very stable and does not leach out into the culture medium. SFE is successfully conducted with an esterification yield of 6.32% using biphasic beads containing iso-octane even though the solvent is proven toxic to the butanol-producing Clostridium spp. PMID:26672465

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

    DOEpatents

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

    1992-07-21

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

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

    DOEpatents

    King, C. Judson; Tung, Lisa A.

    1992-01-01

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

  17. Cation profiling of passive films on stainless steel formed in sulphuric and acetic acid by deconvolution of angle-resolved X-ray photoelectron spectra

    NASA Astrophysics Data System (ADS)

    Högström, Jonas; Fredriksson, Wendy; Edstrom, Kristina; Björefors, Fredrik; Nyholm, Leif; Olsson, Claes-Olof A.

    2013-11-01

    An approach for determining depth gradients of metal-ion concentrations in passive films on stainless steel using angle-resolved X-ray photoelectron spectroscopy (ARXPS) is described. The iterative method, which is based on analyses of the oxidised metal peaks, provides increased precision and hence allows faster ARXPS measurements to be carried out. The method was used to determine the concentration depth profiles for molybdenum, iron and chromium in passive films on 316L/EN 1.4432 stainless steel samples oxidised in 0.5 M H2SO4 and acetic acid diluted with 0.02 M Na2B4O7 · 10H2O and 1 M H2O, respectively. The molybdenum concentration in the film is pin-pointed to the oxide/metal interface and the films also contained an iron-ion-enriched surface layer and a chromium-ion-dominated middle layer. Although films of similar composition and thickness (i.e., about 2 nm) were formed in the two electrolytes, the corrosion currents were found to be three orders of magnitude larger in the acetic acid solution. The differences in the layer composition, found for the two electrolytes as well as different oxidation conditions, can be explained based on the oxidation potentials of the metals and the dissolution rates of the different metal ions.

  18. Aqueous Synthesis of Peptide Thioesters from Amino Acids and a Thiol Using 1,1‧-Carbonyldiimidazole

    NASA Astrophysics Data System (ADS)

    Weber, Arthur L.

    2005-10-01

    A new method was developed for the synthesis of peptide thioesters from free amino acids and thiols in water. This one-pot simple method involves two steps: (1) activation in water of an amino acid presumably as its N-carboxyanhydride (NCA) using 1,1‧-carbonyldiimidazole (CDI), and (2) subsequent condensation of the activated amino acid-NCA in the presence of a thiol. With this method citrulline peptide thioesters containing up to 10 amino acid residues were prepared in a single reaction. This aqueous synthetic method provides a simple way to prepare peptide thioesters for studies of peptide replication involving ligation of peptide thioesters on peptide templates. The relevance of peptide replication to the origin-of-life process is supported by previous studies showing that amino acid thioesters (peptide thioester precursors) can be synthesized under prebiotic conditions by reaction of small sugars with ammonia and a thiol.

  19. Conductometric and fluorometric studies of sodium dodecyl sulphate in aqueous solution and in the presence of amino acids

    NASA Astrophysics Data System (ADS)

    Ali, Anwar; Malik, Nisar Ahmad; Uzair, Sahar; Ali, Maroof

    2014-10-01

    The critical micelle concentration (CMC) of sodium dodecyl sulphate (SDS) in pure water and in the presence of amino acids (0.01, 0.02 and 0.03 mol kg-1), L-valine (Val) and L-leucine (Leu) was determined from conductometric and fluorometric methods using pyrene as luminescence probe. Depression in the CMC at low concentration of amino acids is attributed to the increased hydrophobic-hydrophobic interaction between the non-polar groups of the surfactant, while, at high concentration, amino acids bind strongly with the anion, DS-, head groups of SDS, thereby, delaying the micelle formation, resulting in increased CMC. A pronounced decrease in the CMC, while a marked increase in λ0+, with decrease in the solvated radius (rather than crystal radius) of the counterions is observed. Negative values of ΔG0m and ΔH0m indicate that micellisation of SDS in the presence of amino acids is thermodynamically spontaneous and exothermic. Highest negative value of ΔH0m in 0.01 m Val, with lowest CMC value, shows that 0.01 m aqueous Val is the most suitable medium favouring the micellisation of SDS. Decrease in I1/I3 from Val to Leu confirms the relative hydrophobicity of two amino acids. The observed values of the packing parameter, P, of SDS in water and in aqueous amino acids suggest that micelles formed are spherical in nature.

  20. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension using hydrophobically modified poly(acrylic acid).

    PubMed

    Chen, J; Chen, M C

    2011-01-01

    A series of hydrophobically modified poly(acrylic acid) (PAA), poly(2-phenoxyethyl acrylate-co-acrylic acid) (poly(PHEA-co-AA)), have been synthesized and characterized by Ubbelohde type viscometry, Nuclear Magnetic Resonance (1H NMR) spectrometry and Differential Scanning Calorimetry (DSC). The shear thinning Non-Newtonian fluid behavior of their aqueous solution and the dependence on pH and hydrophobic group contents were found through apparent viscosity and rheological property investigating. Decolourization performance in C. I. Vat Yellow 1 aqueous suspension was evaluated through visible absorbance data. Decolourization performance of hydrophobically associated polymer indicates two times better than that of PAA. The quantitative relationship was mainly studied. PMID:21866762

  1. Copper Catalyzed Sodium Tetraphenylborate, Triphenylborane, Diphenylborinic Acid and Phenylboronic Acid Decomposition Kinetic Studies in Aqueous Alkaline Solutions

    SciTech Connect

    Crawford, C.L.

    1999-03-15

    This work studied the kinetics of copper-catalyzed decomposition of tetraphenylborate, triphenylborane, diphenylborinic acid and phenylboronic acid (NaTPB, 3PB, 2PB and 1PB, respectively) in aqueous alkaline solution over the temperature range of 25 to 70 degrees C. The statistically designed test matrices added copper sulfate to maximum concentrations of 10 mg/L. The relative rates of decomposition increase in the order of NaTPB < 1PB {tilde} 3PB < 2PB. Dependence of decomposition on the amount of added copper increases in the order of 3PB {tilde} 2PB < 1PB {tilde} NaTPB. Activation energies ranged from 82 to 143 kJ/mole over the temperature range studied. Final decomposition products predominately involved benzene and phenol. All 3PB, 2PB and 1PB intermediate phenylborate species proved relatively stable (< 8 percent decomposition over {tilde} 500 h) towards thermal hydrolysis in 1.5 M NaOH when contained in carbon-steel vessels sealed under air at ambient temperature (23 - 25 degrees C) with no added copper. Measurable (> 10-7 Mh-1) thermal hydrolysis of the phenylborate species occurs at 55 to 70 degrees C in alkaline (0.6-2.3 M OH-, 2-4.7 M Na+) solution with no added copper. The experiments suggest an important role for oxygen in copper-catalyzed phenylborate decomposition. NaTPB decomposes promptly under anoxic conditions while 3PB, 2PB and 1PB decompose faster in aerobic solutions. Benzene and phenol form as the predominant end-products from alkaline copper catalysis in static systems sealed under air. Both 2PB and 1PB decompose with near equal rates and quantitatively produce phenol under flowing air-purge conditions at 25 to 60 degrees C. Mechanisms for copper-catalyzed phenylborate decomposition likely involve a redox process giving loss of a phenyl group from the phenylborate with reduction of cupric ion, or dephenylation by reduced cuprous ion involving a phenylated copper intermediate.

  2. Catalytic and stoichiometric bromination of aromatic compounds in aqueous trifluoroacetic acid in the presence of nitrogen-containing oxidizing agents

    SciTech Connect

    Cheprakov, A.V.; Makhon'kov, D.I.; Rodkin, M.A.; Beletskaya, I.P.

    1988-07-10

    The mono- and polybromination of benzene, halogenobenzenes, toluene, p-xylene, anisole, biphenyl, benzotrifluoride, benzoic acid, p-nitro- and p-carboxytoluene, p-methoxybenzonitrile, tetralin, and naphthalene were studied in trifluoroacetic acid and its aqueous solutions in systems containing stoichiometric amounts of bromine or alkali-metal bromide and stoichiometric or catalytic (in the presence of oxygen or air) amounts of nitrogen-containing oxidizing agent (nitrogen(IV) oxide, alkali-metal nitrate or nitrite). It is suggested that the brominating agent under the investigated conditions is nitryl bromide NO/sub 2/Br. Under the conditions of catalytic bromination anthracene is oxidized to anthraquinone with a preparative yield.

  3. [sup 31]P and [sup 27]Al NMR investigations of highly acidic, aqueous solutions containing aluminum and phosphorus

    SciTech Connect

    Mortlock, R.F.; Bell, A.T.; Radke, C.J. Univ. of California, Berkeley )

    1993-01-21

    [sup 31]P and [sup 27]Al NMR spectroscopies have been used to characterize acidic, aqueous solutions of orthophosphoric acid, aluminum chloride, and tetramethylammonium (TMA) hydroxide. The final compositions of the solutions range from 0.1 to 1 mol % P, 0.0 to 20 mol % HCl, P/Al = 0.1 to 20, and P/(TMA)[sub 2]O = 2 to 20. Soluble aluminophosphate cations form reactions of hexaaqua Al monomeric cations, [Al(H[sub 2]O)[sub 6

  4. Aqueous leaching of organic acids and dissolved organic carbon from various biochars prepared at different temperatures.

    PubMed

    Liu, Peng; Ptacek, Carol J; Blowes, David W; Berti, William R; Landis, Richard C

    2015-03-01

    Biochar has been used as a soil amendment, as a water treatment material, and for carbon (C) sequestration. Thirty-six biochars, produced from wood, agricultural residue, and manure feedstocks at different temperatures, were evaluated for the aqueous leaching of different forms of soluble C. The release of inorganic C (alkalinity), organic acids (OAs), and total dissolved organic C (DOC) was highly variable and dependent on the feedstock and pyrolysis temperature. The pH and alkalinity increased for the majority of samples. Higher pH values were associated with high-temperature (high-T) (600 and 700°C) biochars. Statistically significant differences in alkalinity were not observed between low-temperature (low-T) (300°C) and high-T biochars, whereas alkalinity released from wood-based biochar was significantly lower than from others. Concentrations of OAs and DOC released from low-T biochars were greater than from high-T biochars. The C in the OAs represented 1 to 60% of the total DOC released, indicating the presence of other DOC forms. The C released as DOC represented up to 3% (majority <0.1%) of the total C in the biochar. Scanning electron microscopy with energy dispersive X-ray spectroscopy showed the high-T biochars had a greater proportion of micropores. Fourier transform infrared spectroscopy showed that hydroxyl, aliphatic, and quinone were the predominant functional groups of all biochars and that the abundance of other functional groups was dependent on the feedstock. The release of DOC, especially bioavailable forms such as OAs, may promote growth of organisms and heavy metal complexation and diminish the potential effectiveness of various biochars for C sequestration. PMID:26023986

  5. Evidence for 13-carbon enrichment in oxalic acid via iron catalyzed photolysis in aqueous phase

    NASA Astrophysics Data System (ADS)

    Pavuluri, Chandra Mouli; Kawamura, Kimitaka

    2012-02-01

    To investigate the effect of photochemical aging on the stable carbon isotopic ratio (δ13C) of oxalic acid (OxA), a dominant organic species in atmospheric aerosols, we conducted a laboratory photolysis of OxA under H2O2-Fe3+(Fe2+)-UV system in aqueous phase and measured δ13C of remaining OxA. Our results showed that a significant photolysis of OxA occurred with OH radical but the isotopic fractionation of OxA was insignificant. In contrast, in the presence of Fe3+ (Fe2+), we found a significant enrichment of 13C in remaining OxA. We also found that kinetic isotope effect (KIE) of OxA largely depends on photochemical age (irradiation time) and concentration ratios of OxA to iron; 3.20 ± 0.49‰ (2.18 ± 1.18‰) and 21.62 ± 5.41‰ in 90 min and 180 min irradiation, in which OxA and Fe3+ (Fe2+) ratios were 50:1 and 200:1, respectively. The enrichment of 13C in remaining OxA was more significant during the photolysis catalyzed by Fe3+ (7‰) than by Fe2+ (3‰) in 90 min irradiation when OxA and iron ratios are the same (50:1). This study provides a laboratory evidence for the isotopic enrichment of 13C in OxA with photochemical aging. This approach is useful for better interpretation of atmospheric isotopic measurements in terms of the extent of atmospheric processing of aerosols.

  6. 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.

  7. The sodium-sulphur battery

    NASA Astrophysics Data System (ADS)

    Jones, I. W.

    1981-09-01

    The sodium-sulphur battery is considered as a candidate for electric vehicle and bulk storage applications markets estimated to exceed one billion pounds sterling globally by the turn of the century. The sodium-sulphur device offers five times the energy density of conventional batteries, potential cost reductions due to the use of cheap and readily available construction materials, and operates at the relatively low temperatures of 300-400 C. The cells have a solid electrolyte, made by sintering alumina containing 10% sodium oxide, while the electrodes are liquid at operating temperatures. Ceramic element lives in excess of 1000 cycles have been achieved. Attention is given such design details as the thermal and physical properties of glass/ceramic seals and current collector materials and structure.

  8. Quantifying uncertainties in sulphur and nitrogen deposition to wales, uk using the hull acid rain model (harm) within the generalised likelihood uncertainty estimation (glue) framework

    NASA Astrophysics Data System (ADS)

    Page, T.; Whyatt, D.; Beven, K.; Metcalfe, S.; Nicholson, J.

    2003-04-01

    The Hull Acid Rain Model (HARM) is a receptor orientated Lagrangian trajectory model used to represent the processes of emission, transformation and deposition of acidifying species. HARM employs a simplified representation of meteorological conditions. It has a coupled chemical scheme and includes a parameterisation of orographic enhancement which is believed to make a significant contribution to wet deposition in upland UK. An uncertainty analysis of the model using the Generalised Likelihood Uncertainty Estimation methodology (GLUE) is presented, as constrained on multiple observations at 25 sites across Wales, UK. The quantified uncertainty is used to investigate the effect of predictive uncertainty on critical load exceedance. The GLUE analysis comprised 100,000 model realisations from Monte Carlo sampling of pre-specified parameter ranges, which were evaluated on the basis of how well simulated fluxes matched those measured at all observation sites. Only 2101 simulations were deemed to produce adequate representations of the observed fluxes and were used to create weighted prediction bounds for each site. Overall, the uncertainty prediction bounds spanned the observed data satisfactorily for most sites, but there was a tendency for high rainfall sites to be overestimated and sites close to major source areas to be underestimated. For wet-deposited oxidised-N there was a systematic overestimation at the majority of sites. The overestimation of wet-deposited oxidised-N for Wales is in contrast to other regions of the UK, where it is underestimated. The predictive capability of HARM was tested with a ‘hindcast’ to 44 Welsh observation sites for 1984 by using the 2101 acceptable parameterizations for 1995 with a 1984 emissions inventory. The spatial pattern of model predictions was consistent between 1984 and 1995 leading to the conclusion that either: model structural change is required to improve HARMs ability to represent the spatial deposition pattern or

  9. Boronic acid-containing aminopyridine- and aminopyrimidinecarboxamide CXCR1/2 antagonists: Optimization of aqueous solubility and oral bioavailability.

    PubMed

    Schuler, Aaron D; Engles, Courtney A; Maeda, Dean Y; Quinn, Mark T; Kirpotina, Liliya N; Wicomb, Winston N; Mason, S Nicholas; Auten, Richard L; Zebala, John A

    2015-09-15

    The chemokine receptors CXCR1 and CXCR2 are important pharmaceutical targets due to their key roles in inflammatory diseases and cancer progression. We have previously identified 2-[5-(4-fluoro-phenylcarbamoyl)-pyridin-2-ylsulfanylmethyl]-phenylboronic acid (SX-517) and 6-(2-boronic acid-5-trifluoromethoxy-benzylsulfanyl)-N-(4-fluoro-phenyl)-nicotinamide (SX-576) as potent non-competitive boronic acid-containing CXCR1/2 antagonists. Herein we report the synthesis and evaluation of aminopyridine and aminopyrimidine analogs of SX-517 and SX-576, identifying (2-{(benzyl)[(5-boronic acid-2-pyridyl)methyl]amino}-5-pyrimidinyl)(4-fluorophenylamino)formaldehyde as a potent chemokine antagonist with improved aqueous solubility and oral bioavailability. PMID:26248802

  10. Optimization of polyphenol extraction from red grape pomace using aqueous glycerol/tartaric acid mixtures and response surface methodology.

    PubMed

    Makris, Dimitris P; Passalidi, Vassiliki; Kallithraka, Stamatina; Mourtzinos, Ioannis

    2016-01-01

    Grape pomace is a food industry waste containing a high burden of antioxidant polyphenols and several methodologies have been developed for their efficient extraction. However, a sustainable and environmentally friendly process should involve recovery means composed of benign, non-toxic solvents, such as tartaric acid and glycerol, which are natural food constituents. In this line, this study examined the extraction of polyphenols using aqueous tartaric acid/glycerol solutions. The aim was to assess the role of acid and glycerol concentration in the extraction yield, employing a Box-Behnken experimental design and response surface methodology. The results showed that solutions containing only glycerol (20%, w/v) are more suitable for retrieving polyphenols, flavonoids, and pigments from grape pomace, while tartaric acid exerted a negative effect in this regard, when tested at concentrations up to 2% (w/v). PMID:25806718

  11. Acid gas treating by aqueous alkanolamines. Annual report, January-December 1993

    SciTech Connect

    Sandall, O.C.; Rinker, E.B.; Ashour, S.

    1993-12-01

    The objective of the work is to investigate the simultaneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed thus far, density, viscosity, gas diffusivity, gas solubility, surface tension, and amine solution vapor pressure have been measured for aqueous MDEA, DEA, and MDEA/DEA mixtures over the temperature range 20 to 100 deg. C and for concentrations up to 50 weight %. A mathematical model, based on the penetration theory, for the simultaneous absorption (desorption) of CO2 and H2S into (from) aqueous solutions of MDEA and DEA has been developed.

  12. Sulphur Extraction at Bryan Mound

    SciTech Connect

    Kirby, Carolyn L; Lord, Anna C. Snider

    2015-08-01

    The Bryan Mound caprock was subjected to extens ive sulphur mining prior to the development of the Strategic Petroleum Reserve. Undoubtedl y, the mining has modified the caprock integrity. Cavern wells at Bryan Mound have been subject to a host of well integr ity concerns with many likely compromised by the cavernous capro ck, surrounding corrosive environment (H 2 SO 4 ), and associated elevated residual temperatures al l of which are a product of the mining activities. The intent of this study was to understand the sulphur mining process and how the mining has affected the stability of the caprock and how the compromised caprock has influenced the integrity of the cavern wells. After an extensiv e search to collect pert inent information through state agencies, literature sear ches, and the Sandia SPR librar y, a better understanding of the caprock can be inferred from the knowledge gaine d. Specifically, the discovery of the original ore reserve map goes a long way towards modeling caprock stability. In addition the gained knowledge of sulphur mining - subs idence, superheated corrosive wa ters, and caprock collapse - helps to better predict the post mi ning effects on wellbore integrity. This page intentionally left blank

  13. Lanthanide triflates as water-tolerant Lewis acids. Activation of commercial formaldehyde solution and use in the aldol reaction of silyl enol ethers with aldehydes in aqueous media

    SciTech Connect

    Kobayashi, Shue; Hachiya, Iwao

    1994-07-01

    The catalytic effects of lanthanide triflates in the hydroxymethylation and the aldol reaction of silyl enol ethers (w/aldehydes). The rare earth triflates served as Lewis acid catalysts in the aqueous reaction medium.

  14. An analytical scheme for determining forms of sulphur in oil shales and associated rocks

    USGS Publications Warehouse

    Tuttle, M.L.; Goldhaber, M.B.; Williamson, D.L.

    1986-01-01

    An analytical scheme for determining various forms of sulphur in oil shales and associated rocks is presented. Acid-soluble sulphate, sulphur contained in monosulphide and in disulphide minerals, and organically-bound sulphur are all quantitatively recovered as separate fractions. Finely-ground oil-shale samples are treated in an inert atmosphere with 6M hydrochloric acid to dissolve the acid-soluble sulphate minerals and form H2S from the decomposition of monosulphide minerals. The acid-soluble sulphate is precipitated as barium sulphate and the H2S is collected and weighed as silver sulphide. Disulphide minerals in the solid residue from the acid treatment are reduced by an acidified Cr(II) solution in an inert atmosphere, releasing the sulphide as H2S. The H2S is collected as silver sulphide. An Eschka fusion oxidizes and solubilizes all sulphur remaining within the Cr(II)-treated residue. This sulphate represents organically-bound sulphur and is collected as barium sulphate. The analytical procedures have been verified by using 57Fe Mo??ssbauer spectroscopy. Good agreement between the chemical and Mo??ssbauer data substantiated the sequential removal of the forms of sulphur and also demonstrated the ability of Mo??ssbauer spectroscopy to determine the absolute quantities of iron present in specific minerals. ?? 1986.

  15. Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

    NASA Astrophysics Data System (ADS)

    Ryshetti, Suresh; Raghuram, Noothi; Rani, Emmadi Jayanthi; Tangeda, Savitha Jyostna

    2016-04-01

    Densities (ρ ) of (0.01 to 0.07) {mol}{\\cdot } {kg}^{-1} L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) {mol}{\\cdot } {kg}^{-1} solutions have been reported as a function of temperature at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure. The accurate density (ρ ) values are used to estimate the various parameters such as the apparent molar volume (V_{2,{\\upphi }}), the partial molar volume (V2^{∞}), the isobaric thermal expansion coefficient (α 2), the partial molar expansion (E2^{∞}), and Hepler's constant (partial 2V2^{∞}/partial T2)P. The Cosphere overlap model is used to understand the solute-solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler's constant (partial 2V2^{∞}/partial T2)_P is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.

  16. Removal characteristics of As(III) and As(V) from acidic aqueous solution by steel making slag.

    PubMed

    Oh, Chamteut; Rhee, Sungsu; Oh, Myounghak; Park, Junboum

    2012-04-30

    This study focused on the environmental risk of steel making slag itself, arsenic removal mechanism and re-leaching possibility of arsenic to aqueous state after the adsorption. The purpose of the study is to promote the use of steel making slag as a low-cost adsorbent for arsenic in aqueous system. Calcium was easily dissolved out from the slag and become the dominant substance in the leachate. Some of the calcium could form amorphous calcium carbonate in alkaline condition, and arsenic in the aqueous solution would be removed by being co-precipitated with or adsorbed onto the amorphous calcium carbonate. Most of the amorphous calcium carbonate containing arsenic would be bound to amorphous iron oxide of the slag. When the slag was used as an adsorbent for arsenic removal, a little amount of toxic chemicals were leached from the slag itself under pH 0.8 to 13.6. Also, 70-80% of arsenic laden on the slag was bound to amorphous iron oxide which would not easily desorb unless given a reducing and complexing condition. Showing 95-100% removal efficiency near initial pH 2, the slag, therefore, could be used as an appropriate adsorbent for eliminating arsenic in acidic aqueous solution. PMID:22349716

  17. Reactions of aqueous glucose solution over solid-acid Y-zeolite catalyst at 110-160 C

    SciTech Connect

    Lourvanij, K.; Rorrer, G.L. )

    1993-01-01

    Reactions of glucose with solid-acid Y-zeolite catalyst were studied to see if this heterogeneous system could produce oxygenated hydrocarbons by shape-selective, acid-catalyzed processes at fairly low temperatures. Experimentally, aqueous solutions of glucose (12 wt %) were reacted with HY-zeolite powder in a well-mixed batch reactor at temperatures ranging from 110 to 160 C and catalyst concentrations ranging from 2 to 20 g/150 ml. Unreacted glucose and oxygenated hydrocarbon products were measured by HPLC as a function of reaction time (0-24 h) and process conditions. Glucose conversions of 100% were obtained at 160 C after an 8-h reaction time. The apparent activation energy based on glucose conversion was 23.25 [plus minus] 0.40 kcal/mol. Several acid-catalyzed reactions were identified, including isomerization of glucose to fructose, partial dehydration of glucose to 5-(hydroxymethyl)furfural (HMF), rehydration and cleavage of HMF to formic acid and 4-oxo-pentanoic acid, and carbonization . Polymers of HMF and seven minor additional products in the lower molecular weight organic acids/aldehydes/ketones elution range were also isolated by HPLC. High yields of organic acids relative to HMF and lowered selectivity of HMF in the bulk phase relative to the homogeneous acid-catalyzed reaction suggests the possibility of molecular sieving reactions within the Y-zeolite in addition to reactions on the outer surface of the Y-zeolite particle.

  18. Thermodynamic studies of ionic hydration and interactions for amino acid ionic liquids in aqueous solutions at 298.15 K.

    PubMed

    Dagade, Dilip H; Madkar, Kavita R; Shinde, Sandeep P; Barge, Seema S

    2013-01-31

    Amino acid ionic liquids are a special class of ionic liquids due to their unique acid-base behavior, biological significance, and applications in different fields such as templates in synthetic chemistry, stabilizers for biological macromolecules, etc. The physicochemical properties of these ionic liquids can easily be altered by making the different combinations of amino acids as anion along with possible cation modification which makes amino acid ionic liquids more suitable to understand the different kinds of molecular and ionic interactions with sufficient depth so that they can provide fruitful information for a molecular level understanding of more complicated biological processes. In this context, volumetric and osmotic coefficient measurements for aqueous solutions containing 1-ethyl-3-methylimidazolium ([Emim]) based amino acid ionic liquids of glycine, alanine, valine, leucine, and isoleucine are reported at 298.15 K. From experimental osmotic coefficient data, mean molal activity coefficients of ionic liquids were estimated and analyzed using the Debye-Hückel and Pitzer models. The hydration numbers of ionic liquids in aqueous solutions were obtained using activity data. Pitzer ion interaction parameters are estimated and compared with other electrolytes reported in the literature. The nonelectrolyte contribution to the aqueous solutions containing ionic liquids was studied by calculating the osmotic second virial coefficient through an application of the McMillan-Mayer theory of solution. It has been found that the second osmotic virial coefficient which includes volume effects correlates linearly with the Pitzer ion interaction parameter estimated independently from osmotic data as well as the hydrophobicity of ionic liquids. The enthalpy-entropy compensation effect, explained using the Starikov-Nordén model of enthalpy-entropy compensation, and partial molar entropy analysis for aqueous [Emim][Gly] solutions are made by using experimental Gibb

  19. Amino acid composition, antinutrients and allergens in the peanut protein fraction obtained by an aqueous enzymatic process.

    PubMed

    Latif, S; Pfannstiel, J; Makkar, H P S; Becker, K

    2013-01-01

    Enzyme-assisted aqueous extraction (EAE) of peanut kernel was used to extract oil and protein. The aqueous fraction (AF) obtained by EAE had a better essential amino acid profile than the residues obtained by solvent extraction (Rs) and cold pressing (Rc). No major difference in the trypsin inhibitor activity among AF, Rs and Rc was observed; however, the trypsin inhibitor activity was drastically reduced in the residue obtained after EAE. AF was subjected to MALDI-TOF/MS, revealing it to be rich in peptides (107) with molecular masses from m/z 700 to 2369Da. AF had an extremely low phytate content and was rich in peptides, which could be used as a food supplement. ESI-MS/MS data were used for the identification of major peanut allergens, viz., Ara h1, h3, h6-8. Their allergenic potential needs to be established. PMID:23017415

  20. Theoretical study of the hydrolysis of ethyl benzoate in acidic aqueous solution using the QM/MC/FEP method

    NASA Astrophysics Data System (ADS)

    Kaweetirawatt, Thanayuth; Kokita, Yohei; Iwai, Shiho; Sumimoto, Michinori; Hori, Kenji

    2012-09-01

    The hydrolysis of ethyl benzoate in acidic condition was theoretically studied for models with two (2W) or three water (3WA) molecules at the B3LYP/6-311++G(d,p) levels of theory. Activation free energy of solvation in aqueous solution (ΔG‡cal) was calculated using the QM/MC/FEP method. The value of the 2W model in aqueous solution was calculated to be smaller by more than 5.0 kcal mol-1 than the observed value (26.0 kcal mol-1 at 298 K). The position of the third water molecule in the 3WA model plays an essential role in producing the ΔG‡cal value (26.4 kcal mol-1) consistent with the experimental value.

  1. Steam reforming of commercial ultra-low sulphur diesel

    NASA Astrophysics Data System (ADS)

    Boon, Jurriaan; van Dijk, Eric; de Munck, Sander; van den Brink, Ruud

    Two main routes for small-scale diesel steam reforming exist: low-temperature pre-reforming followed by well-established methane steam reforming on the one hand and direct steam reforming on the other hand. Tests with commercial catalysts and commercially obtained diesel fuels are presented for both processes. The fuels contained up to 6.5 ppmw sulphur and up to 4.5 vol.% of biomass-derived fatty acid methyl ester (FAME). Pre-reforming sulphur-free diesel at around 475 °C has been tested with a commercial nickel catalyst for 118 h without observing catalyst deactivation, at steam-to-carbon ratios as low as 2.6. Direct steam reforming at temperatures up to 800 °C has been tested with a commercial precious metal catalyst for a total of 1190 h with two catalyst batches at steam-to-carbon ratios as low as 2.5. Deactivation was neither observed with lower steam-to-carbon ratios nor for increasing sulphur concentration. The importance of good fuel evaporation and mixing for correct testing of catalysts is illustrated. Diesel containing biodiesel components resulted in poor spray quality, hence poor mixing and evaporation upstream, eventually causing decreasing catalyst performance. The feasibility of direct high temperature steam reforming of commercial low-sulphur diesel has been demonstrated.

  2. Equilibrium phase diagrams of aqueous mixtures of malonic acid and sulfate/ammonium salts.

    PubMed

    Salcedo, Dara

    2006-11-01

    Tropospheric aerosols are usually complex mixtures of inorganic and organic components. Although the thermodynamic properties of inorganic aerosols have been widely studied, the effect of organics on such properties is still under discussion. In this study, solubility in water, water activity (a(w)) of aqueous solutions, deliquescence relative humidity (DRH), eutonic composition, and eutonic DRH were determined for bulk mixtures of malonic acid (MA) with ammonium sulfate (AS) and ammonium bisulfate (ABS) at 25 degrees C over the full range of composition (from 0 wt % to the solubility limit of the mixture components). The data were used to construct equilibrium phase diagrams, which show the phase of the mixtures as a function of total composition, dry mixture composition, water content, and ambient relative humidity (RH). This work complements previous reports on the thermodynamic properties of AS/MA mixtures because the range of concentrations investigated is larger than in any other published single study. On the other hand, this is the first report on the a(w), deliquescence, and water absorption of ABS/MA mixtures. The eutonic composition for AS/MA mixtures was found to be 66.8 MA dry wt % (MA dry wt % = MA mass x 100/(AS mass + MA mass) with a DRH of 0.437. The eutonic composition for the ABS/MA mixtures was lower than for the AS/MA mixtures: 20.9 MA dry wt % with a DRH of 0.327. Measured a(w) of liquid AS/MA and ABS/MA solutions is compared with an extended Zdanovskii-Stokes-Robinson expression, obtaining a good agreement (error < 5-6%). The expression was used to predict water uptake of mixtures and might be useful to interpret particle hygroscopic growth experiments. Comparison of the AS/MA and ABS/MA systems indicates that ABS reduces the DRH and enhances water uptake, relative to mixtures with AS. The results confirm that ambient particles containing sulfate and water-soluble organic compounds can remain liquid or partially liquid at very low ambient RH

  3. Removal and recovery of furfural, 5-hydroxymethylfurfural, and acetic acid from aqueous solutions using a soluble polyelectrolyte.

