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Sample records for temperature aqueous solutions

  1. On the calculation of the electrolyte aqueous solution freezing temperature

    International Nuclear Information System (INIS)

    Ptitsyn, A.B.

    1995-01-01

    Analytical expression of the dependence of freezing temperature of electrolyte (CdCl 2 , CdSO 4 , BeSO 4 ) aqueous solutions on their composition was found. Three different methods were suggested were suggested for calculation of water activity in multicomponent solution. It was established that sublinear extrapolation of freezing temperature of salt aqueous solutions was possible not up to -5 deg C, but up to -15 deg C, independently of their composition. 6 refs.; 2 figs

  2. Transitions in aqueous solutions of sucrose at subzero temperatures

    Czech Academy of Sciences Publication Activity Database

    Sikora, Antonín; Dupanov, V. O.; Kratochvíl, Jaroslav; Zámečník, J.

    2007-01-01

    Roč. 46, č. 1 (2007), s. 71-85 ISSN 0022-2348 R&D Projects: GA ČR(CZ) GA522/04/0384 Institutional research plan: CEZ:AV0Z40500505 Keywords : aqueous sucrose solutions * subzero temperature * glass transitions Subject RIV: BJ - Thermodynamics Impact factor: 0.809, year: 2007

  3. Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Cochrane, T. T., E-mail: agteca@hotmail.com [AGTECA S.A., 230 Oceanbeach Road, Mount Maunganui, Tauranga 3116 (New Zealand); Cochrane, T. A., E-mail: tom.cochrane@canterbury.ac.nz [Department of Civil and Natural Resources Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand)

    2016-01-15

    Purpose: To demonstrate that the authors’ new “aqueous solution vs pure water” equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. Methods: The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of “free” water molecules per unit volume of solution, “N{sub f},” and (c) the “t” factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate N{sub f} was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors’ equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. Results: The provisional equations formulated to calculate N{sub f}, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of N{sub f

  4. Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures

    International Nuclear Information System (INIS)

    Cochrane, T. T.; Cochrane, T. A.

    2016-01-01

    Purpose: To demonstrate that the authors’ new “aqueous solution vs pure water” equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. Methods: The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of “free” water molecules per unit volume of solution, “N f ,” and (c) the “t” factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate N f was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors’ equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. Results: The provisional equations formulated to calculate N f , the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of N f using recorded

  5. Isopiestic studies of aqueous solutions at elevated temperatures

    International Nuclear Information System (INIS)

    Holmes, H.F.; Mesmer, R.E.

    1981-01-01

    Isopiestic measurements have been made on SrCl 2 (aq) and BaCl 2 (aq) over the temperature range 382.96 to 473.61 K with NaCl(aq) as the reference solution for the calculation of osmotic coefficients. The molalities corresponded to NaCl(aq) molalities ranging from 0.6 to 6.5 mol kg -1 . An ion-interaction model was fitted to the osmotic coefficients of SrCl 2 (aq) and BaCl 2 (aq) with a standard deviation of fit (in the osmotic coefficient) ranging from 0.0007 to 0.0048. Parameters derived from the fit were used to calculate the activity coefficients. The osmotic and activity coefficients decrease with increasing temperature and become less dependent on molality. Previous isopiestic results between 318 and 394 K agree with the present study. Activity coefficients from electrochemical measurements between 283.15 and 343.15 K are not consistent with the isopiestic results. (author)

  6. Effect of temperature on the behavior of surface properties of alcohols in aqueous solution

    International Nuclear Information System (INIS)

    Romero, Carmen M.; Jimenez, Eulogio; Suarez, Felipe

    2009-01-01

    The influence of temperature on the behavior of surface properties of aqueous solutions has often been used to obtain information about solute structural effects on water. In this work, we present experimental results for surface tension of aqueous solutions of n-pentanol, n-hexanol, n-heptanol, and n-octanol at T = (283.15, 288.15, 293.15, 298.15, 303.15, and 308.15) K at several concentrations. The results were used to evaluate the limiting experimental slopes of surface tension with respect to mole fraction and the hydrophobicity constant of the Connors model at each temperature. The thermodynamic behavior of aqueous alcohol solutions is discussed in terms of the effect of the hydrocarbon chain on water structure. The temperature dependence of the limiting slopes of surface tension with respect to mole fraction, as well as the hydrophobicity constant derived from surface measurements, is interpreted in terms of alcohol hydration

  7. Isopiestic studies of aqueous solutions at elevated temperatures

    International Nuclear Information System (INIS)

    Holmes, H.F.; Mesmer, R.E.

    1981-01-01

    Isopiestic measurements have been made for LiCl(aq) and CsCl(aq) over the temperature range 382.96 to 473.61 K. NcCl(aq) served as the reference electrolyte for the calculation of osmotic coefficients and the molalities ranged from about 0.6 to 6 mol kg -1 , for NaCl(aq). An ion-interaction model gave an excellent fit to the experimental osmotic coefficients with a standard error of fit ranging from 0.0004 to 0.0016 in the osmotic coefficient. Parameters obtained from the fit were used to calculate the activity coefficients. The osmotic and activity coefficients both decreased with increasing temperature over this temperature range. LiCl(aq) is somewhat unusual among the alkali-metal chlorides in that the osmotic (and activity) coefficient is much more dependent on molality at the higher molalities and there is no maximum between 273.15 and 373.15 K in the osmotic coefficient as a function of temperature. For both LiCl(aq) and CsCl(aq) there is an excellent correlation between the isopiestic results and the vapor pressures of Lindsay and Liu. Existing electrochemical results between 283.15 and 343.15 K are consistent with the calculated activity coefficients for CsCl(aq). (author)

  8. Corrosion behaviour of Alloy 800 in high temperature aqueous solutions: Electrochemical studies

    International Nuclear Information System (INIS)

    Olmedo, A.M.; Villegas, M.; Alvarez, M.G.

    1996-01-01

    The anodic behaviour and passivity breakdown of Alloy 800 in aqueous solutions of sodium chloride, sodium sulphate and sodium bicarbonate were studied by electrochemical techniques in the temperature range from 60 C to 280 C. The pitting resistance and pitting morphology of the alloy in chloride plus sulphate and chloride plus bicarbonate mixtures, at 60 C and 280 C, were also examined. Increasing bicarbonate or sulphate additions to chloride solutions shift the characteristic pitting potential of Alloy 800 to higher values, both at low and high temperatures. Changes in pitting morphology were observed in sulphate containing solutions while the morphology of the attack found in bicarbonate containing solutions was similar to that in pure chloride solutions. Finally, no localized or substantial generalized corrosion was detected in pure sulphate or bicarbonate solutions at any temperature. (orig.)

  9. Features of the temperature and concentration dependences of the contraction of aqueous solutions of ethanol

    Science.gov (United States)

    Gotsul'skii, V. Ya.; Malomuzh, N. P.; Chechko, V. E.

    2013-10-01

    Temperature and concentration dependences of the contraction of aqueous solutions of ethanol are studied. It is shown that at a molar concentration of x = 0.077, the curves of the temperature dependences of contraction intersect at one point that is interpreted as the singular point of a water-ethanol solution. To reveal the role of intermolecular forces of attraction, our results are compared to the behavior of contraction for hard-sphere mixtures with varying ratios of their radii. The change in the total volume of the solution induced by the formation of hydrogen bonds is analyzed in detail.

  10. Aqueous solutions of proline and NaCl studied by differential scanning calorimetry at subzero temperatures

    DEFF Research Database (Denmark)

    Rasmussen, Peter Have; Jørgensen, Bo; Nielsen, Jette

    1997-01-01

    was not observed during freezing or melting which shows that proline has the ability to stay in solution at subzero temperatures. Samples containing proline-NaCl-water were also investigated by DSC and it was shown that the solubility of proline is maintained in aqueous salt solutions at temperatures as low as -60....../w) indicating a high water solubility of proline at subzero temperatures. No glass transition was observed within the concentration range 0.9-40.1 wt% (w/w), neither at a low scanning rate of 2.5 degrees C/min nor at a higher scanning rate of 10 degrees C/min. Eutectic crystallization of proline...

  11. 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.

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

    Science.gov (United States)

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

    2016-06-09

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

  13. Low temperature growth and optical properties of ZnO nanowires using an aqueous solution method.

    Science.gov (United States)

    Chu, Manh-Hung; Lee, Joon-Hyung; Kim, Jeong-Joo; Kim, Kyeong-Won; Norton, D P; Heo, Young-Woo

    2012-02-01

    ZnO nanowires were grown on indium tin oxide (ITO) coated glass substrates at a low temperature of 90 degrees C using an aqueous solution method. The ZnO seeds were coated on the ITO thin films by using a spin coater. ZnO nanowires were formed in an aqueous solution containing zinc nitrate hexahydrate (Zn(NO3)2 x 6H2O) and hexamethylenetetramine (C6H12N4). The pH value and concentration of the solution play an important role in the growth and morphologies of ZnO nanowires. The size of ZnO naonowires increased as the concentration of the solution increased. It was formed with a top surface of hexagonal and tapered shape at low and high pH values respectively. Additionally, the single crystalline structure and optical property of the ZnO nanowires were investigated using high-resolution transmission electron microscopy and photoluminescence spectroscopy.

  14. Temperature-dependent chemical shift in the aqueous solution of xenon

    OpenAIRE

    Peuravaara, P. (Petri)

    2017-01-01

    Abstract At standard pressure, the chemical shift of Xe-129 in an aqueous solution of xenon exhibits a maximum as a function of temperature at 311 K, which is in contrast to the well-known density maximum of water at 277 K. In the present work, this phenomenon is studied by means of a molecular dynamics simulation, where the xenon chemical shift is computed quantum-chemically for snapshots of the simulation trajectory. Also...

  15. Effects of Temperature on Aggregation Kinetics of Graphene Oxide in Aqueous Solutions

    Science.gov (United States)

    Wang, M.; Gao, B.; Tang, D.; Sun, H.; Yin, X.; Yu, C.

    2017-12-01

    Temperature may play an important role in controlling graphene oxide (GO) stability in aqueous solutions, but it has been overlooked in the literature. In this work, laboratory experiments were conducted to determine the effects of temperature (6, 25, and 40 °C) on GO aggregation kinetics under different combinations of ionic strength, cation type, humic acid (HA) concentration by monitoring GO hydrodynamic radii and attachment efficiencies. The results showed that, without HA, temperature increase promoted GO aggregation in both monovalent (Na+ and K+) and divalent (Ca2+) solutions. This phenomenon might be caused by multiple processes including enhanced collision frequency, enhanced cation dehydration, and reduced electrostatic repulsion. The presence of HA introduced steric repulsion forces that enhanced GO stability and temperature showed different effects GO aggregation kinetics in monovalent and divalent electrolytes. In monovalent electrolytes, cold temperature diminished the steric repulsion of HA-coated GO. As a result, the fastest increasing rate of GO hydrodynamic radius and the smallest critical coagulation concentration value appeared at the lowest temperature (6 °C). Conversely, in divalent electrolyte solutions with HA, high temperate favored GO aggregation, probably because the interactions between Ca2+ and HA increased with temperature resulting in lower HA coating on GO. Findings of this work emphasized the importance of temperature as well as solution chemistry on the stability and fate of GO nanoparticles in aquatic environment.

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

    International Nuclear Information System (INIS)

    Gorbovitskaya, T.; Tiliks, J.

    1996-01-01

    In order to investigate the radiolysis of iodine containing aqueous solutions a flow type facility - Iodine Thermoradiation Facility (ITF) has been designed. It has a possibility to irradiate aqueous solutions in the steel vessel with 60 Co γ-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 ox (I 2 + I 3 - + HOI), IO 3 - , H 2 O 2 was studied in 10 -5 - 10 -3 mol/dm 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. Under similar conditions, some experiments in glass ampoules were also performed. The steady-state concentrations of I ox and IO 3 - 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 ox does not depend essentially on the iodide ion initial concentration. Molecular iodine (I 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 -3 and 10 -4 M CsI solutions was observed at the temperature about 350 K. The volatility of 10 -5 M solutions gradually decreased with increasing temperature. The experimental data were explained on the base of the hypothesis that the reaction between I 2 and radiolytic H 2 O 2 was the limit one determining the temperature dependence of I ox and IO 3 - steady-state concentrations. Its activation energy was estimated to be 27,5 kcal.mol -1 . The temperature dependence for reaction (IO - + H 2 O 2 ) was also estimated. (author) 8 figs., 1 tab., 17 refs

  17. Solvation behaviour of biologically active compounds in aqueous solutions of antibacterial drug amoxicillin at different temperatures

    International Nuclear Information System (INIS)

    Singla, Meenu; Kumar, Harsh; Jindal, Rajeev

    2014-01-01

    Highlights: • Densities and speeds of sound of amino acids in aqueous amoxicillin solutions. • Partial molar volumes and compressibility of transfer. • Group contribution have been calculated. • (Ion + hydrophilic) and (hydrophilic + hydrophilic) interactions are present. • Pair-wise interactions are dominant in the mixtures. - Abstract: The interactions of glycine (Gly), L-alanine (Ala), L-valine (Val) and L-Leucine (Leu) with drug amoxicillin (AMX) as a function of temperature have been investigated by combination of volumetric and acoustic measurements. Densities and speeds of sound of amino acids in aqueous solutions of amoxicillin have been measured at T = (305.15, 310.15 and 315.15) K and atmospheric pressure. The apparent molar volume (V ϕ ), the partial molar volume (V ϕ 0 ) and standard partial molar volumes of transfer (ΔV ϕ 0 ) for amino acids from water to aqueous amoxicillin solutions have been calculated from density data. Group contributions of amino acids to partial molar volume were determined. Partial molar isentropic compression (κ ϕ,s ) and partial molar isentropic compression of transfer (Δκ ϕ,S 0 ) have been calculated from speed of sound data. The pair and triplet interaction coefficient have been calculated from both the properties. The results have been explained based on competing patterns of interactions of co-solvents and the solute

  18. Temperature and concentration calibration of aqueous polyvinylpyrrolidone (PVP solutions for isotropic diffusion MRI phantoms.

    Directory of Open Access Journals (Sweden)

    Friedrich Wagner

    Full Text Available To use the "apparent diffusion coefficient" (Dapp as a quantitative imaging parameter, well-suited test fluids are essential. In this study, the previously proposed aqueous solutions of polyvinylpyrrolidone (PVP were examined and temperature calibrations were obtained. For example, at a temperature of 20°C, Dapp ranged from 1.594 (95% CI: 1.593, 1.595 μm2/ms to 0.3326 (95% CI: 0. 3304, 0.3348 μm2/ms for PVP-concentrations ranging from 10% (w/w to 50% (w/w using K30 polymer lengths. The temperature dependence of Dapp was found to be so strong that a negligence seems not advisable. The temperature dependence is descriptively modelled by an exponential function exp(c2 (T - 20°C and the determined c2 values are reported, which can be used for temperature calibration. For example, we find the value 0.02952 K-1 for 30% (w/w PVP-concentration and K30 polymer length. In general, aqueous PVP solutions were found to be suitable to produce easily applicable and reliable Dapp-phantoms.

  19. Chemistry in high temperature aqueous solutions application to the power industry

    International Nuclear Information System (INIS)

    Cohen, P.

    1990-01-01

    The power industry utilizes water (aqueous solutions) for two main functions: as a medium for heat transfer and transport and as a thermodynamic working fluid. These functions are performed in systems fabricated from a wide variety of materials, over a wide range of thermal and hydraulic conditions, and at medium temperatures and densities which determine the significant chemical properties. The major chemical interest is in the concentrated solutions derived from the dilute working fluid at selected sites defined by the physical arrangement and temperature and in their consequential effects on heat transfer and corrosion. Examples of these sites for typical fossil fired and nuclear steam generating equipment are described, as well as the extent and limit of the concentration process. The history of steam power plant water chemistry is discussed from the point of view of the chemical processes involved. The period covered is from the 1920s to the present state of the art, which is a major application of the subject of this symposium--chemistry in high temperature aqueous solution

  20. OSMOTIC COEFFICIENTS, SOLUBILITIES, AND DELIQUESCENCE RELATIONS IN MIXED AQUEOUS SALT SOLUTIONS AT ELEVATED TEMPERATURE

    International Nuclear Information System (INIS)

    M.S. Gruszkiewicz; D.A. Palmer

    2006-01-01

    While thermodynamic properties of pure aqueous electrolytes are relatively well known at ambient temperature, there are far fewer data for binary systems extending to elevated temperatures and high concentrations. There is no general theoretically sound basis for prediction of the temperature dependence of ionic activities, and consequently temperature extrapolations based on ambient temperature data and empirical equations are uncertain and require empirical verification. Thermodynamic properties of mixed brines in a wide range of concentrations would enhance the understanding and precise modeling of the effects of deliquescence of initially dry solids in humid air in geological environments and in modeling the composition of waters during heating, cooling, evaporation or condensation processes. These conditions are of interest in the analysis of waters on metal surfaces at the proposed radioactive waste repository at Yucca Mountain, Nevada. The results obtained in this project will be useful for modeling the long-term evolution of the chemical environment, and this in turn is useful for the analysis of the corrosion of waste packages. In particular, there are few reliable experimental data available on the relationship between relative humidity and composition that reveals the eutonic points of the mixtures and the mixture deliquescence RH. The deliquescence RH for multicomponent mixtures is lower than that of pure component or binary solutions, but is not easy to predict quantitatively since the solutions are highly nonideal. In this work we used the ORNL low-temperature and high-temperature isopiestic facilities, capable of precise measurements of vapor pressure between ambient temperature and 250 C for determination of not only osmotic coefficients, but also solubilities and deliquescence points of aqueous mixed solutions in a range of temperatures. In addition to standard solutions of CaCl 2 , LiCl, and NaCl used as references, precise direct

  1. Temperature dependence of the surface enhanced raman spectroelectrochemistry of iron in aqueous solutions.

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, L. J.; Melendres, C. A.; Chemical Engineering

    1996-06-01

    The effect of temperature on the composition of the corrosion film on iron in aqueous sodium hydroxide and borate solutions was investigated using surface enhanced Raman spectroelectrochemistry (SERS). Fe(OH){sub 2} and Fe{sub 3}O{sub 4} were observed in the prepassivation region, while Fe{sub 3}O{sub 4} and FeOOH accounted for most of the passivated film at 25, 60 and 95 C. Fe(OH){sub 2} was found to be a stable component of the corrosion film on iron at 95 C, which is contrary to recently published theoretical calculations.

  2. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Hybrid temperature effect on a quartz crystal microbalance resonator in aqueous solutions

    International Nuclear Information System (INIS)

    Li Qiang; Gu Yu; Xie Bin

    2017-01-01

    The quartz crystal microbalance (QCM) is an important tool that can sense nanogram changes in mass. The hybrid temperature effect on a QCM resonator in aqueous solutions leads to unconvincing detection results. Control of the temperature effect is one of the keys when using the QCM for high precision measurements. Based on the Sauerbrey’s and Kanazawa’s theories, we proposed a method for enhancing the accuracy of the QCM measurement, which takes into account not only the thermal variations of viscosity and density but also the thermal behavior of the QCM resonator. We presented an improved Sauerbrey equation that can be used to effectively compensate the drift of the QCM resonator. These results will play a significant role when applying the QCM at the room temperature. (paper)

  4. Studies on the Solute Solvent Interaction of Nimesulide in Aqueous Solutions of Hydrotropic Agents at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Chandravir S. Solanki

    2010-01-01

    Full Text Available The present study deals with experiments so as to highlight the solute (drug nimesulide - solvent(water interactions and related modifications in case of the presence of hydrotropic agents at different temperatures T(=298.15 to 313.15K. Density and viscosity values of nimesulide have been determined in water in (0.1, 0.2, 0.4, 0.6, 0.8, 1 and 2 mol dm-3 aqueous solutions of hydrotropic agents (sodium benzoate, sodium salicylate, sodium bromide and nicotinamide at temperatures 298.15, 303.15, 308.15 and 313.15 K where as the solubility was studied at 308.15 K. From the density values, the limiting partial molar volumes and expansibilities have been calculated. The experimental viscosity values have been analyzed in terms of jones-dole equation and on the basis of transition theory for relative viscosity.

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

    Science.gov (United States)

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

    2005-01-01

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

  6. Temperature dependent absorption spectra of Br(-), Br2(•-), and Br3(-) in aqueous solutions.

    Science.gov (United States)

    Lin, Mingzhang; Archirel, Pierre; Van-Oanh, Nguyen Thi; Muroya, Yusa; Fu, Haiying; Yan, Yu; Nagaishi, Ryuji; Kumagai, Yuta; Katsumura, Yosuke; Mostafavi, Mehran

    2011-05-05

    The absorption spectra of Br(2)(•-) and Br(3)(-) in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350 °C, respectively. Br(2)(•-) can be observed even in supercritical conditions, showing that this species could be used as a probe in pulse radiolysis at high temperature and even under supercritical conditions. The weak temperature effect on the absorption spectra of Br(2)(•-) and Br(3)(-) is because, in these two systems, the transition occurs between two valence states; for example, for Br(2)(-) we have (2)Σ(u) → (2)Σ(g) transition. These valence transitions involve no diffuse final state. However, the absorption band of Br(-) undergoes an important red shift to longer wavelengths. We performed classical dynamics of hydrated Br(-) system at 20 and 300 °C under pressure of 25 MPa. The radial distribution functions (rdf's) show that the strong temperature increase (from 20 to 300 °C) does not change the radius of the solvent first shell. On the other hand, it shifts dramatically (by 1 Å) the second maximum of the Br-O rdf and introduces much disorder. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br(-) at two temperatures and we compared the results with the experimental data.

  7. Uptake of hypobromous acid (HOBr by aqueous sulfuric acid solutions: low-temperature solubility and reaction

    Directory of Open Access Journals (Sweden)

    L. T. Iraci

    2005-01-01

    Full Text Available Hypobromous acid (HOBr is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45-70wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201-252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H*=104-107mol L-1atm-1. H* is inversely dependent on temperature, with ΔH=-45.0±5.4 kJ mol-1 and ΔS=-101±24 J mol-1K-1 for 55-70wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into 55-70wt% H2SO4, the solubility is described by log H*=(2349±280/T-(5.27±1.24. At temperatures colder than ~213K, the solubility of HOBr in 45wt% H2SO4 is at least a factor of five larger than in 70wt% H2SO4, with log H*=(3665±270/T-(10.63±1.23. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Upon uptake of HOBr into aqueous sulfuric acid in the presence of other brominated gases, particularly for 70wt% H2SO4 solution, our measurements demonstrate chemical reaction of HOBr followed by evolution of gaseous products including Br2O and Br2.

  8. Apparent molal volumes of HMT and TATD in aqueous solutions around the temperature of maximum density of water

    International Nuclear Information System (INIS)

    Clavijo Penagos, J.A.; Blanco, L.H.

    2012-01-01

    Highlights: ►V φ for HMT and TATD in aqueous solutions around the temperature of maximum density of water are reported. ► V φ is linear in m form m = 0.025 for all the aqueous solutions investigated. ► Variation of V ¯ 2 ∞ with T obeys a second grade polynomial trend. ► The solutes are classified as structure breakers according to Hepler’s criterion. - Abstract: Apparent molal volumes V φ have been determined from density measurements for several aqueous solutions of 1,3,5,7-tetraazatricyclo[3.3.1.1(3,7)]decane (HMT) and 1,3,6,8-tetraazatricyclo[4.4.1.1(3,8)]dodecane (TATD) at T = (275.15, 275.65, 276.15, 276.65, 277.15, 277.65 and 278.15) K as function of composition. The infinite dilution partial molar volumes of solutes in aqueous solution are evaluated through extrapolation. Interactions of the solutes with water are discussed in terms of the effect of the temperature on the volumetric properties and the structure of the solutes. The results are interpreted in terms of water structure-breaking or structure forming character of the solutes.

  9. Effect of temperature on the dilution enthalpies of α,ω-amino acids in aqueous solutions

    International Nuclear Information System (INIS)

    Romero, C.M.; Cadena, J.C.; Lamprecht, I.

    2011-01-01

    Highlights: → The dilution of 3-amino propanoic acid, 4-amino butanoic acid, 5-amino pentanoic acid, and 6-amino hexanoic acid in water is an exothermic process at T = (293.15, 298.15, 303.15, and 308.15) K. → The limiting experimental slopes of the enthalpies of dilution with respect to the molality change Δm, are negative suggesting that the solutes interact with water primarily through their alkyl groups. → The value of the pairwise coefficient is positive at the temperatures considered, and the magnitude increases linearly with the number of methylene groups. → The comparison between the pairwise interaction coefficients for α,ω-amino acids and α-amino acids shows that the change in the enthalpic interaction coefficient is related to the relative position of the polar groups. - Abstract: Dilution enthalpies of aqueous solutions of 3-amino propanoic acid, 4-amino butanoic acid, 5-amino pentanoic acid, and 6-amino hexanoic acid were determined at T = (293.15, 298.15, 303.15, and 308.15) K using an LKB flow microcalorimeter. The homotactic interaction coefficients were obtained according to the McMillan-Mayer theory from the experimental data. For all the systems studied, the dilution of α,ω-amino acids in water is an exothermic process; the pair coefficients have positive values which increases with chain length. The obtained values of the interaction coefficients are interpreted in terms of solute-solvent and solute-solute interactions and are used as indicative of hydrophobic behavior of the amino acid studied.

  10. NMR investigations of temperature-induced phase transition in aqueous polymer solutions

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří

    2011-01-01

    Roč. 305, č. 1 (2011), s. 18-25 ISSN 1022-1360 R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Keywords : aqueous polymer solutions * cooperative effects * NMR Subject RIV: CD - Macromolecular Chemistry

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

    International Nuclear Information System (INIS)

    Spencer, B.B.

    1991-01-01

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

  12. The oxidation and hydriding of zircaloy fuel cladding in high temperature aqueous solutions

    Science.gov (United States)

    Chen, Yingzi

    at the metal/film interface control the rate of film growth when the potential is displaced in the positive direction, whereas the kinetics of dissolution of the barrier layer at the barrier layer/solution interface control the rate of passive film thinning when the potential is stepped in the negative direction. Both the growth rate and dissolution rate of the passive films formed in the hydrogenated solution are lower than that formed in the dehydrogenated solution. In addition, the effects of second phase particles (SPPs) on the electrochemistry of passive zirconium in the hydrogenated, high temperature aqueous solutions are examined by using different heat-treated Zircaloy-4 samples; i.e., as-received, beta-quenched, and alpha-annealed. Optical microscopy with polarized light and scanning electron microscopy (SEM) were used to characterize the microstructure and determine the size and density of the SPPs. The average size of the second phase particles in the Zircaloy-4 samples was in the sequence of beta-quenched beta-quenched sample has the highest corrosion resistance, while the a-annealed sample has the lowest. It is also evident that the second phase particles play an important role in determining the electronic character of a passive film, as demonstrated by Mott-Schottky analysis. The second phase particles may cause short circuits in the electrical path across the passive film, which would explain the effect of the size and the density of the SPPs, and hence heat treatment, on the corrosion properties of passive Zircaloy-4.

  13. Temperature-induced phase transition in aqueous solutions of poly(N-isopropylacrylamide)-based block copolymer

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Dybal, Jiří

    2016-01-01

    Roč. 369, č. 1 (2016), s. 92-96 ISSN 1022-1360. [International IUPAC Conference on Polymer-Solvent Complexes and Intercalates /11./ - POLYSOLVAT-11. Kolkata, 27.01.2016-30.01.2016] R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * block copolymers * micelles Subject RIV: CD - Macromolecular Chemistry

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

    Science.gov (United States)

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

    2016-04-01

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

  15. Volumetric behaviour of amino acids and their group contributions in aqueous lactose solutions at different temperatures

    International Nuclear Information System (INIS)

    Pal, Amalendu; Chauhan, Nalin

    2011-01-01

    Densities, ρ, for glycine, L-alanine, L-valine, and L-leucine [(0.05 to 0.30) m] in aqueous lactose solutions ranging from pure water to 6 mass% lactose were determined at T = (293.15, 298.15, 303.15, and 308.15) K. The density was used to compute apparent molar volume, V φ , partial molar volume at infinite dilution, V φ o , and experimental slope, S V were obtained and interpreted in terms of solute-solvent and solute-solute interactions. These data were used to calculate the (∂V φ 0 /∂T) P values. The partial molar volume of transfer, ΔV φ 0 from water to aqueous lactose solutions at infinite dilution has also been calculated. In addition to this, the linear correlation of V φ 0 with number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of NH 3 + COO - , and CH 2 groups to V φ 0 .

  16. Volumetric behaviour of amino acids and their group contributions in aqueous lactose solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Amalendu, E-mail: palchem@sify.co [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India); Chauhan, Nalin [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India)

    2011-02-15

    Densities, {rho}, for glycine, L-alanine, L-valine, and L-leucine [(0.05 to 0.30) m] in aqueous lactose solutions ranging from pure water to 6 mass% lactose were determined at T = (293.15, 298.15, 303.15, and 308.15) K. The density was used to compute apparent molar volume, V{sub {phi}}, partial molar volume at infinite dilution, V{sub {phi}}{sup o}, and experimental slope, S{sub V} were obtained and interpreted in terms of solute-solvent and solute-solute interactions. These data were used to calculate the ({partial_derivative}V{sub {phi}}{sup 0}/{partial_derivative}T){sub P} values. The partial molar volume of transfer, {Delta}V{sub {phi}}{sup 0} from water to aqueous lactose solutions at infinite dilution has also been calculated. In addition to this, the linear correlation of V{sub {phi}}{sup 0} with number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of NH{sub 3}{sup +}COO{sup -}, and CH{sub 2} groups to V{sub {phi}}{sup 0}.

  17. Removal of the Pesticide Pymetrozine from Aqueous Solution by Biochar Produced from Brewer's Spent Grain at Different Pyrolytic Temperatures

    OpenAIRE

    Xinguo Xi; Jinlong Yan; Guixiang Quan; Liqiang Cui

    2014-01-01

    Biochar (BC) produced from brewer's spent grain (BSG) via slow pyrolysis at 300, 400, 500, 600, and 700 °C was characterized and investigated as an adsorbent for the removal of the pesticide pymetrozine from aqueous solution. Batch BSG BCs adsorption experiments were carried out under various conditions (such as pH, pymetrozine concentration, and BC dosage) to adsorb the pymetrozine. The BSG BCs adsorption pymetrozine capacities were increased by 21.4% to 55.5% under pyrolysis temperatures of...

  18. Degeneration of amyloid-ß fibrils caused by exposure to low-temperature atmospheric-pressure plasma in aqueous solution

    OpenAIRE

    Takai, Eisuke; Ohashi, Gai; Yoshida, Tomonori; Sörgjerd, Karin Margareta; Zako, Tamotsu; Maeda, Mizuo; Kitano, Katsuhisa; Shiraki, Kentaro

    2014-01-01

    Low-temperature atmospheric-pressure plasma was applied to degenerate amyloid-ß (Aß) fibrils, which are a major component of neuritic plaque associated with Alzheimer's disease (AD). We showed that an Aß fibril exposed to a low-frequency (LF) plasma jet in aqueous solution retained its morphology, molecular weight, and cytotoxicity, but, intriguingly, decreased in protease resistance and ß-sheet content. These results suggested that an LF plasma jet could be utilized for the treatment of AD t...

  19. Effect of temperature on solvation behaviour of diclofenac sodium salt in aqueous glycine and L-proline solutions

    International Nuclear Information System (INIS)

    Ryshetti, Suresh; Gardas, Ramesh L; Tangeda, Savitha Jyostna

    2015-01-01

    Highlights: • Solvation behaviour of diclofenac drug studied in aqueous solutions. • Density and speed of sound of drug in aq. glycine and L-proline are measured. • Hydrophobic nature of diclofenac sodium salt is studied. • Effect of temperature on solvation of diclofenac sodium salt is analysed. - Abstract: Apparent molar volume (V 2,ϕ ) and apparent molar isentropic compressibility (K s,2,ϕ ) of diclofenac sodium salt (DSS) drug within the concentration range of (0.001 to 0.008) mol · kg −1 in (0.01, 0.03 and 0.05) mol · kg −1 aqueous glycine and L-proline solutions are computed from the experimental density (ρ) and speed of sound (u) values at T = (293.15 to 313.15) K and atmospheric pressure. Derived parameters such as partial molar properties, transfer partial molar properties, hydration numbers and Hepler’s constant are computed from the data of V 2,ϕ and K s,2,ϕ . These parameters have been used to understand the effect of temperature on interactions between DSS drug and aqueous glycine/L-proline solution. Furthermore, the structure making and breaking ability of DSS drug in probed solutions are analysed at experimental conditions

  20. Ultrasonic speed, densities and viscosities of xylitol in water and in aqueous tyrosine and phenylalanine solutions at different temperatures

    Science.gov (United States)

    Ali, A.; Bidhuri, P.; Uzair, S.

    2014-07-01

    Ultrasonic speed u, densities ρ and viscosities η of xylitol in water and in 0.001 m aqueous l-tyrosine (Tyr) and l-phenylalanine (Phe) have been measured at different temperatures. From the density and ultrasonic speed measurements apparent molar isentropic compression κ_{φ}, apparent molar isentropic compressions at infinite dilution κ_{{S,φ}}0 , experimental slope S K , hydration number n H , transfer partial molar isentropic compressibility Δ_{tr} κ_{{S,φ}}0 of xylitol from water to aqueous Tyr and Phe have been obtained. From the viscosity data, B-coefficient and B-coefficient of transfer Δ tr B of xylitol from water to aqueous Phe and Tyr at different temperatures have also been estimated. Gibbs free energies of activation of viscous flow per mole of solvent Δ μ 1 0# and per mole of solute Δ μ 2 0# have been calculated by using Feakins transition state theory for the studied systems. The calculated parameters have been interpreted in terms of solute-solute and solute-solvent interactions and hydration behavior of xylitol.

  1. Amino acid behavior in aqueous amide solutions: Temperature dependence of the L-phenylalanine–N,N-dimethylformamide interaction

    International Nuclear Information System (INIS)

    Kustov, Andrey V.

    2013-01-01

    Highlights: • Thermodynamics of amino acid solvation in aqueous DMF solutions was studied at 288–318 K. • The pair interaction parameters were compared with those for urea solutions. • For hydrophobic solutes enthalpies and entropies of interaction reveal strong temperature changes. • The relationship between the temperature dependence of solvation and solute–solute interactions was found. - Abstract: We have studied thermodynamics of the L-phenylalanine (Phe) pair interaction with denaturing agents – urea (U) and dimethylformamide (DMF) at 288–318 K. Our study does indicate that enthalpies and entropies of the Phe–U interaction reveal the anomalous temperature dependence which does not occur for DMF solutions. The anomalous Phe behavior in U solutions appears to be closely related to peculiarities of U hydration. One more result is in the fact that for hydrophobic solutes such as L-phenylalanine and substituted amides it is not justified to use the results obtained at 298 K for predicting the solute behavior at physiological temperatures

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

    Science.gov (United States)

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

    2016-01-01

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

  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

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat; Shekaari, Hemayat; Hosseini, Rahim

    2009-01-01

    The alkyl chain length of 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = propyl (C 3 ), hexyl (C 6 ), heptyl (C 7 ), and octyl (C 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 -1 were taken. The values of the compressibilities, expansivity and apparent molar properties for [C 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. Aqueous solutions of calcium ions: hydration numbers and the effect of temperature.

    Science.gov (United States)

    Zavitsas, Andreas A

    2005-11-03

    Hydration numbers of calcium ions are determined from extensive measurements of colligative properties of water solutions of calcium salts. The hydration numbers reported refer to the average number of water molecules that are bound sufficiently strongly to calcium ions so as to be removed from the solvent and become part of the solute. Contrary to common descriptions of deviations from ideal behavior for concentrated solutions, ideal behavior is demonstrated when mole fractions are calculated by taking account of such bound water. Measurements over wide concentration and temperature ranges are used to obtain the effect of temperature on the average hydration number of Ca(2+). Freezing point depression measurements yield a hydration number of 12.0 +/- 0.8. Boiling point elevations yield 6.7 +/- 0.6. Consistent with this, vapor pressure measurements from 0 to 200 degrees C show a gradual decrease in hydration number with increasing temperature, with a value of 5.0 at 200 degrees C.

  5. Conductometric and volumetric study of copper sulphate in aqueous ethanol solutions at different temperatures

    Directory of Open Access Journals (Sweden)

    Esam A. Gomaa

    2017-09-01

    Full Text Available An Anton Par Model 55 densimeter was used to measure the densities of copper sulphate solutions in H2O and EtOH–H2O at 298.15 K, 303.15 K, 308.15 K, and 313.15 K. The acquired information was used to ascertain the apparent molar volumes, limiting partial molar volumes, and transfer partial molar volumes of copper sulphate. These computed parameters were utilized to decipher the solute–solute and solute–solvent interactions of copper sulphate in an aqueous ethanol solution. The ion solvation behavior of copper sulphate in water and aqueous ethanol over the range of 298.15–313.15 K was studied using the electrical conductivity principle. The Kraus–Bray and Shedlovsky models of conductivity were used to analyze the obtained conductance data. From the obtained data, the limiting molar conductance λ°m, association constant KA, energy of activation of the rating process (Ea, and related thermodynamic parameters were determined. The Walden product (λ°mη0 was determined. The standard thermodynamic parameters of association (ΔG°A, ΔH°A were calculated and discussed. Increased ion–solvent and solvent–solvent interactions are indicated by limiting molar conductance values with an increasing amount of ethanol. The negative ΔG°A values indicate that the association processes in all of the studied systems are spontaneous processes. The negative estimation of (ΔH°A demonstrates that the association processes is exothermic in nature.

  6. Determination of Optimal Temperature for Biosorption of Heavy Metal Mixture from Aqueous Solution by Pretreated Biomass of Aspergillus niger

    Directory of Open Access Journals (Sweden)

    Javad Yousefi

    2012-01-01

    Full Text Available Biosorption is a novel technology that uses dead and inactive biomass for removal of heavy metals from aqueous solution. Some parameters such as temperature, contact time, solution pH, initial metal concentration, biosorbent dose and also agitating speed of solution and biosorbent mixing can affect the amount of metal sorption by biosorbent. The aim of this study was to investigate the effects of different treatments of temperatures (25, 35, 45 and 55oC on biosorption of metals mixture in order to determine optimal temperature for more metals removal from aqueous solution. This study uses dead and pretreated biomass of Aspergillus niger with 0.5N NaOH for removal of Zn(II, Co(II and Cd(II. In all temperature treatments and in the case of all of heavy metals, maximum amount of metal sorption and concentration decrease was occurred in first 5 minutes and achieved to equilibrium after 20 minute. The percent of metals sorption show growth trend with temperature increase. Between 4 experimental treatments, 55oC treatment was shown maximum sorption and 25oC was shown minimum sorption amount. The percent of Cr(II sorption was increase from 28.5% in 25oC to 44.7% in 55oC. Also, this increase was from 40% to 58% for Cd(II and from 37.7% to 65.6% for Zn(II. About 60% of increase in sorption by A. niger was due to increase in temperature. Therefore the amount of metals sorption can be increase, only with temperature increase and without any biomass addition.

  7. Corrosion rate of copper in aqueous lithium bromide concentrated solutions at room temperature by immersion tests

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Portero, M.J.; Garcia-Anton, J.; Guinon-Segura, J.L.; Perez-Herranz, V. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)

    2004-07-01

    Concentrated solutions of lithium bromide (LiBr) are widely used in absorption refrigeration and heating systems. However, LiBr solutions can cause serious corrosion problems in structural materials (copper, steels, and other metals) in an absorption plant. The aim of the present work was the study of the corrosion rate of copper in 400 and 700 g/L (4.61 and 8.06 M) LiBr solutions pre-nitrogenous or pre-oxygenated at room temperature by immersion tests. The corroded copper concentration was determined with two techniques: weight-loss method and polarographic method. The corrosion curves of copper in LiBr solutions at room temperature as a function of the exposure time showed a similar tendency, and were fitted to a power function such as: C = kt{sup b}, where C was the corroded copper quantity per unit area (mg/cm{sup 2}), t was the exposure time (h), k was the corrosion coefficient, and b was the time exponent. From the corrosion coefficient values (k) it was deduced that the corrosion rate of copper in LiBr solutions at room temperature followed the order: 400 g/L (bubble of O{sub 2}) > 400 g/L (bubble of N{sub 2}) > 700 g/L (bubble of O{sub 2}) > 700 g/L (bubble of N{sub 2}). (authors)

  8. Hexadecyltrimethylammonium bromide micellization in glycine, diglycine, and triglycine aqueous solutions as a function of surfactant concentration and temperatures

    Science.gov (United States)

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

    2014-06-01

    Micellization behavior of hexadecyltrimethylammonium bromide (HTAB) was investigated conductometrically in aqueous solutions containing 0.02 mol kg-1glycine (Gly), diglycine (Gly-Gly), and triglycine (Gly-Gly-Gly) as a function of surfactant concentration at different temperatures. The critical micelle concentration (CMC) of HTAB exhibits a decreasing trend as the number of carbon atoms increases from Gly to Gly-Gly-Gly, favoring the micelle formation. The values of CMC and the degree of counterion dissociation of the micelles were utilized to evaluate the standard free energy for transferring the surfactant hydrophobic chain out of the solvent to the interior of the micelle, Δ G {HP/○}, free energy associated with the surface contributions, Δ G {S/○}, standard free energy, Δ G {m/○}, enthalpy, Δ H {m/○}, and entropy, Δ S {m/○} of micellization were also calculated. The results show that the micellization of HTAB in aqueous solutions as well as in aqueous Gly/Gly-Gly/Gly-Gly-Gly solutions is primarily governed by the entropy gain due to the transfer of the hydrophobic groups of the surfactant from the solvent to the interior part of the micelle. The CMC obtained by fluorometric method is in close agreement with those obtained conductometrically. Furthermore, decrease in the I 1/ I 3 ratio of pyrene fluorescence intensity suggests the solubilization of the additives by the surfactant micelles and that this solubilization increases as the hydrophobicity increases from Gly to Gly-Gly-Gly.

  9. High-temperature thermodynamic data for species in aqueous solution. Final report

    International Nuclear Information System (INIS)

    Cobble, J.W.; Murray, R.C. Jr.; Turner, P.J.; Chen, K.

    1982-05-01

    This final report summarizes the results of experimental and theoretical research on the high temperature thermodynamic properties of aqueous species important to nuclear reactor water chemistry. Methods of predicting thermodynamic functions are included for electrolytes up to 300 0 C where experimental data are lacking. Data in the literature are evaluated and tables of important equilibrium constants for 78 reactions encountered in corrosion and precipitation in nuclear reactors are listed up to 300 0 C. Finally, tables of free energy functions from 0 to 300 0 C are given for 56 individual species. These data represented form a major compilation resulting from the most advanced experimental and theoretical methods. Illustrations of the use of the tables are given for problems involving pH control, precipitation, and corrosion. 11 figures, 100 tables

  10. Quantitative analysis of the calorimetric parameters associated with the temperature induced aggregation of aqueous solutions of polyoxypropylene

    International Nuclear Information System (INIS)

    Armstrong, Jonathan K.; Chowdhry, Babur Z.; Snowden, Martin J.; Dong, Jingfeng; Leharne, Stephen A.

    2003-01-01

    High sensitivity differential scanning calorimetry (HSDSC)--coupled with the application of a previously outlined thermodynamic model [Patterson et al., Langmuir 13 (1997) 2219]--has been used to the obtain thermodynamic parameters that characterise thermal aggregation in aqueous solutions of polyoxypropylene (POP) of molecular mass 1000 g mol -1 over a range of concentrations (2.5-51.5 g dm -3 ). An important aspect of the derived thermodynamic values, which complements previously reported HSDSC data [Armstrong et al., J. Phys. Chem. 99 (1995) 4590], is the elaboration of heat capacity changes which accompany the aggregation transition. The concentration dependence of the POP thermodynamic data, obtained in this investigation, has been established. These observations provide the means for establishing functional relationships between enthalpy and temperature as well as heat capacity and temperature. The parameters describing the quadratic relationship between enthalpy change associated with aggregation and temperature are in close agreement with those describing the linear relationship between heat capacity change and temperature

  11. Ion pair formation in copper sulfate aqueous solutions at high temperatures

    International Nuclear Information System (INIS)

    Mendez De Leo, Lucila P.; Bianchi, Hugo L.; Fernandez-Prini, Roberto

    2005-01-01

    Ionic association between Cu 2+ (aq) and SO42-(aq) has been studied in the temperature range (298 to 473) K using a spectrophotometric technique. Experiments were designed to minimize the contribution of other protolytic equilibria in solution. The values of the ionic association equilibrium constant at different temperatures and pressures were fitted to an appropriate equation that allows the calculation of the thermodynamic quantities for states close to the saturation line. Using Bjerrum's model for ionic association evidence for two ion pair populations was obtained. The process of ion pairing is discussed and a possibility to reconcile the continuum model (Bjerrum) with molecular simulation results is suggested

  12. On-line monitoring of resistance of aqueous solutions at high temperature

    International Nuclear Information System (INIS)

    Hu Shilin; Zhang Pingzhu; Shang Weiguo

    1999-01-01

    The coulostatic measurement is a fast speed electrochemical test method. By this technology, analyzing Δ E(t)- T curves recorded under coulostatic perturbation, the solution resistance R l , resistance of coated film R f , capacity of coated film C f , Polarization resistance R p and double layer capacity C d are obtained. The resistance variety of 0.05N KCl is measured from room temperature up to 255 deg. C under saturation steam pressure. (author)

  13. Pyrolysis temperature and steam activation effects on sorption of phosphate on pine sawdust biochars in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Kangyi Lou

    2016-10-01

    Full Text Available Biochar can be used as an adsorbent for phosphate removal in aquatic environments to treat eutrophication problems. Designing biochars that have large phosphate adsorption capacity through altering pyrolysis conditions and applying activation techniques will improve phosphate removal efficiency. In this study, four pine sawdust biochars were produced at 300 and 550 °C with and without steam activation. Batch sorption experiments including isotherm and kinetic studies were conducted to understand how phosphate removal capabilities and adsorption mechanisms of biochars were affected by pyrolysis temperature and steam activation. Our results showed that the steam activation and pyrolysis temperature did not affect phosphate adsorption by the biochars. The four biochars removed <4% of phosphate from the aqueous solution, which were not affected by the pH of the solution and biochar application rate. The repulsion forces between biochar surfaces and phosphate ions were likely the cause of the low adsorption.

  14. Electrochemistry in aqueous solution at high temperature and under pressure: study of nickel in a highly alkaline environment

    International Nuclear Information System (INIS)

    Forestier, Michel

    1981-01-01

    This research thesis reports the study of the corrosion resistance and anodic behaviour of various metals and alloys used in conventional thermal or nuclear power stations, more particularly the case of nickel in a highly alkaline environment (KOH 5 N) which is widely used for hydrogen production by water electrolysis. The author studied the influence of temperature and pressure on the electrochemical behaviour of nickel, and more particularly the first-oxidation kinetics. The report discusses the physicochemical and thermodynamic properties of aqueous systems at high temperature and under pressure, presents the general techniques of high-temperature electrochemistry, describes the experimental installation, and reports the development of a reference electrode which can operate in those experimental conditions. The author reports the study of the electrochemical behaviour of nickel in alkaline environment and at high temperature, reports a surface analysis performed by Auger spectroscopy, electron spectroscopy for chemical analysis or ESCA, and scanning electronic microscopy, reports the study of the electrochemical behaviour of nickel in a potassium hydroxide solution under normal temperature and pressure, but also in acid environment. Results are interpreted with respect to temperature [fr

  15. An effective route for the room temperature formation of Pd coatings on multiwalled carbon nanotubes in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeong Joon [Dept. of Chemistry, Chungnam National University, Daejeon (Korea, Republic of); Lee, Im Kyu; Song, Jae Hee [Dept. of Chemistry, Sunc hon National University, Suncheon (Korea, Republic of)

    2016-10-15

    We present an easy one-pot synthesis route for the production of palladium nanoparticles and multiwalled carbon nanotubes (MWCNTs)-supported Pd-nanomaterial composites by a simple proton beam irradiation process in an aqueous solution at room temperature. Pristine and surface-modified MWCNTs were used to prepare MWCNT–Pd hybrids. Pd nanoparticles on the surfaces of MWCNTs were produced in situ in an aqueous solution without the addition of any harsh reducing agent. Pristine and thiolated MWCNTs were both densely decorated with spherical Pd nanoparticles and eventually Pd nanowire formation on MWCNTs was realized when reaction times exceeded 60 min. The thicknesses of Pd coatings on MWCNT surfaces were controlled by varying the concentration of MWCNTs in the reaction mixture. MWCNT-Pd composites were characterized by time-resolved transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray spectroscopy, and the results obtained showed that Pd coatings were continuous, and resulted in a MWCNT-supported Pd nanowire structure.

  16. Controllable synthesis of spindle-like ZnO nanostructures by a simple low-temperature aqueous solution route

    Energy Technology Data Exchange (ETDEWEB)

    Lu Hongxia, E-mail: luhx@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhao Yunlong; Yu Xiujun; Chen Deliang [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhang Liwei [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Xinxiang University, Xinxiang 453003 (China); Xu Hongliang; Yang Daoyuan; Wang Hailong [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhang Rui [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450005 (China)

    2011-02-15

    Spindle-like ZnO nanostructures were successfully synthesized through direct precipitation of zinc acetate aqueous solution at 60 deg. C. Phase structure, morphology and microstructure of the products were investigated by X-ray diffraction, TG-DTA, FTIR and field emission scanning electron microscopy (FESEM). Result showed that hexagonal wurtzite structure ZnO nanostructures with about 100 nm in diameter and 100-200 nm in length were obtained. HMTA acted as a soft template in the process and played an important role in the formation of spindle-like ZnO nanostructures. Meanwhile, different morphologies were also obtained by altering synthetic temperature, additional agents and the ratios of Zn{sup 2+}/OH{sup -}. Possible mechanism for the variations of morphology with synthesis parameters was also discussed in this paper.

  17. Electrolytic conductivity and molar heat capacity of two aqueous solutions of ionic liquids at room-temperature: Measurements and correlations

    International Nuclear Information System (INIS)

    Lin Peiyin; Soriano, Allan N.; Leron, Rhoda B.; Li Menghui

    2010-01-01

    As part of our systematic study on physicochemical characterization of ionic liquids, in this work, we report new measurements of electrolytic conductivity and molar heat capacity for aqueous solutions of two 1-ethyl-3-methylimidazolium-based ionic liquids, namely: 1-ethyl-3-methylimidazolium dicyanamide and 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, at normal atmospheric condition and for temperatures up to 353.2 K. The electrolytic conductivity and molar heat capacity were measured by a commercial conductivity meter and a differential scanning calorimeter (DSC), respectively. The estimated experimental uncertainties for the electrolytic conductivity and molar heat capacity measurements were ±1% and ±2%, respectively. The property data are reported as functions of temperature and composition. A modified empirical equation from another researcher was used to correlate the temperature and composition dependence of the our electrolytic conductivity results. An excess molar heat capacity expression derived using a Redlich-Kister type equation was used to represent the temperature and composition dependence of the measured molar heat capacity and calculated excess molar heat capacity of the solvent systems considered. The correlations applied represent the our measurements satisfactorily as shown by an acceptable overall average deviation of 6.4% and 0.1%, respectively, for electrolytic conductivity and molar heat capacity.

