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Sample records for aqueous solutions effect

  1. Aqueous polyethylene oxide solutions

    International Nuclear Information System (INIS)

    A number of aspects concerning the reorientation of polymer, water and ion hydration complexes have been studied in aqueous solution of polyethylene oxide (PEO). The polymer dynamics are investigated by 1H-PEO and 13C-PEO nuclear relaxation experiments. 162 refs.; 30 figs.; 19 tabs

  2. Treatment of Aqueous Solutions

    NARCIS (Netherlands)

    Van Spronsen, J.; Witkamp, G.J.

    2013-01-01

    The invention is directed to a process for the recovery or removal of one or more crystallizable compounds from an aqueous solution containing, apart from the said crystallizable compounds, one or more organic or inorganic scale- forming or scale-inducing materials having a lower solubility in water

  3. Comparative analysis of the effect of pretreating aspen wood with aqueous and aqueous-organic solutions of sulfuric and nitric acid on its reactivity during enzymatic hydrolysis

    DEFF Research Database (Denmark)

    Dotsenko, Gleb; Osipov, D. O.; Zorov, I. N.;

    2016-01-01

    The effect of aspen wood pretreatment methods with the use of both aqueous solutions of sulfuric and nitric acids and aqueous-organic solutions (ethanol, butanol) of sulfuric acid (organosolv) on the limiting degree of conversion of this type of raw material into simple sugars during enzymatic...... of ground wood by 300–400%, compared to the initial raw material. Pretreatment with a 4.8% aqueous solution of nitric acid (125°C, 1.8 MPa, 10 min) is shown to be most effective, as it increases the reactivity of the ground aspen wood by more than 500%....

  4. Effect of electron beam irradiation on the degradation of monochlorophenols in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    ADELEKE Olukunle Francis; ZHOU Rui-min; Zu Jian-hua; Ekoko Bakambo Gracien

    2005-01-01

    Electron beam was successfully used for the degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) in aqueous solutions in this research. The effect of radiation dose on substrate degradation and dechlorination of solutions with concentration of 50 mg/L was investigated. The effect of initial concentration, pH and presence of oxygen was also investigated. The concentration of 2-CP and 4-CP remaining in solution after irradiation were measured by HPLC. The results showed that increased radiation dose led to increased degradation of the chlorophenols and increased Cl- yield. Deaeration was also found to significantly increase the rate of degradation of chlorophenols in water while degradation and dechlorination under alkaline condition was lower than at low to neutral pH.

  5. Effects of solution P H on the adsorption of aromatic compounds from aqueous solutions by activated carbon

    International Nuclear Information System (INIS)

    Absorption of p-Cresol, Benzoic acid and Nitro Benzene by activated carbon from dilute aqueous solutions was carried out under controlled ph conditions at 310 k. In acidic conditions, well below the pKa of all solutes, it was observed that the adsorbate solubility and the electron density of its aromatic ring were the influencing factors on the extent of the adsorption by affecting the extent of London dispersion forces. In higher solution ph conditions, on the other hand, it was found that the electrostatic forces played a significant role on the extent of adsorption. The Effect of ph must be considered from its combined effects on the carbon surface and on the solute molecules. It was found that the uptake of the molecular forms of the aromatic solutes was dependent on the substituents of the aromatic ring. Adsorption of the solutes in higher P H values was found to be dependent on the concentration of anionic form of the solutes. All isotherms were fitted into Freundlich Isotherm Equations

  6. Effect of 60Co gamma-ray irradiation on dilute aqueous solutions of surfactants

    International Nuclear Information System (INIS)

    Present work deals with the effects of gamma irradiation from 60Co γ-ray source upon aqueous solutions of three kinds of surfactants. When dilute aqueous solutions of sodium dodecyl sulfate (SDS, anionic), cethyl trimethyl ammonium chloride (CTAC, cationic), and polyoxyethylene lauryl ether (POE, non-ionic) were irradiated with γ-rays at a room temperature, the residual concentration, products, surface tension, and forming power were examined by colorimetric method, IR spectrophotometric method, gaschromatography, Ross-Miles method, and Traube's stalagmometer etc. These surfactants were decomposed by the irradiation and thus the surface tension increased and the forming power, on the contrary, decreased with dose. Radiation chemical yields (G-value) of the degradation were about 1 for the solutions of SDS and CTAC, and about 0.3 for the POE solution. From the experimental results, it was found that following chemical reactions seem to occur followed by the radiolysis of water: a) bond cleavage of ester for SDS, of CN for CTAC, and of oxyethylene for POE, b) hydrogen abstraction from the surfactants, c) production of CO bond in the presence of dissolved oxygen. (auth.)

  7. Sensitizing effect of cerium (4) sulfate on photooxidation of organic compounds in aqueous solutions

    International Nuclear Information System (INIS)

    Influence of Ce(SO4)2 addition on the photooxidation rate of organic substances in aqueous solutions has been discussed. It is shown that to a certain value, the rate constant of oxalic acid oxidation increases linearly with increasing oxidant amount. Using a combination of chemical and photochemical oxidation of oxalic acid in aqueous solution with Ce(SO4)2 as a sensitizer, one can increase the oxidation rate by a factor of 45 and to reduce the time required for carbon determination in aqueous solutions from 4-5 hours down to 8-9 min

  8. Effect of salt identity on the phase diagram for a globularprotein in aqueous electrolyte solution

    Energy Technology Data Exchange (ETDEWEB)

    Bostrom, Mathias; Tavares, Frederico W.; Ninham, Barry W.; Prausnitz, John M.

    2006-02-22

    Monte Carlo simulations are used to establish the potential of mean force between two globular proteins in an aqueous electrolyte solution. This potential includes nonelectrostatic contributions arising from dispersion forces first, between the globular proteins, and second, between ions in solution and between each ion and the globular protein. These latter contributions are missing from standard models. The potential of mean force, obtained from simulation, is fitted to an analytic equation. Using our analytic potential of mean force and Barker-Henderson perturbation theory, we obtain phase diagrams for lysozyme solutions that include stable and metastable fluid-fluid and solid-fluid phases when the electrolyte is 0.2 M NaSCN or NaI or NaCl. The nature of the electrolyte has a significant effect on the phase diagram.

  9. Biosorption of heavy metal ions from aqueous solutions by short hemp fibers: Effect of chemical composition.

    Science.gov (United States)

    Pejic, Biljana; Vukcevic, Marija; Kostic, Mirjana; Skundric, Petar

    2009-05-15

    Sorption potential of waste short hemp fibers for Pb(2+), Cd(2+) and Zn(2+) ions from aqueous media was explored. In order to assess the influence of hemp fiber chemical composition on their heavy metals sorption potential, lignin and hemicelluloses were removed selectively by chemical modification. The degree of fiber swelling and water retention value were determined in order to evaluate the change in accessibility of the cell wall components to aqueous solutions due to the fiber modification. The effects of initial ion concentration, contact time and cosorption were studied in batch sorption experiments. The obtained results show that when the content of either lignin or hemicelluloses is progressively reduced by chemical treatment, the sorption properties of hemp fibers are improved. Short hemp fibers are capable of sorbing metal ions (Pb(2+), Cd(2+) and Zn(2+)) from single as well as from ternary metal ion solutions. The maximum total uptake capacities for Pb(2+), Cd(2+) and Zn(2+) ions from single solutions are the same, i.e. 0.078mmol/g, and from ternary mixture 0.074, 0.035 and 0.035mmol/g, respectively.

  10. Ultrasonic Degradation of Fuchsin Basic in Aqueous Solution: Effects of Operating Parameters and Additives

    Directory of Open Access Journals (Sweden)

    Rui-Jia Lan

    2013-01-01

    Full Text Available Ultrasonic degradation is one of the recent advanced oxidation processes (AOPs and proven to be effective for removing low-concentration organic pollutants from aqueous solutions. In this study, removal of fuchsin basic from aqueous solutions by ultrasound was investigated. The effects of operating parameters such as ultrasound power (200 W–500 W, initial pH (3–6.5, and temperature (15, 22, 35, and 60°C on the ultrasonic degradation were studied. The degradation of fuchsin under ultrasound irradiation basic was found to obey pseudo first-order reaction kinetics. Addition of catalyst Fe(II had a markedly positive effect on degradation. 84.1% extent of degradation was achieved at initial dye concentration 10 μmol L−1, ultrasound power 400 W, ultrasound frequency 25 kHz, dosage of Fe(II 4 mg L−1, initial pH 6.5, and temperature 22°C. But addition of heterogeneous catalyst TiO2 affected degradation slightly. Addition of radical scavenger suppressed fuchsin basic degradation significantly.

  11. Effect of heterogeneous catalysts on the radiolysis of aqueous phenol solutions

    International Nuclear Information System (INIS)

    A carbon sorbent or a heterogeneous catalyst on a carbon support had a surface-dependent effect on the route and quantitative characteristics pertaining to radiative decomposition of phenol adsorbed from an aqueous solution in a flow system. The heterogeneous catalysts studied were manganese dioxide, platinum, nickel, and nickel-palladium deposited on activated carbon brands AG-3 and BAU (birch carbon) as well as on a spherical carbon sorbent. The nickel-containing catalysts were modified by addition of a 12th series, reduced heteropolytungstate (HPT). The manganese dioxide was deposited on AG-3 carbon by a radiation-chemical method. A weighed amount of the sorent was impregnated with a potassium permanganate solution and then irradiated from a γ source

  12. Effects of hydration on the thermodynamic properties of aqueous ethylene glycol ether solutions

    Energy Technology Data Exchange (ETDEWEB)

    Schroedle, Simon [Institut fuer Physikalische und Theoretische Chemie, Universitaet Regensburg, D-93040 Regensburg (Germany); Hefter, Glenn [Chemistry Department, DSE Murdoch University, Murdoch, WA 6150 (Australia); Buchner, Richard [Institut fuer Physikalische und Theoretische Chemie, Universitaet Regensburg, D-93040 Regensburg (Germany)]. E-mail: richard.buchner@chemie.uni-regensburg.de

    2005-05-15

    The densities and isobaric specific heat capacities of binary mixtures of water with various open-chain and cyclic ethylene glycol ethers have been measured at 298.15 K using vibrating tube densimetry, and flow or differential scanning calorimetry, respectively. Excess molar volumes were derived over the whole composition range. Molar isobaric heat capacities and the relative apparent thermodynamic quantities were determined in the water-rich region. The data reflect the changes in the structure and hydrogen-bond dynamics of water caused by these non-ionic solutes. The observed effects are discussed in terms of the influence of hydrophobic hydration on the thermodynamic properties of aqueous solutions. Correlations are given that enable the prediction of the thermodynamic properties of open-chain and cyclic oligo(ethylene oxide) ethers in their pure liquid state and at infinite dilution in water.

  13. Effects of changing solution chemistry on Fe 3+/Fe 2+ isotope fractionation in aqueous Fe-Cl solutions

    Science.gov (United States)

    Hill, Pamela S.; Schauble, Edwin A.; Young, Edward D.

    2010-12-01

    The range in 56Fe/ 54Fe isotopic compositions measured in naturally occurring iron-bearing species is greater than 5‰. Both theoretical modeling and experimental studies of equilibrium isotopic fractionation among iron-bearing species have shown that significant fractionations can be caused by differences in oxidation state (i.e., redox effects in the environment) as well as by bond partner and coordination number (i.e., nonredox effects due to speciation). To test the relative effects of redox vs. nonredox attributes on total Fe equilibrium isotopic fractionation, we measured changes, both experimentally and theoretically, in the isotopic composition of an Fe 2+-Fe 3+-Cl-H 2O solution as the chlorinity was varied. We made use of the unique solubility of FeCl 4- in immiscible diethyl ether to create a separate spectator phase against which changes in the aqueous phase could be quantified. Our experiments showed a reduction in the redox isotopic fractionation between Fe 2+- and Fe 3+-bearing species from 3.4‰ at [Cl -] = 1.5 M to 2.4‰ at [Cl -] = 5.0 M, due to changes in speciation in the Fe-Cl solution. This experimental design was also used to demonstrate the attainment of isotopic equilibrium between the two phases, using a 54Fe spike. To better understand speciation effects on redox fractionation, we created four new sets of ab initio models of the ferrous chloride complexes used in the experiments. These were combined with corresponding ab initio models for the ferric chloride complexes from previous work. At 20 °C, 1000 ln β ( β = 56Fe/ 54Fe reduced partition function ratio relative to a dissociated Fe atom) values range from 6.39‰ to 5.42‰ for Fe(H 2O) 62+, 5.98‰ to 5.34‰ for FeCl(H 2O) 5+, and 5.91‰ to 4.86‰ for FeCl 2(H 2O) 4, depending on the model. The theoretical models predict ferric-ferrous fractionation about half as large (depending on model) as the experimental results. Our results show (1) oxidation state is likely to be the

  14. The effect of temperature on radiolysis of iodide ion diluted aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gorbovitskaya, T.; Tiliks, J. [Latvia Univ., Lab. of Radiation Chemistry, Riga (Latvia)

    1996-12-01

    To investigate the radiolysis of iodine containing aqueous solutions a flow type facility (ITF) has a possibility to irradiate aqueous solutions in the steel vessel with {sup 60}Co {gamma}-rays and continuously (on line) to analyze the products of radiolysis both in liquid and in gaseous phases. By means of ITF the formation of I{sub ox} (I{sub 2} + I{sub 3}{sup -} + HOI), IO{sub 3}{sup -}, H{sub 2}O{sub 2} was studied in 10{sup -5} - 10{sup -3} mol/dm{sup 3} CsI aqueous solutions by their radiolysis at dose rate 4.5 kGv/h for six hours in region of temperatures from 313 to 404 K. Some experiments in glass ampoules were also performed. The steady-state concentrations of I{sub ox} and IO{sub 3}{sup -} decreased with increasing temperature as linear function of inverted temperature. The effect decreased with decreasing concentration of iodide ion. As the result, at high temperatures (T{>=}380 K) the steady-state concentration of I{sub ox} does not depend essentially on the iodide ion initial concentration. Molecular iodine (I{sub 2}) released from the solution was the main radiolysis product in gaseous phase. Its steady-state concentration increased with increasing temperature because of iodine solubility in the water and decreased at the same time because the radiolytic iodine concentrations decreased. Therefore the most volatility of irradiated 10{sup -3} and 10{sup -4}M CsI solutions was observed at the temperature about 350 K. The volatility of 10{sup -5}M solutions gradually decreased with increasing temperature. The experimental data were explained on the base of the hypothesis that the reaction between I{sub 2} and radiolytic H{sub 2}O{sub 2} was the limit one determining the temperature dependence of I{sub ox} and IO{sub 3}{sup -}steady-state concentrations. Its activation energy was estimated to be 27,5 kcal.mol{sup -1}. The temperature dependence for reaction (IO{sup -} + H{sub 2}O{sub 2}) was also estimated. (author) 8 figs., 1 tab., 17 refs.

  15. EFFECT OF WEAK INTERACTIONS ON PHENOL ADSORPTION FROM AQUEOUS SOLUTIONS BY AMINATED POLYMERIC ADSORBENTS

    Institute of Scientific and Technical Information of China (English)

    Wei-ming Zhang; Jin-long Chen; Ai-min Li; Bing-cai Pan; Qun Chen; Ming-yang He; Quan-xing Zhang

    2006-01-01

    Adsorption behaviors of phenol from aqueous solutions have been investigated in batch systems at 303 K and 318 K respectively, using hypercrosslinked polymeric adsorbent (CHA 111), aminated hypercrosslinked polymeric adsorbents (NDA101, NDA 103, NDA105) and weakly basic polymeric adsorbent (D301) with a view to studying the effect of hydrogen bonding and Van der Waals interactions between adsorbate and the adsorbent. All adsorption isotherms can be well fitted by Langmuir and Freundlich equations. Compared with D301 driven by hydrogen bonding interaction only and CHA111 driven by Van der Waals interaction only, phenol adsorption on aminated adsorbents driven by both hydrogen bonding and Van der Waals interactions were apparently different, i.e., negative effect for NDA105, positive effect for NDA101 and synergistic effect for NDA103. In this synergistic action, some weak interactions would contribute more or less to the adsorption than they work individually.

  16. Radiolysis of Aqueous Toluene Solutions

    International Nuclear Information System (INIS)

    Aqueous toluene solutions have been irradiated with Co γ-rays. In unbuffered solutions the various cresol isomers are formed in a total yield of 0.45, 0.87 and 0.94 molecules/100 eV absorbed energy in argon-, N2O- and air - saturated solutions, respectively. The yields are reduced in acid (pH 3) solutions (G 0.14, 0.14 and 0.52, respectively) but the reduction is compensated by the formation of 1,2-di-phenylethane in yields of 0.49 and 1.60 in argon- and N2O-saturated solutions, respectively. Benzyl radicals are formed through an acid catalysed water elimination reaction from the initially formed hydroxymethylcyclohexadienyl radical. Phenyltolylmethanes, dimethylbiphenyls and partly reduced dimers are also formed during the radiolysis. Hydrogen is formed in the same yield as the molecular yield, g(H2). Xylene isomers and benzene are formed in trace quantities. The most remarkable effects of the addition of Fe(III) ions to deaerated acid toluene solutions are the formation of benzyl alcohol and benzaldehyde and an increase in the yield of 1,2-diphenylethane

  17. Reactant-solute encounters in aqueous solutions studied by kinetic methods : hydration cosphere overlap and camouflage effects

    NARCIS (Netherlands)

    Engberts, Jan B.F.N.; Blandamer, Michael J.

    1998-01-01

    Rates of chemical reactions in aqueous solutions are often sensitive to low concentrations of added solutes such as ureas, alcohols, α-amino acids and carbohydrates. In this work, several simple chemical reactions were used to probe this sensitivity, which arises from interactions between added solu

  18. EFFECT OF HYPERCROSSLINKED RESINS SURFACE CHEMISTRY ON THEADSORPTION OF PHENOL FROM AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Guan-hua Meng; Ai-min Lia; Wei-ben Yang; Fu-qiang Liu; Quan-xing Zhang

    2006-01-01

    Two hypercrosslinked resins with similar physical characters but different surface chemistry were synthesized and used to remove phenol from aqueous solutions. The FTIR spectra, elemental analysis and the Boehm titration were used to characterize the chemical properties of the resins. The adsorption experiments were carried out using the bottle-point technique, and the effects of the surface chemistry on the adsorption were discussed. The adsorption data fit well with the Freundlich model, indicating the heterogeneity of the resins surface. It could be seen from the experimental results that the adsorption capacity increased with the increase in the total surface concentration of oxygen-containing groups. The pH dependence and the effects of ionic strength were also discussed. The kinetic adsorption data fit well with the pseudo-second order model, and the results showed that the surface oxygen-containing groups have little effect on the adsorption rate.

  19. Effect of Protonation on the Solution and Phase Behavior of Aqueous Sodium Myristate.

    Science.gov (United States)

    Wen; Franses

    2000-11-01

    Aqueous sodium myristate solutions have been shown to have unusually low dynamic tensions (1-10 mN/m) under pulsating area conditions. These solutions have no sharp solubility limit, evidently because they are protonated (or "hydrolyzed") to form the much less soluble myristic acid and acid soaps. With no added electrolytes, the protonation fraction is 1% or less. The apparent protonation equilibrium "constant" increases with increasing concentration, indicating strong solution nonidealities, in addition to micellization. This protonation seems to affect the solution and phase behavior of aqueous sodium myristate strongly, as evidenced by the effect of added NaOH. Ion-selective electrodes (for Na(+) and H(+)) and conductimetry indicate that at 25 degrees C dissolved surfactant concentrations keep increasing well after dispersed particles are observed (2 mM). A cmc of about 4.5 mM, micelles of aggregation number n=70 and counterion binding parameter beta=0.7 are inferred from these techniques. The cmc of sodium myristate increases slightly with temperature from 25 to 45 degrees C. FTIR analysis of the filtered particles indicates that the dispersed particles are mainly acid soaps for concentrations less than 6 mM. With 10 mM NaOH, the particles observed above 2 mM consist mostly of sodium myristate. From both conductivity and IR data, the solubility of sodium myristate in water at 25 degrees C is estimated to be about 6 mM, and as expected, it increases with increasing temperature and decreases with increasing sodium ion concentration. Copyright 2000 Academic Press.

  20. Magnetic field effects on copper metal deposition from copper sulfate aqueous solution.

    Science.gov (United States)

    Udagawa, Chikako; Maeda, Aya; Katsuki, Akio; Maki, Syou; Morimoto, Shotaro; Tanimoto, Yoshifumi

    2014-05-01

    Effects of a magnetic field (≤0.5 T) on electroless copper metal deposition from the reaction of a copper sulfate aqueous solution and a zinc thin plate were examined in this study. In a zero field, a smooth copper thin film grew steadily on the plate. In a 0.38 T field, a smooth copper thin film deposited on a zinc plate within about 1 min. Then, it peeled off repeatedly from the plate. The yield of consumed copper ions increased about 2.1 times compared with that in a zero field. Mechanism of this magnetic field effect was discussed in terms of Lorentz force- and magnetic force-induced convection and local volta cell formation.

  1. Effect of heterogeneous catalysts on radiolysis of aqueous solutions of phenol

    International Nuclear Information System (INIS)

    Peculiarities of phenol aqueous solution radiolysis under conditions of continuous liquid flow through the layer of solid sorbent or various heterogeneous catalysts (MnO2, Pt, Ni, Ni-Pd), applied on activated carbons, are investigated. γ-radiation dose rate is 3 Gy/s, the dose is 0.36 kGy. Data on radiation-chemical yields of phenol destruction in the presence of sorbent and heterogeneous catalysts are presented. It is shown that during heterogeneous radiolysis of phenol in all the cases its more effective removal as compared with homogeneous one takes place; simultaneously, selective effect of the surface nature of the catalysts used on the mechanism of reactions and quantitative characteristics of the destruction process is observed

  2. Condensation of glycylglycine to oligoglycines with trimetaphosphate in aqueous solution. II: catalytic effect of magnesium ion.

    Science.gov (United States)

    Yamagata, Y; Inomata, K

    1997-08-01

    The previously reported condensation reaction of glycylglycine with trimetaphosphate (Yamanaka et al., 1988) was reinvestigated and shown to be catalyzed by magnesium ion. Aqueous solutions containing glycylglycine (0.5 M), trimetaphosphate (0.5 M) and magnesium chloride (0.5 M) were incubated at 38 degrees C at pH 4, 5, 6, 7 and 8. After incubation for ten days at pH 5, the maximum yields of tetraglycine and hexaglycine as condensation products were found to be about 12 and 1.4%, respectively. This result indicated the presence of a considerable catalytic effect of magnesium ion compared with the maximum yield of about 2% for tetraglycine and approximately 0% for hexaglycine in the absence of magnesium ion. PMID:11536827

  3. Ludwig-Soret effect of non-ionic surfactant aqueous solution studied by beam deflection method

    Science.gov (United States)

    Maeda, Kousaku; Kita, Rio; Shinyashiki, Naoki; Yagihara, Shin

    2013-02-01

    We have studied the thermal diffusion of non-ionic surfactant aqueous solutions by a beam deflection method. The thermal diffusion of pentaethylene glycol monododecyl ether (C12E5) and hexaethylene glycol monododecyl ether (C12E6) is studied in the concentration range of 1.0-99.0 wt% and in the temperature range of 20.0-35.0 °C. A stable temperature gradient is applied to the solution, where solute molecules shift to the cold side of the solution for lowconcentration samples. The concentration dependence of the Soret coefficient ST of the C12E6 aqueous solution shows a sign inversion behavior. At all concentrations, the developed concentration gradient is proportionally related to the applied temperature gradient. The results confirm that the magnitude of ST has no temperature gradient dependence under the studied experimental conditions.

  4. An effective colorimetric and ratiometric fluorescent probe for bisulfite in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xi [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Zhang, Tao [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Du, Zhi-Fang; Cao, Xiang-Jian; Chen, Ming-Yu [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Taishan College, Shandong University, Jinan 250100 (China); Hu, Sheng-Wen [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Miao, Jun-Ying, E-mail: miaojy@sdu.edu.cn [Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100 (China); Zhao, Bao-Xiang, E-mail: bxzhao@sdu.edu.cn [Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2015-08-12

    We have developed the first two-photon colorimetric and ratiometric fluorescent probe, BICO, for the detection of bisulfite (HSO{sub 3}{sup −}) in aqueous solution. The probe contains coumarin and benzimidazole moieties and can detect HSO{sub 3}{sup −} based on the Michael addition reaction with a limit of detection 5.3 × 10{sup −8} M in phosphate-buffered saline solution. The probe was used to detect bisulfite in tap water, sugar and dry white wine. Moreover, test strips were made and used easily. We successfully applied the probe to image living cells, using one-photon fluorescence imaging. BICO overcomes the limitations in sensitivity of previously reported probes and the solvation effect of bisulfite, which demonstrates its excellent value in practical application. - Highlights: • A colorimetric and ratiometric fluorescent probe was developed. • The probe could detect bisulfite in PBS buffer solution and real samples. • Bisulfite test paper was made to naked-eye detect bisulfite. • This probe successfully used to living cell imaging in ratiometric manner.

  5. Probing Ionic Liquid Aqueous Solutions Using Temperature of Maximum Density Isotope Effects

    Directory of Open Access Journals (Sweden)

    Mohammad Tariq

    2013-03-01

    Full Text Available This work is a new development of an extensive research program that is investigating for the first time shifts in the temperature of maximum density (TMD of aqueous solutions caused by ionic liquid solutes. In the present case we have compared the shifts caused by three ionic liquid solutes with a common cation—1-ethyl-3-methylimidazolium coupled with acetate, ethylsulfate and tetracyanoborate anions—in normal and deuterated water solutions. The observed differences are discussed in terms of the nature of the corresponding anion-water interactions.

  6. A new strategy to stabilize oxytocin in aqueous solutions: I. The effects of divalent metal ions and citrate buffer.

    Science.gov (United States)

    Avanti, Christina; Amorij, Jean-Pierre; Setyaningsih, Dewi; Hawe, Andrea; Jiskoot, Wim; Visser, Jan; Kedrov, Alexej; Driessen, Arnold J M; Hinrichs, Wouter L J; Frijlink, Henderik W

    2011-06-01

    In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. Both monovalent metal ions (Na(+) and K(+)) and divalent metal ions (Ca(2+), Mg(2+), and Zn(2+)) were tested all as chloride salts. The effect of combinations of buffers and metal ions on the stability of aqueous oxytocin solutions was determined by RP-HPLC and HP-SEC after 4 weeks of storage at either 4°C or 55°C. Addition of sodium or potassium ions to acetate- or citrate-buffered solutions did not increase stability, nor did the addition of divalent metal ions to acetate buffer. However, the stability of aqueous oxytocin in aqueous formulations was improved in the presence of 5 and 10 mM citrate buffer in combination with at least 2 mM CaCl(2), MgCl(2), or ZnCl(2) and depended on the divalent metal ion concentration. Isothermal titration calorimetric measurements were predictive for the stabilization effects observed during the stability study. Formulations in citrate buffer that had an improved stability displayed a strong interaction between oxytocin and Ca(2+), Mg(2+), or Zn(2+), while formulations in acetate buffer did not. In conclusion, our study shows that divalent metal ions in combination with citrate buffer strongly improved the stability of oxytocin in aqueous solutions.

  7. 2010 Water & Aqueous Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dor Ben-Amotz

    2010-08-13

    Water covers more than two thirds of the surface of the Earth and about the same fraction of water forms the total mass of a human body. Since the early days of our civilization water has also been in the focus of technological developments, starting from converting it to wine to more modern achievements. The meeting will focus on recent advances in experimental, theoretical, and computational understanding of the behavior of the most important and fascinating liquid in a variety of situations and applications. The emphasis will be less on water properties per se than on water as a medium in which fundamental dynamic and reactive processes take place. In the following sessions, speakers will discuss the latest breakthroughs in unraveling these processes at the molecular level: Water in Solutions; Water in Motion I and II; Water in Biology I and II; Water in the Environment I and II; Water in Confined Geometries and Water in Discussion (keynote lecture and poster winners presentations).

  8. The effect of magnesium ions on dielectric relaxation in semidilute DNA aqueous solutions

    CERN Document Server

    Grgičin, Danijel; Ivek, Tomislav; Tomić, Silvia; Podgornik, Rudi

    2013-01-01

    The effect of magnesium ion Mg2+ on the dielectric relaxation of semidilute DNA aqueous solutions has been studied by means of dielectric spectroscopy. Two dielectric relaxations in the 100 Hz - 100 MHz frequency range, originating in the motion of DNA counterions, were probed as a function of DNA and Mg2+ ion concentration in added MgCl2 salt. The high-frequency mode in the MHz range, stemming from the structural organization of the DNA network, reveals de Gennes-Pfeuty-Dobrynin correlation length as the pertinent fundamental length scale for sufficiently low concentration of added salt. No relaxation fingerprint of DNA denaturation bubbles, leading to exposed hydrophobic core scaling, was detected at low DNA concentrations, thus indicating an increased stability of the double-stranded conformation as compared to the case of DNA solutions with univalent counterions. The presence of Mg2+ does not change qualitatively the low frequency mode in the kHz range correlated with single DNA conformational properties....

  9. The effect of β-cyclodextrin in the photochemical stability of propranolol hydrochloride in aqueous solution

    Directory of Open Access Journals (Sweden)

    Tathiane Lilian Ansolin

    2014-04-01

    Full Text Available The degradation of propranolol hydrochloride (1-isopropylamino-3-(naphthoxy-2-propranolol in an aqueous solution was analyzed when irradiated by light UV, with and without β-cyclodextrin. There was an increase in the compound´s photostability in nanocavity when compared with the drug without the cyclodextrins’ cavity. First order kinetic model was employed for the degradation of propranolol in aqueous media and in cyclodextrins’ cavity. The kinetic parameter was obtained by the drug´s absorption and electronic fluorescence. As a rule, encapsulation of propranolol in β-cyclodextrin decreases photodegradation speed by 53%.

  10. Effects of dimethyl sulfoxide on the hydrogen bonding structure and dynamics of aqueous N-methylacetamide solution

    Indian Academy of Sciences (India)

    APRAMITA CHAND; SNEHASIS CHOWDHURI

    2016-06-01

    Effects of dimethyl-sulfoxide (DMSO) on the hydrogen bonding structure and dynamics in aqueousN-methylacetamide (NMA) solution are investigated by classical molecular dynamics simulations. Themodifications of structure and interaction between water and NMA in presence of DMSO molecules are calculatedby various site-site radial distribution functions and average interaction energies between these speciesin the solution. It is observed that the aqueous peptide hydrogen bond interaction is relatively stronger withincreasing concentration of DMSO, whereas methyl-methyl interaction between NMA and DMSO decreasessignificantly. The DMSO molecule prefers to interact with amide-hydrogen of NMA even at lower DMSO concentration.The lifetimes and structural-relaxation times of NMA-water, water-water and DMSO-water hydrogenbonds are found to increase with increasing DMSO concentration in the solution. The slower translationaland rotational dynamics of NMA is observed in concentrated DMSO solution due to formation of strongerinter-species hydrogen bonds in the solution.

  11. Irradiation effect on insecticides as a pollutant model in aqueous solution

    International Nuclear Information System (INIS)

    Degradation of some insecticides i.e.: fenitrothion, prothiofos, and cypermetrin as a model pollutant was carried out using gamma irradiation of 60Co. Irradiation-induced of fenitrothion in solution acid medium gave the significant effect on the decrease of its concentration. The optimum condition for degradation of fenitrothion (55.5 mg/L) was irradiation at 6 kGy with aeration in initial pH 5.6. At this condition, the concentration of fenitrothion decreased up to 97%. Determination of organic acids in irradiated product by HPLC method showed that oxalic acid and formic acid were clarified as organic acid-degraded products of fenitrothion with the concentration of 23.0 mg/L and 2.5 mg/L respectively. The irradiation of prothiofos in aqueous solution (50 mg/L), showed that irradiation at a dose of 8 kGy and initial pH 7 gave the optimum degradation. At this condition, the concentration of prothiofos decreased up to 98%. Determination of irradiated product by HPLC method showed that oxalic acid (18 mg/L) was clarified as organic acid-degraded product of prothiofos. In the case of cypermetrin, the optimum condition for its degradation was irradiation with aeration of cypermetrin (40 mg/L) at a dose of 20 kGy, initial pH 11, and adding the catalyst 0.05% of FeCl3. At that condition, cypermetrin decreased up to 87% and COD of solution decreased up to 78%. The organic acid detected at optimum condition as degradation products were oxalic acid (1.1 μg/L), maleic acid (9.0 μg/L), formic acid (127.0 μg/L), and acetic acid (286.0 μg/L). From these results, it could be concluded that ionizing radiation can be used as a tool to degrade insecticides as organic pollutants. (author)

  12. A new strategy to stabilize oxytocin in aqueous solutions : I. The effects of divalent metal ions and citrate buffer

    NARCIS (Netherlands)

    Avanti, Christina; Amorij, Jean-Pierre; Setyaningsih, Dewi; Hawe, Andrea; Jiskoot, Wim; Visser, Jan; Kedrov, Alexej; Driessen, Arnold J. M.; Hinrichs, Wouter L. J.; Frijlink, Henderik W.

    2011-01-01

    In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. Both monovalent metal ions (Na+and K+) and divalent metal ions (Ca2+, Mg2+, and Zn2+) were tested all as chloride salts. The effec

  13. [Effect of inorganic ions on degradation of trace nitrobenzene in aqueous solution by catalytic ozonation].

    Science.gov (United States)

    Zhao, Lei; Ma, Jun; Sun, Zhi-zhong

    2006-05-01

    The experiment investigated the effects of general inorganic ions in natural source water on the three processes of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation for degradation of trace nitrobenzene in aqueous solution. The removal rate of ozonation alone and modified ceramic honeycomb-catalyzed ozonation increased by 5.0% and 8.6% with the increase of the concentration of calcium ion (0-4 mg x L(-1)), and that of ceramic honeycomb-catalyzed ozonation reached the climax at the concentration of calcium ion 0.5 mg x L(-1) under the same experimental condition. The degradation efficiency of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation enhanced by 10.9%, 11.6% and 9.6% with the increase of the concentration of manganese ion (0-4 mg x L(-1)), respectively, and decreased by 8.6%, 11.5% and 8.9% with the increase of the concentration of bicarbonate ion (0-200 mg x L(-1)). The concentration of nitrate and sulfate ion had no remarkable effect on ozonation alone, but the removal rate of other two processes decreased with the increase of the concentration of nitrate and sulfate ion.

  14. Effects and mechanism of ozonation for degradation of sodium acetate in aqueous solution

    Directory of Open Access Journals (Sweden)

    De-min YANG

    2012-06-01

    Full Text Available The degradation efficiencies and mechanism of ozonation for the degradation of sodium acetate in aqueous solution were investigated under atmospheric pressure at room temperature (293 K. The effects of the initial pH value, reaction time, and concentrations of, , CaCl2, and Ca(OH2 on the removal rate of chemical oxygen demand (COD were studied. The results indicated that ozonation obviously improved the degradation rate of sodium acetate when the pH value of the solution was not less than 8.5. A suitable long reaction time may be helpful in increasing the COD removal rate, and a removal rate of 36.36% can be obtained after a 30-minute treatment. The COD removal rate increased firstly and decreased subsequently with the increase of the concentration (from 0 to 200 mg/L, and under the same experimental condition it reached the optimum 34.66% at the concentration of 100 mg/L. The COD removal rate was 5.26% lower when the concentration of was 200 mg/L than when there was no . The COD removal rate decreased by 15.68% when the concentration increased from 0 to 200 mg/L. has a more obvious scavenging effect in inhibiting the formation of hydroxyl radicals than . CaCl2 and Ca(OH2 could increase the degradation efficiency of sodium acetate greatly, and the COD removal rates reached 65.73% and 83.46%, respectively, after a 30-minute treatment, 29.37% and 47.10% higher, respectively, than with single ozone oxidation. It was proved that the degradation of sodium acetate in the ozonation process followed the mechanism of oxidization with hydroxyl free radicals (·OH.

  15. Production of perhydroxy radical (HO2) and oxygen in the radiolysis of aqueous solution and the LET effects

    International Nuclear Information System (INIS)

    This article aims to review the results concerning the production of perhydroxy radical (HO2) and oxygen from irradiated aqueous solutions and the LET effects on these products, beginning with a brief introduction to the elementary primary processes in radiolysis of aqueous solution. Oxygen, if produced in the radiolysis of aqueous solution, may be considered responsible for the decreased oxygen enhancement ratio (OER) in biological systems exposed to high LET radiation. A Harwell's group has determined oxygen generated from aqueous ferrous solutions irradiated with heavy ions and concluded that the oxygen is a precursor of perhydroxy radicals. The LET-dependent yields for perhydroxy radical have been determined by LaVerne and Schuler; the analysis of their results sheds light into the reactions taking place in high-LET track cores. In conjunction with these results, the possible contributions to the LET effects are pointed out and discussed of the energetic secondary electrons ejected from the track core by knock-on collision with heavy ions and of the variation in the track core size with energy of the heavy particles. (author)

  16. Efficiency Effectiveness of Photochemical and Sonochemical Processes Combined with Hydrogen Peroxide in Degradation of Basic Violet 16 (BV16 from Aqueous Solutions: A Kinetic Study

    Directory of Open Access Journals (Sweden)

    Majid Kermani

    2013-05-01

    Conclusion: The results showed that UV/H2O2 and US/H2O2 processes can be effective in the removal of BV16 from aqueous solutions. Considering dye removal efficiency and availability, photochemical process combined with hydrogen peroxide can be recommended as a fast effective method for removal of dyes from aqueous solutions.

  17. New insights into bioprotective effectiveness of disaccharides: an FTIR study of human haemoglobin aqueous solutions exposed to static magnetic fields

    OpenAIRE

    Magazù, Salvatore; Calabrò, Emanuele; Campo, Salvatore; Interdonato, Salvatore

    2011-01-01

    The aim of this study was the investigation of static magnetic field effects on haemoglobin secondary structure and the bioprotective effectiveness of two disaccharides, sucrose and trehalose. Samples of haemoglobin aqueous solutions, in the absence and in the presence of sucrose and trehalose, were exposed to a uniform magnetic field at 200 mT, which is the exposure limit established by the ICNIRP recommendation for occupational exposure. Spectral analysis by FTIR spectroscopy after 3 and 7 ...

  18. Chemical effects associated to (n, γ) nuclear reactions in diluted aqueous solutions of liquid or frozen organic halogenides

    International Nuclear Information System (INIS)

    Chemical effects associated to nuclear transformation 37Cl (n, γ) 38Cl or 127I (n, γ) 128I in solid or liquid aqueous solutions of ethyl iodide, trichloro-ethylene, thyroxine or DDT irradiated in a nuclear reactor are studied. The retention of radiohalogen under its initial chemical shape decrease with solute concentration in liquid phase but is almost constant with solute dilution in the solid phase. Potential applications in neutron activation analysis evidencing halogenated molecules in irradiated media are discussed. 57 refs

  19. Investigation of the effect of the uranyl ion on proton-spin-relaxation times in aqueous solutions

    International Nuclear Information System (INIS)

    The purpose of this project was to determine the effect of the uranyl ion on the spin-lattice relaxation time of protons in aqueous solutions. A flowmeter using nuclear magnetic resonance (NMR) techniques is being designed for monitoring the flow rate of aqueous solutions which are acidic, contain plutonium and uranium ions, chemical waste, and radioactive waste materials. The spin-lattice relaxation time is critical to the design of a flowmeter using nuclear magnetic resonance techniques. Experimental studies showed that spin-lattice relaxation time did not change for different molar concentrations of sample solutions of uranyl nitrate and uranyl acetate prepared from pure laboratory chemicals dissolved in distilled water. Therefore, it was concluded that the uranyl ion does not contribute to the relaxation process for protons in water

  20. Effective Biosorption of Nickel(II) from Aqueous Solutions Using Trichoderma viride

    OpenAIRE

    B. Naresh Kumar; Kalarani, V.; P.SUJATHA

    2013-01-01

    The primary objective of the present study is to evaluate the optimization conditions such as kinetic and equilibrium isotherm models involved in the removal of Ni(II) from the aqueous solutions by Trichoderma viride. The biosorbent was characterized by FTIR and SEM. The optimum biosorption conditions were determined as a function of pH, biomass dosage, contact time, initial metal ion concentration, and temperature. The maximum Ni(II) biosorption was obtained at pH 4.5. The equilibrium data w...

  1. Temperature effect on adiolysis of deaerated acid aqueous solutions of ferrous sulfate

    International Nuclear Information System (INIS)

    In the course of γ-radiolysis (60Co, dose rate=3.75 Gr/c, doses=1.575-3.375 kGr) of deaerated acid aqueous solution 3.6x10-3 mol/l of ferrous sulfate in the 20-250 deg C range the hydrogen molecules radiochemical yield per 100 eV of absorbed energy G(H2) decreases from 3.82±0.12 to 2.72±0.26, whereas G(Fe3+) independently of temperature is equal 8.34±0.36

  2. [Effect of organic compounds on the degradation of nitrobenzene in aqueous solution by catalytic ozonation].

    Science.gov (United States)

    Zhao, Lei; Ma, Jun; Liu, Zheng-Qian; Sun, Zhi-Zhong; Hou, Yan-Jun

    2008-05-01

    We investigated the effects of organic compounds on the processes of ozonation alone and ceramic honeycomb-catalyzed ozonation for the degradation of nitrobenzene in aqueous solution, including formaldehyde, methanol, formic acid and dibutyl phthalate. The results indicated that degradation rate of ozonation alone and ceramic honeycomb-catalyzed ozonation decreased by 11.6% and 9.6% with the increase of the concentration of formaldehyde (0-12 mg x L(-1)). The degradation rates of the two processes both increased firstly and decreased subsequently with the increase of the concentration of methanol (0-16 mg x L(-1)). The degradation rate of ozonation alone reached the climax at the concentration of methanol 2 mg x L(-1), and that of ceramic honeycomb-catalyzed ozonation reached the culmination at the concentration of methanol 4 mg x L(-1) under the same experimental condition. With the increase of the concentration of formic acid (0-8 mg x L(-1)), the degradation rates also increased firstly and decreased subsequently, and those of ozonation alone and ceramic honeycomb-catalyzed ozonation reached the vertex, respectively, at the concentration of methanol 0.5 mg x L(-1) and 2 mg x L(-1). At the lower concentration, methanol and formic acid could accelerate the degradation of nitrobenzene, however, the reaction was retarded at higher concentrations of methanol and formic acid. The degradation rates of ozonation alone and ozonation/ceramic honeycomb both declined by 19.7% and 18.6% with the increase of the concentration of dibutyl phthalate (0-10 mg x L(-1)).

  3. Adsorption of dimethyl sulfide from aqueous solution by a cost-effective bamboo charcoal.

    Science.gov (United States)

    Wang, Ming; Huang, Zheng-Hong; Liu, Guangjia; Kang, Feiyu

    2011-06-15

    The adsorption of dimethyl sulfide from an aqueous solution by a cost-effective bamboo charcoal from Dendrocalamus was studied in comparison with other carbon adsorbents. The bamboo charcoal exhibited superior adsorption on dimethyl sulfide compared with powdered activated carbons at different adsorbent dosages. The adsorption characteristics of dimethyl sulfide onto bamboo charcoal were investigated under varying experimental conditions such as particle size, contact time, initial concentration and adsorbent dosage. The dimethyl sulfide removal was enhanced from 31 to 63% as the particle size was decreased from 24-40 to >300 mesh for the bamboo charcoal. The removal efficiency increased with increasing the adsorbent dosage from 0.5 to 10mg, and reached 70% removal efficiency at 10mg adsorbed. The adsorption capacity (μg/g) increased with increasing concentration of dimethyl sulfide while the removal efficiency decreased. The adsorption process conforms well to a pseudo-second-order kinetics model. The adsorption of dimethyl sulfide is more appropriately described by the Freundlich isotherm (R(2), 0.9926) than by the Langmuir isotherm (R(2), 0.8685). Bamboo charcoal was characterized by various analytical methods to understand the adsorption mechanism. Bamboo charcoal is abundant in acidic and alcohol functional groups normally not observed in PAC. A distinct difference is that the superior mineral composition of Fe (0.4 wt%) and Mn (0.6 wt%) was detected in bamboo charcoal-elements not found in PAC. Acidic functional group and specific adsorption sites would be responsible for the strong adsorption of dimethyl sulfide onto bamboo charcoal of Dendrocalamus origin. PMID:21549503

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

    Science.gov (United States)

    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

  5. Effective removal of cationic dyes from aqueous solution using gum ghatti-based biodegradable hydrogel.

    Science.gov (United States)

    Mittal, Hemant; Maity, Arjun; Ray, Suprakas Sinha

    2015-08-01

    Biodegradable hydrogels of gum ghatti (Gg) with a co-polymer mixture of acrylamide (AAm) and methacrylic acid (MAA) (termed as Gg-cl-P(AAm-co-MAA)) were synthesised by microwave-assisted free radical graft co-polymerisation technique. The hydrogel polymer was characterized by FTIR, SEM, and Brunauer-Emmett-Teller techniques. The Gg-cl-P(AAm-co-MAA) hydrogel was studied as an adsorbent for the removal of methylene blue (MB) and methyl violet (MV) from aqueous solutions. Adsorption of both the dyes followed pseudo-second-order kinetics and Langmuir adsorption isotherm models. The hydrogel polymer adsorbed 98% of MB and 95% of MV from aqueous solution. The Gg-cl-P(AAm-co-MAA) maintained its original sorption capacity for three cycles of adsorption-desorption. Furthermore, the hydrogel polymer degraded fully within 50 days in soil compost. In summary, the Gg-cl-P(AAm-co-MAA) hydrogel could be a potential adsorbent for the remediation of dyes from industrial wastewater. PMID:25934107

  6. The ion-selective field-effect transistor application for enzyme analysis of toxic admixtures in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Pavluchenko A. S.

    2010-06-01

    Full Text Available The article describes design and production technology of pH-sensors based on ion-selective field-effect transis-tors (ISFET intended for enzyme analysis of inhibiting admixtures in aqueous solutions, and architecture of the multichannel measuring system built upon the ISFET-sensors. The characteristics of developed prototypes are given and the ways for further improvement of system design, metrological performance and operating parameters are outlined.

  7. Removal of Dimethyl Sulfide from Aqueous Solution Using Cost-Effective Modified Chicken Manure Biochar Produced from Slow Pyrolysis

    OpenAIRE

    Minh-Viet Nguyen; Byeong-Kyu Lee

    2015-01-01

    This study investigated the characteristics of using a cost-effective, amine-modified biochar (BC) derived from chicken manure for removing dimethyl sulfide (DMS) from an aqueous solution. The amine-modified BC showed much higher adsorption of DMS compared to commercial activated carbons under varying conditions of contact time, initial concentration, and adsorbent dosage. The DMS removal efficiency increased as the adsorbent dosage was increased from 0.01 to 0.25 g and reached 92.4% even at...

  8. Redox levels in aqueous solution: Effect of van der Waals interactions and hybrid functionals

    Science.gov (United States)

    Ambrosio, Francesco; Miceli, Giacomo; Pasquarello, Alfredo

    2015-12-01

    We investigate redox levels in aqueous solution using a combination of ab initio molecular dynamics (MD) simulations and thermodynamic integration methods. The molecular dynamics are performed with both the semilocal Perdew-Burke-Ernzerhof functional and a nonlocal functional (rVV10) accounting for van der Waals (vdW) interactions. The band edges are determined through three different schemes, namely, from the energy of the highest occupied and of the lowest unoccupied Kohn-Sham states, from total-energy differences, and from a linear extrapolation of the density of states. It is shown that the latter does not depend on the system size while the former two are subject to significant finite-size effects. For the redox levels, we provide a formulation in analogy to the definition of charge transition levels for defects in crystalline materials. We consider the H+/H2 level defining the standard hydrogen electrode, the OH-/OH∗ level corresponding to the oxidation of the hydroxyl ion, and the H2O/OH∗ level for the dehydrogenation of water. In spite of the large structural modifications induced in liquid water, vdW interactions do not lead to any significant structural effect on the calculated band gap and band edges. The effect on the redox levels is also small since the solvation properties of ionic species are little affected by vdW interactions. Since the electronic properties are not significantly affected by the underlying structural properties, it is justified to perform hybrid functional calculations on the configurations of our MD simulations. The redox levels calculated as a function of the fraction α of Fock exchange are found to remain constant, reproducing a general behavior previously observed for charge transition levels of defects. Comparison with experimental values shows very good agreement. At variance, the band edges and the band gap evolve linearly with α. For α ≃ 0.40, we achieve a band gap, band-edge positions, and redox levels in overall

  9. Redox levels in aqueous solution: Effect of van der Waals interactions and hybrid functionals

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosio, Francesco, E-mail: Francesco.Ambrosio@epfl.ch; Miceli, Giacomo; Pasquarello, Alfredo [Chaire de Simulation à l’Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2015-12-28

    We investigate redox levels in aqueous solution using a combination of ab initio molecular dynamics (MD) simulations and thermodynamic integration methods. The molecular dynamics are performed with both the semilocal Perdew-Burke-Ernzerhof functional and a nonlocal functional (rVV10) accounting for van der Waals (vdW) interactions. The band edges are determined through three different schemes, namely, from the energy of the highest occupied and of the lowest unoccupied Kohn-Sham states, from total-energy differences, and from a linear extrapolation of the density of states. It is shown that the latter does not depend on the system size while the former two are subject to significant finite-size effects. For the redox levels, we provide a formulation in analogy to the definition of charge transition levels for defects in crystalline materials. We consider the H{sup +}/H{sub 2} level defining the standard hydrogen electrode, the OH{sup −}/OH{sup ∗} level corresponding to the oxidation of the hydroxyl ion, and the H{sub 2}O/OH{sup ∗} level for the dehydrogenation of water. In spite of the large structural modifications induced in liquid water, vdW interactions do not lead to any significant structural effect on the calculated band gap and band edges. The effect on the redox levels is also small since the solvation properties of ionic species are little affected by vdW interactions. Since the electronic properties are not significantly affected by the underlying structural properties, it is justified to perform hybrid functional calculations on the configurations of our MD simulations. The redox levels calculated as a function of the fraction α of Fock exchange are found to remain constant, reproducing a general behavior previously observed for charge transition levels of defects. Comparison with experimental values shows very good agreement. At variance, the band edges and the band gap evolve linearly with α. For α ≃ 0.40, we achieve a band gap, band

  10. Redox levels in aqueous solution: Effect of van der Waals interactions and hybrid functionals

    International Nuclear Information System (INIS)

    We investigate redox levels in aqueous solution using a combination of ab initio molecular dynamics (MD) simulations and thermodynamic integration methods. The molecular dynamics are performed with both the semilocal Perdew-Burke-Ernzerhof functional and a nonlocal functional (rVV10) accounting for van der Waals (vdW) interactions. The band edges are determined through three different schemes, namely, from the energy of the highest occupied and of the lowest unoccupied Kohn-Sham states, from total-energy differences, and from a linear extrapolation of the density of states. It is shown that the latter does not depend on the system size while the former two are subject to significant finite-size effects. For the redox levels, we provide a formulation in analogy to the definition of charge transition levels for defects in crystalline materials. We consider the H+/H2 level defining the standard hydrogen electrode, the OH−/OH∗ level corresponding to the oxidation of the hydroxyl ion, and the H2O/OH∗ level for the dehydrogenation of water. In spite of the large structural modifications induced in liquid water, vdW interactions do not lead to any significant structural effect on the calculated band gap and band edges. The effect on the redox levels is also small since the solvation properties of ionic species are little affected by vdW interactions. Since the electronic properties are not significantly affected by the underlying structural properties, it is justified to perform hybrid functional calculations on the configurations of our MD simulations. The redox levels calculated as a function of the fraction α of Fock exchange are found to remain constant, reproducing a general behavior previously observed for charge transition levels of defects. Comparison with experimental values shows very good agreement. At variance, the band edges and the band gap evolve linearly with α. For α ≃ 0.40, we achieve a band gap, band-edge positions, and redox levels in

  11. DEHYDRATION CONDENSATION IN AQUEOUS SOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Steinman, Gary; Kenyon, Dean H.; Calvin, Melvin

    1965-04-01

    EARLIER investigations have demonstrated that di-cyandiamide (DCDA), the dimer of cyanamide, can successfully promote the dehydration condensation of: (1) glucose and orthophosphate to give glucose-6-phosphate; (2) adenosine and orthophosphate to give adenosine-5'-monophosphate; (3) orthophosphate to give pyrophosphate; (4) alanine to give alanylalanine and alanylalanylalanine. These reactions were carried out in dilute aqueous solutions in the dark. (It was also demonstrated that the combination of ultra-violet light and dicyandiamide could promote the synthesis of dipeptides. This observation has since been confirmed by other investigators.) These experiments were designed to demonstrate one possible means by which such compounds could have been formed on the prebiotic Earth, thus providing materials needed for the origin of living systems. Dicyandiamide itself could have been, present on the primitive Earth as was demonstrated with the ultra-violet irradiation of cyanide solution.

  12. Radiolysis of Aqueous Benzene Solutions

    International Nuclear Information System (INIS)

    Aerated and deaerated aqueous solutions of benzene have been irradiated with 60Co γ-rays. The products of radiolysis in deaerated, unbuffered or acid, solutions were phenol, biphenyl, hydrogen and in acid solutions also hydrogen peroxide with the following yields: G(phenol) = 0. 37 (0. 37), G(biphenyl) = 1.3 (1.7), G(H2) = 0.44 (0. 43) and G(H2O2) = 0 (0.60), the figures in brackets giving the results for acid solutions. The results are shown to agree with the conclusion that k(e-aq + H2O2) >> k(H + H2O2). Furthermore, the results indicate that a competition takes place between the reactions: 2 C6H6OH · -> dimer -> biphenyl. C6H7 · + C6H6OH · -> dimer -> biphenyl. The yields in aerated, unbuffered or acid, solutions were: G(phenol) = 2.1 (2.3), G(biphenyl) = 0 (0), and G(H2O2) = 2.2 (3.1), the figures in brackets being valid for acid solutions. The ratio k(H + C6H6)/k(H + O2) was 1.4x10-2. The results indicate that peroxides, or more probably hydroperoxides, take part in the reactions. After the addition of Fe2+ or Fe3+ to aerated acid solutions G(phenol) was increased to 6.6 and 3.4 respectively. Oxygen was consumed more rapidly in the presence of Fe. Reaction mechanisms are discussed

  13. Effect of polymer matrix on structure of Se particles formed in aqueous solutions during redox process

    Energy Technology Data Exchange (ETDEWEB)

    Suvorova, E. I., E-mail: suvorova@ns.crys.ras.ru; Klechkovskaya, V. V. [Shubnikov Institute of Crystallography of Russian Academy of Sciences (Russian Federation)

    2010-12-15

    Transmission electron microscopy and X-ray energy dispersive microanalysis study of the structure of particles formed during the reduction of Se(IV) to Se(0) in aqueous solutions in the presence of amphiphilic polymers showed the formation of Se/polymer composite particles. The content of carbon inside the particles can be as large as 80 at %. Polymers deeply influence the structure of particles. Depending on polymers, the composite particles may be unstable with time and they spontaneously evolve from Se/polymer composite particles to crystalline particles of monoclinic Se. For the stable ones, addition of bacterial cellulose Acetobacter xylinum gel-film can induce crystallization in the particles which expel the polymeric material. The Se/polymer composite particles and Se crystalline particles exhibit different sensitivity to electron irradiation and stiffness.

  14. Rheological Properties of Associative Star Polymers in Aqueous Solutions: Effect of Hydrophobe Length and Polymer Topology

    DEFF Research Database (Denmark)

    Hietala, Sami; Strandman, Satu; Jarvi, Paula;

    2009-01-01

    Rheological properties of aqueous solutions of well-defined four-armed amphiphilic star block copolymers, poly(acrylic acid)-block-polystyrene (PAA-b-PS)(4), were investigated as a function of the length of the PS blocks, polymer concentration, and temperature and compared with a corresponding...... triblock copolymer. These polymers, synthesized by atom transfer radical polymerization (ATRP), were found to form hydrogels due to intermolecular association originating from the PS blocks. The increasing length of the PS block was observed to lead to more elastic networks due to increased hydrophobic...... interaction. Polymers bearing shorter PS blocks gave gels with relatively long linear response followed by strain hardening before shear thinning while the longer PS blocks lead to formation of elastic but brittle gels with limited linear regime before shear thinning. Star-block copolymers showed more elastic...

  15. Gum karaya based hydrogel nanocomposites for the effective removal of cationic dyes from aqueous solutions

    Science.gov (United States)

    Mittal, Hemant; Maity, Arjun; Ray, Suprakas Sinha

    2016-02-01

    Biodegradable hydrogel nanocomposites (HNC) of gum karaya (GK) grafted with poly(acrylic acid) (PAA) incorporated silicon carbide nanoparticles (SiC NPs) were synthesized using the in situ graft copolymerization method and tested for the adsorption of cationic dyes from aqueous solution. The structure and morphology of the HNC were characterized using different spectroscopic and microscopic techniques. The results showed that the surface area and porosity of the hydrogel polymer significantly increased after nanocomposite formation with SiC NPs. The HNC was employed for the removal of cationic dyes, i.e., malachite green (MG) and rhodamine B (RhB) from the aqueous solution. The HNC was found to remove 91% (MG) and 86% (RhB) of dyes with a polymer dose of 0.5 and 0.6 g l-1 in neutral medium, respectively. The adsorption process was found to be highly pH dependent and followed the pseudo-second-order rate model. The adsorption isotherm data fitted well with the Langmuir adsorption isotherm with a maximum adsorption capacity of 757.57 and 497.51 mg g-1 for MG and RhB, respectively. Furthermore, the HNC was demonstrated as a versatile adsorbent for the removal of both cationic and anionic dyes from the simulated wastewater. The HNC showed excellent regeneration capacity and was successfully used for the three cycles of adsorption-desorption. In summary, the HNC has shown its potential as an environment friendly and efficient adsorbent for the adsorption of cationic dyes from contaminated water.

  16. Thermo photo-electrochemical effect in n-InP/aqueous solution of orange dye/C cell

    Science.gov (United States)

    Ali, Taimoor; Karimov, Khasan S.; Akhmedov, Khakim M.; Kabutov, K.; Farooq, Amjad

    2015-03-01

    The effect of light and heat is studied on the electrical properties of an electrochemical n-InP/aqueous solution of orange dye/C cell. The cell is investigated under the light and heat of filament bulb. The n-type indium phosphide and carbon plates are used as electrodes. The aqueous solution of organic material orange dye (C17H17N5O2) in distilled water is served as electrolyte at 1, 3 and 5 wt. % concentration. The cell is assembled in sealed organic glass box with dimensions 35 × 13 × 14 mm. The open circuit voltage ( V oc ) and short circuit current ( I sc ) of the cell are observed by illuminating and heating the samples. The temperature is raised up to 60°C from 25°C when light intensity is increased from dark condition to 425 W/m2. It is observed that the relationship between light intensity and temperature is approximately linear for all cases. The V oc and I sc increase 100% and 300% respectively by increasing the light. The reported n-InP/aqueous solution of orange dye/C cell can be considered as small converter of light and heat into electric power. [Figure not available: see fulltext.

  17. NOTE: The effects of paramagnetic contrast agents on metabolite protons in aqueous solution

    Science.gov (United States)

    Murphy, Philip S.; Leach, Martin O.; Rowland, Ian J.

    2002-03-01

    The longitudinal (R1) and transverse (R2) relaxivities of the clinically used contrast agents Gd(DTPA)2-, Gd(DOTA)- and Gd(DTPA-BMA) have been determined in mixed aqueous metabolite solutions for choline, creatine and N-acetylaspartate. Measurements were performed at 1.5 T using a STEAM sequence on 25 mM metabolite solutions at pH = 7.4 and 22 °C. The data showed that for all the contrast agents and metabolites, R1 ~ R2. The largest range of relaxivity values was found for Gd(DTPA)2-, where R2 = 6.8 +/- 0.3 mM-1 s-1 for choline and 1.5 +/- 0.4 mM-1 s-1 for N-acetylaspartate. Variation in relaxivity values was attributed primarily to differences between the charges of the paramagnetic agent and metabolite. The maximum potential influence of the contrast agents on in vivo metabolite signals was calculated using the measured relaxivities.

  18. Effect of 20 % EDTA Aqueous Solution on Defective Tubes (Alloy600) in High Temperature Chemical Cleaning Environments

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyuk Chul [KHNP-CRI, Daejeon (Korea, Republic of)

    2016-04-15

    The transport and deposition of corrosion products in pressurized water nuclear reactor (PWR) steam generators have led to corrosion (SCC, denting etc.) problems. Lancing, mechanical cleaning and chemical cleaning have been used to reduce these problems. The methods of lancing and mechanical cleaning have limitations in removing corrosion products due to the structure of steam generator tubes. But high temperature chemical cleaning (HTCC) with EDTA is the most effective method to remove corrosion products regardless of the structure. However, EDTA in chemical cleaning aqueous solution and chemical cleaning environments affects the integrity of materials used in steam generators. The nuclear power plants have to perform the pre-test (also called as qualification test (QT)) that confirms the effect on the integrity of materials after HTCC. This is one of the series studies that assess the effect, and this study determines the effects of 20 % EDTA aqueous solution on defective tubes in high temperature chemical cleaning environments. The depth and magnitude of defects in steam generator (SG) tubes were measured by eddy current test (ECT) signals. Surface analysis and magnitude of defects were performed by using SEM/EDS. Corrosion rate was assessed by weight loss of specimens. The ECT signals (potential and depth %) of defective tubes increased marginally. But the lengths of defects, oxides on the surface and weights of specimens did not change. The average corrosion rate of standard corrosion specimens was negligible. But the surfaces on specimens showed traces of etching. The depth of etching showed a range on the nanometer. After comprehensive evaluation of all the results, it is concluded that 20 % EDTA aqueous solution in high temperature chemical cleaning environments does not have a negative effect on defective tubes.

  19. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO2F2. Studies on the effect of added LiNO3 or Na2WO4·2H2O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF6 content of WF6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF6

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

    Science.gov (United States)

    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

  1. Acetic acid extraction from aqueous solutions using fatty acids

    NARCIS (Netherlands)

    IJmker, H.M.; Gramblicka, M.; Kersten, S.R.A.; Ham, van der A.G.J.; Schuur, B.

    2014-01-01

    A major challenge for production of acetic acid via bio-based routes is cost-effective concentration and purification of the acetic acid from the aqueous solutions, for which liquid–liquid extraction is a possible method. A main challenge in extraction of acetic acid from dilute aqueous solutions is

  2. The Effect of Phosphorus and Nitrogen Biofertilizers inoculation on the oily Sunflower to Adsorption of Pb (II from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Temer S Ahmadi Meisam Rahmatifard Zeinab Ghasemi Ahmad Seif Ali Goodarzi

    2012-08-01

    Full Text Available The effect of phosphorus and nitrogen biofertilizers inoculation on oily sunflower (var: iroflor was studied for adsorption of Pb (II from aqueous solutions. We used different types of phosphorus and nitrogen solubilizing bacteria as biological fertilizers. After inoculation of treated samples, we observed that the maximum adsorption was obtained by blank treatment in cases where no fertilizer was added to it (a4b4. So iroflor was applied as a biosorbent for Pb (II adsorption. The effects of varying parameters such as: temperature, initial metal concentration, pH, and contact time on the adsorption process were determined. Adsorption equilibrium was established in 120 min and the maximum adsorption of Pb (II on the biosorbent was observed to occur at a pH of 8.0. The Langmuir isotherm showed the best fit to the equilibrium data. The equilibrium parameter, RL, indicated that this biosorbent is useful for Pb removal from aqueous solutions. The thermodynamic parameters were calculated which showed an exothermic adsorption process.