    PubMed

    Carter, Brian; Gilcrease, Patrick C; Menkhaus, Todd J

    2011-09-01

    In the cellulosic ethanol process, furfural, 5-hydroxymethylfurfural (HMF), and acetic acid are formed during the high temperature acidic pretreatment step needed to convert biomass into fermentable sugars. These compounds can inhibit cellulase enzymes and fermentation organisms at relatively low concentrations (≥ 1 g/L). Effective removal of these inhibitory compounds would allow the use of more severe pretreatment conditions to improve sugar yields and lead to more efficient fermentations; if recovered and purified, they could also be sold as valuable by-products. This study investigated the separation of aldhehydes (furfural and HMF) and organic acid (acetic acid) inhibitory compounds from simple aqueous solutions by using polyethyleneimene (PEI), a soluble cationic polyelectrolyte. PEI added to simple solutions of each inhibitor at a ratio of 1 mol of functional group to 1 mol inhibitor removed up to 89.1, 58.6, and 81.5 wt% of acetic acid, HMF, and furfural, respectively. Furfural and HMF were recovered after removal by washing the polyelectrolyte/inhibitor complex with dilute sulfuric acid solution. Recoveries up to 81.0 and 97.0 wt% were achieved for furfural and HMF, respectively. The interaction between PEI and acetic acid was easily disrupted by the addition of chloride ions, sulfate ions, or hydroxide ions. The use of soluble polymers for the removal and recovery of inhibitory compounds from biomass slurries is a promising approach to enhance the efficiency and economics of an envisioned biorefinery. PMID:21455937

  4. Curcumin-cysteine and curcumin-tryptophan conjugate as fluorescence turn on sensors for picric Acid in aqueous media.

    PubMed

    Gogoi, Bedanta; Sen Sarma, Neelotpal

    2015-06-01

    Rapid detection of picric acid in real sample is of outmost importance from the perspective of health, safety, and environment. In this study, a very simple and cost-effective detection of picric acid is accomplished by developing a couple of biobased conjugates curcumin-cysteine (CC) and curcumin-tryptophan (CT), which undergo efficient fluorescence turn on toward picric acid in aqueous media. Both the probes experience about 26.5-fold fluorescence enhancements at 70 nM concentration of the analyte. Here, the fluorescence turn on process is governed by the aggregation induced emission, which is induced from the electrostatic interaction between the conjugates with picric acid. The detection limit of CC and CT are about 13.51 and 13.54 nM of picric acid, respectively. Importantly, both the probes exhibit high selectivity and low interference of other analogues toward the detection of picric acid. In addition, the probes are highly photostable, show low response time and are practically applicable for sensing picric acid in real environmental samples, which is the ultimate goal of this work. PMID:25955402

  5. Behavior of transplutonium elements on ion-exchange materials in mixed aqueous-organic solutions of mineral acids

    SciTech Connect

    Guseva, L.I.; Tikhomirov, G.S.; Stepushkina, V.V.

    1987-03-01

    Systematic studies are reported on the behavior of transplutonium elements (TPE) on cation-exchange and anion-exchange materials in mixed aqueous-organic solutions of mineral acids (HClO/sub 4/, HCl, HNO/sub 3/, H/sub 2/SO/sub 4/, H/sub 3/PO/sub 4/) as affected by solution composition, nature of acid, and nature of organic solvent. With all these acids, replacing most of the water by alcohol increases the TPE uptake on the ion exchangers, and the effect occurs for the cation exchangers at lower contents of the organic component. Optimum conditions have been identified for concentrating and separating TPE from numerous elements. The most effective system consists of anion exchanger with HNO/sub 3/ and alcohol.

  6. Recovery of transplutonium elements from aqueous and water-ethanol solutions of sulfuric acid and their separation from other actinides

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1988-05-01

    The behavior of Am, Cm, Bk, Cf, Es, and other actinides, as well as Zr, on anion and cation exchangers in aqueous and water-ethanol solutions of sulfuric acid as a function of the various components of the solution has been investigated. It has been discovered that the presence of ethanol in sulfuric acid solutions causes an increase in the distribution coefficients both on cation exchangers and on anion exchangers. The possibility of the use of ion exchangers for the preconcentration and separation of transplutonium elements from U, Np, Pu, Zr, and other elements which form strong complexes with sulfate ions over a broad range of concentrations of sulfuric acid has been demonstrated.

  7. Simultaneous determination of nitric acid and uranium concentrations in aqueous solution from measurements of electrical conductivity, density, and temperature

    SciTech Connect

    Spencer, B.B.

    1991-01-01

    Nuclear fuel reprocessing plants handle aqueous solutions of nitric acid and uranium in large quantities. Automatic control of process operations requires reliable measurements of these solutes concentration, but this is difficult to directly measure. Physical properties such as solution density and electrical conductivity vary with solute concentration and temperature. Conductivity, density and temperature can be measured accurately with relatively simple and inexpensive devices. These properties can be used to determine solute concentrations will good correlations. This paper provides the appropriate correlations for solutions containing 2 to 6 Molar (M) nitric acid and 0 to 300 g/L uranium metal at temperatures from 25--90{degrees}C. The equations are most accurate below 5 M nitric acid, due to a broad maximum in the conductivity curve at 6 M. 12 refs., 9 figs., 6 tabs.

  8. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part II. Recovery of Ammonia from Sour Waters

    SciTech Connect

    Poole, L.J.; King, C.J.

    1990-03-01

    Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, SUCCiOlC acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility of lactic acid and the tendency of the acid to self-associate. The separate recovery of ammonia and acid gases from sour waters can be achieved by combining steam-stripping of the acid gases with simultaneous removal of ammonia by extraction with a liquid cation exchanger. The use of di-2,4,4-trimethylpentyl phosphinic acid as the liquid cation exchanger is explored in this work. Batch extraction experiments were carried out to measure the equilibrium distribution ratio of ammonia between an aqueous buffer solution and an organic solution of the phosphinic acid (0.2N) in Norpar 12. The concentration

  9. Trivalent chromium removal from aqueous solutions by a sol–gel synthesized silica adsorbent functionalized with sulphonic acid groups

    SciTech Connect

    Gomez-Gonzalez, Sergio Efrain; Carbajal-Arizaga, Gregorio Guadalupe; Manriquez-Gonzalez, Ricardo; De la Cruz-Hernandez, Wencel; Gomez-Salazar, Sergio

    2014-11-15

    Highlights: • Corpuscular sulphonic acid-functionalized silica holds improved uptake of chromium. • Mesopores on adsorbent facilitate (CH{sub 3}COO){sub 2}Cr{sup +} ion uptake on sulphonate sites. • Formation of chromium acetate sulphonate complex proposed from XPS results. • Fixed bed chromium uptake results suggest potential industrial use. - Abstract: A high capacity hybrid silica adsorbent was synthesized via sol–gel processing with sulphonic acid groups as trivalent chromium complex ions chelators from aqueous solutions. The synthesis included co-condensation of tetraethoxysilane (TEOS) with 3-(mercaptopropyl)trimethoxysilane (MPS), and oxidation of thiol to sulphonic acid groups. Chromium uptake kinetic, batch and fixed-bed experiments were performed to assess the removal of this metal from aqueous solutions. {sup 13}C, {sup 29}Si CPMAS NMR, FTIR, XPS were used to characterize the adsorbent structure and the nature of chromium complexes on the adsorbent surface. Chromium maximum uptake was obtained at pH 3 (72.8 mg/g). Elemental analysis results showed ligand density of 1.48 mmol sulphonic groups/g. About 407 mL of Cr(III) solution (311 mg/L) were treated to breakthrough point reaching ≤0.06 mg/L at the effluent. These results comply with USEPA regulation for chromium concentration in drinking water (≤0.1 mg/L). The adsorbent shows potential to be used in chromium separations to the industrial level.

  10. Acid gas treating by aqueous alkanolamines. Annual report, July-December 1992

    SciTech Connect

    Sandall, O.C.; Rinker, E.B.; Tamimi, A.; Davis, R.A.; Oelschlager, D.W.

    1992-12-01

    The objective of the work is to investigate the simultaneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed thus far models have been developed for single gas (either H2S or CO2) absorption into a single amine solution (MDEA or DEA). Density and viscosity measurements have been made for aqueous MDEA, DEA and MDEA/DEA mixtures over the temperature range 20 to 100 C and for concentrations up to 50 weight %.

  11. Capillary electrophoresis of some free fatty acids using partially aqueous electrolyte systems and indirect UV detection. Application to the analysis of oleic and linoleic acids in peanut breeding lines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study has shown for the first time the suitability of CE with a partially aqueous electrolyte system for the analysis of free fatty acids (FFA's) in small portions of single peanut seeds. The partially aqueous electrolyte system consisted of 40 mM Tris, 2.5 mM adenosine-5'-monophosphate (AMP) ...

  12. Extractable sulphate-sulphur, total sulphur and trace-element determinations in plant material by flow injection analysis

    SciTech Connect

    Heanes, D.L. )

    1990-01-01

    A rapid, accurate and reproducible procedure for determining total sulphur(S) and trace elements (copper, zinc, manganese and iron) in plant material is described. Plant material is digested in culture tubes with a mixture of nitric and perchloric acids containing ammonium metavanadate and calcium chloride. In the acid digest, concentrations of total-S as sulphate are determined by turbidimetry and trace-elements by flame atomic absorption spectrophotometry using flow injection analysis. The results for a range of plant materials compare well with those obtained by conventional procedures for the same elements. The microprocessor controlled digestion and multielement assay procedure described here offers improved laboratory efficiencies in materials, time and cost effectiveness. The techniques should be particularly useful when plant tissues are in limited supply.

  13. Chemiluminescence studies between aqueous phase synthesized mercaptosuccinic acid capped cadmium telluride quantum dots and luminol-H2O2.

    PubMed

    Kaviyarasan, Kulandaivelu; Anandan, Sambandam; Mangalaraja, Ramalinga Viswanathan; Asiri, Abdullah M; Wu, Jerry J

    2016-08-01

    Mercaptosuccinic acid capped Cadmium telluride quantum dots have been successfully synthesized via aqueous phase method. The products were well characterized by a number of analytical techniques, including FT-IR, XRD, HRTEM, and a corrected particle size analysis by the statistical treatment of several AFM measurements. Chemiluminescence experiments were performed to explore the resonance energy transfer between chemiluminescence donor (luminol-H2O2 system) and acceptor CdTe QDs. The combination of such donor and acceptor dramatically reduce the fluorescence while compared to pristine CdTe QDs without any exciting light source, which is due to the occurrence of chemiluminescence resonance energy transfer (CRET) processes. PMID:27131144

  14. Chemiluminescence studies between aqueous phase synthesized mercaptosuccinic acid capped cadmium telluride quantum dots and luminol-H2O2

    NASA Astrophysics Data System (ADS)

    Kaviyarasan, Kulandaivelu; Anandan, Sambandam; Mangalaraja, Ramalinga Viswanathan; Asiri, Abdullah M.; Wu, Jerry J.

    2016-08-01

    Mercaptosuccinic acid capped Cadmium telluride quantum dots have been successfully synthesized via aqueous phase method. The products were well characterized by a number of analytical techniques, including FT-IR, XRD, HRTEM, and a corrected particle size analysis by the statistical treatment of several AFM measurements. Chemiluminescence experiments were performed to explore the resonance energy transfer between chemiluminescence donor (luminol-H2O2 system) and acceptor CdTe QDs. The combination of such donor and acceptor dramatically reduce the fluorescence while compared to pristine CdTe QDs without any exciting light source, which is due to the occurrence of chemiluminescence resonance energy transfer (CRET) processes.

  15. UV Irradiation and Humic Acid Mediate Aggregation of Aqueous Fullerene (nC60) Nanoparticles

    EPA Science Inventory

    The transport and fate of engineered nanomaterials is affected by multiple environmental factors, including sunlight and natural organic matter. In this study, the initial aggregation kinetics of aqueous fullerene (nC60) nanoparticles before and after UVA irradiation was investig...

  16. Robust Structure and Reactivity of Aqueous Arsenous Acid-Platinum(II) Anticancer Complexes**

    PubMed Central

    Miodragović, Ðenana U.; Quentzel, Jeremy A.; Kurutz, Josh W.; Stern, Charlotte L.; Ahn, Richard W.; Kandela, Irawati; Mazar, Andrew; O’Halloran, Thomas V.

    2014-01-01

    The first molecular adducts of platinum and arsenic based anticancer drugs - arsenoplatins - show unanticipated structure, substitution chemistry, and cellular cytotoxicity. The PtII-AsIII bonds in these complexes are stable in aqueous solution and strongly influence the lability of the trans ligand. PMID:24038962

  17. Structural morphology of orthorhombic sulphur

    NASA Astrophysics Data System (ADS)

    Hartman, P.

    1984-10-01

    Using an interatomic potential function specific surface energies, attachment energies and slice energies have been calculated for 7 F faces and 18 S faces of orthorhombic sulphur. These energies are compared with statistical parameters ( P values) for the frequency of occurrence of these faces on natural sulphur. It is found that P values are not correlated with the specific surface energies, except for the most important F faces. There is a positive correlation ( r=0.881) with the surface energy per mol although this quantity has no physical meaning. It is supposed that an S face is due to alternating periods of dissolution (or evaporation) and growth, so that it occurs as a narrow face on the site of a previous edge. An excellent correlation ( r=0.951) is found between the P value of an S face and a quantity P 1 P 2ξ h, where P 1 and P 2 are the P values of neighbouring faces that constitute the S face, ξ is proportional to the slice energy and h a distance determined by the interfacial angles of the three faces. This process should hold for the morphological development of any mineral, provided that no face-specific adsorption of cosolutes occurs.

  18. Selective Chemical Conversion of Sugars in Aqueous Solutions without Alkali to Lactic Acid Over a Zn-Sn-Beta Lewis Acid-Base Catalyst

    NASA Astrophysics Data System (ADS)

    Dong, Wenjie; Shen, Zheng; Peng, Boyu; Gu, Minyan; Zhou, Xuefei; Xiang, Bo; Zhang, Yalei

    2016-05-01

    Lactic acid is an important platform molecule in the synthesis of a wide range of chemicals. However, in aqueous solutions without alkali, its efficient preparation via the direct catalysis of sugars is hindered by a side dehydration reaction to 5-hydroxymethylfurfural due to Brønsted acid, which originates from organic acids. Herein, we report that a previously unappreciated combination of common two metal mixed catalyst (Zn-Sn-Beta) prepared via solid-state ion exchange synergistically promoted this reaction. In water without a base, a conversion exceeding 99% for sucrose with a lactic acid yield of 54% was achieved within 2 hours at 190 °C under ambient air pressure. Studies of the acid and base properties of the Zn-Sn-Beta zeolite suggest that the introduction of Zn into the Sn-Beta zeolite sequentially enhanced both the Lewis acid and base sites, and the base sites inhibited a series of side reactions related to fructose dehydration to 5-hydroxymethylfurfural and its subsequent decomposition.

  19. Selective Chemical Conversion of Sugars in Aqueous Solutions without Alkali to Lactic Acid Over a Zn-Sn-Beta Lewis Acid-Base Catalyst.

    PubMed

    Dong, Wenjie; Shen, Zheng; Peng, Boyu; Gu, Minyan; Zhou, Xuefei; Xiang, Bo; Zhang, Yalei

    2016-01-01

    Lactic acid is an important platform molecule in the synthesis of a wide range of chemicals. However, in aqueous solutions without alkali, its efficient preparation via the direct catalysis of sugars is hindered by a side dehydration reaction to 5-hydroxymethylfurfural due to Brønsted acid, which originates from organic acids. Herein, we report that a previously unappreciated combination of common two metal mixed catalyst (Zn-Sn-Beta) prepared via solid-state ion exchange synergistically promoted this reaction. In water without a base, a conversion exceeding 99% for sucrose with a lactic acid yield of 54% was achieved within 2 hours at 190 °C under ambient air pressure. Studies of the acid and base properties of the Zn-Sn-Beta zeolite suggest that the introduction of Zn into the Sn-Beta zeolite sequentially enhanced both the Lewis acid and base sites, and the base sites inhibited a series of side reactions related to fructose dehydration to 5-hydroxymethylfurfural and its subsequent decomposition. PMID:27222322

  20. Selective Chemical Conversion of Sugars in Aqueous Solutions without Alkali to Lactic Acid Over a Zn-Sn-Beta Lewis Acid-Base Catalyst

    PubMed Central

    Dong, Wenjie; Shen, Zheng; Peng, Boyu; Gu, Minyan; Zhou, Xuefei; Xiang, Bo; Zhang, Yalei

    2016-01-01

    Lactic acid is an important platform molecule in the synthesis of a wide range of chemicals. However, in aqueous solutions without alkali, its efficient preparation via the direct catalysis of sugars is hindered by a side dehydration reaction to 5-hydroxymethylfurfural due to Brønsted acid, which originates from organic acids. Herein, we report that a previously unappreciated combination of common two metal mixed catalyst (Zn-Sn-Beta) prepared via solid-state ion exchange synergistically promoted this reaction. In water without a base, a conversion exceeding 99% for sucrose with a lactic acid yield of 54% was achieved within 2 hours at 190 °C under ambient air pressure. Studies of the acid and base properties of the Zn-Sn-Beta zeolite suggest that the introduction of Zn into the Sn-Beta zeolite sequentially enhanced both the Lewis acid and base sites, and the base sites inhibited a series of side reactions related to fructose dehydration to 5-hydroxymethylfurfural and its subsequent decomposition. PMID:27222322

  1. Sulphur and skin: from Satan to Saddam!

    PubMed

    Leslie, K S; Millington, G W M; Levell, N J

    2004-04-01

    Since the dawn of time, Beelzebub has been showering fire and brimstone (sulphur) on tortured souls, but the cutaneous effects of this have been poorly described. Sulphur has also been used for centuries as a treatment for many skin conditions, such as fungal infections, scabies, psoriasis, eczema and acne. It has also been used extensively in cosmetic preparations and by cosmetic dermatologists treating conditions such as seborrhoeic eczema. Many natural bathing spas have high levels of sulphur; such balneology has been advocated by medical and cosmetic dermatologists as an effective treatment for cutaneous disorders for more than 500 years. Sulphur was often the active agent in many of the so-called 'patent medicines' that became popular in the mid-nineteenth century. Time has not withered medical practitioners' enthusiasm for sulphur. There are various reports in the medical literature of its current use. However sulphur treatment is not without its risks; a sulphur spring dermatitis has been described from a spa bath in Taiwan. With the satanic threat of bio-terrorism, some dermatologists may be treating the effects of contact with sulphur mustard all too soon. PMID:17147562

  2. Properties and use of sulphur dioxide.

    PubMed

    Usseglio-Tomasset, L

    1992-01-01

    This work analyses comprehensively the mechanism of action of sulphur dioxide in the process of wine-making. The use of sulphur dioxide is still a necessity for the storage and preservation of white wines. Nevertheless, the study of its physico-chemical and antimicrobial properties can make possible a large reduction of doses used even for white wines. PMID:1298642

  3. L-ascorbic acid quenching of singlet delta molecular oxygen in aqueous media: generalized antioxidant property of vitamin C

    SciTech Connect

    Chou, P.T.; Khan, A.U.

    1983-09-30

    L-ascorbic acid quenches singlet (/sup 1/..delta../sub g/) molecular oxygen in aqueous media (pH 6.8 for (/sup 1/H)H/sub 2/O and pD 7.2 for (/sup 2/H)D/sub 2/O) as measured directly by monitoring (0,0) /sup 1/..delta../sub g/ ..-->.. /sup 3/..sigma../sub g//sup -/ emission at 1.28 micron. Singlet oxygen was generated at room temperature in the solutions via photosensitization of sodium chrysene sulfonate; this sulfonated polycyclic hydrocarbon was synthesized to provide a water soluble chromophore inert to usual dye-ascorbate photobleaching. A marked isotope effect is found; k/sub Q//sup H/sub 2/O/ is 3.3 times faster than k/sub Q//sup D/sub 2/O/, suggesting ascorbic acid is chemically quenching singlet oxygen.

  4. Structural study of very thin anodic alumina films on silicon by anodization in citric acid aqueous solution.

    PubMed

    Kokonou, M; Nassiopoulou, A G; Giannakopoulos, K P; Boukos, N; Travlos, A

    2005-03-01

    The formation of thin alumina films on a silicon substrate by anodization in a mild acid, specifically in 1% wt citric acid aqueous solution, is investigated by transmission electron microscopy (TEM). We present a comparative study between two cases of starting material: pure aluminum and an alloy of aluminum with 1% silicon. In both cases the thickness of the Al layer was less than 50 nm. It was observed that under exactly the same conditions, in the first case the anodization was stopping before anodizing the whole film and a remaining non-anodized Al layer was always present, while in the second case, the Al layer was fully anodized, resulting in an alumina matrix with a very high density of silicon nanocrystals of uniform sizes embedded in it. In both cases the alumina film was compact and amorphous. PMID:15913255

  5. Kinetics of catalytic hydrogenation of 4-nitroaniline in aqueous solutions of propan-2-ol with acid or base additives

    NASA Astrophysics Data System (ADS)

    Kha, Nguen Tkhi Tkhu; Merkin, A. A.; Komarov, A. A.; Korpatenkov, D. O.; Lefedova, O. V.

    2014-04-01

    The effect of addition of acetic acid and sodium hydroxide to an aqueous azeotropic solution of propan-2-ol on the rate of 4-nitroaniline hydrogenation is studied. The base additive accelerates the apparent rate of nitro group reduction, while the presence of acetic acid slows the reaction rate. It is experimentally established that the rate of nitro group conversion calculated from the amount of reacted 4-nitroaniline exceeds the rate of hydrogen uptake from the gas phase in all of the studied solvents. Hydrogen bound by active sites of the catalyst surface is found to participate notably in the reactions. It is proved both experimentally and theoretically that strongly bound atomic forms of adsorbed hydrogen are most active in the reduction of the nitro group.

  6. A semi-quantitative approach for the rapid screening and mass profiling of naphthenic acids directly in contaminated aqueous samples.

    PubMed

    Duncan, Kyle D; Letourneau, Dane R; Vandergrift, Gregory W; Jobst, Karl; Reiner, Eric; Gill, Chris G; Krogh, Erik T

    2016-01-01

    We report the use of a direct sampling, online analytical approach for the determination of acid extractable naphthenic acids in complex aqueous samples, known as condensed phase membrane introduction mass spectrometry (CP-MIMS). The technique employs a capillary hollow fibre semi-permeable membrane probe configured for immersion into a pH adjusted sample. A continuously flowing methanol acceptor phase transfers naphthenic acids to an electrospray ionization source, operated in negative ion mode, whereupon they are analysed by mass spectrometry as [M-H](-) ions. High-resolution mass spectrometry is used to characterize the influence of sample pH on membrane transport of multiple components of complex naphthenic acid mixtures. We demonstrate the use of CP-MIMS for semi-quantitative analysis of real-world samples using selected ion monitoring and full scan mass spectra at unit mass resolution. The technique has also been employed to continuously monitor the temporal evolution in the mass profile and concentrations of individual naphthenic acid isomer classes in heterogeneous solutions during adsorption processes. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26757071

  7. Non-aqueous capillary electrophoresis for the analysis of acidic compounds using negative electrospray ionization mass spectrometry.

    PubMed

    Bonvin, Grégoire; Schappler, Julie; Rudaz, Serge

    2014-01-01

    Non-aqueous capillary electrophoresis (NACE) is an attractive CE mode, in which water solvent of the background electrolyte (BGE) is replaced by organic solvent or by a mixture of organic solvents. This substitution alters several parameters, such as the pKa, permittivity, viscosity, zeta potential, and conductivity, resulting in a modification of CE separation performance (i.e., selectivity and/or efficiency). In addition, the use of NACE is particularly well adapted to ESI-MS due to the high volatility of solvents and the low currents that are generated. Organic solvents reduce the number of side electrochemical reactions at the ESI tip, thereby allowing the stabilization of the ESI current and a decrease in background noise. All these features make NACE an interesting alternative to the aqueous capillary zone electrophoresis (CZE) mode, especially in combination with mass spectrometry (MS) detection. The aim of this work was to evaluate the use of NACE coupled to negative ESI-MS for the analysis of acidic compounds with two available CE-MS interfaces (sheath liquid and sheathless). First, NACE was compared to aqueous CZE for the analysis of several pharmaceutical acidic compounds (non-steroidal anti-inflammatory drugs, NSAIDs). Then, the separation performance and the sensitivity achieved by both interfaces were evaluated, as were the impact of the BGE and the sample composition. Finally, analyses of glucuronides in urine samples subjected to a minimal sample pre-treatment ("dilute-and-shoot") were performed by NACE-ESI-MS, and the matrix effect was evaluated. A 20- to 100-fold improvement in sensitivity was achieved using the NACE mode in combination with the sheathless interface and no matrix effect was observed regardless of the interfaces. PMID:24315358

  8. Gamma irradiation of isocitric and citric acid in aqueous solution: Relevance in prebiotic chemistry

    NASA Astrophysics Data System (ADS)

    Negrón-Mendoza, A.; Ramos-Bernal, S.

    2015-07-01

    The radiation chemistry of hydroxy acids like citric and isocitric acids is rather scarce, even though they are crucial compounds in biological systems and for food irradiation. The aim of this work is to study the radiolytic behavior of these acids focused on the interconversion induced by radiation of citric and isocitric acid into other members of the Krebs cycle. The results showed that among the products formed were succinic, malonic, malic and other acids related to metabolic pathways, and these results are correlated with its possible role in chemical evolution processes.

  9. Gamma irradiation of isocitric and citric acid in aqueous solution: Relevance in prebiotic chemistry

    SciTech Connect

    Negrón-Mendoza, A. Ramos-Bernal, S.

    2015-07-23

    The radiation chemistry of hydroxy acids like citric and isocitric acids is rather scarce, even though they are crucial compounds in biological systems and for food irradiation. The aim of this work is to study the radiolytic behavior of these acids focused on the interconversion induced by radiation of citric and isocitric acid into other members of the Krebs cycle. The results showed that among the products formed were succinic, malonic, malic and other acids related to metabolic pathways, and these results are correlated with its possible role in chemical evolution processes.

  10. Surface modification of alumina-coated silica nanoparticles in aqueous sols with phosphonic acids and impact on nanoparticle interactions.

    PubMed

    Pauly, Céline Schmitt; Genix, Anne-Caroline; Alauzun, Johan G; Sztucki, Michael; Oberdisse, Julian; Hubert Mutin, P

    2015-07-15

    It is often necessary to tailor nanoparticle (NP) interactions and their compatibility with a polymer matrix by grafting organic groups, but the commonly used silanization route offers little versatility, particularly in water. Herein, alumina-coated silica NPs in aqueous sols have been modified for the first time with low molecular-weight phosphonic acids (PAs) bearing organic groups of various hydrophobicities and charges: propyl, pentyl and octyl PAs, and two PAs bearing hydrophilic groups, either a neutral diethylene glycol (DEPA) or a potentially charged carboxylic acid (CAPA) group. The interactions and aggregation in the sols have been investigated using zeta potential measurements, dynamic light scattering, transmission electron microscopy, and small-angle scattering methods. The surface modification has been studied using FTIR and (31)P MAS NMR spectroscopies. Both high grafting density ρ and high hydrophobicity of the groups on the PAs induced aggregation, whereas suspensions of NPs grafted by DEPA remained stable up to the highest ρ. Unexpectedly, CAPA-modified NPs showed aggregation even at low ρ, suggesting that the carboxylic end group was also grafted to the surface. Surface modification of aqueous sols with PAs allows thus for the grafting of a higher density and a wider variety of organic groups than organosilanes, offering an increased control of the interactions between NPs, which is of interest for designing waterborne nanocomposites. PMID:26134150

  11. Determination of Arrhenius and Thermodynamic Parameters for the Aqueous Reaction of the Hydroxyl Radical with Lactic Acid

    SciTech Connect

    Leigh R. Martin; Stephen P. Mezyk; Bruce J. Mincher

    2009-01-01

    Lactic acid is a major component of the TALSPEAK process planned for use in the separation of trivalent lanthanide and actinide elements. This acid acts both as a buffer, and also to protect the actinide complexant from radiolytic damage. However, there is little kinetic information on the reaction of water radiolysis species with lactic acid, particularly under the anticipated process conditions of aerated aqueous solution at pH~3, where oxidizing reactions are expected to dominate. Here we have determined temperature-dependent reaction rate constants for the reactions of the hydroxyl radical with lactic acid and the lactate ion. For lactic acid this rate constant is given by the equation: ln k1 = (23.85 ± 0.19) – (1120 ± 54) / T, corresponding to an activation energy of 9.31 ± 0.45 kJ mol-1 and a room temperature reaction rate constant of (5.24 ± 0.09) x 108 M-1 s-1 (24.0oC). For the lactate ion, the temperature-dependent rate constant is given by: ln k2 = (24.83 ± 0.14) – (1295 ± 42) / T, for an activation energy of 10.76 ± 0.35 kJ mol-1 and a room temperature value of (7.77 ± 0.11) x 108 M-1 s-1 (22.2oC). These kinetic data have been combined with autotitration measurements to determine the temperature-dependent behavior of the lactic acid pKa value, allowing thermodynamic parameters for the acid dissociation to be calculated as ?Hº = -10.75 ± 1.77 kJ mol-1, ?Sº = -103.9 ± 6.0 J K-1 mol-1 and ?Gº = 20.24 ± 2.52 kJ mol-1 at low ionic strength.

  12. Fluorescent Ag nanoclusters prepared in aqueous poly(acrylic acid-co-maleic acid) solutions: a spectroscopic study of their excited state dynamics, size and local environment.

    PubMed

    Dandapat, Manika; Mandal, Debabrata

    2016-01-28

    Stable, fluorescent Ag nanoclusters were prepared in aqueous solutions of Na(+) salt of the carboxylate-rich polymer poly(acrylic acid-co-maleic acid) under brief spells of UV irradiation. The nanoclusters were nearly spherical, with diameters within 1.90 ± 0.50 nm, but displayed a prominent red edge excitation shift (REES) of fluorescence upon exciting within the visible absorption band, indicating heterogeneity of energy level distributions. Spectroscopic studies revealed that irrespective of whether the nanoclusters are excited in their UV or visible absorption bands, their fluorescence always ensues from the same manifold of emissive states, with a broad range of fluorescence lifetimes from ∼150 fs to 1 ns. PMID:26700465

  13. In-situ spectroscopic investigations of the redox behavior of poly(indole-5-carboxylic-acid) modified electrodes in acidic aqueous solutions.

