WorldWideScience

Sample records for solvent ionic strength

  1. Thermodynamics of the second-stage dissociation of 2-[N-(2-hydroxyethyl)-N-methylaminomethyl]-propenoic acid (HEMPA) in water at different ionic strength and different solvent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Taha, Mohamed [Department of Chemistry, Faculty of Science, Cairo University, Beni-Suef Branch, Beni-Suef (Egypt)]. E-mail: mtaha978@yahoo.com; Fazary, Ahmed E. [Department of Chemistry, Faculty of Science, Cairo University, Beni-Suef Branch, Beni-Suef (Egypt)

    2005-01-01

    The second stage dissociation constant pK{sub 2} of 2-[N-(2-hydroxyethyl)-N-methylaminomethyl]-propenoic acid (HEMPA) has been determined in aqueous solution at different ionic strengths and different temperatures, using pH-metric technique. The thermodynamic quantities ({delta}G{sup 0}, {delta}H{sup 0}, and {delta}S{sup 0}) have been studied and discussed. Evaluation of the effect of organic solvent of the medium on the dissociation processes have also been reported and discussed. The organic solvents used were methanol, dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone and dioxane. The pK{sub 2} for the ionization in water +10, +20, +30, +40 and +50 wt% dioxane has been determined at five different temperatures from T = (288.15 to 308.15) K at intervals of 5 K. The thermodynamic quantities were calculated. The implications of the results with regard to specific (solute + solvent) interactions (particularly stabilization of zwitterionic species) are also discussed.

  2. Thermodynamics of the second-stage dissociation of 2-[N-(2-hydroxyethyl)-N-methylaminomethyl]-propenoic acid (HEMPA) in water at different ionic strength and different solvent mixtures

    International Nuclear Information System (INIS)

    Taha, Mohamed; Fazary, Ahmed E.

    2005-01-01

    The second stage dissociation constant pK 2 of 2-[N-(2-hydroxyethyl)-N-methylaminomethyl]-propenoic acid (HEMPA) has been determined in aqueous solution at different ionic strengths and different temperatures, using pH-metric technique. The thermodynamic quantities (ΔG 0 , ΔH 0 , and ΔS 0 ) have been studied and discussed. Evaluation of the effect of organic solvent of the medium on the dissociation processes have also been reported and discussed. The organic solvents used were methanol, dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone and dioxane. The pK 2 for the ionization in water +10, +20, +30, +40 and +50 wt% dioxane has been determined at five different temperatures from T = (288.15 to 308.15) K at intervals of 5 K. The thermodynamic quantities were calculated. The implications of the results with regard to specific (solute + solvent) interactions (particularly stabilization of zwitterionic species) are also discussed

  3. CADDIS Volume 2. Sources, Stressors and Responses: Ionic Strength

    Science.gov (United States)

    Introduction to the ionic strength module, when to list ionic strength as a candidate cause, ways to measure ionic strength, simple and detailed conceptual diagrams for ionic strength, ionic strength module references and literature reviews.

  4. Molecular and ionic hydrogen bond formation in fluorous solvents.

    Science.gov (United States)

    O'Neal, Kristi L; Weber, Stephen G

    2009-01-08

    There are only a few studies of noncovalent association in fluorous solvents and even fewer that are quantitative. A full understanding, particularly of stoichiometry and binding strength of noncovalent interactions in fluorous solvents could be very useful in improved molecular-receptor-based extractions, advancements in sensor technologies, crystal engineering, and supramolecular chemistry. This work investigates hydrogen bonding between heterocyclic bases and a perfluoropolyether with a terminal carboxylic acid group (Krytox 157FSH (1)), chiefly in FC-72 (a mixture of perfluorohexanes). In particular, we were interested in whether or not proton transfer occurs, and if so, under what conditions in H-bonded complexes. Continuous variations experiments show that in FC-72 weaker bases (pyrazine, pyrimidine, and quinazoline) form 1:1 complexes with 1, whereas stronger bases (quinoline, pyridine, and isoquinoline) form 1:3 complexes. Ultraviolet and infrared spectral signatures reveal that the 1:1 complexes are molecular (B.HA) whereas the 1:3 complexes are ionic (BH+.A-HAHA). Infrared spectra of 1:3 ionic complexes are discussed in detail. Literature and experimental data on complexes between N-heterocyclic bases and carboxylic acids in a range of solvents are compiled to compare solvent effects on proton transfer. Polar solvents support ionic hydrogen bonds at a 1:1 mol ratio. In nonpolar organic solvents, ionic hydrogen bonds are only observed in complexes with 1:2 (base/acid) stoichiometries. In fluorous solvents, a larger excess of acid, 1:3, is necessary to facilitate proton transfer in hydrogen bonds between carboxylic acids and the bases studied.

  5. Effect of ionic strength on the kinetics of ionic and micellar reactions in aqueous solution

    International Nuclear Information System (INIS)

    Dung, M.H.; Kozak, J.J.

    1982-01-01

    The effect of electrostatic forces on the rate of reaction between ions in aqueous solutions of intermediate ionic strength is studied in this paper. We consider the kinetics of reactions involving simple ionic species (1--1 and 2--2 electrolyte systems) as well as kinetic processes mediated by the presence of micellar ions (or other charged organizates). In the regime of ionic strength considered, dielectric saturation of the solvent in the vicinity of the reacting ions must be taken into account and this is done by introducing several models to describe the recovery of the solvent from saturation to its continuum dielectric behavior. To explore the effects of ion size, charge number, and ionic strength on the overall rate constant for the process considered, we couple the traditional theory of ionic reactions in aqueous solution with calculations of the electrostatic potential obtained via solution of the nonlinear Poisson--Boltzmann equation. The great flexibility of the nonlinear Poisson--Boltzmann theory allows us to explore quantitatively the influence of each of these effects, and our simulations show that the short-range properties of the electrostatic potential affect primarily kinetically controlled processes (to varying degrees, depending on the ionic system considered) whereas the down-range properties of the potential play a (somewhat) greater role in influencing diffusion-controlled processes. A detailed examination is made of ionic strength effects over a broad range of ionic concentrations. In the regime of low ionic strength, the limiting slope and intercept of the curve describing the dependence of log k/sub D/ on I/sup 1/2//(1+I/sup 1/2/) may differ considerably from the usual Debye--Hueckel limiting relations, depending on the particular model chosen to describe local saturation effects

  6. Solvent effects in ionic liquids: empirical linear energy-density relationships.

    Science.gov (United States)

    Cerda-Monje, A; Aizman, A; Tapia, R A; Chiappe, C; Contreras, R

    2012-07-28

    Multiparameter linear energy-density relationships to model solvent effects in room temperature ionic liquids (RTILs) are introduced and tested. The model incorporates two solvent dependent and two specific solute-solvent parameters represented by a set of electronic indexes derived from the conceptual density functional theory. The specific solute-solvent interactions are described in terms of the electronic chemical potential for proton migration between the anion or cation and the transition state structure of a specific reaction. These indexes provide a quantitative estimation of the hydrogen bond (HB) acceptor basicity and the hydrogen bond donor acidity of the ionic solvent, respectively. A sound quantitative scale of HB strength is thereby obtained. The solvent dependent contributions are described by the global electrophilicity of the cation and nucleophilicity of the anion forming the ionic liquid. The model is illustrated for the kinetics of cycloaddition of cyclopentadiene towards acrolein. In general, cation HB acidity outweighs the remaining parameters for this reaction.

  7. Phase Behavior of Mixtures of Ionic Liquids and Organic Solvents

    DEFF Research Database (Denmark)

    Abildskov, Jens; Ellegaard, Martin Dela; O’Connell, J.P.

    2010-01-01

    A corresponding-states form of the generalized van der Waals equation, previously developed for mixtures of an ionic liquid and a supercritical solute, is here extended to mixtures including an ionic liquid and a solvent (water or organic). Group contributions to characteristic parameters...... are implemented, leading to an entirely predictive method for densities of mixed compressed ionic liquids. Quantitative agreement with experimental data is obtained over wide ranges of conditions. Previously, the method has been applied to solubilities of sparingly soluble gases in ionic liquids and in organic...... solvents. Here we show results for heavier and more-than-sparingly solutes such as carbon dioxide and propane in ionic liquids....

  8. Organic high ionic strength aqueous two-phase solvent system series for separation of ultra-polar compounds by spiral high-speed counter-current chromatography

    Science.gov (United States)

    Zeng, Yun; Liu, Gang; Ma, Ying; Chen, Xiaoyuan; Ito, Yoichiro

    2011-01-01

    Existing two-phase solvent systems for high-speed countercurrent chromatography cover the separation of hydrophobic to moderately polar compounds, but often fail to provide suitable partition coefficient values for highly polar compounds such as sulfonic acids, catecholamines and zwitter ions. The present paper introduces a new solvent series which can be applied for the separation of these polar compounds. It is composed of 1-butanol, ethanol, saturated ammonium sulfate and water at various volume ratios and consists of a series of 10 steps which are arranged according to the polarity of the solvent system so that the two-phase solvent system with suitable K values for the target compound(s) can be found in a few steps. Each solvent system gives proper volume ratio and high density difference between the two phases to provide a satisfactory level of retention of the stationary phase in the spiral column assembly. The method is validated by partition coefficient measurement of four typical polar compounds including methyl green (basic dye), tartrazine (sulfonic acid), tyrosine (zwitter ion) and epinephrine (a catecholamine), all of which show low partition coefficient values in the polar 1-butanol-water system. The capability of the method is demonstrated by separation of three catecholamines. PMID:22033108

  9. CADDIS Volume 2. Sources, Stressors and Responses: Ionic Strength - Simple Conceptual Diagram

    Science.gov (United States)

    Introduction to the ionic strength module, when to list ionic strength as a candidate cause, ways to measure ionic strength, simple and detailed conceptual diagrams for ionic strength, ionic strength module references and literature reviews.

  10. CADDIS Volume 2. Sources, Stressors and Responses: Ionic Strength - Detailed Conceptual Diagram

    Science.gov (United States)

    Introduction to the ionic strength module, when to list ionic strength as a candidate cause, ways to measure ionic strength, simple and detailed conceptual diagrams for ionic strength, ionic strength module references and literature reviews.

  11. Green oxidation of alkenes in ionic liquid solvent by hydrogen ...

    Indian Academy of Sciences (India)

    ern organic synthesis, and pharmacology and poly- mer industry.1–8 ... methyl imidazolium chloride (EMIM) ionic liquid as solvent. ... Synthetic procedure for pure siliceous MCM-41 ... ally coordinating propyl chain spacer, which allowed.

  12. Effect of Ionic Strength on Settling of Activated Sludge

    OpenAIRE

    M Ahmadi Moghadam, M Soheili, MM Esfahani

    2005-01-01

    Structural properties of activated sludge flocs were found to be sensitive to small changes in ionic strength. This study investigates the effect of ionic strength on settling of activated sludge. Samples were taken from activated sludge process of Ghazvin Sasan soft drink wastewater treatment plant, then treated with different ionic strengths of KCl and CaCl2 solution, after that the turbidity of supernatant was measured. The results indicated that low ionic strength resulted in a steeper sl...

  13. Unimolecular Solvolyses in Ionic Liquid: Alcohol Dual Solvent Systems

    Directory of Open Access Journals (Sweden)

    Elizabeth D. Kochly

    2016-01-01

    Full Text Available A study was undertaken of the solvolysis of pivaloyl triflate in a variety of ionic liquid:alcohol solvent mixtures. The solvolysis is a kΔ process (i.e., a process in which ionization occurs with rearrangement, and the resulting rearranged carbocation intermediate reacts with the alcohol cosolvent via two competing pathways: nucleophilic attack or elimination of a proton. Five different ionic liquids and three different alcohol cosolvents were investigated to give a total of fifteen dual solvent systems. 1H-NMR analysis was used to determine relative amounts of elimination and substitution products. It was found, not surprisingly, that increasing the bulkiness of alcohol cosolvent led to increased elimination product. The change in the amount of elimination product with increasing ionic liquid concentration, however, varied greatly between ionic liquids. These differences correlate strongly, though not completely, to the Kamlet–Taft solvatochromic parameters of the hydrogen bond donating and accepting ability of the solvent systems. An additional factor playing into these differences is the bulkiness of the ionic liquid anion.

  14. Enhanced performance of dicationic ionic liquid electrolytes by organic solvents

    International Nuclear Information System (INIS)

    Li, Song; Feng, Guang; Cummings Peter, T; Zhang, Pengfei; Fulvio Pasquale, F; Hillesheim Patrick, C; Dai, Sheng

    2014-01-01

    The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance–electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation. (paper)

  15. Nonlocal Poisson-Fermi model for ionic solvent.

    Science.gov (United States)

    Xie, Dexuan; Liu, Jinn-Liang; Eisenberg, Bob

    2016-07-01

    We propose a nonlocal Poisson-Fermi model for ionic solvent that includes ion size effects and polarization correlations among water molecules in the calculation of electrostatic potential. It includes the previous Poisson-Fermi models as special cases, and its solution is the convolution of a solution of the corresponding nonlocal Poisson dielectric model with a Yukawa-like kernel function. The Fermi distribution is shown to be a set of optimal ionic concentration functions in the sense of minimizing an electrostatic potential free energy. Numerical results are reported to show the difference between a Poisson-Fermi solution and a corresponding Poisson solution.

  16. Ionic Liquids as Benign Solvents for the Extraction of Aromatics

    International Nuclear Information System (INIS)

    Hossain, Md. Anwar; Lee, Jeesun; Kim, Dai Hyun; Nguyen, Dinh Quan; Cheong, Minserk; Kim, Hoon Sik

    2012-01-01

    Ionic liquids (ILs) have been extensively investigated as promising alternatives to conventional organic solvents such as sulfolane and N,N-dimethylformamide for the selective extraction of aromatic hydrocarbons from the C 6 -C 10 hydrocarbon mixtures produced from the cracking processes of naphtha and light oils. The most important advantage of ILs over conventional organic solvents is that they are immiscible with aliphatic hydrocarbons, and thus the back extraction of ILs from the raffinate phases and top hydrocarbon-rich layers is not necessary. In this paper, a brief review on the state of the art in the utilization of ILs for aromatics separation is presented

  17. Ionic magnetic fluids in polar solvents with tuned counter-ions

    Energy Technology Data Exchange (ETDEWEB)

    Lopes Filomeno, C. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Grupo de Fluidos Complexos Inst. de Quimica, Univ. de Brasília, Brasília (DF) (Brazil); Kouyaté, M. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Cousin, F. [Lab. Léon Brillouin – CE-Saclay, Gif-sur-Yvette (France); Demouchy, G. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Dpt de physique, Univ. de Cergy Pontoise, Cergy-Pontoise (France); Dubois, E.; Michot, L.; Mériguet, G. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Perzynski, R., E-mail: regine.perzynski@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Peyre, V.; Sirieix-Plénet, J. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Tourinho, F.A. [Grupo de Fluidos Complexos Inst. de Quimica, Univ. de Brasília, Brasília (DF) (Brazil)

    2017-06-01

    The aim of the present study is to propose a new reproducible method for preparing colloidal dispersions of electrostatically charged nanoparticles (NPs) in polar solvents with different kinds of counter-ions. Maghemite NPs are here dispersed in solvents of different dielectric constant, namely water, dimethylsulfoxide (DMSO) and an ionic liquid, ethylammonium nitrate (EAN). If the existence of a NP superficial charge happens to be necessary for the colloidal stability of the dispersions in these three solvents, the standard DLVO theory cannot be used any more to describe the colloidal stability in EAN. The structure of the dispersions and the strength of the interparticle repulsion are investigated by small angle X-ray scattering measurements, in association with Ludwig–Soret coefficient determinations. Specificities, associated to the nature of the counter-ions are identified in this work on the colloidal stability, on the interparticle repulsion and on the Ludwig–Soret coefficient. - Highlights: • A controlled synthesis of ionic magnetic fluids in three polar solvents is proposed. • Colloidal repulsion in the magnetic fluids depends on the counter-ion nature. • Soret coefficient of citrate-coated maghemite nanoparticles is probed in water-pH7. • Thermophilicity of nanoparticles depends on the nature of their counter-ions. • Nanoparticles dressed with same counter-ions have solvent-dependent thermoproperties.

  18. Measurement and Correlation of the Ionic Conductivity of Ionic Liquid-Molecular Solvent Solutions

    Institute of Scientific and Technical Information of China (English)

    LI,Wen-Jing; HAN,Bu-Xing; TAO,Ran-Ting; ZHANG,Zhao-Fu; ZHANG,Jian-Ling

    2007-01-01

    The ionic conductivity of the solutions formed from 1-n-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) or 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) and different molecular solvents (MSs) were measured at 298.15 K. The molar conductivity of the ionic liquids (ILs) increased dramatically with increasing concentration of the MSs. It was found that the molar conductivity of the IL in the solutions studied in this work could be well correlated by the molar conductivity of the neat ILs and the dielectric constant and molar volume of the MSs.

  19. Ionic liquids: solvents and sorbents in sample preparation.

    Science.gov (United States)

    Clark, Kevin D; Emaus, Miranda N; Varona, Marcelino; Bowers, Ashley N; Anderson, Jared L

    2018-01-01

    The applications of ionic liquids (ILs) and IL-derived sorbents are rapidly expanding. By careful selection of the cation and anion components, the physicochemical properties of ILs can be altered to meet the requirements of specific applications. Reports of IL solvents possessing high selectivity for specific analytes are numerous and continue to motivate the development of new IL-based sample preparation methods that are faster, more selective, and environmentally benign compared to conventional organic solvents. The advantages of ILs have also been exploited in solid/polymer formats in which ordinarily nonspecific sorbents are functionalized with IL moieties in order to impart selectivity for an analyte or analyte class. Furthermore, new ILs that incorporate a paramagnetic component into the IL structure, known as magnetic ionic liquids (MILs), have emerged as useful solvents for bioanalytical applications. In this rapidly changing field, this Review focuses on the applications of ILs and IL-based sorbents in sample preparation with a special emphasis on liquid phase extraction techniques using ILs and MILs, IL-based solid-phase extraction, ILs in mass spectrometry, and biological applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Solvent extraction of gold using ionic liquid based process

    Science.gov (United States)

    Makertihartha, I. G. B. N.; Zunita, Megawati; Rizki, Z.; Dharmawijaya, P. T.

    2017-01-01

    In decades, many research and mineral processing industries are using solvent extraction technology for metal ions separation. Solvent extraction technique has been used for the purification of precious metals such as Au and Pd, and base metals such as Cu, Zn and Cd. This process uses organic compounds as solvent. Organic solvents have some undesired properties i.e. toxic, volatile, excessive used, flammable, difficult to recycle, low reusability, low Au recovery, together with the problems related to the disposal of spent extractants and diluents, even the costs associated with these processes are relatively expensive. Therefore, a lot of research have boosted into the development of safe and environmentally friendly process for Au separation. Ionic liquids (ILs) are the potential alternative for gold extraction because they possess several desirable properties, such as a the ability to expanse temperature process up to 300°C, good solvent properties for a wide range of metal ions, high selectivity, low vapor pressures, stability up to 200°C, easy preparation, environmentally friendly (commonly called as "green solvent"), and relatively low cost. This review paper is focused in investigate of some ILs that have the potentials as solvent in extraction of Au from mineral/metal alloy at various conditions (pH, temperature, and pressure). Performances of ILs extraction of Au are studied in depth, i.e. structural relationship of ILs with capability to separate Au from metal ions aggregate. Optimal extraction conditon in order to gain high percent of Au in mineral processing is also investigated.

  1. Ionic strength independence of charge distributions in solvation of biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Virtanen, J. J. [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Sosnick, T. R. [Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 (United States); Computation Institute, University of Chicago, Chicago, Illinois 60637 (United States); Freed, K. F. [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Computation Institute, University of Chicago, Chicago, Illinois 60637 (United States)

    2014-12-14

    Electrostatic forces enormously impact the structure, interactions, and function of biomolecules. We perform all-atom molecular dynamics simulations for 5 proteins and 5 RNAs to determine the dependence on ionic strength of the ion and water charge distributions surrounding the biomolecules, as well as the contributions of ions to the electrostatic free energy of interaction between the biomolecule and the surrounding salt solution (for a total of 40 different biomolecule/solvent combinations). Although water provides the dominant contribution to the charge density distribution and to the electrostatic potential even in 1M NaCl solutions, the contributions of water molecules and of ions to the total electrostatic interaction free energy with the solvated biomolecule are comparable. The electrostatic biomolecule/solvent interaction energies and the total charge distribution exhibit a remarkable insensitivity to salt concentrations over a huge range of salt concentrations (20 mM to 1M NaCl). The electrostatic potentials near the biomolecule's surface obtained from the MD simulations differ markedly, as expected, from the potentials predicted by continuum dielectric models, even though the total electrostatic interaction free energies are within 11% of each other.

  2. Ionic strength independence of charge distributions in solvation of biomolecules

    International Nuclear Information System (INIS)

    Virtanen, J. J.; Sosnick, T. R.; Freed, K. F.

    2014-01-01

    Electrostatic forces enormously impact the structure, interactions, and function of biomolecules. We perform all-atom molecular dynamics simulations for 5 proteins and 5 RNAs to determine the dependence on ionic strength of the ion and water charge distributions surrounding the biomolecules, as well as the contributions of ions to the electrostatic free energy of interaction between the biomolecule and the surrounding salt solution (for a total of 40 different biomolecule/solvent combinations). Although water provides the dominant contribution to the charge density distribution and to the electrostatic potential even in 1M NaCl solutions, the contributions of water molecules and of ions to the total electrostatic interaction free energy with the solvated biomolecule are comparable. The electrostatic biomolecule/solvent interaction energies and the total charge distribution exhibit a remarkable insensitivity to salt concentrations over a huge range of salt concentrations (20 mM to 1M NaCl). The electrostatic potentials near the biomolecule's surface obtained from the MD simulations differ markedly, as expected, from the potentials predicted by continuum dielectric models, even though the total electrostatic interaction free energies are within 11% of each other

  3. Virtual colorimetric sensor array: single ionic liquid for solvent discrimination.

    Science.gov (United States)

    Galpothdeniya, Waduge Indika S; Regmi, Bishnu P; McCarter, Kevin S; de Rooy, Sergio L; Siraj, Noureen; Warner, Isiah M

    2015-04-21

    There is a continuing need to develop high-performance sensors for monitoring organic solvents, primarily due to the environmental impact of such compounds. In this regard, colorimetric sensors have been a subject of intense research for such applications. Herein, we report a unique virtual colorimetric sensor array based on a single ionic liquid (IL) for accurate detection and identification of similar organic solvents and mixtures of such solvents. In this study, we employ eight alcohols and seven binary mixtures of ethanol and methanol as analytes to provide a stringent test for assessing the capabilities of this array. The UV-visible spectra of alcoholic solutions of the IL used in this study show two absorption bands. Interestingly, the ratio of absorbance for these two bands is found to be extremely sensitive to alcohol polarity. A virtual sensor array is created by using four different concentrations of IL sensor, which allowed identification of these analytes with 96.4-100% accuracy. Overall, this virtual sensor array is found to be very promising for discrimination of closely related organic solvents.

  4. Ionic Liquids in Selective Oxidation: Catalysts and Solvents.

    Science.gov (United States)

    Dai, Chengna; Zhang, Jie; Huang, Chongpin; Lei, Zhigang

    2017-05-24

    Selective oxidation has an important role in environmental and green chemistry (e.g., oxidative desulfurization of fuels and oxidative removal of mercury) as well as chemicals and intermediates chemistry to obtain high-value-added special products (e.g., organic sulfoxides and sulfones, aldehydes, ketones, carboxylic acids, epoxides, esters, and lactones). Due to their unique physical properties such as the nonvolatility, thermal stability, nonexplosion, high polarity, and temperature-dependent miscibility with water, ionic liquids (ILs) have attracted considerable attention as reaction solvents and media for selective oxidations and are considered as green alternatives to volatile organic solvents. Moreover, for easy separation and recyclable utilization, IL catalysts have attracted unprecedented attention as "biphasic catalyst" or "immobilized catalyst" by immobilizing metal- or nonmetal-containing ILs onto mineral or polymer supports to combine the unique properties of ILs (chemical and thermal stability, capacity for extraction of polar substrates and reaction products) with the extended surface of the supports. This review highlights the most recent outcomes on ILs in several important typical oxidation reactions. The contents are arranged in the series of oxidation of sulfides, oxidation of alcohols, epoxidation of alkenes, Baeyer-Villiger oxidation reaction, oxidation of alkanes, and oxidation of other compounds step by step involving ILs as solvents, catalysts, reagents, or their combinations.

  5. Volumetric Properties of the Ionic Liquid, 1-Butyl-3-methylimidazolium Tetrafluoroborate, in Organic Solvents at T = 298.15K

    Science.gov (United States)

    Shekaari, Hemayat; Zafarani-Moattar, Mohammed Taghi

    2008-04-01

    Apparent molar volumes, V_φ , and compressibilities, kappa _φ , of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) have been determined from precise density and speed-of-sound measurements in organic solvents, methanol (MeOH), acetonitrile (MeCN), tetrahydrofuran (THF), N, N-dimethylacetamide (DMA), and dimethylsulfoxide (DMSO) in the dilute region of the ionic liquid. Corresponding values at infinite dilution are estimated by the Redlich-Mayer and Pitzer equations. The results have been interpreted by the interaction of the [BMIm][BF4] in the organic solvents. Results show that the structure and dielectric constant of the organic solvents play an important role for the ion-solvent interactions in these mixtures. It was found that the strength of interaction between [BMIm][BF4] with the studied organic solvents has the order DMSO > DMA > MeOH > MeCN > THF.

  6. Comparative Investigation of the Ionicity of Aprotic and Protic Ionic Liquids in Molecular Solvents by using Conductometry and NMR Spectroscopy.

    Science.gov (United States)

    Thawarkar, Sachin; Khupse, Nageshwar D; Kumar, Anil

    2016-04-04

    Electrical conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium-based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15 K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmIm][BF4 ], displays 100 % ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the (1) H NMR chemical shifts of the ionic liquids. The self-diffusion coefficients D of the cation and anion of [HmIm][CH3 COO] in D2 O and in [D6 ]DMSO are determined by using (1) H nuclei with pulsed field gradient spin-echo NMR spectroscopy. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Predictive model for ionic liquid extraction solvents for rare earth elements

    International Nuclear Information System (INIS)

    Grabda, Mariusz; Oleszek, Sylwia; Panigrahi, Mrutyunjay; Kozak, Dmytro; Shibata, Etsuro; Nakamura, Takashi; Eckert, Franck

    2015-01-01

    The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF 3 -ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids’ ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effective extraction solvents for liquid-liquid extraction of DyF 3 were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare earth element for a large number of ionic liquid systems, before extensive experimental tests

  8. Ionic liquids, tuneable solvents for intensifying reactions and separations

    NARCIS (Netherlands)

    Meindersma, G.W.; Kuipers, N.J.M.; Haan, de A.B.

    2007-01-01

    An Ionic Liquid (IL), or a Room Temperature Ionic Liquid (RTIL), is commonly defined as a liquid entirely composed of ions, which is a fluid below 100 °C. Due to the fact that an ionic liquid is a salt, it has a negligible vapour pressure. Therefore, ionic liquids are not volatile at ambient process

  9. Holographic sensors for the determination of ionic strength

    International Nuclear Information System (INIS)

    Marshall, Alexander J.; Young, Duncan S.; Kabilan, Satyamoorthy; Hussain, Abid; Blyth, Jeff; Lowe, Christopher R.

    2004-01-01

    Holographic sensors for monitoring ionic strength have been fabricated from charged sulphonate and quaternary ammonium monomers, incorporated into thin, polymeric hydrogel films which were transformed into volume holograms. The diffraction wavelength or reflected colour of the holograms was used to characterise their swelling or de-swelling behaviour as a function of ionic strength in various media. The effects of co-monomer structure, buffer composition, ion composition, pH and temperature were evaluated, whilst the reversibility and reproducibility of the sensor was also assessed. An acrylamide-based hologram containing equal molar amounts of negatively and positively charged monomers was shown to be able to quantify ionic strength independent of the identity of the ionic species present in the test solution. The sensor was fully reversible, free of hysteresis and exhibited little response to pH between 3 and 9 and temperature within the range 20-45 deg. C. The system was successfully used to quantify the ionic strength of milk solutions, which contain a complex mixture of ions and biological components

  10. Holographic sensors for the determination of ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Alexander J. [Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT (United Kingdom)]. E-mail: ajm205@cam.ac.uk; Young, Duncan S. [Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT (United Kingdom); Kabilan, Satyamoorthy [Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT (United Kingdom); Hussain, Abid [Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT (United Kingdom); Blyth, Jeff [Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT (United Kingdom); Lowe, Christopher R. [Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT (United Kingdom)]. E-mail: crl1@biotech.cam.ac.uk

    2004-11-29

    Holographic sensors for monitoring ionic strength have been fabricated from charged sulphonate and quaternary ammonium monomers, incorporated into thin, polymeric hydrogel films which were transformed into volume holograms. The diffraction wavelength or reflected colour of the holograms was used to characterise their swelling or de-swelling behaviour as a function of ionic strength in various media. The effects of co-monomer structure, buffer composition, ion composition, pH and temperature were evaluated, whilst the reversibility and reproducibility of the sensor was also assessed. An acrylamide-based hologram containing equal molar amounts of negatively and positively charged monomers was shown to be able to quantify ionic strength independent of the identity of the ionic species present in the test solution. The sensor was fully reversible, free of hysteresis and exhibited little response to pH between 3 and 9 and temperature within the range 20-45 deg. C. The system was successfully used to quantify the ionic strength of milk solutions, which contain a complex mixture of ions and biological components.

  11. Solvent extraction of Sr2+ and Cs+ based on hydrophobic protic ionic liquids

    International Nuclear Information System (INIS)

    Luo, Huimin; Yu, Miao; Dai, Sheng

    2007-01-01

    A series of new hydrophobic and protic alkylammonium ionic liquids with bis(trifluoromethylsulfonyl) imide or bis(perfluoroethylsulfonyl)imide as conjugated anions was synthesized in a one-pot reaction with a high yield. In essence our synthesis method involves the combination of neutralization and metathesis reactions. Some of these hydrophobic and protic ionic liquids were liquids at room temperature and therefore investigated as new extraction media for separation of Sr 2+ and Cs + from aqueous solutions. An excellent extraction efficiency was found for some of these ionic liquids using dicyclohexano-18-crown-6 and calix[4]arene-bis(tert-octylbenzo-crown-6) as extractants. The observed enhancement in the extraction efficiency can be attributed to the greater hydrophilicity of the cations of the protic ionic liquids. The application of the protic ionic liquids as new solvent systems for solvent extraction opens up a new avenue in searching for simple and efficient ionic liquids for tailored separation processes. (orig.)

  12. A New Class of Solvents for TRU Dissolution and Separation: Ionic Liquids. Project No. 81891

    International Nuclear Information System (INIS)

    Rogers, Robin D.

    2004-01-01

    Through the current EMSP funding, solvent extraction technologies based on liquid-liquid partitioning of TRU to an Ionic Liquid phase containing conventional complexants has been shown to be viable. The growing understanding of the role that the different components of an ionic liquid can have on the partitioning mechanism, and on the nature of the subsequent dissolved species indicates strongly that ionic liquids are not necessarily direct replacements for volatile or otherwise hazardous organic solvents. Separations and partitioning can be exceptionally complex with competing solvent extraction, cation, anion and sacrificial ion exchange mechanisms are all important, depending on the selection of components for formation of the ionic liquid phase, and that control of these competing mechanisms can be utilized to provide new, alternative separations schemes

  13. Radiation induced polymerization of MMA in imidazolium ionic liquids and their mixed solutions with organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Qi Mingying [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Wu Guozhong [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China)], E-mail: wuguozhong@sinap.ac.cn; Sha Maolin; Liu Yusheng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China)

    2008-10-15

    Considerably higher molecular weight (M{sub w}) and multi-modal molecular weight distribution (MWD) of poly(methyl methacrylate) (PMMA) were observed in neat ionic liquids ([bmim][PF{sub 6}] and [bmim][BF{sub 4}]), as well as their mixed solutions with organic solvents, probably due to the high viscosity and inhomogeneity of ionic liquids. FTIR spectra for PMMA showed that a slight amount of ionic liquid remained in the resulting polymer, and DSC measurement indicated the increase of glass transition point of PMMA with increasing of ionic liquid fraction in mixed solutions.

  14. Magnetic ionic liquids as non-conventional extraction solvents for the determination of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Trujillo-Rodríguez, María J; Nacham, Omprakash; Clark, Kevin D; Pino, Verónica; Anderson, Jared L; Ayala, Juan H; Afonso, Ana M

    2016-08-31

    This work describes the applicability of magnetic ionic liquids (MILs) in the analytical determination of a group of heavy polycyclic aromatic hydrocarbons. Three different MILs, namely, benzyltrioctylammonium bromotrichloroferrate (III) (MIL A), methoxybenzyltrioctylammonium bromotrichloroferrate (III) (MIL B), and 1,12-di(3-benzylbenzimidazolium) dodecane bis[(trifluoromethyl)sulfonyl)]imide bromotrichloroferrate (III) (MIL C), were designed to exhibit hydrophobic properties, and their performance examined in a microextraction method for hydrophobic analytes. The magnet-assisted approach with these MILs was performed in combination with high performance liquid chromatography and fluorescence detection. The study of the extraction performance showed that MIL A was the most suitable solvent for the extraction of polycyclic aromatic hydrocarbons and under optimum conditions the fast extraction step required ∼20 μL of MIL A for 10 mL of aqueous sample, 24 mmol L(-1) NaOH, high ionic strength content of NaCl (25% (w/v)), 500 μL of acetone as dispersive solvent, and 5 min of vortex. The desorption step required the aid of an external magnetic field with a strong NdFeB magnet (the separation requires few seconds), two back-extraction steps for polycyclic aromatic hydrocarbons retained in the MIL droplet with n-hexane, evaporation and reconstitution with acetonitrile. The overall method presented limits of detection down to 5 ng L(-1), relative recoveries ranging from 91.5 to 119%, and inter-day reproducibility values (expressed as relative standard derivation) lower than 16.4% for a spiked level of 0.4 μg L(-1) (n = 9). The method was also applied for the analysis of real samples, including tap water, wastewater, and tea infusion. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Investigating the solvent and temperature effects on the cyclohexadienyl radical in an ionic liquid

    International Nuclear Information System (INIS)

    Taylor, Becky; Cormier, P.J.; Lauzon, J.M.; Ghandi, Khashayar

    2009-01-01

    The cyclohexadienyl radical was studied in a novel green solvent; tetradecyl (trihexyl) phosphonium chloride ionic liquid (IL 101). Both the solvent effects and how the hyperfine coupling changes with respect to temperature have been examined and compared to literature. This was done through experimental muon techniques at the TRIUMF National Laboratory in Canada as well as through ab initio calculations. The ionic liquid solvent effects were found to be consistent with other solvents, when assuming ionic liquids to be a combination of ion pairs. In ionic liquid the hyperfine coupling constants of the proton and reduced muon decreased linearly with increasing temperature. The analysis showed that the majority of this relationship is due to a vibrational effect, although the solvent density plays a role too. The temperature effect on the entropy of the system was determined to be negligible. The temperature coefficient of the reduced muon hyperfine coupling was larger than that of the proton in IL 101 due to the effects of nearby ionic liquid molecules.

  16. Investigating the solvent and temperature effects on the cyclohexadienyl radical in an ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Becky; Cormier, P.J.; Lauzon, J.M. [Department of Chemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G3 (Canada); Ghandi, Khashayar, E-mail: kghandi@mta.c [Department of Chemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G3 (Canada)

    2009-04-15

    The cyclohexadienyl radical was studied in a novel green solvent; tetradecyl (trihexyl) phosphonium chloride ionic liquid (IL 101). Both the solvent effects and how the hyperfine coupling changes with respect to temperature have been examined and compared to literature. This was done through experimental muon techniques at the TRIUMF National Laboratory in Canada as well as through ab initio calculations. The ionic liquid solvent effects were found to be consistent with other solvents, when assuming ionic liquids to be a combination of ion pairs. In ionic liquid the hyperfine coupling constants of the proton and reduced muon decreased linearly with increasing temperature. The analysis showed that the majority of this relationship is due to a vibrational effect, although the solvent density plays a role too. The temperature effect on the entropy of the system was determined to be negligible. The temperature coefficient of the reduced muon hyperfine coupling was larger than that of the proton in IL 101 due to the effects of nearby ionic liquid molecules.

  17. Recent Advances in Anhydrous Solvents for CO{sub 2} Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

    Energy Technology Data Exchange (ETDEWEB)

    Park, Youngjune [School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju (Korea, Republic of); Lin, Kun-Yi Andrew [Department of Environmental Engineering, National Chung Hsing University, Taichung City (China); Park, Ah-Hyung Alissa, E-mail: ap2622@columbia.edu [Department of Earth and Environmental Engineering, Lenfest Center for Sustainable Energy, Columbia University, New York, NY (United States); Department of Chemical Engineering, Lenfest Center for Sustainable Energy, Columbia University, New York, NY (United States); Petit, Camille, E-mail: ap2622@columbia.edu [Department of Chemical Engineering, Imperial College London, London (United Kingdom)

    2015-10-01

    CO{sub 2} capture by amine scrubbing, which has a high CO{sub 2} capture capacity and a rapid reaction rate, is the most employed and investigated approach to date. There are a number of recent large-scale demonstrations including the Boundary Dam Carbon Capture Project by SaskPower in Canada that have reported successful implementations of aqueous amine solvent in CO{sub 2} capture from flue gases. The findings from these demonstrations will significantly advance the field of CO{sub 2} capture in the coming years. While the latest efforts in aqueous amine solvents are exciting and promising, there are still several drawbacks to amine-based CO{sub 2} capture solvents including high volatility and corrosiveness of the amine solutions as well as the high parasitic energy penalty during the solvent regeneration step. Thus, in a parallel effort, alternative CO{sub 2} capture solvents, which are often anhydrous, have been developed as the third-generation CO{sub 2} capture solvents. These novel classes of liquid materials include ionic liquids, CO{sub 2}-triggered switchable solvents (i.e., CO{sub 2}-binding organic liquids, reversible ionic liquids), and nanoparticle organic hybrid materials. This paper provides a review of these various anhydrous solvents and their potential for CO{sub 2} capture. Particular attention is given to the mechanisms of CO{sub 2} absorption in these solvents, their regeneration and their processability – especially taking into account their viscosity. While not intended to provide a complete coverage of the existing literature, this review aims at pointing the major findings reported for these new classes of CO{sub 2} capture media.

  18. Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

    Directory of Open Access Journals (Sweden)

    YOUNGJUNE ePARK

    2015-10-01

    Full Text Available CO2 capture by amine scrubbing, which has a high CO2 capture capacity and a rapid reaction rate, is the most employed and investigated approach to date. There are a number of recent large-scale demonstrations including the Boundary Dam Carbon Capture Project by SaskPower in Canada that have reported successful implementations of aqueous amine solvent in CO2 capture from flue gases. The findings from these demonstrations will significantly advance the field of CO2 capture in the coming years. While the latest efforts in aqueous amine solvents are exciting and promising, there are still several drawbacks to amine-based CO2 capture solvents including high volatility and corrosiveness of the amine solutions, as well as the high parasitic energy penalty during the solvent regeneration step. Thus, in a parallel effort, alternative CO2 capture solvents, which are often anhydrous, have been developed as the third-generation CO2 capture solvents. These novel classes of liquid materials include: Ionic Liquids (ILs, CO2-triggered switchable solvents (i.e., CO2 Binding Organic Liquids (CO2BOLs, Reversible Ionic Liquids (RevILs, and Nanoparticle Organic Hybrid Materials (NOHMs. This paper provides a review of these various anhydrous solvents and their potential for CO2 capture. Particular attention is given to the mechanisms of CO2 absorption in these solvents, their regeneration and their processability – especially taking into account their viscosity. While not intended to provide a complete coverage of the existing literature, this review aims at pointing the major findings reported for these new classes of CO2 capture media.

  19. Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

    International Nuclear Information System (INIS)

    Park, Youngjune; Lin, Kun-Yi Andrew; Park, Ah-Hyung Alissa; Petit, Camille

    2015-01-01

    CO 2 capture by amine scrubbing, which has a high CO 2 capture capacity and a rapid reaction rate, is the most employed and investigated approach to date. There are a number of recent large-scale demonstrations including the Boundary Dam Carbon Capture Project by SaskPower in Canada that have reported successful implementations of aqueous amine solvent in CO 2 capture from flue gases. The findings from these demonstrations will significantly advance the field of CO 2 capture in the coming years. While the latest efforts in aqueous amine solvents are exciting and promising, there are still several drawbacks to amine-based CO 2 capture solvents including high volatility and corrosiveness of the amine solutions as well as the high parasitic energy penalty during the solvent regeneration step. Thus, in a parallel effort, alternative CO 2 capture solvents, which are often anhydrous, have been developed as the third-generation CO 2 capture solvents. These novel classes of liquid materials include ionic liquids, CO 2 -triggered switchable solvents (i.e., CO 2 -binding organic liquids, reversible ionic liquids), and nanoparticle organic hybrid materials. This paper provides a review of these various anhydrous solvents and their potential for CO 2 capture. Particular attention is given to the mechanisms of CO 2 absorption in these solvents, their regeneration and their processability – especially taking into account their viscosity. While not intended to provide a complete coverage of the existing literature, this review aims at pointing the major findings reported for these new classes of CO 2 capture media.

  20. The Solvent Selection framework: solvents for organic synthesis, separation processes and ionic-organic synthesis

    DEFF Research Database (Denmark)

    Mitrofanov, Igor; Sansonetti, Sascha; Abildskov, Jens

    2012-01-01

    This paper presents a systematic integrated framework for solvent selection and solvent design. The framework is divided into several modules, which can tackle specific problems in various solvent-based applications. In particular, three modules corresponding to the following solvent selection pr...

  1. Ionic Liquids Beyond Simple Solvents: Glimpses at the State of the Art in Organic Chemistry.

    Science.gov (United States)

    Kuchenbuch, Andrea; Giernoth, Ralf

    2015-12-01

    Within the last 25 years ionic liquids have written a tremendous success story, which is documented in a nearly uncountable amount of original research papers, reviews, and numerous applications in research and industry. These days, ionic liquids can be considered as a mature class of compounds for many different applications. Frequently, they are used as neoteric solvents for chemical tansformations, and the number of reviews on this field of research is huge. In this focused review, though, we are trying to evaluate the state of the art of ionic liquid chemistry beyond using them simply as solvents for chemical transformations. It is not meant to be a comprehensive overview on the topic; the choice of emphasis and examples rather refects the authors' personal view on the field. We are especially highlighting fields in which we believe the most fundamental developments within the next five years will take place: biomass processing, (chiral) ionic liquids from natural sources, biotransformations, and organic synthesis.

  2. The effect of varying the anion of an ionic liquid on the solvent effects on a nucleophilic aromatic substitution reaction.

    Science.gov (United States)

    Hawker, Rebecca R; Haines, Ronald S; Harper, Jason B

    2018-05-09

    A variety of ionic liquids, each containing the same cation but a different anion, were examined as solvents for a nucleophilic aromatic substitution reaction. Varying the proportion of ionic liquid was found to increase the rate constant as the mole fraction of ionic liquid increased demonstrating that the reaction outcome could be controlled through varying the ionic liquid. The solvent effects were correlated with the hydrogen bond accepting ability (β) of the ionic liquid anion allowing for qualitative prediction of the effect of changing this component of the solute. To determine the microscopic origins of the solvent effects, activation parameters were determined through temperature-dependent kinetic analyses and shown to be consistent with previous studies. With the knowledge of the microscopic interactions in solution, an ionic liquid was rationally chosen to maximise rate enhancement demonstrating that an ionic solvent can be selected to control reaction outcome for this reaction type.

  3. Imidazolium ionic liquids as solvents for cerium(IV)-mediated oxidation reactions

    OpenAIRE

    Mehdi, Hasan; Bodor, Andrea; Lantos, Diana; Horváth, István T; De Vos, Dirk; Binnemans, Koen

    2007-01-01

    Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Ca...

  4. Ionic liquids as alternative solvents for aromatics extraction

    NARCIS (Netherlands)

    Hansmeier, A.R.

    2010-01-01

    The objective of this thesis was the development of an extraction process for the removal of multiple aromatics from several petrochemical streams by means of an ionic liquid. Due to environmental legislation, the demand of ‘clean’ fuels is increasing and most likely will increase even more towards

  5. Oxidative Desulfurization of Gasoline by Ionic Liquids Coupled with Extraction by Organic Solvents

    OpenAIRE

    Abro, Rashid; Gao, Shurong; Chen, Xiaochun; Yu, Guangren; Abdeltawab, Ahmed A.; Al-Deyab, Salem S.

    2016-01-01

    In this work, desulfurization of real fluidized catalytic cracking (FCC) gasoline was investigated in dual steps; first in oxidative desulfurization (ODS) using imidazolium and pyrrolidonium based Brønsted acidic ionic liquids (ILs) as solvent and catalyst and hydrogen peroxide as oxidant. In second step, extractive desulfurization took place using organic solvents of furfural, furfural alcohol and ethylene glycol. Variety of factors such as temperature, time, mass ratio of oil/ILs and regene...

  6. TOUGHREACT Testing in High Ionic Strength Brine Sandstone Systems

    International Nuclear Information System (INIS)

    Xu, Tianfu

    2008-01-01

    Deep saline formations and oil and gas reservoirs often contain concentrated brine solutions of ionic strength greater than 1 (I > 1 M). Geochemical modeling, involving high ionic strength brines, is a challenge. In the original TOUGHREACT code (Xu et al., 2004; Xu et al., 2006), activity coefficients of charged aqueous species are computed using an extended Debye-Huckel (DH) equation and parameters derived by Helgeson et al. (1981). The DH model can deal with ionic strengths from dilute to moderately saline water (up to 6 molal for an NaCl-dominant solution). The equations implemented for the DH model are presented in Appendix A. During the course of the Yucca Mountain project, a Pitzer ion-interaction model was implemented into TOUGHREACT. This allows the application of this simulator to problems involving much more concentrated aqueous solutions, such as those involving geochemical processes in and around high-level nuclear waste repositories where fluid evaporation and/or boiling is expected to occur (Zhang et al., 2007). The Pitzer ion-interaction model, which we refer to as the Pitzer virial approach, and associated ion-interaction parameters have been applied successfully to study non-ideal concentrated aqueous solutions. The formulation of the Pitzer model is presented in Appendix B; detailed information can be founded in Zhang et al. (2007). For CO 2 geological sequestration, the Pitzer ion-interaction model for highly concentrated brines was incorporated into TOUGHREACT/ECO2N, then was tested and compared with a previously implemented extended Debye-Hueckel (DH) ion activity model. The comparison was made through a batch geochemical system using a Gulf Coast sandstone saline formation

  7. Tetraphenylborate Solubility in High Ionic Strength Salt Solutions

    International Nuclear Information System (INIS)

    Serkiz, S.M.; Ginn, J.D.; Jurgensen, A.R.