  3. Effect of freezing and thawing rates on denaturation of proteins in aqueous solutions.

    Science.gov (United States)

    Cao, Enhong; Chen, Yahuei; Cui, Zhanfeng; Foster, Peter R

    2003-06-20

    The freeze denaturation of model proteins, LDH, ADH, and catalase, was investigated in absence of cryoprotectants using a microcryostage under well-controlled freezing and thawing rates. Most of the experimental data were obtained from a study using a dilute solution with an enzyme concentration of 0.025 g/l. The dependence of activity recovery of proteins on the freezing and thawing rates showed a reciprocal and independent effect, that is, slow freezing (at a freezing rate about 1 degrees C/min) and fast thawing (at a thawing rate >10 degrees C/min) produced higher activity recovery, whereas fast freezing with slow thawing resulted in more severe damage to proteins. With minimizing the freezing concentration and pH change of buffer solution by using a potassium phosphate buffer, this phenomenon could be ascribed to surface-induced denaturation during freezing and thawing process. Upon the fast freezing (e.g., when the freezing rate >20 degrees C/min), small ice crystals and a relatively large surface area of ice-liquid interface are formed, which increases the exposure of protein molecules to the ice-liquid interface and hence increases the damage to the proteins. During thawing, additional damage to proteins is caused by recrystallization process. Recrystallization exerts additional interfacial tension or shear on the entrapped proteins and hence causes additional damage to the latter. When buffer solutes participated during freezing, the activity recovery of proteins after freezing and thawing decreased due to the change of buffer solution pH during freezing. However, the patterns of the dependence on freezing and thawing rates of activity recovery did not change except for that at extreme low freezing rates (solutions could be reduced by changing the buffer type and composition and by optimizing the freezing-thawing protocol.

  4. Structural organization of cetyltrimethylammonium sulfate in aqueous solution: The effect of Na2SO4.

    Science.gov (United States)

    Feitosa, Eloi; Brazolin, Marcelo Rodrigo Savério; Naal, Rose Mary Zumstein Georgetto; Del Lama, Maria Perpétua Freire de Morais; Lopes, Josias R; Loh, Watson; Vasilescu, Marilena

    2006-07-15

    We used dynamic light scattering (DLS), steady-state fluorescence, time resolved fluorescence quenching (TRFQ), tensiometry, conductimetry, and isothermal titration calorimetry (ITC) to investigate the self-assembly of the cationic surfactant cetyltrimethylammonium sulfate (CTAS) in aqueous solution, which has SO(2-)4 as divalent counterion. We obtained the critical micelle concentration (cmc), aggregation number (N(agg)), area per monomer (a0), hydrodynamic radius (R(H)), and degree of counterion dissociation (alpha) of CTAS micelles in the absence and presence of up to 1 M Na2SO4 and at temperatures of 25 and 40 degrees C. Between 0.01 and 0.3 M salt the hydrodynamic radius of CTAS micelle R(H) approximately 16 A is roughly independent on Na2SO4 concentration; below and above this concentration range R(H) increases steeply with the salt concentration, indicating micelle structure transition, from spherical to rod-like structures. R(H) increases only slightly as temperature increases from 25 to 40 degrees C, and the cmc decreases initially very steeply with Na2SO4 concentration up to about 10 mM, and thereafter it is constant. The area per surfactant at the water/air interface, a0, initially increases steeply with Na2SO4 concentration, and then decreases above ca. 10 mM. Conductimetry gives alpha = 0.18 for the degree of counterion dissociation, and N(agg) obtained by fluorescence methods increases with surfactant concentration but it is roughly independent of up to 80 mM salt. The ITC data yield cmc of 0.22 mM in water, and the calculated enthalpy change of micelle formation, Delta H(mic) = 3.8 kJ mol(-1), Gibbs free energy of micellization of surfactant molecules, Delta G(mic) = -38.0 kJ mol(-1) and entropy TDelta S(mic) = 41.7 kJ mol(-1) indicate that the formation of CTAS micelles is entropy-driven.

  5. Diketopiperazine-mediated peptide formation in aqueous solution II. Catalytic effect of phosphate

    Science.gov (United States)

    Takaoka, O.; Yamagata, Y.; Inomata, K.

    1991-05-01

    The previous paper (I) reported that DKP (glycine anhydride) spontaneously reacts with glycine (Gly) or oligoglycines (Gly n ) to produce longer oligoglycines (Gly n+2). This paper presents that phosphate catalyzes the condensation reaction quite effectively. Formation of Gly4 from DKP (0.1 M) and Gly2 (0.1 M) in phosphate solution of various concentrations was investigated at a neutral pH at 41 °C. The yields of Gly4 increased almost linearly with the concentration of phosphate from 0.06 M to 0.24 M. The yield in 0.24 M phosphate solution was approximately one hundred times as high as that in the absence of the phosphate, whereas in the case of Gly3 formation from DKP and Gly the effect of the phosphate was of ten times lower than in the former case. Orthophosphate was the most effective catalyst among the various kind of chemicals tried in the present investigation including polyphosphates.

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

    Science.gov (United States)

    Set, Seng; Ford, David; Kita, Masakazu

    2015-01-01

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

  7. Aqueous Solution Vessel Thermal Model Development II

    Energy Technology Data Exchange (ETDEWEB)

    Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-28

    The work presented in this report is a continuation of the work described in the May 2015 report, “Aqueous Solution Vessel Thermal Model Development”. This computational fluid dynamics (CFD) model aims to predict the temperature and bubble volume fraction in an aqueous solution of uranium. These values affect the reactivity of the fissile solution, so it is important to be able to calculate them and determine their effects on the reaction. Part A of this report describes some of the parameter comparisons performed on the CFD model using Fluent. Part B describes the coupling of the Fluent model with a Monte-Carlo N-Particle (MCNP) neutron transport model. The fuel tank geometry is the same as it was in the May 2015 report, annular with a thickness-to-height ratio of 0.16. An accelerator-driven neutron source provides the excitation for the reaction, and internal and external water cooling channels remove the heat. The model used in this work incorporates the Eulerian multiphase model with lift, wall lubrication, turbulent dispersion and turbulence interaction. The buoyancy-driven flow is modeled using the Boussinesq approximation, and the flow turbulence is determined using the k-ω Shear-Stress-Transport (SST) model. The dispersed turbulence multiphase model is employed to capture the multiphase turbulence effects.

  8. Interfacial Thermodynamics of Coexisting Aqueous Polymer Solutions

    NARCIS (Netherlands)

    Vis, M.

    2015-01-01

    Phase separation is commonly observed when two different polymers are present in aqueous solution, forming aqueous two-phase systems which typically consist for 90% of water. It is demonstrated that the presence of charge on one of the polymers results in an electric potential difference between the

  9. Kinetics of ptaquiloside hydrolysis in aqueous solution

    DEFF Research Database (Denmark)

    Ayala-Luis, Karina B.; Bildsøe Hansen, Pernille; Rasmussen, Lars Holm;

    2006-01-01

    of the toxin, a full understanding of the PTA degradation in aqueous environments is important. The kinetics of PTA hydrolysis was examined at 22C in aqueous buffered solutions (pH 2.88–8.93). The reaction was found to follow first-order kinetics with respect to PTA at all pH and temperature conditions. At p...

  10. Tannin (Polyphenol) Stability in Aqueous Solutions

    Science.gov (United States)

    Understanding the chemical stability of tannins (polyphenolics) in soils is critical to understanding their biological activities and fate. We examined the stability of chemically defined tannins in aqueous solutions under conditions simulating natural and laboratory conditions. We evaluated tanni...

  11. Calorimetric studies of macromolecular aqueous solutions

    NARCIS (Netherlands)

    Blandamer, M.J; Cullis, P.M.; Engberts, J.B.F.N.

    1996-01-01

    Both titration and differential scanning microcalorimetric techniques are shown to yield important information concerning the properties of macromolecules in aqueous solution. Application of titration calorimetry is examined in me context of deaggregation of canonic micelles (e.g. hexadecyltrimethyl

  12. Conformation dynamics and polarization effect of α,α-trehalose in a vacuum and in aqueous and salt solutions.

    Science.gov (United States)

    Kan, Zigui; Yan, Xiufen; Ma, Jing

    2015-03-01

    Conformational changes of α,α-trehalose in a vacuum, water, and 0-20 wt % NaCl solutions were investigated by means of molecular dynamics (MD) simulations at different levels of density function theory (DFT) and with fixed-charge nonpolarizable and variable-charge force fields (FFs), respectively. The relative thermodynamic stability of trehalose is enhanced by the formation of intercycle and/or intracycle hydrogen bonds, but some thermodynamically unfavorable structures can be sampled in the DFT-based ab initio MD simulation. The polarization effects of polar trehalose molecule in aqueous and NaCl solutions were studied by a series of MD simulations with both the conventional nonpolarizable and polarizable force field models. In the polarizable model, the partial charges of trehalose were updated every 2 ps using DFT calculations and fused with the other FF parameters for the energy calculation and MD simulation. Around the trehalose, water molecules located in an asymmetry model and trehalose have a stronger tendency to bind with water molecules than Na(+) and Cl(-) ions. When the trehalose concentration is increased from 3.26 to 6.31 wt % in salt aqueous solution, the two trehalose molecules periodically approach each other in a nearly anhydrate state and leave a way to keep the favorable hydration structure with the mean trehalose-trehalose distance of 8.6 Å. The similarity between the solvated dimer packing styles (shoulder-by-shoulder or head-to-head) and crystal stacking can be used to make an extrapolation to higher sugar concentrations and to rationalize the bioprotection function of trehalose in high salt concentration. PMID:25506668

  13. Effects of cryoprotectant concentration and cooling rate on vitrification of aqueous solutions

    CERN Document Server

    Berejnov, V; Alsaied, O A; Thorne, R E; Berejnov, Viatcheslav; Husseini, Naji S.; Alsaied, Osama A.; Thorne, Robert E.

    2006-01-01

    Vitrification of aqueous cryoprotectant mixtures is essential in cryopreservation of proteins and other biological samples. We report systematic measurements of critical cryoprotective agent (CPA) concentrations required for vitrification during plunge cooling from T=295 K to T=77 K in liquid nitrogen. Measurements on fourteen common CPAs including alcohols (glycerol, methanol, isopropanol), sugars (sucrose, xylitol, dextrose, trehalose), PEGs (ethylene glycol, PEG 200, PEG 2 000, PEG 20 000), glycols (DMSO, MPD), and salt (NaCl) were performed for volumes ranging over four orders of magnitude from ~nL to 20 mkL, and covering the range of interest in protein crystallography. X-ray diffraction measurements on aqueous glycerol mixtures confirm that the polycrystalline-to-vitreous transition occurs within a span of less than 2% w/v in CPA concentration, and that the form of polycrystalline ice (hexagonal or cubic) depends on CPA concentration and cooling rate. For most of the studied cryoprotectants, the critica...

  14. Effects of mannose, fructose, and fucose on the structure, stability, and hydration of lysozyme in aqueous solution

    DEFF Research Database (Denmark)

    Rahim, Abdoul; Peters, Günther H.J.; Jalkanen, Karl J.;

    2013-01-01

    The bio-protective properties of monosaccharaides, namely mannose, fructose and fucose, on the stability and dynamical properties of the NMR determined hen egg-white lysozyme structure have been investigated by means of molecular dynamics simulations at room temperature in aqueous solution and in 7...... that of starting NMR structure. The effects of sugars on protein conformation are found to be relatively strong in that the conformation of lysozyme is stable after an initial 9 ns equilibration for fucose and mannose and 12 ns equilibration for fructose, respectively, at high concentrations. For mannose the final...... RMSD is significantly smaller than that of fucose and fructose at the higher concentration, while at the lower concentration the RMSD are essentially the same. The radial distribution function of the water and sugars around lysozyme was used to monitor the preferential hydration. Analysis...

  15. Solvent Effects on Complexation of Molybdenum(VI) with Nitrilotriacetic Acid in Different Aqueous Solutions of Propanol

    Institute of Scientific and Technical Information of China (English)

    MOHAMMADI Behrouz; MOHAMMADI Jalal

    2007-01-01

    By using spectrophotometric and potentiometric techniques the formation constants of the species formed in the systems H++Mo(VI)+nitrilotriacetic acid and H++nitrilotriacetic acid have been determined in aqueous solutions plex was determined by the continuous variation method. It was shown that molybdenum(VI) forms a mononuclear 1 : 1 complex with nitrilotriacetic acid of the type MoO3L-3 at -1g[H+]=5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Linear relationships were observed when 1g Ks was plotted versus p*. Finally, the results were discussed in terms of the effect of solvent on complexation.

  16. Effects of baffles on separation of aqueous ethanol solution with hollow fibers

    Institute of Scientific and Technical Information of China (English)

    Zhihong YANG; Guoliang ZHANG; Lan LIN; Danping REN; Qin MENG; Hongzi ZHANG

    2009-01-01

    The effects of baffles on the operation and mass-transfer characteristics in novel hollow fiber membrane contactor used in distillation were investi-gated. Hollow fiber membranes, coated with a 7 μmpolydimethyl-siloxane, were operated as structural packing in the separation of ethanol-water solutions. The parallel flow mode was chosen for separation due to the stronger driving force of the concentration difference, in which liquid flows through the lumens of the fibers and vapor flows countercurrent-wise outside the fibers. Two baffles were installed on the shell side of the membrane contactors to enhance separation, which had a round shape with a semi-lunar hole. The results show that both baffled and unbaffled membrane contactors gave better, more produc-tive separations than traditional packing in distillation,such as the excellent Sulzer Gauze BX structured packing.The baffled membrane contactors performed better than unbaffled ones, especially at high vapor velocities. The minimal HTU of membrane contactor with baffles could reach as low as 4.5 cm, and almost all the contactors could work well above the limit where flooding normally occurs in conventional cases. Theoretical analysis predicted that baffles helped membrane module to obtain a higher mass-transfer coefficient and a smaller mass-transfer resistance.Finally, theoretical mass-transfer coefficient and experi-mental value were compared as well as the contribution of each individual mass-transfer coefficients among liquid,gas and membrane.

  17. Effect of divalent anions on photodegradation kinetics and pathways of riboflavin in aqueous solution.

    Science.gov (United States)

    Ahmad, Iqbal; Ahmed, Sofia; Sheraz, Muhammad Ali; Vaid, Faiyaz H M; Ansari, Izhar A

    2010-05-10

    The present investigation is based on a study of the effect of buffer and non-buffer divalent anions (phosphate, sulphate, tartrate, succinate, malonate) on the kinetics, product distribution and photodegradation pathways of riboflavin (RF) at pH 6.0-8.0. RF solutions (5x10(-5)M) were photodegraded in the presence of divalent anions (0.2-1.0M) using a visible light source and the photoproducts, cyclodehydroriboflavin (CDRF), formylmethylflavin (FMF), lumichrome (LC) and lumiflavin (LF) were assayed by a specific multicomponent spectrophotometric method. RF degradation in the presence of divalent anions follows parallel first-order kinetics to give CDRF and LC as the final products through photoaddition and photoreduction reactions, respectively. The divalent anion-catalysed CDRF formation is affected in the order: phosphate>sulphate>tartrate>succinate>malonate, showing maximum activity of the anions around pH 7. The divalent anions cause deviation of the photoreduction pathway in favour of the photoaddition pathway to form CDRF. The first- and second-order rate constants for the reactions involved in the photodegradation of RF have been determined and the rate-pH profiles and pathway relationships discussed. The catalytic activity of the divalent anions appears to be a function of the relative strength and chemical reactivity of the RF-divalent anion complex acting as a mediator in the photoaddition reaction.

  18. Aqueous Solutions of Ionic Liquids: Microscopic Assembly.

    Science.gov (United States)

    Vicent-Luna, Jose Manuel; Dubbeldam, David; Gómez-Álvarez, Paula; Calero, Sofia

    2016-02-01

    Aqueous solutions of ionic liquids are of special interest, due to the distinctive properties of ionic liquids, in particular, their amphiphilic character. A better understanding of the structure-property relationships of such systems is hence desirable. One of the crucial molecular-level interactions that influences the macroscopic behavior is hydrogen bonding. In this work, we conduct molecular dynamics simulations to investigate the effects of ionic liquids on the hydrogen-bond network of water in dilute aqueous solutions of ionic liquids with various combinations of cations and anions. Calculations are performed for imidazolium-based cations with alkyl chains of different lengths and for a variety of anions, namely, [Br](-), [NO3](-), [SCN](-) [BF4](-), [PF6](-), and [Tf2N](-). The structure of water and the water-ionic liquid interactions involved in the formation of a heterogeneous network are analyzed by using radial distribution functions and hydrogen-bond statistics. To this end, we employ the geometric criterion of the hydrogen-bond definition and it is shown that the structure of water is sensitive to the amount of ionic liquid and to the anion type. In particular, [SCN](-) and [Tf2N](-) were found to be the most hydrophilic and hydrophobic anions, respectively. Conversely, the cation chain length did not influence the results.

  19. Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2- solutions

    NARCIS (Netherlands)

    Manconi, I.; Maas, van der P.M.F.; Lens, P.N.L.

    2006-01-01

    Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the

  20. Mutagenic effect by phenylalanine during gamma-irradiation of plasmid DNA in aqueous solution under oxic conditions.

    Science.gov (United States)

    Reitsma-Wijker, C A; Slotman, B J; Lafleur, M V

    2000-11-01

    Irradiation of DNA in aqueous solution or in cells with gamma-rays results in different mutational spectra, indicating that in both situations different patterns of DNA damages are induced. One of the causes for these different types of damages might be the formation of secondary, organic radicals, if cells are irradiated. Some organic compounds, including the amino acid phenylalanine, are well known to produce radicals during irradiation. Under oxic conditions these secondary radicals react with oxygen, thus forming peroxyl radicals which can be very harmful to DNA, and which may, therefore, induce DNA damage leading to mutations. This study examines the influence of the presence of phenylalanine during gamma-irradiation of DNA in aqueous solution under oxic conditions. The results indicate that the formation of phenylalanine radicals influences the types of induced mutations in the gamma-radiation-induced mutation spectrum. The most prominent difference is the increase in G:C to T:A transversions and the decrease in G:C to A:T transitions in the presence of phenylalanine. Further, it appears that the gamma-radiation-induced mutation spectrum after irradiation of DNA in aqueous solution is more comparable to the intracellular gamma-radiation-induced mutation spectrum in E. coli cells, if phenylalanine is present during irradiation. Therefore, these results suggest that the presence of phenylalanine during irradiation of DNA in aqueous solution gives a better impression of gamma-radiation-induced mutations in bacterial systems than water only. PMID:11035161

  1. Effect of pH on the Electrophoretic Mobility of Spores of Bacillus anthracis and Its Surrogates in Aqueous Solutions

    Science.gov (United States)

    Electrophoretic mobility (EPM) of endospores of Bacillus anthracis and surrogates were measured in aqueous solution across a broad pH range and several ionic strengths. EPM values trended around phylogenetic clustering based on the 16S rRNA gene. Measurements reported here prov...

  2. Bioremediation of herbicide velpar K® in vitro in aqueous solution with application of EM-4 (effective microorganisms

    Directory of Open Access Journals (Sweden)

    Márcio Antônio Gomes Ramos

    2012-02-01

    Full Text Available This work assessed the bioremediation of herbicide Velpar K®, in vitro in aqueous solution, used against weeds in sugar cane in São Paulo state. The herbicide contained Hexazinone and Diuron. It was used the microbial inoculant denominated Effective Microorganisms (EM-4, pool of microorganisms from soil that contained lactic and photosynthetic bacteria, fungi, yeasts and actinomycetes for bioremediation. Results for the depth of cultivation on agar-agar inoculated with EM-4 showed the microorganisms growth in the concentrations between 0.2% and 1.0% of the Velpar K®in the gel. The analysis of high performance liquid chromatography (HPLC showed that the EM-4 was effective for the bioremediation of the herbicide, which reached the values of 80% for diuron and 70% for hexazinone after 21 days in solution of 2:1 of Velpar K®/EM-4 ratio. These results could be useful for planning the bioremediation of contaminated areas with Velpar K®.

  3. Precipitation of neptunium dioxide from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, K E

    1999-12-01

    Tens of thousands of metric tons of highly radioactive, nuclear waste have been generated in the US. Currently, there is no treatment or disposal facility for these wastes. Of the radioactive elements in high-level nuclear waste, neptunium (Np) is of particular concern because it has a long half-life and may potentially be very mobile in groundwaters associated with a proposed underground disposal site at Yucca Mountain, Nevada. Aqueous Np concentrations observed in previous, short-term solubility experiments led to calculated potential doses exceeding proposed long-term regulatory limits. However, thermodynamic data for Np at 25 C showed that these observed aqueous Np concentrations were supersaturated with respect to crystalline NpO{sub 2}. It was hypothesized that NpO{sub 2} is the thermodynamically stable solid phase in aqueous solution, but it is slow to form in an aqueous solution of NpO{sub 2}{sup +} on the time scale of previous experiments. The precipitation of NpO{sub 2} would provide significantly lower aqueous Np concentrations leading to calculated doses below proposed regulatory limits. To test this hypothesis, solubility experiments were performed at elevated temperature to accelerate any slow precipitation kinetics. Ionic NpO{sub 2}{sup +} (aq) was introduced into very dilute aqueous solutions of NaCl with initial pH values ranging from 6 to 10. The reaction vessels were placed in an oven and allowed to react at 200 C until steady-state aqueous Np concentrations were observed. In all cases, aqueous Np concentrations decreased significantly from the initial value of 10{sup {minus}4} M. The solids that formed were analyzed by x-ray powder diffraction, x-ray absorption spectroscopy, and scanning electron microscopy. The solids were determined to be high-purity crystals of NpO{sub 2}. This is the first time that crystalline NpO{sub 2} has been observed to precipitate from NpO{sub 2}{sup +}(aq) in near-neutral aqueous solutions. The results obtained

  4. Catalyzed reduction of nitrate in aqueous solutions

    International Nuclear Information System (INIS)

    Sodium nitrate and other nitrate salts in wastes is a major source of difficulty for permanent disposal. Reduction of nitrate using aluminum metal has been demonstrated, but NH3, hydrazine, or organic compounds containing oxygen would be advantageous for reduction of nitrate in sodium nitrate solutions. Objective of this seed money study was to determine minimum conditions for reduction. Proposed procedure was batchwise heating of aqueous solutions in closed vessels with monitoring of temperatures and pressures. A simple, convenient apparatus and procedure were demonstrated for observing formation of gaseous products and collecting samples for analyses. The test conditions were 250 degree C and 1000 psi max. Any useful reduction of sodium nitrate to sodium hydroxide as the primary product was not found. The nitrate present at pHs 3 or NH4NO3 is easily decomposed, and the effect of nitromethane at these low pHs was confirmed. When acetic acid or formic acid was added, 21 to 56% of the nitrate in sodium nitrate solutions was reduced by methanol or formaldehyde. With hydrazine and acetic acid, 73 % of the nitrate was decomposed to convert NaNO3 to sodium acetate. With hydrazine and formic acid, 36% of the nitrate was decomposed. If these products are more acceptable for final disposal than sodium nitrate, the reagents are cheap and the conversion conditions would be practical for easy use. Ammonium acetate or formate salts did not significantly reduce nitrate in sodium nitrate solutions

  5. Effective removal of tetracycline from aqueous solution using activated carbon prepared from tomato (Lycopersicon esculentum Mill.) industrial processing waste.

    Science.gov (United States)

    Sayğılı, Hasan; Güzel, Fuat

    2016-09-01

    Activated carbon (TAC) prepared under optimized conditions with ZnCl2 activation from a new precursor; tomato industrial processing waste (TW), was applied as an adsorbent to remove tetracycline (TC) from aqueous solution. The factors (TAC dosage, initial TC concentration, contact time, ionic strength and solution temperature) affecting the adsorption process were examined at natural pH (5.7) of TAC-TC system in aqueous solution. Kinetic data was found to be best complied by the pseudo-second order model. The isotherm analysis indicated that the equilibrium data could be represented by the Langmuir model. The maximum adsorption capacity was identified as 500.0mgg(-1) at 308K.

  6. Effective removal of tetracycline from aqueous solution using activated carbon prepared from tomato (Lycopersicon esculentum Mill.) industrial processing waste.

    Science.gov (United States)

    Sayğılı, Hasan; Güzel, Fuat

    2016-09-01

    Activated carbon (TAC) prepared under optimized conditions with ZnCl2 activation from a new precursor; tomato industrial processing waste (TW), was applied as an adsorbent to remove tetracycline (TC) from aqueous solution. The factors (TAC dosage, initial TC concentration, contact time, ionic strength and solution temperature) affecting the adsorption process were examined at natural pH (5.7) of TAC-TC system in aqueous solution. Kinetic data was found to be best complied by the pseudo-second order model. The isotherm analysis indicated that the equilibrium data could be represented by the Langmuir model. The maximum adsorption capacity was identified as 500.0mgg(-1) at 308K. PMID:27177317

  7. After-effects of electron capture of 57Co in frozen aqueous solutions of 57CoCl2

    International Nuclear Information System (INIS)

    Moessbauer spectra of 57Co in dilute frozen aqueous solutions of 57CoCl2 and in 0.11 at.% frozen aqueous solutions of CoCl2 with and without glass former have been studied. The spectra reveal the presence of a small fraction of Fe3+ ions besides the Fe2+ as a consequence of the Auger cascade following the electron capture. The addition of glycerol to the 57CoCl2 solution resulted in decreasing the fraction of Fe3+. The quadrupole splitting of the ferrous ions was found to be less by 13% than that of the Fe(H2O)62+ complex as measured in absorption geometry. This is suggested as being the consequence of the autoradiolysis of water molecules resulting in a metastable state of the complex. (orig.)

  8. Silver colloidal effects on excited-state structure and intramolecular charge transfer of p-N, N-dimethylaminobenzoic acid in aqueous cyclodextrin solutions

    International Nuclear Information System (INIS)

    The silver colloidal effects on the excited-state structure and intramolecular charge transfer (ICT) of p-N,N-dimethylaminobenzoic acid (DMABA) in aqueous cyclodextrin (CD) solutions have been investigated by UV-VIS absorption, steady-state and time-resolved fluorescence, and transient Raman spectroscopy. As the concentration of silver colloids increases, the ratio of the ICT emission to the normal emission (Ia/Ib) of DMABA in the aqueous α-CD solutions are greatly decreased while the Ia/Ib values in the aqueous β-CD solutions are significantly enhanced. It is also noteworthy that the ICT emission maxima are red-shifted by 15-40 nm upon addition of silver colloids, implying that DMABA encapsulated in α-CD or β-CD cavity is exposed to more polar environment. The transient resonance Raman spectra of DMABA in silver colloidal solutions demonstrate that DMABA in the excited-state is desorbed from silver colloidal surfaces as demonstrated by the disappearance of vs(CO2-)(1380 cm-1) with appearance of v (C-OH)(1280 cm-1) band, respectively. Thus, in the aqueous β-CD solutions the carboxylic acid group of DMABA in the excited-state can be readily hydrogen bonded with the secondary hydroxyl group of β-CD while in aqueous and α-CD solutions the carboxylic acid group of DMABA has the hydrogen-bonding interaction with water. Consequently, in the aqueous β-CD solutions the enhancement of the Ia/Ib value arises from the intermolecular hydrogen-bonding interaction between DMABA and the secondary hydroxyl group of β-CD as well as the lower polarity of the rim of the β-CD cavity compared to bulk water. This is also supported by the increase of the association constant for DMABA/β-CD complex in the presence of silver colloids

  9. Effect of calcination temperature on electrocatalytic activities of Ti/IrO2 electrodes in methanol aqueous solutions

    International Nuclear Information System (INIS)

    The electrochemical activity of thermo-decomposed Ti/IrO2 electrodes in aqueous solution containing methanol compound has been studied, emphasizing on the influence of calcination temperature. Scanning electron microscopy (SEM) images showed that the typical cracked morphology of oxide coatings disappears gradually as the preparation temperature increases, leading to the decrease in the amount of electrochemically active sites as measured by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in organics-free aqueous solution. With the exception of samples prepared at high temperatures (e.g. 600 deg. C), same change tendency of electro-activity with temperature was also found in methanol aqueous solutions, in which activity was observed to decrease as compared with that in blank solution. Three possible explanations for this phenomenon (i.e. active dissolution of oxide coatings, organics adsorption and dimerization/polymerization on electrode surface, respectively) were discussed, where the former two were believed to be more reasonable considering the CH3OH small molecular chosen in this system. However, none of these three mechanisms could explain the abnormal activation behavior observed at electrodes prepared at 600 deg. C in CH3OH solution. XRD pattern showed the fact that when sintering temperature went up to 600 deg. C IrO2 would decompose into metallic iridium component. The existence of metallic iridium might facilitate the organics oxidation as stated in previous literatures, which leads to the exceptional activation of oxide surface by methanol component. A simple reaction mechanism for electrodes in methanol aqueous solutions was proposed and used to interpret the negative shift in startness potential of the oxygen evolution reaction (OER). Organics oxidation seems to facilitate the OER and vice versa. The latter statement has been reported by other workers

  10. Hydrophobic Solvation: Aqueous Methane Solutions

    Science.gov (United States)

    Konrod, Oliver; Lankau, Timm

    2007-01-01

    A basic introduction to concept of a solvation shell around an apolar solute as well as its detection is presented. The hydrophobic solvation of toluene is found to be a good teaching example which connects macroscopic, phenomenological thermodynamic results with an atomistic point of view.

  11. Further insights into the environmental effects on the computed hyperfine coupling constants of nitroxides in aqueous solution.

    Science.gov (United States)

    Houriez, Céline; Ferré, Nicolas; Siri, Didier; Masella, Michel

    2009-11-12

    We investigated the main two factors influencing the mean hyperfine coupling constants of small nitroxide radicals in aqueous solution, i.e., the out-of-plane displacement of their nitrogen atom and the environmental effects (solvent effects), by means of the approach we previously developed and fine-tuned to study the solvation of the dimethyl nitroxide radical. Our methodology efficiently combines classical molecular dynamics based on a polarizable force field at the nanosecond scale and quantum mechanics/molecular mechanics (QM/MM) computations to account for the bulk instantaneous electrostatic environmental effect. Our method has been applied to five small nitroxides, namely methyl nitroxide, ethyl nitroxide, dimethyl nitroxide, di-tert-butyl nitroxide, and PROXYL. The theoretical nitrogen hyperfine coupling constant values for the five nitroxides in solution are in good agreement with experiment (difference of 0.3 G on average). Our approach showed that the solvent shift in nitroxide hyperfine coupling constants is almost constant whatever the nitroxide, and, particularly, whatever the nitroxide NO moiety's accessibility to the solvent. This result contrasts with earlier results derived from 10 ps scale trajectories based on Car-Parrinello molecular dynamics approach. However, we show that if we consider on average these latter results, they are in agreement with our conclusion. We also present an attempt to identify the origin of this result by analyzing the solvent contributions in terms of effects of the nitroxide first hydration shell and of the bulk, and by investigating the relation between these two contributions and the solvent structure at the vicinity of the NO moiety. PMID:19845322

  12. Different immersion periods and aqueous solutions effects upon the corrosion resistance of zinc and aluminium specimens

    Directory of Open Access Journals (Sweden)

    Osório, W. R.

    2005-12-01

    Full Text Available Several metallic materials form spontaneously an oxide film at the surface when is exposed in a corrosive environment. It is well known that the type of corrosive media may develop different results at the material corrosion resistance. The aim of the present paper is to investigate the influence of immersion periods and different solutions upon the corrosion resistance of pure Zn and Al specimens presenting different grain morphologies. The specimens were monitored for several periods in a 3 % NaCl solution at room temperature. Tests were also performed with variations of the 3 % NaCl solution modified by additions of acid and alkaline components. Both the electrochemical impedance spectroscopy (EIS and polarization methods were applied.

    Algunos materiales metálicos, cuando se encuentran en un entorno corrosivo, forman espontáneamente una película de óxido en su superficie. Se sabe que los medios corrosivos pueden dar resultados diferentes, según sea la resistencia a la corrosión del material. El propósito del siguiente trabajo es investigar la influencia de los períodos de inmersión en diferentes soluciones sobre la resistencia a la corrosión de probetas de cinc y aluminio puros, con morfologías de grano diferentes. Las probetas fueron ensayadas durante varios períodos de tiempo en soluciones de NaCl 3 % y también con adiciones de ácidos y bases. Se utilizaron las técnicas de espectrometría de impedancia electroquímica (EIS y de polarización.

  13. Aggregation behavior of 1-dodecyl-3-methylimidazolium bromide in aqueous solution: effect of ionic liquids with aromatic anions.

    Science.gov (United States)

    Gu, Yingqiu; Shi, Lijuan; Cheng, Xiyuan; Lu, Fei; Zheng, Liqiang

    2013-05-28

    The effects of ionic liquids (ILs), 1-butyl-3-methylimidazolium methylsulfonate (bmimMsa), 1-butyl-3-methylimidazolium benzenesulfonate (bmimBsa), and 1-butyl-3-methylimidazolium 2-naphthalenesulfonate (bmimNsa), on the aggregation behavior of 1-dodecyl-3-methylimidazolium bromide (C12mimBr) in aqueous solution were investigated by surface tension, dynamic light scattering measurements, and (1)H NMR spectroscopy. The ability to promote the surfactant aggregation is in the order bmimNsa > bmimBsa > bmimMsa. Nevertheless, only bmimNsa distinctly reduces both the CMC value and the surface tension at CMC. Due to the penetration of C10H7SO3(-)anions into the surfactant aggregate, bmimNsa is found to induce a phase transition from micelles to vesicles, whereas the other ILs only slightly increase the sizes of micelles. The combined effect of intermolecular interactions, such as hydrophobic effect, electrostatic attractions, and π-π stacking interactions, is supposed to be responsible for this structural transformation, in which π-π stacking plays an important role. PMID:23642150

  14. Issues in Freeze Drying of Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    王维; 陈墨; 陈国华

    2012-01-01

    Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The in-creased importance Of the process is gaining a worldwide interest of research. A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error em-piricism. Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying, material science and mechanisms of heat and mass transfer. This paper presents an overview on freeze ding of aqueous solutions based on publications in the past few decades. The important issuesof the process are analyzed.

  15. SODIUM DI-N-DODECYL PHOSPHATE VESICLES IN AQUEOUS-SOLUTION - EFFECTS OF ETHANOL, PROPANOL, AND TETRAHYDROFURAN ON THE GEL TO LIQUID-PHASE TRANSITION

    NARCIS (Netherlands)

    BLANDAMER, MJ; BRIGGS, B; BUTT, MD; WATERS, M; CULLIS, PM; ENGBERTS, JBFN; HOEKSTRA, D; MOHANTY, RK

    1994-01-01

    For aqueous solutions containing vesicles formed by sodium di-n-dodecyl phosphate, the gel to liquid-crystal transition occurs near 35 degrees C, the temperature T-m. When ethanol is added, T-m decreases, but the scan shows evidence of several transitions as more alcohol is added. The effect of adde

  16. Hydrogen/deuterium isotope effects in water and aqueous solutions of organic molecules and proteins

    International Nuclear Information System (INIS)

    Highlights: ► Hydrogen/deuterium substitution has significant effects in hydrogenous materials. ► The effects can involve structure, phase behavior and protein stability. ► The effects must be kept in mind in the interpretation of scattering experiments. ► The effects may be mitigated by an appropriate choice of experimental conditions. - Abstract: It is pointed out that hydrogen/deuterium substitution, frequently used in neutron scattering studies of the structure and dynamics of hydrogenous samples, can have significant effects on structure, phase behavior and protein stability. The effects must be kept in mind in the interpretation of such experiments. In suitable cases, these effects can be mitigated by an appropriate choice of experimental conditions

  17. The Synergistic Effect of High Pressure CO2 and Nisin on Inactivation of Bacillus subtilis Spores in Aqueous Solutions

    Science.gov (United States)

    Rao, Lei; Wang, Yongtao; Chen, Fang; Liao, Xiaojun

    2016-01-01

    The inactivation effects of high pressure CO2 + nisin (simultaneous treatment of HPCD and nisin, HPCD + nisin), HPCD→nisin (HPCD was followed by nisin), and nisin→HPCD (nisin was followed by HPCD) treatments on Bacillus subtilis spores in aqueous solutions were compared. The spores were treated by HPCD at 6.5 or 20 MPa, 84–86°C and 0–30 min, and the concentration of nisin was 0.02%. Treated spores were examined for the viability, the permeability of inner membrane (IM) using flow cytometry method and pyridine-2, 6-dicarboxylic acid (DPA) release, and structural damage by transmission electron microscopy. A synergistic effect of HPCD + nisin treatment on inactivation of the spores was found, and the inactivation efficiency of the spores was HPCD + nisin > HPCD→nisin or nisin→HPCD. Moreover, HPCD + nisin caused higher IM permeability and DPA release of the spores than HPCD. A possible action mode of nisin-enhanced inactivation of the spores was suggested as that HPCD firstly damaged the coat and cortex of spores, and nisin penetrated into and acted on the IM of spores, which increased the damage to the IM of spores, and resulted in higher inactivation of the spores. PMID:27708639

  18. Study of solvent effects on complex formation of tungsten (VI) with ethylenediaminediacetic acid in aqueous solutions of propanol

    International Nuclear Information System (INIS)

    Spectrophotometric and potentiometric techniques were used to determine the formation constants of the species formed in the systems H+ + W(VI) + ethylenediaminediacetic acid and H+ + ethylenediaminediacetic acid in aqueous solutions of propanol at 25 deg C and constant ionic strength 0.1 mol dm-3 of sodium perchlorate. The composition of the complex was determined by the continuous variations method. It was shown that tungsten (VI) forms a mononuclear 1 : 1 complex with ethylenediaminediacetic acid of the type WO3L3- at -log[H+] = 5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Solvents have been parameterized by scales of dipolarity/polarizability π*, hydrogen-bond donor strength α, and hydrogen-bond acceptor strength β. Linear dependence on these solvent parameters are used to correlate and predict a wide variety of solvent effects, as well as to provide an analysis of them. Linear relationships are observed when logKS is plotted versus π*. Finally, the results are discussed in terms of the effect of solvent on complexation

  19. Removal of Dimethyl Sulfide from Aqueous Solution Using Cost-Effective Modified Chicken Manure Biochar Produced from Slow Pyrolysis

    Directory of Open Access Journals (Sweden)

    Minh-Viet Nguyen

    2015-11-01

    Full Text Available This study investigated the characteristics of using a cost-effective, amine-modified biochar (BC derived from chicken manure for removing dimethyl sulfide (DMS from an aqueous solution. The amine-modified BC showed much higher adsorption of DMS compared to commercial activated carbons under varying conditions of contact time, initial concentration, and adsorbent dosage. The DMS removal efficiency increased as the adsorbent dosage was increased from 0.01 to 0.25 g and reached 92.4% even at the relatively low adsorbent dose of 0.015 g. The DMS adsorption capacity of the amine-modified BC (mg/g increased with increasing DMS concentration, while the incremental rate of the removal efficiency decreased. The adsorption process was well explained by a pseudo-second-order kinetics model. The adsorption of DMS is more appropriately described by the Freundlich isotherm (R2 = 0.989 than by the Langmuir isotherm (R2 = 0.942. The DMS removal efficiency was only reduced by 23.4% even after 10 recovery cycles. The surface area of the amine-modified BC was much higher (9.4 ± 1.2 times than that of the unmodified BC. The amine-modified BC with a high surface area of 334.6 m2/g can be utilized as a cheap and effective alternative adsorbent to commercial activated carbon for DMS removal.

  20. Quasi-Immiscible Spreading of Aqueous Surfactant Solutions on Entangled Aqueous Polymer Solution Subphases

    OpenAIRE

    Sharma, Ramankur; Corcoran, Timothy E.; Garoff, Stephen; Przybycien, Todd M.; Swanson, Ellen R.; Tilton, Robert D.

    2013-01-01

    Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface active dye, was added to the surfactant solution. T...

  1. Ludwig-Soret effect of aqueous solutions of ethylene glycol oligomers, crown ethers, and glycerol: Temperature, molecular weight, and hydrogen bond effect

    Science.gov (United States)

    Maeda, Kousaku; Shinyashiki, Naoki; Yagihara, Shin; Wiegand, Simone; Kita, Rio

    2015-09-01

    The thermal diffusion, also called the Ludwig-Soret effect, of aqueous solutions of ethylene glycol oligomers, crown ethers, and glycerol is investigated as a function of temperature by thermal diffusion forced Rayleigh scattering. The Soret coefficient, ST, and the thermal diffusion coefficient, DT, show a linear temperature dependence for all studied compounds in the investigated temperature range. The magnitudes and the slopes of ST and DT vary with the chemical structure of the solute molecules. All studied molecules contain ether and/or hydroxyl groups, which can act as acceptor or donor to form hydrogen bonds, respectively. By introducing the number of donor and acceptor sites of each solute molecule, we can express their hydrogen bond capability. ST and DT can be described by an empirical equation depending on the difference of donor minus acceptor sites and the molecular weight of the solute molecule.

  2. Effects of Aqueous Solutions on the Slow Crack Growth of Soda-Lime-Silicate Glass

    Science.gov (United States)

    Hausmann, Bronson D.; Salem, Jonathan A.

    2016-01-01

    The slow crack growth (SCG) parameters of soda-lime-silicate were measured in distilled and saltwater of various concentrations in order to determine if the presence of salt and the contaminate formation of a weak sodium film affects stress corrosion susceptibility. Past research indicates that solvents affect the rate of crack growth; however, the effects of salt have not been studied. The results indicate a small but statistically significant effect on the SCG parameters A and n at high concentrations; however, for typical engineering purposes, the effect can be ignored.

  3. Aqueous Solution Chemistry on Mars

    Science.gov (United States)

    Quinn, R.; Hecht, M.; Kounaves, S.; Young, S.; West, S.; Fisher, A.; Grunthaner, P.

    2007-12-01

    Currently en route to Mars, the Phoenix mission carries four wet chemistry cells designed to perform basic solution chemistry on martian soil. The measurement objectives are typical of those that would be performed on an unknown sample on Earth, including detection of common anions and cations, total conductivity, pH, redox potential, cyclic voltammetry (CV), etc. Both the challenge and the novelty arise from the necessity to perform these measurements with severely constrained resources in a harsh and (literally) alien environment. Sensors for all measurements are integrated into a common "beaker," with the ability to perform a two-point calibration of some sensors using a pair of low-concentration solutions. Sulfate measurement is performed with a crude titration. While most measurements use ion selective electrodes, halide interferences are resolved by independent chronopotentiometry (CP) measurements. No preconditioning of the soil-water mixture is possible, nor is any physical characterization of the introduced soil sample beyond coarse visual inspection. Among the idiosyncrasies of the measurement is the low external pressure, which requires that the analysis be performed close to the boiling point of water under an atmosphere consisting almost entirely of water vapor. Despite these liabilities, however, extensive laboratory characterization has validated the basic approach, and protocols for both CV and CP have been developed and tested. Enhancing the value of the measurement is the suite of coordinated observations, such as microscopy and evolved gas analysis, to be performed by other Phoenix instruments.

  4. Effect of Counterion and Configurational Entropy on the Surface Tension of Aqueous Solutions of Ionic Surfactant and Electrolyte Mixtures

    OpenAIRE

    Youichi Takata; Hiroaki Tagashira; Atsushi Hyono; Hiroyuki Ohshima

    2010-01-01

    In order to clarify the adsorption behavior of cationic surfactants on the air/aqueous electrolyte solution surface, we derived the theoretical equation for the surface tension. The equation includes the electrical work required for charging the air/water surface and the work attributable to the configurational entropy in the adsorbed film. By fitting the equation to the experimental data, we determined the binding constant between adsorbed surfactant ion and counterion, and found that the br...

  5. Comments on a model for isotope effects on Henry's law constants in aqueous solution

    International Nuclear Information System (INIS)

    A model has been proposed in the literature for isotope effects on Henry's law constants in which the motion of the dissolved molecule surrounded by a solvent cage is approximated by the motion of a particle in a cubic box. The isotope effect then arises from the three free translations of the gas phase molecule which become the restricted translations of a particle in a box for the dissolved molecule. The theoretical equation for the isotope effect is derived here on the basis of this model. Zero-point energy arguments have been used in the literature in conjunction with this model to deduce solvent cage dimensions from observed isotope effect data. These arguments are shown here to be theoretically wrong. The correct theory for the particle in a box model gives much larger dimensions for the solvent cage than the incorrect zero-point he solvent cage than the incorrect zero-point energy argument

  6. Radium removal from aqueous sulphate solutions

    International Nuclear Information System (INIS)

    A process for removing radium from an aqueous sulphate solution also containing magnesium is claimed. The pH of the solution is less than 10. A soluble barium salt is added to the solution to precipitate radium as barium radium sulphate. The pH of the solution is then raised to at least 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate. The precipitates are separated from the solution. If the sulphate solution contains dissolved magnesium and other impurities at a pH not greater than 7, then the first step in the process involves raising the pH of the solution to a value not greater than 10 to precipitate some of the magnesium and a substantial proportion of the other impurities and separating the precipitate from the solution. The radium removal is a step in the treatment of liquids resulting from the sulphuric acid leaching of uranium ores

  7. Arsenic removal from aqueous solutions using Fe3O4-HBC composite: effect of calcination on adsorbents performance.

    Directory of Open Access Journals (Sweden)

    Shams Ali Baig

    Full Text Available The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C and environment (air and nitrogen were investigated for the adsorptive removal of As(V and As(III from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4 via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2>Fe3O4-HBC (uncalcined>Fe3O4-HBC-400°C(N2>Fe3O4-HBC-400°C(air>Fe3O4-HBC-1000°C(air and the maximum As(V and As(III adsorption capacities were found to be about 3.35 mg g(-1 and 3.07 mg g(-1, respectively. The adsorption of As(V and As(III remained stable in a wider pH range (4-10 using Fe3O4-HBC-1000°C(N2. Additionally, adsorption data fitted well in pseudo-second-order (R2>0.99 rather than pseudo-first-order kinetics model. The adsorption of As(V and As(III onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher strongly inhibited As(V and As(III removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water.

  8. Effect of Na+ impregnated activated carbon on the adsorption of NH+4-N from aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Mo Shi; Zhengfang Wang; Zheng Zheng

    2013-01-01

    Two kinds of activated carbons modified by Na+ impregnation after pre-treatments involving oxidation by nitric acid or acidification by hydrochloric acid (denoted as AC/N-Na and AC/HCl-Na,respectively),were used as adsorbents to remove NH4+-N.The surface features of samples were investigated by BET,SEM,XRD and FT-IR.The adsorption experiments were conducted in equilibrium and kinetic conditions.Influencing factors such as initial solution pH and initial concentration were investigated.A possible mechanism was proposed.Results showed that optimal NH4+-N removal efficiency was achieved at a neutral pH condition for the modified ACs.The Langmuir isotherm adsorption equation provided a better fit than other models for the equilibrium study.The adsorption kinetics followed both the pseudo second-order kinetics model and intra-particle kinetic model.Chemical surface analysis indicated that Na+ ions form ionic bonds with available surface functional groups created by pre-treatment,especially oxidation by nitric acid,thus increasing the removal efficiency of the modified ACs for NH4+-N.Na+-impregnated ACs had a higher removal capability in removing NH4+-N than unmodified AC,possibly resulting from higher numbers of surface functional groups and better intra-particle diffusion.The good fit of Langmuir isotherm adsorption to the data indicated the presence of monolayer NH4+-N adsorption on the active homogenous sites within the adsorbents.The applicability of pseudo second-order and intra-particle kinetic models revealed the complex nature of the adsorption mechanism.The intra-particle diffusion model revealed that the adsorption process consisted not only of surface adsorption but also intra-particle diffusion.

  9. COMPETITIVE BIOSORPTION OF LEAD (II IONS FROM AQUEOUS SOLUTIONS ONTO TERMINALIA CATAPPA L. LEAVES AS A COST EFFECTIVE BIOSORBENT

    Directory of Open Access Journals (Sweden)

    Jagruti N. Jadav

    2015-03-01

    Full Text Available In the present study, the competitive biosorption properties of nonliving biosorbent, Terminalia catappa L. leaves as a cost effective biosorbent for Pb(II ions was investigated using batch technique. FTIR analysis of the biosorbent revealed that hydroxyl, carbonyl and carboxyl groups which are involved in the uptake of lead (II ions. SEM represents porous structure with large surface area. The effects of operational factors including solution pH, biosorbent dose, initial lead (II ions concentration, contact time and temperature on the biosorption efficiency were studied. The optimum solution pH for Pb(II ions adsorption by biosorbent was 6.0 with the optimal removal 82.06%. The biosorbent dose 5 mg/mL was enough for optimal removal of 79.35%. The biosorption process was relatively fast and equilibrium was achieved after 90 minutes of contact time. The experimental equilibrium biosorption data were fitted by four widely used two-parameters Langmuir, Freundlich, Dubinin-Kaganer-Redushkevich (DKR and Temkin isotherm equations. Langmuir isotherm model provided a better fit with the experimental data than Freundlich, Temkin and Dubinin-Kaganer-Redushkevich (DKR adsorption isotherm models by high correlation coefficient value (R2= 0.997. The maximum adsorption capacity determined from Langmuir isotherm was found to be 50.00 mg/g of biosorbent. Simple kinetic models such as pseudo-first-order, pseudo-second-order, Elovich equation and Weber and Morris intraparticle diffusion rate mixing equation were employed to determine the adsorption mechanism. Results indicates that pseudo-second-order kinetic model (R2= 0.999 was found to be correlate the experimental data strongest than other three kinetic models and this suggests that chemical biosorption process was more dominant. Thermodynamic study revealed that the biosorption process was spontaneous, endothermic and increasing randomness of the solid solution interfaces. Tarminalia catappa L. leaves were

  10. Aqueous solutions of ionic liquids: microscopic assembly

    NARCIS (Netherlands)

    J.M. Vicent-Luna; D. Dubbeldam; P. Gómez-Álvarez; S. Calero

    2016-01-01

    Aqueous solutions of ionic liquids are of special interest, due to the distinctive properties of ionic liquids, in particular, their amphiphilic character. A better understanding of the structure-property relationships of such systems is hence desirable. One of the crucial molecular-level interactio

  11. Water & Aqueous Solutions. Final Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-08-09

    The Gordon Research Conference (GRC) on Water & Aqueous Solutions was held at Holderness School, New Hampshire, 8/4/02 thru 8/9/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  12. SEPARATION OF SCANDIUM FROM AQUEOUS SOLUTIONS

    Science.gov (United States)

    Peppard, D.F.; Nachtman, E.S.

    1958-02-25

    This patent relates to a process for the separation of scandium from yttrium, thorium, and trivalent rare earths and with their separation from each other. It has been found that scandium and yttrium can be separated from trivalent rare earths in acidic solution, for example, a solution 6 M in HCl, by contacting with tributyl phosphate, whereupon the scandum is preferentially extracted into the organic phase, leaving the yttrium and trivalent rare earths in the aqueous phase.

  13. Alginic acid and hyaluronic acid, effective stabilizers of carthamin red colour in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Koshi Saito

    2014-02-01

    Full Text Available Sodium salts and free forms of two heterosaccharides, alginic and hyaluronic acids were mixed with carthamin in a buffer at pH 5.5 and their preservation effects of carthamin red colour were screened after incubation for 24 h at 3-5oC in the dark. The effects observed were (alginic acid/hyaluronic acid, % on average: 69.3/60.3, for which the values are higher by 40.9 and 29.1%, respectively, compared with those of the control which was conducted with no addition of heterosaccharides. Alginic acid is a more promising stabilizer than haluronic acid, indicating that active groups such as hydroxyls, carboxyls and amino groups on the building units of the macromolecules are associated closely with the carthamin red colour preservation. The empirical outcomes are referred to the practical application of carthamin as a colourant of food products.

  14. Effectiveness of Quercus Branti Activated Carbon in Removal of Methylene Blue from Aqueous Solutions

    OpenAIRE

    Abdolmotaleb Seidmohammadi; Ghorban Asgari; Mostafa Leili; Abdollah Dargahi; Azam Mobarakian

    2015-01-01

    Background & Aims of the Study: Dyes are one of the most contaminants in textile industrial wastewater that they are often carcinogenic, mutagenic and non-degradable. Therefore, with regard to environmental aspects, their removal from effluents is very essential. The purpose of this study was the perception of adsorption process and promotion of an economic technology for colored wastewater treatment. Therefore, activated carbon from Oak fruit bark was used as an effective and economic adsorb...

  15. Solvent isotope effect on the complexation of cyclodextrins in aqueous solutions

    International Nuclear Information System (INIS)

    The replacement of H2O by D2O as a solvent resulted in an appreciable increase in the binding constants (Kb) for complexes of native and modified cyclodextrins with such typical guests as p-nitrophenol, the p-nitrophenolate ion, Methyl Orange, phenolphthalein, and inorganic anions. The observed increase in Kb was attributed mainly to a solvent H/D isotope effect on hydrophobic and electrostatic interactions between the hosts and guests. (author)

  16. Effectiveness of Quercus Branti Activated Carbon in Removal of Methylene Blue from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Abdolmotaleb Seidmohammadi

    2015-10-01

    Full Text Available Background & Aims of the Study: Dyes are one of the most contaminants in textile industrial wastewater that they are often carcinogenic, mutagenic and non-degradable. Therefore, with regard to environmental aspects, their removal from effluents is very essential. The purpose of this study was the perception of adsorption process and promotion of an economic technology for colored wastewater treatment. Therefore, activated carbon from Oak fruit bark was used as an effective and economic adsorbent. Materials & Methods: This study was performed at laboratory scale and batch system. At present study, the adsorbent surface properties was evaluated by use of the (FT-IR test and scanning electronic microscope (SEM. Also, effect of various operating parameters such as pH, contact time, adsorbent dose, initial dye concentration and temperature on dye removal from synthetic wastewater were studied. Results: In this study, maximum removal efficiency of methylene blue were achieved at optimal pH=6, reaction time 180 minutes, and adsorbent dose 2 gl-1. Methylene blue removal efficiency with initial concentration of 100 mg.l-1 was 91.08%. Conclusions: According to results, it was cleared that : Quercus branti activated carbon can be used as an effective and economic adsorbent in waste water treatment processes.

  17. Cryo-bioorganic chemistry: freezing effect on stereoselection of L- and DL-leucine cooligomerization in aqueous solution.

    Science.gov (United States)

    Vajda, T; Hollósi, M

    2001-02-01

    The chirality of L-/DL-leucine (50-50%) cooligomerization was investigated in liquid and frozen aqueous solutions. Cooligomerization was carried out by carbonyldiimidazole activation without initiator at an ambient (+ 22 degrees C) and frozen (- 18 degrees C) temperature, respectively. The separated samples obtained after different time intervals of treatment were completely hydrolyzed (HCl) and the diastereomeric L- and D-leucine derivates of Marfey's reagent (1-fluoro-2,4-dinitrophenyl-5-L-alanine amide) were then traced and evaluated by RP-HPLC analysis. After 9 days of oligomerization, the L-Leu content was slightly enhanced in the liquid (57%) and somewhat more enhanced in the frozen (64%) samples. After 17 days, however, the L-Leu content had decreased in the liquid (53%) and frozen (56%) conditions. These L-enantiomer amplifications indicate that an L-antipode is preferentially incorporated into the alpha-helical turn of the oligomer in the earlier stage of cooligomerization, while, later, the D-antipode is also incorporated. The role of ice in the improved stereoselection is discussed. This is the first recorded example of the effect of freezing on stereoselection. PMID:11289315

  18. Effect of potassium monopersulfate (oxone) and operating parameters on sonochemical degradation of cationic dye in an aqueous solution.

    Science.gov (United States)

    Soumia, Fassi; Petrier, Christian

    2016-09-01

    In this study, removal of Cresol Red (CR), a cationic triphenylmethane dye, by 300kHz ultrasound was investigated. The effect of additive such as potassium monopersulfate (oxone) was studied. Additionally, sonolytic degradation of CR was investigated at varying power and initial pH. RC can be readily eliminated by the ultrasound process. The obtained results showed that. Sonochemical degradation of CR was strongly affected by ultrasonic power and pH. The degradation rate of the dye increased substantially with increasing ultrasonic power in the range of 20-80W. This improvement could be explained by the increase in the number of active cavitation bubbles. The significant degradation was achieved in acidic conditions (pH=2) where the color removal was 99% higher than those observed in higher pH aqueous solutions. The ultrasonic degradation of dye was enhanced by potassium monopersulfate (oxone) addition. It was found that the degradation of the dye was accelerated with increased concentrations of oxone for a reaction time of 75min. PMID:27150780

  19. Effect of oxidant addition on the elimination of 2-naphthalenesulfonate in aqueous solutions by electron beam irradiation

    Science.gov (United States)

    Alkhuraiji, Turki S.; Karpel Vel Leitner, Nathalie

    2016-09-01

    Aromatic sulfonated compounds and naphthalene derivatives are major chemical compounds used in the industry. Electron beam irradiation of aqueous solutions of 2-naphthalenesulfonate (90 μM) was investigated under various experimental conditions. The results obtained demonstrate that the 2-NS concentration decreased dramatically on increasing the absorbed dose in the range 0-1000 Gy. The effectiveness of the radiolytic system was demonstrably enhanced by the addition of oxidants (S2O82- or H2O2). 2-NS removal was higher with S2O82- than with H2O2. For the EB, EB/H2O2, and EB/S2O82- systems, the absorbed doses for 90% elimination of 2-NS (D90) were 700, 480, and 274 Gy, respectively. 2-NS is poorly mineralized by EB but more than 35% mineralization was reached for 15 kGy when oxidants (820 μM S2O82- or 935 μM H2O2) were added. In all systems, the mineralization yield was markedly higher when air (i.e. dissolved oxygen increase) was introduced between successive doses. For 50% 2-NS removal, seven sulfonated transformation products were identified using LC/MS analyses. For the highest absorbed doses the sulfonate group in 2-NS was converted to sulfate ions in the radiolytic systems.

  20. Hydrogen bond network relaxation in aqueous polyelectrolyte solutions: the effect of temperature

    Science.gov (United States)

    Sarti, S.; Truzzolillo, D.; Bordi, F.

    2012-07-01

    Dielectric spectroscopy data over the range 100 MHz-40 GHz allow for a reliable analysis of two of the major relaxation phenomena for polyelectrolytes (PE) in water. Within this range, the dielectric relaxation of pure water is dominated by a near-Debye process at ν = 18.5 GHz corresponding to a relaxation time of τ = 8.4 ps at 25 °C. This mode is commonly attributed to the cooperative relaxation specific to liquids forming a hydrogen bond network (HBN) and arising from long range H-bond-mediated dipole-dipole interactions. The presence of charged polymers in water partially modifies the dielectric characteristics of the orientational water molecule relaxation due to a change of the dielectric constant of water surrounding the charges on the polyion chain. We report experimental results on the effect of the presence of a standard flexible polyelectrolyte (sodium polyacrylate) on the HBN relaxation in water for different temperatures, showing that the HBN relaxation time does not change by increasing the polyelectrolyte density in water, even if relatively high concentrations are reached (0.02 monomol l-1 ≤ C ≤ 0.4 monomol l-1). We also find that the effect of PE addition on the HBN relaxation is not even a broadening of its distribution, rather a decrease of the spectral weight that goes beyond the pure volume fraction effect. This extra decrease is larger at low T and less evident at high T, supporting the idea that the correlation length of the water is less affected by the presence of charged flexible chains at high temperatures.

  1. Effectiveness of Ultrasound and Ultraviolet Irradiation onDegradation of Carbaryl from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    M Khoobdel

    2010-06-01

    Full Text Available Background: Carbaryl (1-naphthyl-N-methyl carbamate is a chemical in the carbamate family used chiefly as an insecticide. It is a cholinesterase inhibitor and is toxic to humans and classified as a likely human carcinogen. In the present study, the degradation of the carbaryl pesticide was investigated in the laboratory synthetic samples of tap water, in the effect of sonolysis and photolysis processes.Methods: This study was conducted during 2006-7 in Chemistry and Biochemistry of Pesticides Laboratory in Tehran University of Medical Sciences (TUMS in Iran. The carbaryl (80% was used for preparing samples. First concentration of all samples were 4 mg/l. Sonochemical examinations in ultrasound reactor was done in two 35, 130 Hz, and 100 w, and three time. Photolysis examinations has done in the effect of 400 w lamp and moderate pressure and 6 time, then the amount of pesticide in the samples has been measured by the High Performance Thin Layer Chromatography (HPTLC method.Results: The highest degradation in photolysis process after 1 hour in the 35 KHz was 35%, and in the 130 KHz was 63%. Degradation of carbaryl at 130 KHz is higher than 35 KHz at the same time. Carbaryl elimination was increased by arise frequency and exposure time. After 8 min in photolysis, 100% omitting has been showed.Conclusion: Degradation of carbaryl in high frequency ultrasound wavelength was more than low frequency. Degradation of carbaryl in water, combination of high frequency ultrasound wave length and UV irradiation was considerably more effective than ultrasound or ultraviolet irradiation alone.

  2. [Effect of background constituents on the degradation of trace nitrobenzene in aqueous solution by catalytic ozonation].

    Science.gov (United States)

    Sun, Zhi-zhong; Zhao, Lei; Ma, Jun

    2006-02-01

    Effect of background constituents on the catalytic ozonation of nitrobenzene was investigated. Degradation rates of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation in tap water increased by 4.90%, 2.47% and 5.12% than those in distilled water respectively. The removal rate of ozonation alone increased by 6.25% with the increase of the concentration of magnesium ion (0 to approximately 8 x mg x L(-1)), but those of other two processes decreased by 11.41% and 17.64%, respectively, under the same experimental condition. Degradation efficiency of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation decreased by 4.42%, 9.38% and 12.24%, respectively, with the increase of the concentration of chloride ion (0 to approximately 40 mg x L(-1)). At the lower concentration, humic acid could accelerate the degradation of nitrobenzene, however, the reaction was retarded at higher concentrations of humic acid. The experiment also studied the influences of the applied ozone and initial concentration of nitrobenzene.

  3. Aqueous stabilization of carbon nanotubes: effects of surface oxidization and solution chemistry.

    Science.gov (United States)

    Bai, Yingchen; Wu, Fengchang; Lin, Daohui; Xing, Baoshan

    2014-03-01

    Surface oxygen functional groups can affect the morphological characteristics, aggregation kinetics, and adsorption capacity of multi-walled carbon nanotubes (MWCNTs). However, little is known about the quantitative relationship between oxygen content and the dispersion stability of MWCNTs. To investigate the effects of surface oxidization, MWCNTs were oxidized using concentrated H2SO4/HNO3 acids for 0, 1, 2, 4, and 8 h, respectively. Experimental results showed that the oxygen content of MWCNTs increased with surface oxidization time. Linear correlations were found to exist between the oxygen content, critical coagulation concentration (CCC) for NaCl, and critical coagulation pH values of MWCNTs detected by optical density at 800 nm. The CCC values for CaCl2 increased with oxygen contents for unmodified MWCNTs and lowly oxidized MWCNTs, while which decreased after further increasing the surface oxidization. CCC ratios in the presence of Ca(2+) to Na(+) were consistent with the empirical Schulze-Hardy rule for unmodified MWCNTs and lowly oxidized MWCNTs; however, which were much lower than the expected values for highly oxidized MWCNTs. Fulvic acid can clearly increase the stability of MWCNT suspension with unmodified MWCNTs and lowly oxidized MWCNTs, while it cannot affect the dispersion of highly oxidized MWCNTs. This study implied that the oxidation and presence of fulvic acid will possibly increase the mobility, exposure, bioavailability, and toxicity of MWCNTs. PMID:24323322

  4. Temperature and pH effect on reduction of graphene oxides in aqueous solution

    International Nuclear Information System (INIS)

    Reduced graphene oxides (RGOs) have usually been obtained by hydrazine reduction, but hydrazine-related compounds are corrosive, highly flammable and very hazardous, and the obtained RGOs heavily aggregated. Here we investigated extensively the effect of temperature and pH value on the structure of RGOs in hydrothermal environments without any reducing agents. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra showed that reduction rate of GOs remarkably increased with the temperature from 100 to 180 °C and with pH value from 3 to 10. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) exhibited the structural transition of the RGOs. Energy-dispersive x-ray analysis (EDX) showed the reduction degree of the RGO samples quantitatively. The results demonstrate that the GOs can be reduced controllably by a hydrothermal reduction process at pH value of 10 at 140 °C, and the large-scale RGOs are cut into small nanosheets with size from several to a few tens of nanometers with increasing temperature and duration. This study provides a feasible approach to controllably reduce GO with different nanostructures such as porous structures and quantum dots for applications in optoelectronics and biomedicals. (paper)

  5. Effects of dilute aqueous NaCl solution on caffeine aggregation

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Bhanita; Paul, Sandip, E-mail: sandipp@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology, Guwahati 781039, Assam (India)

    2013-11-21

    The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

  6. Effects of dilute aqueous NaCl solution on caffeine aggregation

    Science.gov (United States)

    Sharma, Bhanita; Paul, Sandip

    2013-11-01

    The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

  7. Formic acid enhanced effective degradation of methyl orange dye in aqueous solutions under UV-Vis irradiation.

    Science.gov (United States)

    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

  8. Effect of the physicochemical parameters of benzimidazole molecules on their retention by a nonpolar sorbent from an aqueous acetonitrile solution

    Science.gov (United States)

    Shafigulin, R. V.; Safonova, I. A.; Bulanova, A. V.