    PubMed

    Talbi, H; Billaud, D; Louarn, G; Pron, A

    2001-03-01

    The oxidation of electrochemically grown poly(indole-5-carboxylic-acid) (P5CO2H) and its spectroscopic properties have been studied by in-situ spectroelectrochemical techniques. The purpose of this paper is to characterize the different modifications on the P5CO2H backbone, induced by the electrochemical oxidation in aqueous acidic solution. We have identified, on the basis of Raman spectra, the vibrational modes associated with neutral and oxidized segments of polymer. It was shown that at least three chemically and optically different species (perhaps other products too) are produced in different potential regimes upon oxidation of this polymer. The results obtained also indicate that the molecular properties of this conducting polymer are better revealed by in-situ resonant spectra than by ex-situ infrared and Raman studies. PMID:11300553

  14. Fast and highly-efficient removal of methylene blue from aqueous solution by poly(styrenesulfonic acid-co-maleic acid)-sodium-modified magnetic colloidal nanocrystal clusters

    NASA Astrophysics Data System (ADS)

    Song, Yu-Bei; Lv, Shao-Nan; Cheng, Chang-Jing; Ni, Guo-Li; Xie, Xiao-Wa; Huang, Wei; Zhao, Zhi-Gang

    2015-01-01

    Magnetic colloidal nanocrystal clusters (MCNCs) modified with different amounts of poly(4-styrenesulfonic acid-co-maleic acid) sodium (PSSMA) have been prepared through simple one-step solvothermal method for removal of methylene blue (MB) from aqueous solution. The prepared MCNCs are characterized by Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), nitrogen adsorption-desorption technique and dynamic light scattering (DLS). Moreover, effects of the solution pH, contact time, adsorbent dosage, ionic strength and initial dye concentration on MB adsorption onto the MCNCs are systematically investigated. The PSSMA-modified MCNCs show fast and highly-efficient MB removal capacity, which dramatically depends on the immobilization amounts of PSSMA, solution pH and adsorbent dosage. Their adsorption kinetics and isotherms exhibit that the kinetics and equilibrium adsorptions can be well-described by pseudo-second-order kinetic and Langmuir model, respectively. These magnetic nanocomposites, with high separation efficiency, low production cost and recyclable property, are promising as functional adsorbents for efficient removal of cationic organic pollutants from aqueous solution.

  15. Simultaneous removal of acid green 25 and mercury ions from aqueous solutions using glutamine modified chitosan magnetic composite microspheres.

    PubMed

    Tao, Xue; Li, Kun; Yan, Han; Yang, Hu; Li, Aimin

    2016-02-01

    In this current work, the magnetic composite microsphere containing glutamine modified chitosan and silica coated Fe3O4 nanoparticles (CS-Gln-MCM) has been successfully prepared and extensively characterized, which is a kind of biodegradable materials. CS-Gln-MCM shows enhanced removal efficiency for both acid green 25 (AG25), an amphoteric dye, and mercury ions (Hg(2+)) from water in the respective while measured pH range compared with chitosan magnetic composite microsphere (CS-MCM) without modification. It is due to the fact that the grafted amino acid provides a variety of additional adsorption active sites and diverse adsorption mechanisms are involved. In AG25 and Hg(2+) aqueous mixture, the modified adsorbents bear preferential adsorption for AG25 over Hg(2+) in strong acidic solutions ascribed to multiple interactions between AG25 and CS-Gln-MCM, such as hydrogen bonding and electrostatic interactions. While, in weak acidic conditions, an efficient simultaneous removal is observed for different adsorption effects involved in aforementioned two pollutants. Besides, CS-Gln-MCM illuminates not only short equilibrium time for adsorption of each pollutant less than 20.0 min but also rapid magnetic separation from water and efficient regeneration after saturated adsorption. Therefore, CS-Gln-MCM bears great application potentials in water treatment. PMID:26618263

  16. Surface crystallographic dependence of voltammetric oxidation of polyhydric alcohols and related systems at monocrystalline gold-acidic aqueous interfaces

    NASA Astrophysics Data System (ADS)

    Hamelin, Antoinette; Ho, Yeunghaw; Chang, Si-Chung; Gao, Xiaoping; Weaver, Michael J.

    1992-02-01

    The voltammetric oxidation in aqueous 0.1 Molar perchloric acid of four polyhydric alcohols, ethylene glycol, glycerol, meso-erythritol, and d-mannitol, on seven oriented gold surfaces is reported with the objective of assessing the role of surface crystallographic orientation on the catalytic electrooxidation of such poly-functional reactants. The automatically well-ordered nature of these gold surfaces has been scrutinized by in-situ scanning tunneling microscopy. In particular, the Au(221) and (533) faces were selected since they provide stepped surfaces, 4(111)-(111) and 4(111)-(100), respectively. The results are compared with corresponding data for simple unifunctional reactants, specifically for formic acid oxidation and with results reported previously for carbon monoxide oxidation. In contrast to the last reaction, the electrooxidation rates for both the polyhydric alcoholic and formic acid are greatest on Au(111), with Au(110) displaying unusually low activity. While formic acid electrooxidation is insensitive to the presence of monoatomic surface steps, the polyhydric alcohols (especially mannitol) are substantially less reactive on AU(221) and (533) relative to Au(111).

  17. Structural and vibrational investigation on species derived from the cyclamic acid in aqueous solution by using HATR and Raman spectroscopies and SCRF calculations

    NASA Astrophysics Data System (ADS)

    Brizuela, Alicia B.; Raschi, Ana B.; Castillo, María V.; Davies, Lilian; Romano, Elida; Brandán, Silvia A.

    2014-09-01

    In this study, aqueous solutions at different molar concentrations of sodium cyclamate in water were completely characterized by HATR (Horizontal Attenuated Total Reflectance) and Raman spectroscopies. The theoretical structures of cyclamate ion, the zwitterionic and neutral forms of the cyclamic acid and its dimer were optimized in gas and aqueous solution phases by using the hybrid B3LYP/6-31G* method. The solvent effects for the four species in aqueous solutions were simulated by using self-consistent reaction field (SCRF) calculations employing the integral equation formalism variant (IEFPCM) model. The complete assignments of the vibrational spectra of all the forms of cyclamic acid were performed taking into account the factor group analysis with the Scaled Quantum Mechanics Force Field (SQMFF) methodology. The existence of the zwitterionic and neutral forms of the cyclamic acid and its dimer in a solution of cyclamate in water is evidenced by characteristic bands in the HATR and Raman spectra. The dimerization of cyclamate in aqueous solution was previously reported by conductimetric method. The natural population analysis (NPA) and Merz-Kollman (MK) charges, molecular electrostatic potential (MEP), natural bond orbital (NBO) and atoms in molecules (AIM) calculations predict for all the species the principal donor and acceptor sites for the H bonds formation in aqueous solution. The SQM force fields for the cyclamate ion, the zwitterionic and neutral species of the cyclamic acid were obtained and their corresponding force constants in both phases were reported. Additionally, the solvation energies for those species were reported.

  18. Hybrid molecularly imprinted poly(methacrylic acid-TRIM)-silica chemically modified with (3-glycidyloxypropyl)trimethoxysilane for the extraction of folic acid in aqueous medium.

    PubMed

    de Oliveira, Fernanda Midori; Segatelli, Mariana Gava; Tarley, César Ricardo Teixeira

    2016-02-01

    In the present study a hybrid molecularly imprinted poly(methacrylic acid-trimethylolpropane trimethacrylate)-silica (MIP) was synthesized and modified with (3-glycidyloxypropyl)trimethoxysilane (GPTMS) with posterior opening of epoxy ring to provide hydrophilic properties of material in the extraction of folic acid from aqueous medium. The chemical and structural aggregates of hybrid material were characterized by means of Fourier Transform Infrared (FT-IR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TGA) and textural data. Selectivity data of MIP were compared to non-imprinted polymer (NIP) through competitive sorption studies in the presence of caffeine, paracetamol or 4-aminobenzamide yielding relative selectivity coefficients (k′) higher than one unit, thus confirming the selective character of MIP even in the presence of structurally smaller compounds than the folic acid. The lower hydrophobic sorption by bovine serum albumin (BSA) in the MIP as compared to unmodified MIP proves the hydrophilicity of polymer surface by using GPTMS with opening ring. Under acid medium(pH 1.5) the sorption of folic acid onto MIP from batch experiments was higher than the one achieved for NIP. Equilibrium sorption of folic acid was reached at 120 min for MIP, NIP and MIP without GPTMS and kinetic sorption data were well described by pseudo-second-order, Elovich and intraparticle diffusion models. Thus, these results indicate the existence of different binding energy sites in the polymers and a complex mechanism consisting of both surface sorption and intraparticle transport of folic acid within the pores of polymers. PMID:26652418

  19. Sensitization of the luminescence of europium and terbium ions by orotic acids in aqueous solutions

    SciTech Connect

    Davidenko, N.K.; Bukivskaya, G.A.

    1988-03-01

    The stability constants of the complexes of Eu/sup 3 +/ and Tb/sup 3 +/ with the dianions of orotic acid, 2-thioorotic acid, and 3-N-methylorotic acid have been determined at 20/sup 0/C and ..mu.. = 0.15 by a pH-potentiometric method. The influence of orotic acids on the luminescence properties of Eu/sup 3 +/ and Tb/sup 3 +/ has been studied. It has been shown as a result of a study of the excited states of orotic acid and its derivatives by a method based on the sensitized luminescence of the lanthanides that it is preferable to use the Tb/sup 3 +/ ion as an energy acceptor, since quenching of the luminescence by means of a charge-transfer process is observed in the complexes formed by the Eu/sup 3 +/ ion.

  20. Enrichment of the Amino Acid L-Isovaline by Aqueous Alteration on CI and CM Meteorite Parent Bodies

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Dworkin, Jason P.

    2009-01-01

    The distribution and enantiomeric composition of the 5-carbon (C(sub 5)) amino acids found in Cl-, CM-, and CR-type carbonaceous meteorites were investigated by using liquid chromatography fluorescence detection/TOF-MS coupled with o-phthaldialdehyde/Nacetyl- l-cysteine derivatization. A large L-enantiomeric excess (ee) of the a-methyl amino acid isovaline was found in the CM meteorite Murchison (L(sub ee) = 18.5 +/- 2.6%) and the Cl meteorite Orguell (L(sub ee) = 15.2 +/- 4.0%). The measured value for Murchison is the largest enantiomeric excess in any meteorite reported to date, and the Orgueil measurement of an isovaline excess has not been reported previously for this or any Cl meteorite. The L-isovaline enrichments in these two carbonaceous meteorites cannot be the result of interference from other C(sub 5) amino acid isomers present in the samples, analytical biases, or terrestrial amino acid contamination. We observed no L-isovaline enrichment for the most primitive unaltered Antarctic CR meteorites EET 92042 and QUE 99177. These results are inconsistent with UV circularly polarized light as the primary mechanism for L-isovaline enrichment and indicate that amplification of a small initial isovaline asymmetry in Murchison and Orgueil occurred during an extended aqueous alteration phase on the meteorite parent bodies. The large asymmetry in isovaline and other alpha-dialkyl amino acids found in altered Ct and CM meteorites suggests that amino acids delivered by asteroids, comets, and their fragments would have biased the Earth's prebiotic organic inventory with left-handed molecules before the origin of life.

  1. Long-term degradation study of hyaluronic acid in aqueous solutions without protection against microorganisms.

    PubMed

    Simulescu, Vasile; Kalina, Michal; Mondek, Jakub; Pekař, Miloslav

    2016-02-10

    The degradation of hyaluronan (HA) of different molecular weights (Mw 14.3, 267.2 and 1160.6 kDa, measured for fresh solutions, before degradation) was studied in aqueous solutions by SEC-MALLS determination of molecular mass, polydispersity and conformation parameters. The solutions were stored either at laboratory or refrigerator temperatures for two months. After this period the weight average molecular weight decreased by 90% for 14.3 kDa, 95% for 267.2 kDa and 71% for 1160.6 kDa hyaluronan (room temperature) or 5.6% for 14.3 kDa, 6.2% for 267.2 kDa and 7.7% for 1160.6 kDa hyaluronan (refrigerator temperature). The hyaluronan aqueous solutions studied did not contain sodium azide or other protectants against microorganisms, because the aim of our study was to assess the degradation in solutions to be used in medicine or cosmetics (without any compounds that are poisonous or toxic for the human body). The solvent used to prepare the samples was pure water. The polydispersity of all the samples remained unaltered during the entire degradation at both temperatures. This indicates a non-random mechanism of degradation. PMID:26686177

  2. Adsorption behavior of antimony(III) oxyanions on magnetite surface in aqueous organic acid environment

    NASA Astrophysics Data System (ADS)

    Mittal, Vinit K.; Bera, Santanu; Narasimhan, S. V.; Velmurugan, S.

    2013-02-01

    Antimony(III) adsorption is observed on magnetite (Fe3O4) surface under acidic and reducing condition through surface hydroxyl (SOH) groups bonding on Fe3O4 surface. Desorption of adsorbed Sb(III) is observed from Fe3O4 surface along with iron release in organic acid at 85 °C after 5 h of experiment. Tartaric acid (TA) shows minimum Sb(III) adsorption on Fe3O4 among the organic acid studied. The reason is TA having two sets of adjacent functional groups viz. Odbnd Csbnd OH and Csbnd OH which are responsible for the formation of five-membered bidendate chelate with Sb(III). Other oxyanions, cations or complexing agents along with TA influences the Sb(III) adsorption on Fe3O4. The surface of magnetite is modified by the addition of fatty acids viz. Lauric acid, benzoic acid to bind the Ssbnd OH groups present on the surface. This results in delaying the process of adsorption without changing the quantity of saturation adsorption of Sb(III) on Fe3O4 surface.

  3. Removal of dicyclohexyl acetic acid from aqueous solution using ultrasound, ozone and their combination.

    PubMed

    Kumar, Pardeep; Headley, John; Peru, Kerry; Bailey, Jon; Dalai, Ajay

    2014-01-01

    Naphthenic acids are a complex mixture of organic components, some of which include saturated alkyl-substituted cycloaliphatic carboxylic acids and acyclic aliphatic acids. They are naturally found in hydrocarbon deposits like oil sand, petroleum, bitumen and crude oil. In this study, the oxidation of a relatively high molecular weight naphthenic acid (Dicyclohexyl acetic acid) was investigated using ozonation, ultrasonication and hydrogen peroxide alone and their combinations. Effects on oxidation of dicyclohexyl acetic acid (DAA) were measured for different concentrations of ozone ranging between 0.7 to 3.3 mg L(-1) and pH in the range 6 to 10. Ultrasonication and hydrogen peroxide alone were not effective to oxidize dicyclohexyl acetic acid, but combining ultrasonication with H2O2 had a significant effect on oxidation of dicyclohexyl acetic acid with maximum removal reaching to 84 ± 2.2% with 81 ± 2.1% reduction in chemical oxygen demand (COD). Synergistic effects were observed for combining ultrasonication with ozonation and resulted in 100% DAA removal with 98 ± 0.8% reduction in COD within 15 min at 3.3 mg L(-1) ozone concentration and 130 Watts ultrasonication power. The reaction conditions obtained for the maximum oxidation of DAA and COD removal were used for the degradation of naphthenic acids mixture extracted from oil sands process water (OSPW). The percentage oxidation of NAs mixture extracted from OSPW was 89.3 ± 1.1% in ozonation and combined ozonation and ultrasonication, but COD removal observed was 65 ± 1.2% and 78 ± 1.4% for ozonation and combined ozonation and ultrasonication treatments, respectively. PMID:25137539

  4. Modeling aqueous ozone/UV process using oxalic acid as probe chemical.

    PubMed

    Garoma, Temesgen; Gurol, Mirat D

    2005-10-15

    A kinetic model that describes the removal of organic pollutants by an ozone/UV process is described. Oxalic acid, which reacts with a very low rate constant with ozone and relatively high rate constant with hydroxyl radical (OH*), was used as the probe chemical to model the process. The model was verified by experimental data on concentrations of oxalic acid and hydrogen peroxide (H202) under various experimental conditions, i.e., ozone gas dosage, UV light intensity, and varying oxalic acid concentrations. PMID:16295862

  5. Extraction of electrolytes from aqueous solutions and their spectrophotometric determination by use of acid-base chromoionophores in lipophylic solvents.

    PubMed

    Barberi, Paola; Giannetto, Marco; Mori, Giovanni

    2004-04-01

    The formation of non-absorbing complexes in an organic phase has been exploited for the spectrophotometric determination of ionic analytes in aqueous solutions. The method is based on liquid-liquid extraction of aqueous solution with lipophylic organic phases containing an acid-base chromoionophore, a neutral lypophilic ligand (neutral carrier) selective to the analyte and a cationic (or anionic) exchanger. The method avoids all difficulties of the preparation of the very thin membranes used in optodes, so that it can advantageously be used for the study of the role physical-chemical parameters of the system in order to optimize them and to prepare, if necessary, an optimized optode. Two lipophylic derivatives of Nile Blue and 4',5-dibromofluorescein have been synthesized, in order to ensure their permanence within organic phase. Two different neutral carriers previously characterized by us as ionophores for liquid-membrane Ion Selective Electrodes have been employed. Three different ionic exchangers have been tested. Furthermore, a model allowing the interpolation of experimental data and the determination of the thermodynamic constant of the ionic-exchange equilibrium has been developed and applied. PMID:15242090

  6. Kinetic and thermodynamic characterization of C-N bond rotation by N-methylacetohydroxamic acid in aqueous media.

    PubMed

    Sippl, Stefanie P; White, Paul B; Fry, Charles G; Volk, Sarah E; Ye, Lingxiao; Schenck, Heather L

    2016-01-01

    Hydroxamic acids (HAs) perform tasks in medicine and industry that require bidentate metal binding. The two favored conformations of HAs are related by rotation around the C(=O)-N bond. The conformations are unequal in stability. Recently, we reported that the most stable conformation of a small secondary HA in water places the oxygen atoms anti to one another. The barrier to C-N bond rotation may therefore modulate metal binding by secondary HAs in aqueous media. We have now determined the activation barrier to C-N rotation from major to minor conformation of a small secondary HA in D2O to be 67.3 kJ/mol. The HA rotational barrier scales with solvent polarity, as is observed in amides, although the HA barrier is less than that of a comparable tertiary amide in aqueous solution. Successful design of new secondary HAs to perform specific tasks requires solid understanding of rules governing HA structural behavior. Results from this work provide a more complete foundation for HA design efforts. PMID:26477862

  7. Tandem bis-aza-Michael addition reaction of amines in aqueous medium promoted by polystyrenesulfonic Acid

    EPA Science Inventory

    An efficient and environmentally benign tandem bis-aza-Michael addition of amines catalyzed by polystyrene sulfonic acid (PSSA) is described. This operationally simple high yielding microwave assisted synthetic protocol proceeded in water in the absence of any organic solvent.

  8. Magnetically separable nanoferrite-anchored glutathione: Aqueous homocoupling of arylboronic acids under microwave irradiation

    EPA Science Inventory

    A highly active, stable and magnetically separable glutathione based organocatalyst provided good to excellent yields to symmetric biaryls in the homocoupling of arylboronic acids under microwave irradiation. Symmetrical biaryl motifs are present in a wide range of natural p...

  9. Spectrofluorimetric study of the interaction of ciprofloxacin with amino acids in aqueous solution following solvatochromic studies

    NASA Astrophysics Data System (ADS)

    Alizadeh, Kamal; Mobarrez, Mahsa; Ganjali, Mohammad Reza; Norouzi, Parviz; Chaichi, Mohammad Javad

    Complexation of a fluoroquinolone derivative (ciprofloxacin), L, and some amino acids has been studied using spectrofluorimetric method. Results indicated that ciprofloxacin have a greater tendency to form a 1:1 complex with aspartic acid and arginine than the other tested molecules. The fluorescence of ciprofloxacin exhibits quenching process while it has been titrated with these amino acids. Formation constant values (Kf) for complex formed between ciprofloxacin and amino acids were also calculated. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were studied too. Possible reasons for the observed stability sequence were discussed based on the structures proposed for the resulting complexes. Besides the solution studies, solvatochromic properties of the ciprofloxacin are discussed by studying its spectra in a selection of different solvents.

  10. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

    PubMed Central

    Kawasaki, Shin-ichiro; Suzuki, Akira

    2013-01-01

    Summary The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid. PMID:23843908

  11. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors.

    PubMed

    Javaid, Rahat; Kawasaki, Shin-Ichiro; Suzuki, Akira; Suzuki, Toshishige M

    2013-01-01

    The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd-Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid. PMID:23843908

  12. Electrical conductivity measurements of aqueous boric acid at 25--350{degree}C at saturation vapor pressure. Final report

    SciTech Connect

    Ho, P.C.; Palmer, D.A.

    1995-09-01

    Electrical conductance measurements of aqueous boric acid solutions (15-110 g/kg-H{sub 2}O {equivalent_to} 0.251--1.815 mol/kg-H{sub 2}O) were measured over the temperature range 25 to 75 C at saturation vapor pressures in glass cells with parallel platinum electrodes. Sixteen series of measurements were made involving three samples of boric acid from different sources. Conductance measurements were also made at 15.5 and 30.5 g/kg-H{sub 2}O over the temperature range 100 to 350 C at 50 C intervals with a metallic cell fitted with concentric platinum electrodes. The specific conductances of H{sub 3}BO{sub 3} (aq)were calculated after correction for the conductance of the solvent (water) and are tabulated in this report. At the specific conditions requested in the project description, namely a concentration of 110 g/kg-H{sub 2}O and 65 C, the specific conductance of boric acid is 293.2 {+-} 1.8 microSiemens/cm based on duplicate measurements of four independent solutions. The results from these tests will be utilized by the Tokamak Physics Experimental Project (TPX).

  13. Self-consistent field theory investigation of the behavior of hyaluronic acid chains in aqueous salt solutions

    NASA Astrophysics Data System (ADS)

    Nogovitsin, E. A.; Budkov, Yu. A.

    2012-04-01

    In this work we continue to develop a field-theoretic methodology, which combines the technique of Gaussian equivalent representation for the calculation of functional integrals with the continuous Gaussian thread model of flexible polymers for solving statistical-mechanical problems of polyelectrolyte solutions. We present new analytic expressions for the osmotic pressure, the potential of mean force, and the monomer-monomer pair distribution function, and employ them to investigate the structural and thermodynamic quantities of the polyelectrolyte system. We demonstrate the applicability of the method for systems of polyelectrolyte chains in which the monomers interact via a Yukawa-type pair potential. As a specific example, the present work focuses on aqueous solutions of hyaluronic acid with added salts NaCl and CaCl2. Hyaluronic acid is a high molecular weight linear polysaccharide, which has a multitude of roles in biological tissues. We conclude that the effect of sodium chloride and calcium chloride on the osmotic properties of hyaluronic acid solutions can be accounted for by their contributions to the ionic strength. Nevertheless, the effects of coiling and self-association can be stimulated in solution by added salt.

  14. Acid dissociation mechanisms of Si(OH) 4 and Al(H 2O) 63+ in aqueous solution

    NASA Astrophysics Data System (ADS)

    Liu, Xiandong; Lu, Xiancai; Meijer, Evert Jan; Wang, Rucheng; Zhou, Huiqun

    2010-01-01

    Silicic acid and the hexa-aqua of Al 3+ are fundamental model aqueous species of chemical importance in nature. In order to investigate their hydroxyl dissociation mechanisms, Car-Parrinello molecular dynamics (CPMD) simulations were carried out, which allow treating the solutes and solvents on the same footing. The method of constraint was employed to trigger the reactions by taking coordination number as the reaction coordinate and the thermodynamic integration was used to obtain the free-energy profiles. The approximate transition states were located and the reactant and product states were also characterized. The free-energy changes of dissociation are found about 15.0 kcal/mol and 7.7 kcal/mol for silicic acid and Al-aqua, respectively. From the simulation results, the first p Kas were calculated by using two approaches, which are based on the pristine thermodynamic relation and the RDF (radial distribution function)-free energy relation, respectively. Because of more uncertainties involved in the RDF way, it is suggested that the pristine way should be favored, which shows an error margin of 1 p Ka unit. This study provides an encouraging basis for applying the present methodology to predict acidity constants of those groups that are difficult to measure experimentally.

  15. Equilibrium and kinetics study on the adsorption of perfluorooctanoic acid from aqueous solution onto powdered activated carbon.

    PubMed

    Qu, Yan; Zhang, Chaojie; Li, Fei; Bo, Xiaowen; Liu, Guangfu; Zhou, Qi

    2009-09-30

    Powdered activated carbon (PAC) was applied to remove perfluorooctanoic acid (PFOA) from the aqueous PFOA solution in this study. Contact time, adsorbent dose and temperature were analyzed as the effect factors in the adsorption reaction. The contact time of maximum PFOA uptake was around 1h while the sorption removal efficiency increased with the PAC concentrations. And the process of adsorption increased from 303 K to 313 K and then decreased from 313 K to 323 K. Among four applied models, the experimental isotherm data were discovered to follow Langmuir isotherm model more closely. Thermodynamically, adsorption was endothermic because enthalpy, entropy and Gibbs constants were 198.5 kJ/mol, 0.709 kJ/mol/K and negative, respectively, which also indicated that the adsorption process was spontaneous and feasible. From kinetic analysis, the adsorption was suggested to be pseudo-second-order model. The adsorption of PFOA on the PAC was mainly controlled by particle diffusion. PMID:19395160

  16. A mechanistic study of the photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid in aqueous solution.

    PubMed

    Yurkova, Maria P; Pozdnyakov, Ivan P; Plyusnin, Victor F; Grivin, Vycheslav P; Bazhin, Nikolay M; Kruppa, Alexandr I; Maksimova, Tatiana A

    2013-04-01

    Photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous solution was investigated by stationary (254 nm) and nanosecond laser (266 nm) flash photolysis techniques. It was shown that in the primary photochemical step both photoionization (which generates a hydrated electron-radical cation pair) and heterolytic cleavage of a C-Cl bond takes place. The major products of substitution of one of the chlorine atoms in the 2-, 4- or 5-position by a hydroxyl group as well as the products of hydroxylation of the benzene ring in 3- and 6-positions were identified by HPLC and LC-MS methods. The complexation of 2,4,5-T with β- and γ-cyclodextrins (β(γ)CD) was investigated. The influence of such complexation on the quantum yield of herbicide photolysis and on the ratio of photodegradation products was determined. PMID:23085749

  17. Morphological and phase evolution of TiO 2 nanocrystals prepared from peroxotitanate complex aqueous solution: Influence of acetic acid

    NASA Astrophysics Data System (ADS)

    Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

    2009-04-01

    Nanosized anatase and rutile TiO 2 having different shape, phase and size have been prepared from aqueous solutions of peroxo titanium complex starting from titanium(IV) isopropoxide (TTIP), acetic acid and hydrogen peroxide (H 2O 2) in water/isopropanol media by a facile sol-gel process. The TiO 2 nanocrystals are characterized by powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, TEM, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques. The influence of pH and the sequence of addition of reaction contents on the phase and morphology of TiO 2 are studied. The reasons for the observation of only anatase and/or mixture of anatase and rutile are given.

  18. Corrosion phenomena of alloy 625 in aqueous solutions containing sulfuric acid and oxygen under subcritical and supercritical conditions

    SciTech Connect

    Kritzer, P.; Boukis, N.; Dinjus, E.

    1998-12-31

    Corrosion phenomena of alloy 625 pressure tubes were investigated in aqueous solutions containing up to 0.2 mol/kg sulfuric acid and up to 1.44 mol/kg oxygen. Applied maximum temperatures and pressures were 500 C, and 38 MPa, respectively. Corrosion started at temperatures around 150 C with intergranular attack. Above 250 C, the whole surface of the alloy was attacked, shallow pits and deep intergranular attack appeared. This behavior can be explained by transpassive dissolution of the protecting Cr(III) oxide layer and leads to severe material loss. The upper temperature limit of severe corrosion at an experimental pressure of 24 MPa was about 390 C. As temperature was increased further and the density of the solution dropped to low values, only slight corrosion was detected.

  19. Photocatalytic decomposition of humic acids in anoxic aqueous solutions producing hydrogen, oxygen and light hydrocarbons.

    PubMed

    Klauson, Deniss; Budarnaja, Olga; Beltran, Ignacio Castellanos; Krichevskaya, Marina; Preis, Sergei

    2014-01-01

    Photocatalytic water splitting for hydrogen and oxygen production requires sacrificial electron donors, for example, organic compounds. Titanium dioxide catalysts doped with platinum, cobalt, tungsten, copper and iron were experimentally tested for the production of hydrogen, oxygen and low molecular weight hydrocarbons from aqueous solutions of humic substances (HS). Platinum-doped catalyst showed the best results in hydrogen generation, also producing methane, ethene and ethane, whereas the best oxygen production was exhibited by P25, followed by copper--and cobalt-containing photocatalysts. Iron-containing photocatalyst produced carbon monoxide as a major product. HS undergoing anoxic photocatalytic degradation produce hydrogen with minor hydrocarbons, and/or oxygen. It appears that better hydrogen yield is achieved when direct HS splitting takes place, as opposed to HS acting as electron donors for water splitting. PMID:25145176

  20. Contribution of diffuse inputs to the aqueous mass load of perfluoroalkyl acids in river and stream catchments in Korea.

    PubMed

    Kim, Seung-Kyu; Li, Dong-Hao; Shoeib, Mahiba; Zoh, Kyung-Duk

    2014-02-01

    Recent studies disagree regarding the contributions of point versus non-point sources to the aqueous mass loads of perfluoroalkyl acids (PFAAs). This study investigated the longitudinal change in PFAA mass load from upstream to downstream stations along rivers and/or streams to assess the relative contributions of point versus nonpoint inputs. With concentrations 10 to 100 times higher than running water, point sources such as wastewater treatment plants (WWTPs) effluent and airport ditch-outlet (ADO) water were separated from neighboring upstream and downstream running waters using principal component analysis. Source waters were characterized by certain predominant components [e.g., perfluorobutylsulfonate (PFBS) and perfluorooctanoic acid (PFOA) in WWTP effluent and perfluorohexylsulfonate (PFHxS) and perfluorooctylsulfonate (PFOS) in ADO water], which were minor components of running water. From a mass balance assessment of PFAA mass load, certain compounds such as PFOA and PFBS dominated the contribution of point sources to the mass load in the running water at downstream stations or in small catchment basins with high levels of industrial activity. Most of the mass load in the investigated catchments was attributable to upstream running water with a minor influence from industrial, commercial, and domestic human activities. Furthermore, the negative relationship of per capita emission factors (hereafter, EFs) with population density and a lower contribution of PFAA from WWTPs (~30% on average) compared to the running water-derived mass load at the national level indicated that diffuse inputs were more important contributors to aqueous PFAA contamination in each catchment basin as well as the entire watershed of the country (Korea). Volatile precursor compounds, which are readily dispersed to neighboring basins and transformed to PFAAs in the ambient environment, can be an important source of these diffuse inputs and will become more significant over time

  1. Proliferation of Purple Sulphur Bacteria at the Sediment Surface Affects Intertidal Mat Diversity and Functionality

    PubMed Central

    Hubas, Cédric; Jesus, Bruno; Ruivo, Mickael; Meziane, Tarik; Thiney, Najet; Davoult, Dominique; Spilmont, Nicolas; Paterson, David M.; Jeanthon, Christian

    2013-01-01

    There is a relative absence of studies dealing with mats of purple sulphur bacteria in the intertidal zone. These bacteria display an array of metabolic pathways that allow them to disperse and develop under a wide variety of conditions, making these mats important in terms of ecosystem processes and functions. Mass blooms of purple sulphur bacteria develop during summer on sediments in the intertidal zone especially on macroalgal deposits. The microbial composition of different types of mats differentially affected by the development of purple sulphur bacteria was examined, at low tide, using a set of biochemical markers (fatty acids, pigments) and composition was assessed against their influence on ecosystem functions (sediment cohesiveness, CO2 fixation). We demonstrated that proliferation of purple sulphur bacteria has a major impact on intertidal mats diversity and functions. Indeed, assemblages dominated by purple sulphur bacteria (Chromatiaceae) were efficient exopolymer producers and their biostabilisation potential was significant. In addition, the massive growth of purple sulphur bacteria resulted in a net CO2 degassing whereas diatom dominated biofilms represented a net CO2 sink. PMID:24340018

  2. Phase diagrams and water activities of aqueous ammonium salts of malonic acid.

    PubMed

    Beyer, Keith D; Richardson, Michael; Reusch, Breanna

    2011-04-14

    Malonic acid has been observed in the free troposphere and as a component of tropospheric aerosol, among other dicarboxylic acids. These aerosols can uptake ammonia, which partially or completely neutralizes the acids. Therefore, the impact of ammoniated dicarboxylic acids on the phases that can exist in aerosols at atmospheric temperatures needs investigation. To that end, the low temperature, solid/liquid phase diagrams of ammonium hydrogen malonate/water, ammonium malonate/water, and triammonium hydrogen malonate/water have been investigated with differential scanning calorimetry and infrared spectroscopy of thin films. Results show that the order of increasing solubility is triammonium hydrogen malonate, ammonium hydrogen malonate, malonic acid, and ammonium malonate. We have also determined a hydrate may form in the ammonium malonate system and decompose below 240 K. We report water activities at the ice melting points for each system up to the respective eutectic concentrations, and find for a given mole fraction of water, increasing ammonium content leads to decreasing water activity coefficients. PMID:21428389

  3. Interrogating trees as archives of sulphur deposition

    NASA Astrophysics Data System (ADS)

    Wynn, P. M.; Loader, N. J.; Fairchild, I. J.