    1998-04-01

    Solubility of sodium and potassium salts of the tetraphenylborate ion (TPB) in simulated Savannah River Site High Level Waste was investigated. Data generated from this study allow more accurate predictions of TPB solubility at the In-Tank Precipitation (ITP) facility. Because previous research showed large deviations in the observed solubility of TPB salts when compared with model predictions, additional data were generated to better understand the solubility of TPB in more complex systems of high ionic strength and those containing both potassium and sodium. These data allow evaluation of the ability of current models to accurately predict equilibrium TPB concentrations over the range of experimental conditions investigated in this study

  8. Green oxidation of alkenes in ionic liquid solvent by hydrogen

    Indian Academy of Sciences (India)

    Additionally, ion liquid solvent efficiently improved all the catalytic performances. Finally, the reaction was extended to different alkenes using the heterogeneous complex 2-L4. Among all the alkenes, those containing -electron-withdrawing groups and trans-orientations exhibited lower tendency for oxidation.

  9. Anomalous Capacitance Maximum of the Glassy Carbon-Ionic Liquid Interface through Dilution with Organic Solvents.

    Science.gov (United States)

    Bozym, David J; Uralcan, Betül; Limmer, David T; Pope, Michael A; Szamreta, Nicholas J; Debenedetti, Pablo G; Aksay, Ilhan A

    2015-07-02

    We use electrochemical impedance spectroscopy to measure the effect of diluting a hydrophobic room temperature ionic liquid with miscible organic solvents on the differential capacitance of the glassy carbon-electrolyte interface. We show that the minimum differential capacitance increases with dilution and reaches a maximum value at ionic liquid contents near 5-10 mol% (i.e., ∼1 M). We provide evidence that mixtures with 1,2-dichloroethane, a low-dielectric constant solvent, yield the largest gains in capacitance near the open circuit potential when compared against two traditional solvents, acetonitrile and propylene carbonate. To provide a fundamental basis for these observations, we use a coarse-grained model to relate structural variations at the double layer to the occurrence of the maximum. Our results reveal the potential for the enhancement of double-layer capacitance through dilution.

  10. Ionic liquids as solvents for Čerenkov counting and the effect of a wavelength shifter.

    Science.gov (United States)

    Mirenda, M; Rodrigues, D; Ferreyra, C; Arenillas, P; Sarmiento, G P; Krimer, N; Japas, M L

    2018-04-01

    We study the wavelength shift of the Čerenkov light - generated in the ionic liquid (BMIMCl) - caused by the addition of the highly fluorescent ionic liquid (BMIMHPTS). 18 F and 32 P efficiencies increases up to 124% and 14%, respectively, compared with the values obtained with pure BMIMCl. With this improvement, ionic liquid mixtures become a good alternative - when using the TDCR-Cherenkov technique - to standardize radionuclides having electron emissions energies close to the threshold energy in water (∼ 260keV). As an advantage compared with other solvents, the Ionic liquid mixture can be reused, in the case of short-lived radionuclides, by simply removing all water content in a vacuum oven. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Optical, photo-physical properties and photostability of pyrromethene (PM-597) in ionic liquids as benign green-solvents

    International Nuclear Information System (INIS)

    AL-Aqmar, Dalal M.; Abdelkader, H.I.; Abou Kana, Maram T.H.

    2015-01-01

    Laser dye pyrromethene-597 was dissolved with different concentrations in three types of ionic liquids (ILs): 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl 4 ) and 1-butyl-3-methylimidazolium tetrafluoro-borate (BMIM BF 4 ) in addition to ethanol as reference solvent. This paper investigates optical spectra and some photo-physical parameters of PM-597 in BMIM Cl, BMIM AlCl 4 , BMIM BF 4 and ethanol. These parameters are absorption and emission cross sections, fluorescence lifetime and quantum yield. The amplified spontaneous emission (ASE) was studied using the second harmonic Nd-YAG laser of 532 nm. Also, the gain and energy conversion efficiencies were investigated. Relatively high efficiency was obtained with good photostability in case of PM-597 in BMIM BF 4 that was a decrease to ~90% of the initial amplified spontaneous emission. This output energy was observed after pumping by 75,000 shots at a relatively high repetition rate of 10 Hz and pumping energy of 37 mJ. The composition and properties of the matrix of ILs were found to lead to optimize the laser performance and photostability of the investigated laser dye. In this study, we considered ionic liquids as the environmentally benign green solvents in place of volatile toxic organic solvents. - Highlights: • Pyrromethen-597 as laser dye was dissolved in three types of ionic liquids (ILs): BMIM Cl, BMIM AlCl 4 and BMIM BF 4 as benign green-solvent in addition to ethanol as reference solvent. • Important spectroscopic properties of PM-597 dye such as quantum yield, fluorescence lifetime, radiative and nonradiative rate, transition dipole moment, attenuation length and oscillator strength were affected by changing the host material. • The dye laser gain, quantum yield, peak intensity of ASE and photostability were found to be better in BMIM BF 4 than in BMIM Cl and in ethanol. • ILs may be used as ideal hosts for dye laser systems to

  12. Optical, photo-physical properties and photostability of pyrromethene (PM-597) in ionic liquids as benign green-solvents

    Energy Technology Data Exchange (ETDEWEB)

    AL-Aqmar, Dalal M. [Physics Department, Ibb University, Ibb (Yemen); Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Abdelkader, H.I. [Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Abou Kana, Maram T.H., E-mail: mabou202@niles.edu.eg [National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt)

    2015-05-15

    Laser dye pyrromethene-597 was dissolved with different concentrations in three types of ionic liquids (ILs): 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl{sub 4}) and 1-butyl-3-methylimidazolium tetrafluoro-borate (BMIM BF{sub 4}) in addition to ethanol as reference solvent. This paper investigates optical spectra and some photo-physical parameters of PM-597 in BMIM Cl, BMIM AlCl{sub 4}, BMIM BF{sub 4} and ethanol. These parameters are absorption and emission cross sections, fluorescence lifetime and quantum yield. The amplified spontaneous emission (ASE) was studied using the second harmonic Nd-YAG laser of 532 nm. Also, the gain and energy conversion efficiencies were investigated. Relatively high efficiency was obtained with good photostability in case of PM-597 in BMIM BF{sub 4} that was a decrease to ~90% of the initial amplified spontaneous emission. This output energy was observed after pumping by 75,000 shots at a relatively high repetition rate of 10 Hz and pumping energy of 37 mJ. The composition and properties of the matrix of ILs were found to lead to optimize the laser performance and photostability of the investigated laser dye. In this study, we considered ionic liquids as the environmentally benign green solvents in place of volatile toxic organic solvents. - Highlights: • Pyrromethen-597 as laser dye was dissolved in three types of ionic liquids (ILs): BMIM Cl, BMIM AlCl{sub 4} and BMIM BF{sub 4} as benign green-solvent in addition to ethanol as reference solvent. • Important spectroscopic properties of PM-597 dye such as quantum yield, fluorescence lifetime, radiative and nonradiative rate, transition dipole moment, attenuation length and oscillator strength were affected by changing the host material. • The dye laser gain, quantum yield, peak intensity of ASE and photostability were found to be better in BMIM BF{sub 4} than in BMIM Cl and in ethanol. • ILs may be used as ideal

  13. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    Science.gov (United States)

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions.

  14. Complexation of vanadium (v) with alanine in different ionic strength

    International Nuclear Information System (INIS)

    Garib, F.; Zare, K.; Fekri, H

    2002-01-01

    The formation constants of species formed in the system H ++ alanine and VO 2 + alanine have be determined in aqueous solution for 1.0 3 NaCIO 4 ,using a combination of pramiracetam and spectrophotometric techniques. The compositions of the formed complexes and their stability constants were determined ny curve fitting method and it was shown that di oxovanadium(V) forms two mononuclear 1:1 and 1:2 species with alanine of the type VO 2 L and VO 2 L 2 The protonation constant of the amino group of alanine has been determined using a computer program which employ a least-squares method. The defence of the protonation of alanine and the stability constant of the species on ionic strength are described by a Debby-huckel type equation

  15. Determination of the first hydrolysis constant of Europium (III) in 3 M of ionic strength

    International Nuclear Information System (INIS)

    Ramirez B, M.E.

    1994-01-01

    The first hydrolysis constant of Eu 3+ has been determined at 303 K and 3 M (NaCl) ionic strength. A solvent extraction method was used, the extractant was dibenzoylmethane in benzene and di glycolate anion in the aqueous phase provided competitive complexation. The tracer solution was 152m1 Eu (III) in water. The radioactive solution of europium was obtained by neutron irradiation of europium nitrate solutions at pH 3.0, in a TRIGA Mark III nuclear reactor at a neutron flux of 1 x 10 13 cm -2 s -1 . The half life of the produced isotope, 152m1 Eu (9.3 h), was verified by means of a Ge H detector and no interfering radiations were observed in the spectra. (Author)

  16. The A Priori Design and Selection of Ionic Liquids as Solvents for Active Pharmaceutical Ingredients

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Weber, Cameron C.; Rogers, Robin D.

    2017-01-01

    In this paper we derive a straightforward computational approach to predict the optimal ionic liquid (IL) solvent for a given compound, based on COSMO-RS calculations. These calculations were performed on 18 different active pharmaceutical ingredients (APIs) using a matrix of 210 hypothetical ILs...... on the N-alkylguanidinium cation were prepared and characterized. The solubility of the APIs in each of these classes was found to be qualitatively consistent with the predictions of the COSMO-RS model. The suitability of these novel guanidinium salts as crystallization solvents was demonstrated by the use...

  17. Enzymatic Synthesis of Esculin Ester in Ionic Liquids Buffered with Organic Solvents

    DEFF Research Database (Denmark)

    Hu, Yifan; Guo, Zheng; Lue, Bena-Marie

    2009-01-01

    The enzymatic esterification of esculin catalyzed by Candida antarctica lipase B (Novozym 435) was carried out in ionic liquid (IL)-organic solvent mixed systems in comparison with individual systems. The reaction behaviors in IL-organic solvents were systemically evaluated using acetone as a model...... in IL-acetone mixtures made it possible to improve the solubility of esculin while the effects of ILs on lipase activity were minimized. Following the benignity of ILs to lipase activity, the anions of ILs were ranked in the order as [Tf2N](-) > [PF6](-) > [BF4](-) > [CF3SO3](-) > [C4F9SO3](-) > [TAF...

  18. Strong impact of ionic strength on the kinetics of fibrilar aggregation of bovine beta-lactoglobulin

    NARCIS (Netherlands)

    Arnaudov, L.N.; Vries, de R.J.

    2006-01-01

    We investigate the effect of ionic strength on the kinetics of heat-induced fibrilar aggregation of bovine -lactoglobulin at pH 2.0. Using in situ light scattering we find an apparent critical protein concentration below which there is no significant fibril formation for all ionic strengths studied.

  19. SN2 fluorination reactions in ionic liquids: a mechanistic study towards solvent engineering.

    Science.gov (United States)

    Oh, Young-Ho; Jang, Hyeong Bin; Im, Suk; Song, Myoung Jong; Kim, So-Yeon; Park, Sung-Woo; Chi, Dae Yoon; Song, Choong Eui; Lee, Sungyul

    2011-01-21

    In the catalysis of S(N)2 fluorination reactions, the ionic liquid anion plays a key role as a Lewis base by binding to the counterion Cs(+) and thereby reducing the retarding Coulombic influence of Cs(+) on the nucleophile F(-). The reaction rates also depend critically on the structures of ionic liquid cation, for example, n-butyl imidazolium gives no S(N)2 products, whereas n-butylmethyl imidazolium works well. The origin of the observed phenomenal synergetic effects by the ionic liquid [mim-(t)OH][OMs], in which t-butanol is bonded covalently to the cation [mim], is that the t-butanol moiety binds to the leaving group of the substrate, moderating the retarding interactions between the acidic hydrogen and F(-). This work is a significant step toward designing and engineering solvents for promoting specific chemical reactions.

  20. The significance of water ionic strength on aluminium toxicity in brown trout (Salmo trutta L.)

    International Nuclear Information System (INIS)

    Alstad, Nina E.W.; Kjelsberg, Birgitte M.; Voellestad, L. Asbjoern; Lydersen, Espen; Poleo, Antonio B.S.

    2005-01-01

    The toxicity of aluminium to fish is related to interactions between aluminium and the gill surface. We investigated the possible effect of water ionic strength on this interaction. The mortality of brown trout (Salmo trutta L.) exposed to three different degrees of Al polymerisation was compared in water with increased ionic strength (mean 7.31 x 10 -4 M) after additions of the base cations Ca 2+ , Mg 2+ , Na + or K + , and in water with no such addition (mean ionic strength 5.58 x 10 -4 M). Only a very slight ameliorating effect of increased ionic strength was observed, while the degree of Al polymerisation was of major importance in fish mortality. In addition, it was observed that smaller fish survived the Al exposures for a longer time than larger fish. We hypothesise that this is because larger fish are more susceptible to hypoxia than smaller fish. - Ionic strength has a slight ameliorating effect on Al toxicity in brown trout

  1. A Diazonium Salt-Based Ionic Liquid for Solvent-FreeModification of Carbon.

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chengdu [ORNL; Huang, Jing-Fang [ORNL; Li, Zuojiang [ORNL; Luo, Huimin [ORNL; Dai, Sheng [ORNL

    2006-01-01

    A novel ionic liquid that consists of p-butylbenzenediazonium ions and bis(trifluoromethanesulfonyl)amidates (Tf{sub 2}N{sup -}) has been synthesized as a task-specific ionic liquid for the solvent-free modification of carbon materials. The use of anions Tf{sub 2}N{sup =} is the key to rendering the hydrophobicity, low liquidus temperature, and ionicity to this novel molten salt. This diazonium salt has a melting point of 7.2 C and a moderate electric conductivity of 527 {micro} s/cm at 25 C. The thermal stability of this diazonium ionic liquid has been investigated by high-resolution thermogravimetric analysis (HRTGA). The compound is stable up to about 90 C in nitrogen, which is only 10 C less than its solid tetrafluoroborate counterpart. The modification of carbon materials has been carried out through both thermal and electrochemical activations of diazonium ions to generate free radical intermediates without the use of any solvent. The surface-coverage loadings of 3.38 {micro} mol/m{sup 2} and 6.07 {micro} mol/m{sup 2} for covalently attached organic functionalities have been achieved by the thermally induced functionalization and electrochemically assisted reaction, respectively.

  2. Ionic Strength Is a Barrier to the Habitability of Mars.

    Science.gov (United States)

    Fox-Powell, Mark G; Hallsworth, John E; Cousins, Claire R; Cockell, Charles S

    2016-06-01

    The thermodynamic availability of water (water activity) strictly limits microbial propagation on Earth, particularly in hypersaline environments. A considerable body of evidence indicates the existence of hypersaline surface waters throughout the history of Mars; therefore it is assumed that, as on Earth, water activity is a major limiting factor for martian habitability. However, the differing geological histories of Earth and Mars have driven variations in their respective aqueous geochemistry, with as-yet-unknown implications for habitability. Using a microbial community enrichment approach, we investigated microbial habitability for a suite of simulated martian brines. While the habitability of some martian brines was consistent with predictions made from water activity, others were uninhabitable even when the water activity was biologically permissive. We demonstrate experimentally that high ionic strength, driven to extremes on Mars by the ubiquitous occurrence of multivalent ions, renders these environments uninhabitable despite the presence of biologically available water. These findings show how the respective geological histories of Earth and Mars, which have produced differences in the planets' dominant water chemistries, have resulted in different physicochemical extremes which define the boundary space for microbial habitability. Habitability-Mars-Salts-Water activity-Life in extreme environments. Astrobiology 16, 427-442.

  3. Silver nanoparticle aggregation not triggered by an ionic strength mechanism

    International Nuclear Information System (INIS)

    Botasini, Santiago; Méndez, Eduardo

    2013-01-01

    The synthesis of stable colloidal solutions of silver nanoparticles is a major goal in the industry to control their fate in aqueous solutions. The present work studies 10–20-nm silver nanoparticle aggregation triggered by the presence of chloride ions. The aggregation process was followed by UV–Vis–NIR spectroscopy and transmission electron microscopy. We found that the mechanism involved differs from the classic explanation of nanoparticle aggregation triggered by an increase in the ionic strength. Moreover, our results give evidence that even when nanoparticles are resistant to an increment of the total amount of ions, the formation of insoluble salts in the vicinity of the nanoparticle is enough to induce the aggregation. The presence of silver chloride around the silver nanoparticles was documented by an X-ray diffraction pattern and electrochemical methods because chloride anions are ubiquitous in real media; this alternative process jeopardized the development of many applications with silver nanoparticles that depend on the use of stable colloids.

  4. Silver nanoparticle aggregation not triggered by an ionic strength mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Botasini, Santiago; Mendez, Eduardo, E-mail: emendez@fcien.edu.uy [Instituto de Quimica Biologica, Universidad de la Republica, Laboratorio de Biomateriales (Uruguay)

    2013-04-15

    The synthesis of stable colloidal solutions of silver nanoparticles is a major goal in the industry to control their fate in aqueous solutions. The present work studies 10-20-nm silver nanoparticle aggregation triggered by the presence of chloride ions. The aggregation process was followed by UV-Vis-NIR spectroscopy and transmission electron microscopy. We found that the mechanism involved differs from the classic explanation of nanoparticle aggregation triggered by an increase in the ionic strength. Moreover, our results give evidence that even when nanoparticles are resistant to an increment of the total amount of ions, the formation of insoluble salts in the vicinity of the nanoparticle is enough to induce the aggregation. The presence of silver chloride around the silver nanoparticles was documented by an X-ray diffraction pattern and electrochemical methods because chloride anions are ubiquitous in real media; this alternative process jeopardized the development of many applications with silver nanoparticles that depend on the use of stable colloids.

  5. Ionic liquid solutions as extractive solvents for value-added compounds from biomass.

    Science.gov (United States)

    Passos, Helena; Freire, Mara G; Coutinho, João A P

    2014-12-01

    In the past few years, the number of studies regarding the application of ionic liquids (ILs) as alternative solvents to extract value-added compounds from biomass has been growing. Based on an extended compilation and analysis of the data hitherto reported, the main objective of this review is to provide an overview on the use of ILs and their mixtures with molecular solvents for the extraction of value-added compounds present in natural sources. The ILs (or IL solutions) investigated as solvents for the extraction of natural compounds, such as alkaloids, flavonoids, terpenoids, lipids, among others, are outlined. The extraction techniques employed, namely solid-liquid extraction, and microwave-assisted and ultrasound-assisted extractions, are emphasized and discussed in terms of extraction yields and purification factors. Furthermore, the evaluation of the IL chemical structure and the optimization of the process conditions (IL concentration, temperature, biomass-solvent ratio, etc.) are critically addressed. Major conclusions on the role of the ILs towards the extraction mechanisms and improved extraction yields are additionally provided. The isolation and recovery procedures of the value-added compounds are ascertained as well as some scattered strategies already reported for the IL solvent recovery and reusability. Finally, a critical analysis on the economic impact versus the extraction performance of IL-based methodologies was also carried out and is here presented and discussed.

  6. Ionic association and solvation of the ionic liquid 1-hexyl-3-methylimidazolium chloride in molecular solvents revealed by vapor pressure osmometry, conductometry, volumetry, and acoustic measurements.

    Science.gov (United States)

    Sadeghi, Rahmat; Ebrahimi, Nosaibah

    2011-11-17

    A systematic study of osmotic coefficient, conductivity, volumetric and acoustic properties of solutions of ionic liquid 1-hexyl-3-methylimidazolium chloride ([C(6)mim][Cl]) in various molecular solvents has been made at different temperatures in order to study of ionic association and solvation behavior of [C(6)mim][Cl] in different solutions. Precise measurements on electrical conductances of solutions of [C(6)mim][Cl] in water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and acetonitrile at 293.15, 298.15, and 303.15 K are reported and analyzed with Barthel's low-concentration chemical model (lcCM) to obtain the limiting molar conductivities and association constants of this ionic liquid in the investigated solvents. Strong ion pairing was found for the ionic liquid in 2-propanol, 1-butanol, and 1-propanol, whereas ion association in acetonitrile, methanol and ethanol is rather weak and in water the ionic liquid is fully dissociated. In the second part of this work, the apparent molar volumes and isentropic compressibilities of [C(6)mim][Cl] in water, methanol, ethanol, acetonitrile, 1-propanol, 2-propanol, and 1-butanol are obtained at the 288.15-313.15 K temperature range at 5 K intervals at atmospheric pressure from the precise measurements of density and sound velocity. The infinite dilution apparent molar volume and isentropic compressibility values of the free ions and ion pairs of [C(6)mim][Cl] in the investigated solvents as well as the excess molar volume of the investigated solutions are determined and their variations with temperature and type of solvents are also studied. Finally, the experimental measurements of osmotic coefficient at 318.15 K for binary solutions of [C(6)mim][Cl] in water, methanol, ethanol, 2-propanol, and acetonitrile are taken using the vapor pressure osmometry (VPO) method and from which the values of the solvent activity, vapor pressure, activity coefficients, and Gibbs free energies are calculated. The results are

  7. The impact of water content and ionic diffusion on the uniaxial compressive strength of shale

    Directory of Open Access Journals (Sweden)

    Talal AL-Bazali

    2013-12-01

    Finally, the impact of ionic diffusion on the compressive strength of shale was carried out in the absence of both chemical osmosis and capillary forces. Results show that the invasion of sodium and calcium ions into shale reduced its compressive strength considerably while the invasion of potassium ions enhanced its compressive strength.

  8. Ionic Strength Differentially Affects the Bioavailability of Neutral and Negatively Charged Inorganic Hg Complexes.

    Science.gov (United States)

    Stenzler, Benjamin; Hinz, Aaron; Ruuskanen, Matti; Poulain, Alexandre J

    2017-09-05

    Mercury (Hg) bioavailability to bacteria in marine systems is the first step toward its bioamplification in food webs. These systems exhibit high salinity and ionic strength that will both alter Hg speciation and properties of the bacteria cell walls. The role of Hg speciation on Hg bioavailability in marine systems has not been teased apart from that of ionic strength on cell wall properties, however. We developed and optimized a whole-cell Hg bioreporter capable of functioning under aerobic and anaerobic conditions and exhibiting no physiological limitations of signal production to changes in ionic strength. We show that ionic strength controls the bioavailability of Hg species, regardless of their charge, possibly by altering properties of the bacterial cell wall. The unexpected anaerobic bioavailability of negatively charged halocomplexes may help explain Hg methylation in marine systems such as the oxygen-deficient zone in the oceanic water column, sea ice or polar snow.

  9. Synthesis and characterization of solvent-free ionic molybdenum disulphide (MoS2) nanofluids

    International Nuclear Information System (INIS)

    Gu, Shu-Ying; Gao, Xie-Feng; Zhang, Yi-Han

    2015-01-01

    A development of the novel and stable solvent-free ionic MoS 2 nanofluids by a facile and scalable hydrothermal method is presented. The nanofluids were synthesized by surface functionalizing nanoscale MoS 2 from hydrothermal synthesis with a charged corona, and ionically tethering with oligomeric chains as a canopy. The structures and properties of the nanofluids were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR, 1 H), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA) and ARES rheometer. The obtained solvent-free nanofluids are homogeneous, stable amber-like fluids with no evidence of phase separation. The nanofluids could be easily dispersed in both aqueous and organic solvents to form transparent and stable liquids due to the ionic nature and the presence of oligomeric polymer chains. It was found that the solvent-free nanofluids with up to 32 wt% inorganic content show Newtonian rheological behaviors due to the high graft density and uniform dispersion of inorganic cores, indicating that the nanofluids would have a stable lubricating performance. As reported in our previous communication, the nanofluids showing lower, more stable friction coefficients of less than 0.1 with self-healing lubricating behaviors. For deeper understanding of the nanofluids, the details of synthesis, chemical structures, rheological behaviors and molecular dynamics of the nanofluids were investigated in details. The rheological behaviors can be tailored by varying the grafting density of the canopy. Dynamic results of the canopy of the MoS 2 nanofluids show that inorganic MoS 2 cores have hindrance effect on the canopy segmental motions above 253 K due to their effect to the mobility of anions and the departing-recombining motions between the paired cations and anions. - Highlights: • A development of the novel synthesis of solvent-free MoS 2 nanofluids is presented. • The rheological behaviors can be tailored by

  10. Synthesis and characterization of solvent-free ionic molybdenum disulphide (MoS{sub 2}) nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Shu-Ying, E-mail: gushuying@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Gao, Xie-Feng; Zhang, Yi-Han [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China)

    2015-01-15

    A development of the novel and stable solvent-free ionic MoS{sub 2} nanofluids by a facile and scalable hydrothermal method is presented. The nanofluids were synthesized by surface functionalizing nanoscale MoS{sub 2} from hydrothermal synthesis with a charged corona, and ionically tethering with oligomeric chains as a canopy. The structures and properties of the nanofluids were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR, {sup 1}H), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA) and ARES rheometer. The obtained solvent-free nanofluids are homogeneous, stable amber-like fluids with no evidence of phase separation. The nanofluids could be easily dispersed in both aqueous and organic solvents to form transparent and stable liquids due to the ionic nature and the presence of oligomeric polymer chains. It was found that the solvent-free nanofluids with up to 32 wt% inorganic content show Newtonian rheological behaviors due to the high graft density and uniform dispersion of inorganic cores, indicating that the nanofluids would have a stable lubricating performance. As reported in our previous communication, the nanofluids showing lower, more stable friction coefficients of less than 0.1 with self-healing lubricating behaviors. For deeper understanding of the nanofluids, the details of synthesis, chemical structures, rheological behaviors and molecular dynamics of the nanofluids were investigated in details. The rheological behaviors can be tailored by varying the grafting density of the canopy. Dynamic results of the canopy of the MoS{sub 2} nanofluids show that inorganic MoS{sub 2} cores have hindrance effect on the canopy segmental motions above 253 K due to their effect to the mobility of anions and the departing-recombining motions between the paired cations and anions. - Highlights: • A development of the novel synthesis of solvent-free MoS{sub 2} nanofluids is presented. • The rheological

  11. Communication: Potentials of mean force study of ionic liquid ion pair aggregation in polar covalent molecule solvents

    Science.gov (United States)

    Bandlamudi, Santosh Rathan Paul; Benjamin, Kenneth M.

    2018-05-01

    Molecular dynamics (MD) simulations were conducted for 1-ethyl-3-methylimidazolium methylsulfate [EMIM][MeSO4] dissolved in six polar covalent molecules [acetic acid, acetone, chloroform, dimethyl sulfoxide (DMSO), isopropyl alcohol, and methanol] to understand the free energies of ionic liquid (IL) ion pairing/aggregation in the limit of infinite dilution. Free energy landscapes or potentials of mean force (PMF) were computed using umbrella sampling and the weighted histogram analysis method. The PMF studies showed the strongest IL ion pairing in chloroform, and the strength of IL ion pairing decreases in the order of chloroform, acetone, propanol, acetic acid, DMSO, and methanol. In the limit of infinite dilution, the free energy curves for IL ion aggregation in co-solvents were characterized by two distinct minima [global (˜3.6 Å) and local (˜5.7 Å)], while free energy values at these minima differed significantly for IL in each co-solvent. The PMF studies were extended for determining the free energy of IL ion aggregation as a function of concentration of methanol. Studies showed that as the concentration of methanol increased, the free energy of ion aggregation decreased, suggesting greater ion pair stability, in agreement with previously reported MD clustering and radial distribution function data.

  12. Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance

    Science.gov (United States)

    Pilkington, Georgia A.; Harris, Kathryn; Bergendal, Erik; Reddy, Akepati Bhaskar; Palsson, Gunnar K.; Vorobiev, Alexei; Antzutkin, Oleg. N.; Glavatskih, Sergei; Rutland, Mark W.

    2018-05-01

    Using neutron reflectivity, the electro-responsive structuring of the non-halogenated ionic liquid (IL) trihexyl(tetradecyl)phosphonium-bis(mandelato)borate, [P6,6,6,14][BMB], has been studied at a gold electrode surface in a polar solvent. For a 20% w/w IL mixture, contrast matched to the gold surface, distinct Kiessig fringes were observed for all potentials studied, indicative of a boundary layer of different composition to that of the bulk IL-solvent mixture. With applied potential, the amplitudes of the fringes from the gold-boundary layer interface varied systematically. These changes are attributable to the differing ratios of cations and anions in the boundary layer, leading to a greater or diminished contrast with the gold electrode, depending on the individual ion scattering length densities. Such electro-responsive changes were also evident in the reflectivities measured for the pure IL and a less concentrated (5% w/w) IL-solvent mixture at the same applied potentials, but gave rise to less pronounced changes. These measurements, therefore, demonstrate the enhanced sensitivity achieved by contrast matching the bulk solution and that the structure of the IL boundary layers formed in mixtures is strongly influenced by the bulk concentration. Together these results represent an important step in characterising IL boundary layers in IL-solvent mixtures and provide clear evidence of electro-responsive structuring of IL ions in their solutions with applied potential.

  13. Ionic strength-induced formation of smectite quasicrystals enhances nitroaromatic compound sorption.

    Science.gov (United States)

    Li, Hui; Pereira, Tanya R; Teppen, Brian J; Laird, David A; Johnston, Cliff T; Boyd, Stephen A

    2007-02-15

    Sorption of organic contaminants by soils is a determinant controlling their transport and fate in the environment. The influence of ionic strength on nitroaromatic compound sorption by K+- and Ca2+ -saturated smectite was examined. Sorption of 1,3-dinitrobenzene by K-smectite increased as KCl ionic strength increased from 0.01 to 0.30 M. In contrast, sorption by Ca-smectite at CaCl2 ionic strengths of 0.015 and 0.15 M remained essentially the same. The "salting-out" effect on the decrease of 1,3-dinitrobenzene aqueous solubility within this ionic strength range was smectite with increasing KCl ionic strength. X-ray diffraction patterns and light absorbance of K-clay suspensions indicated the aggregation of clay particles and the formation of quasicrystal structures as KCI ionic strength increased. Sorption enhancement is attributed to the formation of better-ordered K-clay quasicrystals with reduced interlayer distances rather than to the salting-out effect. Dehydration of 1,3-dinitrobenzene is apparently a significant driving force for sorption, and we show for the first time that sorption of small, planar, neutral organic molecules, namely, 1,3-dinitrobenzene, causes previously expanded clay interlayers to dehydrate and collapse in aqueous suspension.

  14. Sodium-calcium ion exchange on clay minerals at moderate to high ionic strengths

    International Nuclear Information System (INIS)

    Rogers, W.J.

    1979-12-01

    Sodium-calcium ion exchange on several clay minerals was studied at ionic strengths ranging from 0.01 to above 1.0. The minerals studied included attapulgite, illite, kaolin, and several montmorillonites. Distribution coefficients of calcium and sodium were obtained for the minerals over a wide range of solution conditions at pH five and equilibrium constants were calculated. The distribution coefficient of calcium, D/sub Ca/, was studied as a function of time, solution pH, loading, sodium concentration, and ionic strength fraction of sodium in constant ionic strength solutions. The distribution coefficient of sodium, D/sub Na/, was also studied as a function of time, loading, and sodium ionic strength fraction in constant total ionic strength solutions. Values of equilibrium constants calculated from distribution coefficients for solutions of constant ionic strength scattered bwteen 2 and 10 kg/kg for the montmorillonites and attapulgite while equilibrium constants for illite ranged from 5 to 10 kg/kg. No equilibrium constants for kaolin were calculated since distribution coefficients of sodium on this clay were too small to be measured. It was found that equilibrium constants at trace sodium loading were generally lower than those for higher sodium loadings by an order of magnitude or more due to the sensitivity of sodium distribution coefficients to the concentration of sodium in the clay at low loadings. Theoretical and experimental treatments of ion exclusion were included

  15. Effect of ionic strength on barium transport in porous media

    Science.gov (United States)

    Ye, Zi; Prigiobbe, Valentina

    2018-02-01

    Hydraulic fracturing (or fracking) is a well stimulation technique used to extract resources from a low permeability formation. Currently, the most common application of fracking is for the extraction of oil and gas from shale. During the operation, a large volume of brine, rich in hazardous chemicals, is produced. Spills of brine from wells or pits might negatively impact underground water resources and, in particular, one of the major concerns is the migration of radionuclides, such as radium (Ra2+), into the shallow subsurface. However, the transport behaviour of Ra2+ through a reactive porous medium under conditions typical of a brine, i.e., high salinity, is not well understood, yet. Here, a study on the transport behaviour of barium (Ba2+, congener of radium) through a porous medium containing a common mineral such as goethite (FeO(OH)) is presented. Batch and column flood tests were carried out at conditions resembling the produced brine, i.e., large values of ionic strength (I), namely, 1 to 3 mol/kg. The measurements were described with the triple layer surface complexation model coupled with the Pitzer activity coefficient method and a reactive transport model, in the case of the transport tests. The experimental results show that the adsorption of Ba2+ onto FeO(OH) increases with pH but decreases with I and it becomes negligible at the brine conditions. Moreover, even if isotherms show adsorption at large I, at the same conditions during transport, Ba2+ travels without retardation through the FeO(OH) porous medium. The triple layer model agrees very well with all batch data but it does not describe well the transport tests in all cases. In particular, the model cannot match the pH measurements at large I values. This suggests that the chemical reactions at the solid-liquid interface do not capture the mechanism of Ba2+ adsorption onto FeO(OH) at large salinity. Finally, this study suggests that barium, and potentially its congeners, namely, radium

  16. Lignin Structure and Aggregation Behavior in a Two-Component Ionic Liquid Solvent System

    Directory of Open Access Journals (Sweden)

    Susanne Bylin

    2014-08-01

    Full Text Available Ionic liquids are of potential interest in the processing of lignocellulosic biomass. In this study, the ionic liquid co-solvent system of 1-methylimidazole (MIM and 1-ethyl-3-methyl-imidazolium acetate (EMIMAc was used to solvate LignoBoost lignin fractionated from black liquor obtained from a kraft paper mill. Lignin ethanol-precipitated (LEP and ethanol-soluble (LES fractions were characterized via gel permeation chromatography (GPC and 13C- and 31P-nuclear magnetic resonance spectroscopy (NMR to determine structural characteristics and their relationship to polymer solubility in the system. Polymer integrity and solubility were optimal at ~20% lignin loading (w/w. Results showed that LEPs were generally of higher apparent molecular weight (Mw and enriched with condensed/aliphatic ether linkages and aliphatic hydroxyls. The LESs had a lower apparent Mw and were enriched with carboxylic and phenolic groups. This newly gained knowledge on lignin fractionation and aggregation in the present solvent system provides future opportunities for tuning fractionation/extraction to suit a specific biomass-derived product, e.g., carbon fibers.

  17. Activity and conformation of lysozyme in molecular solvents, protic ionic liquids (PILs) and salt-water systems.

    Science.gov (United States)

    Wijaya, Emmy C; Separovic, Frances; Drummond, Calum J; Greaves, Tamar L

    2016-09-21

    Improving protein stabilisation is important for the further development of many applications in the pharmaceutical, specialty chemical, consumer product and agricultural sectors. However, protein stabilization is highly dependent on the solvent environment and, hence, it is very complex to tailor protein-solvent combinations for stable protein maintenance. Understanding solvent features that govern protein stabilization will enable selection or design of suitable media with favourable solution environments to retain protein native conformation. In this work the structural conformation and activity of lysozyme in 29 solvent systems were investigated to determine the role of various solvent features on the stability of the enzyme. The solvent systems consisted of 19 low molecular weight polar solvents and 4 protic ionic liquids (PILs), both at different water content levels, and 6 aqueous salt solutions. Small angle X-ray scattering, Fourier transform infrared spectroscopy and UV-vis spectroscopy were used to investigate the tertiary and secondary structure of lysozyme along with the corresponding activity in various solvation systems. At low non-aqueous solvent concentrations (high water content), the presence of solvents and salts generally maintained lysozyme in its native structure and enhanced its activity. Due to the presence of a net surface charge on lysozyme, electrostatic interactions in PIL-water systems and salt solutions enhanced lysozyme activity more than the specific hydrogen-bond interactions present in non-ionic molecular solvents. At higher solvent concentrations (lower water content), solvents with a propensity to exhibit the solvophobic effect, analogous to the hydrophobic effect in water, retained lysozyme native conformation and activity. This solvophobic effect was observed particularly for solvents which contained hydroxyl moieties. Preferential solvophobic effects along with bulky chemical structures were postulated to result in less

  18. Evaluation of ionic liquids as solvent for aromatic extraction: Experimental, correlation and COSMO-RS predictions

    International Nuclear Information System (INIS)

    Calvar, Noelia; Domínguez, Irene; Gómez, Elena; Palomar, Jose; Domínguez, Ángeles

    2013-01-01

    Highlights: • BMimMSO 4 and BMimNTf 2 were studied as solvents to extract aromatic from aliphatic hydrocarbons. • Liquid + liquid equilibrium data were measured at 298.15 K and atmospheric pressure. • Selectivity and solute distribution ratio were obtained and compared with literature. • Experimental data were satisfactorily correlated using NRTL and UNIQUAC models. • COSMO-RS model was used as a predictive tool to describe the experimental LLE data for the studied ternary systems. -- Abstract: For the study of the separation of benzene or toluene from octane, nonane and cyclooctane, the ionic liquids 1-butyl-3-methylimidazolium methylsulfate, BMimMSO 4 , and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, BMimNTf 2 , were used as solvents. The (liquid + liquid) equilibria of the ternary systems {octane, or nonane, or (cyclooctane + benzene + BMimMSO 4 )}, and {(nonane + toluene + BMimMSO 4 ) or BMimNTf 2 } at T = 298.15 K were determined, and an analysis of the influence of the structure of each compound was carried out. Besides, the experimental data have been compared with literature data with sulfolane as solvent. The experimental results obtained have been correlated using NRTL and UNIQUAC models. Finally, COSMO-RS has been used to predict the (liquid + liquid) equilibrium of the systems studied. The differences between the predicted and experimental values were used to evaluate the ability of the COSMO-RS model to describe the impact of the structure of the alkane, aromatic and ionic liquid on the (liquid + liquid) equilibria

  19. Room-temperature solid phase ionic liquid (RTSPIL) coated Ω-transaminases: Development and application in organic solvents

    DEFF Research Database (Denmark)

    Grabner, B.; Nazario, M. A.; Gundersen, M. T.

    2018-01-01

    ω-Transaminases ATA-40, ATA-47 and ATA-82P were coated with room-temperature solid phase ionic liquids (RTSPILs) by means of three methods, melt coating, precipitation coating, and co‐lyophilization, and showed increased stability in all of the five tested organic solvents. Co‐lyophilization and ......ω-Transaminases ATA-40, ATA-47 and ATA-82P were coated with room-temperature solid phase ionic liquids (RTSPILs) by means of three methods, melt coating, precipitation coating, and co‐lyophilization, and showed increased stability in all of the five tested organic solvents. Co...

  20. A Selenium-Based Ionic Liquid as a Recyclable Solvent for the Catalyst-Free Synthesis of 3-Selenylindoles

    Directory of Open Access Journals (Sweden)

    Eder J. Lenardão

    2013-04-01

    Full Text Available The ionic liquid 1-butyl-3-methylimidazolium methylselenite, [bmim][SeO2(OCH3], was successfully used as solvent in the catalyst-free preparation of 3-arylselenylindoles by the reaction of indole with ArSeCl at room temperature. The products were obtained selectively in good yields without the need of any additive and the solvent was easily reused for several cycles with good results.

  1. Phase equilibria of didecyldimethylammonium nitrate ionic liquid with water and organic solvents

    International Nuclear Information System (INIS)

    Domanska, Urszula; Lugowska, Katarzyna; Pernak, Juliusz

    2007-01-01

    The phase diagrams for binary mixtures of an ammonium ionic liquid, didecyldimethylammonium nitrate, [DDA][NO 3 ], with: alcohols (propan-1-ol, butan-1-ol, octan-1-ol, and decan-1-ol): hydrocarbons (toluene, propylbenzene, hexane, and hexadecane) and with water were determined in our laboratory. The phase equilibria were measured by a dynamic method from T 220 K to either the melting point of the ionic liquid, or to the boiling point of the solvent. A simple liquidus curve in a eutectic system was observed for [DDA][NO 3 ] with: alcohols (propan-1-ol, butan-1-ol, and octan-1-ol); aromatic hydrocarbons (toluene and propylbenzene) and with water. (Solid + liquid) equilibria with immiscibility in the liquid phase were detected with the aliphatic hydrocarbons heptane and hexadecane and with decan-1-ol. (Liquid + liquid) equilibria for the system [DDA][NO 3 ] with hexadecane was observed for the whole mole fraction range of the ionic liquid. The observation of the upper critical solution temperature in binary mixtures of ([DDA][NO 3 ] + decan-1-ol, heptane, or hexadecane) was limited by the boiling temperature of the solvent. Characterisation and purity of the compounds were determined by elemental analysis, water content (Fisher method) and differential scanning microcalorimetry (d.s.c.) analysis. The d.s.c. method of analysis was used to determine melting temperatures and enthalpies of fusion. The thermal stability of the ionic liquid was resolved by the thermogravimetric technique-differential thermal analysis (TG-DTA) technique over a wide temperature range from (200 to 780) K. The thermal decomposition temperature of 50% of the sample was greater than 500 K. The (solid + liquid) phase equilibria, curves were correlated by means of different G Ex models utilizing parameters derived from the (solid + liquid) equilibrium. The root-mean-square deviations of the solubility temperatures for all calculated data are dependent upon the particular system and the particular

  2. Nanoparticle transport in water-unsaturated porous media: effects of solution ionic strength and flow rate

    International Nuclear Information System (INIS)

    Prédélus, Dieuseul; Lassabatere, Laurent; Louis, Cédric; Gehan, Hélène; Brichart, Thomas; Winiarski, Thierry; Angulo-Jaramillo, Rafael

    2017-01-01

    This paper presents the influence of ionic strength and flow on nanoparticle (NP) retention rate in an unsaturated calcareous medium, originating from a heterogeneous glaciofluvial deposit of the region of Lyon (France). Laboratory columns 10 cm in diameter and 30 cm in length were used. Silica nanoparticles (Au-SiO 2 -FluoNPs), with hydrodynamic diameter ranging from 50 to 60 nm and labeled with fluorescein derivatives, were used to simulate particle transport, and bromide was used to characterize flow. Three flow rates and five different ionic strengths were tested. The transfer model based on fractionation of water into mobile and immobile fractions was coupled with the attachment/detachment model to fit NPs breakthrough curves. The results show that increasing flow velocity induces a decrease in nanoparticle retention, probably as the result of several physical but also geochemical factors. The results show that NPs retention increases with ionic strength. However, an inversion of retention occurs for ionic strength >5.10 −2  M, which has been scarcely observed in previous studies. The measure of zeta potential and DLVO calculations show that NPs may sorb on both solid-water and air-water interfaces. NPs size distribution shows the potential for nanoparticle agglomeration mostly at low pH, leading to entrapment in the soil pores. These mechanisms are highly sensitive to both hydrodynamic and geochemical conditions, which explains their high sensitivity to flow rates and ionic strength.

  3. The significance of water ionic strength on aluminium toxicity in brown trout (Salmo trutta L.)

    Energy Technology Data Exchange (ETDEWEB)

    Alstad, Nina E.W. [Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo (Norway); Kjelsberg, Birgitte M. [Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo (Norway); Voellestad, L. Asbjoern [Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo (Norway); Lydersen, Espen [Norwegian Institute for Water Research, P.O. Box 173 Kjelsaas, N-0411 Oslo (Norway); Poleo, Antonio B.S. [Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo (Norway)]. E-mail: toni.poleo@bio.uio.no

    2005-01-01

    The toxicity of aluminium to fish is related to interactions between aluminium and the gill surface. We investigated the possible effect of water ionic strength on this interaction. The mortality of brown trout (Salmo trutta L.) exposed to three different degrees of Al polymerisation was compared in water with increased ionic strength (mean 7.31 x 10{sup -4} M) after additions of the base cations Ca{sup 2+}, Mg{sup 2+}, Na{sup +} or K{sup +}, and in water with no such addition (mean ionic strength 5.58 x 10{sup -4} M). Only a very slight ameliorating effect of increased ionic strength was observed, while the degree of Al polymerisation was of major importance in fish mortality. In addition, it was observed that smaller fish survived the Al exposures for a longer time than larger fish. We hypothesise that this is because larger fish are more susceptible to hypoxia than smaller fish. - Ionic strength has a slight ameliorating effect on Al toxicity in brown trout.

  4. Nanoparticle transport in water-unsaturated porous media: effects of solution ionic strength and flow rate

    Energy Technology Data Exchange (ETDEWEB)

    Prédélus, Dieuseul; Lassabatere, Laurent, E-mail: laurent.lassabatere@entpe.fr [Université de Lyon, Laboratoire d’Ecologie des Hydrosystèmes Naturels et Anthropisés, LEHNA (France); Louis, Cédric; Gehan, Hélène [Nano-H S.A.S., 2 place de l’Europe, Bâtiment A, Parc d’activité VALAD (France); Brichart, Thomas [Université Lyon 1-CNRS, Institut Lumière Matière, UMR 5306 CNRS (France); Winiarski, Thierry; Angulo-Jaramillo, Rafael [Université de Lyon, Laboratoire d’Ecologie des Hydrosystèmes Naturels et Anthropisés, LEHNA (France)

    2017-03-15

    This paper presents the influence of ionic strength and flow on nanoparticle (NP) retention rate in an unsaturated calcareous medium, originating from a heterogeneous glaciofluvial deposit of the region of Lyon (France). Laboratory columns 10 cm in diameter and 30 cm in length were used. Silica nanoparticles (Au-SiO{sub 2}-FluoNPs), with hydrodynamic diameter ranging from 50 to 60 nm and labeled with fluorescein derivatives, were used to simulate particle transport, and bromide was used to characterize flow. Three flow rates and five different ionic strengths were tested. The transfer model based on fractionation of water into mobile and immobile fractions was coupled with the attachment/detachment model to fit NPs breakthrough curves. The results show that increasing flow velocity induces a decrease in nanoparticle retention, probably as the result of several physical but also geochemical factors. The results show that NPs retention increases with ionic strength. However, an inversion of retention occurs for ionic strength >5.10{sup −2} M, which has been scarcely observed in previous studies. The measure of zeta potential and DLVO calculations show that NPs may sorb on both solid-water and air-water interfaces. NPs size distribution shows the potential for nanoparticle agglomeration mostly at low pH, leading to entrapment in the soil pores. These mechanisms are highly sensitive to both hydrodynamic and geochemical conditions, which explains their high sensitivity to flow rates and ionic strength.