    2015-09-01

    The effect of the structure of benzimidazoles on their chromatographic retention on octadecyl silica gel from an aqueous acetonitrile eluent was studied. One- and many-parameter correlation equations were obtained by linear regression analysis, and their prognostic potential in determining the retention factors of benzimidazoles under study was analyzed.

  9. Removal of radium from aqueous sulphate solutions

    International Nuclear Information System (INIS)

    Radium is often present in ores and an aqueous solution associated with the ore may consequently contain dissolved radium. It is frequently necessary to remove radium from such solutions to reduce the total radium content to a prescribed low level before the solution can be returned to the environment. The present invention is based on the discovery that the total radium content can be reduced to a satisfactory level within a reasonable time by adding a soluble barium salt to a radium-containing sulphate solution which also contains dissolved magnesium at a pH not greater than about 0 to precipitate radium as barium radium sulphate, raising the pH to at least 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate, and separating substantially all of the precipitates from the solution

  10. Experimental and numerical study on effects of airflow and aqueous ammonium solution temperature on ammonia mass transfer coefficient.

    Science.gov (United States)

    Rong, Li; Nielsen, Peter V; Zhang, Guoqiang

    2010-04-01

    This paper reports the results of an investigation, based on fundamental fluid dynamics and mass transfer theory, carried out to obtain a general understanding of ammonia mass transfer from an emission surface. The effects of airflow and aqueous ammonium solution temperature on ammonia mass transfer are investigated by using computational fluid dynamics (CFD) modeling and by a mechanism modeling using dissociation constant and Henry's constant models based on the parameters measured in the experiments performed in a wind tunnel. The validated CFD model by experimental data is used to investigate the surface concentration distribution and mass transfer coefficient at different temperatures and velocities for which the Reynolds number is from 1.36 x 10(4) to 5.43 x 10(4) (based on wind tunnel length). The surface concentration increases as velocity decreases and varies greatly along the airflow direction on the emission surface. The average mass transfer coefficient increases with higher velocity and turbulence intensity. However, the mass transfer coefficient estimated by CFD simulation is consistently larger than the calculated one by the method using dissociation constant and Henry's constant models. In addition, the results show that the liquid-air temperature difference has little impact on the simulated mass transfer coefficient by CFD modeling, whereas the mass transfer coefficient increases with higher liquid temperature using the other method under the conditions that the liquid temperature is lower than the air temperature. Although there are differences of mass transfer coefficients between these two methods, the mass transfer coefficients determined by these two methods are significantly related.

  11. Effects of cationic ammonium gemini surfactant on micellization of PEO-PPO-PEO triblock copolymers in aqueous solution.

    Science.gov (United States)

    Wang, Ruijuan; Tang, Yongqiang; Wang, Yilin

    2014-03-01

    Effects of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) on the micellization of two triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), F127 (EO97PO69EO97) and P123 (EO20PO70EO20), have been studied in aqueous solution by differential scanning calorimetry (DSC), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and NMR techniques. Compared with traditional single-chain ionic surfactants, 12-6-12 has a stronger ability of lowering the CMT of the copolymers, which should be attributed to the stronger aggregation ability and lower critical micelle concentration of 12-6-12. The critical micelle temperature (CMT) of the two copolymers decreases as the 12-6-12 concentration increases and the ability of 12-6-12 in lowering the CMT of F127 is slightly stronger than that of P123. Moreover, a combination of ITC and DLS has shown that 12-6-12 binds to the copolymers at the temperatures from 16 to 40 °C. At the temperatures below the CMT of the copolymers, 12-6-12 micelles bind on single copolymer chains and induce the copolymers to initiate aggregation at very low 12-6-12 concentration. At the temperatures above the CMT of the copolymers, the interaction of 12-6-12 with both monomeric and micellar copolymers leads to the formation of the mixed copolymer/12-6-12 micelles, then the mixed micelles break into smaller mixed micelles, and finally free 12-6-12 micelles form with the increase of the 12-6-12 concentration. PMID:24528103

  12. Zeolites as alcohol adsorbents from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  13. Does Dimeric Melittin Occur in Aqueous Solutions?

    OpenAIRE

    Schubert, D; Pappert, G.; Boss, K.

    1985-01-01

    Melittin, a peptide from bee venom, is known to undergo a monomer / tetramer conversion in aqueous solutions. We have studied the possible participation of dimers in the association equilibrium of melittin by sedimentation equilibrium experiments in the analytical ultracentrifuge and subsequent mathematical analysis of the concentration distributions obtained. It was found that the dimeric state is not significantly populated, the contribution of dimer to the total peptide weight probably bei...

  14. Aqueous solution dispersement of carbon nanotubes

    Science.gov (United States)

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

    2011-01-01

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

  15. Structure of aqueous sodium perchlorate solutions.

    Science.gov (United States)

    General, Ignacio J; Asciutto, Eliana K; Madura, Jeffry D

    2008-12-01

    Salt solutions have been the object of study of many scientists through history, but one of the most important findings came along when the Hofmeister series were discovered. Their importance arises from the fact that they influence the relative solubility of proteins, and solubility is directly related to one of today's holy grails: protein folding. In this work we characterize one of the more-destabilizing salts in the series, sodium perchlorate, by studying it as an aqueous solution at various concentrations ranging from 0.08 to 1.60 mol/L. Molecular dynamics simulations at room temperature permitted a detailed study of the organization of solvent and cosolvent, in terms of its radial distribution functions, along with the study of the structure of hydrogen bonds in the ions' solvation shells. We found that the distribution functions have some variations in their shape as concentration changes, but the position of their peaks is mostly unaffected. Regarding water, the most salient fact is the noticeable (although small) change in the second hydration shell and even beyond, especially for g(O(w)***O(w)), showing that the locality of salt effects should not be restricted to considerations of only the first solvation shell. The perturbation of the second shell also appears in the study of the HB network, where the difference between the number of HBs around a water molecule and around the Na(+) cation gets much smaller as one goes from the first to the second solvation shell, yet the difference is not negligible. Nevertheless, the effect of the ions past their first hydration shell is not enough to make a noticeable change in the global HB network. The Kirkwood-Buff theory of liquids was applied to our system, in order to calculate the activity derivative of the cosolvent. This coefficient, along with a previously calculated preferential binding, allowed us to establish that if a folded AP peptide is immersed in the studied solution, becoming the solute, then

  16. Effect of electrolytes on surface tension and surface adsorption of 1-hexyl-3-methylimidazolium chloride ionic liquid in aqueous solution

    International Nuclear Information System (INIS)

    Surface and bulk properties of 1-hexyl-3-methylimidazolium chloride [C6mim][Cl] as an ionic liquid (IL) have been investigated by surface tension and electrical conductivity techniques at various temperatures. Results reveal that the ionic liquid behaves as surfactant-like and aggregates in aqueous solution. Critical aggregation concentration (cac) values obtained by conductivity and surface tension measurements are in good agreement with values found in the literature. A series of important and useful adsorption parameters including cac, surface excess concentration (Γ), and minimum surface area per molecule (Amin) at the air + water interface were estimated from surface tension in the presence and absence of different electrolytes. Obtained data show that the surface tension as well as the cac of [C6mim][Cl] is reduced by electrolytes. Also, values of surface excess concentration (Γ) show that the IL ions in the presence of electrolyte have much larger affinity to adsorption at the surface and this affinity increased in aqueous electrolyte solution in the order of I- > Br- > Cl- for counter ion of salts that was explained in terms of a larger repulsion of chloride anions from interface to the bromide and iodide anion as well as difference in their excess polarizability.

  17. Removal of Phosphate from Aqueous Solution with Modified Bentonite

    Institute of Scientific and Technical Information of China (English)

    唐艳葵; 童张法; 魏光涛; 李仲民; 梁达文

    2006-01-01

    Bentonite combined with sawdust and other metallic compounds was used to remove phosphate from aqueous solutions in this study. The adsorption characteristics of phosphate on the modified bentonite were investigated, including the effects of temperature, adsorbent dosage, initial concentration of phosphate and pH on removal of phosphate by conducting a series of batch adsorption experiments. The results showed that 98% of phosphate removal rate was obtained since sawdust and bentonite used in this investigation were abundantly and locally available. It is concluded that modified bentonite is a relatively efficient, low cost and easily available adsorbent for the removal of phosphate from aqueous solutions.

  18. OPTICAL PROPERTIES OF CARBAMIDE AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    E. V. Avramenko

    2016-03-01

    Full Text Available Subject of Research. The paper presents the results of measurements of refractometric properties (refractive index n, its temperature factor dn/dt and the ultraviolet spectral absorption in carbonic acid diamide aqueous solutions (carbamide depending on solid residue mass fraction md = 0-50 % and on temperaturet = 10-70 °C.Method of Research. Laboratory methods ofliquid-phase medium refractometry and ultraviolet spectrophotometry were applied for the research. We carried out computational modeling of electronic states spectrum for the carbonic acid diamide molecule and theoretical calculation of the fundamental electronic absorption of the molecule in the ultraviolet wavelenght region.Main Results. We have established that the solution concentration md has a nonlinear character and may be represented by the quadratic polynomial with the error Δn= ± 0,0005. We have shown the refractive indexdependence on temperature n(t changes in linear fashion att = 10-70 °C.At that, the inclination of lines n(t increases at the increase of md; so, the temperature factor dn/dt may be approximated by the quadratic polynomial. Transmission spectra of solutions in the spectral region λ= 225-760 nm have no special features except for the sharp edge in the short-wavelength region; the fundamental electronic absorptionis responsible for it. We have established that dispersion dependences of the refraction index n(λ;md in aqueous solutions of carbamide at λ= 360-760 nm and at md = 0-50 % may be calculated with the satisfactory error without additional adjustable parameters from the ultraviolet absorption data in terms of the one-dimentional oscillator Lorentz model.PracticalRelevance. Representedmeasurements of carbonic acid diamide aqueous solutions optical properties may be applied for the adjustment and calibration of commercial refractometers at processing lines of the AdBlue reagent manufacture for the selective catalytic reduction (SCR of motor transport

  19. 21 CFR 524.1200b - Kanamycin ophthalmic aqueous solution.

    Science.gov (United States)

    2010-04-01

    ... § 524.1200b Kanamycin ophthalmic aqueous solution. (a) Specifications. The drug, which is in an aqueous solution including suitable and harmless preservatives and buffer substances, contains 10 milligrams of... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Kanamycin ophthalmic aqueous solution....

  20. γ-radiation induced tetracycline removal in an aqueous solution

    International Nuclear Information System (INIS)

    Degradation effect of tetracycline (TC) by γ-radiation was investigated in an aqueous solution. The effects of initial concentrations of TC, pH values, combining with H2O2 or CH3OH on degradation of TC were studied. Results showed that TC can be effectively degradated by γ-irradiation in an aqueous solution. Degradation of TC could be remarkably improved both in acid solution and alkaline solution, especially when pH value was 9.0. In addition, H2O2 could gently promote degradation of TC induced by γ-radiation. While, CH3OH markedly restrained degradation of TC induced by γ-radiation. The degradation mechanism of TC was supposed by results of quantum chemical calculations and LC-MS. Results proved that degradation of TC induced by γ-radiation was mainly ascribed to · OH oxidation. (authors)

  1. Modeling reactive geochemical transport of concentrated aqueous solutions

    Science.gov (United States)

    Zhang, Guoxiang; Zheng, Zuoping; Wan, Jiamin

    2005-02-01

    Aqueous solutions with ionic strength larger than 1 M are usually considered concentrated aqueous solutions. These solutions can be found in some natural systems and are also industrially produced and released into accessible natural environments, and as such, they pose a big environmental problem. Concentrated aqueous solutions have unique thermodynamic and physical properties. They are usually strongly acidic or strongly alkaline, with the ionic strength possibly reaching 30 M or higher. Chemical components in such solutions are incompletely dissociated. The thermodynamic activities of both ionic and molecular species in these solutions are determined by the ionic interactions. In geological media the problem is further complicated by the interactions between the solutions and sediments and rocks. The chemical composition of concentrated aqueous solutions when migrating through the geological media may be drastically altered by these strong fluid-rock interactions. To effectively model reactive transport of concentrated aqueous solutions, we must take into account the ionic interactions. For this purpose we substantially extended an existing reactive transport code, BIO-CORE2D©, by incorporating a Pitzer ion interaction model to calculate the ionic activity. In the present paper, the model and two test cases of the model are briefly introduced. We also simulate a laboratory column experiment in which the leakage of highly alkaline waste fluid stored at Hanford (a U.S. Department of Energy site, located in Washington State) was studied. Our simulation captures the measured pH evolution and indicates that all the reactions controlling the pH evolution, including cation exchanges and mineral dissolution/precipitation, are coupled.

  2. Micelles and gels of oxyethylene-oxybutylene diblock copolymers in aqueous solution: The effect of oxyethylene-block length

    DEFF Research Database (Denmark)

    Derici, L.; Ledger, S.; Mai, S.M.;

    1999-01-01

    Block copolymer E(90)B(10) (E = oxyethylene, B = oxybutylene) was synthesised and characterised by gel permeation chromatography and (13)C NMR spectroscopy. Dynamic light scattering (DLS) and static light scattering (SLS) were used to characterise the micelles in solution (both in water and in aq......Block copolymer E(90)B(10) (E = oxyethylene, B = oxybutylene) was synthesised and characterised by gel permeation chromatography and (13)C NMR spectroscopy. Dynamic light scattering (DLS) and static light scattering (SLS) were used to characterise the micelles in solution (both in water...... and in aqueous 0.2 mol dm(-3) K(2)SO(4)), yielding the micellar association numbers, the hydrodynamic and thermodynamic radii, and related expansion factors. Micellar parameters were also obtained by small-angle neutron scattering (SANS) for solutions of a similar copolymer, E(86)B(10), in water, i...... of water in the micelle core. Moderately concentrated solutions of copolymer E(90)B(10) were studied in the gel state by small-angle X-ray scattering (SAXS) in tandem with rheology (oscillatory shear). Values for the dynamic elastic modulus (G') of the gels significantly exceeded 10(4) Pa across the range...

  3. EFFECTS OF NH4CI ON THE INTERACTION BETWEEN POLY(ETHYLENE OXIDE)AND IONIC SURFACTANTS IN AQUEOUS SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The interaction of poly(ethylene oxide)(PEO)with the ionic surfactants,sodium dodecylsulfate(SDS)and cetyltrimethylammonium chloride(CTAC)respectively,in aqueous solutions containing a certain concentration of NH4Cl,is studied by the viscosity measurement.It has been found that the ion-dipole interaction between PEO and ionic surfactants is changed considerably by the organic salt.For anionic surfactant of SDS,the addition of NH4Cl into solution strengthens the interaction between PEO and the headgroup of SDS.On the other hand,for cationic surfactant of CTAC,the interaction between PEO and the headgroup of CTAC is screened significantly by NH4Cl dissolved in solution.These findings may potentially be attributed to the negative property of the oxygen group of the PEO chain.In the presence of NH4Cl,the cationic ions of the organic salt bind to the oxygen group of the PEO chain so that PEO can be referred to as a pseudopolyelectrolyte in solution.

  4. Density of aqueous solutions of CO2

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Julio E.

    2001-10-10

    In this report, we present a numerical representation for the partial molar volume of CO2 in water and the calculation of the corresponding aqueous solution density. The motivation behind this work is related to the importance of having accurate representations for aqueous phase properties in the numerical simulation of carbon dioxide disposal into aquifers as well as in geothermal applications. According to reported experimental data the density of aqueous solutions of CO2 can be as much as 2-3% higher than pure water density. This density variation might produce an influence on the groundwater flow regime. For instance, in geologic sequestration of CO2, convective transport mixing might occur when, several years after injection of carbon dioxide has stopped, the CO2-rich gas phase is concentrated at the top of the formation, just below an overlaying caprock. In this particular case the heavier CO2 saturated water will flow downward and will be replaced by water with a lesser CO2 content.

  5. Effect of sodium phosphate salts on the thermodynamic properties of aqueous solutions of poly(ethylene oxide) 6000 at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)], E-mail: rahsadeghi@yahoo.com; Hosseini, Rahim; Jamehbozorg, Bahman [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2008-09-15

    Precise density, sound velocity, water activity, and phase diagram measurements have been carried out on polyethylene oxide (PEO) in aqueous solutions of sodium di-hydrogen phosphate, di-sodium hydrogen phosphate, and tri-sodium phosphate over a range of temperatures at atmospheric pressure. The experimental density and sound velocity data are used to calculate the apparent specific volume and isentropic compressibility as a function of temperature and concentration. It was found that both of the apparent specific volume and isentropic compressibility of PEO in aqueous solutions increase by increasing temperature and charge on the anion of electrolytes. The results show that the slope of constant water activity lines increased with increasing the temperature and charge on the anion of electrolytes and the vapour pressure depression for an aqueous (PEO + sodium phosphate) system is more than the sum of those for the corresponding binary solutions. Furthermore, the effect of temperature and type of anion of salt on the salting-out effect of polyethylene oxide by sodium phosphate salts has been studied.

  6. NIR Spectroscopic Properties of Aqueous Acids Solutions

    Directory of Open Access Journals (Sweden)

    Mohd Zubir MatJafri

    2012-06-01

    Full Text Available Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R2 above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918–925 nm and 990–996 nm, while at 975 nm for water.

  7. Optical manipulation of proteins in aqueous solution

    International Nuclear Information System (INIS)

    Optical trapping of lysozyme, cytochrome c, or myoglobin based on photon pressure generated by focusing 1064 nm laser beam in an aqueous solution was explored. For all the proteins, microparticle formation was observed at the focal point under an optical microscope. Furthermore, the microparticles were identified to the molecular assemblies of the corresponding protein by means of confocal Raman microspectroscopy. For lysozyme, molecular clusters in solution were optically trapped to form the microparticle and it took more than 1 h to produce the microparticle. By contrast, molecular assembling proceeded within 1 min for cytochrome c and myoglobin. Since heme in cytochrome c or myoglobin would have a high polarizability, that would contribute to rapid assembling of the protein. Thus we demonstrated that a focused laser beam was a powerful tool to manipulate protein molecules in solution.

  8. The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat, E-mail: rsadeghi@uok.ac.i [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Golabiazar, Roonak [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Shekaari, Hemayat [Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2010-04-15

    The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C{sub 4}mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid-liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C{sub 4}mim][Br]) and tri-sodium citrate (Na{sub 3}Cit) are taken. The apparent molar volume of transfer of [C{sub 4}mim][Br] from water to aqueous solutions of Na{sub 3}Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C{sub 4}mim][Br] from water to aqueous solutions of Na{sub 3}Cit have negative values. The effects of temperature and the addition of Na{sub 3}Cit and [C{sub 4}mim][Br] on the liquid-liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na{sub 3}Cit triggers a salting-out effect, leading to significant upward shifts of the liquid-liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of

  9. Adsorption of lead ions from aqueous solutions using clinoptilolite

    OpenAIRE

    Golomeova, Mirjana; Zendelska, Afrodita; Krstev, Boris; Golomeov, Blagoj; Blažev, Krsto; Krstev, Aleksandar

    2014-01-01

    The adsorption of lead ions from synthetic aqueous solutions was performed by using natural zeolite (clinoptilolite). In order to determine the effectivity of clinoptilolite a series of experiments were performed under batch conditions from single ion solutions. Experiments were carried out at different initial concentration of lead ions, different initial pH values and different adsorbent mass. The adsorption kinetics is reasonably fast. It means that in the first 20 min approximately 90...

  10. Removal of azo dye from aqueous solutions using chitosan

    OpenAIRE

    Zuhair Jabbar; G. Hadi Ferdoos Sami; A , Angham

    2014-01-01

    Adsorption of Congo Red (CR) from aqueous solution onto chitosan was investigated in a batch system. The effects of solution pH, initial dye concentration, and temperature were studied. Results indicated that chitosan could be used as a biosorbent to remove the azo dyes from contaminated water. Synthesize of chitosan involved three main stages as preconditioning, demineralization, deproteinization and deacetylation. Chitosan was characterized using Fourier Transform Infrared Spectroscopy (FTI...

  11. The effect of surfactants on the ozonation of o-cresol in aqueous solutions in a rotating packed contactor.

    Science.gov (United States)

    Ku, Young; Ji, Yan-Shiun; Chen, Hua-Wei; Chou, Yiang-Chen; Chang, Ching-Yuan

    2010-02-01

    Steady-state dissolved ozone concentrations were maintained relatively constant for experiments on ozone dissolution conducted in the presence of various amounts of sodium dodecyl sulphate (SDS) and Triton X-100 (TX-100), an anionic surfactant and a nonionic surfactant, respectively. Ozonation in a rotating packed contactor has been shown to be feasible for achieving nearly complete decomposition of o-cresol within about 10 minutes of reaction time for most experiments conducted. The temporal decomposition behaviour of o-cresol in aqueous solution by ozonation was described by a two-step pseudo-first-order reaction kinetics. Even though the presence of SDS and TX-100 slightly affected the decomposition rate constant of o-cresol by ozonation in the rotating packed contactor, the mineralization of total organic carbon was apparently reduced with the addition of SDS and TX-100.

  12. Effect of Counterion and Configurational Entropy on the Surface Tension of Aqueous Solutions of Ionic Surfactant and Electrolyte Mixtures

    Directory of Open Access Journals (Sweden)

    Youichi Takata

    2010-04-01

    Full Text Available In order to clarify the adsorption behavior of cationic surfactants on the air/aqueous electrolyte solution surface, we derived the theoretical equation for the surface tension. The equation includes the electrical work required for charging the air/water surface and the work attributable to the configurational entropy in the adsorbed film. By fitting the equation to the experimental data, we determined the binding constant between adsorbed surfactant ion and counterion, and found that the bromide ions, rather than the chloride ions, are preferentially adsorbed by the air/water surface. Furthermore, it was suggested that the contribution of configurational entropy to the surface tension is predominant in the presence of electrolytes because of the increase in the surface density of surfactant molecules associated with decreasing the repulsive interaction between their hydrophilic groups.

  13. Peach-nut Shells-An Effective and Low Cost Adsorbent for the Removal of Endosulfan from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    G. Z. Memon

    2009-12-01

    Full Text Available In the present studies the adsorption efficiency of peach nut shells for the removal of endosulfan from aqueous solutions has been investigated. The adsorption of endosulfan has been studied as a function of contact time, concentration and temperature. Maximum adsorption (95 ± 1% was achieved for 0.24 × 10−4 mol dm−3 of endosulfan solution, using 0.1 g of adsorbent in 20 ml of solution for 30 min agitation time at pH 6. The Freundlich and Langmuir isotherms fit the equilibrium data satisfactory and their constants, adsorption intensity 1/n (0.36, multilayer adsorption capacity Cm 6.5 ± 0.26 mmol g−1, and monolayer adsorption capacity Q 0.27 ± 0.03 mmol g−1, have been evaluated. Thermodynamics parameters namely change in enthalpy ∆H, Gibbs free energy ∆G and entropy ∆S, were calculated. The negative values of ∆G and positive value of ∆H indicate that the adsorption process is spontaneous and endothermic in nature and positive value of entropy ∆S confirms the possibility of the favorable adsorption. The developed adsorption method has been employed to surface water samples.

  14. Drag enhancement of aqueous electrolyte solutions in turbulent pipe flow.

    Science.gov (United States)

    Doherty, Andrew P; Spedding, Peter L; Chen, John J J

    2010-04-22

    Detailed experimental results are presented for both laminar and turbulent flow of aqueous solutions in pipes of different diameters. Nonelectrolytes, such as sugar solutions followed the normal Moody pressure loss curves. Drag enhancement was demonstrated for turbulent flow of aqueous electrolyte solutions but not for laminar flow. The increased pressure drop for turbulent electrolyte flow was attributed to an electroviscous effect and a theory was developed to explain the drag enhancement. The increased pressure drop for the turbulent region of flow was shown to depend on the Debye length in the laminar sublayer on the pipe wall. Reasonable predictions of the increasing drag were obtained for both 1:1 and 2:1 electrolyte solutions. PMID:20337452

  15. Corrosion effects of the interreaction of 6061 aluminum with aqueous mixtures and solutions of selected HE`s

    Energy Technology Data Exchange (ETDEWEB)

    Clink, G.L. [Sandia Labs., Albuquerque, NM (United States)

    1971-12-31

    The behavior of several selected HE and HE-component materials in aqueous media in contact with 6061 aluminum has been studied via conductance, cathodic tendencies (cell EMF measurements), pH, and visual analysis (photomicrographs) of the 6061 electrodes and media contacts rods. Addition of orthophthalic acid (OPA) to the media was also made to study potential corrosive effects possibly due to some breakdown of the polyphthalate systems in contact with these materials. Overall assessment of data is not made at this time due to the interrelationship of these data with data which should be obtained from unfinished portions of the study.

  16. Effects of pH on the stability of cyanidin and cyanidin 3-O-β-glucopyranoside in aqueous solution

    Directory of Open Access Journals (Sweden)

    Rakić Violeta P.

    2015-01-01

    Full Text Available The colour variation, colour intensity and stability at various pH values (2.0, 4.0, 7.0 and 9.0 of cyanidin 3-O-β-glucopyranoside (Cy3Glc and its aglycone cyanidin was investigated during a period of 8 hours storage at 25ºC. Our data showed that pH of aqueous solution had impact on spectroscopic profile of cyanidin and Cy3Glc. Beginning with the most acidic solutions, increasing the pH induce bathochromic shifts of absorbance maximum in the visible range for all examined pH values (with the exception pH 4.0 for cyanidin, while the presence of the 3-glucosidic substitution induce hypsochromic shift. Compared to cyanidin, Cy3Glc has higher colour intensity and higher stability in the whole pH range, except at pH 7.0. The 3-glucosidic substitution influences on the colour intensity of Cy3Glc in the alkaline region. After 8-hour incubation of Cy3Glc and cyanidin at pH 2.0 and 25 ºC, 99% of Cy3Glc and only 27% of cyanidin remained unchanged.

  17. Preparation and characterization of iron-copper binary oxide and its effective removal of antimony(III) from aqueous solution.

    Science.gov (United States)

    Li, Yongchao; Geng, Bing; Hu, Xiaoxian; Ren, Bozhi; Hursthouse, Andrew S

    2016-01-01

    An Fe-Cu binary oxide was fabricated through a simple co-precipitation process, and was used to remove Sb(III) from aqueous solution. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and N2 adsorption-desorption measurements demonstrated that the Fe-Cu binary oxide consisted of poorly ordered ferrihydrite and CuO, and its specific surface area was higher than both iron oxide and copper oxide. A comparative test indicated that Fe/Cu molar ratio of prepared binary oxide greatly influenced Sb(III) removal and the optimum Fe/Cu molar ratio was about 3/1. Moreover, a maximum adsorption capacity of 209.23 mg Sb(III)/g Fe-Cu binary oxide at pH 5.0 was obtained. The removal of Sb(III) by Fe-Cu binary oxide followed the Freundlich adsorption isotherm and the pseudo-second-order kinetics in the batch study. The removal of Sb(III) was not sensitive to solution pH. In addition, the release of Fe and Cu ions to water was very low when the pH was greater than 6.0. X-ray photoelectron spectroscopy analysis confirmed that the Sb(III) adsorbed on the surface was not oxidized to Sb(V). PMID:27438244

  18. Pulse Radiolysis of Aqueous Thiocyanate Solution

    International Nuclear Information System (INIS)

    The pulse radiolysis of N2O saturated aqueous solutions of KSCN was studied under neutral pH conditions. The observed optical absorption spectrum of the SCN#lgbullet# radical in solution is more complex than previously reported, but it is in good agreement with that measured in the gas phase. Kinetic traces at 330 nm and 472 nm corresponding to SCN#lgbullet# and (SCN)2#lgbullet#-, respectively, were fit using a Monte Carlo simulation kinetic model. The rate coefficient for the oxidation of SCN- ions by OH radicals, an important reaction used in competition kinetics measurements, was found to be 1.4 ± 0.1 x 1010 M-1 s-1, about 30% higher than the normally accepted value. A detailed discussion of the reaction mechanism is presented

  19. Effective improvement in optical properties of colloidal CdTe@ZnS quantum dots synthesized from aqueous solution

    Science.gov (United States)

    Wang, Yongbo; Si, Boni; Lu, Siwu; Ma, Xuan; Liu, Enzhou; Fan, Jun; Li, Xinghua; Hu, Xiaoyun

    2016-09-01

    Efficient synthesis of high-quality quantum dots (QDs) with excellent optical properties by aqueous synthesis is still of great significance for extended optical applications. Herein we highlight the advantages in optical properties of colloidal CdTe@ZnS QDs prepared by a facile and highly effective aqueous synthesis method. These achievements were realized by delicate manipulation of the conditions involved in nucleation and the growth process. Transmission electron microscopy (TEM) images indicated the QDs were uniform size and well dispersible. The emission peaks of the as-prepared QDs could shift from 496 to 698 nm with narrow full width at half maximum (FWHM), and the corresponding fluorescent color changed from green to red. Moreover, the emission could even reach to the near-infrared (NIR) region (706-796 nm) by extending the reaction time. The highest photoluminescence (PL) quantum yield (QY) of the QDs could reach to 60%, and the average of FWHM was about 55 nm. To address the problem of wide size-distribution in PL QY decrease and FWHM broadening, the colloids of QDs prepared at long reaction time (above 3 h) were centrifuged (12 000 r min-1). In addition, the assessment of QD cytotoxicity indicated the CdTe@ZnS QDs were much less cytotoxic and showed good biocompatibility. Compared with organic synthesis, our aqueous synthesis of QDs could be carried out efficiently on a large scale and showed good batch-to-batch reproducibility. The as-prepared CdTe@ZnS QDs exhibited excellent optical properties and hold a good potential to be applied in optoelectronic and biological applications.

  20. Nanoporous activated carbon cloth for capacitive deionization of aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Han-Jun [Department of Materials Science, Hanseo University, Seosan, 352-820 (Korea, Republic of); Lee, Jong-Ho [Department of Chemistry, Hanseo University, Seosan, 352-820 (Korea, Republic of); Ahn, Hong-Joo [Korea Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Jeong, Yongsoo [Korea Institute of Machinery and Materials, Changwon, 641-010 (Korea, Republic of); Kim, Young-Jig [Department of Metallurgical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Chi, Choong-Soo [School of Advanced Materials Engineering, Kookmin University, Seoul, 136-702 (Korea, Republic of)]. E-mail: cschi@kookmin.ac.kr

    2006-09-25

    Activated nanostructured-carbon cloths with a high ratio of surface area to volume are used as electrode for capacitive deionization. The electrochemical properties on capacitive deionization for NaCl solution have been investigated to improve efficiency of capacitive deionization properties from aqueous solution, employing chemical surface-modification by etching in alkaline and acidic solution. The removal efficiency of inorganic salts of activated carbon cloths by chemical modification significantly increased. Specially the carbon cloth surface modified in HNO{sub 3} showed an effect of improvement in the CDI efficiency due to not only ion adsorption by an electric double layer, but also electron transfer by Faradaic reaction.

  1. Structural parameters of concentrated aqueous solutions of lithium chloride under extreme conditions from the data of integral equations method. The effect of isothermal compression

    International Nuclear Information System (INIS)

    Structure formation of aqueous solutions LiCl:nH2O (n = 3.15, 8.05, 14.90) under conditions of isothermal compression (T 523 K, P 100-1500 bar) was studied in the framework of integral equations method. It was ascertained that isothermal compression produces a weak effect on the structure of volumetric solvent in the systems considered. Irrespective of solution concentration the tetrahedral ordering of water molecules is absent in the entire range of pressures, while the number of OH bonds actually does not change. In all the solutions compression involves inessential strengthening of coordinating ability of both ions. In the context described a slight growth of the number of hydrate-separated ionic pairs and an insignificant decrease in the number of contact ionic pairs are observed

  2. Effective Removal of Copper Ions and Dyes from Aqueous Solutions by Polymeric Nanoparticles Prepared by Gamma Radiation

    International Nuclear Information System (INIS)

    In the present investigation, gamma radiation was used to prepare poly(vinyl alcohol/acrylamide) magnetic iron-silver nanoparticles, (PVA/AAm)-Fe-Ag hydrogels as adsorbent materials for waste water treatment. The prepared hydrogels were characterized by infrared spectroscopy (FT- IR) and scanning electron microscope (SEM). The thermal gravimetric analysis (TGA) results confirm the thermal stability enhancement by incorporation of the nanometals into the prepared hydrogel. The EPR results showed that the P(PVA/AAm)-Fe hydrogels exhibited larger magnetization than the P(PVA/AAm)-Fe-Ag hydrogels. The size measurement of nanoparticles by transmission electron microscopy (TEM) which compared with the results of the dynamic light scattering (DLS) confirmed that the prepared hydrogels were in the nanoscale. The swelling percent behavior of P(PVA/AAm) -Fe-Ag hydrogel nanoparticles at different ph media was carried out. The results of the adsorption studies indicated high adsorption capacity of P(PVA/AAm)-Fe - Ag nanoparticles toward the removal of Cu+2, methylene blue (MB) and methylgreen (MG) dyes from aqueous solutions

  3. Effect of electrostatic boundary conditions and system size on the interfacial properties of water and aqueous solutions

    Science.gov (United States)

    Spohr, E.

    1997-10-01

    The consequences of the choice of electrostatic boundary conditions on the interfacial properties of water and on the free energy of ion adsorption from aqueous solution have been investigated. The Ewald summation method for lattices, which are periodic in two dimensions, is considered to be the most adequate method in slabs of finite thickness in one dimension. In agreement with the physics of the problem a field-free region in the bulk phases is observed. The use of spherical truncation methods like the shifted-force method leads to unphysical results. The electrostatic potential depends on the size of the system. Ewald summation methods for three-dimensional lattices lead to results in qualitative agreement with the corresponding two-dimensional lattice sum. The computed value of the electrostatic potential depends on an additional parameter, namely the lattice constant c in the direction perpendicular to the interface. The results for Ewald summation in three dimensions converge to the results for Ewald summation in two dimensions for large c, the shifted-force results converge to the same limit, when the surface area of the simulation cell becomes very large and the cut-off distance increases accordingly.

  4. Sono-Fenton process for metronidazole degradation in aqueous solution: Effect of acoustic cavitation and peroxydisulfate anion.

    Science.gov (United States)

    Ammar, Hafedh Belhadj

    2016-11-01

    The present work investigates the application of an improved treatment approach based on the ultrasound irradiation as clean technology driven Fenton in the presence of peroxydisulfate anion (S2O8(2-)) for the removal of metronidazole (MTZ) from aqueous solution. The sono-generation of sulfate radicals (SO4(-)) as a stronger oxidizing agent from S2O8(2-) (redox potential of 2.6V) has improved the degradation of MTZ. However, no studies have focused on the removal of MTZ using peroxydisulfate anion under sono-Fenton process. The MTZ concentration measurement during the processing allowed the evaluation of the kinetics of organic matter decay. The results have shown that the degradation of MTZ dependent on Fe(2+)/H2O2 molar ratio, temperature and S2O8(2-) concentration. The MTZ concentration decay follows pseudo first-order kinetics, within the range studied. Sono-Fenton process using low iron and hydrogen peroxide doses was proved to be an efficient method for the elimination of MTZ with high degradation rates. At optimum conditions, 96% of MTZ removal was achieved at 60°C in the presence of 1mM of S2O8(2-). PMID:27245967

  5. Phragmites karka as a Biosorbent for the Removal of Mercury Metal Ions from Aqueous Solution: Effect of Modification

    Directory of Open Access Journals (Sweden)

    Muhammad Hamid Raza

    2015-01-01

    Full Text Available Batch scale studies for the adsorption potential of novel biosorbent Phragmites karka (Trin, in its natural and treated forms, were performed for removal of mercury ions from aqueous solution. The study was carried out at different parameters to obtain optimum conditions of pH, biosorbent dose, agitation speed, time of contact, temperature, and initial metal ion concentration. To analyze the suitability of the process and maximum amount of metal uptake, Dubinin-Radushkevich (D-R model, Freundlich isotherm, and Langmuir isotherm were applied. The values of qmax for natural and treated biosorbents were found at 1.79 and 2.27 mg/g, respectively. The optimum values of contact time and agitation speed were found at 50 min and 150 rpm for natural biosorbent whereas 40 min and 100 rpm for treated biosorbent, respectively. The optimum biosorption capacities were observed at pH 4 and temperature 313 K for both natural P. karka and treated P. karka. RL values indicate that comparatively treated P. karka was more feasible for mercury adsorption compared to natural P. karka. Both pseudo-first-order and pseudo-second-order kinetic models were applied and it was found that data fit best to the pseudo-second-order kinetic model. Thermodynamic studies indicate that adsorption process was spontaneous, feasible, and endothermic.

  6. Effect of liquid-sheet thickness on detection sensitivity for laser-induced breakdown spectroscopy of aqueous solution.

    Science.gov (United States)

    Ohba, Hironori; Saeki, Morihisa; Wakaida, Ikuo; Tanabe, Rie; Ito, Yoshiro

    2014-10-01

    For aqueous-solution-based elemental analysis, we used a thin liquid sheet (μm-scale thickness) in laser-induced breakdown spectroscopy with nanosecond laser pulses. Laser-induced plasma is emitted by focusing a pulsed Nd:YAG laser (1064 nm) on a 5- to 80-μm-thick liquid sheet in air. To optimize the conditions for detecting elements, we studied how the signal-to-background ratio (SBR) for Hα Balmer and Na-neutral emission lines depends on the liquid-sheet thickness. The SBR of the Hα Balmer and Na-neutral lines was maximized for a sheet thickness of ~20 μm at the laser energy of 100 mJ. The hydrodynamics of liquid flow induced by the laser pulse was analyzed by laser flash shadowgraph imaging. Time-resolved observation of the hydrodynamics and plasma emission suggests that the dependence of the SBR on the liquid-sheet thickness is correlated with the volume of flowing liquid that interacts with the laser pulses.

  7. Functionalized polymers for binding to solutes in aqueous solutions

    Science.gov (United States)

    Smith, Barbara F.; Robison, Thomas W.

    2006-11-21

    A functionalized polymer for binding a dissolved molecule in an aqueous solution is presented. The polymer has a backbone polymer to which one or more functional groups are covalently linked. The backbone polymer can be such polymers as polyethylenimine, polyvinylamine, polyallylamine, and polypropylamine. These polymers are generally water-soluble, but can be insoluble when cross-linked. The functional group can be for example diol derivatives, polyol derivatives, thiol and dithiol derivatives, guest-host groups, affinity groups, beta-diphosphonic acids, and beta-diamides

  8. Effect of molecular weight on radiation chemical degradation yield of chain scission of γ-irradiated chitosan in solid state and in aqueous solution

    International Nuclear Information System (INIS)

    Chitosan A1, A2 and A3 with molecular weight of 471, 207 and 100 kDa respectively, produced from squid pen chitin was degraded by gamma rays in the solid state and in aqueous solution with various doses in air at ambient temperature. Effect of molecular weight on radiation chemical degradation yield of chain scission and degradation rate constants of γ-irradiated chitosan in solid state and in aqueous solution was investigated. The radiation chemical degradation yield G(s) and degradation rate values were calculated. The molecular weight changes were monitored by capillary viscometry method and the chemical structure changes were followed by UV analysis. The results showed that, the degradation of chitosan was faster in solution, than in solid state. The values of G(s) in solid state and in aqueous solution were respectively 1.1×10−8 mol/J and 0.074×10−7 mol/J for A1, 4.42×10−8 mol/J and 0.28×10−7 mol/J for A2 and 6.08×10−8 mol/J and 0.38×10−7 mol/J for A3. Degradation rate constants values ranged from 0.41×10−5 to 2.1×10−5 kGy−1 in solid state, whereas in solution they ranged from 13×10−5 to 68×10−5 kGy−1. The chitosan A3 was more sensitive to radiolysis than A1 and A2. The chain scission yield, G(s) and degradation rate constants seems to be greatly influenced by the initial molecular weight of the chitosan. Structural changes in irradiated chitosan are revealed by the apparition of absorption peaks at 261 and 295 nm, which could be attributed to the formation of carbonyl groups. In both conditions the peak intensity was higher in chitosan A3 than in A1 and A2, the oxidative products decreased with increasing molecular weight of chitosan. - Highlights: ► We investigated the effects of MW on G(s) value of γ-irradiated chitosan in solid and aqueous state. ► Chitosan with low molecular weight was more sensitive to radiolysis than high molecular weight. ► G(s) value and degradation rate seems to be greatly influenced by the

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

    Science.gov (United States)

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

    2016-09-01

    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.

  10. The Gibbs-free-energy landscape for the solute association in nanoconfined aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    赵亮; 王春雷; 方海平; 涂育松

    2015-01-01

    The theoretical model and the numerical analyses on the Gibbs-free-energy of the association states of am-phiphilic molecules in nanoconfined aqueous solutions are presented in detail. We exhibit the continuous change of the Gibbs-free-energy trend, which plays a critical role in the association states of the system transforming from the dispersion state, through the “reversible state”, and finally to the aggregation state in amphiphilic molecule solutions. Furthermore, for the“reversible state”, we present the difference in the free-energy bar-rier heights of the dispersion state and aggregation state, resulting from the competition between the entropy, which makes the solute molecules evenly disperse in the solution and the energy contribution driving the am-phiphilic molecules to aggregate into a larger cluster. These findings provide a comprehensive understanding of confinement effects on the solute association processes in aqueous solutions and may further improve the techniques of material fabrication.

  11. Polyamide nanofiltration membranes to remove aniline in aqueous solutions.

    Science.gov (United States)

    Hidalgo, A M; León, G; Gómez, M; Murcia, M D; Bernal, M D; Ortega, S

    2014-01-01

    Aniline is commonly used in a number of industrial processes. It is known to be a harmful and persistent pollutant and its presence in wastewater requires treatment before disposal. In this paper, the effectiveness of nanofiltration (NF) to remove aniline from aqueous solutions is studied in a flat membrane test module using two thin-layer composite membranes of polyamide (NF97 and NF99HF). The influence of different operational variables (applied pressure, feed concentration and pH) on the removal of aniline from synthetic aqueous solutions was analysed. The experimental NF results are compared with results previously obtained by reverse osmosis. Based on this comparative study, the effective order for aniline rejection is: HR98PP > NF97 > DESAL3B > SEPA-MS05 > NF99HF. PMID:24701913

  12. Ozone chemistry in aqueous solution : ozone decomposition and stabilisation

    OpenAIRE

    Eriksson, Margareta

    2005-01-01

    Ozone is used in many applications in the industry as an oxidising agent for example for bleaching and sterilisation. The decomposition of ozone in aqueous solutions is complex, and is affected by many properties such as, pH, temperature and substances present in the water. Additives can either accelerate the decomposition rate of ozone or have a stabilising effect of the ozone decay. By controlling the decomposition of ozone it is possible to increase the oxidative capacity of ozone. In this...

  13. Rheological properties of novel thermo-responsive polycarbonates aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    王月霞; 谭业邦; 黄晓玲

    2008-01-01

    Thermo-responsive multiblock polycarbonates were facilely synthesized by covalently binding poly(ethylene glycol)(PEG) and poly(propylene glycol)(PPG) blocks,using triphosgene as coupling agent and pyridine as catalyst.The aqueous solutions of thermo-responsive polycarbonates were investigated by rheological measurements.Steady-state shear measurements reveal that the polycarbonate solutions exhibit shear-thinning behavior and the hydrophilic content has a pronounced effect on the flow behavior of the polycarbonates aqueous solutions.The shear viscosity decreases with increasing poly(ethylene oxide)(PEO) composition.The increase of viscosity with increasing concentration is probably attributed to the formation of stronger network owing to interchain entanglement of PEO block at higher concentration.When the flow curves are fitted to the power law model,flow index is obtained to be less than 1,as exhibiting typical pesudoplastic fluid.The viscoelastic properties of the system also show close dependence on the composition of polycarbonates.Temperature sweep confirms that the multiblock polycarbonates exhibit thermo-responsive properties.For 7% aqueous solution of polycarbonate with composition ratio of EO to PO of 1/1,the sol-gel transition occurs at 37 ℃,which makes the system suitable as an injectable drug delivery system.

  14. Radiolytic degradation of malathion and lindane in aqueous solutions

    International Nuclear Information System (INIS)

    Degradation of malathion and lindane pesticides present in an aqueous solution was investigated on a laboratory scale upon gamma-irradiation from a 60Co source. The effects of pesticide group, presence of various additives and absorbed dose on efficiency of pesticide degradation were investigated. Gamma-irradiation was carried out in distilled water solutions (malathion and lindane) and in combination with humic solution (HS), nitrous oxide (N2O) and HS/N2O (lindane) over the range 0.1-2 kGy (malathion) and 5-30 kGy (lindane). Malathion was easily degraded at low absorbed doses compared to lindane in distilled water solutions. Absorbed doses required to remove 50% and 90% of initial malathion and lindane concentrations in distilled water solutions were 0.53 and 1.77 kGy (malathion) and 17.97 and 28.79 kGy (lindane), respectively. The presence of HS, N2O and HS/N2O additives in aqueous solutions, significantly improved the effectiveness of radiolytic degradation of lindane. Chemical analysis of the pesticides and the by-products resulted from the radiolytic degradation were made using a gas chromatography associated with mass spectrometry (GC-MS). Additionally, the final degradation products of irradiation as detected by ion chromatography (IC) were acetic acid and traces of some anions (phosphate and chloride).

  15. Adsorption of cadmium from aqueous solutions by perlite.

    Science.gov (United States)

    Mathialagan, T; Viraraghavan, T

    2002-10-14

    The present study examined the use of perlite for the removal of cadmium from aqueous solutions. The effects of pH and contact time on the adsorption process were examined. The optimum pH for adsorption was found to be 6.0. Residual cadmium concentration reached equilibrium in 6h and the rate of cadmium adsorption by perlite was rapid in the first hour of the reaction time. Ho's pseudo-second-order model best described the kinetics of the reaction. Batch adsorption experiments conducted at room temperature (22+/-1 degrees C) showed that the adsorption pattern followed the Freundlich isotherm model. The maximum removal of cadmium obtained from batch studies was 55%. Thomas model was used to describe the adsorption data from column studies. The results generally showed that perlite could be considered as a potential adsorbent for cadmium removal from aqueous solutions.

  16. Removal of methyl violet from aqueous solution by perlite.

    Science.gov (United States)

    Doğan, Mehmet; Alkan, Mahir

    2003-11-01

    The use of perlite for the removal of methyl violet from aqueous solutions at different concentration, pH, and temperature has been investigated. Adsorption equilibrium is reached within 1 h. The capacity of perlite samples for the adsorption of methyl violet was found to increase with increasing pH and temperature and decrease with expansion and increasing acid-activation. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. The adsorption isotherm was measured experimentally at different conditions and the experimental data were correlated reasonably well by the adsorption isotherm of Langmuir. The order of heat of adsorption corresponds to a physical reaction. It is concluded that the methyl violet is physically adsorbed onto the perlite. The removal efficiency (P) and dimensionless separation factor (R) have shown that perlite can be used for removal of methyl violet from aqueous solutions, but unexpanded perlite is more effective.

  17. Degradation of Sodium-Polyacrylate in Dilute Aqueous Solution, II

    Science.gov (United States)

    Saita, Takao; Matumura, On

    1983-08-01

    It has been found that Na-PAA molecules in dilute aqueous solution are degraded by shearing stress, oxidation and photolysis during usual viscosity measurements with a capillary viscometer. The results of previous viscosity measurements, mainly about the mechanochemical degradation in air and in air-free conditions, showed that the degradation rate increases with increasing shear stress, and with decreasing polymer concentration. In this work, the effects of the molecular weight and temperature on the degradation rate are measured using a capillary viscometer in air, and the photodegradation of Na-PAA and PAA in aqueous solution irradiated with UV light are studied by viscosity measurements in air, and by UV absorption and ESR methods. The results show that the degradation of molecules is enhanced by an increase in the molecular weight and strongly accelerated by a rise in temperature and by UV irradiation, and is accompanied by free-radical chain reactions.

  18. A lithium ion battery using an aqueous electrolyte solution.

    Science.gov (United States)

    Chang, Zheng; Li, Chunyang; Wang, Yanfang; Chen, Bingwei; Fu, Lijun; Zhu, Yusong; Zhang, Lixin; Wu, Yuping; Huang, Wei

    2016-01-01

    Energy and environmental pollution have become the two major problems in today's society. The development of green energy storage devices with good safety, high reliability, high energy density and low cost are urgently demanded. Here we report on a lithium ion battery using an aqueous electrolyte solution. It is built up by using graphite coated with gel polymer membrane and LISICON as the negative electrode, and LiFePO4 in aqueous solution as the positive electrode. Its average discharge voltage is up to 3.1 V and energy density based on the two electrode materials is 258 Wh kg(-1). It will be a promising energy storage system with good safety and efficient cooling effects. PMID:27328707

  19. A lithium ion battery using an aqueous electrolyte solution

    Science.gov (United States)

    Chang, Zheng; Li, Chunyang; Wang, Yanfang; Chen, Bingwei; Fu, Lijun; Zhu, Yusong; Zhang, Lixin; Wu, Yuping; Huang, Wei

    2016-01-01

    Energy and environmental pollution have become the two major problems in today’s society. The development of green energy storage devices with good safety, high reliability, high energy density and low cost are urgently demanded. Here we report on a lithium ion battery using an aqueous electrolyte solution. It is built up by using graphite coated with gel polymer membrane and LISICON as the negative electrode, and LiFePO4 in aqueous solution as the positive electrode. Its average discharge voltage is up to 3.1 V and energy density based on the two electrode materials is 258 Wh kg−1. It will be a promising energy storage system with good safety and efficient cooling effects. PMID:27328707

  20. A lithium ion battery using an aqueous electrolyte solution

    Science.gov (United States)

    Chang, Zheng; Li, Chunyang; Wang, Yanfang; Chen, Bingwei; Fu, Lijun; Zhu, Yusong; Zhang, Lixin; Wu, Yuping; Huang, Wei

    2016-06-01

    Energy and environmental pollution have become the two major problems in today’s society. The development of green energy storage devices with good safety, high reliability, high energy density and low cost are urgently demanded. Here we report on a lithium ion battery using an aqueous electrolyte solution. It is built up by using graphite coated with gel polymer membrane and LISICON as the negative electrode, and LiFePO4 in aqueous solution as the positive electrode. Its average discharge voltage is up to 3.1 V and energy density based on the two electrode materials is 258 Wh kg‑1. It will be a promising energy storage system with good safety and efficient cooling effects.

  1. SWELLING EQUILIBRIUM OF NONIONIC POLYACRYLAMIDE HYDROGEL IN AQUEOUS SALT SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of nonionic polyacrylamide hydrogels, using acrylamide as monomer and N,N’-methylene diacrylamide as crosslinking agent, were prepared by the free radical polymerization in aqueous solution. Swelling equilibria for the gels were carried out in aqueous solutions of NaCl, KCl, CaCl2, Na2HPO4 and K2HPO4 with concentration ranging from 10-3 to 5mol/kgH2O at 25℃. Experimental results revealed that the chlorides and phosphates cause a different behavior at higher salt concentration. The swelling ratio increases with increasing concentration of chlorides salts, while decreases with the increased phosphates salt concentration. The phenomena seem to be related to the different interactions of chloride and hydrogen phosphate ions with the network groups. Furthermore, the effects of different concentration of crosslinking agent and total monomers on gel swelling performance were also investigated.

  2. Effect of using aqueous/alcohol solution during solution doping on the physical and chemical characteristics of pre-sintered silica soot and the resultant native glass species concentration

    International Nuclear Information System (INIS)

    This paper presents the effect of solution doping on pre-sintered silica soot prepared by flame hydrolysis deposition. Additionally, the effects of using either an aqueous or alcohol solution on the soot layer, and the resultant concentration of native glass species (pre- and post-consolidation) are also discussed. Soot consisting native glass species such as SiO2, GeO2, P2O5, and B2O3 was pre-sintered with temperatures ranging from 550 deg. C to 950 deg. C before undergoing solution doping. Cross-sectional thickness of the soot layer following solution doping was measured via optical microscopy and subsequently compared with those prior to solution doping. Significant variations of GeO2 and P2O5 concentration in the soot layer after solution doping were detected via energy dispersive X-ray analysis. It was found that apart from the pre-sintered soot layer integrity during solution doping, the type of solution used plays an essential role in ensuring retention of native glass species both prior to, and following consolidation. Measurements using inductively coupled plasma atomic emission spectroscopy confirmed that significant amounts of GeO2 and P2O5 were lost during the immersion in solution stage of the process.

  3. Effect of alkyl chain length and temperature on the thermodynamic properties of ionic liquids 1-alkyl-3-methylimidazolium bromide in aqueous and non-aqueous solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)], E-mail: rahsadeghi@yahoo.com; Shekaari, Hemayat [Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Hosseini, Rahim [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2009-02-15

    The alkyl chain length of 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = propyl (C{sub 3}), hexyl (C{sub 6}), heptyl (C{sub 7}), and octyl (C{sub 8})) was varied to prepare a series of room-temperature ionic liquids (RTILs), and experimental measurements of density and speed of sound at different temperatures ranging from (288.15 to 308.15) K for their aqueous and methanolic solutions in the dilute concentration region (0.01 to 0.30) mol . kg{sup -1} were taken. The values of the compressibilities, expansivity and apparent molar properties for [C{sub n}mim][Br] in aqueous and methanolic solutions were determined at the investigated temperatures. The obtained apparent molar volumes and apparent molar isentropic compressibilities were fitted to the Redlich-Mayer and the Pitzer's equations from which the corresponding infinite dilution molar properties were obtained. The values of the infinite dilution molar properties were used to obtain some information about solute-solvent and solute-solute interactions. The thermodynamic properties of investigated ionic liquids in aqueous solutions have been compared with those in methanolic solutions. Also, the comparison between thermodynamic properties of investigated solutions and those of electrolyte solutions, polymer solutions, cationic surfactant solutions and tetraalkylammonium salt solutions have been made.

  4. Characterization of aqueous silver nitrate solutions for leakage tests

    OpenAIRE

    José Ferreira Costa; Walter Luiz Siqueira; Alessandro Dourado Loguercio; Alessandra Reis; Elizabeth de Oliveira; Cláudia Maria Coelho Alves; José Roberto de Oliveira Bauer; Rosa Helena Miranda Grande

    2011-01-01

    OBJECTIVE: To determine the pH over a period of 168 h and the ionic silver content in various concentrations and post-preparation times of aqueous silver nitrate solutions. Also, the possible effects of these factors on microleakage test in adhesive/resin restorations in primary and permanent teeth were evaluated. MATERIAL AND METHODS: A digital pHmeter was used for measuring the pH of the solutions prepared with three types of water (purified, deionized or distilled) and three brands of silv...

  5. Raman spectroscopy application to analyses of components in aqueous solutions

    Science.gov (United States)

    Li, Gang; Zhang, Guoping

    2006-09-01

    The characterization of species in aqueous solutions has presented a challenge to analytical and physical chemist, because the JR absorption of the aqueous solvent is so intense that it becomes difficult to observe the solute in the water by JR absorption. In contrast, Raman spectrum of the solute is unaffected by the water, so the weak scattering of water makes the technique well suited to aqueous samples, and the Raman spectrum exhibits well-defined bands corresponding to fundamental modes of vibration. In addition, Raman spectroscopy has some inherent advantages in aqueous solution analysis, because the spectral features of signals from different species are much more distinct, and it provides characteristic signatures for samples, such as blood, protein and cholesterol. All the advantages make Raman spectroscopy be a potential alternative for the study of aqueous solutions. Now, Raman spectroscopy has been applied to studying samples in aqueous solutions, blood serum, intracellular protein levels. Now, industrial wasted water contains many organic contaminants, and it is necessary to determine and monitor these contaminants. The paper first introduces Raman spectroscopy, and then describes its applications to determining the components in aqueous solutions, analyzes and assignes the Raman spectra of o-dichlorobenzene, o-xylene, m-xyiene and p-xylene in detail. The experimental results demonstrate that Raman spectroscopy is a particularly powerful technique for aqueous solutions analyses.

  6. ESR study on carboxymethyl chitosan radicals in an aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Saiki, Seiichi, E-mail: saiki.seiichi@jaea.go.j [Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Muroya, Yusa; Kudo, Hisaaki [Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Katsumura, Yosuke [Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1195 (Japan)

    2010-03-15

    Carboxymethyl chitosan (CMCTS) at a highly concentrated aqueous solution forms hydrogel by ionizing irradiation. To study on radiation-induced reaction mechanism of CMCTS in an aqueous solution, CMCTS radicals formed by reactions with OH radical were observed by ESR method. As a result of ESR spectral analysis, CMCTS radicals were identified as radicals on carboxymethyl groups.

  7. Specific Na+ and K+ Cation Effects on the Interfacial Water Molecules at the Air/Aqueous Salt Solution Interfaces Probed with Non-resonant Second Harmonic Generation (SHG)

    CERN Document Server

    Bian, Hong-tao; Guo, Yuan; Wang, Hong-fei

    2008-01-01

    Here we report the polarization dependent non-resonant second harmonic generation (SHG) measurement of the interfacial water molecules at the aqueous solution of the following salts: NaF, NaCl, NaBr, KF, KCl, and KBr. Through quantitative polarization analysis of the SHG data,the orientational parameter D value and the relative surface density of the interfacial water molecules at these aqueous solution surfaces were determined. From these results we found that addition of each of the six salts caused increase of the thickness of the interfacial water layer at the surfaces to a certain extent. Noticeably, both the cations and the anions contributed to the changes, and the abilities to increase the thickness of the interfacial water layer were in the following order: KBr > NaBr > KCl > NaCl ~ NaF > KF. Since these changes can not be factorized into individual anion and cation contributions, there are possible ion pairing or association effects, especially for the NaF case. We also found that the orientational ...

  8. Effect of microwave power on the morphology and optical property of zinc oxide nano-structures prepared via a microwave-assisted aqueous solution method

    International Nuclear Information System (INIS)

    The effect of the microwave power on the morphology and optical properties of zinc oxide nanostructures prepared using a microwave-assisted aqueous solution method has been investigated. The ZnO nanostructures were synthesized from zinc chloride and sodium hydroxide mixed aqueous solutions exposed for 5 min to microwave radiation at four different powers, namely 150, 450, 700 and 1000 W. The morphologies of the samples have been characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The results showed that the power of microwave radiation influenced the shape and size of the synthesized nanostructures. It is also found that the average particle size of nanostructures decreased with decreasing microwave power. The results of X-ray diffraction (XRD) showed that all the as-prepared ZnO nanostructures are in crystalline form with high purity. The infrared (IR) spectra indicated that the as-prepared nano ZnO product can be used as infrared gas sensors such as an infrared carbon dioxide (CO2) and/or CO sensor. Optical properties of the as-prepared ZnO nanostructures were investigated by UV-vis spectroscopy and showed that the optical properties of as-synthesized ZnO samples are sensitive to the variation of the power of microwave radiation.

  9. Effect of organic co-solvents on the solvation enthalpies of amino acids and dipeptides in mixed aqueous solutions

    Science.gov (United States)

    Badelin, V. G.; Tyunina, E. Yu.

    2011-09-01

    Transition enthalpies (Δtr H o) of substances from water to binary solutions were calculated at 298.15 K on the basis of standard dissolution enthalpies (Δsol H o) for six amino acids and five dipeptides in the mixtures of water with organic solvents of various chemical natures. The enthalpy pair coefficients of interaction h xy for biomolecules with organic component of mixture were estimated within the formalism of the McMillan-Mayer theory. The change in the character of the interaction of the components of solution was demonstrated in dependence on the physicochemical properties of the solvent and nature of the side radical of the dissolved bioorganic substance. Quantitative estimation of the type of interaction of the substance with the solvent was performed on the basis of correlation ratios relating the enthalpy characteristics of bioorganic substances to properties of organic cosolvents. It was shown that in the solutions under study, the effects of both the specific (mainly electron donor) and non-specific solvation of amino acids and peptides are observed.

  10. Removal of radium from aqueous solutions

    International Nuclear Information System (INIS)

    Adsorption of radium from aqueous solution with montmorillonite clay was investigated. Adsorption isotherm data of the radium and montmorillonite clay system were developed and fitted to both the Langmuir and Freundlich isotherm equations. The Langmuir isotherm equation was determined to be q = 6.700 C/1 + 8.447 x 10-5C and the Freundlich isotherm equation is q = 45.431 C/sup 1/1.401/. A rotary precoat filtration technique was used for dewatering the slurries of the montmorillonite clay and diatomaceous earth mixture. The rate of filtration was found to be a function of the weight percent of the clay, applied vacuum, drum speed and precoat thickness. The functional relationship is of the form Q = (0.682 + 0.035 X1 - 0.014 X2 + 0.140 X3 + 0.007 X1X2)/1 + (3.744 - 0.767 X3 + 0.079 X1X2)C125. 15 figures, 11 tables

  11. Dissolution of gaseous methyl iodide into aqueous sodium hydroxide solutions

    International Nuclear Information System (INIS)

    Absorption process of gaseous methyl iodide by water or sodium hydroxide solutions was investigated using a semi-flow type experimental apparatus by measuring the concentration of all measurable chemical species in both the gas and the liquid phase. The experimental temperature ranged from 288 to 311 K and the gaseous methyl iodide and aqueous sodium hydroxide concentrations were approximately 0.6 x 10-3 to 7 x 10-3 and 0 to 0.2 mol/dm3, respectively. It is estimated that the dissolution of methyl iodide into the sodium hydroxide solution proceeds according to the following steps. Step (1) Methyl iodide in air dissolves physically into the aqueous phase. Physical dissolution process obeys Henry's law. Step (2) Methyl iodide dissolved into the aqueous phase is decomposed by a base catalytic hydrolysis and produces methyl alcohol and iodide ion. The equilibrium constants of physical dissolution were obtained from the steady concentration in both the gas and the liquid phases in the semi-flow type experiment because the hydrolysis reaction rate of methyl iodide is very slow in comparison with the physical dissolution in this experimental conditions. The obtained value of the standard heat of solution of methyl iodide into water was 7.2 kcal/mol. Salting-out effect was observed when the concentration of sodium hydroxide in the absorbent was over 0.01 mol/dm3. (auth.)

  12. Dermal absorption of a dilute aqueous solution of malathion

    Directory of Open Access Journals (Sweden)

    Scharf John

    2008-01-01

    Full Text Available Malathion is an organophosphate pesticide commonly used on field crops, fruit trees, livestock, agriculture, and for mosquito and medfly control. Aerial applications can result in solubilized malathion in swimming pools and other recreational waters that may come into contact with human skin. To evaluate the human skin absorption of malathion for the assessment of risk associated with human exposures to aqueous solutions, human volunteers were selected and exposed to aqueous solutions of malathion. Participants submerged their arms and hands in twenty liters of dilute malathion solution in either a stagnant or stirred state. The "disappearance method" was applied by measuring malathion concentrations in the water before and after human exposure for various periods of time. No measurable skin absorption was detected in 42% of the participants; the remaining 58% of participants measured minimal absorbed doses of malathion. Analyzing these results through the Hazard Index model for recreational swimmer and bather exposure levels typically measured in contaminated swimming pools and surface waters after bait application indicated that these exposures are an order of magnitude less than a minimal dose known to result in a measurable change in acetylcholinesterase activity. It is concluded that exposure to aqueous malathion in recreational waters following aerial bait applications is not appreciably absorbed, does not result in an effective dose, and therefore is not a public health hazard.

  13. Adsorption of nicotine on different zeolite types, from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Stošić Dušan K.

    2007-01-01

    Full Text Available The plant alkaloid, nicotine, is a strongly toxic heterocyclic compound: the lethal dose for an adult human being (40-60 mg is importantly lower in comparison with the other known poisons such as arsenic or strychni­ne. Cigarettes represent "the most toxic and addictive form of nicotine". Besides the negative effects of nicotine on public health produced by self-administration, recently another potentially very dangerous effect has been recognized: because of its miscibility with water, nicotine can be found in industrial wastewaters, and consequently, in groundwater. Therefore, the problem of nicotine removal from aqueous solutions has became an interesting topic. In this work, the removal of nicotine has been probed by adsorption on solid materials. Adsorption of nicotine on different zeolites (clinoptilolite, ZSM-5 and β zeolite and on activated carbon was investigated from aqueous solutions, at 298 K. The obtained results are presented as adsorption isotherms: the amount of adsorbed nicotine as a function of equilibrium concentration. These data were obtained from the residual amount of nicotine in the aqueous phase, by the use of UV spectroscopy. The highest amounts of adsorbed nicotine was found for activated carbon and p zeolite (~ mmol·g-1. The attempt to modify the adsorption properties of ZSM-5 zeolite has been also done: ZSM-5 was modified by ion-exchange with VIII group metal (Cu2+ and Fe3+. In addition, the adsorption of nicotine on ZSM-5 zeolite with different Si/Al ratios has been done. It has been noticed that ion-exchange did not improve the adsorption possibilities, while the adsorption was importantly lower in the case of higher silicon content in ZMS-5 structure. 13C NMR spectra were collected for suspensions formed of solid adsorbent and aqueous solution of nicotine; in this way, the part of nicotine molecule which is most probably connected with the adsorbent was recognized.