    2012-04-01

    A principal driver of climatic variability over the past 1,000 years and essential forcing mechanism for climate, are the changes in atmospheric composition resulting from sulphur aerosols. Natural and anthropogenic aerosols released into the atmosphere disrupt the radiative balance through backscattering and absorption of incoming solar radiation and increase cloud albedo by acting as condensation nuclei. Understanding the impact of sulphur emissions upon climate beyond the last few hundred years however is not straightforward and natural archives of environmental information must be explored. Tree-rings represent one such archive as they are widely distributed and preserve environmental information within a precisely dateable, annually resolved timescale. Until recently the sulphur contained within tree-rings has largely remained beyond the reach of environmental scientists and climate modelers owing to difficulties associated with the extraction of a robust signal and uncertainties regarding post-depositional mobility. Our recent work using synchrotron radiation has established that the majority of non-labile sulphur in two conifer species is preserved within the cellular structure of the woody tissue after uptake and demonstrates an increasing trend in sulphur concentration during the 20th century and during known volcanic events. Due to the clear isotopic distinction between marine (+21), geological (+10 to +30), atmospheric pollution (-3 to +9 ) and volcanic sources of sulphur (0 to +5), isotopic ratios provide a diagnostic tool with which changes in the source of atmospheric sulphur can be detected in a more reliable fashion than concentration alone. Sulphur isotopes should thereby provide a fingerprint of short lived events including volcanic activity when extracted at high resolution and in conjunction with high resolution S concentrations defining the event. Here we present methodologies associated with extracting the sulphur isotopic signal from tree

  4. Rheology and interfacial properties of aqueous solutions of the diblock polyelectrolyte poly(styrene-block-acrylic acid)

    NASA Astrophysics Data System (ADS)

    Kimerling, Abigail

    In aqueous solutions diblock polyelectrolytes with amphiphilic character form aggregate structures, which affect physical properties such as viscosity, elasticity, surface tension, and film hydrophilicity. Potential applications for diblock polyelectrolyte solutions include coatings, inks, oil recovery agents, personal care products, and biomaterials. By varying the diblock polyelectrolyte and solution properties, the solutions can be tuned to meet the needs of particular applications. The research objective was to identify the influences of block length, pH, and ionic strength on the rheological and interfacial properties of poly(styrene- b-acrylic acid) (PS-PAA) solutions. Six polymers with varied PS and PAA block lengths were examined, all at 1.0 wt% in aqueous solutions. The hydrophobicity of the PS block causes the formation of spherical micelles in aqueous solutions. Increasing the solution pH ionizes the PAA block, which leads to an increase in micelle corona thickness due to repulsions between chains. Major trends observed in the rheological and interfacial properties can be understood in terms of expected changes in the micelle size and interfacial self-assembly with pH, ionic strength, and block length. Addition of NaOH was found to increase the solution pH and initially led to increases in solution viscosity, elasticity, surface tension, and film hydrophilicity. This effect was attributed to creation of larger micelles and greater inter-micellar repulsions as the PAA chain became more fully charged. However, when the concentration of NaOH exceeded a critical value, the solution viscosity, elasticity, and film hydrophilicity decreased. It is believed this was due to charge shielding by excess sodium ions, leading to shrinkage of the micelle corona and smaller micelles. Increasing the PS-PAA solution ionic strength by adding NaCl also provided charge shielding, as observed by decreases in solution viscosity and elasticity. Increasing the length of either

  5. Degradation of trans-ferulic acid in acidic aqueous medium by anodic oxidation, electro-Fenton and photoelectro-Fenton.

    PubMed

    Flores, Nelly; Sirés, Ignasi; Garrido, José Antonio; Centellas, Francesc; Rodríguez, Rosa María; Cabot, Pere Lluís; Brillas, Enric

    2016-12-01

    Solutions of pH 3.0 containing trans-ferulic acid, a phenolic compound in olive oil mill wastewater, have been comparatively degraded by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were performed with a BDD/air-diffusion cell, where oxidizing OH was produced from water discharge at the BDD anode and/or in the solution bulk from Fenton's reaction between cathodically generated H2O2 and added catalytic Fe(2+). The substrate was very slowly removed by AO-H2O2, whereas it was very rapidly abated by EF and PEF, at similar rate in both cases, due to its fast reaction with OH in the bulk. The AO-H2O2 process yielded a slightly lower mineralization than EF, which promoted the accumulation of barely oxidizable products like Fe(III) complexes. In contrast, the fast photolysis of these latter species under irradiation with UVA light in PEF led to an almost total mineralization with 98% total organic carbon decay. The effect of current density and substrate concentration on the performance of all treatments was examined. Several solar PEF (SPEF) trials showed its viability for the treatment of wastewater containing trans-ferulic acid at larger scale. Four primary aromatic products were identified by GC-MS analysis of electrolyzed solutions, and final carboxylic acids like fumaric, acetic and oxalic were detected by ion-exclusion HPLC. A reaction sequence for trans-ferulic acid mineralization involving all the detected products is finally proposed. PMID:26691522

  6. Pervaporation of Water from Aqueous Sulfuric Acid at Elevated Temperatures Using Nafion® Membranes

    SciTech Connect

    Christopher J. Orme; Frederick F. Stewart

    2009-01-01

    The concentration of sulfuric acid by pervaporation has been studied using Nafion-112® and Nafion-117® membranes, which have been characterized in terms of flux, permeability, and selectivity at 100 ºC and 120 ºC. Feed concentrations investigated ranged from 40 to over 80 weight percent. In general, water fluxes ranged from 100-8000 g/m2h, depending on feed acid concentration and separations factors as high as 104 were observed. Membrane stability was probed using Dynamic Mechanical Analysis that revealed some embrittlement of the membranes during use. Further studies showed that the embrittlement was due to an interaction with the acid and was not induced by the operating temperature.

  7. 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

  8. Chemisorption of Perfluorooctanoic Acid on Powdered Activated Carbon Initiated by Persulfate in Aqueous Solution.

    PubMed

    Sun, Bo; Ma, Jun; Sedlak, David L

    2016-07-19

    Perfluorooctanoic acid (PFOA) is a perfluorocarboxylic acid that is difficult to treat by most conventional methods. As a result, it is often removed from solution by adsorption on powdered activated carbon (PAC), followed by incineration of the spent carbon. To provide a new approach for treatment, PFOA was exposed to sulfate radicals (SO4(-•)) produced by thermolysis of persulfate (S2O8(2-)) in the presence of PAC. Under acidic conditions, thermal activation of persulfate resulted in transformation of PFOA to shorter-chain-length perfluorinated compounds, as previously reported. However, when thermolysis of persulfate occurred under circumneutral pH conditions in the presence of PAC, a new removal pathway for PFOA was observed. Under these conditions, the removal of PFOA was attributable to chemisorption, a process in which PAC catalyzed persulfate decomposition and reacted with the transformation products to produce covalently bound PFOA. At PAC concentrations between 200 and 1000 mg/L and an initial PFOA concentration of 0.5 μM, covalent bonding resulted in removal of 10-40% of the PFOA. Under these conditions, the process resulted in removal of more than half of a more hydrophilic perfluoroalkyl acid (i.e., perfluorobutanoic acid, PFBA), which was greater than the amount of PFBA removed by physical adsorption on PAC. Although the high reaction temperatures (i.e., 80 °C) and relatively high doses of PAC used in this study may be impractical for drinking water treatment, this process may be applied to the treatment of these recalcitrant compounds in industrial wastewater, reverse osmosis concentrate, and other waters that contain high concentrations of PFOA and other perfluorocarboxylic acids. PMID:27336204

  9. Interaction of some metals between marine-origin humic acids and aqueous solutions

    SciTech Connect

    Huljev, D.J.

    1986-08-01

    The interaction of metal ions (carrier-free form) in aquatic medium with humic acids is a complicated process depending on the properties of humic acids (elementary, chemical, and trace element composition), metals studied (valence, charge, chemical form, concentration), and medium used (pH, ionic strength). The use of radionuclides was found to be very suitable for a rapid and precise determination of the distribution coefficient K/sub d/ (ratio of the concentration of a certain trace metal association with a gram of humic acid over the concentration of the same trace metal per milliliter of solution) of the investigated system. Isolated humic acids from offshore sediments from the North Adriatic (Lim channel, near Rovinj, Yugoslavia) were characterized according to their elementary composition, the amount of products of hydrolysis, and the trace elements bound. All experiments were carried out between pH 3 and 5. It was found that conditions usually present at the site where humic acid interacts with metal ions (anaerobic conditions, H/sub 2/S) in brackish (21% S) and standard seawater (38% S) are determined in the pH range 3 to 5. The results of the pick-up (uptake) and replacement (release) experiments are presented as a distribution coefficient (K/sub d/), as a function of contact time. Processes of pick-up and replacement of a number of metals under various physicochemical conditions were investigated and special attention was paid to the influence of salinity. With the increase in NaCl concentration and pH in the system, the fixation of ruthenium, zinc, cobalt, and mercury by humic acids decreased.

  10. Development of poly(3,4-ethylenedioxythiophene-co-indole-5-carboxylic acid) co-polymer coatings on passivated low-nickel stainless steel for enhanced corrosion resistance in the sulphuric acid medium

    NASA Astrophysics Data System (ADS)

    Gopi, D.; Karthikeyan, P.; Kavitha, L.; Surendiran, M.

    2015-12-01

    The present study deals with the successful development of poly(3,4-ethylenedioxythiophene-co-indole-5-carboxylic acid) co-polymer coatings on passivated low-nickel stainless steel (LN SS) by electropolymerization. The structural and morphological evaluation of the co-polymer coatings were performed using various analytical techniques. Also, the effect of monomer feed ratio on the morphological behaviour of the co-polymer coatings was studied towards the protection efficiency of LN SS in 0.5 M H2SO4. The results demonstrated that the co-polymer coating on passivated LN SS improved the corrosion protection efficiency at the feed ratio 50:50 and hence the as-coated LN SS can serve as a prospective material for industrial applications.

  11. Aqueous Alteration of Mars-Analog Rocks Under an Acidic Atmosphere

    NASA Technical Reports Server (NTRS)

    Bullock, M. A.; Moore, J. M.; Mellon, M. T.

    2001-01-01

    The wind-blown fines of Mars have high amounts of salts that are easily mobilized by water. We report on laboratory experiments that produce brines from the interaction of water with Mars-analog rocks and a simulated acidic Mars paleoatmosphere. Additional information is contained in the original extended abstract.

  12. Solute-enhanced production of gamma-valerolactone (GVL) from aqueous solutions of levulinic acid

    SciTech Connect

    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.

  13. Determination of the optimum conditions for boric acid extraction with carbon dioxide gas in aqueous media from colemanite containing arsenic

    SciTech Connect

    Ata, O.N.; Colak, S.; Copur, M.; Celik, C.

    2000-02-01

    The Taguchi method was used to determine optimum conditions for the boric acid extraction from colemanite ore containing As in aqueous media saturated by CO{sub 2} gas. After the parameters were determined to be efficient on the extraction efficiency, the experimental series with two steps were carried out. The chosen experimental parameters for the first series of experiments and their ranges were as follows: (1) reaction temperature, 25--70 C; (2) solid-to-liquid ratio (by weight), 0.091 to 0.333; (3) gas flow rate (in mL/min), 66.70--711; (4) mean particle size, {minus}100 to {minus}10 mesh; (5) stirring speed, 200--600 rpm; (6) reaction time, 10--90 min. The optimum conditions were found to be as follows: reaction temperature, 70 C; solid-to-liquid ratio, 0.091; gas flow rate, 711 (in mL/min); particle size, {minus}100 mesh; stirring speed, 500 rpm; reaction time, 90 min. Under these optimum conditions, the boric acid extraction efficiency from the colemanite containing As was approximately 54%. Chosen experimental parameters for the second series of experiments and their ranges were as follows: (1) reaction temperature, 60--80 C; (2) solid-to-liquid ratio (by weight), 0.1000 to 0.167; (3) gas pressure (in atm), 1.5; 2.7; (4) reaction time, 45--120 min. The optimum conditions were found to be as follows: reaction temperature, 70 C; solid-to-liquid ratio, 0.1; gas pressure, 2.7 atm; reaction time, 120 min. Under these optimum conditions the boric acid extraction efficiency from the colemanite ore was approximately 75%. Under these optimum conditions, the boric acid extraction efficiency from calcined colemanite ore was approximately 99.55%.

  14. Interactions of aqueous amino acids and proteins with the (110) surface of ZnS in molecular dynamics simulations

    SciTech Connect

    Nawrocki, Grzegorz; Cieplak, Marek

    2014-03-07

    The growing usage of nanoparticles of zinc sulfide as quantum dots and biosensors calls for a theoretical assessment of interactions of ZnS with biomolecules. We employ the molecular-dynamics-based umbrella sampling method to determine potentials of mean force for 20 single amino acids near the ZnS (110) surface in aqueous solutions. We find that five amino acids do not bind at all and the binding energy of the remaining amino acids does not exceed 4.3 kJ/mol. Such energies are comparable to those found for ZnO (and to hydrogen bonds in proteins) but the nature of the specificity is different. Cysteine can bind with ZnS in a covalent way, e.g., by forming the disulfide bond with S in the solid. If this effect is included within a model incorporating the Morse potential, then the potential well becomes much deeper—the binding energy is close to 98 kJ/mol. We then consider tryptophan cage, a protein of 20 residues, and characterize its events of adsorption to ZnS. We demonstrate the relevance of interactions between the amino acids in the selection of optimal adsorbed conformations and recognize the key role of cysteine in generation of lasting adsorption. We show that ZnS is more hydrophobic than ZnO and that the density profile of water is quite different than that forming near ZnO—it has only a minor articulation into layers. Furthermore, the first layer of water is disordered and mobile.

  15. Interactions of aqueous amino acids and proteins with the (110) surface of ZnS in molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Nawrocki, Grzegorz; Cieplak, Marek

    2014-03-01

    The growing usage of nanoparticles of zinc sulfide as quantum dots and biosensors calls for a theoretical assessment of interactions of ZnS with biomolecules. We employ the molecular-dynamics-based umbrella sampling method to determine potentials of mean force for 20 single amino acids near the ZnS (110) surface in aqueous solutions. We find that five amino acids do not bind at all and the binding energy of the remaining amino acids does not exceed 4.3 kJ/mol. Such energies are comparable to those found for ZnO (and to hydrogen bonds in proteins) but the nature of the specificity is different. Cysteine can bind with ZnS in a covalent way, e.g., by forming the disulfide bond with S in the solid. If this effect is included within a model incorporating the Morse potential, then the potential well becomes much deeper—the binding energy is close to 98 kJ/mol. We then consider tryptophan cage, a protein of 20 residues, and characterize its events of adsorption to ZnS. We demonstrate the relevance of interactions between the amino acids in the selection of optimal adsorbed conformations and recognize the key role of cysteine in generation of lasting adsorption. We show that ZnS is more hydrophobic than ZnO and that the density profile of water is quite different than that forming near ZnO—it has only a minor articulation into layers. Furthermore, the first layer of water is disordered and mobile.

  16. Interactions of aqueous amino acids and proteins with the (110) surface of ZnS in molecular dynamics simulations.

    PubMed

    Nawrocki, Grzegorz; Cieplak, Marek

    2014-03-01

    The growing usage of nanoparticles of zinc sulfide as quantum dots and biosensors calls for a theoretical assessment of interactions of ZnS with biomolecules. We employ the molecular-dynamics-based umbrella sampling method to determine potentials of mean force for 20 single amino acids near the ZnS (110) surface in aqueous solutions. We find that five amino acids do not bind at all and the binding energy of the remaining amino acids does not exceed 4.3 kJ/mol. Such energies are comparable to those found for ZnO (and to hydrogen bonds in proteins) but the nature of the specificity is different. Cysteine can bind with ZnS in a covalent way, e.g., by forming the disulfide bond with S in the solid. If this effect is included within a model incorporating the Morse potential, then the potential well becomes much deeper--the binding energy is close to 98 kJ/mol. We then consider tryptophan cage, a protein of 20 residues, and characterize its events of adsorption to ZnS. We demonstrate the relevance of interactions between the amino acids in the selection of optimal adsorbed conformations and recognize the key role of cysteine in generation of lasting adsorption. We show that ZnS is more hydrophobic than ZnO and that the density profile of water is quite different than that forming near ZnO--it has only a minor articulation into layers. Furthermore, the first layer of water is disordered and mobile. PMID:24606380

  17. USEPA METHOD STUDY 38 - SW-846 METHOD 3010, ACID DIGESTION OF AQUEOUS SAMPLES AND EXTRACTS FOR TRACE METALS BY FLAME ATOMIC ABSORPTION SPECTROSCOPY

    EPA Science Inventory

    An interlaboratory collaborative study was conducted on SW-846 Method 3010, "Acid Digestion of Aqueous Samples and Extracts for Total Metals for Analysis by Flame Atomic Absorption Spectroscopy", to determine the mean recovery and precision for analyses of 21 trace metals in surf...

  18. Efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate Escherichia coli O157:H7 from lettuce leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study compared the efficacy of chlorine (20 – 200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20 – 200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20 – 200 ppm chlorite ion concentration, TriNova) washes in reducing population...

  19. Production of fermentable sugars from corn fiber using soaking in aqueous ammonia (saa) pretreatment and fermentation to succinic acid by Escherichia coli afp184

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conversion of corn fiber (CF), a by-product from the corn-to-ethanol conversion process, into fermentable sugar and succinic acid was investigated using soaking in aqueous ammonia (SAA) pretreatment followed by biological conversions including enzymatic hydrolysis and fermentation using genetically ...

  20. DEFINITIVE SOX CONTROL PROCESS EVALUATIONS: AQUEOUS CARBONATE AND WELLMAN-LORD (ACID, ALLIED CHEMICAL, AND RESOX) FGD (FLUE GAS DESULFURIZATION) TECHNOLOGIES

    EPA Science Inventory

    The report gives results of economic evaluations of two processes: the Rockwell International aqueous carbonate process (ACP) and the Wellman-Lord process, the latter applied to a sulfuric acid plant, the Foster Wheeler Resox process, and the Allied Chemical coal reduction proces...

  1. IUPAC-NIST Solubility Data Series. 90. Hydroxybenzoic Acid Derivatives in Binary, Ternary, and Multicomponent Systems. Part I. Hydroxybenzoic Acids, Hydroxybenzoates, and Hydroxybenzoic Acid Salts in Water and Aqueous Systems

    NASA Astrophysics Data System (ADS)

    Goto, Rensuke; Fukuda, Hiroshi; Königsberger, Erich; Königsberger, Lan-Chi

    2011-03-01

    The solubility data for well-defined binary, ternary, and multicomponent systems of solid-liquid type are reviewed. One component, which is 2-, 3-, and 4-hydroxybenzoic acids, 4-hydroxybenzoate alkyl esters (parabens), or hydroxybenzoic acid salts, is in the solid state at room temperature and another component is liquid water, meaning that all of the systems are aqueous solutions. The ternary or multicomponent systems include organic substances of various classes (hydrocarbons of several structural types, halogenated hydrocarbons, alcohols, acids, ethers, esters, amides, and surfactants) or inorganic substances. Systems reported in the primary literature from 1898 through 2000 are compiled. For seven systems, sufficient binary data for hydroxybenzoic acids or parabens in water are available to allow critical evaluation. Almost all data are expressed as mass and mole fractions as well as the originally reported units, while some data are expressed as molar concentration.

  2. Acidity of the amidoxime functional group in aqueous solution: a combined experimental and computational study.

    PubMed

    Mehio, Nada; Lashely, Mark A; Nugent, Joseph W; Tucker, Lyndsay; Correia, Bruna; Do-Thanh, Chi-Linh; Dai, Sheng; Hancock, Robert D; Bryantsev, Vyacheslav S

    2015-02-26

    Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pK(a) values that have been reported for the amidoxime functional group. To resolve this existing controversy we investigated the pK(a) values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopic titrations to measure the pK(a) values of representative amidoximes, acetamidoxime, and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pK(a) values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance, with a root-mean-square deviation of 0.46 pK(a) units and 0.45 pK(a) units, respectively. Finally, we employ our two best methods to predict the pK(a) values of promising, uncharacterized amidoxime ligands, which provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents. PMID:25621618

  3. A combination of synchronous fluorescence spectroscopy with chemometric treatment and internal standards in non-aqueous potentiometric titrations of fulvic acids.

    PubMed

    Esteves da Silva, J C; Machado, A A

    1994-12-01

    The acid properties of a soil fulvic acid (sfua) were characterized by potentiometric titration with tetrabutylammonium hydroxide in two non-aqueous solvents with high acid-base resolution power N,N-dimethylformamide (DMF) and acetonitrile. Synchronous fluorescence spectroscopy (SyF) was also used to monitor directly the sfua status during the potentiometric titration in DMF. The potentiometric titration curves showed no clear end-point and the analysis of the sets of spectra obtained at increasing neutralization degree, with a self-modeling curve resolution method (SIMPLISMA), revealed the existence of two components with featureless concentration profiles. Internal standards (maleic, salicylic and p-hydroxylbenzoic acids) were used to determine the amounts of acid groups with different acid strengths in the two non-aqueous solvents. It was shown that the variations observed in the SyF spectra sets of the internal standards are not correlated with those observed in the sfua data. The splitting of the sfua groups in the non-aqueous titration curves seems to be forced artificially depending on the standards used. PMID:18966177

  4. Contact ion pair formation between hard acids and soft bases in aqueous solutions observed with 2DIR spectroscopy.

    PubMed

    Sun, Zheng; Zhang, Wenkai; Ji, Minbiao; Hartsock, Robert; Gaffney, Kelly J

    2013-12-12

    The interaction of charged species in aqueous solution has important implications for chemical, biological, and environmental processes. We have used 2DIR spectroscopy to study the equilibrium dynamics of thiocyanate chemical exchange between free ion (NCS(-)) and contact ion pair configurations (MNCS(+)), where M(2+) = Mg(2+) or Ca(2+). Detailed studies of the influence of anion concentration and anion speciation show that the chemical exchange observed with the 2DIR measurements results from NCS(-) exchanging with other anion species in the first solvation shell surrounding Mg(2+) or Ca(2+). The presence of chemical exchange in the 2DIR spectra provides an indirect, but robust, determinant of contact ion pair formation. We observe preferential contact ion pair formation between soft Lewis base anions and hard Lewis acid cations. This observation cannot be easily reconciled with Pearson's acid-base concept or Collins' Law of Matching Water Affinities. The anions that form contact ion pairs also correspond to the ions with an affinity for water and protein surfaces, so similar physical and chemical properties may control these distinct phenomena. PMID:23895531

  5. Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework.

    PubMed

    Demir, Selvan; Brune, Nicholas K; Van Humbeck, Jeffrey F; Mason, Jarad A; Plakhova, Tatiana V; Wang, Shuao; Tian, Guoxin; Minasian, Stefan G; Tyliszczak, Tolek; Yaita, Tsuyoshi; Kobayashi, Tohru; Kalmykov, Stepan N; Shiwaku, Hideaki; Shuh, David K; Long, Jeffrey R

    2016-04-27

    Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr(2+), Fe(3+), Nd(3+), and Am(3+), from aqueous solutions employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity. PMID:27163056

  6. Electrocatalytic and photocatalytic hydrogen production from acidic and neutral-pH aqueous solutions using iron phosphide nanoparticles.

    PubMed

    Callejas, Juan F; McEnaney, Joshua M; Read, Carlos G; Crompton, J Chance; Biacchi, Adam J; Popczun, Eric J; Gordon, Thomas R; Lewis, Nathan S; Schaak, Raymond E

    2014-11-25

    Nanostructured transition-metal phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of -10 mA cm(-2), FeP nanoparticles deposited at a mass loading of ∼1 mg cm(-2) on Ti substrates exhibited overpotentials of -50 mV in 0.50 M H2SO4 and -102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods under galvanostatic control. Under UV illumination in both acidic and neutral-pH solutions, FeP nanoparticles deposited on TiO2 produced H2 at rates and amounts that begin to approach those of Pt/TiO2. FeP therefore is a highly Earth-abundant material for efficiently facilitating the HER both electrocatalytically and photocatalytically. PMID:25250976

  7. Solution properties and taste behavior of lactose monohydrate in aqueous ascorbic acid solutions at different temperatures: Volumetric and rheological approach.

    PubMed

    Sarkar, Abhijit; Sinha, Biswajit

    2016-11-15

    The densities and viscosities of lactose monohydrate in aqueous ascorbic acid solutions with several molal concentrations m=(0.00-0.08)molkg(-1) of ascorbic acid were determined at T=(298.15-318.15)K and pressure p=101kPa. Using experimental data apparent molar volume (ϕV), standard partial molar volume (ϕV(0)), the slope (SV(∗)), apparent specific volumes (ϕVsp), standard isobaric partial molar expansibility (ϕE(0)) and its temperature dependence [Formula: see text] the viscosity B-coefficient and solvation number (Sn) were determined. Viscosity B-coefficients were further employed to obtain the free energies of activation of viscous flow per mole of the solvents (Δμ1(0≠)) and of the solute (Δμ2(0≠)). Effects of molality, solute structure and temperature and taste behavior were analyzed in terms of solute-solute and solute-solvent interactions; results revealed that the solutions are characterized predominantly by solute-solvent interactions and lactose monohydrate behaves as a long-range structure maker. PMID:27283672

  8. Removal of Cu(II) and Ni(II) from aqueous solution by lignite-based humic acids

    SciTech Connect

    Arslan, G.; Cetin, S.; Pehlivan, E.

    2007-07-01

    The removal of Cu(II) and Ni(II) metal ions from an aqueous solution were investigated by using humic acids (HAs) in a batch arrangement. HAs were prepared by using alkaline extraction, following sedimentation and acidic precipitation from three Turkish lignites: Ilgin, Beysehir, and Ermenek. The interactions of Cu(II) and Ni(II) with solid HAs and influence of three parameters (initial metal concentration, solution pH and temperature) on the removal of metals were studied. Adsorption equilibrium was achieved in about 120 min for Cu(II) and Ni(II) ions. The sorption of Cu(II) and Ni(II) on the surface of HAs depended strongly on the pH, and increased with increasing pH and the initial concentration of metal. The sorption of Cu(II) was higher than that of Ni(II) for HAs. The equilibrium relationship between adsorbent and adsorbate is described by adsorption isotherms at a fixed temperature 35 {sup o}C, at pH about 4.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. Adsorption isotherms and kinetics data of Cu(II) and Ni(II) ions removed by HAs are presented and discussed.

  9. Structural evolution of molybdenum carbides in hot aqueous environments and impact on low-temperature hydroprocessing of acetic acid

    SciTech Connect

    Choi, Jae -Soon; Schwartz, Viviane; Santillan-Jimenez, Eduardo; Crocker, Mark; Lewis, Sr., Samuel A.; Lance, Michael J.; Meyer, III, Harry M.; More, Karren L.

    2015-03-13

    In this paper, we investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore volume and surface area. The extent of these structural changes was sensitive to the initial carbide structure and was lower under actual hydroprocessing conditions indicating the possibility of further improving the hydrothermal stability of Mo carbides by optimizing catalyst structure and operating conditions. Mo carbides were active in acetic acid conversion in the presence of liquid water, their activity being comparable to that of Ru/C. Finally, the results suggest that effective and inexpensive bio-oil hydroprocessing catalysts could be designed based on Mo carbides, although a more detailed understanding of the structure-performance relationships is needed, especially in upgrading of more complex reaction mixtures or real bio-oils.

  10. Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

    PubMed Central

    2016-01-01

    Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr2+, Fe3+, Nd3+, and Am3+, from aqueous solutions employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity. PMID:27163056

  11. Study of the dose response of the system ferrous ammonium sulfate-sucrose-xylenol orange in acid aqueous solution

    NASA Astrophysics Data System (ADS)

    Juarez-Calderon, J. M.; Negron-Mendoza, A.; Ramos-Bernal, S.

    2014-11-01

    An aqueous solution of ammonium ferrous sulfate-sucrose-xylenol orange in sulfuric acid (FSX) is proposed as a dosimetric system for the processes of gamma irradiation in a range between 0.3 and 6 Gy. This system is based on the indirect oxidation of ferrous ion by an organic compound (sucrose) to ferric ion and on the formation of a color complex of Fe3+ in an acidic medium with xylenol orange (a dye). After gamma radiation, an observable change occurs in the color of the system. Irradiation was executed at three different temperatures (13 °C, 22 °C, and 40 °C). A spectrometric readout method at 585 nm was employed to evaluate the system's dose response. In all of the cases analyzed, the responses had a linear behavior, and a slight effect of irradiation temperature was observed. Post-irradiation response was also evaluated and showed the stability of the solutions 24 h after the irradiation. The results obtained suggest that FSX might be used as a dosimeter for low doses of gamma irradiation because it provides a stable signal, good reproducibility, and an accessible technique for analysis.

  12. Structural evolution of molybdenum carbides in hot aqueous environments and impact on low-temperature hydroprocessing of acetic acid

    DOE PAGESBeta

    Choi, Jae -Soon; Schwartz, Viviane; Santillan-Jimenez, Eduardo; Crocker, Mark; Lewis, Sr., Samuel A.; Lance, Michael J.; Meyer, III, Harry M.; More, Karren L.

    2015-03-13

    In this paper, we investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore volume and surface area. The extent of these structural changes was sensitive to the initial carbide structure and was lower under actual hydroprocessing conditions indicating themore » possibility of further improving the hydrothermal stability of Mo carbides by optimizing catalyst structure and operating conditions. Mo carbides were active in acetic acid conversion in the presence of liquid water, their activity being comparable to that of Ru/C. Finally, the results suggest that effective and inexpensive bio-oil hydroprocessing catalysts could be designed based on Mo carbides, although a more detailed understanding of the structure-performance relationships is needed, especially in upgrading of more complex reaction mixtures or real bio-oils.« less

  13. How Does the C-Halogen Bond Break in the Photosubstitution Reaction of 3-Fluorobenzophenone in Acidic Aqueous Solutions?