  18. Inverted Organic Solar Cells with Low-Temperature Al-Doped-ZnO Electron Transport Layer Processed from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Qianni Zhang

    2018-01-01

    Full Text Available The aqueous-based Zn-ammine complex solutions represent one of the most promising routes to obtain the ZnO electron transport layer (ETL at a low temperature in inverted organic solar cells (OSCs. However, to dope the ZnO film processed from the Zn-ammine complex solutions is difficult since the introduction of metal ions into the Zn-ammine complex is a nontrivial process as ammonium hydroxide tends to precipitate metal salts due to acid-base neutralization reactions. In this paper, we investigate the inverted OSCs with Al-doped-ZnO ETL made by immersion of metallic Al into the Zn-ammine precursor solution. The effects of ZnO layer with different immersion time of Al on film properties and solar cell performance have been studied. The results show that, with the Al-doped-ZnO ETL, an improvement of the device performance could be obtained compared with the device with the un-doped ZnO ETL. The improved device performance is attributed to the enhancement of charge carrier mobility leading to a decreased charge carrier recombination and improved charge collection efficiency. The fabricated thin film transistors with the same ZnO or AZO films confirm the improved electrical characteristics of the Al doped ZnO film.

  19. A Flow-Through High-Pressure Electrical Conductance Cell for Determining of Ion Association of Aqueous Electrolyte Solutions at High Temperature and Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, H.; Ho, P.C.; Palmer, D.A.; Wood, R.H.

    1999-09-12

    A flow-through high-pressure electrical conductance cell was designed and constructed to measure limiting molar conductances and ion association constants of dilute aqueous solutions with high precision at high temperatures and pressures. The basic concept of the cell employs the principle developed at the University of Delaware in 1995, but overall targets higher temperatures (to 600 C) and pressures (to 300 MPa). At present the cell has been tested by measuring aqueous NaCl and LiOH solutions (10{sup {minus}3} to 10{sup {minus}5} mol.kg{sup {minus}1}) to 405 C and 33 MPa with good results.

  20. Calcium and strontium isotope fractionation during precipitation from aqueous solutions as a function of temperature and reaction rate; II. Aragonite

    Science.gov (United States)

    AlKhatib, Mahmoud; Eisenhauer, Anton

    2017-07-01

    In order to study Strontium (Sr) partitioning and isotope fractionation of Sr and Calcium (Ca) in aragonite we performed precipitation experiments decoupling temperature and precipitation rates (R∗, μmol/m2 h) in the interval of about 2.3-4.5 μmol/m2 h. Aragonite is the only pure solid phase precipitated from a stirred solutions exposed to an atmosphere of NH3 and CO2 gases throughout the spontaneous decomposition of (NH4)2CO3. The order of reaction with respect to Ca ions is one and independent of temperature. However, the order of reaction with respect to the dissolved inorganic carbon (DIC) is temperature dependent and decreases from three via two to one as temperature increases from 12.5 and 25.0 to 37.5 °C, respectively. Strontium distribution coefficient (DSr) increases with decreasing temperature. However, R∗ responds differently depending on the initial Sr/Ca concentration and temperature: at 37.5 °C DSr increase as a function of increasing R∗ but decrease for 12.5 and 25 °C. Not seen at 12.5 and 37.5 °C but at 25 °C the DSr-R∗ gradient is also changing sign depending on the initial Sr/Ca ratio. Magnesium (Mg) adsorption coefficient between aragonite and aqueous solution (DMg) decreases with temperature but increases with R∗ in the range of 2.4-3.8 μmol/m2 h. Strontium isotope fractionation (Δ88/86Sraragonite-aq) follows the kinetic type of fractionation and become increasingly negative as a function of R∗ for all temperatures. In contrast Ca isotope fractionation (Δ44/40Caaragonite-aq) shows a different behavior than the Sr isotopes. At low temperatures (12.5 and 25 °C) Ca isotope fractionation (Δ44/40Caaragonite-aq) becomes positive as a function of R∗. In contrast, at 37.5 °C and as a function of increasing R∗ the Δ44/40Caaragonite-aq show a Sr type like behavior and becomes increasingly negative. Concerning both the discrepant behavior of DSr as a function of temperature as well as for the Ca isotope fractionation as a

  1. Effect of temperature on sequestration of Cu (II) from aqueous solution onto turmeric powder

    International Nuclear Information System (INIS)

    Qayoom, A.

    2010-01-01

    In this work effect of temperature on adsorption of Cu(II) onto turmeric powder was investigated in order to understand sequestrating behavior of turmeric powder. Langmuir, Freundlich and D-R equilibrium models were employed and changes in equilibrium parameters with changing temperature have been discussed. Various thermodynamic parameters such as delta H, delta G and delta S have been calculated. It was found that with increase in temperature maximum adsorption capacities of Cu(II) increase which showed that the adsorption of Cu(II) onto turmeric powder is endothermic. delta H and Ea values also confirmed the same trend. Entropy values showed increased in randomness with increasing temperature. Gibbs free energies were non spontaneous at all the temperatures studied. E values were in the range of 2.89-3.53 KJmol /sup -1/, which indicated that adsorption is essentially of physical nature. The value of S is much less than 1 indicating favourable sticking of adsorbate to adsorbent with physiosorption mechanism predominant. (author)

  2. Poisson-Fermi modeling of ion activities in aqueous single and mixed electrolyte solutions at variable temperature

    Science.gov (United States)

    Liu, Jinn-Liang; Eisenberg, Bob

    2018-02-01

    The combinatorial explosion of empirical parameters in tens of thousands presents a tremendous challenge for extended Debye-Hückel models to calculate activity coefficients of aqueous mixtures of the most important salts in chemistry. The explosion of parameters originates from the phenomenological extension of the Debye-Hückel theory that does not take steric and correlation effects of ions and water into account. By contrast, the Poisson-Fermi theory developed in recent years treats ions and water molecules as nonuniform hard spheres of any size with interstitial voids and includes ion-water and ion-ion correlations. We present a Poisson-Fermi model and numerical methods for calculating the individual or mean activity coefficient of electrolyte solutions with any arbitrary number of ionic species in a large range of salt concentrations and temperatures. For each activity-concentration curve, we show that the Poisson-Fermi model requires only three unchanging parameters at most to well fit the corresponding experimental data. The three parameters are associated with the Born radius of the solvation energy of an ion in electrolyte solution that changes with salt concentrations in a highly nonlinear manner.

  3. Combined Effect of Temperature and pKa on the Kinetics of Absorption of Carbon Dioxide in Aqueous Alkanolamine and Carbonate Solutions with Carbonic Anhydrase

    NARCIS (Netherlands)

    Penders-Van Elk, Nathalie J M C; Oversteegen, S. Martijn; Versteeg, Geert F.

    2016-01-01

    In present work the absorption of carbon dioxide in aqueous N-methyldiethanolamine, N,N-dimethylethanolamine, and triisopropanolamine solutions with and without the enzyme carbonic anhydrase has been studied in a stirred cell reactor at temperatures varying between 278 and 313 K, at an alkanolamine

  4. The role of the temperature in the morphology and properties of zinc oxide structures obtained by electrosynthesis in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Jaffry, U.; Mazario, E. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain); Lemus, J. [CICECO – Aveiro Institute of Materials, Chemistry Department, University of Aveiro, 3810-193 Aveiro (Portugal); Rivero, M.; Muñoz-Bonilla, A. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain)

    2016-09-15

    Herein, ZnO micro and nanostructures were synthesized by an electrochemical method in aqueous solution employing NaCl as the electrolyte. Different parameters influencing the synthesis process, i.e. current intensity, reaction time and temperature, were investigated. From this, it was concluded that the productivity of the reaction increases with longer reaction time, whereas the use of higher current intensity augments the specific energy consumption. On the other hand, the increase in temperature seems to exert a negative effect. The characterization of the resulting materials by scanning electron microscopy, X-ray diffraction and thermogravimetric analysis demonstrated that a mixture of Zn(OH){sub 2} and ZnO crystalline structures is formed directly from the synthesis procedure. The content of Zn(OH){sub 2} phase in the sample decreases as the temperature of the synthesis increases, this fact indicates that the low productivity obtained at higher temperatures is related to the nature of the resulting material. Thermal annealing of the samples containing both phases prepared following synthesis allows the phase transformation from Zn(OH){sub 2} to pure ZnO structures. The band gap energies of the ZnO materials were determined by diffuse reflectance measurements according to the Kubelka Munk theory, revealing low values in all the cases which were highly dependent on the size of crystals within the materials. The photocatalytic properties of the pure ZnO samples post calcination were investigated by the decomposition of an organic dye under UV light irradiation. The results show the beneficial photocatalytic properties of the samples that had undergone calcination, these were superior in comparison to those prepared at room temperature which mainly consisted of Zn(OH){sub 2}. - Highlights: • ZnO micro and nanostructures were synthesized by an electrochemical method. • Increasing the applied current and synthesis temperature augments the specific energy

  5. Kinetics of hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solution as a function of temperature near the temperature of maximum density, and the isochoric controversy

    NARCIS (Netherlands)

    Blandamer, MJ; Buurma, NJ; Engberts, JBFN; Reis, JCR; Buurma, Niklaas J.; Reis, João C.R.

    2003-01-01

    At temperatures above and below the temperature of maximum density, TMD, for water at ambient pressure, pairs of temperatures exist at which the molar volumes of water are equal. First-order rate constants for the pH-independent hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solution at pairs of

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

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat; Hosseini, Rahim; Jamehbozorg, Bahman

    2008-01-01

    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

  7. 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.

  8. 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).

  9. Changes in the structure of water in aqueous solutions of acetic acid, depending on concentration and temperature according to densitometry, viscosimetry, and IR spectroscopy data

    Science.gov (United States)

    Masimov, E. A.; Khasanov, G. Sh.; Pashaev, B. G.

    2013-06-01

    The structural features of aqueous solutions of acetic acid are studied by means of viscosimetry, densimetry, and IR spectroscopy within the temperature range of 283.15-333.15 K and a concentration range of 0-80%. The results from our experiments are used to calculate the parameters of viscous flow activation, the structural temperature, the partial molar volume of acetic acid in the solution, the thermal expansion coefficient, and the energies and lengths of the hydrogen bonds between water molecules. The concentration dependences of these parameters are analyzed. Based on the obtained results, we conclude that acetic acid disrupts the structure of water.

  10. Rate constants and temperature effects for reactions of Cl2sm-bullet- with unsaturated alcohols and hydrocarbons in aqueous and acetonitrile/water solutions

    International Nuclear Information System (INIS)

    Padmaja, S.; Neta, P.; Huie, R.E.

    1992-01-01

    Absolute rate constants for reactions of the dichlorine radical anion, Cl 2 sm-bullet- , with unsaturated alcohols and hydrocarbons have been measured at various temperatures. The alcohol reactions were measured in aqueous solutions and the hydrocarbon reactions in 1:1 aqueous acetonitirle (ACN) solutions. The rate constants for two alcohols and one hydrocarbon were also examined as a function of solvent composition. The room temperature rate constants varied between 10 6 and 10 9 M -1 s -1 . The pre-exponential factors, A, were about (1-5) x 10 9 M -1 s -1 for the alcohols in aqueous solutions and about (0.1-1) x 10 9 M -1 s -1 for the hydrocarbons in aqueous ACN solutions. The activation energies, E a , varied considerably, between 4 and 12 kJ mol -1 for the alcohols and between 2 and 8 kJ mol -1 for the hydrocarbons. The rate constants, k 298 , decrease with increasing ionization potential (IP) of the unsaturated compound, in agreement with an electrophilic addition mechanism. The activation energies for the unsaturated alcohols decrease when the IP decreases from 9.7 to 9.1 eV but appear to level off at lower IP. Most alkenes studied had IP a . Upon addition of ACN to the aqueous solution, the values of log k 298 decreased linearly by more than 1 order of magnitude with increasing ACN mole fraction. This decrease appears to result from a combination of changes in the activation energy and in the pre-exponential factor. The reason for these changes may lie in changes in the solvation shell of the Cl 2 sm-bullet- radical, which will affect the A factor, in combination with changes in solvation of Cl - , which will affect the energetics of the reactions as well. 20 refs., 7 figs., 6 tabs

  11. Determination of Three-Dimensional Morphology and Inner Structure of Second-Phase Inclusions in Metals by Non-Aqueous Solution Electrolytic and Room Temperature Organic Methods

    OpenAIRE

    Jing Guo; Keming Fang; Hanjie Guo; Yiwa Luo; Shengchao Duan; Xiao Shi; Wensheng Yang

    2018-01-01

    The secondary-phase particles in metals, particularly those composed of non-metallic materials, are often detrimental to the mechanical properties of metals; thus, it is crucial to control inclusion formation and growth. One of the challenges is determining the three-dimensional morphology and inner structures of such inclusions. In this study, a non-aqueous solution electrolytic method and a room-temperature organic technique were developed based on the principle of electrochemistry to deter...

  12. Thermodynamic properties of aqueous solutions with citrate ions. Compressibility studies in aqueous solutions of citric acid

    International Nuclear Information System (INIS)

    Apelblat, Alexander; Korin, Eli; Manzurola, Emanuel

    2013-01-01

    Highlights: • Over a wide range of concentrations and temperatures sound velocities were measured in aqueous solutions of citric acid. • Compressibility properties of citric acid solutions are thermodynamically characterized. • Changes in the structure of water when citric acid is dissolved are discussed. -- Abstract: Sound velocities in aqueous solutions of citric acid were measured from 15 °C to 50 °C in 5 °C intervals, within the 0.1 mol · kg −1 to 5.0 mol · kg −1 concentration range. These sound velocities served to evaluate the isentropic and isothermal compressibilities, the apparent molar compressibilities, the isochoric thermal pressure coefficients, changes of the cubic expansion coefficients with pressure at constant temperature, the changes of heat capacities with volume and hydration numbers of citric acid in aqueous solutions

  13. Model description of the equivalent electroconductivity of aqueous solutions of alkali metal hydroxides over a wide range of concentrations and temperatures

    Science.gov (United States)

    Kuznetsova, E. M.; Volkov, D. S.

    2011-09-01

    The possibility of a quantitative theoretical description of the λ( c) dependence for aqueous solutions of alkali metal hydroxides in a wide concentration (from 0.0001 to 12 M) and temperature (from 0 to 100°C) was considered on the basis of concept suggested earlier. Effectiveness of the description of characteristics analyzed was illustrated on the examples of the calculation of electroconductivity values for aqueous LiOH, NaOH, KOH, RbOH, and CsOH solutions and comparison of them with experimental values taken from published data. The suggestion on different H+ and OH- ion migration mechanism was made on the basis of the model used for description of λ( c).

  14. Enthalpies of solution of methylcalix[4]resorcinarene in non-aqueous solvents as a function of concentration and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Riveros, Diana C. [Laboratorio de Termodinamica de Soluciones, Departamento de Quimica, Facultad de Ciencias, Universidad de los Andes, Bogota D.C. (Colombia); Martinez, Fleming [Grupo de Investigaciones Farmaceutico-Fisicoquimicas, Departamento de Farmacia, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota D.C. (Colombia); Vargas, Edgar F., E-mail: edvargas@uniandes.edu.co [Laboratorio de Termodinamica de Soluciones, Departamento de Quimica, Facultad de Ciencias, Universidad de los Andes, Bogota D.C. (Colombia)

    2012-11-20

    Highlights: Black-Right-Pointing-Pointer The solution enthalpies of methylcalix[4]resorcinarene in alcohols have been measured. Black-Right-Pointing-Pointer The solution enthalpies of methylcalix[4]resorcinarene in alcohols are endothermic. Black-Right-Pointing-Pointer Enthalpies of transference are interpreted in terms of proton donor capacity of alcohols. - Abstract: Enthalpies of solution of 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octahydroxyresorci[4]arene in methanol, ethanol and propanol as a function of molal concentration at (288.15, 298.15 and 308.15) K were measured calorimetrically. The enthalpies of solvation were estimated. Using propanol as the referent solvent, transfer properties to other alcohols were also calculated. In addition, temperature dependence of the enthalpy of solution at infinite dilution was also obtained. The data were interpreted in terms of solute-solvent interactions.

  15. Influence of temperature on the kinetics absorption of carbon dioxide in aqueous of enzyme catalysed MDEA solutions

    NARCIS (Netherlands)

    Penders-van Elk, Nathalie J. M. C.; van Aken, Coen; Versteeg, Geert F.

    In the present work the absorption of carbon dioxide in 1000 mol m(-3) N-methyldiethanolamine (MDEA) solutions with and without enzyme has been studied in a stirred cell reactor in the temperature range 278-343 K and enzyme concentrations ranging from 0 to 1600 gm(-3). During this study a new type

  16. Enthalpies of solution of methylcalix[4]resorcinarene in non-aqueous solvents as a function of concentration and temperature

    International Nuclear Information System (INIS)

    Riveros, Diana C.; Martínez, Fleming; Vargas, Edgar F.

    2012-01-01

    Highlights: ► The solution enthalpies of methylcalix[4]resorcinarene in alcohols have been measured. ► The solution enthalpies of methylcalix[4]resorcinarene in alcohols are endothermic. ► Enthalpies of transference are interpreted in terms of proton donor capacity of alcohols. - Abstract: Enthalpies of solution of 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octahydroxyresorci[4]arene in methanol, ethanol and propanol as a function of molal concentration at (288.15, 298.15 and 308.15) K were measured calorimetrically. The enthalpies of solvation were estimated. Using propanol as the referent solvent, transfer properties to other alcohols were also calculated. In addition, temperature dependence of the enthalpy of solution at infinite dilution was also obtained. The data were interpreted in terms of solute–solvent interactions.

  17. Phase equilibrium properties of binary aqueous solutions containing ethanediamine, 1,2-diaminopropane, 1,3-diaminopropane, or 1,4-diaminobutane at several temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Nouria Chiali-Baba [LATA2M, Laboratoire de Thermodynamique Appliquee et Modelisation Moleculaire, University AbouBekr Belkaid of Tlemcen, P.O. Box 119, Tlemcen 13000 (Algeria); Negadi, Latifa, E-mail: l_negadi@mail.univ-tlemcen.d [LATA2M, Laboratoire de Thermodynamique Appliquee et Modelisation Moleculaire, University AbouBekr Belkaid of Tlemcen, P.O. Box 119, Tlemcen 13000 (Algeria); Mokbel, Ilham; Jose, Jacques [LSA, Laboratoire des Sciences Analytiques, CNRS-UMR 5180, Universite Claude Bernard - Lyon I. 43, Bd du 11 Novembre 1918, Villeurbanne Cedex 69622 (France)

    2011-05-15

    Research highlights: Vapour pressures of ethanediamine (EDA), 1,2-diaminopropane, 1,3-diaminopropane (1,3-DAP), or 1,4-diaminobutane (1,4-DAB) aqueous solutions are reported between (293 and 363) K. The two first mixtures show negative azeotropic behaviour. The aqueous solutions of EDA, 1,2-DAP, or 1,3-DAP exhibit negative G{sup E} whereas the one containing 1,4-DAB shows either negative G{sup E} or sinusoidal shape for G{sup E}. - Abstract: The vapour pressures of {l_brace}ethanediamine (EDA) + water{r_brace}, {l_brace}1,2-diaminopropane (1,2-DAP) + water{r_brace}, {l_brace}1,3-diaminopropane (1,3-DAP) + water{r_brace} or {l_brace}1,4-diaminobutane (1,4-DAB) + water{r_brace} binary mixtures, and of pure EDA, 1,2-DAP, 1,3-DAP, 1,4-DAB, and water components were measured by means of two static devices at temperatures between (293 and 363) K. The data were correlated with the Antoine equation. From these data, the excess Gibbs function (G{sup E}) was calculated for several constant temperatures and fitted to a fourth-order Redlich-Kister equation using the Barker's method. The {l_brace}ethanediamine (EDA) + water{r_brace}, and {l_brace}1,2-diaminopropane (1,2-DAP) + water{r_brace} binary systems show negative azeotropic behaviour. The aqueous solutions of EDA, 1,2-DAP, or 1,3-DAP exhibit negative deviations in G{sup E} for all investigated temperatures over the whole composition range whereas the (1,4-DAB + water) binary mixture shows negative G{sup E} for temperatures (293.15 < T/K < 353.15) and a sinusoidal shape for G{sup E} at T = 363.15 K.

  18. Radiolysis of Aqueous Toluene Solutions

    International Nuclear Information System (INIS)

    Christensen, H.C.; Gustafson, R.

    1971-04-01

    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-, N 2 O- 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 N 2 O-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(H 2 ). 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

  19. Two cloud-point phenomena in tetrabutylammonium perfluorooctanoate aqueous solutions: anomalous temperature-induced phase and structure transitions.

    Science.gov (United States)

    Yan, Peng; Huang, Jin; Lu, Run-Chao; Jin, Chen; Xiao, Jin-Xin; Chen, Yong-Ming

    2005-03-24

    This paper reported the phase behavior and aggregate structure of tetrabutylammonium perfluorooctanoate (TBPFO), determined by differential scanning calorimeter, electrical conductivity, static/dynamic light scattering, and rheology methods. We found that above a certain concentration the TBPFO solution showed anomalous temperature-dependent phase behavior and structure transitions. Such an ionic surfactant solution exhibits two cloud points. When the temperature was increased, the solution turned from a homogeneous-phase to a liquid-liquid two-phase system, then to another homogeneous-phase, and finally to another liquid-liquid two-phase system. In the first homogeneous-phase region, the aggregates of TBPFO were rodlike micelles and the solution was Newtonian fluid. While in the second homogeneous-phase region, the aggregates of TBPFO were large wormlike micelles, and the solution behaved as pseudoplastic fluid that also exhibited viscoelastic behavior. We thought that the first cloud point might be caused by the "bridge" effect of the tetrabutylammonium counterion between the micelles and the second one by the formation of the micellar network.

  20. Crystallisation of materials from aqueous solutions

    NARCIS (Netherlands)

    Witkamp, G.J.; Vrijenhoef, J.P.; De Graauw, J.; Van der Ham, F.

    2001-01-01

    The invention is directed to a process for recovering a crystalline material from an aqueous solution, which solution also contains organic contaminants, in which process the material is crystallised from the aqueous solution by freeze crystallising at a eutectic freezing point of the solution.

  1. Sound velocity in potassium hydroxide aqueous solution

    International Nuclear Information System (INIS)

    Tsapuryan, Kh.D.; Aleksandrov, A.A.; Kochetkov, A.I.

    1992-01-01

    Measurements of ultrasonic velocities in potassium hydroxide aqueous solutions are carried out within the frames of studies on improvement of water chemistry in NPP cooling systems. Method of echo pulses superposition with acoustic path length of 41.447 mm is used for measurements. The measurements are performed at 2.6 MHz frequency. Complex temperature dependence of ultrasonic velocity is determined. Ultrasonic velocity dependence on pressure is close to linear one. The formula for calculation of thermodynamic properties of the studied solutions on the basis of experimental data obtained is proposed

  2. Isobaric specific heat capacity of water and aqueous cesium chloride solutions for temperatures between 298 K and 370 K at p = 0.1 MPa

    International Nuclear Information System (INIS)

    Lourenco, M.J.V.; Santos, F.J.V.; Ramires, M.L.V.; Nieto de Castro, C.A.

    2006-01-01

    There has been some controversy regarding the uncertainty of measurements of thermal properties using differential scanning calorimeters, namely heat capacity of liquids. A differential scanning calorimeter calibrated in enthalpy and temperature was used to measure the isobaric specific heat capacity of water and aqueous solutions of cesium chloride, in the temperature range 298 K to 370 K, for molalities up 3.2 mol . kg -1 , at p = 0.1 MPa, with an estimated uncertainty (ISO definition) better than 1.1%, at a 95% confidence level. The measurements are completely traceable to SI units of energy and temperature. The results obtained were correlated as a function of temperature and molality and compared with other authors, obtained by different methods and permit to conclude that a DSC calibrated by Joule effect is capable of very accurate measurements of the isobaric heat capacity of liquids, traceable to SI units of measurement

  3. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

    Beitz, J.V.; Williams, C.W.

    1996-01-01

    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 HClO 4 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 UO 2 F 2 . Studies on the effect of added LiNO 3 or Na 2 WO 4 ·2H 2 O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF 6 content of WF 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF 6

  4. 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

  5. Radiolysis of Aqueous Benzene Solutions

    International Nuclear Information System (INIS)

    Christensen, H.

    1964-05-01

    Aerated and deaerated aqueous solutions of benzene have been irradiated with 60 Co 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(H 2 ) = 0.44 (0. 43) and G(H 2 O 2 ) = 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 + H 2 O 2 ) >> k(H + H 2 O 2 ). Furthermore, the results indicate that a competition takes place between the reactions: 2 C 6 H 6 OH · -> dimer -> biphenyl. C 6 H 7 · + C 6 H 6 OH · -> dimer -> biphenyl. The yields in aerated, unbuffered or acid, solutions were: G(phenol) = 2.1 (2.3), G(biphenyl) = 0 (0), and G(H 2 O 2 ) = 2.2 (3.1), the figures in brackets being valid for acid solutions. The ratio k(H + C 6 H 6 )/k(H + O 2 ) was 1.4x10 -2 . The results indicate that peroxides, or more probably hydroperoxides, take part in the reactions. After the addition of Fe 2+ or Fe 3+ 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

  6. Fluorescence lifetime of Rhodamine B in aqueous solutions of polysaccharides and proteins as a function of viscosity and temperature.

    Science.gov (United States)

    Mercadé-Prieto, Ruben; Rodriguez-Rivera, Luis; Chen, Xiao Dong

    2017-11-08

    Rhodamine B (RhB) is a well known dye extensively used in thermometric studies, either considering the decrease in the fluorescence intensity or the lifetime (τ) with temperature. Lifetime measurements are preferred over intensity ones as they are more robust. In order to expand microscopy thermometry to complex food fluids, the effect of solutes on the τ of RhB was studied using fluorescence lifetime imaging microscopy (FLIM) in a two-photon microscope. Polysaccharides of different molecular weights (glucose, lactose, dextran, maltodextrin, and sodium alginate), as well as whey proteins, were considered as typical model food ingredients. A linear increase in τ with the concentration is observed in most polysaccharides, highlighting that it is not due to an increase in the macroscopic viscosity, but in maltodextrins a Langmuir-like concentration dependence is observed. There are extensive interactions between RhB and whey proteins at small concentrations that quickly increase τ up to saturation at >10 wt% proteins, with τ modelled well using an adsorption Langmuir model. Therefore, the effect of solutes on RhB τ is not related to changes in the macroscopic viscosity. The temperature sensitivity of τ, quantified using apparent activation energies, decreases at high solute contents.

  7. Ternary (liquid + liquid) equilibria for the extraction of ethanol, or 2-propanol from aqueous solutions with 1,1′-oxybis(butane) at different temperatures

    International Nuclear Information System (INIS)

    Wang, Cui; Guo, Jitai; Cheng, Kai; Chen, Yao

    2016-01-01

    Highlights: • LLE data of [water + ethanol or 2-propanol + 1,1′-oxybis(butane)] were measured at four temperatures. • Tie-line data were correlated by using the extended and modified UNIQUAC models. • The temperature influence on liquid-phase regions was analyzed. • The ability of DBE to extract ethanol or 2-propanol from aqueous solutions was discussed. - Abstract: (Liquid + liquid) equilibrium data for the ternary systems of {water + ethanol + 1,1′-oxybis(butane)} and {water + 2-propanol + 1,1′-oxybis(butane)} at T = (293.15, 298.15, 303.15, 308.15) K have been measured under atmospheric pressure. The experimental results were correlated by using the modified and extended UNIQUAC models. Distribution coefficients and separation factors of ethanol and 2-propanol were calculated and discussed in detail. The temperature influence on liquid-phase regions was analysed.

  8. Computation of Equilibrium Partial Vapor Pressures of Aqueous Ammonia Solutions

    National Research Council Canada - National Science Library

    Field, Paul

    2000-01-01

    This report evaluates all available vapor-liquid equilibria (VLE) data from low-to-moderate pressures over the normal liquid water temperature range for the highly non-ideal aqueous ammonia solutions spanning nearly a century...

  9. Study on corrosion of carbon steel in DEA aqueous solutions

    Science.gov (United States)

    Yang, Jun Han; Xie, Jia Lin; Zhang, Li

    2018-02-01

    Corrosion of carbon steel in the CO2 capture process using diethanolamine (DEA) aqueous solutions was investigated. The effects of the mass concentrations of DEA, solution temperature and CO2 loading on the corrosion rate of carbon steel were demonstrated. The experimental results provided comprehensive information on the appropriate concentration range of DEA aqueous solutions under which low corrosion of carbon steel can be achieved.

  10. Room temperature synthesis of PbSe quantum dots in aqueous solution: Stabilization by interactions with ligands

    Science.gov (United States)

    Primera-Pedrozo, Oliva M.; Arslan, Zikri; Rasulev, Bakhtiyor; Leszczynski, Jerzy

    2011-01-01

    An aqueous route of synthesis is described for rapid synthesis of lead selenide quantum dots (PbSe QDs) at room temperature in an attempt to produce water-soluble and stable nanocrystals. Several thiol-ligands, including thioglycolic acid (TGA), thioglycerol (TGC), 3-mercaptopropionic acid (MPA), 2-mercaptoethyleamine hydrochloride (MEA), 6-mercaptohexanoic acid (MHA), and L-cysteine (L-cys), were used for capping/stabilization of PbSe QDs. The effects of the ligands on the stability of PbSe QDs were evaluated for a period of two months at room temperature under normal light conditions and at 4 °C in dark. The TGA- and MEA-capped QDs exhibited the highest stability prior to purification, almost two months when kept in dark at 4 °C. However, the stability of TGA-capped QDs was reduced substantially after purification to about 5 days under same conditions, while MEA-capped QDs did not show any significant instability. The stabilization energies of Pb-thiolate complexes determined by theoretical DFT simulations supported the experimental results. The PbSe QDs capped with TGA, MPA and MEA were successfully purified and re-dispersed in water, while those stabilized with TGC, MHA and L-cys aggregated during purification attempts. The purified PbSe QDs possess very susceptible surface resulting in poor stability for about 30 – 45 min after re-dispersion in water. In the presence of an excess of free ligand, the stability increased up to 5 days for TGA-capped QDs at pH 7.19, 9 –12 days for MPA-capped QDs at pH 7.3–7.5 and 45–47 days for MEA-capped QDs at pH 7.35. X-Ray Diffraction (XRD) results showed that the QDs possess a cubic rock salt structure with the most intense peaks located at 2θ = 25.3° (200) and 2θ = 29.2° (100). TEM images showed that the size of the QDs ranges between 5 and 10 nm. ICP-MS results revealed that Pb:Se ratio was 1.26, 1.28, 3.85, 1.18, and 1.31 for the QDs capped with TGA, MPA, MEA, L-Cys, and TGC, respectively. The proposed method

  11. Phase separation during freezing upon warming of aqueous solutions

    Science.gov (United States)

    Bogdan, A.; Loerting, T.

    2014-11-01

    Using differential scanning calorimetry, we show that the addition of solute(s) to emulsified water lowers the freezing temperature to nanodrops adsorbed on fumed silica resemble bulk water more than water confined in nanoscaled confinement and also more than nanoscaled water domains in aqueous solution.

  12. 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.

  13. Shear-Induced Phase Separation in Aqueous Polymer Solutions: Temperature-Sensitive Microgels and Linear Polymer Chains

    NARCIS (Netherlands)

    Stieger, M.A.; Richtering, W.

    2003-01-01

    The influence of shear flow on the phase separation of aqueous poly(N-isopropylacrylamide) (PNiPAM) microgel suspensions was investigated by means of rheo-turbidity and rheo-small angle neutron scattering (rheo-SANS) and compared to the behavior of linear PNiPAM macromolecules. The rheological

  14. 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.

  15. Studies on the conformational transformations of L-arginine molecule in aqueous solution with temperature changing by circular dichroism spectroscopy and optical rotations

    Science.gov (United States)

    Wang, Luning; Zhang, Guanghui; Wang, Xinqiang; Wang, Lei; Liu, Xitao; Jin, Lutong; Xu, Dong

    2012-10-01

    Experimental measurements, including circular dichroism (CD) spectroscopy and optical rotations have been employed to characterize the changing tendency of molecular conformations of the full protonated L-arginine (LA2+) in aqueous solution with the rising of temperature. Calculating methods, including conformational search, molecular structural optimization, CD responses as well as specific rotation calculations have been performed to interpret experimental results. Calculated results, no matter in CD spectra or specific rotations, are consistent with experiments, which strongly certify the transformation of molecular conformations. This successful reproduction of experimental results with molecular simulations in both areas of CD responses and optical rotations is of great significance. More detailed analysis about the relationship between LA2+ molecular structure and the optical activity has been conducted.

  16. Stabilization of aqueous alkali metal aluminate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Allenson, S.J.

    1988-03-29

    A method of stabilizing an aqueous solution of alkali metal aluminate is described comprising: admixing an aqueous solution of alkali metal aluminate having a pH of at least 10 with a sufficient amount of vinyl polymer having pendant carboxylate groups to form a solution containing from 0.1 to 2.0 weight percent of an anionic vinyl polymer based on alkali metal aluminate solids. The anionic vinyl polymer has an average molecular weight of at least 500,000.

  17. Internal Nanoparticle Structure of Temperature-Responsive Self-Assembled PNIPAM-b-PEG-b-PNIPAM Triblock Copolymers in Aqueous Solutions: NMR, SANS, and Light Scattering Studies.

    Science.gov (United States)

    Filippov, Sergey K; Bogomolova, Anna; Kaberov, Leonid; Velychkivska, Nadiia; Starovoytova, Larisa; Cernochova, Zulfiya; Rogers, Sarah E; Lau, Wing Man; Khutoryanskiy, Vitaliy V; Cook, Michael T

    2016-05-31

    In this study, we report detailed information on the internal structure of PNIPAM-b-PEG-b-PNIPAM nanoparticles formed from self-assembly in aqueous solutions upon increase in temperature. NMR spectroscopy, light scattering, and small-angle neutron scattering (SANS) were used to monitor different stages of nanoparticle formation as a function of temperature, providing insight into the fundamental processes involved. The presence of PEG in a copolymer structure significantly affects the formation of nanoparticles, making their transition to occur over a broader temperature range. The crucial parameter that controls the transition is the ratio of PEG/PNIPAM. For pure PNIPAM, the transition is sharp; the higher the PEG/PNIPAM ratio results in a broader transition. This behavior is explained by different mechanisms of PNIPAM block incorporation during nanoparticle formation at different PEG/PNIPAM ratios. Contrast variation experiments using SANS show that the structure of nanoparticles above cloud point temperatures for PNIPAM-b-PEG-b-PNIPAM copolymers is drastically different from the structure of PNIPAM mesoglobules. In contrast with pure PNIPAM mesoglobules, where solidlike particles and chain network with a mesh size of 1-3 nm are present, nanoparticles formed from PNIPAM-b-PEG-b-PNIPAM copolymers have nonuniform structure with "frozen" areas interconnected by single chains in Gaussian conformation. SANS data with deuterated "invisible" PEG blocks imply that PEG is uniformly distributed inside of a nanoparticle. It is kinetically flexible PEG blocks which affect the nanoparticle formation by prevention of PNIPAM microphase separation.

  18. D{sub 2}O−H{sub 2}O solvent isotope effects on the enthalpies of bicaret hydration and dilution of its aqueous solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Evgeniy V., E-mail: evi@isc-ras.ru [Laboratory of Thermodynamics of Solutions of Non-electrolytes and Biologically Active Substances, G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, 1 Akademicheskaya Str., 153045 Ivanovo (Russian Federation); Batov, Dmitriy V. [Incorporated Physicochemical Center of Solution Researches, G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, 1 Akademicheskaya Str., 153045, Ivanovo (Russian Federation); Ivanovo' s State University of Chemistry and Technology, 7 Sheremetevsky Ave, 153000 Ivanovo (Russian Federation); Gazieva, Galina A.; Kravchenko, Angelina N. [Laboratory of Nitrogen-containing Compounds, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Ave., 199119 Moscow (Russian Federation); Abrosimov, Vladimir K. [Laboratory of Thermodynamics of Solutions of Non-electrolytes and Biologically Active Substances, G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, 1 Akademicheskaya Str., 153045 Ivanovo (Russian Federation)

    2014-08-20

    Graphical abstract: - Highlights: • Enthalpies of solution of bicaret (tetraethylglycoluril) in H{sub 2}O and D{sub 2}O were measured. • D{sub 2}O–H{sub 2}O enthalpy-isotopic effect is negative and decreasing with temperature. • Enthalpic coefficients h{sub 22} for pairwise solute–solute interactions were derived. • Quantity of h{sub 22} is negative and becoming the more negative in heavy water. • Prevailingly hydrophobic hydration of bicaret is weakened with rising temperature. - Abstract: The molar enthalpies of solution of bicaret or 2,4,6,8-tetraethyl-2,4,6,8-tatraazabicyclo[3.3.0]octane-3,7-dione in ordinary (H{sub 2}O) and heavy (D{sub 2}O) water at (278.15, 288.15, 298.15, 308.15, and 318.15) K as well as the enthalpies for dilution of its H/D isotopically distinguishable aqueous solutions at 298.15 K were measured calorimetrically. The standard (at infinite dilution) molar enthalpies and heat capacities of solution, and the enthalpic coefficients for pair (h{sub 22}) and triplet (h{sub 222}) interactions between hydrated solute molecules, along with D{sub 2}O–H{sub 2}O solvent isotope effects (IEs) on the studied quantities were computed. The enthalpic effects of bicaret dissolution and corresponding IEs were found to be negative and decreasing in magnitude with increasing temperature. On the contrary, the h{sub 22} and h{sub 222} values as well as IEs on them were found to be positive. These facts indicate that the bicaret hydration being predominantly hydrophobic is enhanced in the D{sub 2}O medium. The hydration behavior of the solute considered was discussed in comparison with that for mebicar or 2,4,6,8-tetramethyl-2,4,6,8-tatraazabicyclo[3.3.0]octane-3,7-dione using the previously obtained data.

  19. Rheological behaviour of some saccharides in aqueous potassium chloride solutions over temperature range (288.15 to 318.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Banipal, Parampaul K., E-mail: pkbanipal@yahoo.co [Department of Chemistry, Guru Nanak Dev University, Amritsar 143005 (India); Chahal, Amanpreet K.; Singh, Vickramjeet [Department of Chemistry, Guru Nanak Dev University, Amritsar 143005 (India); Banipal, Tarlok S. [Department of Applied Chemistry, Guru Nanak Dev University, Amritsar 143005 (India)

    2010-08-15

    The viscosities, {eta} of mono-, di-, tri-saccharides and methylglycosides, viz., D(+)-xylose (XYL), D(-)-arabinose (ARA), D(-)-ribose (RIB), D(-)-fructose (FRU), D(+)-galactose (GAL), D(+)-mannose (MAN), D(+)-glucose (GLU), D(+)-melibiose (MEL), D(+)-cellobiose (CEL), D(+)-lactose monohydrate (LAC), D(+)-maltose monohydrate (MAL), D(+)-trehalose dihydrate (TRE), sucrose (SUC), D(+)-raffinose pentahydrate (RAF), {alpha}-methyl-D(+)-glucoside ({alpha}-Me-GLU), methyl-{alpha}-D-xylopyranoside (Me-{alpha}-XYL), and methyl-{beta}-D-xylopyranoside (Me-{beta}-XYL) in water and in (0.5, 1.0, 2.0, and 3.0) mol . kg{sup -1} aqueous solutions of potassium chloride (KCl) have been determined at T = (288.15, 298.15, 308.15, and 318.15) K from efflux time measurements by using a capillary viscometer. Densities used to determine viscosities have been reported earlier. The viscosity data have been utilized to determine the viscosity B-coefficients employing the Jones-Dole equation at different temperatures. From these data, the viscosity B-coefficients of transfer, {Delta}{sub t}B have been estimated for the transfer of various saccharides/methylglycosides from water to aqueous potassium chloride solutions. The {Delta}{sub t}B values have been found to be positive, whose magnitude increases with the increase in concentration of potassium chloride in all cases. The dB/dT coefficients, pair, {eta}{sub AB} and triplet, {eta}{sub ABB} viscometric interaction coefficients have also been determined. Gibbs free energies of activation and related thermodynamic parameters of activation of viscous flow have been determined employing Feakin's transition-state theory. The signs and magnitudes of various parameters have been discussed in terms of solute-solute and solute-solvent interactions occurring in these solutions. The effect of substitution of -OH by methoxy group, -OCH{sub 3} has also been discussed.

  20. Crystallization of urea from an evaporative aqueous solution sessile droplet at sub-boiling temperatures and surfaces with different wettability

    NARCIS (Netherlands)

    Schmid, J.; Zarikos, I.|info:eu-repo/dai/nl/413577473; Terzis, A.; Roth, N.; Weigand, B.

    The injection of urea-water-solution sprays in the exhaust pipe of modern diesel engines eliminates NOx emissions in a very great extent. However, as water evaporates from the solution, urea is crystallized and causes walldeposit formations hindering the performance of selective-catalytic-reaction.

  1. ADSORPTION OF Pb(II) IONS FROM AQUEOUS SOLUTION USING ...

    African Journals Online (AJOL)

    ABSTRACT. The adsorption of lead(II) ions from aqueous solution onto alkali lignin extracted from Hagenia abyssinica was investigated by electrochemical methods. The effect of solution pH, lignin dosage and contact time were investigated at room temperature in a batch system. Adsorption equilibrium was approached ...

  2. Thermodynamics of aqueous solutes at high temperatures and pressures: Application of the hydration theory and implications for fluid-mediated mass transfer

    Science.gov (United States)

    Sulak, M.; Dolejs, D.

    2012-04-01

    Magmatic activity and prograde devolatilization of subducting or underplating lithologies release large quantities of aqueous fluids that act as mass and heat transfer agents in the planetary interiors. Understanding of mineral-melt-fluid interactions is essential for evaluating the effects of fluid-mediated mass transport in subduction zones, collisional orogens as well as in igneous provinces. The thermodynamic properties of aqueous species were frequently described by the Helgeson-Kirkham-Flowers equation of state [1] but its utility is limited by inavailability of the solvent dielectric properties at high pressures and temperatures, and by decoupling of species-solvent mechanical and electrostatic interactions that cannot be separated within the Born theory. Systematic description of the hydration process in a Born-Haber cycle leads to the following thermochemical contributions: (i) thermodynamic properties of an unhydrated species, (ii) the pressure-volume work required to create a cavity within the solvent to accommodate the species, described by the scaled particle theory, (iii) entropic contribution related to changes in the solute's and the solvent's kinetic degrees of freedom, and (iv) contribution from the solute-solvent molecular interactions and corresponding rearrangement of the solvent molecules to form the hydration shell. Application of the spatial correlation functions [2, 3] results in apparent Gibbs energy of aqueous species, ΔaGi = a + bT + cTlnT + dP + eTlnρ + fTρlnρ, where athrough f represent constants related to standard thermodynamic properties of aqueous species (ΔfH, S, V, cP) and to solvent volumetric properties at 298.15 K and 1 bar (ρ, α, β etc.). In phase equilibrium calculations, the number of required parameters often reduces to four (c = f = 0) while noting that H2O density as the only solvent-related property is accurately known to extreme temperatures and pressures. The equation of state parameters were calibrated for 30

  3. 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.

  4. Studies on volumetric properties of some saccharides in aqueous potassium chloride solutions over temperature range (288.15 to 318.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Banipal, Parampaul K. [Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India)], E-mail: pkbanipal@yahoo.com; Chahal, Amanpreet K. [Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India); Banipal, Tarlok S. [Department of Applied Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India)

    2009-04-15

    The standard partial molar volumes, V{sub 2}{sup {infinity}} at infinite dilution of monosaccharides; D(+)-xylose, D(-)-arabinose, D(-)-ribose, D(+)-mannose, D(+)-galactose, D(-)-fructose and D(+)-glucose, disaccharides; D(+)-melibiose, D(+)-cellobiose, D(+)-maltose monohydrate, D(+)-trehalose dihydrate, D(+)-lactose monohydrate and sucrose, trisaccharide; D(+)-raffinose pentahydrate, methylglycosides; {alpha}-methyl-D(+)-glucoside, methyl-{alpha}-D-xylopyranoside and methyl-{beta}-D-xylopyranoside have been determined in water and in aqueous solutions of potassium chloride (0.5, 1.0, 2.0, and 3.0) mol . kg{sup -1} at T = (288.15, 298.15, 308.15, and 318.15) K from density measurements employing a vibrating-tube densimeter. These results have been utilized to determine the corresponding standard partial molar volumes of transfer, {delta}{sub t}V{sub 2}{sup {infinity}} for the transfer of various saccharides from water to aqueous potassium chloride solutions. The standard transfer volumes have been found to be positive (except for {alpha}- and {beta}-methyl xylopyranosides in 0.5 mol . kg{sup -1} solutions of potassium chloride) whose magnitude increase with the concentration of potassium chloride as well as temperature for all the saccharides. Partial molar expansion coefficients, ({partial_derivative}V{sub 2}{sup {infinity}}/{partial_derivative}T){sub p} and the second derivative ({partial_derivative}{sup 2}V{sub 2}{sup {infinity}}/{partial_derivative}T{sup 2}){sub p} values have been estimated. Pair and higher order volumetric interaction coefficients have also been calculated from {delta}{sub t}V{sub 2}{sup {infinity}} by using the McMillan-Mayer theory. These parameters have been discussed in terms of the solute-cosolute interactions and are used to understand various mixing effects due to these interactions. The effect of substitution of -OH by glycosidic group, -OCH{sub 3} is also discussed. Attempt has also been made to discuss the stereochemical effects

  5. Corrosion behaviour of sensitized and unsensitized Alloy 900 (UNS 1.4462) in concentrated aqueous lithium bromide solutions at different temperatures

    International Nuclear Information System (INIS)

    Leiva-Garcia, R.; Munoz-Portero, M.J.; Garcia-Anton, J.

    2010-01-01

    Duplex stainless steels can undergo microstructural changes if they are heated improperly. When that happens, duplex stainless steels are sensitized and intermetallic phases appear. The high Chromium and Molybdenum content promotes the formation of secondary phases as a consequence of the heat treatment. These secondary phases, which are rich in alloying elements, such as Cr and Mo, deplete these elements from the neighbouring phases, leading to a reduction in corrosion resistance. In order to study the influence of the secondary phases on the corrosion parameters, samples of duplex stainless steel, Alloy 900 (UNS 1.4462), have been heated in argon atmosphere at 825 deg. C for 1 h. The corrosion behaviour of sensitized and unsensitized Alloy 900 has been analyzed in a concentrated aqueous lithium bromide (LiBr) solution of 992 g/L by means of cyclic potentiodynamic curves. Secondary phase presence reduces the pitting potential value of Alloy 900. Besides, the pitting potential decreases with temperature. On the other hand, the corrosion potential and open circuit potential values increase with temperature and sensitization.

  6. Kinetics of ptaquiloside hydrolysis in aqueous solution

    DEFF Research Database (Denmark)

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

    2006-01-01

    Ptaquiloside (PTA) is a well-known toxin produced by the bracken fern (Pteridium aquilinum (L.) Kuhn). It is proposed that PTA from bracken stands can leach through soil and sediments into drinking-water reservoirs, thus representing a concern for human health. To predict the persistence of the t......Ptaquiloside (PTA) is a well-known toxin produced by the bracken fern (Pteridium aquilinum (L.) Kuhn). It is proposed that PTA from bracken stands can leach through soil and sediments into drinking-water reservoirs, thus representing a concern for human health. To predict the persistence...... 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......H lower than 4.43 (0.32), the reaction is acid-mediated, whereas the reaction is base-mediated at pH higher than 6.39 (0.28). The rate constants for the acidcatalyzed, base-catalyzed, and neutral hydrolysis are 25.70 (0.96), 4.83 (0.03) 104, and 9.49 (6.02) 104 h1, respectively. The PTA hydrolysis at pH 4...

  7. Separation of metal ions from aqueous solutions

    Science.gov (United States)

    Almon, Amy C.

    1994-01-01

    A process and apparatus for quantitatively and selectively separating metal ions from mixtures thereof in aqueous solution. The apparatus includes, in combination, a horizontal electrochemical flow cell containing flow bulk electrolyte solution and an aqueous, metal ion-containing solution, the cell containing a metal mesh working electrode, a counter electrode positioned downstream from the working electrode, an independent variable power supply/potentiostat positioned outside of the flow cell and connected to the electrodes, and optionally a detector such as a chromatographic detector, positioned outside the flow cell. This apparatus and its operation has significant application where trace amounts of metal ions are to be separated.

  8. from aqueous solution by Azolla filiculoides

    African Journals Online (AJOL)

    Jane

    2011-07-25

    Jul 25, 2011 ... tion, electroplating, ion exchange and membrane pro- cesses, are limited in practical application ... adequate dilution of the stock solution with deionised water. All the adsorption experiments were .... aqueous solutions by pre-treated biomass of Australian marine algae. Bioresour. Technol. 69: 223-229.

  9. Temperature-induced phase separation and hydration in poly(N-vinylcaprolactam) aqueous solutions: a study by NMR and IR spectroscopy, SAXS, and quantum-chemical calculations

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Dybal, Jiří; Starovoytova, Larisa; Zhigunov, Alexander; Sedláková, Zdeňka

    2012-01-01

    Roč. 8, č. 22 (2012), s. 6110-6119 ISSN 1744-683X R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : phase separation * coil-globule phase transition * aqueous solution Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.909, year: 2012

  10. EXTRACTION OF URANYL NITRATE FROM AQUEOUS SOLUTIONS

    Science.gov (United States)

    Furman, N.H.; Mundy, R.J.

    1957-12-10

    An improvement in the process is described for extracting aqueous uranyl nitrate solutions with an organic solvent such as ether. It has been found that the organic phase will extract a larger quantity of uranyl nitrate if the aqueous phase contains in addition to the uranyl nitrate, a quantity of some other soluble nitrate to act as a salting out agent. Mentioned as suitable are the nitrates of lithium, calcium, zinc, bivalent copper, and trivalent iron.

  11. Knudsen thermogravimetry approach to the thermodynamics of aqueous solutions

    International Nuclear Information System (INIS)

    Schiraldi, Alberto; Signorelli, Marco; Fessas, Dimitrios

    2013-01-01

    Highlights: ► Knudsen cells were designed to replace standard TG pans for desorption experiments. ► The Knudsen effusion data allow determination of water activity of aqueous solutions. ► This methods can replace the traditional isopiestic approach for aqueous solutions. ► The Gibbs–Duhem relationship was used to fit the experimental data. -- Abstract: The use of isothermal TGA with Knudsen-like cells allows determination of the thermodynamic activity of water, a W . The typical experiment implies a slow dehydration of the aqueous solution at constant temperature in dynamic vacuum conditions. The method is alternative to the classical isopiestic approach and offers the advantage of a continuous record on increasing the solute concentration. These data can be directly treated according to the classical thermodynamic relationships drawn from the Gibbs–Duhem expression to evaluate the activity and osmotic coefficient of the aqueous solutions of electrolytes and non-electrolytes, and, in the case of electrolytes, allow determination of solubility of the solute. Discrepancies with respect to the literature data are observed when the viscosity of the systems becomes too high, as in the case of sugars with a very large solubility. Such a mismatch may however be accounted for either slowing the dehydration rate with use of a narrower Knudsen orifice, or correcting the experimental a W with a calibration curve. The same approach can be applied to non-aqueous solutions

  12. Kinetics of absorption of carbon dioxide in aqueous ammonia solutions

    NARCIS (Netherlands)

    Derks, P. W. J.; Versteeg, G. F.

    2009-01-01

    In the present work the absorption of carbon dioxide into aqueous ammonia solutions has been studied in a stirred cell reactor, at low temperatures and ammonia concentrations ranging from 0.1 to about 7 kmol m-3. The absorption experiments were carried out at conditions where the so-called pseudo

  13. 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

  14. Adsorption of methylene blue from aqueous solution on the surface ...

    African Journals Online (AJOL)

    Adsorption of dye methylene blue from aqueous solution on the surface of sheep wool and cotton fibers was accomplished under the optimize conditions of temperature, concentration, pH, stay time duration and quantity of adsorbent. Spectrometric technique was used for the measurements of concentration of dye before ...