  14. Effects of ion concentration on the hydrogen bonded structure of water in the vicinity of ions in aqueous NaCl solutions

    Indian Academy of Sciences (India)

    A Nag; D Chakraborty; A Chandra

    2008-01-01

    Molecular dynamics simulations of dilute and concentrated aqueous NaCl solutions are carried out to investigate the changes of the hydrogen bonded structures in the vicinity of ions for different ion concentrations. An analysis of the hydrogen bond population in the first and second solvation shells of the ions and in the bulk water is done. Although essentially no effect of ions on the hydrogen bonding is observed beyond the first solvation shell of the ions for the dilute solutions, for the concentrated solutions a noticeable change in the average number of water-water hydrogen bonds is observed in the second solvation shells of the ions and even beyond. However, the changes in the average number of hydrogen bonds are found to be relatively less when both water-water and ion-water hydrogen bonds are counted. Thus, the changes in the total number of hydrogen bonds per water are not very dramatic beyond the first solvation shell even for concentrated solutions.

  15. Effects of reactive oxygen and nitrogen species induced by ammonium dinitramide decomposition in aqueous solutions of deoxyribose nucleic acid.

    Science.gov (United States)

    Steel-Goodwin, L; Kuhlman, K J; Miller, C; Pace, M D; Carmichael, A J

    1997-01-01

    Ammonium dinitramide (ADN), a potential rocket fuel, decomposes in water forming NO2. The chemistry of this ADN-released NO2 in oxygenated biological systems is complex both in the number of potential chemical species and in the number of parallel and consecutive reactions that can theoretically occur. High-pressure liquid chromatography (HPLC) studies revealed ADN fragmented deoxyribose nucleic acid (DNA). Damage to DNA standard solutions was caused by at least two major pathways, one arising from reactions of NO2 with oxygen and one arising from a reaction with superoxide (O2-.). The radical species generated when ADN is incubated with standard solutions of DNA, pH 7.5, in the presence of the spin trap agent n-tert-butyl-alpha-nitrone (PBN) was compared with the PBN-radical adducts generated in the presence of ADN and O2-. or of ADN and hydrogen peroxide (H2O2). The ADN-induced PBN radical adducts increased linearly over the 90-minute study period. The values of peak intensity in the presence of O2-. and in the presence of H2O2, were 828% and 7.08%, respectively, of the ADN-induced radicals alone. The synergistic effect of ADN with O2- may provide an understanding of the sensitivity of the rat blastocyst to aDN at the preimplantation stage of development and the lack of toxicity in in vivo studies in tissues high in catalase. PMID:9142377

  16. The effect of laser repetition rate on the LASiS synthesis of biocompatible silver nanoparticles in aqueous starch solution

    Directory of Open Access Journals (Sweden)

    Zamiri R

    2013-01-01

    Full Text Available Reza Zamiri,1 Azmi Zakaria,1,* Hossein Abbastabar Ahangar,2 Majid Darroudi,3 Golnoosh Zamiri,1 Zahid Rizwan,1 Gregor PC Drummen4,* 1Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Selangor Darul Ehsan, Malaysia; 3Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 4Bionanoscience and Bio-Imaging Program, Cellular Stress and Ageing Program, Bio&Nano-Solutions, Düsseldorf, Germany*These authors contributed to this work equallyAbstract: Laser ablation-based nanoparticle synthesis in solution is rapidly becoming popular, particularly for potential biomedical and life science applications. This method promises one pot synthesis and concomitant bio-functionalization, is devoid of toxic chemicals, does not require complicated apparatus, can be combined with natural stabilizers, is directly biocompatible, and has high particle size uniformity. Size control and reduction is generally determined by the laser settings; that the size and size distribution scales with laser fluence is well described. Conversely, the effect of the laser repetition rate on the final nanoparticle product in laser ablation is less well-documented, especially in the presence of stabilizers. Here, the influence of the laser repetition rate during laser ablation synthesis of silver nanoparticles in the presence of starch as a stabilizer was investigated. The increment of the repetition rate does not negatively influence the ablation efficiency, but rather shows increased productivity, causes a red-shift in the plasmon resonance peak of the silver–starch nanoparticles, an increase in mean particle size and size distribution, and a distinct lack of agglomerate formation. Optimal results were achieved at 10 Hz repetition rate, with a mean particle size of ~10 nm and a

  17. Ozone photolysis of paracetamol in aqueous solution.

    Science.gov (United States)

    Neamţu, Mariana; Bobu, Maria; Kettrup, Antonius; Siminiceanu, Ilie

    2013-01-01

    The degradation of a paracetamol (N-acetil-para-aminofenol) aqueous solution (C (0) P = 5 mmol L(-1)) is studied in a bench-scale setup by means of simple ozonation (O3) and ozonation catalyzed with UV light (O3/UV) in order to quantify the influence of UV light on the degradation process. The results have shown that under the adopted experimental conditions (25°C, applied ozone dose = 9.8 mg L(-1) and gas flow rate of 20 L h(-1)) both oxidative systems are capable of removing the substrate with mineralization degrees up to 51% for ozonation and 53% for O3/UV. HPICE chromatography allowed the detection of nitrate ions and maleic and oxalic acids as ultimate carboxylic acids. The experimental data have been interpreted through 5 indicators: the conversion of paracetamol (XP ), the conversion degree of TOC (XTOC ), the apparent rate constant (kap ), the Hatta number (Ha) and the enhancement factor (E). The main advantage of photo-ozonation compared to simple ozonation was a more advanced conversion (79% vs. 92% after 90 min). The paracetamol decay follows a pseudo-first-order reaction with a superior rate constant (higher by 54%) for the UV catalyzed system in comparison with direct ozonation. Mineralization is slightly accelerated (+4%) in the O3/UV system, due to the additional production of hydroxyl radicals induced by the UV light and a higher Hatta number (+24%). Nevertheless, the process was still in the slow reaction kinetic regime (Ha < 0.3), and the enhancement factor was not significantly increased. The results are useful for the design and scale-up of the gas-liquid processes. PMID:23647117

  18. Ozone photolysis of paracetamol in aqueous solution.

    Science.gov (United States)

    Neamţu, Mariana; Bobu, Maria; Kettrup, Antonius; Siminiceanu, Ilie

    2013-01-01

    The degradation of a paracetamol (N-acetil-para-aminofenol) aqueous solution (C (0) P = 5 mmol L(-1)) is studied in a bench-scale setup by means of simple ozonation (O3) and ozonation catalyzed with UV light (O3/UV) in order to quantify the influence of UV light on the degradation process. The results have shown that under the adopted experimental conditions (25°C, applied ozone dose = 9.8 mg L(-1) and gas flow rate of 20 L h(-1)) both oxidative systems are capable of removing the substrate with mineralization degrees up to 51% for ozonation and 53% for O3/UV. HPICE chromatography allowed the detection of nitrate ions and maleic and oxalic acids as ultimate carboxylic acids. The experimental data have been interpreted through 5 indicators: the conversion of paracetamol (XP ), the conversion degree of TOC (XTOC ), the apparent rate constant (kap ), the Hatta number (Ha) and the enhancement factor (E). The main advantage of photo-ozonation compared to simple ozonation was a more advanced conversion (79% vs. 92% after 90 min). The paracetamol decay follows a pseudo-first-order reaction with a superior rate constant (higher by 54%) for the UV catalyzed system in comparison with direct ozonation. Mineralization is slightly accelerated (+4%) in the O3/UV system, due to the additional production of hydroxyl radicals induced by the UV light and a higher Hatta number (+24%). Nevertheless, the process was still in the slow reaction kinetic regime (Ha < 0.3), and the enhancement factor was not significantly increased. The results are useful for the design and scale-up of the gas-liquid processes.

  19. Photolysis of Periodate and Periodic Acid in Aqueous Solution

    DEFF Research Database (Denmark)

    Sehested, Knud; Kläning, U. K.

    1978-01-01

    The photochemistry of periodate and periodic acid in aqueous solution was studied (i) by quantum yield measurements at low light intensity (ii) by flash photolysis, and (iii) by photolysis of glassy samples at 77 K. The photochemical studies were supplemented with pulse radiolysis studies...... of aqueous periodate solutions and with kinetic studies using stopped-flow technique. In strongly alkaline solution the photodecomposition of periodate proceeds via formation of O– and IVI. At pH

  20. Glasslike Behavior in Aqueous Electrolyte Solutions

    CERN Document Server

    Turton, David A; Hefter, Glenn; Buchner, Richard; Wynne, Klaas; 10.1063/1.2906132

    2009-01-01

    When salts are added to water, the viscosity generally increases suggesting the ions increase the strength of the water's hydrogen-bond network. However, infrared pump-probe measurements on electrolyte solutions have found that ions have no influence on the rotational dynamics of water molecules implying no enhance-ment or breakdown of the hydrogen-bond network. Here we report optical Kerr-effect and dielectric relaxa-tion spectroscopic measurements, which have enabled us to separate the effects of rotational and transitional motions of the water molecules. These data show that electrolyte solutions behave like a supercooled liquid approaching a glass transition in which rotational and translational molecular motions are decoupled. It is now possible to understand previously conflicting viscosity data, nuclear magnetic resonance relaxation, and ultrafast infrared spectroscopy in a single unified picture.

  1. Glasslike behavior in aqueous electrolyte solutions.

    Science.gov (United States)

    Turton, David A; Hunger, Johannes; Hefter, Glenn; Buchner, Richard; Wynne, Klaas

    2008-04-28

    When salts are added to water, generally the viscosity increases, suggesting that the ions increase the strength of the water's hydrogen-bond network. However, infrared pump-probe measurements on electrolyte solutions have found that ions have no influence on the rotational dynamics of water molecules, implying no enhancement or breakdown of the hydrogen-bond network. Here, we report optical Kerr effect and dielectric relaxation spectroscopic measurements, which have enabled us to separate the effects of rotational and transitional motions of the water molecules. These data show that electrolyte solutions behave like a supercooled liquid approaching a glass transition in which rotational and translational molecular motions are decoupled. It is now possible to understand previously conflicting viscosity data, nuclear magnetic resonance relaxation, and ultrafast infrared spectroscopy in a single unified picture.

  2. Removal of Cholera Toxin from Aqueous Solution by Probiotic Bacteria

    Directory of Open Access Journals (Sweden)

    Jussi A. O. Meriluoto

    2012-06-01

    Full Text Available Cholera remains a serious health problem, especially in developing countries where basic hygiene standards are not met. The symptoms of cholera are caused by cholera toxin, an enterotoxin, which is produced by the bacterium Vibrio cholerae. We have recently shown that human probiotic bacteria are capable of removing cyanobacterial toxins from aqueous solutions. In the present study we investigate the ability of the human probiotic bacteria, Lactobacillus rhamnosus strain GG (ATCC 53103 and Bifidobacterium longum 46 (DSM 14583, to remove cholera toxin from solution in vitro. Lactobacillus rhamnosus strain GG and Bifidobacterium longum 46 were able to remove 68% and 59% of cholera toxin from aqueous solutions during 18 h of incubation at 37 °C, respectively. The effect was dependent on bacterial concentration and L. rhamnosus GG was more effective at lower bacterial concentrations. No significant effect on cholera toxin concentration was observed when nonviable bacteria or bacterial supernatant was used.

  3. Specific Na+ and K+ Cation Effects on the Interfacial Water Molecules at the Air/Aqueous Salt Solution Interfaces Probed with Non-resonant Second Harmonic Generation (SHG)

    OpenAIRE

    Bian, Hong-tao; Feng, Ran-Ran; Guo, Yuan; Wang, Hong-fei

    2008-01-01

    Here we report the polarization dependent non-resonant second harmonic generation (SHG) measurement of the interfacial water molecules at the aqueous solution of the following salts: NaF, NaCl, NaBr, KF, KCl, and KBr. Through quantitative polarization analysis of the SHG data,the orientational parameter D value and the relative surface density of the interfacial water molecules at these aqueous solution surfaces were determined. From these results we found that addition of each of the six sal...

  4. Aqueous solution of basic fuchsin as food irradiation dosimeter

    International Nuclear Information System (INIS)

    Dosimetric characterization of aqueous solution of basic fuchsin has been studied spectrophotometrically for the possible application in the low-dose food irradiation dosimetry. Absorption spectra of unirradiated and irradiated solutions were determined and decrease in the absorption with the radiation dose was noted down. Radiation-induced bleaching of the dye was measured at wavelengths of maximum absorption λmax (540nm) as well as 510, 460 and 400 nm wavelengths. At all these wavelengths, the decrease in the absorbance of the dosimeter was linear with respect to the absorbed dose from 0.05 to 0.6 kGy. The stability of dosimetric solution during the post-irradiation storage in the dark at room temperature showed that after initial bleaching during first eight days, the response was almost stable for about 34 days. The effect of different light and temperature conditions also showed that the response gradually decreased during the storage period of 34 days, which shows that the basic fuchsin dye is photosensitive as well as thermally sensitive. The possibility of using aqueous solution of basic fuchsin as food irradiation dosimeter will be discussed. (authors)

  5. Effect of carbon dioxide on the rate of iodine vapor absorption by aqueous solution of sodium hydroxide

    International Nuclear Information System (INIS)

    There is always carbon dioxide in the atmosphere as an impurity. Since this is an acid gas similar to iodine, each absorption rate seems to be affected by the other due to the coexistence of these two. Experiments have been conducted to clarify the absorption rate and absorption mechanism of iodine in the simultaneous absorption of iodine and carbon dioxide. Carbon dioxide coexisting with gas phases as an impurity decreases the absorption rate of iodine in the removal by washing with water of iodine mixed in the air. The first cause of this is that the diffusion coefficient of iodine in gas phase decreases with the carbon dioxide content in the gas phase. The second cause is that coexistent carbon dioxide is an acid gas, dissociates by dissolving into the absorbing solution, increases hydrogen ion concentration together with the formation of negative ions of bicarbonate and carbonate, and reduces hydroxyl ion concentration as a result. It is more important that existence of iodine has a catalytic effect to the rate of basic catalytic hydrolysis of carbon dioxide simultaneously dissolved in water phase, and accelerates this reaction rate. The mechanism of catalytic effect of iodine for the hydrolysis of carbon dioxide can not be clarified in detail only by this experiment, but the simultaneous absorption rate of iodine and carbon dioxide can be explained satisfactorily. (Wakatsuki, Y

  6. Removing Phosphorus from Aqueous Solutions Using Lanthanum Modified Pine Needles.

    Directory of Open Access Journals (Sweden)

    Xianze Wang

    Full Text Available The renewable pine needles was used as an adsorbent to remove phosphorus from aqueous solutions. Using batch experiments, pine needles pretreated with alkali-isopropanol (AI failed to effectively remove phosphorus, while pine needles modified with lanthanum hydroxide (LH showed relatively high removal efficiency. LH pine needles were effective at a wide pH ranges, with the highest removal efficiency reaching approximately 85% at a pH of 3. The removal efficiency was kept above 65% using 10 mg/L phosphorus solutions at desired pH values. There was no apparent significant competitive behavior between co-existing anions of sulfate, nitrate, and chloride (SO4(2-, NO3(- and Cl(-; however, CO3(2- exhibited increased interfering behavior as concentrations increased. An intraparticle diffusion model showed that the adsorption process occurred in three phases, suggesting that a boundary layer adsorption phenomena slightly affected the adsorption process, and that intraparticle diffusion was dominant. The adsorption process was thermodynamically unfavorable and non-spontaneous; temperature increases improved phosphorus removal. Total organic carbon (TOC assays indicated that chemical modification reduced the release of soluble organic compounds from 135.6 mg/L to 7.76 mg/L. This new information about adsorption performances provides valuable information, and can inform future technological applications designed to remove phosphorus from aqueous solutions.

  7. Removing Phosphorus from Aqueous Solutions Using Lanthanum Modified Pine Needles

    Science.gov (United States)

    Wang, Xianze; Liu, Zhongmou; Liu, Jiancong; Huo, Mingxin; Huo, Hongliang; Yang, Wu

    2015-01-01

    The renewable pine needles was used as an adsorbent to remove phosphorus from aqueous solutions. Using batch experiments, pine needles pretreated with alkali-isopropanol (AI) failed to effectively remove phosphorus, while pine needles modified with lanthanum hydroxide (LH) showed relatively high removal efficiency. LH pine needles were effective at a wide pH ranges, with the highest removal efficiency reaching approximately 85% at a pH of 3. The removal efficiency was kept above 65% using 10 mg/L phosphorus solutions at desired pH values. There was no apparent significant competitive behavior between co-existing anions of sulfate, nitrate, and chloride (SO42-, NO3- and Cl-); however, CO32- exhibited increased interfering behavior as concentrations increased. An intraparticle diffusion model showed that the adsorption process occurred in three phases, suggesting that a boundary layer adsorption phenomena slightly affected the adsorption process, and that intraparticle diffusion was dominant. The adsorption process was thermodynamically unfavorable and non-spontaneous; temperature increases improved phosphorus removal. Total organic carbon (TOC) assays indicated that chemical modification reduced the release of soluble organic compounds from 135.6 mg/L to 7.76 mg/L. This new information about adsorption performances provides valuable information, and can inform future technological applications designed to remove phosphorus from aqueous solutions. PMID:26630014

  8. Effects of dissolved Ca2+, Mg2+, and Na+ ions on the supramolecular aggregation of natural organic matter in aqueous solutions

    Science.gov (United States)

    Ahn, W.; Kalinichev, A. G.; Clark, M. M.

    2008-12-01

    The complexation of natural organic matter (NOM) with metal ions, minerals and organic species in soil and water allows NOM to form water-soluble and water-insoluble aggregates of widely differing chemical and biological stabilities. Metal-NOM interaction induces strong correlations between the concentration of natural organic matter and the speciation, solubility and toxicity of many metals in the environment. In water purification and desalination, NOM is also implicated in fouling of nanofiltration and reverse osmosis membranes, either as the primary foulant or as a conditioning layer for microbial attachment ("biofouling"). In this work we investigated the effects of various metal ions on NOM aggregation in aqueous solutions, by a combination of dynamic light scattering (DLS), small angle neutron scattering (SANS) and large-scale molecular dynamics (MD) computer simulations. This allows a detailed molecular-scale statistical analysis of the size and the structural topology of metal-NOM aggregates. The DLS measurements show that Ca2+ ions present in a Suwannee River NOM (SRNOM) solution lead to the formation of a wide range of supramolecular structures with sizes between 100 and 1,000 nm. In contrast, Mg2+ and Na+ do not affect the aggregation of SRNOM as strongly. SANS data are inconclusive but indicate the presence of quite large (>50 nm) fractal particles formed presumably through a cluster-cluster aggregation. MD simulations confirm these observations and show that NOM can aggregate in aqueous solutions by two different mechanisms. On the one hand, NOM molecules can spontaneously aggregate by hydrogen bonding between their functional groups when only Na+ and Mg2+ are present as background cations. This promotes the formation of uniformly shaped NOM clusters. On the other hand, if Ca2+ ions are present in solution, they can more strongly bind two different NOM molecules by co-complexing the carboxylate groups, thus promoting the formation of longer linear and

  9. Degradation of Sodium-Polyacrylate in Dilute Aqueous Solution

    Science.gov (United States)

    Saita, Takao

    1980-12-01

    It is shown using a capillary viscometer that the viscosity of a dilute aqueous solution of sodium-polyacrylate at 20°C decreases gradually for each flow time measurement and also decreases with the time of rest. Assuming that the polymer degradation is caused by shearing stress and oxidation, their effects are discussed with the data obtained using a closed-type capillary viscometer derived for this investigation. It is proved from the results that rupture of the Na-PAA molecule is caused by mechanochemical degradation, and also photo-degradation under the usual illumination and sunlight in a laboratory.

  10. Hydrate-based heavy metal separation from aqueous solution

    Science.gov (United States)

    Song, Yongchen; Dong, Hongsheng; Yang, Lei; Yang, Mingjun; Li, Yanghui; Ling, Zheng; Zhao, Jiafei

    2016-02-01

    A novel hydrate-based method is proposed for separating heavy metal ions from aqueous solution. We report the first batch of experiments and removal characteristics in this paper, the effectiveness and feasibility of which are verified by Raman spectroscopy analysis and cross-experiment. 88.01-90.82% of removal efficiencies for Cr3+, Cu2+, Ni2+, and Zn2+ were obtained. Further study showed that higher R141b-effluent volume ratio contributed to higher enrichment factor and yield of dissociated water, while lower R141b-effluent volume ratio resulted in higher removal efficiency. This study provides insights into low-energy, intensive treatment of wastewater.

  11. ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION ON ATTAPULGITE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Batch adsorption experiments were carried out for the removal of methylene blue (MB) from aqueous solution using attapulgite as adsorbent. The effects of various parameters such as temperature, contact time, the pH value, and attapulgite dosage on the adsorption performance were investigated. The standard curve and regression equation were established by spectrophotometry. The adsorption experimental results showed that the adsorption equilibrium data were well in accord with Langmuir adsorptive model. The optimal result was acquired under the experimental condition of attapulgite dosage 0.18g, MB concentration 50.0mg/L, pH 10, and adsorption time 20min at room temperature.

  12. Strong adhesion and cohesion of chitosan in aqueous solutions

    OpenAIRE

    Lee, DW; Lim, C. (Cheryl); Israelachvili, JN; Hwang, DS

    2013-01-01

    Chitosan, a load-bearing biomacromolecule found in the exoskeletons of crustaceans and insects, is a promising biopolymer for the replacement of synthetic plastic compounds. Here, surface interactions mediated by chitosan in aqueous solutions, including the effects of pH and contact time, were investigated using a surface forces apparatus (SFA). Chitosan films showed an adhesion to mica for all tested pH ranges (3.0-8.5), achieving a maximum value at pH 3.0 after a contact time of 1 h (Wad ∼ ...

  13. Tannin-immobilized mesoporous silica bead (BT-SiO2) as an effective adsorbent of Cr(III) in aqueous solutions

    International Nuclear Information System (INIS)

    This study describes a new approach for the preparation of tannin-immobilized adsorbent by using mesoporous silica bead as the supporting matrix. Bayberry tannin-immobilized mesoporous silica bead (BT-SiO2) was characterized by powder X-ray diffraction to verify the crystallinity, field-emission scanning electron microscopy to observe the surface morphology, and surface area and porosity analyzer to measure the mesoporous porous structure. Subsequently, the adsorption experiments to Cr(III) were applied to evaluate the adsorption performances of BT-SiO2. It was found that the adsorption of Cr(III) onto BT-SiO2 was pH-dependent, and the maximum adsorption capacity was obtained in the pH range of 5.0-5.5. The adsorption capacity was 1.30 mmol g-1 at 303 K and pH 5.5 when the initial concentration of Cr(III) was 2.0 mmol L-1. Based on proton nuclear magnetic resonance (HNMR) analyses, the adsorption mechanism of Cr(III) on BT-SiO2 was proved to be a chelating interaction. The adsorption kinetic data can be well described using pseudo-first-order model and the equilibrium data can be well fitted by the Langmuir isothermal model. Importantly, no bayberry tannin was leached out during the adsorption process and BT-SiO2 can simultaneously remove coexisting metal ions from aqueous solutions. In conclusion, this study provides a new strategy for the preparation of tannin-immobilized adsorbents that are highly effective in removal of heavy metals from aqueous solutions.

  14. Effect of ultrasonic frequency on H2O2 sonochemical formation rate in aqueous nitric acid solutions in the presence of oxygen.

    Science.gov (United States)

    Dalodière, Elodie; Virot, Matthieu; Moisy, Philippe; Nikitenko, Sergey I

    2016-03-01

    The influence of the ultrasonic frequency (20 kHz, 207 kHz, and 615 kHz) towards the formation kinetics of H2O2 under Ar and Ar/(20 vol.%)O2 atmospheres was evaluated in pure water and aqueous nitric solutions. Results obtained at low frequency ultrasound demonstrate that hydrogen peroxide formation is enhanced under an Ar/O2 gas mixture whatever the sonicated medium. Nevertheless, H2O2 yields are higher in aqueous nitric solutions whatever the nature of the saturating gas. These observations are consistent at high frequency ultrasound under Ar gas notwithstanding higher yields for H2O2. Surprisingly, an inverse tendency is observed for high frequency sonolysis carried out under an Ar/O2 atmosphere: higher yields of H2O2 are measured in pure water. Further studies in the presence of pure Ar revealed a more important decomposition of nitric acid under high frequency ultrasound leading to higher yields of both HNO2 in the liquid phase and NO in the gas phase. In the presence of Ar/O2 mixture, the intrabubble oxidation of NO causes cavitation bubble depletion in O2 leading to the drop of H2O2 yield. On the other hand, it was found that for Ar/(20 vol.%)O2 mixture there is no influence of oxygen on HNO2 yield whatever the ultrasonic frequency; this is most likely explained by two processes: (i) HNO2 formation results from nitrate-ion thermolysis in the liquid reaction zone surrounding the cavitation bubble, and (ii) effective intrabubble oxidation of NOx species by oxygen to nitrate-ion. PMID:26584999

  15. Tannin-immobilized mesoporous silica bead (BT-SiO{sub 2}) as an effective adsorbent of Cr(III) in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Huang Xin [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); Liao Xuepin, E-mail: xpliao@scu.edu.cn [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); Shi Bi [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China)

    2010-01-15

    This study describes a new approach for the preparation of tannin-immobilized adsorbent by using mesoporous silica bead as the supporting matrix. Bayberry tannin-immobilized mesoporous silica bead (BT-SiO{sub 2}) was characterized by powder X-ray diffraction to verify the crystallinity, field-emission scanning electron microscopy to observe the surface morphology, and surface area and porosity analyzer to measure the mesoporous porous structure. Subsequently, the adsorption experiments to Cr(III) were applied to evaluate the adsorption performances of BT-SiO{sub 2}. It was found that the adsorption of Cr(III) onto BT-SiO{sub 2} was pH-dependent, and the maximum adsorption capacity was obtained in the pH range of 5.0-5.5. The adsorption capacity was 1.30 mmol g{sup -1} at 303 K and pH 5.5 when the initial concentration of Cr(III) was 2.0 mmol L{sup -1}. Based on proton nuclear magnetic resonance (HNMR) analyses, the adsorption mechanism of Cr(III) on BT-SiO{sub 2} was proved to be a chelating interaction. The adsorption kinetic data can be well described using pseudo-first-order model and the equilibrium data can be well fitted by the Langmuir isothermal model. Importantly, no bayberry tannin was leached out during the adsorption process and BT-SiO{sub 2} can simultaneously remove coexisting metal ions from aqueous solutions. In conclusion, this study provides a new strategy for the preparation of tannin-immobilized adsorbents that are highly effective in removal of heavy metals from aqueous solutions.

  16. Redox switching and oxygen evolution at hydrous oxyhydroxide modified nickel electrodes in aqueous alkaline solution: effect of hydrous oxide thickness and base concentration

    OpenAIRE

    Lyons, Michael

    2012-01-01

    Outstanding issues regarding the film formation, the redox switching reaction and the oxygen evolution reaction (OER) electrocatalytic behaviour of multi-cycled nickel oxy-hydroxide films in aqueous alkaline solution have been discussed. The oxide is grown using a repetitive potential multi-cycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of t...

  17. Nanoscale lubricating film formation by linear polymer in aqueous solution

    Science.gov (United States)

    Liu, Shuhai; Guo, Dan; Xie, Guoxin

    2012-11-01

    Film-forming properties of polymer in aqueous solution flowing through a nanogap have been investigated by using a thin film interferometry. The film properties of linear polymer in aqueous solution flowing through a confined nanogap depend on the ratio of water film thickness to averaged radius of polymer chains H0/RPolymer. It was found that the lubrication film thickness of linear polymer in aqueous solution decreases as the polymer molecular weight increasing when H0/RPolymer < 2 ˜ 3. A new lubrication map was proposed, which includes the lubrication regime of weak confinement influence, the lubrication regime of strong confinement influence (LRSCI), and the transition regime of confinement influence. It is very difficult to increase the lubrication film thickness using the higher molecule weight in the LRSCI regime. The lubrication mechanism inferred from our experimental results may help to better understand the dynamic film properties of linear polymer in aqueous solution flowing through a nanogap.

  18. Boron removal from aqueous solution by direct contact membrane distillation

    International Nuclear Information System (INIS)

    The removal of boron from aqueous solution by direct contact membrane distillation (DCMD) was studied with self-prepared polyvinylidene fluoride (PVDF) hollow fiber membranes in the present work. The effect of pH, boron concentration, temperature and salt concentration of the feed solution on the boron rejection was investigated. The experimental results indicated that boron rejection was less dependent on the feed pH and salt concentration. DCMD process had high boron removal efficiency (>99.8%) and the permeate boron was below the maximum permissible level even at feed concentration as high as 750 mg/L. Although the permeate flux was enhanced exponentially with the feed temperature increasing, the influence of feed temperature on the boron rejection could be neglected. Finally, the natural groundwater sample containing 12.7 mg/L of boron was treated by DCMD process. The permeate boron kept below 20 μg/L whether the feed was acidified or not, but pre-acidification was helpful to maintain the permeate flux stability. All the experimental results indicated that DCMD could be efficiently used for boron removal from aqueous solution.

  19. Qualitative and quantitative analysis of beta emitters in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hamzah, Zaini bin

    1983-01-01

    A beta spectrometer, consisting of a liquid scintillation counter, coupled to a programmable multichannel analyser was used to achieve the objective of detecting and measuring beta activity in low level aqueous environmental solution as well as identifying the radioisotopes present. Aqueous solutions of standard beta emitters, covering a range of energies between 18.6 KeV and 3550 KeV, were used to develop computer methods for analysis. The effects of pH, acids, bases, buffers, and salts on the stability of the mixture and on the detection efficiency of the radioisotopes, were investigated. It was found that temperature changes, beyond the operating temperature range, could result in severe errors. Application of the Cherenkov counting technique for beta emitters, gives extra data to support the main results. For the analysis of environmental solutions, which may contain a variety of radioisotopes, the system was used to obtain spectra of alpha emitters, beta emitters with internal conversion and Cherenkov radiation. Synthetic mixtures of tritium and carbon-14 of activity ratios between 8:1 and 1:8 were used to investigate the problems of multielement spectral analysis.

  20. Surface tension and related thermodynamic quantities of aqueous electrolyte solutions

    CERN Document Server

    Matubayasi, Norihiro

    2013-01-01

    Surface tension provides a thermodynamic avenue for analyzing systems in equilibrium and formulating phenomenological explanations for the behavior of constituent molecules in the surface region. While there are extensive experimental observations and established ideas regarding desorption of ions from the surfaces of aqueous salt solutions, a more successful discussion of the theory has recently emerged, which allows the quantitative calculation of the distribution of ions in the surface region. Surface Tension and Related Thermodynamic Quantities of Aqueous Electrolyte Solutions provides a d

  1. NMR studies of proton exchange kinetics in aqueous formaldehyde solutions

    Science.gov (United States)

    Rivlin, Michal; Eliav, Uzi; Navon, Gil

    2014-05-01

    Aqueous solutions of formaldehyde, formalin, are commonly used for tissue fixation and preservation. Treatment with formalin is known to shorten the tissue transverse relaxation time T2. Part of this shortening is due to the effect of formalin on the water T2. In the present work we show that the shortening of water T2 is a result of proton exchange between water and the major constituent of aqueous solutions of formaldehyde, methylene glycol. We report the observation of the signal of the hydroxyl protons of methylene glycol at 2 ppm to high frequency of the water signal that can be seen at low temperatures and at pH range of 6.0 ± 1.5 and, at conditions where it cannot be observed by the single pulse experiment, it can be detected indirectly through the water signal by the chemical exchange saturation transfer (CEST) experiment. The above finding made it possible to obtain the exchange rate between the hydroxyl protons of the methylene glycol and water in aqueous formaldehyde solutions, either using the dispersion of the spin-lattice relaxation rate in the rotating frame (1/T1ρ) or, at the slow exchange regime, from the line width hydroxyl protons of methylene glycol. The exchange rate was ∼104 s-1 at pH 7.4 and 37 °C, the activation energy, 50.2 kJ/mol and its pH dependence at 1.1 °C was fitted to: k (s-1) = 520 + 6.5 × 107[H+] + 3.0 × 109[OH-].

  2. Removal of phenols from aqueous solutions by emulsion liquid membranes.

    Science.gov (United States)

    Reis, M Teresa A; Freitas, Ondina M F; Agarwal, Shiva; Ferreira, Licínio M; Ismael, M Rosinda C; Machado, Remígio; Carvalho, Jorge M R

    2011-09-15

    The present study deals with the extraction of phenols from aqueous solutions by using the emulsion liquid membranes technique. Besides phenol, two derivatives of phenol, i.e., tyrosol (2-(4-hydroxyphenyl)ethanol) and p-coumaric acid (4-hydroxycinnamic acid), which are typical components of the effluents produced in olive oil plants, were selected as the target solutes. The effect of the composition of the organic phase on the removal of solutes was examined. The influence of pH of feed phase on the extraction of tyrosol and p-coumaric was tested for the membrane with Cyanex 923 as an extractant. The use of 2% Cyanex 923 allowed obtaining a very high extraction of phenols (97-99%) in 5-6 min of contact time for either single solute solutions or for their mixtures. The removal efficiency of phenol and p-coumaric acid attained equivalent values by using the system with 2% isodecanol, but the removal rate of tyrosol was found greatly reduced. The extraction of tyrosol and p-coumaric acid from their binary mixture was also analysed for different operating conditions like the volume ratio of feed phase to stripping phase (sodium hydroxide), the temperature and the initial concentration of solute in the feed phase.

  3. Photocatalytic degradation of molinate in aqueous solutions.

    Science.gov (United States)

    Bizani, E; Lambropoulou, D; Fytianos, K; Poulios, I

    2014-11-01

    In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes. PMID:24928378

  4. Photocatalytic degradation of molinate in aqueous solutions.

    Science.gov (United States)

    Bizani, E; Lambropoulou, D; Fytianos, K; Poulios, I

    2014-11-01

    In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes.

  5. Characterization of aqueous silver nitrate solutions for leakage tests

    Directory of Open Access Journals (Sweden)

    José Ferreira Costa

    2011-06-01

    Full Text Available OBJECTIVE: To determine the pH over a period of 168 h and the ionic silver content in various concentrations and post-preparation times of aqueous silver nitrate solutions. Also, the possible effects of these factors on microleakage test in adhesive/resin restorations in primary and permanent teeth were evaluated. MATERIAL AND METHODS: A digital pHmeter was used for measuring the pH of the solutions prepared with three types of water (purified, deionized or distilled and three brands of silver nitrate salt (Merck, Synth or Cennabras at 0, 1, 2, 24, 48, 72, 96 and 168 h after preparation, and storage in transparent or dark bottles. Ionic silver was assayed according to the post-preparation times (2, 24, 48, 72, 96, 168 h and concentrations (1, 5, 25, 50% of solutions by atomic emission spectrometry. For each sample of each condition, three readings were obtained for calculating the mean value. Class V cavities were prepared with enamel margins on primary and permanent teeth and restored with the adhesive systems OptiBond FL or OptiBond SOLO Plus SE and the composite resin Filtek Z-250. After nail polish coverage, the permanent teeth were immersed in 25% or 50% AgNO3 solution and the primary teeth in 5% or 50% AgNO3 solutions for microleakage evaluation. ANOVA and the Tukey's test were used for data analyses (α=5%. RESULTS: The mean pH of the solutions ranged from neutral to alkaline (7.9±2.2 to 11.8±0.9. Mean ionic silver content differed depending on the concentration of the solution (4.75±0.5 to 293±15.3 ppm. In the microleakage test, significant difference was only observed for the adhesive system factor (p=0.000. CONCLUSIONS: Under the tested experimental conditions and based on the obtained results, it may be concluded that the aqueous AgNO3 solutions: have neutral/alkaline pH and service life of up to 168 h; the level of ionic silver is proportional to the concentration of the solution; even at 5% concentration, the solutions were

  6. Characterization of aqueous silver nitrate solutions for leakage tests

    Science.gov (United States)

    COSTA, José Ferreira; SIQUEIRA, Walter Luiz; LOGUERCIO, Alessandro Dourado; REIS, Alessandra; de OLIVEIRA, Elizabeth; ALVES, Cláudia Maria Coelho; BAUER, José Roberto de Oliveira; GRANDE, Rosa Helena Miranda

    2011-01-01

    Objectives To determine the pH over a period of 168 h and the ionic silver content in various concentrations and post-preparation times of aqueous silver nitrate solutions. Also, the possible effects of these factors on microleakage test in adhesive/resin restorations in primary and permanent teeth were evaluated. Material and Methods A digital pHmeter was used for measuring the pH of the solutions prepared with three types of water (purified, deionized or distilled) and three brands of silver nitrate salt (Merck, Synth or Cennabras) at 0, 1, 2, 24, 48, 72, 96 and 168 h after preparation, and storage in transparent or dark bottles. Ionic silver was assayed according to the post-preparation times (2, 24, 48, 72, 96, 168 h) and concentrations (1, 5, 25, 50%) of solutions by atomic emission spectrometry. For each sample of each condition, three readings were obtained for calculating the mean value. Class V cavities were prepared with enamel margins on primary and permanent teeth and restored with the adhesive systems OptiBond FL or OptiBond SOLO Plus SE and the composite resin Filtek Z-250. After nail polish coverage, the permanent teeth were immersed in 25% or 50% AgNO3 solution and the primary teeth in 5% or 50% AgNO3 solutions for microleakage evaluation. ANOVA and the Tukey's test were used for data analyses (α=5%). Results The mean pH of the solutions ranged from neutral to alkaline (7.9±2.2 to 11.8±0.9). Mean ionic silver content differed depending on the concentration of the solution (4.75±0.5 to 293±15.3 ppm). In the microleakage test, significant difference was only observed for the adhesive system factor (p=0.000). Conclusions Under the tested experimental conditions and based on the obtained results, it may be concluded that the aqueous AgNO3 solutions: have neutral/alkaline pH and service life of up to 168 h; the level of ionic silver is proportional to the concentration of the solution; even at 5% concentration, the solutions were capable of

  7. Preparation of CdTe nanocrystal-polymer composite microspheres in aqueous solution by dispersing method

    Institute of Scientific and Technical Information of China (English)

    LI Minjie; WANG Chunlei; HAN Kun; YANG Bai

    2005-01-01

    Highly fluorescent CdTe nanocrystals were synthesized in aqueous solution, and then processible CdTe nanocrystal-polymer composites were fabricated by coating the aqueous nanocrystals with copolymers of styrene and octadecyl-p-vinyl-benzyldimethylammonium chloride (SOV- DAC) directly. A dichloromethane solution of CdTe nano- crystal-polymer composites was dispersed in the aqueous solution of poly (vinyl alcohol) (PVA) generating highly fluorescent microspheres. Experimental parameters such as the concentration of nanocrystal-polymer composites, the concentration of PVA, and stirring speed which had important effect on the preparation of the microspheres were investigated in detail with fluorescent microscope characterization.

  8. INTERACTION OF POLYVINYLPYRROLIDONE WITH METAL CHLORIDE AQUEOUS SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    Mohammad Saleem Khan; Khaista Gul; Najeeb Ur Rehman

    2004-01-01

    Interactions of polyvinylpyrrolidone (PVP) with metal chlorides (MgCl2, CaCl2, KC1 and BaC12) have been investigated by viscometric and spectrophotometric techniques in aqueous solutions. Intrinsic viscosity [η] of (PVP) has shown a discontinuity with varying concentration of metal chlorides. The decreasing order of effectiveness of cation is K1+>Ca2+> Mg2+> Ba2+ for poly(vinylpyrrolidone) solution. Changes in the absorption spectra of the cosolutes were observed in the presence of PVP in the lower limit of the UV-visible region i.e. 200-210 nm. These changes were attributed to interaction of PVP molecules with the cosolute molecules. As the concentration of the cosolute increased, a red shift in the peaks was observed, indicating an increase in interaction between PVP and cosolutes.

  9. Adsorption of thorium from aqueous solutions by perlite.

    Science.gov (United States)

    Talip, Z; Eral, M; Hiçsönmez, U

    2009-02-01

    The use of expanded perlite for the adsorption of thorium from aqueous solution by batch technique is presented. The effects of particle size, pH of the solution, initial thorium concentration, shaking time, V/m ratio and temperature were determined. It was found that the adsorption capacity increases by the increase in the pH of the suspensions. The rate of thorium adsorption on expanded perlite was observed to be fast in the first hour of the reaction time. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models and the adsorption experiments conducted at 30 +/- 1 degrees C showed that the adsorption isotherms correlated well with the Langmuir model. From the adsorption data, thermodynamic parameters such as DeltaG(o), DeltaH(o) and DeltaS(o) were calculated as a function of temperature.

  10. Radiolysis of pentachlorophenol (PCP) in aqueous solution by gamma radiation

    Institute of Scientific and Technical Information of China (English)

    XUE Jun; WANG Jianlong

    2008-01-01

    Steady-state radiolysis experiments were performed to investigate the y-irradiation treatment of pentachlorophenol (PCP) in aqueoussolution. The effect of initial concentration on the PCP degradation was also investigated. The experimental results showed that γ-irradiation was able to degrade PCP in aqueous solution successfully, and the radiolytical degradation process of PCP could be describedby the first-order kinetic model. When the initial concentration of PCP was 25 and 50 mg/L and the radiation dose was 4 and 6 kGy,respectively, the degradation efficiency was 100%. A luminescence bacterial test was used for evaluating the toxicity of the radiolyticintermediate products. Total detoxification of a 75 mg/L PCP solution could be achieved by carrying out the irradiation procedure at the dose of 15 kGy.

  11. Density functional theory-based prediction of the formation constants of complexes of ammonia in aqueous solution: indications of the role of relativistic effects in the solution chemistry of gold(I).

    Science.gov (United States)

    Hancock, Robert D; Bartolotti, Libero J

    2005-10-01

    A prediction of the formation constants (log K1) for complexes of metal ions with a single NH3 ligand in aqueous solution, using quantum mechanical calculations, is reported. DeltaG values at 298 K in the gas phase for eq 1 (DeltaG(DFT)) were calculated for 34 metal ions using density functional theory (DFT), with the expectation that these would correlate with the free energy of complex formation in aqueous solution (DeltaG(aq)). [M(H2O)6]n+(g) + NH(3)(g) = [M(H2O)5NH3]n+(g) + H2O(g) (eq 1). The DeltaG(aq) values include the effects of complex changes in solvation on complex formation, which are not included in eq 1. It was anticipated that such changes in solvation would be constant or vary systematically with changes in the log K(1) value for different metal ions; therefore, simple correlations between DeltaG(DFT) and DeltaG(aq) were sought. The bulk of the log K1(NH3) values used to calculate DeltaG(aq) were not experimental, but estimated previously (Hancock 1978, 1980) from a variety of empirical correlations. Separate linear correlations between DeltaG(DFT) and DeltaG(aq) for metal ions of different charges (M2+, M3+, and M4+) were found. In plots of DeltaG(DFT) versus DeltaG(aq), the slopes ranged from 2.201 for M2+ ions down to 1.076 for M4+ ions, with intercepts increasing from M2+ to M4+ ions. Two separate correlations occurred for the M3+ ions, which appeared to correspond to small metal ions with a coordination number (CN) of 6 and to large metal ions with a higher CN in the vicinity of 7-9. The good correlation coefficients (R) in the range of 0.97-0.99 for all these separate correlations suggest that the approach used here may be the basis for future predictions of aqueous phase chemistry that would otherwise be experimentally inaccessible. Thus, the log K1(NH3) value for the transuranic Lr3+, which has a half-life of 3.6 h in its most stable isotope, is predicted to be 1.46. These calculations should also lead to a greater insight into the factors

  12. Preparation of metallic nanoparticles by irradiation in starch aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Nemţanu, Monica R., E-mail: monica.nemtanu@inflpr.ro; Braşoveanu, Mirela, E-mail: monica.nemtanu@inflpr.ro; Iacob, Nicuşor, E-mail: monica.nemtanu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Electron Accelerators Laboratory, 409 Atomiştilor St., PO Box MG-36, 077125, Bucharest-Măgurele (Romania)

    2014-11-24

    Colloidal silver nanoparticles (AgNPs) were synthesized in a single step by electron beam irradiation reduction of silver ions in aqueous solution containing starch. The nanoparticles were characterized by spectrophotocolorimetry and compared with those obtained by chemical (thermal) reduction method. The results showed that the smaller sizes of AgNPs were prepared with higher yields as the irradiation dose increased. The broadening of particle size distribution occurred by increasing of irradiation dose and dose rate. Chromatic parameters such as b* (yellow-blue coordinate), C* (chroma) and ΔE{sub ab} (total color difference) could characterize the nanoparticles with respect of their concentration. Hue angle h{sup o} was correlated to the particle size distribution. Experimental data of the irradiated samples were also subjected to factor analysis using principal component extraction and varimax rotation in order to reveal the relation between dependent variables and independent variables and to reduce their number. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those produced by chemical reduction method. Therefore, the electron beam irradiation is effective for preparation of silver nanoparticles using starch aqueous solution as dispersion medium.

  13. Removal of heavy metals from aqueous solution by sawdust adsorption

    Institute of Scientific and Technical Information of China (English)

    BULUT Yasemin; TEZ Zeki

    2007-01-01

    The adsorption of lead, cadmium and nicel from aqueous solution by sawdust of walnut was investigated. The effect of contact time,initial metal ion concentration and temperature on metal ions removal has been studied. The equilibrium time was found to be of the order of 60 min. Kinetics fit pseudo first-order, second-order and intraparticle diffusion models, hence adsorption rate constants were calculated. The adsorption data of metal ions at temperatures of 25, 45 and 60C have been described by the Freundlich and Langmuir isotherm models. The thermodynamic parameters such as energy, entropy and enthalpy changes for the adsorption of heavy metal ions have also been computed and discussed. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to the walnut sawdust. The selectivity order of the adsorbent is Pb(Ⅱ)≈Cd(Ⅱ)>Ni(Ⅱ). From these results, it can be concluded that the sawdust of walnut could be a good adsorbent for the metal ions from aqueous solutions.

  14. Efficient removal of mercury from aqueous solutions and industrial effluent.

    Science.gov (United States)

    Dos Santos, Maria B P; Leal, Katia Z; Oliveira, Fernando J S; Sella, Silvia M; Vieira, Méri D; Marques, Elisa M D; Gomes, Vanessa A C

    2015-01-01

    The objective of this study was to examine the ability of a solid waste produced during beneficiation of ornamental rocks to remove mercury (Hg) from an industrial effluent and aqueous solutions under various conditions. Batch studies have been carried out by observing the effects of pH, concentration of the adsorbate, contact time, and so on. Various sorption isotherm models such as Langmuir, Freundlich, and Tóth have been applied for the adsorbent. Film and intraparticle diffusion were both found to be rate-limiting steps. Adsorption was properly described by the Freundlich model (capacity constant of 0.3090 (mg g(-1))(mg L(-1))(-1/n) and adsorption intensity indicator of 2.2939), which indicated a favorable sorption and encouraged subsequent studies for treatment of Hg-containing industrial effluent. Industrial effluent treatment efficiency reached Hg removals greater than 90% by using ornamental rock solid waste (ORSW). Besides, desorption studies indicated that the maximum recovery of mercury was 100 ± 2% for 1 mol L(-1) HNO3 and 74 ± 8% for 0.1 mol L(-1) HNO3. The ORSW could be reused thrice without significant difference on the Hg removal rate from industrial effluent. These findings place ORSW as a promising efficient and low-cost adsorbent for the removal of Hg from aqueous solutions and industrial effluent. PMID:26301849

  15. The radiation chemistry of aqueous sodium terephthalate solutions

    International Nuclear Information System (INIS)

    The radiation chemistry of cobalt-60 gamma-irradiated aqueous sodium terephthalate solutions has been studied. In aerated 4 x 10-4M sodium hydroxide solutions, the main products are hydroxyterephthalate (HTA) (G = 0.99 +- 0.01), carbonate (G = 1.31 +- 0.08), and peroxides (G = 2.84 +- 0.04). The HTA and carbonate species are both formed as a result of hydroxyl radical attack and account for approximately 90 per cent of hydroxyl radical reactions. Oxygen needs to be present for efficient conversion of the terephthalate-OH radical adduct to HTA and oxygenation increases G(HTA) above the aerated solution value. G(HTA) is unaffected by changes in terephthalate concentration between 1 x 10-4M and 1 x 10-2M in sodium hydroxide solutions at pH 10. Decreasing the solution pH does however affect G(HTA). In phosphate buffered solutions pH 6.85, G(HTA) is 0.93 +- 0.01 and lower values are obtained with further decrease in solution pH. The lowering of the G(HTA) value is attributed to recombination reactions between the terephthalate-OH radical products and reducing radical products. Experimental evidence supporting the recombination postulate was obtained from the measurement of a parallel decrease in the peroxide yield and the observation of a dose rate effect on G(HTA). Competition kinetic studies with the added solutes carbonate and bicarbonate gave the rate ratios k (OH + TA2-) : k(OH + CO32-) : k(OH + HCO3-) = 1 : 0.105 : 0.0036

  16. Effect of acetate and carbonate buffers on the photolysis of riboflavin in aqueous solution: a kinetic study.

    Science.gov (United States)

    Ahmad, Iqbal; Anwar, Zubair; Iqbal, Kefi; Ali, Syed Abid; Mirza, Tania; Khurshid, Adeela; Khurshid, Aqeela; Arsalan, Adeel

    2014-06-01

    The photolysis of riboflavin (RF) in the presence of acetate buffer (pH 3.8-5.6) and carbonate buffer (pH 9.2-10.8) has been studied using a multicomponent spectrophotometric method for the simultaneous assay of RF and its photoproducts. Acetate and carbonate buffers have been found to catalyze the photolysis reaction of RF. The apparent first-order rate constants for the acetate-catalyzed reaction range from 0.20 to 2.86 × 10(-4) s(-1) and for the carbonate-catalyzed reaction from 3.33 to 15.89 × 10(-4) s(-1). The second-order rate constants for the interaction of RF with the acetate and the carbonate ions range from 2.04 to 4.33 × 10(-4) M(-1) s(-1) and from 3.71 to 11.80 × 10(-4) M(-1) s(-1), respectively. The k-pH profile for the acetate-catalyzed reaction is bell shaped and for the carbonate-catalyzed reaction a steep curve. Both HCO3(-) and CO3(2-) ions are involved in the catalysis of the photolysis reaction in alkaline solution. The rate constants for the HCO3(-) and CO3(2-) ions catalyzed reactions are 0.72 and 1.38 × 10(-3) M(-1) s(-1), respectively, indicating a major role of CO3(2-) ions in the catalysis reaction. The loss of RF fluorescence in acetate buffer suggests an interaction between RF and acetate ions to promote the photolysis reaction. The optimum stability of RF solutions is observed in the pH range 5-6, which is suitable for pharmaceutical preparations.

  17. Examination of rheological properties of aqueous solutions of sodium caseinate

    Directory of Open Access Journals (Sweden)

    Jolanta Gawałek

    2012-12-01

    Full Text Available Application of sodium caseinate as a functional additive in manufacturing processes requires production of its concentrated aqueous solutions which, in industrial conditions, presents a number of difficulties. In order to develop an effective and optimal industrial process of mixing – manufacturing a concentrated solution of sodium caseinate, it is essential to know rheological properties in a definite range of concentrations changing in the course of the dissolving process. The material for investigations was typical commercial sodium caseinate in the form of dry powder manufactured in Poland from acid casein using the method of extrusion. The objective of the undertaken empirical studies was the assessment of the impact of the concentration on rheological properties of sodium caseinate concentrates. Investigations were carried out for five concentrates manufactured in a mixer equipped in a mechanical agitator at concentrations ranging X (% Î (2.5¸12.5 and changing mass proportions of sodium caseinate in the aqueous solution as follows: GS/G (kgS·kg-1 = 0.025. On the basis of the obtained research results, classical flow curves were plotted for individual concentrates. The determined values of viscosity and density of the examined solutions were correlated in the form of h = f(GS/G and r = f(GS/G dependencies which were used during the determination of classical characteristics of mixing forces essential for the assessment of energetic expenditures required to manufacture concentrates in a mixer equipped in a mechanical agitator. The density of the examined concentrates increased in a way directly proportional, while the dynamic viscosity coefficient increased exponentially together with the increase of sodium caseinate concentration. Sodium caseinate concentrates exhibited Newtonian character in the examined range of concentrations.

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

    Science.gov (United States)

    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…

  19. Application of new biosorbent based on chemicaly modified Lagenaria vulgaris shell for the removal of copper(II from aqueous solutions: Effects of operational parameters

    Directory of Open Access Journals (Sweden)

    Kostić Miloš M.

    2013-01-01

    Full Text Available In present study a low cost biosorbent derived from Lagenaria vulgaris plant by xanthation, was tested for its ability to remove copper from aqueous solution. The effect of contact time, initial pH, initial concentration of copper(II ions and adsorbent dosage on the removal efficiency were studied in a batch process mode. The optimal pH for investigated metal was 5. A dosage of 4 g dm-3 of xanthated Lagenaria vulgaris biosorbent (xLVB was found to be effective for maximum uptake of copper(II. The kinetic of sorption of metal was fast, reaching at equilibrium in 50 min. The kinetic data were found to follow closely the pseudo-second-order model. The adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 23.18 mg g-1 copper(II ions on xLVB. The presence of sulfur groups on xLVB were identified by FTIR spectroscopic study. Copper removal efficiency was achieved at 81.35% from copper plating industry wastevater.

  20. Synthesis and Aqueous Solution Viscosity of Hydrophobically Modified Xanthan Gum

    Institute of Scientific and Technical Information of China (English)

    QIAN Xiao-lin; WU Wen-hui; YU Pei-zhi; WANG Jian-quan

    2007-01-01

    Two xanthan gum derivatives hydrophobically modified by 4 or 8 tetradecyl chains per 100 xanthan gum structure units were synthesized. The derivatives were studied by scanning electron microscope and pyrene fluorescence spectrometry. And the aqueous solution apparent viscosity of the derivatives was investigated. The results indicate that the network of the derivatives with more hydrophobic groups is closer and tighter. With increasing of alkyl chain substitution degree, the hydrophobically associating interactions enhance in aqueous solution. Aqueous solution apparent viscosity of the derivatives increases with increasing of polymer concentration and alkyl substitution degree, and decreases with the increase of temperature. In the brine solution, the strong viscosity enhancement phenomenon appears. The interaction between the derivatives and surfactant sodium dodecylbenzene sulfonate is strong.

  1. Biosorption of Lead Ions from Aqueous Solution Using Ficus benghalensis L.

    OpenAIRE

    Venkateswara Rao Surisetty; Janusz Kozinski; L. Rao Nageswara

    2013-01-01

    Ficus benghalensis L., a plant-based material leaf powder, is used as an adsorbent for the removal of lead ions from aqueous solution using the biosorption technique. The effects of process parameters such as contact time, adsorbent size and dosage, initial lead ion concentration, and pH of the aqueous solution on bio-sorption of lead by Ficus benghalensis L. were studied using batch process. The Langmuir isotherm was more suitable for biosorption followed by Freundlich and Temkin isotherms w...

  2. Radiation-induced destruction peculiarities of hydroxyl containing amino acids in diluted aqueous solution

    International Nuclear Information System (INIS)

    Amino acids aqueous solution of alpha-alanine and beta-alanine, serine, threonine (concentration 5*10-4 M) were irradiated with dose rate 0.35 Gy/s in range 100-1100 Gy and analysed. Effectiveness of radiation-induced decomposition process depends on row of factors: concentration of amino acid aqueous solution, pH, oxygen presence and other acceptors

  3. Effect of acidity on the equilibria of formation of mixed Co2+ complexes with heparin and arginine in aqueous solutions at 37°C

    Science.gov (United States)

    Feofanova, M. A.; Frantseva, Yu. V.; Semenov, A. N.; Baranova, N. V.; Zhuravlev, E. V.

    2014-02-01

    Results from studying interactions in the heparin-Co2+ ion-arginine system are presented. The constants of formation of mixed Co2+ complexes with heparin and arginine in aqueous solutions in a broad pH range at 37°C are determined potentiometrically. The chemical equilibria in the system are simulated and the stoichiometry of formation of the complex forms is determined.

  4. Degradation of chlorophenols in aqueous solution by {gamma}-radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hu Jun [INET, Tsinghua University, Beijing 100084 (China)]. E-mail: hujun@mail.tsinghua.edu.cn; Wang Jianlong [INET, Tsinghua University, Beijing 100084 (China)

    2007-08-15

    Degradation of chlorophenols (CPs) in aqueous solutions by {gamma}-radiation was studied. The effect of absorbed dose on degradation, dechlorination and mineralization of CPs were investigated. The results indicated that the degradation of CPs, Cl{sup -} release and mineralization increased with increase in absorbed dose. When the initial concentration was 100 mg L{sup -1} and the dosage was 6 kGy, the removal efficiencies of CPs were 44.54% for 2-CP, 91.46% for 3-CP, 82.72% for 4-CP and 93.25% for 2,4-DCP, respectively. The combination of irradiation and H{sub 2}O{sub 2} leads to a synergistic effect, which remarkably increased the degradation efficiency of CPs and TOC removal. The kinetics of CPs during irradiation are also mentioned.

  5. Degradation of chlorophenols in aqueous solution by γ-radiation

    Science.gov (United States)

    Hu, Jun; Wang, Jianlong

    2007-08-01

    Degradation of chlorophenols (CPs) in aqueous solutions by γ-radiation was studied. The effect of absorbed dose on degradation, dechlorination and mineralization of CPs were investigated. The results indicated that the degradation of CPs, Cl - release and mineralization increased with increase in absorbed dose. When the initial concentration was 100 mg L -1 and the dosage was 6 kGy, the removal efficiencies of CPs were 44.54% for 2-CP, 91.46% for 3-CP, 82.72% for 4-CP and 93.25% for 2,4-DCP, respectively. The combination of irradiation and H 2O 2 leads to a synergistic effect, which remarkably increased the degradation efficiency of CPs and TOC removal. The kinetics of CPs during irradiation are also mentioned.

  6. Adsorption of cesium on cement mortar from aqueous solutions.

    Science.gov (United States)

    Volchek, Konstantin; Miah, Muhammed Yusuf; Kuang, Wenxing; DeMaleki, Zack; Tezel, F Handan

    2011-10-30

    The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L(-1) and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive (137)Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L(-1) while the respective surface concentration on coupons varied from 0.0395 to 22.34 μg cm(-2). Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol(-1) suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar.

  7. Aqueous solution synthesis of zinc oxide for application in optoelectronics

    Science.gov (United States)

    Joo, John Hwajong

    Recently, ZnO has garnered widespread attention in the semiconductor community for its large set of useful properties, which include a wide bandgap and its resulting optical transparency, a large exciton binding energy, a significant piezoelectric response, and good electrical conductivity. In many ways, it shares many properties with a widely used and technologically important semiconductor GaN, which is widely used for blue LEDs and lasers. However, ZnO cannot substitute for GaN in most optoelectronic applications, because it cannot be doped p-type. On the other hand, unlike many traditional, covalently bonded semiconductors like GaN, ZnO can be easily formed aqueous solutions at close to room temperature and pressure in the form of large crystals or a variety of nanostructures, making possible applications that are normally very difficult with traditional semiconductors. In this light, we aimed to take advantage of aqueous solution-based, ZnO growth techniques and incorporated ZnO structures novel optoelectronic and photonic structures. By controlling the morphology of ZnO, we studied the effects of nanowire-based ZnO/Cu2O solar cells. Carrier collection was increased using a nanowire-based device architecture. The main result, however, was the time evolution of the performance of these devices due to the movement of ionized defects in the material. The effects of geometry on the ageing characteristics were studied, which showed that the carrier collection could be increased further with aging in a nanowire Cu2O solar cell. The aging behavior was substantially different between nanowire and planar solar cells, which implies that future design of nanostructured solar cells must long term aging effects. In addition to solar cells, we explored the possibilities of using aqueous solution growth of ZnO to fabricated whispering gallery mode optical cavities and waveguides for enhancing extraction from a single photon source. In both applications, we used templated

  8. Effectiveness of Rice Husk Ash in Removal of Phenolic Compounds from Aqueous Solutions, Equilibrium and Kinetics Studies

    OpenAIRE

    Majid Kermani; Mitra Gholami; Abdolmajid Gholizade; Mahdi Farzadkia; Ali Esrafili

    2012-01-01

    Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Background and Objectives: Phenols in trace quantities are usually present in the treated effluent of many wastewater-treatment plants. Phenol compounds even at low concentration can cause toxicity, health and significant taste and odor problem in drinking waters. This research focuses on understanding the sorption process and developing a cost-effective technology for the treatment of water contaminated with phe...

  9. Arsenic Removal from Aqueous Solutions by Salvadora persica Stem Ash

    Directory of Open Access Journals (Sweden)

    Ferdos Kord Mostafapour

    2013-01-01

    Full Text Available Arsenic is a naturally occurring metalloid, which is widely distributed in nature and is regarded as the largest mass poisoning in history. In the present study, the adsorption potential of Salvadora persica (S. persica stem ash in a batch system for the removal of As(V from aqueous solutions was investigated. Isotherm studies were carried out to evaluate the effect of contact time (20–240 min, pH (2–11, initial arsenic concentration (50–500 μg/L, and adsorbent dose on sorption efficiency. Maximum removal efficiency of 98.33% and 99.32% was obtained at pH 6, adsorbent dosage 3.5 g/L, initial As(V concentration 500 μg/L, and contact time 80 and 60 min for S. persica stem ash at 300 °C and 500 °C, respectively. Also, the adsorption equilibriums were analyzed by the Langmuir and Freundlich isotherm models. Such equilibriums showed that the adsorption data was well fitted with the Freundlich isotherm model for S. persica stem ash at both 300 °C and 500 °C (R2=0.8983 and 0.9274, resp.. According to achieved results, it was defined that S. persica stem ash can be used effectively for As(V removal from the aqueous environment.

  10. Conductivity of Oxalic Acid in Aqueous Solution at Low Concentration

    Institute of Scientific and Technical Information of China (English)

    倪良; 韩世钧

    2005-01-01

    Oxalic acid is a weak and unsymmetrical bi-basic acid. There exist dissociation and association equilibria among the species in aqueous solution. The molar conductivity of the solution is the sum of the ionic contributions.Based on this idea, a new prediction equation of ionic conductivity was proposed at low concentration. The molar conductivities of the solution and its relevant ions were calculated respectively. The results obtained were in good agreement with those from experiments and the Quint-Viallard equation.

  11. Ultrasound assisted destruction of estrogen hormones in aqueous solution: Effect of power density, power intensity and reactor configuration

    Energy Technology Data Exchange (ETDEWEB)

    Suri, Rominder P.S. [Villanova Center for the Environment, Department of Civil and Environmental Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085-4263 (United States)]. E-mail: rominder.suri@villanova.edu; Nayak, Mohan [Villanova Center for the Environment, Department of Civil and Environmental Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085-4263 (United States); Devaiah, Uthappa [Villanova Center for the Environment, Department of Civil and Environmental Engineering, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085-4263 (United States); Helmig, Edward [Wyeth Pharmaceuticals, Frazer, PA 19355 (United States)

    2007-07-31

    There are many reports documenting the adverse effects, such as feminization of fish, of estrogen hormones in the environment. One of the major sources of these compounds is from municipal wastewater effluents. The biological processes at municipal wastewater treatment plants cannot completely remove these compounds. This paper discusses the use of ultrasound to destroy estrogen compounds in water. The study examines the effect of ultrasound power density and power intensity on the destruction of various estrogen compounds which include: 17{alpha}-estradiol, 17{beta}-estradiol, estrone, estriol, equilin, 17{alpha}-dihydroequilin, 17{alpha}-ethinyl estradiol and norgestrel. These tests were conducted in single component batch and flow through reactors using 0.6, 2 and 4 kW ultrasound sources. The sonolysis process produced 80-90% destruction of individual estrogens at initial concentration of 10 {mu}g/L within 40-60 min of contact time. First order rate constants for the individual compounds under different conditions are presented. The estrogen degradation rates increase with increase in power intensity. However, the energy efficiency of the reactor was higher at lower power density. The 4 kW ultrasound reactor was more energy efficient compared to the 0.6 and 2 kW sonicators.