    PubMed

    Huang, Jinqing; Ma, Jiani; Li, Mingde; Liu, Mingyue; Zhang, Xiting; Phillips, David Lee

    2015-10-01

    The efficient photosubstitution reaction of m-fluorobenzophenone and the related photohydration reactions were systematically investigated in acidic aqueous solutions. The mechanisms and intermediates were directly characterized by femtosecond transient absorption spectroscopy and nanosecond time-resolved resonance Raman spectroscopy, which is supported by density functional theory calculations. This photosubstitution was found to be a two-step process, based on the observation of a meta-hydration intermediate. The protonation of the ketone was confirmed as a crucial precursor step for further photochemical reactions as indicated by the observation of the absorption spectrum of an excited triplet protonated species. More interestingly, the efficient photosubstitution reaction could selectively occur under specific conditions. Control experiments on a series of halogen-substituted benzophenones were conducted to study the influence of the solution acidity, substituent positions, and the kind of substituted halogens on the efficiency in forming the corresponding hydroxyl photosubstitution product. Some practical conditions in predicting the efficiency of the photosubstitution reaction of interest are summarized, and they were successfully used to predict when the photosubstitution reaction takes place for some other halogen-substituted benzophenone derivatives. The driving force of this photosubstitution reaction may provide insights into several possible applications which are also briefly discussed. PMID:26322959

  14. Temperature-Induced Aggregate Transitions in Mixtures of Cationic Ammonium Gemini Surfactant with Anionic Glutamic Acid Surfactant in Aqueous Solution.

    PubMed

    Ji, Xiuling; Tian, Maozhang; Wang, Yilin

    2016-02-01

    The aggregation behaviors of the mixtures of cationic gemini surfactant 1,4-bis(dodecyl-N,N-dimethylammonium bromide)-2,3-butanediol (C12C4(OH)2C12Br2) and anionic amino acid surfactant N-dodecanoylglutamic acid (C12Glu) in aqueous solution of pH = 10.0 have been studied. The mixture forms spherical micelles, vesicles, and wormlike micelles at 25 °C by changing mixing ratios and/or total surfactant concentration. Then these aggregates undergo a series of transitions upon increasing the temperature. Smaller spherical micelles transfer into larger vesicles, vesicles transfer into solid spherical aggregates and then into larger irregular aggregates, and entangled wormlike micelles transfer into branched wormlike micelles. Moreover, the larger irregular aggregates and branched micelles finally lead to precipitation and clouding phenomenon, respectively. All these transitions are thermally reversible, and the transition temperatures can be tuned by varying the mixing ratios and/or total concentration. These temperature-dependent aggregate transitions can be elucidated on the basis of the temperature-induced variations in the dehydration, electrostatic interaction, and hydrogen bonds of the headgroup area and in the hydrophobic interaction between the hydrocarbon chains. The results suggest that the surfactants carrying multiple binding sites will greatly improve the regulation ability and temperature sensitivity. PMID:26750978

  15. Electrochemical degradation of trichloroacetic acid in aqueous media: influence of the electrode material.

    PubMed

    Esclapez, M D; Díez-García, M I; Sàez, V; Bonete, P; González-García, José

    2013-01-01

    The electrochemical degradation of trichloroacetic acid (TCAA) in water has been analysed through voltammetric studies with a rotating disc electrode and controlled-potential bulk electrolyses. The influence of the mass-transport conditions and initial concentration of TCAA for titanium, stainless steel and carbon electrodes has been studied. It is shown that the electrochemical reduction of TCAA takes place prior to the massive hydrogen evolution in the potential window for all electrode materials studied. The current efficiency is high (> 18%) compared with those normally reported in the literature, and the fractional conversion is above 50% for all the electrodes studied. Only dichloroacetic acid (DCAA) and chloride anions were routinely detected as reduction products for any of the electrodes, and reasonable values of mass balance error were obtained. Of the three materials studied, the titanium cathode gave the best results. PMID:23530352

  16. A novel, stable, aqueous glucagon formulation using ferulic acid as an excipient.

    PubMed

    Bakhtiani, Parkash A; Caputo, Nicholas; Castle, Jessica R; El Youssef, Joseph; Carroll, Julie M; David, Larry L; Roberts, Charles T; Ward, W Kenneth

    2015-01-01

    Commercial glucagon is unstable due to aggregation and degradation. In closed-loop studies, it must be reconstituted frequently. For use in a portable pump for 3 days, a more stable preparation is required. At alkaline pH, curcumin inhibited glucagon aggregation. However, curcumin is not sufficiently stable for long-term use. Here, we evaluated ferulic acid, a stable breakdown product of curcumin, for its ability to stabilize glucagon. Ferulic acid-formulated glucagon (FAFG), composed of ferulic acid, glucagon, L-methionine, polysorbate-80, and human serum albumin in glycine buffer at pH 9, was aged for 7 days at 37°C. Glucagon aggregation was assessed by transmission electron microscopy (TEM) and degradation by high-performance liquid chromatography (HPLC). A cell-based protein kinase A (PKA) assay was used to assess in vitro bioactivity. Pharmacodynamics (PD) of unaged FAFG, 7-day aged FAFG, and unaged synthetic glucagon was determined in octreotide-treated swine. No fibrils were observed in TEM images of fresh or aged FAFG. Aged FAFG was 94% intact based on HPLC analysis and there was no loss of bioactivity. In the PD swine analysis, the rise over baseline of glucose with unaged FAFG, aged FAFG, and synthetic native glucagon (unmodified human sequence) was similar. After 7 days of aging at 37°C, an alkaline ferulic acid formulation of glucagon exhibited significantly less aggregation and degradation than that seen with native glucagon and was bioactive in vitro and in vivo. Thus, this formulation may be stable for 3-7 days in a portable pump for bihormonal closed-loop treatment of T1D. PMID:25253164

  17. Acidity of the amidoxime functional group in aqueous solution. A combined experimental and computational study

    SciTech Connect

    Mehio, Nada; Lashely, Mark A.; Nugent, Joseph W.; Tucker, Lyndsay; Correia, Bruna; Do-Thanh, Chi-Linh; Dai, Sheng; Hancock, Robert D.; Bryantsev, Vyacheslav S.

    2015-01-26

    Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. It has been demonstrated repeatedly in the literature that the success of these materials is due to the amidoxime functional group. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pKa values that have been reported for the amidoxime functional group in the literature. To resolve this existing controversy we investigated the pKa values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopic titrations to measure the pKa values of representative amidoximes, acetamidoxime and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pKa values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance with a mean absolute error of 0.33 pKa units and 0.35 pKa units, respectively, and a root mean square deviation of 0.46 pKa units and 0.45 pKa units, respectively. Finally, we employ our two best methods to predict the pKa values of promising, uncharacterized amidoxime ligands. Hence, our study provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents used to mine uranium from seawater.

  18. Acidity of the amidoxime functional group in aqueous solution. A combined experimental and computational study

    DOE PAGESBeta

    Mehio, Nada; Lashely, Mark A.; Nugent, Joseph W.; Tucker, Lyndsay; Correia, Bruna; Do-Thanh, Chi-Linh; Dai, Sheng; Hancock, Robert D.; Bryantsev, Vyacheslav S.

    2015-01-26

    Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. It has been demonstrated repeatedly in the literature that the success of these materials is due to the amidoxime functional group. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pKa values that have been reported for the amidoxime functional group in the literature. To resolve this existing controversy we investigated the pKa values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopicmore » titrations to measure the pKa values of representative amidoximes, acetamidoxime and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pKa values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance with a mean absolute error of 0.33 pKa units and 0.35 pKa units, respectively, and a root mean square deviation of 0.46 pKa units and 0.45 pKa units, respectively. Finally, we employ our two best methods to predict the pKa values of promising, uncharacterized amidoxime ligands. Hence, our study provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents used to mine uranium from seawater.« less

  19. Hyaluronic acid-coated niosomes facilitate tacrolimus ocular delivery: Mucoadhesion, precorneal retention, aqueous humor pharmacokinetics, and transcorneal permeability.

    PubMed

    Zeng, Weidong; Li, Qi; Wan, Tao; Liu, Cui; Pan, Wenhui; Wu, Zushuai; Zhang, Guoguang; Pan, Jingtong; Qin, Mengyao; Lin, Yuanyuan; Wu, Chuanbin; Xu, Yuehong

    2016-05-01

    Tacrolimus (FK506) was used to prevent corneal allograft rejection in patients who were resistant to steroids and cyclosporine. However, the formulation for FK506 ocular delivery remained a challenge due to the drug's high hydrophobicity, high molecular weight, and eye's physiological and anatomical constraints. The aim of this project is to develop an ocular delivery system for FK506 based on a combined strategy of niosomes and mucoadhesive hyaluronic acid (HA), i.e., FK506HA-coated niosomes, which exploits virtues of both niosomes and HA to synergistically improve ophthalmic bioavailability. The FK506HA-coated niosomes were characterized with particle size, zeta potential, and rheology behavior. Mucoadhesion of FK506HA-coated niosomes to mucin was investigated through surface plasmon resonance in comparison with non-coated niosomes and HA solution. The results showed that niosomes possessed adhesion to mucin, and HA coating enhanced the adhesion. The in vivo precorneal retention was evaluated in rabbit, and the results showed that HA-coated niosomes prolonged the residence of FK506 significantly in comparison with non-coated niosomes or suspension. Aqueous humor pharmacokinetics test showed that area under curve of HA-coated niosomes was 2.3-fold and 1.2-fold as that of suspension and non-coated niosomes, respectively. Moreover, the synergetic corneal permeability enhancement of the hybrid delivery system on FK506 was visualized and confirmed by confocal laser scanning microscope. Overall, the results indicated that the hybrid system facilitated FK506 ocular delivery on mucoadhesion, precorneal retention, aqueous humor pharmacokinetics and transcorneal permeability. Therefore, HA-coated niosomes may be a promising approach for ocular targeting delivery of FK506. PMID:26820107

  20. Effect of Humic Acid on Migration, Distribution and Remediation of Dense Non-aqueous Phase Liquids: A laboratory investigation

    NASA Astrophysics Data System (ADS)

    Cheng, Z.; Wu, J.; Xu, H.; Gao, Y.

    2014-12-01

    Over the last decades, dense non-aqueous phase liquids (DNAPLs) contamination in the subsurface increases with the rapid development of oil industry and becomes the focus of many studies. The migration, distribution and remediation efficiency of DNAPLs in the subsurface environment are greatly affected by the solution chemistry besides the physical heterogeneities of aquifers. Humic acid (HA), which is ubiquitous in natural environments, is a surface active substance exhibiting solubility enhancement behavior for hydrophobic organic compounds such as DNAPLs. Here we reported a laboratory investigation to study the effects of HA on the infiltration, immobilization and subsequent recovery of DNAPL in porous media. Tetrachloroethylene (PCE) was selected as the representative DNAPL in this study. Two-dimensional (2-D) sandbox experiments were conducted to investigate the effects of different HA concentrations on the transport, distribution of PCE and the remediation of PCE using surfactant (Tween 80) flushing in a saturated porous media system. The surfactant flushing of PCE was performed after the PCE transport and distribution had reached equilibrium. A light transmission visualization method with charge-coupled device (CCD) camera was adopted to visualize PCE distribution and quantify its saturation. In addition, the experiments were also designed to gather data for the validation of multiphase flow models. Effluent samples were collected to determine dissolved PCE concentrations. PCE solubilization and PCE-water interfacial tension were experimentally determined in aqueous solutions of varying HA concentrations. The experimental results showed that the presence of HA can have a dramatic impact on PCE flow and entrapment, and significantly improved the recovery of PCE during surfactant enhanced aquifer remediation (SEAR). The findings are of use for better understanding of the migration and entrapment of DNAPLs and developing of SEAR technology.

  1. Shikimic acid ozonolysis kinetics of the transition from liquid aqueous solution to highly viscous glass.

    PubMed

    Steimer, Sarah S; Berkemeier, Thomas; Gilgen, Anina; Krieger, Ulrich K; Peter, Thomas; Shiraiwa, Manabu; Ammann, Markus

    2015-12-14

    Ageing of particulate organic matter affects the composition and properties of atmospheric aerosol particles. Driven by temperature and humidity, the organic fraction can vary its physical state between liquid and amorphous solid, or rarely even crystalline. These transitions can influence the reaction kinetics due to limitations of mass transport in such (semi-) solid states, which in turn may influence the chemical ageing of particles containing such compounds. We have used coated wall flow tube experiments to investigate the reaction kinetics of the ozonolysis of shikimic acid, which serves as a proxy for oxygenated, water-soluble organic matter and can form a glass at room temperature. Particular attention was paid to how the presence of water influences the reaction, since it acts a plasticiser and thereby induces changes in the physical state. We analysed the results by means of a traditional resistor model, which assumes steady-state conditions. The ozonolysis rate of shikimic acid is strongly increased in the presence of water, a fact we attribute to the increased transport of O3 and shikimic acid through the condensed phase at lower viscosities. The analysis using the resistor model suggests that the system undergoes both surface and bulk reaction. The second-order rate coefficient of the bulk reaction is 3.7 (+1.5/-3.2) × 10(3) L mol(-1) s(-1). At low humidity and long timescales, the resistor model fails to describe the measurements appropriately. The persistent O3 uptake at very low humidity suggests contribution of a self-reaction of O3 on the surface. PMID:26536455

  2. Cassava starch maltodextrinization/monomerization through thermopressurized aqueous phosphoric acid hydrolysis.

    PubMed

    Fontana, J D; Passos, M; Baron, M; Mendes, S V; Ramos, L P

    2001-01-01

    Kinetic conditions were established for the depolymerization of cassava starch for the production of maltodextrins and glucose syrups. Thin-layer chromatography and high-performance liquid chromatography analyses corroborated that the proper H3PO4 strength and thermopressurization range (e.g., 142-170 degrees C; 2.8-6.8 atm) can be successfully explored for such hydrolytic purposes of native starch granules. Because phosphoric acid can be advantageously maintained in the hydrolysate and generates, after controlled neutralization with ammonia, the strategic nutrient triplet for industrial fermentations (C, P, N), this pretreatment strategy can be easily recognized as a recommended technology for hydrolysis and upgrading of starch and other plant polysaccharides. Compared to the classic catalysts, the mandatory desalting step (chloride removal by expensive anion-exchange resin or sulfate precipitation as the calcium-insoluble salt) can be avoided. Furthermore, properly diluted phosphoric acid is well known as an allowable additive in several popular soft drinks such as colas since its acidic feeling in the mouth is compatible and synergistic with both natural and artificial sweeteners. Glycosyrups from phosphorolyzed cassava starch have also been upgraded to high-value single-cell protein such as the pigmented yeast biomass of Xanthophyllomyces dendrorhous (Phaffia rhodozyma), whose astaxanthin (diketo-dihydroxy-beta-carotene) content may reach 0.5-1.0 mg/g of dry yeast cell. This can be used as an ideal complement for animal feeding as well as a natural staining for both fish farming (meat) and poultry (eggs). PMID:11963875

  3. Synthesis of high intrinsic loss power aqueous ferrofluids of iron oxide nanoparticles by citric acid-assisted hydrothermal-reduction route

    SciTech Connect

    Behdadfar, Behshid; Kermanpur, Ahmad; Sadeghi-Aliabadi, Hojjat; Morales, Maria del Puerto; Mozaffari, Morteza

    2012-03-15

    Monodispersed aqueous ferrofluids of iron oxide nanoparticle were synthesized by hydrothermal-reduction route. They were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and dynamic light scattering. The results showed that certain concentrations of citric acid (CA) are required to obtain only magnetic iron oxides with mean particle sizes around 8 nm. CA acts as a modulator and reducing agent in iron oxide formation which controls nanoparticle size. The XRD, magnetic and heating measurements showed that the temperature and time of hydrothermal reaction can affect the magnetic properties of obtained ferrofluids. The synthesized ferrofluids were stable at pH 7. Their mean hydrodynamic size was around 80 nm with polydispersity index (PDI) of 0.158. The calculated intrinsic loss power (ILP) was 9.4 nHm{sup 2}/kg. So this clean and cheap route is an efficient way to synthesize high ILP aqueous ferrofluids applicable in magnetic hyperthermia. - Graphical abstract: Monodispersed aqueous ferrofluids of iron oxide nanoparticles were synthesized by hydrothermal-reduction method with citric acid as reductant which is an efficient way to synthesize aqueous ferrofluids applicable in magnetic hyperthermia. Highlights: Black-Right-Pointing-Pointer Aqueous iron oxide ferrofluids were synthesized by hydrothermal-reduction route. Black-Right-Pointing-Pointer Citric acid acted as reducing agent and surfactant in the route. Black-Right-Pointing-Pointer This is a facile, low energy and environmental friendly route. Black-Right-Pointing-Pointer The aqueous iron oxide ferrofluids were monodispersed and stable at pH of 7. Black-Right-Pointing-Pointer The calculated intrinsic loss power of the synthesized ferrofluids was very high.

  4. REDUCTION OF PLUTONIUM VALUES IN AN ACIDIC AQUEOUS SOLUTION WITH FORMALDEHYDE

    DOEpatents

    Olson, C.M.

    1959-06-01

    A method is given for reducing Pu to the tetravalent state and lowering the high acidity of dissolver solutions containing U and Pu. Formaldehyde is added to the HNO/sub 3/ solution of U and Pu to effect a formaldehyde to HNO/sub 3/ molar ratio of 0.375:1 to 1.5:1. The Pu can then be removed from the solution by carrier precipitation using BiPO/sub 4/ or by ion exchange. (T.R.H.)

  5. Factors affecting the removal of chlorendic acid from aqueous solutions using high energy electron irradiation

    SciTech Connect

    Taylor, T.C.; Cooper, W.J.; Nickelsen, M.G. ); Kurucz, C.N.; Waite, T.D. )

    1990-01-01

    Irradiation of water has been studied for many years. In pure water, the product distribution is well known and results in the formation of several highly reactive radical species. These radical species, e{sup {minus}} ag, H{sup {sm bullet}} and OH{sup {sm bullet}}, are known to react with many organic compounds. Thus, it appears that this treatment may be of interest in treating waste streams which contain compounds of known threat to the environment. This paper will provide initial results of experiments on the removal of chlorendic acid in wastewater.

  6. Transport phenomena accompanying redox switching in polythionine films immersed in aqueous acetic acid solutions

    SciTech Connect

    Bruckenstein, S.; Wilde, C.P. ); Hillman, A.R. )

    1990-08-09

    The transport of neutral molecules in electroactive polymer films is a problem of considerable importance and is addressed here for thin (ca. 10 nm thick) polythionine films. In weak acid media, pH < pK{sub HA}, both solvent and undissociated weak acid are present in the polymer. Raising the pH above pK{sub HA} progressively removes HA. Using the quartz crystal microbalance, we determined the film weight changes accompanying the redox switching process. At all pH's studied, a mass decrease accompanies reduction. The magnitude of this change is consistent with the expulsion of one water molecule per redox site where, at low pH, HA within the film acts as the sole source of counterion, A{sup {minus}}. At higher pH, counterions must increasingly be supplied by the bathing solution, with the result that the mass change becomes less negative. These results are interpreted from a purely thermodynamic viewpoint, and then we discuss a coordination model as a relevant, special case.

  7. Kinetics and mechanism of the oxidation of bromide by periodate in aqueous acidic solution.

    PubMed

    Szél, Viktor; Csekő, György; Horváth, Attila K

    2014-11-13

    The periodate–bromide reaction has been studied spectrophotometrically mainly in excess of bromide ion, monitoring the formation of the total amount of bromine at 450 nm at acidic buffered conditions and at a constant ionic strength in the presence of a phosphoric acid/dihydrogen phosphate buffer. The stoichiometry of the reaction was established to be strictly IO4(–) + 2Br(–) + 2H(+) → Br2 + IO3(–) + H2O. The formal kinetic order of the reactants was found to be perfectly one and two in the cases of periodate and bromide, respectively, but that of the hydrogen ion lies between one and two. We have also provided experimental evidence that dihydrogen phosphate accelerates the formation of bromine, suggesting the appearance of strong buffer assistance. On the basis of the experiments, a simple two-step kinetic model is proposed involving BrIO3 as a key intermediate that perfectly explains all of the experimental findings. Furthermore, we have also shown that in huge excess of bromide, the apparent rate coefficient obtained from the individual curve fitting method of the absorbance–time series is necessarily independent of the initial periodate concentration that may falsely be interpreted as the rate of bromine formation is also independent of the concentration of periodate. PMID:25365468

  8. Sulphur selective ablation by UV laser

    NASA Astrophysics Data System (ADS)

    Lorusso, Antonella; Nassisi, Vincenzo; Belloni, Fabio; Buccolieri, Giovanni; Caretto, Giuseppe; Castellano, Alfredo

    2005-06-01

    In this work we report the preliminary experimental results on the selective ablation of sulphur in ancient stones. The sulphur concentration was reduced after laser action. For this goal an excimer laser operating at 308 nm wavelength and time duration of 20 ns was used. In order to estimate the sulphur concentration before and after laser cleaning, a portable apparatus for energy-dispersive X-ray fluorescence (EDXRF) was utilised. The processed sample were characterized by an initial sulphur concentration of 2.8% w/w. After the laser treatment, sulphur concentration decreased after a total deposited energy of about 30 J/cm2 up to 1.2% w/w value. Due to the porosity of the stone, in fact, it is difficult to eliminate completely the S presence in the composition of the stones. It was also observed that after a few laser shots the initial black area of the stone became white showing in this way the great potential of the laser action on the cleaning process of the pietra leccese.

  9. 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

  10. Recombinant D. radiodurans cells for bioremediation of heavy metals from acidic/neutral aqueous wastes.

    PubMed

    Misra, Chitra Seetharam; Appukuttan, Deepti; Kantamreddi, Venkata Siva Satyanarayana; Rao, Amara S; Apte, Shree Kumar

    2012-01-01

    The stability and superior metal bioremediation ability of genetically engineered Deinococcus radiodurans cells, expressing a non-specific acid phosphatase, PhoN in high radiation environment has already been established. The lyophilized recombinant DrPhoN cells retained PhoN activity and uranium precipitation ability. Such cells also displayed an extended shelf life of 6 months during storage at room temperature and showed surface associated precipitation of uranium as well as other metals like cadmium. Lyophilized cells, immobilized in polyacrylamide gels could be used for uranium bioprecipitation in a flow through system resulting in 70% removal from 1mM input uranium solution and a loading of 1 g uranium/g dry weight cells. Compared with a batch process which achieved a loading of 5.7 g uranium/g biomass, the efficiency of the column process was low due to clogging of the column by the precipitate. PMID:22179144

  11. Spectrophotometric determination of Rare Earth Elements in aqueous nitric acid solutions for process control.

    PubMed

    Rodionova, Oxana Ye; Tikhomirova, Tatyana I; Pomerantsev, Alexey L

    2015-04-15

    Noninvasive analytical control is of special interest for the complicated and hazardous production processes. On-line monitoring provides a unique opportunity to determine critical concentrations rapidly and without serious risks to operating personnel and the environment. Models for quantitative determination of concentrations of Rare Earth Elements in complex mixtures in nitric acid serve for these purposes. Here, the feasibility of simultaneous determination of cerium, praseodymium, and neodymium using the whole UV-vis spectroscopic range, together with chemometric data processing, is studied. The predictability of two chemometric techniques, partial least squares regression and correlation constrained multivariate curve resolution-alternating least squares are compared. Models' performances are analyzed in out-of-control cases. PMID:25818140

  12. Factor analysis for isolation of the Raman spectra of aqueous sulfuric acid components

    SciTech Connect

    Malinowski, E.R.; Cox, R.A.; Haldna, U.L.

    1984-04-01

    The Raman spectra of 16 sulfuric acid/water mixtures over the entire mole fraction range were studied by various factor analysis techniques. Abstract factor analysis showed that three factors account for 98.69% of the variation in the data with a real error of 13%. Key-set factor analysis, was used to identify three spectral wavenumbers unique to each component. Spectral-isolation factor analysis, based on the key wavenumbers, revealed the spectra of each unknown component. Target factor analysis, based on the isolated spectra, yielded the relative amounts of the three spectral components. The concentration profiles obtained from the factor loadings, as well as the isolated spectra, were used to identify the chemical species.

  13. Adsorption kinetics and thermodynamics of acid Bordeaux B from aqueous solution by graphene oxide/PAMAMs.

    PubMed

    Zhang, Fan; He, Shengfu; Zhang, Chen; Peng, Zhiyuan

    2015-01-01

    Graphene oxide/polyamidoamines dendrimers (GO/PAMAMs) composites were synthesized via modifying GO with 2.0 G PAMAM. The adsorption behavior of the GO/PAMAMs for acid Bordeaux B (ABB) was studied and the effects of media pH, adsorption time and initial ABB concentration on adsorption capacity of the adsorbent were investigated. The optimum pH value of the adsorption of ABB onto GO/PAMAMs was 2.5. The maximum adsorption capacity increased from 325.78 to 520.83 mg/g with the increase in temperature from 298 to 328 K. The equilibrium data followed the Langmuir isotherm model better than the Freundlich model. The kinetic study illustrated that the adsorption of ABB onto GO/PAMAMs fit the pseudo-second-order model. The thermodynamic parameters indicated that the adsorption process was physisorption, and also an endothermic and spontaneous process. PMID:26398038

  14. 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

  15. Compartmentalization of amino acids in surfactant aggregates - Partitioning between water and aqueous micellar sodium dodecanoate and between hexane and dodecylammonium propionate trapped water in hexane

    NASA Technical Reports Server (NTRS)

    Fendler, J. H.; Nome, F.; Nagyvary, J.

    1975-01-01

    The partitioning of amino acids (glycine, alanine, leucine, phenylalanine, histidine, aspartic acid, glutamic acid, lysine, isoleucine, threonine, serine, valine, proline, arginine) in aqueous and nonaqueous micellar systems was studied experimentally. Partitioning from neat hexane into dodecylammonium propionate trapped water in hexane was found to be dependent on both electrostatic and hydrophobic interactions, which implies that the interior of dodecylammonium propionate aggregates is negatively charged and is capable of hydrogen bonding in addition to providing a hydrophobic environment. Unitary free energies of transfer of amino acid side chains from hexane to water were determined and solubilities of amino acids in neat hexane substantiated the amino acid hydrophobicity scale. The relevance of the experiments to prebiotic chemistry was examined.

  16. Dissolution kinetics of kaolinite in acidic aqueous solutions at 25 C

    SciTech Connect

    Wieland, E.; Stumm, W. Swiss Federal Inst. of Tech., Zuerich )

    1992-09-01

    The dissolution of kaolinite is interpreted in terms of the surface complexation model. Acid/base properties of the terminal OH groups and ion exchange reactions occurring at the kaolinite surface have been investigated. A three-site model incorporating solid-solution equilibria at aluminol groups of the edge and gibbsite surfaces and at negatively charged XO groups of the siloxane surface account for the protonation of kaolinite platelets in acidic solutions. The dissolution kinetics of kaolinite at 25 C has been studied as a function of solution pH. The dissolution of kaolinite is nonstoichiometric in the pH range 2-6.5 with a preferential release of silicon. Stoichiometry of the dissolution reaction is achieved, however, in the presence of oxalate as Al-complexing ligand. The detachment of aluminium from the lattice structure of the kaolinite surface and its readsorption on distinct surface sites occur simultaneously during the dissolution process causing the experimentally observed nonstoichiometry. The proton-promoted dissolution of kaolinite occurs at the edge surface (pH < 6.5) and the gibbsite surface (pH < 4). The pH-dependence of the dissolution rate R[sub H](Si) reflects sequential protonation of terminal OH groups on both surfaces. The dissolution reaction can be interpreted as a coupled release of Al and Si with the detachment of the Al center from the surface lattice structure as the rate-limiting step. The aluminium:proton stoichiometry of the activated complex is 1:3 at the gibbsite surface and 1:1 at the edge surface.

  17. GEOCHEMICAL FEATURES OF WATER-ROCK INTERACTIONS AT THE SULPHUR BANK MERCURY MINE, LAKE COUNTY, CALIFORNIA

    EPA Science Inventory

    The Sulphur Bank Mercury Mine on the eastern shore of Clear Lake is the source of poor quality acid mine drainage seeping into Clear Lake. Lateral and vertical geochemical trends in ground water composition point to a number of redox reactions taking place as a function of subsu...

  18. Enhanced catalytic performance of Pd catalyst for formic acid electrooxidation in ionic liquid aqueous solution

    NASA Astrophysics Data System (ADS)

    Feng, Yuan-Yuan; Yin, Qian-Ying; Lu, Guo-Ping; Yang, Hai-Fang; Zhu, Xiao; Kong, De-Sheng; You, Jin-Mao

    2014-12-01

    A protic ionic liquid (IL), n-butylammonium nitrate (N4NO3), is prepared and employed as the electrolyte for formic acid electrooxidation reaction (FAOR) on Pd catalysts. The oxidation peak potential of FAOR in the IL solution shows about a 200 mV negative shift as compared with those in traditional H2SO4/HClO4 electrolytes, suggesting that FAOR can be more easily carried out on Pd catalysts in IL media. The catalytic properties of Pd toward FAOR are not only dependent on the concentration of IL, as a consequence of the varied electronic conductivity of the IL solution, but also on the high potential limit of the cyclic voltammograms. When the Pd catalyst is cycled up to 1.0 V (vs. SCE), which induces a significant oxidation of Pd, it shows ca. 4.0 times higher activity than that not subjected to the Pd oxidation (up to 0.6 V). The Pd oxides, which are more easily formed in IL solution than in traditional H2SO4/HClO4 electrolytes, may play a crucial role in increasing the catalytic activities of Pd toward FAOR. Our work would shed new light on the mechanism of FAOR and highlight the potential applications of IL as green and environment-friendly electrolytes in fuel cells and other technologies.

  19. Sequence dependent N-terminal rearrangement and degradation of peptide nucleic acid (PNA) in aqueous solution

    NASA Technical Reports Server (NTRS)

    Eriksson, M.; Christensen, L.; Schmidt, J.; Haaima, G.; Orgel, L.; Nielsen, P. E.

    1998-01-01

    The stability of the PNA (peptide nucleic acid) thymine monomer inverted question markN-[2-(thymin-1-ylacetyl)]-N-(2-aminoaminoethyl)glycine inverted question mark and those of various PNA oligomers (5-8-mers) have been measured at room temperature (20 degrees C) as a function of pH. The thymine monomer undergoes N-acyl transfer rearrangement with a half-life of 34 days at pH 11 as analyzed by 1H NMR; and two reactions, the N-acyl transfer and a sequential degradation, are found by HPLC analysis to occur at measurable rates for the oligomers at pH 9 or above. Dependent on the amino-terminal sequence, half-lives of 350 h to 163 days were found at pH 9. At pH 12 the half-lives ranged from 1.5 h to 21 days. The results are discussed in terms of PNA as a gene therapeutic drug as well as a possible prebiotic genetic material.