  5. Neptunium (V) Adsorption to a Halophilic Bacterium Under High Ionic Strength Conditions: A Surface Complexation Modeling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Ams, David A [Los Alamos National Laboratory

    2012-06-11

    Rationale for experimental design: Np(V) -- important as analog for Pu(V) and for HLW scenarios; High ionic strength -- relevant to salt-based repositories such as the WIPP; Halophilic microorganisms -- representative of high ionic strength environments. For the first time showed: Significant adsorbant to halophilic microorganisms over entire pH range under high ionic strength conditions; Strong influence of ionic strength with increasing adsorption with increasing ionic strength (in contrast to trends of previous low ionic strength studies); Effect of aqueous Np(V) and bacterial surface site speciation on adsorption; and Developed thermodynamic models that can be incorporated into geochemical speciation models to aid in the prediction of the fate and transport of Np(V) in more complex systems.

  6. The second evolution of ionic liquids: from solvents and separations to advanced materials--energetic examples from the ionic liquid cookbook.

    Science.gov (United States)

    Smiglak, Marcin; Metlen, Andreas; Rogers, Robin D

    2007-11-01

    In this Account of the small portion of the recent research in ionic liquids (ILs) by the Rogers Group, we fast forward through the first evolution of IL research, where ILs were studied for their unique set of physical properties and the resulting potential for tunable "green solvents", to the second evolution of ILs, where the tunability of the cation and anion independently offers almost unlimited access to targeted combinations of physical and chemical properties. This approach is demonstrated here with the field of energetic ionic liquids (EILs), which utilizes this design flexibility to find safe synthetic routes to ILs with high energy content and targeted physical properties.

  7. Influence of anion on thermophysical properties of ionic liquids with polar solvent

    International Nuclear Information System (INIS)

    Govinda, Varadhi; Reddy, P. Madhusudhana; Attri, Pankaj; Venkatesu, P.; Venkateswarlu, P.

    2013-01-01

    Highlights: ► We have reported a series of ionic liquids (ILs) involving a common cation. ► The molecular interactions between ILs and DMSO. ► The results for observed anion dependent phenomena. ► Redlich–Kister polynomial was used to correlate the results. ► The intermolecular interactions were analyzed on the basis of properties. -- Abstract: In this work, we have reported a series of ionic liquids (ILs) involving a common cation trimethyl ammonium, ([(CH 3 ) 3 NH] + ), with generally used anions (acetate, [CH 3 COO] − , sulfate, [HSO 4 ] − , phosphate, [H 2 PO 4 ] − ). To address the molecular interactions between the relatively new class of solvents such as trimethylammonium acetate [(CH 3 ) 3 NH + ] [CH 3 COO – ] (TMAA), trimethylammonium hydrogen sulfate [(CH 3 ) 3 NH + ][HSO 4 − ] (TMAS), and trimethylammonium dihydrogen phosphate [(CH 3 ) 3 NH + ][H 2 PO 4 – ] (TMAP), with the polar solvent, dimethylsulfoxide (DMSO), the density (ρ), speed of sound (u) and viscosity (η) values have been measured over complete concentration range and wide temperature range from 298.15 K to 313.15 K in steps of 5 K under ambient pressure. By using these experimental results, excess volumes (V E ), isentropic compressibility deviations (Δκ s ) and viscosity deviations (Δη) were obtained for all these binary systems at all experimental temperatures. The results are correlated by the Redlich−Kister type function to derive the coefficients and estimate the standard error. Further, the results for observed anion dependent phenomena and temperature influence on measured and derived properties are also discussed

  8. Radiation stability of diglycolamide functionalized calix[4]arenes in ionic liquid: Solvent extraction, EPR and GC–MS studies

    NARCIS (Netherlands)

    Sengupta, A; Mohapatra, P.K.; Patil, A.B.; Kadam, R.M.; Verboom, Willem

    2016-01-01

    Ionic liquid-based solvent systems containing diglycolamide-functionalized calix[4]arenes (C4DGAs) are efficient for actinide ion extraction from nitric acid feeds. Therefore, the radiolytic stability of three C4DGAs (wide-rim, narrow-rim and both side DGA-functionalized calix[4]arenes) and TODGA

  9. [Cu(I)(bpp)]BF4: the first extended coordination network prepared solvothermally in an ionic liquid solvent.

    Science.gov (United States)

    Jin, Kun; Huang, Xiaoying; Pan, Long; Li, Jing; Appel, Aaron; Wherland, Scot; Pang, Long

    2002-12-07

    Use of an ionic liquid [bmim][BF4] (bmim = 1-butyl-3-methylimidazolium) as solvent has resulted in the first extended coordination structure, the two-dimensional network [Cu(bpp)]BF4 [bpp = 1,3-bis(4-pyridyl)propane], produced via a solvothermal route.

  10. Plutonium (IV) complexation by nitrate in acid solutions of ionic strengths from 2 to 19 molal

    International Nuclear Information System (INIS)

    Berg, J.M.; Veirs, D.K.; Vaughn, R.B.; Cisneros, M.A.; Smith, C.A.

    1997-01-01

    Titrations of Pu(IV) with HNO 3 in a series of aqueous HClO 4 solutions ranging in ionic strength from 2 to 19 molal were followed using absorption spectrophotometry. The Pu 5f-5f spectra in the visible and near IR range change with complex formation. At each ionic strength, a series of spectra were obtained by varying nitrate concentration. Each series was deconvoluted into spectra f Pu 4+ (aq), Pu(NO 3 ) 3+ and Pu(NO 3 ) 2 2+ complexes, and simultaneously their formation constants were determined. When corrected for the incomplete dissociation of nitric acid, the ionic strength dependence of each formation constant can be described by two parameters, β 0 and Δ var-epsilon using the formulae of specific ion interaction theory. The difficulties with extending this analysis to higher nitrate coordination numbers are discussed

  11. How ionic strength affects the conformational behavior of human and rat beta amyloids--a computational study.

    Directory of Open Access Journals (Sweden)

    Zdeněk Kříž

    Full Text Available Progressive cerebral deposition of amyloid beta occurs in Alzheimers disease and during the aging of certain mammals (human, monkey, dog, bear, cow, cat but not others (rat, mouse. It is possibly due to different amino acid sequences at positions 5, 10 and 13. To address this issue, we performed series of 100 ns long trajectories (each trajectory was run twice with different initial velocity distribution on amyloid beta (1-42 with the human and rat amino acid sequence in three different environments: water with only counter ions, water with NaCl at a concentration of 0.15 M as a model of intracellular Na(+ concentration at steady state, and water with NaCl at a concentration of 0.30 M as a model of intracellular Na(+ concentration under stimulated conditions. We analyzed secondary structure stability, internal hydrogen bonds, and residual fluctuation. It was observed that the change in ionic strength affects the stability of internal hydrogen bonds. Increasing the ionic strength increases atomic fluctuation in the hydrophobic core of the human amyloid, and decreases the atomic fluctuation in the case of rat amyloid. The secondary structure analyses show a stable α-helix part between residues 10 and 20. However, C-terminus of investigated amyloids is much more flexible showing no stable secondary structure elements. Increasing ionic strength of the solvent leads to decreasing stability of the secondary structural elements. The difference in conformational behavior of the three amino acids at position 5, 10 and 13 for human and rat amyloids significantly changes the conformational behavior of the whole peptide.

  12. Study and modeling of lanthanide(3)-L and americium(3)-L (With L = NTA, EDTA and DTPA) in high ionic strength aqueous solutions

    International Nuclear Information System (INIS)

    Rocchiccioli, F.

    2000-01-01

    The dissociation constants of NTA, EDTA, DTPA in NaCl, NaClO 4 , LiCl and LiClO 4 aqueous solutions of various ionic strengths have been gathered from the literature and from the Critical Surveys of Stability Constants. These values have been completed by a series of pKa values obtained in the same salted solution at higher ionic strengths by potentiometry involving a combined glass electrode at 25 deg C. The dependencies of the pKas versus the ionic strength have been investigated by using the Specific Interaction Theory (SIT), the parabolic model and the Pitzer model. The stability constants of complexes involving lanthanides (III), such as Nd 3+ , Eu 3+ and Lu 3+ , and americium (III), with the ligands previously mentioned in NaCl, NaClO 4 , LiCl and LiClO 4 aqueous solutions of high ionic strengths have been determined. The methods used for the determination of the stability constants for the lanthanide complexes are various: direct measurements by potentiometry when possible, UV-visible absorption spectroscopy involving Arsenazo (III) as a competitor ligand. For the actinide complexes, solvent extraction experiments have been performed. The different systems, along with the dissociation constants of several complexes in the same aqueous media, have been successfully modeled by the SIT, the parabolic method and the Pitzer method. (author)

  13. Ionic strength dependence of stability constants, complexation of Molybdenum(V I) with EDTA

    International Nuclear Information System (INIS)

    Zare, K.; Majlesi, K.; Teimoori, F.

    2002-01-01

    The stability constant of Mo (Vi) complexes with EDTA in aqueous solution has been determined by various authors using different techniques, but according to literature, no work has been reported on ionic strength dependence of these complexes. The present work describes the complexation of Mo (Vi) with EDTA in an ionic strength range of 0.1 to 1.0 moldm - 3 s odium perchlorate at 25 d ig C . The complexation of molybdenum (Vi) with EDTA was investigated in aqueous solution ranging in ph from 5 to 7 using UV spectrophotometric techniques. The composition of the complex was determined by the continuous variations method. It was shown that molybdenum (Vi) forms a 2:1 complex with EDTA of the type (MoO 3 ) 2 L - 4 a t ph =5.5 The parameters that define the dependence on ionic strength were analyzed with the aim of obtaining further information regarding to their variation as a function of the charges involved in the complex reaction. Moreover, a Debye-Huckel type equation makes it possible to estimate a stability constant at a fixed ionic strength when its value is known at another ionic media in the range of 0.1 3 . Therefore the evaluation may make a significant contribution solving many analytical and speciation problems

  14. Response surface optimization of pH and ionic strength for emulsion characteristics of egg yolk.

    Science.gov (United States)

    Kurt, S; Zorba, O

    2009-11-01

    Effects of pH (3.5, 4.5, 6.0, 7.5, and 8.5) and ionic strength (0.05, 0.15, 0.30, 0.45, and 0.55 M NaCl) on emulsion capacity, emulsion stability (ES), apparent yield stress of emulsion (AYS), and emulsion density (ED) of egg yolk were studied by using a model system. Ionic strength and pH had significant (P emulsion characteristics of egg yolk. Their interaction effects also have been found significant on ES, AYS, and ED. Predicted solutions of ES, emulsion capacity, and ED were minimum. The critical point of ES was determined to be at pH 6.08 and an ionic strength of 0.49 (M NaCl). Predicted solution for AYS was a maximum, which was determined to be at pH 6.04 and an ionic strength of 0.29 (M NaCl). Optimum values of pH and ionic strenght were 4.61 to 7.43 and 0.10 to 0.47, respectively.

  15. Neptunium(V) Adsorption to Bacteria at Low and High Ionic Strength

    Science.gov (United States)

    Ams, D.; Swanson, J. S.; Reed, D. T.

    2010-12-01

    Np(V) is expected to be the predominant oxidation state of neptunium in aerobic natural waters. Np(V), as the NpO2+ aquo and associated complexed species, is readily soluble, interacts weakly with geologic media, and has a high redox stability under a relatively wide range of subsurface conditions. These chemical properties, along with a long half-life make it a primary element of concern regarding long-term nuclear waste storage and subsurface containment. The fate and transport of neptunium in the environment may be influenced by adsorption onto bacterial surfaces. The adsorption of neptunium to bacterial surfaces ties the mobility of the contaminant to the mobility of the bacterium. In this study, the adsorption of the neptunyl (NpO2+) ion was evaluated at low ionic strength on a common soil bacterium and at high ionic strength on a halophilic bacterium isolated from a briny groundwater near the Waste Isolation Pilot Plant (WIPP) in southeast New Mexico. Adsorption experiments were performed in batch reactors as a function of pH, ionic strength, and bacteria/Np mass ratio. Np(V) adsorption was modeled using a surface complexation approach with the mathematical program FITEQL to determine functional group specific binding constants. The data from acid and base titrations of the bacteria used were also modeled to estimate the concentrations and deprotonation constants of discrete bacterial surface functional groups. Bacterial functional group characteristics and Np(V) adsorption behavior between the soil bacterium and the halophilic bacterium were compared. These results highlight key similarities and differences in actinide adsorption behavior in environments of significantly different ionic strength. The observed adsorption behavior may be linked to similarities and differences in the characteristics of the moieties between the cell walls of common gram-negative soil and halophilic bacteria. Moreover, differences in adsorption behavior may also reflect ionic

  16. Neptunium(V) adsorption to bacteria at low and high ionic strength

    International Nuclear Information System (INIS)

    Ams, David A.; Swanson, Juliet S.; Reed, Donald T.; Fein, Jeremy B.

    2010-01-01

    Np(V) is expected to be the predominant oxidation state of neptunium in aerobic natural waters. Np(V), as the NpO 2 + aquo and associated complexed species, is readily soluble, weakly interacting with geologic media, and has a high redox stability under a relatively wide range of subsurface conditions. These chemical properties, along with a long half-life make it a primary element of concern regarding long-term nuclear waste storage and subsurface contaminant. The fate and transport of neptunium in the environment may be influenced by adsorption onto bacterial surfaces. The adsorption of neptunium to bacterial surfaces ties the mobility of the contaminant to the mobility of the bacterium. In this study, the adsorption of the neptunyl (NpO 2 + ) ion was evaluated at low ionic strength on a common soil bacterium and at high ionic strength on a halophilic bacterium isolated from a briny groundwater near the Waste Isolation Pilot Plant (WIPP) in southeast New Mexico. Adsorption experiments were performed in batch reactors as a function of pH, ionic strength, and bacterialNp mass ratio. Np(V) adsorption was modeled using a surface complexation approach with the mathematical program FITEQL to determine functional group specific binding constants. The data from acid and base titrations of the bacteria were also modeled to estimate the concentrations and deprotonation constants of discrete bacterial surface functional groups. Bacterial functional group characteristics and Np(V) adsorption behavior between the soil bacterium and the halophilic bacterium were compared. These results highlight the key similarities and differences in actinide adsorption behavior in environments of significantly different ionic strength. Similarities in adsorption behavior may be linked to similarities in the characteristics of the moieties between all bacterial cell walls. Differences in adsorption behavior may reflect differences in ionic strength effects, rather than differences in bacteria

  17. Neptunium(V) adsorption to bacteria at low and high ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Ams, David A [Los Alamos National Laboratory; Swanson, Juliet S [Los Alamos National Laboratory; Reed, Donald T [Los Alamos National Laboratory; Fein, Jeremy B [UNIV OF NOTRE DAME

    2010-12-08

    Np(V) is expected to be the predominant oxidation state of neptunium in aerobic natural waters. Np(V), as the NpO{sub 2}{sup +} aquo and associated complexed species, is readily soluble, weakly interacting with geologic media, and has a high redox stability under a relatively wide range of subsurface conditions. These chemical properties, along with a long half-life make it a primary element of concern regarding long-term nuclear waste storage and subsurface contaminant. The fate and transport of neptunium in the environment may be influenced by adsorption onto bacterial surfaces. The adsorption of neptunium to bacterial surfaces ties the mobility of the contaminant to the mobility of the bacterium. In this study, the adsorption of the neptunyl (NpO{sub 2}{sup +}) ion was evaluated at low ionic strength on a common soil bacterium and at high ionic strength on a halophilic bacterium isolated from a briny groundwater near the Waste Isolation Pilot Plant (WIPP) in southeast New Mexico. Adsorption experiments were performed in batch reactors as a function of pH, ionic strength, and bacterialNp mass ratio. Np(V) adsorption was modeled using a surface complexation approach with the mathematical program FITEQL to determine functional group specific binding constants. The data from acid and base titrations of the bacteria were also modeled to estimate the concentrations and deprotonation constants of discrete bacterial surface functional groups. Bacterial functional group characteristics and Np(V) adsorption behavior between the soil bacterium and the halophilic bacterium were compared. These results highlight the key similarities and differences in actinide adsorption behavior in environments of significantly different ionic strength. Similarities in adsorption behavior may be linked to similarities in the characteristics of the moieties between all bacterial cell walls. Differences in adsorption behavior may reflect differences in ionic strength effects, rather than

  18. Effects of ionic strength and ion pairing on (plant-wide) modelling of anaerobic digestion

    DEFF Research Database (Denmark)

    Solon, Kimberly; Flores Alsina, Xavier; Mbamba, Christian Kazadi

    2015-01-01

    Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections....... The paper describes: 1) how the anaerobic digester performance is affected by physico-chemical corrections; 2) the effect on pH and the anaerobic digestion products (CO2, CH4 and H2); and, 3) how these variations are propagated from the sludge treatment to the water line. Results at high ionic strength...

  19. Hydrolysis, formation and ionization constants at 250C, and at high temperature-high ionic strength

    International Nuclear Information System (INIS)

    Phillips, S.L.; Phillips, C.A.; Skeen, J.

    1985-02-01

    Thermochemical data for nuclear waste disposal are compiled. The resulting computerized database consists of critically evaluated data on Gibbs energy of formation, enthalpy of formation, entropy and heat capacity of selected substances for about 16 elements at 25 0 C and zero ionic strength. Elements covered are Am, As, Br, C, Cl, F, I, Mo, Np, N, O, P, Pu, Si, Sr, S, and U. Values of these thermodynamic properties were used to calculate equilibrium quotients for hydrolysis, complexation and ionization reactions up to 300 0 C and 3 ionic strength, for selected chemical reactions

  20. Ionically cross-linked poly(allylamine) as a stimulus-responsive underwater adhesive: ionic strength and pH effects.

    Science.gov (United States)

    Lawrence, Patrick G; Lapitsky, Yakov

    2015-02-03

    Gel-like coacervates that adhere to both hydrophilic and hydrophobic substrates under water have recently been prepared by ionically cross-linking poly(allylamine) (PAH) with pyrophosphate (PPi) and tripolyphosphate (TPP). Among the many advantages of these underwater adhesives (which include their simple preparation and low cost) is their ability to dissolve on demand when exposed to high or low pH. To further analyze their stimulus-responsive properties, we have investigated the pH and ionic strength effects on the formation, rheology and adhesion of PAH/PPi and PAH/TPP complexes. The ionic cross-linker concentrations needed to form these adhesives decreased with increasing pH and ionic strength (although the complexes ceased to form when the parent solution pH exceeded ca. 8.5; i.e., the effective pKa of PAH). Once formed, their ionic cross-links were most stable (as inferred from their relaxation times) at near-neutral or slightly alkaline pH values (of roughly 6.5-9) and at low ionic strengths. The decrease in ionic cross-link stability within complexes prepared at other pH values and at elevated (150-300 mM) NaCl concentrations diminished both the strength and longevity of adhesion (although, under most conditions tested, the short-term tensile adhesion strengths remained above 10(5) Pa). Additionally, the sensitivity of PAH/PPi and PAH/TPP complexes to ionic strength was demonstrated as a potential route to injectable adhesive design (where spontaneous adhesive formation was triggered via injection of low-viscosity, colloidal PAH/TPP dispersions into phosphate buffered saline). Thus, while the sensitivity of ionically cross-linked PAH networks to pH and ionic strength can weaken their adhesion, it can also impart them with additional functionality, such as minimally invasive, injectable delivery, and ability to form and dissolve their bonds on demand.

  1. Effect of temperature on mixing thermodynamics of a new ionic liquid: {2-Hydroxy ethylammonium formate (2-HEAF) + short hydroxylic solvents}

    International Nuclear Information System (INIS)

    Iglesias, M.; Torres, A.; Gonzalez-Olmos, R.; Salvatierra, D.

    2008-01-01

    Density and ultrasonic velocity of the mixtures of the new ionic liquid 2-hydroxy ethylammonium formate (2-HEAF) and short hydroxylic solvents (water, methanol, and ethanol) have been measured at the range of temperature (288.15 to 323.15) K and atmospheric pressure. The corresponding apparent molar volume and the apparent molar isentropic compressibility values have been evaluated from the experimental data and fitted to a temperature dependent Redlich-Mayer equation. From these correlations, the limiting infinite dilution values of the apparent magnitudes have also been computed. Derived properties such as isobaric expansibility and isothermal coefficient of pressure excess molar enthalpy were computed due to their importance in the study of specific molecular interactions. The new experimental data were used to test the capability of prediction of the modified Heller temperature dependent equation (MHE) and collision factor theory (CFT). The obtained results indicate that ionic liquid interactions in water are weaker than in the studied alcoholic solutions. An intersection point in isotherms of isentropic compressibility was observed for aqueous solutions which may be an indication of the clathrate structural interactions at high solvent composition. The observed inverse dependence on temperature for aqueous or alcoholic mixtures points out the special trend of packing of this ionic liquid into hydroxylic solvents and its strong dependence on steric hindrance of aliphatic residues. As previously observed, the increase in van der Waals forces due to the presence of long alkyl chain (into ionic liquid and alcohols) leads to higher interactions on mixing

  2. Selection of optimum ionic liquid solvents for flavonoid and phenolic acids extraction

    Science.gov (United States)

    Rahman, N. R. A.; Yunus, N. A.; Mustaffa, A. A.

    2017-06-01

    Phytochemicals are important in improving human health with their functions as antioxidants, antimicrobials and anticancer agents. However, the quality of phytochemicals extract relies on the efficiency of extraction process. Ionic liquids (ILs) have become a research phenomenal as extraction solvent due to their unique properties such as unlimited range of ILs, non-volatile, strongly solvating and may become either polarity. In phytochemical extraction, the determination of the best solvent that can extract highest yield of solute (phytochemical) is very important. Therefore, this study is conducted to determine the best IL solvent to extract flavonoids and phenolic acids through a property prediction modeling approach. ILs were selected from the imidazolium-based anion for alkyl chains ranging from ethyl > octyl and cations consisting of Br, Cl, [PF6], BF4], [H2PO4], [SO4], [CF3SO3], [TF2N] and [HSO4]. This work are divided into several stages. In Stage 1, a Microsoft Excel-based database containing available solubility parameter values of phytochemicals and ILs including its prediction models and their parameters has been established. The database also includes available solubility data of phytochemicals in IL, and activity coefficient models, for solid-liquid phase equilibrium (SLE) calculations. In Stage 2, the solubility parameter values of the flavonoids (e.g. kaempferol, quercetin and myricetin) and phenolic acids (e.g. gallic acid and caffeic acid) are determined either directly from database or predicted using Stefanis and Marrero-Gani group contribution model for the phytochemicals. A cation-anion contribution model is used for IL. In Stage 3, the amount of phytochemicals extracted can be determined by using SLE relationship involving UNIFAC-IL model. For missing parameters (UNIFAC-IL), they are regressed using available solubility data. Finally, in Stage 4, the solvent candidates are ranked and five ILs, ([OMIM] [TF2N], [HeMIM] [TF2N], [HMIM] [TF2N

  3. Solubility and first hydrolysis constants of europium at different ionic strength and 303 K

    International Nuclear Information System (INIS)

    Ramirez-Garcia, J.J.; Jimenez-Reyes, M.; Lopez-Gonzalez, H.; Autonoma Metropolitana-Iztapalapa Univ., Mexico City; Solache-Rios, M.; Fernandez-Ramirez, E.; Centro Interamericano de Recursos del Agua, Toluca; Rojas-Hernandez, A.

    2003-01-01

    The solubility of europium at 0.02M, 0.1M and 0.7M NaClO 4 ionic strength solutions was determined by a radiometric method and pEu s -pC H diagrams were obtained. Hydrolysis constants were also determined at the same ionic strengths by pH titration and the values found were log *β 1 -7.68±0.11, -8.07±0.10 and -8.20±0.11. The log K sp values were -23.5±0.2, -22.7±0.2 and -21.9±0.2 for 0.02M, 0.1M and 0.7M NaClO 4 ionic strengths, respectively, at 303 K under CO 2 -free conditions and the extrapolated value at zero ionic strength was log K sp 0 = -24.15. The working pC H ranges for the calculation of the hydrolysis constants were selected from the pEu s -pC H diagrams in the region where precipitation of europium oxide or hydroxide was less than 20%. Europium removal from aqueous solutions with zeolites was explored. (author)

  4. Incorporating the effect of ionic strength in free energy calculations using explicit ions

    NARCIS (Netherlands)

    Donnini, S; Mark, AE; Juffer, AH; Villa, Alessandra

    2005-01-01

    The incorporation of explicit ions to mimic the effect of ionic strength or to neutralize the overall charge on a system in free energy calculations using molecular dynamics simulations is investigated. The difference in the free energy of hydration between two triosephosphate isomerase inhibitors

  5. Adsorption of Sr on kaolinite, illite and montmorillonite at high ionic strengths

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, J.J.; Langmuir, D. (Colorado School of Mines, Golden (USA). Dept. of Chemistry and Geochemistry)

    1991-01-01

    Experimental measurements of Sr adsorption onto kaolinite, illite and montmorillonite in up to 4.0 mol/kg NaCl solutions, were modelled with the surface ionization and complexation triple-layer (SIC) model (Davis et al.) to determine if model adjustments were required for high ionic strengths. Improved model fits to the adsorption data were obtained at high ionic strengths, reflecting a lowered sensitivity of the model. A general reduction in Sr adsorption with increasing ionic strength was caused by an increase in the outer layer surface charge, rather than by a drop in the number of available adsorption sites. Sensitivity analysis showed that the range of values of model constants yielding acceptable fits was as large as variations reported in the literature for these constants. The study demonstrates that adsorption will not retard Sr migration in brines, and that it is unnecessary to introduce a Pitzer ion interaction subroutine in the SIC model when considering adsorption at high ionic strengths. (orig.).

  6. Effect of pH and ionic strength on the bioadhesive properties of ...

    African Journals Online (AJOL)

    Prosopis gum (PG) extracted from Prosopis africana was investigated for bioadhesive properties as affected by pH and ionic strength. The bioadhesive properties were evaluated using the adhesion of gum dispersion-coated glass beads on the antrum region of the porcine gastrointestinal tract and Lecomte Du Nouy ...

  7. Adsorbed polymers in aqueous media. The relation between zeta-potential, layer thickness and ionic strength

    NARCIS (Netherlands)

    Cohen Stuart, M.A.; Mulder, J.W.

    1985-01-01

    Streaming potentials for glass capillaries with and without adsorbed poly(vinyl pyrrolidone) were used to determine the thickness of the adsorbed polymer layer. It was found that the thickness determined in this way is a strong function of the ionic strength of the solution. The results are compared

  8. Thermodynamics for proton binding of phytate in KNO3(aq) at different temperatures and ionic strengths

    International Nuclear Information System (INIS)

    Bretti, Clemente; De Stefano, Concetta; Lando, Gabriele; Sammartano, Silvio

    2013-01-01

    Highlights: • Protonation data were modeled in a wide range of temperatures and ionic strengths. • Protonation values decrease with increasing ionic strength and temperature. • In KNO 3 proton binding process is slightly exothermic, but less than in NaCl. • The major contribution for the proton association is entropic in nature. • Results are in agreement with previous findings for KCl and NaCl. - Abstract: Potentiometric measurements were performed in KNO 3(aq) , to determine the apparent protonation constants of phytate at different temperatures (278.15 ≤ T (K) ≤ 323.15) and ionic strengths (0.25 ≤ I (mol) dm −3 ≤ 3.0) values. In general, the protonation constants decrease with increasing both temperature and ionic strength. The data reported were critically compared with previous results obtained in KCl and the values are in a good agreement, considering the experimental errors and slight differences between the activity coefficients of the various species in KCl and KNO 3 . Experimental data were then modeled as a function of temperature and ionic strength using, with comparable results, two approaches: the extended Debye–Hückel equation and the specific ion interaction theory (SIT). The single specific ion interaction coefficients, ε, were also determined. The corresponding values are higher than those in Na + media. The protonation constants were also analyzed considering a simplified weak interaction model using an empirical equation that contains an additional term which takes into account the formation of weak complexes. The results obtained for the modeling of the protonation constants are in agreement with the literature findings. Thermodynamic protonation parameters were also obtained at different temperatures and ionic strengths. The proton association process is slightly exothermic and the enthalpic contribution is less negative than that in NaCl solution. As observed in other cases for phytate anion, the major contribution for

  9. Diffusivities, viscosities, and conductivities of solvent-free ionically grafted nanoparticles

    KAUST Repository

    Hong, Bingbing; Panagiotopoulos, Athanassios Z.

    2013-01-01

    A new class of conductive composite materials, solvent-free ionically grafted nanoparticles, were modeled by coarse-grained molecular dynamics methods. The grafted oligomeric counterions were observed to migrate between different cores, contributing to the unique properties of the materials. We investigated the dynamics by analyzing the dependence on temperature and structural parameters of the transport properties (self-diffusion coefficients, viscosities and conductivities) and counterion migration kinetics. Temperature dependence of all properties follows the Arrhenius equation, but chain length and grafting density have distinct effects on different properties. In particular, structural effects on the diffusion coefficients are described by the Rouse model and the theory of nanoparticles diffusing in polymer solutions, viscosities are strongly influenced by clustering of cores, and conductivities are dominated by the motions of oligomeric counterions. We analyzed the migration kinetics of oligomeric counterions in a manner analogous to unimer exchange between micellar aggregates. The counterion migrations follow the "double-core" mechanism and are kinetically controlled by neighboring-core collisions. © 2013 The Royal Society of Chemistry.

  10. Evaluation of the polysubstituted pyridinium ionic liquid [hmmpy][Ntf2] as a suitable solvent for desulfurization: Phase equilibria

    International Nuclear Information System (INIS)

    Arce, Alberto; Francisco, Maria; Soto, Ana

    2010-01-01

    Suitability of a pyridinium ionic liquid as a solvent in desulfurization has been analyzed. (Liquid + liquid) equilibria for ternary systems composed by 1-hexyl-3,5-dimethyl pyridinium {bis[trifluoromethylsulfonyl]imide, thiophene, and three hydrocarbons representative of fuel (n-heptane, 2,2,4 trimethylpentane, and toluene) have been determined at T = 298.15 K and atmospheric pressure. High solubility of thiophene in the ionic liquid and also of toluene have been found, being this solvent practically immiscible with 2,2,4 trimethylpentane and heptane. Equilibrium data of these systems have been well correlated with UNIQUAC equations finding the highest deviations for the ternary system involving toluene. NRTL model drove to worse results being considered as not suitable model to correlate the experimental results.

  11. Extraction of acetanilides in rice using ionic liquid-based matrix solid phase dispersion-solvent flotation.

    Science.gov (United States)

    Zhang, Liyuan; Wang, Changyuan; Li, Zuotong; Zhao, Changjiang; Zhang, Hanqi; Zhang, Dongjie

    2018-04-15

    Ionic liquid-based matrix solid phase dispersion-solvent flotation coupled with high performance liquid chromatography was developed for the determination of the acetanilide herbicides, including metazachlor, propanil, alachlor, propisochlor, pretilachlor, and butachlor in rice samples. Some experimental parameters, including the type of dispersant, the mass ratio of dispersant to sample, pH of sample solution, the type of extraction solvent, the type of ionic liquid, flotation time, and flow rate of N 2 were optimized. The average recoveries of the acetanilide herbicides at spiked concentrations of 50, 125, and 250 µg/kg ranged from 89.4% to 108.7%, and relative standard deviations were equal to or lower than 7.1%, the limits of quantification were in the range of 38.0 to 84.7 µg/kg. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Influence of ionic liquids on actinides extraction by diphenyl(dibutyl)carbamoylmethylphosphine oxide in different solvents from nitric acid solution

    International Nuclear Information System (INIS)

    Pribylova, G.A.

    2011-01-01

    Influence of ionic liquids (ILs) addition (1-50 wt%) on extraction efficiency of actinides by diphenyl(dibutyl)carbamoylmethylphosphine oxide (Ph 2 Bu 2 ) from 3 M HNO 3 has been studied. Am(III) distribution ratios in two-phase systems 0.1 M Ph 2 Bu 2 in either DCE or CHCl 3 -3 M HNO 3 depending on the nature of additional ionic liquids: imidazolium-based ILs: [C 4 mim][PF 6 ], [C 4 mim][BF 4 ] and phosphonium-based ILs: PPF 6 , PBF 4 and PCl were determined. The highest value of Am(III) extraction ratio change (1040) was found on addition of PPF 6 to Ph 2 Bu 2 in CHCl 3 . Extraction of Pu(IV) and U(VI) by 0.001 M Ph 2 Bu 2 in the presence of [C 4 mim][PF 6 ] in DCE, CHCl 3 or meta-nitrobenzotrifluoride (NBTF) have been investigated. The greatest enhancement of extraction efficiency was observed using CHCl 3 , the least polar studied solvent. Using a mixture of conventional solvent and ionic liquid as a solvent for extractant enables one to increase distribution ratios and reduce viscosity of organic phase as compared with ionic liquid viscosity. The marked increase of Am(III), Pu(IV) and U(VI) extraction extent by Ph 2 Bu 2 on addition of ionic liquids to the extent of 10 wt% permit one essentially to diminish amounts considerably more expensive carbamoylmethylphosphine oxide(the general name is CMPO) used in TRUEX process. (author)

  13. Enhanced fluidity liquid chromatography of inulin fructans using ternary solvent strength and selectivity gradients.

    Science.gov (United States)

    Bennett, Raffeal; Olesik, Susan V

    2018-01-25

    The value of exploring selectivity and solvent strength ternary gradients in enhanced fluidity liquid chromatography (EFLC) is demonstrated for the separation of inulin-type fructans from chicory. Commercial binary pump systems for supercritical fluid chromatography only allow for the implementation of ternary solvent strength gradients which can be restrictive for the separation of polar polymeric analytes. In this work, a custom system was designed to extend the capability of EFLC to allow tuning of selectivity or solvent strength in ternary gradients. Gradient profiles were evaluated using the Berridge function (RF 1 ), normalized resolution product (NRP), and gradient peak capacity (P c ). Selectivity gradients provided the separation of more analytes over time. The RF 1 function showed favor to selectivity gradients with comparable P c to that of solvent strength gradients. NRP did not strongly correlate with P c or RF 1 score. EFLC with the hydrophilic interaction chromatography, HILIC, separation mode was successfully employed to separate up to 47 fructan analytes in less than 25 min using a selectivity gradient. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Temperature dependence measurements and structural characterization of trimethyl ammonium ionic liquids with a highly polar solvent.

    Science.gov (United States)

    Attri, Pankaj; Venkatesu, Pannuru; Hofman, T

    2011-08-25

    We report the synthesis and characterization of a series of an ammonium ionic liquids (ILs) containing acetate, dihydrogen phosphate, and hydrogen sulfate anions with a common cation. To characterize the thermophysical properties of these newly synthesized ILs with the highly polar solvent N,N-dimethylformamide (DMF), precise measurements such as densities (ρ) and ultrasonic sound velocities (u) over the whole composition range have been performed at atmospheric pressure and over wide temperature ranges (25-50 °C). The excess molar volume (V(E)) and the deviation in isentropic compressibilities (Δκ(s)) were predicted using these temperature dependence properties as a function of the concentration of ILs. The Redlich-Kister polynomial was used to correlate the results. The ILs investigated in the present study included trimethylammonium acetate [(CH(3))(3)NH][CH(3)COO] (TMAA), trimethylammonium dihydrogen phosphate [(CH(3))(3)NH][H(2)PO(4)] (TMAP), and trimethylammonium hydrogen sulfate [(CH(3))(3)NH][HSO(4)] (TMAS). The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. In addition, the hydrogen bonding between ILs and DMF has been demonstrated using semiempirical calculations with help of Hyperchem 7. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and DMF molecules and their structural factors. The influence of the anion of the protic IL, namely, acetate (CH(3)COO), dihydrogen phosphate (H(2)PO(4)), and hydrogen sulfate (HSO(4)), on the thermophysical properties is also provided. © 2011 American Chemical Society

  15. Influence of ionic strength on the viscosities and water loss of bentonite suspensions containing polymers

    Directory of Open Access Journals (Sweden)

    Luciana Viana Amorim

    2007-03-01

    Full Text Available A study was made of the influence of ionic strength (S on the apparent (AV and plastic (PV viscosities and water loss (WL of sodium bentonite suspension with polymers. Na-bentonite was dispersed in water (4.86% w/w of different ionic strengths (S = 0.0, 0.015, 0.030 and 0.045 M followed by the addition of polymer. Three polymer samples were studied, i.e., low viscosity carboxymethyl cellulose (CMC BV, polyanionic cellulose (PAC, and partially hydrolyzed polyacrylamide (HPAM. The results indicated that the presence of salts and increased salinity greatly influence the apparent and plastic viscosities and water loss of bentonite suspensions with polymer.

  16. Adsorption of barium on kaolinite, illite and montmorillonite at various ionic strengths

    International Nuclear Information System (INIS)

    Atun, G.; Bascetin, E.

    2003-01-01

    The sorption behaviour of Ba 2+ in three different clay minerals from various regions of Turkey has been investigated by means of a tracer technique using 133 Ba in batch experiments. Sorption of Ba 2+ on montmorillonite, kaolinite and illite has been studied in mixed solutions of BaCl 2 and NaCl at ionic strengths ranging from 1 x 10 -3 M to 1 x 10 -1 M. The L-shape exchange isotherms for Ba 2+ -Na + systems are well defined by a Langmuir type equation. The exchange capacity of Ba 2+ ions for all three clay minerals increased with decreasing ionic strength. The adsorption data were fitted to a Freundlich isotherm and empirical Freundlich parameters enabled to the generation of a site distribution function. The selectivity coefficients were nearly constant at low Ba loading and decreased as loading increased. This behavior was an indication of an ion exchange process between Ba 2+ and Na + ions

  17. Microfludic device for creating ionic strength gradients over DNA microarrays for efficient DNA melting studies and assay development

    DEFF Research Database (Denmark)

    Petersen, Jesper; Poulsen, Lena; Birgens, Henrik

    2009-01-01

    microfluidic device that creates a gradient comprising zones of defined ionic strength over a glass slide, in which each zone corresponds to a subarray. Using this device, we demonstrated that ionic strength gradients function in a similar fashion as corresponding thermal gradients in assay development. More...... specifically, we noted that (i) the two stringency modulators generated melting curves that could be compared, (ii) both led to increased assay robustness, and (iii) both were associated with difficulties in genotyping the same mutation. These findings demonstrate that ionic strength stringency buffers can...

  18. Films of Agarose Enable Rapid Formation of Giant Liposomes in Solutions of Physiologic Ionic Strength

    OpenAIRE

    Horger, Kim S.; Estes, Daniel J.; Capone, Ricardo; Mayer, Michael

    2009-01-01

    This paper describes a method to form giant liposomes in solutions of physiologic ionic strength, such as phosphate buffered saline (PBS) or 150 mM KCl. Formation of these cell-sized liposomes proceeded from hybrid films of partially dried agarose and lipids. Hydrating the films of agarose and lipids in aqueous salt solutions resulted in swelling and partial dissolution of the hybrid films and in concomitant rapid formation of giant liposomes in high yield. This method did not require the pre...

  19. The binding of glucose to yeast hexokinase monomers is independent of ionic strength.

    Science.gov (United States)

    Mayes, E L; Hoggett, J G; Kellett, G L

    1982-05-01

    Hoggett & Kellett [Eur. J. Biochem. 66, 65-77 (1976)] have reported that the binding of glucose to the monomer of hexokinase PII isoenzyme is independent of ionic strength, in contrast to the subsequent claim of Feldman & Kramp [Biochemistry 17, 1541-1547 (1978)] that the binding is strongly dependent on ionic strength. Since measurements with native hexokinase P forms are complicated by the fact that the enzyme exists in a monomer-dimer association-dissociation equilibrium, we have now studied the binding of glucose to the proteolytically-modified S forms which are monomeric. At pH 8.5, the affinity of glucose for both SI and SII monomers is independent of salt concentration over the range of KCl concentrations 0-1.0 mol . dm-3 and is in good agreement with that of the corresponding P forms in both low and high salt. These observations confirm that the binding of glucose to hexokinase P monomers is independent of ionic strength and that the affinity of glucose for the hexokinase PII monomer is about an order of magnitude greater than that for the dimer.

  20. Interaction of radionickel with diatomite as a function of pH, ionic strength and temperature

    International Nuclear Information System (INIS)

    Xue Wang

    2013-01-01

    Sequestration of Ni(II) on diatomite as a function of reaction time, pH, ionic strength, foreign ions and temperature were investigated by batch sorption technique. The results indicated that the sorption of Ni(II) on diatomite was quickly in the first contact time of 2 h and then slowly with increasing contact time. The interaction of Ni(II) with diatomite was strongly pH- and ionic strength-dependent at low pH values (i.e., which was dominated by ion exchange or outer-sphere surface complexation), while the pH-dependent and ionic strength-independent sorption at high pH suggested that inner-sphere or multinuclear surface complexation was the main sorption mechanism. With increasing temperature, the sorption of Ni(II) on diatomite increased and the experimental data were well fitted by Langmuir model. The sorption samples at pH 6.8 and 10.0 were also characterized by XPS spectroscopy, and the results suggested that Si atoms also participated in Ni(II) sorption on diatomite. The results are important to evaluate the physicochemical behavior of Ni(II) and other similar radionuclides and heavy metal ions in the environment. (author)

  1. Carbonate adsorption onto goethite as a function of pH and ionic strength

    International Nuclear Information System (INIS)

    Rundberg, R.S.; Albinsson, Y.

    1991-01-01

    The adsorption of carbonate onto geothite was studied as a function of both pH and ionic strength (NaClO 4 electrolyte) using 14 C tracer. The pH ranged from 2.5 to 11.6. The ionic strength was controlled by varying the NaClO 4 concentration and ranged from 0.01 to 0.1 molar. The results indicate that carbonate is adsorbed on goethite as primarily an inner-sphere complex at pH values above the point of zero charge. This is inferred from the lack of dependence on ionic strength in the adsorption of carbonate. Below the point of zero charge carbonate is adsorbed by an additional outer-sphere mechanism. An adsorption isotherm was measured at pH 7.0 with an electrolyte concentration of 0.01M. Deconvolution of the isotherm proved that at least two sorption mechanisms exist. These mechanisms lead to large distribution coefficients at low pH. Thereby making the complete removal and exclusion of carbonate from an aqueous goethite system difficult, for the purpose of characterizing a ''clean'' goethite surface

  2. Effect of high ionic strength on the extraction of uranium(VI ions

    Directory of Open Access Journals (Sweden)

    M.K. Nazal

    2014-01-01

    Full Text Available Preparation and characterization of didodecylphosphoric acid (HDDPA as an extractant in toluene was carried. Mass spectroscopy showed that the monomer peak at 457.4 amu [M–Na+] is double that of the dimer at 891.9 amu [M–M–Na+] and the monomer molecules concentration dominate the dimer molecules in toluene. HDDPA was used as an extractant for the extraction of U(VI ion from perchlorate and nitrate media that have ionic strength (1.00, 3.00, 5.00, 7.00 M. The effect of HDDPA concentration, pcH, ionic strength of supporting electrolytes, and temperature in the range 15–45 °C on the extraction process have been studied. The stoichiometry of the extraction of U(VI ion, the free energy change (ΔG, the enthalpy change (ΔH, the entropy change (ΔS, and Kex at different ionic strength have been calculated. The formula of the complexes, which were formed has been established to be UO2(X(R2(HR2 at pcH equal 2.00 and UO2(X(R2(HR2 and UO2(X(R2 at pcH = 1.00, where (X isClO4- orNO3- and (HR2 is didodecylphosphoric acid monomer, (R2 is the deprotonated didodecylphosphoric acid, where R is the dodecyl group.

  3. Solvent effects in the synergistic solvent extraction of Co2+

    International Nuclear Information System (INIS)

    Kandil, A.T.; Ramadan, A.

    1979-01-01

    The extraction of Co 2+ from a 0.1M ionic strength aqueous phase (Na + , CH 3 COOH) of pH = 5.1 was studied using thenoyltrifluoroacetone, HTTA, in eight different solvents and HTTA + trioctylphosphine oxide, TOPO, in the same solvents. A comparison of the effect of solvent dielectric constant on the equilibrium constant shows a synergism as a result of the increased hydrophobic character imparted to the metal complex due to the formation of the TOPO adduct. (author)

  4. Application of non-ionic surfactant as a developed method for the enhancement of two-phase solvent bar microextraction for the simultaneous determination of three phthalate esters from water samples.

    Science.gov (United States)

    Bandforuzi, Samereh Ranjbar; Hadjmohammadi, Mohammad Reza

    2018-08-03

    The extraction of phthalate esters (PEs) from aqueous matrices using two-phase solvent bar microextraction by organic micellar phase was investigated. A short hollow fiber immobilized with reverse micelles of Brij 35 surfactant in 1-octanol was served as the solvent bar for microextraction. Experimental results show that the extraction efficiency were much higher using two-phase solvent bar microextraction based on non-ionic surfactant than conventional two-phase solvent bar microextraction because of a positive effect of surfactant-containing extraction phase in promoting the partition process by non-ionic intermolecular forces such as polar and hydrophobicity interactions. The nature of the extraction solvent, type and concentration of non-ionic surfactant, extraction time, sample pH, temperature, stirring rate and ionic strength were the effecting parameters which optimized to obtain the highest extraction recovery. Analysis of recovered analytes was carried out with high performance liquid chromatography coupled with ultraviolet detection (HPLC-UV). Under the optimum conditions, linearity was observed in the range of 1-800 ng mL -1 for dimethylphthalate (DMP) and 0.5-800 ng mL -1 for diethylphthalate (DEP) and di-n-butyl phthalate (DBP) with correlation determination values above 0.99 for them. The limits of detection and quantification were ranged from 0.012 to 0.03 ng mL -1 and 0.04-0.1 ng mL -1 , respectively. The ranges of intra-day and inter-day RSD (n = 3) at 20 ng mL -1 of PEs were 1.8-2.1% and 2.1-2.6%, respectively. Results showed that developed method can be a very powerful, innovative and promising sample preparation technique in PEs analysis from environmental and drinking water samples. Copyright © 2018. Published by Elsevier B.V.