  12. Isotope effects in aqueous systems. 13. The hydrophobic interaction. Some thermodynamic properties of benzene/water and toluene/water solutions and their isotope effects

    International Nuclear Information System (INIS)

    Henry's law constants, K/sub H/ = K0 + K1X, have been measured as a function of concentration for the water-rich and benzene-rich solutions C6H6/H2O and C6H6/D2O and for the water-rich solutions C6D6/H2O and C6D6/D2O at several temperatures The constants K0 and K1 are sensitive to temperature and to isotopic label. The vapor pressure results have been supplemented with measurements of the apparent molar volumes of the solutions listed above, as well as for H2O- and D2O-rich solutions of toluene and deuteriotoluene, and with determinations of the solubilities and solubility isotope effects of the toluene solutions. The data have been interpreted in the context of the theory of isotope effects in condensed-phase systems. That analysis indicates that a significant dynamical vibrational coupling between solute and solvent normal modes occurs in these solutions. The result is of interest particularly as it pertains to models of the hydrophobic interaction

  13. Photoproducts of tetracycline and oxytetracycline involving self-sensitized oxidation in aqueous solutions: Effects of Ca2+ and Mg2+

    Institute of Scientific and Technical Information of China (English)

    Yong Chen; Hua Li; Zongping Wang; Tao Tao; Chun Hu

    2011-01-01

    Tetracyclines constitute one of the most important antibiotic families and represent a classic example of phototoxicity.The photoproducts of tetracyclines and their parent compounds have potentially adverse effects on natural ecosystem.In this study,the self-sensitized oxidation products of tetracycline (TC) and oxytetracycline (OTC) were determined and the effects of Ca2+ and Mg2+on self-sensitized degradation were investigated.The Ca2+ and Mg2+ in the natural water sample accounted for enhancement (pH 7.3)and inhibition (pH 9.0) of photodegradation of TC and OTC due to the formation of metal-ions complexes.The formation of Mg2+ complexes was unfavorable for the photodegradation of the tetracyclines at both pH values.In contrast,the Ca2+ complexes facilitated the attack of singlet oxygen (1O2) arising from self-sensitization at pH 7.3 and enhanced TC photodegradation.For the first time,selfsensitized oxidation products of TC and OTC were verified by quenching experiments and detected by LC/ESI-DAD-MS.The products had a nominal mass 14 Da higher than the parent drugs (designated M+14),which resulted from the 1O2 attack of the dimethylamino group on the C-4 atom of the tetracyclines.The presence of Ca2+ and Mg2+ also affected the generation of M+14 due to the formation of metal-ions complexes with TC and OTC.The findings suggest that the metal-ion complexation has significant impact on the selfsensitized oxidation processes and the photoproducts of tetracyclines.

  14. KINETICS OF HYDROLYSIS IN AQUEOUS-SOLUTION OF 1-BENZOYL-1,2,4-TRIAZOLE - THE ROLE OF PAIRWISE AND TRIPLET GIBBS ENERGY INTERACTION PARAMETERS IN DESCRIBING THE EFFECTS OF ADDED SALTS AND ADDED ALCOHOLS

    NARCIS (Netherlands)

    NOORDMAN, WH; BLOKZIJL, W; ENGBERTS, JBF; BLANDAMER, MJ

    1995-01-01

    Kinetic data are reported for the spontaneous hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solutions at ambient-pressure and 298.2 K, in aqueous solutions containing added ethanol, propanol and sodium chloride. Kinetic-data are also reported for the same reaction in aqueous mixtures of sodium c

  15. Kinetics of hydrolysis in aqueous solution of 1-benzoyl-1,2,4-triazole; the role of pairwise and triplet Gibbs energy interaction parameters in describing the effects of added salts and added alcohols

    NARCIS (Netherlands)

    Noordman, Wouter H.; Blokzijl, Wilfried; Engberts, Jan B.F.N.; Blandamer, Michael J.

    1995-01-01

    Kinetic data are reported for the spontaneous hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solutions at ambient pressure and 298.2 K, in aqueous solutions containing added ethanol, propanol and sodium chloride. Kinetic data are also reported for the same reaction in aqueous mixtures of sodium c

  16. Molecular Weight and Aggregation of Erwinia Gum in Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weight-average molecular weights Mw, number-average molecular weights Mn and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.

  17. Reorientation and Allied Dynamics in Water and Aqueous Solutions

    Science.gov (United States)

    Laage, Damien; Stirnemann, Guillaume; Sterpone, Fabio; Rey, Rossend; Hynes, James T.

    2011-05-01

    The reorientation of a water molecule is important for a host of phenomena, ranging over—in an only partial listing—the key dynamic hydrogen-bond network restructuring of water itself, aqueous solution chemical reaction mechanisms and rates, ion transport in aqueous solution and membranes, protein folding, and enzymatic activity. This review focuses on water reorientation and related dynamics in pure water, and for aqueous solutes with hydrophobic, hydrophilic, and amphiphilic character, ranging from tetra-methylurea to halide ions and amino acids. Attention is given to the application of theory, simulation, and experiment in the probing of these dynamics, in usefully describing them, and in assessing the description. Special emphasis is placed on a novel sudden, large-amplitude jump mechanism for water reorientation, which contrasts with the commonly assumed Debye rotational diffusion mechanism, characterized by small-amplitude angular motion. Some open questions and directions for further research are also discussed.

  18. Degradation of carbofuran in aqueous solution by ultrasound and Fenton processes: Effect of system parameters and kinetic study.

    Science.gov (United States)

    Ma, Ying-Shih; Sung, Chi-Fanga; Lin, Jih-Gaw

    2010-06-15

    To establish an efficient oxidation process for carbofuran degradation, the effects of some operating parameters such as dosages of H(2)O(2), Fe(2+) and initial carbofuran concentrations were observed during carbofuran degradation by the ultrasound process, Fenton process and a combined ultrasound/Fenton process. The degradation kinetics of carbofuran was also examined based on the experimental data. The results show that more than 99% of the carbofuran was degraded by the ultrasound/Fenton process within short reaction time periods. Increased dosages of H(2)O(2) and Fe(2+) enhanced the degradation of carbofuran in the ultrasound and Fenton oxidation processes, but initial carbofuran concentrations decreased carbofuran degradation in both the Fenton and ultrasound/Fenton processes. The degradation kinetics of carbofuran by the three oxidation processes was found to be in accordance with first-order reaction kinetics. The results provide fundamental information about the treatment of carbofuran wastewater and/or other pesticides by the ultrasound/Fenton oxidation process.

  19. Effectiveness of Rice Husk Ash in Removal of Phenolic Compounds from Aqueous Solutions, Equilibrium and Kinetics Studies

    Directory of Open Access Journals (Sweden)

    Majid Kermani

    2012-04-01

    Full Text Available Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Background and Objectives: Phenols in trace quantities are usually present in the treated effluent of many wastewater-treatment plants. Phenol compounds even at low concentration can cause toxicity, health and significant taste and odor problem in drinking waters. This research focuses on understanding the sorption process and developing a cost-effective technology for the treatment of water contaminated with phenolic compounds, which are discharged into the aquatic environment from a variety of sources. In order to remove phenolic compounds from water, a new natural sorbent, rice husk ash, was developed.Materials and Methods: Removal of phenol, 2-chlorophenol and 4-chlorophenol were characterized by spectrophotometric technique at wavelengths of 269.5, 274 and 280 nm, respectively, under batch equilibrium conditions and via changing the parameters of contact time, initial pH, and initial concentration of adsorbates and dosages of sorbent. Finally, the results were analyzed by the kinetic and isotherm models.Results: in this study, the equilibrium time was found to be 240 min for full equilibration of adsorbates. Removal percent of 2-chlorophenol was lower than two others. The maximum removal of phenol, 2-CP and 4-CP was observed at an initial pH of 5. The percentage removal of these phenolic compounds increased with increasing adsorbent dose and decreasing initial concentration. In kinetics studies, correlation coefficient and ARE factor showed that the sorption of phenol (R2=0.9999, 2-chlorophenol (R2=0.9992 and 4-chlorophenol (R2=1 fitted by pseudo second order model. Isotherm studies also revealed that, Langmuirmodel for phenol (R2=0.9499, Freundlich model for 2-chlorophenol (R2=0.9659 and 4-chlorophenol (R2=0.9542 were the best choices to describe the sorption behaviors.Conclusion: Sorption process is highly dependent on the pH and it affects adsorbent surface

  20. γ-Irradiation of malic acid in aqueous solutions

    Science.gov (United States)

    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.

  1. Gamma-irradiation of malic acid in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Negron-Mendoza, A.; Graff, R.L.; Ponnamperuma, C.

    1980-12-01

    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.

  2. Aqueous dispersions of silver nanoparticles in polyelectrolyte solutions

    Indian Academy of Sciences (India)

    Dan Donescu; Raluca Somoghi; Marius Ghiurea; Raluca Ianchis; Cristian Petcu; Stefania Gavriliu; Magdalena Lungu; Claudia Groza; Carmen R Ionescu; Carmen Panzaru

    2013-03-01

    In this report, we present the versatile and effective technique, using environmental friendly reductant glucose, to prepare stable silver nanodispersions by reduction of Ag+ ions. Alternant copolymers of maleic anhydride with vinyl acetate and styrene sulphonate sodium acid salt polyelectrolytes were synthesized in aqueous solution and used as stabilizers. The formation of nano silver particles was confirmed by UV-Vis spectrophotometry and TEM measurements. Dynamic Light Scattering (DLS) measurements were needed to study how the reagents and their concentrations influence particle size. SEM images show the nanostructure of the hybrid films and indicate a strong interaction between the polyelectrolyte and the silver NPs. Moreover, the silver NPs could be stored for one year without observation of aggregates or sedimentation. The final solid products obtained after evaporating to dryness can be used to produce stable dispersions upon mixing with water. Few of the final products were found to exhibit a high antibacterial and antifungal activity.

  3. [Extraction of alpha-cypermethrin from aqueous methanol solutions].

    Science.gov (United States)

    Shormanov, V K; Chigareva, E N; Belousova, O V

    2010-01-01

    Alpha cypermethrin was extracted from aqueous methanol solutions using hydrophobic organic solvents. The efficiency of extraction was shown to depend on the chemical nature of the solvent, the water to methanol ratio, and saturation of the aqueous methanol layer with an electrolyte. Optimal extraction of alpha-cypermethrin was achieved using toluene as the solvent under desalinization conditions. The extraction factor for the removal of the sought amount of alpha-cypermethrin from the water-methanol solution (4:1) using various solvents was calculated.

  4. Ionisation constants of inorganic acids and bases in aqueous solution

    CERN Document Server

    Perrin, D D

    2013-01-01

    Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution, Second Edition provides a compilation of tables that summarize relevant data recorded in the literature up to the end of 1980 for the ionization constants of inorganic acids and bases in aqueous solution. This book includes references to acidity functions for strong acids and bases, as well as details about the formation of polynuclear species. This text then explains the details of each column of the tables, wherein column 1 gives the name of the substance and the negative logarithm of the ionization constant and column 2

  5. Predicting accurate absolute binding energies in aqueous solution

    DEFF Research Database (Denmark)

    Jensen, Jan Halborg

    2015-01-01

    Recent predictions of absolute binding free energies of host-guest complexes in aqueous solution using electronic structure theory have been encouraging for some systems, while other systems remain problematic. In this paper I summarize some of the many factors that could easily contribute 1-3 kcal......-represented by continuum models. While I focus on binding free energies in aqueous solution the approach also applies (with minor adjustments) to any free energy difference such as conformational or reaction free energy differences or activation free energies in any solvent....

  6. Degradation kinetics of benzyl nicotinate in aqueous solution

    Directory of Open Access Journals (Sweden)

    Mbah C

    2010-01-01

    Full Text Available The degradation of benzyl nicotinate in aqueous solution over a pH range of 2.0-10.0 at 50±0.2 o was studied. The degradation was determined by high performance liquid chromatography. The degradation was observed to follow apparent first-order rate kinetics and the rate constant for the decomposition at 25 o was estimated by extrapolation. The reaction was shown to be hydroxide ion catalyzed and the Arrhenius plots showed the temperature dependence of benzyl nicotinate degradation. A significant increase in the stability of benzyl nicotinate was observed when glycerol or polyethylene glycol 400 was incorporated into the aqueous solution.

  7. Valence Electronic Structure of Aqueous Solutions: Insights from Photoelectron Spectroscopy

    Science.gov (United States)

    Seidel, Robert; Winter, Bernd; Bradforth, Stephen E.

    2016-05-01

    The valence orbital electron binding energies of water and of embedded solutes are crucial quantities for understanding chemical reactions taking place in aqueous solution, including oxidation/reduction, transition-metal coordination, and radiation chemistry. Their experimental determination based on liquid-photoelectron spectroscopy using soft X-rays is described, and we provide an overview of valence photoelectron spectroscopy studies reported to date. We discuss principal experimental aspects and several theoretical approaches to compute the measured binding energies of the least tightly bound molecular orbitals. Solutes studied are presented chronologically, from simple electrolytes, via transition-metal ion solutions and several organic and inorganic molecules, to biologically relevant molecules, including aqueous nucleotides and their components. In addition to the lowest vertical ionization energies, the measured valence photoelectron spectra also provide information on adiabatic ionization energies and reorganization energies for the oxidation (ionization) half-reaction. For solutes with low solubility, resonantly enhanced ionization provides a promising alternative pathway.

  8. Biosorption of arsenic from aqueous solution using dye waste.

    Science.gov (United States)

    Nigam, Shubha; Vankar, Padma S; Gopal, Krishna

    2013-02-01

    The purpose of this study is to examine on removal of arsenic from water by biosorption through potential application of herbal dye wastes. Four different flower dye residues (after extraction of natural dye) viz. Hibiscus rosasinensis, Rosa rosa, Tagetes erecta, and Canna indica were utilized successfully for the removal of arsenic from aqueous solution. Batch studies were carried out for various parameters viz. pH, sorbent dose, contact time, initial metal ion concentration, and temperature. Data were utilized for isothermal, kinetic, and thermodynamic studies. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDAX), and Fourier transform infrared (FTIR) analyses of biomass were performed. The results showed that 1 g/100 ml for 5.0-5.5 h contact time at pH 6.0-7.5 with agitation rate 150 rpm provided 98, 96, 92, and 85 % maximum absorption of arsenic by R. rosa, H. rosasinensis, T. erecta, and C. indica, respectively, at initial concentration of 500 ppb. Data followed Langmuir isotherm showing sorption to be monolayer on heterogeneous surface of biosorbent. Negative values of ΔG° indicated spontaneous nature, whereas ΔH° indicates exothermic nature of system followed by pseudo-first-order adsorption kinetics. FTIR results showed apparent changes in functional group regions after metal chelation. SEM and EDAX analyses showed the changes in surface morphology of all test biosorbents. Herbal dye wastes, used as biosorbent, exhibited significant (85-98 %) removal of arsenic from aqueous solution. Hence, these biosorbents are cost-effective, easily available, eco-friendly, and comparatively more effective than other biosorbents already in use. These may be used to remove arsenic and other toxic metals from water. PMID:22661261

  9. LIGHT SCATTERING OF POLYSACCHARIDE FROM LACQUER IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lina; DU Yumin; KUMANOTANI JU

    1989-01-01

    The polysaccharide having weight-average molecular weight Mw= 1. 09 × 105 , isolated from the sap of lac trees ( Vietnam ), was separated into 12 fractions by aqueous-phase preparative gel permeation chromatography. The molecular weights and molecular weight distributions of the fractions were measured in aqueous 0.08M KCl/0.01 M NaAc and 0.4M KCl/0.05M NaAc at pH = 7.6 by light scattering, viscometry and gel permeation chromatography. The Mark-Houwink equation in aqueous 0.08M KCl/0.01M NaAc at30 ℃ was found to be [ η] = 2.28 ×10-2 M0.52w ( cm3/g ), which indicated the polysaccharide chain in the aqueous solution to be a spherical random coil.

  10. Aqueous solution of basic fuchsin as food irradiation dosimeter

    Institute of Scientific and Technical Information of China (English)

    Hasan M. KHAN; Shagufta NAZ

    2007-01-01

    Dosimetric characterization of aqueous solution of basic fuchsin was studied spectrophotometrically for possible application in the low-dose food irradiation dosimetry. Absorption spectra of unirradiated and irradiated solutions were determined and the decrease in absorbance with the dose was noted down. Radiation-induced bleaching of the dye was measured at wavelengths of maximum absorption λmax (540nm) as well as 510nm and 460 nm. At all these wavelengths, the decrease in absorbance of the dosimeter was linear with respect to the absorbed dose from 50 Gy to 600 Gy. The stability of dosimetric solution during post-irradiation storage in the dark at room temperature showed that after initial bleaching during first ten to twenty days, the response was almost stable for about 34 days. The study on the effect of different light and temperature conditions also showed that the response gradually decreased during the storage period of 34 days, which shows that basic fuchsin dye is photosensitive as well as thermally sensitive.

  11. Demonstration of reverse symmetry waveguide sensing in aqueous solutions

    DEFF Research Database (Denmark)

    Horvath, R.; Pedersen, H.C.; Larsen, N.B.

    2002-01-01

    A reverse symmetry waveguide is presented for evanescent wave sensing in aqueous solutions. The waveguide consists of a thin polystyrene film, supported by a thicker substrate layer of nanoporous silica on glass. The nanoporous substrate layer has a refractive index of n(S)=1.193, hence, with an ......A reverse symmetry waveguide is presented for evanescent wave sensing in aqueous solutions. The waveguide consists of a thin polystyrene film, supported by a thicker substrate layer of nanoporous silica on glass. The nanoporous substrate layer has a refractive index of n(S)=1.193, hence......, with an aqueous cover refractive index of n(C)=1.331, a reverse symmetry (n(S)

  12. Cations bind only weakly to amides in aqueous solutions.

    Science.gov (United States)

    Okur, Halil I; Kherb, Jaibir; Cremer, Paul S

    2013-04-01

    We investigated salt interactions with butyramide as a simple mimic of cation interactions with protein backbones. The experiments were performed in aqueous metal chloride solutions using two spectroscopic techniques. In the first, which provided information about contact pair formation, the response of the amide I band to the nature and concentration of salt was monitored in bulk aqueous solutions via attenuated total reflection Fourier transform infrared spectroscopy. It was found that molar concentrations of well-hydrated metal cations (Ca(2+), Mg(2+), Li(+)) led to the rise of a peak assigned to metal cation-bound amides (1645 cm(-1)) and a decrease in the peak associated with purely water-bound amides (1620 cm(-1)). In a complementary set of experiments, the effect of cation identity and concentration was investigated at the air/butyramide/water interface via vibrational sum frequency spectroscopy. In these studies, metal ion-amide binding led to the ordering of the adjacent water layer. Such experiments were sensitive to the interfacial partitioning of cations in either a contact pair with the amide or as a solvent separated pair. In both experiments, the ordering of the interactions of the cations was: Ca(2+) > Mg(2+) > Li(+) > Na(+) ≈ K(+). This is a direct cationic Hofmeister series. Even for Ca(2+), however, the apparent equilibrium dissociation constant of the cation with the amide carbonyl oxygen was no tighter than ∼8.5 M. For Na(+) and K(+), no evidence was found for any binding. As such, the interactions of metal cations with amides are far weaker than the analogous binding of weakly hydrated anions.

  13. Catalytic destruction of hazardous organics in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Baker, E.G.; Sealock, L.J. Jr.

    1988-04-01

    Pacific Northwest Laboratory (PNL) is developing a process for destroying hazardous organics and chlorinated organics in aqueous solutions. The process is targeted at liquid waste streams that are difficult and costly to treat with conventional or developing technologies. Examples of these waste streams include contaminated groundwater and surface water and industrial wastewater. Aqueous solutions are treated with a transition metal catalyst at 300/degree/C to 460/degree/C and 2000 to 5000 psig pressure to convert the wastes to innocuous gases. During proof-of-principle tests conducted in a 1-L batch reactor, destruction of over 99/percent/ (in most cases approaching 99.9/percent/) of the organic material was achieved. Hexone (methyl is isobutyl ketone, MIBK), p-cresol, hexane, benzene, and naphthalene were used as model waste materials. The only major product with all of the organic compounds was a gas containing 50/percent/ to 75/percent/ methane, 25/percent/ to 45/percent/ carbon dioxide, and 0/percent) to 5/percent/ hydrogen. Reduced nickel was the only effective catalyst and that the optimal operating conditions for destroying nonchlorinated organics were 350/degree/C to 400/degree/C, 2000 to 4000 psig, and 30/endash/ to 60/endash/min residence time. These tests also indicated that catalyst deactivation or fouling would not be a problem at these conditions. Chlorobenzene and trichloroethylene (TEC), were also tested. Destruction of both compounds was 99/percent/ or greater, but the products were different from those obtained from hydrocarbons. With TCE, the major product was carbon dioxide; with chlorobenzene the major product identified was benzene. In the tests with the chlorinated hydrocarbons, the chlorine was converted to HC1 and the reduced nickel was converted to nickel hydroxide, which may be detrimental to long-term catalyst activity. (15 refs., 8 figs., 6 tabs).

  14. Humic acid removal from aqueous solutions by peroxielectrocoagulation process

    Directory of Open Access Journals (Sweden)

    Ahmad Reza Yazdanbakhsh

    2015-06-01

    Full Text Available Background: Natural organic matter is the cause of many problems associated with water treatment such as the presence of disinfection by-products (DBPs and membrane fouling during water filtration. In this study, the performance of the peroxi-electrocoagulation process (PEP was investigated for the removal of humic acids (HAs from aqueous solutions. Methods: PEP was carried out for the removal of HA using a plexiglas reactor with a volume of 2 L and fitted with iron electrodes and a direct current supply (DC. Samples were taken at various amounts of pH (2-4, current density (1 and 2A/cm2, hydrogen peroxide (50-150 mg/L and reaction time (5-20 minutes and then filtered to remove sludge formed during reaction. Finally, the HA concentration was measured by UV absorbance at 254 nm (UV254. Results: Results indicated that increasing the concentration of H2O2 from 50 to 150 mg/L increased HA removal efficiency from 83% to 94.5%. The highest removal efficiency was observed at pH 3.0; by increasing the pH to the alkaline range, the efficiency of the process was reduced. It was found that HA removal efficiency was high in current density 1A/cm2. Increasing current density up to 1 A cm-2 caused a decrease in removal efficiency. Results of this study showed that under the optimum operating range for the process ([current density] = 1A/cm2, [hydrogen peroxide concentration] = 150 mg/L, [reaction time]= 20 minutes and [pH]= 3.0, HA removal efficiency reached 98%. Conclusion: It can be concluded that PEP has the potential to be utilized for cost-effective removal of HA from aqueous solutions.

  15. Influence aqueous solutions on the mechanical behavior of argillaceous rocks

    International Nuclear Information System (INIS)

    The hydration of the shale with an aqueous solution induces a swelling deformation which plays an important role in the behaviour of the structures excavated in this type of grounds. This deformation is marked by a three-dimensional and anisotropic character and involves several mechanisms like adsorption, osmosis or capillarity. Several researches were dedicated to swelling and were often much debated due to the complexity of the implied phenomena. The goal of this thesis is therefore to contribute to a better understanding of shale swelling when the rock is confined and hydrated with an aqueous solution. The main part of the work accomplished was related to the Lorraine shale and to the Tournemire shale. To characterize swelling and to identify the main governing parameters, it was necessary to start the issue with an experimental approach. Many apparatus were then developed to carry out tests under various conditions of swelling. In order to facilitate the interpretation of the tests and thereafter the modelling of the behaviour, the experimental procedure adopted consisted of studying first the mechanical aspect and then the chemical aspect of swelling. In the mechanical part, swelling was studied by imposing on the sample a mechanical loading while maintaining during the tests the same aqueous solution. The principal parameters which were studied are the effect of the lateral conditions on axial swelling (impeded strain or constant stress) as well as the influence of the axial stress on radial swelling. The anisotropy of swelling was studied by carrying out, for different orientations of the sample, tests of free swelling, impeded swelling and uniaxial swelling. These various mechanical tests allowed to study the three-dimensional anisotropic swelling in all the conditions and to select the most appropriate test to be used in the second phase of the research. The precise analysis performed to explain the mechanisms behind the swelling of an argillaceous rock

  16. Investigation of Durasil absorbers for the removal of radionuclides from aqueous solutions

    International Nuclear Information System (INIS)

    Inorganic ion-exchange materials supplied by the Duratek Corporation, Maryland, USA have been tested in batch contact experiments to assess their effectiveness in removing radionuclides from aqueous solutions. The three absorbers tested, D10, D70 and D190, showed an affinity for all fourteen radionuclides present in the test solutions. (author)

  17. Cost effective and shape controlled approach to synthesize hierarchically assembled NiO nanoflakes for the removal of toxic heavy metal ions in aqueous solution

    Indian Academy of Sciences (India)

    K Yogesh Kumar; H B Muralidhara; Y Arthoba Nayaka; H Hanumanthappa; M S Veena; S R Kiran Kumar

    2015-02-01

    Hierarchical mesoporous NiO nanoflakes (NiOs) have been synthesized in high yield via a simple, economical and environmentally friendly hydrothermal route. The as-prepared NiOs were characterized by powder X-ray diffraction (PXRD), scanning electronicmicroscopy (SEM), transmission electronmicroscopy (TEM), selected area electron diffraction patterns (SAED), X-ray energy dispersive spectroscopy (EDS) and nitrogen adsorption–desorption techniques (Brunauer–Emmett–Teller, BET). Adsorption of heavy metal ions onto the as-prepared sample from aqueous solutions was investigated using differential pulse anodic stripping voltametry (DPASV) technique and discussed. The product possesses a BET surface area of 69.27 m2 g-1. It is found that NiOs exhibited the excellent performance for the removal of Hg(II), Pb(II) and Cd(II) from aqueous solution. The equilibrium adsorption data of Hg(II), Pb(II) and Cd(II) on the as-prepared NiOs were analyzed by Langmuir and Freundlich models, suggesting that the Langmuir model provides the better correlation of the experimental data. The adsorption capacities for removal of Hg(II), Pb(II) and Cd(II) were determined using the Langmuir equation and found to be 1324.5, 1428.9 and 1428.5 mg g-1, respectively. Adsorption kinetics of all the metal ions followed pseudo second-order model. Moreover, NiOs can be recycled by simple acid treatment, which could retain the high removal efficiency in three successive cycles. This study suggests that nanoflakes could be explored as a new adsorbent with high efficiency and recyclability for removing heavy metal ions from aqueous solution.

  18. Permeability in a state of partial solidification of aqueous solution

    Science.gov (United States)

    Okada, Masashi; Kang, Chaedong; Okiyama, Haruhiko

    A mushy region was formed by solidifying NaCl aqueous solution in a circular tube or a rectangular tube. The measurements of permeability were performed by changing volume fraction of liquid region in the mushy region. The dendritic ice in the solidification process was observed with a CCD microscope. The following results were obtained. The permeability increases with the volume fraction of liquid phase, and decreases with increasing the super-cooling degree of the solution or increasing the initial concentration of the solution, and is constant after the mushy region was formed. The arm space of dendrite becomes narrower as the super-cooling degree of the solution increases.

  19. [Pulsed radiolysis of aqueous solutions of serum albumin containing naphthoquinones].

    Science.gov (United States)

    Pribush, A G; Savich, A V

    1987-01-01

    As was shown by the pulse radiolysis method the simultaneous presence of naphthoquinone and human serum albumin molecules in an aqueous solution leads to the adsorption of the former on the surface of the latter. It is suggested that in these conditions the protein tertiary structure changes. New conformation reduces the reactivity of albumin toward the hydrated electron. PMID:3628723

  20. Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aqueous solution containing a reactive extractant, like borate salts, borate complexes, a monosalt of dicarboxylic acid,hydroxypropyl-cyclodextrins, and silver nitrate, shows limited potential to be used. Another approach, in which the alcohol is chemically modified prior to the extraction into an easy-extractable form, in this case a monoesterlcarboxylic acid, shows much more potential. An environmentally benign aqueous solution of sodium hydrogen carbonate can provide a distribution ratio of benzyl alcohol up to 200, leaving the solubility of the organic solvent in the aqueous solution unchanged relative to pure water and therefore increasing the selectivity with two orders of magnitude. The modification of aromatic, cyclo-aliphatic, and linear aliphatic alcohols can be performed efficiently in the apolar organic solvent without need for a catalyst. The recovery of the modified alcohol can be performed by back-extraction in combination with a spontaneous hydrolysis.

  1. Neodymium(3) complexing with bischloromethylphosphinic acid in aqueous solution

    International Nuclear Information System (INIS)

    High resolution spectrography is used to study Nd3+ complexing with (ClCH2)2POOH(HL) in aqueous solution. NdL2+ complex (lg Kstab = 0.44±0.04) with the corresponding absorption band with a maximum at λ=4283 A is formed in a system

  2. Gamma radiolysis of aqueous solutions of glycerin α-monochlorohydrin

    International Nuclear Information System (INIS)

    Data on γ-radiolysis of 0.1 mol/l aqueous solutions of glycerin α-monochlorohydrin (GMC) are presented. The radiolysis mechanism is considered. The rate constant of GMC reaction with esub(aq) k=(6.8+-0.8)x108 l/molxs is determined on the basis of experimental data

  3. DETERMINATION OF CHLORHEXIDINE IN SALIVA AND IN AQUEOUS-SOLUTIONS

    NARCIS (Netherlands)

    de Vries, J.; Ruben, J; Arends, J.

    1991-01-01

    A new method is presented for the determination of chlorhexidine in centrifuged saliva and in aqueous solutions by means of fluorescence spectroscopy. The method relies on complex formation between chlorhexidine and eosin. The fluorescence value of the chlorhexidine-eosin system decreases with incre

  4. Solubility of carbon dioxide in aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W. J.; Dijkstra, H. B. S.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    In the present work, new experimental data are presented on the solubility of carbon dioxide in aqueous piperazine solutions, for concentrations of 0.2 and 0.6 molar piperazine and temperatures of 25, 40, and 70°C respectively. The present data, and other data available in the literature, were corr

  5. Adsorption of copper ions from aqueous solutions on natural zeolite

    OpenAIRE

    Zendelska, Afrodita; Golomeova, Mirjana; Blažev, Krsto; Krstev, Boris; Golomeov, Blagoj; Krstev, Aleksandar

    2015-01-01

    The adsorption of copper ions from synthetic aqueous solutions on natural zeolite (clinoptilolite) was examined. In order to determine the rate of adsorption and the copper uptake at equilibrium, a series of experiments were performed under batch conditions from single ion solutions. Equilibrium data were evaluated based on adsorption (Langmuir and Freundlich) isotherms. The adsorption kinetics is reasonably fast. In the first 20 min of the experiment, approximately 80% of Cu2+ io...

  6. Biosorption of mercury from aqueous solutions using highly characterised peats

    OpenAIRE

    A.M. Rizzuti; F.L. Ellis; L.W. Cosme; A.D. Cohen

    2015-01-01

    This research investigated the biosorption of mercury from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after being treated with hydrochloric acid (HCl) to free up any occupied exchange sites. Other variables tested were sample dose, contact time, mixing temperature, and the concentration and pH of the mercury solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re...

  7. Utilization of Mg2Al-layered double hydroxide as an effective sequestrator to trap Cu(II) ions from aqueous solution impacted by water quality parameters

    Science.gov (United States)

    Xu, Meng; Linghu, Wensheng; Hu, Jun; Jiang, Gongyi; Sheng, Jiang

    2016-11-01

    Recently, Mg2Al-layered double hydroxide (Mg2Al-LDH) has been extensively studied as promising candidates to trap metal ions due to their high complexation and adsorption capacity. Herein, Mg2Al-LDH was utilized as an effectiveness sequestrator to trap Cu(II) ions from aqueous solution by an adsorption process using batch technique under ambient conditions. The results showed that Cu(II) adsorption on Mg2Al-LDH increases with pH increasing and maintains a high level at pH>7.0. The adsorption of Cu(II) was obviously affected by ionic strength at low pH, which was not dependent on ionic strength at high pH. The presence of HA or FA promotes the adsorption of Cu(II) on Mg2Al-LDH at low pH values, while reduces the adsorption of Cu(II) at high pH values. The adsorption isotherms of Cu(II) on Mg2Al-LDH at three different temperatures were simulated by the Langmuir, Freundlich, and Dubinin-Radushkevitch (D-R) models very well. The thermodynamic parameters were determined from the temperature-dependent adsorption, and the results showed that Cu(II) adsorption on Mg2Al-LDH was exothermic and the process was favored at high temperature. The results suggest that Mg2Al-LDH is suitable as a sorbent material for the recovery and attenuation of Cu(II)-polluted wastewater.

  8. Effects of the steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent on the adsorption of p-nitroaniline in aqueous solution

    International Nuclear Information System (INIS)

    Graphical abstract: The hyper-cross-linked polymeric adsorbents (GQ-05 and GQ-03) with different steric hindrance of micropores were designed. The adsorption capacity and adsorption rate of PNA onto the two adsorbents followed the order GQ-05 > GQ-03. The steric hindrance of micropores was a crucial factor for the adsorption capacity and adsorption rate order. - Highlights: • Two adsorbents with different steric hindrance of micropores were designed. • The adsorption capacity and adsorption rate followed the order GQ-05 > GQ-03. • The steric hindrance of micropores was a crucial factor for the order. - Abstract: A hyper-cross-linked polymeric adsorbent with “-CH2-phenol-CH2-” as the cross-linked bridge (denoted GQ-05), and another hyper-cross-linked polymeric adsorbent with “-CH2-p-cresol-CH2-” as the cross-linked bridge (denoted GQ-03) were synthesized to reveal the effect of the steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent on adsorption capacity and adsorption rate of p-nitroaniline (PNA) from aqueous solution. The results of adsorption kinetics indicated the order of the adsorption rate GQ-05 > GQ-03. The pseudo-first-order rate equation could describe the entire adsorption process of PNA onto GQ-05 while the equation characterized the adsorption process of GQ-03 in two stages. The order of the adsorption capacity GQ-05 > GQ-03 was demonstrated by thermodynamic analysis and dynamic adsorption. The steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent was a crucial factor for the order of the adsorption capacity and adsorption rate

  9. Effects of the steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent on the adsorption of p-nitroaniline in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Guqing, E-mail: xiaoguqing2005@163.com; Wen, Ruimin; Wei, Dongmei; Wu, Dan

    2014-09-15

    Graphical abstract: The hyper-cross-linked polymeric adsorbents (GQ-05 and GQ-03) with different steric hindrance of micropores were designed. The adsorption capacity and adsorption rate of PNA onto the two adsorbents followed the order GQ-05 > GQ-03. The steric hindrance of micropores was a crucial factor for the adsorption capacity and adsorption rate order. - Highlights: • Two adsorbents with different steric hindrance of micropores were designed. • The adsorption capacity and adsorption rate followed the order GQ-05 > GQ-03. • The steric hindrance of micropores was a crucial factor for the order. - Abstract: A hyper-cross-linked polymeric adsorbent with “-CH{sub 2}-phenol-CH{sub 2}-” as the cross-linked bridge (denoted GQ-05), and another hyper-cross-linked polymeric adsorbent with “-CH{sub 2}-p-cresol-CH{sub 2}-” as the cross-linked bridge (denoted GQ-03) were synthesized to reveal the effect of the steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent on adsorption capacity and adsorption rate of p-nitroaniline (PNA) from aqueous solution. The results of adsorption kinetics indicated the order of the adsorption rate GQ-05 > GQ-03. The pseudo-first-order rate equation could describe the entire adsorption process of PNA onto GQ-05 while the equation characterized the adsorption process of GQ-03 in two stages. The order of the adsorption capacity GQ-05 > GQ-03 was demonstrated by thermodynamic analysis and dynamic adsorption. The steric hindrance of micropores in the hyper-cross-linked polymeric adsorbent was a crucial factor for the order of the adsorption capacity and adsorption rate.

  10. The effect of electrochemical phenomena on the deposition of carbon containing inorganic thin films from supersonic expansion of aqueous supercritical solutions

    Science.gov (United States)

    Sezer, Ali Osman

    The supersonic expansion of dilute aqueous solutions for the synthesis of new materials is a complex flow system. Flow prediction and modeling are, therefore, quite challenging. Electrokinetic streaming potentials generated during the supersonic nozzle expansion further complicate the nature of these flow processes. Flow-generated potentials are believed to significantly affect the electrochemical environment of the flow, and therefore, may influence the properties of the product. This dissertation research was an attempt to experimentally and theoretically investigate the significance of flow-generated electrochemical phenomena and their possible effect on the deposited thin carbon films. Brand's computer model was used to predict the physical properties of the expanding jet at the nozzle. The sensitivity of the predicted flow parameters to operating conditions was then analyzed. The results of this parametric flow modeling were used to identify deposition regions of flow space that have less sensitivity to fluctuations in process temperatures and pressures. Streaming currents were predicted from measured nozzle currents. The first high-temperature-pressure Pourbaix diagrams were constructed for the carbon-water system. Equilibrium Pourbaix diagrams together with predicted streaming currents suggested a possible CVD-like mechanism for the deposition of thin carbon films. Deposited carbon films were analyzed for morphology, composition and structure by vibrational spectroscopy and electron microscopy. IR and Raman analysis of carbon samples were not conclusive in revealing any measurable differences in samples. Although Raman spectra showed considerable shifts in peak positions, the lack of internal standard in the spectra made it difficult to draw any reliable conclusions. Significant variations in surface morphology were found for samples grown under different substrate bias. Electron diffraction analysis conclusively showed the presence of a cubic diamond and

  11. Phytoremediation of Heavy Metals in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Felix Aibuedefe AISIEN

    2010-12-01

    Full Text Available One of the major environmental problems is the pollution of water and soil by toxic heavy metals. This study investigated the phytoremediation potential of water hyacinth, for the removal of cadmium (Cd, lead (Pb and zinc (Zn. Water hyacinths were cultured in bore-hole water, supplemented with 5mg/l of Zn and Pb and 1mg/l of Cd at pH 4.5, 6.8 and 8.5. The plants were separately harvested each week for six weeks. The results showed that removal of these metals from solution was fast especially in the first two weeks, after which it became gradual till saturation point was reached. The accumulation of Cd and Zn in leaves and roots increased with increase in pH. The highest accumulation was in the roots with metal concentration of 4870mg/kg, 4150mg/kg and 710mg/kg for Zn, Pb and Cd respectively at pH 8.5. The maximum values of bioconcentration factor (BCF for Zn, Pb and Cd were 1674, 1531 and 1479 respectively, suggesting that water hyacinth was good accumulator of Zn, Pb and Cd, and could be used to treat industrial wastewater contaminated with heavy metals such as Zn, Pb and Cd.

  12. Block copolymer membranes for aqueous solution applications

    KAUST Repository

    Nunes, Suzana Pereira

    2016-03-22

    Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.

  13. Critical droplet theory explains the glass formability of aqueous solutions.

    Science.gov (United States)

    Warkentin, Matthew; Sethna, James P; Thorne, Robert E

    2013-01-01

    When pure water is cooled at ~10(6) K / s, it forms an amorphous solid (glass) instead of the more familiar crystalline phase. The presence of solutes can reduce this required (or "critical") cooling rate by orders of magnitude. Here, we present critical cooling rates for a variety of solutes as a function of concentration and a theoretical framework for understanding these rates. For all solutes tested, the critical cooling rate is an exponential function of concentration. The exponential's characteristic concentration for each solute correlates with the solute's Stokes radius. A modification of critical droplet theory relates the characteristic concentration to the solute radius and the critical nucleation radius of ice in pure water. This simple theory of ice nucleation and glass formability in aqueous solutions has consequences for general glass-forming systems, and in cryobiology, cloud physics, and climate modeling. PMID:23383808

  14. Adsorption of cesium on cement mortar from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Volchek, Konstantin, E-mail: konstantin.volchek@ec.gc.ca [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Miah, Muhammed Yusuf [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Department of Applied Chemistry and Chemical Technology, Noakhali Science and Technology University (Bangladesh); Kuang, Wenxing; DeMaleki, Zack [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Tezel, F. Handan [Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis-Pasteur, Ottawa, Ontario, Canada K1N 6N5 (Canada)

    2011-10-30

    Highlights: {yields} The adsorption of cesium on cement mortar was investigated in a range of temperatures and cesium concentrations. {yields} The pseudo-second order kinetic model produced a good fit with the experimental kinetic data. {yields} Equilibrium test results correlated well with the Freundlich isotherm adsorption model. {yields} The interaction between cesium ions and cement mortar was dominated by chemical adsorption. - Abstract: The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L{sup -1} and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive {sup 137}Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L{sup -1} while the respective surface concentration on coupons varied from 0.0395 to 22.34 {mu}g cm{sup -2}. Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol{sup -1} suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar.

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

    Science.gov (United States)

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

    2002-07-01

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

  16. Photocatalytic decomposition of cortisone acetate in aqueous solution.

    Science.gov (United States)

    Romão, Joana Sobral; Hamdy, Mohamed S; Mul, Guido; Baltrusaitis, Jonas

    2015-01-23

    The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L(-1)min(-1) at 10 mg L(-1) concentration, using the following heterogeneous photocatalysts in decreasing order of their catalytic activity: ZnO>Evonik TiO2 P25>Hombikat TiO2>WO3. Due to the lack of ZnO stability in aqueous solutions, TiO2 P25 was chosen for further experiments. The decomposition reaction was found to be pseudo-first order and the rate constant decreased as a function of increasing initial CA concentration. Changing the initial pH of the CA solution did not affect the reaction rate significantly. The decomposition reaction in the presence of the oxidizing sacrificial agent sodium persulfate showed an observed decomposition rate constant of 0.004 min(-1), lower than that obtained for TiO2 P25 (0.040 min(-1)). The highest photocatalytic degradation rate constant was obtained combining both TiO2 P25 and S2O8(2-) (0.071 min(-1)) showing a synergistic effect. No reactive intermediates were detected using LC-MS showing fast photocatalytic decomposition kinetics of CA. PMID:24953705

  17. Removal of Nitrate From Aqueous Solution Using Rice Chaff

    Directory of Open Access Journals (Sweden)

    Dehghani

    2015-09-01

    Full Text Available Background Nitrate is largely dissolved in the surface and ground water, due to its high solubility. Continual uptake of nitrite through drinking water can lead to problems and diseases (such as blue baby for humans, especially children. Objectives The aim of this study was to develop a new and inexpensive method for the removal of nitrate from water. In this regard, the possibility of using chaff for removal of nitrate from aqueous solutions was studied and the optimum operating conditions of nitrate removal was determined. Materials and Methods This is a cross-sectional study conducted in laboratory scale. The UV spectrophotometer at a wavelength of maximum absorbance (220 nm was used to determine the nitrate concentration. The effect of pH, amount of chaff, temperature, and contact time were investigated. Results The result of this study revealed that chaff as an absorbent could remove nitrate from solutions, and the efficiency of adsorption increased as contact time increased from 5 to 30 minutes, amount of chaff increased from 1 to 3 g, temperature increased in a range of 300 - 400°C and the amount of pH decreased from 10 to 3. The maximum adsorption rate was around pH 3 (53.14%. Conclusions It was shown that the removal efficiency of nitrate was directly proportional to the amount of chaff, temperature, and contact time but inversely to the pH. This study showed that nitrate removal by chaff is a promising technique.

  18. Degradation of 2-mercaptobenzothiazole in aqueous solution by gamma irradiation

    Science.gov (United States)

    Bao, Qiburi; Chen, Lujun; Tian, Jinping; Wang, Jianlong

    2014-10-01

    Industrial wastewaters containing 2-mercaptobenzothiazole (MBT), a widely used chemical additive, usually cannot be treated properly by conventional biological methods, thus cause an environmental risk. Ionizing radiation was proposed as a method for abatement of several refractory pollutants from water. The paper investigated MBT degradation using irradiation technology. The decomposition kinetics was described, and the transformation and the change of biodegradability were discussed. The results of gamma radiation experiments on MBT-containing aqueous solutions indicated that reactive radicals resulting from water radiolysis effectively degrade MBT and improve the biodegradability of the solutions. At a 20 mg/L MBT concentration, the removal of 82% was achieved at the absorbed dose of 1.2 kGy. The results of specific oxygen uptake rate (SOUR) test showed that MBT was decomposed into biodegradable products, after irradiation at 20 kGy. Radicals attacked the sulfur atoms of the studied molecule leading to the release of sulfate ions, but the mineralization of organic carbons was rather weak. Initial concentration significantly affected the degradation efficacy of MBT by gamma radiation.

  19. Electrodeposition of metals from non-aqueous solutions

    International Nuclear Information System (INIS)

    Electrodeposition of metals from non-aqueous solutions is reviewed. Attention is paid mainly to surface morphology of deposits and their adhesion. The major reasons for carrying out electrodeposition in non-aqueous electrolytes (such as conventional organic solvents, ionic liquids and molten salts) are the water and air stability and the wide electrochemical window of these media. The following metals have been electrodeposited and investigated for the last 15 years: aluminum, zinc, silver, palladium, tantalum, zirconium, gadolinium, plutonium, nickel, cobalt, and other alloys.

  20. Raman spectra of amino acids and their aqueous solutions

    Science.gov (United States)

    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.

  1. Solid-like mechanical behaviors of ovalbumin aqueous solutions.

    Science.gov (United States)

    Ikeda, S; Nishinari, K

    2001-04-12

    Flow and dynamic mechanical properties of ovalbumin (OVA) aqueous solutions were investigated. OVA solutions exhibited relatively large zero-shear viscosity values under steady shear flow and solid-like mechanical responses against oscillating small shear strains, that is, the storage modulus was always larger than the loss modulus in the examined frequency range (0.1--100 rad s(-1)). These results suggest that dispersed OVA molecules arranged into a colloidal crystal like array stabilized by large interparticle repulsive forces. However, marked solid-like mechanical behaviors were detected even when electrostatic repulsive forces among protein molecules were virtually absent, which could not be explained solely on the basis of conventional Derjaguin--Landau--Verwey--Overbeek (DLVO) theory. Large non-DLVO repulsive forces seem to stabilize native OVA aqueous solutions.

  2. Succinic acid in aqueous solution : connecting microscopic surface composition and macroscopic surface tension

    OpenAIRE

    Werner, Josephina; Julin, Jan; Dalirian, Maryam; Prisle, Nønne; Öhrwall, Gunnar; Persson, Ingmar; Björneholm, Olle; Riipinen, Ilona

    2014-01-01

    The water vapor interface of aqueous solutions of succinic acid, where pH values and bulk concentrations were varied, has been studied using surface sensitive X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations. It was found that succinic acid has a considerably higher propensity to reside in the aqueous surface region than its deprotonated form, which is effectively depleted from the surface due to the two strongly hydrated carboxylate groups. From both XPS experim...

  3. Micellization properties of cationic gemini surfactants in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Łudzik, K., E-mail: kasialudzik@tlen.pl [Department of Physical Chemistry, University of Łódź, Pomorska 165, 90-236 Łódź (Poland); Piekarski, H.; Kubalczyk, K.; Wasiak, M. [Department of Physical Chemistry, University of Łódź, Pomorska 165, 90-236 Łódź (Poland)

    2013-04-20

    Highlights: ► We measured the d and c{sub p} of for the aqueous solutions of 8-6-8 and 8-12-8 surfactants. ► We analyzed the α{sub T} = f (m), V{sub ϕ} = f (m), c{sub p} = f (m) and C{sub p,ϕ} = f (m). ► The inflection point in the curves of the C{sub p,ϕ} = f (m) corresponds to the c.m.c. ► We analyzed thermodynamics parameters of the micellization for the surfactants. - Abstract: The main goal of this work was to investigate the self-assembly process for water solutions of two gemini surfactants, which differ in spacer chain length, at wide range of temperatures. For this reason the aqueous solutions of hexylene-1,6-bis(dimethyl-octylammonium bromide) and dodecylene-1,12-bis(dimethyloctylammonium bromide) have been examined by the calorimetric (DSC) and densimetric methods within the 293–323 K and 288–323 K temperature range, respectively. The analysis of c{sub p} values obtained for the examined systems allowed to propose an alternative way to estimate the region where micellization process can occur. The observed temperature dependence of the c.m.c. for surfactants investigated shows a typical shape for ionic gemini surfactants. This behavior was explained as a resultant of two competing effect: decrease in the hydrophilic properties of the surfactant molecule and decrease in the hydrophobic hydration of the alkyl chain along with the temperature increase. The enthalpy of micellization ΔH{sub mic} and other thermodynamics parameters associated with the micellization process: ΔG{sub mic}, ΔS{sub mic} and ΔC{sub p} {sub mic} were calculated on the base of the pseudo-phase separation model. As expected, more exothermic enthalpies of micellization are observed with increasing temperature for both the surfactants investigated in this work.

  4. Ion aggregation in high salt solutions. III. Computational vibrational spectroscopy of HDO in aqueous salt solutions

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jun-Ho; Lim, Sohee; Chon, Bonghwan; Cho, Minhaeng, E-mail: mcho@korea.ac.kr [Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 136-713 (Korea, Republic of); Department of Chemistry, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Heejae; Kim, Seongheun [Department of Chemistry, Korea University, Seoul 136-713 (Korea, Republic of)

    2015-05-28

    The vibrational frequency, frequency fluctuation dynamics, and transition dipole moment of the O—D stretch mode of HDO molecule in aqueous solutions are strongly dependent on its local electrostatic environment and hydrogen-bond network structure. Therefore, the time-resolved vibrational spectroscopy the O—D stretch mode has been particularly used to investigate specific ion effects on water structure. Despite prolonged efforts to understand the interplay of O—D vibrational dynamics with local water hydrogen-bond network and ion aggregate structures in high salt solutions, still there exists a gap between theory and experiment due to a lack of quantitative model for accurately describing O—D stretch frequency in high salt solutions. To fill this gap, we have performed numerical simulations of Raman scattering and IR absorption spectra of the O—D stretch mode of HDO in highly concentrated NaCl and KSCN solutions and compared them with experimental results. Carrying out extensive quantum chemistry calculations on not only water clusters but also ion-water clusters, we first developed a distributed vibrational solvatochromic charge model for the O—D stretch mode in aqueous salt solutions. Furthermore, the non-Condon effect on the vibrational transition dipole moment of the O—D stretch mode was fully taken into consideration with the charge response kernel that is non-local polarizability density. From the fluctuating O—D stretch mode frequencies and transition dipole vectors obtained from the molecular dynamics simulations, the O—D stretch Raman scattering and IR absorption spectra of HDO in salt solutions could be calculated. The polarization effect on the transition dipole vector of the O—D stretch mode is shown to be important and the asymmetric line shapes of the O—D stretch Raman scattering and IR absorption spectra of HDO especially in highly concentrated NaCl and KSCN solutions are in quantitative agreement with experimental results. We

  5. Ion aggregation in high salt solutions. III. Computational vibrational spectroscopy of HDO in aqueous salt solutions.

    Science.gov (United States)

    Choi, Jun-Ho; Kim, Heejae; Kim, Seongheun; Lim, Sohee; Chon, Bonghwan; Cho, Minhaeng

    2015-05-28

    The vibrational frequency, frequency fluctuation dynamics, and transition dipole moment of the O-D stretch mode of HDO molecule in aqueous solutions are strongly dependent on its local electrostatic environment and hydrogen-bond network structure. Therefore, the time-resolved vibrational spectroscopy the O-D stretch mode has been particularly used to investigate specific ion effects on water structure. Despite prolonged efforts to understand the interplay of O-D vibrational dynamics with local water hydrogen-bond network and ion aggregate structures in high salt solutions, still there exists a gap between theory and experiment due to a lack of quantitative model for accurately describing O-D stretch frequency in high salt solutions. To fill this gap, we have performed numerical simulations of Raman scattering and IR absorption spectra of the O-D stretch mode of HDO in highly concentrated NaCl and KSCN solutions and compared them with experimental results. Carrying out extensive quantum chemistry calculations on not only water clusters but also ion-water clusters, we first developed a distributed vibrational solvatochromic charge model for the O-D stretch mode in aqueous salt solutions. Furthermore, the non-Condon effect on the vibrational transition dipole moment of the O-D stretch mode was fully taken into consideration with the charge response kernel that is non-local polarizability density. From the fluctuating O-D stretch mode frequencies and transition dipole vectors obtained from the molecular dynamics simulations, the O-D stretch Raman scattering and IR absorption spectra of HDO in salt solutions could be calculated. The polarization effect on the transition dipole vector of the O-D stretch mode is shown to be important and the asymmetric line shapes of the O-D stretch Raman scattering and IR absorption spectra of HDO especially in highly concentrated NaCl and KSCN solutions are in quantitative agreement with experimental results. We anticipate that this

  6. Interaction of gypsum with lead in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Astilleros, J.M., E-mail: jmastill@geo.ucm.es [Dpto. Cristalografia y Mineralogia, Universidad Complutense de Madrid, Jose Antonio Novais, 2, E-28040 Madrid (Spain); Godelitsas, A. [Department of Mineralogy and Petrology, Faculty of Geology and Geoenvironment, University of Athens, Panepistimioupoli Zographou, 15784 Athens (Greece); Rodriguez-Blanco, J.D. [School of Earth and Environments, Faculty of Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Fernandez-Diaz, L. [Dpto. Cristalografia y Mineralogia, Universidad Complutense de Madrid, Jose Antonio Novais, 2, E-28040 Madrid (Spain); Prieto, M. [Dpto. de Geologia, Universidad de Oviedo, E-30005 Oviedo (Spain); Lagoyannis, A.; Harissopulos, S. [Tandem Accelerator Laboratory, Institute of Nuclear Physics, NCSR ' Demokritos' , GR-15310 Attiki (Greece)

    2010-07-15

    Sorption processes on mineral surfaces are a critical factor in controlling the distribution and accumulation of potentially harmful metals in the environment. This work investigates the effectiveness of gypsum (CaSO{sub 4}.2H{sub 2}O) to sequester Pb. The interaction of gypsum fragments with Pb-bearing solutions (10, 100 and 1000 mg/L) was monitored by performing macroscopic batch-type experiments conducted at room temperature. The aqueous phase composition was periodically determined by Atomic Absorption Spectrometry (AAS), Ion Chromatography (IC) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Regardless of the [Pb{sub aq}]{sub initial}, a [Pb{sub aq}]{sub final} < 4 mg/L was always reached. The uptake process was fast (t < 1 h) for [Pb{sub aq}]{sub initial} {>=} 100 mg/L and significantly slower (t > 1 week) for [Pb{sub aq}]{sub initial} = 10 mg/L. Speciation calculations revealed that after a long time of interaction (1 month), all the solutions reached equilibrium with respect to both gypsum and anglesite. For [Pb{sub aq}]{sub initial} {>=} 100 mg/L, sorption takes place mainly via the rapid dissolution of gypsum and the simultaneous formation of anglesite both on the gypsum surface and in the bulk solution. In the case of [Pb{sub aq}]{sub initial} = 10 mg/L, no anglesite precipitation was observed, but surface spectroscopy (proton Rutherford Backscattering Spectroscopy, p-RBS) confirmed the formation of Pb-bearing surface layers on the (0 1 0) gypsum surface in this case also. This study shows that the surface of gypsum can play an important role in the attenuation of Pb in contaminated waters.

  7. Biosorption of carbaryl from aqueous solution onto Pistia stratiotes biomass

    Science.gov (United States)

    Chattoraj, Soumya; Mondal, Naba Kumar; Das, Biswajit; Roy, Palas; Sadhukhan, Bikash

    2014-03-01

    In this work, adsorption of carbaryl from aqueous solution on Pistia stratiotes biomass was investigated. The effects of operating parameters such as initial concentration, pH, adsorbent dose and contact time on the adsorption of carbaryl were analyzed using response surface methodology. The proposed quadratic model for central composite design fitted very well to the experimental data that it could be used to navigate the design space according to analysis of variance results. Response surface plots were used to determine the interaction effects of main factors and optimum conditions of the process. The optimum adsorption conditions were found to be initial carbaryl concentration = 15.57 mg L-1, pH 2.01, adsorbent dose = 0.72 g and contact time = 30 min. The Langmuir, Freundlich and Temkin isotherm models were applied to the equilibrium data. The maximum biosorption capacity of P. stratiotes biomass for carbaryl was found to be 3.1 mg g-1. The pseudo-second-order kinetic model described the carbaryl biosorption process with a good fitting.

  8. Adsorption removal of thiocyanate from aqueous solution by calcined hydrotalcite

    Institute of Scientific and Technical Information of China (English)

    LI Yu-jiang; YANG Min; ZHANG Xiao-jin; WU Tao; CAO Nan; WEI Na; BI Yan-jun; WANG Jing

    2006-01-01

    A hydrotalcite with Mg/Al molar ratio 2 was prepared by co-precipitation method and was characterized by XRD,TG/DTA, Zeta potential and BET surface area. The hydrotalcite was calcined at 500℃, with the dehydration from interlayer, the dehydroxilation from the brucite-like layer and the decomposition of carbonate successively, transformed into the mixed oxide type.The removal of thiocyanate from aqueous solution by using the original hydrotalcite and calcined hydrotalcite (HTC-500) was investigated. The results showed that the thiocyanate adsorption capacity of calcined hydrotalcite was much higher than that of the original form. Calcined hydrotalcite was particularly effective at removing thiocyanate, and that the effective range of pH for the thiocyanate removal are between 5.5-10.0. The experimental data of thiocyanate removal fit nicely with Langmuir isotherm, and the saturated adsorption uptake was 96.2 mg SCN-/g HTC-500. The adsorption ofthiocyanate by calcined hydrotalcite follows first-order kinetics. And the intercalation to the structure recovery for calcined hydrotalcite. But the presence of additional anions could affect the adsorption behavior of thiocyanate.

  9. Photodegradation of Norfloxacin in aqueous solution containing algae

    Institute of Scientific and Technical Information of China (English)

    Junwei Zhang; Dafang Fu; Jilong Wu

    2012-01-01

    Photodegradation of Norfloxacin in aqueous solution containing algae under a medium pressure mercury lamp (15 W,λmax =365 nm) was investigated.Results indicated that the photodegradation of Norfloxacin could be induced by the algae in the heterogeneous algaewater systems.The photodegradation rate of Norfloxacin increased with increasing algae concentration,and was greatly influenced by the temperature and pH of solution.Meanwhile,the cooperation action of algae and Fe(Ⅲ),and the ultrasound were beneficial to photodegradation of Norfloxaciu.The degradation kinetics of Norfloxacin was found to follow the pseudo zero-order reaction in the suspension of algae.In addition,we discussed the photodegradation mechanism of Norfloxacin in the suspension of algae.This work will be helpful for understanding the photochemical degradation of antibiotics in aqueous environment in the presence of algae,for providing a new method to deal with antibiotics pollution.

  10. Diketopiperazine-mediated peptide formation in aqueous solution

    Science.gov (United States)

    Nagayama, M.; Takaoka, O.; Inomata, K.; Yamagata, Y.

    1990-05-01

    Though diketopiperazines (DKP) are formed in most experiments concerning the prebiotic peptide formation, the molecules have not been paid attention in the studies of chemical evolution. We have found that triglycine, tetraglycine or pentaglycine are formed in aqueous solution of glycine anhydride (DKP) and glycine, diglycine or triglycine, respectively. A reaction of alanine with DKP resulted in the formation of glycylglycylalanine under the same conditions. These results indicate that the formation of the peptide bonds proceeds through the nucleophilic attack of an amino group of the amino acids or the oligoglycines on the DKP accompanied by the ring-opening. The formation of glycine anhydride, di-, tri- and tetraglycine was also observed in a mixed aqueous solution of urea and glycine in an open system to allow the evaporation of ammonia. A probable pathway is proposed for prebiotic peptide formation through diketopiperazine on the primitive Earth.

  11. Performance of multiwall carbon nanotubes for removal phenol from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Mohamad Hadi Dehghani

    2013-05-01

    Conclusion: It is concluded that carbon nanotubes being effective in a wide range of pH, short time to reach equilibrium and the absence of competing ions on the absorption process can be used effectively in removing phenol from aqueous solution.

  12. Experimental observation of the ion-ion correlation effects on charge inversion and strong adhesion between mica surfaces in aqueous electrolyte solutions.

    Science.gov (United States)

    Tan, Qiyan; Zhao, Gutian; Qiu, Yinghua; Kan, Yajing; Ni, Zhonghua; Chen, Yunfei

    2014-09-16

    Direct force measurements between two mica surfaces in aqueous electrolyte solutions over broad ranges of LaCl3 concentrations and pH values were carried out with a surface forces apparatus. Charge inversion on mica surfaces is detected once the LaCl3 concentration reaches a critical value. With the continual increase of LaCl3 concentrations, the mica surface will be overscreened by the counterions. It is demonstrated that the two mica surfaces may experience the jump-in contact even at high LaCl3 concentrations, which is seldom seen in monovalent salt solutions. The strong adhesion cannot be attributed to the van der Waals force alone, but should include the ion-ion correlation forces. Through adjusting the pH values in LaCl3 solutions, the ion-ion correlation force can be evaluated quantitatively. These results provide important insight into the fundamental understanding in the role of ion-ion correlations in ion screening mechanism and interactions between charged objects.

  13. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  14. Angular correlation of annihilation photons in frozen aqueous solutions

    DEFF Research Database (Denmark)

    Milosevic-Kvajic, M.; Mogensen, O. E.; Kvajic, G.;

    1972-01-01

    Linear‐slit angular correlation curves were obtained at about −140°C for frozen aqueous solutions of HF, HCl, HBr, HI, NH3, FeCl2, FeCl3, NaI, H2SO4, NHO3, MnSO4, KMnO4, K2Cr2O7, NaOH, and LiOH. We found no appreciable influence of a 4% concentration of the last seven impurities. Only halide...

  15. Determination of concentration of saturated ferrocene in aqueous solution

    OpenAIRE

    Aoki, Koichi

    2013-01-01

    Chun Ouyang, Koichi Jeremiah Aoki, Jingyuan Chen, Toyohiko Nishiumi, Bo Wang Department of Applied Physics, University of Fukui, Bunkyo, Fukui, Japan Abstract: The solubility of ferrocene in aqueous solution is known to be approximately 0.04 mmol/dm3. The solubility values determined by voltammetry have been overestimated because of adsorption on electrodes. This work deals with discerning diffusion from adsorption by altering not only the voltammetric time scale but also the solvents used. ...

  16. EXAFS studies of actinide ions in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Karim, D P; Georgopoulos, P; Knapp, G S

    1979-01-01

    The applicability of the EXAFS technique in the study of actinide systems is discussed. Uranium L/sub III/-edge spectra obtained on an in-lab rotating anode EXAFS facility are presented and analyzed for crystalline UO/sub 2/F/sub 2/ and aqueous solutions containing hexavalent uranium ions. Methods for the extension of the technique to more dilute systems are discussed.

  17. Pulse radiolysis of aqueous lignin solutions with acryl monomers

    International Nuclear Information System (INIS)

    Radiation-induced polymerization in aqueous solutions of methylmethacrylate and methylacrylate with and without lignin added was studied by pulse radiolysis method. Optical spectra of intermediates taking part in the chain evolution were obtained. The rate constant of the chain polymerization termination diminished when lignin added from 1.2 x 109 up to 2 x 108 mol-1 s-1. A reaction scheme of radiation-induced polymerization was proposed which included the lignin entering in chain propagation reactions. (author)

  18. Pulse Radiolysis of Adrenaline in Acid Aqueous Solutions

    DEFF Research Database (Denmark)

    Gohn, M.; Getoff, N.; Bjergbakke, Erling

    1976-01-01

    Pulse radiolysis of adrenaline in acid aqueous solutions (pH 1–3) was carried out. The rate constants for the reactions of adrenaline with H and OH were determined: k(H + adr.) = (0·9±0·1) × 109 dm3 mol−1s−1; k(OH + adr.) = (1·65±0·15) × 1010 dm3 mol−1s−1. The H-adduct of adrenaline has two λmax...