  20. Synthesis and Evaluation of Molecularly Imprinted Silica Gel for 2-Hydroxybenzoic Acid in Aqueous Solution

    PubMed Central

    Abdul Raof, Siti Farhana; Mohamad, Sharifah; Abas, Mhd Radzi

    2013-01-01

    A molecularly imprinted silica gel sorbent for selective removal of 2-Hydroxybenzoic acid (2-HA) was prepared by a surface imprinting technique with a sol-gel process. The 2-HA molecularly imprinted silica gel (2-HA-MISG) sorbent was evaluated by various parameters, including the influence of pH, static, kinetic adsorption and selectivity experiments. The optimum adsorption capacity to the 2-HA appeared to be around pH 2 by the polymer. Morevoer, the imprinted sorbent displayed fast uptake kinetics, obtained within 20 min. The adsorption capacity of the 2-HA-MISG (76.2 mg g−1) was higher than that of the non-imprinted silica gel (NISG) (42.58 mg g−1). This indicates that the 2-HA-MISG offers a higher affinity for 2-HA than the NISG. The polymer displays good selectivity and exhibits good reusability. Experimental results show the potential of molecularly imprinted silica sorbent for selective removal of 2-HA. PMID:23493059

  1. Effect of acid hydrolysis on regenerated kenaf core membrane produced using aqueous alkaline-urea systems.

    PubMed

    Padzil, Farah Nadia Mohammad; Zakaria, Sarani; Chia, Chin Hua; Jaafar, Sharifah Nabihah Syed; Kaco, Hatika; Gan, Sinyee; Ng, Peivun

    2015-06-25

    Bleached kenaf core pulps (BKC) were hydrolyzed in H2SO4 (0.5M) at different time (0min to 90min) at room temperature. After the hydrolysis process, the viscosity average molecular weight (Mŋ) for BKC sample has reduced from 14.5×10(4) to 2.55×10(4). The hydrolyzed BKC was then dissolved in NaOH:urea:water and in LiOH:urea:water mixed solvent at the ratio of 7:12:81 and 4.6:15:80.4, respectively. The increased in hydrolysis time has decreased Mŋ of cellulose leading to easy dissolution process. Higher porosity and transparency with lower crystallinity index (CrI) of regenerated membrane produced can be achieved as the Mŋ reduced. The properties of membrane were observed through FESEM, UV-vis spectrophotometer and XRD. This study has proven that acid hydrolysis has reduced the Mŋ of cellulose, thus, enhanced the properties of regenerated membrane produced with assisted by alkaline/urea system. PMID:25839807

  2. Adsorption of 2,4-Dichlorophenoxyacetic Acid from an Aqueous Solution on Fly Ash.

    PubMed

    Kuśmierek, Krzysztof; Świątkowski, Andrzej

    2016-03-01

    The adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on fly ash was studied. The effects of adsorbent dose, contact time, pH, ionic strength, and temperature on the adsorption were investigated. Adsorption kinetic data were analyzed using pseudo-first and pseudo-second order models, and results showed that adsorption kinetics were better represented by the pseudo-second order model. Adsorption isotherms of 2,4-D on fly ash were analyzed using the Freundlich and Langmuir models. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicated that the adsorption process was spontaneous and endothermic. The negative values of ΔG° and the positive value of ΔH° indicate the spontaneous nature of 2,4-D adsorption on fly ash, and that the adsorption process was endothermic. Results showed that fly ash is an efficient, low-cost adsorbent for removal of 2,4-D from water. PMID:26931534

  3. The initiation of material corrosion in semicritical and supercritical aqueous hydrochloric acid solutions

    SciTech Connect

    Boukis, N.; Kritzer, P.; Schacht, M.; Dinjus, E.

    1999-11-01

    In recent years, a lot of work has been performed to interpret corrosion during the process of supercritical water oxidation (SCWO). For a better understanding of the corrosion mechanisms, the initiation processes of corrosion have to be known. The corrosion resistance of two alumina ceramics and sapphire in hydrochloric acid (HCl) solutions was investigated at T = 240 C -- 500 C and p = 27 MPa. For the alumina ceramics, intergranular corrosion and dissolution of the grains were identified as corrosion mechanisms. The corrosion experiments with the nickel-base alloy 625 (UNS N06625) and its main constituents nickel, chromium, and molybdenum were performed in oxygenated HCl solutions at T = 350 C and p = 24 MPa. Nickel and molybdenum showed severe weight loss after only 5 h of reaction. The attack on chromium started with grain boundary etching and proceeded via the formation of thick, spalling oxide layers on the surface. Initial corrosion phenomena observed on alloy 625 were intergranular attack and pit formation. At longer reaction times, a complete surface attack was observed.

  4. 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.

  5. Kinetics and thermodynamic studies for removal of acid blue 129 from aqueous solution by almond shell

    PubMed Central

    2014-01-01

    Efficiency and performance of Almond shell (AS) adsorbent for the removal and recovery of Acid Blue 129 (AB129) from wastewater is presented in this report. The influence of variables including pH, initial dye concentration, adsorbent dosage, particle size, contact time and temperature on the dye removal have been investigated in batch method by one at a time optimization method. The experimental equilibrium data were tested by four widely used isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich (D–R). It was found that adsorption of AB129 on AS well with the Langmuir isotherm model, implying monolayer coverage of dye molecules onto the surface of the adsorbent. More than 98% removal efficiency was obtained within 14 min at adsorbent dose of 0.4 g for initial dye concentration of 40 mg/L at pH 2. Kinetics of the adsorption process was tested by pseudo-first-order and pseudo-second-order kinetics, and intraparticle diffusion mechanism. Pseudo-second-order kinetic model provided a better correlation for the experimental data studied in comparison to the pseudo-first-order model. Calculation of various thermodynamic parameters such as, Gibb’s free energy, entropy and enthalpy of the on-going adsorption process indicate feasibility and endothermic nature of AB129 adsorption on all adsorbents. This work can be used in design of adsorption columns for dyes removal. PMID:24620822

  6. Transport of trivalent and hexavalent chromium through different ion-selective membranes in acidic aqueous media

    SciTech Connect

    Costa, R.F.D.; Rodrigues, M.A.S.; Ferreira, J.Z.

    1998-06-01

    The aim of this work was to evaluate the transport of trivalent and hexavalent chromium through anion- and cation-selective membranes using two- and three-compartment electrodialysis cells. Tests were done with acidic solutions of trivalent chromium ions, Cr{sup 3+}, and hexavalent chromium ions, Cr{sub 2}O{sub 7}{sup 2{minus}}. In each situation the transport of metallic ions through the membrane was evaluated. In the tests with trivalent chromium, Nafion 417 and Selemion CMT cation-selective membranes were used, and in the tests with hexavalent chromium, Selemion AMT membrane was used. The influence of SO{sub 4}{sup 2{minus}} ions and of the concentration of H{sup +} ions in the solutions was also analyzed. Results showed the oxidation of the Cr{sup 3+} ion at the anode and the reduction of the Cr{sub 2}O{sub 7}{sup 2{minus}} ion at the cathode. The maximum yield in the process was reached when hexavalent chromium solutions were used in the absence of sulfate ions and a Selemion AMT membrane in a three-compartment cell.

  7. Biosorption of clofibric acid and carbamazepine in aqueous solution by agricultural waste rice straw.

    PubMed

    Liu, Zhanguang; Zhou, Xuefei; Chen, Xiaohua; Dai, Chaomeng; Zhang, Juan; Zhang, Yalei

    2013-12-01

    Due to their widespread use, clofibric acid (CA) and carbamazepine (CBZ) have been frequently detected simultaneously at relatively high concentrations in aquatic environments. In this study, agricultural waste rice straw was employed as a potentially low-cost, effective and easy-to-operate biosorbent (RSB) to remove CA and CBZ. The adsorption of both pharmaceuticals followed pseudo second-order kinetics, and intraparticle diffusion was an important rate-limiting step. The adsorption isotherms of both drugs were fit well with Freundlich model. The adsorption of CA onto RSB was exothermic and was more likely to be dominated by physical processes, while the adsorption of CBZ was endothermic. Solution pH was determined to be the most important factor for CA adsorption, such that the adsorption capacity of CA onto RSB increased with the decline of solution pH. In the lower range of solution pH below 3.1, the CA removal efficiency was enhanced with the increase of biosorbent dosage. The CBZ removal efficiency was enhanced with the increase of RSB dosage without pH control. The maximum adsorption capacities were 126.3 mg/g for CA and 40.0 mg/g for CBZ. PMID:24649668

  8. Lithium-sulphur battery with activated carbon cloth-sulphur cathode and ionic liquid as electrolyte

    NASA Astrophysics Data System (ADS)

    Swiderska-Mocek, Agnieszka; Rudnicka, Ewelina

    2015-01-01

    In this study a binder-free activated carbon cloth-sulphur (ACC-S) composite cathode is presented. Such a cathode was obtained using the impregnating technique of microporous activated carbon cloth with elemental melted sulphur. The surface morphology of an activated carbon cloth-sulphur electrode was studied using a scanning electron microscope (SEM), which was equipped with an EDX spectroscopy attachment. Electrochemical properties of the ACC-S composite cathode was tested in an ionic liquid electrolyte consisting of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide (EtMeImNTf2) and bis(trifluoromethanesulphonyl)imide (LiNTf2). The ACC-sulphur cathode working together with lithium anode was tested with the use of cyclic voltammetry (CV), galvanostatic charge/discharge cycles and electrochemical impedance spectroscopy (EIS). The capacity and cyclic stability of the ACC-S composite cathode were much better than those for the sulphur cathode (a mixture of sulphur from graphene nanoplatelets and carbon black) tested in the same ionic liquid electrolyte. The ACC-sulphur cathode showed good cyclability and coulombic efficiency (99%) with the ionic liquid electrolyte. The reversible capacity of the ACC-S|electrolyte|Li cell was ca. 830 mAh g-1 after 50 cycles.

  9. Point-of-service, quantitative analysis of ascorbic acid in aqueous humor for evaluating anterior globe integrity

    PubMed Central

    Gartia, Manas R.; Misra, Santosh K.; Ye, Mao; Schwartz-Duval, Aaron; Plucinski, Lisa; Zhou, Xiangfei; Kellner, David; Labriola, Leanne T.; Pan, Dipanjan

    2015-01-01

    Limited training, high cost, and low equipment mobility leads to inaccuracies in decision making and is concerning with serious ocular injuries such as suspected ruptured globe or post-operative infections. Here, we present a novel point-of-service (POS) quantitative ascorbic acid (AA) assay with use of the OcuCheck Biosensor. The present work describes the development and clinical testing of the paper-based biosensor that measures the changes in electrical resistance of the enzyme-plated interdigitated electrodes to quantify the level of AA present in ocular fluid. We have demonstrated the proof-of-concept of the biosensor testing 16 clinical samples collected from aqueous humor of patients undergoing therapeutic anterior chamber paracentesis. Comparing with gold standard colorimetric assay for AA concentration, OcuCheck showed accuracy of >80%, sensitivity of >88% and specificity of >71%. At present, there are no FDA-approved POS tests that can directly measures AA concentration levels in ocular fluid. We envisage that the device can be realized as a handheld, battery powered instrument that will have high impact on glaucoma care and point-of-care diagnostics of penetrating ocular globe injuries. PMID:26525715

  10. Point-of-service, quantitative analysis of ascorbic acid in aqueous humor for evaluating anterior globe integrity

    NASA Astrophysics Data System (ADS)

    Gartia, Manas R.; Misra, Santosh K.; Ye, Mao; Schwartz-Duval, Aaron; Plucinski, Lisa; Zhou, Xiangfei; Kellner, David; Labriola, Leanne T.; Pan, Dipanjan

    2015-11-01

    Limited training, high cost, and low equipment mobility leads to inaccuracies in decision making and is concerning with serious ocular injuries such as suspected ruptured globe or post-operative infections. Here, we present a novel point-of-service (POS) quantitative ascorbic acid (AA) assay with use of the OcuCheck Biosensor. The present work describes the development and clinical testing of the paper-based biosensor that measures the changes in electrical resistance of the enzyme-plated interdigitated electrodes to quantify the level of AA present in ocular fluid. We have demonstrated the proof-of-concept of the biosensor testing 16 clinical samples collected from aqueous humor of patients undergoing therapeutic anterior chamber paracentesis. Comparing with gold standard colorimetric assay for AA concentration, OcuCheck showed accuracy of >80%, sensitivity of >88% and specificity of >71%. At present, there are no FDA-approved POS tests that can directly measures AA concentration levels in ocular fluid. We envisage that the device can be realized as a handheld, battery powered instrument that will have high impact on glaucoma care and point-of-care diagnostics of penetrating ocular globe injuries.

  11. Efficient photocatalytic degradation of acid fuchsin in aqueous solution using separate porous tetragonal-CuFe2O4 nanotubes.

    PubMed

    Jing, Panpan; Li, Jianan; Pan, Lining; Wang, Jianbo; Sun, Xiaojun; Liu, Qingfang

    2015-03-01

    To develop a new promising magnetic photocatalyst, homogeneous tetragonal-CuFe2O4 (t-CuFe2O4) nanotubes were successfully synthesized via the electrospinning technique followed by heating treatment. The detailed investigation of chemical phase and microstructure reveals that the obtained samples are inversely spinel CuFe2O4 nanotubes with an average diameter of about 272±2nm, which are assembled by numerous CuFe2O4 single crystal nanoparticles with regular polyhedron structure and possess a very outstanding porous feature. Furthermore, element mapping, UV-vis adsorption spectrum, N2 adsorption-desorption isotherm, and magnetic hysteresis loop indicate that these t-CuFe2O4 nanotubes have uniform component distribution, strong light response in the range of 200 nm-800 nm, considerable specific surface area of 12.8 m(2)/g and porosity of 15.5 nm, and enough magnetization of about 18 emu/g. Therefore, the t-CuFe2O4 nanotubes show an excellent catalytic activity and durability for the photodecomposition of acid fuchsin dye in aqueous solution under a simulated sunlight source. Furthermore, these CuFe2O4 nanotubes could be acted as an eco-friendly and recyclable photocatalyst because they can be efficiently separated from the residual solution. Finally, a mechanism is presented for the significant photocatalytic performance of the porous CuFe2O4 nanotubes. PMID:25463230

  12. Rhodamine-modified upconversion nanophosphors for ratiometric detection of hypochlorous acid in aqueous solution and living cells.

    PubMed

    Zhou, Yi; Pei, Wenbo; Wang, Chenyuan; Zhu, Jixin; Wu, Jiansheng; Yan, Qinyu; Huang, Ling; Huang, Wei; Yao, Cheng; Loo, Joachim Say Chye; Zhang, Qichun

    2014-09-10

    Hypochlorous acid (HOCl), a reactive oxygen species (ROS) produced by myeloperoxidase (MPO) enzyme-mediated peroxidation of chloride ions, acts as a key microbicidal agent in immune systems. However, misregulated production of HOCl could damage host tissues and cause many inflammation-related diseases. Due to its biological importance, many efforts have been focused on developing fluorescent probes to image HOCl in living system. Compared with those conventional fluorescent probes, up-conversion luminescence (UCL) detection system has been proven to exhibit a lot of advantages including no photo-bleaching, higher light penetration depth, no autofluorescence and less damage to biosamples. Herein, we report a novel water-soluble organic-nano detection system based on rhodamine-modified UCNPs for UCL-sensing HOCl. Upon the interaction with HOCl, the green UCL emission intensity in the detection system were gradually decreased, but the emissions in the NIR region almost have no change, which is very important for the ratiometric UCL detection of HOCl in aqueous solution. More importantly, RBH1-UCNPs could be used for the ratiometric UCL visualization of HOCl released by MPO-mediated peroxidation of chloride ions in living cells. This organic-nano system could be further developed into a novel next-generation imaging technique for bio-imaging HOCl in living system without background noise. PMID:24497481

  13. Preparation and characterization of irradiated carboxymethyl sago starch-acid hydrogel and its application as metal scavenger in aqueous solution.

    PubMed

    Basri, Sri Norleha; Zainuddin, Norhazlin; Hashim, Kamaruddin; Yusof, Nor Azah

    2016-03-15

    Carboxymethyl sago starch-acid hydrogel was prepared via irradiation technique to remove divalent metal ions (Pb, Cu and Cd) from their aqueous solution. The hydrogel was characterized by using Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The removal of these metal ions was analyzed by using inductively coupled plasma-optic emission spectra (ICP-OES) to study the amount of metal uptake by the hydrogel. Parameters of study include effect of pH, amount of sample, contact time, initial concentration of metal solution and reaction temperature. FTIR spectroscopy shows the CMSS hydrogel absorption peaks at 1741cm(-1), 1605cm(-1) and 1430cm(-1) which indicates the substitution of carboxymethyl group of modified sago starch. The degradation temperature of CMSS hydrogel is higher compared to CMSS due to the crosslinking by electron beam radiation and formed a porous hydrogel. From the data obtained, about 93.5%, 88.4% and 85.5% of Pb, Cu and Cd ions has been respectively removed from their solution under optimum condition. PMID:26794735

  14. Fe-based MOFs for efficient adsorption and degradation of acid orange 7 in aqueous solution via persulfate activation

    NASA Astrophysics Data System (ADS)

    Li, Xianghui; Guo, Weilin; Liu, Zhonghua; Wang, Ruiqin; Liu, Hua

    2016-04-01

    Fe-based metal-organic frameworks (MOFs) including MIL-101(Fe), MIL-100(Fe), MIL-53(Fe), and MIL-88B(Fe) prepared via a facile solvothermal process were introduced as both adsorbents and catalysts to generate powerful radicals from persulfate for acid orange 7 (AO7) removal in aqueous solution. Various catalysts were described and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectra. Because of the high specific surface area of the materials, we studied the adsorption isotherms of the four MILs by the fitting of Langmuir adsorption isotherm. Meanwhile, the catalytic activities in persulfate oxidation system were investigated. The results showed that the sequence of the materials ability in the combination of adsorption and degradation was MIL-101(Fe) > MIL-100(Fe) > MIL-53(Fe) > MIL-88B(Fe), which had a close connection with the activity of metal ion in active site of the catalysts and their different cages in size. Moreover, the reactive species in MILs/persulfate system were identified as sulfate radicals and hydroxyl radicals. The reaction mechanism for persulfate activation over MILs was also studied.

  15. Protective Effects of Aqueous Extract of Luehea divaricata against Behavioral and Oxidative Changes Induced by 3-Nitropropionic Acid in Rats

    PubMed Central

    Courtes, Aline Alves; Arantes, Letícia Priscila; Barcelos, Rômulo Pillon; da Silva, Ingrid Kich; Boligon, Aline Augusti; Athayde, Margareth Linde; Puntel, Robson Luiz; Soares, Félix Alexandre Antunes

    2015-01-01

    Huntington's disease (HD) is an autosomal dominant neurodegenerative disease. Accordingly, 3-nitropropionic acid (3-NP) has been found to effectively produce HD-like symptoms. Luehea divaricata (L. divaricata), popularly known in Brazil as “açoita-cavalo,” may act as a neuroprotective agent in vitro and in vivo. We evaluated the hypothesis that the aqueous extract of L. divaricata could prevent behavioral and oxidative alterations induced by 3-NP in rats. 25 adult Wistar male rats were divided into 5 groups: (1) control, (2) L. divaricata (1000 mg/kg), (3) 3-NP, (4) L. divaricata (500 mg/kg) + 3-NP, and (5) L. divaricata (1000 mg/kg) + 3-NP. Groups 2, 4, and 5 received L. divaricata via intragastric gavage daily for 10 days. Animals in groups 3, 4, and 5 received 20 mg/kg 3-NP daily from days 8–10. At day 10, parameters of locomotor activity and biochemical evaluations were performed. Indeed, rats treated with 3-NP showed decreased locomotor activity compared to controls. Additionally, 3-NP increased levels of reactive oxygen species and lipid peroxidation and decreased ratio of GSH/GSSG and acetylcholinesterase activity in cortex and/or striatum. Our results suggest that rats pretreated with L. divaricata prior to 3-NP treatment showed neuroprotective effects when compared to 3-NP treated controls, which may be due to its antioxidant properties. PMID:26604972

  16. In vivo inhibition of gastric acid secretion by the aqueous extract of Scoparia dulcis L. in rodents.

    PubMed

    Mesía-Vela, Sonia; Bielavsky, Monica; Torres, Luce Maria Brandão; Freire, Sonia Maria; Lima-Landman, Maria Teresa R; Souccar, Caden; Lapa, Antonio José

    2007-05-01

    The freeze-dried aqueous extract (AE) from the aerial parts of Scoparia dulcis was tested for its effects on experimental gastric hypersecretion and ulcer in rodents. Administration of AE to animals with 4h pylorus ligature potently reduced the gastric secretion with ED(50)s of 195 mg/kg (rats) and 306 mg/kg (mice). The AE also inhibited the histamine- or bethanechol-stimulated gastric secretion in pylorus-ligated mice with similar potency suggesting inhibition of the proton pump. Bio-guided purification of the AE yielded a flavonoid-rich fraction (BuF), with a specific activity 4-8 times higher than the AE in the pylorus ligature model. BuF also inhibited the hydrolysis of ATP by H(+),K(+)-ATPase with an IC(50) of 500 microg/ml, indicating that the inhibition of gastric acid secretion of Scoparia dulcis is related to the inhibition of the proton pump. Furthermore, the AE inhibited the establishment of acute gastric lesions induced in rats by indomethacin (ED(50)=313 mg/kg, p.o.) and ethanol (ED(50)=490 mg/kg, p.o.). No influence of the AE on gastrointestinal transit allowed discarding a possible CNS or a cholinergic interaction in the inhibition of gastric secretion by the AE. Collectively, the present data pharmacologically validates the popular use of Scoparia dulcis in gastric disturbances. PMID:17300892

  17. Removal of Acid Orange 7 from aqueous solution using magnetic graphene/chitosan: a promising nano-adsorbent.

    PubMed

    Sheshmani, Shabnam; Ashori, Alireza; Hasanzadeh, Saeed

    2014-07-01

    Magnetic graphene/chitosan (MGCh) nanocomposite was fabricated through a facile chemical route and its application as a new adsorbent for Acid Orange 7 (AO7) removal was also investigated. After synthesis, the full characterization with various techniques (FTIR, XRD, VSM, and SEM) was achieved revealing many possible interactions/forces of dye-composite system. The results showed that, benefiting from the surface property of graphene oxide, the abundant amino and hydroxyl functional groups of chitosan, and from the magnetic property of Fe3O4, the adsorbent possesses quite a good and versatile adsorption capacity to the dye under investigation, and can be easily and rapidly extracted from water by magnetic attraction. The maximum absorption capacity was reached at initial pH 3 and 120min contact time. The batch adsorption experiments showed that the adsorption of the AO7 is considerably dependent on pH of milieu, amount of adsorbent, and contact time. The adsorption kinetics and isotherms were investigated to indicate that the kinetic and equilibrium adsorption were well-described by pseudo-first order kinetic and Langmuir isotherm model, respectively. The adsorption behavior suggested that the adsorbent surface was homogeneous in nature. The study suggests that the MGCh is a promising nano adsorbent for removal of anionic azo dyes from aqueous solution. PMID:24813679

  18. Degradation of Acid Orange 7 in aqueous solution by dioxygen activation in a pyrite/H₂O/O₂ system.

    PubMed

    Hao, Feifei; Guo, Weilin; Lin, Xin; Leng, Yanqiu; Wang, Anqi; Yue, Xinxin; Yan, Liangguo

    2014-05-01

    Increasing attention has been paid to pyrite due to its ability to generate hydroxyl radicals in air-saturated solutions. In this study, the mineral pyrite was studied as a catalyst to activate molecular oxygen to degrade Acid Orange 7 (AO7) in aqueous solution. A complete set of control experiments were conducted to optimize the reaction conditions, including the dosage of pyrite, the AO7 concentration, as well as the initial pH value. The role of reactive oxygen species (ROS) generated by pyrite in the process was elucidated by free radical quenching reactions. Furthermore, the concentrations of Fe(II) and total Fe formed were also measured. The mechanism for the production of ROS in the pyrite/H2O/O2 system was that H2O2 was formed by hydrogen ion and superoxide anion (O2(·-)) which was produced by the reaction of pyrite activating O2 and then reacted with Fe(II) dissolved from pyrite to produce (·)OH through Fenton reaction. The findings suggest that pyrite/H2O/O2 system is potentially practical in pollution treatment. Moreover, the results provide a new insight into the understanding of the mechanism for degradation of organic pollutants by pyrite. PMID:24510532

  19. Inhibition of gastric acid secretion by a standardized aqueous extract of Cecropia glaziovii Sneth and underlying mechanism.

    PubMed

    Souccar, C; Cysneiros, R M; Tanae, M M; Torres, L M B; Lima-Landman, M T R; Lapa, A J

    2008-06-01

    Cecropia glazioui Sneth (Cecropiaceae) is used in folk medicine in tropical and subtropical Latin America as cardiotonic, diuretic, hypotensive, anti-inflammatory and anti-asthmatic. The hypotensive/antihypertensive activity of the plant aqueous extract (AE) and isolated butanolic fraction (BuF) has been confirmed and putatively related to calcium channels blockade in vascular smooth musculature [Lapa, A.J., Lima-Landman, M.T.R., Cysneiros, R.M, Borges, A.C.R., Souccar, C., Barreta, I.P., Lima, T.C.M., 1999. The Brazilian folk medicine program to validate medicinal plants - a topic in new antihypertensive drug research. In: Hostettman, K., Gupta, M.P., Marston, A. (Eds.), Proceedings Volume, IOCD/CYTED Symposium, Panamá City, Panamá, 23-26 February 1997. Chemistry, Biological and Pharmacological Properties of Medicinal Plants from the Americas. Harwood Academic Publishers, Amsterdam, pp. 185-196; Lima-Landman, M.T., Borges, A.C., Cysneiros, R.M., De Lima, T.C., Souccar, C., Lapa, A.J., 2007. Antihypertensive effect of a standardized aqueous extract of Cecropia glaziovii Sneth in rats: an in vivo approach to the hypotensive mechanism. Phytomedicine 14, 314-320]. Bronchodilation and antidepressant-like activities of both AE and BuF have been also shown [Delarcina, S., Lima-Landman, M.T., Souccar, C., Cysneiros, R.M., Tanae, M.M., Lapa, A.J., 2007. Inhibition of histamine-induced bronchospasm in guinea pigs treated with Cecropia glaziovi Sneth and correlation with the in vitro activity in tracheal muscles. Phytomedicine 14, 328-332; Rocha, F.F., Lima-Landman, M.T., Souccar, C., Tanae, M.M., De Lima, T.C., Lapa, A.J., 2007. Antidepressant-like effect of Cecropia glazioui Sneth and its constituents -in vivo and in vitro characterization of the underlying mechanism. Phytomedicine 14, 396-402]. This study reports the antiulcer and antisecretory gastric acid activities of the plant AE, its BuF and isolated compounds with the possible mechanism involved. Both AE and Bu

  20. Rare Earth Element - Humic Acid Interaction: Experimental Evidence for Kinetic and Equilibrium Fractionation in Aqueous Systems.

    NASA Astrophysics Data System (ADS)

    Sonke, J. E.; Salters, V. J.; Benedetti, M. F.

    2003-12-01

    Dissolved organic matter (DOM) is well known for it's strong binding capacity for trace metals. In order to better predict the role of DOM in the speciation and transport of trace metals in the environment we coupled capillary electrophoresis (CE), a molecular separation technique, to a Sector Field Inductively Coupled Plasma Mass Spectrometer (SF-ICP-MS). The combination of these two techniques allows for the study of non-labile metal speciation in aquatic samples. By separating Rare Earth Element (REE) complexes with EDTA and Humic Acid's (i.e. ligand competition) we have been able to determine conditional equilibrium binding constants (Kc) and kinetic rate constants for all 14 REE's with Humic (HA) and Fulvic Acids (FA) as a function of pH (6-9) and ionic strength (IS, 0.01-0.1 mol/L). Assuming a 1:1 binding mechanism, logKc values for REE-FA varied from 9.0 (La) to 10.5 (Lu) at pH 6, 0.1 mol/L IS, and 11.7 (La) to 14.6 (Lu) at pH 9, 0.1 mol/L IS. LogKc values for REE-HA were 10.6 (La) to 12.2 (Lu) at pH 6, 0.1 mol/L IS and 13.2 (La) to 16.5 (Lu) at pH 9, 0.1 mol/L IS. Slightly higher values for Kc were obtained at 0.01 mol/L IS. The general observations of stronger REE-HA binding compared to REE-FA, and stronger binding with increasing pH and decreasing IS correlate with our current understanding of metal-DOM interactions (1). Both Kc's as well as kinetic rate constants increase with increasing REE mass number (decreasing ionic radius); a reflection of the well-known lanthanide contraction. This is the first comprehensive metal binding dataset between REE and DOM, and the first experimental evidence for differential equilibrium and kinetic binding behavior between REE's and DOM. The 30-1000 fold increase in binding strength of heavy REE's with DOM provides for a an equilibrium fractionation mechanism that may explain features of the global geochemical REE cycle such as fractionation related to weathering, estuarine mixing, and REE scavenging in the deep ocean

  1. Transformation of Flame Retardant Tetrabromobisphenol A by Aqueous Chlorine and the Effect of Humic Acid.

    PubMed

    Gao, Yuan; Pang, Su-Yan; Jiang, Jin; Ma, Jun; Zhou, Yang; Li, Juan; Wang, Li-Hong; Lu, Xue-Ting; Yuan, Li-Peng

    2016-09-01

    In this work, it was found that the most widely used brominated flame retardant tetrabromobisphenol A (TBrBPA) could be transformed by free chlorine over a wide pH range from 5 to 10 with apparent second-order rate constants from 138 to 3210 M(-1)·s(-1). A total of eight products, including one quinone-like compound (i.e., 2,6-dibromoquinone), two dimers, and several simple halogenated phenols (e.g., 4-(2-hydroxyisopropyl)-2,6-dibromophenol, 2,6-dibromohydroquinone, and 2,4,6-tribromophenol), were detected by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) using a novel precursor ion scan (PIS) approach. A tentative reaction pathway was proposed: chlorine initially oxidized TBrBPA leading to the formation of a phenoxy radical, and then this primary radical and its secondary intermediates (e.g., 2,6-dibromo-4-isopropylphenol carbocation) formed via beta-scission subsequently underwent substitution, dimerization, and oxidation reactions. Humic acid (HA) considerably inhibited the degradation rates of TBrBPA by chlorine even accounting for oxidant consumption. A similar inhibitory effect of HA was also observed in permanganate and ferrate oxidation. This inhibitory effect was possibly attributed to the fact that HA competitively reacted with the phenoxy radical of TBrBPA and reversed it back to parent TBrBPA. This study confirms that chlorine can transform phenolic compounds (e.g., TBrBPA) via electron transfer rather than the well-documented electrophilic substitution, which also have implications on the formation pathway of halo-benzoquinones during chlorine disinfection. These findings can improve the understanding of chlorine chemistry in water and wastewater treatment. PMID:27487036

  2. Effect of initiator on photopolymerization of acidic, aqueous dental model adhesives

    PubMed Central

    Guo, Xinglin; Peng, Zhonghua; Spencer, Paulette; Wang, Yong

    2013-01-01

    This study evaluated different initiator systems in self-etching model adhesives, in which camphorquinone (CQ) or [3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-2-hydroxylpropy] trimethylammonium chloride (QTX) was employed as a photoinitiator (dye). N-phenylglycine (NPG), ethyl 4-dimethylaminobenzoate (4E) or 2-(dimethylamino) ethyl methacrylate (DMAEMA) was used as the coinitiator (CI). The role of diphenyliodonium hexafluorophosphate (DPIHP) in the polymerization process was also studied. The concentrations of dye, CI, and DPIHP in model adhesives were all maintained at 0.022 mmol per gram monomer. The model adhesive contained two monomers: (bis[2-(methacryloyloxy)ethyl] phosphate) (2MP) and 2-hydroxyethyl methacrylate (HEMA) whose mass ratio was 1:1, thus representing an acidic and hydrophilic formulation. The polymerization rate and the degree of conversion (DC) of the model adhesives with 5, 15, or 25% water content were determined using FTIR/ATR with a time-based spectrum analysis. The results indicated that with CQ as the photoinitiator, 4E appeared to be the most efficient CI, whereas the CQ-DMAEMA combination led to very low radical generation efficiency (DC < 5%). DPIHP exhibited little effect on the polymerization process. With QTX as the photoinitiator, however, DPIHP played an essential role. Without DPIHP, all three QTX-CI systems failed to initiate polymerization (DC < 5%). The QTX-DPIHP combination, on the other hand, was found to be a viable initiator system. The above results provide the critical information for the development of self-etching adhesive systems. PMID:18671261

  3. Removal of humic acid from aqueous solution by magnetically separable polyaniline: adsorption behavior and mechanism.

    PubMed

    Wang, Jiahong; Bi, Lijuan; Ji, Yanfen; Ma, Hongrui; Yin, Xiaolong

    2014-09-15

    Magnetically separable polyaniline (Fe3O4@SiO2-PANI) was prepared by in situ chemical polymerization of aniline on the surface of silica-coated Fe3O4 nanoparticles, and characterized by FTIR spectroscopy, powder X-ray diffraction, elemental analysis, transmission electron microscopy, vibrating sample magnetometry and X-ray photoelectron spectroscopy. Characterization results showed that Fe3O4@SiO2-PANI with amino groups of 1.78 mmol/g and the average diameter of 21.6 nm are superparamagnetic. Adsorption behavior of Fe3O4@SiO2-PANI nanoparticles for humic acid (HA) was investigated by batch experiments and adsorption kinetic tests. HA adsorption amount on the adsorbent decreased with increasing solution pH and the presence of Ca(2+) resulted in the enhanced HA adsorption. HA adsorption on Fe3O4@SiO2-PANI could be well described by Langmuir model and the maximum adsorption amount of the adsorbent for HA at 25°C was 36.36 mg/g. HA adsorption process on the adsorbent obey pseudo-second-order kinetics and the adsorption rates decrease with increasing initial HA concentration. The XPS analysis verified that HA adsorption over the adsorbent could be attributed to the surface complexation between the disassociated HA molecules and the protonated nitrogen of polyaniline on the adsorbent. HA loaded adsorbent could be magnetically separated and easily desorbed in 0.01 mol/L NaOH solution. Regeneration tests indicated that Fe3O4@SiO2-PANI could be used repeatedly. PMID:24998066

  4. MTBE Hydrolysis in Dilute Aqueous Solution Using Heterogeneous Strong Acid Catalysts

    NASA Astrophysics Data System (ADS)

    Rixey, W. G.