  15. Kinetics of absorption of carbon dioxide in aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W. J.; Kleingeld, T.; van Aken, C.; Hogendoorn, J. A.; Versteeg, G. F.

    2006-01-01

    In the present work the absorption of carbon dioxide into aqueous piperazine (PZ) solutions has been studied in a stirred cell, at low to moderate temperatures, piperazine concentrations ranging from 0.6 to 1.5 kmol m- 3, and carbon dioxide pressures up to 500 mbar, respectively. The obtained

  16. Kinetics of Absorption of CO2 in Aqueous Piperazine Solutions

    NARCIS (Netherlands)

    Derks, P.W.J.; Kleingeld, T.; van Aken, C.; Hogendoorn, Kees; Versteeg, Geert

    2006-01-01

    In the present work the absorption of carbon dioxide into aqueous piperazine (PZ) solutions has been studied in a stirred cell, at low to moderate temperatures, piperazine concentrations ranging from 0.6 to 1.5 kmolm−3, and carbon dioxide pressures up to 500 mbar, respectively. The obtained

  17. Volumetric studies of some amino acids in binary aqueous solutions ...

    Indian Academy of Sciences (India)

    Unknown

    partial molar volumes (Vφ. 0) of each amino acid have been calculated. These data were combined with the earlier reported Vφ. 0 values of glycine, L-alanine, and L-valine in aqueous MgCl2⋅6H2O solutions at. 298⋅15 K in order to describe the temperature dependence behaviour of partial molar quantities. Group.

  18. Densities concentrations of aqueous of uranyl nitrate solutions

    International Nuclear Information System (INIS)

    Rodrigo Otero, A.; Rodriguez Hernandez, B.; Fernandez Rodriguez, L.

    1966-01-01

    The ratio density-concentration of aqueous uranyl nitrate solutions expressed as U 3 O 8 grams/liter, U grams/liter and hexahydrate uranyl nitrate weight percent at different temperatures, are established. Experimental values are graphically correlated and compared whit some published data. (Author) 2 refs

  19. Biosorption of cadmium (ii) ion from aqueous solution by Afzelia ...

    African Journals Online (AJOL)

    The batch adsorption of cadmium (II) ion from aqueous solution using low-cost adsorbent of biological origin, Afzelia africana shell under different experimental conditions was investigated in this study. The influences of initial Cd (II) ion concentration, initial pH, contact times and temperature were reported. Adsorption of Cd ...

  20. Sol-gel transition behavior of aqueous peptide-amphiphile (C16-W3K) solutions: effects of alkyl-tail length, mechanical shear, temperature, and salt

    Science.gov (United States)

    Yamamoto, Masashi; Otsuka, Takahiro; Orimo, Yoshinori; Maeda, Tomoki; Hotta, Atsushi

    Peptide amphiphiles (PA) possess nanoscale micelle structures and excellent biocompatibility. In aqueous PA solution, PA molecules can self-assemble through various configurations into spherical and wormlike micelles, which can occasionally form hydrogels. C16-W3K is one of the unique PA, whose micelle configurations can transfer from spherical to wormlike structures in its aqueous solution over time, while the wormlike micelles could also lead to gelation. In our recent research, the effects of the length of the hydrophobic alkyl tail and other external factors of C16-W3K on the gelation behavior of the C16-W3K solution have been discussed. It has been revealed that longer alkyl-tails could facilitate the gelation of the C16-W3K solution, and that the external stimuli, such as mechanical shear and heat, could promote faster gelation of the C16-W3K solution. It was also found that salt could adjust the pH of the C16-W3K solution, having profound influence on the gelation behavior of the C16-W3K solution. In fact, the gelation of the C16-W3K with a higher storage modulus could be obtained from relatively acidic solutions, while the gelation of the C16-W3K solution was firmly suppressed in highly basic solutions. This work was supported by a Grant-in-Aid for Scientific Research (A) (No. 15H02298 to A.H.) and a Grant-in-Aid for Research Activity Start-up (No.15H06586 to T.M.) from JSPS: KAKENHI.

  1. REMOVAL OF CADMIUM FROM AQUEOUS SOLUTION USING ...

    African Journals Online (AJOL)

    The discharge of industrial effluents containing appreciably high concentrations of heavy metals such as zinc, cadmium, lead, ... synthesized products for the removal of cadmium ion from aqueous solution. This involves investigation ... manganese, and the charge is not compensated by the presence of other cation. Table 1.

  2. Aqueous solutions of ionic liquids: microscopic assembly

    NARCIS (Netherlands)

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

    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

  3. Pulse radiolysis of anthraquinone dye aqueous solution

    International Nuclear Information System (INIS)

    Perkowski, J.; Gebicki, J.L.; Lubis, R.; Mayer, J.

    1988-01-01

    Pulse radiolysis of argon flushed aqueous solutions of 10 -5 -10 -4 mol dm -3 anthraquinone dye (C.I. Acid Blue 62) gives rise to the transients originated from the reactions of e - aq , OH and H. The rate constants of these reactions are determined. (author)

  4. Production of Plutonium Metal from Aqueous Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Orth, D.A.

    2003-01-16

    The primary separation of plutonium from irradiated uranium by the Purex solvent extraction process at the Savannah River Plant produces a dilute plutonium solution containing residual fission products and uranium. A cation exchange process is used for concentration and further decontamination of the plutonium, as the first step in the final preparation of metal. This paper discusses the production of plutonium metal from the aqueous solutions.

  5. Temperature-induced phase separation and hydration in aqueous polymer solutions studied by NMR and IR spectroscopy: comparison of poly(N-vinylcaprolactam) and acrylamide-based polymers

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Dybal, Jiří

    2014-01-01

    Roč. 336, č. 1 (2014), s. 39-46 ISSN 1022-1360. [International IUPAC Conference on Polymer-Solvent Complexes and Intercalates /9./ - POLYSOLVAT-9. Kiev, 11.09.2012-14.09.2012] R&D Projects: GA ČR GA202/09/1281 Institutional support: RVO:61389013 Keywords : aqueous polymer solutions * FT-IR * NMR Subject RIV: CD - Macromolecular Chemistry

  6. Removal of uranium from aqueous solutions by diatomite (Kieselguhr)

    International Nuclear Information System (INIS)

    Aytas, S.Oe.; Akyil, S.; Aslani, M.A.A.; Aytekin, U.

    1999-01-01

    In this study, the removal of uranium from aqueous solutions by diatomite earth (Kieselguhr) fine particles has been investigated. Diatomite earth is an important absorbent material in chromatographic studies. Uranium adsorption capacity of four different types of diatomite was determined. The adsorption of uranium on the chosen diatomite sample was examined as a function of uranium concentration, solution pH, contact time and temperature. The adsorption of uranium on diatomite followed a Langmuir-type isotherm. (author)

  7. Determination of Three-Dimensional Morphology and Inner Structure of Second-Phase Inclusions in Metals by Non-Aqueous Solution Electrolytic and Room Temperature Organic Methods

    Directory of Open Access Journals (Sweden)

    Jing Guo

    2018-01-01

    Full Text Available The secondary-phase particles in metals, particularly those composed of non-metallic materials, are often detrimental to the mechanical properties of metals; thus, it is crucial to control inclusion formation and growth. One of the challenges is determining the three-dimensional morphology and inner structures of such inclusions. In this study, a non-aqueous solution electrolytic method and a room-temperature organic technique were developed based on the principle of electrochemistry to determine the three-dimensional morphologies and inner structures of non-metallic inclusions in Al-killed steel, Si-killed steel, and ductile cast iron. The inclusions were first extracted without any damage to the inclusions, and then the collected inclusions were wrapped and cut through Cu ion deposition. The results revealed that the inclusions in Al-killed steel had an irregular morphology, that those in the Si-killed steel were mainly spherical, and that almost all the spheroidal graphite in the ductile cast iron featured a uniform globular morphology. In addition, nucleation was not observed in the inner structures of the inclusions in the Al-killed steel, while some dendritic or rod-like MnS phase precipitates appeared on the silicate inclusion surfaces, and some silicate-rich phases were detected in their inner matrix. For spheroidal graphite, rare-earth oxides (one particle or more were observed as nuclei in the center of almost every graphite particle. The formation and evolution of inclusions in these types of metals can be better understood by means of the two developed methods.

  8. Sm doped mesoporous CeO2 nanocrystals: aqueous solution-based surfactant assisted low temperature synthesis, characterization and their improved autocatalytic activity.

    Science.gov (United States)

    Mandal, Bappaditya; Mondal, Aparna; Ray, Sirsendu Sekhar; Kundu, Amar

    2016-01-28

    Mesoporous Sm(3+) doped CeO2 (Ce-Sm) with a nanocrystalline framework, a high content of Ce(3+) and surface area (184 m(2) g(-1)), have been synthesized through a facile aqueous solution-based surfactant assisted route by using inorganic precursors and sodium dodecyl sulphate as a template. The XRD results indicate that the calcined Ce-Sm and even the as-prepared material have a cubic fluorite structure of CeO2 with no crystalline impurity phase. XRD studies along with HRTEM results confirmed the formation of mesoporous nanocrystalline CeO2 at a lower temperature as low as 100 °C. A detailed analysis revealed that Sm(3+) doping in CeO2 has increased the lattice volume, surface area, mesopore volume and engineered the surface defects. Higher concentrations of Ce(3+) and oxygen vacancies of Ce-Sm resulted in lowering of the band gap. It is evident from the H2-TPR results that Sm(3+) doping in CeO2 strongly modified the reduction behavior of CeO2 by shifting the bulk reduction at a much lower temperature, indicating increased oxygen mobility in the sample which enables enhanced oxygen diffusion at lower temperatures, thus promoting reducibility, i.e., the process of Ce(4+)→ Ce(3+). UV-visible transmission studies revealed improved autocatalytic performance due to easier Ce(4+)/Ce(3+) recycling in the Sm(3+) doped CeO2 nanoparticles. From the in vitro cytotoxicity of both pure CeO2 and Sm(3+) doped CeO2 calcined at 500 °C in a concentration as high as 100 μg mL(-1) (even after 120 h) on MG-63 cells, no obvious decrease in cell viability is observed, confirming their excellent biocompatibility. The presence of an increased amount of surface hydroxyl groups, mesoporosity, and surface defects have contributed towards an improved autocatalytic activity of mesoporous Ce-Sm, which appear to be a potential candidate for biomedical (antioxidant) applications.

  9. Molecular mechanism of the viscosity of aqueous glucose solutions

    Science.gov (United States)

    Bulavin, L. A.; Zabashta, Yu. F.; Khlopov, A. M.; Khorol'skii, A. V.

    2017-01-01

    Experimental relations are obtained for the viscosity of aqueous glucose solutions in the temperature range of 10-80°C and concentration range 0.01-2.5%. It is found that the concentration dependence of fluidity is linear when the concentration is higher than a certain value and varies at different temperatures. The existence of such a dependence indicates that the mobilities of solvent and solute molecules are independent of the concentration of solutions. This assumption is used to construct a theoretical model, in which the structure of an aqueous glucose solution is presented as a combination of two weakly interacting networks formed by hydrogen bonds between water molecules and between glucose molecules. Theoretical relations are obtained using this model of network solution structure for the concentration and temperature dependence of solution viscosity. Experimental data are used to calculate the activation energies for water ( U w = 3.0 × 10-20 J) and glucose molecules ( U g = 2.8 × 10-20 J). It is shown that the viscosity of a solution in such a network structure is governed by the Brownian motion of solitons along the chains of hydrogen bonds. The weak interaction between networks results in the contributions to solution fluidity made by the motion of solitons in both of them being almost independent.

  10. Luminescence properties of tetravalent uranium in aqueous solution

    International Nuclear Information System (INIS)

    Kirishima, A.; Kimura, T.; Nagaishi, R.; Tochiyama, O.

    2004-01-01

    The luminescence spectra of U 4+ in aqueous solutions were observed in the UV-VIS region at ambient and liquid nitrogen temperatures. The excitation spectrum indicates that the luminescence is arising from the deexcitation of a 5f electron at the 1 S 0 level and no other emissions of U 4+ in aqueous solutions were detected for other f-f transitions. All the luminescence peaks were assigned to the transitions from 1 S 0 to lower 5f levels. To estimate the luminescence lifetime, luminescence decay curves were measured using time-resolved laser-induced fluorescence spectroscopy. At room temperature, the decay curve indicated that the lifetime was shorter than 20 ns. On the other hand, the frozen sample of U 4+ in aqueous solution at liquid nitrogen temperature showed the same emission spectrum as at room temperature and its lifetime was 149 ns in H 2 O system and 198 ns in D 2 O system. The longer lifetime at liquid nitrogen temperature made it possible to measure the spectrum of U 4+ at the concentration as low as 10 -6 M. The difference in the anion species (ClO 4 - , Cl - , SO 4 2- ) affected the structure of the emission spectrum to some extent. (orig.)

  11. 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.

  12. Radiolysis of anthraquinone dyes in aqueous solutions

    International Nuclear Information System (INIS)

    Vysotskaya, N.A.; Bortun, L.N.; Ogurtsov, N.A.; Migdalovich, E.A.; Revina, A.A.; Volodko, V.V.; AN SSSR, Moscow. Inst. Ehlektrokhimii)

    1986-01-01

    The commercial anthraquinone dyes (Dark Blue, Light Blue, Green) in aqueous solutions were shown to be decoloured and degrade under the action of ionizing radiation. The degree of decolouration and degradation of aromatic rings was found to increase in presence of oxygen. Hydroxyl radicals were shown to play the key role in the degradation of the dyes under irradiation. The radiolysis intermediate products were studied using the pulse radiolysis technique. (author)

  13. 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.

  14. 21 CFR 524.1200b - Kanamycin ophthalmic aqueous solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Kanamycin ophthalmic aqueous solution. 524.1200b... § 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...

  15. Aggregation of sodium alkylbenzenesulfonates in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Magid, L.J.; Shaver, R.J.; Gulari, E.; Bedwell, B.; Alkhafaji, S.

    1981-01-01

    The surfactant 6 phenyl C/sub 12/SNa forms small spherical micelles in aqueous solution, having an aggregation number of 20 to 30 and a fractional charge of 0.45. These micelles are hydrated to the extent of approximately 18 moles H/sub 2/O per moles of surfactant. A second larger aggregate is also present in 6 phenyl C/sub 12/SNa solutions; its importance increases with solution age. Addition of NaCl causes both aggregates to apparently increase modestly in size. The surfactant 8 phenyl C/sub 16/SNa also contains both aggregates in its solutions; the larger one is relatively more important here. The larger aggregate does not correspond to dispersed bits of a liquid crystalline mesophase.

  16. 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.

  17. 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.

  18. Effects of Radiosterilization on Sealed Aqueous Solutions

    International Nuclear Information System (INIS)

    Pandula, E.L.; Farkas, E.; Rácz, I.

    1967-01-01

    For aqueous solutions sensitive to heat,and in connection with the use of plastic ampoules, the need for applying radiosterilization is growing. Studying the possibilities of radiosterilization, experiments were made with the following: 0.1% atropine, 1.0% morphine, and 2% lidocain in aqueous solutions. The aim of the work was to establish whether the active ingredients of the injections suffer decomposition or not, to study the factors influencing the degradation and, furthermore, to make attempts to prevent decomposition. The samples were irradiated by 420 Ci 60 Co γ-radiation source. The applied doses were 1 to 2.5 Mrad, with a 10 4 to 2.5 x 10 5 rad/h dose intensity. After irradiation the change in colour, pH-value, concentration and UV-spectra were studied. Changes of the last three types were found. Studying the factors influencing decomposition it has been found that the degree of degradation was increased by the increase of radiation dose, increase of concentration, decrease of dose intensity, and increase of oxygen content in the atmosphere over the solution. Attempts were made to prevent degradation. Solutions were prepared with sulphite, ascorbic acid, and AET, and some measure of success was achieved, especially with the sulphite addition. (author)

  19. Sonolysis of chlorinated compounds in aqueous solution.

    Science.gov (United States)

    Lim, Myung Hee; Kim, Seung Hyun; Kim, Young Uk; Khim, Jeehyeong

    2007-02-01

    To examine the reaction rates of sonochemical degradation of aqueous phase carbon tetrachloride, trichloroethylene and 1,2,3-trichloropropane at various temperatures, power intensities, and saturating gases, the batch tests were carried out. The degradations of chlorinated hydrocarbons were analyzed as pseudo first order reactions and their reaction rate constants were in the range of 10(-1)-10(-3)/min. The reaction was fast at the low temperature with higher power intensity. Also, the reaction went fast with the saturating gas with high specific heat ratio, high solubility and low thermal conductivity. The main mechanism of destruction of chemicals was believed the thermal combustion in the bubble.

  20. Volumetric studies of some amino acids in binary aqueous solutions ...

    Indian Academy of Sciences (India)

    Unknown

    0 values of glycine, L-alanine, and L-valine in aqueous MgCl2⋅6H2O solutions at. 298⋅15 K in order to describe the temperature dependence behaviour of partial molar quantities. Group contributions to partial molar volumes have been determined for the amino acids. The trends of transfer volumes (∆Vφ. 0) have been ...

  1. ISOCHORIC HEAT CAPACITY OF 1% AQUEOUS SOLUTION OF MAGNESIUM CHLORIDE

    Directory of Open Access Journals (Sweden)

    V. I. Dvoryanchikov

    2016-01-01

    Full Text Available Aim. The aim is to conduct an experimental study of isochoric heat capacity of 1% aqueous solution of magnesium chloride along the phase boundary curve.Method. In order to determine the isochoric heat capacity at the phase boundary curve we used the adiabatic calorimeter of KH. I. Amirkhanov.Results. Results of the study of the isochoric heat capacity depending on the temperature are given in tables and figures; the findings are compared with those of other researchers. When evaluating a complex system, we ought not to evaluate its effectiveness on the basis of only one criterion, even a very important, in this case must take into account the requirements of the technical, economic, environmental and of other natures.Conclusions. When solving optimization problems of efficiency in geothermal energy it is necessary to take into account the fact of the temperature dependence of the heat and density. The temperature dependence of the density and heat capacity in the calculations significantly affect the value of the efficiency criterion to be taken into account, otherwise the calculation error can be up to 20%. The data obtained from the isochoric heat capacity of aqueous solutions of magnesium chloride is compared with the data for water and aqueous solutions of NaCl and NaOH, obtained previously, which may be represented as a model of geothermal and sea water.

  2. NIR spectroscopic properties of aqueous acids solutions.

    Science.gov (United States)

    Omar, Ahmad Fairuz; Atan, Hanafi; Matjafri, Mohd Zubir

    2012-06-15

    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.

  3. Density, Viscosity, Solubility, and Diffusivity of N2O in Aqueous Amino Acid Salt Solutions

    NARCIS (Netherlands)

    Kumar, P. Senthil; Hogendoorn, J.A.; Feron, P.H.M.; Versteeg, G.F.

    2001-01-01

    Solubility and diffusivity of N2O in aqueous solutions of potassium taurate are reported over a wide range of concentration and temperature. Also, the solubility of N2O in aqueous potassium glycinate solution is reported at 295 K. The ion specific constants are reported for taurate and glycinate

  4. Surface tension of aqueous electrolyte solutions. Thermodynamics

    NARCIS (Netherlands)

    Drzymala, J.; Lyklema, J.

    2012-01-01

    A thermodynamic theory is developed for obtaining the enthalpic and entropic contributions to the surface excess Gibbs energy of electrolyte solutions from the dependence of the surface tension on concentration and temperature. For elaboration, accurate activity coefficients in solution as functions

  5. Radiation-induced nitration of organic compounds in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Ershov, B.G.; Gordeev, A.V.; Bykov, G.L. [Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Inst. of Physical Chemistry and Electrochemistry; Moisy, P. [CEA, Bagnols sur Ceze (France). Nuclear Energy Div.

    2012-07-01

    Radiolysis in aqueous nitrate and acetic acid solutions and nitrate/nitric acid and phenol was studied. The radiolysis of these solutes occurs with {sup circle} NO{sup 2} radical, which is the active nitrating agent. Accumulation of nitromethane and nitrite was determined during {gamma}-irradiation of aqueous solutions containing acetic and nitrate solutions. Irradiation of aqueous phenol-nitrate/nitric acid solutions results in the formation of 2- and 4-nitrophenols.

  6. Gamma irradiation of coumarin in aqueous solution

    International Nuclear Information System (INIS)

    Gopakumar, K.; Kini, U.R.; Ashawa, S.C.; Bhandari, N.S.; Krishnan, G.U.; Krishnan, D.

    1977-01-01

    Aqueous solutions of coumarin become fluorescent on gamma irradiation. The main fluorescent product formed, 7-hydroxy coumarin, shows a dependence on oxygen. The yield in the presence of oxygen is three times that in the nitrogen saturated condition. The effect of cysteine, dimethyl sulfoxide, thymine and sodium nitrite on the gamma response of coumarin suggests the involvement of hydroxyl radicals in the formation of the fluorescent product. The hydroxyl rate constant for coumarin was determined using isopropanol as the co-competitor. The G (-coumarin) in the aerated and nitrogen saturated conditions was also determined. (author)

  7. Radiosensitization of thymidine in deaerated aqueous solution

    International Nuclear Information System (INIS)

    Berger, Maurice.

    1982-09-01

    This work investigates the mode of action of various radiosensitizing agents on the radio-induced degradation of thymidine in deaerated aqueous solution. A special effort was devoted to the separation of addition products formed by one of these substances (a stable nitroxide radical: TAN) with the radio-induced neutral radicals of thymidine. The complex mixture of different diastereoisomers resulting from the covalent addition of the TAN molecule on the thymidine carbons C (5) or C (6) was resolved by HPLC. The structural determination of these adducts (absolute configuration) was achieved by various spectroscopic techniques and specific chemical syntheses. A conformational study has been undertaken [fr

  8. The Krafft temperature of surfactant solutions

    Directory of Open Access Journals (Sweden)

    Manojlović Jelena Ž.

    2012-01-01

    Full Text Available Our main motivation to revisit the solution properties of cetyltrimethylammonium bromide is related to the clear requirement for better control of the adsorption parameters to form uniform self-assembled monolayers on muscovite mica substrates. To readily monitor the temporal evolution of structural details in cetyltrimethylammonium bromide solutions, we realized a rather simple conductivity experiment. Conductivity measurements were carried out as a function of temperature, to look closer into the Krafft temperature behavior of this surfactant. We measured the electrical conductivity of different concentrations of aqueous cetyltrimethylammonium bromide solutions, below and above the critical micells concentration.

  9. RECOVERY OF ACTINIDES FROM AQUEOUS NITRIC ACID SOLUTIONS

    Science.gov (United States)

    Ader, M.

    1963-11-19

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

  10. Principles of interactions in non-aqueous electrolyte solutions

    NARCIS (Netherlands)

    Lyklema, J.

    2013-01-01

    In this paper a review is presented on the molecular interactions in non-aqueous media of low dielectric permittivity. Qualitative and quantitative distinctions with aqueous solutions are emphasized. The reviewed themes include dispersion forces, dissociation and association equilibria,

  11. Process for disposal of aqueous solutions containing radioactive isotopes

    International Nuclear Information System (INIS)

    Colombo, P.; Neilson, R.M. Jr.; Becker, W.W.

    1979-01-01

    A process for disposing of radioactive aqueous waste solutions whereby the waste solution is utilized as the water of hydration to hydrate densified powdered portland cement in a leakproof container; said waste solution being dispersed without mechanical inter-mixing in situ in said bulk cement, thereafter the hydrated cement body is impregnated with a mixture of a monomer and polymerization catalyst to form polymer throughout the cement body. The entire process being carried out while maintaining the temperature of the components during the process at a temperature below 99 0 C. The container containing the solid polymer-impregnated body is thereafter stored at a radioactive waste storage dump such as an underground storage dump

  12. Process for disposal of aqueous solutions containing radioactive isotopes

    International Nuclear Information System (INIS)

    Colombo, P.; Neilson, R.M. Jr.; Becker, W.W.

    1979-01-01

    A process for disposing of radioactive aqueous waste solution in which the waste solution is utilized as the water of hydration to hydrate densified powdered portland cement in a leakproof container is described. The waste solution is dispersed without mechanical inter-mixing in situ in the bulk cement. Thereafter the hydrated cement body is impregnated with a mixture of a monomer and polymerization catalyst to form polymer throughout the cement body. The entire process is carried out while the temperature of the components during the process is maintained at a temperature below 99 0 C. The container containing the solid polymerimpregnated body is thereafter stored at a radioactive waste storage dump such as an underground storage dump

  13. The Influence of pH and Temperature on the Stability of N-[(Piperidinemethylene]daunorubicin Hydrochloride and a Comparison of the Stability of Daunorubicin and Its Four New Amidine Derivatives in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Mikołaj Piekarski

    2014-01-01

    Full Text Available The influence of pH and temperature on the stability of N-[(piperidinemethylene]daunorubicin hydrochloride (PPD was investigated. Degradation was studied using an HPLC method. Specific acid-base catalysis of PPD involves hydrolysis of protonated molecules of PPD catalyzed by hydrogen ions and spontaneous hydrolysis under the influence of water zwitterions, unprotonated molecules, and monoanions of PPD. The thermodynamic parameters of these reactions, energy, enthalpy, and entropy, were calculated. Also, the stability of daunorubicin and its new amidine derivatives (piperidine, morpholine, pyrrolidine, and hexahydroazepin-1-yl in aqueous solutions was compared and discussed.

  14. Chemical metallization of KMPR photoresist polymer in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Zeb, Gul [MiQro Innovation Collaborative Centre (C2MI), 45, boul. de l' Aéroport, Bromont, QC, J2L 1S8 (Canada); Mining & Materials Engineering, McGill University, 3610,University Street, Montreal, QC, H3A 0C5 (Canada); Duong, Xuan Truong [Department of Mechanical Engineering, Ecole polytechnique de Montréal, Montréal, QC, H3C 3T5 (Canada); Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam); Vu, Ngoc Pi; Phan, Quang The; Nguyen, Duc Tuong; Ly, Viet Anh [Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam); Salimy, Siamak [ePeer Review LLC, 145 Pine Haven Shores Rd, Suite 1000-X, Shelburne, VT 05482 (United States); Le, Xuan Tuan, E-mail: xuantuan.le@teledyne.com [MiQro Innovation Collaborative Centre (C2MI), 45, boul. de l' Aéroport, Bromont, QC, J2L 1S8 (Canada); Thai Nguyen University of Technology, 3-2 Street, Thai Nguyen City (Viet Nam)

    2017-06-15

    Highlights: • Electroless deposition of Ni-B film on KMPR photoresist polymer insulator with excellent adhesion has been achieved. • This metallization has been carried out in aqueous solutions at low temperature. • Polyamine palladium complexes grafts serve as seeds for the electroless plating on KMPR. • This electroless metallization process is simple, industrially feasible, chromium-free and environment-friendly. - Abstract: While conventional methods for preparing thin films of metals and metallic alloys on insulating substrates in the field of microelectromechanical systems (MEMS) include vapor deposition techniques, we demonstrate here that electroless deposition can be considered as an alternate efficient approach to metallize the surface of insulating substrates, such as KMPR epoxy photoresist polymer. In comparison with the physical and chemical vapor deposition methods, which are well-established for metallization of photoresist polymers, our electroless nickel plating requires only immersing the substrates into aqueous solutions in open air at low temperatures. Thin films of nickel alloy have been deposited electrolessly on KMPR surface, through a cost-effective and environmental chromium-free process, mediated through direct grafting of amine palladium complexes in aqueous medium. This covalent organic coating provides excellent adhesion between KMPR and the nickel film and allows better control of the palladium catalyst content. Covalent grafting and characterization of the deposited nickel film have been carried out by means of Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy techniques.

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

    Science.gov (United States)

    Hou, Deyin; Wang, Jun; Sun, Xiangcheng; Luan, Zhaokun; Zhao, Changwei; Ren, Xiaojing

    2010-05-15

    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 microg/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. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  16. Formation and disappearance of superoxide radicals in aqueous solutions

    International Nuclear Information System (INIS)

    Allen, A.O.; Bielski, B.H.J.

    1980-01-01

    A literature review of superoxide radicals in aqueous solutions is presented covering the following: history; methods of formation of aqueous HO 2 /HO 2 - by radiolysis and photolysis, electrolysis, mixing nonaqueous solutions into water, chemical reactions, enzymatic generation of O 2 - , and photosensitization; and properties of HO 2 /O 2 - in aqueous solution, which cover spontaneous dismutation rates, pk and absorption spectra, catalyzed dismutation, thermodynamics and the so-called Haber-Weiss Reaction

  17. Effect of sodium acetate on the volumetric behaviour of some mono-, di-, and tri-saccharides in aqueous solutions over temperature range (288.15 to 318.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Banipal, Parampaul K., E-mail: pkbanipal@yahoo.co [Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India); Singh, Vickramjeet [Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India); Banipal, Tarlok S. [Department of Applied Chemistry, Guru Nanak Dev University, Amritsar 143 005 (India)

    2010-01-15

    The standard partial molar volumes, V{sub 2}{sup 0} at infinite dilution of eight monosaccharides [D(+)-xylose, D(-)-arabinose, D(-)-ribose, L(-)-sorbose, D(-)-fructose, D(+)-galactose, D(+)-glucose, and D(+)-mannose], six disaccharides [D(+)-cellobiose, sucrose, D(+)-melibiose, D(+)-lactose monohydrate, D(+)-trehalose dihydrate, and D(+)-maltose monohydrate] and two trisaccharides [D(+)-melizitose and D(+)-raffinose pentahydrate] (molalities of saccharides range from (0.03 to 0.12) mol . kg{sup -1}) have been determined in water and in (0.5, 1.0, 2.0, and 3.0) mol . kg{sup -1} aqueous sodium acetate solutions at temperatures, T = (288.15, 298.15, 308.15, and 318.15) K from density measurements using a vibrating-tube digital densimeter. From these results, corresponding standard partial molar volumes of transfer, DELTA{sub t}V{sub 2}{sup 0} have been determined for the transfer of various saccharides from water to aqueous solutions of sodium acetate. Positive values of DELTA{sub t}V{sub 2}{sup 0} were obtained for most of the saccharides, whose magnitude increase with the concentration of sodium acetate as well as temperature. However, negative DELTA{sub t}V{sub 2}{sup 0} values were observed for L(-)-sorbose, D(-)-fructose and D(+)-xylose at lower concentrations of co-solute. The negative magnitude of DELTA{sub t}V{sub 2}{sup 0} values decrease with rise of temperature from (288.15 to 318.15) K. Pair and higher order volumetric interaction coefficients have been determined by using McMillan-Mayer theory. Partial molar expansion coefficients, (partial derivV{sub 2}{sup 0}/partial derivT){sub p} and the second derivatives (partial deriv{sup 2}V{sub 2}{sup 0}/partial derivT{sup 2}){sub p} have also been estimated. These parameters have been utilized to understand various mixing effects in aqueous solutions due to the interactions between solute (saccharide) and co-solute (sodium acetate).

  18. Radiation chemistry of aqueous solutions of cyanamide

    International Nuclear Information System (INIS)

    Draganic, Z.D.; Draganic, I.G.; Jovanovic, S.V.

    1978-01-01

    Oxygen-free aqueous solutions of 0.1 M NH 2 CN (pH 2.4 and 5) were irradiated with γ rays (0.01--25 Mrad). The rate constants determined in competition experiments are: k(H + NH 2 CN) = 6.7 x 10 6 M -1 sec -1 , k(e/sub aq/ - + NH 2 CN) = 1.5 x 10 9 M -1 sec -1 , and k(OH + NH 2 CN) = 8.5 x 10 6 M -1 sec -1 . Radiation-chemical yields were determined for the decomposition of cyanamide molecules and the formation of several radiolytic products. The following compounds were identified in irradiated solutions: H 2 , CO 2 , NH 3 , urea, biuret, arginine, and a--N=N-- molecule assigned to methylaminoazoformamide. Possible reactions of secondary free radicals leading to the formation of radiolytic products were considered by taking into account the model of water radiolysis and the measured radiation yields

  19. Aqueous Solution Thermal Conductivity of Beryllium-Subgroup Metal Chlorides

    Directory of Open Access Journals (Sweden)

    K. M. Abdullayev

    2013-01-01

    Full Text Available The paper presents experimental data on thermal conductivity of BeCl2 and SrCl2 salt aqueous solutions in the temperature range from 20 to 300 °С  and at various electrolyte concentrations  in mass percent. For the first time thermal conductivity of the system Н2О + BeCl2 has been investigated at high temperatures.The experimental results are described with the help of an empirical equation in the form of: λs = λo (1+ Am + Bm3/2 + Cm2,where λs  and λo – thermal conductivity coefficients of solution and water; A, B and C – coefficients depending on electrolyte nature; m – molality in units mol/kg.The formula error is less than  ±1 %.

  20. ISOCHORIC HEAT CAPACITY OF 1% AQUEOUS SOLUTION OF MAGNESIUM CHLORIDE

    OpenAIRE

    V. I. Dvoryanchikov; D. K. Djavatov; G. A. Rabadanov; E. G. Iskenderov; D. P. Shikhakhmedova

    2016-01-01

    Aim. The aim is to conduct an experimental study of isochoric heat capacity of 1% aqueous solution of magnesium chloride along the phase boundary curve.Method. In order to determine the isochoric heat capacity at the phase boundary curve we used the adiabatic calorimeter of KH. I. Amirkhanov.Results. Results of the study of the isochoric heat capacity depending on the temperature are given in tables and figures; the findings are compared with those of other researchers. When evaluating a comp...

  1. Kinetics of synthesis of monomeric betaines in aqueous solutions

    Science.gov (United States)

    Kazantsev, O. A.; Baruta, D. S.; Kamorin, D. M.; Shirshin, K. V.; Shirshin, K. K.; Kolosov, E. S.

    2016-05-01

    In the nucleophilic addition of N-(3-dimethylaminopropyl)methacrylamide to acrylic acid (1 : 1) in aqueous solutions, forming monomeric β-propiobetaine, the dependence of the initial rate on the starting reagent concentration was found to have a pronounced maximum (whose position does not depend on the temperature at 30-70°C). In the case of the addition of N, N-dimethylaminoethyl methacrylate, the dependence was exponential. The dependences of equilibrium conversions on the starting reagent concentrations were of the same type and had a maximum for both systems. The detected concentration effects are related to the peculiarities of the pre-reaction association of the reagents.

  2. Interaction of indium trichloride with calcium carbonate in aqueous solutions

    International Nuclear Information System (INIS)

    Kochetkova, N.V.; Toptygina, G.M.; Soklakova, O.V.; Evdokimov, V.I.

    1991-01-01

    Interaction of indium trichloride with calcium carbonate in aqueous solutions was studied, using methods of potentiometry, isothermal solubility and physicochemical computer simulating. The Gibb's energy value for crystal indium trihydroxide formation was calculated on the basis of experimental data on In(OH) 3 solubility. The value obtained was used for estimating equilibrium composition of InCl 3 -HCl-CaCO 3 -CO 2 -H 2 O system at a temperature of 25 deg C and carbon dioxide partial pressure of 0.05 to 1 at

  3. Opto-electrochemical spectroscopy of metals in aqueous solutions

    International Nuclear Information System (INIS)

    Habib, K.

    2016-01-01

    In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance–emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0%–2.5% H 2 SO 4 ) at room temperature. In the meantime, the real time holographic interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0%, 1.5%, 2.0%, and 2.5% H 2 SO 4 solutions. The electrical resistance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions.

  4. Opto-electrochemical spectroscopy of metals in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Habib, K., E-mail: khaledhabib@usa.net [Materials Science and Photo-Electronics Laboratory, IRE Program, EBR Center KISR, P.O. Box 24885, Safat 13109 (Kuwait)

    2016-03-15

    In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance–emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0%–2.5% H{sub 2}SO{sub 4}) at room temperature. In the meantime, the real time holographic interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0%, 1.5%, 2.0%, and 2.5% H{sub 2}SO{sub 4} solutions. The electrical resistance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions.

  5. Removal of hexavalent chromium from aqueous solution using ...

    African Journals Online (AJOL)

    Removal of hexavalent chromium from aqueous solution using activated carbon derived from palmyra palm fruit seed. A. Kannan, S. Thambidurai. Abstract. In this study, removal of chromium(VI) from aqueous solutions by Palmyra palm fruit seed carbon (PPFSC) and commercial activated carbon (CAC) was investigated.

  6. Acetic acid extraction from aqueous solutions using fatty acids

    NARCIS (Netherlands)

    IJmker, H.M.; Gramblicka, M.; Kersten, Sascha R.A.; van der Ham, Aloysius G.J.; Schuur, Boelo

    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

  7. Enthalpy of solution of biuret in various aqueous electrolyte solutions and in an urea solution

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Hisashi; Murakami, Sachio (Osaka City Univ. (Japan))

    1989-06-30

    Enthalpies of biuret which is simplest amido acid and does not have hydrophobic group, in various aqueous solutions and in urea solution were measured at 298.15K to clarify the influence of salt on polymer conformal changes of organism or structure and functions of membrane. The isoperibol calorimeter where the quartz thermometer was used as the thermal sensor, was used in the measurement. The performance of this calorimeter was tested by comparing measurements with values in references. From the analysis of enthalpies of biuret solutions, following results of solute-solute-solvent interactions could be obtained: the rate where biuret destroys water structure is smaller in salt solutions than in aqueous solutions and the tendency depends on the ion size; ion-water interaction weakens owing to the ion-biuret interaction in salt solution of biuret; and water molecules are made free. 25 refs., 4 figs., 5 tabs.

  8. Removal of radium from aqueous solutions

    International Nuclear Information System (INIS)

    Chintawongvanich, P.

    1982-05-01

    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 -5 C 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 X 1 - 0.014 X 2 + 0.140 X 3 + 0.007 X 1 X 2 )/1 + (3.744 - 0.767 X 3 + 0.079 X 1 X 2 )C 1 25 . 15 figures, 11 tables

  9. Beryllium Chelation by Dicarboxylic Acids in Aqueous Solution.

    Science.gov (United States)

    Schmidt, Michael; Bauer, Andreas; Schmidbaur, Hubert

    1997-05-07

    Maleic and phthalic acids are found to react with Be(OH)(2), generated in situ from BeSO(4)(aq) and Ba(OH)(2)(aq), in aqueous solution at pH 3.0 or 4.4, respectively (25 degrees C), to give solutions containing the complexes (H(2)O)(2)Be[(OOCCH)(2)] (1) and (H(2)O)(2)Be[(OOC)(2)C(6)H(4)] (3). The products can be isolated in high yield and identified by microanalytical data. With 2 equiv of the dicarboxylic acids and the pH adjusted to 5.5 and 5.9, respectively, by addition of ammonia, the bis-chelate complexes [(NH(4))(+)](2){[Be[(OOCCH)(2)](2)}(2)(-) (2) and [(NH(4))(+)](2){Be[(OOC)(2)C(6)H(4)](2)}(2)(-) (4) are obtained, which can also be isolated. The compounds show distinct (9)Be, (1)H, and (13)C resonances in their NMR spectra in aqueous solutions. Layering of an aqueous solution of compound 4 with acetone at ambient temperature leads to the precipitation of single crystals suitable for an X-ray structure determination. This salt (5) was found to contain the bis-chelated dianion {Be[(OOC)(2)C(6)H(4)](2)}(2)(-) with the beryllium atom in the spiro center of two seven-membered rings and an overall geometry approaching closely C(2) symmetry. These anions are associated with two crystallographically independent but structurally similar counterions [MeC(O)CH(2)CMe(2)NH(3)](+), which are the product of a condensation reaction of the ammonium cation with the acetone solvent. In the crystal the ammonium hydrogen atoms of the cations form N-H.O hydrogen bonds with the oxo functions of the dianion.

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

    Science.gov (United States)

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

    2013-01-01

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

  11. Simple quantification of ultrasonic intensity using aqueous solution of phenolphthalein.

    Science.gov (United States)

    Rong, L; Kojima, Y; Koda, S; Nomura, H

    2001-01-01

    Aqueous phenolphthalein solution under sonication was investigated for use as a chemical dosimeter. The fading time of aqueous phenolphthalein solution under sonication depended on the concentration of phenolphthalein and the pH values of solutions. The fading time was correlated to the ultrasonic intensity in a reaction vessel that is estimated on the basis of decomposition of porphyrin. The relation between the fading time and the ultrasonic intensity for different frequencies is expressed by a single curve. From these results, it is indicated that aqueous solutions of phenolphthalein is useful for simple quantification of ultrasonic intensity for practical use, and one can regard it as one of the ultrasonic intensity indicators.

  12. Study of the physicochemical properties of the interface between titanium dioxide and various aqueous solutions

    International Nuclear Information System (INIS)

    Mazilier, C.

    1988-01-01

    The aim of this work is the study of ion exchange capacity of titanium dioxide in view of high temperature water purification and radioactive effluent processing because of its resistance to heat and radiations. Titanium dioxide is obtained by alkaline hydrolysis of an aqueous solution of Ti (IV) and is characterized by analytical physical chemistry methods. Interface between Ti0 2 and simple aqueous solutions (electrolytes) is more particularly studied by potentiometry [fr

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

    Science.gov (United States)

    Suzuki, Yoshiharu

    2017-08-14

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

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

    Science.gov (United States)

    Suzuki, Yoshiharu

    2017-08-01

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

  15. Neutron studies of paramagnetic fullerenols’ assembly in aqueous solutions

    Science.gov (United States)

    Lebedev, V. T.; Szhogina, A. A.; Suyasova, M. V.

    2018-03-01

    Recent results on structural studies of aqueous solutions of water-soluble derivatives of endofullerenes encapsulating 4f- and 3d-elements have been presented. Neutron small angle scattering experiments allowed recognize subtle features of fullerenols assembly as dependent on chemical nature (atomic number) of interior atom, pH-factor and temperature of solutions. It was observed a fractal-type fullerenols’ ordering at the scale of correlation radii ∼ 10-20 nm when molecules with iron atoms are integrated into branched structures at low concentrations (C ≤ 1 % wt.) and organized into globular aggregates at higher amounts (C > 1 % wt.). On the other hand, for Lanthanides captured in carbon cages the supramolecular structures are mostly globular and have larger gyration radii ∼ 30 nm. They demonstrated a good stability in acidic (pH ∼ 3) and neutral (pH ∼ 7) media that is important for forthcoming medical applications.

  16. 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

  17. Reverse osmosis separation of radium from dilute aqueous solutions

    International Nuclear Information System (INIS)

    Subramanian, K.S.; Sastri, V.S.

    1980-01-01

    Porous cellulose acetate membranes obtained from Osmonics Inc. were characterized in terms of pure water permeability constant, solute transport parameter, and mass transfer coefficient with aqueous sodium chloride solution as the reference system. Reverse osmosis separation behavior of radium-226 as nitrate, chloride, and sulfate salts was studied. Reverse osmosis method of removing radium-226 from aqueous solutions has been compared with other methods, and it has been shown to be one of the best methods for alleviating radium contamination problems

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

    Science.gov (United States)

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

    2017-08-01

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

  19. 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 2ppm 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 ∼10(4)s(-1) at pH 7.4 and 37°C, the activation energy, 50.2kJ/mol and its pH dependence at 1.1°C was fitted to: k (s(-1))=520+6.5×10(7)[H(+)]+3.0×10(9)[OH(-)]. Copyright © 2014. Published by Elsevier Inc.

  20. Biosorptive removal of cobalt (II) ions from aqueous solution by ...

    African Journals Online (AJOL)

    hope&shola

    2010-11-29

    Nov 29, 2010 ... African Journal of Biotechnology Vol. ... an alternative to high cost commercial adsorbent materials for the removal of Co (II) from aqueous ..... J. Hazard. Mater. 137: 865-870. Han R, Zhang J, Zou W, Xiao H, Shi J, Liu H (2005). Biosorption of copper (II) and lead (II) from aqueous solution by chaff in a fixed- ...

  1. Viscosity of aqueous DNA solutions determined using dynamic light scattering.

    Science.gov (United States)

    Gilroy, Emma L; Hicks, Matthew R; Smith, David J; Rodger, Alison

    2011-10-21

    Viscosity is a key parameter for characterising the behaviour of liquids and their flow. It is, however, difficult to measure precisely, reproducibly and accurately for aqueous solutions on a micro-litre volume scale, which is what is usually needed for biological samples. We report the development of a new method for measuring dynamic viscosity by measuring dynamic light scattering (DLS) data for a range of particles of well-defined size. Most applications of DLS involve determining particle size for samples of known viscosity. We inverted the usual protocol and endeavoured to determine viscosity for samples of known particle size. Viscosity measurements for water and aqueous solutions of calf thymus DNA made using DLS were compared with those from a U-tube viscometer. The styrene particles, frequently used as particle size standards, gave unsatisfactory results for our DNA samples as did C-6 derivatized silica and positively charged amino polystyrene microspheres. However, negatively charged carboxylate polystyrene microspheres particles readily gave accurate viscosity measurements over a range of temperatures (0-100 °C). The sample volume required depends on the cuvette used to measure DLS, but can be performed with samples sizes ranging from 40 to 3000 μL. The sample can then be recovered for subsequent experiments. The DLS method is simple to perform at different temperatures and provides data of accuracy significantly above that of a U-tube viscometer. Our results also indicate a way forward to account accurately for solution viscosity in the normal applications of DLS to particle size determination by including the appropriate non-interacting particles as an internal standard.

  2. Corrosion inhibition of aqueous solutions of inorganic mineral acids

    Energy Technology Data Exchange (ETDEWEB)

    Stanford, J.R.

    1971-06-15

    A particularly corrosive use of mineral acids is the employment of 15% solutions and, in some instances, even more concentrated solutions of hydrochloric acid in oil well acidizing applications. It has been found that aqueous solutions of inorganic mineral acids, particularly hydrochloric acid solutions, may be inhibited against their corrosive tendencies toward ferrous metals by adding novel compositions of the invention whereby inhibited mineral acid aqueous solutions are provided. In its simplest embodiment the invention comprises using in combination the Mannich reaction products of a hydroabietyl amine, formaldehyde, and certain aliphatic aldehydes in combination with an acetylenic alcohol which contains from 3 to 12 carbon atoms. (7 claims)

  3. The enhanced anisotropic properties of the Fe sub 3 sub - sub x M sub x O sub 4 (M = Fe, Co, Mn) films deposited on glass surface from aqueous solutions at low temperature

    CERN Document Server

    Kim, T Y; Kim, Y I; Lee, C S; Park, J C; Kim, D

    2003-01-01

    The enhancement of structural anisotropy and magnetic anisotropy in ferrite films, Fe sub 3 sub - sub x M sub x O sub 4 (M = Fe, Co, Mn), which were deposited on glass substrates from aqueous solutions by thin liquid film (TLF) method at a low temperature (358 K), was compared in x-ray diffraction, conversion electron Moessbauer spectroscopy, and vibrating sample magnetometer measurements. The experimental results showed that the highly coercive Fe sub 3 sub - sub x Co sub x O sub 4 films, maximum coercivity of 0.21 T at room temperature, have a preferential growing direction along the magnetic easy axis of the magnetite, (111). While anisotropy was enhanced by the addition of Co sup 2 sup + ions in the reaction solution, no enhancement was observed in the TLF-films of Fe sub 3 O sub 4 and Fe sub 3 sub - sub x Mn sub x O sub 4. The enhanced anisotropy is probably caused by the extra stabilization energy of the Co sup 2 sup + ions in the octahedral sites of the spinel and the interactions between the Co sup 2 ...

  4. Reactions of alkylnitrosoureas in aqueous solution

    International Nuclear Information System (INIS)

    Snyder, J.K.; Stock, L.M.

    1980-01-01

    The acid- and base-catalyzed decompositions of N-methyl-,N,N'-dimethyl-, and N,N',N'-trimethyl-N-nitrosourea in aqueous solution have been studied. Below pH 2, the N-methyl compound undergoes both denitrosation and hydrolysis to yield methylurea, nitrous acid, methylamine, nitrogen, and carbon dioxide. The acid-catalyzed denitrosation and hydrolysis of the trimethylnitrosourea are somewhat more rapid than the corresponding reactions of N-methyl-N-nitrosourea. The solvent isotope effect, k/sub H 2 O//k/sub D 2 O/ = 1.3, and the absence of chloride ion catalysis suggest that the denitrosation reaction proceeds by a rate-determining proton transfer which is followed by the rapid loss of the nitroso group. The results for the hydrolysis reaction are compatible with a formulation in which a hydrate of the nitrosourea is protonated in a rate-determining step to form a tetrahedral intermediate which subsequently decomposes to yield methyldiazonium hydroxide and a carbamic acid derivative. The base-catalyzed reactions of the mono, di-, and trimethylnitrosoureas are first order in hydroxide ion over a broad pH range. The hydrolysis of N-methyl-N-nitrosourea yields methanol and derivatives of carbamic acid. Salt effects on the reaction rate are negligible except for the influence of lithium ion. The rate constants for the hydrolysis of the mono- and dimethyl compounds depend upon the buffer concentrationat pH 9.5. The rate constants for the hydrolysis of the trimethyl compound also depend upon the buffer concentration, but a limiting value is not achieved. The solvent isotope effect for the base-catalyzed reaction, the exchange reaction of water- 18 O with the carbonyl group of the urea, and the fact that N-methyl-N-nitrosourea is hydrolyzed about 2.2 x 10 4 times more rapidly than N,N',N'-trimethyl-N-nitrosourea suggest that the hydrolysis occurs by a mechanism in which a tetrahedral intermediate is formed

  5. Investigation on Minimum Film Boiling Point of Highly Heated Vertical Metal Rod in Aqueous Surfactant Solution

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chi Young; Kim, Jae Han [Pukyong Nat’l Univ., Busan (Korea, Republic of)

    2017-09-15

    In this study, experiments were conducted on the MFB(minimum film boiling) point of highly heated vertical metal rod quenched in aqueous surfactant solution at various temperature conditions. The aqueous Triton X-100 solution(100 wppm) and pure water were used as the liquid pool. Their temperatures ranged from 77 °C to 100 °C. A stainless steel vertical rod of initial center temperature of 500 °C was used as a test specimen. In both liquid pools, as the liquid temperature decreased, the time to reach the MFB point decreased with a parallel increase in the temperature and heat flux of the MFB point. However, over the whole present temperature range, in the aqueous Triton X-100 solution, the time to reach the MFB point was longer, while the temperature and heat flux of the MFB point were reduced when compared with pure water. Based on the present experimental data, this study proposed the empirical correlations to predict the MFB temperature of a high temperature vertical metal rod in pure water and in aqueous Triton X-100 solution.

  6. 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.

  7. Thermodynamic properties of Sodium Dodecyl Sulfate aqueous solutions with Methanol, Ethanol, n-Propanol and iso-Propanol at different temperatures

    Directory of Open Access Journals (Sweden)

    Md. Abdul Motin

    2015-03-01

    The ΔH# values that are positive for all the studied systems indicate that positive work has to be done to overcome the energy barrier for the flow process. The variation of ΔS# is reversing the variation of the ΔH#. The excess parameters (ΔG#E, ΔH#E data have been fitted by the least square method to the four parameter Redlich–Kister equation and the values of the parameter aj have been reported. The observed increase of thermodynamic values in the aqueous SDS region are thought to be mainly due to the combined effect of hydrophobic hydration and hydrophilic effect.