  19. Fluorescence of lanthanide(III) complexes in aqueous solutions

    International Nuclear Information System (INIS)

    The fluorescence of lanthanide ions and of their complexes with EDTA, NTA and AA in aqueous solutions was investigated. It has been shown that the fluorescence band intensities of Sm(III), Eu(III), Gd(III), Tb(III) and Dy(III) complexes depend on the pH and the complexing agent concentration. Fluorescence measurements were used to characterise the lanthanide complexes formed and an attempt was made to interpret the results theoretically. (Author)

  20. Effects of ferrous iron on the precipitation and growth of CaCO3 in slightly basic aqueous solutions, from macro to nanoscale

    Science.gov (United States)

    Di Lorenzo, Fulvio; Burgos-Cara, Alejandro; Ruiz-Agudo, Encarnación; Putnis, Christine V.; Prieto, Manuel

    2016-04-01

    The precipitation of CaCO3 and further growth of calcite has been studied in aqueous solutions containing ferrous iron (Fe2+). Two different types of bulk experiments have been carried out. Nucleation experiments have been conducted at pH 9 with five different CaTOT/FeTOT ratios: 10, 5, 2.5, 1.25 and 0.625. As well, calcite growth experiments have been conducted at pH 8.5 (following the constant composition method) with CaTOT/FeTOT ratios: 100, 50 and 25; this higher dilution partially reduces the impact of inhibition on growth of calcite occurring when CaTOT/FeTOT ≤ 25. Parameters such as the solution pH, [Ca2+], conductivity, solution transmittance (610 nm), and volume added were continuously monitored by a Titrino 905 system (Metrohm, Switzerland). After the experiments, the CaCO3 precipitates were collected, filtered, dried and characterized by powder-XRD, HRTEM, FESEM-EDX, EMPA. Solution composition was determined by ICP-MS. Additionally, in-situ Atomic Force Microscopy (AFM) flow-through growth experiments were conducted in a sealed fluid cell using freshly cleaved natural calcite (Iceland spar). The solution composition in AFM experiments was analogous to the bulk growth experiments. The results of these experiments reveal the significant influence of ferrous iron on nucleation and growth in the CaCO3-H2O system, reflected as well in polymorphic selection in this system.Finally, thermodynamic considerations for the system Ca-Fe-CO2-H2O are discussed that allow the modelling of geochemical processes involving this system, such as geological carbon storage in basaltic rocks.

  1. Catalytic oxidation of calcium sulfite in solution/aqueous slurry

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-qin; WU Zhong-biao; WANG Da-hui

    2004-01-01

    Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfurization(FGD) residue. Experiments were conducted in a semi-batch system and a continuous flow system on lab scales. The main reactor in semi-batch system is a 1000 ml volume flask. It has five necks for continuous feeding of gas and a batch of calcium sulfite solution/aqueous slurry. In continuous flow system, the main part is a jacketed Pyrex glass reactor in which gas and solution/aqueous slurry are fed continuously. Calcium sulfite oxidation is a series of complex free-radical reactions. According to experimental results and literature data, the reactions are influenced significantly by manganese as catalyst. At low concentration of manganese and calcium sulfite, the reaction rate is dependent on 1.5 order of sulfite concentration, 0.5 order of manganese concentration, and zero order of oxygen concentration in which the oxidation is controlled by chemical kinetics. With concentrations of calcium sulfite and manganese increasing, the reactions are independent gradually on the constituents in solution but are impacted by oxygen concentration. Manganese can accelerate the free-radical reactions, and then enhances the mass transfer of oxygen from gas to liquid. The critical concentration of calcium sulfite is 0.007 mol/L, manganese is 10-4 mol/L, and oxygen is of 0.2-0.4 atm.

  2. Observations on the Solubility of Skeletal Carbonates in Aqueous Solutions.

    Science.gov (United States)

    Chave, K E; Deffeyes, K S; Weyl, P K; Garrels, R M; Thompson, M E

    1962-07-01

    Carbonate skeletal materials of marine organisms exhibit a wide range of solubilities in aqueous solutions. In most cases, the dissolution of the carbonate mineral is irreversible and therefore the material can have no true equilibrium solubility. Relative solubilities have been measured in distilled water and in sea water. The least soluble mineral appears to be calcite with low magnesium content; the most soluble is calcite containing 20 to 30 percent MgCO(3) in solid solution. Aragonite has an intermediate solubility. PMID:17774123

  3. Radiolysis of berberine or palmatine in aqueous solution

    Science.gov (United States)

    Marszalek, Milena; Wolszczak, Marian

    2011-01-01

    The reactions of hydrated electron (eaq-), hydrogen atom (H rad ) (reducing species) and Cl2•-, Br2•-, N,O•H radicals (oxidizing species) with berberine or palmatine in aqueous solution have been studied by steady-state and pulse radiolysis. The spectra of transient intermediates, leading to the final products, are presented. The rate constants of the reaction of eaq- and rad OH radical with both alkaloids in the homogenous solution and in the presence of DNA are reported. It is demonstrated that the primary products of the reaction of berberine and palmatine with eaq- and radicals generated during radiolysis are unstable and undergo further reactions.

  4. Direct photolysis of nitroaromatic compounds in aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    CHEN Bing; YANG Chun; GOH Ngoh Khang

    2005-01-01

    The direct photolysis of nitrobenzene and nitrophenols in aqueous solutions irradiated by polychromatic light were investigated.Several aromatic intermediates were identified as three nitrophenol isomers, nitrohydroquinone, nitrosobenzene, nitrocatechol, catechol and phenol. Nitrite and nitrate ions were also detected in the irradiated solution indicating direct photolysis of nitrobenzene or nitrophenols.The degradation of nitrobenzene and nitrophenols and the formation of three nitrophenol isomers were observed to follow zero-order kinetics. The quantum yields for nitrobenzene and nitrophenols removal are about 10-3 and 10-3-10-4 respectively. The mechanism for nitrobenzene degradation was suggested to follow mainly nitro-nitrite intramolecular arrangement.

  5. Removal of uranyl ions from aqueous solutions using barium titanate

    International Nuclear Information System (INIS)

    Remediation of water sources contaminated with radioactive waste products is a major environmental issue that demands new and more efficient technologies. For this purpose, we report a highly efficient ion-exchange material for the removal of radioactive nuclides from aqueous solutions. The kinetic characteristics of adsorption of uranyl ions on the surface of barium titanate were investigated using a spectrophotometric method under a wide range of conditions. By controlling the pH it was possible to exert fine control over the speciation of uranium, and by optimizing the temperature and grain size of the exchanger, almost total removal was achieved in a matter of just hours. The highest efficiency (>90 % removal) was realized at high temperature (80 deg C). Moreover, the effect of competitive ion adsorption from a range of different cations and anions was quantified. Adsorption was found to follow first-order kinetics and both Freundlich and Langmuir isotherms could be applied to this system. The results of a mathematical treatment of the kinetic data combined with the observation that adsorption was independent of stirring speed and dependent on the ion-exchanger grain size, indicate that the dominant mechanism influencing adsorption is particle spreading. The adsorption behavior was not influenced by exposure to high-intensity gamma radiation, indicating potential for use of this ion-exchanger in systems containing radioactive material. These results will be of use in the development of uranium extraction systems for contaminated water sources. (author)

  6. Sonochemical degradation of organophosphorus pesticide in dilute aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    Robina Farooq; FENG Kai-lin; S. F. Shaukat; HUANG Jian-jun

    2003-01-01

    Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2-12. Process parameters studied include pH, steady-state temperature, concentration, and the type of gases. Greater than 96% hydrolysis was observed in 30 minutes through this process and the rate of destruction increased with the help of more soluble and low thermal inert gas. So with Krypton, omethoate was found to undergo rapid destruction as compared with Argon. In the presence of ultrasound, the observed first-order rate of hydrolysis of omethoate is found to be independent of pH. The formation of transient supercritical water(SCW) appears to be an important factor in the acceleration of chemical reactions in the presence of ultrasound. A detailed chemical reaction mechanism for omethoate destruction in water was formulated. Experimental results and theoretical kinetic mechanism demonstrated that the most of the omethoate undergo destruction inside the cavitating holes. A very less effect of temperature on the degradation of omethoate within a temperature range of 20-70℃ proves that a small quantity of omethoate undergoes secondary destruction in the bulk liquid.

  7. Photo- and thermal degradation of piroxicam in aqueous solution

    Directory of Open Access Journals (Sweden)

    M Aminuddin

    2011-01-01

    Full Text Available Light and temperature have considerable effect on the degradation of piroxicam in aqueous solutions. The pH and acetate buffer ions also affect the degradation process. The apparent first-order rate constants for the photochemical and thermal degradation of piroxicam have been determined as 2.04-10.01 and 0.86-3.06×10−3 min−1 , respectively. The first-order plots for the degradation of piroxicam showed good linearity within a range of 20-50% loss of piroxicam at pH 2.0-12.0. The rate-pH profile for the photodegradation of piroxicam is a U-shaped curve and for the thermal degradation a bell-shaped curve in the pH range of 2.0-12.0. The thermal degradation of piroxicam was maximum around pH 6.0. It is increased in the presence of acetate ions but was not affected by citrate and phosphate ions.

  8. A vibrational spectroscopy study on anserine and its aqueous solutions.

    Science.gov (United States)

    Akkaya, Y; Balci, K; Goren, Y; Akyuz, S; Stricker, M C; Stover, D D; Ritzhaupt, G; Collier, W B

    2015-01-01

    In this study based on vibrational spectroscopic measurements and Density Functional Theory (DFT), we aimed for a reliable interpretation of the IR and Raman spectra recorded for anserine in the solid phase and water (H2O) and heavy water (D2O) solutions. Initial DFT calculations at the B3LYP/6-31G(d) searched possible conformers of the anserine zwitterion using a systematic conformational search. The corresponding equilibrium geometrical parameters and vibrational spectral data were determined for each of the stable conformers (in water) by the geometry optimization and hessian calculations performed at the same level of theory using the polarized continuum model (PCM). The same calculations were repeated to determine the most energetically preferred dimer structure for the molecule and the associated geometry, force field and vibrational spectral data. The harmonic force constants obtained from these calculations were scaled by the Scaled Quantum Mechanical Force Field (SQM) method and then used in the calculation of the refined wavenumbers, potential energy distributions, IR and Raman intensities. These refined theoretical data, which confirm the zwitterion structure for anserine in the solid phase or aqueous solvents, revealed the remarkable effects of intermolecular hydrogen bonding on the structural properties and observed IR and Raman spectra of this molecule. PMID:25997178

  9. Cadmium Removal from Aqueous Solutions by Ground Pine Cone

    Directory of Open Access Journals (Sweden)

    H Izanloo, S Nasseri

    2005-01-01

    Full Text Available A study on the removal of cadmium ions from aqueous solutions by pine cone was conducted in batch conditions. Kinetic data and equilibrium removal isotherms were obtained. The influence of different experimental parameters such as contact time, initial concentration of cadmium, pine cone mass and particle size, and temperature on the kinetics of cadmium removal was studied. Results showed that the main parameters that played an important role in removal phenomenon were initial cadmium concentration, particle size and pine cone mass. The necessary time to reach equilibrium was between 4 and 7 hours based on the initial concentration of cadmium. The capacity of cadmium adsorption at equilibrium increased with the decrease of pine cone particle size. The capacity of cadmium adsorption at equilibrium by pine cone increased with the quantity of pine cone introduced (1–4 g/L. Temperature in the range of 20-30°C showed a restricted effect on the removal kinetics (13.56 mg/g at 20°C and a low capacity of adsorption about 11.48 mg/g at 30°C. The process followed pseudo second-order kinetics. The cadmium uptake of pine cone was quantitatively evaluated using adsorption isotherms. Results indicated that the Langmuir model gave a better fit to the experimental data in comparison with the Freundlich equation.

  10. Biosorption of mercury from aqueous solutions using highly characterised peats

    Directory of Open Access Journals (Sweden)

    A.M. Rizzuti

    2015-02-01

    Full Text Available This research investigated the biosorption of mercury from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after being treated with hydrochloric acid (HCl to free up any occupied exchange sites. Other variables tested were sample dose, contact time, mixing temperature, and the concentration and pH of the mercury solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re-used for mercury biosorption. The results indicate that all six peat types biosorb mercury from aqueous solutions extremely well (92−100 % removal and that their mercury removal capacities are not significantly affected by manipulation of the various factors tested. The factor that had the greatest impact on the mercury removal capacities of the peats was the pH of the mercury solution. The optimal mercury solution pH for mercury removal was in the range 5−7 for four of the peats and in the range 2−3 for the other two. The desorption results indicate that it may be possible to recover up to 41 % of the removed mercury. All of the peat types tested can be repeatedly re-used for additional mercury biosorption cycles. Hence, their disposal should not become a hazardous waste problem.

  11. EFFECT OF TEMPERATURE AND CONCENTRATION ON THE VISCOSITY OF AQUEOUS SOLUTIONS OF 3-AMINOPROPANOIC ACID, 4-AMINOBUTANOIC ACID, 5-AMINOPENTANOIC ACID, 6-AMINOHEXANOIC ACID

    Directory of Open Access Journals (Sweden)

    Carmen María Romero

    2011-12-01

    Full Text Available In this work we present the effect of temperatureon the viscosities of aqueous solutionsof 3-aminopropanoic acid, 4-aminobutanoicacid, 5-aminopentanoic acidand 6-aminohexanoic acid as a functionof concentration. The experimental measurementswere done from 293.15 K to308.15 K. At each temperature the experimentaldata were fi tted to the Tsangaris-Martin equation and the B viscosity coefficient was determined. The dependenceof the B coeffi cients on the number ofcarbon atoms of the amino acids is linear,so the contribution of polar and apolargroups was established. The results areinterpreted in terms of amino acid hydration.

  12. Label-free monitoring of interaction between DNA and oxaliplatin in aqueous solution by terahertz spectroscopy

    Science.gov (United States)

    Wu, Xiaojun; E, Yiwen; Xu, Xinlong; Wang, Li

    2012-07-01

    We demonstrated the feasibility of applying terahertz time-domain spectroscopy (THz-TDS) to monitor the molecular reactions in aqueous solutions of anticancer drug oxaliplatin with λ-DNA and macrophages DNA. The reaction time dependent refractive index and absorption coefficient were extracted and analyzed. The reaction half-decaying time of about 4.0 h for λ-DNA and 12.9 h for M-DNA was established. The results suggest that the THz-TDS detection could be an effective label-free technique to sense the molecular reaction in aqueous solutions and could be very useful in biology, medicine, and pharmacy industry.

  13. Removal of Indigo Carmine Dye from Aqueous Solution Using Magnesium Hydroxide as an Adsorbent

    OpenAIRE

    Thimmasandra Narayan Ramesh; Vani Pavagada Sreenivasa

    2015-01-01

    Magnesium hydroxide is used as an adsorbent for the removal of indigo carmine dye from aqueous solution. We have investigated the effectiveness of removal of indigo carmine dye from aqueous solutions at pH 6-7 and 12-13 using magnesium hydroxide thereby varying the dose of the adsorbent, concentration of the dye, duration, and temperature. Structural transformations of adsorbent during the adsorption process at different pH values are monitored using powder X-ray diffraction and infrared spec...

  14. Effect of total aluminum concentration on the formation and transformation of nanosized Al13 and Al30 in hydrolytic polymeric aluminum aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhaoyang; LIU Changjun; LUAN Zhaokun; ZHANG Zhongguo; LI Yanzhong; JIA Zhiping

    2005-01-01

    Influence of total aluminum concentration (CAlT) on the generation and transformation of nanosized Al13 and Al30 in hydrolytic polyaluminum aqueous solutions was investigated using high field 27Al NMR and time-developed Al-Ferron complex colorimetry. When prepared at the optimal basicity (B) of Al13 generation and 80℃, the Al13 species in polyaluminum solution tends to further polymerize and convert to Al30 and higher polymers when CAlT >0.2 mol·L-1, but Al13 does not convert to Al30 quantificationally, as the formation of Alu from Al13 and Al30 is accelerated in the same way. The conversion rate of Al13 is accelerated by the increase in CAlT. When CAlT >0.75 mol·L-1, Al13 content decreases rapidly, and Al30 content increases continuously and becomes the dominant nanometer polynuclear aluminum species. Alm is one of prerequisites of Al13 conversion to Al30. When CAlT increases and B reduces, the polymerization rate between Al13 and Alm increases, and at the same time, the dissociation reaction rate of Al13 and Al30 by H+ also increases. The latter becomes the dominant reaction in polyaluminum solution with low B value, so Al30 decreases with the increasing CAlT. The hydrolytic polyaluminum solution with Al13 content beyond 80% can only be prepared under the condition of CAlT<0.5 mol·L-1 and optimal B value.

  15. Corrosion behavior of bulk metallic glasses in different aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The corrosion behavior of as-cast fully amorphous, structural relaxed amorphous and crystallized Fe65.5Cr4Mo4Ga4P12C5B5.5 bulk metallic glasses (BMGs) in NaCl, HCl and NaOH solutions was investigated by electrochemical polarization and immersion methods. X-ray photoelectron spectroscopy measurements was used to analyze the changes of the elements on the alloy surface before and after immersion in various solutions. The corrosion resistance of the Fe65.5Cr4Mo4Ga4P12C5B5.5 BMG was better than its structural relaxation/crystallization counterparts and common alloys (such as stainless steel, carbonized steel, and steel) in the selected aqueous solutions. The high corrosion resistance of this alloy in corrosive solutions leads to the formation of Fe-, Cr- and Mo-enriched protective thin surface films.

  16. Heavy metal removal from aqueous solutions by activated phosphate rock

    Energy Technology Data Exchange (ETDEWEB)

    Elouear, Z. [Laboratoire Eau Energie et Environnement, Departement de genie geologique, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038, Sfax (Tunisia)], E-mail: zouheir.elouaer@tunet.tn; Bouzid, J.; Boujelben, N. [Laboratoire Eau Energie et Environnement, Departement de genie geologique, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038, Sfax (Tunisia); Feki, M. [Unite de chimie industriel I, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038 Sfax (Tunisia); Jamoussi, F. [Laboratoire de Georessources CERTE BP 95, 2050 Hamam-Lif (Tunisia); Montiel, A. [Societe Anonyme de Gestion des Eaux de Paris, 9 rue Schoelcher, 75675 Paris cedex 14 (France)

    2008-08-15

    The use of natural adsorbent such as phosphate rock to replace expensive imported synthetic adsorbent is particularly appropriate for developing countries such as Tunisia. In this study, the removal characteristics of lead, cadmium, copper and zinc ions from aqueous solution by activated phosphate rock were investigated under various operating variables like contact time, solution pH, initial metal concentration and temperature. The kinetic and the sorption process of these metal ions were compared for phosphate rock (PR) and activated phosphate rock (APR). To accomplish this objective we have: (a) characterized both (PR) and (APR) using different techniques (XRD, IR) and analyses (EDAX, BET-N{sub 2}); and, (b) qualified and quantified the interaction of Pb{sup 2+}, Cd{sup 2+}, Cu{sup 2+} and Zn{sup 2+} with these sorbents through batch experiments. Initial uptake of these metal ions increases with time up to 1 h for (PR) and 2 h for (APR), after then, it reaches equilibrium. The maximum sorption obtained for (PR) and (APR) is between pH 2 and 3 for Pb{sup 2+} and 4 and 6 for Cd{sup 2+}, Cu{sup 2+} and Zn{sup 2+}. The effect of temperature has been carried out at 10, 20 and 40 deg. C. The data obtained from sorption isotherms of metal ions at different temperatures fit to linear form of Langmuir sorption equation. The heat of sorption ({delta}H{sup o}), free energy ({delta}G{sup o}) and change in entropy ({delta}S{sup o}) were calculated. They show that sorption of Pb{sup 2+}, Cd{sup 2+}, Cu{sup 2+} and Zn{sup 2+}on (PR) and (APR) an endothermic process. These findings are significant for future using of (APR) for the removal of heavy metal ions from wastewater under realistic competitive conditions in terms of initial heavy metals, concentrations and pH.

  17. Depolarization of negative muons in water and aqueous solutions

    International Nuclear Information System (INIS)

    The dependence of negative muon depolarization on temperature and hydrogen peroxide concentration is measured in various aqueous solutions located in longitudinal or transverse magnetic fields. It is shown that the experimental data are mot inconsistent with the familiar concepts regarding the behaviour of free radicals in aqueous solutions. The residual polarization in pure water solution of hydrogen peroxide is found to 1.8 times higher than that in pure water. This is interpreted as being the result of chemical interaction between meso nitrogen and hydrogen peroxide molecules leading to the formation of diamagnetic compounds. It is shown that the degree of depolarization does not depend on the magnetic field strength. According to the depolarization model in which meso nitrogen chemical reactions are taken into account this signifies that the meso atom enters the chemical reactions during a time t≅10-11 sec. at T=300 K; the paramagnetic products of these primary reactions which contain meso nitrogen then participate in secondary reactions during a time t1≤10-7 sec. The rate constants of the reactions leading to the formation of diamagnetic products can be obtained by treating the concentration and temperature dependences of depolarization in an aqueous solution of hydrogen peroxide in accordance with the model assuming chemical reactions between the meso atom and H2O molecules. The order of magnitude of the constant k≅10-11 sec-1⋅sm3is the same as that of the constant for reactions between free H and OH radicals in water. The temperature dependences of depolarization in water and a water solution of hydrogen peroxide are same consistent with the concept that the meso nitrogen reactions are chemical reactions by diffusion. (author)

  18. Synergistic effect of nanocavities in anatase TiO2 nanobelts for photocatalytic degradation of methyl orange dye in aqueous solution.

    Science.gov (United States)

    Praveen Kumar, D; Lakshmana Reddy, N; Karthikeyan, M; Chinnaiah, N; Bramhaiah, V; Durga Kumari, V; Shankar, M V

    2016-09-01

    Nanocavities are empty voids exposed on the surface of one dimensional TiO2 nanostructured material. Often, they exhibited beneficial optical and electrical properties that leads to efficient photocatalytic reactions. This study reports formation of nanocavities on anatase TiO2 nanobelts (TNB) through dehydroxylation of surface hydroxyl groups during calcination process (350-600°C). The morphological and crystal structure analysis of TNB-500, -550 and -600 displayed the nanobelts shape with high density of nano-size cavities and increase in average diameter with calcination temperature. The SAED patterns confirm the anatase TiO2 phase. The enhanced light absorption properties of biphasic anatase/TiO2-B and anatase TiO2 than H2Ti3O7 are attributed to transformation of crystal structure upon calcination process. The catalytic activity was evaluated for degradation of methyl orange dye in aqueous solution under solar light irradiation. The reaction variables such as calcination temperature, amount of catalyst and pH of the methyl orange dye solution were studied and discussed in detail. Under optimal experimental conditions TNB-550 photocatalyst displayed highest degradation performance about 8 folds higher than H2Ti3O7. The high performance is explained as due to synergistic properties of one dimensional anatase TiO2 with high density of nanocavities leading to one dimensional transfer of electrons and high absorption co-efficient in UV-A spectrum are suitable for efficient red-ox reactions. PMID:27289430

  19. Removal of Basic Dyes from Aqueous Solution by Chloroacetic Acid Modified Ferula Communis Based Adsorbent: Thermodynamic and Kinetic Studies

    OpenAIRE

    Salih, Shameran Jamal

    2014-01-01

    ABSTRACT: This research aimed to propose an alternative cheap and abundantly available adsorbent (Ferula communis) for the removal of basic dyes from aqueous solutions. Chloroacetic acid modified Ferula communis (MFC) shows a great potential for the removal of basic red 9 dyes (BR9) from aqueous solution with the effects of solution capacity under pH, temperature, contact time, adsorbent dosage, and initial dye concentration condition on BR9 removal were examined. The adsorption equilibrium d...

  20. Aqueous Solutions on Silica Surfaces: Structure and Dynamics from Simulations

    Science.gov (United States)

    Striolo, Alberto; Argyris, Dimitrios; Tummala, Naga Rajesh

    2009-03-01

    Our group is interested in understanding the properties of aqueous electrolyte solutions at interfaces. The fundamental questions we seek to answer include: (A) how does a solid structure perturb interfacial water? (B) How far from the solid does this perturbation persist? (C) What is the rate of water reorientation and exchange in the perturbed layer? (D) What happens in the presence of simple electrolytes? To address such topics we implemented atomistic molecular dynamics simulations. Recent results for water and simple electrolytes near silicon dioxide surfaces of various degrees of hydroxylation will be presented. The data suggest the formation of a layered aqueous structure near the interface. The density profile of interfacial water seems to dictate the density profiles of aqueous solutions containing NaCl, CaCl2, CsCl, and SrCl2 near the solid surfaces. These results suggest that ion-ion and ion-water correlations are extremely important factors that should be considered when it is desired to predict the distribution of electrolytes near a charged surface. Our results will benefit a number of practical applications including water desalination, exploitation of the oil shale in the Green River Basin, nuclear waste sites remediation, and design of nanofluidic devices.

  1. Reomoval of Heavy Metals from Aqueous Solutions using Bascteria

    Institute of Scientific and Technical Information of China (English)

    HUANGMin-sheng; PANjing; 等

    2001-01-01

    The accumulation of heavy metals by microbial biomass with high surface area-to-volume ratio holds great potential for heavy metal removal in both soluble and particular forms,especially when the heavy metal concentrations are low(<50mg/L),E.coli and B.Subtilis are effective agents for metal removal.We further investigated the effect of pH,temperature,equilibration time,and pre-treatment reagents on the removal of pH(Ⅱ),Cd(Ⅱ) and Cr(VI) from aqueous solutions by E.Coli and B.subtilis.E.coli and B.subtilis were cultivated for 60 hours,the experimentally determined optimal cultivation time before they were used in metal removal experiments,Under the optimal conditions of pH 6.0,equilibration temperature 30℃ and equilibration time 1 hour,63.39% and 69.90%Cd(Ⅱ) can be removed by E.coli and B.subtilis.Under the optimal conditions of pH5.5,equilibration temperature 30℃ and equliobration time 1 hour,68.51% and 67.36% pB(Ⅱ) can be removed by E.coli and B.subtilis.And under the optimal conditons of pH5.5,equilibration temperature 30℃,and equilibration time 1 hour,60.26% and 54.56% Cr(VI) can be removed by E.coli and B.subtilis.Chemical treatment of cultivated bacteria(0.1mol/L NaOH,0.1mol/L HCl,30% ethanol,and distilled water)affects the efficiency of metal removal by E.coli and B.subtilis,pretreatment of biomass by NaOH enhanced Cd(Ⅱ),Pb(Ⅱ)and Cr(VI) removal,while preteatment by HCl,ethanol and distilled water reduced Ca(Ⅱ) ,Pb(Ⅱ) and Cr(VI) removal,For metal removal from industrial waste discharges,pretreated biomass of E.coli can remove 68.5% of Cd and 58.1% of Cr from solutions,while pretreated biomass of B.subtilis can remove 62.6% of Cd and 57% of Cr from Solutions.

  2. RHEOLOGICAL BEHAVIOR OF ERWINIA GUM IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Li-na Zhang; Mei Zhang; Jing-hua Chen; Hideki Iijima; Hiromichi Tsuchiya

    1999-01-01

    Erwinia (E) gum, an extracellular polysaccharide, is composed of fucose, galatose, glucose and glucuronic acid. Its viscosity behavior was investigated by a low-shear-rate multiball viscometer and a rotational viscometer. Its weight-average molecular weight Mw and intrinsic viscosity [η] in 0.2 mol/L NaCl aqueous solution were measured by light scattering method at 35℃ and viscometry at 25℃ and found to be 1.06 × 106 g/mol and 1050 mL/g, respectively, and its aggregates in aqueous solution were proved by gel permeation chromatography (GPC). These results indicated that E gum in water has exceedingly high viscosity and exhibits Binham fluid behavior, owing to its aggregation. The viscosity of E gum decreased with increasing temperature, and the turning point appeared at 38℃ for dilute solution and 80℃ for concentrated solution suggesting that the aggregates of E gum in water started to disaggregate under these temperatures. In addition, the aggregates can be disrupted by adding either acid or base. The experimental results indicated that the E gum is a good thickening agent, and its fluid behavior is similar to xanthan.

  3. An electrochemical treatment for aqueous radioactive solutions using pottery

    International Nuclear Information System (INIS)

    A bench scale electrolytic cell made from plexiglas was used for electrochemical separation of 137Cs and 60Co from simullated aqueous radioactive solutions. In this cell, a stainless steel plate represented the anode. The electrochemical treatment technique used depends on forcing the radioactive cations of the solution (137Cs+ and 60Co++) towards the opposite electrode under the influence of applied electric current, where they highly sorbed in the pottery body. The highest removal for137Cs+ and 60Co was in the alkalina medium, especially at pH>9. The investigated factors affected the electrochemicla processes are, applied voltage, treatment duration, hydrogen ion concentration of the radioactive solution, and the consumed electrical energy . It was found that at pH 11, applied voltage 30V and current 100 mA, the highest removal of 137Cs is 99.8% after 2.5 hours, and 99.3% and 99.3% for 60Co after 1.25 hour.The total consumed energy for 137Cs and 60Co were 33.75 and 16.88 W.h.dm-3, respectively. Comparing with other treatment methods, the electrochemical method revealed three advantages: shorter treatment time, low-cost materials, and low consumed energy. The results obtained showed that the dual application of electric current and sorption on the surface of pottery are feasible for the treatment of aqueous radioactive solutions

  4. Desalination of aqueous solutions by LTA and MFI zeolite membranes using pervaporation method

    Directory of Open Access Journals (Sweden)

    A. Malekpour

    2011-12-01

    Full Text Available LTA and MFI zeolite membranes were hydrothermally grown on the surface of an α-alumina porous support. The synthesized membranes were used for removal of cationic and anionic species from aqueous solutions by the pervaporation method. The perfection of the membranes was improved by employing the multi-stage synthesis method. The membranes were characterized by XRD, SEM and IR methods. The membranes were initially evaluated by the pervaporation separation of water from aqueous 2-propanol mixtures. The separation factors obtained were 7081 and 105 for NaA and ZSM-5 membranes, respectively. The ability of membranes for desalination of some aqueous solutions containing I-, Cs+ and Sr2+ ions was examined in various conditions. These ionic species were chosen because of their importance in the nuclear sciences. Both membranes effectively removed (more than 99 wt% I-, Cs+ and Sr2+ from their singlesalt solutions (0.001mol dm-3 over a temperature range of 298-338 K. The effects of parameters such as time and temperature on the separation factors and fluxes were investigated. This work shows that, due to their excellent chemical, thermal and mechanical stability, the zeolitic membranes are useful for desalination of aqueous solutions and treating saline wastewaters by pervaporation. Therefore, this method has the ability to desalinate harsh environment solutions involving strong solvent and radioactive components.

  5. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  6. Plasmon interactions between gold nanoparticles in aqueous solution with controlled spatial separation

    DEFF Research Database (Denmark)

    Sendroiu, I.E.; Mertens, Stijn; Schiffrin, D.J.

    2006-01-01

    The effects of interparticle distance on the UV-visible absorption spectrum of gold nanocrystals aggregates in aqueous solution have been investigated. The aggregates were produced by ion-templated chelation of omega-mercaptocarboxylic acid ligands covalently attached to the nanoparticles surface...

  7. Influence of Deacetylation on the Rheological Properties of Xanthan-Guar Interactions in Dilute Aqueous Solutions

    Science.gov (United States)

    An oscillating capillary rheometer was used to investigate the effects of xanthan deacetylation on the viscoelastic properties and intrinsic viscosity of xanthan and guar mixtures in dilute aqueous solutions. Deacetylated xanthan exhibited a stronger synergistic interaction with guar than native xan...

  8. Nano particles@Calix arenas via aqueous solution

    Directory of Open Access Journals (Sweden)

    Sahar Dehghani

    2016-05-01

    Full Text Available The electronic structure and magnetic properties of Al2O3, GaN and Fe3O4@ Calix (8 COOH have been studied using ONIOM and DFT methods. The studies focus on how to improve the adsorption of some nano particles solution aqueous for achieving good magnetic and functionalized potential performances. The results revealed that the Fe3O4@ Calix (8 COOH and some of its derivations exhibited better thermodynamic stability. Furthermore, the particle size and magnetic property of the GaN@ Calix (8 COOH nano particles can be controlled by the aqueous. The electrical properties such as NMR Shielding, electron densities, energy densities, potential energy densities, ELF, LOL, ellipticity of electron density, eta index and ECP for nano particles@ Calix (8COOH have been calculated.

  9. Kinetics of ozone-phenol reaction in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, M.G.; Shambaugh, R.L.

    1982-01-01

    The kinetics of the reaction of ozone and phenol in aqueous medium was studied. The reaction was first order with respect to both ozone and phenol. The rate constant was found to increase with increase in the pH of the reaction mixture. Four different catalysts were examined for their effect on the rate of reaction. 30 refs.

  10. Characterization of trehalose aqueous solutions by neutron spin echo

    CERN Document Server

    Branca, C; Magazù, S; Maisano, G; Mangione, A; Pappas, C; Triolo, A

    2002-01-01

    The present work reports neutron spin-echo (NSE) results on aqueous mixtures of trehalose, a naturally occurring disaccharide of glucose, which shows an extraordinary bioprotective effectiveness against dehydration and freezing. The aim of the work is to furnish new results on the dynamics of the trehalose/water system on the nano- and picosecond scales. (orig.)

  11. Transient species produced in irradiated alkaline aqueous solutions containing oxygen

    International Nuclear Information System (INIS)

    The spectra and decay kinetics of the optical absorption in the UV region and at 430nm (maximum of the ozonide ion absorption), were investigated in oxygenated neutral, slightly and strongly alkaline aqueous solutions. It is assumed that the initial absorption after the pulse in oxygenated alkaline solutions is due to the ozonide ion O3-, superoxide radical ion O2- and ozone O3. The long-living absorption in these solutions cannot be excluded as to be probably caused by the ozone O3 or some product formed from O2- or an alkaline stabilized form of this radical-ion. The advantage of applying additional non-optical measurements of the system is shown on the example of H2O2 role played in the mechanism. (author)

  12. Nature of oxygen containing radicals in radiation chemistry and photochemistry of aqueous solutions. Final progress report, July 1982-July 1983

    Energy Technology Data Exchange (ETDEWEB)

    Czapski, G.

    1983-01-01

    This report summarizes the results of research on the physical and chemical properties of ozonide and hydroperoxy radical in aqueous solutions, particularly in biological systems. The effects of the presence of copper and iron on oxygen toxicity were studied. (ACR)

  13. Removal of lead and zinc ions from aqueous solutions using clinoptilolite

    OpenAIRE

    Golomeova, Mirjana; Zendelska, Afrodita; Krstev, Boris; Golomeov, Blagoj; Blažev, Krsto

    2014-01-01

    The removed of lead and zinc ions from synthetic aqueous solutions was performed using clinoptilolite. In order to determine the effectivity of clinoptilolite a series of experiments were performed under batch conditions from single ion solutions. Experiments were carried out at different initial ions concentration, different initial pH values and different adsorbent mass. The adsorption kinetics is reasonably fast. It means that in the first 20 min approximately 90% o...

  14. Homotopy perturbation method for Ozone decomposition of the second order in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Ayati Z.

    2015-05-01

    Full Text Available In this article the problem of mass transfer of ozone of the second order from a gaseous phase into an aqueous phase has been studied. Homotopy perturbation method is employed to derive an analytical approximation to the solutions of the system of differential equations governing on the problem. Some parametric studies have been included. The effects of the temperature and hydroxyl ion reaction order to the solutions are illustrated by some plots

  15. Preparation of fluorescent polyaniline nanoparticles in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Kleber G. B. [Universidade Federal de Pernambuco, Departamento de Engenharia Mecanica (Brazil); Melo, Etelino F. de [Universidade Federal de Pernambuco, Departamento de Quimica Fundamental (Brazil); Andrade, Cesar A. S. [Universidade Federal de Pernambuco, Departamento de Bioquimica (Brazil); Melo, Celso P. de, E-mail: celso@df.ufpe.br [Universidade Federal de Pernambuco, Departamento de Fisica (Brazil)

    2013-01-15

    We report the synthesis of stable polyaniline nanoparticles (PANI{sub N}Ps) based on the chemical oxidative polymerization of aniline in aqueous solutions of surfactants. Surfactants of three different types-cationic (dodecyltrimethylammonium bromide-DTAB), anionic (sodium dodecyl sulfate-SDS), and non-ionic (Triton X-405-TX-405)-were used. The resulting PANI{sub N}Ps{sub s}urfactant samples were characterized through UV-Vis, fluorescence and Fourier transform infrared spectroscopies, and scanning electronic microscopy (SEM). We have verified that the color of the PANI{sub N}Ps{sub s}urfactant dispersions is affected by a change in the pH of the solution. The PANI-NPs{sub s}urfactant colloidal suspensions in aqueous solution present a surprising high fluorescence quantum yield value (ranging from 1.9 Multiplication-Sign 10{sup -3} to 6.9 Multiplication-Sign 10{sup -3}) that can be controlled as a function of the pH, a fact that we associate to the corresponding protonation degree of the PANI polymeric chains. We suggest that these fluorescent nanocomposites can find important technological applications in different areas such as organic light emitting devices, biosensors, and pigments for coatings.

  16. 2, 4 dichlorophenol (2, 4-DCP) sorption from aqueous solution using granular activated carbon and polymeric adsorbents and studies on effect of temperature on activated carbon adsorption.

    Science.gov (United States)

    Ghatbandhe, A S; Yenkie, M K N

    2008-04-01

    Adsorption equilibrium, kinetics and thermodynamics of 2,4-dichlorophenol (2,4-DCP), one of the most commonly used chlorophenol, onto bituminous coal based Filtrasorb-400 grade granular activated carbon, were studied in aqueous solution in a batch system with respect to temperature. Uptake capacity of activated carbon found to increase with temperature. Langmuir isotherm models were applied to experimental equilibrium data of 2, 4-DCP adsorption and competitive studies with respect to XAD resin were carried out. Equilibrium data fitted very well to the Langmuir equilibrium model. Adsorbent monolayer capacity 'Q0, Langmuir constant 'b' and adsorption rate constant 'k(a)' were evaluated at different temperatures for activated carbon adsorption. This data was then used to calculate the energy of activation of adsorption and also the thermodynamic parameters, namely the free energy of adsorption, deltaG0, enthalpy of adsorption, deltaH0 and the entropy of adsorption deltaS0. The obtained results showed that the monolayer capacity increases with the increase in temperatures. The obtained values of thermodynamic parameters showed that adsorption of 2,4 DCP is an endothermic process. Synthetic resin was not found efficient to adsorb 2,4 DCP compared to activated carbon. The order of adsorption efficiencies of three resins used in the study found as XAD7HP > XAD4 > XAD1180. PMID:19295102

  17. Effect of Vesicle-to-Micelle Transition on the Interactions of Phospholipid/Sodium Cholate Mixed Systems with Curcumin in Aqueous Solution.

    Science.gov (United States)

    Zhang, Sha; Wang, Xiaoyong

    2016-08-01

    The role of vesicle-to-micelle transition has been investigated in the interactions of phospholipid vesicles, phospholipid/sodium cholate (NaC) mixed vesicles, and phospholipid/NaC mixed micelles with curcumin in aqueous solution. The addition of NaC causes phospholipid vesicles to transit into phospholipid/NaC mixed vesicles and phospholipid/NaC mixed micelles. Turbidity measurement reveals that the presence of curcumin increases the NaC concentration for the solubilization of phospholipid vesicles, which indicates that the bound curcumin tends to suppress the vesicle-to-micelle transition. The pyrene polarity index and curcumin fluorescence anisotropy measurements suggest that phospholipid/NaC mixed micelles have a more compact structure than that of phospholipid vesicles and phospholipid/NaC mixed vesicles. Curcumin associated with phospholipid vesicles, phospholipid/NaC mixed vesicles, and phospholipid/NaC mixed micelles often results in higher intensities of absorption and fluorescence than those of free curcumin. However, phospholipid/NaC mixed vesicles lead to the highest values of absorption and fluorescence intensities, binding constant, and radical-scavenging capacity with curcumin. The different structures in the phospholipid bilayer of phospholipid/NaC mixed vesicles and the hydrophobic part of phospholipid/NaC mixed micelles where curcumin located are discussed to explain the interaction behaviors of phospholipid/NaC mixed systems with curcumin.

  18. Effect of Vesicle-to-Micelle Transition on the Interactions of Phospholipid/Sodium Cholate Mixed Systems with Curcumin in Aqueous Solution.

    Science.gov (United States)

    Zhang, Sha; Wang, Xiaoyong

    2016-08-01

    The role of vesicle-to-micelle transition has been investigated in the interactions of phospholipid vesicles, phospholipid/sodium cholate (NaC) mixed vesicles, and phospholipid/NaC mixed micelles with curcumin in aqueous solution. The addition of NaC causes phospholipid vesicles to transit into phospholipid/NaC mixed vesicles and phospholipid/NaC mixed micelles. Turbidity measurement reveals that the presence of curcumin increases the NaC concentration for the solubilization of phospholipid vesicles, which indicates that the bound curcumin tends to suppress the vesicle-to-micelle transition. The pyrene polarity index and curcumin fluorescence anisotropy measurements suggest that phospholipid/NaC mixed micelles have a more compact structure than that of phospholipid vesicles and phospholipid/NaC mixed vesicles. Curcumin associated with phospholipid vesicles, phospholipid/NaC mixed vesicles, and phospholipid/NaC mixed micelles often results in higher intensities of absorption and fluorescence than those of free curcumin. However, phospholipid/NaC mixed vesicles lead to the highest values of absorption and fluorescence intensities, binding constant, and radical-scavenging capacity with curcumin. The different structures in the phospholipid bilayer of phospholipid/NaC mixed vesicles and the hydrophobic part of phospholipid/NaC mixed micelles where curcumin located are discussed to explain the interaction behaviors of phospholipid/NaC mixed systems with curcumin. PMID:27403579

  19. 2, 4 dichlorophenol (2, 4-DCP) sorption from aqueous solution using granular activated carbon and polymeric adsorbents and studies on effect of temperature on activated carbon adsorption.

    Science.gov (United States)

    Ghatbandhe, A S; Yenkie, M K N

    2008-04-01

    Adsorption equilibrium, kinetics and thermodynamics of 2,4-dichlorophenol (2,4-DCP), one of the most commonly used chlorophenol, onto bituminous coal based Filtrasorb-400 grade granular activated carbon, were studied in aqueous solution in a batch system with respect to temperature. Uptake capacity of activated carbon found to increase with temperature. Langmuir isotherm models were applied to experimental equilibrium data of 2, 4-DCP adsorption and competitive studies with respect to XAD resin were carried out. Equilibrium data fitted very well to the Langmuir equilibrium model. Adsorbent monolayer capacity 'Q0, Langmuir constant 'b' and adsorption rate constant 'k(a)' were evaluated at different temperatures for activated carbon adsorption. This data was then used to calculate the energy of activation of adsorption and also the thermodynamic parameters, namely the free energy of adsorption, deltaG0, enthalpy of adsorption, deltaH0 and the entropy of adsorption deltaS0. The obtained results showed that the monolayer capacity increases with the increase in temperatures. The obtained values of thermodynamic parameters showed that adsorption of 2,4 DCP is an endothermic process. Synthetic resin was not found efficient to adsorb 2,4 DCP compared to activated carbon. The order of adsorption efficiencies of three resins used in the study found as XAD7HP > XAD4 > XAD1180.

  20. Effect of solution pH on CO: formate formation rates during electrochemical reduction of aqueous CO2 at Sn cathodes

    International Nuclear Information System (INIS)

    The dependence of the molar ratios of CO:formate products formed by electrochemical reduction of CO2 at Sn electrodes was studied in aqueous buffer solutions as a function of pH, with values of those ratios ranging from 1 to 0.15 over the pH range 2.9 to 7.8. However, decreasing pH led to decreased charge yields of CO2 reduction, due to increasing rates of the competing hydrogen evolution reaction. A reaction scheme was proposed to explain the observed relationship and a mathematical model was developed to quantify the dependence of the product ratios on pH and to predict the observed partial current densities of product formation at different pHs and electrode potentials. The reaction scheme was based on multiple protonation states of the intermediate in CO2 reduction; the higher the protonation state, the higher was the tendency of the intermediate to form CO. A generalised reaction mechanism for other electrode materials was also proposed

  1. Effect of electrochemical treatment in H2SO4 aqueous solution on carbon material derived from cellulose with added guanidine phosphate

    Science.gov (United States)

    Tsubota, Toshiki; Wang, Chuanshu; Murakami, Naoya; Ohno, Teruhisa

    2013-03-01

    The electrochemical treatment in a 1 M H2SO4 aqueous solution is applied to the carbon material synthesized from cellulose mixed with guanidine phosphate. The capacitance value increased by the addition of guanidine phosphate; furthermore, the value significantly increased by the electrochemical treatment and was higher than 350 F g-1 at 50 mA g-1. The process used in this study, that is, removing the lignin from wood waste products, such as bamboo, and then mixing with guanidine phosphate before the heat treatment followed by an electrochemical treatment, should be of benefit for the synthesis of a high performance material for the electrodes of electrochemical capacitors. The significant enhancement of the capacitance value appears in the range of 1.5 V∼2.8 V vs. Ag/AgCl for the applied maximum voltage. This voltage range is consistent with the voltage for the significant enhancement of the current value in the CV curve. The change in the capacitance value should be related to the electrochemical reaction of the water electrolysis. The XPS data indicated that the concentrations of both the N atom and the O atom on the surface increased after the electrochemical process.

  2. Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution-2: Effects of nuclear fragmentation and its simulation with PHITS

    Energy Technology Data Exchange (ETDEWEB)

    Maeyama, Takuya [Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Yamashita, Shinichi; Taguchi, Mitsumasa [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Baldacchino, Gerard [CEA Saclay, IRAMIS, UMR 3299 CEA-CNRS SIS2M, Laboratoire de Radiolyse, F-91191 Gif sur Yvette Cedex (France); Sihver, Lembit [Department of Physics, University of Houston, Houston, TX 77204-5005 (United States); Department of Nuclear Engineering, Texas A and M University, TX 77843-3133 (United States); Department of Roanoke College, Salem, VA 24153 (United States); Department of Nuclear Engineering, Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Murakami, Takeshi [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Katsumura, Yosuke, E-mail: katsu@n.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nuclear Professional School, School of Engineering, University of Tokyo, 2-22 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)

    2011-12-15

    The G(OH) values in aqueous coumarin-3-carboxylic-acid (3-CCA) solutions irradiated with {sup 12}C{sup 6+} beams having the energies of 135, 290 and 400 MeV/u were measured by a fluorescent method around the Bragg peak, with 0.6 mm intervals, and quartz cells of 1 cm optical lengths, at the Heavy Ion Medical Accelerator in Chiba, National Institute of Radiological Sciences (NIRS). For each ion, the G(OH) has been calculated as a function of dose average LET and position. The calculated results have been compared to measurements, and the results, reproducibility and reliability of the calculations are discussed in the paper. - Highlights: > Therapeutic ion beam has energy of several hundred MeV/u because it is necessary for a few tens cm range. > With such high energy, nuclear fragmentations of carbon ions occur resulting in production of lighter ions. > In this study, OH yield in water radiolysis near the Bragg peak of therapeutic ion beams was measured. > Measured yields are discussed considering nuclear fragmentation by PHITS code.

  3. Removal of heavy metals from aqueous solutions using opalized tuff

    OpenAIRE

    Golomeova, Mirjana; Zendelska, Afrodita; Golomeov, Blagoj; Krstev, Boris; Jakupi, Shaban

    2015-01-01

    This paper presents the results of the examination of the possibility of applying opalized tuff as a natural raw material for disposal of heavy metals (copper, zinc, manganese and lead) from aqueous solutions. Of actual experiments obtained results show that working conditions attaching to the removal of Cu and Pb ions is more than 91% of zinc ions is above 81%, while manganese ions are removed about 77% .On this can be concluded that the removal of examined heavy metals using opalized tuff i...

  4. Fluorescence of aqueous solutions of commercial humic products

    Science.gov (United States)

    Gosteva, O. Yu.; Izosimov, A. A.; Patsaeva, S. V.; Yuzhakov, V. I.; Yakimenko, O. S.

    2012-01-01

    We have studied the spectral luminescence characteristics of aqueous solutions of humic products obtained from different raw material sources, and their behavior as the excitation wavelength increases from 270 nm to 355 nm. We have identified differences in the spectral properties of industrial humic products from coalified materials, lignin-containing organic waste, and humic products from plant raw material (peat, sapropel, vermicompost). We have shown that humic products from plant raw material have spectral properties closer to those for humic substances in natural water or soil than humic products from coalified materials.

  5. Nano particles@Calix arenas via aqueous solution

    OpenAIRE

    Sahar Dehghani

    2016-01-01

    The electronic structure and magnetic properties of Al2O3, GaN and Fe3O4@ Calix (8) COOH have been studied using ONIOM and DFT methods. The studies focus on how to improve the adsorption of some nano particles solution aqueous for achieving good magnetic and functionalized potential performances. The results revealed that the Fe3O4@ Calix (8) COOH and some of its derivations exhibited better thermodynamic stability. Furthermore, the particle size and magnetic property of the GaN@ Calix (8) C...

  6. Standard Electrode Potentials Involving Radicals in Aqueous Solution: Inorganic Radicals

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, David A.; Huie, Robert E.; Koppenol, Willem H.; Lymar, Sergei V.; Merenyi, Gabor; Neta, Pedatsur; Ruscic, Branko; Stanbury, David M.; Steenken, Steen; Wardman, Peter

    2015-12-01

    Recommendations are made for standard potentials involving select inorganic radicals in aqueous solution at 25 °C. These recommendations are based on a critical and thorough literature review and also by performing derivations from various literature reports. The recommended data are summarized in tables of standard potentials, Gibbs energies of formation, radical pKa’s, and hemicolligation equilibrium constants. In all cases, current best estimates of the uncertainties are provided. An extensive set of Data Sheets is appended that provide original literature references, summarize the experimental results, and describe the decisions and procedures leading to each of the recommendations

  7. The characterization methods for colloids in aqueous solutions

    International Nuclear Information System (INIS)

    This literature review deals with characterization methods for colloids in aqueous solutions and in groundwater. The basis for the review has been the needs of nuclear waste disposal studies and methods applicable in such studies. The methods considered include non-destructive laserspectroscopic methods (e.g. TRLFS, LPAS, PALS), several separation methods (e.g. ultrafiltration, dialysis, electrophoresis, field-flow-fractionation) and also some surface analytical methods, as well as some other methods giving additional information on formation and migration properties of colloids. (au.) (71 refs., 13 figs., 3 tabs.)

  8. The decisive role of free water in determining homogenous ice nucleation behavior of aqueous solutions.

    Science.gov (United States)

    Wang, Qiang; Zhao, Lishan; Li, Chenxi; Cao, Zexian

    2016-01-01

    It is a challenging issue to quantitatively characterize how the solute and pressure affect the homogeneous ice nucleation in a supercooled solution. By measuring the glass transition behavior of solutions, a universal feature of water-content dependence of glass transition temperature is recognized, which can be used to quantify hydration water in solutions. The amount of free water can then be determined for water-rich solutions, whose mass fraction, Xf, is found to serve as a universal relevant parameter for characterizing the homogeneous ice nucleation temperature, the meting temperature of primary ice, and even the water activity of solutions of electrolytes and smaller organic molecules. Moreover, the effects of hydrated solute and pressure on ice nucleation is comparable, and the pressure, when properly scaled, can be incorporated into the universal parameter Xf. These results help establish the decisive role of free water in determining ice nucleation and other relevant properties of aqueous solutions. PMID:27225427

  9. The decisive role of free water in determining homogenous ice nucleation behavior of aqueous solutions

    Science.gov (United States)

    Wang, Qiang; Zhao, Lishan; Li, Chenxi; Cao, Zexian

    2016-05-01

    It is a challenging issue to quantitatively characterize how the solute and pressure affect the homogeneous ice nucleation in a supercooled solution. By measuring the glass transition behavior of solutions, a universal feature of water-content dependence of glass transition temperature is recognized, which can be used to quantify hydration water in solutions. The amount of free water can then be determined for water-rich solutions, whose mass fraction, Xf, is found to serve as a universal relevant parameter for characterizing the homogeneous ice nucleation temperature, the meting temperature of primary ice, and even the water activity of solutions of electrolytes and smaller organic molecules. Moreover, the effects of hydrated solute and pressure on ice nucleation is comparable, and the pressure, when properly scaled, can be incorporated into the universal parameter Xf. These results help establish the decisive role of free water in determining ice nucleation and other relevant properties of aqueous solutions.

  10. Adsorption of ammonium dinitramide (ADN) from aqueous solutions. 1. Adsorption on powdered activated charcoal.

    Science.gov (United States)

    Santhosh, G; Venkatachalam, S; Ninan, K N; Sadhana, R; Alwan, S; Abarna, V; Joseph, M A

    2003-03-17

    Investigations on the adsorption of ammonium dinitramide (NH(4)N(NO(2))(2)) (ADN) from aqueous solutions on powdered activated charcoal (PAC) were carried out in order to find out an effective and easier method of separating ADN from aqueous solutions. The effectiveness of PAC in the selective adsorption of ADN from aqueous solutions of ADN (ADN-F) and ADN in presence of sulfate (SO(4)(2-)) and nitrate (NO(3)(-)) ions (ADN-PS) was examined and compared using batch and column methods. The adsorption process follows both Langmuir and Freundlich adsorption isotherms and the isotherm parameters for the models were determined. The observed data favor the formation of monolayer adsorption. The adsorption capacities were found to be 63.3, 119, 105.3 and 82 mg of ADN per g of PAC for ADN-F (batch), ADN-PS (batch), ADN-F (column) and ADN-PS (column), respectively. Break-through curves for ADN-F and ADN-PS were obtained for the optimization of separation of ADN from aqueous solutions. Elution curves were generated for the desorption of ADN from PAC using hot water as eluent.

  11. Adsorption of ammonium dinitramide (ADN) from aqueous solutions. 1. Adsorption on powdered activated charcoal.

    Science.gov (United States)

    Santhosh, G; Venkatachalam, S; Ninan, K N; Sadhana, R; Alwan, S; Abarna, V; Joseph, M A

    2003-03-17

    Investigations on the adsorption of ammonium dinitramide (NH(4)N(NO(2))(2)) (ADN) from aqueous solutions on powdered activated charcoal (PAC) were carried out in order to find out an effective and easier method of separating ADN from aqueous solutions. The effectiveness of PAC in the selective adsorption of ADN from aqueous solutions of ADN (ADN-F) and ADN in presence of sulfate (SO(4)(2-)) and nitrate (NO(3)(-)) ions (ADN-PS) was examined and compared using batch and column methods. The adsorption process follows both Langmuir and Freundlich adsorption isotherms and the isotherm parameters for the models were determined. The observed data favor the formation of monolayer adsorption. The adsorption capacities were found to be 63.3, 119, 105.3 and 82 mg of ADN per g of PAC for ADN-F (batch), ADN-PS (batch), ADN-F (column) and ADN-PS (column), respectively. Break-through curves for ADN-F and ADN-PS were obtained for the optimization of separation of ADN from aqueous solutions. Elution curves were generated for the desorption of ADN from PAC using hot water as eluent. PMID:12628781

  12. Effect of the Net Charge Distribution on the Aqueous Solution Properties of Polyampholytes Effet de la répartition de la charge nette sur les propriétés des solutions aqueuses de polyampholytes

    Directory of Open Access Journals (Sweden)

    Candau F.

    2006-12-01

    Full Text Available The zwitterion nature of ampholytic polymers provides features that are useful in environmental and industrial applications, e. g. ion-exchange membrane, as flocculants in sewage treatment and in oil recovery processes. In the latter case, the increase in viscosity which is observed in the presence of brine (anti -polyelectrolyte behavior make them ideal candidates for high salinity media. The aqueous solution properties of a series of ampholytic terpolymers based on sodium-2-acrylamido-2- rilethylpropanesulfonate (NaAMPS, Methacryloyloxyethyltrimethylammonium chloride (MADQUAT and acrylamide (AM, prepared in inverse micro emulsions have been investigated by viscometry and light scattering experiments. The distribution of the net charge among the chains was varied by adjusting the initial monomer composition and the degree of conversion. The effect of this distribution on the solubility of the samples and on the chain conformation was studied. It was found that samples with a narrow distribution of net charges were soluble in water even if the average net charge is small. Addition of salt produces a transition from an extended conformation to a more compact one in qualitative agreement with theoretical predictions. A practically alternated NaAMPS- MADQUAT copolymer prepared in homogeneous solution and with a small average net charge shows a behaviour quite similar to that of the terpolymers. La nature zwitterioniquedes polymères ampholytes présente des caractéristiques qui sont utiles dans les applications environnementales et industrielles, comme les membranes d'échange ionique, les floculants dans le traitement des eaux usées et dans les procédés de récupération de pétrole. Dans ce dernier cas, l'augmentation de viscosité qui est observée en présence de saumure (comportement antipolyélectrolyte en fait des candidats idéaux pour des milieux de salinité élevée. Les propriétés de la solution aqueuse d'une série de terpolym

  13. Rheological properties of aqueous solutions of biopolymeric hyaluronan

    Science.gov (United States)

    Szwajczak, Elzbieta

    2004-09-01

    Aqueous solutions of hyaluronic acid (hyaluronan, HA) were studied. The HA compound is a natural polysaccharide, bipolymer. It plays an important role in numerous biological processes as a component of the extracellular matrix, connective tissues and, especially, human and animal synovial joints. Natural and artificial solutions of the HA have demonstrated the viscoelastic nature. These properties are shown to be related to the microstructure parameters (bulk concentration, molecular weight) and external parameters (temperature, stress, shear rate). We emphasize the role of the flow properties of polymeric systems. It is found a liquid crystalline "order" can be "induced" during the material flow. The dynamic properties, such as the elastic shear modulus and viscous shear modulus, are given. These results are discussed in relation to the postulated function of hyaluronic acid in synovial joint and with respect to possibilities o their application in medicine and pharmacology.

  14. Radiolysis of berberine or palmatine in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Marszalek, Milena [Institute of Applied Radiation Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz (Poland); Wolszczak, Marian, E-mail: marianwo@mitr.p.lodz.p [Institute of Applied Radiation Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz (Poland)

    2011-01-15

    The reactions of hydrated electron (e{sub aq}{sup -}), hydrogen atom (H{sup {center_dot}}) (reducing species) and Cl{sub 2}{sup {center_dot}}{sup -},Br{sub 2}{sup {center_dot}}{sup -},{sup {center_dot}}N{sub 3},{sup {center_dot}}OH radicals (oxidizing species) with berberine or palmatine in aqueous solution have been studied by steady-state and pulse radiolysis. The spectra of transient intermediates, leading to the final products, are presented. The rate constants of the reaction of e{sub aq}{sup -} and {sup {center_dot}}OH radical with both alkaloids in the homogenous solution and in the presence of DNA are reported. It is demonstrated that the primary products of the reaction of berberine and palmatine with e{sub aq}{sup -} and radicals generated during radiolysis are unstable and undergo further reactions.

  15. The crystal growth of barium flouride in aqueous solution

    Science.gov (United States)

    Barone, J. P.; Svrjcek, D.; Nancollas, G. H.

    1983-06-01

    The kinetics of growth of barium flouride seed crystals were investigated in aqueous solution at 25°C using a constant composition method, in which the supersaturation and ionic strength were maintained constant by the addition of titrants consisting of barium nitrate and potassium flouride solutions. The rates of reaction, studied over a range of supersaturation (σ ≈ 0.4 to 1.0), were interpreted in terms of crystal growth models. A spiral growth mechanism best describes the data, and scanning electron microscopy indicates a three-dimensional growth. In the presence of inorganic additives such as phosphate, however, induction periods precede a morphological two-dimensional crystallization. Coulter Counter results show little crystal agglomeration.

  16. Analysis and modeling of alkali halide aqueous solutions

    DEFF Research Database (Denmark)

    Kim, Sun Hyung; Anantpinijwatna, Amata; Kang, Jeong Won;

    2016-01-01

    A new model is proposed for correlation and prediction of thermodynamic properties of electrolyte solutions. In the proposed model, terms of a second virial coefficient-type and of a KT-UNIFAC model are used to account for a contribution of binary interactions between ion and ion, and water and ion...... on calculations for various electrolyte properties of alkali halide aqueous solutions such as mean ionic activity coefficients, osmotic coefficients, and salt solubilities. The model covers highly nonideal electrolyte systems such as lithium chloride, lithium bromide and lithium iodide, that is, systems......, respectively, with a Debye-Hückel term for electrostatic interactions. In a second approach of the model, additional parameters for interactions of ion pairs in the KT-UNIFAC are introduced as a correction to get better agreement with data. Structural parameters of ions used in the framework of UNIFAC...

  17. Photoelectron spectra of aqueous solutions from first principles.

    Energy Technology Data Exchange (ETDEWEB)

    Gaiduk, A.lex P.; Govoni, Marco; Seidel, Robert; Skone, Jonathan H.; Winter, Bernd; Galli, Giulia

    2016-06-08

    We present a combined computational and experimental study of the photoelectron spectrum of a simple aqueous solution of NaCl. Measurements were conducted on microjets, and first-principles calculations were performed using hybrid functionals and many-body perturbation theory at the G0W0 level, starting with wave functions computed in ab initio molecular dynamics simulations. We show excellent agreement between theory and experiments for the positions of both the solute and solvent excitation energies on an absolute energy scale and for peak intensities. The best comparison was obtained using wave functions obtained with dielectric-dependent self-consistent and range-separated hybrid functionals. Our computational protocol opens the way to accurate, predictive calculations of the electronic properties of electrolytes, of interest to a variety of energy problems.

  18. Determination of the enthalpy of solute-solvent interaction from the enthalpy of solution: aqueous solutions of erythritol and L-threitol.

    Science.gov (United States)

    Lopes Jesus, A J; Tomé, Luciana I N; Eusébio, M Ermelinda S; Redinha, J S

    2006-05-11

    In this work the enthalpy of the solute-solvent interaction of erythritol and L-threitol in aqueous solution was determined from the values obtained for the enthalpy of solvation. The values for this property were calculated from those determined for the enthalpies of solution and sublimation. To determine the values of the enthalpy of solute-solvent interaction, the solvation process is considered as taking place in three steps: opening a cavity in the solvent to hold the solute molecule, changing the solute conformation when it passes from the gas phase into solution, and interaction between the solute and the solvent molecules. The cavity enthalpy was calculated by the scaled particle theory and the conformational enthalpy change was estimated from the value of this function in the gas phase and in solution. Both terms were determined by DFT calculations. The solvent effect on the solute conformation in solution was estimated using the CPCM solvation model. The importance of the cavity and conformational terms in the interpretation of the enthalpy of solvation is noted. While the cavity term has been used by some authors, the conformational term is considered for the first time. The structural features in aqueous solution of erythritol and L-threitol are discussed.

  19. Sorption of 137Cs from Aqueous Waste Solutions using Pottery

    International Nuclear Information System (INIS)

    A simple and inexpensive method for sorption of 137Cs from aqueous solutions using a highly available vase shape pottery material has been investigated. Porosity of the used pottery allowed for the penetration of the radioactive solution through its permeable body. Two routes had been investigated for cesium removal from the radioactive solutions. In the first one, pottery bodies were immersed into the radioactive solutions. In the second method; the radioactive solutions were filled the inner volumes of the pottery bodies. Vase shape pottery showed higher sorption capability for 137Cs much more than its powder forms, especially in the alkaline medium. Pottery bodies showed high potential for 137Cs removal. Adsorption isotherms revealed good lit to the Freundlich and Langumir isotherms. During sorption processes outside and inside the pottery body, 137Cs was well captured inside the amorphous microstructure of the pottery body. In this respect, micro filtration of cesium radionuclides through the used pottery could be postulated. Desorption experiments indicated higher immobilization affinity for radiocesium into pottery bodies, which indicates a high containment for 137Cs with an irreversible fixation mechanism

  20. Hydrophobic effect at aqueous interfaces

    Science.gov (United States)

    Pohorille, Andrew

    2005-01-01

    Conceptual basis for hydrophobic effects in bulk water and at aqueous interfaces have similar conceptual basis but often manifests itself differently. Using a wide range of computer simulations as the basis, I will review different forms of hydrophobic effects at a variety of interfaces starting from simple liquid-vapor and water-oil interfaces and progressing to water-membrane interfaces. I will start with discussing how water is organized at different interfaces, stressing both similarities and differences. The main thread is that, as in the bulk liquid, hydrophobic effects have profound influence on conformational equilibria and organization of both small molecules and macromolecules, but the result of this influence is quite different. Specifically, it will be shown that many small, but not necessarily amphiphilic molecules tend to accumulate at the interface and, and this tendency will be explained. Furthermore, I will show that many short peptides that are disordered in water spontaneously fold into well-defined structures in the interfacial environment. Biological implications of this self-organizing effect will be discussed.