    2003-12-01

    The objective of this research has been the development of a potential in situ catalytic process for the hydrolysis of methyl tertiary butyl ether (MTBE) to tertiary butyl alcohol (TBA) and methanol in ground water. Bench-scale batch reactor studies were conducted over a temperature range of 23 deg C to 50 deg C with several heterogeneous strong acid catalysts to obtain rates of hydrolysis of MTBE to TBA and methanol at dilute concentrations in water. Continuous flow experiments were then conducted to obtain kinetic data over a temperature range of 15 deg C to 50 deg C for various flow rates for the most active catalysts. It was found that the batch and continuous flow experiments yielded similar intrinsic kinetic rate constants when sorption of MTBE to the catalyst was accounted for. Additional fixed-bed experiments were conducted with deionized water and 0.005 M CaCl2 feed solutions containing 100 mg/L MTBE, respectively, to assess the deactivation of the catalyst, and deactivation was found to be controlled by ion exchange of H+ in the catalyst with Ca+2 in the feed. Our results indicate that, for low to moderate groundwater velocities and cation concentrations at ambient temperatures, an in situ reactive barrier process using the most active catalysts studied in this research could be a viable process in terms of both suitable conversion of MTBE and catalyst life. Although application to in situ remediation is emphasized, the results of this research are also applicable to ex-situ groundwater treatment.

  5. Utilization of cation exchange resins for the isolation and separation of transplutonium elements from others in aqueous and non aqueous-alcohol solutions of hydrochloric and nitric acids

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.

    1985-07-01

    The authors study the sorption of several transplutonium and fission elements on cation exchange resins in relation to the acid concentration and content of alcohol in solution. They observe a significant increase in sorption of the TPE on the cation exchanges from nitric acid solutions containing more than 50% of alcohol. On the basis of the experimental results they determine the optimum conditions for the concentration of TPE on cation exchangers with their subsequent separation from certain fission and other elements by means of hydrochloric acid and nitric acid solutions.

  6. Elucidation of adsorption processes at the surface of Pt(331) model electrocatalysts in acidic aqueous media.

    PubMed

    Pohl, Marcus D; Colic, Viktor; Scieszka, Daniel; Bandarenka, Aliaksandr S

    2016-04-20

    The Pt(331) surface has long been known to be the most active pure metal electrocatalyst for the oxygen reduction reaction (ORR) in acidic media. Its activity is often higher than those known for the Pt-based alloys towards ORR, being comparable with the most active Pt3Ni(111), Pt3Y or Pt5Gd, and being more active than e.g. polycrystalline Pt3Ni. Multiple active sites at this surface offer adsorption energies which are close to the optimal binding energy with respect to the main ORR intermediates; nevertheless, the exact location of these sites is still not clear. Taking into account the unique surface geometry of Pt(331), some adsorbates (including some oxygenated ORR-intermediates) should also contribute to the electronic structure of the neighbouring catalytic centres. However, the experimental elucidation of the specific adsorption of oxygenated species at this surface appears to be a non-trivial task. Such information holds the keys to the understanding of the high activity of this material and would enable the rational design of nanostructured ORR catalysts even without alloying. In this work, the electrified Pt(331)/electrolyte interface has been characterised using cyclic voltammetry (CV) combined with potentiodynamic electrochemical impedance spectroscopy (PDEIS) in 0.1 M HClO4 solutions. The systems were studied in the potential region between 0.05 V and 1.0 V vs. RHE, where the adsorption of *H, *OH and *O species is possible in both O2-free and O2-saturated electrolytes. Our CV and PDEIS results support the hypothesis that in contrast to Pt(111), many Pt(331) surface sites are likely blocked by *O species at the polymer electrolyte membrane fuel cell benchmark potential of 0.9 V (RHE). We propose a model illustrated by simplified adsorbate structures at different electrode potentials, which is, however, able to explain the voltammetric and impedance data, and which is in good agreement with previously reported electrocatalytic measurements. PMID

  7. Sorption of estrogens and pesticides from aqueous solution by a humic acid and raw and processed plant materials

    NASA Astrophysics Data System (ADS)

    Loffredo, Elisabetta; Taskin, Eren

    2016-04-01

    The huge number of organic contaminants released in water as a consequence of anthropogenic activities have detrimental effects to environmental systems and human health. Industrial products and byproducts, pharmaceuticals, pesticides, detergents and so on impose increasing costs for wastewater decontamination. Adsorption techniques can be successfully used for the treatment of wastewaters to remove contaminants of various nature. Humic acids (HA) have well-known adsorptive capacities towards hydrophilic and, especially, hydrophobic compounds. In the recent years, alternative low-cost adsorbents, especially originated from agricultural wastes and food industries residues, such as wood chips, almond and coconut shells, peanut and rice husks, are under investigation. Biochar is also considered a promising and relatively low-cost adsorbent, even if there are still knowledge gaps about the influence of feedstock type, pyrolysis conditions, physical and chemical properties on its potential and safe use. In the present work, a HA from a green compost was used along with three other materials of plant origin to remove two estrogens, 4-tert-octylphenol and 17-β-estradiol, and two pesticides, carbaryl and fenuron, from an aqueous solution. The four molecules were spiked in water each at a concentration of 1 mg L-1. The materials were: a biochar obtained from 100% red spruce pellet pyrolysed at 550 °C, spent coffee grounds and spent tea leaves. Kinetics curves and adsorption isotherms studies were performed using a batch equilibrium method. Adsorption data obtained for each compound were fitted to a linear equation and non-linear Freundlich and Langmuir models. Kinetics data of the four compounds onto all adsorbents showed an initial very rapid adsorption which was completed in few hours when it reached equilibrium. The two estrogens were adsorbed onto all materials more quickly than the two less hydrophobic pesticides. Significant differences among adsorbents and the

  8. 1. LOOKING NORTH, SHOWING IODINE SPRING (FOREGROUND), SALT SULPHUR SPRING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. LOOKING NORTH, SHOWING IODINE SPRING (FOREGROUND), SALT SULPHUR SPRING (LEFT BACKGROUND), AND TWIN COTTAGES (UPPER RIGHT) (4 x 5 negative; 5 x 7 print) - Salt Sulpher Springs, U.S. Route 219, Salt Sulphur Springs, Monroe County, WV

  9. 30 CFR 250.1603 - Determination of sulphur deposit.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Sulphur... paragraph (a) of this section shall be based upon the following: (1) Core analyses that indicate...

  10. 30 CFR 250.1603 - Determination of sulphur deposit.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Sulphur Operations... this section shall be based upon the following: (1) Core analyses that indicate the presence of...

  11. 30 CFR 250.1603 - Determination of sulphur deposit.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Sulphur Operations... this section shall be based upon the following: (1) Core analyses that indicate the presence of...

  12. 30 CFR 250.1603 - Determination of sulphur deposit.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Sulphur Operations... this section shall be based upon the following: (1) Core analyses that indicate the presence of...

  13. Amine Chemistry at Aqueous Interfaces: The Study of Organic Amines in Neutralizing Acidic Gases at an Air/Water Surface Using Vibrational Sum Frequency Spectroscopy

    NASA Astrophysics Data System (ADS)

    McWilliams, L.; Wren, S. N.; Valley, N. A.; Richmond, G.

    2014-12-01

    Small organic bases have been measured in atmospheric samples, with their sources ranging from industrial processing to animal husbandry. These small organic amines are often highly soluble, being found in atmospheric condensed phases such as fogwater and rainwater. Additionally, they display acid-neutralization ability often greater than ammonia, yet little is known regarding their kinetic and thermodynamic properties. This presentation will describe the molecular level details of a model amine system at the vapor/liquid interface in the presence of acidic gas. We find that this amine system shows very unique properties in terms of its bonding, structure, and orientation at aqueous surfaces. The results of our studies using a combination of computation, vibrational sum frequency spectroscopy, and surface tension will report the properties inherent to these atmospherically relevant species at aqueous surfaces.

  14. SULPHUR DIOXIDE LEACHING OF URANIUM CONTAINING MATERIAL

    DOEpatents

    Thunaes, A.; Rabbits, F.T.; Hester, K.D.; Smith, H.W.

    1958-12-01

    A process is described for extracting uranlum from uranium containing material, such as a low grade pitchblende ore, or mill taillngs, where at least part of the uraniunn is in the +4 oxidation state. After comminuting and magnetically removing any entrained lron particles the general material is made up as an aqueous slurry containing added ferric and manganese salts and treated with sulfur dioxide and aeration to an extent sufficient to form a proportion of oxysulfur acids to give a pH of about 1 to 2 but insufficient to cause excessive removal of the sulfur dioxide gas. After separating from the solids, the leach solution is adjusted to a pH of about 1.25, then treated with metallic iron in the presence of a precipitant such as a soluble phosphate, arsonate, or fluoride.

  15. CHEMICAL TRANSFORMATIONS IN ACID RAIN. VOLUME 2. INVESTIGATION OF KINETICS AND MECHANISM OF AQUEOUS-PHASE PEROXIDE FORMATION

    EPA Science Inventory

    The aqueous-phase reactions of O3 with a number of species have been studied in an effort to identify pathways leading to the production of hydrogen peroxide in solution. The aqueous-phase systems studied included the decomposition of O3 in pure water and the interaction of O3 wi...

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

    PubMed

    Kribéche, 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), α-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

  17. The Negative Effects of Volatile Sulphur Compounds.

    PubMed

    Milella, Lisa

    2015-01-01

    Oral malodor has been studied extensively in humans but not necessarily to the same degree in our veterinary patients where malodor constitutes a significant problem. Breath malodor may originate from the mouth, or from an extra oral source, originating from other organ systems such as gastrointestinal, respiratory, or even systemic disease. Oral malodor is a result of microbial metabolism of exogenous and endogenous proteinaceous substrates leading to the production of compounds such as indole, skatole, tyramine, cadaverine, puterescine, mercaptans, and sulphides. Volatile sulphur compounds have been shown to be the main cause of oral malodor. Although most clients perceive oral malodor to be primarily a cosmetic problem, there is an increasing volume of evidence in human dental literature demonstrating that volatile sulphur compounds produced by bacteria, even at low concentrations, are toxic to tissues and play a role in the pathogenesis of periodontitis. This article reviews the current available literature in human dentistry looking at these negative effects. No veterinary studies have been conducted looking at the negative effects of volatile sulphur compounds specifically, but as this article highlights, we should be aware of the potential negative effects of volatile sulphur compounds and consider this an area of future research. PMID:26415386

  18. Conversion of carbohydrate biomass to γ-valerolactone by using water-soluble and reusable iridium complexes in acidic aqueous media.

    PubMed

    Deng, Jin; Wang, Yan; Pan, Tao; Xu, Qing; Guo, Qing-Xiang; Fu, Yao

    2013-07-01

    Mild-mannered manipulation: A catalytic method for the conversion of carbohydrate biomass to γ-valerolactone in acidic aqueous media has been developed. The water-soluble iridium complexes were observed to be extremely catalytically active for providing γ-valerolactone in high yields with high TONs. The homogeneous catalysts can also be recycled and reused by applying a simple phase separation process. PMID:23757330

  19. Facile, room-temperature pre-treatment of rice husks with tetrabutylphosphonium hydroxide: Enhanced enzymatic and acid hydrolysis yields.

    PubMed

    Lau, B B Y; Luis, E T; Hossain, M M; Hart, W E S; Cencia-Lay, B; Black, J J; To, T Q; Aldous, L

    2015-12-01

    Aqueous solutions of tetrabutylphosphonium hydroxide have been evaluated as pretreatment media for rice husks, prior to sulphuric acid hydrolysis or cellulase enzymatic hydrolysis. Varying the water:tetrabutylphosphonium hydroxide ratio varied the rate of delignification, as well as silica, lignin and cellulose solubility. Pre-treatment with 60wt% hydroxide dissolved the rice husk and the regenerated material was thus heavily disrupted. Sulphuric acid hydrolysis of 60wt%-treated samples yielded the highest amount of glucose per gram of rice husk. Solutions with good lignin and silica solubility but only moderate to negligible cellulose solubility (10-40wt% hydroxide) were equally effective as pre-treatment media for both acid and enzymatic hydrolysis. However, pre-treatment with 60wt% hydroxide solutions was incompatible with downstream enzymatic hydrolysis. This was due to significant incorporation of phosphonium species in the regenerated biomass, which significantly inhibited the activity of the cellulase enzymes. PMID:26342336

  20. Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: a kinetic approach.

    PubMed

    Ghosh, Aniruddha; Saha, Rumpa; Ghosh, Sumanta K; Mukherjee, Kakali; Saha, Bidyut

    2013-05-15

    The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation. PMID:23501718

  1. Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: A kinetic approach

    NASA Astrophysics Data System (ADS)

    Ghosh, Aniruddha; Saha, Rumpa; Ghosh, Sumanta K.; Mukherjee, Kakali; Saha, Bidyut

    2013-05-01

    The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.

  2. Removal of Mefenamic acid from aqueous solutions by oxidative process: Optimization through experimental design and HPLC/UV analysis.

    PubMed

    Colombo, Renata; Ferreira, Tanare C R; Ferreira, Renato A; Lanza, Marcos R V

    2016-02-01

    Mefenamic acid (MEF) is a non-steroidal anti-inflammatory drug indicated for relief of mild to moderate pain, and for the treatment of primary dysmenorrhea. The presence of MEF in raw and sewage waters has been detected worldwide at concentrations exceeding the predicted no-effect concentration. In this study, using experimental designs, different oxidative processes (H2O2, H2O2/UV, fenton and Photo-fenton) were simultaneously evaluated for MEF degradation efficiency. The influence and interaction effects of the most important variables in the oxidative process (concentration and addition mode of hydrogen peroxide, concentration and type of catalyst, pH, reaction period and presence/absence of light) were investigated. The parameters were determined based on the maximum efficiency to save time and minimize the consumption of reagents. According to the results, the photo-Fenton process is the best procedure to remove the drug from water. A reaction mixture containing 1.005 mmol L(-1) of ferrioxalate and 17.5 mmol L(-1) of hydrogen peroxide, added at the initial reaction period, pH of 6.1 and 60 min of degradation indicated the most efficient degradation, promoting 95% of MEF removal. The development and validation of a rapid and efficient qualitative and quantitative HPLC/UV methodology for detecting this pollutant in aqueous solution is also reported. The method can be applied in water quality control that is generated and/or treated in municipal or industrial wastewater treatment plants. PMID:26686073

  3. Selective removal of Cr(VI) from aqueous solution by polypyrrole/2,5-diaminobenzene sulfonic acid composite.

    PubMed

    Kera, Nazia H; Bhaumik, Madhumita; Ballav, Niladri; Pillay, Kriveshini; Ray, Suprakas Sinha; Maity, Arjun

    2016-08-15

    A polypyrrole/2,5-diaminobenzenesulfonic acid (PPy/DABSA) composite, synthesised by the in situ oxidative polymerization of pyrrole in the presence of DABSA, was studied as an adsorbent for the removal of Cr(VI) from aqueous solution. The structure and morphology of the composite were investigated by ATR-FTIR, FE-SEM, EDX, TGA, XRD and XPS studies. The adsorption of Cr(VI) by PPy/DABSA composite was highly pH dependent and optimum removal was achieved at pH 2. Adsorption of Cr(VI) was confirmed by EDX and XPS studies. The isotherm data fitted the linear Langmuir model well, with a maximum adsorption capacity of 303mg/g at 25°C. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) were calculated using isotherm data and confirmed that the adsorption process was spontaneous and endothermic. Adsorption kinetics was best described by the pseudo-second-order model. The activation energy of the adsorption process suggested that Cr(VI) was chemisorbed by PPy/DABSA composite. PPy/DABSA composite could be used for three consecutive adsorption-desorption cycles without loss of its original adsorption capacity. Highly selective removal of Cr(VI) was observed even when co-existing ions such as Cu(2+), Zn(2+), Ni(2+), Cl(-), SO4(2)(-) and NO3(-) were present in the solution. In summary, the potential of PPy/DABSA composite for remediating industrial wastewater contaminated by Cr(VI) has been demonstrated. PMID:27209399

  4. Experimental studies of selective acid gas removal: Absorption of hydrogen sulfide and carbon dioxide into aqueous methyldiethanolamine using packed columns

    SciTech Connect

    Schubert, C.N.

    1988-01-01

    The use of aqueous methyldiethanolamine (MDEA) for selective removal of hydrogen sulfide from acid gas streams has been studied in a 2 inch column packed with 1/4 inch ceramic Intalox saddles. The column was operated in a counter-current, steady state fashion. The feed gas composition varied between 1 and 5 mole % hydrogen sulfide and between 0 and 50 mole % carbon dioxide. In order to assist the development of packed column absorption models, the rate at which pure carbon dioxide absorbs into 2 M MDEA was measured as a function of pressure, liquid flow rate and packed bed length. The importance of end effects was carefully evaluated. In addition, draining and tracer methods were used to estimate the amount of static holdup present in the column. Using classical draining methods, as much as 50 % of the total holdup was found to be static. However, according to the step decrease in tracer method, less than 5 % of the total holdup was static. Since the step decrease in tracer method measures the amount of static holdup present in the bed under irrigated conditions, it seems likely that the draining method provides an unrealistic estimate of static holdup. Thus, although the notion of static holdup may be useful as a means of correlating mass transfer coefficients, the data indicate that very little static holdup exists in the column under irrigated conditions. Hence, in the absence of a mechanistically sound model, the choice of whether to use static holdup or dispersion as a means of accounting for deviations from plug flow in the liquid phase should be made on the basis of computational convenience.

  5. Hydrolysis of Np(IV) and Pu(IV) and Their Complexation by Aqueous Orthosilicic Acid Si(OH)4

    SciTech Connect

    Yusov, A B.; Fedoseev, A M.; Delegard, Calvin H.

    2004-12-10

    The hydrolysis and interaction of Np(IV) and Pu(IV) with orthosilicic acid, Si(OH)4, were studied in 0.1-1.0 M ionic strength aqueous solutions. Spectrophotometry was used to study these reactions at about 10-4 M Np(IV) and Pu(IV) concentrations. The first hydrolysis constants, Khydr, agree with the majority of earlier spectrophotometric and potentiometric data. The absorption spectra of NpOH3+ and PuOH3+ were obtained by spectral deconvolution. Reasons to explain the overestimation of Khydr obtained by other methods [by extraction of trace amounts of Np(IV) and Pu(IV) and by solubility] are discussed. Formation of the complexes NpOSi(OH)33+ and PuOSi(OH)33+ is demonstrated in the p[H+] range 1.4-2.1 and 0.7-1.4, respectively. Measured values of equilibrium constants of the reaction M4+ + Si(OH)4 ? MOSi(OH)33+ + H+ at ionic strength I=1.0 are log ?1 = 0.41?0.02 and 1.04?0.04, respectively, for Np(IV) and Pu(IV). The stability constants of the NpOSi(OH)33+ and PuOSi(OH)33+ complexes, recalculated to zero ionic strength, are log ?10 = 11.2 and 11.8, respectively. The correlation between Khydr and ?1, as observed for all earlier studied metal ions, also occurs for both Np(IV) and Pu(IV).

  6. Efficient degradation of Acid Orange 7 in aqueous solution by iron ore tailing Fenton-like process.

    PubMed

    Zheng, Jianming; Gao, Zhanqi; He, Huan; Yang, Shaogui; Sun, Cheng

    2016-05-01

    An effective method based on iron ore tailing Fenton-like process was studied for removing an azo dye, Acid Orange 7 (AO7) in aqueous solution. Five tailings were characterized by X-ray fluorescence spectroscope (XFS), Brunner-Emmet-Teller (BET) measurement, and Scanning Electron Microscope (SEM). The result of XFS showed that Fe, Si and Ca were the most abundant elements and some toxic heavy metals were also present in the studied tailings. The result of BET analysis indicated that the studied tailings had very low surface areas (0.64-5.68 m(2) g(-1)). The degradation efficiencies of AO7 were positively correlated with the content of iron oxide and cupric oxide, and not related with the BET surface area of the tailings. The co-existing metal elements, particularly Cu, might accelerate the heterogeneous Fenton-like reaction. The effects of other parameters on heterogeneous Fenton-like degradation of AO7 by a converter slag iron tailing (tailing E) which contains highest iron oxide were also investigated. The tailing could be reused 10 times without significant decrease of the catalytic capacity. Very low amount of iron species and almost undetectable toxic elements were leached in the catalytic degradation of AO7 by the tailing E. The reaction products were identified by gas chromatography-mass spectrometry and a possible pathway of AO7 degradation was proposed. This study not only provides an effective method for removing azo dyes in polluted water by employing waste tailings as Fenton-like catalysts, but also uses waste tailings as the secondary resource. PMID:26891355

  7. Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

    NASA Astrophysics Data System (ADS)

    Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

    2016-09-01

    There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe3+/Fe2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles' formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH.

  8. Vanillic and syringic acids from biomass burning: Behaviour during Fenton-like oxidation in atmospheric aqueous phase and in the absence of light.

    PubMed

    Santos, Gabriela T A D; Santos, Patrícia S M; Duarte, Armando C

    2016-08-01

    Biomass combustion is a threat to the environment since it emits to the atmosphere organic compounds, which may react and originate others more aggressive. This work studied the behaviours of vanillic and syringic acids, small aromatic tracers of biomass burning, during Fenton-like oxidation in aqueous phase and absence of light. For both compounds, the extent of oxidation increased with pH decrease from neutral to acid in atmospheric waters, but for vanillic acid the neutral pH was not able of promoting the oxidation. With the oxidation of both acids were formed chromophoric compounds, and the formation rate increased with the degree of electron-donator substituents in benzene ring. The initial and produced compounds were not totally degraded up to 24h of reaction at pH 4.5, suggesting that the night period may be not sufficient for their full degradation in atmospheric waters. The major compounds formed were the 3,4-dihydroxybenzoic acid for vanillic acid, and the 1,4-dihydroxy-2,6-dimethoxybenzene for syringic acid. These findings suggest the occurrence of an ipso attack by the hydroxyl radical preferential to the methoxy and carboxyl groups of vanillic and syringic acids, respectively. It is important to highlight that for both aromatic acids the main compounds produced are also small aromatic compounds. PMID:27085101

  9. A new atmospherically relevant oxidant of sulphur dioxide.

    PubMed

    Mauldin, R L; Berndt, T; Sipilä, M; Paasonen, P; Petäjä, T; Kim, S; Kurtén, T; Stratmann, F; Kerminen, V-M; Kulmala, M

    2012-08-01

    Atmospheric oxidation is a key phenomenon that connects atmospheric chemistry with globally challenging environmental issues, such as climate change, stratospheric ozone loss, acidification of soils and water, and health effects of air quality. Ozone, the hydroxyl radical and the nitrate radical are generally considered to be the dominant oxidants that initiate the removal of trace gases, including pollutants, from the atmosphere. Here we present atmospheric observations from a boreal forest region in Finland, supported by laboratory experiments and theoretical considerations, that allow us to identify another compound, probably a stabilized Criegee intermediate (a carbonyl oxide with two free-radical sites) or its derivative, which has a significant capacity to oxidize sulphur dioxide and potentially other trace gases. This compound probably enhances the reactivity of the atmosphere, particularly with regard to the production of sulphuric acid, and consequently atmospheric aerosol formation. Our findings suggest that this new atmospherically relevant oxidation route is important relative to oxidation by the hydroxyl radical, at least at moderate concentrations of that radical. We also find that the oxidation chemistry of this compound seems to be tightly linked to the presence of alkenes of biogenic origin. PMID:22874964

  10. Structure and oxidation state of hematite surfaces reacted with aqueous Fe(II) at acidic and neutral pH

    NASA Astrophysics Data System (ADS)

    Catalano, Jeffrey G.; Fenter, Paul; Park, Changyong; Zhang, Zhan; Rosso, Kevin M.

    2010-03-01

    Structural changes and surface oxidation state were examined following the reaction of hematite (0 0 1), (0 1 2), and (1 1 0) with aqueous Fe(II). X-ray reflectivity measurements indicated that Fe(II) induces changes in the structure of all three surfaces under both acidic (pH 3) and neutral (pH 7) conditions. The structural changes were generally independent of pH although the extent of surface transformation varied slightly between acidic and neutral conditions; no systematic trends with pH were observed. Induced changes on the (1 1 0) and (0 1 2) surfaces include the addition or removal of partial surface layers consistent with either growth or dissolution. In contrast, a <1 nm thick, discontinuous film formed on the (0 0 1) surface that appears to be epitaxial yet is not a perfect extension of the underlying hematite lattice, being either structurally defective, compositionally distinct, or nanoscale in size and highly relaxed. Resonant anomalous X-ray reflectivity measurements determined that the surface concentration of Fe(II) present after reaction at pH 7 was below the detection limit of approximately 0.5-1 μmol/m 2 on all surfaces. These observations are consistent with Fe(II) oxidative adsorption, whereby adsorbed Fe(II) is oxidized by structural Fe(III) in the hematite lattice, with the extent of this reaction controlled by surface structure at the atomic scale. The observed surface transformations at pH 3 show that Fe(II) oxidatively adsorbs on hematite surfaces at pH values where little net adsorption occurs, based on historical macroscopic Fe(II) adsorption behavior on fine-grained hematite powders. This suggests that Fe(II) plays a catalytic role, in which an electron from an adsorbed Fe(II) migrates to and reduces a lattice Fe(III) cation elsewhere, which subsequently desorbs in a scenario with zero net reduction and zero net adsorption. Given the general pH-independence and substantial mass transfer involved, this electron and atom exchange

  11. Selective environmental stress from sulphur emitted by continental flood basalt eruptions

    NASA Astrophysics Data System (ADS)

    Schmidt, Anja; Skeffington, Richard; Thordarson, Thorvaldur; Self, Stephen; Forster, Piers; Rap, Alexandru; Ridgwell, Andy; Fowler, David; Wilson, Marjorie; Mann, Graham; Wignall, Paul; Carslaw, Ken

    2016-04-01

    Several biotic crises during the past 300 million years have been linked to episodes of continental flood basalt volcanism, and in particular to the release of massive quantities of magmatic sulphur gas species. Flood basalt provinces were typically formed by numerous individual eruptions, each lasting years to decades. However, the environmental impact of these eruptions may have been limited by the occurrence of quiescent periods that lasted hundreds to thousands of years. Here we use a global aerosol model to quantify the sulphur-induced environmental effects of individual, decade-long flood basalt eruptions representative of the Columbia River Basalt Group, 16.5-14.5 million years ago, and the Deccan Traps, 65 million years ago. For a decade-long eruption of Deccan scale, we calculate a decadal-mean reduction in global surface temperature of 4.5 K, which would recover within 50 years after an eruption ceased unless climate feedbacks were very different in deep-time climates. Acid mists and fogs could have caused immediate damage to vegetation in some regions, but acid-sensitive land and marine ecosystems were well-buffered against volcanic sulphur deposition effects even during century-long eruptions. We conclude that magmatic sulphur from flood basalt eruptions would have caused a biotic crisis only if eruption frequencies and lava discharge rates had been high and sustained for several centuries at a time.

  12. Selective environmental stress from sulphur emitted by continental flood basalt eruptions

    NASA Astrophysics Data System (ADS)

    Schmidt, Anja; Skeffington, Richard A.; Thordarson, Thorvaldur; Self, Stephen; Forster, Piers M.; Rap, Alexandru; Ridgwell, Andy; Fowler, David; Wilson, Marjorie; Mann, Graham W.; Wignall, Paul B.; Carslaw, Kenneth S.

    2016-01-01

    Several biotic crises during the past 300 million years have been linked to episodes of continental flood basalt volcanism, and in particular to the release of massive quantities of magmatic sulphur gas species. Flood basalt provinces were typically formed by numerous individual eruptions, each lasting years to decades. However, the environmental impact of these eruptions may have been limited by the occurrence of quiescent periods that lasted hundreds to thousands of years. Here we use a global aerosol model to quantify the sulphur-induced environmental effects of individual, decade-long flood basalt eruptions representative of the Columbia River Basalt Group, 16.5-14.5 million years ago, and the Deccan Traps, 65 million years ago. For a decade-long eruption of Deccan scale, we calculate a decadal-mean reduction in global surface temperature of 4.5 K, which would recover within 50 years after an eruption ceased unless climate feedbacks were very different in deep-time climates. Acid mists and fogs could have caused immediate damage to vegetation in some regions, but acid-sensitive land and marine ecosystems were well-buffered against volcanic sulphur deposition effects even during century-long eruptions. We conclude that magmatic sulphur from flood basalt eruptions would have caused a biotic crisis only if eruption frequencies and lava discharge rates had been high and sustained for several centuries at a time.