  8. Biosorption of nickel (II) ions from aqueous solutions by tapioca peel ...

    African Journals Online (AJOL)

    Tapioca peel, waste from native tapioca starch industry in Thailand, was used for the biosorption of nickel from aqueous solution. The experimental parameter focuses on the influence of contact time, solution pH, initial concentration and temperature using batch experiments. The results indicated that the biosorption ...

  9. KINETICS OF THE HYDROXYPROPYLATION OF POTATO STARCH IN AQUEOUS-SOLUTION

    NARCIS (Netherlands)

    LAMMERS, G; STAMHUIS, EJ; BEENACKERS, AACM

    Kinetic results are presented for the hydroxypropylation of Potato starch with methyloxirane in aqueous solution. Reaction temperatures were varied from 303 to 362 K. Sodium hydroxide was used as a catalyst. The overall conversion rate of methyloxirane in alkaline starch solution is determined by

  10. Rapid synthesis of CdSe nanocrystals in aqueous solution at room ...

    Indian Academy of Sciences (India)

    Administrator

    Water-soluble thioglycolic acid-capped CdSe nanocrystals (NCs) were prepared in aqueous solu- tion at room temperature. We investigated the ... NCs dispersed in buffer solution (pH = 4⋅0). FTIR spectra were recorded on a ... the theory of acid-base equilibrium, the initial pH value of original solution determines the ...

  11. Adsorption of Pb(II) ions from aqueous solution using lignin from ...

    African Journals Online (AJOL)

    The adsorption of lead(II) ions from aqueous solution onto alkali lignin extracted from Hagenia abyssinica was investigated by electrochemical methods. The effect of solution pH, lignin dosage and contact time were investigated at room temperature in a batch system. Adsorption equilibrium was approached within 80 min.

  12. Separation of cesium from aqueous solutions using alkylated tetraaryl borates

    International Nuclear Information System (INIS)

    Feldmaier, F.

    1991-01-01

    The water solubility of cesium tetraaryl borates was lowered by introducing hydrophobic aliphatic side chains into corresponding acid-resistant fluorosubstituted tetraaryl borates. This improved cesium spearability both in precipitation and in extraction from aqueous solutions. (orig.) [de

  13. Preparation, assay and certification of aqueous ethanol reference solutions

    CSIR Research Space (South Africa)

    Archer, M

    2007-04-01

    Full Text Available Internationally, certified ethanol reference materials are required to calibrate breathalysers and blood-alcohol measurement instruments. The CSIR National Metrology Laboratory of South Africa provides certified aqueous ethanol solutions...

  14. 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

  15. γ-Irradiation-induced radiolysis of inulin in aqueous solutions

    International Nuclear Information System (INIS)

    Tsyba, I.A.; Revina, A.A.; Shostenko, A.G.

    1997-01-01

    Radiochemical transformations of inulin in aqueous solutions, in air, in the presence of inert gases, helium, nitrogen and in nitrous oxide exposed to various doses of 60 Co γ-irradiation were investigated. It was shown that interactions in inulin with OH radicals are principally responsible for radiolytic decomposition of inulin. The data on radiolysis of more simple model systems were used to make available decomposition spectra of γ-irradiated aerated aqueous solution of inulin. 9 refs., 6 figs

  16. 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.

  17. Adsorption of Mn(II) and Co(II) ions from aqueous solution using ...

    African Journals Online (AJOL)

    The adsorption of Mn(II) and Co(II) ions from aqueous solution was investigated using batch adsorption experiment at room temperature. The effect of pH, contact time, metal ion concentration and temperature were evaluated. The residual concentrations of the metal ions were determined by atomic absorption ...

  18. Radiation induced degradation of xanthan gum in aqueous solution

    Science.gov (United States)

    Hayrabolulu, Hande; Demeter, Maria; Cutrubinis, Mihalis; Güven, Olgun; Şen, Murat

    2018-03-01

    In our previous study, we have investigated the effect of gamma rays on xanthan gum in the solid state and it was determined that dose rate was an important factor effecting the radiation degradation of xanthan gum. In the present study, in order to provide a better understanding of how ionizing radiation effect xanthan gum, we have investigated the effects of ionizing radiation on aqueous solutions of xanthan at various concentrations (0.5-4%). Xanthan solutions were irradiated with gamma rays in air, at ambient temperature, at different dose rates (0.1-3.3-7.0 kGy/h) and doses (2.5-50 kGy). Change in their molecular weights was followed by size exclusion chromatography (SEC). Chain scission yield (G(S)), and degradation rate constants (k) were calculated. It was determined that, solution concentration was a factor effecting the degradation chemical yield and degradation rate of xanthan gum. Chain scission reactions were more effective for lower solution concentrations.

  19. Extracting alcohols from aqueous solutions. [USDOE patent application

    Science.gov (United States)

    Compere, A.L.; Googin, J.M.; Griffith, W.L.

    1981-12-02

    The objective is to provide an efficient process for extracting alcohols in aqueous solutions into hydrocarbon fuel mixtures, such as gasoline, diesel fuel and fuel oil. This is done by contacting an aqueous fermentation liquor with a hydrocarbon or hydrocarbon mixture containing carbon compounds having 5-18 carbon atoms, which may include gasoline, diesel fuel or fuel oil. The hydrocarbon-aqueous alcohol solution is then mixed with one or more of a group of polyoxyalkylene polymers to extract the alcohol into the hydrocarbon fuel-polyoxyalkylene polymer mixture.

  20. Degradation of malachite green in aqueous solution by Fenton process.

    Science.gov (United States)

    Hameed, B H; Lee, T W

    2009-05-30

    In this study, advanced oxidation process utilizing Fenton's reagent was investigated for degradation of malachite green (MG). The effects of different reaction parameters such as the initial MG concentration, initial pH, the initial hydrogen peroxide concentration, the initial ferrous concentration and the reaction temperature on the oxidative degradation of MG have been investigated. The optimal reacting conditions were experimentally found to be pH 3.40, initial hydrogen peroxide concentration=0.50mM and initial ferrous concentration=0.10mM for initial MG concentration of 20mg/L at 30 degrees C. Under optimal conditions, 99.25% degradation efficiency of dye in aqueous solution was achieved after 60 min of reaction.

  1. 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.

  2. The stability of oxymetazoline hydrochloride in aqueous solution.

    Science.gov (United States)

    Stanisz, Beata

    2002-01-01

    The kinetics of the hydrolysis reaction of oxymetazoline hydrochloride in aqueous solution at three temperatures (343 K, 353 K, 363 K), over the pH-range 0.5-12.5 and ionic strength 0.5 has been investigated. The changes of concentration of oxymetazoline hydrochloride were followed by the HPLC method with UV detection. In the pH range from 0.45 to 12.50, the hydrolysis of oxymetazoline consists of hydrolysis of oxymetazoline molecules catalyzed by hydrogen ions, spontaneous hydrolysis of the dissociated and undissociated oxymetazoline molecules. A minimal rate of the hydrolysis oxymetazoline was observed to occur in the pH range from 2.0 to 5.0. Thermodynamic parameters of the reaction: energy, entropy and enthalpy of activation and the frequency factor for the specific rate constants were determined.

  3. Ionic conductivity in aqueous solutions: deuterium isotope effect

    International Nuclear Information System (INIS)

    Samanta, Alok; Ghosh, Swapan K.

    1997-01-01

    A simple theoretical investigation of the calculation of ionic conductivity in aqueous solution is presented. The dipolar hard sphere model for the solvent which has been successful elsewhere has been employed here and it has been possible to reproduce the experimental results quite accurately for both water and heavy water using only two parameters. In a more detailed theoretical approach one should employ better models for water with proper account of its vibrations, liberations and also hydrogen bonding. It is also of interest to study the temperature effect and the concentration dependence of the conductivity. The time-dependent friction can also be calculated from the present formalism and be used for the study of isotope effect in proton transfer reactions or other aspects of chemical dynamics

  4. Aqueous Geochemistry at High Pressures and High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bass, Jay D. [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2015-05-21

    This project is aimed at experimental characterization of the sound velocities, equations of state (EOS), and derived physical and chemical properties of aqueous solutions and carbon dioxide at extreme pressure and temperature conditions relevant to processes occurring in the interior of the Earth. Chemical transport, phase changes (including melting), fluid-solid reactions, and formation of magmatic liquids at convergent plat boundaries are a key motivation for this project. Research in this area has long been limited by the extreme experimental challenges and lack of data under the appropriate pressure-temperature (P-T) conditions. The vast majority of studies of aqueous geochemistry relevant to terrestrial problems of fluid-rock interactions have been conducted at 0.3 GPa or less, and the widely used Helgeson-Kirkham-Flowers equation of state for aqueous species is applicable only at ~ < 0.5 GPa. These limits are unfortunate because fluid flow and reactions plays a central role in many deeper environments. Recent efforts including our own, have resulted in new experimental techniques that now make it possible to investigate properties of homogeneous and heterogeneous equilibria involving aqueous species and minerals over a much broader range of pressure and temperature appropriate for deep crustal and upper mantle processes involving water-rich fluids. We carried out 1) Brillouin scattering measurements of the equations of state and molar volume of water and carbon dioxide to over 10 GPa and 870K using precise resistance heating of samples under pressure in the diamond anvil cell, and 2) the phase diagrams of the water and CO2, and 3) Exploring new experimental approaches, including CO2 laser heating of samples in a diamond cell, to measurements of sound velocities, EOS, and phase relations by Brillouin scattering to far greater pressures and temperatures.

  5. Chemical metallization of KMPR photoresist polymer in aqueous solutions

    Science.gov (United States)

    Zeb, Gul; Duong, Xuan Truong; Vu, Ngoc Pi; Phan, Quang The; Nguyen, Duc Tuong; Ly, Viet Anh; Salimy, Siamak; Le, Xuan Tuan

    2017-06-01

    While conventional methods for preparing thin films of metals and metallic alloys on insulating substrates in the field of microelectromechanical systems (MEMS) include vapor deposition techniques, we demonstrate here that electroless deposition can be considered as an alternate efficient approach to metallize the surface of insulating substrates, such as KMPR epoxy photoresist polymer. In comparison with the physical and chemical vapor deposition methods, which are well-established for metallization of photoresist polymers, our electroless nickel plating requires only immersing the substrates into aqueous solutions in open air at low temperatures. Thin films of nickel alloy have been deposited electrolessly on KMPR surface, through a cost-effective and environmental chromium-free process, mediated through direct grafting of amine palladium complexes in aqueous medium. This covalent organic coating provides excellent adhesion between KMPR and the nickel film and allows better control of the palladium catalyst content. Covalent grafting and characterization of the deposited nickel film have been carried out by means of Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy techniques.

  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. Efficient indium-tin-oxide free inverted organic solar cells based on aluminum-doped zinc oxide cathode and low-temperature aqueous solution processed zinc oxide electron extraction layer

    International Nuclear Information System (INIS)

    Chen, Dazheng; Zhang, Chunfu; Wang, Zhizhe; Zhang, Jincheng; Tang, Shi; Wei, Wei; Sun, Li; Hao, Yue

    2014-01-01

    Indium-tin-oxide (ITO) free inverted organic solar cells (IOSCs) based on aluminum-doped zinc oxide (AZO) cathode, low-temperature aqueous solution processed zinc oxide (ZnO) electron extraction layer, and poly(3-hexylthiophene-2, 5-diyl):[6, 6]-phenyl C 61 butyric acid methyl ester blend were realized in this work. The resulted IOSC with ZnO annealed at 150 °C shows the superior power conversion efficiency (PCE) of 3.01%, if decreasing the ZnO annealing temperature to 100 °C, the obtained IOSC also shows a PCE of 2.76%, and no light soaking issue is observed. It is found that this ZnO film not only acts as an effective buffer layer but also slightly improves the optical transmittance of AZO substrates. Further, despite the relatively inferior air-stability, these un-encapsulated AZO/ZnO IOSCs show comparable PCEs to the referenced ITO/ZnO IOSCs, which demonstrates that the AZO cathode is a potential alternative to ITO in IOSCs. Meanwhile, this simple ZnO process is compatible with large area deposition and plastic substrates, and is promising to be widely used in IOSCs and other relative fields.

  8. Solute strengthening at high temperatures

    Science.gov (United States)

    Leyson, G. P. M.; Curtin, W. A.

    2016-08-01

    The high temperature behavior of solute strengthening has previously been treated approximately using various scaling arguments, resulting in logarithmic and power-law scalings for the stress-dependent energy barrier Δ E(τ ) versus stress τ. Here, a parameter-free solute strengthening model is extended to high temperatures/low stresses without any a priori assumptions on the functional form of Δ E(τ ) . The new model predicts that the well-established low-temperature, with energy barrier Δ {{E}\\text{b}} and zero temperature flow stress {τy0} , transitions to a near-logarithmic form for stresses in the regime 0.2intermediate-temperature and the associated transition for the activation volume. Overall, the present analysis unifies the different qualitative models in the literature and, when coupled with the previous parameter-free solute strengthening model, provides a single predictive model for solute strengthening as a function of composition, temperature, and strain rate over the full range of practical utility.

  9. Determination of metastable zone width of potassium sulfate in aqueous solution by ultrasonic sensor and FBRM

    Science.gov (United States)

    Luo, Mengjie; Liu, Chenglin; Xue, Jin; Li, Ping; Yu, Jianguo

    2017-07-01

    The metastable zone width (MSZW) and nucleation kinetics of potassium sulfate in the aqueous solution were investigated. MSZW was measured using both the ultrasonic velocity sensor and the focused beam reflectance measurement (FBRM) at different cooling rate, stirring rate and impurities concentration (aluminum ions and silicon ions), and the effects of these conditions on MSZW were discussed in details. In addition, the accuracy and sensitivity of detectors to measure the nucleation temperature of potassium sulfate in the aqueous solution were compared between the ultrasonic velocity sensor and FBRM over a wider range of operating conditions. Although two detectors measured MSZW with an acceptable accuracy, the ultrasonic velocity sensor had a higher sensitivity to the phase transition of potassium sulfate in solution since it directly detected the concentration change of potassium sulfate in solution. Furthermore, both self-consistent Nývlt-like equation method and classical 3D nucleation theory approach were applied to estimate MSZW of potassium sulfate in aqueous solution. According to these classical theories, the nucleation kinetics parameters were calculated based on the measured MSZW data for potassium sulfate aqueous solution with 40 °C, 50 °C and 60 °C saturation temperature, respectively. It was found two approaches could describe MSZW of potassium sulfate aqueous system very well.

  10. NMR and DSC study of temperature-induced phase transition in aqueous solutions of poly(N-isopropylmethacrylamide-co-acrylamide) copolymers

    Czech Academy of Sciences Publication Activity Database

    Šťastná, J.; Hanyková, L.; Spěváček, Jiří

    2012-01-01

    Roč. 290, č. 17 (2012), s. 1811-1817 ISSN 0303-402X R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : temperature induced phase transition * thermosensitive copolymer * poly(N-isopropylmethacrylamide-co- acrylamide ) Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.161, year: 2012

  11. Interactions of Cl- and OH radical in aqueous solution.

    Science.gov (United States)

    Valiev, Marat; D'Auria, Raffaella; Tobias, Douglas J; Garrett, Bruce C

    2009-08-06

    There is a considerable controversy surrounding the nature of the Cl-/OH complex in aqueous solution, which appears as a byproduct of the irradiation of salt solutions in nuclear reactor operation, radioactive waste storage, medicine, and environmental problems. In this work, we report results of combined quantum mechanical molecular mechanics calculations of ground-state free-energy surfaces and absorption spectrum through the CCSDT level of theory that are consistent with the experimental data and suggest that hemibonded HOCl- species may indeed exist in bulk aqueous solution.

  12. Selective Oxidation of Glycerol to Glyceric Acid in Base-Free Aqueous Solution at Room Temperature Catalyzed by Platinum Supported on Carbon Activated with Potassium Hydroxide

    KAUST Repository

    Tan, Hua

    2016-04-18

    Pt supported on KOH-activated mesoporous carbon (K-AMC) was used to catalyze glycerol oxidation under base-free conditions at room temperature. To study the relationship between the carbon surface chemistry and the catalytic performance of the K-AMC-based Pt catalysts, different levels of surface oxygen functional groups (SOFGs) on the AMC supports were induced by thermal treatment at different temperatures under inert or H2 gas. A strong effect of the surface chemistry was observed on AMC-supported Pt catalysts for glycerol oxidation. The presence of carboxylic acid groups impedes the adsorption of glycerol, which leads to the reduction of catalytic activity, whereas the presence of high-desorption-temperature SOFGs, such as phenol, ether, and carbonyl/quinone groups, provide hydrophilicity to the carbon surface that improves the adsorption of glycerol molecules on Pt metal surface, which is beneficial for the catalytic activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Radiation-induced nitration of organic compounds in aqueous solutions

    International Nuclear Information System (INIS)

    Ershov, B.G.; Gordeev, A.V.; Bykov, G.L.

    2009-01-01

    Radiation-induced nitration of organic compounds in aqueous solutions was studied. It was found that γ-irradiation of solutions containing acetic and nitric acid and/or their salts gives nitromethane. Dependences of the product yield on the absorbed dose and the contents of components were established. The mechanism of radiation nitration involving radicals is discussed. (author)

  14. 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…

  15. Optimization of Crystal Violet dye removal from aqueous solution ...

    African Journals Online (AJOL)

    Batch adsorption process involving use of groundnut shell (GS) and orange peel (OP) as adsorbents was employed for the removal of carcinogenic Crystal Violet dye from aqueous solution. Studies were carried out as function of contact time, sorbent dosage, initial dye concentration and pΗ of the dye solution with a view of ...

  16. Primary photochemistry of peroxynitrite in aqueous solution

    Science.gov (United States)

    Thøgersen, Jan; Kissner, Reinhard; Nauser, Thomas; Koppenol, Willem H.; Richter, Bo; Jensen, Frank; Keiding, Søren Rud; Jensen, Svend J. Knak

    2015-11-01

    The photolysis of aqueous peroxynitrite, ONOO-(aq), by 266 nm UV radiation is explored by femtosecond UV-UV and UV-IR transient absorption spectroscopies. The experiments show that 90 ± 10% of the photolyzed ONOO- anions remain dissociated after 400 ps. We analyze the photolysis in terms of five potential reaction channels, using steady-state absorption spectra together with electron structure calculations on potential photoproducts in clusters of water molecules. In addition, calculations of all excited electronic states of ONOO-(g) below the excitation energy help to explore the reaction channels. The dominant reaction channel is hν + ONOO- → O2•- + NO•.

  17. aqueous solutions by caladium bicolor (wild

    African Journals Online (AJOL)

    The biomaterial is cellulosic and therefore biodegradable and environment friendly. Kinetics describes the solute uptake rate that controls the residence time of sorbate uptake at the solid-solution interface. Kinetic studies are important in determining the time needed to reach equilibrium and examinations into the rates of ...

  18. The removal of reactive dyes from aqueous solutions using chemically modified mesoporous silica in the presence of anionic surfactant-The temperature dependence and a thermodynamic multivariate analysis

    International Nuclear Information System (INIS)

    Cestari, Antonio R.; Vieira, Eunice F.S.; Vieira, Glaucia S.; Costa, Luiz P. da; Tavares, Andrea M.G.; Loh, Watson; Airoldi, Claudio

    2009-01-01

    The three-parameter Sips adsorption model was successfully employed to modeled equilibrium adsorption data of a yellow and a red dye onto a mesoporous aminopropyl-silica, in the presence of the surfactant sodium dodecylbenzenesulfonate (DBS) from 25 to 55 deg. C. The results were evaluated in relation to the previously reported surface tension measurements. The presence of curvatures of the vant Hoff plots suggested the presence of non-zero heat capacities terms (Δ ads C p ). For the yellow dye, it is observed that the values of Δ ads H are almost all positive and they decrease in endothermicity, in the absence and in the presence of DBS, from 25 to 55 deg. C. For the red dye, there is an increase in endothermicity in relation to the temperature increase. The negative Δ ads G values indicate spontaneous adsorption processes. Almost all adsorption entropy values (Δ ads S) were positive. This suggests that entropy is a driving force of adsorption. The adsorption thermodynamic parameters were also evaluated using a new 2 3 full factorial design analysis. The multivariate polynomial modelings indicated that the thermodynamic parameters are also affected by important interactive effects of the experimental factors and not by the temperature changes alone

  19. [Enhancement effect of double-beam laser processed aqueous solution on ICP emission spectrum].

    Science.gov (United States)

    Chen, Jin-zhong; Xu, Li-jing; Su, Hong-xin; Li, Xu; Wang, Shu-fang

    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 tension and viscosity of aqueous solution reduced by 42. 13% and 14. 03% compared with the untreated, and the atomization efficiency 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 elements 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%, respectively. 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 significantly, and raise the radiationintensity of ICP source, and will provide a better condition for detecting the trace heavy metal elements in water samples.

  20. Investigation of the removal of chromium (VI by Nanocomposites Chitosan-tragacanth solution from aqueous solution

    Directory of Open Access Journals (Sweden)

    Adel Almasi Nahnaji

    2016-03-01

    Full Text Available Background: The aim of this study was to investigate the removal of chromium (VI by Nanocomposites Chitosan-tragacanth solution from aqueous solution. Methods: In this study, chitosan-tragacanth nanocomposites were synthesized and analyzed by electron microscopy (SEM, (TEM and Fourier transform spectroscopy (FT-IR for the size and shape of the surface. The nano-composite of chitosan-tragacanth, for the adsorption of chromium (VI in aqueous solution was used as adsorbent. Results: The optimum conditions with multiple experiments to enhance the absorption were evaluated. The highest absorption of Cr (VI was occurred in the adsorbent dosage of 0.2 g, 8 ppm concentration of chromium ions, the pH=6 and also retention time of 50 min; in 298 ˚K temperature. After determining optimal conditions of adsorption, isotherms equations and study and thermodynamic parameters were applied. Adsorption process of chromium (VI on nano-composite chitosan - Tragacanth was conformed with Temkin isotherm. Conclusion: The thermodynamic parameters such as standard Gibbs free energy changes, changes in enthalpy and entropy changes in the standard showed that the adsorption process of Cr (VI is spontaneous and heating, and kinetics studies of models Lagergren, Ho , Alovich and intraparticle is used, the results show that the adsorption kinetics follows the pseudo-second order.

  1. Flotation separation of hafnium(IV) from aqueous solutions

    International Nuclear Information System (INIS)

    Downey, D.M.; Narick, C.N.; Cohen, T.A.

    1985-01-01

    A simple, rapid method for the separation of hafnium from aqueous solutions was investigated using sup(175+181)Hf tracer. Cationic hafnium complex ions were floated from dilute acid solutions with sodium lauryl sulfate (SLS) and anionic hafnium complexes were floated from basic and oxalic acid solutions with hexadecyltrimethyl ammonium bromide (HTMAB). The conditions necessary for quantitative recovery of the metal and mechanisms of flotation are described. (author)

  2. Self-aggregation of liquids from biomass in aqueous solution

    International Nuclear Information System (INIS)

    Lomba, Laura; Giner, Beatriz; Zuriaga, Estefanía; Moya, Juana; Lafuente, Carlos

    2013-01-01

    Highlights: • Aggregation behaviour of liquids from biomass in aqueous solution has been studied. • Standard Gibbs free energies of aggregation have been calculated. • Solubility in water of these compounds has been determined. • Critical aggregation concentration decreases as the solubility in water does. -- Abstract: Aggregation of several chemicals from biomass: furfural derived compounds (furfural, 5-methylfurfural, furfuryl alcohol and tetrahydrofurfuryl alcohol), lactate derived compounds (methyl lactate, ethyl lactate and butyl lactate), acrylate derived compound (methyl acrylate) and levulinate compounds (methyl levulinate, ethyl levulinate and butyl levulinate) in aqueous solution has been characterised at T = 298.15 K through density, ρ, speed of sound, u, and isentropic compressibilities, κ S , measurements. In addition the standard Gibbs free energies of aggregation have been also calculated. Furthermore, in order to deepen insight the behaviour of these chemicals in aqueous solution, the solubility of these compounds has been measured at T = 298.15 K

  3. Study of free acidity determinations in aqueous solution

    International Nuclear Information System (INIS)

    Kergreis, A.

    1966-04-01

    The object of this work is the study of the principal methods which can be applied to the measurement of 'free' acidity. In the first part, we define the various types of acidity which can exist in aqueous solution; then, after having studied some hydrolysis reactions, we compare the value of the neutralisation pH of the hydrated cation and that of the precipitation of the hydroxide. In the second part we have started to study the determination of the acidity of an aqueous solution. After having rapidly considered the 'total' acidity determination, we deal with the problem of the 'free' acidity titration. We have considered in particular certain methods: extrapolation of the equivalent point, colorimetric titrations with or without a complexing agent, and finally the use of ion-exchange resins with mixed aqueous and solvent solutions. (author) [fr

  4. Electrochemical Removal Of Selenate From Aqueous Solutions

    Science.gov (United States)

    Baek, Kitae; Kasem, Naji; Ciblak, Ali; Vesper, Dorothy; Padilla, Ingrid; Alshawabkeh, Akram N.

    2013-01-01

    Removal of selenate from solution is investigated in batch electrochemical systems using reactive iron anodes and copper plate cathode in a bicarbonate medium. Iron anodes produce ferrous hydroxide, which is a major factor in the removal of selenate from solution. Iron anodes also generate a significant decrease in the oxidation-reduction potential (ORP) of the solution because it prevents generation of oxygen gas at the anode by electrolysis. The removal rates varied from 45.1 to 97.4%, depending on current density and selenate concentration. The transformation of selenate by the process is modeled based on a heterogeneous reaction coupled with electrochemical generation of ferrous and hydroxide. The rates are optimized at lower initial concentrations, higher electrical currents, and the presence of anions. Presence of dissolved oxygen does not cause any significant effects the removal of selenate. PMID:23378820

  5. Metal ion removal from aqueous solution using physic seed hull.

    Science.gov (United States)

    Mohammad, Masita; Maitra, Saikat; Ahmad, Naveed; Bustam, Azmi; Sen, T K; Dutta, Binay K

    2010-07-15

    The potential of physic seed hull (PSH), Jantropha curcas L. as an adsorbent for the removal of Cd(2+) and Zn(2+) metal ions from aqueous solution has been investigated. It has been found that the amount of adsorption for both Cd(2+) and Zn(2+) increased with the increase in initial metal ions concentration, contact time, temperature, adsorbent dosage and the solution pH (in acidic range), but decreased with the increase in the particle size of the adsorbent. The adsorption process for both metal ions on PSH consists of three stages-a rapid initial adsorption followed by a period of slower uptake of metal ions and virtually no uptake at the final stage. The kinetics of metal ions adsorption on PSH followed a pseudo-second-order model. The adsorption equilibrium data were fitted in the three adsorption isotherms-Freundlich, Langmuir and Dubinin-Radushkevich isotherms. The data best fit in the Langmuir isotherm indication monolayer chemisorption of the metal ions. The adsorption capacity of PSH for both Zn(2+) and Cd(2+) was found to be comparable with other available adsorbents. About 36-47% of the adsorbed metal could be leached out of the loaded PSH using 0.1M HCl as the eluting medium. 2010 Elsevier B.V. All rights reserved.

  6. Spontaneous nematic alignment of a lipid nanotube in aqueous solutions.

    Science.gov (United States)

    Ding, Wuxiao; Minamikawa, Hiroyuki; Kameta, Naohiro; Wada, Momoyo; Masuda, Mitsutoshi; Shimizu, Toshimi

    2015-01-27

    The dispersibility and liquid crystal formation of a self-assembled lipid nanotube (LNT) was investigated in a variety of aqueous solutions. As the lipid component, we chose a bipolar lipid with glucose and tetraglycine headgroups, which self-assembled into an LNT with a small outer diameter of 16 to 17 nm and a high axial ratio of more than 310. The LNT gave a stable colloidal dispersion in its dilute solutions and showed spontaneous liquid crystal (LC) alignment at relatively low concentrations and in a pH region including neutral pH. The LNT samples with shorter length distributions were prepared by sonication, and the relationship between the LNT axial ratio and the minimum LC formation concentration was examined. The robustness of the LNT made the liquid crystal stable in mixed solvents of water/ethanol, water/acetone, and water/tetrahydrofuran (1:1 by volume) and at a temperature of up to 90 °C in water. The observed colloidal behavior of the LNT was compared to those of similar 1D nanostructures such as a phospholipid tubule.

  7. Synchrotron x-ray spectroscopy of EuHN O3 aqueous solutions at high temperatures and pressures and Nb-bearing silicate melt phases coexisting with hydrothermal fluids using a modified hydrothermal diamond anvil cell and rail assembly

    Science.gov (United States)

    Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

    2007-01-01

    A modified hydrothermal diamond anvil cell (HDAC) rail assembly has been constructed for making synchrotron x-ray absorption spectroscopy, x-ray fluorescence, and x-ray mapping measurements on fluids or solid phases in contact with hydrothermal fluids up to ???900??C and 700 MPa. The diamond anvils of the HDAC are modified by laser milling grooves or holes, for the reduction of attenuation of incident and fluorescent x rays and sample cavities. The modified HDAC rail assembly has flexibility in design for measurement of light elements at low concentrations or heavy elements at trace levels in the sample and the capability to probe minute individual phases of a multiphase fluid-based system using focused x-ray microbeam. The supporting rail allows for uniform translation of the HDAC, rotation and tilt stages, and a focusing mirror, which is used to illuminate the sample for visual observation using a microscope, relative to the direction of the incident x-ray beam. A structure study of Eu(III) aqua ion behavior in high-temperature aqueous solutions and a study of Nb partitioning and coordination in a silicate melt in contact with a hydrothermal fluid are described as applications utilizing the modified HDAC rail assembly. ?? 2007 American Institute of Physics.

  8. REMOVAL OF CADMIUM FROM AQUEOUS SOLUTION USING ...

    African Journals Online (AJOL)

    All synthesized products were thermally stable up to 300 oC and were highly insoluble in most mineral acids except hot perchloric acid. The sorption of cadmium ion from 0.1 M HNO3 solutions on manganese hexacyanoferrates (II) and (III) was investigated. Both sorption kinetics and isotherms were studied. The sorption ...

  9. Removal of Phenol in Aqueous Solution Using Kaolin Mineral Clay

    International Nuclear Information System (INIS)

    Sayed, M.S.

    2008-01-01

    Kaolin clay were tested for phenol removal as toxic liquid waste from aqueous waste water. Several experimental conditions such as weight and particle size of clay were investigated to study batch kinetic techniques, also the ph and concentration of the phenol solution were carried out. The stability of the Langmuir adsorption model of the equilibrium data were studied for phenol sorbent clay system. Infrared spectra, thermogravimetric and differential thermal analysis techniques were used to characterize the behavior of kaolin clay and kaolin clay saturated with phenol. The results obtained showed that kaolin clay could be used successfully as an efficient sorbent material to remove phenol from aqueous solution

  10. Radiation chemistry of aqueous solutions of acetonitrile and propionitrile

    International Nuclear Information System (INIS)

    Shushtarian, M.J.

    1975-01-01

    The radiation chemistry of water and aqueous solutions is a branch of radiation chemistry dealing with chemical changes in water and aqueous solutions induced by high energy radiations. High energy radiations of interest in radiation chemistry are short-wave electromagnetic radiations (X- and γ-rays) and fast charged particles (α- and β-particles, electrons, deuterons and fission fragments). The energy of the particles and photons bringing about chemical reactions in the field of modern radiation chemistry is much higher than that of photons causing photochemical reactions

  11. Photochemical properties of Ysub(t) base in aqueous solution

    International Nuclear Information System (INIS)

    Paszyc, S.; Rafalska, M.

    1979-01-01

    Photoreactivity of Ysub(t) base (I) has been studied in aqueous solution (pH-6) saturated with oxygen. Two photoproducts (II,III), resulting from irradiation at lambda = 253.7 nm and lambda >= 290 nm were isolated and their structures determined. The quantum yield for Ysub(t) base disappearance (rho dis) is 0.002 (lambda = 313 nm). It was shown that dye- sensitised photo-oxidation of Ysub(t) base in aqueous solution occurs according to a Type I mechanism as well as with participation of singlet state oxygen. Quantum yields, fluorescence decay times and phosphorescence of Ysub(t) base have also been determined. (author)

  12. 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

  13. 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.

  14. THERMODYNAMICS OF ETHANOLAMMONIUM CATIONES DISSOCIATION IN AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    R. E. Khoma

    2017-03-01

    Full Text Available The literature data on the thermodynamics of ethanolamines onium cations dissociation have been systematized and generalized. The correlation between these cations dissociation thermodynamic functions (DH and DS and physicochemical properties (Tmp., Tbp, Pp, lgPow et al. has been revealed. There was a correlation between lipophilicity determined experimentally and calculated by QSAR. For monoethanolammonium, diethanolammonium, and their N-methyl and N-ethyl derivatives it was found dissociation thermodynamic functions to depend on bases lgPow. Acid-base dissociation of TRIS and triethanolamine onium cations does not correspond to said relationship because TRIS (primary amine, TEA (tertiary amine act differently on aqueous solutions of SO2. TEA, unlike MEA, DEA and MMEA, has a salting out effect towards sulfur dioxide because of competing hydration that promotes sulfite «onium» salts hydrolysis. TRIS promotes S(IV → S(VI sulphooxidation, in contrast to another ethanolamines. Enthalpy–enthropy compensation with isothermodynamic temperature 303 K has been recorded. The revealed correlations may be useful in developing of procedures for air sanitary cleaning from acidic gases; chemisorbents immobilized for gas and ion exchange chromatography; potentiometric methods for fluorocomplex acids determinations. The use of monoethanolamine is most promising to obtain chemisorbents because the thermodynamic functions of its onium cation acid-base dissociation are least dependent on temperature compared to other etanolammonium cations.

  15. Assorted interactions of amino acids prevailing in aqueous vitamin C solutions probed by physicochemical and ab-initio contrivances

    Science.gov (United States)

    Das, Koyeli; Roy, Milan Chandra; Rajbanshi, Biplab; Roy, Mahendra Nath

    2017-11-01

    Qualitative and quantitative analysis of molecular interaction prevailing in tyrosine and tryptophan in aqueous solution of vitamin C have been probed by thermophysical properties. The apparent molar volume (ϕV), viscosity B-coefficient, molal refraction (RM) of tyrosine and tryptophan have been studied in aqueous vitamin C solutions at diverse temperatures via Masson equation which deduced solute-solvent and solute-solute interactions, respectively. Spectroscopic study along with physicochemical and computational techniques provides lots of interesting and highly significant insights of the model biological systems. The overall results established strong solute-solvent interactions between studied amino acids and vitamin C mixture in the ternary solutions.

  16. Gelation Behavior of 5-Chloro-8-hydroxyquinoline, an Antituberculosis Agent in Aqueous Alcohol Solutions

    Directory of Open Access Journals (Sweden)

    Jukka Korpela

    2012-09-01

    Full Text Available It was shown that 5-chloro-8-hydroxyquinoline, an antituberculosis agent, gels aqueous alcohol solutions efficiently. Thermal stability and gel-to-sol transition temperature of 1% gel in CD3OD/D2O (2:1 was studied by 1H-NMR. Fibrous structures of four xerogels have been characterized by scanning electron microscope.

  17. Heat of Absorption of CO2 in Aqueous Solutions of DEEA, MAPA and their Mixture

    DEFF Research Database (Denmark)

    Waseem Arshad, Muhammad; von Solms, Nicolas; Thomsen, Kaj

    2013-01-01

    A reaction calorimeter was used to measure the differential heat of absorption of CO2 in phase change solvents as a function of temperature, CO2 loading and solvent composition. The measurements were taken for aqueous solutions of 2-(diethylamino)ethanol (DEEA), 3-(methylamino)propylamine (MAPA...

  18. Solubility of N2O in and density, viscosity, and surface tension of aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W.; Hogendoorn, K. J.; Versteeg, G. F.

    2005-01-01

    The physical solubility of N2O in and the density and viscosity of aqueous piperazine solutions have been measured over a temperature range of (293.15 to 323.15) K for piperazine concentrations ranging from about (0.6 to 1.8) kmol·mr-3. Furthermore, the present study contains experimental surface

  19. Kinetics of COS with primary and secondary amines in aqueous solutions

    NARCIS (Netherlands)

    Littel, R.J.; Littel, R.J.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1992-01-01

    The reaction between COS and aqueous solutions of primary and secondary amines has been studied by means of the stirred cell technique. Kinetic experiments at temperatures 283 to 333 K were carried out with MEA, DGA, DEA, DIPA, MMEA, AMP, and MOR. All kinetic experiments could be described by a

  20. Gelation Behavior of 5-Chloro-8-hydroxyquinoline, an Antituberculosis Agent in Aqueous Alcohol Solutions.

    Science.gov (United States)

    Kolehmainen, Erkki; Salo, Hannu; Korpela, Jukka

    2012-09-19

    It was shown that 5-chloro-8-hydroxyquinoline, an antituberculosis agent, gels aqueous alcohol solutions efficiently. Thermal stability and gel-to-sol transition temperature of 1% gel in CD₃OD/D₂O (2:1) was studied by ¹H-NMR. Fibrous structures of four xerogels have been characterized by scanning electron microscope.

  1. Adsorption of Pb 2+ and Cu2+ ions from aqueous solutions by ...

    African Journals Online (AJOL)

    The removal of heavy metal ions Cu2+ and Pb2+ from aqueous solution using mango tree (Mangifera indica) saw dust as adsorbent under different experimental conditions was investigated. The effects of pH, contact time, temperature, adsorbent dosage and initial metal ion concentrations for the removal of Cu2+ and Pb2+ ...

  2. Reaction path sampling of the reaction between iron(II) and hydrogen peroxide in aqueous solution

    NARCIS (Netherlands)

    Ensing, B.; Baerends, E.J.

    2002-01-01

    Previously, we have studied the coordination and dissociation of hydrogen peroxide with iron(II) in aqueous solution by Car-Parrinello molecular dynamics at room temperature. We presented a few illustrative reaction events, in which the ferryl ion ([Fe(IV)O

  3. Solubility and Diffusivity of Acid Gases (CO2, N2O) in Aqueous Alkanolamine Solutions

    NARCIS (Netherlands)

    Versteeg, Geert F.; Swaaij, Wim P.M. van

    1988-01-01

    Solubility and diffusivity of N2O and CO2 in water were determined as a function of temperature from the results published in the open literature, and new data were measured in the present work. The solubility of N2O in several aqueous alkanolamine (DEA, DIPA, DMMEA, and DIPA) solutions at various

  4. Synthesis and Rheological Properties of an Associative Star Polymer in Aqueous Solutions

    DEFF Research Database (Denmark)

    Hietala, Sami; Mononen, Pekka; Strandman, Satu

    2007-01-01

    Rheological properties of aqueous solutions and hydrogels fonned by an amphiphiIic star block copolymer poly(acrylic acid)-blockpolystyrene (PAAS4-b-PS6)4. were investigated as a function of the polymer concentration (Cp), temperature, and added saIt concentration. The water-soluble polymer...

  5. 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.

  6. Spontaneous unilamellar polymer vesicles in aqueous solution.

    Science.gov (United States)

    Kim, Tae-Hwan; Song, Chaeyeon; Han, Young-Soo; Jang, Jong-Dae; Choi, Myung Chul

    2014-01-21

    A unilamellar polymeric vesicle is a self-assembled structure of a block copolymer that forms a spherical single bilayer structure with a hydrophobic interlayer and a hydrophilic surface. Due to their enhanced colloidal stability and mechanical property, controllable surface functionality, or tunable membrane thickness, polymeric vesicles are useful in nano and bio-science, providing potential applications as nanosized carriers for catalysts, drugs, and enzymes. For fabrication of a unilamellar vesicle, however, preparative procedures with a few steps are inherently required. Herein, without complicated preparative procedures, we report spontaneous unilamellar polymeric vesicles with nanometer sizes (small angle neutron scattering and cryo-TEM, resulting in a phase diagram drawn as a function of temperature and the 5mS concentration. Interestingly the critical temperature for the micelle-to-vesicle phase transition was easily controlled by varying the 5mS concentration, i.e. it was decreased with increasing the 5mS concentration.

  7. Glycine phases formed from frozen aqueous solutions: Revisited

    Science.gov (United States)

    Surovtsev, N. V.; Adichtchev, S. V.; Malinovsky, V. K.; Ogienko, A. G.; Drebushchak, V. A.; Manakov, A. Yu.; Ancharov, A. I.; Yunoshev, A. S.; Boldyreva, E. V.

    2012-08-01

    Glycine phases formed when aqueous solutions were frozen and subsequently heated under different conditions were studied by Raman scattering, x-ray diffraction, and differential scanning calorimetry (DSC) techniques. Crystallization of ice Ih was observed in all the cases. On cooling at the rates of 0.5 K/min and 5 K/min, glassy glycine was formed as an intermediate phase which lived about 1 min or less only, and then transformed into β-polymorph of glycine. Quench cooling of glycine solutions (15% w/w) in liquid nitrogen resulted in the formation of a mixture of crystalline water ice Ih and a glassy glycine, which could be preserved at cryogenic temperatures (80 K) for an indefinitely long time. This mixture remained also quite stable for some time after heating above the cryogenic temperature. Subsequent heating under various conditions resulted in the transformation of the glycine glass into an unknown crystalline phase (glycine "X-phase") at 209-216 K, which at 218-226 K transformed into β-polymorph of glycine. The "X-phase" was characterized by Raman spectroscopy; it could be obtained in noticeable amounts using a special preparation technique and tentatively characterized by x-ray powder diffraction (P2, a = 6.648 Å, b = 25.867 Å, c = 5.610 Å, β = 113.12°); the formation of "X-phase" from the glycine glassy phase and its transformation into β-polymorph were followed by DSC. Raman scattering technique with its power for unambiguous identification of the crystalline and glassy polymorphs without limitation on the crystallite size helped us to follow the phase transformations during quenching, heating, and annealing. The experimental findings are considered in relation to the problem of control of glycine polymorphism on crystallization.

  8. Effect of sodium tetraborate (borax) on the thermal properties of frozen aqueous sugar and polyol solutions.

    Science.gov (United States)

    Izutsu, Ken-ichi; Rimando, Annie; Aoyagi, Nobuo; Kojima, Shigeo

    2003-06-01

    The effect of sodium tetraborate (Na(2)B(4)O(7), borax) on the thermal property of frozen aqueous sugar and polyol solutions was studied through thermal analysis. Addition of borax raised the thermal transition temperature (glass transition temperature of maximally freeze-concentrated solutes; T(g)') of frozen sucrose solutions depending on the borax/sucrose concentration ratios. Changes in the T(g)' of frozen mono- and disaccharide solutions suggested various forms of complexes, including those of a borate ion and two saccharide molecules. Borax exerted the maximum effect to raise the oligosaccharide and dextran T(g)'s at borax/saccharide molar ratios of approximately 1-2 (maltose and maltooligosaccharides), 2 (dextran 1060), 5 (dextran 4900), and 10 (dextran 10200). Further addition of borax lowered T(g)'s of the saccharide solutions. Borax also raised T(g) and T(g)' temperatures of frozen aqueous glycerol solutions. The decreased solute mobility in frozen solutions by the borate-polyol complexes suggested higher collapse temperature in the freeze-drying process and improved stability of biological systems in frozen solutions.

  9. Chemical denitration of aqueous nitrate solutions

    International Nuclear Information System (INIS)

    Burrill, K.A.

    1987-11-01

    The Plant for Active Waste Liquids (PAWL) at CRNL will immobilize in glass the fission products in waste from Mo-99 production. The nitrate ions in the waste can be destroyed by heating, but also by chemical reaction with formic acid (HCOOH). Since chemical denitration has several advantages over thermal denitration it was studied in the course of vitrification process development. Two free radical mechanisms are examined here to explain kinetic data on chemical denitration of nitric acid solutions with formic acid. One mechanism is applicable at > 1 mol/L HNO 3 and involves the formate radical (HCOO . ). The second mechanism holds at 3 and involves the hyponitrous radical (HNO . ). Mass balances for various species were written based on the law of mass action applied to the equations describing the reaction mechanism. Analytical and numerical solutions were obtained and compared. Literature data on batch denitration were used to determine some of the rate constants while others were set arbitrarily. Observed stoichiometry and trends in reactant concentrations are predicted accurately for batch data. There are no literature data to compare with the prediction of negligible induction time

  10. 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.

  11. Adsorption of Rhodamine B Dye from Aqueous Solution on Irvingia ...

    African Journals Online (AJOL)

    NICOLAAS

    RawIrvingia gabonenses(dika nut) (DN) and its acid-treated form (ADN) were used for the uptake of rhodamine B (RhB) dye from aqueous solution. The adsorbents were characterized by Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–. Teller (BET) surface area analysis and scanning electron ...

  12. 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 ...

  13. Removal of some metal ions from aqueous solution using orange ...

    African Journals Online (AJOL)

    In this study, the use of orange mesocarp residue biomass (modified and unmodified) as a costeffective and environmentally safe technique to remove Mg2+, Zn2+, Cu2+, Pb2+ from aqueous solution was investigated. The results showed that unmodified orange mesocarp residue bound 56% of Mg2+, 81% of Zn2+, 71% of ...

  14. Adsorptive removal of cationic dye from aqueous solution using ...

    African Journals Online (AJOL)

    PROF HORSFALL

    2017-12-03

    Dec 3, 2017 ... Langmuir isotherm also had the highest correlation factor, thus it was the best for describing the equilibrum process. REFERENCES. Ahmad M. A, Ahmad, N and Bello O. S (2015). Removal of Remazol Brilliant Blue Reactive. Dye from Aqueous Solutions Using Watermelon. Rinds as Adsorbent. J. Disp. Sci.

  15. Ammonium removal from aqueous solution by ion-exchange using ...

    African Journals Online (AJOL)

    Ammonium removal from aqueous solution by a natural ion-exchange resin was investigated by considering the factors affecting the ammonium-exchange capacity including the zeolites' particle size, the loading flow rates and the impact of a number of regenerations upon the ion-exchange capacity. The resin column was ...

  16. Volumetric studies of some amino acids in binary aqueous solutions ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 117; Issue 3. Volumetric studies of some amino acids in binary aqueous solutions of MgCl2.6H2O at 288.15, and 308.15 K. Amalendu Pal Suresh Kumar. Volume 117 Issue 3 May 2005 pp 267-273 ...

  17. Cast iron deterioration with time in various aqueous salt solutions

    Indian Academy of Sciences (India)

    Unknown

    Abstract. 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 ...

  18. Pulse radiolysis of pyridine and methylpyridines in aqueous solutions

    DEFF Research Database (Denmark)

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

    1993-01-01

    The radicals formed from pyridine, 3-methylpyridine, 3,5-dimethylpyridine, 2,6-dimethylpyridine and 2,4,6-trimethylpyridine by attack of H, e(aq)-, OH and O.- in aqueous solutions were investigated by pulse radiolysis in the pH-range 1-13.8. The UV-vis. absorption spectra as well as the formation...

  19. Determination of Lifetimes of Carbocations in Aqueous Solution ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 6. Determination of Lifetimes of Carbocations in Aqueous Solution by Azide Clock: A Simple Physical-Organic Chemistry Experiment. V Jagannadham. Classroom Volume 12 Issue 6 June 2007 pp 76-82 ...

  20. Volumetric studies of some amino acids in binary aqueous solutions

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 117; Issue 3. Volumetric studies of some amino acids in binary aqueous solutions of MgCl2.6H2O at 288.15, and 308.15 K. Amalendu Pal Suresh Kumar. Volume 117 Issue 3 May 2005 pp 267-273 ...

  1. 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...

  2. Accurate Description of Calcium Solvation in Concentrated Aqueous Solutions

    Czech Academy of Sciences Publication Activity Database

    Kohagen, Miriam; Mason, Philip E.; Jungwirth, Pavel

    2014-01-01

    Roč. 118, č. 28 (2014), s. 7902-7909 ISSN 1520-6106 R&D Projects: GA ČR GBP208/12/G016; GA MŠk LH12001 Institutional support: RVO:61388963 Keywords : calcium chloride * aqueous solution * molecular dynamics * neutron scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.302, year: 2014

  3. In Vitro Antioxidant Activity of Chitosan Aqueous Solution: Effect of ...

    African Journals Online (AJOL)

    Purpose: To investigate the effect of salt form on the antioxidant activities of chitosan aqueous solution. Methods: The antioxidant activities of chitosan acetate (CS-acetate), chitosan hydroxybenzotriazole (CS-HOBt), chitosan thiamine pyrophosphate (CS-TPP) and chitosan ethylenediaminetetraacetic acid (CS-EDTA) ...

  4. 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

  5. Lead removal in aqueous solution by activated carbons prepared ...

    African Journals Online (AJOL)

    AJL

    Desalination, 206(1–3): 270–278. Bedoui K, Bekri-Abbes I, Srasra E (2008). Removal of Cadmium (II) from aqueous solution using pure smectite and lewatite S 100: the effect of time and metal concentration. Desalination. 223:269-273. Bohem HP (1994). Some aspects of the chemistry of carbon blacks and other carbons.

  6. NMR study of thermoresponsive block copolymer in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Čadová, Eva

    2016-01-01

    Roč. 217, č. 12 (2016), s. 1370-1375 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * NMR * NOESY Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.500, year: 2016

  7. Removal of Hexavalent Chromium from Aqueous Solutions using ...

    African Journals Online (AJOL)

    The hexavalent chromium exists in aquatic media as water soluble complex anions and persist. These are concentrated in industrial waste water especially from the tannery industries and release of effluents from industries adversely affects the environment. The removal of heavy metals from aqueous solutions is carried ...

  8. Biosorptive removal of cobalt (II) ions from aqueous solution by ...

    African Journals Online (AJOL)

    The objective of this study was to investigate the possibility of using Amaranthus hybridus L. stalk as an alternative to high cost commercial adsorbent materials for the removal of Co (II) from aqueous solution. The experiment was carried out by batch method at 33°C. The influence of pH, contact time and initial metal ion ...

  9. Sequestration of Congo red Dye from Aqueous Solution using ...

    African Journals Online (AJOL)

    The adsorption of Congo red dye in aqueous solution using locally sourced almond shell adsorbent was investigated in this study. The effect of various factors such as contact time, initial dye concentration and adsorbent dosage on the adsorption capacity of the adsorbent was studied. The adsorption of Congo red dye was ...

  10. from an aqueous solution using Azadirachta indica leaf powder

    African Journals Online (AJOL)

    Azadirachta indica (neem) leaf powder was used as an adsorbent for the removal of textile dye from aqueous solution. The adsorption of dye on A. indica was found to be dependent on contact time, dye concentration and amount of adsorbent. Spectrophotometric technique was used for the measurement of concentration of ...

  11. Removal of Uranium from Aqueous Solutions using Ammonium ...

    African Journals Online (AJOL)

    NICOLAAS

    of lead from aqueous solution onto untreated orange barks, Chem. Engin. Trans., 2013, 32, 55–60. 36 E.N.Bakatula, Biofunctionalisation and Influence on Remediation capacity of Bentonite and Zeolite for Metal Remediation in Gold Mine and Tailing. Water, Ph.D. thesis, University of the Witwatersrand, Johannesburg,.

  12. Removal of phosphate and nitrate from aqueous solution using ...

    African Journals Online (AJOL)

    The aim of the present study was the removal of phosphate and nitrate by sodium alginate seagrass (Cymodocea rotundata) beads from aqueous solutions. The adsorption characteristics of phosphate and nitrate on the seagrass beads were optimized under different operational parameters like adsorbent dosage, initial ...

  13. Gamma radiolysis of aerated aqueous solution of cytosine. Pt. 3

    International Nuclear Information System (INIS)

    Polverelli, M.; Teoule, R.