  5. The effect of high ionic strength on neptunium (V) adsorption to a halophilic bacterium

    Science.gov (United States)

    Ams, David A.; Swanson, Juliet S.; Szymanowski, Jennifer E. S.; Fein, Jeremy B.; Richmann, Michael; Reed, Donald T.

    2013-06-01

    The mobility of neptunium (V) in subsurface high ionic strength aqueous systems may be strongly influenced by adsorption to the cell wall of the halophilic bacteria Chromohalobacter sp. This study is the first to evaluate the adsorption of neptunium (V) to the surface of a halophilic bacterium as a function of pH from approximately 2 to 10 and at ionic strengths of 2 and 4 M. This is also the first study to evaluate the effects of carbonate complexation with neptunium (V) on adsorption to whole bacterial cells under high pH conditions. A thermodynamically-based surface complexation model was adapted to describe experimental adsorption data under high ionic strength conditions where traditional corrections for aqueous ion activity are invalid. Adsorption of neptunium (V) was rapid and reversible under the conditions of the study. Adsorption was significant over the entire pH range evaluated for both ionic strength conditions and was shown to be dependent on the speciation of the sites on the bacterial surface and neptunium (V) in solution. Adsorption behavior was controlled by the relatively strong electrostatic attraction of the positively charged neptunyl ion to the negatively charged bacterial surface at pH below circum-neutral. At pH above circum-neutral, the adsorption behavior was controlled by the presence of negatively charged neptunium (V) carbonate complexes resulting in decreased adsorption, although adsorption was still significant due to the adsorption of negatively charged neptunyl-carbonate species. Adsorption in 4 M NaClO4 was enhanced relative to adsorption in 2 M NaClO4 over the majority of the pH range evaluated, likely due to the effect of increasing aqueous ion activity at high ionic strength. The protonation/deprotonation characteristics of the cell wall of Chromohalobacter sp. were evaluated by potentiometric titrations in 2 and 4 M NaClO4. Bacterial titration results indicated that Chromohalobacter sp. exhibits similar proton buffering

  6. Bio-oil extraction of Jatropha curcas with ionic liquid co-solvent: Fate of biomass protein.

    Science.gov (United States)

    Severa, Godwin; Edwards, Melisa; Cooney, Michael J

    2017-02-01

    The fate of oil-seed biomass protein has been tracked through all steps of a multi-phase extraction process using an ionic liquid based co-solvent system previously demonstrated to extract bio-oil and phorbol esters and to recover fermentable sugars from Jatropha oil seed. These analyses, however, did not address the fate of biomass protein. This work demonstrated that the majority of protein (∼86%) tracked with the biomass with the balance lost to co-solvent (∼12%) and methanol (∼2%) washes. A significant portion of the ionic liquid remained with the treated biomass and required aggressive methanol washes to recover. A system analysis showed a net-positive energy balance and thus the potential of this system to produce both bio-oil and protein-rich toxin-free biomass. While these results further support Jatropha as an oil seed crop, the additional costs of solvent recovery will need to be addressed if commercialization is to be realized. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Electrochemical reactions of uranyl(VI) complexes in aqueous solution, non-aqueous solvents, and ionic liquids

    International Nuclear Information System (INIS)

    Ikeda, Yasuhisa

    2006-01-01

    Author's recent experimental results on the chemistry of U(V) in aqueous solution, non-aqueous solvents, and ionic solvents by cyclic voltametry are described. The U(V) was produced by electrochemical reduction of uranyl U(VI) ions or complexes such as carbonates, DMF(N, N-dimethylformamide), DMSO(dimethylsulfoxide), acetylacetonato, and other organic polydental ligands. The produced U(V) complexes were studied by spectrophotometry using optical-transmission thin-layer electrode. The U(V) complexes in non-aqueous solvents were found to be rather stable, they undergo ligand-dissociation reaction but not disproportionation reaction. The structure and electronic spectra as well as IR spectra of the complexes were studied. The present method was further developed to study the behavior of U(V) complexes in ionic liquids as molten salts, e.g., alkaline metals chlorides. Thus, the present research contributes to understanding the chemistry of 5fl system. Application to such nuclear technology as spent fuel reprocessing is discussed. (S. Ohno)

  8. Controlling adsorption and passivation properties of bovine serum albumin on silica surfaces by ionic strength modulation and cross-linking.

    Science.gov (United States)

    Park, Jae Hyeon; Sut, Tun Naw; Jackman, Joshua A; Ferhan, Abdul Rahim; Yoon, Bo Kyeong; Cho, Nam-Joon

    2017-03-29

    Understanding the physicochemical factors that influence protein adsorption onto solid supports holds wide relevance for fundamental insights into protein structure and function as well as for applications such as surface passivation. Ionic strength is a key parameter that influences protein adsorption, although how its modulation might be utilized to prepare well-coated protein adlayers remains to be explored. Herein, we investigated how ionic strength can be utilized to control the adsorption and passivation properties of bovine serum albumin (BSA) on silica surfaces. As protein stability in solution can influence adsorption kinetics, the size distribution and secondary structure of proteins in solution were first characterized by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), and circular dichroism (CD) spectroscopy. A non-monotonic correlation between ionic strength and protein aggregation was observed and attributed to colloidal agglomeration, while the primarily α-helical character of the protein in solution was maintained in all cases. Quartz crystal microbalance-dissipation (QCM-D) experiments were then conducted in order to track protein adsorption onto silica surfaces as a function of ionic strength, and the measurement responses indicated that total protein uptake at saturation coverage is lower with increasing ionic strength. In turn, the QCM-D data and the corresponding Voigt-Voinova model analysis support that the surface area per bound protein molecule is greater with increasing ionic strength. While higher protein uptake under lower ionic strengths by itself did not result in greater surface passivation under subsequent physiologically relevant conditions, the treatment of adsorbed protein layers with a gluteraldehyde cross-linking agent stabilized the bound protein in this case and significantly improved surface passivation. Collectively, our findings demonstrate that ionic strength modulation influences BSA adsorption

  9. Crystallization of an organic compound from an ionic liquid using carbon dioxide as anti-solvent

    NARCIS (Netherlands)

    Kroon, M.C.; Toussaint, V.A.; Shariati - Sarabi, A.; Florusse, L.J.; Spronsen, van J.; Witkamp, G.J.; Peters, C.J.

    2008-01-01

    In this paper the anti-solvency behavior of supercritical carbon dioxide (CO2) as a way to recover an organic compound from an ionic liquid by crystallization is explored. As an example, the conditions for crystallization of the organic compound methyl-(Z)-a-acetamido cinnamate (MAAC) from the ionic

  10. Ionic Liquid as a Solvent and Catalyst for Acylation of Maltodextrin

    Science.gov (United States)

    Catalyst-free esterification of maltodextrin was carried out in ionic liquid. Stearate esters of maltodextrin were obtained in various degree of substitution (DS) when vinyl stearate or stearic acid was heated with maltodextrin in ionic liquid, 1-butyl-3-methylimidazolium cyanamide (bmim[dca]). Re...

  11. Solvent extraction of aromatic sulfur compounds from n-heptane using the 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid

    International Nuclear Information System (INIS)

    Królikowski, Marek; Walczak, Klaudia; Domańska, Urszula

    2013-01-01

    Highlights: • LLE data for (EMIMTCM + thiophene/benzothiophene + n-heptane) were determined. • High S and β for the extraction of thiophene/benzothiophene from n-heptane was found. • Results of S and β were compared with available literature. • The NRTL model satisfactorily correlates the LLE data. -- Abstract: The ionic liquid 1-ethyl-3-methylimidazolium tricyanomethanide ([EMIM][TCM]) has been tested as a solvent for the separation of sulfur compounds from aliphatic hydrocarbon. Liquid–liquid phase equilibrium data have been determined for ternary systems containing the ionic liquid, thiophene or benzothiophene and n-heptane. The influence of temperature on the separation of thiophene from n-heptane was determined. High solubility of sulfur compounds and practical immiscibility of aliphatic hydrocarbon in ionic liquid have been found. The values of selectivity and solute distribution ratios have been calculated for all systems and compared with literature data for other 1-ethyl-3-methylimidazolium-based ionic liquids. High values of selectivity were obtained. The experimental data were correlated using the NRTL equation, and the binary interaction parameters have been reported. The phase equilibria diagrams for the ternary mixtures including the experimental and calculated tie-lines have been presented

  12. Physics and chemistry of an ionic liquid in some industrially important solvent media probed by physicochemical techniques

    International Nuclear Information System (INIS)

    Roy, Mahendra Nath; Banik, Ishani; Ekka, Deepak

    2013-01-01

    Highlights: ► Molecular interaction of Bu 4 PBF 4 in DMSO, DMA, and DMF has been studied. ► More ion–solvent interaction between Bu 4 PBF 4 and DMSO. ► Ion–solvent interaction dominate over ion–ion interaction in the studied solutions. - Abstract: Electrolytic conductivities (Λ), densities (ρ), viscosities (η), and ultrasonic speed (u) of an ionic liquid (IL) tetrabutylphosphonium tetrafluoroborate [Bu 4 PBF 4 ] have been studied in dimethylsulfoxide (DMSO), dimethylacetamide (DMA), and dimethylformamide (DMF) at T = 298.15 K. The limiting molar conductivity (Λ 0 ), the association constant (K A ), and the distance of closest approach of ions (R) have been evaluated using the Fuoss conductance equation (1978). The molar conductivities observed were explained by the formation of ion-pairs (M + + X − ↔ MX). The Walden product is obtained and discussed. Ion–solvent interactions have been interpreted in terms of apparent molar volumes (φ V ) and viscosity B-coefficients which are obtained from the results supplemented with densities and viscosities, respectively. The limiting apparent molar volumes (φ V 0 ), experimental slopes (S V ∗ ) derived from the Masson equation and viscosity A and B coefficients using the Jones–Dole equation have been interpreted in terms of ion–ion and ion–solvent interactions respectively. The adiabatic compressibility (β) has been evaluated using the ultrasonic speed (u) values. Finally values of the limiting partial molar adiabatic compressibility (φ K 0 ) are calculated and discussed.

  13. Excessive counterion condensation on immobilized ssDNA in solutions of high ionic strength.

    Science.gov (United States)

    Rant, Ulrich; Arinaga, Kenji; Fujiwara, Tsuyoshi; Fujita, Shozo; Tornow, Marc; Yokoyama, Naoki; Abstreiter, Gerhard

    2003-12-01

    We present experiments on the bias-induced release of immobilized, single-stranded (ss) 24-mer oligonucleotides from Au-surfaces into electrolyte solutions of varying ionic strength. Desorption is evidenced by fluorescence measurements of dye-labeled ssDNA. Electrostatic interactions between adsorbed ssDNA and the Au-surface are investigated with respect to 1), a variation of the bias potential applied to the Au-electrode; and 2), the screening effect of the electrolyte solution. For the latter, the concentration of monovalent salt in solution is varied from 3 to 1600 mM. We find that the strength of electric interaction is predominantly determined by the effective charge of the ssDNA itself and that the release of DNA mainly occurs before the electrochemical double layer has been established at the electrolyte/Au interface. In agreement with Manning's condensation theory, the measured desorption efficiency (etarel) stays constant over a wide range of salt concentrations; however, as the Debye length is reduced below a value comparable to the axial charge spacing of the DNA, etarel decreases substantially. We assign this effect to excessive counterion condensation on the DNA in solutions of high ionic strength. In addition, the relative translational diffusion coefficient of ssDNA in solution is evaluated for different salt concentrations.

  14. System Development from Organic Solvents to Ionic Liquids for Synthesiz-ing Ascorbyl Esters with Conjugated Linoleic Acids

    DEFF Research Database (Denmark)

    Yang, Zhiyong; Schultz, Lise; Guo, Zheng

    2012-01-01

    . Results show that only Novozym® 435 turned out to be a useful enzymatic preparation for the production of ascorbyl-CLA ester. The optimum reaction conditions in the or-ganic solvent system were 4 h at 55°C and at a molar ratio of 5 (CLA/ascorbic acid). The esterification reaction was trans......-ferred to an ionic liquid system for the purpose of improving solubility of the polar substrate and avoiding the application of organic solvents. From screening experiments, it was evident that only methyltrioctylammonium triflouroacetate (tO-MA·TFA) could provide a proper reaction environment for production...... of ascorbyl-CLA ester when using Novozym® 435 as biocatalyst. It was possible to significantly increase the productivity (150 g/l) through the increase of ascorbic acid sol-ubility in ionic liquids by super saturation together with the increase of reaction temperature to 70°C, far beyond than that in organic...

  15. Self-diffusion of charged colloidal tracer spheres in transparent porous glass media: Effect of ionic strength and pore size

    Science.gov (United States)

    Kluijtmans, Sebastiaan G. J. M.; de Hoog, Els H. A.; Philipse, Albert P.

    1998-05-01

    The influence of charge on diffusion in porous media was studied for fluorescent colloidal silica spheres diffusing in a porous glass medium. The bicontinuous porous silica glasses were optically matched with an organic solvent mixture in which both glass and tracers are negatively charged. Using fluorescence recovery after photobleaching, the long-time self-diffusion coefficient DSL of the confined silica particles was monitored in situ as a function of the ionic strength and particle to pore size ratio. At high salt concentration DSL reaches a relatively high plateau value, which depends on the particle to pore size ratio. This plateau value is unexpectedly higher than the value found for uncharged silica spheres in these porous glasses, but still significantly smaller than the free particle bulk diffusion coefficient of the silica spheres. At low salt concentration DSL reduces markedly, up to the point where colloids are nearly immobilized. This peculiar retardation probably originates from potential traps and barriers at pore intersections due to deviations from cylinder symmetry in the double layer interactions between tracers and pore walls. This indicates that diffusion of charged particles in tortuous porous media may be very different from transport in long capillaries without such intersections.

  16. Measuring the relative hydrogen-bonding strengths of alcohols in aprotic organic solvents.

    Science.gov (United States)

    Tessensohn, Malcolm E; Lee, Melvyn; Hirao, Hajime; Webster, Richard D

    2015-01-12

    Voltammetric experiments with 9,10-anthraquinone and 1,4-benzoquinone performed under controlled moisture conditions indicate that the hydrogen-bond strengths of alcohols in aprotic organic solvents can be differentiated by the electrochemical parameter ΔEp (red) =|Ep (red(1)) -Ep (red(2)) |, which is the potential separation between the two one-electron reduction processes. This electrochemical parameter is inversely related to the strength of the interactions and can be used to differentiate between primary, secondary, tertiary alcohols, and even diols, as it is sensitive to both their steric and electronic properties. The results are highly reproducible across two solvents with substantially different hydrogen-bonding properties (CH3 CN and CH2 Cl2 ) and are supported by density functional theory calculations. This indicates that the numerous solvent-alcohol interactions are less significant than the quinone-alcohol hydrogen-bonding interactions. The utility of ΔEp (red) was illustrated by comparisons between 1) 3,3,3-trifluoro-n-propanol and 1,3-difluoroisopropanol and 2) ethylene glycol and 2,2,2-trifluoroethanol. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Empirical parameters for solvent acidity, basicity, dipolarity, and polarizability of the ionic liquids [BMIM][BF4] and [BMIM][PF6].

    Science.gov (United States)

    del Valle, J C; García Blanco, F; Catalán, J

    2015-04-02

    The empirical solvent scales for polarizability (SP), dipolarity (SdP), acidity (SA), and basicity (SB) have been successfully used to interpret the solvatochromism of compounds dissolved in organic solvents and their solvent mixtures. Providing that the published solvatochromic parameters for the ionic liquids 1-(1-butyl)-3-methylimidazolium tetrafluoroborate, [BMIM][BF4] and 1-(1-butyl)-3-methylimidazolium hexafluorophosphate, [BMIM][PF6], are excessively widespread, their SP, SdP, SA, and SB values are measured herein at temperatures from 293 to 353 K. Four key points are emphasized herein: (i) the origin of the solvatochromic solvent scales--the gas phase, that is the absence of any medium perturbation--; (ii) the separation of the polarizability and dipolarity effects; (iii) the simplification of the probing process in order to obtain the solvatochromic parameters; and (iv) the SP, SdP, SA, and SB solvent scales can probe the polarizability, dipolarity, acidity, and basicity of ionic liquids as well as of organic solvents and water-organic solvent mixtures. From the multiparameter approach using the four pure solvent scales one can draw the conclusion that (a) the solvent influence of [BMIM][BF4] parallels that of formamide at 293 K, both of them miscible with water; (b) [BMIM][PF6] shows a set of solvatochromic parameters similar to that of chloroacetonitrile, both of them water insoluble; and (c) that the corresponding solvent acidity and basicity of the ionic liquids can be explained to a great extent from the cation species by comparing the empirical parameters of [BMIM](+) with those of the solvent 1-methylimidazole. The insolubility of [BMIM][PF6] in water as compared to [BMIM][BF4] is tentatively connected to some extent to the larger molar volume of the anion [PF6](-), and to the difference in basicity of [PF6](-) and [BF4](-).

  18. Effective visualization assay for alcohol content sensing and methanol differentiation with solvent stimuli-responsive supramolecular ionic materials.

    Science.gov (United States)

    Zhang, Li; Qi, Hetong; Wang, Yuexiang; Yang, Lifen; Yu, Ping; Mao, Lanqun

    2014-08-05

    This study demonstrates a rapid visualization assay for on-spot sensing of alcohol content as well as for discriminating methanol-containing beverages with solvent stimuli-responsive supramolecular ionic material (SIM). The SIM is synthesized by ionic self-assembling of imidazolium-based dication C10(mim)2 and dianionic 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in water and shows water stability, a solvent stimuli-responsive property, and adaptive encapsulation capability. The rationale for the visualization assay demonstrated here is based on the combined utilization of the unique properties of SIM, including its water stability, ethanol stimuli-responsive feature, and adaptive encapsulation capability toward optically active rhodamine 6G (Rh6G); the addition of ethanol into a stable aqueous dispersion of Rh6G-encapsulated SIM (Rh6G-SIM) destructs the Rh6G-SIM structure, resulting in the release of Rh6G from SIM into the solvent. Alcohol content can thus be visualized with the naked eyes through the color change of the dispersion caused by the addition of ethanol. Alcohol content can also be quantified by measuring the fluorescence line of Rh6G released from Rh6G-SIM on a thin-layer chromatography (TLC) plate in response to alcoholic beverages. By fixing the diffusion distance of the mobile phase, the fluorescence line of Rh6G shows a linear relationship with alcohol content (vol %) within a concentration range from 15% to 40%. We utilized this visualization assay for on-spot visualizing of the alcohol contents of three Chinese commercial spirits and discriminating methanol-containing counterfeit beverages. We found that addition of a trace amount of methanol leads to a large increase of the length of Rh6G on TLC plates, which provides a method to identify methanol adulterated beverages with labeled ethanol content. This study provides a simple yet effective assay for alcohol content sensing and methanol differentiation.

  19. Ionic Liquids as Solvents for Rhodium and Platinum Catalysts Used in Hydrosilylation Reaction

    Directory of Open Access Journals (Sweden)

    Witold Zielinski

    2016-08-01

    Full Text Available A group of imidazolium and pyridinium based ionic liquids has been synthetized, and their ability to dissolve and activate the catalysts used in hydrosilylation reaction of 1-octane and 1,1,1,3,5,5,5-heptamethyltrisiloxane was investigated. An organometallic catalyst as well as inorganic complexes of platinum and rhodium dissolved in ionic liquids were used, forming liquid solutions not miscible with the substrates or with the products of the reaction. The results show that application of such a simple biphasic catalytic system enables reuse of ionic liquid phase with catalysts in multiple reaction cycles reducing the costs and decreasing the amount of catalyst needed per mole of product.

  20. Electrohydrodynamics in nanochannels coated by mixed polymer brushes: effects of electric field strength and solvent quality

    Science.gov (United States)

    Cao, Qianqian; Tian, Xiu; You, Hao

    2018-04-01

    We examine the electrohydrodynamics in mixed polymer brush-coated nanochannels and the conformational dynamics of grafted polymers using molecular dynamics simulations. Charged (A) and neutral polymers (B) are alternately grafted on the channel surfaces. The effects of the electric field strength and solvent quality are addressed in detail. The dependence of electroosmotic flow characteristics and polymer conformational behavior on the solvent quality is influenced due to the change of the electric field strength. The enhanced electric field induces a collapse of the neutral polymer chains which adopt a highly extended conformation along the flow direction. However, the thickness of the charged polymer layer is affected weakly by the electric field, and even a slight swelling is identified for the A-B attraction case, implying the conformational coupling between two polymer species. Furthermore, the charged polymer chains incline entirely towards the electric field direction oppositely to the flow direction. More importantly, unlike the neutral polymer chains, the shape factor of the charged polymer chains, which is used to describe the overall shape of polymer chains, is reduced significantly with increasing the electric field strength, corresponding to a more coiled structure.

  1. Reassessment of pH reference values with improved methodology for the evaluation of ionic strength

    International Nuclear Information System (INIS)

    Lito, M.J. Guiomar H.M.; Camoes, M. Filomena G.F.C.

    2005-01-01

    The conflict between pH as empirical number in routine control and the pH value regarded as conveying some information concerning the effective concentration or activity of hydrogen ions, a H , has caused much confusion. There are, however, reasons to conclude that the overwhelming amount of thermodynamic data is not sufficiently accurate--either due to ignorance of metrological concepts or due to insufficiently specified measurement processes of fundamental chemical quantities pH. The commonly used seven reference buffer solutions to which primary pH values have been conventional assigned, represent a selection out of a more extensive list, recommended by NBS (now NIST) in 1962. From then onwards conventions concerning the Debye-Hueckel model of electrolyte solutions and ionic strength have been revised and the pH(S) values reassessed in conformity but only for these seven reference buffer solutions. The others have, so far remained unchanged, locking harmonisation of the conventionally assigned pH(S) values. In this work, ionic strength is calculated through complete equations derived from the acidity constants. Concentrations of the various species involved in the conventional assignment of pH and their corresponding activity coefficients are therefore, more rigorously known. The process proves particularly useful for poliprotic acids with overlapping acidity constants, where the ratio is less than 10 3 . As a consequence, conventionally assigned pH values of reference buffer solutions are recalculated and corrections are introduced as appropriate

  2. Ionic Strength Modulation of the Free Energy Landscape of Aβ40 Peptide Fibril Formation.

    Science.gov (United States)

    Abelein, Axel; Jarvet, Jüri; Barth, Andreas; Gräslund, Astrid; Danielsson, Jens

    2016-06-01

    Protein misfolding and formation of cross-β structured amyloid fibrils are linked to many neurodegenerative disorders. Although recently developed quantitative approaches have started to reveal the molecular nature of self-assembly and fibril formation of proteins and peptides, it is yet unclear how these self-organization events are precisely modulated by microenvironmental factors, which are known to strongly affect the macroscopic aggregation properties. Here, we characterize the explicit effect of ionic strength on the microscopic aggregation rates of amyloid β peptide (Aβ40) self-association, implicated in Alzheimer's disease. We found that physiological ionic strength accelerates Aβ40 aggregation kinetics by promoting surface-catalyzed secondary nucleation reactions. This promoted catalytic effect can be assigned to shielding of electrostatic repulsion between monomers on the fibril surface or between the fibril surface itself and monomeric peptides. Furthermore, we observe the formation of two different β-structured states with similar but distinct spectroscopic features, which can be assigned to an off-pathway immature state (Fβ*) and a mature stable state (Fβ), where salt favors formation of the Fβ fibril morphology. Addition of salt to preformed Fβ* accelerates transition to Fβ, underlining the dynamic nature of Aβ40 fibrils in solution. On the basis of these results we suggest a model where salt decreases the free-energy barrier for Aβ40 folding to the Fβ state, favoring the buildup of the mature fibril morphology while omitting competing, energetically less favorable structural states.

  3. Peroxidase-mediated polymerization of 1-naphthol: impact of solution pH and ionic strength.

    Science.gov (United States)

    Bhandari, Alok; Xu, Fangxiang; Koch, David E; Hunter, Robert P

    2009-01-01

    Peroxidase-mediated oxidation has been proposed as a treatment method for naphthol-contaminated water. However, the impact of solution chemistry on naphthol polymerization and removal has not been documented. This research investigated the impact of pH and ionic strength on peroxidase-mediated removal of 1-naphthol in completely mixed batch reactors. The impact of hydrogen peroxide to 1-naphthol ratio and activity of horseradish peroxidase was also studied. Size exclusion chromatography was used to estimate the molecular weight distribution of oligomeric products, and liquid chromatography/mass spectrometry was used to estimate product structure. Naphthol transformation decreased with ionic strength, and substrate removal was lowest at neutral pHs. Solution pH influenced the size and the composition of the oligomeric products. An equimolar ratio of H(2)O(2):naphthol was sufficient for optimal naphthol removal. Polymerization products included naphthoquinones and oligomers derived from two, three, and four naphthol molecules. Our results illustrate the importance of water chemistry when considering a peroxidase-based approach for treatment of naphthol-contaminated waters.

  4. pH and ion strength modulated ionic species loading in mesoporous silica nanoparticles

    International Nuclear Information System (INIS)

    Liu, Wei; Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Yang, Meng; Li, Li; Xu, Jianguo

    2013-01-01

    Mesoporous silica nanoparticles (MSN) have emerged as appealing host materials to accommodate guest molecules for biomedical applications, and recently various methods have been developed to modulate the loading of guest molecules in the silica matrix. Herein, it was demonstrated that pH and ion strength showed great influence on the loading of charged species into the nanoparticles, taking MCM-41 as a host MSN model and methylviologen (MV 2+ ) and 1,5-naphthalene disulfonate (NDS 2− ) as typical charged ionic guest molecules. As the pH increased from 3.0 to 8.0, the loading amount of MV 2+ increased gradually, while on the contrary, it decreased gradually for NDS 2− , for the solution pH changed the electrostatic interaction between the silica matrix and the ionic guest molecules. Additionally, the adding of NaCl reduced the electrostatic interaction, which resulted in a decreasing of the electrostatic rejection and electrostatic accumulation for the molecules carrying the same and the opposite charge to the particle respectively. Thus, pH and ion strength can be employed as simple approaches to modulate the loading of charged molecules and permselectivity in MSN. This work has a definite guidance function for molecule loading, transport modulation, controlled release as well as sensors based on MSN. (paper)

  5. Adsorption of barium on kaolinite, illite and montmorillonite at various ionic strengths

    Energy Technology Data Exchange (ETDEWEB)

    Atun, G.; Bascetin, E. [Istanbul Univ., Dept. of Chemistry, Istanbul (Turkey)

    2003-07-01

    The sorption behaviour of Ba{sup 2+} in three different clay minerals from various regions of Turkey has been investigated by means of a tracer technique using {sup 133}Ba in batch experiments. Sorption of Ba{sup 2+} on montmorillonite, kaolinite and illite has been studied in mixed solutions of BaCl{sub 2} and NaCl at ionic strengths ranging from 1 x 10{sup -3}M to 1 x 10{sup -1}M. The L-shape exchange isotherms for Ba{sup 2+}-Na{sup +} systems are well defined by a Langmuir type equation. The exchange capacity of Ba{sup 2+} ions for all three clay minerals increased with decreasing ionic strength. The adsorption data were fitted to a Freundlich isotherm and empirical Freundlich parameters enabled to the generation of a site distribution function. The selectivity coefficients were nearly constant at low Ba loading and decreased as loading increased. This behavior was an indication of an ion exchange process between Ba{sup 2+} and Na{sup +} ions.

  6. Effects of pH and ionic strength on the thermodynamics of human serum albumin-photosensitizer binding

    International Nuclear Information System (INIS)

    Jones, Cecil L.; Dickson, TiReJe; Hayes, Ronald; Thomas, Lana

    2012-01-01

    Highlights: ► The pH dependence of entropy and enthalpy changes was determined for zinc phthalocyanine tetrasulfonic acid, ZnPcS 4 binding to human serum albumin, HSA. ► The ionic strength dependence of entropy and enthalpy changes was determined for ZnPcS 4 acid binding to HSA. ► The primary driving force governing the interaction between ZnPcS 4 and HSA over the range of pH and ionic strength was solution dynamics. ► The interplay between entropy and enthalpy changes was demonstrated. - Abstract: Fluorescence spectroscopy was used to measure the effects of pH and ionic strength on thermodynamic parameters governing the interaction of human serum albumin with zinc phthalocyanine tetrasulfonic acid. Fluorescence emission of zinc phthalocyanine increases at 686 nm with increasing concentrations of the protein. The non-linear correlation between protein concentration and emission of the photosensitizer was fitted using Chipman's analysis to calculate the binding affinities. The standard enthalpy and entropy changes were estimated from van’t Hoff analysis of data that were acquired from temperature ramping studies. Results show that reaction is primarily driven by solution dynamics and that the change in enthalpy for the system becomes increasingly unfavorable with increasing pH and ionic strength. The effect of ionic strength on the entropy change for binding is shown to be significantly greater than the effects of pH. The interplay between entropy and enthalpy changes is demonstrated.

  7. Sorption behaviour of Np(IV) on illite, shale and MX-80 in high ionic strength solutions

    International Nuclear Information System (INIS)

    Shinya Nagasaki; Riddoch, Justin; Goguen, Jared; Walker, Andrew; Tammy Tianxiao Yang

    2017-01-01

    The dependence of sorption distribution coefficient (K_d) of Np(IV) for illite, shale and MX-80 was investigated as a function of pH_c and ionic strength (I) under high ionic strength, reducing conditions. The overall trends of K_d on three solids were independent of pH_c at 5 ≤ pH_c ≤ 10 and I at 0.5 M ≤ I ≤ 6 M. The surface complexation constants of Np(IV) sorption on illite and MX-80 were estimated by the 2 SPNE SC/CE model. The sorption model well predicted the pH_c dependence of K_d, but could not completely describe the ionic strength dependence. (author)

  8. Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent.

    Science.gov (United States)

    Kavitha, T; Attri, Pankaj; Venkatesu, Pannuru; Devi, R S Rama; Hofman, T

    2012-04-19

    Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R(4)N](+) with commonly used anion hydroxide [OH](-) were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R(4)N](+)[OH](-) are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH(3))(4)N](+)[OH](-) (TMAH), tetraethyl ammonium hydroxide [(C(2)H(5))(4)N](+)[OH](-) (TEAH), tetrapropyl ammonium hydroxide [(C(3)H(7))(4)N](+)[OH](-) (TPAH) and tetrabutyl ammonium hydroxide [(C(4)H(9))(4)N](+)[OH](-) (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (V(E)), the deviation in isentropic compressibility (Δκ(s)) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich-Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7.

  9. The effect of organic solvents on one-bottle adhesives' bond strength to enamel and dentin.

    Science.gov (United States)

    Reis, André Figueiredo; Oliveira, Marcelo Tavares; Giannini, Marcelo; De Goes, Mário Fernando; Rueggeberg, Frederick A

    2003-01-01

    This study evaluated the microtensile bond strength (pTBS) of ethanol/water- and acetone-based, one-bottle adhesive systems to enamel (E) and dentin (D) in the presence (P) or absence (A) of their respective solvents. Thirty-two freshly extracted third molars were flattened with 600-grit SiC paper and restored with Single Bond (SB) or Prime&Bond 2.1 (PB) according to the manufacturers' instructions and after full solvent elimination. The molars were divided into eight test groups (n = 4): G1-SB-E-P, G2-SB-E-A, G3-PBE-P, G4-PB-E-A, G5-SB-D-P, G6-SB-D-A, G7-PB-D-P and G8-PB-D-A. After applying the adhesive resins, composite crowns of approximately 8 mm were built up with TPH Spectrum composite. After 24-hour water storage, the specimens were serially sectioned bucco-lingually to obtain 0.8 mm slabs that were trimmed to an hourglass shape, approximately 0.8 mm2 at the bonded interface. The specimens were tested in tension using a universal testing machine (0.5 mm/minute). The results were statistically analyzed by ANOVA and Tukey test. The frequency of fracture mode was compared using the Kruskal-Wallis test. There were no statistically significant differences in mean bond strength among the groups restored with or without solvent for enamel. However, the results were significantly different for the dentin groups (MPa): G5-26.2 +/- 8.6a; G7-23.6 +/- 11.3ab; G6-12.8 +/- 2.1bc; G8-6.2 +/- 3.1c. SEM examination indicated that the dentin group failure modes were significantly different from the enamel groups. The results suggest that the presence of organic solvents does not influence microTBS to enamel. However, microTBS to dentin was significantly affected by the absence of solvents in the adhesive system.

  10. Protein fouling in carbon nanotubes enhanced ultrafiltration membrane: Fouling mechanism as a function of pH and ionic strength

    KAUST Repository

    Lee, Jieun; Jeong, Sanghyun; Ye, Yun; Chen, Vicki; Vigneswaran, Saravanamuthu; Leiknes, TorOve; Liu, Zongwen

    2016-01-01

    The protein fouling behavior was investigated in the filtration of the multiwall carbon nanotube (MWCNT) composite membrane and commercial polyethersulfone ultrafiltration (PES-UF) membrane. The effect of solution chemistry such as pH and ionic strength on the protein fouling mechanism was systematically examined using filtration model such as complete pore blocking, intermediate pore blocking and cake layer formation. The results showed that the initial permeate flux pattern and fouling behavior of the MWCNT composite membrane were significantly influenced by pH and ionic strength while the effect of PES-UF membrane on flux was minimal. In a lysozyme (Lys) filtration, the severe pore blocking in the MWCNT membrane was made by the combined effect of intra-foulant interaction (Lys-Lys) and electrostatic repulsion between the membrane surface and the foulant at pH 4.7 and 10.4, and increasing ionic strength where the foulant-foulant interaction and membrane-fouling interaction were weak. In a bovine serum albumin (BSA) filtration, severe pore blocking was reduced by less deposition via the electrostatic interaction between the membrane and foulant at pH 4.7 and 10.4 and increasing ionic strength, at which the interaction between the membrane and BSA became weak. For binary mixture filtration, the protein fouling mechanism was more dominantly affected by foulant-foulant interaction (Lys-BSA, Lys-Lys, and BSA-BSA) at pH 7.0 and increase in ionic strength. This research demonstrates that MWCNT membrane fouling can be alleviated by changing pH condition and ionic strength based on the foulant-foulant interaction and the electrostatic interaction between the membrane and foulant.

  11. Protein fouling in carbon nanotubes enhanced ultrafiltration membrane: Fouling mechanism as a function of pH and ionic strength

    KAUST Repository

    Lee, Jieun

    2016-11-04

    The protein fouling behavior was investigated in the filtration of the multiwall carbon nanotube (MWCNT) composite membrane and commercial polyethersulfone ultrafiltration (PES-UF) membrane. The effect of solution chemistry such as pH and ionic strength on the protein fouling mechanism was systematically examined using filtration model such as complete pore blocking, intermediate pore blocking and cake layer formation. The results showed that the initial permeate flux pattern and fouling behavior of the MWCNT composite membrane were significantly influenced by pH and ionic strength while the effect of PES-UF membrane on flux was minimal. In a lysozyme (Lys) filtration, the severe pore blocking in the MWCNT membrane was made by the combined effect of intra-foulant interaction (Lys-Lys) and electrostatic repulsion between the membrane surface and the foulant at pH 4.7 and 10.4, and increasing ionic strength where the foulant-foulant interaction and membrane-fouling interaction were weak. In a bovine serum albumin (BSA) filtration, severe pore blocking was reduced by less deposition via the electrostatic interaction between the membrane and foulant at pH 4.7 and 10.4 and increasing ionic strength, at which the interaction between the membrane and BSA became weak. For binary mixture filtration, the protein fouling mechanism was more dominantly affected by foulant-foulant interaction (Lys-BSA, Lys-Lys, and BSA-BSA) at pH 7.0 and increase in ionic strength. This research demonstrates that MWCNT membrane fouling can be alleviated by changing pH condition and ionic strength based on the foulant-foulant interaction and the electrostatic interaction between the membrane and foulant.

  12. Intensification of the Use of Ionic Liquids as Efficient Reaction Co-Solvents in Asymmetric Hydrogenations

    Czech Academy of Sciences Publication Activity Database

    Černá, I.; Klusoň, Petr; Bendová, Magdalena; Floriš, Tomáš; Pelantová, Helena; Pekárek, T.

    2011-01-01

    Roč. 50, č. 3 (2011), s. 264-272 ISSN 0255-2701 R&D Projects: GA AV ČR KAN400720701; GA AV ČR IAA400720710 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : Ionic liquids * asymmetric hydrogenations * BmimPF6 Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.924, year: 2011

  13. Ternary polymer electrolytes with 1-methylimidazole based ionic liquids and aprotic solvents

    Czech Academy of Sciences Publication Activity Database

    Reiter, Jakub; Vondrák, Jiří; Michálek, Jiří; Mička, Z.

    2006-01-01

    Roč. 52, č. 3 (2006), s. 1398-1408 ISSN 0013-4686 R&D Projects: GA MŠk LC523; GA MŽP SN/3/171/05 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40500505 Keywords : polymer gel electrolyte * ionic liquids * lithium-ion batteries Subject RIV: CA - Inorganic Chemistry Impact factor: 2.955, year: 2006

  14. Stimuli responsive ion gels based on polysaccharides and other polymers prepared using ionic liquids and deep eutectic solvents.

    Science.gov (United States)

    Prasad, Kamalesh; Mondal, Dibyendu; Sharma, Mukesh; Freire, Mara G; Mukesh, Chandrakant; Bhatt, Jitkumar

    2018-01-15

    Ion gels and self-healing gels prepared using ionic liquids (ILs) and deep eutectic solvents (DESs) have been largely investigated in the past years due to their remarkable applications in different research areas. Herewith we provide an overview on the ILs and DESs used for the preparation of ion gels, highlight the preparation and physicochemical characteristics of stimuli responsive gel materials based on co-polymers and biopolymers, with special emphasis on polysaccharides and discuss their applications. Overall, this review summarizes the fundamentals and advances in ion gels with switchable properties prepared using ILs or DESs, as well as their potential applications in electrochemistry, in sensing devices and as drug delivery vehicles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Extractive distillation with ionic liquids as solvents : selection and conceptual process design

    NARCIS (Netherlands)

    Gutierrez Hernandez, J.P.

    2013-01-01

    Extractive distillation technology is widely used in the chemical and petrochemical industries for separating azeotropic, close-boiling and low relative volatility mixtures. It uses an additional solvent in order to interact with the components of different chemical structure within the mixture. The

  16. Solubility of sulfur compounds in commercial physical solvents and an ionic liquid from Monte Carlo simulations

    NARCIS (Netherlands)

    Jamali, S.H.; Ramdin, M.; Becker, T.M.; Torres-Knoop, Ariana; Dubbeldam, D.; Buijs, W.; Vlugt, T.J.H.

    2017-01-01

    Natural gas, synthesis gas, and flue gas typically contain a large number of impurities (e.g., acidic gases), which should be removed to avoid environmental and technological problems, and to meet customer specifications. One approach is to use physical solvents to remove the acidic gases. If no

  17. Volumetric and compressibility behaviour of ionic liquid, 1-n-butyl-3-methylimidazolium hexafluorophosphate and tetrabutylammonium hexafluorophosphate in organic solvents at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Zafarani-Moattar, Mohammed Taghi [Department of Physical Chemistry, Faculty of Chemistry, Excellence of Science for New Materials and Clean Chemistry, Daneshgah Street, University of Tabriz, Tabriz, East Azarbyjan 51664 (Iran, Islamic Republic of)]. E-mail: zafarani47@yahoo.com; Shekaari, Hemayat [Department of Physical Chemistry, Faculty of Chemistry, Excellence of Science for New Materials and Clean Chemistry, Daneshgah Street, University of Tabriz, Tabriz, East Azarbyjan 51664 (Iran, Islamic Republic of)

    2006-05-15

    Density and speed of sound measurements have been made on the systems containing the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF{sub 6}]) and some organic solvents having a wide range of dielectric constants. Similar studies have been carried out for tetrabutylammonium hexafluorophosphate ([TBA][PF{sub 6}]), which has common anion ([PF{sub 6}]{sup -}) with the studied ionic liquid. For the systems investigated, the apparent molar volumes and apparent molar isentropic compressibilities were determined and fitted to the Redlich-Mayer and the Pitzer equations from which the corresponding limiting values were obtained. These limiting values were used to obtain some information about ion-solvent interactions. Furthermore, using the ionic limiting apparent volume values for [TBA]{sup +} from the literature and limiting apparent molar volume for the ionic liquid and [TBA][PF{sub 6}] obtained in this work, the ionic limiting apparent molar volume values for the cation [BMIM]{sup +} in different organic solvents were also estimated.

  18. Ionic liquids as solvents for liquid scintillation technology. Čerenkov counting with 1-Butyl-3-Methylimidazolium Chloride

    International Nuclear Information System (INIS)

    Mirenda, Martín; Rodrigues, Darío; Arenillas, Pablo; Gutkowski, Karin

    2014-01-01

    We report the detection of the Čerenkov luminescence after the incorporation of a few droplets of a physiological solution of 2-deoxi-2( 18 F)fluorine-D-glucose into the ionic liquid 1-Butyl-3-Methylimidazolium Chloride (BmimCl). The phenomenon is attributed to the β + particles having energy above the threshold energy value for the Čerenkov radiation in this medium. The presence of another type of radiation that could eventually cause coincidences in the photodetectors was safely discarded. We show that this property serves to determine the activity of a 18 F solution by means of the novel TDCR–Čerenkov technique. The results were compared with those obtained from the classic TDCR scintillation method using a commercial scintillation cocktail. The activity values obtained from both methods were found to be virtually identical within the experimental uncertainties. The fact that high energy β particles in BmimCl generates Čerenkov photons makes this ionic liquid a promising compound for future research in detection and quantification of ionizing radiation, and it provides a potential alternative for applications in nuclear technology. - Highlights: • Čerenkov luminescence was detected when 18 F was dissolved in 1-Butyl-3-Methylimidazolium Chloride (BmimCl) ionic liquid. • The presence of another type of radiation that could eventually cause coincidences in the photodetectors was safely discarded. • Čerenkov luminescence serves to determine the activity of a 18 F solution by means of TDCR–Čerenkov technique. • Some advantages of the use of BmimCl as solvent for Čerenkov counting were listed

  19. Extraction of Am(III) using novel solvent systems containing a tripodal diglycolamide ligand in room temperature ionic liquids: a 'green' approach for radioactive waste processing

    NARCIS (Netherlands)

    Sengupta, A; Mohapatra, P.K.; Iqbal, M.; Verboom, Willem; Huskens, Jurriaan; Godbole, S.V.

    2012-01-01

    Extraction of Am3+ from acidic feed solutions was investigated using novel solvent systems containing a tripodal diglycolamide (T-DGA) in three room temperature ionic liquids (RTIL), viz. [C4mim][NTf2], [C6mim][NTf2] and [C8mim][NTf2]. Compared to the results obtained with N,N,N′,N′-tetra-n-octyl

  20. Conformations of polyelectrolyte macromolecules with different charge density in solutions of different ionic strengths

    International Nuclear Information System (INIS)

    Dommes, O A; Okatova, O V; Pavlov, G M

    2016-01-01

    Studies of charged polymer chains are interesting in both fundamental and applied aspects. Especially, polyelectrolytes attract huge attention of researchers due to their ability to form interpolymer complexes with synthetic and biopolymers. The study was carried out on the fractions of hydrophilic copolymers of N-methyl-N-vinyl acetamide and N-methyl-N-vinyl amine hydrochloride of different degrees of polymerization and of different charge density using methods of molecular hydrodynamics. Hydrodynamic and conformational characteristics as well as molar masses of isolated molecules were estimated. In addition, the intrinsic viscosity of fractions was studied at the extreme ionic strengths - in distilled water (∼10 -6 M) and in 6M NaCl. Scaling relations for intrinsic viscosity, sedimentation and translational diffusion coefficients with molar mass were obtained. Conformational behavior of macromolecules with different linear charge density was compared. (paper)

  1. Effect of ionic strength, cation exchanger and inoculum age on the performance of Microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Yama; Das, Debabrata [Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302 (India)

    2009-09-15

    Power generation in Microbial fuel cells (MFCs) is a function of various physico-chemical as well as biological parameters. In this study, we have examined the effect of ionic strength, cation exchanger and inoculum age on power generation in a mediator MFC with methylene blue as electron mediator using Enterobacter cloacae IIT-BT08. The effect of ionic strength was studied using NaCl in the anode chamber of a two chambered salt-bridge MFC at concentrations of 5 mM, 10 mM and 15 mM. Maximum power density of 12.8 mW/m{sup 2} was observed when 10 mM NaCl was used. Corresponding current density was noted to be 35.5 mA/m{sup 2}. Effect of cation exchanger was observed by replacing salt-bridge with a proton exchange membrane of equal surface area. When the salt-bridge was replaced by a proton exchange membrane, a 3-fold increase in the power density was observed. Power density and current density of 37.8 mW/m{sup 2} and 110.3 mA/m{sup 2} respectively were detected. The influence of the pre-inoculum on the MFC was studied using E. cloacae IIT-BT08 grown for 12, 14, 16 and 18 h. It was observed that 16 h grown culture when inoculated in the anode chamber gave the maximum power output. Power density and current density of 68 mW/m{sup 2} and 168 mA/m{sup 2} respectively were obtained. We demonstrate from these results that both physico-chemical as well as biological parameters need to be optimized for improving the power generation in MFCs. (author)

  2. Complexation study of NpO2+ and UO22+ ions with several organic ligands in aqueous solutions of high ionic strength

    International Nuclear Information System (INIS)

    Borkowski, M.; Lis, S.; Choppin, G.R.