  1. New terahertz dielectric spectroscopy for the study of aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    George, Deepu K.; Charkhesht, Ali; Vinh, N. Q., E-mail: Vinh@vt.edu [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2015-12-15

    We present the development of a high precision, tunable far-infrared (terahertz) frequency-domain dielectric spectrometer for studying the dynamics of biomolecules in aqueous solutions in the gigahertz-to-terahertz frequency. As an important benchmark system, we report on the measurements of the absorption and refractive index for liquid water in the frequency range from 5 GHz to 1.12 THz (0.17–37.36 cm{sup −1} or 0.268–60 mm). The system provides a coherent radiation source with power up to 20 mW in the gigahertz-to-terahertz region. The dynamic range of our instrument reaches 10{sup 12} and the system achieves a spectral resolution of less than 100 Hz. The temperature of samples can be controlled precisely with error bars of ±0.02 °C from 0 °C to 90 °C. Given these attributes, our spectrometer provides unique capabilities for the accurate measurement of even very strongly absorbing materials such as aqueous solutions.

  2. New terahertz dielectric spectroscopy for the study aqueous solutions

    CERN Document Server

    George, Deepu K; Vinh, N Q

    2015-01-01

    We present a development of a high precision, tunable far-infrared (terahertz) frequency-domain dielectric spectrometer for studying the dynamics of biomolecules in aqueous solutions in the gigahertz-to-terahertz frequency. As a first application we report on the measurement of the absorption and refractive index for liquid water in the frequency range from 5 GHz to 1.12 THz (0.17 to 37.36 cm-1 or 0.268 to 60 mm). The system provides a coherent radiation source with a power up to 20 mW in the gigahertz-to-terahertz region. The power signal-to-noise ratio of our instrument reaches 1015 and the system achieves a spectral resolution of less than 100 Hz. The temperature of samples can be controlled precisely with an error bars of 0.02 oC from above 0 oC to 90 oC. Given these attributes, our spectrometer provides unique capabilities for the accurate measurement of even very strongly absorbing materials such as aqueous solutions.

  3. Gamma radiolytic degradation of naphthalene in aqueous solution

    Science.gov (United States)

    Chu, Libing; Yu, Shaoqing; Wang, Jianlong

    2016-06-01

    The decomposition of naphthalene in aqueous solution was studied using gamma irradiation combined with both H2O2 and TiO2 nanoparticles. Gamma irradiation led to a complete degradation of naphthalene and a partial mineralization. With initial concentration of 5-32 mg/L, more than 98% of naphthalene was removed and TOC reduction reached 28-31% at an absorbed dose of 3.0 kGy. The degradation of naphthalene was faster at neutral pH and the initial degradation rate increased with increasing the initial concentration of naphthalene. Addition of H2O2 and TiO2 nanoparticles all enhanced the degradation and mineralization of naphthalene. TOC removal efficiency increased from 28% (irradiation alone) to 35% with addition of H2O2 (40 mg/L), and to 48% with addition of TiO2 (0.8 g/L). The degradation of naphthalene in aqueous solution by gamma irradiation was mainly through the oxidation by ·OH radicals. The intermediate naphthol and carboxylic acids such as formic acid and oxalic acid were identified by LC-MS and IC.

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

    Science.gov (United States)

    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

  5. Method of precipitating uranium from an aqueous solution and/or sediment

    Science.gov (United States)

    Tokunaga, Tetsu K; Kim, Yongman; Wan, Jiamin

    2013-08-20

    A method for precipitating uranium from an aqueous solution and/or sediment comprising uranium and/or vanadium is presented. The method includes precipitating uranium as a uranyl vanadate through mixing an aqueous solution and/or sediment comprising uranium and/or vanadium and a solution comprising a monovalent or divalent cation to form the corresponding cation uranyl vanadate precipitate. The method also provides a pathway for extraction of uranium and vanadium from an aqueous solution and/or sediment.

  6. Free energetics of carbon nanotube association in aqueous inorganic NaI salt solutions: Temperature effects using all-atom molecular dynamics simulations.

    Science.gov (United States)

    Ou, Shu-Ching; Cui, Di; Wezowicz, Matthew; Taufer, Michela; Patel, Sandeep

    2015-06-15

    In this study, we examine the temperature dependence of free energetics of nanotube association using graphical processing unit-enabled all-atom molecular dynamics simulations (FEN ZI) with two (10,10) single-walled carbon nanotubes in 3 m NaI aqueous salt solution. Results suggest that the free energy, enthalpy and entropy changes for the association process are all reduced at the high temperature, in agreement with previous investigations using other hydrophobes. Via the decomposition of free energy into individual components, we found that solvent contribution (including water, anion, and cation contributions) is correlated with the spatial distribution of the corresponding species and is influenced distinctly by the temperature. We studied the spatial distribution and the structure of the solvent in different regions: intertube, intratube and the bulk solvent. By calculating the fluctuation of coarse-grained tube-solvent surfaces, we found that tube-water interfacial fluctuation exhibits the strongest temperature dependence. By taking ions to be a solvent-like medium in the absence of water, tube-anion interfacial fluctuation shows similar but weaker dependence on temperature, while tube-cation interfacial fluctuation shows no dependence in general. These characteristics are discussed via the malleability of their corresponding solvation shells relative to the nanotube surface. Hydrogen bonding profiles and tetrahedrality of water arrangement are also computed to compare the structure of solvent in the solvent bulk and intertube region. The hydrophobic confinement induces a relatively lower concentration environment in the intertube region, therefore causing different intertube solvent structures which depend on the tube separation. This study is relevant in the continuing discourse on hydrophobic interactions (as they impact generally a broad class of phenomena in biology, biochemistry, and materials science and soft condensed matter research), and

  7. The synergistic effect of Na{sub 3}PO{sub 4} and benzotriazole on the inhibition of copper corrosion in tetra-n-butylammonium bromide aerated aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, S.; Dong, J.; Guan, W.W.; Duan, J.M.; Jiang, R.Y. [Department of Applied Chemistry, South China University of Technology, Guangzhou 510640 (China); Feng, Z.P.; Song, W.J. [Guangzhou Institute of Energy Conversion, CAS, Guangzhou 510640 (China)

    2012-11-15

    The effect of Na{sub 3}PO{sub 4} and the mixture of benzotriazole (BTA) and Na{sub 3}PO{sub 4} (SP) on the corrosion of copper in 17 wt% (0.534 mol/L) tetra-n-butylammonium bromide (TBAB) aerated aqueous solution has been investigated by means of weight-loss test, potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy/energy dispersive X-ray techniques. The experimental results showed that a dosage of Na{sub 3}PO{sub 4} stimulated the copper corrosion, and the corrosion rate increased with increasing Na{sub 3}PO{sub 4} concentration, whereas the mixture of BTA and Na{sub 3}PO{sub 4} could protect copper in aqueous TBAB solution. The inhibition action of the mixture of BTA and Na{sub 3}PO{sub 4} on the corrosion of copper is mainly due to the inhibition of the anodic process of corrosion. The inhibition efficiency of a mixture consisting of 2 g/L BTA and 1 g/L Na{sub 3}PO{sub 4} was about 96%. The mixture of BTA and Na{sub 3}PO{sub 4} inhibits the corrosion of copper better than BTA by itself, indicating that Na{sub 3}PO{sub 4} has a synergistic role with BTA on the corrosion inhibition of copper in TBAB aqueous solution. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Removal of silver(I) from aqueous solutions with low-rank Turkish coals

    Energy Technology Data Exchange (ETDEWEB)

    Karabakan, A.; Karabulut, S.; Denizli, A.; Yurum, Y. [University of Hacettepe, Ankara (Turkey). Dept. of Chemistry

    2004-07-01

    The removal of silver ions from aqueous solutions containing low-to-moderate levels of contamination using Turkish Beypazari low-rank coal was investigated. Carboxylic acid and phenolic hydroxyl functional groups present on the coal surface provided adsorption sites for the removal of silver ions from solution via ion exchange. The equilibrium pH of the coal/solution mixture was shown to be the principal factor controlling the extent of recovery of Ag{sup +} ions from aqueous solutions. The optimum pH was measured as 4.0 and it was found that the maximum removal of silver from solution was achieved within 30 min. The maximum adsorption capacity of the Ag{sup +} ions was 1.87 mg/g coal. The adsorption phenomena appeared to follow a typical Langmuir isotherm. It was observed that the use of low-rank coal was considerably more effective in the recovery Ag{sup +} ions from aqueous solutions. Higher amounts of adsorbed Ag{sup +} ions could be desorbed (up to 92%) using 25 mM EDTA. Low-rank Turkish coals were suitable for consecutive use for more than 10 cycles without significant loss of adsorption capacity.

  9. Melittin Aggregation in Aqueous Solutions: Insight from Molecular Dynamics Simulations.

    Science.gov (United States)

    Liao, Chenyi; Esai Selvan, Myvizhi; Zhao, Jun; Slimovitch, Jonathan L; Schneebeli, Severin T; Shelley, Mee; Shelley, John C; Li, Jianing

    2015-08-20

    Melittin is a natural peptide that aggregates in aqueous solutions with paradigmatic monomer-to-tetramer and coil-to-helix transitions. Since little is known about the molecular mechanisms of melittin aggregation in solution, we simulated its self-aggregation process under various conditions. After confirming the stability of a melittin tetramer in solution, we observed—for the first time in atomistic detail—that four separated melittin monomers aggregate into a tetramer. Our simulated dependence of melittin aggregation on peptide concentration, temperature, and ionic strength is in good agreement with prior experiments. We propose that melittin mainly self-aggregates via a mechanism involving the sequential addition of monomers, which is supported by both qualitative and quantitative evidence obtained from unbiased and metadynamics simulations. Moreover, by combining computer simulations and a theory of the electrical double layer, we provide evidence to suggest why melittin aggregation in solution likely stops at the tetramer, rather than forming higher-order oligomers. Overall, our study not only explains prior experimental results at the molecular level but also provides quantitative mechanistic information that may guide the engineering of melittin for higher efficacy and safety. PMID:26208115

  10. Peculiarity of aqueous solutions of 2,2,2-trifluoroethanol.

    Science.gov (United States)

    Burakowski, Andrzej; Gliński, Jacek; Czarnik-Matusewicz, Bogusława; Kwoka, Paulina; Baranowski, Andrzej; Jerie, Kazimierz; Pfeiffer, Helge; Chatziathanasiou, Nikos

    2012-01-12

    Aqueous solutions of 2,2,2-trifluoroethanol appear to show a structural transition at alcohol mole fraction equal to x(TFE) = 0.05, which can be concluded from a discontinuity of the speed of sound. At the same concentration, a discontinuity was observed in the parameters of the long-living component of the positron annihilation spectrum. Moreover, the partial molar volumes of components show transition-like behavior in the range of low solute contents, which is significantly different from nonsubstituted ethanol. The peculiarities of the low concentration system correlate with minor infrared spectra changes assigned to a mode composed of the CH(2) bending and CF(3) stretching internal vibrations being sensitive to polarity of the hydration shell surrounding the solute. The majority of the spectral changes arise from a gradual shift of the equilibrium between trans ↔ gauche isomers when the composition of the solution is changing. A possible explanation for the peculiar behavior of the system is a thermodynamic equilibrium between hydrated monomers and dimers at that respective mole number. PMID:22142252

  11. Enzyme stabilization by glass-derived silicates in glass-exposed aqueous solutions

    Science.gov (United States)

    Ives, J.A.; Moffett, J.R.; Arun, P.; Lam, D.; Todorov, T.I.; Brothers, A.B.; Anick, D.J.; Centeno, J.; Namboodiri, M.A.A.; Jonas, W.B.

    2010-01-01

    Objectives: To analyze the solutes leaching from glass containers into aqueous solutions, and to show that these solutes have enzyme activity stabilizing effects in very dilute solutions. Methods: Enzyme assays with acetylcholine esterase were used to analyze serially succussed and diluted (SSD) solutions prepared in glass and plastic containers. Aqueous SSD preparations starting with various solutes, or water alone, were prepared under several conditions, and tested for their solute content and their ability to affect enzyme stability in dilute solution. Results: We confirm that water acts to dissolve constituents from glass vials, and show that the solutes derived from the glass have effects on enzymes in the resultant solutions. Enzyme assays demonstrated that enzyme stability in purified and deionized water was enhanced in SSD solutions that were prepared in glass containers, but not those prepared in plastic. The increased enzyme stability could be mimicked in a dose-dependent manner by the addition of silicates to the purified, deionized water that enzymes were dissolved in. Elemental analyses of SSD water preparations made in glass vials showed that boron, silicon, and sodium were present at micromolar concentrations. Conclusions: These results show that silicates and other solutes are present at micromolar levels in all glass-exposed solutions, whether pharmaceutical or homeopathic in nature. Even though silicates are known to have biological activity at higher concentrations, the silicate concentrations we measured in homeopathic preparations were too low to account for any purported in vivo efficacy, but could potentially influence in vitro biological assays reporting homeopathic effects. ?? 2009 The Faculty of Homeopathy.

  12. Removal of Dyes from Aqueous Solution by Adsorption on Biomass of Mango (Mangifera Indica) Leaves

    OpenAIRE

    T. Murugan; A. Ganapathi; Valliappan, R.

    2010-01-01

    The potential feasibility of mango leaves powder (MLP) (Mangifera indica) for removal of dye (Grey BL) from aqueous solution was investigated. The effects of various experimental parameters were examined and optimal experimental conditions were decided. Above the value of initial pH 7, the dye studied could be removed effectively. The isothermal data fitted the Langmuir model or Freundlich model. The adsorption processes followed the pseudo-first-order rate kinetics. The results in this study...

  13. Removal of dexamethasone from aqueous solution and hospital wastewater by electrocoagulation

    Energy Technology Data Exchange (ETDEWEB)

    Arsand, Daniel R., E-mail: danielarsand@pelotas.ifsul.edu.br [Chemistry Department, Federal University of Santa Maria, RS (Brazil); Kümmerer, Klaus, E-mail: klaus.kuemmerer@leuphana.de [Institute for Environmental Chemistry, Leuphana University Lüneburg (Germany); Martins, Ayrton F., E-mail: martins@quimica.ufsm.br [Chemistry Department, Federal University of Santa Maria, RS (Brazil)

    2013-01-15

    This study is concerned with the removal of the anti-inflammatory dexamethasone from aqueous solution and hospital wastewater by electrocoagulation. The variation of the toxicity during the electrocoagulation was also studied through experiments that were designed and optimized by means of response surface methodology. The coagulation efficiency was evaluated by measuring the dexamethasone concentration by high performance liquid chromatography coupled to a diode array detector. In addition, variation was evaluated through a Vibrio fischeri test. The results showed an increase in the removal of dexamethasone (up to 38.1%) with a rise of the current applied and a decrease of the inter-electrode distance, in aqueous solutions. The application to hospital effluent showed similar results for the removal of dexamethasone. The main effect of the electrocoagulation was that it removed colloids and reduced the organic load of the hospital wastewater. Regarding the current applied, the calculated energy efficiency was 100%. Without pH adjustment of the aqueous solution or hospital wastewater, the residual aluminum concentration always remained lower than 10 mg L{sup −1}, and, with adjustment (to pH 6.5), lower than 0.30 mg L{sup −1}, at the final stage. No toxicity variation was observed during the electrocoagulation process in aqueous solution, either in the presence or absence of dexamethasone. - Highlights: ► Removal of DEX and organic load from aqueous solution and hospital wastewater by EC ► Evaluation of the toxicity during the removal of DEX by EC ► Suggestion of the EC process as a pretreatment for subsequent processes.

  14. Removal of dexamethasone from aqueous solution and hospital wastewater by electrocoagulation

    International Nuclear Information System (INIS)

    This study is concerned with the removal of the anti-inflammatory dexamethasone from aqueous solution and hospital wastewater by electrocoagulation. The variation of the toxicity during the electrocoagulation was also studied through experiments that were designed and optimized by means of response surface methodology. The coagulation efficiency was evaluated by measuring the dexamethasone concentration by high performance liquid chromatography coupled to a diode array detector. In addition, variation was evaluated through a Vibrio fischeri test. The results showed an increase in the removal of dexamethasone (up to 38.1%) with a rise of the current applied and a decrease of the inter-electrode distance, in aqueous solutions. The application to hospital effluent showed similar results for the removal of dexamethasone. The main effect of the electrocoagulation was that it removed colloids and reduced the organic load of the hospital wastewater. Regarding the current applied, the calculated energy efficiency was 100%. Without pH adjustment of the aqueous solution or hospital wastewater, the residual aluminum concentration always remained lower than 10 mg L−1, and, with adjustment (to pH 6.5), lower than 0.30 mg L−1, at the final stage. No toxicity variation was observed during the electrocoagulation process in aqueous solution, either in the presence or absence of dexamethasone. - Highlights: ► Removal of DEX and organic load from aqueous solution and hospital wastewater by EC ► Evaluation of the toxicity during the removal of DEX by EC ► Suggestion of the EC process as a pretreatment for subsequent processes

  15. Effect of temperature on the protonation of N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid in aqueous solutions: Potentiometric and calorimetric studies

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xingliang [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Div.; China Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry; Zhang, Zhicheng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Div.; Endrizzi, Francesco [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Div.; Martin, Leigh R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Luo, Shunzhong [China Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry; Rao, Linfeng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Div.

    2015-06-01

    The TALSPEAK process (Trivalent Actinide Lanthanide Separations by Phosphorus-reagent Extraction from Aqueous Komplexes) has been demonstrated in several pilot-scale operations to be effective at separating trivalent actinides (An3+) from trivalent lanthanides (Ln3+). However, fundamental studies have revealed undesired aspects of TALSPEAK, such as the significant partitioning of Na+, lactic acid, and water into the organic phase, thermodynamically unpredictable pH dependence, and the slow extraction kinetics. In the modified TALSPEAK process, the combination of the aqueous holdback complexant HEDTA (N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid) with the extractant HEH[EHP] (2-ethyl(hexyl) phosphonic acid mono-2-ethylhexyl ester) in the organic phase has been found to exhibit a nearly flat pH dependence between 2.5 and 4.5 and more rapid phase transfer kinetics for the heavier lanthanides. To help understand the speciation of Ln3+ and An3+ in the modified TALSPEAK, systematic studies are underway on the thermodynamics of major reactions in the HEDTA system under conditions relevant to the process (e.g., higher temperatures). Thermodynamics of the protonation and complexation of HEDTA with Ln3+ were studied at variable temperatures. Equilibrium constants and enthalpies were determined by a combination of techniques including potentiometry and calorimetry. This paper presents the protonation constants of HEDTA at T = (25 to 70) °C. The potentiometric titrations have demonstrated that, stepwise, the first two protonation constants decrease and the third one slightly increases with the increase of temperature. This trend is in good agreement with the enthalpy of protonation directly determined by calorimetry. The results of NMR analysis further confirm that the first two protonation reactions occur on the diamine nitrogen atoms, while the third protonation reaction occurs on the

  16. DNA dynamics in aqueous solution: opening the double helix

    Science.gov (United States)

    Pohorille, A.; Ross, W. S.; Tinoco, I. Jr; MacElroy, R. D. (Principal Investigator)

    1990-01-01

    The opening of a DNA base pair is a simple reaction that is a prerequisite for replication, transcription, and other vital biological functions. Understanding the molecular mechanisms of biological reactions is crucial for predicting and, ultimately, controlling them. Realistic computer simulations of the reactions can provide the needed understanding. To model even the simplest reaction in aqueous solution requires hundreds of hours of supercomputing time. We have used molecular dynamics techniques to simulate fraying of the ends of a six base pair double strand of DNA, [TCGCGA]2, where the four bases of DNA are denoted by T (thymine), C (cytosine), G (guanine), and A (adenine), and to estimate the free energy barrier to this process. The calculations, in which the DNA was surrounded by 2,594 water molecules, required 50 hours of CRAY-2 CPU time for every simulated 100 picoseconds. A free energy barrier to fraying, which is mainly characterized by the movement of adenine away from thymine into aqueous environment, was estimated to be 4 kcal/mol. Another fraying pathway, which leads to stacking between terminal adenine and thymine, was also observed. These detailed pictures of the motions and energetics of DNA base pair opening in water are a first step toward understanding how DNA will interact with any molecule.

  17. Forecasting of thermodynamic properties of solution for non-polar molecules in aqueous salt solutions and in aqueous organic solutions

    International Nuclear Information System (INIS)

    The scaled particle theory has been used rather successfully to predict the values of thermodynamic properties of solution for non-polar molecules. Two very important parameters has been used in the equations of the scaled particle theory: the hard sphere diameter of the solute and the closeness of the solvent (closeness in which the diameters of the hard sphere particles forming the solvent are taken into account). With non-polar solutes, a correlation exists between calculated and experimental values of: free enthalpy of solution - enthalpy of solution - molar heat capacity change for the solution process. The fit between calculated and experimental values is only more qualitative than quantitative. However the variation of thermodynamic properties with the temperature and the modality is consistent with the variation calculated according to the scaled particle theory. (author)

  18. Comparison of Photochemical Reactions of m-Cresol in Aqueous Solution and in Ice

    Institute of Scientific and Technical Information of China (English)

    PENG Fei; XUE Hong-hai; TANG Xiao-jian; KANG Chun-li; LI Lin-lin; LI Zhe

    2012-01-01

    We compared the photochemical reaction of m-cresol containing OH precursors such as H2O2,NO2- and NO3- in aqueous solution with those in ice.The results show that the conversion rate of m-cresol in aqueous solution was higher than that in ice,H2O2,NO2- and NO3- all accelerated the photoconversion of m-cresol in both aqueous solution and ice.The photochemical reactions of m-cresol obeys the first order kinetics equation.According to the photoproducts identified by GC-MS,we proposed that hydroxylation and nitration reactions occurred in both aqueous solution and ice.Coupling reaction was common in ice,however,in aqueous solution it was found only in UV system.Our results suggest that the photochemical reactions of m-cresol were different in aqueous solution and in ice.

  19. Decolorisation of Reactive Red 120 Dye by Using Single-Walled Carbon Nanotubes in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Edris Bazrafshan

    2013-01-01

    Full Text Available Dyes are one of the most hazardous chemical compound classes found in industrial effluents and need to be treated since their presence in water bodies reduces light penetration, precluding the photosynthesis of aqueous flora. In the present study, single-walled carbon nanotubes (SWCNTs was used as an adsorbent for the successful removal of Reactive Red 120 (RR-120 textile dye from aqueous solutions. The effect of various operating parameters such as initial concentration of dye, contact time, adsorbent dosage and initial pH was investigated in order to find the optimum adsorption conditions. Equilibrium isotherms were used to identify the possible mechanism of the adsorption process. The optimum pH for removing of RR-120 dye from aqueous solutions was found to be 5 and for this condition maximum predicted adsorption capacity for RR-120 dye was obtained as 426.49 mg/g. Also, the equilibrium data were also fitted to the Langmuir, Freundlich and BET equilibrium isotherm models. It was found that the data fitted to BET (R2=0.9897 better than Langmuir (R2=0.9190 and Freundlich (R2=0.8819 model. Finally it was concluded that the single-walled carbon nanotubes can be used for dye removal from aqueous solutions.

  20. Hydrophilic molecularly imprinted polymers for bisphenol A prepared in aqueous solution

    International Nuclear Information System (INIS)

    We have prepared a hydrophilic molecularly imprinted polymer (MIP) for the hydrophobic compound bisphenol A (BPA) in aqueous solution using 3-acrylamido-N,N,N-trimethylpropan-1-aminium chloride (AMTC) as the functional monomer. Under redox-polymerization conditions, BPA forms an ion-pair with AMTC, which was confirmed by 1H-NMR titration. The imprinting effect in aqueous solution was evaluated by comparison of this material with the corresponding non-imprinted polymer (NIP) and with a control polymer (CP) bearing no AMTC. The MIP showed the highest activity among the three polymers, and the imprinting factors as calculated from the amount of BPA bound to the MIP divided by the amounts bound to NIP and CP, respectively, are 1.8 and 6.0. The MIP was selective for BPA in aqueous solution, while structurally related compounds are not recognized. Such a selectivity for a hydrophobic compound is rarely observed in aqueous medium because non-specific binding of BPA inevitably leads to hydrophobic interaction. (author)

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

    Science.gov (United States)

    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.

  2. Thermodynamic and kinetic studies of cadmium adsorption from aqueous solution onto rice husk

    Directory of Open Access Journals (Sweden)

    P. Senthil Kumar

    2010-06-01

    Full Text Available The adsorption behavior of rice husk for cadmium ions from aqueous solutions has been investigated as a function of appropriate equilibrium time, adsorbent dose, temperature, adsorbate concentrations and pH in a batch system. Studies showed that the pH of aqueous solutions affected cadmium removal with the result that removal efficiency increased with increasing solution pH. The maximum adsorption was 98.65% at solution pH 6, contact time 60 min and initial concentration of 25 mg/L. The experimental data were analysed by the Langmuir, Freundlich and Temkin models of adsorption. The characteristic parameters for each isotherm and related correlation coefficients have been determined.  Thermodynamic parameters such as,  and have also been evaluated and it has been found that the sorption process was feasible, spontaneous and exothermic in nature. The kinetics of the sorption were analysed using the pseudo-first order and pseudo-second order kinetic models. Kinetic parameters, rate constants, equilibrium sorption capacities and related correlation coefficients for each kinetic model were calculated and discussed. It was shown that the adsorption of cadmium could be described by the pseudo-second order equation, suggesting that the adsorption process is presumably a chemisorption. The rice husk investigated in this study showed good potential for the removal of cadmium from aqueous solutions. The goal for this work is to develop inexpensive, highly available, effective metal ion adsorbents from natural waste as alternative to existing commercial adsorbents.

  3. Adsorption of CTAB onto perlite samples from aqueous solutions.

    Science.gov (United States)

    Alkan, Mahir; Karadaş, Mecit; Doğan, Mehmet; Demirbaş, Ozkan

    2005-11-15

    In this study, the adsorption properties of unexpanded and expanded perlite samples in aqueous cetyltrimethylammonium bromide (CTAB) solutions were investigated as a function of ionic strength, pH, and temperature. It was found that the amount of cetyltrimethylammonium bromide adsorbed onto unexpanded perlite was greater than that onto expanded perlite. For both perlite samples, the sorption capacity increased with increasing ionic strength and pH and decreasing temperature. Experimental data were analyzed by Langmuir and Freundlich isotherms and it was found that the experimental data were correlated reasonably well by the Freundlich adsorption isotherm. Furthermore, the isotherm parameters (KF and n) were also calculated. The adsorption enthalpy was determined from experimental data at different temperatures. Results have shown that the interaction between the perlite surface and CTAB is a physical interaction, and the adsorption process is an exothermic one.

  4. Photo-degradation behaviour of roseoflavin in some aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Mathes, T.; Hegemann, P. [Institut fuer Biologie/Experimentelle Biophysik, Humboldt Universitaet zu Berlin, Invalidenstrasse 42, D-10115 Berlin (Germany)

    2010-03-24

    An absorption and emission spectroscopic characterization of roseoflavin (8-dimethylamino-8-demethyl-riboflavin, RoF) in aqueous solutions was carried out. The studies were concentrated on roseoflavin in pH 8 phosphate buffer. Absorption cross-section spectra, fluorescence excitation spectra, fluorescence quantum distributions, fluorescence quantum yields and fluorescence lifetimes were determined. The fluorescence of RoF is quenched by photo-induced intra-molecular charge-transfer at room temperature. The photo-degradation of RoF in un-buffered water, in Tris-HCl buffer, and in phosphate buffer was studied. Phosphate buffer and to a smaller extent Tris buffer catalyse the RoF photo-degradation. Photo-excitation of the primary photoproduct, 8-methylamino-riboflavin (8-MNH-RF), enhanced the RoF degradation by triplet 8-MNH-RF - singlet RoF excitation transfer with subsequent triplet-state RoF degradation.

  5. Dual fluorescence of naphthylamines in alkaline aqueous solution

    Science.gov (United States)

    Ma, Li-Hua; Wen, Zhen-Chang; Lin, Li-Rong; Jiang, Yun-Bao

    2001-10-01

    Dual fluorescence was observed with N-(1-naphthyl)aminoacetate (1-NAA) in aqueous solution of pH 13.0 in the presence of cationic surfactants, cetyltrimethylammonium bromide (CTAB) and chloride (CTAC), below and after the critical micelle concentration (CMC). Similar dual fluorescence was also found with 1- and 2-naphthylamine (1-NA, 2-NA), N-(2-naphthyl)aminoacetate (2-NAA) and (1-naphthyl)ethylenediamine (1-NEDA), in the presence and absence of the cationic surfactants, but not with N, N-disubstituted 1- and 2-NAs. We concluded that the dual fluorescence was due to the excited-state deprotonation of the amino group in these NAs. The p Ka*s of the dual fluorescent NAs were estimated to be around 14 from the dual fluorescence pH titrations. No clear correlation was found for p Ka* with the amino substitution and the presence of cationic micelle.

  6. Degradation of aqueous solutions of camphor by heterogeneous photocatalysis.

    Science.gov (United States)

    Sirtori, Carla; Altvater, Priscila K; de Freitas, Adriane M; Peralta-Zamora, Patricio G

    2006-02-28

    In this study the photocatalytic degradation of aqueous solutions of camphor was investigated by using TiO2 and ZnO photocatalysts. In the presence of artificial UV-light the highly photosensitive camphor was almost totally degraded after reaction times of 60 min. However, under these conditions the mineralization degree was lower than 25%. In the presence of semiconductors the degradation was complete after a treatment time of about 30 min. Moreover, the mineralization was considerably greater, mainly with the use of TiO2 (> 80% at reaction time of 60 min). Heterogeneous photocatalytic processes applied in the presence of solar radiation show a promising degradation capability. TiO2-based processes afforded mineralization degrees of about 90% after a reaction time of 120 min, when the system was assisted by aeration.

  7. Protein thermal stabilization in aqueous solutions of osmolytes.

    Science.gov (United States)

    Bruździak, Piotr; Panuszko, Aneta; Jourdan, Muriel; Stangret, Janusz

    2016-01-01

    Proteins' thermal stabilization is a significant problem in various biomedical, biotechnological, and technological applications. We investigated thermal stability of hen egg white lysozyme in aqueous solutions of the following stabilizing osmolytes: Glycine (GLY), N-methylglycine (NMG), N,N-dimethylglycine (DMG), N,N,N-trimethylglycine (TMG), and trimethyl-N-oxide (TMAO). Results of CD-UV spectroscopic investigation were compared with FTIR hydration studies' results. Selected osmolytes increased lysozyme's thermal stability in the following order: Gly>NMG>TMAO≈DMG>TMG. Theoretical calculations (DFT) showed clearly that osmolytes' amino group protons and water molecules interacting with them played a distinctive role in protein thermal stabilization. The results brought us a step closer to the exact mechanism of protein stabilization by osmolytes. PMID:26495438

  8. Infrared spectroscopy for monitoring gas hydrates in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, G.T.; Luzinova, Y.; Mizaikoff, B. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemistry and Biochemistry; Raichlin, Y.; Katzir, A. [Tel-Aviv Univ., Tel-Aviv (Israel). Shool of Physics and Astronomy

    2008-07-01

    This paper introduced the first principles for monitoring gas hydrate formation and dissociation in aqueous solution by evaluating state-responsive infrared (IR) absorption features of water with fiberoptic evanescent field spectroscopy. A first order linear functional relationship was also derived according to Lambert Beer's law in order to quantify the percentage gas hydrate within the volume of water probed via the evanescent field. In addition, spectroscopic studies evaluating seafloor sediments collected from a gas hydrate site in the Gulf of Mexico revealed minimal spectral interferences from sediment matrix components. As such, evanescent field sensing strategies were established as a promising perspective for monitoring the dynamics of gas hydrates in oceanic environments. 21 refs., 5 figs.

  9. Radiation-induced degradation of 4-chloroaniline in aqueous solution

    International Nuclear Information System (INIS)

    The radiation-induced decomposition of 4-chloroaniline (4-ClA) was studied under steady-state conditions using aqueous solutions saturated with air, pure oxygen, N2O, argon and argon in the presence of t-Butanol. Using HPLC-method, the initial G-values of the substrate degradation as well as of a number of radiolytic products were determined. The formation of aminophenols, chlorophenols, aniline and phenol in addition to chloride, ammonia, formaldehyde and mixture of aldehydes as well as carboxylic acids was studied as a function of absorbed dose. Based on the experimental data, probable reaction mechanisms for the degradation of 4-ClA by γ-rays and the formation of the identified products are presented

  10. Ionizing radiation induced degradation of monuron in dilute aqueous solution

    Science.gov (United States)

    Kovács, Krisztina; He, Shijun; Míle, Viktória; Földes, Tamás; Pápai, Imre; Takács, Erzsébet; Wojnárovits, László

    2016-07-01

    The decomposition of monuron was investigated in dilute aqueous solutions using pulse radiolysis and γ-radiolysis in order to identify the intermediates and final products. The main reaction takes place between monuron and the hydroxyl radicals yielding hydroxycyclohexadienyl type radicals with a second order rate constant of (7.4±0.2)×109 mol-1 dm3 s-1. In •OH reactions, the aminyl and phenoxyl radicals may also form. Dechlorination was observed in both hydroxyl radical and hydrated electron reactions. The •OH induced dechlorination reactions are suggested to occur through OH substitution or phenoxyl radical formation. The rate of oxidation is very high in the presence of dissolved oxygen. Some of the results are also supported by quantum chemical calculations.

  11. Adsorption of catechol from aqueous solution by aminated hypercrosslinked polymers

    Institute of Scientific and Technical Information of China (English)

    SUN Yue; LI Xiao-tao; XU Chao; CHEN Jin-long; LI Ai-min; ZHANG Quan-xing

    2005-01-01

    Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1,AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition,thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.

  12. VISCOSITY BEHAVIOR OF LACQUER POLYSACCHARIDE IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    QIU Xingping; ZHANG Lina; DU Yumin; QIAN Baogong

    1991-01-01

    The dependence of measured viscosity on NaCl concentration (0.1 to 3.0M), pH (range of 2-13) and cadoxen composition Wcad (from 2% to 100% ) for the lacquer polysaccharide in NaCl/cadoxen/H2O mixture containing HCl or without were obtained. All the viscosity exponents γ in the Mark-Houwink equations under three different solvent condition are close to 0.5. The wcad dependence of reduced viscosity ηsp/c confirms the single strand chain of the polysaccharide. As the γ values close to 0.5 and values of unperturbed dimension θ/M and [η] much smaller than those for usual linear polymers, these facts suggest that the polysaccharide chains in the aqueous solutions should be dense random coil owing to the highly branched structure.

  13. Adsorption of Anthraquinone Dyes from Aqueous Solutions by Penicillium Terrestre

    Institute of Scientific and Technical Information of China (English)

    XIN Bao-ping; LIU Xiao-mei

    2006-01-01

    Penicillium terrestre was used for removing four anthraquinone dyes from aqueous solution. The experiments were performed in Erlenmeyer flasks and spore suspension was used for inoculation. The results show that the mechanism of dye removal by penicillium terrestre is biosorption and the growing pellets exhibit higher adsorptive capacity than the resting or dead ones. The maximum removals of disperse blue 2BLN, reactive brilliant blue KN-R, acid anthraquinone blue and bromamine acid at the concentration of 120 mg/L by biosorption of growing pellets are 100 %, 100 %, 96 % and 91%, respectively. The 100.0 % and 91.4 % KN-R removals are achieved respectively at the much higher concentration of 250 and 400 mg/L. 2.5 g/L glucose is sufficient for 100% KN-R removal by growing pellets. Salinity (NaC1) increase from 0 to 2% (W/V) moderately accelerates both mycelium growth and KN-R removal.

  14. Extraction of certain radionuclides from aqueous schungite solutions

    International Nuclear Information System (INIS)

    The sorption of 90Sr, 106Ru, 137Cs, and 238Pu from aqueous solutions over a wide pH range was studied. Swelled schungite chips (Nigozero, Kondopozhsk region) (1) and schungite (Onezhsk lake) (2) were tested as sorbents. The minerals were used both untreated and after oxidation (HNO3, 1:1, contact time 1 day). The oxidation, judging from the literature, facilitates the formation of carboxylic and phenolic functional groups on the surface of the carbon-containing sorbents. The presence of such groups is responsible for the high selectivity of the sorbents for multicharged cations. Futhermore, the hydrophobicity of the schungites enormously decreases after the oxidation. The studied sorbents had an average particle size of 0.08-0.1 mm. The schungite was contacted with the solution under static conditions with periodic stirring in order to establish equilibrium. The concentration of the radionuclides was 2-4 MBq/liter. The solution volumes were 10 ml. The sorbent content was 0.01 g. The required pH was set by adding HCl or NaOH

  15. Ultrasonic Measurements of Temperature in Aqueous Solutions: Why and How

    Directory of Open Access Journals (Sweden)

    A. Afaneh

    2011-01-01

    Full Text Available The paper describes two different approaches to ultrasonic measurements of temperature in aqueous solutions. The first approach uses two narrowband ultrasonic transducers and support electronics that form an oscillating sensor which output frequency is related to the measured temperature. This low-cost sensor demonstrated sensitivity of about 40 Hz/K at the distance of 190 mm and the operating frequency of about 25 kHz. The second approach utilised pulse-echo mode at the centre frequency of 20 MHz. The reflector featured a cavity that was filled with deionised water. The ultrasound propagation delay in the cavity was related to the temperature in the solution. The experiments were conducted for deionised water, and solutions of sodium persulfate, sodium chloride, and acetic acid with concentrations up to 0.5 M. In the experiments (conducted within the temperature range from 15 to 30°C, we observed increases in the ultrasound velocity for increased temperatures and concentrations as was expected. Measurement results were compared with literature data for pure and seawater. It was concluded that ultrasonic measurements of temperature were conducted with the resolution well below 0.1 K for both methods. Advantages of ultrasonic temperature measurements over conventional thermometers were discussed.

  16. Removal of aluminum from aqueous solution by organic materials of agricultural use

    International Nuclear Information System (INIS)

    With the objective of identify characteristics of organic materials of common use in agriculture, related to the aluminum removal from aqueous systems, a chemical characterization of six organic materials was carried out. Their capacity to remove aluminum was evaluated in the laboratory by correlating the observed Al-removal with their characteristics. 6 materials were used as follows: rice straw, chicken manure, cowpea, compost, earth warm compost and leonardite oxidable organic C, total N, P, Ca, Mg, Na, K and Al, pH, carbonates, CEC, exchangeable cations, hydrosoluble n and p, fulvic and humic acids, together with their totals acidity and functional groups (carboxylic and phenolic) were evaluated. To estimate the al-removal capacity by the organic materials in aqueous systems, seven aqueous solutions with different Al concentrations (from o to 900 mmol/L) were prepared at an initial pH value of 4.2 and a relation of organic material: aqueous of 180 mg: 200 ml. after shaking and filtration, the pH values and al concentration (by atomic absorption) were determined in the equilibrium solution. The adsorbed Al by the organic materials was calculated by the difference between the initial al concentrations and the amount found in the equilibrium solution. The al removal using all the organic materials was also measured from an aqueous solution, which contained 900 mmol/L of Al in a pH value range between 2.4 and 4.2. The most effective organic material to remove al was the chicken manure, this material removed up to the 80% of Al, leaving in the aqueous solutions concentrations up to 50 mmol/L. the effectiveness of the rest organic materials was as follows: compost, earth warm compost, cowpea, rice straw and leonardite. Positive and significative correlations were obtained between the Al-retention and the following variables: pH values of organic materials, pH values of the equilibrium solution, CaCO3 content, total and hydrosoluble P, total sum and exchangeable sum

  17. The Removal of Dye from Aqueous Solution by Adsorption on Low Cost Adsorbents

    OpenAIRE

    J. J. Chamargore; Bharad, J. V.; Madje, B. R.; Ubale, M. B.

    2010-01-01

    Removal of color from aqueous solution by using low cost easily available adsorbent was conducted by batch experiment. The potential of the low cost adsorbent (Marble powder-treated and untreated) to remove methylene red from aqueous solution were assessed at room temperature. Laboratory investigation of the potential of marble powder and sulphuric acid treated marble powder to remove dye color from aqueous solution has been studied. Parameters studied included pH, adsorbent dose, initial dye...

  18. Measurement and correlation of physical properties of aqueous solutions of tetrabutylammonium hydroxide, piperazine and their aqueous blends

    Institute of Scientific and Technical Information of China (English)

    Rizwan Safdar; Abdul Aziz Omar; Lukman B Ismail; Arhama Bari; Bhajan Lal

    2015-01-01

    The density, viscosity and refractive index of aqueous solutions of tetrabutylammonium hydroxide (TBAOH), pi-perazine (PZ) and their aqueous blends are determined at several temperatures (303.15 to 333.15 K). All these measured physicochemical properties decreases with an increase in temperature. The density data is used to cal-culate the coefficient of thermal expansion and excess molar volume of al aqueous binary and ternary solutions. The coefficient of thermal expansion increases with increase in temperatures and concentrations. The negativity of excess molar volume for al the aqueous solution decreased with increase in temperature. Each physical prop-erty is correlated with temperature by least square method and the corresponding coefficients for each property are presented. The prediction values from correlations for the physical properties are in good agreement with the experimental values.

  19. Removal of Arsenic(V) from Aqueous Solutions by Lanthanum-loaded Zeolite

    Institute of Scientific and Technical Information of China (English)

    PU Hongping; HUANG Jiangbo; JIANG Zhe

    2008-01-01

    A new adsorption process for the removal of As(V) ion from aqueous solutions is studied in this paper using lanthanum-loaded zeolite. The removal efficiency of different adsorbents, activated alumina and activated carbon are obtained in the study for comparison. The results show that lanthanum-loaded zeolite is an effective adsorbent for the removal of As(V) from aqueous solutions.Then, the pH effect and regeneration of modified zeolite on the As(V) removing efficiency are also assessed. It functions with a wide range of pH (2-8). After adsorption, zeolite adsorbed with As(V) ions can be regenerated successfully with 1 M NaOH. Based on the data obtained, an adsorption mechanism and the possible complex structure are tentatively presented. Compare to other adsorbents, easy availability of this adsorbent, excellent adsorption capacity, wide optimum pH range, and regeneration are expected to be utilized in practical operations.

  20. Poisson-Fermi model of single ion activities in aqueous solutions

    Science.gov (United States)

    Liu, Jinn-Liang; Eisenberg, Bob

    2015-09-01

    A Poisson-Fermi model is proposed for calculating activity coefficients of single ions in strong electrolyte solutions based on the experimental Born radii and hydration shells of ions in aqueous solutions. The steric effect of water molecules and interstitial voids in the first and second hydration shells play an important role in our model. The screening and polarization effects of water are also included in the model that can thus describe spatial variations of dielectric permittivity, water density, void volume, and ionic concentration. The activity coefficients obtained by the Poisson-Fermi model with only one adjustable parameter are shown to agree with experimental data, which vary nonmonotonically with salt concentrations.

  1. Removal of Heavy Metals from Aqueous Solution using Clinoptilolite and Stilbite

    OpenAIRE

    Golomeova, Mirjana; Zendelska, Afrodita; Blažev, Krsto; Krstev, Boris; Golomeov, Blagoj

    2014-01-01

    Heavy metals are highly toxic and they must be removed from the polluted streams. Аdsorption by zeolites is currently considered to be very suitable for wastewater treatment because of its simplicity and cost effectiveness. The aim of this investigation was to compare adsorption efficiency of heavy metals (Cu, Zn, Mn and Pb) from aqueous solution using two different types of natural zeolite: clinoptilolite from Bulgaria and stilbite from Macedonia. The obtained information will be basis for f...

  2. Biosorption of malachite green from aqueous solutions by Pleurotus ostreatus using Taguchi method

    OpenAIRE

    Chen, Zhengsuo; Deng, Hongbo; Chen, Can; Yang, Ying; Xu, Heng

    2014-01-01

    Dyes released into the environment have been posing a serious threat to natural ecosystems and aquatic life due to presence of heat, light, chemical and other exposures stable. In this study, the Pleurotus ostreatus (a macro-fungus) was used as a new biosorbent to study the biosorption of hazardous malachite green (MG) from aqueous solutions. The effective disposal of P. ostreatus is a meaningful work for environmental protection and maximum utilization of agricultural residues. The operation...

  3. Evaluation of phosphate removal capacity of Mg/Al layered double hydroxides from aqueous solutions

    OpenAIRE

    Novillo, Corina; Guaya, Diana; Allen-Perkins Avendaño, A.; Armijos, Chabaco; Cortina Pallás, José Luís; Cota, Iuliana

    2014-01-01

    In the present study, the adsorptive properties of phosphate on Mg/Al layered double hydroxides (LDHs) from aqueous solution were evaluated. The FTIR results confirmed the anionic exchange of the nitrate anions from the interlayer space with phosphate anions took place successfully. The kinetics experiments indicated that the kinetic models which best describe phosphate adsorption on LDHs are the pseudo-second order and intraparticle diffusion models. The effects of the pH and the amount of a...

  4. FT-RAMAN SPECTROSCOPY FOR MONITORING THE POLYMERIZATION OF ACRYLIC ACID IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Jiang Yu; Hui-zhou Liu; Jia-yong Chen

    1999-01-01

    FT-Raman spectroscopy was used to monitor the polymerization of acrylic acid in aqueous solution. A simple method to avoid the noise in the background during the signal processing via Fourier transformation was used in this work. The effects of the amount of initiator used on the polymerization are studied. When the amount of the initiator in the polymerization was increased, both the rate and extent of polymerization of acrylic acid will be increased.

  5. Osmotic Pressure of Aqueous Chondroitin Sulfate Solution: A Molecular Modeling Investigation

    OpenAIRE

    Bathe, Mark; Rutledge, Gregory C.; Grodzinsky, Alan J.; TIDOR, BRUCE

    2005-01-01

    The osmotic pressure of chondroitin sulfate (CS) solution in contact with an aqueous 1:1 salt reservoir of fixed ionic strength is studied using a recently developed coarse-grained molecular model. The effects of sulfation type (4- vs. 6-sulfation), sulfation pattern (statistical distribution of sulfate groups along a chain), ionic strength, CS intrinsic stiffness, and steric interactions on CS osmotic pressure are investigated. At physiological ionic strength (0.15 M NaCl), the sulfation typ...

  6. Structure and phase behavior of aqueous methylcellulose solutions

    Science.gov (United States)

    McAllister, John; Schmidt, Peter; Lodge, Timothy; Bates, Frank

    2015-03-01

    Cellulose ethers (CE) constitute a multi-billion dollar industry, and have found end uses in a broad array of applications from construction materials, food products, personal care products, and pharmaceuticals for more than 80 years. Methylcellulose (MC, with the trade name METHOCEL™) is a CE in which there is a partial substitution of -OH groups with -OCH3 groups. This results in a polymer that is water-soluble at low temperatures, and aqueous solutions of MC display gelation and phase separation at higher temperatures. The nature of MC gelation has been debated for many years, and this project has made significant advances in the understanding of the solution properties of CEs. We have characterized a fibrillar structure of MC gels by cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron scattering (SANS). Using light scattering, turbidity measurements, and dynamic mechanical spectroscopy (DMS) we report that MC microphase separates by nucleation and growth of fibril aggregates, and is a different process from LCST phase separation.

  7. Characterization of Chitin and Chitosan Molecular Structure in Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Franca, Eduardo D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lins, Roberto D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Freitas, Luiz C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Straatsma, t. P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2008-11-08

    Molecular dynamics simulations have been used to characterize the structure of chitin and chitosan fibers in aqueous solutions. Chitin fibers, whether isolated or in the form of a β-chitin nanoparticle, adopt the so-called 2-fold helix with Φ and φ values similar to its crystalline state. In solution, the intramolecular hydrogen bond HO3(n)•••O5(n+1) responsible for the 2-fold helical motif is stabilized by hydrogen bonds with water molecules in a well-defined orientation. On the other hand, chitosan can adopt five distinct helical motifs and its conformational equilibrium is highly dependent on pH. The hydrogen bond pattern and solvation around the O3 atom of insoluble chitosan (basic pH) are nearly identical to these quantities in chitin. Our findings suggest that the solubility and conformation of these polysaccharides are related to the stability of the intrachain HO3(n)•••O5(n+1) hydrogen bond, which is affect by the water exchange around the O3-HO3 hydroxyl group.

  8. Speciation of aluminum in aqueous solutions using ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Bertsch, P.M.; Anderson, M.A.

    1989-03-15

    An ion chromatographic method in which aluminum (AI) is quantitatively determined via postcolumn derivatization with Tiron (4,5-dihydroxy-m-benzenedisulfonic acid) was evaluated for its utility as a method for speciating AI in aqueous solutions. Fluro-, oxalato-, and citratoaluminum complexes were identified by distinct peaks within chromatograms of AI solutions when the appropriate ligand was added. Excellent quantitative agreement between predicted species concentrations (via the thermodynamic speciation model GEOCHEM) and those determined by ion chromatography was obtained for samples prepared in the eluent matrix. The predominantly outer sphere sulfatoaluminum complexes were not observed to elute as singly charged species, but rather exhibited a retention time indistinguishable from the AI(H/sub 2/O)6(3+) species. It is concluded that inner sphere AI complexes (generally possessing relatively high association constants) possess adequate kinetic stability to withstand degradation during the ion exchange process, whereas outer sphere complexes apparently readily dissociate in the presence of the sulfonate exchange sites. Deviations in sample ionic strength (mu) and pH from that of the eluent resulted in some redistribution among species, the degree of which was ligand specific.

  9. Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

    International Nuclear Information System (INIS)

    Ionizing radiation induced degradation of acetylsalicylic acid, its hydrolysis product salicylic acid and a salicylic acid derivative 5-sulpho-salicylic acid, was investigated in dilute aqueous solutions by UV–vis spectrophotometry, HPLC separation and diode-array or MS/MS detection, chemical oxygen demand, total organic carbon content and by Vibrio fischeri toxicity measurements. Hydroxyl radicals were shown to degrade these molecules readily, and first degradation products were hydroxylated derivatives in all cases. Due to the by-products, among them hydrogen peroxide, the toxicity first increased and then decreased with the absorbed dose. With prolonged irradiation complete mineralization was achieved. - Highlights: • In OH induced reactions of salicylates first products are hydroxylated derivatives. • With prolonged irradiation dihydroxy derivatives also form. • In aerated solutions the one-electron oxidant OH induces 3–4 oxidations. • Toxicity first increases and then decreases with dose mainly due to H2O2 formation. • The toxicity in tap water is smaller than in pure water

  10. Adsorption of itaconic acid from aqueous solutions onto alumina

    Directory of Open Access Journals (Sweden)

    JELENA J. GULICOVSKI

    2008-08-01

    Full Text Available Itaconic acid, IA (C5H6O4, was investigated as a potential flocculant for the aqueous processing of alumina powders. The adsorption of IA, as a function of its concentration and pH value of the solution, onto the alumina surface was studied by the solution depletion method. The stability of the suspensions in the presence of itaconic acid was evaluated in light of the surface charge of the alumina powder used, the degree of dissociation of IA, as well as the sedimentation behavior and rheology of the suspensions. It was found that the adsorption process is extremely pH dependent; the maximum adsorption of IA onto alumina surface occurring at a pH close to the value of the first IA dissociation constant, pKa1. Also, IA does not influence the value of the point of zero charge of alumina. It was shown that IA represents an efficient flocculant for concentrated acidic alumina suspensions.

  11. Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids.

    Science.gov (United States)

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

    2015-10-20

    Single molecule electrochemical detection (SMED) is an extremely challenging aspect of electroanalytical chemistry, requiring unconventional electrochemical cells and measurements. Here, SMED is reported using a "quad-probe" (four-channel probe) pipet cell, fabricated by depositing carbon pyrolytically into two diagonally opposite barrels of a laser-pulled quartz quadruple-barreled pipet and filling the open channels with electrolyte solution, and quasi-reference counter electrodes. A meniscus forms at the end of the probe covering the two working electrodes and is brought into contact with a substrate working electrode surface. In this way, a nanogap cell is produced whereby the two carbon electrodes in the pipet can be used to promote redox cycling of an individual molecule with the substrate. Anticorrelated currents generated at the substrate and tip electrodes, at particular distances (typically tens of nanometers), are consistent with the detection of single molecules. The low background noise realized in this droplet format opens up new opportunities in single molecule electrochemistry, including the use of ionic liquids, as well as aqueous solution, and the quantitative assessment and analysis of factors influencing redox cycling currents, due to a precisely known gap size. PMID:26398675

  12. Columnar molecular aggregation in the aqueous solutions of disodium cromoglycate

    Science.gov (United States)

    Agra-Kooijman, Dena M.; Singh, Gautam; Lorenz, Alexander; Collings, Peter J.; Kitzerow, Heinz-S.; Kumar, Satyendra

    2014-06-01

    Stack, chimneylike, and threadlike assemblies have previously been proposed for the structure of disodium cromoglycate (DSCG) aggregates in aqueous solutions. The results of the synchrotron x-ray scattering investigations reported here reveal the formation of simple columnar assemblies with π-π stacking at a separation of 3.4 Å between the DSCG molecules. Lateral separation between the assemblies is concentration and temperature dependent, varying from ˜35 to 42 Å in the orientationally ordered nematic (N) phase and from 27 to 32 Å in the columnar or middle (M) phase having long range lateral positional order. The assemblies' length depends on concentration and consists of ˜23 molecules in the N phase, becoming three to ten times larger in the M phase. The scission energy is concentration dependent in the N phase with values ˜7.19 ± 0.14 kBT (15 wt %), 2.73 ± 0.4 kBT (20 wt %), and 3.05 ± 0.2 kBT (25 wt %). Solutions of all concentrations undergo a spinodal decomposition at temperatures above ˜40 °C, resulting in DSCG-rich regions with the M phase and water-rich regions in the N and isotropic phases.

  13. Cast iron deterioration with time in various aqueous salt solutions

    Indian Academy of Sciences (India)

    Rita Mehra; Aditi Soni

    2002-02-01

    The changes with time in the corrosion rate and corrosion current density on a cast iron electrode in various aqueous salt solutions have been carried out using total immersion test and potentiostatic polarization curves. The concentration of salts taken is expected to be present in potable water. The relative behaviour of these salts towards corrosion has also been studied, which is found to be different from previous studies. The total immersion test parameters viz. weight loss, corrosion rate as well as potentiostatic parameters, open circuit potential, corr, Tafel slopes, corrosion rate, have been calculated by standard methods. Besides these the relative increase in corrosion rate with time as well as the percentage to which corrosion rate should be decreased so as to provide protection towards corrosion have also been calculated. It was found that KCl and NaCl are major contributors than MnSO4, Pb(NO3)2, KI and KBr. The relative increase in corrosion is high in KBr, KI, NaNO3, CaCl2, and less in Pb(NO3)2, NaHCO3 and CaCO3 test solutions. For the reliability of results the data has been statistically analysed.

  14. Removal of copper and cadmium from aqueous solution using switchgrass biochar produced via hydrothermal carbonization process.

    Science.gov (United States)

    Regmi, Pusker; Garcia Moscoso, Jose Luis; Kumar, Sandeep; Cao, Xiaoyan; Mao, Jingdong; Schafran, Gary

    2012-10-30

    Biochar produced from switchgrass via hydrothermal carbonization (HTC) was used as a sorbent for the removal of copper and cadmium from aqueous solution. The cold activation process using KOH at room temperature was developed to enhance the porous structure and sorption properties of the HTC biochar. The sorption efficiency of HTC biochar and alkali activated HTC biochar (HTCB) for removing copper and cadmium from aqueous solution were compared with commercially available powdered activated carbon (PAC). The present batch adsorption study describes the effects of solution pH, biochar dose, and contact time on copper and cadmium removal efficiency from single metal ion aqueous solutions. The activated HTCB exhibited a higher adsorption potential for copper and cadmium than HTC biochar and PAC. Experiments conducted with an initial metal concentration of 40 mg/L at pH 5.0 and contact time of 24 h resulted in close to 100% copper and cadmium removal by activated HTCB at 2 g/L, far greater than what was observed for HTC biochar (16% and 5.6%) and PAC (4% and 7.7%). The adsorption capacities of activated HTCB for cadmium removal were 34 mg/g (0.313 mmol/g) and copper removal was 31 mg/g (0.503 mmol/g). PMID:22687632

  15. Spectroscopic and Thermogravimetric Investigation of Cd(II Dinonyldithiophosphate: Removal of Cadmium from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Nermin Biricik

    2015-01-01

    Full Text Available Dinonyldithiophosphoric acid (HDDTP was synthesised from the reaction of phosphorus pentasulphide and nonyl alcohol. Dinonyldithiophosphate complex of cadmium [Cd(DDTP2] was prepared by mixing solutions of Cd(II with HDDTP in ethanol at room temperature. The acid and its complex were characterised by elemental analysis and spectroscopy. The thermal behaviour of Cd(DNDTP2 was investigated by thermogravimetric analysis. Removal of Cd(II from aqueous media by HDDTP solution was also studied. The optimum conditions for removal of Cd(II were investigated for effects of solvent, pH, contact time, concentration, and inorganic anions. Cd(II was quantitatively removed from aqueous solutions at the pH range of 0.5aqueous solutions.

  16. Application of Homotopy-Perturbation Method to Nonlinear Ozone Decomposition of the Second Order in Aqueous Solutions Equations

    DEFF Research Database (Denmark)

    Ganji, D.D; Miansari, Mo; B, Ganjavi;

    2008-01-01

    In this paper, homotopy-perturbation method (HPM) is introduced to solve nonlinear equations of ozone decomposition in aqueous solutions. HPM deforms a di¢ cult problem into a simple problem which can be easily solved. The effects of some parameters such as temperature to the solutions...

  17. Standard enthalpy of formation of L-glutamine and the products of its dissociation in aqueous solutions

    Science.gov (United States)

    Kochergina, L. A.; Lytkin, A. I.; Krutova, O. N.; Damrina, K. V.

    2014-03-01

    Heat effects of the dissolution of crystalline L-glutamine in water and lithium hydroxide solutions were determined by direct calorimetry at 298.15 K. Standard enthalpies of formation of L-glutamine and the products of its dissociation in aqueous solution were calculated.

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

    Science.gov (United States)

    Lytkin, A. I.; Chernikov, V. V.; Krutova, O. N.; Skvortsov, I. A.; Korchagina, A. S.

    2016-09-01

    Heat effects of the dissolution of crystalline γ-aminobutyric acid in water and potassium hydroxide solutions are determined by direct colorimetry at 298.15 K. Standard enthalpies of formation of γ-aminobutyric acid and the products of its dissociation in aqueous solution are calculated.

  19. Effects of concentration and temperature on the dynamic behavior of PAA-g-PEO aqueous solutions with different counterion species: a dielectric spectroscopy study.

    Science.gov (United States)

    Liu, Chunyan; Zhao, Kongshuang

    2012-01-19

    Dielectric properties of PAA-g-PEO-7% solutions with different counterions were measured as a function of concentration and temperature over a frequency range of 40 Hz to 110 MHz. After the contribution of electrode polarization effects was subtracted, the dielectric spectra of PAA-g-PEO-7% solutions showed three relaxation processes in the experimental frequency range, named low-, mid-, and high-frequency relaxation. The observed three relaxations were strictly analyzed by using the Cole-Cole relaxation function, and the dielectric parameters (dielectric increment Δε and the relaxation time τ) were obtained. The scaling relation of dielectric increment and relaxation time of high frequency with concentration C(p) were obtained and compared with the predictions of scaling theories. The information on the dynamics and microstructure of PAA-g-PEO-7% was obtained. Using different counterion species, the mid- and high-frequency relaxation mechanisms were attributed to the fluctuation of condensed counterions and free counterions, respectively, and the low-frequency relaxation was considered to be caused by the interface polarization of a complex formed by the hydrogen bonding between carboxylic group of PAA and ether oxygen on the side-chain PEO. In addition, by means of Eyring equation, the thermodynamic parameters, enthalpy change ΔH and entropy change ΔS, of the three relaxations were calculated from the relaxation time and discussed from the microscopic thermodynamical view.

  20. Removal of Indigo Carmine Dye from Aqueous Solution Using Magnesium Hydroxide as an Adsorbent

    Directory of Open Access Journals (Sweden)

    Thimmasandra Narayan Ramesh

    2015-01-01

    Full Text Available Magnesium hydroxide is used as an adsorbent for the removal of indigo carmine dye from aqueous solution. We have investigated the effectiveness of removal of indigo carmine dye from aqueous solutions at pH 6-7 and 12-13 using magnesium hydroxide thereby varying the dose of the adsorbent, concentration of the dye, duration, and temperature. Structural transformations of adsorbent during the adsorption process at different pH values are monitored using powder X-ray diffraction and infrared spectroscopy. Different types of adsorption isotherm models were evaluated and it was found that Langmuir isotherm fits well at both pH values (6-7 and 12-13. Adsorption of indigo carmine onto magnesium hydroxide at pH 6-7/pH 12-13 follows pseudo-second order rate kinetics.

  1. Thorium removal from aqueous solutions of Mexican erionite and X zeolite

    International Nuclear Information System (INIS)

    Thorium(IV) removal from aqueous solutions by erionite and X zeolite was investigated. The Th(IV) uptake at different thorium nitrate concentrations (from 0.25 to 25 mM) was evaluated. The thorium content in the aqueous solution was determined by neutron activation analysis. Th(IV) retained by zeolites was 1.7 and 3.7 meq/g for erionite and X zeolite. In order to explain the thorium sorption process in both zeolites, ion exchange mechanism was considered. It was found that thorium sorption behavior is strongly dependent of the type of zeolite, the separation factor for Mexican erionite was αTh(IV)Na(I) Th(IV)Na(I) ∼1, this value suggested an approximately ideal ion exchange behavior. The effect of pH on thorium sorption was also considered. (author)

  2. The removal of lead ions using zeolite nanoparticles from aqueous solutions

    Science.gov (United States)

    Joshi, Parth

    2016-05-01

    The experiment for adsorption of lead ions from its aqueous solutions were carried out at room temperature and initial concentration of lead ions as well as after adsorption were determined by UV-Visible spectrophotometer. The effect of various parameters such as contact time, zeolite nanoparticles dosage and initial concentration of lead ions on the adsorption capacity of zeolite nanoparticles were studied in batch experiment. The kinetics of the adsorption processes was studied by using pseudo-first order and pseudo-second order. The pseudo-second order kinetic model provided the best correlation of the used experimental data compared to the pseudo-first order. The maximum lead ions adsorbed was found to be 43.91 mg/g. The present study indicated that zeolite nanoparticles could be used as an efficient adsorbent for removal of lead ions from aqueous solution.

  3. Chemical modification of amino acids by atmospheric-pressure cold plasma in aqueous solution

    Science.gov (United States)

    Takai, Eisuke; Kitamura, Tsuyoshi; Kuwabara, Junpei; Ikawa, Satoshi; Yoshizawa, Shunsuke; Shiraki, Kentaro; Kawasaki, Hideya; Arakawa, Ryuichi; Kitano, Katsuhisa

    2014-07-01

    Plasma medicine is an attractive new research area, but the principles of plasma modification of biomolecules in aqueous solution remain elusive. In this study, we investigated the chemical effects of atmospheric-pressure cold plasma on 20 naturally occurring amino acids in aqueous solution. High-resolution mass spectrometry revealed that chemical modifications of 14 amino acids were observed after plasma treatment: (i) hydroxylation and nitration of aromatic rings in tyrosine, phenylalanine and tryptophan; (ii) sulfonation and disulfide linkage formation of thiol groups in cysteine; (iii) sulfoxidation of methionine and (iv) amidation and ring-opening of five-membered rings in histidine and proline. A competitive reaction experiment using 20 amino acids demonstrated that sulfur-containing and aromatic amino acids were preferentially decreased by the plasma treatment. These data provide fundamental information for elucidating the mechanism of protein inactivation for biomedical plasma applications.

  4. Study on Properties and Structural Parameters of Microemulsion CTAB/Butanol/Cyclohexane/Salt Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    Chen Yongjie; Qiu Guanming; Tian Yiguang; Fang Li; Xiao Linjiu; Sun Yanbin

    2005-01-01

    The phase diagrams of microemulsion CTAB/butanol/cyclohexane/aqueous solution of nitrate (or aqueous solution of ammonium salt) were determined and the structural parameters and ΔG*o→i were obtained by means of dilution method and theoretical calculation. The effect of different w/s and salt concentration on the stability and structural parameters of microemulsion were investigated. The result shows that with the increase of w/s, the area of microemulsion and Nd decrease, Rw, l and n increase; with the increase of salt concentration, the area of microemulsion, l and Nd decrease, ΔG*o→I, Rw and n increase. Theoretical basis of preparing size-controlled long afterglow luminescence materials and study of the relationship between fluorescence properties and particle size are provided.