    1976-01-01

    In gamma-irradiation of cytosine in aerated aqueous solution, two new radiolysis products were isolated and identified: 1-carbamoyl-5-hydroxyhydantoin and N-formyl-biuret. This formation involves ring cleavage between C4 and C5 and belongs to the nondeamination pathway. (orig.) [de

  14. REMOVAL OF Ni(II) FROM AQUEOUS SOLUTION USING LEAF ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. The present study investigates the possibility of using leaf, bark and seed of Moringa stenopetala as alternative adsorbents for removal of Ni(II) from aqueous solutions. The optimum adsorption conditions for removal of Ni(II) were found to be 30, 20 and 50 mg/L initial concentration, 1.5, 2 and 2.5 g adsorbent ...

  15. Lead ions removal from aqueous solution using modified carbon ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... Abstract. Surface-modified carbon nanotubes (CNTs) were prepared in order to remove lead ions (Pb2+) from aqueous solution. The modification of CNTs was conducted by oxidation, using a mixture of nitric acid (HNO3) and sulphuric acid. (H2SO4). The adsorption behaviour was well fitted to the ...

  16. Removal of zinc ions from aqueous solution using micellar ...

    African Journals Online (AJOL)

    Removal of zinc ions from aqueous solution using micellar- enhanced ultrafiltration at low surfactant concentrations. ... adsorption isotherm to the SDS micelle. The study demonstrates the potential practicality of the MEUF technique for the removal of heavy metal ion pollutants such as Zn2+ at low surfactant concentrations ...

  17. Removal of heavy metals from aqueous solution by using mango ...

    African Journals Online (AJOL)

    user

    2011-03-14

    Mar 14, 2011 ... biomass indicates that they are effective in removing metal ions from single metal solutions as well as other co-ions with ... been devised for the treatment and removal of heavy metals. The commonly used procedures for removing metal ions from aqueous streams include phyto- ...... Removal of uranium (vi).

  18. Adsorption of Rhodamine B Dye from Aqueous Solution on Irvingia ...

    African Journals Online (AJOL)

    Raw Irvingia gabonenses (dika nut) (DN) and its acid-treated form(ADN) were used for the uptake of rhodamineB(RhB) dye from aqueous solution. The adsorbents were characterized by Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett– Teller (BET) surface area analysis and scanning electron microscopy ...

  19. Equilibrium Sorption Studies of Hg (II) Ions from Aqueous Solution ...

    African Journals Online (AJOL)

    The potential of swamp arum (Lasimorpha senegalensis) seeds as a low-cost adsorbent for the removal of Hg (II) ions from aqueous solution was investigated in this study. The influence of initial metal concentration on the percent adsorption of Hg (II) ions onto powdered swamp arum seeds was studied in a batch system ...

  20. Arsenic (III Adsorption Using Palladium Nanoparticles from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Farzaneh Arsiya

    2017-07-01

    Full Text Available The presence of Arsenic in drinking water is the greatest threat to health effects especially in water. The purpose of this study is application of green palladium nanoparticles for removal of trivalent Arsenic from aqueous solutions and also the impact of some factors such as retention time, pH, concentration of palladium nanoparticles and Arsenic concentrations was studied. The values for Arsenic removal from aqueous solutions were measured by furnace atomic adsorption spectrometry (Conter AA700. In the study, Langmuir and Freundlich isotherm models and pseudo-second order kinetic model were studied. The results of  optimization is shown that 0.5 g of nanoparticles can removed %99.8 of Arsenic with initial concentration of  0.5 g/l, in 5 minutes at pH=4. Langmuir model, Freundlich model (R2=0.94 and pseudo-second order kinetic model (R2=0.99 shown high correlation for removing of Arsenic from aqueous solutions. It was found, palladium nanoparticles can be used as an efficient method to remove Arsenic from aqueous solutions in a short time.

  1. Analysis and modeling of alkali halide aqueous solutions

    DEFF Research Database (Denmark)

    Kim, Sun Hyung; Anantpinijwatna, Amata; Kang, Jeong Won

    2016-01-01

    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...

  2. Aqueous interactions of zeolitic material in acidic and basic solutions

    OpenAIRE

    Polatoğlu, İlker; Çakıcıoğlu Özkan, Seher Fehime

    2010-01-01

    Aqueous interactions of natural zeolitic material in as-received and modified forms were studied. The zeolitic materials was interacted with acidic (hydrochloric acid, lactic acid, acetic acid) and basic (sodium hydroxide) solutions. Ion exchange, adsorption, complex formation, precipitation and cation hydrolysis were possible interaction mechanisms affected by the amount and cation content of zeolite and pH. The dominant mechanisms seemed to be ion exchange and adsorption in HCl solution whe...

  3. Modelling of flame temperature of solution combustion synthesis of ...

    Indian Academy of Sciences (India)

    Hydroxyapatite (HAp), an important bio-ceramic was successfully synthesized by combustion in the aqueous system containing calcium nitrate-di-ammonium hydrogen orthophosphate-urea. The combustion flame temperature of solution combustion reaction depends on various process parameters, and it plays a significant ...

  4. Investigating self-assembly and metal nanoclusters in aqueous di-block copolymers solutions

    CERN Document Server

    Lo Celso, F; Triolo, R; Triolo, A; Strunz, P; Bronstein, L; Zwanziger, J; Lin, J S

    2002-01-01

    Self-assembling properties of di-block copolymers/ surfactant hybrids in aqueous solution can be exploited to obtain metal nanoparticles stable dispersion. Results will be presented here for polystyrene-block-poly(ethylene oxide) solutions. A SANS structural investigation has been performed over different molecular weights of both hydrophilic and hydrophobic block, by varying temperature and concentration of the copolymer. A SAXS characterization of micellar systems containing Pt nanoparticles is reported. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-03

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

  6. Reentrant condensation of lysozyme: Implications for studying dynamics of lysozyme in aqueous solutions of lithium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Mamontov, Eugene [ORNL; O' Neill, Hugh Michael [ORNL

    2014-01-01

    Recent studies have outlined the use of eutectic solution of lithium chloride in water to study microscopic dynamics of lysozyme in an aqueous solvent that is remarkably similar to pure water in many respects, yet allows experiments over a wide temperature range without the solvent crystallization. The eutectic point in (H2O)R(LiCl) system corresponds to R 7.3, and it is of interest to investigate whether less concentrated aqueous solutions of LiCl could be employed in low-temperature studies of a solvated protein. We have investigated a range of concentrations of lysozyme and LiCl in aqueous solutions to identify systems that do not show phase separation and avoid solvent crystallization on cooling down. Compared to the lysozyme concentration in solution, the concentration of LiCl in the aqueous solvent plays the major role in determining systems suitable for low-temperature studies. We have observed interesting and rich phase behavior reminiscent of reentrant condensation of proteins.

  7. Thermodynamic characteristics of protolytic equilibria of L-serine in aqueous solutions

    Science.gov (United States)

    Kochergina, L. A.; Volkov, A. V.; Khokhlova, E. A.; Krutova, O. N.

    2011-05-01

    The heat effects of the reaction of aqueous solution of L-serine with aqueous solutions of HNO3 and KOH were determined by calorimetry at temperatures of 288.15, 298.15, and 308.15 K, and ionic strength values of 0.2, 0.5, and 1.0 (background electrolyte, KNO3). Standard thermodynamic characteristics (Δr H o, Δr G o, Δr S o, Δ C {/p o}) of the acid-base reactions in aqueous solutions of L-serine were calculated. The effect of the concentration of background electrolyte and temperature on the heats of dissociation of amino acid was considered. The combustion energy of L-serine by bomb calorimetry in the medium of oxygen was determined. The standard combustion and formation enthalpies of crystalline L-serine were calculated. The heats of dissolution of crystalline L-serine in water and solutions of potassium hydroxide at 298.15 K were measured by direct calorimetry. The standard enthalpies of formation of L-serine and products of its dissociation in aqueous solution were calculated.

  8. 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.

  9. Assembly of DNA Architectures in a Non-Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Thomas J. Proctor

    2012-08-01

    Full Text Available In the present work, the procedures for the creation of self-assembled DNA nanostructures in aqueous and non-aqueous media are described. DNA-Surfactant complex formation renders the DNA soluble in organic solvents offering an exciting way to bridge the transition of DNA origami materials electronics applications. The DNA retains its structural features, and these unique geometries provide an interesting candidate for future electronics and nanofabrication applications with potential for new properties. The DNA architectures were first assembled under aqueous conditions, and then characterized in solution (using circular dichroism (CD spectroscopy and on the surface (using atomic force microscopy (AFM. Following aqueous assembly, the DNA nanostructures were transitioned to a non-aqueous environment, where butanol was chosen for optical compatibility and thermal properties. The retention of DNA hierarchical structure and thermal stability in non-aqueous conditions were confirmed via CD spectroscopy. The formation and characterization of these higher order DNA-surfactant complexes is described in this paper.

  10. 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.

  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. Electrostatic interactions in aqueous solutions of polyelectrolyte

    International Nuclear Information System (INIS)

    Belloni, Luc

    1982-01-01

    In this study, the structure, equilibrium and transport properties of poly-electrolytes solutions are reported. These dissymmetric systems are studied in the context of a primitive model (Charged hard spheres and rods in a solvent continuum). The first phenomenon studied is the strong electrostatic attractive interaction of counterions on the poly-ion surface. The model used considers the poly-ions on a matrix and the different concentrations are calculated using the P.B. equation. Auto-diffusion coefficients obtained give a good description of experimental slowing down of the counterions. The model allows a correlation between the theoretical limits represented by Bjerrum's and Manning's models and gives a physical significance to the concept of condensation. In the second part, the complete structure is calculated using only slightly restrictive H.N.C. approximation. This theory enables all the pair correlation functions to be calculated as well as thermodynamic data and structure factors. The last part of this study treats transport phenomena. Quasi-elastic light scattering gives information on the autocorrelation function of the scattered light intensity. Analysis using cumulants leads to an effective diffusion coefficient which is theoretically related to the structure factor and the hydrodynamic interactions. A crude approximation of the last contribution allows to fit the experimental data. (author) [fr

  13. ELVIS: Multi-Electrolyte Aqueous Activity Model for Geothermal Solutions

    Science.gov (United States)

    Hingerl, F. F.; Wagner, T.; Driesner, T.; Kulik, D. A.; Kosakowski, G.

    2011-12-01

    High temperature, pressure, and fluid salinities render geochemical modeling of fluid-rock interactions in Enhanced Geothermal Systems a demanding task. Accurate prediction of fluid-mineral equilibria strongly depends on the availability of thermodynamic data and activity models. Typically, the Pitzer activity model is applied for geothermal fluids. A drawback of this model is the large number of parameters required to account for temperature and pressure dependencies, which significantly reduces computational efficiency of reactive transport simulations. In addition, most available parameterizations are valid only at vapor-saturated conditions. As an alternative we implemented the EUNIQUAC local composition model [2] that needs substantially fewer fitting parameters. However, the current EUNIQUAC model design does not include provision for high temperature (>150°C) applications and lacks a formulation for pressure dependence. Therefore, its application to geothermal conditions requires a re-formulation and re-fitting of the model. We developed a new tool termed GEMSFIT that allows generic fitting of activity models (for aqueous electrolyte and non-electrolyte solutions) and equations of state implemented in our geochemical equilibrium solver GEM-Selektor (http://gems.web.psi.ch). GEMSFIT combines a PostgreSQL database for storing and managing the datasets of experimental measurements and interaction parameters, the parallelized genetic algorithm toolbox of MATLAB° for the parameter fitting, and an interface to the numerical kernel of GEM-Selektor to access activity models and perform chemical equilibrium calculations. Benchmarking of the partly re-parameterized EUNIQUAC model against Pitzer revealed that the former is less accurate, which can result in incorrect predictions of mineral precipitation/dissolution. Consequently, we modified the EUNIQUAC model and concurrently introduced a pressure dependence to be able to fit experimental data over wide ranges of

  14. Absorption performance for CO2 capture process using MDEA-AMP aqueous solution

    Science.gov (United States)

    Liu, Gang; Kou, Liqing; Li, Chao

    2017-03-01

    The absorption capacity and the absorption rate of CO2 in 2-amino-2-methyl-1-propanol (AMP)-N-methyldiethanolamine (MDEA) aqueous solution were measured. The temperatures ranged from 303.2K to 323.2K. The mass fractions of AMP and MDEA respectively ranged from 0 to 0.03 and 0.2 to 0.3. The influence of temperature and w AMP on the absorption capacity and absorption rate of CO2 was illustrated.

  15. Radiation resistance of organic azo dyes in aqueous solutions

    International Nuclear Information System (INIS)

    Khabarov, V.N.; Kozlov, L.L.

    1987-01-01

    The resistance to the action of the ionizing radiation of aqueous and aqueous-alcoholic solutions of organic mono- and diazo dyes was studied. The radiation chemical yield of decolorization of the dye, determined from the kinetic decolorization curves served as a quantitative criterion of the radiation resistance. The influence of pH, addition of ethanol, hydroquinone, thiourea, glucose and oxygen on the radiation resistance of the azo dyes was studied. An attempt was made to relate the efficiency of radiation decolorization to the chemical nature of the dye

  16. Solvation properties of N-substituted cis and trans amides are not identical: significant enthalpy and entropy changes are revealed by the use of variable temperature 1H NMR in aqueous and chloroform solutions and ab initio calculations.

    Science.gov (United States)

    Troganis, Anastassios N; Sicilia, Emilia; Barbarossou, Klimentini; Gerothanassis, Ioannis P; Russo, Nino

    2005-12-29

    The cis/trans conformational equilibrium of N-methyl formamide (NMF) and the sterically hindered tert-butylformamide (TBF) was investigated by the use of variable temperature gradient 1H NMR in aqueous solution and in the low dielectric constant and solvation ability solvent CDCl3 and various levels of first principles calculations. The trans isomer of NMF in aqueous solution is enthalpically favored relative to the cis (deltaH(o) = -5.79 +/- 0.18 kJ mol(-1)) with entropy differences at 298 K (298 x deltaS(o) = -0.23 +/- 0.17 kJ mol(-1)) playing a minor role. The experimental value of the enthalpy difference strongly decreases (deltaH(o) = -1.72 +/- 0.06 kJ mol(-1)), and the contribution of entropy at 298 K (298 x deltaS(o) = -1.87 +/- 0.06 kJ mol(-1)) increases in the case of the sterically hindered tert-butylformamide. The trans isomer of NMF in CDCl3 solution is enthalpically favored relative to the cis (deltaH(o) = -3.71 +/- 0.17 kJ mol(-1)) with entropy differences at 298 K (298 x deltaS(o) = 1.02 +/- 0.19 kJ mol(-1)) playing a minor role. In the sterically hindered tert-butylformamide, the trans isomer is enthalpically disfavored (deltaH(o) = 1.60 +/- 0.09 kJ mol(-1)) but is entropically favored (298 x deltaS(o) = 1.71 +/- 0.10 kJ mol(-1)). The results are compared with literature data of model peptides. It is concluded that, in amide bonds at 298 K and in the absence of strongly stabilizing sequence-specific inter-residue interactions involving side chains, the free energy difference of the cis/trans isomers and both the enthalpy and entropy contributions are strongly dependent on the N-alkyl substitution and the solvent. The significant decreasing enthalpic benefit of the trans isomer in CDCl3 compared to that in H2O, in the case of NMF and TBF, is partially offset by an adverse entropy contribution. This is in agreement with the general phenomenon of enthalpy versus entropy compensation. B3LY/6-311++G** and MP2/6-311++G** quantum chemical calculations

  17. 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. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Sorption of lead from aqueous solution by modified activated carbon ...

    African Journals Online (AJOL)

    They were based on using powdered activated carbon (PACI), which was prepared from olive stones generated, as plant wastes, and modified with aqueous oxidizing agent such as (NH 4)2S2O8. The main parameters (pH, sorbent, lead concentrations, stirring times and temperature) influencing the sorption process in ...

  19. Aqueous synthesis and characterization of TGA-capped CdSe quantum dots at freezing temperature.

    Science.gov (United States)

    Sun, Qizhuang; Fu, Shasha; Dong, Tingmei; Liu, Shuxian; Huang, Chaobiao

    2012-07-11

    CdSe quantum dots (QDs) have traditionally been synthesized in organic phase and then transferred to aqueous solution by functionalizing their surface with silica, polymers, short-chain thiol ligands, or phospholipid micelles. However, a drastic increase in the hydrodynamic size and biotoxicity of QDs may hinder their biomedical applications. In this paper, the TGA-capped CdSe QDs are directly synthesized in aqueous phase at freezing temperature, and they prove to possess high QY (up to 14%).

  20. Unusual radiolytic behavior of neptunium ions in aqueous bicarbonate solutions

    International Nuclear Information System (INIS)

    Shilov, V.P.; Gogolev, A.V.; Pikaev, A.K.

    2000-01-01

    Behavior of neptunium ions in carbonate and bicarbonate aqueous solutions saturated with air, oxygen or argon during gamma radiation ( 60 Co) by doses up to 3 kGy at dose rates 10 and 25 Gy/min was studied by the method of spectrophotometry. It is shown that in neptunium (5) bicarbonate solution nearly complete (95%) neptunium ion oxidation occurs under the effect of radiation, whereas no oxidation is observed in carbonate solution. Radiation-chemical yield of neptunium (5) oxidation and stationary concentration of neptunium (6) ions depend on concentration of bicarbonate-ions. Explanation to the results obtained is made from the viewpoint of potential radiolytic reactions [ru

  1. Biosorption of strontium ions from aqueous solution using Ca-alginate biopolymer beads

    International Nuclear Information System (INIS)

    Goek, C.; Aytas, S.; Gerstmann, U.

    2009-01-01

    Biosorption of strontium ions from aqueous solution onto calcium alginate biopolymer beads was investigated in a batch system. Ca-alginate biopolymer beads were prepared from Na-alginate via cross-linking with divalent calcium ions according to the egg box model. Optimum biosorption conditions were determined as a function of initial solution pH, initial Sr concentration, contact time, biomass dosage and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of Sr ions by Ca-alginate biopolymer beads. The thermodynamic parameters (ΔH, ΔS, ΔG) for Sr sorption onto biosorbent were also determined from the temperature dependence. The results indicate that this biosorbent has a good potential for removal of Sr ions from dilute aqueous solution.

  2. Thermodynamic Modeling of Surface Tension of Aqueous Electrolyte Solution by Competitive Adsorption Model

    Directory of Open Access Journals (Sweden)

    Mohamad Javad Kamali

    2015-01-01

    Full Text Available Thermodynamic modeling of surface tension of different electrolyte systems in presence of gas phase is studied. Using the solid-liquid equilibrium, Langmuir gas-solid adsorption, and ENRTL activity coefficient model, the surface tension of electrolyte solutions is calculated. The new model has two adjustable parameters which could be determined by fitting the experimental surface tension of binary aqueous electrolyte solution in single temperature. Then the values of surface tension for other temperatures in binary and ternary system of aqueous electrolyte solution are predicted. The average absolute deviations for calculation of surface tension of binary and mixed electrolyte systems by new model are 1.98 and 1.70%, respectively.

  3. Solvation consequences of polymer PVP with biological buffers MES, MOPS, and MOPSO in aqueous solutions

    International Nuclear Information System (INIS)

    Gupta, Bhupender S.; Chen, Bo-Ren; Lee, Ming-Jer

    2015-01-01

    Highlights: • Densities and viscosities data for aqueous solutions with PVP and/or buffer. • The studied buffers include MES, MOPS, and MOPSO. • DFT was used to estimate the binding energies of the (PVP + buffer) complexes. • The viscosity data were correlated with the Jones–Dole equation. • The investigated buffers behave as Kosmotropies. - Abstract: Densities and viscosities were measured for the aqueous buffer (MES, MOPS, or MOPSO) solutions containing different concentrations of polyvinylpyrrolidone (PVP) (5, 10, 15, 20 and 30) mass% at temperatures from (298.15 to 318.15) K under atmospheric pressure. The DFT calculations were also performed and the binding energies of the possible (PVP + buffer) complexes were obtained. The experimental and computational results reveal the interactions of the PVP with the constituent compounds in the aqueous buffer solutions. Additionally we have explored the solvation behavior of the buffers by measuring the densities and the viscosities data of the aqueous buffer solutions from (0.0 to 1.0) mol · kg −1 at temperatures from (298.15 to 318.15) K. The viscosity results were correlated with the Jones–Dole equation. The correlated results confirmed that all the investigated buffers behave as Kosmotropes (structure makers).

  4. Formation of the second organic phase during uranyl nitrate extraction from aqueous solution by 30% tributylphosphate solution in paraffin

    International Nuclear Information System (INIS)

    Yhrkin, V.G.

    1996-01-01

    For extraction systems aqueous solution of uranyl nitrate-30% solution of tributylphosphate in individual paraffins from C 13 to C 17 the influence of the second organic phase of uranyl nitrate concentration in aqueous and organic phases, the length of hydrocarbon chain of paraffin hydrocarbon and temperature from 25 to 50 deg C on formation conditions has been defected. A special method of achieving the conditions of organic phase stratification from three-phase region, involving definition of equilibrium phases composition by density and refractive index, has been elaborated for more precise definition of organic phase homogeneity region. It has been revealed that without addition of nitric acid to uranyl nitrate solution the organic phase homogeneity limits can be achieved solely on paraffins C 15 , C 16 and C 17 and only under conditions similar to equeous phase saturation in terms of uranyl nitrate. 16 refs., 2 figs

  5. The effect of dimethylsulfoxide on absorption and fluorescence spectra of aqueous solutions of acridine orange base.

    Science.gov (United States)

    Markarian, Shiraz A; Shahinyan, Gohar A

    2015-12-05

    The photophysical properties of aqueous solutions of acridine orange base (AOB) in wide concentration range of dimethylsulfoxide (DMSO) were studied by using absorption and steady-state fluorescence spectroscopy techniques at room temperature. The absorption spectrum of acridine orange in water shows two bands at 468 and 490 nm which were attributed to the dimer ((AOBH)2(2+)) and monomer (AOBH(+)) species respectively. In DMSO solution for the same AOB concentration only the basic form was detected with the band at 428 nm. The addition of DMSO to AOB aqueous solution leads to the decrease of absorption band at 490 nm and the new absorption band increases at 428 nm due to deprotonated (basic) form of AO and the first isosbestic point occurs at 450 nm. The evolution of isosbestic point reveals that an other equilibrium, due to the self-association of DMSO molecules takes place. From the steady-state fluorescence spectra Stokes shifts were calculated for AOB in aqueous and DMSO solutions. The addition of DMSO into the aqueous solution induced the enhancement in the fluorescence intensity of the dye compared to those in water. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Radiolytic degradation of malathion and lindane in aqueous solutions

    International Nuclear Information System (INIS)

    Mohamed, K.A.; Basfar, A.A.; Al-Kahtani, H.A.; Al-Hamad, K.S.

    2009-01-01

    Degradation of malathion and lindane pesticides present in an aqueous solution was investigated on a laboratory scale upon gamma-irradiation from a 60 Co 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 (N 2 O) and HS/N 2 O (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, N 2 O and HS/N 2 O 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).

  7. Water Evaporation from Acoustically Levitated Aqueous Solution Droplets.

    Science.gov (United States)

    Combe, Nicole A; Donaldson, D James

    2017-09-28

    We present a systematic study of the effect of solutes on the evaporation rate of acoustically levitated aqueous solution droplets by suspending individual droplets in a zero-relative humidity environment and measuring their size as a function of time. The ratios of the early time evaporation rates of six simple salts (NaCl, NaBr, NaNO 3 , KCl, MgCl 2 , CaCl 2 ) and malonic acid to that of water are in excellent agreement with predictions made by modifying the Maxwell equation to include the time-dependent water activity of the evaporating aqueous salt solution droplets. However, the early time evaporation rates of three ammonium salt solutions (NH 4 Cl, NH 4 NO 3 , (NH 4 ) 2 SO 4 ) are not significantly different from the evaporation rate of pure water. This finding is in accord with a previous report that ammonium sulfate does not depress the evaporation rate of its solutions, despite reducing its water vapor pressure, perhaps due to specific surface effects. At longer evaporation times, as the droplets approach crystallization, all but one (MgCl 2 ) of the solution evaporation rates are well described by the modified Maxwell equation.

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

    International Nuclear Information System (INIS)

    Elbanowski, M.; Lis, S.; Makowska, B.; Konarski, J.

    1985-01-01

    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)

  9. 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...

  10. Removal of Toxic Metals from Aqueous Solution by Saw Dust ...

    African Journals Online (AJOL)

    In this work, feasibility studies of using a natural and low cost adsorbent; saw dust for the removal of Cr(VI), Ni(II), Fe(II) and Cd(II) from aqueous solution was carried out. The efficiency of the adsorbent was judged from the variation of the % adsorption with (i) contact time, (ii) adsorbent dose, (iii) initial metal ion concentration ...

  11. Degradation of Para-Phenylenediamine in Aqueous Solution by ...

    African Journals Online (AJOL)

    In this research Photo-Fenton Oxidation of Para-Phenylenediamine (PPD) in aqueous solution by UV/Fenton's reagent (Fe2+ and H2O2) was investigated. Experiments were conducted in a batch reactor, at pH 3.5 and at 25°C with a source of UV-C light. The effects of different reaction parameters such as initial PPD ...

  12. Retention of 131I volatilized from aqueous solutions by sorbents

    International Nuclear Information System (INIS)

    Deuber, H.

    1985-02-01

    By far the largest proportion of the I-131 that was volatilized from alkaline aqueous solutions was in a form whose retention by various sorbents was lower than that of I 2 , but higher than that of CH 3 I. This form is called 'HOI' although no direct identification exists. With all the fresh impregnated activated carbons investigated, the retention of 'HOI' was higher than 99% at a residence time of 0.1 s. The influence of purging was insignificant. (orig.) [de

  13. Design of non-molecular coordination solids from aqueous solution ...

    Indian Academy of Sciences (India)

    J. Chem. Sci. Vol. 126, No. 5, September 2014, pp. 1433–1442. c Indian Academy of Sciences. Design of non-molecular coordination solids from aqueous solution: [Cu. II. LnX(H2O)], where X=SO4, Cl or H2O and L=pyrazole, imidazole or glutamic acid and n=1 or 4. VINEET KUMARa, ARITRA KUNDUa, MONIKA SINGHa,.

  14. Pulse-Radiolysis of Aqueous KBrO4 Solutions

    DEFF Research Database (Denmark)

    Olsen, K. J.; Sehested, Knud; Appelman, L.H.

    1973-01-01

    Pulse-radiolysis of aqueous KBrO4 solutions show that BrO−4 reacts with e−aq by the reaction BrO−4 + e−aq → BrO−3 + O−. keaq + BrO−4 = (7.0 ± 0.7) × 109 M−1 sec−1. The reactions between BrO−4 and H, OH and O− are slow. The rate constants for these reactions are less than 107 M−1 sec−1....

  15. Pulse Radiolysis of Methyl Viologen in Aqueous Solutions

    DEFF Research Database (Denmark)

    Solar, S.; Solar, W.; Getoff, N.

    1982-01-01

    Pulse radiolysis of air-free aqueous methyl viologen (MV2+) solutions was carried out at various pH. The attack of e–aq on MV2+, with k(e–aq+ MV2+)= 7.5 × 1010 dm3 mol–1 s–1, leads to the formation of the long-lived radical cation (MV˙+), which possesses two absorption maxima at 392.5 nm (ε392.5...

  16. 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‐cont...

  17. Study on radiation-induced deactivation and post-deactivation of some oxidoreductases in dilute aqueous solution and protective effect: Pt. 1

    International Nuclear Information System (INIS)

    Chen Yiqing; Ha Hongfei

    1993-01-01

    In this work the radiation-induced deactivation of catalase in dilute aqueous solution was reported. The effects of irradiation atmosphere, temperature and original concentration of catalase in dilute aqueous solutions on the deactivation of catalase were investigated. The protective effect by some additives (CH 3 CH 2 OH, HCOONa and EDTA) to radiation deactivation in dilute aqueous solutions was also studied. Remarkable protective effect by those additives was observed. The mechanism of radiation deactivation and protective effect have been discussed

  18. Redox-switched amphiphilic ionic liquid behavior in aqueous solution.

    Science.gov (United States)

    Chamiot, Bénédicte; Rizzi, Cécile; Gaillon, Laurent; Sirieix-Plénet, Juliette; Lelièvre, Joël

    2009-02-03

    A new redox amphiphilic ionic liquid (AIL) containing ferrocene as a redox-active group was synthesized, 1-(11-ferrocenylundecyl)-3-methylimidazolium bromide (Fc11MIm+). Adsorption and aggregation of both reduced and oxidized forms of this ferrocenated AIL in aqueous solution were studied by surface tension measurements. The micellization was favored for the reduced ferrocenated AIL (Fc11MIm+) as compared with the oxidized ferrocenated AIL (Fc+11MIm+). Minimum areas at the air/aqueous solution interface were identical whereas limiting surface tensions were slightly different. This corroborated the formation of an expanded monolayer of redox active AIL at the interface. The electrochemical behavior of redox active AIL was investigated. The electrochemical responses of Fc11MIm+ aqueous solution interestingly differed, depending on its concentration. Below the cmc, the electrochemical reaction was dominated by ferrocenated AIL adsorbed onto the electrode surface; then above the cmc, it was controlled by the Fc11MIm+ diffusing to the electrode. For the latter, the electrochemical mechanism was suggested to couple with the disruption reaction of the reduced form micelles.

  19. Aqueous ozone solutions for pesticide removal from potatoes.

    Science.gov (United States)

    Heleno, Fernanda F; de Queiroz, Maria Eliana Lr; Faroni, Lêda Ra; Neves, Antônio A; de Oliveira, André F; Costa, Luiz Pl; Pimenta, Gustavo G

    2016-12-01

    The presence of pesticide residues in potatoes is of concern because of the potential impact to human health due to the high consumption of this vegetable. In this study, aqueous solutions with and without ozone saturation as postharvest wash treatment at pH 4.0, 7.0, and 9.0 were tested to remove chlorothalonil from potatoes. The method used for pesticide analysis has been validated, presenting recovery values of 94-103%, with variations in the repeatability coefficients of ≤10.6%, and a quantification limit of 0.05 mg kg -1 Regardless of pH, treatment with aqueous ozone solutions removed 70-76% of the pesticide present in the potato. In the no-ozone treatments, the percentage average removal of chlorothalonil residues in potatoes was only 36%. Over 24 days of storage, the quality of potatoes washed with aqueous ozone solutions was not significantly different from those washed with pure water. © The Author(s) 2016.

  20. 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.

  1. Dynamic viscoelastic properties of cellulose carbamate dissolved in NaOH aqueous solution.

    Science.gov (United States)

    Guo, Yi; Zhou, Jinping; Zhang, Lina

    2011-05-09

    Dynamic viscoelastic properties of cellulose carbamate (CC) dissolved in NaOH aqueous solution were systematically studied for the first time. CC was microwave-assisted synthesized from the mixture of cellulose and urea and then dissolved in 7 wt % NaOH aqueous solution precooled to -7 °C. The obtained CC solution is transparent and has good liquidity. To clarify the rheological behavior of the solution, the CC solutions were investigated by dynamic viscoelastic measurements. The shear storage modulus (G') and loss modulus (G'') as a function of the angular frequency (ω), concentration (c), nitrogen content (N %), viscosity-average molecular weight (M(η)), temperature (T), and time (t) were analyzed and discussed in detail. The sol-gel transition temperature of CC (M(η) = 7.78 × 10(4)) solution decreased from 36.5 to 31.3 °C with an increase of the concentration from 3.0 to 4.3 wt % and decreased from 35.7 to 27.5 °C with an increase of the nitrogen content from 1.718 to 5.878%. The gelation temperature of a 3.8 wt % CC solution dropped from 38.2 to 34.4 °C with the M(η) of CC increased from 6.35 × 10(4) to 9.56 × 10(4). The gelation time of the CC solution was relatively short at 30 °C, but the solution was stable for a long time at about 15 °C. Moreover, the gels already formed at elevated temperature were irreversible; that is, after cooling to a lower temperature including the dissolution temperature (-7 °C), they could not be dissolved to become liquid.

  2. ENTIRELY AQUEOUS SOLUTION-GEL ROUTE FOR THE PREPARATION OF ZIRCONIUM CARBIDE, HAFNIUM CARBIDE AND THEIR TERNARY CARBIDE POWDERS

    Directory of Open Access Journals (Sweden)

    Zhang Changrui

    2016-07-01

    Full Text Available An entirely aqueous solution-gel route has been developed for the synthesis of zirconium carbide, hafnium carbide and their ternary carbide powders. Zirconium oxychloride (ZrOCl₂.8H₂O, malic acid (MA and ethylene glycol (EG were dissolved in water to form the aqueous zirconium carbide precursor. Afterwards, this aqueous precursor was gelled and transformed into zirconium carbide at a relatively low temperature (1200 °C for achieving an intimate mixing of the intermediate products. Hafnium and the ternary carbide powders were also synthesized via the same aqueous route. All the zirconium, hafnium and ternary carbide powders exhibited a particle size of ∼100 nm.

  3. The blue complexes of U in aqueous solutions

    International Nuclear Information System (INIS)

    Musikas, C.

    1976-01-01

    Mixed-valence uranium complexes were synthesized. Hydrolysis of hexavalent U leads to anionic species soluble in aqueous solutions when the UO 2 ++ ions are neutralized by tetraalkylammonium hydroxides. These complexes are polynuclear and the size and interatomic distances found for the polyanions are those of macromolecules. By hydrazine of these complexes, solutions were obtained and their absorption spectra studied. The spectra of U(VI) and U(V) ions are observed, together with new bands attributable to a charge transfer. It may be concluded that the blue complexes of uranium are type II composite-valence complexes for which the delocalization coefficient α can be calculated [fr

  4. Oscillometric and conductometric analysis of aqueous and organic dosimeter solutions

    DEFF Research Database (Denmark)

    Kovacs, A.; Slezsak, I.; McLaughlin, W.L.

    1995-01-01

    ''conductometric'' electrodes and the study of the effect of frequency on the sensitivity of the method. On the basis of these investigations an oscillometric reader has been designed and tested. The same evaluation methods have been tested on the irradiated aqueous alanine solutions, aiming also at the study...... of the applicable concentration of the alanine solute and the dose (1 to 50 kGy) and dose-rate range using both electron (2.6 mu s at 13 mu A to 4 mu s at 1.0 A pulse length and beam current) and gamma radiation (0.13 to 30 kGy h(-1))....

  5. Reaction kinetics of iodine compounds in aqueous solution

    International Nuclear Information System (INIS)

    Sellers, R.M.

    1985-11-01

    A review is presented of the reaction kinetics of inorganic iodine species in aqueous solution, and describes the establishment of a kinetics data base for use in computer modelling of iodine release in PWR design basis faults. A data base of 167 reactions has been established to describe the behaviour of inorganic iodine species in solution. Organic iodides have been omitted because of the lack of understanding about how they are formed. A number of inadequacies in the data base requiring further research are noted. (author)

  6. Biosorption of chromium (VI) from aqueous solutions and ANN modelling.

    Science.gov (United States)

    Nag, Soma; Mondal, Abhijit; Bar, Nirjhar; Das, Sudip Kumar

    2017-08-01

    The use of sustainable, green and biodegradable natural wastes for Cr(VI) detoxification from the contaminated wastewater is considered as a challenging issue. The present research is aimed to assess the effectiveness of seven different natural biomaterials, such as jackfruit leaf, mango leaf, onion peel, garlic peel, bamboo leaf, acid treated rubber leaf and coconut shell powder, for Cr(VI) eradication from aqueous solution by biosorption process. Characterizations were conducted using SEM, BET and FTIR spectroscopy. The effects of operating parameters, viz., pH, initial Cr(VI) ion concentration, adsorbent dosages, contact time and temperature on metal removal efficiency, were studied. The biosorption mechanism was described by the pseudo-second-order model and Langmuir isotherm model. The biosorption process was exothermic, spontaneous and chemical (except garlic peel) in nature. The sequence of adsorption capacity was mango leaf > jackfruit leaf > acid treated rubber leaf > onion peel > bamboo leaf > garlic peel > coconut shell with maximum Langmuir adsorption capacity of 35.7 mg g -1 for mango leaf. The treated effluent can be reused. Desorption study suggested effective reuse of the adsorbents up to three cycles, and safe disposal method of the used adsorbents suggested biodegradability and sustainability of the process by reapplication of the spent adsorbent and ultimately leading towards zero wastages. The performances of the adsorbents were verified with wastewater from electroplating industry. The scale-up study reported for industrial applications. ANN modelling using multilayer perception with gradient descent (GD) and Levenberg-Marquart (LM) algorithm had been successfully used for prediction of Cr(VI) removal efficiency. The study explores the undiscovered potential of the natural waste materials for sustainable existence of small and medium sector industries, especially in the third world countries by protecting the environment by eco-innovation.

  7. Genotoxicity study of photolytically treated 2-chloropyridine aqueous solutions

    International Nuclear Information System (INIS)

    Vlastos, Dimitris; Skoutelis, Charalambos G.; Theodoridis, Ioannis T.; Stapleton, David R.; Papadaki, Maria I.

    2010-01-01

    2-Chloropyridine (2-CPY) has been identified as a trace organic chemical in process streams, wastewater and even drinking water. Furthermore, it appears to be formed as a secondary pollutant during the decomposition of specific insecticides. As reported in our previous work, 2-CPY was readily removed and slowly mineralised when subjected to ultraviolet (UV) irradiation at 254 nm. Moreover, 2-CPY was found to be genotoxic at 100 μg ml -1 but it was not genotoxic at or below 50 μg ml -1 . In this work 2-CPY aqueous solutions were treated by means of UV irradiation at 254 nm. 2-CPY mineralisation history under different conditions is shown. 2-CPY was found to mineralise completely upon prolonged irradiation. Identified products of 2-CPY photolytic decomposition are presented. Solution genotoxicity was tested as a function of treatment time. Aqueous solution samples, taken at different photo-treatment times were tested in cultured human lymphocytes applying the cytokinesis block micronucleus (CBMN) assay. It was found that the solution was genotoxic even when 2-CPY had been practically removed. This shows that photo-treatment of 2-CPY produces genotoxic products. Upon prolonged irradiation solution genotoxicity values approached the control value.

  8. Genotoxicity study of photolytically treated 2-chloropyridine aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Vlastos, Dimitris, E-mail: dvlastos@cc.uoi.gr [Department of Environmental and Natural Resources Management, University of Ioannina, Seferi 2, Agrinio 30100 (Greece); Skoutelis, Charalambos G.; Theodoridis, Ioannis T. [Department of Environmental and Natural Resources Management, University of Ioannina, Seferi 2, Agrinio 30100 (Greece); Stapleton, David R. [Chemical Engineering, IPSE, School of Process Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Papadaki, Maria I. [Department of Environmental and Natural Resources Management, University of Ioannina, Seferi 2, Agrinio 30100 (Greece); Chemical Engineering, IPSE, School of Process Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2010-05-15

    2-Chloropyridine (2-CPY) has been identified as a trace organic chemical in process streams, wastewater and even drinking water. Furthermore, it appears to be formed as a secondary pollutant during the decomposition of specific insecticides. As reported in our previous work, 2-CPY was readily removed and slowly mineralised when subjected to ultraviolet (UV) irradiation at 254 nm. Moreover, 2-CPY was found to be genotoxic at 100 {mu}g ml{sup -1} but it was not genotoxic at or below 50 {mu}g ml{sup -1}. In this work 2-CPY aqueous solutions were treated by means of UV irradiation at 254 nm. 2-CPY mineralisation history under different conditions is shown. 2-CPY was found to mineralise completely upon prolonged irradiation. Identified products of 2-CPY photolytic decomposition are presented. Solution genotoxicity was tested as a function of treatment time. Aqueous solution samples, taken at different photo-treatment times were tested in cultured human lymphocytes applying the cytokinesis block micronucleus (CBMN) assay. It was found that the solution was genotoxic even when 2-CPY had been practically removed. This shows that photo-treatment of 2-CPY produces genotoxic products. Upon prolonged irradiation solution genotoxicity values approached the control value.

  9. Genotoxicity study of photolytically treated 2-chloropyridine aqueous solutions.

    Science.gov (United States)

    Vlastos, Dimitris; Skoutelis, Charalambos G; Theodoridis, Ioannis T; Stapleton, David R; Papadaki, Maria I

    2010-05-15

    2-Chloropyridine (2-CPY) has been identified as a trace organic chemical in process streams, wastewater and even drinking water. Furthermore, it appears to be formed as a secondary pollutant during the decomposition of specific insecticides. As reported in our previous work, 2-CPY was readily removed and slowly mineralised when subjected to ultraviolet (UV) irradiation at 254 nm. Moreover, 2-CPY was found to be genotoxic at 100 microg ml(-1) but it was not genotoxic at or below 50 microg ml(-1). In this work 2-CPY aqueous solutions were treated by means of UV irradiation at 254 nm. 2-CPY mineralisation history under different conditions is shown. 2-CPY was found to mineralise completely upon prolonged irradiation. Identified products of 2-CPY photolytic decomposition are presented. Solution genotoxicity was tested as a function of treatment time. Aqueous solution samples, taken at different photo-treatment times were tested in cultured human lymphocytes applying the cytokinesis block micronucleus (CBMN) assay. It was found that the solution was genotoxic even when 2-CPY had been practically removed. This shows that photo-treatment of 2-CPY produces genotoxic products. Upon prolonged irradiation solution genotoxicity values approached the control value. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  10. 21 CFR 522.380 - Chloral hydrate, pentobarbital, and magnesium sulfate sterile aqueous solution.

    Science.gov (United States)

    2010-04-01

    ... sulfate sterile aqueous solution. 522.380 Section 522.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... sterile aqueous solution. (a) [Reserved] (b)(1) Specifications. Chloral hydrate, pentobarbital, and magnesium sulfate sterile aqueous solution contains 42.5 milligrams of chloral hydrate, 8.86 milligrams of...

  11. Hydrate phase equilibria of CO2+N2+aqueous solution of THF, TBAB or TBAF system

    DEFF Research Database (Denmark)

    Sfaxi, Imen Ben Attouche; Durand, Isabelle; Lugo, Rafael

    2014-01-01

    We report hydrate dissociation conditions of CO2 (15 and 30mol%)+N2 (85 and 70mol%) in the presence of aqueous solutions of THF, TBAB or TBAF. The concentrations of TBAB and TBAF in the aqueous solutions are 5wt% and 9wt% while THF concentration in aqueous solution is 3mol%. Two different experim...

  12. Fabrication of an ultrafine fish gelatin nanofibrous web from an aqueous solution by electrospinning.

    Science.gov (United States)

    Kwak, Hyo Won; Shin, Munju; Lee, Jeong Yun; Yun, Haesung; Song, Dae Woong; Yang, Yesol; Shin, Bong-Seob; Park, Young Hwan; Lee, Ki Hoon

    2017-09-01

    Electrospinning of aqueous gelatin solution obtained from bovine or porcine sources has been difficult to achieve without additional facilities, such as a temperature control oven or heating cover. Gelatin from cold-water fish has low contents of proline (Pro) and hydroxyproline (Hyp) compared with mammalian-derived gelatin. For this reason, the fish-derived gelatin maintains a sol state without showing gelation behavior at room temperature. In the present study, we prepared an ultrafine fish gelatin nanofibrous web by electrospinning from aqueous solutions without any additive polymers or temperature control facilities. The concentration and viscosity of fish gelatin are the most important factor in determining the electrospinnability and fiber diameter. Electrospinning of aqueous fish gelatin has the highest nanofiber productivity compared to other organic solvent systems. Using glutaraldehyde vapor (GTA), the water stability was improved and substantial enhancement was achieved in the mechanical properties. Finally, the cytotoxicity of a fish gelatin nanofibrous scaffold was evaluated based on a cell proliferation study by culturing human dermal fibroblasts (HDFs) compared with a fish gelatin film and nanofibrous mat from mammalian gelatin. The result shows better initial cell attachment and proliferation compared with the fish gelatin film and no significant difference compared with mammalian-derived gelatin nanofibrous mat. We expect that electrospinning of aqueous fish gelatin could be an effective alternative mammalian gelatin source. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. On the structure of an aqueous propylene glycol solution

    Science.gov (United States)

    Rhys, Natasha H.; Gillams, Richard J.; Collins, Louise E.; Callear, Samantha K.; Lawrence, M. Jayne; McLain, Sylvia E.

    2016-12-01

    Using a combination of neutron diffraction and empirical potential structure refinement computational modelling, the interactions in a 30 mol. % aqueous solution of propylene glycol (PG), which govern both the hydration and association of this molecule in solution, have been assessed. From this work it appears that PG is readily hydrated, where the most prevalent hydration interactions were found to be through both the PG hydroxyl groups but also alkyl groups typically considered hydrophobic. Hydration interactions of PG dominate the solution over PG self-self interactions and there is no evidence of more extensive association. This hydration behavior for PG in solutions suggests that the preference of PG to be hydrated rather than to be self-associated may translate into a preference for PG to bind to lipids rather than itself, providing a potential explanation for how PG is able to enhance the apparent solubility of drug molecules in vivo.

  14. 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.

  15. Protein Conformation and Supercharging with DMSO from Aqueous Solution

    Science.gov (United States)

    Sterling, Harry J.; Prell, James S.; Cassou, Catherine A.; Williams, Evan R.

    2011-07-01

    The efficacy of dimethyl sulfoxide (DMSO) as a supercharging reagent for protein ions formed by electrospray ionization from aqueous solution and the mechanism for supercharging were investigated. Addition of small amounts of DMSO to aqueous solutions containing hen egg white lysozyme or equine myoglobin results in a lowering of charge, whereas a significant increase in charge occurs at higher concentrations. Results from both near-UV circular dichroism spectroscopy and solution-phase hydrogen/deuterium exchange mass spectrometry indicate that DMSO causes a compaction of the native structure of these proteins at low concentration, but significant unfolding occurs at ~63% and ~43% DMSO for lysozyme and myoglobin, respectively. The DMSO concentrations required to denature these two proteins in bulk solution are ~3-5 times higher than the concentrations required for the onset of supercharging, consistent with a significantly increased concentration of this high boiling point supercharging reagent in the ESI droplet as preferential evaporation of water occurs. DMSO is slightly more basic than m-nitrobenzyl alcohol and sulfolane, two other supercharging reagents, based on calculated proton affinity and gas-phase basicity values both at the B3LYP and MP2 levels of theory, and all three of these supercharging reagents are significantly more basic than water. These results provide additional evidence that the origin of supercharging from aqueous solution is the result of chemical and/or thermal denaturation that occurs in the ESI droplet as the concentration of these supercharging reagents increases, and that proton transfer reactivity does not play a significant role in the charge enhancement observed.

  16. Copper Extraction from Aqueous Solution by Pentaerythrityl Tetrabenzylamine

    OpenAIRE

    KARA, Derya

    2001-01-01

    The extraction of copper(II) from the aqueous phase with pentaerythrityl tetrabenzylamine (PETBA), which was synthesized from pentaerythrityl tetrabromide and benzyl amine, was studied. The influences of ionic strength, extraction time, pH and temperature were evaluated. The extraction results showed that the ionic strength had no effect on extraction efficiency and that the extraction equilibrium was established in a few minutes. The extraction percentage was independent of pH up ...

  17. Uranium, thorium and rare earth extraction and separation process by processing their chloride aqueous solutions

    International Nuclear Information System (INIS)

    Sabot, J.L.; Leveque, A.

    1983-01-01

    The different steps of the process are the following: uranium and iron extraction by a neutral organic phosphorus compound and thorium and rare earth recovery in an aqueous solution, iron recovery in acid aqueous phase, concentration of the thorium and rare earth aqueous solution followed by thorium extraction with a organic phosphorus compound and rare earth recovery in the aqueous phase, thorium recovery in acid aqueous phase [fr

  18. Small-Angle Neutron Scattering Study of Shear-Induced Phase Separation in Aqueous Poly(N-isopropylacrylamide) Solutions

    NARCIS (Netherlands)

    Stieger, M.A.; Lindner, P.; Richtering, W.

    2004-01-01

    The influence of shear flow on the structure of concentrated aqueous poly(N-isopropylacrylamide) solutions near the lower critical solution temperature was investigated by means of small-angle neutron scattering. Two samples, both in the semi-dilute regime above the overlap concentration, were

  19. 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...

  20. Lactose and sucrose aqueous solutions for high-dose dosimetry with 10-MeV electron beam irradiation

    International Nuclear Information System (INIS)

    Amraei, R.; Kheirkhah, M.; Raisali, G.

    2012-01-01

    In the present study, dosimetric characterisation of aqueous solutions of lactose and sucrose was analysed by UV spectrometry following irradiation using 10-MeV electron beam at doses between 0.5 and 10.5 kGy. As a dosimetric index, absorbance is selected at 256 and 264 nm for lactose and sucrose aqueous solutions, respectively. The intensity of absorbance for irradiated solutions depends on the pre-irradiation concentration of lactose and sucrose. The post-irradiation stability of both solutions was investigated at room temperature for a measurement period of 22 d. (authors)

  1. Adsorption of methylene blue from aqueous solution on zeolitic material for color and toxicity removal

    OpenAIRE

    Denise Alves Fungaro; Lucas Caetano Grosche; Alessandro Pinheiro; Juliana de Carvalho Izidoro; Sueli Ivone Borrely

    2011-01-01

    The adsorption of methylene blue (MB) from aqueous solution was carried out using zeolite. This adsorbent material was synthesized from fly ash as a low-cost adsorbent, allowing fly ash to become a recycled residue. Factors that affected adsorption were evaluated: initial dye concentration, contact time and temperature. The equilibrium of adsorption was modeled by Langmuir, Freundlich and Temkin models. The adsorption obtained data were well described by Temkin, the adsorption isotherm model....

  2. Radiation polymerization and crosslinking of N-isopropylacrylamide in aqueous solution and in solid state

    International Nuclear Information System (INIS)

    Safranj, A.; Yoshida, Masaru; Omichi, Hideki; Nagaoka, Noriyasu; Kubota, Hitoshi; Katakai, Ryoichi.

    1995-01-01

    Poly(N-isopropylacrylamide) hydrogels were synthesized by radiation induced simultaneous polymerization and cross-linking. Aqueous monomer solutions and pure monomer, without crosslinker, were irradiated in nitrogen atmosphere at a 60 Co gamma source. The conversion from monomer to polymer and cross-linked gel was investigated as a function of temperature and monomer concentration. The swelling behavior of the gels showed clear dependence on the synthesis conditions. (author)

  3. Graph Theory and Ion and Molecular Aggregation in Aqueous Solutions.

    Science.gov (United States)

    Choi, Jun-Ho; Lee, Hochan; Choi, Hyung Ran; Cho, Minhaeng

    2018-04-20

    In molecular and cellular biology, dissolved ions and molecules have decisive effects on chemical and biological reactions, conformational stabilities, and functions of small to large biomolecules. Despite major efforts, the current state of understanding of the effects of specific ions, osmolytes, and bioprotecting sugars on the structure and dynamics of water H-bonding networks and proteins is not yet satisfactory. Recently, to gain deeper insight into this subject, we studied various aggregation processes of ions and molecules in high-concentration salt, osmolyte, and sugar solutions with time-resolved vibrational spectroscopy and molecular dynamics simulation methods. It turns out that ions (or solute molecules) have a strong propensity to self-assemble into large and polydisperse aggregates that affect both local and long-range water H-bonding structures. In particular, we have shown that graph-theoretical approaches can be used to elucidate morphological characteristics of large aggregates in various aqueous salt, osmolyte, and sugar solutions. When ion and molecular aggregates in such aqueous solutions are treated as graphs, a variety of graph-theoretical properties, such as graph spectrum, degree distribution, clustering coefficient, minimum path length, and graph entropy, can be directly calculated by considering an ensemble of configurations taken from molecular dynamics trajectories. Here we show percolating behavior exhibited by ion and molecular aggregates upon increase in solute concentration in high solute concentrations and discuss compelling evidence of the isomorphic relation between percolation transitions of ion and molecular aggregates and water H-bonding networks. We anticipate that the combination of graph theory and molecular dynamics simulation methods will be of exceptional use in achieving a deeper understanding of the fundamental physical chemistry of dissolution and in describing the interplay between the self-aggregation of solute

  4. Physical chemistry of the interface between oxide and aqueous solution

    International Nuclear Information System (INIS)

    Jolivet, J.P.