    1995-01-01

    The acid dissociation constants, pK a , and the stability constants for NpO 2 + and UO 2 2+ have been measured for certain organic ligands [acetate, α-hydroxyisobutyrate, lactate, ascorbate, oxalate, citrate, EDTA, 8-hydroxyquinoline, 1, 10-phenanthroline, and thenoyltrifluoroacetone] in 5 m (NaCl) ionic strength solution. The pK a values were determined by potentiometry or spectrometry. These methods, as well as solvent extraction with 233 U and 237 Np radiotracers, were used to measure the stability constants of the 1:1 and 1:2 complexes of dioxo cations. These constants were used to estimate the concentrations required to result in 10 % competition with hydrolysis in the 5 m NaCl solution. Such estimates are of value in assessing the solubility from radioactive waste of AnO 2 + and AnO 2 2+ in brine solutions in contact with nuclear waste in a salt-bed repository

  3. Thermodynamics of ionic migration of simple and complex rare earth salts in mixed alcohol solvents

    International Nuclear Information System (INIS)

    Gorodyskij, A.V.; Fialkov, Yu.Ya.; Chernyj, D.B.

    1982-01-01

    The influence of the composition of double mixed solvents (water-methanol and methanol-propanol) on thermodynamic characteristics of electrolytic dissociation process-enthalpy and entropy, dissociation constants of chlorides and diphenanthroline chlorides of lanthanum, neodymium, europium and dysprosium, is analyzed. It is shown that when passing from water to methanol, that is, with decrease of dielectric permeability, the endothermicity of electrolytic dissociation process increases

  4. Thermodynamics of ionic migration of simple and complex rare earth salts in mixed alcohol solvents

    Energy Technology Data Exchange (ETDEWEB)

    Gorodyskij, A.V.; Fialkov, Yu.Ya.; Chernyj, D.B. (AN Ukrainskoj SSR, Kiev. Inst. Obshchej i Neorganicheskoj Khimii; Kievskij Politekhnicheskij Inst. (Ukrainian SSR))

    1982-04-01

    The influence of the composition of double mixed solvents (water-methanol and methanol-propanol) on thermodynamic characteristics of electrolytic dissociation process-enthalpy and entropy, dissociation constants of chlorides and diphenanthroline chlorides of lanthanum, neodymium, europium and dysprosium, is analyzed. It is shown that when passing from water to methanol, that is, with decrease of dielectric permeability, the endothermicity of electrolytic dissociation process increases.

  5. Inkjet-printed gold nanoparticle chemiresistors: Influence of film morphology and ionic strength on the detection of organics dissolved in aqueous solution

    International Nuclear Information System (INIS)

    Chow, Edith; Herrmann, Jan; Barton, Christopher S.; Raguse, Burkhard; Wieczorek, Lech

    2009-01-01

    The influence of film morphology on the performance of inkjet-printed gold nanoparticle chemiresistors has been investigated. Nanoparticles deposited from a single-solvent system resulted in a 'coffee ring'-like structure with most of the materials deposited at the edge. It was shown that the uniformity of the film could be improved if the nanoparticles were deposited from a mixture of solvents comprising N-methyl-2-pyrrolidone and water. Electrical conductivity measurements showed that both 'coffee ring' and 'flat' films were qualitatively similar suggesting that the films have similar nanoscale structures. To form the functional chemiresistor device, the 4-(dimethylamino)pyridine coating on the nanoparticle was exchanged with 1-hexanethiol to provide a hydrophobic sensing layer. The performance of 1-hexanethiol coated gold nanoparticle chemiresistors to small organic molecules, toluene, dichloromethane and ethanol dissolved in 1 M KCl in regard to changes in impedance and response times was unaffected by the film morphology. For larger hydrocarbons such as octane, the rate of uptake of the analyte into the film was significantly faster when the flatter nanoparticle film was used as opposed to the 'coffee ring' film which has a thicker edge. Furthermore, the presence of potassium and chloride ions in the solution media does not significantly affect the impedance of the nanoparticle film at 1 Hz (<2% variation in film impedance over more than four orders of magnitude change in ionic strength). However, the ionic strength of the media affected the partitioning of the analyte into the hydrophobic nanoparticle film. The response of the sensor was found to increase with an increased salt concentration due to a salting-out of the analyte from the solution

  6. Inkjet-printed gold nanoparticle chemiresistors: Influence of film morphology and ionic strength on the detection of organics dissolved in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Edith [CSIRO Materials Science and Engineering, PO Box 218, Lindfield, NSW 2070 (Australia)], E-mail: Edith.Chow@csiro.au; Herrmann, Jan; Barton, Christopher S.; Raguse, Burkhard; Wieczorek, Lech [CSIRO Materials Science and Engineering, PO Box 218, Lindfield, NSW 2070 (Australia)

    2009-01-19

    The influence of film morphology on the performance of inkjet-printed gold nanoparticle chemiresistors has been investigated. Nanoparticles deposited from a single-solvent system resulted in a 'coffee ring'-like structure with most of the materials deposited at the edge. It was shown that the uniformity of the film could be improved if the nanoparticles were deposited from a mixture of solvents comprising N-methyl-2-pyrrolidone and water. Electrical conductivity measurements showed that both 'coffee ring' and 'flat' films were qualitatively similar suggesting that the films have similar nanoscale structures. To form the functional chemiresistor device, the 4-(dimethylamino)pyridine coating on the nanoparticle was exchanged with 1-hexanethiol to provide a hydrophobic sensing layer. The performance of 1-hexanethiol coated gold nanoparticle chemiresistors to small organic molecules, toluene, dichloromethane and ethanol dissolved in 1 M KCl in regard to changes in impedance and response times was unaffected by the film morphology. For larger hydrocarbons such as octane, the rate of uptake of the analyte into the film was significantly faster when the flatter nanoparticle film was used as opposed to the 'coffee ring' film which has a thicker edge. Furthermore, the presence of potassium and chloride ions in the solution media does not significantly affect the impedance of the nanoparticle film at 1 Hz (<2% variation in film impedance over more than four orders of magnitude change in ionic strength). However, the ionic strength of the media affected the partitioning of the analyte into the hydrophobic nanoparticle film. The response of the sensor was found to increase with an increased salt concentration due to a salting-out of the analyte from the solution.

  7. Solvent-Controlled Assembly of ionic Metal-Organic Frameworks Based on Indium and Tetracarboxylate Ligand: Topology Variety and Gas Sorption Properties

    KAUST Repository

    Zheng, Bing

    2016-07-15

    Four Metal-Organic Frameworks (MOFs) based on Indium and tetracarboxylate ligand have been synthesized through regulation of the solvent conditions, the resulted compounds not only exhibited rich structural topologies (pts, soc and unique topologies), but also interesting charge reversal framework features. By regulating the solvent, different building units (indium monomer, trimer) have been generated in situ, and they are connected with the ligand to form ionic frameworks 1-4, respectively. Among the synthesized four ionic frameworks, compounds 3 and 4 could keep their crystallinity upon heating temperature up to 300oC after fully removal of solvent guest molecules, they also exhibit the charge reversal framework features (3 adopts an overall cationic framework, while 4 has an anionic framework). Both compounds 3 and 4 exhibit significant uptake capacity for CO2 and H2, besides that, compounds 3 and 4 also present excellent selective adsorption of CO2 over N2 and CH4.

  8. Solvent-Controlled Assembly of ionic Metal-Organic Frameworks Based on Indium and Tetracarboxylate Ligand: Topology Variety and Gas Sorption Properties

    KAUST Repository

    Zheng, Bing; Sun, Xiaodong; Li, Guanghua; Cairns, Amy; Kravtsov, Victor; Huo, Qisheng; Liu, Yunling; Eddaoudi, Mohamed

    2016-01-01

    Four Metal-Organic Frameworks (MOFs) based on Indium and tetracarboxylate ligand have been synthesized through regulation of the solvent conditions, the resulted compounds not only exhibited rich structural topologies (pts, soc and unique topologies), but also interesting charge reversal framework features. By regulating the solvent, different building units (indium monomer, trimer) have been generated in situ, and they are connected with the ligand to form ionic frameworks 1-4, respectively. Among the synthesized four ionic frameworks, compounds 3 and 4 could keep their crystallinity upon heating temperature up to 300oC after fully removal of solvent guest molecules, they also exhibit the charge reversal framework features (3 adopts an overall cationic framework, while 4 has an anionic framework). Both compounds 3 and 4 exhibit significant uptake capacity for CO2 and H2, besides that, compounds 3 and 4 also present excellent selective adsorption of CO2 over N2 and CH4.

  9. Controlling the transport of cations through permselective mesoporous alumina layers by manipulation of electric field and ionic strength

    NARCIS (Netherlands)

    Schmuhl, R.; Keizer, Klaas; van den Berg, Albert; ten Elshof, Johan E.; Blank, David H.A.

    2004-01-01

    The electric field-driven transport of ions through supported mesoporous γ-alumina membranes was investigated. The influence of ion concentration, ion valency, pH, ionic strength, and electrolyte composition on transport behavior was determined. The permselectivity of the membrane was found to be

  10. Polyelectrolyte multilayer assembly as a function of pH and ionic strength using the polysaccharides chitosan and heparin.

    Science.gov (United States)

    Boddohi, Soheil; Killingsworth, Christopher E; Kipper, Matt J

    2008-07-01

    The goal of this work is to explore the effects of solution ionic strength and pH on polyelectrolyte multilayer (PEM) assembly, using biologically derived polysaccharides as the polyelectrolytes. We used the layer-by-layer (LBL) technique to assemble PEM of the polysaccharides heparin (a strong polyanion) and chitosan (a weak polycation) and characterized the sensitivity of the PEM composition and layer thickness to changes in processing parameters. Fourier-transform surface plasmon resonance (FT-SPR) and spectroscopic ellipsometry provided in situ and ex situ measurements of the PEM thickness, respectively. Vibrational spectroscopy and X-ray photoelectron spectroscopy (XPS) provided details of the chemistry (i.e., composition, electrostatic interactions) of the PEM. We found that when PEM were assembled from 0.2 M buffer, the PEM thickness could be increased from less than 2 nm per bilayer to greater than 4 nm per bilayer by changing the solution pH; higher and lower ionic strength buffer solutions resulted in narrower ranges of accessible thickness. Molar composition of the PEM was not very sensitive to solution pH or ionic strength, but pH did affect the interactions between the sulfonates in heparin and amines in chitosan when PEM were assembled from 0.2 M buffer. Changes in the PEM thickness with pH and ionic strength can be interpreted through descriptions of the charge density and conformation of the polyelectrolyte chains in solution.

  11. Ionic strength dependence of the oxidation of SO2 by H2O2 in sodium chloride particles

    Science.gov (United States)

    Ali, H. M.; Iedema, M.; Yu, X.-Y.; Cowin, J. P.

    2014-06-01

    The reaction of sulfur dioxide and hydrogen peroxide in the presence of deliquesced (>75% RH) sodium chloride (brine) particles was studied by utilizing a cross flow mini-reactor. The reaction kinetics were followed by observing chloride depletion in particles by computer-controlled scanning electron microscope with energy dispersive X-ray analysis, namely CCSEM/EDX. The reactions take place in concentrated mixed salt brine aerosols, for which no complete kinetic equilibrium data previously existed. We measured the Henry's law solubility of H2O2 in brine solutions to close that gap. We also calculated the reaction rate as the particle transforms continuously from concentrated NaCl brine to, eventually, a mixed NaHSO4 plus H2SO4 brine solution. The reaction rate of the SO2 oxidation by H2O2 was found to be influenced by the change in ionic strength as the particle undergoes compositional transformation, following closely the dependence of the third order rate constant on ionic strength as predicted using established rate equations. This is the first study that has measured the ionic strength dependence of sulfate formation (in non-aqueous media) from oxidation of mixed salt brine aerosols in the presence of H2O2. It also gives the first report of the dependence of the Henry's law constant of H2O2 on ionic strength.

  12. Effect of free calcium concentration and ionic strength on alginate fouling in cross-flow membrane filtration

    NARCIS (Netherlands)

    Brink, van den P.; Zwijnenburg, A.; Smith, G.; Temmink, B.G.; Loosdrecht, van M.C.

    2009-01-01

    Extracellular polymeric substances (EPS) are generally negatively charged polymers. Membrane fouling in membrane bioreactors (MBRs) by EPS is therefore influenced by the water chemistry of the mixed liquor (calcium concentration, foulant concentration and ionic strength). We used alginate as a model

  13. A model of mitochondrial creatine kinase binding to membranes: adsorption constants, essential amino acids and the effect of ionic strength

    DEFF Research Database (Denmark)

    Fedosov, Sergey; Belousova, Lubov; Plesner, Igor

    1993-01-01

    The quantitative aspects of mitochondrial creatinekinase (mitCK) binding to mitochondrial membranes were investigated. A simple adsorption and binding model was used for data fitting, taking into account the influence of protein concentration, pH, ionic strength and substrate concentration on the...

  14. Soy Glycenin: Influence of pH and Ionic Strength on Solubility and Molecular Structure at Ambient Temperatures

    NARCIS (Netherlands)

    Lakemond, C.M.M.; Jongh, de H.H.J.; Hessing, M.; Gruppen, H.; Voragen, A.G.J.

    2000-01-01

    This study describes the relationship between the solubility of glycinin, a major soy protein, and its structural properties at a quaternary, tertiary, and secondary folding level under conditions representative for food products. When the ionic strength is lowered from 0.5 to 0.2 or 0.03, the basic

  15. On the addition of conducting ceramic nanoparticles in solvent-free ionic liquid electrolyte for dye-sensitized solar cells

    KAUST Repository

    Lee, Chuan-Pei

    2009-08-01

    Titanium carbide (TiC) is an extremely hard conducting ceramic material often used as a coating for titanium alloys as well as steel and aluminum components to improve their surface properties. In this study, conducting ceramic nanoparticles (CCNPs) have been used, for the first time, in dye-sensitized solar cells (DSSCs), and the incorporation of TiC nanoparticles in a binary ionic liquid electrolyte on the cell performance has been investigated. Cell conversion efficiency with 0.6 wt% TiC reached 1.68%, which was higher than that without adding TiC (1.18%); however, cell efficiency decreased when the TiC content reached 1.0 wt%. The electrochemical impedance spectroscopy (EIS) technique was employed to analyze the interfacial resistance in DSSCs, and it was found that the resistance of the charge-transfer process at the Pt counter electrode (Rct1) decreased when up to 1.0 wt% TiC was added. Presumably, this was due to the formation of the extended electron transfer surface (EETS) which facilitates electron transfer to the bulk electrolyte, resulting in a decrease of the dark current, whereby the open-circuit potential (VOC) could be improved. Furthermore, a significant increase in the fill factor (FF) for all TiC additions was related to the decrease in the series resistance (RS) of the DSSCs. However, at 1.0 wt% TiC, the largest charge-transfer resistance at the TiO2/dye/electrolyte interface was observed and resulted from the poor penetration of the electrolyte into the porous TiO2. The long-term stability of DSSCs with a binary ionic liquid electrolyte, which is superior to that of an organic solvent-based electrolyte, was also studied. © 2009 Elsevier B.V. All rights reserved.

  16. Separation of benzene from alkanes by solvent extraction with 1-ethylpyridinium ethylsulfate ionic liquid

    International Nuclear Information System (INIS)

    Gomez, Elena; Dominguez, Irene; Calvar, Noelia; Dominguez, Angeles

    2010-01-01

    The (liquid + liquid) equilibrium (LLE) data for ternary mixtures {alkane + benzene + 1-ethylpyridinium ethylsulfate ([EPy][EtSO 4 ])} at T = (283.15 and 298.15) K and atmospheric pressure are presented. The alkanes used were hexane and heptane. The cloud point method was used to determinate the binodal curve, and the tie-line compositions were obtained by density measurements. The LLE data obtained were used to calculate distribution coefficients and selectivity values. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations. Correlation of the experimental tie-lines was conducted through the use of NRTL equation, which provides good correlation of the experimental data. The results show that [EPy][EtSO 4 ] can be used as an alternative solvent in liquid extraction processes for the removal of benzene from its mixtures with alkanes.

  17. Evaluation of thermophysical properties of ionic liquids with polar solvent: a comparable study of two families of ionic liquids with various ions.

    Science.gov (United States)

    Govinda, Varadhi; Attri, Pankaj; Venkatesu, Punnuru; Venkateswarlu, Ponneri

    2013-10-17

    In this work, we explore and compare the role of the ion effect on the thermophysical properties of two families of ionic liquids (ILs), namely, tetra-alkyl ammonium cation [R4N](+) with hydroxide [OH](-) anion and 1-alkyl-3-methyl imidazolium cation [amim](+) with different anions (chloride, methyl sulfate, and tetrafluoroborate), with polar solvent such as dimethylsulfoxide (DMSO) in the temperature range from 25 to 40 °C and over the whole concentration range of ILs. Two families of ILs, namely, tetramethyl ammonium hydroxide [(CH3)4N][OH] (TMAH), tetraethyl ammonium hydroxide [(C2H5)4N][OH] (TEAH), tetrapropyl ammonium hydroxide [(C3H7)4N][OH] (TPAH), and tetrabutyl ammonium hydroxide [(C4H9)4N][OH] (TBAH) from ammonium-based ILs and 1-ethyl-3-methylimidazolium chloride [Emim][Cl], 1-ethyl-3-methylimidazolium methylsulfate [Emim][MeSO4], 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4], and 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) from imidazolium family of ILs, are used in the present study. To address the molecular interactions of ILs with DMSO, densities (ρ), ultrasonic sound velocities (u), and viscosities (η) have been measured over the entire composition range and at four temperatures, 25, 30, 35, and 40 °C, under atmospheric pressure. From these experimental data, the excess molar volume (V(E)), the deviation in isentropic compressibility (Δκs), and the deviation in viscosity (Δη) were calculated and were adequately correlated by using the Redlich-Kister polynomial equation. The measured and predicted data were interpreted on the basis of intermolecular interactions and structural effects between like and unlike molecules upon mixing. The hydrogen-bonding features between ammonium-based ILs and DMSO were analyzed using molecular modeling program by HyperChem 7.

  18. Solvent extraction of Th(IV) from aqueous solution with methylimidazole in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenkui; Lv, Hui; Liu, Ziyi; Wu, Jianrong; Li, Shun; Shen, Yinglin [Lanzhou Univ. (China). Radiochemistry Lab.; Yang, Shenghua [State Key Laboratory of Applied Organic Chemistry, Lanzhou (China)

    2016-07-01

    An extraction of Th(IV) was performed using 1-methylimidazole (1-MIM) or 2-methylimidazole (2-MIM) as the extractant in imidazolium type ionic liquids (ILs) or n-pentanol. The extractability for Th{sup 4+} in ILs was by far higher than that obtained in n-pentanol. The extraction mechanism was determined by slope analysis and ESI-MS. The transfer of Th{sup 4+} with MIM into ILs proceeded through both a cationic exchange and a neutral solvation mechanism, whereas the partitioning of Th{sup 4+} with MIM into n-pentanol only underwent a neutral solvation mechanism. The thermodynamic parameters values (ΔH, ΔS and ΔG) for extraction of Th{sup 4+} with 1-MIM in IL were calculated and the results indicated the extraction reaction was spontaneous and went through endothermic process. Separation of Th{sup 4+} from the solution of lanthanides (III) and uranium was also carried out by 1-MIM in ILs and n-pentanol.

  19. Evaluating the complexation behavior and regeneration of boron selective glucaminium-based ionic liquids when used as extraction solvents

    International Nuclear Information System (INIS)

    Joshi, Manishkumar D.; Steyer, Daniel J.; Anderson, Jared L.

    2012-01-01

    Highlights: ► Glucaminium-based ILs exhibit high selectivity for boron species using DLLME. ► The concentration of glucaminium-based IL affects type of boron complex formed. ► Use of 0.1 M HCl allows for regeneration of the IL solvent following extraction. ► Selectivity of the glucaminium-based ILs for boron species in seawater is similar to Milli-Q water. - Abstract: Glucaminium-based ionic liquids are a new class of solvents capable of extracting boron-species from water with high efficiency. The complexation behavior of these ILs with borate was thoroughly studied using 11 B NMR. Two different complexes, namely, monochelate complex and bischelate complex, were observed. 11 B NMR was used extensively to determine the formation constants for monochelate and bischelate complexes. The IL concentration was observed to have a significant effect on the IL–borate complexes. Using an in situ dispersive liquid–liquid microextraction (in situ DLLME) method, the extraction efficiency for boron species was increased dramatically when lithium bis[(trifluoromethyl)sulfonyl]imide (LiNTf 2 ) was used as the metathesis salt in an aqueous solution containing 0.1 M sodium chloride. IL regeneration after extraction was achieved using 0.1 M hydrochloric acid. The extraction efficiency of boron species was consistent when the IL was employed after three regeneration cycles. The selectivity of the IL for boron species in synthetic seawater samples was similar to performing the same extraction from Milli-Q water samples.

  20. Stability of the Cadmium Complex with the Bacterial Trihydroxamate Siderophore Desferrioxamine B at Seawater Ionic Strength

    Science.gov (United States)

    Christenson, E. A.; Schijf, J.

    2010-12-01

    strength. Whereas this is orders of magnitude smaller than values for DFOB complexes of other divalent transition metals (e.g., β(Cu2+) ~ 1014), it nevertheless makes DFOB one of the strongest known biogenic Cd ligands, rivaling synthetic ligands such as NTA. We present measurements of the stability constant of the Cd(II)-DFOB complex that were obtained by potentiometric titration of DFOB in the presence of Cd in a non-complexing background electrolyte (NaClO4) at seawater ionic strength (0.7 M). The titrations were corrected for hydrolysis and also performed at different Cd:DFOB ratios to detect any polynuclear species. Stability constants were derived from non-linear regressions of the data using FITEQL4.0. The results may provide new insights into the marine biogeochemistry of cadmium and its potential effects on primary productivity.

  1. Development of a New Binary Solvent System Using Ionic Liquids as Additives to Improve Rotenone Extraction Yield from Malaysia Derris sp.

    Directory of Open Access Journals (Sweden)

    Zetty Shafiqa Othman

    2015-01-01

    Full Text Available Rotenone is one of the prominent insecticidal isoflavonoid compounds which can be isolated from the extract of Derris sp. plant. Despite being an effective compound in exterminating pests in a minute concentration, procuring a significant amount of rotenone in the extracts for commercialized biopesticides purposes is a challenge to be attained. Therefore, the objective of this study was to determine the best ionic liquid (IL which gives the highest yield of rotenone. The normal soaking extraction (NSE method was carried out for 24 hrs using five different types of binary solvent systems comprising a combination of acetone and five respective ionic liquids (ILs of (1 [BMIM] Cl; (2 [BMIM] OAc; (3 [BMIM] NTf2; (4 [BMIM] OTf; and (5 [BMPy] Cl. Next, the yield of rotenone, % (w/w, and its concentration (mg/mL in dried roots were quantitatively determined by means of RP-HPLC and TLC. The results showed that a binary solvent system of [BMIM] OTf + acetone was the best solvent system combination as compared to other solvent systems (P<0.05. It contributed to the highest rotenone content of 2.69 ± 0.21% (w/w (4.04 ± 0.34 mg/mL at 14 hrs of exhaustive extraction time. In conclusion, a combination of the ILs with a selective organic solvent has been proven to increase a significant amount of bioactive constituents in the phytochemical extraction process.

  2. Viscosity of binary mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid with four organic solvents

    International Nuclear Information System (INIS)

    Ciocirlan, Oana; Croitoru, Oana; Iulian, Olga

    2016-01-01

    Highlights: • Viscosities of four binary mixtures of [Emim][BF4] with organic solvents. • Viscosity models based on Eyring’s theory. • Excess functions calculated. • Data for binaries new in the literature, except for system with DMSO. - Abstract: This paper reports experimental values of dynamic viscosity for four binary systems of 1-ethyl-3-methylimidazolium tetrafluoroborate, [Emim][BF4], with dimethyl sulfoxide (DMSO), acetonitrile (ACN), ethylene glycol (EG) and 1,4-dioxane over the temperature ranges from 293.15 K to 353.15 K at p = 0.1 MPa. All binary mixtures were completely miscible over the entire range of mole fraction, except the system with 1,4-dioxane. The viscosity results have been correlated by the one parameter Grunberg–Nissan and Fang and He equations and the two-parameter McAllister, Eyring-UNIQUAC, Eyring-NRTL and Eyring-Wilson models and the results were compared. Additionally, the viscosity deviations, Δη, and the excess Gibbs energy of activation for viscous flow, G"∗"E, were calculated and fitted to the Redlich–Kister equation. The results show that all Δη values are negative over the whole composition range and the G"∗"E values are positive, except for the system with EG. The results of the excess functions are discussed in terms of molecular interactions.

  3. Impact of the solution ionic strength on strontium diffusion through the Callovo-Oxfordian clayrocks: An experimental and modeling study

    International Nuclear Information System (INIS)

    Savoye, S.; Beaucaire, C.; Grenut, B.; Fayette, A.

    2015-01-01

    Highlights: • HTO and 85 Sr diffusion is studied in clayrocks under increasing ionic strengths. • Sr diffusive flux is 5 times higher than HTO under standard porewater ionic strength. • Sr diffusive flux is reduced when the porewater ionic strength increases. • The Sr diffusive evolution is qualitatively reproduced by a surface diffusion model. - Abstract: Diffusion of cations in clayrocks is widely investigated, because deep clay-rich formations are currently considered as one of the potential host rocks for radioactive waste repositories. However, several authors have already reported that sorbing cations seem to diffuse at rates larger than those predicted by a simple pore diffusion model from their sorption coefficients and from the diffusive flux of non-sorbing water tracers. This process has been attributed to the migration of cations within the electrical double layer, next to the mineral surfaces, called the surface diffusion phenomenon. The aim of this work was to verify whether this “enhanced” cation diffusion compared to neutral species was observed for strontium and, if so, to what extent this effect might vary with the salinity of the synthetic solutions. These questions were addressed by performing batch sorption, through-diffusion and out-diffusion experiments on rock samples from the Callovo-Oxfordian claystone formation (France). The results showed that there was a good agreement of the distribution ratios (R D ) determined on crushed and intact rocks by batch and through-diffusion methods with a R D decrease related to the increase of the sodium concentration, a sorption competitor. Such a trend was also well reproduced by means of a geochemical modeling based on the multi-site ion exchange (MSIE) theory. Moreover, the “enhanced” diffusion for strontium was clearly observed in this study: the Sr diffusive flux was almost five times higher than that for HTO in the cell with the lowest ionic strength, and diminished to less than 1

  4. The role of ionic strength on the mobility of uranium at ore-water interface

    International Nuclear Information System (INIS)

    Singh, Sarjan; Rout, S.; Kumar, Ajay; Ravi, P.M.; Tripathi, R.M.

    2016-01-01

    Uranium contamination of soil and groundwater is a legacy of past activities associated with the nuclear fuel cycle, continuing concern associated with current mining operations as well as weathering of uranium bearing minerals. Considerable radio-toxicity is one of the challenges for environmentalist therefore; efforts have been given in recent years to understand 'U' behavior with respect to soil-water and rock-water chemistry for safety assessment of radioactive waste disposal program. Recent studies indicate that U mobility increases at soil-water interface with increase in salinity of the water. If salinization results in increased mobility of U significantly, this would be an important additional adverse phenomenon. It should then be taken into account when evaluating the effects of salinization in the context of environmental risk assessments. Nowadays, groundwater salinization is one of the main problems in arid and semi arid regions. The objective of the study was to evaluate the role of ionic strength of the water in uranium mobilization and speciation in the binary (Ore-Water) system

  5. Structure evolution of gelatin particles induced by pH and ionic strength.

    Science.gov (United States)

    Xu, Jing; Li, Tianduo; Tao, Furong; Cui, Yuezhi; Xia, Yongmei

    2013-03-01

    Microstructure of gelatin particles played a key role in determining the physicochemical properties of gelatin. Ionic strength and pH as systematic manners were considered to affect gelatin particles structure on the micrometer scale. Scanning electron microscopy was used for depicting the morphologies of gelatin particles. Increasing pH to 10.0 or decreasing pH to 4.0, spherical, spindle, and irregular aggregates of gelatin particles at 2, 6, 10, and 14% solution (w/w) were all transformed to spindle aggregates. When NaCl was added to the system, the molecular chains of gelatin possibly rearranged themselves in a stretched state, and the ribbon aggregates was observed. The structural transitions of gelatin aggregates were strongly depended on the electrostatic repulsion. In the gelatin-sodium dodecyl sulfate (SDS) case, the micrometer scale of aggregates was larger and the different degrees of cross-links were induced through hydrophobic interaction and electrostatic repulsion. Copyright © 2012 Wiley Periodicals, Inc.

  6. Phase equilibrium study of the binary systems (N-hexyl-3-methylpyridinium tosylate ionic liquid + water, or organic solvent)

    International Nuclear Information System (INIS)

    Domanska, Urszula; Krolikowski, Marek

    2011-01-01

    Highlights: → Synthesis, DSC, and measurements of phase equilibrium of N-hexyl-3-methylpyridinium tosylate. → Solvents used: water, alcohols, benzene, alkylbenzenes, and aliphatic hydrocarbons. → Correlation with UNIQUAC, Wilson and NRTL models. → Comparison with different tosylate-based ILs. - Abstract: The (solid + liquid) phase equilibrium (SLE) and (liquid + liquid) phase equilibrium (LLE) for the binary systems ionic liquid (IL) N-hexyl-3-methylpyridinium tosylate (p-toluenesulfonate), {([HM 3 Py][TOS] + water, or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol), or an aromatic hydrocarbon (benzene, toluene, or ethylbenzene, or propylbenzene), or an alkane (n-hexane, n-heptane, n-octane)} have been determined at ambient pressure using a dynamic method. Simple eutectic systems with complete miscibility in the liquid phase were observed for the systems involving water and alcohols. The phase equilibrium diagrams of IL and aromatic or aliphatic hydrocarbons exhibit eutectic systems with immiscibility in the liquid phase with an upper critical solution temperature as for most of the ILs. The correlation of the experimental data has been carried out using the UNIQUAC, Wilson and the non-random two liquid (NRTL) correlation equations. The results reported here have been compared with analogous phase diagrams reported by our group previously for systems containing the tosylate-based ILs.

  7. Combination of deep eutectic solvent and ionic liquid to improve biocatalytic reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cell

    OpenAIRE

    Pei Xu; Peng-Xuan Du; Min-Hua Zong; Ning Li; Wen-Yong Lou

    2016-01-01

    The efficient anti-Prelog asymmetric reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cells was successfully performed in a biphasic system consisting of deep eutectic solvent (DES) and water-immiscible ionic liquid (IL). Various DESs exerted different effects on the synthesis of (R)-2-octanol. Choline chloride/ethylene glycol (ChCl/EG) exhibited good biocompatibility and could moderately increase the cell membrane permeability thus leading to the better results. Adding ChCl/EG ...

  8. Study of solvent effects on the stability constant and ionic mobility of the dibenzo-18-crown-6 complex with potassium ion by affinity capillary electrophoresis

    Czech Academy of Sciences Publication Activity Database

    Konášová, Renáta; Jaklová Dytrtová, Jana; Kašička, Václav

    2016-01-01

    Roč. 39, č. 22 (2016), s. 4429-4438 ISSN 1615-9306 R&D Projects: GA ČR(CZ) GA15-01948S; GA ČR GP13-21409P Institutional support: RVO:61388963 Keywords : affinity capillary electrophoresis * crown ethers * hydro-organic solvents * ionic mobility * potassium complexes Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 2.557, year: 2016

  9. Determination of atenolol in human plasma using ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography.

    Science.gov (United States)

    Zeeb, Mohsen; Farahani, Hadi; Papan, Mohammad Kazem

    2016-06-01

    An efficient analytical method called ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography was developed for the determination of atenolol in human plasma. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was formed by the addition of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) to a sample solution containing an ion-pairing agent during microextraction. The analyte was extracted into the ionic liquid phase while the microextraction solvent was dispersed throughout the sample by utilizing ultrasound. The sample was then centrifuged, and the extracting phase retracted into the microsyringe and injected to liquid chromatography. After optimization, the calibration curve showed linearity in the range of 2-750 ng/mL with the regression coefficient corresponding to 0.998. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.5 and 2 ng/mL, respectively. A reasonable relative recovery range of 90-96.7% and satisfactory intra-assay (4.8-5.1%, n = 6) and interassay (5.0-5.6%, n = 9) precision along with a substantial sample clean-up demonstrated good performance of the procedure. It was applied for the determination of atenolol in human plasma after oral administration and some pharmacokinetic data were obtained. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Effect of pH, ionic strength and fulvic acid on the sorption and desorption of cobalt to bentonite

    International Nuclear Information System (INIS)

    Yu, Sh.M.; Ren, A.P.; Chen, Ch.L.; Chen, Y.X.; Wang, X.

    2006-01-01

    Humic substances and bentonite have attracted great interest in radioactive waste management. Here the sorption of cobalt on bentonite in the presence and absence of fulvic acid (FA) under ambient conditions was studied. The effects of pH, ionic strength, FA and solution concentrations on cobalt sorption to bentonite were also investigated using batch techniques. The results indicate that the sorption of cobalt is strongly dependent on pH and is independent of ionic strength under our experimental conditions. Surface complexation is considered the main mechanism of cobalt sorption to bentonite. In the presence of FA, little effect of FA on cobalt sorption was found at pH 8. The addition sequences of FA/Co 2+ to the bentonite suspension on the sorption of cobalt to FA-coated bentonite were also studied. The results indicated that the sorption is not influenced by the addition sequences. Some possible mechanisms are discussed

  11. The effect of addition of primary positive salts, complex salt, on the ionic strength and rate constant at various temperatures by reaction kinetics

    Science.gov (United States)

    Kurade, S. S.; Ramteke, A. A.

    2018-05-01

    In this work, we have investigated the rate of reaction by using ionic strength at different temperatures. The main goal of this experiment is to determine the relation between ionic strength with reaction rate, reaction time and rate constant with temperature. It is observed that the addition of positive salt indicate the increasing ionic strength with increase in run time at various temperatures. Thus the temperature affects the speed of reaction and mechanism by which chemical reaction occurs and time variable plays vital role in the progress of reaction at different temperatures.

  12. In-vitro investigations of a pH- and ionic-strength-responsive polyelectrolytic hydrogel using a piezoresistive microsensor

    Science.gov (United States)

    Schulz, Volker; Guenther, Margarita; Gerlach, Gerald; Magda, Jules J.; Tathireddy, Prashant; Rieth, Loren; Solzbacher, Florian

    2010-01-01

    Environmental responsive or smart hydrogels show a volume phase transition due to changes of external stimuli such as pH or ionic strength of an ambient solution. Thus, they are able to convert reversibly chemical energy into mechanical energy and therefore they are suitable as sensitive material for integration in biochemical microsensors and MEMS devices. In this work, micro-fabricated silicon pressure sensor chips with integrated piezoresistors were used as transducers for the conversion of mechanical work into an appropriate electrical output signal due to the deflection of a thin silicon bending plate. Within this work two different sensor designs have been studied. The biocompatible poly(hydroxypropyl methacrylate-N,N-dimethylaminoethyl methacrylate-tetra-ethyleneglycol dimethacrylate) (HPMA-DMA-TEGDMA) was used as an environmental sensitive element in piezoresistive biochemical sensors. This polyelectrolytic hydrogel shows a very sharp volume phase transition at pH values below about 7.4 which is in the range of the physiological pH. The sensor's characteristic response was measured in-vitro for changes in pH of PBS buffer solution at fixed ionic strength. The experimental data was applied to the Hill equation and the sensor sensitivity as a function of pH was calculated out of it. The time-dependent sensor response was measured for small changes in pH, whereas different time constants have been observed. The same sensor principal was used for sensing of ionic strength. The time-dependent electrical sensor signal of both sensors was measured for variations in ionic strength at fixed pH value using PBS buffer solution. Both sensor types showed an asymmetric swelling behavior between the swelling and the deswelling cycle as well as different time constants, which was attributed to the different nature of mechanical hydrogel-confinement inside the sensor. PMID:21152365

  13. In-vitro investigations of a pH- and ionic-strength-responsive polyelectrolytic hydrogel using a piezoresistive microsensor

    OpenAIRE

    Schulz, Volker; Guenther, Margarita; Gerlach, Gerald; Magda, Jules J.; Tathireddy, Prashant; Rieth, Loren; Solzbacher, Florian

    2009-01-01

    Environmental responsive or smart hydrogels show a volume phase transition due to changes of external stimuli such as pH or ionic strength of an ambient solution. Thus, they are able to convert reversibly chemical energy into mechanical energy and therefore they are suitable as sensitive material for integration in biochemical microsensors and MEMS devices. In this work, micro-fabricated silicon pressure sensor chips with integrated piezoresistors were used as transducers for the conversion o...

  14. Renewable energy powered membrane technology: Impact of pH and ionic strength on fluoride and natural organic matter removal.

    Science.gov (United States)

    Owusu-Agyeman, Isaac; Shen, Junjie; Schäfer, Andrea Iris

    2018-04-15

    Real water pH and ionic strength vary greatly, which influences the performance of membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Systematic variation of pH (3-12) and ionic strength (2-10g/L as total dissolved solids (TDS)) was undertaken with a real Tanzanian water to investigate how water quality affects retention mechanisms of fluoride (F) and natural organic matter (NOM). An autonomous solar powered NF/RO system driven by a solar array simulator was supplied with constant power from a generator. An open NF (NF270) and a brackish water RO (BW30) membrane were used. A surface water with a very high F (59.7mg/L) and NOM (110mgC/L) was used. Retention of F by NF270 was 80% at pH4, and about 99% at pH >5, due to the smaller pore size and hence a more dominant size exclusion. In consequence, only little impact of ionic strength increase was observed for BW30. The concentration of NOM in permeates of both NF270 and BW30 were typically energy fluctuations, this research emphasises on feed water quality that affects system performance and may alter due to a number of environmental factors. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Sorption of uranyl ions on silica. Effects of contact time, pH, ionic strength, concentration and phosphate

    International Nuclear Information System (INIS)

    Zhang Hongxia; Tao Zuyi

    2002-01-01

    The sorption of UO 2 2+ and phosphate on silica were simultaneously studied. The effect of contact time between the solid phase and aqueous solution, pH and ionic strength on the UO 2 2+ sorption in the absence and the presence of phosphate was investigated. The effect of contact time between the solid phase and aqueous solution, pH and ionic strength on the phosphate sorption was investigated too. The isotherms of UO 2 2+ and phosphate sorption at different pH values were determined. It was found that as compared with the sorption in the absence of phosphate, the sorption of UO 2 2+ on silica in the presence of phosphate is increased at low pH and decreased at high pH; the abruptly increased with increasing pH in the pH range 3-6; the sorption is gradually decreased with increasing pH in the pH range 2-12; the sorption insensitive and the sorption of phosphate is sensitive to ionic strength. (author)

  16. Sorption of triclosan onto activated carbon, kaolinite and montmorillonite: effects of pH, ionic strength, and humic acid.

    Science.gov (United States)

    Behera, Shishir Kumar; Oh, Seok-Young; Park, Hung-Suck

    2010-07-15

    Sorption of triclosan on three sorbents, viz., activated carbon, kaolinite and montmorillonite was studied as a function of pH, ionic strength and humic acid (HA) concentration through controlled batch experiments. Triclosan sorption was found to be higher in the acidic pH range, as varying pH showed significant influence on the surface charge of the sorbents and degree of ionization of the sorbate. Sorption capacity of the sorbents increased with an increase in the ionic strength of solution. At low pH (pH 3), the overall increase in triclosan sorption was 1.2, approximately 4 and 3.5 times, respectively for activated carbon, kaolinite and montmorillonite when ionic strength was increased from 1x10(-3) to 5x10(-1) M. Triclosan sorption onto activated carbon decreased from 31.4 to 10.6 mg g(-1) by increasing the HA concentration to 200 mg C L(-1). However, during sorption onto kaolinite and montmorillonite, the effect of HA was very complex probably due to (i) hydrophobicity (log K(ow)=4.76) of triclosan; and (ii) complexation of HA with triclosan. Though triclosan sorption onto activated carbon is higher, the potential of kaolinite and montmorillonite in controlling the transport of triclosan in subsurface environment can still be appreciable. 2010 Elsevier B.V. All rights reserved.

  17. UO2 leaching and radionuclide release modelling under high and low ionic strength solution and oxidation conditions

    International Nuclear Information System (INIS)

    1995-01-01

    In this work, the UO 2 dissolution under oxidizing conditions has been studied in order to compare these results to those obtained with spent fuel. Two different leaching solutions have been used, one with a high ionic strength trying to simulate the conditions expected in a saline repository and the other at low ionic strength much appropriate to granitic environments. In both cases, the dissolution has been studied studied as a function of pH, redox potential, oxidants, complexing agents, particle size as well as the experimental methodology. Results can be summarized as follows: a) The UO 2 dissolution is rather independent on ionic strength. b) Dissolution rates can be explained in general independent on the oxidant as: Log R=3DK [oxidant] Surface solid evolution is very important to understand the dissolution/oxidation mechanism of UO 2 . d) Under oxidizing conditions, the dissolution is H+ and HCO 3 promoted. e) In carbonate medium, both UO 2 and spent fuel dissolution rates are very similar, while in a non-complexing medium, spent fuel dissolution rate is much higher than the UO 2 one. This fact seems to indicate that radiolysis is much important non-complexing media. (Author)

  18. Solubilization of myofibrillar proteins in water or low ionic strength media: Classical techniques, basic principles, and novel functionalities.

    Science.gov (United States)

    Chen, Xing; Tume, Ron K; Xu, Xinglian; Zhou, Guanghong

    2017-10-13

    The qualitative characteristics of meat products are closely related to the functionality of muscle proteins. Myofibrillar proteins (MPs), comprising approximately 50% of total muscle proteins, are generally considered to be insoluble in solutions of low ionic strength ( 0.3 M) for solubilization. These soluble proteins are the ones which determine many functional properties of meat products, including emulsification and thermal gelation. In order to increase the utilization of meat and meat products, many studies have investigated the solubilization of MPs in water or low ionic strength media and determining their functionality. However, there still remains a lack of systematic information on the functional properties of MPs solubilized in this manner. Hence, this review will explore some typical techniques that have been used. The main procedures used for their solubilization, the fundamental principles and their functionalities in water (low ionic strength medium) are comprehensively discussed. In addition, advantages and disadvantages of each technique are summarized. Finally, future considerations are presented to facilitate progress in this new area and to enable water soluble muscle MPs to be utilized as novel meat ingredients in the food industry.

  19. Effect of deoxycholate conjugation on stability of pDNA/polyamidoamine-diethylentriamine (PAM-DET) polyplex against ionic strength.

    Science.gov (United States)

    Jeong, Yunseong; Jin, Geun-Woo; Choi, Eunjung; Jung, Ji Hyuk; Park, Jong-Sang

    2011-11-28

    Polyplexes formed from cationic polymer/pDNA have been known to be vulnerable to external ionic strength. To improve polyplex stability against ionic strength, we attempted the chemical conjugation of the hydrophobic deoxycholate (DC) moiety to the polyamidoamine-diethylenetriamine (PAM-DET) dendrimer. Dynamic light scattering studies showed that the tolerance of the resulting PAM-DET-DC against ionic strength is higher than that of PAM-DET. In addition, we confirmed that the stability of polyplex has a strong relationship with the degree of conjugation of the DC moiety to the PAM-DET dendrimer and the charge ratio of PAM-DET-DC. Furthermore, the transfection efficiency of the PAM-DET-DC polyplex is higher than that of PAM-DET but its cytotoxicity remains the same. Therefore, the chemical conjugation of DC is a safe and effective method for increasing the stability of supramolecules formed from electrostatic interaction. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. The effect of pH and ionic strength of dissolution media on in-vitro release of two model drugs of different solubilities from HPMC matrices.

    Science.gov (United States)

    Asare-Addo, Kofi; Conway, Barbara R; Larhrib, Hassan; Levina, Marina; Rajabi-Siahboomi, Ali R; Tetteh, John; Boateng, Joshua; Nokhodchi, Ali

    2013-11-01

    The evaluation of the effects of different media ionic strengths and pH on the release of hydrochlorothiazide, a poorly soluble drug, and diltiazem hydrochloride, a cationic and soluble drug, from a gel forming hydrophilic polymeric matrix was the objective of this study. The drug to polymer ratio of formulated tablets was 4:1. Hydrochlorothiazide or diltiazem HCl extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC)) were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus. The ionic strength of the media was varied over a range of 0-0.4M to simulate the gastrointestinal fed and fasted states and various physiological pH conditions. Sodium chloride was used for ionic regulation due to its ability to salt out polymers in the midrange of the lyotropic series. The results showed that the ionic strength had a profound effect on the drug release from the diltiazem HCl K100LV matrices. The K4M, K15M and K100M tablets however withstood the effects of media ionic strength and showed a decrease in drug release to occur with an increase in ionic strength. For example, drug release after the 1h mark for the K100M matrices in water was 36%. Drug release in pH 1.2 after 1h was 30%. An increase of the pH 1.2 ionic strength to 0.4M saw a reduction of drug release to 26%. This was the general trend for the K4M and K15M matrices as well. The similarity factor f2 was calculated using drug release in water as a reference. Despite similarity occurring for all the diltiazem HCl matrices in the pH 1.2 media (f2=64-72), increases of ionic strength at 0.2M and 0.4M brought about dissimilarity. The hydrochlorothiazide tablet matrices showed similarity at all the ionic strength tested for all polymers (f2=56-81). The values of f2 however reduced with increasing ionic strengths. DSC hydration results explained the hydrochlorothiazide release from their HPMC matrices. There was an increase in

  1. Spectroscopic Characterization of Aqua [ fac-Tc(CO)3]+ Complexes at High Ionic Strength.

    Science.gov (United States)

    Chatterjee, Sayandev; Hall, Gabriel B; Engelhard, Mark H; Du, Yingge; Washton, Nancy M; Lukens, Wayne W; Lee, Sungsik; Pearce, Carolyn I; Levitskaia, Tatiana G

    2018-06-05

    Understanding fundamental Tc chemistry is important to both the remediation of nuclear waste and the reprocessing of nuclear fuel; however, current knowledge of the electronic structure and spectral signatures of low-valent Tc compounds significantly lags behind the remainder of the d-block elements. In particular, identification and treatment of Tc speciation in legacy nuclear waste is challenging due to the lack of reference data especially for Tc compounds in the less common oxidation states (I-VI). In an effort to establish a spectroscopic library corresponding to the relevant conditions of extremely high ionic strength typical for the legacy nuclear waste, compounds with the general formula of [ fac-Tc(CO) 3 (OH 2 ) 3- n (OH) n ] 1- n (where n = 0-3) were examined by a range of spectroscopic techniques including 99 Tc/ 13 C NMR, IR, XPS, and XAS. In the series of monomeric aqua species, stepwise hydrolysis results in the increase of the Tc metal center electron density and corresponding progressive decrease of the Tc-C bond distances, Tc electron binding energies, and carbonyl stretching frequencies in the order [ fac-Tc(CO) 3 (OH 2 ) 3 ] + > [ fac-Tc(CO) 3 (OH 2 ) 2 (OH)] > [ fac-Tc(CO) 3 (OH 2 )(OH) 2 ] - . These results correlate with established trends of the 99 Tc upfield chemical shift and carbonyl 13 C downfield chemical shift. The lone exception is [ fac-Tc(CO) 3 (OH)] 4 which exhibits a comparatively low electron density at the metal center attributed to the μ 3 -bridging nature of the - OH ligands causing less σ-donation and no π-donation. This work also reports the first observations of these compounds by XPS and [ fac-Tc(CO) 3 Cl 3 ] 2- by XAS. The unique and distinguishable spectral features of the aqua [ fac-Tc(CO) 3 ] + complexes lay the foundation for their identification in the complex aqueous matrixes.