  5. The reducibility of sulphuric acid and sulphate in aqueous solution

    International Nuclear Information System (INIS)

    In connection with the Swedish project for final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister. A simple reaction between copper and sulphate is thermodynamically impossible, but copper can react to give copper sulphide if an additional electron donor such as iron(II) is available. The problem was extended to the more general question of the reducibility of sulphur(VI) in dilute aqueous solution. Chemical reduction of sulphate does not take place in dilute solution at temperatures below 100oC. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300oC. The oxidising action of sulphuric acid on metals becomes perceptible only at acid concentrations over 45-50%. In experiments on the cathodic reduction of 74% sulphuric acid the formation of hydrogen sulphide and elementary sulphur starts, depending on the current density, at 50-130oC, and polarographic measurements suggest that the reducible species is not the hydrogen sulphate ion but molecular sulphuric acid. The resistance of copper to oxygen-free sulphuric acid up to a concentration of 60% is well-known. Numerous processes in industrial electrochemistry take place in sulphuric acid or sulphate electrolytes. The reversible metal/metal-sulphate electrodes of lead and cadmium are unstable relative to the corresponding metal sulphides. Nevertheless the reversible lead sulphate electrode does not fail from sulphide formation. All these facts confirm that sulphur(VI) in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be almost certainly be ruled out. (author) 5 figs., 85 refs

  6. 双光束激光处理水溶液对ICP发射光谱的增强作用%Enhancement Effect of Double-Beam Laser Processed Aqueous Solution on ICP Emission Spectrum

    Institute of Scientific and Technical Information of China (English)

    陈金忠; 徐丽晶; 苏红新; 李旭; 王淑芳

    2015-01-01

    In order to change the physical properties of aqueous solution and improve the radiation intensity of the ICP emission spectrum ,the effects of different laser power density and irradiation time on the surface tension and viscosity of aqueous solution were investigated by using near infrared laser at 976 nm and CO2 laser at 10.6 μm to irradiate aqueous solution orthogonally , then the enhancement of ICP spectral intensity with processed solution was discussed .The results showed that the surface ten-sion and viscosity of aqueous solution reduced by 42.13% and 14.03% compared with the untreated ,and the atomization effi-ciency increased by 51.26% at the laser power density 0.265 7 W・cm -2 of 976 nm and 0.206 9 W・cm -2 of CO2 laser with 40 min irradiation time .With the optimized aqueous solution introduced into the ICP source ,the spectral line intensity of sample el-ements As ,Cd ,Cr ,Hg and Pb was enhanced by 46.29% ,94.65% ,30.76% ,33.07% and 94.58% compared to the untreated aqueous solution ,while the signal-to-background ratio increased by 43.84% ,85.35% ,28.71% ,34.37% and 90.91% ,respec-tively .Plasma temperature and electron density also increased by 5.94% and 1.18% respectively .It is obvious that the method of double-beam laser orthogonal irradiation on solution can reduce the surface tension and viscosity of aqueous solution signifi-cantly ,and raise the radiation intensity of ICP source ,and will provide a better condition for detecting the trace heavy metal ele-ments in water samples .%为了改变水溶液的物理性质,提高IC P发射光谱的辐射强度,实验采用波长为976 nm的近红外激光和10.6μm的CO2激光正交辐照水溶液,研究了不同激光功率密度和辐照时间对水溶液表面张力和粘度的影响,也探讨了处理后水溶液对IC P光谱强度的增强作用。实验结果表明,在976 nm激光功率密度为0.2657 W・cm -2,CO2激光为0.2069 W・cm-2以及辐照时间为40 min条件下,

  7. Experiment and model for the surface tension of amine–ionic liquids aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: • The surface tensions of MEA/DEA–ionic liquids aqueous solutions were measured. • The experiments were modeled satisfactorily by using a thermodynamic equation. • The temperature dependence of the surface tension was illustrated. • The effects of the mass fractions of MEA/DEA and ionic liquids were demonstrated. - Abstract: The surface tension (γ) of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4])–monoethanolamine (MEA), 1-butyl-3-methylimidazolium bromide ([Bmim][Br])–MEA, [Bmim][BF4]–diethanolamine (DEA) and [Bmim][Br]–DEA aqueous solutions was measured by using the BZY-1 surface tension meter. The temperature ranged from (293.2 to 323.2) K. The mass fraction of amines and ionic liquids (ILS) respectively ranged from 0.15 to 0.30 and 0.05 to 0.10. A thermodynamic equation was proposed to model the surface tension of amines–ILS aqueous solutions and the calculated results agreed well with the experiments. The effects of temperature, mass fraction of amines and ILS on the surface tension were demonstrated on the basis of experiments and calculations

  8. Photochemical processing of aldrin and dieldrin in frozen aqueous solutions under arctic field conditions

    Energy Technology Data Exchange (ETDEWEB)

    Rowland, Glenn A.; Bausch, Alexandra R. [Department of Chemistry, Villanova University, Villanova, PA 19085 (United States); Grannas, Amanda M., E-mail: amanda.grannas@villanova.edu [Department of Chemistry, Villanova University, Villanova, PA 19085 (United States)

    2011-05-15

    Organochlorine (OC) contaminants are transported to the Polar Regions, where they have the potential to bioaccumulate, presenting a threat to the health of wildlife and indigenous communities. They deposit onto snowpack during winter, and accumulate until spring, when they experience prolonged solar irradiation until snowmelt occurs. Photochemical degradation rates for aldrin and dieldrin, in frozen aqueous solution made from MilliQ water, 500 {mu}M hydrogen peroxide solution or locally-collected melted snow were measured in a field campaign near Barrow, AK, during spring-summer 2008. Significant photoprocessing of both pesticides occurs; the reactions depend on temperature, depth within the snowpack and whether the predominant phase is ice or liquid water. The effect of species present in natural snowpack is comparable to 500 {mu}M hydrogen peroxide, pointing to the potential significance of snowpack-mediated reactions. Aldrin samples frozen at near 0 deg. C were more reactive than comparable liquid samples, implying that the microenvironments experienced on frozen ice surfaces are an important consideration. - Highlights: > Photodegradation rates for aldrin and dieldrin in frozen aqueous solutions made from MilliQ water, H{sub 2}O{sub 2} or melted snow are reported. > Photoprocessing depends on temperature, depth beneath the snowpack surface and dominant phase. > Species present in natural snowpack have a photosensitizing effect comparable to 500 {mu}M H{sub 2}O{sub 2}. > Aldrin samples frozen at near 0 deg. C were more reactive than comparable liquid samples. > Collectively we find that frozen aqueous surfaces play a unique role in aldrin and dieldrin photochemistry. - A field study finds that frozen aqueous solutions of aldrin and dieldrin undergo photochemical degradation under arctic snowpack conditions. The reactions are enhanced in frozen systems and by natural snowpack constituents.

  9. Degradation of some pesticides in aqueous solutions by electron beam and gamma-radiation

    International Nuclear Information System (INIS)

    Decomposition by ionizing radiations of two pesticides (Lannate and Fenvalerate) present in an aqueous solution has been studied on laboratory-scale experiments. The effect of pH of the solution, the concentration of the pesticide and the irradiation dose on the degradation process was investigated. Gamma-irradiation was carried out in air and in combination with nitrogen, oxygen and ozone. Lannate showed more degradation than Fenvalerate in all conditions investigated. Radiation was not enough to achieve the complete decomposition of the pesticides. Adsorption of the pollutants after irradiation was achieved using granular activated carbon (GAC) and two anion exchangers (Dowex 1-X8 and Lewatit AP 246). (author)

  10. Modeling of Pervaporation Separation Benzene from Dilute Aqueous Solutions Through Polydimethylsiloxane Membranes

    Institute of Scientific and Technical Information of China (English)

    彭福兵; 姜忠义

    2005-01-01

    A modified solution-diffusion model was established based on Flory-Huggins thermodynamic theory and Fujita's free volume theory. This model was used for description of the mass transfer of removal benzene from dilute aqueous solutions through polydimethylsiloxane (PDMS) membranes. The effect of component concentration on the interaction parameter between components, that of the polymer membrane on the selectivity to benzene, and that of feed concentration and temperature on the permeation flux and separation factor of benzene/water through PDMS membranes were investigated. Calculated pervaporation fluxes of benzene and water were compared with the experimental results and were in good agreement with the experimental data.

  11. Electrophoretic method for the determination of diffusion coefficients of ions in aqueous solutions

    International Nuclear Information System (INIS)

    The electrophoretic method was recently developed for the determination of diffusion coefficients of ions in aqueous solution. By solving the Fick's second law in the presence of unlimited media and constant quantity of diffusing species we obtain a relationship between the diffusion coefficient and the standard deviation of the distribution profile. The diffusion coefficients of Cd(II), In(III), Zr(IV), Hf(IV), Pu(VI) and [InDTPA]2- in nitric acid solution were determined as well as the effective charge of In-DTPA complex at pH 4.50. (author)

  12. Aqueous Solution Preparation of Ruthenium Nanoparticles Using Ammonium Formate as the Reducing Agent

    Institute of Scientific and Technical Information of China (English)

    LIU Shaohong; CHEN Jialin; GUAN Weiming; BI Jun; CHEN Nanguang; CHEN Dengquan; LIU Manmen; SUN Xudong

    2012-01-01

    Ruthenium,one of the platinum group metals,has drawn much attention due to its catalytic behavior,hardness,electrical conductivity and density.Ruthenium particles are usually prepared on a small scale by the polyol process,however,the size of the obtained ruthenium nanoparticles is most below 10 nm.In this work,ruthenium particles about 200 nm in diameter were obtained in aqueous solution by using ammonium formate as the reducing agent.Tohave a better control of particle's size and shape,the effects of PVP,mixing mode,reaction temperature,solution pH and calcination temperature were investigated.

  13. Interaction between bacteriophage and pyrophyllite clay in aqueous solution

    Science.gov (United States)

    Park, Jeong-Ann; Kim, Jae-Hyun; Kang, Jin-Kyu; Son, Jeong-Woo; Yi, In-Geol; Kim, Song-Bae

    2014-05-01

    Viral contamination results in a degradation in drinking water quality and a threat to public health. Toprovide safe drinking water, water treatment alternatives using various adsorbents and filter media such as activated carbon, bituminous coal, quartz sand and clay have been considered. Pyrophyllite is a 2:1 clay mineral having dioctahedral layer structure with octahedrally coordinated Al ion sheets between two sheets of SiO4 tetrahedra. It is a hydrous aluminosilicate clay with the chemical composition AlSi2O5(OH). Pyrophyllite has recently been investigated as a potential low-cost and environmental friendly adsorbent for removing various contaminants. The aim of this study was to investigate the removal of the bacteriophage MS2 from aqueous solution using pyrophyllite. Batch experiments were conducted to examine the MS2 sorption to pyrophyllite. The influence of fluoride, a groundwater contaminant, on the removal of MS2 was also observed. Batch results demonstrated that pyrophyllite was effective in MS2 removal. The percent removal increased from 5.26% to 99.99% (= 4.0 log removal) as the pyrophyllite concentrations increased from 0.2 to 20 g/L. More than 99% of MS2 could be removed with a pyrophyllite concentration of ≥ 4 g/L. The sorption of MS2 to pyrophyllite was rapid. Within 15 min, approximately 99.98% (= 3.7 log removal) of MS2 was attained. More than 4.0 log removal was achieved after 180 min. The experimental data were analyzed with the pseudo first-order and pseudo second-order kinetic models. The correlation coefficient showed that pseudo second-order model was better than pseudo first-order model at describing the kinetic data. The amount of MS2 removed at equilibrium was determined to be 1.43 × 108 pfu/g from the pseudo second-order model. The experimental data were also analyzed with the Freundlich and Langmuir isotherm models. The correlation coefficients showed that the Langmuir model was more suitable than the Freundlich model for MS2

  14. Oxidative dissolution of spent nuclear fuel in aqueous alkaline solutions - An alternative to the Purex process?

    Energy Technology Data Exchange (ETDEWEB)

    Runde, Wolfgang; Peper, Shane; Brodnax, Lia; Crooks, William; Zehnder, Ralph; Jarvinen, Gordon

    2004-07-01

    As an alternative to acidic reprocessing of spent nuclear, oxidative dissolution of UO{sub 2} into aqueous alkaline solutions and subsequent separation of fission products is considered. The efficacy of such a method is limited by the kinetics of the UO{sub 2} dissolution and the capacity of alkaline solutions for dissolved U(VI) species. We performed a series of dissolution studies on UO{sub 2} and U{sub 3}O{sub 8} in aqueous alkaline solutions applying various oxidants. Among the oxidative agents commonly used to transform low-valence actinides into their higher oxidation states, H{sub 2}O{sub 2} has proven to be the most effective in basic media. Consequently, we investigated the dissolution of UO{sub 2} and U{sub 3}O{sub 8} in NaOH-H{sub 2}O{sub 2} and Na{sub 2}CO{sub 3}-H{sub 2}O{sub 2} solutions and determined the dissolution kinetics as a function of peroxide and hydroxide (carbonate) concentrations. Methods to remove fission products, e.g., Cs, Sr, Ba and Zr, from alkaline solutions will be evaluated based upon their decontamination factors. We will discuss the feasibility of using chemically oxidizing alkaline solutions as an alternative spent nuclear fuel reprocessing method based on results from experimental quantitative investigations. (authors)

  15. Self-healing effect of ceria electrodeposited thin films on stainless steel in aggressive 0.5 mol/L NaCl aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Desislava Guergova; Emilia Stoyanova; Dimitar Stoychev; Ivalina Avramova; Plamen Stefanov

    2015-01-01

    The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404 (SS) in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after covering it with CeO2-Ce2O3 layer and thermal treatment (i.e. potential of the system CeO2-Ce2O3/SSt.t.), was shifted sharply to a considerably more positive value, while the corro-sion current was reduced noticeably. The X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and scan-ning electron microscopy (SEM) analyses on the observed scratched surface area of the system CeO2-Ce2O3/SSt.t., after exposure of investigated specimens to 0.5 mol/L NaCl corrosion media, showed partial accumulation of ceria, as well as remarkable increase in the concentrations of oxides of Al, Cr and Fe, on the mechanically revealed steel surface. On the basis of the obtained results one could conclude that the secondary passive oxide/hydroxide films, formed after a definite time interval of exposure to corrosion media, acted as barriers, hindering the corrosion processes in active zones. A hypothesis was put forward about the mechanism of self-repairing oxide layers on the steel surface and their corrosion protection effect respectively.

  16. A sedimentation study of graphene oxide in aqueous solution using gradient differential centrifugation.

    Science.gov (United States)

    Huang, Jing-Jing; Yuan, Yong J

    2016-04-28

    This work involved the study of sedimentation of graphene oxide (GO) in aqueous solution by gradient differential centrifugation. GO sheets of size varying from 400 nm to 1100 nm were separated with layer numbers ranging from 2-17. Semiquantitative analysis of FT-IR spectra was conducted based on statistical variance, in which relative oxidation and hydration degrees were numeralized. Combining XRD, optical microscopy and particle size measurements, the dominant effects of hydration and d-spacing on GO sediment in aqueous solution were observed. However, lateral particle shifting showed a relatively insignificant influence even though it has much larger effects on the GO weight compared with the GO thickness. Highly oxidized GO sheets were highly hydrated and had the tendency to face more severe resistance in aqueous sedimentation. Larger d-spacing allowed more water molecules to enter into interlayers and thus improved the degree of hydration, the lower density and the lower sedimentation velocity of GO sheets. However, fast sedimentation could be found in both large and small GO sheets due to the relatively non-dominant effect from lateral size shifting. The underlying mechanism was further probed by the mathematical modeling process. Our study reveals the potential limitations of current theory for explaining GO sedimentation and also demonstrates the effectiveness of gradient differential centrifugation for sorting GO sheets varying in hydration degree and thickness. PMID:27086748

  17. The photochemical decomposition of Indol in an aqueous solution; Descomposicion fotoquimica de Indol en solucion acuosa

    Energy Technology Data Exchange (ETDEWEB)

    Ibarz, A.; Tejero, J.M.; Panades, R.

    1998-06-01

    The photo decomposition of Indol at different pH has been studied. The Indol photo decomposition rate in aqueous solution a maximum at pH 10. By means of a simple mechanism in three steps, it is possible to explain the kinetics behavior of the Indol photo decomposition in aqueous solution. (Author) 6 refs.

  18. Solution properties and taste behavior of lactose monohydrate in aqueous ascorbic acid solutions at different temperatures: Volumetric and rheological approach.

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  20. Nano Polyamidoamine-G7 (NPAMAM-G7 Dendrimer Synthesis and Assessment the Effect of its antibacterial on Escherichia Coli, Klebsiella Oxytoca, Pseudomonas Aeruginosa , Proteus Mirabilis and Staphylococcus Aureus from aqueous solution

    Directory of Open Access Journals (Sweden)

    mitra Gholami

    2016-06-01

    Full Text Available Background: Nano scale dendrimers are macromolecules synthetic which frequently used in medical and health field. This study was aimed to examine synthesis and the antibacterial effect of NanoPolyamidoamine-G7 (NPAMAM-G7 dendrimer on Escherichia Coli, Klebsiella Oxytoca, Pseudomonas Aeruginosa , Proteus Mirabilis and Staphylococcus Aureus from aqueous solution. Material and methods: In this experimental study, initially dilution of 103 CFU/ml were prepared from each strain of bacteria. Then different concentrations of dendrimer (0.025, 0.25, 2.5 and 25 µg/ml in the laboratory temperature (23-25 °C was added to water. In order to determine the efficiency of dendrimers in removal of bacteria, samples were taken at different times (0, 10, 20, 30, 40, 50 and 60 min and were cultured on nutrient agar medium. Samples were incubated for 24 hours at 37 °C and then number of colonies were counted. Results: Antibacterial properties of dendrimers in aqueous solution by increasing the dendrimer concentration and contact time is directly related. At a concentration of 25 μg/ml at 60 minutes all bacteria except Staphylococcus Aureus, and at 30 minutes, Escherichia Coli and Klebsiella Oxytoca bacteria for 100% excluded. The concentration of 2.5 μg/ml at 60 minutes of bacteria, Escherichia Coli, Klebsiella Oxytoca and Proteus Mirabilis are 100% excluded. All concentrations of dendrimers at different times were reduced bacteria in the PAMAM- G7 dendrimer effect on gram-negative bacteria, gram-positive bacteria was better. Conclusion: The NPAMAM-G7 dendrimer with end amine groups exhibited a positive impact on the removal of standard strains, gram-positive and gram-negative bacteria. Therefore, it is possible to use these nanodendrimers as antibacterial in the future.

  1. Ethylbenzene Removal by Carbon Nanotubes from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Bijan Bina

    2012-01-01

    Full Text Available The removal of ethylbenzene (E from aqueous solution by multiwalled, single-walled, and hybrid carbon nanotubes (MWCNTs, SWCNTs, and HCNTs was evaluated for a nanomaterial dose of 1 g/L, concentration of 10–100 mg/L, and pH 7. The equilibrium amount removed by SWCNTs (E: 9.98 mg/g was higher than by MWCNTs and HCNTs. Ethylbenzene has a higher adsorption tendency on CNTs, so that more than 98% of it adsorbed in first 14 min, which is related to the low water solubility and the high molecular weight. The SWCNTs performed better for ethylbenzene sorption than the HCNTs and MWCNTs. Isotherms study indicates that the BET isotherm expression provides the best fit for ethylbenzene sorption by SWCNTs. Carbon nanotubes, specially SWCNTs, are efficient and rapid adsorbents for ethylbenzene which possess good potential applications to maintain high-quality water. Therefore, it could be used for cleaning up environmental pollution to prevent ethylbenzene borne diseases.

  2. The evaporation behavior of sessile droplets from aqueous saline solutions.

    Science.gov (United States)

    Soulié, Virginie; Karpitschka, Stefan; Lequien, Florence; Prené, Philippe; Zemb, Thomas; Moehwald, Helmuth; Riegler, Hans

    2015-09-14

    Quantitative experiments on the evaporation from sessile droplets of aqueous saline (NaCl) solutions show a strong dependence on salt concentration and droplet shape. The experiments were performed with seven decades of initial NaCl concentrations, with various droplet sizes and with different contact angles. The evaporation rate is significantly lower for high salt concentrations and small contact angles than what is expected from the well-accepted diffusion-controlled evaporation scenario for sessile droplets, even if the change of the vapor pressure due to the salt is taken into account. Particle tracking velocimetry reveals that this modification of the evaporation behavior is caused by marangoni flows that are induced by surface tension gradients originating from the local evaporative peripheral salt enrichment. In addition it is found that already very low salt concentrations lead to a pinning of the three phase contact line. Whereas droplets with concentration ≥10(-6) M NaCl are pinned as soon as evaporation starts, droplets with lower salt concentration do evaporate in a constant contact angle mode. Aside from new, fundamental insights the findings are also relevant for a better understanding of the widespread phenomenon of corrosion initiated by sessile droplets.

  3. Uranium biosorption from aqueous solution onto Eichhornia crassipes.

    Science.gov (United States)

    Yi, Zheng-ji; Yao, Jun; Chen, Hui-lun; Wang, Fei; Yuan, Zhi-min; Liu, Xing

    2016-04-01

    Batch experiments were conducted to investigate the biosorption of U(VI) from aqueous solutions onto the nonliving biomass of an aquatic macrophyte Eichhornia crassipes. The results showed that the adsorption of U(VI) onto E. crassipes was highly pH-dependent and the best pH for U(VI) removal was 5.5. U(VI) adsorption proceeded rapidly with an equilibrium time of 30 min and conformed to pseudo-second-order kinetics. The Langmuir isotherm model was determined to best describe U(VI) biosorption with a maximum monolayer adsorption capacity of 142.85 mg/g. Thermodynamic calculation results indicated that the U(VI) biosorption process was spontaneous and endothermic. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis implied that the functional groups (amino, hydroxyl, and carboxyl) may be responsible for the U(VI) adsorption process, in which the coordination and ion exchange mechanisms could be involved. We conclude that E. crassipes biomass is a promising biosorbent for the removal of uranium pollutants. PMID:26854553

  4. Lifetimes of -halo and -azidobenzyl carbocations in aqueous solution

    Indian Academy of Sciences (India)

    R Sanjeev; V Jagannadham

    2002-02-01

    The title cations were produced in aqueous solution by chemical initiation (solvolysis) of benzyl-gem-dihalides and benzyl-gem-diazides. The solvolysis reactions of benzyl-gem-dihalides and benzyl-gem-diazides in water proceed by a stepwise mechanism through -halobenzyl carbocation and -azidobenzyl carbocation intermediates, which are captured by water to give the corresponding carbonyl compounds as the sole detectable products. Rate constant ratio / (M-1) for partitioning of the carbocation between reaction with halide/azide ion and reaction with water is determined by analysis of halide/azide common ion inhibition of the solvolysis reaction. The rate constants (s-1) for the reaction of the cation with solvent water were determined from the experimental values of / and solv, for the solvolysis of the benzyl-gem-dihalides and benzyl-gem-diazides respectively, using = 5 × 109 M-1 s-1 for diffusion-limited reaction of halide/azide ion with -substituted benzyl carbocations. The values of 1/ are thus the lifetimes of the -halobenzyl carbocations and -azidobenzyl carbocations respectively.

  5. Direct Photolysis of Chlorophenols In Aqueous Solution By Ultraviolet Excilamps

    Science.gov (United States)

    Matafonova, Galina; Philippova, Natalya; Batoev, Valeriy

    2011-08-01

    The direct photolysis of 2-chlorophenol (2-CP), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) in model aqueous solution was studied using UV XeBr (282 nm) and KrCl (222 nm) excilamps. The highest pseudo-first order rate constants and quantum yields were found for molecular form of 4-CP (at pH 2 and 5.7) and anionic forms of 2-CP and 2,4-DCP (at pH 11) when irradiated by XeBr excilamp. The maximum removal efficiency of molecular form of 2-CP and 2,4-DCP with the lowest UV dose of absorbed energy was observed using KrCl excilamp. On the contrary, the XeBr excilamp required the lowest dose (˜2 Jṡcm-2) for complete degradation of molecular 4-CP and anionic 2-CP. The highest removal efficiency of anionic form of 4-CP (65%) was achieved when using KrCl excilamp.

  6. Electrochemical degradation of amaranth aqueous solution on ACF.

    Science.gov (United States)

    Fan, Li; Zhou, Yanwei; Yang, Weishen; Chen, Guohua; Yang, Fenglin

    2006-09-21

    The degradation of Amaranth, a kind of azo dye, has been studied under galvanostatic model with activated carbon fiber (ACF) electrode in aqueous solution with electrochemical method. The ACF was used as anode and cathode, respectively for the decolorization process. The onset oxidation potential and reduction potential for Amaranth on ACF were respectively ascertained at 0.6 and -0.4 V. During the range of -1.1 to 0.50 mA cm(-2), the decolorization was clarified into three processes as electroreduction, adsorption and electrooxidation. There were little contributions to the color and COD removals for the process of adsorption. The color removal can be up to 99% when the current density was 0.50 mA cm(-2). The maximum COD removal was 52% for the process of electrooxidation. Hundred percent color removal was obtained when the current density of -1.0 mA cm(-2) was applied. The maximum COD removal was 62% for the electroreduction. The COD removal results from the adsorption of products for the decolorization process of electrooxidation or electroreduction.

  7. Defluoridation from aqueous solutions by granular ferric hydroxide (GFH).

    Science.gov (United States)

    Kumar, Eva; Bhatnagar, Amit; Ji, Minkyu; Jung, Woosik; Lee, Sang-Hun; Kim, Sun-Joon; Lee, Giehyeon; Song, Hocheol; Choi, Jae-Young; Yang, Jung-Seok; Jeon, Byong-Hun

    2009-02-01

    This research was undertaken to evaluate the feasibility of granular ferric hydroxide (GFH) for fluoride removal from aqueous solutions. Batch experiments were performed to study the influence of various experimental parameters such as contact time (1 min-24h), initial fluoride concentration (1-100 mgL(-1)), temperature (10 and 25 degrees C), pH (3-12) and the presence of competing anions on the adsorption of fluoride on GFH. Kinetic data revealed that the uptake rate of fluoride was rapid in the beginning and 95% adsorption was completed within 10 min and equilibrium was achieved within 60 min. The sorption process was well explained with pseudo-first-order and pore diffusion models. The maximum adsorption capacity of GFH for fluoride removal was 7.0 mgg(-1). The adsorption was found to be an endothermic process and data conform to Langmuir model. The optimum fluoride removal was observed between pH ranges of 4-8. The fluoride adsorption was decreased in the presence of phosphate followed by carbonate and sulphate. Results from this study demonstrated potential utility of GFH that could be developed into a viable technology for fluoride removal from drinking water.

  8. Pulse radiolysis study of 5-amino tetrazole in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dey, G.R.; Naik, D.B.; Kishore, K.; Moorthy, P.N. [Bhabha Atomic Research Centre, Bombay (India). Chemistry Div.

    1996-04-01

    Reactions of e{sub aq}{sup -}, H-atoms and {sup .}OH radicals have been studied with 5-amino tetrazole (ATZ) in aqueous solution. e{sub aq}{sup -}reaction in the pH range 4.5-9 did not give any light absorbing transient species but NH{sub 3} was obtained as a product indicating that the site for e{sub aq}{sup -} reactions is the -NH{sub 2} group. In the case of {sup .}OH radical reaction, a transient spectrum with {lambda}{sub max} at 340 nm was obtained at pH 7.5. An identical spectrum was produced by the reaction of SO{sub 4}{sup -.} radicals with ATZ at neutral pH indicating that both {sup .}OH radical and SO{sub 4}{sup -.} radical react by one electron oxidation. The rate constants for the reactions of e{sub aq}{sup -} and {sup .}OH with ATZ at pH 7.5 were found to be 6 x 10{sup 7} and 5.2 x 10{sup 9} dm{sup 3} mol{sup -1} s{sup -1} respectively, whereas the rate constant for H-atom reaction may be < 10{sup 7} dm{sup 3} mol{sup -1} s{sup -1}. (author).

  9. Fenton Oxidation of Methyl Violet in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Saeedeh Hashemian

    2013-01-01

    Full Text Available In this study, oxidative discoloration of methyl violet (MV dye in aqueous solution has been studied using Fenton (Fe2+/H2O2 process. The parameters such as concentration of Fe2+, H2O2, MV, temperature, and Cl− and ions that affected of discoloration in Fenton process were investigated. The rate of degradation is dependent on initial concentration of Fe2+ ion, initial concentration of H2O2, and pH of media. Discoloration of MV was increased by increasing the temperature of reaction. Optimized condition was determined and it was found that the obtained efficiency was about 95.5% after 15 minutes of reaction at pH 3. TOC of dye sample, before and after the oxidation process, was determined. TOC removal indicates partial and significant mineralization of MV dye. The results of experiments showed that degradation of MV dye in Fenton oxidation can be described with a pseudo-irst-order kinetic model. The thermodynamic constants of the Fenton oxidation process were evaluated. The results implied that the oxidation process was feasible, spontaneous, and endothermic.

  10. Formation and reactivity of phenylperoxyl radicals in aqueous solutions

    International Nuclear Information System (INIS)

    The reaction of phenyl radicals with oxygen, to produce phenylperoxyl radicals, and the reactions of several phenylperoxyl radicals with a number of organic compounds in aqueous solutions have been studied by pulse radiolysis. Phenyl radicals were produced by reduction of aryl halides with hydrated electrons. The rate constant for the reaction of 4-carboxyphenyl with O2 was determined from the rate of buildup of the peroxyl radical absorption at 520 nm as a function of [O2] and found to be 1.6 x 109 L mol-1 s-1. Phenyl radicals react with 2-PrOH by H abstraction; a rate constants of 4 x 106 L mol-1 s-1 was determined for 4-carboxyphenyl by competition with the reaction of this radical with O2. Phenylperoxyl radicals react with 4-methoxyphenolate ions, trolox C(6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), ascorbate ions, chlorpromazine, and ABTS [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate ion)] by one-electron oxidation. The rate constants for such reactions, determined from the rate of formation of the one-electron oxidation product as a function of substrate concentration, were found to be near 108-109 L mol-1 s-1. 24 refs., 4 figs., 1 tab

  11. Flash photolysis of chlorine dioxide in aqueous solution

    International Nuclear Information System (INIS)

    The primary process when aqueous solutions of chlorine dioxide are flash photo-lysed by light with a wave length greater than 270 nm is: OClO →hν ClO (2Π) + O (3P). The photochemical decomposition is characterized by the formation of small quantities of O (3P) atoms and of equal amounts of chlorine atoms and molecular oxygen, the latter originating in the reaction: ClOO → Cl + O2. The isomer ClOO is formed by the germinate recombination of ClO and O, a process which is twice as important as diffusion of the fragments into the mass of the solution and one which represents 30 per cent of the decomposition of the chlorine dioxide. Under our experimental conditions, the lifetime of the ClOO is less than one microsecond. Chlorine atoms are precursors of Cl2O2, whose UV absorption spectrum has been determined, and which is formed by the reactions: Cl + OClO → Cl2O2; Cl + Cl- → Cl2-; Cl2- + OClO → Cl2O2 + Cl- k = (1,0 ±0,1) 109 M-1s-1. Cl2O2 disappears by a first-order process which leads to the formation of the ions Cl- and ClO3-. Competition between the reactions: O (3P) + O2 → O3; O (3P) + OClO → ClO3. (kOClO + O)/(kO2 + O) = 1.85±0.25 has been studied and the molar extinction coefficient of ClO3 determined at its absorption maximum (255 nm): ε255nm = (920 ± 90) M-1 cm-1. (author)

  12. Ethylbenzene Removal from Aqueous Solutions by Nano Magnetic Particles

    Directory of Open Access Journals (Sweden)

    Mostafa Hadei

    2016-02-01

    Full Text Available Background and Objectives : Ethylbenzene (EB is a dangerously organic compound which the presence of this pollutant in water solutions can be considered as an environmental and public health hazard. In this study, nano magnetic particles (Fe 3 O 4 were used as an adsorbent to remove ethylbenzene from aqueous solutions. Methods : The specification of the adsorbent was investigated by transmission electronic microscope (TEM and X-ray diffraction (XRD pattern. A 4×4 factorial design including initial concentration of ethylbenzene, nano magnetic particles dose, contact time and pH were studied. Results : The results showed that the maximum ethylbenzene removal by nano magnetic particles was achieved in the following conditions; 100 mg.L -1 , 2000 mg.L -1 , 20 minutes and 8, in initial concentration, nano magnetic concentration, contact time and pH respectively. The most amounts of ethylbenzene adsorption and distribution ratio in optimum condition was 49.9 mg.g -1 and 261.9 l.g -1 respectively. The results demonstrated that the removal rate of ethylbenzene was higher in batch (99.8 % rather than continuous (97.4% condition. Conclusion: the removal rate of ethylbenzene was higher in batch rather than continuous condition.The study of isotherm showed that adsorption data follow up linear isotherm. Comparing adsorption rate of NM particles and other adsorbents proved that Fe 3 o 4 , as a material with high capacity of adsorption can apply for removing ethylbenzene as an efficient and also cheap adsorbent.  

  13. Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam

    International Nuclear Information System (INIS)

    In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 μA). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water

  14. Transparent conducting oxide films of group V doped titania prepared by aqueous chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Elen, Ken [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Strategisch Initiatief Materialen (SIM), SoPPoM Program (Belgium); Capon, Boris [Strategisch Initiatief Materialen (SIM), SoPPoM Programm (Belgium); Coating and Contacting of Nanostructures, Ghent University, Krijgslaan 281 S1, B-9000 Ghent (Belgium); De Dobbelaere, Christopher [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Dewulf, Daan [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Peys, Nick [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw, Kapeldreef 75, B-3001 Heverlee (Belgium); Detavernier, Christophe [Coating and Contacting of Nanostructures, Ghent University, Krijgslaan 281 S1, B-9000 Ghent (Belgium); Hardy, An [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Van Bael, Marlies K., E-mail: marlies.vanbael@uhasselt.be [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium)

    2014-03-31

    Transparent conducting oxide (TCO) films of titania doped with vanadium (V), niobium (Nb) and tantalum (Ta) are obtained by aqueous Chemical Solution Deposition (CSD). The effect of the dopant on the crystallization and microstructure of the resulting films is examined by means of X-ray diffraction and electron microscopy. During annealing of the thin films, in-situ characterization of the crystal structure and sheet resistance is carried out. Niobium doped anatase films, obtained after annealing in forming gas, show a resistivity of 0,28 Ohm cm, which is the lowest resistivity reported for a solution deposited anatase-based TCO so far. Here, we demonstrate that aqueous CSD may provide a strategy for scalable TCO production in the future. - Highlights: • Aqueous chemical solution deposition of doped titanium dioxide • Doping delays the phase transition from anatase to rutile • Lowest resistivity after doping with niobium and annealing in Forming Gas • Transparency higher than 80% in the visible range of optical spectrum.

  15. Extraction of cobalt(II) from aqueous solution by N,N'-carbonyl difatty amides

    Institute of Scientific and Technical Information of China (English)

    Emad A. Jaffar Al-Mulla; Khalid Waleed S. Al-Janabi

    2011-01-01

    The development of economic and environmentally friendly extractants to recover cobalt metal is required due to the increasing demand for this metal. In this study, solvent extraction of Co(Ⅱ) from aqueous solution using a mixture of N,N'-carbonyl difatty amides (CDFAs) synthesised from palm oil as the extractant was carried out. The effects of various parameters such as acid, contact time, extractant concentration, metal ion concentration and stripping agent and the separation of Co(Ⅱ) from other metal ions such as Fe(Ⅱ), Ni(Ⅱ), Zn(Ⅲ) and Cd(Ⅱ) were investigated. It was found that the extraction of Co(Ⅱ) into the organic phase involved the formation of 1:1 complexes. Co(Ⅱ) was successfully separated from commonly associated metal ions such as Fe(Ⅱ), Ni(Ⅱ), Zn(Ⅲ) and Cd(Ⅱ). Co(Ⅱ) stripping from the loaded organic phase was studied in aqueous solution. These results are useful to recover Co(Ⅱ) from aqueous solution utilising (CDFAs) as an extractant.

  16. Transparent conducting oxide films of group V doped titania prepared by aqueous chemical solution deposition

    International Nuclear Information System (INIS)

    Transparent conducting oxide (TCO) films of titania doped with vanadium (V), niobium (Nb) and tantalum (Ta) are obtained by aqueous Chemical Solution Deposition (CSD). The effect of the dopant on the crystallization and microstructure of the resulting films is examined by means of X-ray diffraction and electron microscopy. During annealing of the thin films, in-situ characterization of the crystal structure and sheet resistance is carried out. Niobium doped anatase films, obtained after annealing in forming gas, show a resistivity of 0,28 Ohm cm, which is the lowest resistivity reported for a solution deposited anatase-based TCO so far. Here, we demonstrate that aqueous CSD may provide a strategy for scalable TCO production in the future. - Highlights: • Aqueous chemical solution deposition of doped titanium dioxide • Doping delays the phase transition from anatase to rutile • Lowest resistivity after doping with niobium and annealing in Forming Gas • Transparency higher than 80% in the visible range of optical spectrum

  17. Electrolyte ion adsorption and charge blocking effect at the hematite/aqueous solution interface: an electrochemical impedance study using multivariate data analysis.

    Science.gov (United States)

    Shimizu, K; Nyström, J; Geladi, P; Lindholm-Sethson, B; Boily, J-F

    2015-05-01

    A model-free multivariate analysis using singular value decomposition is employed to refine an equivalent electrical circuit model in order to probe the electrochemical properties of the hematite/water interface in dilute NaCl and NH4Cl solutions using electrochemical impedance spectroscopy. The result shows that the surface protonation is directly related to the mobility and trapping of charge carriers at the mineral surface. Moreover, the point of zero charge can be found at pH where the charge transfer resistance is the highest, in addition to the minimum double layer capacitance. The inner-sphere interaction of the NH4(+) ion with the surface is indicated by an increase of capacitance for charge carrier trapping from the protonated surface as well as lower double layer capacitance and open circuit potential. It is clear that the intrinsic electrochemical activity of hematite depends on the degree of surface (de)protonation and other inner-sphere adsorption, as these processes affect the charge carrier density in the surface state. This work also highlights an important synergistic effect of the two spectral analyses that enables EIS to be utilized in an in-depth investigation of mineral/water interfaces. PMID:25857599

  18. Radiolysis of Reactive Azo Dyes in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Agustin N.M. Bagyo

    2004-07-01

    Full Text Available The effects of radiation on aerated reactive dye solutions i.e Cibacron Violet, Cibacron Orange and Cibacron Yellow solutions have been studied. Parameters analysis were the change of pH after radiation, the change of absorption, degradation products and effects of pH on the radiolysis. The uv-vis absorption of solutions were observed before and after irradiation. pH variation was done from pHs 3, 5, 7, 9 and 12. Irradiation was done at doses of 0, 2, 4, 6, 8 and 10 kGy with dose rate of 5 kGy/h and was determined by a Fricke dosimeter. HPLC with UV detector was used to analyze the degradation products. Oxalic acid was the main degradation product and small amount of succinic acid was also detected.

  19. Radiation induced degradation of ketoprofen in dilute aqueous solution

    International Nuclear Information System (INIS)

    The intermediates and final products of ketoprofen degradation were investigated in 0.4 mmol dm−3 solution by pulse radiolysis and gamma radiolysis. For observation of final products UV−vis spectrophotometry and HPLC separation with diode array detection were used, and for identification MS was used. The reactions of •OH lead to hydroxycyclohexadienyl type radical intermediates, in their further reactions hydroxylated derivatives of ketoprofen form as final products. The hydrated electron is scavenged by the carbonyl oxygen and the electron adduct protonates to ketyl radical •OH is more effective in decomposing ketoprofen than hydrated electron. Chemical oxygen demand and total organic carbon content measurements on irradiated aerated solutions showed that using irradiation technology ketoprofen can be mineralised. The initial toxicity of the solution monitored by the Daphnia magna test steadily decreases with irradiation. Using 5 kGy dose no toxicity of the solution was detected with this test. - Highlights: ► In •OH reactions hydroxylated derivatives of ketoprofen form as stable products. ► •OH is more effective in decomposing ketoprofen than hydrated electron. ► Toxicity of the ketoprofen solution decreases with irradiation.

  20. Characteristics and mechanisms of Ni(Ⅱ) removal from aqueous solution by Chinese loess

    Institute of Scientific and Technical Information of China (English)

    王艳; 唐晓武; 王恒宇

    2015-01-01

    Nickel is a toxic heavy metal among trace elements which has a detrimental impact on living organisms. There is growing need of finding an economic and effective solution for Ni(Ⅱ) immobilization in environments. Chinese loess was selected as adsorbent to remove Ni(Ⅱ) from aqueous solution. Adsorbent dosage, reaction time, solute concentration, temperature, and solution p H also have influences on efficiency of Ni(Ⅱ) removal. The monolayer adsorption capacity of loess towards Ni(Ⅱ) is determined to be about 15.61 mg/g. High temperature and p H favor the removal of Ni(Ⅱ) using Chinese loess soil and the optimal dosage of loess is determined to be 10 g/L. The kinetics and adsorption isotherms of the adsorption process can be best-fitted with the pseudo second order kinetics and Langmuir isothermal model, respectively. The thermodynamic analysis reveals that the adsorption process is spontaneous, endothermic and the system disorder increases with duration. Nickel ions can be removed with the removal efficiency of 98.5% at p H greater than or equal to 9.7. Further studies on loess and Ni(Ⅱ) laden loess(using X-Ray diffraction, Fourier transform infrared spectroscopy) and Ni(Ⅱ) species distribution at various p H have been conducted to discuss the adsorption mechanism. Loess soils in China have proven to be a potential adsorbent for Ni(Ⅱ) removal from aqueous solutions.

  1. Characteristics and mechanisms of Ni(II) removal from aqueous solution by Chinese loess

    Institute of Scientific and Technical Information of China (English)

    王艳; 唐晓武; 王恒宇

    2015-01-01

    Nickel is a toxic heavy metal among trace elements which has a detrimental impact on living organisms. There is growing need of finding an economic and effective solution for Ni(II) immobilization in environments. Chinese loess was selected as adsorbent to remove Ni(II) from aqueous solution. Adsorbent dosage, reaction time, solute concentration, temperature, and solution pH also have influences on efficiency of Ni(II) removal. The monolayer adsorption capacity of loess towards Ni(II) is determined to be about 15.61 mg/g. High temperature and pH favor the removal of Ni(II) using Chinese loess soil and the optimal dosage of loess is determined to be 10 g/L. The kinetics and adsorption isotherms of the adsorption process can be best-fitted with the pseudo second order kinetics and Langmuir isothermal model, respectively. The thermodynamic analysis reveals that the adsorption process is spontaneous, endothermic and the system disorder increases with duration. Nickel ions can be removed with the removal efficiency of 98.5% at pH greater than or equal to 9.7. Further studies on loess and Ni(II) laden loess (using X-Ray diffraction, Fourier transform infrared spectroscopy) and Ni(II) species distribution at various pH have been conducted to discuss the adsorption mechanism. Loess soils in China have proven to be a potential adsorbent for Ni(II) removal from aqueous solutions.

  2. Effects of concentration and temperature on molar volumes of L-serine, L-isoleucine, and L-glutamine in aqueous NaCl and NaNO3 solutions

    Science.gov (United States)

    Riyazuddeen; Kumar, Dheeraj; Afrin, Sadaf

    2014-01-01

    Densities of L-serine, L-isoleucine, L-glutamine in 1.5 mol kg-1 aqueous NaCl, and NaNO3 solutions have been measured for several molal concentrations of amino acids at temperatures from 298.15 to 323.15 K. The partial molar volumes (ϕ{/v 0}) of L-serine, L-isoleucine, and L-glutamine in 1.5 mol kg-1 aqueous NaCl/NaNO3 solutions have been computed using density data. The transfer partial molar volumes (Δtrϕ{/v 0}) of L-serine, L-isoleucine, and L-glutamine from water to 1.5 mol kg-1 aqueous NaCl/1.5 mol kg-1 aqueous NaNO3 solutions have been determined at 298.15 K. The trends of variation of ϕ{/v 0} and Δtrϕ{/v 0} with change in temperature have been discussed in terms of ion-ion, ion-hydrophilic, and ion-hydrophobic interactions operative in solutions.

  3. Effects of Bile Salt Sodium Glycodeoxycholate on the Self-Assembly of PEO-PPO-PEO Triblock Copolymer P123 in Aqueous Solution.

    Science.gov (United States)

    Bayati, Solmaz; Galantini, Luciano; Knudsen, Kenneth D; Schillén, Karin

    2015-12-22

    A comprehensive experimental study on the interaction between the PEO-PPO-PEO block copolymer P123 (EO20PO68EO20) and the anionic bile salt sodium glycodeoxycholate (NaGDC) in water has been performed. The work was aimed at investigating the suitability of using P123 as bile salt sequestrant beside the fundamental aspects of PEO-PPO-PEO block copolymer-bile salt interactions. Various experimental techniques including dynamic and static light scattering, small-angle X-ray scattering, and differential scanning calorimetry (DSC) were employed in combination with electrophoretic mobility measurements. The system was investigated at a constant P123 concentration of 1.74 mM and with varying bile salt concentrations up to approximately 250 mM NaGDC (or a molar ratio n(NaGDC)/n(P123) = 144). In the mixed P123-NaGDC solutions, the endothermic process related to the self-assembly of P123 was observed to gradually decrease in enthalpy and shift to higher temperatures upon progressive addition of NaGDC. To explain this effect, the formation of NaGDC micelles carrying partly dehydrated P123 unimers was proposed and translated into a stoichiometric model, which was able to fit the experimental DSC data. In the mixtures at low molar ratios, NaGDC monomers associated with the P123 micelle forming a charged "P123 micelle-NaGDC" complex with a dehydrated PPO core. These complexes disintegrated upon increasing NaGDC concentration to form small "NaGDC-P123" complexes visualized as bile salt micelles including one or a few P123 copolymer chains.

  4. Direct Assembly of Modified Proteins on Carbon Nanotubes in an Aqueous Solution

    Science.gov (United States)

    Kim, Jae-Woo; Lillehei, Peter T.; Park, Cheol; Harrison, Joycelyn S.

    2007-01-01

    Carbon nanotubes (CNTs) have superior mechanical and electrical properties that have opened up many potential applications. However, poor dispersibility and solubility, due to the substantial van der Waals attraction between tubes, have prevented the use of CNTs in practical applications, especially biotechnology applications. Effective dispersion of CNTs into small bundles or individual tubes in solvents is crucial to ensure homogeneous properties and enable practical applications. In addition to dispersion of CNTs into a solvent, the selection of appropriate solvent, which is compatible with a desired matrix, is an important factor to improve the mechanical, thermal, optical, and electrical properties of CNT-based fibers and composites. In particular, dispersion of CNTs into an aqueous system has been a challenge due to the hydrophobic nature of CNTs. Here we show an effective method for dispersion of both single wall CNTs (SWCNTs) and few wall CNTs (FWCNTs) in an aqueous buffer solution. We also show an assembly of cationized Pt-cored ferritins on the well dispersed CNTs in an aqueous buffer solution.

  5. Partition Equilibrium Between Charged Membrane and Single Electrolyte Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ionic partition equilibrium in charged membrane immersed in solution of single electrolyte with mono valence or multi-valence is systematically investigated and several expressions are established for determination of partition coefficients. On this basis, the effects of the ratio of membrane charge density to bulk electrolyte solution concentration, the charge sign and valence of electrolyte ions and the type of membrane on the partition equilibrium were analyzed and simulated within chosen parameters. It is revealed that ion partition is not related solely with the respective concentrations but also definitely with the concentration ratio of fixed group to bulk solution in addition to the charge sign and the valence. For a counterion, the partition coefficient increases with this ratio and the valence; while for a coion, the partition coefficient decreases with this ratio and the valence. The theoretical calculations were compared with the experimental data and a good agreement was observed.

  6. Partition Equilibrium Between Charged Membrane and Single Electrolyte Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    徐铜文; 杨伟华; 何柄林

    2001-01-01

    Ionic partition equilibrium in charged membrane immersed in solution of single electrolyte with monovalence or multi-valence is systematically investigated and several expressions are established for determination of partition coefficients. On this basis, the effects of the ratio of membrane charge density to hulk electrolyte solution concentration, the charge sign and valence of electrolyte ions and the type of membrane on the partition equilibrium were analyzed and simulated with in chosen parameters. It is revealed that ion partition is not related solely withthe respective concentrations but also definitely with the concentration ratio of fixed group to bulk solution in addition to the charge sign and the valence. For a counterion, the partition coefficient increases with this ratio and the valence; while for a coion, the partition coefficient decreases with this ratio and the valence. The theoreticalcal culations were compared with the experimental data and a good agreement was observed.

  7. Nitrogen-Doped Carbonaceous Materials for Removal of Phenol from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Magdalena Hofman

    2012-01-01

    Full Text Available Carbonaceous material (brown coal modified by pyrolysis, activation, and enrichment in nitrogen, with two different factor reagents, have been used as adsorbent of phenol from liquid phase. Changes in the phenol content in the test solutions were monitored after subsequent intervals of adsorption with selected adsorbents prepared from organic materials. Significant effect of nitrogen present in the adsorbent material on its adsorption capacity was noted. Sorption capacity of these selected materials was found to depend on the time of use, their surface area, and pore distribution. A conformation to the most well-known adsorption isotherm models, Langmuir, and Freundlich ones, confirms the formation of mono- and heterolayer solute (phenol coverage on the surface of the adsorbent applied herein. The materials proposed as adsorbents of the aqueous solution contaminants were proved effective, which means that the waste materials considered are promising activated carbon precursors for liquid phase adsorbents for the environmental protection.

  8. Kinetics and Adsorption Isotherms Studies of Acridine Orange Dye from Aqueous Solution by Activated Charcoal

    OpenAIRE

    2N. Qamar; R. Azmat; Naz, R.; Malik, B.

    2014-01-01

    The goal of this research is to evaluate the efficiency of charcoal as low coast and effective adsorbent for acridine orange (a cationic dye) from aqueous solution at room temperature. Effect of initial pH (2-8), shaking time (5min. - 1hour), adsorbent dose (0.1gm- 0.9gm) and dye concentration (37mg/30ml-185mg/30ml) were investigated. Results demonstrated that charcoal act as good adsorbent for the removal AO where 99.15% of the dye was adsorbed within 30 minutes. For the maximum dye removal ...

  9. Effect of aqueous solution and load on the formation of DLC transfer layer against Co-Cr-Mo for joint prosthesis.

    Science.gov (United States)

    Guo, Feifei; Zhou, Zhifeng; Hua, Meng; Dong, Guangneng

    2015-09-01

    Diamond-like carbon (DLC) coating exhibits excellent mechanical properties such as high hardness, low friction and wear, which offer a promising solution for the metal-on-metal hip joint implants. In the study, the hydrogen-free DLC coating with the element Cr as the interlay addition was deposited on the surface of the Co-Cr-Mo alloy by a unbalanced magnetron sputtering method. The coating thickness was controlled as 2 µm. Nano-indentation test indicated the hardness was about 13 GPa. DLC coated Co-Cr-Mo alloy disc against un-coated Co-Cr-Mo alloy pin (spherical end SR9.5) comprised the friction pairs in the pin-on-disc tribotest under bovine serum albumin solution (BSA) and physiological saline(PS).The tribological behavior under different BSA concetrations(2-20 mg/ml), and applied load (2-15N) was investigated.DLC transfer layer did not form under BSA solution, even though different BSA concetration and applied load changed. The coefficient of friction(COF) under 6 mg/ml BSA at 10 N was the lowest as 0.10. A higher COF of 0.13 was obtained under 20 mg/ml BSA. The boundary absorption layer of protein is the main factor for the counterparts. However, the continous DLC transfer layer was observed under PS solution, which make a lower COF of 0.08.

  10. Effect of aqueous solution and load on the formation of DLC transfer layer against Co-Cr-Mo for joint prosthesis.

    Science.gov (United States)

    Guo, Feifei; Zhou, Zhifeng; Hua, Meng; Dong, Guangneng

    2015-09-01

    Diamond-like carbon (DLC) coating exhibits excellent mechanical properties such as high hardness, low friction and wear, which offer a promising solution for the metal-on-metal hip joint implants. In the study, the hydrogen-free DLC coating with the element Cr as the interlay addition was deposited on the surface of the Co-Cr-Mo alloy by a unbalanced magnetron sputtering method. The coating thickness was controlled as 2 µm. Nano-indentation test indicated the hardness was about 13 GPa. DLC coated Co-Cr-Mo alloy disc against un-coated Co-Cr-Mo alloy pin (spherical end SR9.5) comprised the friction pairs in the pin-on-disc tribotest under bovine serum albumin solution (BSA) and physiological saline(PS).The tribological behavior under different BSA concetrations(2-20 mg/ml), and applied load (2-15N) was investigated.DLC transfer layer did not form under BSA solution, even though different BSA concetration and applied load changed. The coefficient of friction(COF) under 6 mg/ml BSA at 10 N was the lowest as 0.10. A higher COF of 0.13 was obtained under 20 mg/ml BSA. The boundary absorption layer of protein is the main factor for the counterparts. However, the continous DLC transfer layer was observed under PS solution, which make a lower COF of 0.08. PMID:25967039

  11. Effect of organic solvents on reduction of uranyl and plutonium (4) up to metals by sodium amalgam in aqueous-organic solutions

    International Nuclear Information System (INIS)

    Reduction of uranyl and plutonium (4) with sodium amalgam has been studied in water-dioxane, methanol, acetonitrile, dimethyl-formamide, and dimethylsulfoxide solutions. To determine the content of uranium and plutonium, reduced to metal and transferred to amalgam, the mercury and water phases have been analyzed. Uranium has been determined by the titrimetric method and plutonium - radiometrically. The dependence of the uranium and plutonium amalgam yield on the content of organic solvents in the solution has been studied. It has been shown that with the in)reasing concentration of the organic solvent, the yield of the amalgams of these elements decreases. This is due to intensification of hydrolysis and complexing in water-organic solutions. In the solutions of acetonitrile, DMFA, and DMSO with water content of 102M order the amalgamating process does not take place at all. The polarographic and potentiometric methods have been used to show that liquid sodium amalgam with sodium content less than or equal to 0.17 wt.% cannot reduce uranium chloride in dimethylformamide containing 10-2 M H2O to uranium amalgam since the potential arising is less negative than the potential of the Vsup((3))-Vsup(0)(Hg) pair under these conditions

  12. Polystyrene-Poly(sodium methacrylate) Amphiphilic Block Copolymers by ATRP : Effect of Structure, pH, and Ionic Strength on Rheology of Aqueous Solutions

    NARCIS (Netherlands)

    Raffa, Patrizio; Brandenburg, Piter; Wever, Diego A. Z.; Broekhuis, Antonius A.; Picchioni, Francesco

    2013-01-01

    Three well-defined polystyrene-poly(sodium methacrylate) amphiphilic block copolymers characterized by different molecular architecture (diblock, triblock, and four-arm star) have been synthesized by ATRP. The rheology of their water solutions has been evaluated by measuring dynamic moduli and shear

  13. Biosorption of strontium from aqueous solutions onto spent coffee grounds

    International Nuclear Information System (INIS)

    A set of experiments was carried out to evaluate the strontium uptake potential of spent coffee grounds (SCG) by batch tests in aqueous medium. Adsorption of Sr2+ as a function of contact time and adsorbent dose, pH, particles size, agitation speed, temperature and co-ions presence was investigated. Obtained results revealed that the maximum adsorption took place at pH range of 5-8 and temperature values between 283 and 333 K. Particles size effect was not very significant and agitation speed influenced on the equilibrium time. Competitive adsorption experiments allowed us to classify the negative effect on the Sr2+ uptake according to this order Al3+ ≫ Co2+ > Mg2+ > Ca2+ ≫ Na+ > K+ > Cs+. Kinetic study indicated that the Sr2+ uptake was fast and it was well fitted by the pseudo second order reaction model. Adsorption isotherm was well interpreted by Langmuir model. The maximum adsorption capacity was found to be 69.01 mg g−1 at pH 7, 293 K, particles sizes = 200-400 μm and agitation speed 250 rpm. The thermodynamic study revealed that the process was spontaneous (ΔG0 0 2+ (ΔG0 0 > 0) and occurred by physical adsorption (Ea = 8.37 kJ mol-1). FTIR analysis showed carboxylic acid and amino group presence on SCG surface playing a vital role in Sr2+ biosorption. (author)

  14. Removal of patulin from aqueous solutions by propylthiol functionalized SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Appell, Michael, E-mail: michael.appell@ars.usda.gov [Bacterial Foodborne Pathogens and Mycology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, 1815 N. University St., Peoria, IL 61604 (United States); Jackson, Michael A.; Dombrink-Kurtzman, Mary Ann [Renewable Product Technology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, 1815 N. University St., Peoria, IL 61604 (United States)

    2011-03-15

    Propylthiol functionalized SBA-15 silica was investigated to detoxify aqueous solutions contaminated with the regulated mycotoxin patulin. Micelle templated silicas with a specific pore size were synthetically modified to possess propylthiol groups, a functional group known to form Michael reaction products with the conjugated double bond system of patulin. BET surface area analysis indicated the propylthiol functionalized SBA-15 possesses channels with the pore size of 5.4 nm and a surface area of 345 m{sup 2} g{sup -1}. Elemental analysis indicates the silicon/sulfur ratio to be 10:1, inferring one propylthiol substituent for every ten silica residues. The propylthiol modified SBA-15 was effective at significantly reducing high levels of patulin from aqueous solutions (pH 7.0) in batch sorption assays at room temperature. The material was less effective at lower pH; however heating low pH solutions and apple juice to 60 deg, C in the presence of propylthiol functionalized SBA-15 significantly reduced the levels of patulin in contaminated samples. Composite molecular models developed by semi-empirical PM3 and empirical force field methods support patulin permeation through the mesoporous channels of propylthiol functionalized SBA-15. Density functional study at the B3LYP/6-31G(d,p) level predicts the proposed patulin adducts formed by reaction with the thiol residues exhibit less electrophilic properties than patulin. It is demonstrated the use of propylthiol functionalized SBA-15 is a viable approach to reduce patulin levels in aqueous solutions, including contaminated apple juice.

  15. Removal of Cadmium Ions from Aqueous Solution by Silicate-incorporated Hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    SHI Hebin; ZHONG Hong; LIU Yu; DENG Jinyang

    2007-01-01

    This article reports a preliminary research on silicate-incorporated hydroxyapatite as a new environmental mineral used to remove cadmium ions from aqueous solutions. The silicate-incorporated hydroxyapatite was prepared by coprecipitation and calcining, and silicate was incorporated into the crystal lattice of hydroxyapatite by partial substitution of phosphate. The amount of cadmium ions removed by silicate-incorporated hydroxyapatite was significantly elevated, which was 76% higher than that of pure hydroxyapatite. But the sorption behavior of cadmium ions on silicate-incorporated hydroxyapatite was similar to that of pure hydroxyapatite. Morphological study revealed that silicate incorporation confined the crystal growth and increased the specific surface area of hydroxyapatite,which were in favor of enhancing the cadmium ion sorpfion capacity of the samples. Incorporation of silicate into hydroxyapatite seems to be an effective approach to improve the environmental property of hydroxyapatite on removal of aqueous cadmium ions.

  16. Kinetics of the decomposition and the estimation of the stability of 10% aqueous and non-aqueous hydrogen peroxide solutions

    Directory of Open Access Journals (Sweden)

    Zun Maria

    2014-12-01

    Full Text Available In this study, the stability of 10% hydrogen peroxide aqueous and non-aqueous solutions with the addition of 6% (w/w of urea was evaluated. The solutions were stored at 20°C, 30°C and 40°C, and the decomposition of hydrogen peroxide proceeded according to first-order kinetics. With the addition of the urea in the solutions, the decomposition rate constant increased and the activation energy decreased. The temperature of storage also affected the decomposition of substance, however, 10% hydrogen peroxide solutions prepared in PEG-300, and stabilized with the addition of 6% (w/w of urea had the best constancy.

  17. Hydrogen bonding of single acetic acid with water molecules in dilute aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In separation processes,hydrogen bonding has a very significant effect on the efficiency of isolation of acetic acid (HOAc) from HOAc/H2O mixtures. This intermolecular interaction on aggregates composed of a single HOAc molecule and varying numbers of H2O molecules has been examined by using ab initio molecular dynamics simulations (AIMD) and quantum chemical calculations (QCC). Thermodynamic data in aqueous solution were obtained through the self-consistent reaction field calculations and the polarizable continuum model. The aggregation free energy of the aggregates in gas phase as well as in aqueous system shows that the 6-membered ring is the most favorable structure in both states. The relative stability of the ring structures inferred from the thermodynamic properties of the QCC is consistent with the ring distributions of the AIMD simulation. The study shows that in dilute aqueous solution of HOAc the more favorable molecular interaction is the hydrogen bonding between HOAc and H2O molecules,resulting in the separation of acetic acid from the HOAc/H2O mixtures with more difficulty than usual.

  18. Bioremediation of zirconium from aqueous solution by coriolus versicolor: process optimization

    International Nuclear Information System (INIS)

    In the present study the potential of live mycelia of Coriolus versicolor was explored for the removal of zirconium from simulated aqueous solution. Optimum experimental parameters for the bioremediation of zirconium using C. versicolor biomass have been investigated by studying the effect of mycelia dose, concentration of zirconium, contact time and temperature. The isothermal studies indicated that the ongoing bioremediation process was exothermic in nature and obeyed Langmuir adsorption isotherm model. The Gibbs free energy (ΔG), entropy (ΔS) and enthalpy (ΔH) of bioremediation were also determined. The result showed that bioremediation of zirconium by live C. versicolor was feasible and spontaneous at room temperature. The equilibrium data verified the involvement of chemisorption during the bioremediation. The kinetic data indicated the operation of pseudo-second order process during the biosorption of zirconium from aqueous solution. Maximum bioremediation capacity (110.75 mg/g) of C. versicolor was observed under optimum operational conditions: pH 4.5, biomass dose 0.05 mg/100 mL, contact time 6 h and temperature 30 degree C. The results showed that C. versicolor could be used for bioremediation of heavy metal ions from aqueous systems. (author)

  19. Influence of thermal treatment on bentonite used as adsorbent for Cd, Pb, Zn retention from mono-solute and poly-solute aqueous solutions

    Directory of Open Access Journals (Sweden)

    Susana Yamila Martinez Stagnaro

    2012-08-01

    Full Text Available The retentions of Zn, Cd and Pb cations by one treated bentonite up to 750 °C were analyzed. The retentions were evaluated by using mono-and poly-solute aqueous solutions of such cations. The adsorptions were carried out in batch system at room temperature. The solid/liquid ratio was 2% wt.v-1. The solids were characterized by X-ray diffraction, thermal and chemical analyses. The Zn cation from mono- or polysolute-solutions was retained in higher amount than Cd and Pb cations in similar solution types by bentonite. The retentions were effective up to 450 °C calcined bentonite, after that, the retention capacity decreased in concordance with dehydroxylation of the structure of clay minerals.

  20. Experimental study on oxidative decomposition of nitrobenzene in aqueous solution by honeycomb ceramic-catalyzed ozonation

    Institute of Scientific and Technical Information of China (English)

    Lei ZHAO; Jun MA; Zhizhong SUN; Zhengqian LIU; Yixin YANG

    2008-01-01

    The ozonation of nitrobenzene in aqueous solu-tion was carried out in a semi-batch reactor to investigate the degradation efficiency, the effect factors, and the reaction mechanism, where honeycomb ceramic was used as a cata-lyst. The presence of honeycomb ceramic could improve the degradation rate of nitrobenzene by 15.46% compared to the results ofozonation alone. Under the conditions of this exper-iment, the degradation rate of honeycomb ceramic-catalyzed ozonation increased by 12.94% with the increase of the amount of catalyst from 1 to 5 blocks. The degradation rates all increased greatly with the increase of temperature and pH of the solution in the processes of honeycomb ceramic-catalyzed ozonation and ozonation alone. But, when the pH of the solution increased to 9.50, the advantage of the honey-comb ceramic-catalyzed ozonation process would be lost. The experimental findings indicated that in the processes of ozonation alone and honeycomb ceramic-catalyzed ozona-tion, nitrobenzene was primarily oxidized by·OH free radical in aqueous solution. The adsorption of nitrobenzene was too limited to have an important influence on the degradation rate of nitrobenzene. With the same total dosage of applied ozone, the multiple step addition of ozone showed much higher removal efficiency than that obtained by one step in the two processes.