  13. Responses to betaine and inorganic sulphur of sheep in growth performance and fibre growth.

    PubMed

    Nezamidoust, M; Alikhani, M; Ghorbani, G R; Edriss, M A

    2014-12-01

    Sulphur-containing amino acids (SAA) are essential and usually the first limiting amino acids for growth, milk and wool production. The keratin fibre that grows from epidermal tissue is rich in SAA. The rate of fibre growth and its S content are influenced by the availability of SAA. Betaine is a dietary source for a labile methyl group and actively participates in methionine metabolism by donating methyl groups for the remethylation of homocysteine to methionine. Ruminants are capable of synthesizing SAA from inorganic S sources, and most bacteria in the rumen can use inorganic S to meet their requirements for growth. The objective of this study was to examine whether betaine and an inorganic sulphur supplement could provide methyl groups and sulphur amino acids in a way that growth performance and wool production of ewes and lambs are improved. Treatments performed included betaine supplementation, sulphate supplementation and betaine plus sulphate supplementation with five replications for each treatment. The dry matter intake of the ewes was affected by betaine plus sulphate supplementation (p < 0.05). In the ewes, betaine plus sulphate supplementation increased (p < 0.05) the wool growth rate, wool yield, staple length and wool sulphur concentration, while decreasing wool wax and wool yellowness (p < 0.05). In the lambs, wool growth rate, wool yield, fibre diameter, staple length, staple strength, wool sulphur concentration, wool wax and fibre percentage did not differ (p > 0.05) between treatments. In the ewes, plasma methionine concentration increased (p < 0.05) with betaine plus sulphate treatment. No corresponding difference (p > 0.05) was observed in plasma methionine concentration in the lambs. It can be concluded that betaine plus sulphate supplementation has the potential to change wool characteristics in the ewes, while these compounds were without any effect on growth and wool production of the lambs. Combining the two supplements was advantageous

  14. Comparison of the influence of polyaspartic acid and polylysine functional groups on the adsorption at the Cr2O3-Aqueous polymer solution interface

    NASA Astrophysics Data System (ADS)

    Ostolska, Iwona; Wiśniewska, Małgorzata

    2014-08-01

    Polyamino acids are a group of synthesized polymers obtained by polymerization of a given kind of amino acid monomer. Because of high biodegradability of this class of polymers, they can be used as flocculation or stabilization agents in the environmental aspects. Therefore determination of their influence on the stability of the aqueous suspension of metal oxides is important. An influence of different functional groups of polyamino acids, their molecular weight and concentration on the adsorption at the chromium (III) oxide (Cr2O3)-aqueous solution interface was determined. Experiments were carried out for four values of solution pH varying from 3 to 10 (3, 4, 7.6 and 10, respectively). Two polymers were used: anionic polyaspartic acid (ASP) of 6800 and 27,000 as well as polylysine (LYS) of 4900 and 33,000 molecular weights. Changes of surface charge density of colloidal Cr2O3 in the presence and in the absence of macromolecular substances were determined using potentiometric titration. In these studies the influence of the concentration and molecular weight of the ionic polymers on the pHpzc value was determined. Additionally, due to the lack of appropriate literature data, potentiometric titration of the selected polymers was performed to determine pKa values.

  15. Ion-pair chromatography of acidic drug metabolites and endogenic compounds.

    PubMed

    Fransson, B; Wahlund, K G; Johansson, I M; Schill, G

    1976-09-29

    Liquid-liquid chromatographic systems based on ion-pair partition with silica microparticles as the support for the stationary phase have been used for the separation of anionic compounds of biochemical and pharmacological interest. A high separating efficiency can be obtained with both aqueous and organic mobile phases and the retention is easily regulated by the nature and the concentration of the quaternary ammonium counter ion, present in the aqueous phase. The influence of the composition of the liquid phases on the selectivity and separating efficiency has been studied, as well as equilibration methods and the stability of the systems. Examples are given of separations of sulphonamides, barbiturates, glucuronic and sulphuric acid conjugates of steroidal compounds and phenols glycine conjugates of carboxylic acids (hippuric, nicotinuric and salicyluric acid) and anionic metabolites of biogenic amines (indoleacetic, benzoic, mandelic and phenylacetic acid derivatives). PMID:10314

  16. Biomaterial based sulphur di oxide gas sensor

    NASA Astrophysics Data System (ADS)

    Ghosh, P. K.; Sarkar, A.

    2013-06-01

    Biomaterials are getting importance in the present research field of sensors. In this present paper performance of biomaterial based gas sensor made of gum Arabica and garlic extract had been studied. Extract of garlic clove with multiple medicinal and chemical utility can be proved to be useful in sensing Sulphur di Oxide gas. On exposure to Sulphur di Oxide gas the material under observation suffers some temporary structural change, which can be observed in form of amplified potentiometric change through simple electronic circuitry. Exploiting this very property a potentiometric gas sensor of faster response and recovery time can be designed. In this work sensing property of the said material has been studied through DC conductance, FTIR spectrum etc.

  17. Sulphur mountain: Cosmic ray intensity records

    SciTech Connect

    Venkatesan, D.; Mathews, T.

    1985-01-01

    This book deals with the comic ray intensity registrations at the Sulphur Mountain Cosmic Ray Laboratory. The time series of intensity form a valuable data-set, for studying cosmic ray intensity variations and their dependence on solar activity. The IGY neutron monitor started operating from July 1, 1957 and continued through 1963. Daily mean values are tabulated for the period and these are also represented in plots. This monitor was set up by the National Research Council of Canada.

  18. Formic acid enhanced effective degradation of methyl orange dye in aqueous solutions under UV-Vis irradiation.

    PubMed

    Wang, Jingjing; Bai, Renbi

    2016-09-15

    Developing efficient technologies to treat recalcitrant organic dye wastewater has long been of great research and practical interest. In this study, a small molecule, formic acid (FA), was applied as a process enhancer for the degradation of methyl orange (MO) dye as a model recalcitrant organic pollutant in aqueous solutions under the condition of UV-Vis light irradiation and air aeration at the ambient temperature of 25 °C. It was found that the decolouration of the dye solutions can be rapidly achieved, reducing the time, for example, from around 17.6 h without FA to mostly about less than 2 h with the presence of FA. The mineralization rate of MO dye reached as high as 81.8% in 1.5 h in the case of initial MO dye concentration at 25 mg L(-1), which is in contrast to nearly no mineralization of the MO dye for a similar system without the FA added. The study revealed that the generation of the H2O2 species in the system was enhanced and the produced OH radicals effectively contributed to the degradation of the MO dye. Process parameters such as the initial concentration of MO dye, FA dosage and solution pH were all found to have some effect on the degradation efficiency under the same condition of UV-Vis light irradiation and air aeration. The MO dye degradation performance was found to follow a first-order reaction rate to the MO dye concentration in most cases and there existed a positive correlation between the reaction rate constant and the initial FA concentration. Compared to the traditional H2O2/UV-Vis oxidation system, the use of FA as a process-enhancing agent can have the advantages of low cost, easy availability, and safe to use. The study hence demonstrates a promising approach to use a readily available small molecule of FA to enhance the degradation of recalcitrant organic pollutants, such as MO dye, especially for their pre-treatment. PMID:27258621

  19. Morphology controls of GeO 2 particles precipitated by a facile acid-induced decomposition of germanate ions in aqueous medium

    NASA Astrophysics Data System (ADS)

    Jing, Chengbin; Hou, Jinxia; Zhang, Yongheng

    2008-01-01

    GeO 2 single crystals with various morphologies were synthesized at room temperature by an acid-induced homogenous liquid phase precipitation technique without using any surfactants as studied previously. With addition of aqueous ammonia, the solubility of hexagonal GeO 2 in water was significantly increased by formation of soluble germanate ions as confirmed by IR spectra analyses. Supersaturated GeO 2 solution could be produced by adding acid into the GeO 2-ammonia solution through the acid-induced transformation of germinate ions into GeO 2. GeO 2 spheres were obtained with phosphoric acid addition. Truncated cubic-like and cubic-like GeO 2 single crystals could be produced in the solutions with hydrochloric acid and ascorbic acid (vitamin C) additions, respectively. The morphology developments of the GeO 2 particles induced by various acids were discussed and the growth mechanism conforms to BFDH and HP crystal growth models.

  20. Experimental investigation of aqueous corrosion of R7T7 nuclear glass at 90{degrees}C in the presence of humic acids: A kinetic approach

    SciTech Connect

    Gin, S.; Godon, N.; Mestre, J.P.; Vernaz, E.Y.

    1994-12-31

    The dissolution kinetics of the French {open_quotes}R7T7{close_quotes} nonradioactive LWR reference glass in solutions containing dissolved humic acids were investigated at 9O{degrees}C during static tests with imposed or free pH. Experiments conducted in highly dilute media, with a glass-surface-area-to-solution-volume (SA/V) ratio of 5 m{sup -1}, showed that the glass dissolution surface reaction is catalyzed by humic acids. With higher degrees of reaction progress (SA/V = 100 m{sup -1} and free pH) the humic acids impose pH modifications on the system compared with inorganic media; moreover, they directly or indirectly enhance the dissolution of certain alkali metals and transition elements, forming aqueous complexes with the latter. During experiments with an imposed pH of 8.5 (SA/V = 1300 and 5300 m{sup -1}), the humic acids appear to cause increased silica solubility that cannot be accounted for by the formation of silica complexes. A residual corrosion rate in the humic acid media exceeding the rate measured in inorganic media suggests that, in addition to silica, one or more element complexes formed by humic acids may be a kinetically limiting factor. This hypothesis must be confirmed, however, as the quantity of humic acids per unit glass surface area was too small in this experiment to allow unambiguous characterization of the phenomenon.

  1. Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.

    2011-01-01

    A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

  2. Unsaturated C3,5,7,9-Monocarboxylic Acids by Aqueous, One-Pot Carbon Fixation: Possible Relevance for the Origin of Life

    PubMed Central

    Scheidler, Christopher; Sobotta, Jessica; Eisenreich, Wolfgang; Wächtershäuser, Günter; Huber, Claudia

    2016-01-01

    All scientific approaches to the origin of life share a common problem: a chemical path to lipids as main constituents of extant cellular enclosures. Here we show by isotope-controlled experiments that unsaturated C3,5,7,9-monocarboxylic acids form by one-pot reaction of acetylene (C2H2) and carbon monoxide (CO) in contact with nickel sulfide (NiS) in hot aqueous medium. The primary products are toto-olefinic monocarboxylic acids with CO-derived COOH groups undergoing subsequent stepwise hydrogenation with CO as reductant. In the resulting unsaturated monocarboxylic acids the double bonds are mainly centrally located with mainly trans-configuration. The reaction conditions are compatible with an origin of life in volcanic-hydrothermal sub-seafloor flow ducts. PMID:27283227

  3. Thermodynamic characteristics of molecular interactions between L-tryptophan and nicotinic acid and uracyl in aqueous buffer solutions at 298 K

    NASA Astrophysics Data System (ADS)

    Badelin, V. G.; Tyunina, E. Yu.; Mezhevoi, I. N.; Tarasova, G. N.

    2015-12-01

    The interaction between L-tryptophan (Trp) and nicotinic acid (NA) and uracyl (Ur) in aqueous buffer solutions (pH 7.35) at different ratios of reagents is studied via the calorimetry of dissolution. The enthalpies of dissolution of the amino acid in the buffer solutions of the ligands at 298.15 K are obtained. The stoichiometric compositions of the complexes being formed and binding constants have been determined. The values of the thermodynamic characteristics for the complex formation of L-tryptophan with nicotinic acid and uracyl are calculated. It is shown that the formation of molecular complexes with 1 : 2 composition is stabilized by the entropy factor for the Trp-NA system, and by the enthalpy factor for the Trp-Ur system.

  4. Unsaturated C3,5,7,9-Monocarboxylic Acids by Aqueous, One-Pot Carbon Fixation: Possible Relevance for the Origin of Life.

    PubMed

    Scheidler, Christopher; Sobotta, Jessica; Eisenreich, Wolfgang; Wächtershäuser, Günter; Huber, Claudia

    2016-01-01

    All scientific approaches to the origin of life share a common problem: a chemical path to lipids as main constituents of extant cellular enclosures. Here we show by isotope-controlled experiments that unsaturated C3,5,7,9-monocarboxylic acids form by one-pot reaction of acetylene (C2H2) and carbon monoxide (CO) in contact with nickel sulfide (NiS) in hot aqueous medium. The primary products are toto-olefinic monocarboxylic acids with CO-derived COOH groups undergoing subsequent stepwise hydrogenation with CO as reductant. In the resulting unsaturated monocarboxylic acids the double bonds are mainly centrally located with mainly trans-configuration. The reaction conditions are compatible with an origin of life in volcanic-hydrothermal sub-seafloor flow ducts. PMID:27283227

  5. Effects of low molecular weight organic acids on the immobilization of aqueous Pb(II) using phosphate rock and different crystallized hydroxyapatite.

    PubMed

    Wei, Wei; Cui, Jing; Wei, Zhenggui

    2014-06-01

    Understanding the effects of low molecular weight organic acids (LMWOAs) on the transformation of Pb(II) to geochemically stable pyromorphite (PY) by apatite materials (AMs), has considerable benefits for risk assessment and remediation strategies for contaminated water and soil. In this study, we systematically investigated the immobilization of Pb(II) from aqueous solution by natural phosphate rock (PR) and different crystallized hydroxyapatite (HAp) in the absence and presence of LMWOAs (oxalic, malic and citric acids). The results indicated that the effectiveness of PR and HAp in immobilizing Pb(II) followed in descending order by HAp2 (the poorly crystallized HAp), HAp1 (the well crystallized HAp) and PR, regardlessof the presence of LMWOAs. The presence of malic and citric acids significantly decreased the immobilizationefficiency of Pb(II) by HAp1 and PR, clarifying the lower adsorption affinities of Pb(II)-organic acid complexes on HAp1 and PR rather than Pb(II) ion. On thecontrary, oxalic acid could markedly enhance the removal of Pb(II) from aqueous solution by HAp1 and PR through the formation of lead oxalate, which was confirmed by FT-IR and XRDanalysis. Results also showed that LMWOAs had little promoting or inhibiting effect on the immobilization of Pb(II) by HAp2. This study suggested that the ubiquity of LMWOAs in natural environments could retard the transformation efficiency of Pb(II) to PY by AMs, especiallyin thepresenceof oxalic acid, and the poorly crystallized HAp2 had great potential to remediate Pb(II)-contaminated water and soil due to its insusceptibility to LMWOAs. PMID:24216261

  6. Sulphur diagenesis in the sediments of the Kiel Bight, SW Baltic Sea, as reflected by multiple stable sulphur isotopes.

    PubMed

    Strauss, Harald; Bast, Rebecca; Cording, Anja; Diekrup, David; Fugmann, Artur; Garbe-Schönberg, Dieter; Lutter, Andreas; Oeser, Martin; Rabe, Katharina; Reinke, Debora; Teichert, Barbara M A; Westernströer, Ulrike

    2012-01-01

    In this work, the biogeochemistry of marine sediments from the Kiel Bight, coastal SW Baltic Sea, is studied based on the abundance and isotopic composition of organic carbon and different forms of sedimentary sulphur. Active bacterial sulphate reduction, partly under sulphate-limiting conditions, is evident from paired δ(34)S and δ(18)O values of pore water sulphate. The resulting pore water sulphide is partly precipitated as acid-volatile iron sulphide and subsequently forms sedimentary pyrite, partly serves in later diagenetic sulphurisation of organic matter, or remains dissolved in the pore water, all evident from the respective δ(34)S values. Microbial sulphate turnover is associated with an apparent isotopic fractionation between dissolved sulphate and dissolved sulphide (Δ(34)S) that varies between 46 and 66‰. PMID:22303924

  7. Redox reactions of dissolved organic matter contribute to anaerobic sulphur cycling in peatland soils

    NASA Astrophysics Data System (ADS)

    Blodau, C.; Margit, R.; Bernhard, M.; Moore, T. R.

    2004-05-01

    Sulphate reduction rates in wetland soils typically account for a large fraction of the anaerobic electron flow, despite small pool sizes of sulphate in the pore waters. The studies objective was to test the hypothesis that recycling of sulphur occurs and that redox-reactions of dissolved organic matter (DOM) are involved in the recycling process. To examine the recycling process we used peat mesocosm from two peatlands in Ontario, Canada and subjected them to sulphur deposition and vertical water flow of about 2 mm/day. Depth profiles of DOC and sulphate concentrations were determined and vertical mass balances calculated. In addition we determined 34S sulphate profiles of pore waters. Batch experiments with addition of H2S to solutions of standard peat humic acid (Pahokee Peat, IHSS) were used to determine whether H2S was oxidized by humic acids, and what the reaction products were. Enrichment with 34S at intermediate depths, constant sulphate concentrations with depth and absence of oxygen suggested that sulphate reduction and anaerobic sulphate release concurrently occurred. In the batch experiments two apparent reactions of H2S with DOM were observed. In the fast initial reaction, H2S was oxidized mostly to elemental sulphur and secondarily to sulphate. Production of thiosulfate was not observed. In a slower reaction step H2S was further consumed and the sum of dissolved inorganic forms of sulphur in the pore water decreased. This was interpreted as H2S being incorporated into the organic substance. No systematic relationship between pH and the oxidation process was found. Overall the results suggest that dissolved organic matter is involved in an anaerobic sulphur cycle allowing for high rates of sulphate reduction in sulphate-poor peatlands.

  8. Microbial carbon metabolism associated with electrogenic sulphur oxidation in coastal sediments.

    PubMed

    Vasquez-Cardenas, Diana; van de Vossenberg, Jack; Polerecky, Lubos; Malkin, Sairah Y; Schauer, Regina; Hidalgo-Martinez, Silvia; Confurius, Veronique; Middelburg, Jack J; Meysman, Filip J R; Boschker, Henricus T S

    2015-09-01

    Recently, a novel electrogenic type of sulphur oxidation was documented in marine sediments, whereby filamentous cable bacteria (Desulfobulbaceae) are mediating electron transport over cm-scale distances. These cable bacteria are capable of developing an extensive network within days, implying a highly efficient carbon acquisition strategy. Presently, the carbon metabolism of cable bacteria is unknown, and hence we adopted a multidisciplinary approach to study the carbon substrate utilization of both cable bacteria and associated microbial community in sediment incubations. Fluorescence in situ hybridization showed rapid downward growth of cable bacteria, concomitant with high rates of electrogenic sulphur oxidation, as quantified by microelectrode profiling. We studied heterotrophy and autotrophy by following (13)C-propionate and -bicarbonate incorporation into bacterial fatty acids. This biomarker analysis showed that propionate uptake was limited to fatty acid signatures typical for the genus Desulfobulbus. The nanoscale secondary ion mass spectrometry analysis confirmed heterotrophic rather than autotrophic growth of cable bacteria. Still, high bicarbonate uptake was observed in concert with the development of cable bacteria. Clone libraries of 16S complementary DNA showed numerous sequences associated to chemoautotrophic sulphur-oxidizing Epsilon- and Gammaproteobacteria, whereas (13)C-bicarbonate biomarker labelling suggested that these sulphur-oxidizing bacteria were active far below the oxygen penetration. A targeted manipulation experiment demonstrated that chemoautotrophic carbon fixation was tightly linked to the heterotrophic activity of the cable bacteria down to cm depth. Overall, the results suggest that electrogenic sulphur oxidation is performed by a microbial consortium, consisting of chemoorganotrophic cable bacteria and chemolithoautotrophic Epsilon- and Gammaproteobacteria. The metabolic linkage between these two groups is presently unknown and

  9. Microbial carbon metabolism associated with electrogenic sulphur oxidation in coastal sediments

    PubMed Central

    Vasquez-Cardenas, Diana; van de Vossenberg, Jack; Polerecky, Lubos; Malkin, Sairah Y; Schauer, Regina; Hidalgo-Martinez, Silvia; Confurius, Veronique; Middelburg, Jack J; Meysman, Filip JR; Boschker, Henricus TS

    2015-01-01

    Recently, a novel electrogenic type of sulphur oxidation was documented in marine sediments, whereby filamentous cable bacteria (Desulfobulbaceae) are mediating electron transport over cm-scale distances. These cable bacteria are capable of developing an extensive network within days, implying a highly efficient carbon acquisition strategy. Presently, the carbon metabolism of cable bacteria is unknown, and hence we adopted a multidisciplinary approach to study the carbon substrate utilization of both cable bacteria and associated microbial community in sediment incubations. Fluorescence in situ hybridization showed rapid downward growth of cable bacteria, concomitant with high rates of electrogenic sulphur oxidation, as quantified by microelectrode profiling. We studied heterotrophy and autotrophy by following 13C-propionate and -bicarbonate incorporation into bacterial fatty acids. This biomarker analysis showed that propionate uptake was limited to fatty acid signatures typical for the genus Desulfobulbus. The nanoscale secondary ion mass spectrometry analysis confirmed heterotrophic rather than autotrophic growth of cable bacteria. Still, high bicarbonate uptake was observed in concert with the development of cable bacteria. Clone libraries of 16S complementary DNA showed numerous sequences associated to chemoautotrophic sulphur-oxidizing Epsilon- and Gammaproteobacteria, whereas 13C-bicarbonate biomarker labelling suggested that these sulphur-oxidizing bacteria were active far below the oxygen penetration. A targeted manipulation experiment demonstrated that chemoautotrophic carbon fixation was tightly linked to the heterotrophic activity of the cable bacteria down to cm depth. Overall, the results suggest that electrogenic sulphur oxidation is performed by a microbial consortium, consisting of chemoorganotrophic cable bacteria and chemolithoautotrophic Epsilon- and Gammaproteobacteria. The metabolic linkage between these two groups is presently unknown and

  10. Ionic liquid-based ultrasound-assisted extraction and aqueous two-phase system for analysis of caffeoylquinic acids from Flos Lonicerae Japonicae.

    PubMed

    Tan, Ting; Lai, Chang-Jiang-Sheng; OuYang, Hui; He, Ming-Zhen; Feng, Yulin

    2016-02-20

    In this work, an ionic liquid-based ultrasonic-assisted extraction (ILUAE) method was developed to extract caffeoylquinic acids (CQAs) from Flos Lonicerae Japonicae (FLJ). ILUAE parameters were optimized by response surface methodology, including IL concentration, ultrasonic time, and liquid-solid ratio. Optimized ILUAE approach gained the highest extraction yields of 28.53, 18.21, 3.84mg/g for 3-O-caffeoylquinic acid (C1), 3,5-di-O-caffeoylquinic acid (C2), 3,4-di-O-caffeoylquinic acid (C3), respectively. C1-C3 are the three most abundant CQAs compounds in FLJ. The method showed comparable extraction yield and shorter extraction time compared with conventional extraction techniques. Subsequently, an aqueous two-phase system (ATPS) was applied in extraction solutions. Two trace CQAs, 5-O-caffeoylquinic acid (C4) and 4,5-di-O-caffeoylquinic acid (C5), were significantly enriched with signal to noise values increasing from less than 10 to higher than 1475. The results indicated that ILUAE and ATPS are efficient and environmentally-friendly sample extraction and enrichment techniques for CQAs from herbal medicines. PMID:26730510

  11. Heat-initiated prebiotic formation of peptides from glycine/aspartic acid and glycine/valine in aqueous environment and clay suspension

    NASA Astrophysics Data System (ADS)

    Pant, Chandra Kala; Lata, Hem; Pathak, Hari Datt; Mehata, Mohan Singh

    2009-04-01

    The effect of heat on the reaction system of glycine/aspartic acid and glycine/valine in the aqueous environment as well as in montmorillonite clay suspension with or without divalent cations (Ca2+, Mg2+ and Ni2+) has been investigated at 85°C±5°C for varying periods under prebiotic drying and wetting conditions. The resulting products were analysed and characterized by chromatographic and spectroscopic methods. Peptide formation appears to depend on the duration of heat effect, nature of reactant amino acids and, to some extent, on montmorillonite clay incorporated with divalent cations. In the glycine/aspartic acid system, oligomerization of glycine was limited up to trimer level (Gly)3 along with the formation of glycyl-aspartic acid, while linear and cyclic peptides of aspartic acid were not formed, whereas the glycine/valine system preferentially elongated homo-oligopeptide of glycine up to pentamer level (Gly)5 along with formation of hetero-peptides (Gly-Val and Val-Gly). These studies are relevant in the context of the prebiotic origin of proteins and the role of clay and metal ions in condensation and oligomerization of amino acids. The length of the bio-oligomer chain depends upon the reaction conditions. However, condensation into even a small length seems significant, as the same process would have taken millions of years in the primitive era of the Earth, leading to the first proteins.

  12. Electrospray mass spectrometry of some proteins and the aqueous solution acid/base equilibrium model in the negative ion detection mode

    NASA Astrophysics Data System (ADS)

    Le Blanc, J. C. Y.; Guevremont, R.; Siu, K. W. M.

    1993-06-01

    Basic solutions of myoglobin, [beta]-lactoglobulin, pepsin and ubiquitin have been examined by means of electrospray mass spectrometry in the negative ion detection mode. The distribution of protein ions in the mass spectra was found to correlate well with the distribution of protein species in solution calculated from published titration data. These results lend further credibility to an earlier proposed aqueous solution acid/base equilibrium model, which relates the "bellshape" ion distribution observed in the electrospray mass spectrometry of proteins to the distribution of protein ions in solution.

  13. An investigation of the applicability of attenuated total reflection infrared spectroscopy for measurement of solubility and supersaturation of aqueous citric acid solutions

    NASA Astrophysics Data System (ADS)

    Dunuwila, Dilum D.; Carroll, Leslie B.; Berglund, Kris A.

    1994-04-01

    Currently applied methods for measurement of solubility and supersaturation based on viscometry, refractometry, interferometry and density require the separation of phases prior to measurement. ATR (attenuated total reflection) infrared spectroscopy provides a unique configuration in which the infrared spectrum of a liquid phase can be obtained in a slurry without phase separation. The applicability of the technique was investigated using a micro Circle ® open boat cell equipped with a ZnSe (zinc selenide) ATR rod. Experiments conducted with aqueous citric acid proved that ATR infrared spectroscopy can be successfully employed to determine solubility and supersaturation.

  14. 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 µmol/L) and quantification limits (14-22 µmol/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

  15. Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids

    EPA Science Inventory

    In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry...

  16. Efficient combination of promoter and catalyst for chromic acid oxidation of propan-2-ol to acetone in aqueous acid media at room temperature.

    PubMed

    Mukherjee, Kakali; Saha, Rumpa; Ghosh, Aniruddha; Ghosh, Sumanta K; Saha, Bidyut

    2013-01-15

    Oxidation of propan-2-ol to acetone was carried out in aqueous media at room temperature. The effect of promoter (PA, bpy, phen), micellar catalyst (SDS, CPC, TX-100) and their combination has been studied. The reactions were performed under the condition [Propan-2-ol]T≫[Cr(VI)]T at 30°C. Then kobs and half life of all the reaction were determined to identify which promoter and which combination are the most effective for this oxidation. Among the promoters phen accelerates the reaction most in aqueous media. In absence of promoters anionic surfactant SDS increases the rate more effectively than neutral surfactant TX-100. CPC retards the rate in comparison to aqueous media. The rate of the oxidation is highest in presence of the combination of bpy and SDS. PMID:23123236

  17. An Aqueous Thermodynamic Model for the Complexation of Sodium and Strontium with Organic Chelates valid to High Ionic Strength. I. Ethylenedinitrilotetraacetic acid (EDTA)

    SciTech Connect

    Felmy, Andrew R.; Mason, Marvin J.

    2003-04-01

    An aqueous thermodynamic model is developed, which accurately describes the effects of Na+ complexation, ionic strength, carbonate concentration, and temperature on the complexation of Sr2+ by ethylenedinitrilotetraacetic acid (EDTA) under basic conditions. The model is developed from the analysis of literature data on apparent equilibrium constants, enthalpies, and heat capacities; as well as on an extensive set of solubility data on SrCO3(c) in the presence of EDTA obtained as part of this study. The solubility data for SrCO3(c) were obtained in solutions ranging in Na2CO3 concentration from 0.01m to 1.8m, in NaNO3 concentration from 0 to 5m, and at temperatures extending to 75?C. The final aqueous thermodynamic model is based upon the equations of Pitzer and requires the inclusion of a NaEDTA3- species. An accurate model for the ionic strength dependence of the ion-interaction coefficients for the SrEDTA2- and NaEDTA3- aqueous species allows the extrapolation of standard state equilibrium constants for these species which are significantly different from the 0.1m reference state values available in the literature. The final model is tested by application to chemical systems containing competing metal ions (i.e., Ca2+) to further verify the proposed model and indicate the applicability of the model parameters to chemical systems containing other divalent metal-EDTA complexes.

  18. Review of the origin of sulphur in DN-1 discharge and its implication for future development, Dauin prospect, central Philippines

    SciTech Connect

    Bayrante, L.F.; Hermoso, D.Z.; Candelaria, M.R.

    1997-12-31

    Well DN-1, the first exploratory well of the Dauin geothermal prospect discharged in 1983 substantial quantities of sulphur with a near-neutral pH fluid (pH 6.4 to 7.2) containing maximum chloride levels of 3,300 mg/kg, SO{sub 4} of 300 mg/kg; and high CO{sub 2} and H{sub 2}S relative to the production wells in Palinpinon Field to the north. The chemistry of DN-1 discharge-fluid and the origin of sulphur have been the cause of apprehension for any future development due to concerns on the presence of a possible acid resource southeast of Cuernos de Negros. A reinterpretation of the previous and new surface data was undertaken in 1992 and 1996, including the origin of sulphur, to evaluate the potential of Dauin for development. The results indicate that the sulphur in DN-1 is formed from partial oxidation of hydrogen sulphide derived from the neutralised-acid fluids formed by sulphur hydrolysis at shallow levels but distant from DN-1. The study argues for the presence of near neutral exploitable resource in the prospect area.

  19. Integration of advanced oxidation processes at mild conditions in wet scrubbers for odourous sulphur compounds treatment.

    PubMed

    Vega, Esther; Martin, Maria J; Gonzalez-Olmos, Rafael

    2014-08-01

    The effectiveness of different advanced oxidation processes on the treatment of a multicomponent aqueous solution containing ethyl mercaptan, dimethyl sulphide and dimethyl disulphide (0.5 mg L(-1) of each sulphur compound) was investigated with the objective to assess which one is the most suitable treatment to be coupled in wet scrubbers used in odour treatment facilities. UV/H2O2, Fenton, photo-Fenton and ozone treatments were tested at mild conditions and the oxidation efficiency obtained was compared. The oxidation tests were carried out in magnetically stirred cylindrical quartz reactors using the same molar concentration of oxidants (hydrogen peroxide or ozone). The results show that ozone and photo-Fenton are the most efficient treatments, achieving up to 95% of sulphur compounds oxidation and a mineralisation degree around 70% in 10 min. Furthermore, the total costs of the treatments taking into account the capital and operational costs were also estimated for a comparative purpose. The economic analysis revealed that the Fenton treatment is the most economical option to be integrated in a wet scrubber to remove volatile organic sulphur compounds, as long as there are no space constraints to install the required reactor volume. In the case of reactor volume limitation or retrofitting complexities, the ozone and photo-Fenton treatments should be considered as viable alternatives. PMID:24873715

  20. High pressure liquid chromatographic identification of hyaluronic acid and chondroitin sulphate disaccharides.

    PubMed

    Zebrower, M; Kieras, F J; Heaney-Kieras, J

    1991-06-01

    In this report we describe a system capable of resolving all of the known unsaturated disaccharides derived from the chondroitin sulphates, dermatan sulphate and hyaluronic acid by chondroitinase digestion. This system is superior to others in that the non-sulphated and mono-, di- and tri-sulphated disaccharides can be separated with good resolution in approximately 40 min in an isocratic solvent. The system employs an amino-cyano silica gel column (Whatman Partisil 5 PAC, 25 cm) and is eluted with an isocratic solvent consisting of 48% (v/v) acetonitrile, 14% (v/v) methanol and 38% (v/v) aqueous buffer. This aqueous buffer contains 0.5 M Tris-HCl, 0.1 M boric acid, 23.4 mM sulphuric acid, pH 8.0. UV absorption is monitored at 229 nm and for most disaccharides as little as 150 ng can be reliably determined. The addition of boric acid to the eluent is essential for good resolution of all components and the addition of low concentrations of sulphuric acid is used to control the elution times of various components. The system was applied to the analysis of glycosaminoglycan standards and excellent agreement with previous compositional analyses was obtained. PMID:1794040