  2. Thermodynamic properties of deep eutectic solvent and ionic liquid mixtures at temperatures from 293.15 K to 343.15 K

    Science.gov (United States)

    Achsah, R. S.; Shyam, S.; Mayuri, N.; Anantharaj, R.

    2018-04-01

    Deep eutectic solvents (DES) and ionic liquids (ILs) have their applications in various fields of research and in industries due to their attractive physiochemical properties. In this study, the combined thermodynamic properties of DES (choline chloride-glycerol) + IL1 (1-butyl-3-methylimiazolium acetate) and DES(choline chloride-glycerol) + IL2 (1-ethyl-3-methylimadzolium ethyl sulphate) have been studied. The thermodynamic properties such as excess molar volume, partial molar volume, excess partial molar volume and apparent molar volume were calculated for different mole fractions ranging from 0 to 1 and varying temperatures from 293.15 K to 343.15 K. In order to know the solvent properties of DESs and ILs mixtures at different temperatures and their molecular interactions to enhance the solvent performance and process efficiency at fixed composition and temperature the thermodynamic properties were analyzed.

  3. Extraction of toluene from aliphatic compounds using an ionic liquid as solvent: Influence of the alkane on the (liquid + liquid) equilibrium

    International Nuclear Information System (INIS)

    Gonzalez, Emilio J.; Calvar, Noelia; Dominguez, Irene; Dominguez, Angeles

    2011-01-01

    Research highlights: → An ionic liquid was analyzed as solvent for extraction of toluene from alkanes. → Liquid-liquid equilibrium data were measured at 298.15 K and atmospheric pressure. → Selectivity and solute distribution ratio were obtained and compared with literature. → The Othmer-Tobias equation was used to ascertain the experimental LLE data. → Experimental data were correlated using NRTL and UNIQUAC models. - Abstract: In this paper, the feasibility of using 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid, [EMim][ESO 4 ], as solvent for the extraction of toluene from aliphatic compounds (hexane, heptane, octane, or nonane) was analyzed. (Liquid + liquid) equilibrium (LLE) data for the ternary systems {alkane (1) + toluene (2) + [EMim][ESO 4 ] (3)} were measured at T = 298.15 K and atmospheric pressure. Selectivity and solute distribution ratio were calculated from the experimental LLE data, and the obtained values were compared to those previously reported using other ionic liquids and sulfolane. The degree of consistency of the experimental LLE data was ascertained using the Othmer-Tobias equation. Finally, the experimental LLE data were satisfactorily correlated with NRTL and UNIQUAC models.

  4. Temperature and ionic strength influences on actinide(VI)/(V) redox potentials for carbonate limiting complexes

    International Nuclear Information System (INIS)

    Capdevila, H.; Vitorge, P.

    1998-01-01

    Actinide behaviour was studied in two limiting aqueous solutions: acidic and carbonate. Cyclic voltametry was validated with well-known U redox system. SIT was used to account for I influence. Taylor's series expansions to the second order were used to account for T influence. Redox potentials of actinide couples had previously been measured in non complexing media. The above data treatments give standard values for redox potential E 0 , for the corresponding entropy ΔS 0 , enthalpy ΔH 0 and heat capacity ΔC p 0 changes, and also for the corresponding excess values (i.e. the variation of these thermodynamic constants with ionic strength). This methodology was here used in carbonate media to measure the potential of the redox couple PuO 2 (CO 3 ) 3 4- /PuO 2 (CO 3 ) 3 5- from 5 to 70 degC and from I = 0.5 to 4.5 M in Na 2 CO 3 , NaClO 4 media. Experimental details and full results are given for Pu. Only final results are given for Np. Previous and/or published data for U and Am are discussed. E and ΔS variations with T or I were enough to be measured. The values obtained for the fitted SIT coefficients Δε, and for ΔS and ΔCp are similar for U, Np and Pu redox reactions. Using this analogy for Am missing data is discussed. β 3 V /β 3 VI formation constant ratio of the carbonate limiting complexes were deduced from the potential shift from complexing to non complexing media for the Actinide(VI)/Actinide(V) redox couples. β 3 V (U and Pu) and β 3 VI (Np) were finally proposed using published β3 VI (U and Pu) and β 3 V (Np). For Am, this data treatment was used to discuss the AmO 2 2+ / AmO 2 + redox potential

  5. Solubility product of tetravalent neptunium hydrous oxide and its ionic strength dependence

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, K.; Mori, T. [Japan Nuclear Cycle Development Institute (JNC), 4-33, Muramatsu, Tokai-mura, Naka-gun, Ibaraki-ken, 319-1194 (Japan); Kohara, Y. [Inspection and Development Company, 4-33, Muramatsu, Tokaimura, Naka-gun, Ibaraki-ken, 319-1112 (Japan)

    2005-07-01

    Full text of publication follows: Solubility products (K{sub sp}) are key parameters in the context of reliable assessment of actinides migration in the repository conditions of high level radioactive waste. Neptunium (Np(IV)) is one of the most important actinide elements in the assessment, because of its inventory and the long half-life. A few previous data for Np(IV) solubility are varied widely due to experimental difficulties related to the extremely low solubility. We carried out batch-type experiments under nitrogen atmosphere using a glovebox. Np(V) was reduced to Np(III) by bubbling 0.5 ppm H{sub 2} / N{sub 2} gas through the solution for 30 days in the presence of platinum black as catalyst. After reducing treatment, the Np(III) converted to Np(IV) by auto-oxidation within approximately three days. The solubilities of the Np(IV) were measured in the pHc ranging from 2 to 4, at room temperature (23 {+-} 2 deg. C), in ionic strength(I) = 0.1, 0.5, 1.0 and 2.0 M NaClO{sub 4}. The equilibrium condition was confirmed by over-saturation and under-saturation method. After the equilibrium, the pH{sub c} and the E{sub h} value of the suspension were measured. The suspension was then filtered using a filter with a NMWL of 3000 (less than 2 nm{phi}). The Np radio activity in the filtrate was determined by alpha spectrometry and absorption spectra of Np(IV). The solubility decreased with increasing pHc and the hydrolysis species are predominantly formed. From the obtained results, the solubility products (K{sub sp}) of Np hydroxide, for the reaction, NpO{sub 2} . xH{sub 2}O {r_reversible} Np{sup 4+} + 4OH{sup -} + (x-2)H{sub 2}O, at I = 0.1, 0.5, 1.0 and 2.0 were determined by using formation constants ({beta}{sub n}(I)), which were determined for the reaction, Np{sup 4+} + nOH{sup -} {r_reversible} Np(OH){sub n}{sup (4-n)+}. By using the specific interaction theory (SIT), the solubility product of tetravalent Np hydrous oxide is calculated to be log K{sub sp}{sup 0

  6. Conformation and Catalytic Properties Studies of Candida rugosa Lip7 via Enantioselective Esterification of Ibuprofen in Organic Solvents and Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Xiang Li

    2013-01-01

    Full Text Available Enantioselective esterification of ibuprofen was conducted to evaluate the enzyme activity and ees of lipase from Candida rugosa (CRL7 in ten conventional organic solvents and three ionic liquids. Different alcohols were tested for selecting the most suitable acyl acceptor due to the fact that the structure of alcohols (branch and length of carbon chains; location of –OH functional group could affect the enzyme activity and ees. The results of alcohol and solvent selection revealed that 1-isooctanol and isooctane were the best substrate and reaction medium, respectively, because of the highest enzyme activity and ees. Compared with the control, conformational studies via FT-IR indicate that the variations of CRL7’s secondary structure elements are probably responsible for the differences of enzyme activity and ees in the organic solvents and ionic liquids. Moreover, the effects of reaction parameters, such as molar ratio, water content, temperature, and reaction time, in the selected reaction medium, were also examined.

  7. Solvent extraction of thiophene from n-alkanes (C7, C12, and C16) using the ionic liquid [C8mim][BF4

    International Nuclear Information System (INIS)

    Alonso, Luisa; Arce, Alberto; Francisco, Maria; Soto, Ana

    2008-01-01

    In the last years, new strict environmental regulations to reduce sulfur content in liquid fuels have been established. Thiophene derivates can be considered as the key substances to be separated from liquid fuel oils. This paper reports the ability of the ionic liquid 1-methyl-3-octylimidazolium tetrafluoroborate to act as solvent in the (liquid + liquid) extraction of thiophene from aliphatic hydrocarbons. Tie-line data have been determined for ternary systems containing the ionic liquid, thiophene, and some n-alkanes at T = 298.15 K. Extraction process has been analyzed by means of thiophene distribution ratio and selectivity. The solute distribution coefficient decreases and the selectivity increases as the chain length of n-alkane increases. The use of 1-methyl-3-octylimidazolium tetrafluoroborate as potential solvent for separation of thiophene from n-alkanes is feasible using the necessary quantity of solvent. A correlation of the equilibrium data reported here has also been made, using the NRTL activity coefficient model, in order to facilitate their use in simulation and design processes

  8. Nickel adsorption and desorption in an acric oxisol as a function of pH, ionic strength and incubation time

    Directory of Open Access Journals (Sweden)

    Estêvão Vicari Mellis

    Full Text Available ABSTRACT Although nickel (Ni has both important potential benefits and toxic effects in the environment, its behavior in tropical soils has not been well studied. Nickel adsorption-desorption in topsoil and subsoil samples of an acric Oxisol was studied at three pH values (from 3.0 to 8.0. Adsorption-desorption isotherms were elaborated from experiments with increasing Ni concentration (5 to 100 mg L-1, during 0, 4, and 12 weeks, using CaCl2 0.01 and 0.1 M as electrolytic support in order to also verify the effect of Ni-soil time contact and of ionic strength on the reaction. Experimental results of Ni adsorption fitted Langmuir model, which indicated that maximum Ni adsorption (71,440 mg kg-1 occurred at subsoil, after 12 weeks. Nickel affinity (KL was also greater at subsoil (1.0 L kg-1. The Ni adsorption in the topsoil samples was higher, due to its lower point of zero salt effect (PZSE and higher organic matter content. The increase in soil pH resulted in the increase of Ni adsorption. Nickel desorbed less from soil samples incubated for 4 or 12 weeks, suggesting that Ni interactions with colloidal particles increase over time. The amount of Ni desorbed increased with increasing ionic strength in both the topsoil and subsoil soil samples. Finally, adsorption-desorption hysteresis was clearly observed. Soil pH, ionic strength of soil solution and the Ni-soil contact time should be considered as criteria for selecting the areas for disposal of residues containing Ni or to compose remediation strategies for acric soils contaminated with Ni.

  9. The effect of pH and ionic strength on proton adsorption by the thermophilic bacterium Anoxybacillus flavithermus

    Science.gov (United States)

    Burnett, Peta-Gaye; Heinrich, Hannah; Peak, Derek; Bremer, Phil J.; McQuillan, A. James; Daughney, Christopher J.

    2006-04-01

    Numerous studies have utilized surface complexation theory to model proton adsorption behaviour onto mesophilic bacteria. However, few experiments, to date, have investigated the effects of pH and ionic strength on proton interactions with thermophilic bacteria. In this study, we characterize proton adsorption by the thermophile Anoxybacillus flavithermus by performing acid-base titrations and electrophoretic mobility measurements in NaNO 3 (0.001-0.1 M). Equilibrium thermodynamics (Donnan model) were applied to describe the specific chemical reactions that occur at the water-bacteria interface. Acid-base titrations were used to determine deprotonation constants and site concentrations for the important cell wall functional groups, while electrophoretic mobility data were used to further constrain the model. We observe that with increasing pH and ionic strength, the buffering capacity increases and the electrophoretic mobility decreases. We develop a single surface complexation model to describe proton interactions with the cells, both as a function of pH and ionic strength. Based on the model, the acid-base properties of the cell wall of A. flavithermus can best be characterized by invoking three distinct types of cell wall functional groups, with p Ka values of 4.94, 6.85, and 7.85, and site concentrations of 5.33, 1.79, and 1.42 × 10 -4 moles per gram of dry bacteria, respectively. A. flavithermus imparts less buffering capacity than pure mesophilic bacteria studied to date because the thermophile possesses a lower total site density (8.54 × 10 -4 moles per dry gram bacteria).

  10. Effect of carboxymethyl cellulose and ionic strength on stability of mineral suspensions in potash ore flotation systems.

    Science.gov (United States)

    Pawlik, M; Laskowski, J S; Ansari, A

    2003-04-15

    The adsorption of sodium carboxymethyl cellulose from aqueous solutions varying in ionic strength from that of distilled water to 50% NaCl/KCl brine (about 3.5 mol/dm(3)) onto illite and dolomite has been studied. The purpose of this work was to investigate the solvency effects in the phenomena underlying the potash flotation process that is carried out in saturated brine. Based on viscosity measurements, the adsorption results were analyzed in terms of a simple model of polymer macromolecules in solution. Suspension stability measurements carried out concomitantly with adsorption tests showed the ranges of carboxymethyl cellulose concentration over which the tested suspensions either were aggregated or were restabilized.

  11. Application of volt-chins for determination of ionic components in real and chemical Gibbs transition energies of individual ions from water in aqueous-organic solvents

    International Nuclear Information System (INIS)

    Parfenyuk, V.I.

    2007-01-01

    Thermodynamic description of separate ions (among which is I - ) in individual and mixed solvents is conducted on the basis of the volt potential difference method. Application of the presented methodology serves as one of candidates problem solving of individual ions thermodynamic characterisation in solutions. Validity of application of the volt potential difference method for the determination of ionic components in real and chemical thermodynamic properties of separate ions in solutions as well as surface potential values on the solution-gas phase interfaces is demonstrated [ru

  12. Effect of organic solvents compared to sandblasting on the repair bond strength of nanohybrid and nanofilled composite resins

    Directory of Open Access Journals (Sweden)

    Rafael Torres Brum

    2017-01-01

    Full Text Available Background: This study evaluated the effect of different surface treatments on the repair bond strength of nanohybrid (Empress Direct and nanofilled (Filtek Z350 XT composite resins. Materials and Methods: A total of 120 specimens of each material (7.5 x 4.5 x 3 mm were prepared and polished with SiC paper. Half of the specimens were kept in water for seven days and the other half for six months; they were then divided into six groups according to the type of surface treatment: negative control (no treatment, Al2O3sandblasted, liquid acetone, acetone gel, liquid alcohol and alcohol gel. Following application of the silane coupling agent and the adhesive system, composite resin cylinders were fabricated on the specimens and light cured (20 seconds. The same composite resins were used for the repair. Additionally, ten intact specimens of each composite resin (without repair were prepared (positive control. The specimens were then loaded to failure in the microshear mode. Three additional specimens were fabricated in each group, and the surface treatments were analyzed by atomic force microscopy, energy-dispersive X-ray spectroscopy (EDS and scanning electron microscopy (SEM. Results: The nanofilled composite resin showed higher cohesive strength and repair bond strength than the nanohybrid composite resin. The aging process affected the repair bond strength of the nanofilled composite resin. Al2O3sandblasting was more efficient for the nanofilled composite resin and promoted greater surface roughness in both materials. The solvents demonstrated higher efficacy for the nanohybrid composite resin. Conclusion: The strengths resulting from the solvents were material dependent, and Al2O3sandblasting resulted in superior repair bond strength in both materials.

  13. Effect of organic solvents compared to sandblasting on the repair bond strength of nanohybrid and nanofilled composite resins.

    Science.gov (United States)

    Brum, Rafael Torres; Vieira, Sergio; Freire, Andrea; Mazur, Rui Fernando; De Souza, Evelise Machado; Rached, Rodrigo Nunes

    2017-01-01

    This study evaluated the effect of different surface treatments on the repair bond strength of nanohybrid (Empress Direct) and nanofilled (Filtek Z350 XT) composite resins. A total of 120 specimens of each material (7.5 x 4.5 x 3 mm) were prepared and polished with SiC paper. Half of the specimens were kept in water for seven days and the other half for six months; they were then divided into six groups according to the type of surface treatment: negative control (no treatment), Al2O3sandblasted, liquid acetone, acetone gel, liquid alcohol and alcohol gel. Following application of the silane coupling agent and the adhesive system, composite resin cylinders were fabricated on the specimens and light cured (20 seconds). The same composite resins were used for the repair. Additionally, ten intact specimens of each composite resin (without repair) were prepared (positive control). The specimens were then loaded to failure in the microshear mode. Three additional specimens were fabricated in each group, and the surface treatments were analyzed by atomic force microscopy, energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). The nanofilled composite resin showed higher cohesive strength and repair bond strength than the nanohybrid composite resin. The aging process affected the repair bond strength of the nanofilled composite resin. Al2O3sandblasting was more efficient for the nanofilled composite resin and promoted greater surface roughness in both materials. The solvents demonstrated higher efficacy for the nanohybrid composite resin. The strengths resulting from the solvents were material dependent, and Al2O3sandblasting resulted in superior repair bond strength in both materials.

  14. Debye length dependence of the anomalous dynamics of ionic double layers in a parallel plate capacitor

    NARCIS (Netherlands)

    Kortschot, R. J.; Philipse, A. P.; Erné, B. H.

    2014-01-01

    The electrical impedance spectrum of simple ionic solutions is measured in a parallel plate capacitor at small applied ac voltage. The influence of the ionic strength is investigated using several electrolytes at different concentrations in solvents of different dielectric constants. The electric

  15. Salting-out-enhanced ionic liquid microextraction with a dual-role solvent for simultaneous determination of trace pollutants with a wide polarity range in aqueous samples.

    Science.gov (United States)

    Gao, Man; Qu, Jingang; Chen, Kai; Jin, Lide; Dahlgren, Randy Alan; Wang, Huili; Tan, Chengxia; Wang, Xuedong

    2017-11-01

    In real aquatic environments, many occupational pollutants with a wide range of polarities coexist at nanogram to milligram per liter levels. Most reported microextraction methods focus on extracting compounds with similar properties (e.g., polarity or specific functional groups). Herein, we developed a salting-out-enhanced ionic liquid microextraction based on a dual-role solvent (SILM-DS) for simultaneous detection of tetracycline, doxycycline, bisphenol A, triclosan, and methyltriclosan, with log K ow ranging from -1.32 to 5.40 in complex milk and environmental water matrices. The disperser in the ionic-liquid-based dispersive liquid-liquid microextraction was converted to the extraction solvent in the subsequent salting-out-assisted microextraction procedures, and thus a single solvent performed a dual role as both extractant and disperser in the SILM-DS process. Acetonitrile was selected as the dual-role solvent because of its strong affinity for both ionic liquids and water, as well as the extractant in the salting-out step. Optimized experimental conditions were 115 μL [C 8 MIM][PF 6 ] as extractor, 1200 μL acetonitrile as dual-role solvent, pH 2.0, 5.0 min ultrasound extraction time, 3.0 g Na 2 SO 4 , and 3.0 min vortex extraction time. Under optimized conditions, the recoveries of the five pollutants ranged from 74.5 to 106.9%, and their LODs were 0.12-0.75 μg kg -1 in milk samples and 0.11-0.79 μg L -1 in environmental waters. Experimental precision based on relative standard deviation was 1.4-6.4% for intraday and 2.3-6.5% for interday analyses. Compared with previous methods, the prominent advantages of the newly developed method are simultaneous determination of pollutants with a wide range of polarities and a substantially reduced workload for ordinary environmental monitoring and food tests. Therefore, the new method has great application potential for simultaneous determination of trace pollutants with strongly contrasting polarities in several

  16. Kinetics of the oxidation of hydrogen sulfite by hydrogen peroxide in aqueous solution:. ionic strength effects and temperature dependence

    Science.gov (United States)

    Maaß, Frank; Elias, Horst; Wannowius, Klaus J.

    Conductometry was used to study the kinetics of the oxidation of hydrogen sulfite, HSO -3, by hydrogen peroxide in aqueous non-buffered solution at the low concentration level of 10 -5-10 -6 M, typically found in cloud water. The kinetic data confirm that the rate law reported for the pH range 3-6 at higher concentration levels, rate= kH·[H +]·[HSO -3]·[H 2O 2], is valid at the low concentration level and at low ionic strength Ic. At 298 K and Ic=1.5×10 -4 M, third-order rate constant kH was found to be kH=(9.1±0.5)×10 7 M -2 s -1. The temperature dependence of kH led to an activation energy of Ea=29.7±0.9 kJ mol -1. The effect of the ionic strength (adjusted with NaCl) on rate constant kH was studied in the range Ic=2×10 -4-5.0 M at pH=4.5-5.2 by conductometry and stopped-flow spectrophotometry. The dependence of kH on Ic can be described with a semi-empirical relationship, which is useful for the purpose of comparison and extrapolation. The kinetic data obtained are critically compared with those reported earlier.

  17. Charge and softness of the outer part of the cell wall of Thiobacillus ferrooxidans in the low ionic strength medium

    Directory of Open Access Journals (Sweden)

    Škvarla Jiří

    2002-03-01

    Full Text Available The surface charge and surface potential are parameters influencing the microbial adhesion phenomenon through the electrostatic interaction between bacteria and substrates. The Smoluchowski equation, originally developed for estimating the above parameters from the experimentally accessible electrophoretic mobility of rigid colloid particles, is however inapplicable to the elastic bacterial cells. The problem is that the outer cell wall of bacteria is a layer with a complex polyelectrolyte structure. In this article, the OhshimaLs model of the gsofth particle is applied to describe the surface electrostatics of Thiobacillus ferrooxidans cells by measuring their electrophoretic mobility in distilled water as a function of a (low ionic strength and pH. In this model, the rigid core is considered to be covered with a charged ion-penetrable layer of polyelectrolytes. Two model parameters have been determined by the curve fitting at pH from 3.2 to 5.8, namely the number density of the dissociated groups N and the softness parameter 1/ƒÉ of the polyelectrolyte layer of the bacterium. A disagreement of the best fit parameters (evaluated by the correlation coefficient with the analogous parameters determined for other colloids (including bacterial cells in aqueous solutions of a high ionic strength is discussed.

  18. Transport of vanadium (V in saturated porous media: effects of pH, ionic-strength and clay mineral

    Directory of Open Access Journals (Sweden)

    Yulu Wang

    2016-10-01

    Full Text Available Vanadium, a hazardous pollutant, has been frequently detected in soil and groundwater, however, its transport behavior in porous media were not clearly understood. In this study, the effects of solution pH, ionic strength (IS and the effect of clay mineral on the transport of vanadium in saturated porous media were investigated. Laboratory experiments using a series of columns packed with quartz sand were carried out to explore the retention and transport of vanadium with a range of ionic-strength (0.001–0.1 M and pH (4–8 and two different types of clay minerals montmorillonite and kaolinite. Results of the breakthrough experiments showed that vanadium was highly mobile in the saturated porous media. The increase in pH rendered a higher transport of vanadium in saturated porous media. The study also indicated an easier transfer of vanadium with an increase in IS. Montmorillonite enhanced the mobility of vanadium in the column when compared to kaolinite. A mathematical model based on advection-dispersion equation coupled with equilibrium and kinetic reactions was used to describe the retention and transport of vanadium in the columns very well.

  19. Influence of ionic strength and OH(-) ion concentration on the Cu(II) complex formation with EDTA in alkaline solutions.

    Science.gov (United States)

    Norkus, E; Vaskelis, A; Zakaite, I

    1996-03-01

    D.c. polarographic data show that the complex formation of copper ions with EDTA depends markedly on the ionic strength of the solution at pH 8-10. This is primarily associated with the dependence of the fourth deprotonization constant of EDTA on the solution ionic strength: when it increases from 0.4 to 3.4, the pK(a4) value decreases from 9.5 to 8.2. According to polarographic and spectrophotometric data the degree of Cu(II) complexation increases at pH>10 due to transformation of the complex CuY(2-) to the more stable CuY(OH)(3-) (Y(4-), a fully deprotonized anion of EDTA), but it decreases with increase in alkalinity in a highly alkaline solution (pH>13.5). The latter result could be explained by the decrease in the EDTA anion activity. The calculated values of the activity coefficient are lower than 0.05 at pH>14.

  20. Influence of cellulose nanocrystals concentration and ionic strength on the elaboration of cellulose nanocrystals-xyloglucan multilayered thin films.

    Science.gov (United States)

    Dammak, Abir; Moreau, Céline; Azzam, Firas; Jean, Bruno; Cousin, Fabrice; Cathala, Bernard

    2015-12-15

    The effect of the variation of CNC concentration on the growth pattern of CNC-XG films is investigated. We found that a transition in the growth slope occurs at a CNC concentration of roughly 3-4gL(-1). A close effect can be obtained by the increase of the ionic strength of the CNC suspensions, suggesting that electrostatic interactions are involved. Static light scattering investigation of CNC dispersions at increasing concentrations demonstrated that the particle-particle interactions change as the CNC concentration increases. Neutron Reflectivity (NR) was used to probe the internal structure of the films. The increase of the CNC concentration as well as the increase of the ionic strength in the CNC suspension were found to induce a densification of the adsorbed CNC layers, even though the mechanisms are not strictly identical in both cases. Small changes in these parameters provide a straightforward way of controlling the architecture of CNC-based multilayered thin films and, as a result, their functional properties. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Evolution of carboxymethyl cellulose layer morphology on hydrophobic mineral surfaces: variation of polymer concentration and ionic strength.

    Science.gov (United States)

    Beaussart, Audrey; Mierczynska-Vasilev, Agnieszka; Beattie, David A

    2010-06-15

    The adsorption of carboxymethyl cellulose (CMC) on the basal planes of talc and molybdenite has been studied using in situ atomic force microscope (AFM) imaging. These experiments were partnered with quantitative adsorption isotherm determinations on particulate samples. The isotherms revealed a clear increase of the CMC adsorbed amount upon increasing the solution ionic strength for adsorption on both minerals. In addition, the shapes of the isotherms changed in response to the change in the electrolyte concentration, with CMC on talc displaying stepped (10(-3) M KCl), Langmuir (10(-2) M KCl), then Freundlich isotherm shapes (10(-1) M KCl), and CMC on molybdenite displaying stepped (10(-3) M KCl), Freundlich (10(-2) M KCl), then Langmuir isotherm shapes (10(-1) M KCl). AFM imaging of the polymer layer on the mineral surfaces with varying solution conditions mirrored and confirmed the conclusions from the isotherms: as the polymer solution concentration increased, coverage on the basal plane increased; as the ionic strength increased, coverage on the basal plane increased and the morphology of the layer changed from isolated well-distributed polymer domains to extensive adsorption and formation of dense, uneven polymer domains/features. In addition, comparison of the talc and molybdenite datasets points toward the presence of different binding mechanisms for CMC adsorption on the talc and molybdenite basal plane surfaces. 2010 Elsevier Inc. All rights reserved.

  2. Glass transition dynamics and conductivity scaling in ionic deep eutectic solvents: The case of (acetamide + lithium nitrate/sodium thiocyanate) melts

    Energy Technology Data Exchange (ETDEWEB)

    Tripathy, Satya N., E-mail: satyanarayantripathy@gmail.com; Wojnarowska, Zaneta; Knapik, Justyna; Paluch, Marian [Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pulku Piechoty 1A, 41-500 Chorzow (Poland); Shirota, Hideaki [Department of Nanomaterial Science and Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522 (Japan); Biswas, Ranjit [Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake, Kolkata 700098 (India)

    2015-05-14

    A detailed investigation on the molecular dynamics of ionic deep eutectic solvents (acetamide + lithium nitrate/sodium thiocyanate) is reported. The study was carried out employing dielectric relaxation spectroscopy covering seven decades in frequency (10{sup −1}-10{sup 6} Hz) and in a wide temperature range from 373 K down to 173 K, accessing the dynamic observables both in liquid and glassy state. The dielectric response of the ionic system has been presented in the dynamic window of modulus formalism to understand the conductivity relaxation and its possible connection to the origin of localized motion. Two secondary relaxation processes appear below glass transition temperature. Our findings provide suitable interpretation on the nature of secondary Johari-Goldstein process describing the ion translation and orientation of dipoles in a combined approach using Ngai’s coupling model. A nearly constant loss feature is witnessed at shorter times/lower temperatures. We also discuss the ac conductivity scaling behavior using Summerfield approach and random free energy barrier model which establish the time-temperature superposition principle. These experimental observations have fundamental importance on theoretical elucidation of the conductivity relaxation and glass transition phenomena in molten ionic conductors.

  3. Iron species determination by task-specific ionic liquid-based in situ solvent formation dispersive liquid-liquid microextraction combined with flame atomic absorption spectrometry.

    Science.gov (United States)

    Sadeghi, Susan; Ashoori, Vahid

    2017-10-01

    The task-specific ionic liquid (TSIL) of 1-ethyl-3-methylimidazolium bromide functionalized with 8-hydroxyquinoline was used as a chelating agent and extracting solvent for dispersive liquid-liquid microextraction and subsequent determination of Fe(III) by flame atomic absorption spectrometry. The in situ solvent formation of TSIL using KPF 6 provided the desired water-immiscible ionic liquid. The total Fe concentration could be determined after pre-oxidation of Fe(II) to Fe(III). Various factors affecting the proposed extraction procedure were optimized. The proposed analytical conditions were: sample pH 5, TSIL amount 0.3% (w/v), KPF 6 amount 0.15% (w/v), anti-sticking 0.1% (w/v) and salt concentration 5% (w/v). Under optimal conditions, the linear dynamic ranges for Fe(III) and total Fe were 20-80 and 20-110 ng mL -1 , respectively, with a detection limit of 6.9 ng mL -1 for Fe(III) and relative standard deviation of 2.2%. The proposed method was successfully applied to the determination of trace Fe(III) in water (underground, tap, refined water and artificial sea water) and beverage (apple, tomato, and tea) samples. The developed method offers advantages such as simplicity, ease of operation, and extraction of Fe(III) from aqueous solutions without the use of organic solvent. It was successfully applied for iron speciation in different real samples. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  4. Effect of the ionic strength of pulsed electric field treatment medium on the physicochemical and structural characteristics of lactoferrin.

    Science.gov (United States)

    Sui, Qian; Roginski, Hubert; Williams, Roderick P W; Wooster, Tim J; Versteeg, Cornelis; Wan, Jason

    2010-11-24

    Pulsed electric field (PEF) treatment (35 kV cm(-1) for 19.2 μs using bipolar 2 μs pulses) was conducted on bovine lactoferrin (LF; 0.4 mg mL(-1)) prepared in simulated milk ultrafiltrate (SMUF), at concentrations between 0.2× and 2× normal strength, with electrical conductivities ranging from 0.17 to 1.04 S m(-1). The physicochemical and structural characteristics (LF content by a spectrophotometric and an ELISA method, surface hydrophobicity, electrophoretic mobility, far-UV circular dichroism spectra, and tryptophan fluorescence) of LF dissolved in SMUF of all strengths tested were not changed after PEF treatment. The PEF treatment of LF in 0.2 strength SMUF did not cause the release of LF-bound ferric ion into the aqueous phase, with a concentration of LF-bound iron being the same as that of the untreated LF control (174 μg L(-1)). However, in treatment media with higher ionic strengths, ferric ion was released from the LF molecule into the aqueous phase. The concentration of LF-bound iron decreased from 174 μg L(-1) for the LF treated in 0.2 strength SMUF to 80 μg L(-1) for that treated in double-strength SMUF. The results suggest that the PEF-induced iron depletion of LF does not appear to cause an appreciable conformational change in LF molecules. PEF treatment could be developed as a novel physical way to produce iron-depleted LF, as an alternative to the existing chemical method.

  5. Advances in QSPR/QSTR models of ionic liquids for the design of greener solvents of the future.

    Science.gov (United States)

    Das, Rudra Narayan; Roy, Kunal

    2013-02-01

    In order to protect the life of all creatures living in the environment, the toxicity arising from various hazardous chemicals must be controlled. This imposes a serious responsibility on different chemical, pharmaceutical, and other biological industries to produce less harmful chemicals. Among various international initiatives on harmful aspects of chemicals, the 'Green Chemistry' ideology appears to be one of the most highlighted concepts that focus on the use of eco-friendly chemicals. Ionic liquids are a comparatively new addition to the huge garrison of chemical compounds released from the industry. Extensive research on ionic liquids in the past decade has shown them to be highly useful chemicals with a good degree of thermal and chemical stability, appreciable task specificity and minimal environmental release resulting in a notion of 'green chemical'. However, studies have also shown that ionic liquids are not intrinsically non-toxic agents and can pose severe degree of toxicity as well as the risk of bioaccumulation depending upon their structural components. Moreover, ionic liquids possess issues of waste generation during synthesis as well as separation problems. Predictive quantitative structure-activity relationship (QSAR) models constitute a rational opportunity to explore the structural attributes of ionic liquids towards various physicochemical and toxicological endpoints and thereby leading to the design of environmentally more benevolent analogues with higher process selectivity. Such studies on ionic liquids have been less extensive compared to other industrial chemicals. The present review attempts to summarize different QSAR studies performed on these chemicals and also highlights the safety, health and environmental issues along with the application specificity on the dogma of 'green chemistry'.

  6. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, an efficient solvent for extraction of acetone from aqueous solutions

    International Nuclear Information System (INIS)

    Saien, Javad; Badieh, Marjan Mohammadi Sarab; Norouzi, Mahdi; Salehzadeh, Sadegh

    2015-01-01

    Highlights: • The use of HMIMPF_6 as a green ionic was feasible in the extraction of acetone from water. • The binodal curves were determined by cloud point measurement method. • High level separation factor of acetone between the ionic liquid and water were achieved. • The thermodynamic properties of HMIMPF_6 were obtained by the Density Functional Theory calculations. • The NRTL and UNIQUAC models were applied satisfactorily to correlate the equilibrium data. - Abstract: (Liquid + liquid) equilibrium (LLE) of the chemical system of {water + acetone + 1-Hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF_6) ionic liquid} was studied at different temperatures of (293.2, 298.2 and 303.2) K and under atmospheric pressure of 81.5 kPa. The results show that HMIMPF_6 provides the acetone distribution coefficient and separation factor values within (0.8813 to 1.2351) and (3.0 to 54.4), respectively; indicating the high capability of the ionic liquid for extraction of acetone from aqueous solutions. In most cases, acetone solubility in the ionic liquid is higher than in water, especially at higher solute concentrations. Meanwhile, higher separation factor is relevant to the lower temperature due to lower (water + ionic liquid) miscibility. The consistency of tie line data, at each temperature, was examined with Othmer–Tobias correlation. The values were nicely reproduced with the well-known NRTL and UNIQUAC models. Accordingly, the required thermodynamic properties of HMIMPF_6 were obtained by the Density Functional Theory (DFT) calculations, carried out at the M06/6-311++G"∗"∗ level of theory. The root mean square deviations (RMSD) between experimental and model concentration values were 0.0192 and 0.0255, respectively; indicating close agreement of the both models.

  7. Comparative study on sorption of radiocobalt to montmorillonite and its Al-pillared and cross-linked samples. Effect of pH, ionic strength and fulvic acid

    International Nuclear Information System (INIS)

    Yu, S.; Cheng, J.; Chen, C.; Wang, X.

    2007-01-01

    Effects of pH, ionic strength and fulvic acid on sorption of radiocobalt on montmorillonite and its Al-pillared and cross-linked samples were studied using batch technique. The results indicate that the sorption of cobalt is strongly dependent on pH values and independent of ionic strength. Fulvic acid enhances the sorption of cobalt slightly at low pH, but has no influence at high pH values. Surface complexation is considered the main mechanism of cobalt sorption to montmorillonite. The sequences of FA/Co 2+ additions to the system did not affect cobalt sorption. (author)

  8. On the addition of conducting ceramic nanoparticles in solvent-free ionic liquid electrolyte for dye-sensitized solar cells

    KAUST Repository

    Lee, Chuan-Pei; Lee, Kun-Mu; Chen, Po-Yen; Ho, Kuo-Chuan

    2009-01-01

    ) have been used, for the first time, in dye-sensitized solar cells (DSSCs), and the incorporation of TiC nanoparticles in a binary ionic liquid electrolyte on the cell performance has been investigated. Cell conversion efficiency with 0.6 wt% TiC reached

  9. An Efficient Synthesis of 3,4-Dihydropyrimidin-2(1H-Ones and Thiones Catalyzed by a Novel Brønsted Acidic Ionic Liquid under Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Yonghong Zhang

    2015-02-01

    Full Text Available We report here an efficient and green method for Biginelli condensation reaction of aldehydes, β-ketoesters and urea or thiourea catalyzed by Brønsted acidic ionic liquid [Btto][p-TSA] under solvent-free conditions. Compared to the classical Biginelli reaction conditions, the present method has the advantages of giving good yields, short reaction times, near room temperature conditions and the avoidance of the use of organic solvents and metal catalyst.

  10. Bactericidal activity of LFchimera is stronger and less sensitive to ionic strength than its constituent lactoferricin and lactoferrampin peptides.

    Science.gov (United States)

    Bolscher, Jan G M; Adão, Regina; Nazmi, Kamran; van den Keybus, Petra A M; van 't Hof, Wim; Nieuw Amerongen, Arie V; Bastos, Margarida; Veerman, Enno C I

    2009-01-01

    The innate immunity factor lactoferrin harbours two antimicrobial moieties, lactoferricin and lactoferrampin, situated in close proximity in the N1 domain of the molecule. Most likely they cooperate in many of the beneficial activities of lactoferrin. To investigate whether chimerization of both peptides forms a functional unit we designed a chimerical structure containing lactoferricin amino acids 17-30 and lactoferrampin amino acids 265-284. The bactericidal activity of this LFchimera was found to be drastically stronger than that of the constituent peptides, as was demonstrated by the need for lower dose, shorter incubation time and less ionic strength dependency. Likewise, strongly enhanced interaction with negatively charged model membranes was found for the LFchimera relative to the constituent peptides. Thus, chimerization of the two antimicrobial peptides resembling their structural orientation in the native molecule strikingly improves their biological activity.

  11. Computer-aided model analysis for ionic strength-dependent effective charge of protein in ion-exchange chromatography

    DEFF Research Database (Denmark)

    Lim, Young-il; Jørgensen, Sten Bay; Kim, In-Ho

    2005-01-01

    differential algebraic equation (PDAE) system, a fast and accurate numerical method (i.e., conservation element/solution element (CE/SE) method), is proposed. Sensitivity and elasticity of the model parameters (e.g., steric/shape factors, adsorption heat coefficient, effective protein charge, equilibrium...... constant, mass transfer coefficient, axial dispersion coefficient and bed voidage) are analyzed for a BSA-salt system in a low protein concentration range. Within a low concentration range of bovine serum albumin (BSA) where linear adsorption isotherms are shown, the adsorption heat coefficient, shape...... salt concentrations, it is proposed that the effective protein charge could depend upon the salt concentration (or ionic strength). The reason for this dependence may be a steric hindrance of protein binding sites combined with a salt shielding effect neutralizing the surface charges of the protein. (c...

  12. Flashphotolysis investigations of the influence of the ionic strength on the kinetics of energy transfer reactions. Investigation of the reaction of Tb(III)- and Eu(III)-trisdipicolinate with different charged iron compounds

    International Nuclear Information System (INIS)

    Dorle, A.

    1999-01-01

    Luminescent lanthanide complexes are especially important as labels for the investigation of biological substances. The rare earths are employed as probes and are often able to substitute more expensive radioactive labels. The kinetic investigations of the reactions of Tb(III)- and Eu(III)-trisdipicolinate (charge: 3**-) with different charged iron complexes as quenchers (charge: 3 - , 1 - , 2 + ) (solvent: H 2 O) at varying ionic strength give results that can help to find out more details about how the intermolecular energy transfer takes place. By creating a Stern-Volmer plot one can get the rate constant of the luminescent quenching: Plotting the rate constants of quenching taken from the timeresolved flashphotolysis measurement (y-axis) versus the concentration of the quencher (x-axis) the resulting slope equals a rate constant k 2 of 2 nd order. (author)

  13. Assessing the influence of media composition and ionic strength on drug release from commercial immediate-release and enteric-coated aspirin tablets.

    Science.gov (United States)

    Karkossa, Frank; Klein, Sandra

    2017-10-01

    The objective of this test series was to elucidate the importance of selecting the right media composition for a biopredictive in-vitro dissolution screening of enteric-coated dosage forms. Drug release from immediate-release (IR) and enteric-coated (EC) aspirin formulations was assessed in phosphate-based and bicarbonate-based media with different pH, electrolyte composition and ionic strength. Drug release from aspirin IR tablets was unaffected by media composition. In contrast, drug release from EC aspirin formulations was affected by buffer species and ionic strength. In all media, drug release increased with increasing ionic strength, but in bicarbonate-based buffers was delayed when compared with that in phosphate-based buffers. Interestingly, the cation species in the dissolution medium had also a clear impact on drug release. Drug release profiles obtained in Blank CarbSIF, a new medium simulating pH and average ionic composition of small intestinal fluid, were different from those obtained in all other buffer compositions studied. Results from this study in which the impact of various media parameters on drug release of EC aspirin formulations was systematically screened clearly show that when developing predictive dissolution tests, it is important to simulate the ionic composition of intraluminal fluids as closely as possible. © 2017 Royal Pharmaceutical Society.

  14. Transport and Retention of TiO2 Rutile Nanoparticles in Saturated Porous Media: Influence of Solution pH, Ionic Strength, and the Presence of Humic Acid

    Science.gov (United States)

    The influence of solution pH, ionic strength, and varying concentrations of the Suwannee River Humic Acid (SRHA) on the transport of titanium dioxide (TiO2, rutile) nanoparticle aggregates (nTiO2) in saturated porous media was investigated through systematically examining the tra...

  15. Effects of hydrodynamic mixing intensity coupled with ionic strength on the initial stage dynamics of bridging flocculation of polystyrene latex particles with polyelectrolyte

    NARCIS (Netherlands)

    Adachi, Y.; Matsumoto, T.; Cohen Stuart, M.A.

    2002-01-01

    Effects of hydrodynamic mixing intensity on the initial stage dynamics of bridging flocculation induced by adsorbing polyelectrolyte were analyzed as an extension of previous report on the effect of ionic strength (J. Coll. Int. Sci. 204 (1998) 328). Mixing condition were changed by adopting forked

  16. Adsorption of a Textile Dye on Commercial Activated Carbon: A Simple Experiment to Explore the Role of Surface Chemistry and Ionic Strength

    Science.gov (United States)

    Martins, Angela; Nunes, Nelson

    2015-01-01

    In this study, an adsorption experiment is proposed using commercial activated carbon as adsorbent and a textile azo dye, Mordant Blue-9, as adsorbate. The surface chemistry of the activated carbon is changed through a simple oxidation treatment and the ionic strength of the dye solution is also modified, simulating distinct conditions of water…

  17. The influence of a fulvic acid on the adsorption of europium and strontium by alumina and quartz: effects of pH and ionic strength

    International Nuclear Information System (INIS)

    Norden, M.; Ephraim, J.H.; Allard, B.

    1994-01-01

    A batch method has been employed to study the adsorption of trace quantities of Eu and Sr on α-Al 2 O 3 and SiO 2 as a function of pH (3-9), ionic strength (0.10 and 0.01 M NaClO 4 ) and the presence of a well-characterized aquatic fulvic acid (FA). A comparison of Eu and Sr adsorption by alumina showed that FA could both reduce and enhance metal ion adsorption. In the absence of FA the adsorption of the metal ions onto alumina was a function of both pH and ionic strength. In the presence of FA the ionic strength effect on the Eu adsorption vanished, while the Sr adsorption showed a clear dependence on ionic strength. The adsorption of Eu and Sr on quartz was lower than the adsorption of the metals on alumina. Additionally, the adsorption of Eu and Sr on quartz was apparently lower than the adsorption on alumina in the presence of Fa. For both metal ions the adsorption on quartz was higher at 0.10 M than at 0.01 M NaClO 4 - an observation that was reversed in the case of alumina. Increasing concentrations of FA lowered the pH at which Eu adsorption on alumina would be reduced. (orig.)

  18. SORPTION OF CU AND ZN TO KAOLINITE AND IRON OXIDE: EFFECTS OF HUMIC ACID AND IONIC STRENGTH AND IMPLICATIONS FOR STORMWATER RUNOFF

    Science.gov (United States)

    Heavy metals are common pollutants in wet weather flows and urban waterways. Changes in ionic strength, whether from mixing with saline waters, road salt, or from the large osmotic adjustment needed for the Microtox toxicity assay, affect the aqueous chemistry of stormwater runof...

  19. Effects of solvent volatilization time on the bond strength of etch-and-rinse adhesive to dentin using conventional or deproteinization bonding techniques.