    1997-01-01

    The behavior and properties of small oxide particles in aqueous suspension are dominated by the physico-chemistry of their surface. It is electrostatically charged and strongly solvated. The origin of the surface charge is discussed through the MUSIC model [Hiemstra 1996], allowing to estimate the acid-base behavior of surface oxygen atoms. The stability of aqueous dispersions of particles is analysed following the DLVO model, with a special attention on the hydration layers allowing the peptization of flocs. Different adsorption mechanisms of metal cations are presented in terms of coordination chemistry (outer- and inner-sphere complexes) emphasizing the coordinating ability of the surface towards metal complexes in solution. The anion adsorption is also studied in relation with some interesting consequences on spinel iron oxide nano-particles. (author)

  5. Radiation chemical studies of purine bases in aqueous solutions

    International Nuclear Information System (INIS)

    Infante, H.; Castro, J.W.; Arroyo, I.; Giron, E.; Infante, G.A.

    1984-01-01

    Rate constants of purine bases, such as xanthine and hypoxanthine, with the radiolytic species (e a-bar q and . OH) produced upon the action of ionizing radiation in aqueous solutions were determined using pulse radiolysis. The rate constants obtained were similar to other purine bases. Using radiochromatographic and spectroscopic techniques, destruction yields for these purine bases have been determined in the presence of suitable scavengers. The formation yields of several radiolytic products produced during the radiolysis of these compounds have been determined. Glycol and 7 and 8 hydroxy derivatives of both xanthine and hypoxanthine are the major products in the hydroxyl radical reactions. The dihydropurines and aminopyrimidines derivatives are the major products in the aqueous electron reactions. The results of these investigations are compared with those for other purine and pyrimidine bases. A basic mechanism for the radiolysis of purine bases is postulated and discussed

  6. Experiment and model for the surface tension of amine–ionic liquids aqueous solutions

    International Nuclear Information System (INIS)

    Zhang, Pan; Du, LeiXia; Fu, Dong

    2014-01-01

    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][BF 4 ])–monoethanolamine (MEA), 1-butyl-3-methylimidazolium bromide ([Bmim][Br])–MEA, [Bmim][BF 4 ]–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

  7. Determination of Ga in aqueous uranium solution by EDXRF

    International Nuclear Information System (INIS)

    Natarajan, V.; Purohit, P.J.; Goyal, Neelam; Seshagiri, T.K.; Godbole, S.V.; Manchanda, V.K.

    2009-01-01

    A method has been developed using EDXRF technique for the determination of gallium in aqueous solution using a set of solution standards in the concentration range 20-5000 μg/ml. When this method was applied to U containing solutions, the estimated values were found to be lower due to matrix effects. Hence the method was modified in order to determine gallium in the presence of uranium using lower tube current and another set of standards with U concentration at 100 mg/ml. The method was applicable for the estimation of Ga from 50 μg/ml to 5mg/ml (i.e.0.05-5% Ga in U). Three synthetic samples were analysed by the present methods in order to evaluate the method for its reliability and reproducibility. (author)

  8. 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...... hydrolysis are compared. The effects of temperature, acid concentration, composition of organic phase (for sulfuric acid), and pressure (for nitric acid) on the effectiveness of pretreatment were analyzed. It is shown that the use of organosolv with 0.5% sulfuric acid allows us to increase the reactivity...

  9. Room temperature electrodeposition of actinides from ionic solutions

    Science.gov (United States)

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

    2017-04-25

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

  10. 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.

  11. Preferential adsorption of uranium ions in aqueous solutions by polymers

    International Nuclear Information System (INIS)

    Sakuragi, Masako; Ichimura, Kunihiro; Fujishige, Shoei; Kato, Masao

    1981-01-01

    Amidoxime fiber and triazine fiber were prepared by chemical modification of commercially available polyacrylonitril fiber. It was found that the Amidoxime fiber is efficient to adsorb uranium ions in the artificial sea water. The efficiency of the preferential adsorption decreases by treatment the material with an acid-or an alkaline-solution. The triazine fiber adsorbs uranium ions only in aqueous solutions of such uranyl acetate, in the absence of other ions. In the artificial sea water, it adsorbs other ions instead of uranium. The preferential adsorption of uranium ions was further investigated with a series of polystyrenesulfonamides. Among the polystyrene derivatives, those having carboxyl groups, derived from imino diacetic acid (PSt-Imi), β-alanine (PSt-Ala), glycine (PSt-Gly), and sarcosine (PSt-Sar) were qualified for further discussion. However, it was found that the amount of adsorption of uranium ions by PSt-Imi decreases with increasing the volume of the artificial sea water and/or the duration of the treatment. Taking into account the facts, the preferential adsorption of uranium ions by PSt-Imi in aqueous solution was discussed in detail. (author)

  12. 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.

  13. Lubrication, adsorption, and rheology of aqueous polysaccharide solutions.

    Science.gov (United States)

    Stokes, Jason R; Macakova, Lubica; Chojnicka-Paszun, Agnieszka; de Kruif, Cornelis G; de Jongh, Harmen H J

    2011-04-05

    Aqueous lubrication is currently at the forefront of tribological research due to the desire to learn and potentially mimic how nature lubricates biotribological contacts. We focus here on understanding the lubrication properties of naturally occurring polysaccharides in aqueous solution using a combination of tribology, adsorption, and rheology. The polysaccharides include pectin, xanthan gum, gellan, and locus bean gum that are all widely used in food and nonfood applications. They form rheologically complex fluids in aqueous solution that are both shear thinning and elastic, and their normal stress differences at high shear rates are found to be characteristic of semiflexible/rigid molecules. Lubrication is studied using a ball-on-disk tribometer with hydrophobic elastomer surfaces, mimicking biotribological contacts, and the friction coefficient is measured as a function of speed across the boundary, mixed, and hydrodynamic lubrication regimes. The hydrodynamic regime, where the friction coefficient increases with increasing lubricant entrainment speed, is found to depend on the viscosity of the polysaccharide solutions at shear rates of around 10(4) s(-1). The boundary regime, which occurs at the lowest entrainment speeds, depends on the adsorption of polymer to the substrate. In this regime, the friction coefficient for a rough substrate (400 nm rms roughness) is dependent on the dry mass of polymer adsorbed to the surface (obtained from surface plasmon resonance), while for a smooth substrate (10 nm rms roughness) the friction coefficient is strongly dependent on the hydrated wet mass of adsorbed polymer (obtained from quartz crystal microbalance, QCM-D). The mixed regime is dependent on both the adsorbed film properties and lubricant's viscosity at high shear rates. In addition, the entrainment speed where the friction coefficient is a minimum, which corresponds to the transition between the hydrodynamic and mixed regime, correlates linearly with the ratio

  14. 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.

  15. 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

  16. Thermochemical study of aqueous solutions of lithium diclofenac at 293.15-318.15 K

    Science.gov (United States)

    Manin, N. G.; Perlovich, G. L.; Fini, A.

    2013-04-01

    The enthalpies of solution and dilution of aqueous solutions of lithium diclofenac (LiDC) are measured in the concentration range of 0.002-0.047 m at 293.15, 298.15, 308.15, and 318.5 K using an isoperibolic calorimeter. The heat capacity of solid LiDC in the temperature range of 273.15-373.15 K is determined using a DSC 204 F1 Phoenix differential scanning calorimeter (NETZSCH, Germany). The virial coefficients of the enthalpy characteristics of a water-LiDC solution are derived in terms of the Pitzer model to calculate a wide range of thermodynamic properties of both the solution and its components. Changes in these characteristics as a function of concentration and temperature are discussed.

  17. On extraction of ruthenium chelate compounds from diluted aqueous solutions

    International Nuclear Information System (INIS)

    Brukhertzajfer, Kh.; Kokh, Kh.

    1975-01-01

    Ruthenium(84) extraction from diluted aqueous solutions has been investigated with the use of the di-n-buthyl phosphoric and di-2-ethyl-hexyl phosphoric acids, acetyl acetone and tenoyl-tri-fluoroacetone taken as extraction agents and benzene, toluene and chloroform as solvents. The data on kinetics of the ruthenium(4) complexes formation are given. The results of the experiments point out the possibility of the quantitative ruthenium complexes separation. Ruthenium compound extractivity can be influenced by means of selecting the solvent, the type and concentration of the extraction agents

  18. Photoluminescence of hydrophilic silicon nanocrystals in aqueous solutions

    International Nuclear Information System (INIS)

    Prtljaga, Nikola; D'Amato, Elvira; Pitanti, Alessandro; Guider, Romain; Froner, Elena; Larcheri, Silvia; Scarpa, Marina; Pavesi, Lorenzo

    2011-01-01

    Stable aqueous solutions of undecylenic-acid-grafted silicon nanocrystals (Si-nc) were prepared. The time evolution of the photoluminescence properties of these hydrophilic silicon nanocrystals has been followed on different timescales (hours and days). On a short timescale (hours), Si-nc tend to agglomerate while the PL lineshape and intensity are stable. Agglomeration can be reduced by using suitable surfactants. On a long timescale (days), oxidation of Si-nc occurs even in the presence of surfactants. These two observations render Si-nc very useful as a labeling agent for biosensing.

  19. Photoluminescence of hydrophilic silicon nanocrystals in aqueous solutions

    Science.gov (United States)

    Prtljaga, Nikola; D'Amato, Elvira; Pitanti, Alessandro; Guider, Romain; Froner, Elena; Larcheri, Silvia; Scarpa, Marina; Pavesi, Lorenzo

    2011-05-01

    Stable aqueous solutions of undecylenic-acid-grafted silicon nanocrystals (Si-nc) were prepared. The time evolution of the photoluminescence properties of these hydrophilic silicon nanocrystals has been followed on different timescales (hours and days). On a short timescale (hours), Si-nc tend to agglomerate while the PL lineshape and intensity are stable. Agglomeration can be reduced by using suitable surfactants. On a long timescale (days), oxidation of Si-nc occurs even in the presence of surfactants. These two observations render Si-nc very useful as a labeling agent for biosensing.

  20. Photoluminescence of hydrophilic silicon nanocrystals in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Prtljaga, Nikola; D' Amato, Elvira; Pitanti, Alessandro; Guider, Romain; Froner, Elena; Larcheri, Silvia; Scarpa, Marina; Pavesi, Lorenzo, E-mail: nikolap@science.unitn.it [Department of Physics, University of Trento, Via Sommarive 14, I-38123 Trento (Italy)

    2011-05-27

    Stable aqueous solutions of undecylenic-acid-grafted silicon nanocrystals (Si-nc) were prepared. The time evolution of the photoluminescence properties of these hydrophilic silicon nanocrystals has been followed on different timescales (hours and days). On a short timescale (hours), Si-nc tend to agglomerate while the PL lineshape and intensity are stable. Agglomeration can be reduced by using suitable surfactants. On a long timescale (days), oxidation of Si-nc occurs even in the presence of surfactants. These two observations render Si-nc very useful as a labeling agent for biosensing.

  1. Structural aspects of magnetic fluid stabilization in aqueous agarose solutions

    Science.gov (United States)

    Nagornyi, A. V.; Petrenko, V. I.; Avdeev, M. V.; Yelenich, O. V.; Solopan, S. O.; Belous, A. G.; Gruzinov, A. Yu.; Ivankov, O. I.; Bulavin, L. A.

    2017-06-01

    Structure characterization of magnetic fluids (MFs) synthesized by three different methods in aqueous solutions of agarose was done by means of small-angle neutron (SANS) and synchrotron X-ray scattering (SAXS). The differences in the complex aggregation observed in the studied magnetic fluids were related to different stabilizing procedures of the three kinds of MFs. The results of the analysis of the scattering (mean size of single polydisperse magnetic particles, fractal dimensions of the aggregates) are consistent with the data of transmission electron microscopy (TEM).

  2. Volumetric and calorimetric properties of aqueous ionene solutions.

    Science.gov (United States)

    Lukšič, Miha; Hribar-Lee, Barbara

    2017-02-01

    The volumetric (partial and apparent molar volumes) and calorimetric properties (apparent heat capacities) of aqueous cationic polyelectrolyte solutions - ionenes - were studied using the oscillating tube densitometer and differential scanning calorimeter. The polyion's charge density and the counterion properties were considered as variables. The special attention was put to evaluate the contribution of electrostatic and hydrophobic effects to the properties studied. The contribution of the CH 2 group of the polyion's backbone to molar volumes and heat capacities was estimated. Synergistic effect between polyion and counterions was found.

  3. Electrochemical reduction of /Ru edta L/ compounds in aqueous solution

    International Nuclear Information System (INIS)

    Fernandes, J.R.; Santos, A.A.; Oliveira, L.A.A.; Benedetti, A.V.

    1988-01-01

    Electrochemical reduction of the complexes [Ru edta L], [L= 2,2' bipyridine (2,2' bipy) pyrazinamide (pz CONH 2 ); 4-cyanopyridine 4-cyanopyridine (4-CNpy); nicotinamide (NIC); hydroxil; 3-aminophenol (3-NH 2 φ OH) and 2-aminopyridine (2-NH 2 py)] in aqueous solution (acetate buffer, pH 4.65 or phosphate buffer, pH=8.2), μ=0,2 M p-cH 3 φSO 3 Li is investigated. The measurements have been made by cyclic voltammetry technique, using platinum, gold and mercury pool as working electrodes. (M.J.C.) [pt

  4. Simultaneous Extraction, Enrichment and Removal of Dyes from Aqueous Solutions Using a Magnetic Aqueous Micellar Two-Phase System

    Directory of Open Access Journals (Sweden)

    Shuanggen Wu

    2017-12-01

    Full Text Available The magnetic aqueous micellar two-phase system (MAMTPS has the advantages combined of magnetic solid phase extraction (MSPE and aqueous micellar two-phase system (AMTPS. Thus, MAMTPS based on Fe3O4 magnetic nanoparticles (MNPs and a nonionic surfactant Triton X-114 (TX-114 was developed for the extraction, enrichment and removal of three dyes (Congo red, methyl blue, and methyl violet from aqueous solutions in this study. The MNPs Fe3O4@NH2 was screened as the optimal MNPs benefiting the extraction. Then, the influencing factors of MNPs amount, TX-114 concentration, vibration time, and extraction temperature were investigated in detail. The results showed that the extraction efficiencies of three dyes almost reached 100% using MAMTPS under the optimal conditions; MAMTPS had higher extraction ability than the individual MSPE or AMTPS. Thus, MAMTPS had the advantages of simple operation, high extraction ability, easy recycling of MNPs, and short phase-separation time, which showspotential for use in the extraction and analysis of contaminants from water samples.

  5. Viscosimetry and IR spectroscopy studies of the structure of water in aqueous KBr solutions

    Science.gov (United States)

    Masimov, E. A.; Pashayev, B. G.; Hasanov, H. Sh.; Hasanov, N. H.

    2015-07-01

    The structure of aqueous solutions of KBr was studied by viscosimetry and IR spectroscopy at temperatures of 283.15-333.15 K and concentrations of 0.01-0.07 mole fractions. The results of our experiments were used for calculating the activation parameters of viscous flow, the partial molar volume of KBr in solution, and the energies and lengths of hydrogen bonds between water molecules; the concentration dependences of these parameters were analyzed. The results indicate that KBr desrtroys the structure of water.

  6. Changes in the color, chemical stability and antioxidant capacity of thermally treated anthocyanin aqueous solution over storage.

    Science.gov (United States)

    Sui, Xiaonan; Bary, Solène; Zhou, Weibiao

    2016-02-01

    Many anthocyanin-containing foods are thermally processed to ensure their safety, and stored for some time before being consumed. However, the combination of thermal processing and subsequent storage has a significant impact on anthocyanins. This study aimed to investigate the color, chemical stability, and antioxidant capacity of thermally treated anthocyanin aqueous solutions during storage at 4, 25, 45, and 65 °C, respectively. Anthocyanin aqueous solutions were thermally treated before storage. Results showed that the degradation rate of anthocyanins in aqueous solutions was much faster than those in real food. The color of the anthocyanin aqueous solutions changed dramatically during storage. The anthocyanin aqueous solutions stored at 4 °C showed the best chemical stability. Interestingly, the antioxidant capacity of the anthocyanin aqueous solutions stored at lower temperatures remained the same; however, the antioxidant capacity of those thermally treated at 120 or 140 °C and stored at 45 or 65 °C significantly decreased. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Molecular-dynamics simulations of urea nucleation from aqueous solution

    Science.gov (United States)

    Salvalaglio, Matteo; Perego, Claudio; Giberti, Federico; Mazzotti, Marco; Parrinello, Michele

    2015-01-01

    Despite its ubiquitous character and relevance in many branches of science and engineering, nucleation from solution remains elusive. In this framework, molecular simulations represent a powerful tool to provide insight into nucleation at the molecular scale. In this work, we combine theory and molecular simulations to describe urea nucleation from aqueous solution. Taking advantage of well-tempered metadynamics, we compute the free-energy change associated to the phase transition. We find that such a free-energy profile is characterized by significant finite-size effects that can, however, be accounted for. The description of the nucleation process emerging from our analysis differs from classical nucleation theory. Nucleation of crystal-like clusters is in fact preceded by large concentration fluctuations, indicating a predominant two-step process, whereby embryonic crystal nuclei emerge from dense, disordered urea clusters. Furthermore, in the early stages of nucleation, two different polymorphs are seen to compete. PMID:25492932

  8. Removal of thiobencarb in aqueous solution by zero valent iron.

    Science.gov (United States)

    Nurul Amin, Md; Kaneco, Satoshi; Kato, Tetsuya; Katsumata, Hideyuki; Suzuki, Tohru; Ohta, Kiyohisa

    2008-01-01

    A cost-effective method with zero valent iron (ZVI) powder was developed for the purification of thiobencarb (TB)-contaminated water. The removal treatment was performed in the batch system. A sample solution of 10 ml containing 10 microg ml(-1) of TB could be almost completely treated by 100mg of ZVI at 25 degrees C for 12h of treatment time. Since the formation of chloride ion in the aqueous solution during the treatment of TB was observed, the removal of TB with ZVI may contain two processes: reduction (degradation) and adsorption. Because the present treatment for TB is simple, easy handling and cheap, the developed technology with ZVI can contribute to the treatment of agricultural wastewaters.

  9. The radiation chemistry of aqueous sodium terephthalate solutions

    International Nuclear Information System (INIS)

    Matthews, R.W.

    1980-04-01

    The radiation chemistry of cobalt-60 gamma-irradiated aqueous sodium terephthalate solutions has been studied. In aerated 4 x 10 -4 M 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 -4 M and 1 x 10 -2 M 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 + TA 2- ) : k(OH + CO 3 2- ) : k(OH + HCO 3 - ) = 1 : 0.105 : 0.0036

  10. 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.

  11. 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.

  12. Chemical activation of tea waste and use for the removal of chromium (Vi) from aqueous solution

    International Nuclear Information System (INIS)

    Qureshi, K.; Bhatti, I.; Ansari, A.K.

    2009-01-01

    Tea waste is the residue left after the preparation of tea. At present the tea waste is regarded as a waste product having no use. In this study, tea waste is converted into an adsorbent. Tea waste is chemically activated with phosphoric acid at low temperature 450 degree C. This activated carbon is then utilized as an adsorbent for the removal of Chromium (VI) from aqueous solution. The various sorption parameters i.e pH, sorbent dose sorbate concentration, shaking time and shaking speed are first optimized. 75% of chromium from aqueous solution is effectively removed at pH 2. The best optimum conditions were obtained when 1 gm of sorbent was agitated at 100 rpm with 60 mg/l of sorbate for 50 minutes. Better results were obtained when low concentrations of sorbates were used. Hence tea waste could also be successfully used for the sorption of Chromium (VI), from industrial waste water. (author)

  13. Synthesis of carboxymethyl chitin in aqueous solution and its thermo- and pH-sensitive behaviors.

    Science.gov (United States)

    Liu, Hui; Yang, Qizhi; Zhang, Lina; Zhuo, Renxi; Jiang, Xulin

    2016-02-10

    Homogenous modification of natural chitin offers the advantage of fair structure control. In this work, novel carboxymethyl chitins (CMCHs) with broad range of degree of substitution (DS: 0.035 to 0.74), high degree of acetylation (DA) and little de-polymerization were synthesized homogeneously in aqueous NaOH/urea solution. The simultaneous determination of DA, DS and carboxymethylation fraction at C3 and C6 for these CMCHs was achieved by proton NMR in acidic deuterated aqueous solution for the first time. Due to the good homogeneity, the prepared CMCH-4 with lower DS of carboxymethylation exhibited, for the first time to our knowledge, dual thermo- and pH-sensitive properties. The nontoxic thermo-sensitive polymer systems gel at body temperature (37 °C) in physiological condition, which is very useful as injectable hydrogels for drug delivery and tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Removal of lead from aqueous solution using waste tire rubber ash as an adsorbent

    Directory of Open Access Journals (Sweden)

    H. Z. Mousavi

    2010-03-01

    Full Text Available The purpose of this study was to investigate the possibility of the utilization of waste tire rubber ash (WTRA as a low cost adsorbent for removal of lead (II ion from aqueous solution. The effect of different parameters (such as contact time, sorbate concentration, adsorbent dosage, pH of the medium and temperature were investigated. The sorption process was relatively fast and equilibrium was reached after about 90 min of contact. The experimental data were analyzed by the Freundlich isotherm and the Langmuir isotherm. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 22.35 mg/g. The adsorption kinetics was investigated and the best fit was achieved by a first-order equation. The results of the removal process show that the Pb (II ion adsorption on WTRA is an endothermic and spontaneous process. The procedure developed was successfully applied for the removal of lead ions in aqueous solutions.

  15. Complex formation in aqueous trimethylamine-N-oxide (TMAO) solutions.

    Science.gov (United States)

    Hunger, Johannes; Tielrooij, Klaas-Jan; Buchner, Richard; Bonn, Mischa; Bakker, Huib J

    2012-04-26

    We study aqueous solutions of the amphiphilic osmolyte trimethylamine-N-oxide (TMAO) using broadband dielectric spectroscopy and femtosecond mid-infrared spectroscopy. Both experiments provide strong evidence for distinctively slower rotation dynamics for water molecules interacting with the hydrophobic part of the TMAO molecules. Further, water is found to interact more strongly at the hydrophilic site of the TMAO molecules: we find evidence for the formation of stable, TMAO·2H2O and/or TMAO·3H2O complexes. While this coordination structure seems obvious, the lifetime of these complexes is found to be extraordinarily long (>50 ps). The existence of these long-lived complexes leads to pronounced parallel dipole correlations between water and TMAO, reflected in enhanced amplitudes in the dielectric spectra. The strong interaction between water and TMAO also results in a red-shifted band for the O-D stretching vibration of HDO molecules in an isotopically diluted aqueous TMAO solution. This O-D stretching vibration has a vibrational lifetime of 670 fs, which is significantly shorter than the lifetime of the O-D stretch vibration of bulk-like HDO molecules, presumably due to efficient coupling to vibrational modes of TMAO. The rotational dynamics of these O-D groups are slowed down dramatically, and are limited by the rotation of the whole complex, while the O-D vector oriented away from TMAO probably shows an accelerated reorientation.

  16. Adsorption of Chromium from Aqueous Solution Using Polyaniline

    Directory of Open Access Journals (Sweden)

    Majid Riahi Samani

    2011-10-01

    Full Text Available New group of polymers have been synthesized that are conductive of electricity so they are called conducting polymers. One of the most conducting polymers is "polyaniline". In the present study, polyaniline was synthesized by oxidizing aniline monomer under strongly acidic conditions using potassium iodate as an initiator of oxidative polymerization. Synthesized polyaniline as a powder used as an adsorbent to remove chromium from aqueous solution. Experiments were conducted in batch mode with variables such as amount of polyaniline, chromium solution pH and adsorbtion isotherms. Due to presence of Cr (III in solution after using polyaniline, removal mechanism is the combination of surface adsorption and reduction. It seems that polyaniline reduces the Cr(VI to Cr(III and adsorbs the Cr(III and a part of remaining  Cr(VI. It is well known that nitrogen atom in compounds of amine derivative makes co-ordinate bond with positive charge of metals due to the presence of electron in sp3 orbital of nitrogen. The majority of total chromium removal  occurred at 30minute for polyaniline  and the optimum  time for  hexavalent chromium  removal was about 5 min. Polyaniline has the maximum total cheomiume removal at pH, 3-9. The maximum hexavalent chromium removal occurred at acidic pH for polyanilines. The equilibrium adsorption data for polyaniline fitted both Freundlich’s and Langmuir’s isotherms. This research shows that polyaniline can be used as an adsorbent  for removal chromium from aqueous solution.

  17. Bioremediation of zirconium from aqueous solution by coriolus versicolor: process optimization

    International Nuclear Information System (INIS)

    Amin, M.; Bhatti, H. N.; Sadaf, S.

    2013-01-01

    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)

  18. Pitting Corrosion Behavior of 304 SS and 316 SS Alloys in Aqueous Chloride and Bromide Solutions

    Directory of Open Access Journals (Sweden)

    Ibtehal Kareem Shakir

    2018-01-01

    Full Text Available The importance of the present work falls on the pitting corrosion behavior investigation of 304 SS and 316 SS alloys in 3.5 wt% of aqueous solution bearing with chloride and bromide anion at different solutions temperature range starting from (20-50oC due to the pitting corrosion tremendous effect on the economic, safety and materials loss due to leakage. The impact of solution temperatures on the pitting corrosion resistance at 3.5wt% (NaCl and NaBr solutions for the 304 SS and 316 SS has been investigated utilizing the cyclic polarization techniques at the potential range -400 to1000 mV vs. SCE at 40 mV/sec scan rate followed by the surface characterization employing Scanning Electron Microscope. The results show that a significant decline in the pitting corrosion potential Ep values of both stainless steel alloys in chloride and bromide solution during temperature increase attributed to the pitting corrosion potential decreased arises from the modification of the passive film properties. The surface examination using optical microscope and scanning electron microscope prove the occurring of higher pitting density over 304 SS in chloride solution than that observed in bromide solution with a non-circular lacy cover pitfall out at the center and falls inside the pits hall in comparison to the isolated circular lacy cover pit formed on 316 SS in 3.5wt% NaBr solution at 50 oC.

  19. The Use of Alum Mixtures for Removal and Decontamination of VX and QL In Aqueous Solutions

    National Research Council Canada - National Science Library

    Williams, Daniel J; Bevilacqua, Vicky L; Creasy, William R; McGarvey, David J; Rice, Jeffrey S; DeLeon, Christopher L; Sanders, Melanie J; Durst, H. D

    2004-01-01

    ...), were treated with aqueous aluminum sulfate (alum), sodium aluminate, or mixtures of the two. The mixtures were prepared by combining varying volumes of the aqueous salts to give buffered solutions (pH 2-12...

  20. Determining the saturation vapour pressures of keto-dicarboxylic acids in aqueous solutions

    Science.gov (United States)

    Crljenica, Ivica; Yli-Juuti, Taina; Zardini, Alessandro A.; Julin, Jan; Bilde, Merete; Riipinen, Ilona

    2013-05-01

    A two-compartment binary mass transport model with group contribution methods parametrizations for the physical properties of the organic acids (UNIFAC Dortmund method for activity coefficients, GCVOL-OL-60 method for the pure liquid acid density, GC-MG method for the pure acid surface tension at room temperature, Fuller et al. method for the diffusion coefficients) was used to interpret the evaporation experiments of 100 nm sized ketodicarboxylic acid aqueous solutions droplets at ambient temperature. The determined values for the saturation vapour pressure of liquid 2-keto-glutaric acid are in the order of 10-5 Pa.

  1. Sorption behaviour of uranium and thorium on cryptomelane-type hydrous manganese dioxide from aqueous solution

    International Nuclear Information System (INIS)

    El-Naggar, I.M.; El-Absy, M.A.; Abdel-Hamid, M.M.; Aly, H.F.

    1993-01-01

    The kinetics of sorption of uranium and thorium from aqueous nitrate solutions on cryptomelane-type hydrous manganese dioxide (CRYMO) was studied. The exchange of uranium is particle diffusion controlled while that of thorium is chemical reaction at the exchange sites. Sorption of uranium and thorium by CRYMO has been also studied as a function of metal concentrations and temperature. The sorption of both cations is found to be an endothermic process and increases markedly with temperature between 30 and 60 degree C. The sorption results have been analysed by the langmuir adsorption isotherm over the entire range of uranium and thorium concentrations investigated. 35 refs., 8 figs., 5 tabs

  2. 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.

  3. Quenching characteristics of bathocuproinedisulfonic acid, disodium salt in aqueous solution and copper sulfate plating solution

    Science.gov (United States)

    Koga, Toshiaki; Hirakawa, Chieko; Takeshita, Michinori; Terasaki, Nao

    2018-04-01

    Bathocuproinedisulfonic acid, disodium salt (BCS) is generally used to detect Cu(I) through a color reaction. We newly found BCS fluorescence in the visible blue region in an aqueous solution. However, the fluorescence mechanism of BCS is not well known, so we should investigate its fundamental information. We confirmed that the characteristics of fluorescence are highly dependent on the molecular concentration and solvent properties. In particular, owing to the presence of the copper compound, the fluorescence intensity extremely decreases. By fluorescence quenching, we observed that a copper compound concentration of 10-6 mol/L or less could easily be measured in an aqueous solution. We also observed BCS fluorescence in copper sulfate plating solution and the possibility of detecting monovalent copper by fluorescence reabsorption.

  4. Corrosion control of vanadium in aqueous solutions by amino acids

    International Nuclear Information System (INIS)

    El-Rabiee, M.M.; Helal, N.H.; El-Hafez, Gh.M. Abd; Badawy, W.A.

    2008-01-01

    The electrochemical behavior of vanadium in amino acid free and amino acid containing aqueous solutions of different pH was studied using open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS). The corrosion current density, i corr , the corrosion potential, E corr and the corrosion resistance, R corr , were calculated. A group of amino acids, namely, glycine, alanine, valine, histidine, glutamic and cysteine has been investigated as environmentally safe inhibitors. The effect of Cl - on the corrosion inhibition efficiency especially in acid solutions was investigated. In neutral and basic solutions, the presence of amino acids increases the corrosion resistance of the metal. The electrochemical behavior of V before and after the corrosion inhibition process has shown that some amino acids like glutamic acid and histidine have promising corrosion inhibition efficiency at low concentration (≅25 mM). The inhibition efficiency (η) was found to depend on the structure of the amino acid and the constituents of the corrosive medium. The corrosion inhibition process is based on the adsorption of the amino acid molecules on the metal surface and the adsorption process follows the Freundlich isotherm. The adsorption free energy for valine on V in acidic solutions was found to be -9.4 kJ/mol which reveals strong physical adsorption of the amino acid molecules on the vanadium surface

  5. On the state of phosphomolybdenovanadic heteropolyblue in aqueous solutions

    International Nuclear Information System (INIS)

    Kuznetsova, L.I.; Yurchenko, Eh.N.; Maksimovskaya, R.I.; Kirik, N.P.; Matveev, K.I.

    1977-01-01

    The effect has been investigated of pH solution on the state of the phosphomolybdenovanadic heteropolyblues of the 12. series, containing n=1,2,3,6 atoms of vanadium (6). It has been shown that the free VO 2+ intrusion into the sphere of heteropolyanions takes place alongside with pH increasing from 1 to 3. At the some time the rate of oxidation of the heteropolyblue solutions by oxygen and the optical density of solutions increase too. The dissociation constants of the heteropolyblue molecule in acid medium increase with increasing of the quantity of vanadium atoms. It has been shown that stability of heteropolyblue in relation to molybdenum decreases with increasing of its quantity in the heteropolyblue molecule. Using precipitation of the heteropolyanions by the cation of tetraethyl ammonium, it has been shown that heteropolyanions can consist of 1,2,3 and 6 atoms of V(6). The state of heteropolyblues in an aqueous solution is characterized by electron absorption spectra

  6. The movement of solutes through aqueous fissures in porous rock

    International Nuclear Information System (INIS)

    Glueckauf, E.

    1980-06-01

    A mathematical treatment has been given for the movement of materials dissolved in water flowing through narrow fissures of a micro-porous substrate. As there is no water flow in these micro-pores, equilibrium between the aqueous solution and the micro-porous substrate proceeds only by diffusion, with the result that there arises a gross disequilibrium. Two major effects arise: first, the hold-up in the substrate - even when there is no adsorption taking place - is orders of magnitude larger than on non-porous substrate, and increases even further, if adsorption takes place. Secondly, dispersion caused by non-equilibrium is also orders of magnitude greater than dispersion arising from convection effects of the water flow in interconnecting fissures. As a result, the solutes arrive very much later at the end of the underground fissures, and in concentrations which are very much lower than have been calculated in previous modelling experiments. The significance of these effects is discussed in detail, and this can be helpful in the selection of sites for underground disposal of radioactive waste. It is now quite feasible to specify sites with conditions, where even solutes with minimal adsorption would not return to the surface within a million years, and where solutes of moderately strong adsorption would be effectively immobile. (author)

  7. Pulse Radiolysis of Aqueous Solutions of Aniline and Substituted Anilines

    International Nuclear Information System (INIS)

    Christensen, H.C.

    1971-01-01

    The primary reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals with aniline and the aniline cation in aqueous solutions have been studied by the technique of pulse radiolysis and by determination of end products after y-radiolysis. Hydrogen atoms and hydrated electrons react with aniline under formation of the cyclohexadienyl type radical with absorption maximum at 355 nm and an extinction coefficient of 4100/M/cm. A similar radical formed by reaction of hydrogen atoms with the aniline cation has its absorption maximum at 31 0 nm and an extinction coefficient of 3200/M/cm. Hydrogen atoms react with the acid and neutral forms of aniline with rate constants of (1.3 ± 0.2 ) x 10 9 /M/s and (2.9 ± 0.7) x 10 9 /M/s, respectively. OH radicals react with aniline with a rate constant of (1.4 ± 0.3) x 10 10 /M/s under formation of the cyclohexadienyl radical with absorption maximum at 355 nm and the anilino radical with absorption maxima at 300 and 400 nm. The cyclohexadienyl radical decayed in a first order process with a rate constant of 1.4 x 10 5 /s by elimination of NH 3 , whereas the anilino radical disappeared in a second order reaction under formation of hydrazobenzene. O - radicals react with aniline at pH 13.3 with a rate constant of (3.1 ± 0.6) x 10 9 under formation of anilino radicals. The reaction of OH radicals with the aniline cation produced the anilino radical cation with a rate constant of (4.8 ± 0.8) x 10 9 . The absorption maximum was placed at 415 nm, The cyclohexadienyl type radical with absorption maximum at 350 nm was also found in aqueous solutions of 2-amino-1,3-dimethylbenzene but was not formed in solutions of N,N' -dimethylaniline

  8. Quasi-steady model for predicting temperature of aqueous foams circulating in geothermal wellbores

    Energy Technology Data Exchange (ETDEWEB)

    Blackwell, B.F.; Ortega, A.

    1983-01-01

    A quasi-steady model has been developed for predicting the temperature profiles of aqueous foams circulating in geothermal wellbores. The model assumes steady one-dimensional incompressible flow in the wellbore; heat transfer by conduction from the geologic formation to the foam is one-dimensional radially and time-dependent. The vertical temperature distribution in the undisturbed geologic formation is assumed to be composed of two linear segments. For constant values of the convective heat-transfer coefficient, a closed-form analytical solution is obtained. It is demonstrated that the Prandtl number of aqueous foams is large (1000 to 5000); hence, a fully developed temperature profile may not exist for representative drilling applications. Existing convective heat-transfer-coefficient solutions are adapted to aqueous foams. The simplified quasi-steady model is successfully compared with a more-sophisticated finite-difference computer code. Sample temperature-profile calculations are presented for representative values of the primary parameters. For a 5000-ft wellbore with a bottom hole temperature of 375{sup 0}F, the maximum foam temperature can be as high as 300{sup 0}F.

  9. Photocatalytic degradation of indigo carmine in aqueous solution by TiO2-coated non-woven fibres.

    Science.gov (United States)

    Barka, N; Assabbane, A; Nounah, A; Ichou, Y Aît

    2008-04-15

    The photocatalytic degradation of indigo carmine has been investigated in aqueous solutions using TiO2 coated non-woven fibres as photocatalyst. The experiments were carried out to investigate the factors influencing the photocatalytic degradation, such as the previous adsorption in the dark, initial concentration of dye solution, temperature, and pH. The experimental results show that adsorption is an important parameter controlling the apparent kinetic constant of the degradation. The photocatalytic degradation rate was favoured by a high concentration of solution in respect to Langmuir-Hinshelwood model. The degradation rate was pH and temperature dependent with a high degradation rate at high temperature.

  10. Iron(III) citrate speciation in aqueous solution.

    Science.gov (United States)

    Silva, Andre M N; Kong, XiaoLe; Parkin, Mark C; Cammack, Richard; Hider, Robert C

    2009-10-28

    Citrate is an iron chelator and it has been shown to be the major iron ligand in the xylem sap of plants. Furthermore, citrate has been demonstrated to be an important ligand for the non-transferrin bound iron (NTBI) pool occurring in the plasma of individuals suffering from iron-overload. However, ferric citrate chemistry is complicated and a definitive description of its aqueous speciation at neutral pH remains elusive. X-Ray crystallography data indicates that the alcohol function of citrate (Cit4-) is involved in Fe(III) coordination and that deprotonation of this functional group occurs upon complex formation. The inability to include this deprotonation in the affinity constant calculations has been a major source of divergence between various reports of iron(III)-citrate affinity constants. However the recent determination of the alcoholic pKa of citric acid (H4Cit) renders the reassessment of the ferric citrate system possible. The aqueous speciation of ferric citrate has been investigated by mass spectrometry and EPR spectroscopy. It was observed that the most relevant species are a monoiron dicitrate species and dinuclear and trinuclear oligomeric complexes, the relative concentration of which depends on the solution pH value and the iron : citric acid molar ratio. Spectrophotometric titration was utilized for affinity constant determination and the formation constant for the biologically relevant [Fe(Cit)2]5- is reported for the first time.

  11. Kinetics of CO2 Absorption into Aqueous Basic Amino Acid Salt: Potassium Salt of Lysine Solution.

    Science.gov (United States)

    Shen, Shufeng; Yang, Ya-nan; Bian, Yangyang; Zhao, Yue

    2016-02-16

    Aqueous amino acid salts are considered as an attractive alternative to alkanolamine solvents (e.g., MEA) for carbon dioxide (CO2) absorption. The kinetics of CO2 into unloaded aqueous solutions of potassium lysinate (LysK) was studied using a wetted wall column at concentrations ranging from 0.25 to 2.0 M and temperatures from 298 to 333 K. Physicochemical properties of aqueous LysK solutions such as density, viscosity, and physical solubility of CO2 were measured to evaluate the reaction rate constants. The reaction pathway is described using zwitterion mechanism taking into account the effect of ionic strength on the reaction rate. Under the fast pseudo-first-order regime, the reaction rate parameters were obtained and correlated in a power-law reaction rate expression. LysK shows higher chemical reactivity toward CO2 than the industrial standard MEA and most of amino acid salts. Its reaction rate constants increase considerably with concentration and temperature. The reaction order is found to be an average value of 1.58 with respect to LysK. The forward second-order kinetic rate constant, k2 0 , are obtained as 31615 and 84822 m3 kmol−1 s−1 at 298 and 313 K, respectively with activation energy of 51.0 kJ mol−1. The contribution of water to the zwitterion deprotonation seems to be more significant than that of LysK for the above-mentioned kinetic conditions

  12. Hg(II) removal from aqueous solutions by bacillus subtilis biomass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue Song; Li, Fei Yan; He, Wen; Miao, Hua Hua [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang (China)

    2010-01-15

    The biosorption of Hg(II) from aqueous solutions using Bacillus subtilis biomass was investigated in this study. The adsorbent was characterized by FTIR. Various factors including solution pH, initial concentration of Hg(II), contact time, reaction temperature and ionic strength were taken into account and promising results were obtained. An initial solution pH of 5.0 was most favorable for Hg(II) removal. The kinetic data was also analyzed using pseudo first order and pseudo second order equations. The results suggested that Hg(II) bioadsorption was best represented by the pseudo second order equation. Freundlich, Langmuir and Langmuir-Freundlich isotherms for the present systems were analyzed. The most satisfactory interpretation for the equilibrium data at different temperatures was given by the Langmuir-Freundlich isotherm. The effect of ionic strength on bioadsorption was significant. Bacillus subtilis biomass could serve as low cost adsorbent to remove Hg(II) from aqueous solutions, especially at lower concentrations of Hg(II) (<20 mg Hg/L). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  13. Magnetic composite nanofibers fabricated by electrospinning of Fe3O4/gelatin aqueous solutions

    International Nuclear Information System (INIS)

    Wang, Shuhong; Sun, Zhiyao; Yan, Eryun; Yuan, Jihong; Gao, Yang; Bai, Yuhao; Chen, Yu; Wang, Cheng; Zheng, Yongjie; Jing, Tao

    2014-01-01

    Graphical abstract: Superparamagnetic Fe 3 O 4 /GE composite nanofibers with saturation magnetization of 12.87 emμ g −1 were prepared from gelatin aqueous solution at an elevated temperature by electrospinning. - Highlights: • Electrospinning GE aqueous solution at higher temperature. • Presenting a simple and effective technique, combining wet blending with high temperature electrospinning to prepare magnetic composite nanofibers. • Developing composite nanofibers with higher superparamagnetic properties is expected to be useful in application for the biomedical field. - Abstract: We have fabricated magnetic composite nanofibers containing superparamagnetic Fe 3 O 4 nanoparticles by the electrospinning method. Highly dispersed Fe 3 O 4 magnetic nanoparticles were synthesized by one-step co-precipitation of Fe 2+ /Fe 3+ under an alkaline condition with 4 wt% poly(vinyl alcohol) (PVA) aqueous solution as the stabilizer. Gelatin (GE) was used as a polymeric matrix for fabricating the nanocomposites. The prepared Fe 3 O 4 /GE composite nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. These composite nanofibers show uniform and continuous morphology with the Fe 3 O 4 nanoparticles embedded in the nanofibers. By studying the magnetic properties of the Fe 3 O 4 /GE composite nanofibers, we confirm that the composite nanofibers possess superparamagnetic properties with a high saturated magnetization (M s = 12.87 emμ g −1 ) at room temperature. The features of this approach for getting one-dimensional magnetic nanostructure are its simplicity, effectiveness and safety. The Fe 3 O 4 /GE nanofibers with superparamagnetic properties would be potentially applied in biomedical field

  14. Preformulation study of methazolamide for topical ophthalmic delivery: physicochemical properties and degradation kinetics in aqueous solutions.

    Science.gov (United States)

    Jiang, Sunmin; Wang, Fengzhen; Zhu, Shuning; Zhang, Xiumei; Guo, Zhigang; Li, Rui; Xu, Qunwei

    2013-05-20

    Methazolamide (MTZ) is an anti-glaucoma drug. The present paper aims to characterize the physicochemical properties and degradation kinetics of MTZ to provide a basis for topical ophthalmic delivery. With the increase in pH (pH 5.5-8.0) of aqueous solution, the solubility of the compound increased while the partition coefficient (Ko/w) which was estimated in the system n-octanol/aqueous solution decreased. The degradation of MTZ in aqueous solution followed pseudo-first-order kinetic. The degradation rate kpH is the rate in the absence of buffer catalysis. Plotting the natural logarithm of kpH versus the corresponding pH value gave a V-shaped pH-rate profile with a maximum stability at pH 5.0. The degradation rate constants as a function of the temperature obeyed the Arrhenius equation (R(2)=0.9995 at pH 7.0 and R(2)=0.9955 at pH 9.0, respectively). A decrease in ionic strength and buffer concentration displayed a stabilizing effect on MTZ. Buffer species also influenced the MTZ hydrolysis. Phosphate buffer system was more catalytic than tris and borate buffer systems. In brief, it is important to consider the physicochemical properties and the stability of MTZ during formulation. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Voltammetric oxidation of dipyridamole in aqueous acid solutions

    Directory of Open Access Journals (Sweden)

    Castilho Marilza

    2000-01-01

    Full Text Available The electrochemical oxidation of dipyridamole (DIP has been studied in acidified aqueous solutions at platinum electrodes employing cyclic voltammetry and controlled-potential electrolysis. The progress of the anodic oxidation as a function of time was monitored by cyclic voltammetry with platinum ultramicroelectrodes, absorption and fluorescence optical spectroscopies, the resulting integrated charge being indicative of a two electron process. The cyclic voltammograms registered for low scan speeds are characterized by a single irreversible diffusion controlled anodic wave, the related cathodic wave being also observable for scan speeds higher than 1 V s-1. Oxidation reaction stoichiommetric parameters were obtained through Tafel slopes resulting in unitary reaction orders for DIP and H+.

  16. Pulse radiolysis of pyridinecarboxylic acids in aqueous solution

    Science.gov (United States)

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

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

  17. Pulse radiolysis of Triton X-100 aqueous solution

    International Nuclear Information System (INIS)

    Perkowski, J.; Mayer, J.

    1990-01-01

    Pulse radiolysis of deaerated aqueous solutions of 4 · 10 -5 -2.4 · 10 -3 mol · dm -3 Triton X-100 gives rise to a transient species originating from the reactions of OH radicals and H atoms. The rate constants of these reactions were found to be 8.8 · 10 9 mol -1 · dm 3 · s -1 and 1.25 · 10 9 mol -1 · dm 3 · s -1 , respectively, for Triton X-100 concentrations below CMC. The corresponding transient species were found to decay according to second order kinetics. The mechanism of the reactions, including concentration effects is discussed. (author) 18 refs.; 3 figs

  18. Sequestering nickel (ii) ions from aqueous solutions using various adsorbents

    International Nuclear Information System (INIS)

    Bello, O.S.; Adegoke, K.A.; Bello, O.U.

    2014-01-01

    Adsorption process has proven to be one of the best water treatment technologies around the world and activated carbon is undoubtedly considered as a universal adsorbent for the removal of different types of pollutants from water. However, widespread use of commercial activated carbon is sometimes restricted due to its high cost. Attempts have been made to develop inexpensive adsorbents utilizing numerous agro-industrial and municipal waste materials. Use of agricultural waste materials as low-cost adsorbents is attractive because it reduces the cost of waste disposal, thereby leading to environmental protection. In this review, agricultural, synthetic and other adsorbents used for adsorbing nickel (II) ion from aqueous solutions are reported. Different ways to improve their efficiencies are also discussed. (author)

  19. Partial molar volume of anionic polyelectrolytes in aqueous solution.

    Science.gov (United States)

    Salamanca, Constain; Contreras, Martín; Gamboa, Consuelo

    2007-05-15

    In this work the partial molar volumes (V) of different anionic polyelectrolytes and hydrophobically modified polyelectrolytes (PHM) were measured. Polymers like polymaleic acid-co-styrene, polymaleic acid-co-1-olefin, polymaleic acid-co-vinyl-2-pyrrolidone, and polyacrylic acid (abbreviated as MAS-n, PA-n-K2, AMVP, and PAA, respectively) were employed. These materials were investigated by density measurements in highly dilute aqueous solutions. The molar volume results allow us to discuss the effect of the carboxylic groups and the contributions from the comonomeric principal chain. The PAA presents the smaller V, while the largest V value was for AMVP. The V of PHM shows a linear relationship with the number of methylene groups in the lateral chain. It is found that the magnitude of the contribution per methylene group decreases as the hydrophobic character of the environment increases.

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

    Science.gov (United States)

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

    2016-04-01

    Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε acidic media. © 2015 Wiley Periodicals, Inc.

  1. Photochemical recovery of europium from non-aqueous solutions.

    Science.gov (United States)

    Van den Bogaert, Bart; Gheeraert, Lore; Leblebici, Mumin Enis; Binnemans, Koen; Van Gerven, Tom

    2016-11-21

    The photochemical recovery of europium from non-aqueous media, more specifically alcohols, is studied. The recovery was performed by photochemical reduction of europium(iii) to europium(ii) and subsequent removal as the insoluble EuCl 2 . Two charge transfer bands are present in the UV-C region, one originating from the alcohol (around 230 nm) and the other from the chloride anion (at 271 nm), which are responsible for the photochemical reduction when the solution is illuminated by a medium-pressure mercury lamp. When using different alcohol solvents, a trend is observed with regards to the removal rate and efficiency, following methanol (MeOH) lamp phosphors (Y 2 O 3 :Eu 3+ ), which consist entirely of europium and yttrium with a Eu/Y molar ratio of 1/20-1/30.

  2. Photoreduction of methyl viologen in aqueous neutral solution without additives

    Science.gov (United States)

    Ebbesen, T. W.; Levey, G.; Patterson, L. K.

    1982-08-01

    The direct photoreduction of methyl viologen (paraquat) in aqueous solution to the reducd species radical cation MV(2+)Cl(-)2 was examined to study its effectiveness as a herbicide and in solar photochemical energy conversion devices. Dissolved crystalline cations were found to vary in absorption spectrum with added Cl(-), and excitation with a nitrogen laser at 377 nm indicated the presence of a transient species absorbing below 400 nm. The oxidation of Cl ions by a photolysis-excited state of the MV(2+) is shown to have a quantum yield of 0.2 at 337 nm, using anthracene as a reference. A parallel pathway to normal toxic oxidation of the substance on plants is suggested, involving the photoproduction of the radical Cl(2-), which reacts with thymine, uracil, guanine, histidine, thyrosine, tryptophan, cysteine, and ascorbic acid. The observed properties are suggested to be useful in the photoreduction and oxidation of water.

  3. Adsorption of catechol from aqueous solution by aminated hypercrosslinked polymers.

    Science.gov (United States)

    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.

  4. Neutron dosimetry using aqueous solutions of lithium acetate

    International Nuclear Information System (INIS)

    Rakovan, L.J.

    1996-01-01

    A thermal neutron dosimetry system using the 6 Li(n,α) 3 H reaction and liquid scintillation counting of tritium was developed. Lithium acetate was chosen to supply the 6 Li in the aqueous dosimetry solutions. Neutron irradiations were completed using The Ohio State University Research Reactor. After two sets of samples were irradiated, variables in the system such as the mass of lithium acetate in the solutions and the counting window of the liquid scintillation counter used to analyze the sample were chosen. The system was evaluated by completing two sets of 23 minute irradiations with the reactor at 500 kW, 50 kW, 5 kW, and one irradiation at 500 W. The samples irradiated at 500 W were below the threshold of the system, and could not be used. Prompt analysis was essential due to loss of detectable emissions in the dosimetry solutions over time. The thermal neutron fluences calculated with the data from the samples were compared to the fluences determined from gold wire irradiations. The fluence values differed at most by 6%. The fluence values calculated from the samples were consistently less than those determined from the gold wires

  5. Mechanism of chitosan adsorption on silica from aqueous solutions.

    Science.gov (United States)

    Tiraferri, Alberto; Maroni, Plinio; Rodríguez, Diana Caro; Borkovec, Michal

    2014-05-06

    We present a study of the adsorption of chitosan on silica. The adsorption behavior and the resulting layer properties are investigated by combining optical reflectometry and the quartz crystal microbalance. Exactly the same surfaces are used to measure the amount of adsorbed chitosan with both techniques, allowing the systematic combination of the respective experimental results. This experimental protocol makes it possible to accurately determine the thickness of the layers and their water content for chitosan adsorbed on silica from aqueous solutions of varying composition. In particular, we study the effect of pH in 10 mM NaCl, and we focus on the influence of electrolyte type and concentration for two representative pH conditions. Adsorbed layers are stable, and their properties are directly dependent on the behavior of chitosan in solution. In mildly acidic solutions, chitosan behaves like a weakly charged polyelectrolyte, whereby electrostatic attraction is the main driving force for adsorption. Under these conditions, chitosan forms rigid and thin adsorption monolayers with an average thickness of approximately 0.5 nm and a water content of roughly 60%. In neutral solutions, on the other hand, chitosan forms large aggregates, and thus adsorption layers are significantly thicker (∼10 nm) as well as dissipative, resulting in a large maximum of adsorbed mass around the pK of chitosan. These films are also characterized by a substantial amount of water, up to 95% of their total mass. Our results imply the possibility to produce adsorption layers with tailored properties simply by adjusting the solution chemistry during adsorption.