    Science.gov (United States)

    de Sousa Júnior, José Aginaldo; Carregosa Santana, Márcia Luciana; de Figueiredo, Fabricio Eneas Diniz; Faria-E-Silva, André Luis

    2015-08-01

    This study determined the effect of the air-stream application time and the bonding technique on the dentin bond strength of adhesives with different solvents. Furthermore, the content and volatilization rate of the solvents contained in the adhesives were also evaluated. Three adhesive systems with different solvents (Stae, SDI, acetone; XP Bond, Dentsply De Trey, butanol; Ambar, FGM, ethanol) were evaluated. The concentrations and evaporation rates of each adhesive were measured using an analytical balance. After acid-etching and rinsing, medium occlusal dentin surfaces of human molars were kept moist (conventional) or were treated with 10% sodium hypochlorite for deproteinization. After applying adhesives over the dentin, slight air-stream was applied for 10, 30 or 60 sec. Composite cylinders were built up and submitted to shear testing. The data were submitted to ANOVA and Tukey's test (α = 0.05). Stae showed the highest solvent content and Ambar the lowest. Acetone presented the highest evaporation rate, followed by butanol. Shear bond strengths were significantly affected only by the factors of 'adhesive' and 'bonding technique' (p Stae showed the lowest bond strength values (p < 0.05), while no significant difference was observed between XP Bond and Ambar. Despite the differences in content and evaporation rate of the solvents, the duration of air-stream application did not affect the bond strength to dentin irrespective of the bonding technique.

  20. The Hinge Segment of Human NADPH-Cytochrome P450 Reductase in Conformational Switching: The Critical Role of Ionic Strength

    Directory of Open Access Journals (Sweden)

    Diana Campelo

    2017-10-01

    Full Text Available NADPH-cytochrome P450 reductase (CPR is a redox partner of microsomal cytochromes P450 and is a prototype of the diflavin reductase family. CPR contains 3 distinct functional domains: a FMN-binding domain (acceptor reduction, a linker (hinge, and a connecting/FAD domain (NADPH oxidation. It has been demonstrated that the mechanism of CPR exhibits an important step in which it switches from a compact, closed conformation (locked state to an ensemble of open conformations (unlocked state, the latter enabling electron transfer to redox partners. The conformational equilibrium between the locked and unlocked states has been shown to be highly dependent on ionic strength, reinforcing the hypothesis of the presence of critical salt interactions at the interface between the FMN and connecting FAD domains. Here we show that specific residues of the hinge segment are important in the control of the conformational equilibrium of CPR. We constructed six single mutants and two double mutants of the human CPR, targeting residues G240, S243, I245 and R246 of the hinge segment, with the aim of modifying the flexibility or the potential ionic interactions of the hinge segment. We measured the reduction of cytochrome c at various salt concentrations of these 8 mutants, either in the soluble or membrane-bound form of human CPR. All mutants were found capable of reducing cytochrome c yet with different efficiency and their maximal rates of cytochrome c reduction were shifted to lower salt concentration. In particular, residue R246 seems to play a key role in a salt bridge network present at the interface of the hinge and the connecting domain. Interestingly, the effects of mutations, although similar, demonstrated specific differences when present in the soluble or membrane-bound context. Our results demonstrate that the electrostatic and flexibility properties of the hinge segment are critical for electron transfer from CPR to its redox partners.

  1. Ion Exchange Distribution Coefficient Tests and Computer Modeling at High Ionic Strength Supporting Technetium Removal Resin Maturation

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Charles A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hamm, L. Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, Frank G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McCabe, Daniel J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-12-19

    The primary treatment of the tank waste at the DOE Hanford site will be done in the Waste Treatment and Immobilization Plant (WTP) that is currently under construction. The baseline plan for this facility is to treat the waste, splitting it into High Level Waste (HLW) and Low Activity Waste (LAW). Both waste streams are then separately vitrified as glass and poured into canisters for disposition. The LAW glass will be disposed onsite in the Integrated Disposal Facility (IDF). There are currently no plans to treat the waste to remove technetium, so its disposition path is the LAW glass. Due to the water solubility properties of pertechnetate and long half-life of 99Tc, effective management of 99Tc is important to the overall success of the Hanford River Protection Project mission. To achieve the full target WTP throughput, additional LAW immobilization capacity is needed, and options are being explored to immobilize the supplemental LAW portion of the tank waste. Removal of 99Tc, followed by off-site disposal, would eliminate a key risk contributor for the IDF Performance Assessment (PA) for supplemental waste forms, and has potential to reduce treatment and disposal costs. Washington River Protection Solutions (WRPS) is developing some conceptual flow sheets for supplemental LAW treatment and disposal that could benefit from technetium removal. One of these flowsheets will specifically examine removing 99Tc from the LAW feed stream to supplemental immobilization. To enable an informed decision regarding the viability of technetium removal, further maturation of available technologies is being performed. This report contains results of experimental ion exchange distribution coefficient testing and computer modeling using the resin SuperLig® 639a to selectively remove perrhenate from high ionic strength simulated LAW. It is advantageous to operate at higher concentration in order to treat the waste

  2. Analysis of responsive characteristics of ionic-strength-sensitive hydrogel with consideration of effect of equilibrium constant by a chemo-electro-mechanical model.

    Science.gov (United States)

    Li, Hua; Lai, Fukun; Luo, Rongmo

    2009-11-17

    A multiphysics model is presented in this paper for analysis of the influence of various equilibrium constants on the smart hydrogel responsive to the ionic strength of environmental solution, and termed the multieffect-coupling ionic-strength stimulus (MECis) model. The model is characterized by a set of partial differential governing equations by consideration of the mass and momentum conservations of the system and coupled chemical, electrical, and mechanical multienergy domains. The Nernst-Planck equations are derived by the mass conservation of the ionic species in both the interstitial fluid of the hydrogel and the surrounding solution. The binding reaction between the fixed charge groups of the hydrogel and the mobile ions in the solution is described by the fixed charge equation, which is based on the Langmuir monolayer theory. As an important effect for the binding reaction, the equilibrium constant is incorporated into the fixed charge equation. The kinetics of the hydrogel swelling/deswelling is illustrated by the mechanical equation, based on the law of momentum conservation for the solid polymeric networks matrix within the hydrogel. The MECis model is examined by comparison of the numerical simulations and experiments from open literature. The analysis of the influence of different equilibrium constants on the responsive characteristics of the ionic-strength-sensitive hydrogel is carried out with detailed discussion.

  3. Spectroscopic investigations on sorption of uranium onto suspended bentonite. Effects of pH, ionic strength and complexing anions

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Parveen Kumar; Pathak, Priyanath; Mohapatra, Manoj; Mohapatra, Prasanta Kumar [Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry Div.; Yadav, Ashok Kumar; Jha, Sambhunath; Bhattacharyya, Dibyendu [Bhabha Atomic Research Centre, Mumbai (India). Atomic and Molecular Physics Div.

    2015-06-01

    Batch sorption experiments were carried out under aerobic conditions to understand the sorption behavior of U(VI) onto bentonite clay under varying pH (2-8) and ionic strength (I = 0.01 - 1 M (NaClO{sub 4})) conditions. The influences of different complexing anions (1 x 10{sup -4} M) such as oxalic acid (ox), carbonate (CO{sub 3}{sup 2-}), citric acid (cit), and humic acid (HA, 10 mg/L) on the sorption behavior were also investigated. The sorption of U(VI) increased with increasing pH up to pH 6 beyond which a decrease was attributed to the formation of anionic carbonate species. Marginal influence of the change in the ionic strength of the medium on the sorption profile of uranium suggested inner-sphere complexation onto the bentonite surface. The presence of humic acid showed interesting sorption profile with varying pH. Initially, there was an enhancement in the sorption with increased pH followed by a plateau and finally a decrease thereafter due to the formation of aqueous U(VI)-humate complexes. Spectroscopic studies such as UV spectrophotometry, luminescence and extended X-ray absorption fine structure (EXAFS) measurements were also performed to understand the changes in aqueous speciation of U(VI) ion. The luminescence yields of different aqueous U(VI) species followed the order: U(VI){sub Hydroxy} > U(VI){sub HumicAcid} > U(VI){sub carbonate} > U(VI){sub citrate}. The lower luminescence yield of U(VI)carbonate complex can be attributed to the strong dynamic quenching by carbonate at room temperature. The U(VI) samples shows two distinct life-time suggesting the presence of the different luminescent U(VI) species. Similar trend was observed for U(VI)-bentonite suspension in presence/absence of the complexing ligands. There was luminescence quenching for the sorbed U(VI) due to surface complexation. These observations were further supported by spectrophotometric measurements. EXAFS spectra of U(VI) samples were recorded in luminescence mode at the U L{sub 3

  4. Determination of UV filters in high ionic strength sample solutions using matrix-compatible coatings for solid-phase microextraction.

    Science.gov (United States)

    An, Jiwoo; Anderson, Jared L

    2018-05-15

    A double-confined polymeric ionic liquid (PIL) sorbent coating was fabricated for the determination of nine ultraviolet (UV) filters in sample solutions containing high salt content by direct immersion solid-phase microextraction (DI-SPME) coupled to high-performance liquid chromatography (HPLC). The IL monomer and crosslinker cations and anions, namely, 1-vinyl-3-decylimidazolium styrenesulfonate ([VImC 10 ][SS]) and 1,12-di(3-vinylbenzylimidazolium) dodecane distyrenesulfonate ([(VBIm) 2 C 12 ] 2[SS]), were co-polymerized to create a highly stable sorbent coating which allowed for up to 120 direct-immersion extractions in 25% NaCl (w/v) solution without a decrease in its extraction capability. Extraction and desorption parameters such as desorption solvent, agitation rate, extraction time, desorption solvent volume, and desorption time were evaluated and optimized. The analytical performance of the styrenesulfonate anion-based PIL fiber, PIL fiber containing chloride anions, and a commercially available polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber were compared. Coefficients of determination (R 2 ) for the styrenesulfonate anion-based PIL fiber ranged from 0.995 to 0.999 and the limits of detection (LODs) varied from 0.1 to 5 µg L -1 . The developed method was successfully applied in real water samples including tap, pool, and lake water, and acceptable relative recovery values were obtained. The lifetime of the PIL fiber containing chloride anions as well as the PDMS/DVB fiber were considerably shorter than the PIL fiber containing the styrenesulfonate anion, with both fibers showing a notable decrease in reproducibility and significant damage to the sorbent coating surface after 40 and 70 extractions, respectively. The R 2 values for the chloride anion containing PIL fiber were at or higher than 0.991 with LODs ranging from 0.5 to 5 µg L -1 . For the PDMS/DVB fiber, R 2 values ranged from 0.992 to 0.999 and LODs were found to be as low as 0.2

  5. Separation of toluene from n-heptane by liquid–liquid extraction using binary mixtures of [bpy][BF4] and [4bmpy][Tf2N] ionic liquids as solvent

    International Nuclear Information System (INIS)

    García, Silvia; Larriba, Marcos; García, Julián; Torrecilla, José S.; Rodríguez, Francisco

    2012-01-01

    Highlights: ► Binary mixtures of ionic liquids as extraction solvents of aromatics. ► [4bmpy][Tf 2 N] shows higher capacity but lower selectivity than sulfolane. ► [bpy][BF 4 ] shows lower capacity but higher selectivity than sulfolane. ► Mixed {[4bmpy][Tf 2 N] + [bpy][BF 4 ]} improves both extractive properties. - Abstract: The use of binary mixture of ionic liquids N-butylpyridinium tetrafluoroborate ([bpy][BF 4 ]), and 1-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4bmpy][Tf 2 N]) in the liquid–liquid extraction of toluene from n-heptane has been investigated at 313.2 K and atmospheric pressure. The experimental capacity of extraction and selectivity for this binary mixture has proved to be intermediate to those corresponding to the pure ionic liquids, and they can be predicted using a logarithmic–linear model of solubility. Furthermore, the results showed that the use of binary mixture of {[bpy][BF 4 ] + [4bmpy][Tf 2 N]} at a mole solvent composition around 0.7 for [bpy][BF 4 ] improves both the capacity of extraction of toluene and the selectivity with respect to those of sulfolane, the organic solvent taken as a benchmark. Thus, this mixed ionic liquid could be likely to be used in the extraction of aromatic from aliphatic in replacement to sulfolane.

  6. Rice Starch Particle Interactions at Air/Aqueous Interfaces—Effect of Particle Hydrophobicity and Solution Ionic Strength

    Science.gov (United States)

    McNamee, Cathy E.; Sato, Yu; Wiege, Berthold; Furikado, Ippei; Marefati, Ali; Nylander, Tommy; Kappl, Michael; Rayner, Marilyn

    2018-01-01

    Starch particles modified by esterification with dicarboxylic acids to give octenyl succinic anhydride (OSA) starch is an approved food additive that can be used to stabilize oil in water emulsions used in foods and drinks. However, the effects of the OSA modification of the starch particle on the interfacial interactions are not fully understood. Here, we directly measured the packing of films of rice starch granules, i.e., the natural particle found inside the plant, at air/aqueous interfaces, and the interaction forces in that system as a function of the particle hydrophobicity and ionic strength, in order to gain insight on how starch particles can stabilize emulsions. This was achieved by using a combined Langmuir trough and optical microscope system, and the Monolayer Interaction Particle Apparatus. Native rice starch particles were seen to form large aggregates at air/water interfaces, causing films with large voids to be formed at the interface. The OSA modification of the rice starches particles decreased this aggregation. Increasing the degree of modification improved the particle packing within the film of particles at the air/water interface, due to the introduction of inter-particle electrostatic interactions within the film. The introduction of salt to the water phase caused the particles to aggregate and form holes within the film, due to the screening of the charged groups on the starch particles by the salt. The presence of these holes in the film decreased the stiffness of the films. The effect of the OSA modification was concluded to decrease the aggregation of the particles at an air/water interface. The presence of salts, however, caused the particles to aggregate, thereby reducing the strength of the interfacial film. PMID:29868551

  7. Effect of pH, ionic strength and humic acid on the sorption of uranium(VI) to attapulgite

    Energy Technology Data Exchange (ETDEWEB)

    Niu Zhiwei [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China); Fan Qiaohui [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China)], E-mail: fanqiaohui@gmail.com; Wang Wenhua; Xu Junzheng [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China); Chen Lei [School of Chemical Engineering, Shandong University of Technology, 255049 Zibo, Shandong (China); Wu Wangsuo [Radiochemistry Laboratory, Lanzhou University, Lanzhou 730000, Gansu (China)], E-mail: wuws@lzu.edu.cn

    2009-09-15

    Attapulgite was investigated to remove UO{sub 2}{sup 2+} from aqueous solutions because of its strong sorption capacity. Herein, the attapulgite sample was characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and acid-base titration in detail. Sorption of UO{sub 2}{sup 2+} on attapulgite was strongly dependent on pH values and ionic strength. The presence of humic acid enhanced the sorption of UO{sub 2}{sup 2+} on attapulgite obviously because of the strong complexation of humic acid (HA) with UO{sub 2}{sup 2+} on attapulgite surface. Sorption of UO{sub 2}{sup 2+} on attapulgite was mainly dominated by ion-exchange or outer-sphere complexation at low pH values, and by inner-sphere complexation at high pH values. The results indicated that attapulgite was a suitable material for the preconcentration and solidification of UO{sub 2}{sup 2+} from large volume of solutions because of its negative surface charge and large surface areas.

  8. Roles of ionic strength and biofilm roughness on adhesion kinetics of Escherichia coli onto groundwater biofilm grown on PVC surfaces

    Science.gov (United States)

    Janjaroen, Dao; Ling, Fangqiong; Monroy, Guillermo; Derlon, Nicolas; Mogenroth, Eberhard; Boppart, Stephen A.; Liu, Wen-Tso; Nguyen, Thanh H.

    2013-01-01

    Mechanisms of Escherichia coli attachment on biofilms grown on PVC coupons were investigated. Biofilms were grown in CDC reactors using groundwater as feed solution over a period up to 27 weeks. Biofilm physical structure was characterized at the micro- and meso-scales using Scanning Electron Microscopy (SEM) and Optical Coherence Tomography (OCT), respectively. Microbial community diversity was analyzed with Terminal Restricted Fragment Length Polymorphism (T-RFLP). Both physical structure and microbial community diversity of the biofilms were shown to be changing from 2 weeks to 14 weeks, and became relatively stable after 16 weeks. A parallel plate flow chamber coupled with an inverted fluorescent microscope was also used to monitor the attachment of fluorescent microspheres and E. coli on clean PVC surfaces and biofilms grown on PVC surfaces for different ages. Two mechanisms of E. coli attachment were identified. The adhesion rate coefficients (kd) of E. coli on nascent PVC surfaces and 2-week biofilms increased with ionic strength. However, after biofilms grew for 8 weeks, the adhesion was found to be independent of solution chemistry. Instead, a positive correlation between kd and biofilm roughness as determined by OCT was obtained, indicating that the physical structure of biofilms could play an important role in facilitating the adhesion of E. coli cells. PMID:23497979

  9. Ionic Strength-Controlled Mn (Hydr)oxide Nanoparticle Nucleation on Quartz: Effect of Aqueous Mn(OH)2.

    Science.gov (United States)

    Jung, Haesung; Jun, Young-Shin

    2016-01-05

    The early formation of manganese (hydr)oxide nanoparticles at mineral-water interfaces is crucial in understanding how Mn oxides control the fate and transport of heavy metals and the cycling of nutrients. Using atomic force microscopy, we investigated the heterogeneous nucleation and growth of Mn (hydr)oxide under varied ionic strengths (IS; 1-100 mM NaNO3). Experimental conditions (i.e., 0.1 mM Mn(2+) (aq) concentration and pH 10.1) were chosen to be relevant to Mn remediation sites. We found that IS controls Mn(OH)2 (aq) formation, and that the controlled Mn(OH)2 (aq) formation can affect the system's saturation and subsequent Mn(OH)2 (s) and further Mn3O4 (s) nanoparticle formation. In 100 mM IS system, nucleated Mn (hydr)oxide particles had more coverage on the quartz substrate than those in 1 mM and 10 mM IS systems. This high IS also resulted in low supersaturation ratio and thus favor heterogeneous nucleation, having better structural matching between nucleating Mn (hydr)oxides and quartz. The unique information obtained in this work improves our understanding of Mn (hydr)oxide formation in natural as well as engineered aqueous environments, such as groundwater contaminated by natural leachate and acid mine drainage remediation.

  10. Release mechanism of doxazosin from carrageenan matrix tablets: Effect of ionic strength and addition of sodium dodecyl sulphate.

    Science.gov (United States)

    Kos, Petra; Pavli, Matej; Baumgartner, Saša; Kogej, Ksenija

    2017-08-30

    The polyelectrolyte matrix tablets loaded with an oppositely charged drug exhibit complex drug-release mechanisms. In this study, the release mechanism of a cationic drug doxazosin mesylate (DM) from matrix tablets based on an anionic polyelectrolyte λ-carrageenan (λ-CARR) is investigated. The drug release rates from λ-CARR matrices are correlated with binding results based on potentiometric measurements using the DM ion-sensitive membrane electrode and with molecular characteristics of the DM-λ-CARR-complex particles through hydrodynamic size measurements. Experiments are performed in solutions with different ionic strength and with the addition of an anionic surfactant sodium dodecyl sulphate (SDS). It is demonstrated that in addition to swelling and erosion of tablets, the release rates depend strongly on cooperative interactions between DM and λ-CARR. Addition of SDS at concentrations below its critical micelle concentration (CMC) slows down the DM release through hydrophobic binding of SDS to the DM-λ-CARR complex. On the contrary, at concentrations above the CMC SDS pulls DM from the complex by forming mixed micelles with it and thus accelerates the release. Results involving SDS show that the concentration of surfactants that are naturally present in gastrointestinal environment may have a great impact on the drug release process. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Using ionic liquid as the solvent to prepare Pd–Ni bimetallic nanoparticles by a pyrolysis method for ethanol oxidation reaction

    International Nuclear Information System (INIS)

    Ding, Keqiang; Yang, Hongwei; Cao, Yanli; Zheng, Chunbao; Rapole, Sowjanya B.; Guo, Zhanhu

    2013-01-01

    Room temperature ionic liquids (RTILs) of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) is used as the solvent for the first time to prepare multi-walled carbon nanotubes (MWCNTs) supported nanocomposite catalysts of Pd x Ni y (atomic ratios of Pd to Ni are 1:1, 1:1.5, 1:2, and 1:2.5) nanoparticles (denoted as Pd x Ni y /MWCNTs) by using a simple pyrolysis process. The Pd x Ni y /MWCNTs catalysts are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that the Pd x Ni y nanoparticles (NPs) are quite uniformly dispersed on the surface of MWCNTs with an average crystallite size of ∼7.0 nm. The electro-catalytic activity of the Pd x Ni y /MWCNTs catalysts for ethanol oxidation reaction (EOR) is examined by cyclic voltammetry (CV). It is revealed that the onset potential is ∼80 mV lower and the peak current is about three times higher for ethanol oxidation for MWCNT catalysts with Pd 1 Ni 1.5 compared to those of Pd/MWCNTs. The catalytic mechanisms of the Pd 1 Ni 1.5 /MWCNTs towards EOR are also proposed and discussed. - Highlights: • Introducing ionic liquids to the pyrolysis process for the preparation of Pd x Ni y nanoparticles. • Pd x Ni y nanoparticles with an average particle size of ∼7.0 nm were fabricated. • The peak current of EOR was about three times higher at Pd 1 Ni 1.5 compared to those of Pd

  12. Ionic liquid solvent bar micro-extraction of CdCln(n-2)- species for ultra-trace Cd determination in seawater.

    Science.gov (United States)

    Herce-Sesa, Belén; López-López, José A; Moreno, Carlos

    2018-02-01

    Water analysis of trace metals has been benefited by recent studies on sample preparation by liquid micro-extraction. However, there are still limitations for its application to seawater, such as the need of additives to preserve the sample or the availability of chemical extractants for the selective extraction from highly saline samples. In this work, a three phase solvent bar micro-extraction (3SBME) system containing the ionic liquid trioctylmethylammonium chloride (Aliquat ® 336) has been used for isolation and pre-concentration of Cd from seawater samples, due to its ability for ionic exchange of CdCl n (n-2)- . The system was optimized to work at the natural pH of seawater, and conditions for application to real samples were 0.18 M Aliquat ® 336 dissolved in kerosene with 0.25 M dodecan-1-ol as organic solution, 1.5 M HNO 3 as acceptor solution, 60 min extraction time, and 800 rpm stirring speed in the sample. Loss of organic solution into the sample during extraction was evaluated and revealed its dependence on stirring rate and extraction time. Under optimum conditions samples containing Cd 0.09-0.90 nM were pre-concentrated 65 times. GF-AAS was used for metal quantification with a limit of detection of 0.04 nM. Accuracy was successfully evaluated measuring Cd in a seawater certified reference material BCR-403. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Azole-Anion-Based Aprotic Ionic Liquids: Functional Solvents for Atmospheric CO2 Transformation into Various Heterocyclic Compounds.

    Science.gov (United States)

    Zhao, Yanfei; Wu, Yunyan; Yuan, Guangfeng; Hao, Leiduan; Gao, Xiang; Yang, Zhenzhen; Yu, Bo; Zhang, Hongye; Liu, Zhimin

    2016-10-06

    The chemical transformation of atmospheric CO 2 is of great significance yet still poses a great challenge. Herein, azole-anion-based aprotic ionic liquids (ILs) were synthesized by the deprotonation of weak proton donors (e.g., 2-methylimidazole, 4-methylimidazole, and 2,4-dimethylimidazole) with tetrabutylphosphonium hydroxide, [Bu 4 P][OH]. We found that these ILs, such as [Bu 4 P][2-MIm], could activate atmospheric CO 2 through the formation of carbamates. The resultant carbamate intermediates could further react with various types of substrate, including propargylic alcohols, 2-aminobenzonitriles, ortho-phenylenediamines, and 2-aminothiophenol, thereby producing α-alkylidene cyclic carbonates, quinazoline-2,4(1 H,3 H)-diones, benzimidazolones, and benzothiazoline, respectively, in moderate-to-good yields. Thus, we have achieved the transformation of CO 2 at atmospheric pressure, and we expect this method to open up new routes for the synthesis of various oxygen-containing heterocyclic compounds under metal-free conditions. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Preparation of Second Generation Ionic Liquids by Efficient Solvent-Free Alkylation of N-Heterocycles with Chloroalkanes

    Directory of Open Access Journals (Sweden)

    Werner Bonrath

    2008-01-01

    Full Text Available Non-conventional techniques, such as microwave (MW and power ultrasound(US as well as combined MW/US irradiation, have been used to promote one-potsynthesis of second-generation ionic liquids (ILs, cutting down reaction times andimproving yields. However, the use of chloroalkanes in the alkylation of N-heterocyclesrequires more drastic conditions if results are to match those obtained with more reactivealkyl halides. The present paper describes a series of MW- or MW/US-promoted ILpreparations starting from chloroalkanes and classic heterocycles (1-methylimidazole,pyridine and 1-methylpyrrolidine. When reactions were carried out under conventionalheating in an oil bath they required longer reaction times and gave poorer yields. 1H-NMRanalysis and ion-exchange chromatography showed that the present solventless procedureafforded ILs of satisfactory purity. The observed high yields (usually 70-98% isolated,and short reaction times showed that a straightforward access to ILs can be also achievedwith the use of alkyl chlorides, resulting in a considerable reduction of costs.

  15. Ionic liquid as a potential solvent for preparation of collagen-alginate-hydroxyapatite beads as bone filler.

    Science.gov (United States)

    Iqbal, Bushra; Sarfaraz, Zenab; Muhammad, Nawshad; Ahmad, Pervaiz; Iqbal, Jibran; Khan, Zia Ul Haq; Gonfa, Girma; Iqbal, Farasat; Jamal, Arshad; Rahim, Abdur

    2018-07-01

    In this study, collagen/alginate/hydroxyapatite beads having different proportions were prepared as bone fillers for the restoration of osteological defects. Ionic liquid was used to dissolve the collagen and subsequently the solution was mixed with sodium alginate solution. Hydroxyapatite was added in different proportions, with the rationale to enhance mechanical as well as biological properties. The prepared solutions were given characteristic bead shapes by dropwise addition into calcium chloride solution. The prepared beads were characterized using FTIR, XRD, TGA and SEM analysis. Microhardness testing was used to evaluate the mechanical properties. The prepared beads were investigated for water adsorption behavior to ascertain its ability for body fluid uptake and adjusted accordingly to the bone cavity. Drug loading and subsequently the antibacterial activity was investigated for the prepared beads. The biocompatibility was assessed using the hemolysis testing and cell proliferation assay. The prepared collagen-alginate-HA beads, having biocompatibility and good mechanical properties, have showed an option of promising biologically active bone fillers for bone regeneration.

  16. Effects of solvent volatilization time on the bond strength of etch-and-rinse adhesive to dentin using conventional or deproteinization bonding techniques

    Directory of Open Access Journals (Sweden)

    José Aginaldo de Sousa Júnior

    2015-08-01

    Full Text Available Objectives This study determined the effect of the air-stream application time and the bonding technique on the dentin bond strength of adhesives with different solvents. Furthermore, the content and volatilization rate of the solvents contained in the adhesives were also evaluated. Materials and Methods Three adhesive systems with different solvents (Stae, SDI, acetone; XP Bond, Dentsply De Trey, butanol; Ambar, FGM, ethanol were evaluated. The concentrations and evaporation rates of each adhesive were measured using an analytical balance. After acid-etching and rinsing, medium occlusal dentin surfaces of human molars were kept moist (conventional or were treated with 10% sodium hypochlorite for deproteinization. After applying adhesives over the dentin, slight air-stream was applied for 10, 30 or 60 sec. Composite cylinders were built up and submitted to shear testing. The data were submitted to ANOVA and Tukey's test (α = 0.05. Results Stae showed the highest solvent content and Ambar the lowest. Acetone presented the highest evaporation rate, followed by butanol. Shear bond strengths were significantly affected only by the factors of 'adhesive' and 'bonding technique' (p < 0.05, while the factor 'duration of air-stream' was not significant. Deproteinization of dentin increased the bond strength (p < 0.05. Stae showed the lowest bond strength values (p < 0.05, while no significant difference was observed between XP Bond and Ambar. Conclusions Despite the differences in content and evaporation rate of the solvents, the duration of air-stream application did not affect the bond strength to dentin irrespective of the bonding technique.

  17. Effect of surface chemistry, solution pH, and ionic strength on the removal of herbicides diuron and amitrole from water by an activated carbon fiber.

    Science.gov (United States)

    Fontecha-Cámara, M A; López-Ramón, M V; Alvarez-Merino, M A; Moreno-Castilla, C

    2007-01-30

    A study was conducted on the effects of carbon surface chemistry, solution pH, and ionic strength on the removal of diuron and amitrole from aqueous solutions by adsorption on an as-received and oxidized activated carbon fiber. Results obtained were explained by the surface characteristics of the adsorbents and the characteristics of the herbicide molecules. Under the experimental conditions used, diuron uptake was much higher than that of amitrole, despite its larger molecular dimensions, due to the lesser water solubility, greater hydrophobicity, and larger dipolar moment of diuron compared with amitrole. Uptake variations associated with differences in carbon surface oxidation, solution pH, and ionic strength were explained by corresponding changes in electrostatic, hydrophobic, and van der Waals interactions.

  18. Beyond the Debye length in high ionic strength solution: direct protein detection with field-effect transistors (FETs) in human serum.

    Science.gov (United States)

    Chu, Chia-Ho; Sarangadharan, Indu; Regmi, Abiral; Chen, Yen-Wen; Hsu, Chen-Pin; Chang, Wen-Hsin; Lee, Geng-Yen; Chyi, Jen-Inn; Chen, Chih-Chen; Shiesh, Shu-Chu; Lee, Gwo-Bin; Wang, Yu-Lin

    2017-07-12

    In this study, a new type of field-effect transistor (FET)-based biosensor is demonstrated to be able to overcome the problem of severe charge-screening effect caused by high ionic strength in solution and detect proteins in physiological environment. Antibody or aptamer-immobilized AlGaN/GaN high electron mobility transistors (HEMTs) are used to directly detect proteins, including HIV-1 RT, CEA, NT-proBNP and CRP, in 1X PBS (with 1%BSA) or human sera. The samples do not need any dilution or washing process to reduce the ionic strength. The sensor shows high sensitivity and the detection takes only 5 minutes. The designs of the sensor, the methodology of the measurement, and the working mechanism of the sensor are discussed and investigated. A theoretical model is proposed based on the finding of the experiments. This sensor is promising for point-of-care, home healthcare, and mobile diagnostic device.

  19. The effect of pH, buffer capacity and ionic strength on quetiapine fumarate release from matrix tablets prepared using two different polymeric blends.

    Science.gov (United States)

    Hamed, Rania; AlJanabi, Reem; Sunoqrot, Suhair; Abbas, Aiman

    2017-08-01

    The objective of this study was to investigate the effect of the different physiological parameters of the gastrointestinal (GI) fluid (pH, buffer capacity, and ionic strength) on the in vitro release of the weakly basic BCS class II drug quetiapine fumarate (QF) from two once-a-day matrix tablet formulations (F1 and F2) developed as potential generic equivalents to Seroquel ® XR. F1 tablets were prepared using blends of high and low viscosity grades of hydroxypropyl methylcellulose (HPMC K4M and K100LV, respectively), while F2 tablets were prepared from HPMC K4M and PEGylated glyceryl behenate (Compritol ® HD5 ATO). The two formulations attained release profiles of QF over 24 h similar to that of Seroquel ® XR using the dissolution medium published by the Food and Drug Administration (FDA). A series of solubility and in vitro dissolution studies was then carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH, buffer capacity and ionic strength range of the GIT. Solubility studies revealed that QF exhibits a typical weak base pH-dependent solubility profile and that the solubility of QF increases with increasing the buffer capacity and ionic strength of the media. The release profiles of QF from F1, F2 and Seroquel ® XR tablets were found to be influenced by the pH, buffer capacity and ionic strength of the dissolution media to varying degrees. Results highlight the importance of studying the physiological variables along the GIT in designing controlled release formulations for more predictive in vitro-in vivo correlations.

  20. Influence of ionic strength and surfactant concentration on electrostatic surfacial assembly of cetyltrimethylammonium bromide-capped gold nanorods on fully immersed glass.

    Science.gov (United States)

    Ferhan, Abdul Rahim; Guo, Longhua; Kim, Dong-Hwan

    2010-07-20

    The effect of ionic strength as well as surfactant concentration on the surface assembly of cetyltrimethylammonium bromide (CTAB)-capped gold nanorods (GNRs) has been studied. Glass substrates were modified to yield a net negative charge through electrostatic coating of polystyrenesulfonate (PSS) over a self-assembled monolayer (SAM) of positively charged aminopropyltriethoxysilane (APTS). The substrates were then fully immersed in GNR solutions at different CTAB concentrations and ionic strengths. Under slightly excess CTAB concentrations, it was observed that the density of GNRs immobilized on a substrate was predictably tunable through the adjustment of NaCl concentration over a wide range. Motivated by the experimental observation, we hypothesize that electrostatic shielding of charges around the GNRs affects the density of GNR immobilization. This model ultimately explains that at moderate to high CTAB concentrations a second electrostatic shielding effect contributed by excess CTAB molecules occurs, resulting in a parabolic trend of nanorod surface density when ionic strength is continually increased. In contrast, at a low CTAB concentration, the effect of ionic strength becomes much less significant due to insufficient CTAB molecules to provide for the second electrostatic shielding effect. The tunability of electrostatic-based surface assembly of GNRs enables the attainment of a dense surface assembly of nanorods without significant removal of CTAB or any other substituted stabilizing agent, both of which could compromise the stability and morphology of GNRs in solution. An additional study performed to investigate the robustness of such electrostatic-based surface assembly also proved its reliability to be used as biosensing platforms.

  1. Extensive Evaluation of the Conductor-like Screening Model for Real Solvents Method in Predicting Liquid-Liquid Equilibria in Ternary Systems of Ionic Liquids with Molecular Compounds.

    Science.gov (United States)

    Paduszyński, Kamil

    2018-04-12

    A conductor-like screening model for real solvents (COSMO-RS) is nowadays one of the most popular and commonly applied tools for the estimation of thermodynamic properties of complex fluids. The goal of this work is to provide a comprehensive review and analysis of the performance of this approach in calculating liquid-liquid equilibrium (LLE) phase diagrams in ternary systems composed of ionic liquid and two molecular compounds belonging to diverse families of chemicals (alkanes, aromatics, S/N-compounds, alcohols, ketones, ethers, carboxylic acid, esters, and water). The predictions are presented for extensive experimental database, including 930 LLE data sets and more than 9000 data points (LLE tie lines) reported for 779 unique ternary mixtures. An impact of the type of molecular binary subsystem on the accuracy of predictions is demonstrated and discussed on the basis of representative examples. The model's capability of capturing qualitative trends in the LLE distribution ratio and selectivity is also checked for a number of structural effects. Comparative analysis of two levels of quantum chemical theory (BP-TZVP-COSMO vs BP-TZVPD-FINE) for the input molecular data for COSMO-RS is presented. Finally, some general recommendations for the applicability of the model are indicated based on the analysis of the global performance as well as on the results obtained for systems relevant from the point of view of important separation problems.

  2. Deep Desulfurization of Diesel Fuels with Plasma/Air as Oxidizing Medium, Diperiodatocuprate (III) as Catalyzer and Ionic Liquid as Extraction Solvent

    Science.gov (United States)

    Ban, Lili; Liu, Ping; Ma, Cunhua; Dai, Bin

    2013-12-01

    In this paper, the oxidative desulfurization (ODS) system is directly applied to deal with the catalytic oxidation of sulfur compounds of sulfur-containing model oil by dielectric barrier discharge (DBD) plasma in the presence of air plus an extraction step with the oxidation-treated fuel put over ionic liquid [BMIM]FeCl4 (1-butyl-3-methylimidazolium tetrachloroferrate). This new system exhibited an excellent desulfurization effect. The sulfur content of DBT in diesel oil decreased from 200 ppm to 4.92 ppm (S removal rate up to 97.5%) under the following optimal reaction conditions: air flow rate (ν) of 60 mL/min, amplitude of applied voltage (U) on DBD of 16 kV, input frequency (f) of 79 kHz, catalyst amount (ω) of 1.25 wt%, reaction time (t) of 10 min. Moreover, a high desulfurization rate was obtained during oxidation of benzothiophene (BT) or 4,6-DMDBT (4,6-dimethyl-dibenzothiophene) under the aforementioned conditions. The oxidation reactivity of different S compounds was decreased in the order of DBT, 4,6-DMDBT and BT. The remarkable advantage of the novel ODS system is that the desulfurization condition applies in the presence of air at ambient conditions without peroxides, aqueous solvent or biphasic oil-aqueous solution system.

  3. Deep Desulfurization of Diesel Fuels with Plasma/Air as Oxidizing Medium, Diperiodatocuprate (III) as Catalyzer and Ionic Liquid as Extraction Solvent

    International Nuclear Information System (INIS)

    Ban Lili; Liu Ping; Ma Cunhua; Dai Bin

    2013-01-01

    In this paper, the oxidative desulfurization (ODS) system is directly applied to deal with the catalytic oxidation of sulfur compounds of sulfur-containing model oil by dielectric barrier discharge (DBD) plasma in the presence of air plus an extraction step with the oxidation-treated fuel put over ionic liquid [BMIM]FeCl 4 (1-butyl-3-methylimidazolium tetrachloroferrate). This new system exhibited an excellent desulfurization effect. The sulfur content of DBT in diesel oil decreased from 200 ppm to 4.92 ppm (S removal rate up to 97.5%) under the following optimal reaction conditions: air flow rate (ν) of 60 mL/min, amplitude of applied voltage (U) on DBD of 16 kV, input frequency (f) of 79 kHz, catalyst amount (ω) of 1.25 wt%, reaction time (t) of 10 min. Moreover, a high desulfurization rate was obtained during oxidation of benzothiophene (BT) or 4,6-DMDBT (4,6-dimethyl-dibenzothiophene) under the aforementioned conditions. The oxidation reactivity of different S compounds was decreased in the order of DBT, 4,6-DMDBT and BT. The remarkable advantage of the novel ODS system is that the desulfurization condition applies in the presence of air at ambient conditions without peroxides, aqueous solvent or biphasic oil-aqueous solution system. (plasma technology)

  4. Combination of deep eutectic solvent and ionic liquid to improve biocatalytic reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cell

    Science.gov (United States)

    Xu, Pei; Du, Peng-Xuan; Zong, Min-Hua; Li, Ning; Lou, Wen-Yong

    2016-05-01

    The efficient anti-Prelog asymmetric reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cells was successfully performed in a biphasic system consisting of deep eutectic solvent (DES) and water-immiscible ionic liquid (IL). Various DESs exerted different effects on the synthesis of (R)-2-octanol. Choline chloride/ethylene glycol (ChCl/EG) exhibited good biocompatibility and could moderately increase the cell membrane permeability thus leading to the better results. Adding ChCl/EG increased the optimal substrate concentration from 40 mM to 60 mM and the product e.e. kept above 99.9%. To further improve the reaction efficiency, water-immiscible ILs were introduced to the reaction system and an enhanced substrate concentration (1.5 M) was observed with C4MIM·PF6. Additionally, the cells manifested good operational stability in the reaction system. Thus, the efficient biocatalytic process with ChCl/EG and C4MIM·PF6 was promising for efficient synthesis of (R)-2-octanol.

  5. Graphene and graphene oxide modified by deep eutectic solvents and ionic liquids supported on silica as adsorbents for solid-phase extraction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoqin; Li, Guizhen; Row, Kyung Ho [Dept. of Chemistry and Chemical Engineering, Inha University, Incheon (Korea, Republic of)

    2017-02-15

    A novel deep eutectic solvent (DES) and ionic liquid (IL)-modified graphene (G) and graphene oxide (GO) were synthesized and used as effective adsorbents for the preconcentration of three chlorophenols (CPs), 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP), in environmental water samples prior to high-performance liquid chromatography (HPLC). The new materials were characterized by scanning electron microscopy (S-4200) and Fourier-transform infrared spectrometry. The prepared functionalized GO@silica shows remarkable adsorption capacity toward CPs. When used as solid-phase extraction (SPE) sorbents, a superior recovery (88.49–89.70%) could be obtained compared to commercial sorbents, such as silica and aminosilica. Based on this, a method for the analysis of CPs in water samples was established by coupling SPE with HPLC. These results highlight the potential new role of DES and IL-modified GO in the preparation of analytical samples.

  6. Interaction of nucleic acids with electrically charged surfaces. VII. The effect of ionic strength of neutral medium on the conformation of dna adsorbed on the mercury electrode.

    Science.gov (United States)

    Brabec, V

    1980-02-01

    Triangular-wave direct current (d.c.) voltammetry at a hanging mercury drop electrode and phase-selective alternating current (a.c.) polarography at a dropping mercury electrode were used for the investigation of adsorption of double-helical (ds) DNA at mercury electrode surfaces from neutral solutions of 0.05-0.4 M HCOONH4. It was found for the potential region T (from -0.1 V up to ca. -1.0 V) that the height of voltammetric peaks of ds DNA is markedly influenced by the initial potential only at relatively low ionic strength (mu) (from 0.05 up to ca. 0.3). Also a decrease of differential capacity (measured by means of a.c. polarography) in the region T depended markedly on the electrode potential only at relatively low ionic strength. The following conclusions were made concerning the interaction of ds DNA with a mercury electrode charged to potentials of the region T in neutral medium of relatively low ionic strength mu potentials in the Vicinity of the zero charge potential a higher number of ds DNA segments can be opened, probably as a consequence of the strain which could act on the ds DNA molecule in the course of the segmental adsorption/desorption process.

  7. Hydrolysis of polyacrylamide containing associative hydrophobic groups: effect of the degree of hydrolysis and ionic strength on the viscosity in aqueous medium

    International Nuclear Information System (INIS)

    Lima, Bruna V. de; Vidal, Rosangela R.L.; Reis, Jeanne H.C. dos; Balaban, Rosangela de C.

    2009-01-01

    The HAPAM-10N polymer (hydrophobically modified and partially hydrolyzed polyacrylamide) was obtained by partial hydrolysis of HAPAM (hydrophobically modified polyacrylamide) precursor containing very low amount of hydrophobic groups (0.75%) in 0.1 M NaCl and 0.25 M NaOH aqueous solutions, at 40 deg C for 10 min. Hydrolysis degree of 44.64 % was obtained by 13 C NMR. The viscosity of polymers solutions was evaluated as a function of polymer concentration, ionic strength and temperature, at constant shear rate. The viscosity of HAPAM solutions increased with polymer concentration, however, it did not change significantly with the increase of ionic strength, and decreased with the temperature enhancement. The viscosity of HAPAM-10N solutions increased significantly in distilled water, due to electrostatic repulsions among carboxylate groups. However, with the increase of polymer concentration, ionic strength and temperature, it was not observed a significant increase of viscosity, probably due to the low amount of hydrophobic groups and high hydrolysis degree. (author)

  8. Sorption of Am(III) on attapulgite/iron oxide magnetic composites. Effect of pH, ionic strength and humic acid

    International Nuclear Information System (INIS)

    Yu, T.; East China Institute of Technology, Fuzhou, Jiangxi; Fan, Q.H.; Wu, W.S.; Lanzhou Univ., Gansu; Liu, S.P.; Pan, D.Q.; Zhang, Y.Y.; Li, P.

    2012-01-01

    Attapulgite/iron oxide magnetic (ATP/IOM) composites was prepared, and the sorption behavior of Am(III) on that composites was studied as a function of pH, ionic strength, the solid-to-liquid ratio (m/V), contact time, and the concentration of Am(III) under ambient conditions using batch technique. The time to achieve the sorption equilibrium was less than 5 h. The sorption of Am(III) on ATP/IOM composites was strongly affected by pH and ionic strength. Though ion exchange reaction contributed to Am(III) sorption over low pH range and low ionic strength, the sorption was mainly dominated by surface complexion (i.e., outer- and/or inner-sphere complexes) in the whole observed pH range. In the presence of humic acid (HA), the sorption edge of Am(III) on ATP/IOM composites obviously shifted to lower pH; but Am(III) sorption gradually became weak after pH exceeded 4, which may be mainly in terms of the soluble complexes of HA-Am(III). (orig.)

  9. The Influence of High Drug Loading in Xanthan Tablets and Media with Different Physiological pH and Ionic Strength on Swelling and Release.

    Science.gov (United States)

    Mikac, Urša; Sepe, Ana; Baumgartner, Saša; Kristl, Julijana

    2016-03-07

    The formation of a gel coat around xanthan (Xan) tablets, empty or loaded with pentoxifylline (PF), and its release in media differing in pH and ionic strength by NMR, MR imaging, and two release methods were studied. The T1 and T2 NMR relaxation times in gels depend predominantly on Xan concentration; the presence of PF has negligible influence on them. It is interesting that the matrix swelling is primarily regulated by Xan despite high drug loading (25%, 50%). The gastric pH and high ionic strength of the media do not influence the position of the penetration and swelling fronts but do affect the erosion front and gel thickness. The different release profiles obtained in mixing and nonmixing in vitro methods are the consequence of matrix hydration level and erosion at the surface. In water and in diluted acid medium with low ionic strength, the main release mechanism is erosion, whereas in other media (pH 1.2, μ ≥ 0.20 M), anomalous transport dominates as was found out by fitting of measured data with theoretical model. Besides the in vitro investigation that mimics gastric conditions, mathematical modeling makes the product development more successful.

  10. A study on the swelling characteristics of a potential buffer material : Effect of ionic strength and temperature on the swelling pressure

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Owan; Cho, Won Jin; Chun, Kwan Sik [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-04-01

    This study is intended to investigate the effect of ionic strength and temperature on the swelling pressure of bentonite. The dry density for compacted bentonite was adjusted between 1.4 Mg/m{sup 3} - 1.8 Mg/m{sup 3}. The effect of temperature was tested at 20 deg C, 40 deg C, 60 deg C, 80 deg C, and the effect of ionic strength with distilled water, synthetic ground water, and 0.01 M - 0.1 M NaCl solution. The swelling pressure decreased with increasing ionic strength, and its dependency got lower at high dry density. Temperature had negligible effect on the swelling pressure of compacted bentonite, which could be explained by the change in hydration pressure, osmotic pressure, and pore water pressure in accordance with temperature. The swelling pressure of compacted bentonite with low dry density was dominated mainly by osmosis. However, hydration was thought to become important at higher dry density, compared with the osmosis. 32 refs., 11 figs., 4 tabs. (Author)

  11. [Verification of a decrease in the rigidity of the phage lambda DNA polymeric chain in low ionic strength aqueous solutions by testing the polymer-polymer interlink interactions].