  6. Thermodynamics of dilute aqueous solutions of imidazolium based ionic liquids

    International Nuclear Information System (INIS)

    Singh, Tejwant; Kumar, Arvind

    2011-01-01

    Research highlights: → The thermodynamic behaviour of aqueous imidazolium ILs has been investigated. → Volumetric and ultrasonic results indicated the hydrophobic hydration of ILs. → Viscometric studies revealed studied ionic liquids as water-structure makers. → Hydration number increased with increase in alkyl chain length of the cation. - Abstract: Experimental measurements of density ρ, speed of sound u, and viscosity η of aqueous solutions of various 1-alkyl-3-methylimidazolium based ionic liquid (IL) solutions have been performed in dilute concentration regime at 298.15 K to get insight into hydration behaviour of ILs. The investigated ILs are based on 1-alkyl-3-methylimidazolium cation, [C n mim] having [BF 4 ] - , [Cl] - , [C 1 OSO 3 ] - , and [C 8 OSO 3 ] - as anions where n = 4 or 8. Several thermodynamic parameters like apparent molar volume φ V , isentropic compressibility β s , and viscosity B-coefficients have been derived from experimental data. Limiting value of apparent molar volume has been discussed in terms of intrinsic molar volume (V int ) molar electrostriction volume (V elec ), molar disordered (V dis ), and cage volume (V cage ). Viscosity B-coefficients have been used to quantify the kosmotropic or chaotropic nature of ILs. Hydration number of ILs obtained using elctrostriction volume, isentropic compressibility, viscosity, and differential scanning calorimetry have been found to be comparative within the experimental error. The hydrophobic hydration has found to play an important role in hydration of ILs as compared to hydration due to hydrogen bonding and electrostriction. Limiting molar properties, hydration numbers, and B-coefficients have been discussed in terms of alkyl chain length of cation or nature of anion.

  7. Spontaneous vesicle phase formation by pseudogemini surfactants in aqueous solutions.

    Science.gov (United States)

    Sun, Nan; Shi, Lijuan; Lu, Fei; Xie, Shuting; Zheng, Liqiang

    2014-08-14

    The phase behavior of a kind of pseudogemini surfactant in aqueous solutions, formed by the mixture of sodium dodecyl benzene sulfonate (SDBS) and butane-1,4-bis (methylimidazolium bromide) ([mim-C4-mim]Br2) or butane-1,4-bis(methylpyrrolidinium bromide) ([mpy-C4-mpy]Br2) in a molar ratio of 2 : 1, is reported in the present work. When [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 is mixed with SDBS in aqueous solutions, one cationic [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 molecule "bridges" two SDBS molecules by noncovalent interactions (e.g. electrostatic, π-π stacking, and σ-π interactions), behaving like a pseudogemini surfactant. Vesicles can be formed by this kind of pseudogemini surfactant, determined by freeze-fracture transmission electron microscopy (FF-TEM) or cryogenic-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). The mixed system of sodium dodecyl sulfate (SDS) with [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 was also constructed, and only micelles were observed. We infer that a pseudogemini surfactant is formed under the synergic effect of electrostatic, π-π stacking, and σ-π interactions in the SDBS/[mim-C4-mim]Br2/H2O system, while electrostatic attraction and hydrophobic interactions may provide the directional force for vesicle formation in the SDBS/[mpy-C4-mpy]Br2/H2O system.

  8. Kinetic study on removal of heavy metal ions from aqueous solution by using soil.

    Science.gov (United States)

    Lim, Soh-Fong; Lee, Agnes Yung Weng

    2015-07-01

    In the present study, the feasibility of soil used as a low-cost adsorbent for the removal of Cu(2+), Zn(2+), and Pb(2+) ions from aqueous solution was investigated. The kinetics for adsorption of the heavy metal ions from aqueous solution by soil was examined under batch mode. The influence of the contact time and initial concentration for the adsorption process at pH of 4.5, under a constant room temperature of 25 ± 1 °C were studied. The adsorption capacity of the three heavy metal ions from aqueous solution was decreased in order of Pb(2+) > Cu(2+) > Zn(2+). The soil was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopic-energy dispersive X-ray (SEM-EDX), and Brunauer, Emmett, and Teller (BET) surface area analyzer. From the FTIR analysis, the experimental data was corresponded to the peak changes of the spectra obtained before and after adsorption process. Studies on SEM-EDX showed distinct adsorption of the heavy metal ions and the mineral composition in the study areas were determined to be silica (SiO2), alumina (Al2O3), and iron(III) oxide (FeO3). A distinct decrease of the specific surface area and total pore volumes of the soil after adsorption was found from the BET analysis. The experimental results obtained were analyzed using four adsorption kinetic models, namely pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion. Evaluating the linear correlation coefficients, the kinetic studies showed that pseudo-second-order equation described the data appropriable than others. It was concluded that soil can be used as an effective adsorbent for removing Cu(2+), Zn(2+), and Pb(2+) ions from aqueous solution.

  9. A method for calculating the acid-base equilibria in aqueous and nonaqueous electrolyte solutions

    Science.gov (United States)

    Tanganov, B. B.; Alekseeva, I. A.

    2017-06-01

    Concentrations of particles in acid-base equilibria in aqueous and nonaqueous solutions of electrolytes are calculated on the basis of logarithmic charts, activity coefficients, and equilibrium constants.

  10. Self-association and thermodynamic behavior of etilefrine hydrochloride in aqueous electrolyte solution

    International Nuclear Information System (INIS)

    Elmasry, Manal S.; Hassan, Wafaa S.; Elazazy, Marwa S.

    2014-01-01

    Highlights: • The self-association of etilefrine HCl in aqueous solution has been studied. • Conductivity and 1 H NMR measurements were used to study the self association. • The critical micelle concentrations and the degree of ionizations were calculated. • The effect of different temperatures and NaCl concentrations were studied. • The thermodynamic parameters of self association of etilefrine HCl were evaluated. - Abstract: The self-association (micellization) behavior of etilefrine HCl, an amphiphilic drug, in aqueous electrolyte solution has been investigated as a function of temperature and sodium chloride (NaCl) concentration by conductivity and 1 H NMR measurements. The critical micelle concentration (CMC) was calculated from the inflection in the data obtained from both techniques. The CMC and the degree of ionization (α) values were determined over the temperature range (298.15 to 313.15) K in water and in presence of different concentrations of NaCl. The thermodynamic parameters of micellization for etilefrine HCl i.e. the standard Gibbs free energy change ΔG° m , the standard enthalpy change, ΔH° m , and the standard entropy change, ΔS° m , were evaluated according to the pseudo-phase model. The obtained CMC values, in presence and absence of electrolyte, showed an inverted U-shaped behavior. While the degree of micelle ionization (α) showed a linear response to the increase in temperature in absence of electrolyte, addition of NaCl did not cause a specific response

  11. Osmotic coefficient of aqueous solutions of cyclohexylsulfamic Acid at the freezing point of solutions.

    Science.gov (United States)

    Bešter-Rogač, Marija; Klofutar, Cveto; Rudan-Tasič, Darja

    2010-12-01

    The osmotic coefficient of aqueous solutions of cyclohexylsulfamic acid was determined by freezing point measurements up to the molality 0.65 mol kg-1. The osmotic coefficients were fitted to the Pitzer equation, and ion interaction parameters α1, β(0) and β(1) were evaluated. The mean ion activity coefficient of the solute was calculated, and the non-ideal behaviour of the system investigated was characterized by calculation of the excess Gibbs energy of solution, as well as the respective partial molar functions of solute and solvent. The partial molar excess Gibbs energy of the solute is negative, like the excess Gibbs energy of its solution, while the partial molar excess Gibbs energy of the solvent is positive and increases with increasing concentration of the solute. The solvation ability of water was calculated from the difference between the Gibbs energy of solution of water in solution and that of pure water, and found to be positive and small for the solute investigated, throughout the concentration range studied.

  12. Densities concentrations of aqueous of uranyl nitrate solutions; densidades concentraciones de soluciones acuosas de nitrato de uranilo

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigo Otero, A.; Rodriguez Hernandez, B.; Fernandez Rodriguez, L.

    1966-07-01

    The ratio density-concentration of aqueous uranyl nitrate solutions expressed as U{sub 3}O{sub 8} grams/liter, U grams/liter and hexahydrate uranyl nitrate weight percent at different temperatures, are established. Experimental values are graphically correlated and compared whit some published data. (Author) 2 refs.

  13. Polyaniline (PANI) modified bentonite by plasma technique for U(VI) removal from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinghao [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Intelligent Manufacturing Technology Research Institute, Hefei University of Technology, Hefei 230088 (China); Cheng, Cheng [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Xiao, Chengjian, E-mail: xiaocj@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Shao, Dadong, E-mail: shaodadong@126.com [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Xu, Zimu, E-mail: xzm@mail.ustc.edu.cn [Intelligent Manufacturing Technology Research Institute, Hefei University of Technology, Hefei 230088 (China); Wang, Jiaquan; Hu, Shuheng [Intelligent Manufacturing Technology Research Institute, Hefei University of Technology, Hefei 230088 (China); Li, Xiaolong; Wang, Weijuan [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2017-07-31

    Highlights: • PANI/bentonie can be synthesized by simple plasma technique. • PANI/bentonie has an excellent adsorption capacity for trace uranium in solution. • U(VI) adsorption on PANI/bentonite is a spontaneous and endothermic process. - Abstract: Polyaniline (PANI) modified bentonite (PANI/bentonie) was synthesized by plasma induced polymerization of aniline on bentonite surface, and applied to uptake of uranium(VI) ions from aqueous solution. The as-synthesized PANI/bentonie was characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Batch adsorption technique was utilized to investigate the adsorption of U(VI) on bentonite and PANI/bentonite. The adsorption of U(VI) (10 mg/L) on PANI/bentonite surface is fairly depend on solution pH, ionic strength, and temperature in solution. The modified PANI on PANI/bentonite surface significantly enhances its adsorption capability for U(VI). The presence of humic acid (HA) can sound enhance U(VI) adsorption on PANI/bentonite at pH < 6.5 because of the strong complexation, and inhibits U(VI) adsorption at pH > 6.5. According to the thermodynamic parameters, the adsorption of U(VI) on PANI/bentonite surface is a spontaneous and endothermic process. The results highlight the application of PANI/bentonite composites as candidate material for the uptake of trace U(VI) from aqueous solution.

  14. Lysozyme as diffusion tracer for measuring aqueous solution viscosity.

    Science.gov (United States)

    Parmar, Avanish S; Muschol, Martin

    2009-11-01

    Measuring tracer diffusion provides a convenient approach for monitoring local changes in solution viscosity or for determining viscosity changes in response to multiple solution parameters including pH, temperature, salt concentrations or salt types. One common limitation of tracer diffusion in biologically relevant saline solutions is the loss of colloidal stability and aggregation of the tracer particles with increasing ionic strength. Using dynamic light scattering to measure tracer diffusion, we compared the performance of two different types of tracer particles, polystyrene nanobeads vs. the small protein lysozyme, for viscosity measurements of saline solutions. Polystyrene beads provide reliable values for water viscosity, but begin flocculating at ionic strengths exceeding about 100mM. Using lysozyme, in contrast, we could map out viscosity changes of saline solutions for a variety of different salts, for salt concentrations up to 1M, over a wide range of pH values, and over the temperature range most relevant for biological systems (5-40 degrees C). Due to its inherently high structural and colloidal stability, lysozyme provides a convenient and reliable tracer particle for all these measurements, and its use can be readily extended to other optical approaches towards localized measurements of tracer diffusion such as fluorescence correlation spectroscopy.

  15. Enthalpies of Dissolution of Crystalline Naproxen Sodium in Water and Potassium Hydroxide Aqueous Solutions at 298 K

    Science.gov (United States)

    Lytkin, A. I.; Chernikov, V. V.; Krutova, O. N.; Bychkova, S. A.; Volkov, A. V.; Skvortsov, I. A.

    2018-03-01

    The enthalpies of dissolution of crystalline naproxen sodium in water and aqueous solutions of KOH at 298.15 K are measured by direct calorimetric means in a wide range of concentrations. The acid-base properties of naproxen sodium at ionic strength I 0 and I = 0.1 (KNO3) and a temperature of 298.15 K are studied by spectrophotometric means. The concentration and thermodynamic dissociation constants are determined. The standard enthalpies of the formation of naproxen sodium and the products of its dissociation in aqueous solution are calculated.

  16. 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.

  17. Conversion of phosphogypsum to potassium sulfate and calcium carbonate in aqueous solution

    Directory of Open Access Journals (Sweden)

    Ennaciri Y.

    2013-09-01

    Full Text Available The dissociation of the phosphogysum by the liquid route which is the object of our work, is most appropriate and little expensive. Indeed, it leads to materials of direct application. The present work has for objective to study the decomposition of the phosphogypsum by the soft chemistry into valuable products such as K2SO4 and CaCO3. K2SO4 is a fertilizer which is highly recommended in the field of the agriculture, while CaCO3 can be used in the fields of the industry (cement and the environment. According to the obtained results, we notice that the decomposition of the phosphogypsum in aqueous solution is very workable, reproducible, inexpensive and it is an ecologically interesting reaction. This reaction is made at room temperature and in aqueous environment, by giving two valuable products K2SO4 and CaCO3. The reaction is total after one hour and a half.

  18. 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.

  19. The effect of gamma irradiation on rice protein aqueous solution

    Science.gov (United States)

    Baccaro, Stefania; Bal, Oya; Cemmi, Alessia; Di Sarcina, Ilaria

    2018-05-01

    The use of proteins as natural biopolymers are sensibly increasing in several application fields such as food industry, packaging and environment protection. In particular, rice proteins (RP) present good nutritional, hypoallergenic and healthful properties very interesting for human consumption. Since ionizing radiation can be successfully applied on protein containing systems involved in different industrial processes, this work aims to determine the effect of gamma radiation on 5 wt%-7.5 wt% RP aqueous solutions in a wide range of absorbed doses up to around 40 kGy. The changes of RP secondary and tertiary structures and their chemical composition were followed by UV-VIS absorbance spectroscopy, luminescence analysis and pH measurements. The experimental data showed the occurrence of the unfolding of RP chains with the increase of the absorbed dose and the formation of new molecules, due to the reaction among tryptophane and tyrosine amino acids and the radical species induced by gamma radiation. The results are also confirmed by the modification of the pH values measured for the irradiated solutions.

  20. Degradation of diuron in aqueous solution by dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Feng Jingwei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China); Zheng Zheng [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)], E-mail: zzheng@nju.edu.cn; Sun Yabing; Luan Jingfei; Wang Zhen; Wang Lianhong; Feng Jianfang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)

    2008-06-15

    Degradation of diuron in aqueous solution was conducted in a dielectric barrier discharge (DBD) reactor and the proposed degradation mechanism was investigated in detail. The factors that affect the degradation of diuron were examined. The degradation efficiency of diuron and the removal of total organic carbon (TOC) increased with increasing input power, and the degradation of diuron by DBD fitted first-order kinetics. Both strong acidic and alkaline solution conditions could improve diuron degradation efficiency and TOC removal rate. Degradation of diuron could be accelerated or inhibited in the presence of H{sub 2}O{sub 2} depending on the dosage. The degradation efficiency increased dramatically with adding Fe{sup 2+}. The removal of TOC and the amount of the detected Cl{sup -}, NO{sub 3}{sup -} and NH{sub 4}{sup +} were increased in the presence of Fe{sup 2+}. The concentrations of oxalic and acetic acids were almost the same in the absence and presence of Fe{sup 2+}, but high concentration of formic acid was accumulated in the presence of Fe{sup 2+}. The main degradation pathway of diuron by DBD involved a series of dechlorination-hydroxylation, dealkylation and oxidative opening of the aromatic ring processes.

  1. Gamma Radiolysis Studies of Aqueous Solution of Brilliant Green Dye

    Directory of Open Access Journals (Sweden)

    D. V. Parwate

    2011-01-01

    Full Text Available The effect of γ–radiation on colour intensity of aqueous solution of Brilliant Green has been investigated at two different concentrations. The degradation of Brilliant Green (BG has also been investigated in presence of suspended ZnO, by adding different amounts of ZnO. Simultaneously the conductance and pH of each solution system were measured before and after γ-irradiation. All the γ–irradiations were performed at a dose rate of 0.60 kGyhr-1 in GC-900. The maximum dose required for the complete degradation of the dye was found to be 0.39 kGy. G(-dye values were found to decrease with increase in gamma dose and were in the range 4.26 - 12.81. The conductance (7.6 - 25.3 μS and pH values increased marginally with dose for both the concentrations. The rate of decolouration was found to be high at lower doses and the efficiency of dye removal was higher at low concentration of the dye. This may be attributed to the presence of reaction by-products from the destruction of parent compound build up and compete for reaction intermediate species. The rate of reaction and rate constants were calculated and it was found that the degradation reaction follows first order kinetics. It was found that the decolouration percentage was more in dye systems in absence of ZnO.

  2. Processes for working-up an aqueous fluosilicic acid solution

    Directory of Open Access Journals (Sweden)

    Alpha O. Toure

    2012-11-01

    Full Text Available Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6%– 7%solution with yields of about 70% – 80%by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol was more successful than precipitation by sodium chloride (EA = 7452.405 J/mol. Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry.

  3. Radiation chemistry of aqueous solutions of cyanamide. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Draganic, Z.D.; Draganic, I.G.; Jovanovic, S.V.

    1978-09-01

    Oxygen-free aqueous solutions of 0.1 M NH/sub 2/CN (pH 2.4 and 5) were irradiated with ..gamma.. rays (0.01--25 Mrad). The rate constants determined in competition experiments are: k(H + NH/sub 2/CN) = 6.7 x 10/sup 6/ M/sup -1/ sec/sup -1/, k(e/sub aq//sup -/ + NH/sub 2/CN) = 1.5 x 10/sup 9/ M/sup -1/ sec/sup -1/, and k(OH + NH/sub 2/CN) = 8.5 x 10/sup 6/ M/sup -1/ sec/sup -1/. Radiation-chemical yields were determined for the decomposition of cyanamide molecules and the formation of several radiolytic products. The following compounds were identified in irradiated solutions: H/sub 2/, CO/sub 2/, NH/sub 3/, urea, biuret, arginine, and a--N=N-- molecule assigned to methylaminoazoformamide. Possible reactions of secondary free radicals leading to the formation of radiolytic products were considered by taking into account the model of water radiolysis and the measured radiation yields.

  4. Electrodialysis potential for fractionation of multicomponent aqueous solutions

    Science.gov (United States)

    Grzegorzek, Martyna; Majewska-Nowak, Katarzyna

    2017-11-01

    The paper aimed at the evaluation of the batch electrodialysis (ED) run in the course of treatment and desalination of various aqueous mixtures containing both mineral (sodium fluoride, sodium chloride) and organic substances (dyes or humic acids). The commercial ED stack (PCCell Bed) equipped with standard anion-exchange and cation-exchange membranes or monovalent selective anion-exchange membranes was used. The ED experiments were performed at a constant current density (1.56 or 1.72 mA/cm2). The mechanism of ion migration as well as membrane deposition for variable solution composition and various membrane types was analyzed The calculated mass balance and electrical energy demand for each ED run were helpful in evaluating the membrane fouling intensity. It was found that the presence of organic substances in the treated solution had a minor impact on energy consumption, but rather strongly affected chloride flux. The extent of organics deposition was significantly lower for monovalent selective anion-exchange membranes than for classic anion-exchange membranes.

  5. Electrodialysis potential for fractionation of multicomponent aqueous solutions

    Directory of Open Access Journals (Sweden)

    Grzegorzek Martyna

    2017-01-01

    Full Text Available The paper aimed at the evaluation of the batch electrodialysis (ED run in the course of treatment and desalination of various aqueous mixtures containing both mineral (sodium fluoride, sodium chloride and organic substances (dyes or humic acids. The commercial ED stack (PCCell Bed equipped with standard anion-exchange and cation-exchange membranes or monovalent selective anion-exchange membranes was used. The ED experiments were performed at a constant current density (1.56 or 1.72 mA/cm2. The mechanism of ion migration as well as membrane deposition for variable solution composition and various membrane types was analyzed The calculated mass balance and electrical energy demand for each ED run were helpful in evaluating the membrane fouling intensity. It was found that the presence of organic substances in the treated solution had a minor impact on energy consumption, but rather strongly affected chloride flux. The extent of organics deposition was significantly lower for monovalent selective anion-exchange membranes than for classic anion-exchange membranes.

  6. Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

    International Nuclear Information System (INIS)

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Rácz, Gergely; Takács, Erzsébet; Wojnárovits, László

    2014-01-01

    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 H 2 O 2 formation. • The toxicity in tap water is smaller than in pure water

  7. Adsorption of gold (III) from aqueous solutions on bagasse ash

    International Nuclear Information System (INIS)

    Hussain, G.; Khan, M.A.

    2011-01-01

    To assess the potential of cheap biomass materials for the recovery of gold from industrial, and electroplating waste water effluents, adsorption of gold (III) from dilute solutions of hydrochloric acid on bagasse ash has been studied under various experimental conditions by using batch technique. Percentage extraction of gold (III) on bagasse ash was determined from its distribution coefficients as a function of contact time, pH, adsorbent, adsorbate concentrations, and temperature. The uptake of gold (III) by bagasse ash is time, pH, metal concentration, amount of adsorbate, and temperature dependent. Adsorption data have been interpreted in terms of Langmuir, and the Freundlich equations. Thermodynamic parameters for the adsorption of gold (III) on bagasse ash have been determined at three different temperatures. The positive value of heat of adsorption; delta H 44.52 kJ/mol shows that the adsorption of gold (III) on bagasse ash is endothermic where as the negative value of delta G = -0.5303 kJ/mol at 318 K shows the spontaneity of the process. Delta G becomes more negative with increase in temperature which shows that the adsorption is more favorable at higher temperatures. Under the optimal adsorption conditions the adsorption capacity of gold is 0.70 mg /g of the adsorbent out of which 0.65 mg of gold gets desorbed with 0.1 % thiourea solution. (author)

  8. Silver (I-coordinated bis(trimethoxysilylpropylamine Polycondensate for Adsorptive Removal of Iodide from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Zhang Huifang

    2016-01-01

    Full Text Available Silver-coordinated bis(trimethoxysilylpropylamine polycondensate (TSPA-AgNO3 was prepared and used to adsorb iodide ions in aqueous solutions. Batch adsorption studies were performed to investigate the effects of pH, temperature and coexisting NaCl on adsorption behavior. The results show that TSPA-AgNO3 is easy to prepare and remarkably efficient in adsorbing iodide in water, especially in acidic solutions. Furthermore, increased temperature accelerated the adsorption, while coexisting NaCl inhibited the adsorption. TSPA-AgNO3 also proved to be chemically stable in simulated environmental situations, which reveals a promising potential for applying this method to the disposal of radioactive iodide in environment water.

  9. ELECTROOXIDATION OF USED SYNTHETIC ENGINE OIL IN AQUEOUS SOLUTION OF H2SO4

    Directory of Open Access Journals (Sweden)

    Paweł Piotr Włodarczyk

    2017-02-01

    Full Text Available The paper presents possibility of using used synthetic engine oil to direct electricity production. The measurements conducted in the temperature range 293-333 K. Were measured electrooxidation of used synthetic engine oil emulsion on a smooth platinum electrode in an aqueous solution of H2SO4. The emulsion prepared on the basis of a nonionic surfactant Syntanol DS-10. The maximum current density reached the level of 22 mA/cm2 (temp. 333 K. Measurements shows possibility of direct electricity production from used synthetic engine oil emulsion, so powering fuel cell of this oil.

  10. Comparative ion insertion study into a nanostructured vanadium oxide in aqueous salt solutions

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Q.; Ren, S. L.; Zukowski, J.; Pomeroy, M.; Soghomonian, V., E-mail: soghomon@vt.edu [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2014-07-07

    We present a comparative study for the electrochemical insertion of different cations into a nanostructured vanadium oxide material. The oxide is hydrothemally synthesized and electrically characterized by variable temperature measurements. The electrochemical reactions are performed in aqueous chloride solutions of lithium, sodium, potassium, and ammonium, and the electrochemical behavior of various cycles are correlated with visual changes in the vanadium oxide nanosheets as observed by scanning electron microscopy. We note an increase in the specific charge per cycle in the cases of sodium and ammonium ions only, correlated with minimal physical changes to the nanosheets. The differing behavior of the various ions has implications for their use in electrical energy storage applications.

  11. Investigation of uranium biosorption from aqueous solutions by Dictyopteris polypodioides brown algae

    International Nuclear Information System (INIS)

    Bampaiti, A.; Ege University, Izmir; Yusan, S.; Aytas, S.; Pavlidou, E.; Noli, F.

    2016-01-01

    The biosorption of uranium from aqueous solutions by Dictyopteris polypodioides brown algae was investigated. The effect of pH, uranium concentration, mass of the adsorbent, temperature and contact time on the removal efficiency were studied and the results were simulated by Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Kinetics data could be satisfactorily reproduced by the pseudo-second order equation and thermodynamic parameters were determined in order to evaluate the uranium uptake behavior. SEM/EDS and FTIR were additionally used to characterize the algae and comprehend the sorption process which can be described as a combination of several mechanisms, including physical sorption, ion exchange and complexation. (author)

  12. Biosorption kinetics of Cd (II), Cr (III) and Pb (II) in aqueous solutions by olive stone

    OpenAIRE

    M. Calero; F. Hernáinz; G. Blázquez; M. A. Martín-Lara; G. Tenorio

    2009-01-01

    A by-product from olive oil production, olive stone, was investigated for the removal of Cd (II), Cr (III) and Pb (II) from aqueous solutions. The kinetics of biosorption are studied, analyzing the effect of the initial concentration of metal and temperature. Pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models have been used to represent the kinetics of the process and obtain the main kinetic parameters. The results show that the pseudo-second order model is th...

  13. Selected constants oxidation-reduction potentials of inorganic substances in aqueous solution

    CERN Document Server

    Charlot, G; Marchon, M J C

    2013-01-01

    Selected Constants: Oxidation-reduction Potentials of Inorganic Substances in Aqueous Solution presents tables that will aid chemists in finding the best or most probable value of the normal or formal oxidation-reduction potential of oxidation-reduction systems. The book first presents numerical calculations that show the degree of oxidation and real oxidation-reduction systems, including the value of the potential, temperature, nature and composition of the medium, and the method of determination used. The text then takes a look at the choice of data, as well as intensity/potential curves an

  14. Surfactant-assisted synthesis and characterization of silver nanorods and nanowires by an aqueous solution approach

    Science.gov (United States)

    Zhou, Guangjun; Lü, Mengkai; Yang, Zhongsen; Zhang, Haiping; Zhou, Yuanyuan; Wang, Shumei; Wang, Shufen; Zhang, Aiyu

    2006-03-01

    The silver nanorods and nanowires have been synthesized by a facile aqueous solution process using tri-sodium citrate as reducing agent in the presence of anionic surfactant dodecyl benzene sulfonic acid sodium (DBS). The products were characterized by the techniques of X-ray diffraction (XRD) and transmission electron microscopy (TEM). Experimental results indicated that the concentrations of the reactants AgNO 3 and tri-sodium citrate, in addition to the surfactant DBS should be interdependent in the formation of the silver nanorods and nanowires. The optical properties were investigated and the prepared nanostructures displayed a very strong absorption band at the room temperature.

  15. Feasibility study of silica sol as the carrier of a hydrophobic drug in aqueous solution using enrofloxacin as the model

    International Nuclear Information System (INIS)

    Song Meirong; Song Junling; Ning Aimin; Cui Baoan; Cui Shumin; Zhou Yaobing; An Wankai; Dong Xuesong; Zhang Gege

    2010-01-01

    The aim of this study was to determine the feasibility of using silica sol to carry a hydrophobic drug in aqueous solution. Enrofloxacin, which was selected as the model drug because it is a broad-spectrum antibiotic drug with poor solubility in water, was adsorbed onto silica sol in aqueous solution during cooling from 60 deg. C to room temperature. The drug-loaded silica sol was characterized by transmission electron microscopy, Fourier transform infrared spectrum, thermal gravimetric analysis and ultraviolet-visible light spectroscopy. The results showed that enrofloxacin was adsorbed by silica sol without degradation at a loading of 15.23 wt.%. In contrast to the rapid release from pure enrofloxacin, the drug-loaded silica sol showed a slower release over a longer time. Kinetics analysis suggested the drug release from silica sol was mainly a diffusion-controlled process. Therefore, silica sol can be used to carry a hydrophobic drug in aqueous solution for controlled drug delivery.

  16. Evolution of ZnS Nanoparticles via Facile CTAB Aqueous Micellar Solution Route: A Study on Controlling Parameters

    Directory of Open Access Journals (Sweden)

    Gradzielski Michael

    2008-01-01

    Full Text Available Abstract Synthesis of semiconductor nanoparticles with new photophysical properties is an area of special interest. Here, we report synthesis of ZnS nanoparticles in aqueous micellar solution of Cetyltrimethylammonium bromide (CTAB. The size of ZnS nanodispersions in aqueous micellar solution has been calculated using UV-vis spectroscopy, XRD, SAXS, and TEM measurements. The nanoparticles are found to be polydispersed in the size range 6–15 nm. Surface passivation by surfactant molecules has been studied using FTIR and fluorescence spectroscopy. The nanoparticles have been better stabilized using CTAB concentration above 1 mM. Furthermore, room temperature absorption and fluorescence emission of powdered ZnS nanoparticles after redispersion in water have also been investigated and compared with that in aqueous micellar solution. Time-dependent absorption behavior reveals that the formation of ZnS nanoparticles depends on CTAB concentration and was complete within 25 min.

  17. Surfactant-free exfoliation of graphite in aqueous solutions.

    Science.gov (United States)

    Ricardo, Karen B; Sendecki, Anne; Liu, Haitao

    2014-03-14

    We report an ultrasound exfoliation of graphite in a weakly basic solution to produce multi-layer graphene dispersion. A unique feature of this process is that no surfactant was added to stabilize the exfoliated graphene in water. The concentration of the graphene dispersion prepared by this approach can be up to 0.02 mg mL(-1) and it was stable at room temperature for several months.

  18. Glass transition of aqueous solutions involving annealing-induced ice recrystallization resolves liquid-liquid transition puzzle of water

    Science.gov (United States)

    Zhao, Li-Shan; Cao, Ze-Xian; Wang, Qiang

    2015-01-01

    Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, . Here we report a universal water-content, , dependence of for aqueous solutions. Solutions with vitrify/devitrify at a constant temperature, , referring to freeze-concentrated phase with left behind ice crystallization. Those solutions with totally vitrify at under conventional cooling/heating process though, of the samples annealed at temperatures   to effectively evoke ice recrystallization is stabilized at . Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of by annealing is attributable to freeze-concentrated phase of solutions instead of ‘liquid II phase of water’. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution. PMID:26503911

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

    International Nuclear Information System (INIS)

    Sawai, Teruko; Shimokawa, Toshinari; Miki, Yasushi; Oseko, Koichi; Sawai, Takeshi

    1978-01-01

    Present work deals with the effects of gamma irradiation from 60 Co 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.)

  20. Cobalt separation present in aqueous solution using shell tamarind as bio sorbent

    International Nuclear Information System (INIS)

    Hernandez L, J.

    2014-01-01

    In this work a new carbonaceous material is presented with improved adsorption properties obtained by a heart treatment about 5 min from the shell tamarind. It was found that the samples obtained carbonaceous adsorbents are effective in removing Co 2+ (41 mg / g) ions in aqueous solutions. These samples were prepared from tamarind shell, urea, ammonium nitrate and water. The solution was subjected to a combustion process at different temperatures. Carbonaceous samples prepared in this manner were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy (Sem) and surface area measurements by Physisorption of N 2 . Changes in structure, morphology and texture were studied. The results show that this material is of great importance to the applications of adsorption of metal ions. The measurements of specific surface area (Bet) were 2.35 to 203.76 m 2 g -1 with pore diameters between 2.31 and 15.63 nm, indicating that the samples obtained are predominantly meso porous. The combustion process of the solution proved to be advantageous to improve the textural properties of the tamarind shell. The obtained carbonaceous material plays an important role in adsorption to remove cobalt in aqueous solutions. (Author)

  1. Evaluation of the stability of linezolid in aqueous solution and commonly used intravenous fluids

    Directory of Open Access Journals (Sweden)

    Taylor R

    2017-07-01

    Full Text Available Rachel Taylor, Bruce Sunderland, Giuseppe Luna, Petra Czarniak School of Pharmacy, Faculty of Health Sciences, Curtin University, Bentley, WA, Australia Purpose: The aim was to evaluate the stability of linezolid in commonly used intravenous fluids and in aqueous solution to determine the kinetics of degradation and shelf-life values at alkaline pH values. Methods: Forced degradation studies were performed on linezolid in solution to develop a validated high-performance liquid chromatography analysis. Sodium chloride 0.9%, sodium lactate, and glucose 5% and glucose 10% solution containing 2.0 mg/mL linezolid were stored at 25.0°C (±0.1°C for 34 days. The effect of temperature on the stability of linezolid in 0.1 M sodium hydroxide solution was investigated to determine the activation energy. The degradation rates of linezolid at selected pH values at 70.0°C and the influence of ionic strength were also examined. Activation energy data were applied to determine the shelf-life values at selected pH values, and a pH rate profile was constructed over the pH range of 8.7–11.4. The stability of intravenous linezolid (Zyvox® solution was evaluated by storing at 70.0°C for 72 hours. Results: Linezolid was found to maintain >95.0% of its initial concentration after storage at 25.0°C for 34 days in sodium lactate, 0.9% in sodium chloride, and 5% and 10% in glucose solutions. Linezolid was degraded at alkaline pH values by first-order kinetics. Activation energy data showed that temperature, but not ionic strength, influenced the degradation rate significantly. An activation energy of 58.22 kJ/mol was determined for linezolid in 0.1 M sodium hydroxide solution. Linezolid was least stable at high pH values and at elevated temperatures. It was determined that linezolid has adequate stability for the preparation of intravenous fluids for clinical administration. Conclusion: Linezolid was found to have a shelf life of 34 days at 25°C when added to

  2. Ozone plus radiation on aqueous solution of DNA - a suggestion for treatment of waste water

    International Nuclear Information System (INIS)

    Unnikrishnan, Gouri; Gopakumar, Kamala; Krishnan, D.

    1986-01-01

    Radiation can be used in waste water or sewage treatment for degrading large molecules. A reduction in total organic carbon in model compounds has been reported, following irradiation treatment and this has been enhanced tenfold by bubbling oxygen containing ozone through aqueous solutions of phenols. In similar experiments aqueous solutions of DNA were used as model compounds and the results are reported. (UK)

  3. Adsorption of Cu 2+ , As 3+ and Cd 2+ ions from aqueous solution ...

    African Journals Online (AJOL)

    The adsorption of Cu2+, Cd2+ and As3+ ions on eggshell from aqueous solution was studied under batch conditions at 30, 40, 50 and 60oC and concentrations of 10, 20, 30, 60 and 80 mg/l. The partition coefficient for the ions between aqueous solution and chicken eggshell increased with time and with increase in the ...

  4. A study on the reaction between CO2 and alkanolamines in aqueous solutions

    NARCIS (Netherlands)

    Blauwhoff, P.M.M.; Versteeg, G.F.; Swaaij, W.P.M. van

    1983-01-01

    Literature data on the rates of reaction between CO2 and alkanolamines (MEA, DEA, DIPA, TEA and MDEA) in aqueous solution are discussed. These data induced us to carry out absorption experiments of CO2 into aqueous DEA, DIPA, TEA and MDEA solutions from which the respective rate constants were

  5. A study on the reaction between CO2 and alkanolamines in aqueous solutions

    NARCIS (Netherlands)

    Blauwhoff, P.M.M.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1983-01-01

    Literature data on the rates of reaction between CO2 and alkanolamines (MEA, DEA, DIPA, TEA and MDEA) in aqueous solution are discussed. These data induced us to carry out absorption experiments of CO2 into aqueous DEA, DIPA, TEA and MDEA solutions from which the respective rate constants The

  6. A study on the reaction between CO2 and alkanolamines in aqueous solutions

    NARCIS (Netherlands)

    Blauwhoff, P.M.M.; Versteeg, G.F.; Swaaij, W.P.M. van

    1984-01-01

    Literature data on the rates of reaction between CO2 and alkanolamines (MEA, DEA, DIPA, TEA and MDEA) in aqueous solution are discussed. These data induced us to carry out absorption experiments of CO2 into aqueous DEA, DIPA, TEA and MDEA solutions from which the respective rate constants were

  7. Adsorption of methyl orange from aqueous solution onto PMMA nanofiber: Kinetics study

    Science.gov (United States)

    Zulfikar, Muhammad Ali; Bahri, Afdal; Setiyanto, Henry; Nasir, Muhammad

    2017-07-01

    The potential of polymethyl methacrylate (PMMA) nanofiber prepared by the electrospinning technique for the methyl orange (MO) adsorption from aqueous solution was investigated. In this study, the adsorption experiments were carried out to investigate the effect of temperatures in a batch system. From experiment it can be seen that the MO adsorption using PMMA nanofiber increased with increasing temperature. The kinetic data of MO were analyzed by pseudo-first-order and pseudo-second-order kinetic models. It was found that the amount of MO adsorbed increase with increasing temperature. Kinetics parameters data indicated that the MO adsorption onto PMMA nanofiber was found to follow both pseudo first and second-order rate equations.

  8. Controlling ZIF-67 crystals formation through various cobalt sources in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiangli [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Jiangsu Key Laboratory of Advanced Metallic Materials, Nanjing 211189 (China); Xing, Tiantian [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Lou, Yongbing [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Jiangsu Key Laboratory of Advanced Metallic Materials, Nanjing 211189 (China); Chen, Jinxi, E-mail: chenjinxi@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Jiangsu Key Laboratory of Advanced Metallic Materials, Nanjing 211189 (China)

    2016-03-15

    Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120 °C) and non-hydrothermal (room temperature) from various cobalt sources and 2-methylimidazolate (Hmim) in aqueous solution within 30 min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co{sup 2+} molar ratios and experimental condition. Using Co(NO{sub 3}){sub 2} as cobalt source, small-sized ZIF-67 crystals with agglomeration were formed. For CoCl{sub 2}, small-sized rhombic dodecahedron were obtained. While large-sized crystals of rhombic dodecahedron structure were obtained from CoSO{sub 4} and Co(OAc){sub 2}. Under hydrothermal condition, the size of ZIF-67 crystals tended to be more uniform and the morphology were more regular comparing to non-hydrothermal condition. This study provides a simple way to control the size and morphology of ZIF-67 crystals prepared in aqueous solution. - Graphical abstract: Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120 °C) and non-hydrothermal (room temperature) from four different cobalt sources (Co(NO{sub 3}){sub 2}, CoCl{sub 2}, CoSO{sub 4} and Co(OAc){sub 2}) in aqueous solution within 30 min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co{sup 2+} molar ratios and experimental condition. - Highlights: • The particle size and morphology were determined by the reactivity of cobalt salt. • ZIF-67 could be prepared from CoSO{sub 4} and Co(OAc){sub 2} at Hmim/Co{sup 2+} molar ratio of 10. • Uniform and regular particles were obtained under hydrothermal condition.

  9. Controlling ZIF-67 crystals formation through various cobalt sources in aqueous solution

    International Nuclear Information System (INIS)

    Guo, Xiangli; Xing, Tiantian; Lou, Yongbing; Chen, Jinxi

    2016-01-01

    Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120 °C) and non-hydrothermal (room temperature) from various cobalt sources and 2-methylimidazolate (Hmim) in aqueous solution within 30 min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co 2+ molar ratios and experimental condition. Using Co(NO 3 ) 2 as cobalt source, small-sized ZIF-67 crystals with agglomeration were formed. For CoCl 2 , small-sized rhombic dodecahedron were obtained. While large-sized crystals of rhombic dodecahedron structure were obtained from CoSO 4 and Co(OAc) 2 . Under hydrothermal condition, the size of ZIF-67 crystals tended to be more uniform and the morphology were more regular comparing to non-hydrothermal condition. This study provides a simple way to control the size and morphology of ZIF-67 crystals prepared in aqueous solution. - Graphical abstract: Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120 °C) and non-hydrothermal (room temperature) from four different cobalt sources (Co(NO 3 ) 2 , CoCl 2 , CoSO 4 and Co(OAc) 2 ) in aqueous solution within 30 min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co 2+ molar ratios and experimental condition. - Highlights: • The particle size and morphology were determined by the reactivity of cobalt salt. • ZIF-67 could be prepared from CoSO 4 and Co(OAc) 2 at Hmim/Co 2+ molar ratio of 10. • Uniform and regular particles were obtained under hydrothermal condition.

  10. Calculation of chemical equilibrium between aqueous solution and minerals: the EQ3/6 software package

    International Nuclear Information System (INIS)

    Wolery, T.J.

    1979-01-01

    The newly developed EQ/36 software package computes equilibrium models of aqueous geochemical systems. The package contains two principal programs: EQ3 performs distribution-of-species calculations for natural water compositions; EQ6 uses the results of EQ3 to predict the consequences of heating and cooling aqueous solutions and of irreversible reaction in rock--water systems. The programs are valuable for studying such phenomena as the formation of ore bodies, scaling and plugging in geothermal development, and the long-term disposal of nuclear waste. EQ3 and EQ6 are compared with such well-known geochemical codes as SOLMNEQ, WATEQ, REDEQL, MINEQL, and PATHI. The data base allows calculations in the temperature interval 0 to 350 0 C, at either 1 atm-steam saturation pressures or a constant 500 bars. The activity coefficient approximations for aqueous solutes limit modeling to solutions of ionic strength less than about one molal. The mathematical derivations and numerical techniques used in EQ6 are presented in detail. The program uses the Newton--Raphson method to solve the governing equations of chemical equilibrium for a system of specified elemental composition at fixed temperature and pressure. Convergence is aided by optimizing starting estimates and by under-relaxation techniques. The minerals present in the stable phase assemblage are found by several empirical methods. Reaction path models may be generated by using this approach in conjunction with finite differences. This method is analogous to applying high-order predictor--corrector methods to integrate a corresponding set of ordinary differential equations, but avoids propagation of error (drift). 8 figures, 9 tables

  11. Structure of aqueous electrolyte solutions near a hydrophobic surface

    Directory of Open Access Journals (Sweden)

    M.Kinoshita

    2007-09-01

    Full Text Available The structure of aqueous solutions of 1:1 salts (KCl, NaCl, KF,and CsI near a hydrophobic surface is analysed using the angle-dependent integral equation theory. Water molecules are taken to be hard spheres imbedded with multipolar moments including terms up to octupole order, and hard spherical ions are immersed in this model water. The many-body interactions associated with molecular polarizability are treated at the self-consistent mean field level. The effects of cationic and anionic sizes and salt concentration in the bulk are discussed in detail. As the salt concentration increases, the layer of water molecules next to the surface becomes denser but its orientational order remains almost unchanged. The concentration of each ion at the surface can be drastically different from that in the bulk. Asa striking example, at sufficiently low salt concentrations, the concentration of I- is about 500 times higher than that of F- at the surface.

  12. 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.

  13. Structure and dynamics of aqueous solution of uranyl ions

    International Nuclear Information System (INIS)

    Chopra, Manish; Choudhury, Niharendu

    2014-01-01

    The present work describes a molecular dynamics simulation study of structure and dynamics of aqueous solution of uranyl ions in water. Structural properties of the system in terms of radial distribution functions and dynamical characteristics as obtained through velocity autocorrelation function and mean square displacements have been analyzed. The results for radial distribution functions show the oxygen of water to form the first solvation shell at 2.4 Å around the uranium atom, whereas the hydrogen atoms of water are distributed around the uranium atom with the major peak at around 3.0 Å. Analyses of transport behaviors of ions and water through MSD indicates that the diffusion of the uranyl ion is much less as compared to that of the water molecules. It is also observed that the dynamical behavior of water molecules gets modified due to the presence of uranyl ion. The effect of increase in concentration of uranyl ions on the structure and dynamics of water molecules is also studied

  14. [Reductive degradation of chlorophenols in aqueous solution by gamma irradiation].

    Science.gov (United States)

    Peng, Yun-Xia; He, Shi-Jun; Gong, Wen-Qi; Wang, Jian-Long

    2013-04-01

    Because chlorine is an electron withdrawing group, the highly chlorinated phenols may react quickly with hydrated electrons rather than with hydroxyl radicals. The process of reactions of four chlorophenols (4-CP, 2-CP, 2,4-DCP, 2,4,6-TCP) with e(aq)(-) was investigated in aqueous solutions by detecting the concentration of CPs, Cl- and intermediates. In the e(aq)(-) reductive system, the experimental results showed that the order of four kinds of chlorophenol degradation and dechlorination was 2,4,6-TCP > 2,4-DCP > 2-CP > 4-CP. The greater the chlorine content was the higher reactivity of hydrated electrons towards chlorophenols was. Furthermore, hydrated electrons may preferentially attack the ortho-position of chlorine atom rather than the para-position of chlorine atom. Phenol and Cl- were detected as the final product of the reductive reaction. Additionally, processes of degradation and dechlorination of CPs were observed as the pseudo-first-order kinetics. The reaction constant of degradation of 4-CP, 2-CP, 2,4-DCP and 2,4,6-TCP were 0.154, 0.253, 0.750 and 1.188 kGy(-1), respectively. Meanwhile, the dechlorination of 4-CP, 2-CP, 2,4-DCP and 2,4,6-TCP were 0.137, 0.219, 0.251 and 0.306 kGy(-1), respectively.

  15. Destruction of amphetamine in aqueous solution using gamma irradiation

    Science.gov (United States)

    Alkhuraiji, Turki S.; Ajlouni, Abdul-Wali

    2017-10-01

    Amphetamine-type stimulants are among the most prevalent and widespread commonly abused drugs. Amphetamine and its derivatives were detected in aquatic environment. This study aimed to demonstrate experimentally the ability of γ-irradiation combined with persulfate anions (S2O82-) to degrade and mineralize the amphetamine in aqueous solution. An initial amphetamine concentration of 125 μM in distilled water was completely degraded by a γ-ray dose of 2.8 kGy. Generation of the sulfate radical (SO4•-) from the fast reaction of added S2O82- with hydrated electrons (eaq-; keaq-/S2O82- = 1.1×1010 M-1 s-1) improved the efficiency of amphetamine degradation and mineralization. A γ-ray dose of 0.667 and 0.350 kGy in the absence and presence of S2O82- anions degraded 90% of the amphetamine, respectively. For γ-ray/free O2 and γ-ray/S2O82- systems, 11.5 and 7 kGy was required for 50% amphetamine mineralization, respectively. Addition of HCO3- anions lowered the amphetamine degradation yield, whereas N2 gas, SO42-, and Cl- anions had a negligible effect.

  16. Degradation of diuron in aqueous solution by ozonation.

    Science.gov (United States)

    Feng, Jingwei; Zheng, Zheng; Luan, Jingfei; Zhang, Jibiao; Wang, Lianhong

    2008-09-01

    Degradation of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] in aqueous solution and the proposed degradation mechanism of diuron by ozonation were investigated. The factors that affect the degradation efficiency of diuron were examined. The generated inorganic ions and organic acids during the ozonation process were detected. Total organic carbon removal rate and the amount of the released Cl(-) increased with increasing ozonation time, but only 80.0% of the maximum theoretical concentration of Cl(-) at total mineralization was detected when initial diuron concentration was 13.8 mg L(-1). For N species, the final concentrations of NO3(-) and NH4+ after 60 min of reaction time were 0.28 and 0.19 mg L(-1), respectively. The generated acetic acid, formic acid and oxalic acid were detected during the reaction process. The main degradation pathway of diuron by ozonation involved a series of dechlorination-hydroxylation, dealkylation and oxidative opening of the aromatic ring processes, leading to small organic species and inorganic species. The degradation efficiency of diuron increased with decreasing initial diuron concentration. Higher pH value, more ozone dosage, additive Na2CO3, additive NaHCO3 and additive H2O2 were all advantageous to improve the degradation efficiency of diuron.

  17. Pulse radiolysis of adrenaline in acid aqueous solutions

    International Nuclear Information System (INIS)

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

    1976-01-01

    Pulse radiolysis of adrenaline in acid aqueous solutions (pH 1 to 3) was carried out. The rate constants for the reactions of adrenaline with H and 0H were determined: k(H + adr.) = (0.9 +- 0.1) x 10 9 dm 3 mol -1 s -1 ; k(0H + adr.) = (1.65 +- 0.15) x 10 10 dm 3 mol -1 s -1 . The H-adduct of adrenaline has two lambdasub(max), at 280 and 355 nm, with epsilon 280 = 420 m 2 mol -1 and epsilon 355 = 390 m 2 mol -1 , which disappears according to a first order reaction, k 1 = 1.4 x 10 3 s -1 . The spectra formed by 0H attack was assigned to the corresponding benzoxy radical with absorption maxima at 285 and 365 nm and epsilon 285 = 620 m 2 mol -1 and epsilon 365 = 105 m 2 mol -1 . Due to the overlapping of the intermediates, no decay kinetics could be obtained. (author)

  18. The photochemistry of neptunium in aqueous perchloric acid solutions

    International Nuclear Information System (INIS)

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

    1979-01-01

    The photochemistry of neptunium ions in aqueous perchloric acid has been investigated using 254 and 300 nm UV radiation. In the absence of other reagents, Np(IV) and (V) oxidized to Np(VI), in a stepwise fashion, with individual quantum efficiencies for each step that vary from 0.02 to 0.004. Decreasing acid concentration favors the Np(IV) → Np(V) reaction whereas it hinders the Np(V) → Np(VI) photo-oxidation. When ethanol, acetaldehyde and other mild reducing agents are added to neptunium-perchloric acid solutions which are then photolyzed, the Np species are reduced to Np(III) in a stepwise fashion with individual quantum efficiencies that vary from 0.07 to 0.006. The overall photoredox reactions of neptunium are subject to competing secondary product reactions that become significant as the photolysis products accumulate. Absorption spectrophotometry was used to monitor the changes in Np oxidation states and reference spectra of the various Np oxidation states are given for 1.0 N HClO 4 . The Np species have absorption bands in the 300 to 1320 nm region that obey Beer's law only when they were properly resolved. (author)

  19. Morphology control of brushite prepared by aqueous solution synthesis

    Directory of Open Access Journals (Sweden)

    T. Toshima

    2014-03-01

    Full Text Available Dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O, also known as brushite, is one of the important bioceramics due to not only diseases factors such as kidney stone and plaque formation but also purpose as fluoride insolubilization material. It is used medicinally to supply calcium, and is of interest for its unique properties in biological and pathological mineralization. It is important to control the crystal morphology of brushite since its chemical reactivity depends strongly on its surface properties; thus, its morphology is a key issue for its applications as a functional material or precursor for other bioceramics. Here, we report the effects of the initial pH and the Ca and phosphate ion concentrations on the morphology of DCPD particles during aqueous solution synthesis. Crystal morphologies were analyzed by scanning electron microscopy and X-ray diffraction. The morphology phase diagram of DCPD crystallization revealed that increasing the initial pH and/or ion concentration transformed DCPD morphology from petal-like into plate-like structures.

  20. Montmorillonite surface properties and sorption characteristics for heavy metal removal from aqueous solutions

    International Nuclear Information System (INIS)

    Ijagbemi, Christianah Olakitan; Baek, Mi-Hwa; Kim, Dong-Su

    2009-01-01

    Surface properties of montmorillonite (MMT) and its adsorption characteristics for heavy metals have been investigated with nickel and copper as sorbate from aqueous solutions. Employing the potentiometric and mass titration techniques in batch experimental methods, the point of zero charge (PZC) and point of zero net proton charge (PZNPC) of MMT edges at different ionic strengths present pH PZC and pH PZNPC to be 3.4 ± 0.2. A crossing point was observed for the proton adsorption vs. pH curves at different ionic strengths of KCl electrolyte and in investigating MMT remediation potentialities as sorbent for heavy metals polluted waters, the effects of heavy metal concentration, pH, MMT dosage, reaction time and temperature for Cu 2+ and Ni 2+ uptake were studied. The sorption of metal ions by MMT was pH dependent and the adsorption kinetics revealed sorption rate could be well fitted by the pseudo-second-order rate model. The data according to mass transfer and intraparticle diffusion models confirmed diffusion of solutes inside the clay particles as the rate-controlling step and more important for the adsorption rate than the external mass transfer. Adsorption isotherms showed that the uptake of Cu 2+ and Ni 2+ could be described by the Langmuir model and from calculations on thermodynamic parameters, the positive ΔG o values at different temperatures suggest that the sorption of both metal ions were non-spontaneous. Change in enthalpy (ΔH o ) for Ni 2+ and Cu 2+ were 28.9 and 13.27 kJ/mol K respectively, hence an endothermic diffusion process, as ion uptake increased with increase in temperature. Values of ΔS o indicate low randomness at the solid/solution interface during the uptake of both Cu 2+ and Ni 2+ by MMT. Montmorillonite has a considerable potential for the removal of heavy metal cationic species from aqueous solution and wastewater.

  1. Removal mechanism of phosphate from aqueous solution by fly ash.

    Science.gov (United States)

    Lu, S G; Bai, S Q; Zhu, L; Shan, H D

    2009-01-15

    This work studied the effectiveness of fly ash in removing phosphate from aqueous solution and its related removal mechanism. The adsorption and precipitation of phosphate by fly ash were investigated separately in order to evaluate their role in the removal of phosphate. Results showed that the removal of phosphate by fly ash was rapid. The removal percentage of phosphate in the first 5min reached 68-96% of the maximum removal of phosphate by fly ash. The removal processes of phosphate by fly ash included a fast and large removal representing precipitation, then a slower and longer removal due to adsorption. The adsorption of phosphate on fly ash could be described well by Freundlich isotherm equation. The pH and Ca2+ concentration of fly ash suspension were decreased with the addition of phosphate, which suggests that calcium phosphate precipitation is a major mechanism of the phosphate removal. Comparison of the relative contribution of the adsorption and precipitation to the total removal of phosphate by fly ash showed that the adsorption accounted for 30-34% of the total removal of phosphate, depending on the content of CaO in fly ash. XRD patterns of the fly ash before and after phosphate adsorption revealed that phosphate salt (CaHPO4 x 2H2O) was formed in the adsorption process. Therefore, the removal of phosphate by fly ash can be attributed to the formation of phosphate precipitation as a brushite and the adsorption on hydroxylated oxides. The results suggested that the use of fly ash could be a promising solution to the removal of phosphate in the wastewater treatment and pollution control.

  2. Flash photolysis of chlorine dioxide in aqueous solution

    International Nuclear Information System (INIS)

    Mialocq, Jean-Claude

    1972-01-01

    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 ( 2 Π) + O ( 3 P). The photochemical decomposition is characterized by the formation of small quantities of O ( 3 P) atoms and of equal amounts of chlorine atoms and molecular oxygen, the latter originating in the reaction: ClOO → Cl + O 2 . 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 Cl 2 O 2 , whose UV absorption spectrum has been determined, and which is formed by the reactions: Cl + OClO → Cl 2 O 2 ; Cl + Cl - → Cl 2- ; Cl 2- + OClO → Cl 2 O 2 + Cl - k = (1,0 ±0,1) 10 9 M -1 s -1 . Cl 2 O 2 disappears by a first-order process which leads to the formation of the ions Cl - and ClO 3 - . Competition between the reactions: O ( 3 P) + O 2 → O 3 ; O ( 3 P) + OClO → ClO 3 . ( k OClO + O)/( k O 2 + O) = 1.85±0.25 has been studied and the molar extinction coefficient of ClO 3 determined at its absorption maximum (255 nm): ε 255 nm = (920 ± 90) M -1 cm -1 . (author) [fr

  3. Temperature Induced Aggregation and Clouding in Humic Acid Solutions

    Directory of Open Access Journals (Sweden)

    Leah Shaffer

    2015-01-01

    Full Text Available Humic acids in aqueous solution demonstrate inverse temperature-solubility relationships when solution conditions are manipulated to reduce coulombic repulsion among the humic polyanions. These effects were followed by dynamic light scattering (DLS measurements of the resulting aggregates, as well as the addition of a polarity sensitive fluorescent probe (pyrene. The humic solutions could be primed for temperature induced clouding by carefully lowering the pH to a point where hydration effects became dominant. The exact value of the cloud point (CP was a function of both pH and humate concentration. The CPs mostly lay in the range 50–90°C, but DLS showed that temperature induced aggregation proceeded from approximately 30°C onward. Similar effects could be achieved by adding multivalent cations at concentrations below those which cause spontaneous precipitation. The declouding of clouded humate solutions could be affected by lowering the temperature combined with mechanical agitation to disentangle the humic polymers.

  4. Removal of patulin from aqueous solutions by propylthiol functionalized SBA-15.

    Science.gov (United States)

    Appell, Michael; Jackson, Michael A; Dombrink-Kurtzman, Mary Ann

    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(2)g(-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 °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. Published by Elsevier B.V.

  5. 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.

  6. Removal of patulin from aqueous solutions by propylthiol functionalized SBA-15

    International Nuclear Information System (INIS)

    Appell, Michael; Jackson, Michael A.; Dombrink-Kurtzman, Mary Ann

    2011-01-01

    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 2 g -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.

  7. Interactions of dipeptides with Triton X-100 in aqueous solution: A volumetric and spectroscopic study

    International Nuclear Information System (INIS)

    Yan, Zhenning; Wu, Shuangyan; Pan, Qi; Geng, Rui; Gu, Bixin; Wang, Jianji

    2014-01-01

    Highlights: • The values of V 2,ϕ o and Δ t V° are positive. • Interactions of Triton X-100 with charged and polar groups of dipeptides dominate. • Addition of dipeptide in water decreases the c cmc and the aggregation number of Triton X-100. • The affinity between dipeptide and Triton X-100 micelle increases with the increase in the length of alkyl chain of peptides. • Triton X-100 interacts with dipeptides more weakly than SDS. -- Abstract: The interactions of dipeptides with Triton X-100 in aqueous solution have been investigated by means of density, fluorescence spectroscopy and UV–vis spectroscopy. The standard partial molar volume (V 2,ϕ o ), standard partial molar volume of transfer for dipeptide from water to aqueous Triton X-100 solution (Δ t V o ) and partial molar expansibility (E ϕ o ) have been calculated from density data. Fluorescence spectroscopy was used to estimate the critical micellar concentration (c cmc ) and micelle aggregation number of Triton X-100 in aqueous dipeptide solutions. Effects of temperature and hydrocarbon chain length of dipeptides on the volumetric properties of dipeptide and critical micelle concentration (c cmc ) of Triton X-100 were examined. The pyrene fluorescence spectra were also used to study the change of micropolarity produced by the interactions of Triton X-100 with dipeptides. From the results of UV–vis absorption spectra, the binding constant between dipeptide and Triton X-100 above the c cmc was determined. The results have been interpreted in terms of solute–solvent interactions and structural changes in the mixed solutions

  8. [Adsorption of phenanthrene from aqueous solution on cetylpyridinium bromide (CPB) -modified zeolite].

    Science.gov (United States)

    Li, Jia; Lin, Jian-Wei; Zhan, Yan-Hui; Chen, Zu-Mei; Wang, Peng-Jun

    2014-02-01

    Surfactant-modified zeolites (SMZs) with different coverage types were prepared by loading of different amounts of cetylpyridinium bromide (CPB) onto natural zeolites and were used as adsorbents to remove phenanthrene from aqueous solution. The adsorption of phenanthrene from aqueous solution on monolayer and bilayer SMZs as a function of adsorbent dosage, initial phenanthrene concentration, contact time, and temperature was investigated using batch experiments. Results showed monolayer and bilayer SMZs were effective for the removal of phenanthrene from aqueous solution. The phenanthrene removal efficiency of SMZs increased with increasing adsorbent dosage, but the amount of phenanthrene adsorbed on SMZs decreased with increasing adsorbent dosage. The adsorption kinetics of phenanthrene on SMZs well followed a pseudo-second-order kinetic model. The equilibrium adsorption data of phenanthrene on SMZs at a low concentration of phenanthrene in solution could be described by the Linear equation and Freundlich equation. The main mechanism for phenanthrene adsorption onto monolayer SMZ is hydrophobic interaction, and the main mechanism for phenanthrene adsorption onto bilayer SMZ is organic partitioning. The calculated thermodynamic parameters such as Gibbs free energy change (deltaG(theta)), enthalpy changes (deltaH(theta)), and entropy change (deltaS(theta)) showed that the adsorption process of phenanthrene on SMZs is spontaneous and exothermic in nature. When the CPB loading amount of bilayer SMZ was twice as much as that of monolayer SMZ, the phenanthrene adsorption capacity for bilayer SMZ was slightly higher than that for monolayer SMZ. In a conclusion, both monolayer and bilayer SMZs are promising adsorbents for the removal of phenanthrene from water and wastewater, and monolayer SMZ is a more cost-effective adsorbent for phenanthrene removal than bilayer SMZ.

  9. Determination of the cis-trans isomerization barriers of L-alanyl-L-proline in aqueous solutions and at water/hydrophobic interfaces by on-line temperature-jump relaxation HPLC and dynamic on-column reaction HPLC.

    Science.gov (United States)

    Shibukawa, Masami; Miyake, Ayaka; Eda, Sayaka; Saito, Shingo

    2015-09-15

    Proline cis-trans isomerization is known to play a key role in the rate-determining steps of protein folding. It is thus very important to understand the influence of environments, not only bulk solutions but also microenvironments such as interfaces, on the isomerization reaction of proline peptides. Here we present two HPLC methods for measurements of kinetic and equilibrium parameters for the isomerization reactions in bulk solutions and at liquid/solid interfaces. On-line temperature-jump relaxation HPLC (T-jump HPLC) allows the determination of forward and reverse rate constants of the isomerization in a bulk solution by monitoring the whole time course of conversion of pure isomers from both sides of the reaction, in contrast to other HPLC and capillary zone electrophoresis as well as spectrometric and calorimetric methods, which use a mixture of the isomers. We can then determine cis-trans isomerization barriers of the peptide at liquid/solid interfaces from the kinetic data obtained by dynamic on-column reaction HPLC and T-jump HPLC. We observed that the interconversion around the peptide bond for l-alanyl-l-proline (Ala-Pro) in water is accelerated at the surfaces of an alkyl-bonded silica and a poly(styrene-divinylbenzene) copolymer resin, and this is caused by a remarkable decrease in the enthalpy of activation. The molecular structures of the cis and trans forms of Ala-Pro estimated by quantum mechanics calculation reveal that an equilibrium shift toward the cis form as well as the rapid isomerization of Ala-Pro at the water/hydrophobic interfaces can be attributed to the lower polarity of the interfacial water at the surfaces of the hydrophobic materials compared to that of bulk water.

  10. DETERMINING PARAMETERS OF THE DIELECTRIC FUNCTION OF A SUBSTANCE IN AQUEOUS SOLUTION BY SELF-REFERENCED REFLECTION THZ SPECTROSCOPY

    DEFF Research Database (Denmark)

    2008-01-01

    Method and apparatus for determining dielectric function of liquid solutions and thereby concentrations of substances in aqueous solution or the volatile/non-volatile nature of the liquid by self-referenced reflection THz spectroscopy. Having the aqueous solution in any container with a window al....... The invention is particularly useful for determining alcohol (ethanol) content in aqueous solution containing other substances and particles....

  11. Biosorption of aniline violet from aqueous solution on moringa oleifera saw dust (abstract)

    International Nuclear Information System (INIS)

    Javed, T.; Mirza, M.L.

    2011-01-01

    Batch adsorption studies were carried out to evaluate the potential of Moringa Oleifera wood saw dust for the removal of aniline violet dye from aqueous solution by optimizing different parameters such as effect of shaking time, adsorbent dose, initial adsorbate concentration etc. The experimental data was subjected to different types of linearized isotherm models such as Freundlich, Langmuir and Dubinin-Radushkevich. The Freundlich isotherm was fitted well with the data. The maximum adsorption capacity of 8.92 m mol./g of aniline violet has been observed through Freundlich isotherm by using the optimized parameters of 50 mg of adsorbent, 5 minutes of shaking time at room temperature of 25 deg. C. The sorption mean free energy from Dubinin-Radushkevich isotherm is 13.36 kJ mol 1 indicating chemisorption. Pseudo-first and Pseudo-second order kinetics models were tested for the adsorption of 1.23 X 10/sup -5) mol L/sup -1) of aniline violet onto Moringa Oleifera wood saw dust. The experimental data fitted well for Pseudo-second order model with coefficient of correlation R/sup 2/ greater or equal to 0.999. The uptake of aniline violet was also studied with the rise in temperature. Thermodynamic parameters have been evaluated and the adsorption process seems to be endothermic. The results indicate that the Moringa Oleifera wood saw dust is an efficient adsorbent for aniline violet from aqueous solutions. (author)

  12. Removal of Pb (II from Aqueous Solutions Using Waste Tea Leaves

    Directory of Open Access Journals (Sweden)

    Mehrdad Cheraghi

    2015-03-01

    Full Text Available Background: The presence of lead in natural waters has become an important issue around the world. Lead has been identified as a highly toxic metal that can cause severe environmental and public health problems and its decontamination is of utmost importance. The aim of this work was to evaluate the adsorption of lead (Pb(II on waste tea leaves as a cheap purification method. Methods: In this experimental study, prepared waste tea leaves were used as adsorbent for the removal of Pb (II from aqueous solutions. Adsorption experiments were carried out as batch studies at different contact time, pH, amount of adsorbent, initial metal concentration and temperature. Results: The results showed that maximum removal efficiency was observed at pH 6. Also the adsorption of Pb (II ions increased with decreasing initial metal concentration. The Langmuir isotherm model fits well with the equilibrium adsorption isotherm data and its calculated maximum monolayer adsorption capacity was 166.6 mg g-1 at a temperature of 25±0.1˚C. The kinetic data obtained have been analyzed using pseudo-first-order and pseudo-second-order models. The best fitted kinetic model was found to be pseudo-second-order. Conclusion: The results suggest that tea wastes could be employed as cheap material for the removal of lead from aqueous solutions.

  13. Amoxicillin removal from aqueous solution using activated carbon prepared by chemical activation of olive stone.

    Science.gov (United States)

    Limousy, Lionel; Ghouma, Imen; Ouederni, Abdelmottaleb; Jeguirim, Mejdi

    2017-04-01

    A chemical-activated carbon (CAC) was prepared by phosphoric acid activation of olive stone. The CAC was characterized using various analytical techniques and evaluated for the removal of amoxicillin from aqueous solutions under different operating conditions (initial concentration, 12.5-100 mg L -1 , temperature, 20-25 °C, contact time, 0-7000 min). The CAC characterization indicates that it is a microporous carbon with a specific surface area of 1174 m 2 /g and a pore volume of 0.46 cm 3 /g and contains essentially acidic functional groups. The adsorption tests indicated that 93 % of amoxicillin was removed at 20 °C for 25 mg L -1 initial concentration. Moreover, it was found that adsorption capacity increased with contact time and temperature. Kinetic study shows that the highest correlation was obtained for the pseudo-second-order kinetic model, which confirms that the process of adsorption of amoxicillin is mainly chemisorption. Using the intraparticle diffusion model, the mechanism of the adsorption process was determined. The equilibrium data analysis showed that the Sips and Langmuir models fitted well the experimental data with maximal adsorption capacities of 67.7 and 57 mg/g, respectively, at 25 °C. The chemical-activated carbon of olive stones could be considered as an efficient adsorbent for amoxicillin removal from aqueous solutions.

  14. Adsorption characteristics of As(III) from aqueous solution on iron oxide coated cement (IOCC)

    International Nuclear Information System (INIS)

    Kundu, Sanghamitra; Gupta, A.K.

    2007-01-01

    Contamination of potable groundwater with arsenic is a serious health hazard, which calls for proper treatment before its use as drinking water. The objective of the present study is to assess the effectiveness of iron oxide coated cement (IOCC) for As(III) adsorption from aqueous solution. Batch studies were conducted to study As(III) adsorption onto IOCC at ambient temperature as a function of adsorbent dose, pH, contact time, initial arsenic concentration and temperature. Kinetics reveal that the uptake of As(III) ion is very rapid and most of fixation occurs within the first 20 min of contact. The pseudo-second order rate equation successfully described the adsorption kinetics. Langmuir, Freundlich, Redlich-Peterson (R-P), and Dubinin-Radushkevich (D-R) models were used to describe the adsorption isotherms at different initial As(III) concentrations and at 30 g l -1 fixed adsorbent dose. The maximum adsorption capacity of IOCC for As(III) determined from the Langmuir isotherm was 0.69 mg g -1 . The mean free energy of adsorption (E) calculated from the D-R isotherm was found to be 2.86 kJ mol -1 which suggests physisorption. Thermodynamic parameters indicate an exothermic nature of adsorption and a spontaneous and favourable process. The results suggest that IOCC can be suitably used for As(III) removal from aqueous solutions

  15. Optimization of uranyl ions removal from aqueous solution by natural and modified kaolinites

    Energy Technology Data Exchange (ETDEWEB)

    Elhefnawy, O.A.; Elabd, A.A. [Nuclear and Radiological Regulatory Authority (NRRA), Cairo (Egypt). Nuclear Safeguards and Physical Protection Dept.

    2017-10-01

    The paper addresses the modifications of the most common mineral clay ''kaolinite'' for U(VI) removal from aqueous solutions. A new modified Egyptian natural kaolinite (Ca-MK) was prepared by coating kaolinite with calcium oxide. Another modification process was utilized by calcination and acid activation of kaolinite (E-MK). The Egyptian natural kaolinite (E-NK) and the two modified kaolinites were characterized by different techniques SEM, EDX, XRD, and FTIR. The removal process were investigated in batch experiments as a function of pH, contact time, initial U(VI) concentration, effect of temperature, and recovery of U(VI) were studied. The equilibrium stage was achieved after 60 min and the kinetic data was described well by pseudo-second order model. Isothermal data was better described by the Langmuir isotherm model, indicating the homogeneous removal process. Also the removal process was studied on different temperature 293, 313, and 323 K. The thermodynamic parameters ΔH , ΔS , and ΔG were calculated. The thermodynamic results pointed to the endothermic and favorable nature of the U(VI) removal process in the three kaolinite adsorbents. This study indicated that (Ca-MK) has higher CEC and can be used as a new adsorbent for highly efficient removal of U(VI) from aqueous solutions.

  16. Aluminum speciation in aqueous fluids at deep crustal pressure and temperature

    Science.gov (United States)

    Mookherjee, Mainak; Keppler, Hans; Manning, Craig E.

    2014-05-01

    We investigated aluminum speciation in aqueous fluids in equilibrium with corundum using in situ Raman spectroscopy in hydrothermal diamond anvil cells to 20 kbar and 1000 °C. We have studied aluminum species in (a) pure H2O, (b) 5.3 m KOH solution, and (c) 1 m KOH solution. In order to better understand the spectral features of the aqueous fluids, we used ab initio simulations based on density functional theory to calculate and predict the energetics and vibrational spectra for various aluminum species that are likely to be present in aqueous solutions. The Raman spectra of pure water in equilibrium with Al2O3 are devoid of any characteristic spectral features. In contrast, aqueous fluids with 5.3 m and 1 m KOH solution in equilibrium with Al2O3 show a sharp band at ˜620 cm-1 which could be attributed to the [ species. The band grows in intensity with temperature along an isochore. A shoulder on the high-frequency side of this band may be due to a hydrated, charge neutral Al(OH)3·H2O species. In the limited pressure, temperature and density explored in the present study, we do not find any evidence for the polymerization of the [ species to dimers [(OH)2-Al-(OH)2-Al(OH)2] or [(OH)3-Al-O-Al(OH)3]2-. This is likely due to the relatively low concentration of Al in the solutions and does not rule out significant polymerization at higher pressures and temperatures. Upon cooling of Al-bearing solutions to room temperatures, Raman bands indicating the precipitation of diaspore (AlOOH) were observed in some experiments. The Raman spectra of the KOH solutions (with or without dissolved alumina) showed a sharp OH stretching band at ˜3614 cm-1 and an in-plane OH bending vibration at ˜1068 cm-1, likely related to an OH- ion with the oxygen atom attached to a water molecule by hydrogen bonding. A weak feature at ˜935 cm-1 may be related to the out-of-plane bending vibration of the same species or to an OH species with a different environment.

  17. Removal of Acid Green 25 from Aqueous Solution by Adsorption

    Directory of Open Access Journals (Sweden)

    R. Parimalam

    2012-01-01

    Full Text Available The adsorptive removal of Acid Green 25 by Ananas Comosus (L Activated carbon was investigated in this study. The effects of initial dye concentration, contact time, pH and temperature were studied for the adsorption of Acid Green 25 in batch mode. At 100 mg/L of initial dye concentration the adsorbent removes 182.6 mg/g of dye from solution; it further increases on increasing the temperature. The calculated values of ∆G° indicate that the adsorption process is spontaneous, negative ∆H° indicate that the adsorption process is exothermic and the positive value of ∆S° indicates the increase in randomness. The rate of dye adsorption follows pseudo second order model with an r2 value of 0. 999. Standard adsorption isotherms were used to fit the experimental equilibrium data. The Langmuir, Freundlich, and Tempkin models are appropriate to explain the adsorption phenomenon with good fit.

  18. Adsorption removal of boron in aqueous solutions by amine-modified tannin gel.

    Science.gov (United States)

    Morisada, Shintaro; Rin, Tetsuzen; Ogata, Takeshi; Kim, Yoen-Ho; Nakano, Yoshio

    2011-07-01

    A tannin gel (TG) synthesized from condensed tannin molecules has a remarkable ability to adsorb various metal ions in aqueous solutions. In the present study, the adsorption removal of boron in solutions at various pHs and temperatures has been examined using the TG and the amine-modified tannin gel (ATG) prepared with ammonia treatment of the TG. The adsorption amounts of boron for the TG and the ATG were relatively small and almost constant below pH 7, whereas the boron adsorption amounts increased with increasing pH in the range of pH above 7. Considering that in aqueous solutions above pH 7, the mole fraction of boric acid decreases while that of tetrahydroxyborate ion increases with increasing pH, the boron adsorption onto both gels takes place probably through the chelate formation of tetrahydroxyborate ion with the hydroxy and the amino groups in the gels. Besides, the adsorbability of the ATG for boron was higher than that of the TG due to the stable coordination bond between boron and nitrogen of the amino group in the ATG. The adsorption kinetics were adequately described by the pseudo-second order kinetic equation while the adsorption isotherms followed both the Langmuir and the Freundlich equations. The boron adsorbability of both the TG and the ATG at low boron concentration were comparable or fairly good compared with other adsorbents. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Hexavalent chromium removal from aqueous solutions by a novel powder prepared from Colocasia esculenta leaves.

    Science.gov (United States)

    Nakkeeran, E; Saranya, N; Giri Nandagopal, M S; Santhiagu, A; Selvaraju, N

    2016-08-02

    In this study, batch removal of hexavalent chromium from aqueous solutions by powdered Colocasia esculenta leaves was investigated. Batch experiments were conducted to study the effects of adsorption of Cr(VI) at different pH values, initial concentrations, agitation speeds, temperatures, and contact times. The biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrometer analysis. The biosorptive capacity of the adsorbent was dependent on the pH of the chromium solution in which maximum removal was observed at pH 2. The adsorption equilibrium data were evaluated for various adsorption isotherm models, kinetic models, and thermodynamics. The equilibrium data fitted well with Freundlich and Halsey models. The adsorption capacity calculated was 47.62 mg/g at pH 2. The adsorption kinetic data were best described by pseudo-second-order kinetic model. Thus, Colocasia esculenta leaves can be considered as one of the efficient and cheap biosorbents for hexavalent chromium removal from aqueous solutions.

  20. Biosorption characteristics of phosphates from aqueous solution onto Phoenix dactylifera L. date palm fibers.

    Science.gov (United States)

    Riahi, Khalifa; Thayer, Béchir Ben; Mammou, Abdallah Ben; Ammar, Aouatef Ben; Jaafoura, Mohamed Habib

    2009-10-30

    Phosphates are very important basic materials in agricultural and other industrial applications. The removal of phosphates from surface waters is generally necessary to avoid problems, such as eutrophication, particularly near urban areas. This paper is focused on the sorption of PO4(3-) ions from aqueous solution onto date palm fibers as a raw, natural and abundantly materials. A series of batch tests were conducted and the influence of contact time, initial phosphate concentration, pH of the solution and adsorbent dosage on PO4(3-) specie removal was investigated. FT-IR spectroscopy, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) analysis of the date palm fibers before and after phosphates biosorption and desorption studies were investigated to confirm the mechanism of the retention of phosphates. Results indicate that PO4(3-) uptake increased with increased initial phosphate concentration and decreased with increased pH values. The results showed that the highest phosphates adsorption capacity (4.35 mg/g) was found at pH 6.8, for an adsorbent dosage of 6g/L, initial phosphate concentration of 50mg/L, under a constant temperature of 18 degrees C+/-02, and the equilibrium state was reached within 120 min of exposure time. The relatively low cost and high capabilities of date palm fibers make them potentially attractive adsorbents for the removal of phosphate from aqueous solution.

  1. Biosorption characteristics of phosphates from aqueous solution onto Phoenix dactylifera L. date palm fibers

    International Nuclear Information System (INIS)

    Riahi, Khalifa; Thayer, Bechir Ben; Mammou, Abdallah Ben; Ammar, Aouatef Ben; Jaafoura, Mohamed Habib

    2009-01-01

    Phosphates are very important basic materials in agricultural and other industrial applications. The removal of phosphates from surface waters is generally necessary to avoid problems, such as eutrophication, particularly near urban areas. This paper is focused on the sorption of PO 4 3- ions from aqueous solution onto date palm fibers as a raw, natural and abundantly materials. A series of batch tests were conducted and the influence of contact time, initial phosphate concentration, pH of the solution and adsorbent dosage on PO 4 3- specie removal was investigated. FT-IR spectroscopy, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) analysis of the date palm fibers before and after phosphates biosorption and desorption studies were investigated to confirm the mechanism of the retention of phosphates. Results indicate that PO 4 3- uptake increased with increased initial phosphate concentration and decreased with increased pH values. The results showed that the highest phosphates adsorption capacity (4.35 mg/g) was found at pH 6.8, for an adsorbent dosage of 6 g/L, initial phosphate concentration of 50 mg/L, under a constant temperature of 18 deg. C ± 02, and the equilibrium state was reached within 120 min of exposure time. The relatively low cost and high capabilities of date palm fibers make them potentially attractive adsorbents for the removal of phosphate from aqueous solution.

  2. High-κ Lanthanum Zirconium Oxide Thin Film Dielectrics from Aqueous Solution Precursors.

    Science.gov (United States)

    Woods, Keenan N; Chiang, Tsung-Han; Plassmeyer, Paul N; Kast, Matthew G; Lygo, Alexander C; Grealish, Aidan K; Boettcher, Shannon W; Page, Catherine J

    2017-03-29

    Metal oxide thin films are critical components in modern electronic applications. In particular, high-κ dielectrics are of interest for reducing power consumption in metal-insulator-semiconductor (MIS) field-effect transistors. Although thin-film materials are typically produced via vacuum-based methods, solution deposition offers a scalable and cost-efficient alternative. We report an all-inorganic aqueous solution route to amorphous lanthanum zirconium oxide (La 2 Zr 2 O 7 , LZO) dielectric thin films. LZO films were spin-cast from aqueous solutions of metal nitrates and annealed at temperatures between 300 and 600 °C to produce dense, defect-free, and smooth films with subnanometer roughness. Dielectric constants of 12.2-16.4 and loss tangents MIS devices utilizing LZO as the dielectric layer (1 kHz). Leakage currents <10 -7 A cm -2 at 4 MV cm -1 were measured for samples annealed at 600 °C. The excellent surface morphology, high dielectric constants, and low leakage current densities makes these LZO dielectrics promising candidates for thin-film transistor devices.

  3. Method to separate ionized substances with special chemical or physical characteristics from an aqueous solution

    International Nuclear Information System (INIS)

    Zimmermann, U.

    1975-01-01

    Ionized substances may be separated from aqueous solutions containing at least 0.5 mM Mg and/or Ca or K ions with the aid of complexing agents which form compounds hard to dissociate or dissolve with the substances to be separated. The present method uses bubbles of living cells (e.g. bacterial cells) containing complexing agents, whose osmolarity is different from that of the aqueous solution. Mass transfer takes place through the cell membrane. Separation is carried out by well-known processes (flotation, sedimentation, filtration etc.). The varying osmolarity of the successive process steps is achieved by adding osmotically active substances. It is one of the main advantages of the process that the acidity of seawater need not be changed in the case of substances dissolved in seawater. Also, raw materials can be regained from waste water in an economical way. For different ionized substances to be extracted and separated from each other, suitable complexing agents may be used one after the other or in separate chambers. The process also works with low-molecular complexing agents (e.g. uranium extraction from seawater using β-hydroxychinoline). When using bacterial cells, the process is carried out at temperatures between 15 0 C and 40 0 C, pH = 8, with addition of the potassium salt of ethylene diamine-tetracetic acid and lysozyme. The example given in the paper describes a solution for the extraction of nickel (10 4 mol/l). (UWI) [de

  4. EQUILIBRIUM AND KINETIC STUDY OF ADSORPTION OF NICKEL FROM AQUEOUS SOLUTION ONTO BAEL TREE LEAF POWDER

    Directory of Open Access Journals (Sweden)

    P. SENTHIL KUMAR

    2009-12-01

    Full Text Available The ability of bael tree (BT leaf powder to adsorb nickel, Ni2+, from aqueous solutions has been investigated through batch experiments. The Ni2+ adsorption was found to be dependent on adsorbent dosage, initial concentration and contact time. All batch experiments were carried out at natural solution pH and at a constant temperature of 30°C using wrist-action shaker that operated at 120 rpm. The experimental isotherm data were analyzed using the Langmuir, Freundlich and Temkin equations. The monolayer adsorption capacity is 1.527 mg Ni per g BT leaf powder. The experiments showed that highest removal rate was 60.21% for Ni2+ under optimal conditions. The kinetic processes of Ni2+ adsorption on BT leaf powder were described by applying pseudo-first-order and pseudo-second-order rate equations. The kinetic data for the adsorption process obeyed pseudo-second-order rate equations. The BT leaf powder investigated in this study exhibited a high potential for the removal of Ni2+ from aqueous solution.

  5. NMR studies of the equilibria and reaction rates in aqueous solutions of formaldehyde.

    Science.gov (United States)

    Rivlin, Michal; Eliav, Uzi; Navon, Gil

    2015-03-26

    Formaldehyde has an important role in the chemical industry and in biological sciences. In dilute aqueous solutions of formaldehyde only traces of the molecular formaldehyde are present and the predominant species are methylene glycol and in lower concentrations, dimethylene glycol. The chemical equilibria and reaction rates of the hydration of formaldehyde in H2O and D2O solutions at low concentrations were studied by (1)H and (13)C NMR at various conditions of pH (1.8-7.8) and temperature (278-333 K). These measurements became possible by direct detection of formaldehyde (13)C and (1)H peaks. The equilibrium and rate constants of the dimerization reaction of methylene glycol were also measured. The rate constants for both the hydration and the dimerization reactions were measured by a new version of the conventional selective inversion transfer method. This study, together with previous published work, completes the description of dynamics and equilibria of all the processes occurring in dilute aqueous formaldehyde solutions.

  6. Nanoscale Stress-Corrosion of Geomaterials in Aqueous Solutions

    Science.gov (United States)

    Criscenti, L. J.; Rimsza, J. M.; Matteo, E. N.; Jones, R. E.

    2017-12-01

    Predicting subcritical crack propagation in low-permeability geo-materials is an unsolved problem crucial to assessing shale caprocks at CO2 sequestration sites, and controlling fracturing for gas and oil extraction. Experiments indicate that chemical reactions at fluid-material interfaces play a major role in subcritical crack growth by weakening the material and altering crack nucleation and growth rates. However, understanding subsurface fracture has been hindered by a lack of understanding of the mechanisms relating chemical environment to mechanical outcome, and a lack of capability directly linking atomistic insight to macroscale observables. We are using both molecular simulation and experiment to develop an atomistic-level understanding of the chemical-mechanical coupling that controls subcritical crack propagation. We are investigating fracture of isotropic silica glass in different environments (air, distilled water, and Na+-rich solutions) and will extend our research to include clay minerals in shales. Molecular simulations are performed with ReaxFF, a reactive force field that allows for explicit modeling of bond breaking and formation processes during crack propagation. A coarse-graining method produces calculated fracture toughness values from the atomistic data. We are performing double cleavage drilled compression (DCDC) experiments in aqueous environmental chambers and monitoring crack propagation with either a confocal or atomic force microscope. Our results show that silica fracture toughness decreases as the environment changes from air to distilled water to Na+-rich solutions. These results suggest that our newly developed computational and experimental techniques can be used to investigate the impact of fluid composition on crack growth in geo-materials and that we will be able to use these methods to understand coupled chemo-mechanical processes and predict crack propagation in shale minerals. Sandia National Laboratories is a multimission

  7. THE TREATED EGGSHELLS AS A NEW BIOSORBENT FOR ELIMINATION OF CARBARYL PESTICIDE FROM AQUEOUS SOLUTIONS: KINETICS, THERMODYNAMICS AND ISOTHERMS

    Directory of Open Access Journals (Sweden)

    ABDELHAMID BAKKA

    2016-10-01

    Full Text Available The efficiency of treated eggshells (TES for removing the carbaryl pesticide from aqueous solutions was examined by biosorption process. Batch mode experiments were conducted using various parameters such as contact time, temperature, biosorbent amount, carbaryl concentration and pH. Removal efficiency of carbaryl by the TES attained 87.35 % after 60 min of contact time, using 10 mg·L-1 of pesticide and 1.5 g·L-1 of biosorbent. The results indicate that Freundlich equation is well described with the carbaryl adsorption, with correlation coefficient R2 value of 0.99. They showed that the biosorption processes were spontaneous and exothermic. The Gibbs energy ∆G increased with increase in temperature indicating an increase in feasibility of biosorption at low temperature. These results show that treated eggshells can be employed as an alternative to commercial adsorbents in the removal of pesticides from aqueous solutions.

  8. Separation of Co{sup 2+} present in aqueous solution on calcium carbonate; Separacion de Co{sup 2+} presente en solucion acuosa sobre carbonato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Garcia A, E.; Granados C, F. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac, Estado de Mexico (Mexico)

    2008-07-01

    The CaCO{sub 3} was synthesized by precipitation method and characterized using SEM, EDS, TGA and IR. It was studied the adsorption behavior of Co{sup 2+} present in aqueous solution on the synthesized material by experiments batch type at room temperature. Was found that removal of cobalt ions was greater than 40% indicating that this material can be used to remove Co{sup 2+} present in aqueous solution. (Author)

  9. Temperature-Invariant Aqueous Microgels as Hosts for Biomacromolecules.

    Science.gov (United States)

    Mastour Tehrani, Sepehr; Lu, Yijie; Guerin, Gerald; Soleimani, Mohsen; Pichugin, Dmitry; Winnik, Mitchell A

    2015-10-12

    Immobilization of enzymes on solid supports has been widely used to improve enzyme recycling, enzyme stability, and performance. We are interested in using aqueous microgels (colloidal hydrogels) as carriers for enzymes used in high-temperature reactions. These microgels should maintain their volume and colloidal stability in aqueous media up to 100 °C to serve as thermo-stable supports for enzymes. For this purpose, we prepared poly(N-hydroxyethyl acrylamide) (PHEAA) microgels via a two-step synthesis. First, we used precipitation polymerization in water to synthesize colloidal poly(diethylene glycol-ethyl ether acrylate) (PDEGAC) particles as a precursor. PDEGAC forms solvent swollen microgels in organic solvents such as methanol and dioxane and in water at temperatures below 15 °C. In the second step, these PDEGAC particles were transformed to PHEAA microgels through aminolysis in dioxane with ethanolamine and a small amount of ethylenediamine. Dynamic laser scattering studies confirmed that the colloidal stability of microgels was maintained during the aminolysis in dioxane and subsequent transfer to water. Characterization of the PHEAA microgels indicated about 9 mol % of primary amino groups. These provide functionality for bioconjugation. As proof-of-concept experiments, we attached the enzyme horseradish peroxidase (HRP) to these aqueous microgels through (i) N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride (EDC) coupling to the carboxylated microgels or (ii) bis-aryl hydrazone (BAH) coupling to microgels functionalized with 6-hydrazinonicotinate acetone (PHEAA-HyNic). Our results showed that HRP maintained its catalytic activity after covalent attachment (87% for EDC coupling, 96% for BAH coupling). The microgel enhanced the stability of the enzyme to thermal denaturation. For example, the residual activity of the microgel-supported enzyme was 76% after 330 min of annealing at 50 °C, compared to only 20% for the free enzyme under these

  10. KDP Aqueous Solution-in-Oil Microemulsion for Ultra-Precision Chemical-Mechanical Polishing of KDP Crystal

    Directory of Open Access Journals (Sweden)

    Hui Dong

    2017-03-01

    Full Text Available A novel functional KH2PO4 (KDP aqueous solution-in-oil (KDP aq/O microemulsion system for KDP crystal ultra-precision chemical-mechanical polishing (CMP was prepared. The system, which consisted of decanol, Triton X-100, and KH2PO4 aqueous solution, was available at room temperature. The functional KDP aq/O microemulsion system was systematically studied and applied as polishing solution to KDP CMP technology. In this study, a controlled deliquescent mechanism was proposed for KDP polishing with the KDP aq/O microemulsion. KDP aqueous solution, the chemical etchant in the polishing process, was caged into the micelles in the microemulsion, leading to a limitation of the reaction between the KDP crystal and KDP aqueous solution only if the microemulsion was deformed under the effect of the external force. Based on the interface reaction dynamics, KDP aqueous solutions with different concentrations (cKDP were applied to replace water in the traditional water-in-oil (W/O microemulsion. The practicability of the controlled deliquescent mechanism was proved by the decreasing material removal rate (MRR with the increasing of the cKDP. As a result, the corrosion pits on the KDP surface were avoided to some degree. Moreover, the roughnesses of KDP with KDP aq/O microemulsion (cKDP was changed from 10 mM to 100 mM as polishing solutions were smaller than that with the W/O microemulsion. The smallest surface root-mean-square roughness of 1.5 nm was obtained at a 30 mmol/L KDP aq solution, because of the most appropriate deliquescent rate and MRR.

  11. Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures.

    Science.gov (United States)

    Shen, Chen; Julius, Ethan F; Tyree, Timothy J; Dan, Ritwik; Moreau, David W; Thorne, Robert

    2017-06-28

    We demonstrate a method for determining the vitreous phase cryogenic temperature densities of aqueous mixtures, and other samples that require rapid cooling, to prepare the desired cryogenic temperature phase. Microliter to picoliter size drops are cooled by projection into a liquid nitrogen-argon (N2-Ar) mixture. The cryogenic temperature phase of the drop is evaluated using a visual assay that correlates with X-ray diffraction measurements. The density of the liquid N2-Ar mixture is adjusted by adding N2 or Ar until the drop becomes neutrally buoyant. The density of this mixture and thus of the drop is determined using a test mass and Archimedes principle. With appropriate care in drop preparation, management of gas above the liquid cryogen mixture to minimize icing, and regular mixing of the cryogenic mixture to prevent density stratification and phase separation, densities accurate to <0.5% of drops as small as 50 pL can readily be determined. Measurements on aqueous cryoprotectant mixtures provide insight into cryoprotectant action, and provide quantitative data to facilitate thermal contraction matching in biological cryopreservation.

  12. Removal of catechol from aqueous solutions by adsorption onto organophilic-bentonite.

    Science.gov (United States)

    Shakir, K; Ghoneimy, H F; Elkafrawy, A F; Beheir, Sh G; Refaat, M

    2008-02-11

    Organophilic-bentonite, produced by exchange of cetyltrimethylammonium cation for metal cations on the bentonite, was exploited as adsorbent for removal of catechol from aqueous solutions using batch technique. The dependence of removal on various physico-chemical parameters, such as contact time (1-250 min), concentration (0.8-15.3 mmol L(-1)), temperature (30, 40, 50+/-1 degrees C) and pH (5-12) of the adsorptive solution were investigated. Obtained results show that catechol could be removed efficiently ( approximately 100%) at pH values > or =9.9. The uptake process follows first-order rate kinetics and the equilibrium data fit well into the Langmuir and Freundlich adsorption isotherms over a wide range of concentration (1-10 mmol L(-1)). The magnitude of change of free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) were determined.

  13. Removal of oxytetracycline from aqueous solutions by hydroxyapatite as a low-cost adsorbent

    Directory of Open Access Journals (Sweden)

    Harja Maria

    2017-01-01

    Full Text Available The present paper involved a study of the adsorption process of the oxytetracycline drug from aqueous medium by using the hydroxyapatite nanopowders as adsorbent materials. The batch adsorption experiments were performed by monitoring the solution pH, contact time, adsorbent dosage and drug solution concentration. At pH 8 and ambient temperature, high oxytetracycline removal rates of about 97.58% and 89.95% for the uncalcined and calcined nanohydroxyapatites, respectively, were obtained. The kinetic studies indicate that the oxytetracycline adsorption onto nanohydroxyapatite samples follows a pseudo-second order kinetic model. The maximum adsorption capacities of 291.32 mg/g and 278.27 mg/g for uncalcined and calcined nanohydroxyapatite samples, respectively, have been found. So, the conclusion can be drawn that the hydroxyapatite shows good adsorption ability towards oxytetracycline.

  14. Removal of oxytetracycline from aqueous solutions by hydroxyapatite as a low-cost adsorbent

    Science.gov (United States)

    Harja, Maria; Ciobanu, Gabriela

    2017-11-01

    The present paper involved a study of the adsorption process of the oxytetracycline drug from aqueous medium by using the hydroxyapatite nanopowders as adsorbent materials. The batch adsorption experiments were performed by monitoring the solution pH, contact time, adsorbent dosage and drug solution concentration. At pH 8 and ambient temperature, high oxytetracycline removal rates of about 97.58% and 89.95% for the uncalcined and calcined nanohydroxyapatites, respectively, were obtained. The kinetic studies indicate that the oxytetracycline adsorption onto nanohydroxyapatite samples follows a pseudo-second order kinetic model. The maximum adsorption capacities of 291.32 mg/g and 278.27 mg/g for uncalcined and calcined nanohydroxyapatite samples, respectively, have been found. So, the conclusion can be drawn that the hydroxyapatite shows good adsorption ability towards oxytetracycline.

  15. [Ultrasonic inactivation of Aspergillus niger glucose oxidase in aqueous solutions].

    Science.gov (United States)

    Karaseva, E I; Tarun, E I; Metelitsa, D I

    2009-01-01

    The inactivation of Aspergillus niger glucose oxidase (GO) was studied in 0.02 M phosphate-citrate buffer (PCB) at various pH, temperatures of 37-59 degrees C, and sonication with low frequency (27 kHz, LF-US) and high frequency (2.64 MHz, HF-US) ultrasound. The GO inactivation was characterized by the effective first-order inactivation rate constants k(in), k(in)*, and k(in)(us), reflecting the total, thermal, and ultrasonic inactivation components. The constants strongly depended on the pH and temperature of solution, GO concentration, and the presence of acceptors of the free radicals HO* -DMF, DMSO, ethanol, butanol, octanol, and mannitol, confirming that the active radicals formed in the ultrasonic cavitation field played an important role in the GO inactivation. The activation energy in the loss of GO catalytic activity considerably decreased when the enzyme solution was treated with LF-US or HF-US. The dissociative scheme of GO inactivation is discussed. Mannitol can be used for protection of GO from inactivation with LF-US or HF-US in the food industry and immunobiotechnology.

  16. Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

    International Nuclear Information System (INIS)

    Cemal Oezeroglu; Niluefer Metin

    2012-01-01

    In this paper, the crosslinked polyester resin containing acrylic acid functional groups was used for the adsorption of uranium ions from aqueous solutions. For this purpose, the crosslinked polyester resin of unsaturated polyester in styrene monomer (Polipol 353, Poliya) and acrylic acid as weight percentage at 80 and 20%, respectively was synthesized by using methyl ethyl ketone peroxide (MEKp, Butanox M60, Azo Nobel)-cobalt octoate initiator system. The adsorption of uranium ions on the sample (0.05 g copolymer and 5 mL of U(VI) solution were mixed) of the crosslinked polyester resin functionalized with acrylic acid was carried out in a batch reactor. The effects of adsorption parameters of the contact time, temperature, pH of solution and initial uranium(VI) concentration for U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid were investigated. The adsorption data obtained from experimental results depending on the initial U(VI) concentration were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The adsorption capacity and free energy change were determined by using D-R isotherm. The obtained experimental adsorption data depending on temperature were evaluated to calculate the thermodynamic parameters of enthalpy (ΔH o ), entropy (ΔS o ) and free energy change (ΔG o ) for the U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid from aqueous solutions. The obtained adsorption data depending on contact time were analyzed by using adsorption models such as the modified Freundlich, Elovich, pseudo-first order and pseudo-second-order kinetic models. (author)

  17. Schwertmannite stability in anoxic Fe(II)-rich aqueous solution

    Science.gov (United States)

    Paikaray, Susanta; Schröder, Christian; Peiffer, Stefan

    2017-11-01

    Schwertmannite (SHM) is a powerful scavenger for As(III) leading to As(III)-enriched precipitates around acid mine drainage environments that may become exposed to aqueous Fe(II). In this study we have investigated the stability of pure SHM and SHM containing 0.92 wt% As(III) under Fe(II)aq-rich (0.4-1.0 mM) anoxic conditions using XRD, SEM, Mössbauer and FTIR spectroscopic techniques. Schwertmannite transformation proceeded through an alkalinity-driven pathway releasing sulfate and a Fe(II)-catalyzed pathway that generated lepidocrocite and goethite at pH 6 and 6.9 in the presence of 1 mM Fe(II)aq. Lepidocrocite was found to be needle shaped if the SHM contained As(III) and platy for pure SHM. Goethite had a poor degree of crystallinity in As(III) containing SHM. Pre-adsorption of As(III) inhibited the extent of SHM transformation. Fe(II) sorption onto SHM was pH dependent and reflected a sorption edge with complete consumption at pH 6.9, while only ∼20% were adsorbed at pH 5. Surface coverage with Fe(II) appears to be the key parameter controlling extent and products of the transformation process. As(III) concentrations in solution are controlled by two mechanisms: (1) exchange of As(III) for sulfate upon alkalinity-driven transformation of schwertmannite and (2) re-adsorption to new phases formed upon Fe(II)-catalyzed transformation. The adsorbed As(III) has inhibited the extent of transformation and was partly released with the maximum release at pH 5 (0.5%) in the absence of Fe(II)aq.

  18. Electrodeposition of nickel-iridium alloy films from aqueous solutions

    Science.gov (United States)

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

    2018-03-01

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

  19. Comparision of Chitosan Function as Adsorbent for Nitrate Removal Using Synthetic Aqueous Solution and Drinking Water

    Directory of Open Access Journals (Sweden)

    Mohammad Norisepehr

    2013-12-01

    Full Text Available Background & Objectives: Nitrate and nitrite compounds pollution of groundwater resources in recent years which recently their mean concentration due to enhancement of different kind of municipal, industrial and agriculture waste water, were increased. The most common source of nitrates entering the water include chemical fertilizers and animal manure in agriculture, septic tank effluent, wastewater, wastewater treatment plants, animal and plant residue analysis on the ground of non-sanitary disposal of solid waste and the use of absorbing wells for sewage disposal. Materials and methods: This experimental study is applied to the nitrate removal using chitosan in laboratory scale at ambient temperature and the design of the system was Batch. Effects of parameters such as pH, contact time, initial concentration and adsorbent concentration of nitrate on nitrate removal from aqueous solution was studied. Results: Function of chitosan in synthetic aqueous solution and drinking water according to the slurry system results, the optimum condition was obtained at pH=4, 20 min contact time and increasing the initial concentration of nitrate enhance the adsorption capacity of chitosan. Also optimum dosage of adsorbent was obtained at 0.5 g/l. The data obtained from the experiments of adsorbent isotherm were analyzed using Langmuir and Freundlich isotherm models. The Langmuir equation was found to be the best fitness with the experimental data (R2>0.93. Conclusion: Although efficiency of Nitrate removal in synthetic aqueous solution was better than drinking water, adsorption process using chitosan as an option for the design and selection nitrate removal should be considered in order to achieve environmental standards.

  20. Oligomerization and phase transitions in aqueous solutions of native and truncated human beta B1-crystallin.

    Science.gov (United States)

    Annunziata, Onofrio; Pande, Ajay; Pande, Jayanti; Ogun, Olutayo; Lubsen, Nicolette H; Benedek, George B

    2005-02-01

    Human betaB1-crystallin is a major eye-lens protein that undergoes in vivo truncation at the N-terminus with aging. By studying native betaB1 and truncated betaB1DeltaN41, which mimics an age-related in vivo truncation, we have determined quantitatively the effect of truncation on the oligomerization and phase transition properties of betaB1 aqueous solutions. The oligomerization studies show that the energy of attraction between the betaB1DeltaN41 proteins is about 10% greater than that of the betaB1 proteins. We have found that betaB1DeltaN41 aqueous solutions undergo two distinct types of phase transitions. The first phase transition involves an initial formation of thin rodlike assemblies, which then evolve to form crystals. The induction time for the formation of rodlike assemblies is sensitive to oligomerization. The second phase transition can be described as liquid-liquid phase separation (LLPS) accompanied by gelation within the protein-rich phase. We refer to this process as heterogeneous gelation. These two phase transitions are not observed in the case of betaB1 aqueous solutions. However, upon the addition of poly(ethylene glycol) (PEG), we observe heterogeneous gelation also for betaB1. Our PEG experiments allow us to estimate the difference in phase separation temperatures between betaB1 and betaB1DeltaN41. This difference is consistent with the increase in energy of attraction found in our oligomerization studies. Our work suggests that truncation is a cataractogenic modification since it favors protein condensation and the consequent formation of light scattering elements, and highlights the importance of the N-terminus of betaB1 in maintaining lens transparency.