    Science.gov (United States)

    Arutiunian, A V; Ivanova, M A; Kurliand, D I; Kapshin, Iu S; Landa, S B; Poshekhonov, S T; Drobchenko, E A; Shevelev, I V

    2011-01-01

    Changes in the rigidity of the polymetric chain of phage lambda double-strand DNA have been studied by laser correlation spectroscopy. It was shown that, as the ionic strength increases, the effect of the screening of the hydrodynamic interaction of the links of the polymeric chain specific for polymeric coils arises in a DNA solution. It is assumed that the screening occurs when the threshold of the overlapping of DNA coils is achieved. The overlapping of coils is the result of a previously observed significant rise of DNA coil size from abnormally small DNA coils in low ionic strength buffers (about 10(-2) M Na+ or less) to maximum possible large coils in the 5SSC and 5SSC-like buffers. Further analysis of the far interlink interactions in linear lambda phage DNA coils in similar buffers at pH 7 and 4 confirms the earlier proposal about the role of H+ ions in the appearance of abnormally small DNA coils. The abnormal decrease in the DNA coil size in low ionic strength buffers is not a specific feature of lambda phage DNA only.

  12. Development of an in situ solvent formation microextraction and preconcentration method based on ionic liquids for the determination of trace cobalt (II in water samples by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Jamali

    2017-02-01

    Full Text Available A simple in situ solvent formation microextraction (ISFME methodology based on the application of ionic liquid (IL as an extractant solvent and sodium hexafluorophosphate (NaPF6 as an ion-pairing agent was proposed for the preconcentration of the trace levels of cobalt ions. In this method cobalt was complexed with 2-(5-bromo-2-pyridylazo-5-diethylaminophenol (5-Br-PADAP and extracted into an ionic liquid phase. After phase separation, the enriched analyte in the final solution is determined by flame atomic absorption spectrometry (FAAS. Some effective factors that influence the microextraction efficiency were investigated and optimized. Under the optimum experimental conditions, the limit of detection and the enrichment factor were 0.97 μg L−1 and 50, respectively. The relative standard deviation (R.S.D. was obtained as 2.4%. The proposed method was assessed through the analysis of certified reference water and recovery experiments.

  13. Translational recognition of the 5'-terminal 7-methylguanosine of globin messenger RNA as a function of ionic strength.

    Science.gov (United States)

    Chu, L Y; Rhoads, R E

    1978-06-13

    The translation of rabbit globin mRNA in cell-free systems derived from either wheat germ or rabbit reticulocyte was studied in the presence of various analogues of the methylated 5' terminus (cap) as a function of ionic strength. Inhibition by these analogues was strongly enhanced by increasing concentrations of KCl, K(OAc), Na(OAc), or NH4(OAc). At appropriate concentrations of K(OAc), both cell-free systems were equally sensitive to inhibition by m7GTP. At 50 mM K(OAc), the reticulocyte system was not sensitive to m7GMP or m7GTP, but at higher concentrations up to 200 mM K(OAc), both nucleotides caused strong inhibition. The compound in m7G5'ppp5'Am was inhibitory at all concentrations of K(OAc) ranging from 50 to 200 mM, although more strongly so at the higher concentrations. Over the same range of nucleotide concentrations, the compounds GMP, GTP, and G5'ppp5'Am were not inhibitors. The mobility on sodium dodecyl sulfate-polyacrylamide electrophoresis of the translation product was that of globin at all K(OAc) concentrations in the presence of m7GTP. Globin mRNA from which the terminal m7GTP group had been removed by chemical treatment (periodate-cyclohexylamine-alkaline phosphatase) or enzymatic treatment (tobacco acid pyrophosphatase-alkaline phosphatase) was translated less efficiently than untreated globin mRNA at higher K(OAc) concentrations, but retained appreciable activity at low K(OAc) concentrations.

  14. Effects of starvation on the transport of Escherichia coli K12 in saturated porous media are dependent on pH and ionic strength

    Science.gov (United States)

    Xu, S.; Walczak, J. J.; Wang, L.; Bardy, S. L.; Li, J.

    2010-12-01

    In this research, we investigate the effects of starvation on the transport of E. coli K12 in saturated porous media. Particularly, we examine the relationship between such effects and the pH and ionic strength of the electrolyte solutions that were used to suspend bacterial cells. E. coli K12 (ATCC 10798) cells were cultured using either Luria-Bertani Miller (LB-Miller) broth (10 g trypton, 5 g yeast extract and 10 g NaCl in 1 L of deionized water) or LB-Luria broth (10 g tryptone, 5 g yeast extract and 0.5 g NaCl in 1 L of deionized water). Both broths had similar pH (~7.1) but differed in ionic strength (LB-Miller: ~170 mM, LB-Luria: ~ 8 mM). The bacterial cells were then harvested and suspended using one of the following electrolyte solutions: phosphate buffered saline (PBS) (pH ~7.2; ionic strength ~170 mM), 168 mM NaCl (pH ~5.7), 5% of PBS (pH ~ 7.2; ionic strength ~ 8 mM) and 8 mM NaCl (pH ~ 5.7). Column transport experiments were performed at 0, 21 and 48 hours following cell harvesting to evaluate the change in cell mobility over time under “starvation” conditions. Our results showed that 1) starvation increased the mobility of E. coli K12 cells; 2) the most significant change in mobility occurred when bacterial cells were suspended in an electrolyte solution that had different pH and ionic strength (i.e., LB-Miller culture suspended in 8 mM NaCl and LB-Luria culture suspended in 168 mM Nacl); and 3) the change in cell mobility primarily occurred within the first 21 hours. The size of the bacterial cells was measured and the surface properties (e.g., zeta potential, hydrophobicity, cell-bound protein, LPS sugar content, outer membrane protein profiles) of the bacterial cells were characterized. We found that the measured cell surface properties could not fully explain the observed changes in cell mobility caused by starvation.

  15. Deposition and release kinetics of nano-TiO2 in saturated porous media: Effects of solution ionic strength and surfactants

    International Nuclear Information System (INIS)

    Godinez, Itzel G.; Darnault, Christophe J.G.; Khodadoust, Amid P.; Bogdan, Dorin

    2013-01-01

    The aggregation, transport and deposition kinetics (i.e. attachment and release) of TiO 2 nanoparticles (nano-TiO 2 ) were investigated as a function of ionic strength and the presence of anionic (sodium dodecylbenzene sulfonate, SDBS) and non-ionic (Triton X-100) surfactants in 100% critical micelle concentration (CMC). The electrolyte concentration of the suspensions dictated the kinetic stability of nano-TiO 2 thus influencing the transport and retention of the nanoaggregates in the saturated porous medium. With increasing ionic strength, the interaction between approaching nano-TiO 2 and nano-TiO 2 already deposited onto collectors surfaces seemed to be more favorable than the interaction between approaching nano-TiO 2 and bare collectors surfaces. The abrupt and gradual reduction in electrolyte concentration during the flushing cycles of the column experiments induced the release of previously deposited nano-TiO 2 suggesting attachment of nano-TiO 2 through secondary energy minimum. Highlights: ► This study focuses on aggregation, transport and deposition kinetics of nano-TiO 2 . ► Ionic strength and surfactants impact nano-TiO 2 transport in saturated porous media. ► Previously deposited nano-TiO 2 serve as preferential sites for subsequent deposition. ► Changes in solution chemistry cause nanodeposits to release a portion of nano-TiO 2 . -- Previously deposited nano-TiO 2 serve as preferential sites for subsequent deposition and changes in solution chemistry cause nanodeposits to release a portion of nano-TiO 2

  16. Use of TOUGHREACT to Simulate Effects of Fluid Chemistry onInjectivity in Fractured Geothermal Reservoirs with High Ionic StrengthFluids

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Zhang, Guoxiang; Pruess, Karsten

    2005-02-09

    Recent studies suggest that mineral dissolution/precipitation and clay swelling effects could have a major impact on the performance of hot dry rock (HDR) and hot fractured rock (HFR) reservoirs. A major concern is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths. A Pitzer ionic interaction model has been introduced into the publicly available TOUGHREACT code for solving non-isothermal multi-phase reactive geochemical transport problems under conditions of high ionic strength, expected in typical HDR and HFR systems. To explore chemically-induced effects of fluid circulation in these systems, we examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance. We performed a number of coupled thermo-hydrologic-chemical simulations in which the fractured medium was represented by a one-dimensional MINC model (multiple interacting continua). Results obtained with the Pitzer activity coefficient model were compared with those using an extended Debye-Hueckel equation. Our simulations show that non-ideal activity effects can be significant even at modest ionic strength, and can have major impacts on permeability evolution in injection-production systems. Alteration of injection water chemistry, for example by dilution with fresh water, can greatly alter precipitation and dissolution effects, and can offer a powerful tool for operating hot dry rock and hot fractured rock reservoirs in a sustainable manner.

  17. Structures of self-assembled amphiphilic peptide-heterodimers: effects of concentration, pH, temperature and ionic strength

    KAUST Repository

    Luo, Zhongli

    2010-01-01

    The amphiphilic double-tail peptides AXG were studied regarding secondary structure and self-assembly in aqueous solution. The two tails A = Ala 6 and G = Gly6 are connected by a central pair X of hydrophilic residues, X being two aspartic acids in ADG, two lysines in AKG and two arginines in ARG. The peptide AD (Ala6Asp) served as a single-tail reference. The secondary structure of the four peptides was characterized by circular dichroism spectroscopy under a wide range of peptide concentrations (0.01-0.8 mM), temperatures (20-98 °C), pHs (4-9.5) and ionic strengths. In salt-free water both ADG and AD form a β-sheet type of structure at high concentration, low pH and low temperature, in a peptide-peptide driven assembly of individual peptides. The transition has a two-state character for ADG but not for AD, which indicates that the added tail in ADG makes the assembly more cooperative. By comparison the secondary structures of AKG and ARG are comparatively stable over the large range of conditions covered. According to dynamic light scattering the two-tail peptides form supra-molecular aggregates in water, but high-resolution AFM-imaging indicate that ordered (self-assembled) structures are only formed when salt (0.1 M NaCl) is added. Since the CD-studies indicate that the NaCl has only a minor effect on the peptide secondary structure we propose that the main role of the added salt is to screen the electrostatic repulsion between the peptide building blocks. According to the AFM images ADG and AKG support a correlation between nanofibers and a β-sheet or unordered secondary structure, whereas ARG forms fibers in spite of lacking β-sheet structure. Since the AKG and ARG double-tail peptides self-assemble into distinct nanostructures while their secondary structures are resistant to environment factors, these new peptides show potential as robust building blocks for nano-materials in various medical and nanobiotechnical applications. © 2010 The Royal Society

  18. Effect of pH and ionic strength on exposure and toxicity of encapsulated lambda-cyhalothrin to Daphnia magna.

    Science.gov (United States)

    Son, Jino; Hooven, Louisa A; Harper, Bryan; Harper, Stacey L

    2015-12-15

    Encapsulation of pesticide active ingredients in polymers has been widely employed to control the release of poorly water-soluble active ingredients. Given the high dispersibility of these encapsulated pesticides in water, they are expected to behave differently compared to their active ingredients; however, our current understanding of the fate and effects of encapsulated pesticides is still limited. In this study, we employed a central composite design (CCD) to investigate how pH and ionic strength (IS) affect the hydrodynamic diameter (HDD) and zeta potential of encapsulated λ-cyhalothrin and how those changes affect the exposure and toxicity to Daphnia magna. R(2) values greater than 0.82 and 0.84 for HDD and zeta potential, respectively, irrespective of incubation time suggest those changes could be predicted as a function of pH and IS. For HDD, the linear factor of pH and quadratic factor of pH×pH were found to be the most significant factors affecting the change of HDD at the beginning of incubation, whereas the effects of IS and IS×IS became significant as incubation time increased. For zeta potential, the linear factor of IS and quadratic factor of IS×IS were found to be the most dominant factors affecting the change of zeta potential of encapsulated λ-cyhalothrin, irrespective of incubation time. The toxicity tests with D. magna under exposure conditions in which HDD or zeta potential of encapsulated λ-cyhalothrin was maximized or minimized in the overlying water also clearly showed the worst-case exposure condition to D. magna was when the encapsulated λ-cyhalothrin is either stable or small in the overlying water. Our results show that water quality could modify the fate and toxicity of encapsulated λ-cyhalothrin in aquatic environments, suggesting understanding their aquatic interactions are critical in environmental risk assessment. Herein, we discuss the implications of our findings for risk assessment. Copyright © 2015 Elsevier B.V. All

  19. Effects of ionic strength on the coordination of Eu(III) and Cm(III) to a Gram-negative bacterium, Paracoccus denitrificans

    International Nuclear Information System (INIS)

    Ozaki, T.; Ohnuki, T.; Kimura, T.; Francis, A.J.

    2006-01-01

    We studied the effect of ionic strength on the interactions of Europium(III) and Curium(III) with a Gram-negative bacterium Paracoccus denitrificans. Bacterial cells grown in 0.5-, 3.5-, and 5.0% NaCl were used in adsorption experiments and laser experiments that were performed at the same ionic strengths as those in the original growth media. The distribution ratio (log K d ) for Eu(III) and Cm(III) was determined at pHs 3-5. To elucidate the coordination environment of Eu(III) adsorbed on P. denitrificans, we estimated the number of water molecules in the inner sphere and strength of the ligand field by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at pHs 4-6. The log K d of Eu(III) and Cm(III) increased with an increase of pH at all ionic strengths because there was less competition for ligands in cells with H + at higher pHs, wherein less H + was present in solution: cation adsorption generally occurs through an exchange with H + on the functional groups of coordination sites. No significant differences were observed in the log K d of Eu(III) and Cm(III) at each pH in 0.5-, 3.5-, and 5.0% NaCl solutions, though competition for ligands with Na + would be expected to increase at higher NaCl concentrations. The log K d of Eu(III) was almost equivalent to that of Cm(III) under all the experimental conditions. TRLFS showed that the coordination environments of Eu(III) did not differ from each other at 0.5-, 3.5-, and 5.0% NaCl at pHs 4-6. TRLFS also showed that the characteristic of the coordination environment of Eu(III) on P. denitrificans was similar to that on a halophile, Nesterenkonia halobia, while it significantly differed from that on a non-halophile, Pseudomonas putida. These findings indicate that the number of coordination sites for Eu(III) on P. denitrificans, whose cell surface may have similar structures to that of halophiles, increased with increasing ionic strength, though their structure remained unchanged. (orig.)

  20. Determination of the second virial coefficient of bovine serum albumin under varying pH and ionic strength by composition-gradient multi-angle static light scattering.

    Science.gov (United States)

    Ma, Yingfang; Acosta, Diana M; Whitney, Jon R; Podgornik, Rudolf; Steinmetz, Nicole F; French, Roger H; Parsegian, V Adrian

    2015-01-01

    Composition-gradient multi-angle static light scattering (CG-MALS) is an emerging technique for the determination of intermolecular interactions via the second virial coefficient B22. With CG-MALS, detailed studies of the second virial coefficient can be carried out more accurately and effectively than with traditional methods. In addition, automated mixing, delivery and measurement enable high speed, continuous, fluctuation-free sample delivery and accurate results. Using CG-MALS we measure the second virial coefficient of bovine serum albumin (BSA) in aqueous solutions at various values of pH and ionic strength of a univalent salt (NaCl). The systematic variation of the second virial coefficient as a function of pH and NaCl strength reveals the net charge change and the isoelectric point of BSA under different solution conditions. The magnitude of the second virial coefficient decreases to 1.13 x 10(-5) ml*mol/g(2) near the isoelectric point of pH 4.6 and 25 mM NaCl. These results illuminate the role of fundamental long-range electrostatic and van der Waals forces in protein-protein interactions, specifically their dependence on pH and ionic strength.

  1. Transport and abatement of fluorescent silica nanoparticle (SiO{sub 2} NP) in granular filtration: effect of porous media and ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao, E-mail: chaozeng@email.arizona.edu; Shadman, Farhang; Sierra-Alvarez, Reyes [University of Arizona, Department of Chemical and Environmental Engineering (United States)

    2017-03-15

    The extensive production and application of engineered silica nanoparticles (SiO{sub 2} NPs) will inevitably lead to their release into the environment. Granular media filtration, a widely used process in water and wastewater treatment plants, has the potential for NP abatement. In this work, laboratory-scale column experiments were performed to study the transport and retention of SiO{sub 2} NPs on three widely used porous materials, i.e., sand, anthracite, and granular activated carbon (GAC). Synthetic fluorescent core-shell SiO{sub 2} NPs (83 nm) were used to facilitate NP detection. Sand showed very low capacity for SiO{sub 2} filtration as this material had a surface with limited surface area and a high concentration of negative charge. Also, we found that the stability and transport of SiO{sub 2} NP were strongly dependent on the ionic strength of the solution. Increasing ionic strength led to NP agglomeration and facilitated SiO{sub 2} NP retention, while low ionic strength resulted in release of captured NPs from the sand bed. Compared to sand, anthracite and GAC showed higher affinity for SiO{sub 2} NP capture. The superior capacity of GAC was primarily due to its porous structure and high surface area. A process model was developed to simulate NP capture in the packed bed columns and determine fundamental filtration parameters. This model provided an excellent fit to the experimental data. Taken together, the results obtained indicate that GAC is an interesting material for SiO{sub 2} NP filtration.

  2. Transport and abatement of fluorescent silica nanoparticle (SiO_2 NP) in granular filtration: effect of porous media and ionic strength

    International Nuclear Information System (INIS)

    Zeng, Chao; Shadman, Farhang; Sierra-Alvarez, Reyes

    2017-01-01

    The extensive production and application of engineered silica nanoparticles (SiO_2 NPs) will inevitably lead to their release into the environment. Granular media filtration, a widely used process in water and wastewater treatment plants, has the potential for NP abatement. In this work, laboratory-scale column experiments were performed to study the transport and retention of SiO_2 NPs on three widely used porous materials, i.e., sand, anthracite, and granular activated carbon (GAC). Synthetic fluorescent core-shell SiO_2 NPs (83 nm) were used to facilitate NP detection. Sand showed very low capacity for SiO_2 filtration as this material had a surface with limited surface area and a high concentration of negative charge. Also, we found that the stability and transport of SiO_2 NP were strongly dependent on the ionic strength of the solution. Increasing ionic strength led to NP agglomeration and facilitated SiO_2 NP retention, while low ionic strength resulted in release of captured NPs from the sand bed. Compared to sand, anthracite and GAC showed higher affinity for SiO_2 NP capture. The superior capacity of GAC was primarily due to its porous structure and high surface area. A process model was developed to simulate NP capture in the packed bed columns and determine fundamental filtration parameters. This model provided an excellent fit to the experimental data. Taken together, the results obtained indicate that GAC is an interesting material for SiO_2 NP filtration.

  3. Sorption of metal ions on clay minerals. 2: Mechanism of Co sorption on hectorite at high and low ionic strength and impact on the sorbent stability

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, M.L.; Charlet, L.; Manceau, A.

    1999-12-15

    The mechanism of Co uptake from aqueous solution onto hectorite (a magnesian smectite) and its impact on the stability of this clay mineral were investigated as a function of Co concentration (TotCo = 20 to 200 {micro}M, 0.3 M NaNO{sub 3}) and ionic strength (0.3 and 0.01 M NaNO{sub 3}, TotCo = 100 {micro}M) by combining kinetics measurements and Co K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The morphology of the sorbent phase was characterized by atomic force microscopy (AFM) and consists of lath-type particles bounded by large basal planes and layer edges. Time-dependent isotherms for Co uptake at high ionic strength indicated the existence of several sorption mechanisms having distinct equilibration times. The dissolution of hectorite was monitored before and after Co addition. Spectral simulations revealed the occurrence of {approximately} 2 Mg and {approximately} 2 Si neighboring cations at interatomic distances characteristic of edge-sharing linkages between Co and Mg octahedra and corner-sharing linkages between Co octahedra and Si tetrahedra, respectively. This local structure is characteristic of inner sphere mononuclear surface complexes at layer edges of hectorite platelets. The occurrence of these complexes even at low ionic strength apparently conflicts with kinetics results, as exchangeable divalent cations are known to form outer sphere surface complexes. To clarify this issue, the amount of Co adsorbed on exchange sites was calculated from the solute Co concentration, assuming that cation exchange was always at equilibrium. These calculations showed that sorbed Co was transferred within 48 h from exchange sites to edge sorption sites.

  4. Transport and abatement of fluorescent silica nanoparticle (SiO2 NP) in granular filtration: effect of porous media and ionic strength

    Science.gov (United States)

    Zeng, Chao; Shadman, Farhang; Sierra-Alvarez, Reyes

    2017-03-01

    The extensive production and application of engineered silica nanoparticles (SiO2 NPs) will inevitably lead to their release into the environment. Granular media filtration, a widely used process in water and wastewater treatment plants, has the potential for NP abatement. In this work, laboratory-scale column experiments were performed to study the transport and retention of SiO2 NPs on three widely used porous materials, i.e., sand, anthracite, and granular activated carbon (GAC). Synthetic fluorescent core-shell SiO2 NPs (83 nm) were used to facilitate NP detection. Sand showed very low capacity for SiO2 filtration as this material had a surface with limited surface area and a high concentration of negative charge. Also, we found that the stability and transport of SiO2 NP were strongly dependent on the ionic strength of the solution. Increasing ionic strength led to NP agglomeration and facilitated SiO2 NP retention, while low ionic strength resulted in release of captured NPs from the sand bed. Compared to sand, anthracite and GAC showed higher affinity for SiO2 NP capture. The superior capacity of GAC was primarily due to its porous structure and high surface area. A process model was developed to simulate NP capture in the packed bed columns and determine fundamental filtration parameters. This model provided an excellent fit to the experimental data. Taken together, the results obtained indicate that GAC is an interesting material for SiO2 NP filtration.

  5. Potentiometric and spectrophotometric characterization of the UO{sub 2}{sup 2+}-citrate complexes in aqueous solution, at different concentrations, ionic strengths and supporting electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Berto, S.; Daniele, P.G.; Prenesti, E. [Torino Univ. (Italy). Dipt. di Chimica Analitica; Crea, F.; De Stefano, C.; Sammartano, S. [Messina Univ. (Italy). Dipt. di Chimica Inorganica, Chimica Analitica e Chimica Fisica

    2012-07-01

    In this paper we report an investigation on the interactions between dioxouranium(VI) and citrate using potentiometry (H{sup +}-glass electrode) and UV-spectrophotometry. Potentiometric measurements were carried out in NaCl and KNO{sub 3} aqueous solutions at t = 25 C in a wide range of experimental conditions (concentrations, ligand/metal molar ratio, pH, titrants). Measurements in NaCl were carried out at different ionic strength values (0.1 {<=} I/mol L{sup -1} {<=} 1.0); different procedures were employed for the acquisition of experimental data and careful analysis of these data performed. In all cases the speciation model that best fits experimental data takes into account the formation of the following species: UO{sub 2}(Cit){sup -}, (UO{sub 2}){sub 2}(Cit){sub 2}{sup 2-}, (UO{sub 2}){sub 2}(Cit){sub 2}(OH){sub 2}{sup 4-}, (UO{sub 2}){sub 2}(Cit){sub 2}(OH){sup 3-}, (UO{sub 2}){sub 2}(Cit)(OH){sub 2}{sup -}, (UO{sub 2}){sub 2}(Cit)(OH){sup 0}, (UO{sub 2}){sub 3}(Cit){sub 2}(OH){sub 5}{sup 5-}. The dependence on ionic strength of formation constants was taken into account by using both a simple Debye-Hueckel type equation and the SIT (specific ion interaction theory) approach. Moreover, a visible absorption spectrum for each complex reaching a significant percentage of formation in solution (KNO{sub 3} medium) has been calculated to characterise the compounds found by pH-metric refinement. Recommended values for the uranyl-citrate species were proposed for each ionic strength values in NaCl aqueous solution. Comparison with literature stability constants is reported too. (orig.)

  6. The effect of Ca2+ ions and ionic strength on Mn(II) oxidation by spores of the marine Bacillus sp. SG-1

    Science.gov (United States)

    Toyoda, Kazuhiro; Tebo, Bradley M.

    2013-01-01

    Manganese(IV) oxides, believed to form primarily through microbial activities, are extremely important mineral phases in marine environments where they scavenge a variety of trace elements and thereby control their distributions. The presence of various ions common in seawater are known to influence Mn oxide mineralogy yet little is known about the effect of these ions on the kinetics of bacterial Mn(II) oxidation and Mn oxide formation. We examined factors affecting bacterial Mn(II) oxidation by spores of the marine Bacillus sp. strain SG-1 in natural and artificial seawater of varying ionic conditions. Ca2+ concentration dramatically affected Mn(II) oxidation, while Mg2+, Sr2+, K+, Na+ and NO3- ions had no effect. The rate of Mn(II) oxidation at 10 mM Ca2+ (seawater composition) was four or five times that without Ca2+. The relationship between Ca2+ content and oxidation rate demonstrates that the equilibrium constant is small (on the order of 0.1) and the binding coefficient is 0.5. The pH optimum for Mn(II) oxidation changed depending on the amount of Ca2+ present, suggesting that Ca2+ exerts a direct effect on the enzyme perhaps as a stabilizing bridge between polypeptide components. We also examined the effect of varying concentrations of NaCl or KNO3 (0-2000 mM) on the kinetics of Mn(II) oxidation in solutions containing 10 mM Ca2+. Mn(II) oxidation was unaffected by changes in ionic strength (I) below 0.2, but it was inhibited by increasing salt concentrations above this value. Our results suggest that the critical coagulation concentration is around 200 mM of salt (I = ca. 0.2), and that the ionic strength of seawater (I > 0.2) accelerates the precipitation of Mn oxides around the spores. Under these conditions, the aggregation of Mn oxides reduces the supply of dissolved O2 and/or Mn2+ and inhibits the Mn(II) → Mn(III) step controlling the enzymatic oxidation of Mn(II). Our results suggest that the hardness and ionic strength of the aquatic environment

  7. Removal of radiocobalt from aqueous solutions by kaolinite affected by solid content, pH, ionic strength, contact time and temperature

    International Nuclear Information System (INIS)

    Kan Li; Zhengjie Liu; Lei Chen; Yunhui Dong; Jun Hu; Chinese Academy of Sciences, Hefei

    2013-01-01

    The kaolinite sample was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction, and was applied as adsorbent for the removal of radiocobalt ions from radioactive wastewater. The results demonstrated that the sorption of Co(II) was strongly dependent on pH and ionic strength at low pH values, and independent of pH and ionic strength at high pH values. The sorption of Co(II) was dominated by outer-sphere surface complexation or ion exchange at low pH values, whereas inner-sphere surface complexation was the main sorption mechanism at high pH values. The sorption isotherms were well described by Langmuir, Freundlich and Dubinin-Radushkevich models. The thermodynamic parameters (i.e., ΔGdeg, ΔSdeg, ΔHdeg) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on kaolinite was an endothermic and spontaneous process. The results of high sorption capacity of kaolinite suggested that the kaolinite sample was a suitable material for the preconcentration of Co(II) from large volumes of aqueous solutions and as backfill materials in nuclear waste management. (author)

  8. Adsorption of Sr(II) and Eu(III) on Na-rectorite. Effect of pH, ionic strength, concentration and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Hu, J.; Wang, X.K. [School of Nuclear Science and Engineering, North China Electric Power Univ., BJ (China); Key Lab. of Novel Thin Film Solar Cells, Inst. of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Chen, C.L.; Sheng, G.D.; Li, J.X. [Key Lab. of Novel Thin Film Solar Cells, Inst. of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Chen, Y.X. [School of Nuclear Science and Engineering, North China Electric Power Univ., BJ (China)

    2010-07-01

    The surface charge characteristics of Na-rectorite (NaAl{sub 4}[Si,Al]{sub 8}O{sub 20}(OH){sub 4}.nH{sub 2}O;) were studied by potentiometric acid-base titrations. Sr(II) and Eu(III) adsorptions on Na-rectorite as a function of pH, ionic strength, and Sr(II)/Eu(III) concentrations were carried out to investigate the surface interactions between Sr(II)/Eu(III) with Na-rectorite. The results indicated that the adsorptions of Sr(II) and Eu(III) on Na-rectorite increased with increasing pH and decreased with increasing ionic strength and initial Sr(II)/Eu(III) concentrations, and that the affinity of Na-rectorite for Eu(III) was much higher than for Sr(II). The experimental data of Sr(II)/Eu(III) adsorption were simulated by the diffuse-layer model (DLM) well with the aid of FITEQL 3.2. Simultaneous adsorptions of Sr(II) and Eu(III) on Na-rectorite were also modeled using the DLM. The adsorption mechanisms of Sr(II) and Eu(III) on Na-rectorite may be dominated by ion exchange interaction at low pH or moderate pH, and by surface complexation interaction at high pH. (orig.)

  9. Sorption properties of Th(IV) on the raw diatomite-Effects of contact time, pH, ionic strength and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sheng Guodong; Hu Jun [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); Wang Xiangke [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China)], E-mail: xkwang@ipp.ac.cn

    2008-10-15

    Diatomite has a number of unique physicochemical properties and has diversified industrial uses. Natural diatomite has been tested as a potential sorbent for the removal of Th(IV) from aqueous solutions. The results indicate that sorption of Th(IV) is strongly dependent on ionic strength at pH<3, and is independent of ionic strength at pH>3. Outer-sphere complexation or ion exchange may be the main sorption mechanism of Th(IV) to diatomite at low pH values, whereas the sorption of Th(IV) at pH>3 is mainly dominated by inner-sphere complexation or precipitation. The competition for Th(IV) between aqueous or surface adsorbed anions (e.g., herein ClO{sub 4}{sup -}, NO{sub 3}{sup -} and Cl{sup -}) and surface functional groups of diatomite is important for Th(IV) sorption. The thermodynamic data ({delta}H{sup 0}, {delta}S{sup 0}, {delta}G{sup 0}) are calculated from the temperature-dependent sorption isotherms. The results suggest that sorption process of Th(IV) on diatomite is spontaneous and endothermic.

  10. Increased dissolved organic carbon (DOC) in Central European streams is driven by reductions in ionic strength rather than climate change or decreasing acidity.

    Science.gov (United States)

    Hruska, Jakub; Krám, Pavel; McDowell, William H; Oulehle, Filip

    2009-06-15

    Temporal trends in DOC concentration and flux were investigated at two geochemically distinct forested catchments in western Czech Republic. Mean discharge-weighted DOC concentrations averaged 18.8 mg L(-1) at the acidic Lysina catchment, and 20.2 mg L(-1) at base-rich and well-buffered Pluhuv Bor. Between 1993 and 2007 DOC in streamwater increased significantly in both catchments: the mean annual increase was 0.42 mg L(-1) yr(-1) (p DOC were correlated with only modest increases in stream pH in both catchments, but large declines in ionic strength (IS), that resulted from declining atmospheric deposition. Neither catchment has undergone changes in soil-water pH, yet DOC concentrations tripled in the soil-water of both catchments. We conclude that changes in ionic strength of soil-water and streamwater, rather than acidity, are the primary drivers of changes in streamwater DOC in this region. Temperature, precipitation and discharge show no statistically significant trends during the study period, suggesting that climate change has played no role in the changes in DOC that we have observed.

  11. Biosorption removal of benzene and toluene by three dried macroalgae at different ionic strength and temperatures: Algae biochemical composition and kinetics.

    Science.gov (United States)

    Flores-Chaparro, Carlos E; Chazaro Ruiz, Luis Felipe; Alfaro de la Torre, Ma Catalina; Huerta-Diaz, Miguel Angel; Rangel-Mendez, Jose Rene

    2017-05-15

    Release of low-molecular aromatic hydrocarbons (HC) into natural waters brings severe consequences to our environment. Unfortunately very limited information is available regarding the treatment of these pollutants. This work evaluated the use of brown, green and red macroalgae biomass as biosorbents of benzene and toluene, two of the most soluble HC. Raw seaweed biomasses were completely characterized, then evaluated under different temperatures and ionic strengths to assess their potential as biosorbents and to elucidate the biosorption mechanisms involved. Brown macroalgae registered the highest removal capacities for benzene and toluene (112 and 28 mg·g -1 , respectively), and these were not affected at ionic strength < 0.6 M. Langmuir and Sips isotherm equations well described biosorption data, and the pseudo-second order model provided the best fit to the kinetics rate. Hydrocarbons are adsorbed onto the diverse chemical components of the cell wall by London forces and hydrophobic interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Batch and flow-through continuous stirred reactor experiments of Sr2+-adsorption onto smectite: influence of pH, concentration and ionic strength

    International Nuclear Information System (INIS)

    Guimaraes, V.; Azenha, M.; Silva, A.F.; Bobos, I.

    2012-01-01

    Document available in extended abstract form only. Strontium-90 (t 1/2 = 29.1 years) resulting from the nuclear fission process is one of the main constituents connected with nuclear waste fuel. Concerning the physical properties and sorption behaviour one of the suitable buffer materials used as a backfill in the geological disposal systems for high-level radioactive wastes is smectite. The 2 μm clay fractions of di-octahedral smectite were used for adsorption experiments in batch and flow-through experiments. Flow-through experiments were carried out at different pH (4 and 8) and concentrations (8.00x10 -2 mmolSr 2+ /L, 2.0x10 -1 mmolSr 2+ /L, 3.3x10 -1 mmolSr 2+ /L and 4.1 x10 -1 mmol Sr 2+ /L). Batch experiments were carried out at different ionic strength ([KNO 3 ]=10 -2 M and [KNO 3 ]=10 -3 M), pH (4 and 8), whereas the concentration ranged between 0.19 mmolSr 2+ /L and 9.60 mmolSr 2+ /L. The adsorption strontium rate in flow-through experiments was found higher at pH 4 than at pH 8, where less of 20% amount of strontium was adsorbed on clay surface after 34 hours. This is explained by the surface charge of smectite layers with a permanent negative charge on the basal planes due essentially to isomorphic substitution. Also additional polar sites are conditionally charged by direct protonation of outer edge surfaces. Therefore, more negative sites become available for the strontium ions sorption, as the pH increasing. After adsorption, the clays were submitted to a desorption process. The rate of desorption at pH 4 is initially too fast due to the elevated amount of strontium released by smectite. After 255 min, the strontium amount desorbed is very low and the rate of desorption approached to zero. By contrast at pH 8 the rate of desorption is practically constant, and after 255 min there is a significant amount of strontium released by clay. Due to these different behaviors in different pH conditions, after 10 hours of desorption, the amount of strontium

  13. A new approach combining different MRI methods to provide detailed view on swelling dynamics of xanthan tablets influencing drug release at different pH and ionic strength.

    Science.gov (United States)

    Mikac, Ursa; Sepe, Ana; Kristl, Julijana; Baumgartner, Sasa

    2010-08-03

    The key element in drug release from hydrophilic matrix tablets is the gel layer that regulates the penetration of water and controls drug dissolution and diffusion. We have selected magnetic resonance imaging (MRI) as the method of choice for visualizing the dynamic processes occurring during the swelling of xanthan tablets in a variety of media. The aims were (i) to develop a new method using MRI for accurate determination of penetration, swelling and erosion fronts, (ii) to investigate the effects of pH and ionic strength on swelling, and (iii) to study the influence of structural changes in xanthan gel on drug release. Two dimensional (2D) MRI and one dimensional single point imaging (SPI) of swollen xanthan tablets were recorded, together with T(2) mapping. The border between dry and hydrated glassy xanthan-the penetration front-was determined from 1D SPI signal intensity profiles. The erosion front was obtained from signal intensity profiles of 2D MR images. The swelling front, where xanthan is transformed from a glassy to a rubbery state (gel formation), was determined from T(2) profiles. Further, the new combination of MRI methods for swelling front determination enables to explain the appearance of the unusual "bright front" observed on 2D MR images in tablets swollen in HCl pH 1.2 media, which represents the position of swelling front. All six media studied, differing in pH and ionic strength, penetrate through the whole tablet in 4h+/-0.3h, but formation of the gel layer is significantly delayed. Unexpectedly, the position of the swelling front was the same, independently of the different xanthan gel structures formed under different conditions of pH and ionic strength. The position of the erosion front, on the other hand, is strongly dependent on pH and ionic strength, as reflected in different thicknesses of the gel layers. The latter are seen to be the consequence of the different hydrodynamic radii of the xanthan molecules, which affect the drug

  14. Solvent extraction of zirconium

    International Nuclear Information System (INIS)

    Kim, S.S.; Yoon, J.H.

    1981-01-01

    The extraction of zirconium(VI) from an aqueous solution of constant ionic strength with versatic acid-10 dissolved in benzen was studied as a function of pH and the concentration of zirconium(VI) and organic acid. The effects of sulphate and chlorine ions on the extraction of the zirconium(VI) were briefly examined. It was revealed that (ZrOR 2 .2RH) is the predominant species of extracted zirconium(VI) in the versatic acid-10. The chemical equation and the apparent equilibrium constants thereof have been determined as follows. (ZrOsup(2+))aq+ 2(R 2 H 2 )sub(org) = (ZrOR 2 .2RH)sub(org)+2(H + )aq Ksub(Zr) = (ZrOR 2 .2RH)sub(org)(H + ) 2 /(ZrOsup(2+))sub(aq)(R 2 H 2 )sup(2)sub(org) = 3.3 x 10 -7 . The synergistic effects of TBP and D2EHPA were also studied. In the mixed solvent with 0.1M TBP, the synergistic effect was observed, while the mixed solvent with D2EHPA showed the antisynergistic effect. (Author)

  15. Proposed kinetic mechanism of biodiesel production through lipase catalysed interesterification with a methyl acetate acyl acceptor and ionic liquid BMIM PF6 co-solvent

    Energy Technology Data Exchange (ETDEWEB)

    Ruzich, Nicholas Ivan; Bassi, A.S.

    2011-02-15

    As the depletion of fossil resources continues, the demand for environmentally friendly sources of energy as biodiesel is increasing. Biodiesel is the resulting fatty acid methyl ester (FAME) from an esterification reaction. To enhance this reaction lipase catalysts and ionic liquids can also used. The aim of this study was to develop a kinetic model of this reaction and to determine the effect of ionic liquids. The esterification reaction was conducted in a jacketed reactor under constant temperature in presence of ionic liquid and with the use of lipase to start the reaction; samples were analyzed with a high-performance liquid chromatography. A kinetic model was developed and results indicated that ionic liquids tend to limit mass transfer and thus reduce initial reaction rates; the authors proposed to increase the flow rate of the reaction mixture to overcome this issue. This study successfully investigated the reaction of lipase-catalyzed biodiesel production and developed its kinetic model.

  16. Optimizing gradient conditions in online comprehensive two-dimensional reversed-phase liquid chromatography by use of the linear solvent strength model

    DEFF Research Database (Denmark)

    Græsbøll, Rune; Janssen, Hans-Gerd; Christensen, Jan H.

    2017-01-01

    The linear solvent strength model was used to predict coverage in online comprehensive two-dimensional reversed-phase liquid chromatography. The prediction model uses a parallelogram to describe the separation space covered with peaks in a system with limited orthogonality. The corners of the par......The linear solvent strength model was used to predict coverage in online comprehensive two-dimensional reversed-phase liquid chromatography. The prediction model uses a parallelogram to describe the separation space covered with peaks in a system with limited orthogonality. The corners...... of the parallelogram are assumed to behave like chromatographic peaks and the position of these pseudo-compounds was predicted. A mix of 25 polycyclic aromatic compounds were used as a test. The precision of the prediction, span 0-25, was tested by varying input parameters, and was found to be acceptable with root...... factors were low, or when gradient conditions affected parameters not included in the model, e.g. second dimension gradient time affects the second dimension equilibration time. The concept shows promise as a tool for gradient optimization in online comprehensive two-dimensional liquid chromatography...

  17. Counterion-induced swelling of ionic microgels

    Science.gov (United States)

    Denton, Alan R.; Tang, Qiyun

    2016-10-01

    Ionic microgel particles, when dispersed in a solvent, swell to equilibrium sizes that are governed by a balance between electrostatic and elastic forces. Tuning of particle size by varying external stimuli, such as pH, salt concentration, and temperature, has relevance for drug delivery, microfluidics, and filtration. To model swelling of ionic microgels, we derive a statistical mechanical theorem, which proves exact within the cell model, for the electrostatic contribution to the osmotic pressure inside a permeable colloidal macroion. Applying the theorem, we demonstrate how the distribution of counterions within an ionic microgel determines the internal osmotic pressure. By combining the electrostatic pressure, which we compute via both Poisson-Boltzmann theory and molecular dynamics simulation, with the elastic pressure, modeled via the Flory-Rehner theory of swollen polymer networks, we show how deswelling of ionic microgels with increasing concentration of particles can result from a redistribution of counterions that reduces electrostatic pressure. A linearized approximation for the electrostatic pressure, which proves remarkably accurate, provides physical insight and greatly eases numerical calculations for practical applications. Comparing with experiments, we explain why soft particles in deionized suspensions deswell upon increasing concentration and why this effect may be suppressed at higher ionic strength. The failure of the uniform ideal-gas approximation to adequately account for counterion-induced deswelling below close packing of microgels is attributed to neglect of spatial variation of the counterion density profile and the electrostatic pressure of incompletely neutralized macroions.

  18. The solvent at antigen-binding site regulated C3d-CR2 interactions through the C-terminal tail of C3d at different ion strengths: insights from molecular dynamics simulation.

    Science.gov (United States)

    Zhang, Yan; Guo, Jingjing; Li, Lanlan; Liu, Xuewei; Yao, Xiaojun; Liu, Huanxiang

    2016-10-01

    The interactions of complement receptor 2 (CR2) and the degradation fragment C3d of complement component C3 play important links between the innate and adaptive immune systems. Due to the importance of C3d-CR2 interaction in the design of vaccines and inhibitors, a number of studies have been performed to investigate C3d-CR2 interaction. Many studies have indicated C3d-CR2 interactions are ionic strength-dependent. To investigate the molecular mechanism of C3d-CR2 interaction and the origin of effects of ionic strength, molecular dynamics simulations for C3d-CR2 complex together with the energetic and structural analysis were performed. Our results revealed the increased interactions between charged protein and ions weaken C3d-CR2 association, as ionic strengths increase. Moreover, ion strengths have similar effects on antigen-binding site and CR2 binding site. Meanwhile, Ala17 and Gln20 will transform between the activated and non-activated states mediated by His133 and Glu135 at different ion strengths. Our results reveal the origins of the effects of ionic strengths on C3d-CR2 interactions are due to the changes of water, ion occupancies and distributions. This study uncovers the origin of the effect of ionic strength on C3d-CR2 interaction and deepens the understanding of the molecular mechanism of their interaction, which is valuable for the design of vaccines and small molecule inhibitors. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Detailed landfill leachate plume mapping using 2D and 3D Electrical Resistivity Tomography - with correlation to ionic strength measured in screens

    DEFF Research Database (Denmark)

    Maurya, P.K.; Rønde, Vinni; Fiandaca, G.

    2017-01-01

    Leaching of organic and inorganic contamination from landfills is a serious environmental problem as surface water and aquifers are affected. In order to assess these risks and investigate the migration of leachate from the landfill, 2D and large scale 3D electrical resistivity tomography were used...... at a heavily contaminated landfill in Grindsted, Denmark. The inverted 2D profiles describe both the variations along the groundwater flow as well as the plume extension across the flow directions. The 3D inversion model shows the variability in the low resistivity anomaly pattern corresponding to differences...... in the ionic strength of the landfill leachate. Chemical data from boreholes agree well with the observations indicating a leachate plume which gradually sinks and increases in size while migrating from the landfill in the groundwater flow direction. Overall results show that the resistivity method has been...

  20. Diffusion of organic colloids in compacted bentonite. The influence of ionic strength on molecular size and transport capacity of the colloids

    International Nuclear Information System (INIS)

    Wold, S.; Eriksen, Trygve E.

    2000-09-01

    Diffusion of radionuclides in compacted bentonite can be affected by inorganic and organic colloids if the radionuclides form complexes with the colloids. Formation and mobility of the colloid-radionuclide complexes will be governed by the properties of the colloids as well as the competition between complexation and sorption of the radionuclides on bentonite. This report presents the results of experiments with organic colloids humic acid (HA) and lignosulfonate (LS). The aim of the experiments has been to describe the HA and LS properties: size distribution, acidity, sorption on bentonite, diffusivity in compacted bentonite, complexation with strontium, and diffusion of strontium in bentonite in the presence of HA. This study indicates that the diffusion of cationic radionuclides like Sr 2+ is not affected by the presence of HA in high ionic strength solution. In 0.1 M NaClO 4 solution, HA is most probably not available for complexation due to coiling and shielding of the negative sites

  1. Electroformation of Giant Unilamellar Vesicles from Native Membranes and Organic Lipid Mixtures for the Study of Lipid Domains under Physiological Ionic-Strength Conditions

    DEFF Research Database (Denmark)

    Montes, Ruth; Ahyayauch, Hasna; Ibarguren, Maitane

    2010-01-01

    Giant unilamellar vesicles (GUVs) constitute a cell-sized model membrane system that allows direct visualization of particular membrane-related phenomena, such as domain formation, at the level of single vesicles using fluorescence microscopy-related techniques. Currently available protocols...... for the preparation of GUVs work only at very low salt concentrations, thus precluding experimentation under physiological conditions. In addition, the GUVs thus obtained lack membrane compositional asymmetry. Here we show how to prepare GUVs using a new protocol based on the electroformation method either from...... native membranes or organic lipid mixtures at physiological ionic strength. Additionally, we describe methods to test whether membrane proteins and glycosphingolipids preserve their natural orientation after electroformation of GUVs composed of native membranes...

  2. The solubility of UO22+ in dilute sodium chloride solutions and in high-ionic strength sodium sulfate and chlorine brines

    International Nuclear Information System (INIS)

    Marquez, L.N.; Kadkhodayan, B.; Wruck, D.A.

    1995-01-01

    Uranium is a major component of high-level nuclear waste. In an oxidizing environment, UO 2 2+ would be expected to be the dominant dissolved species in solution. In addition to dilute solutions, because high-level nuclear waste may be stored in repositories containing salt, it is important to characterize the aqueous chemistry of UO 2 2+ and the solubility-controlling U(VI) solids in high-ionic strength brines as a function of pH. We have studied the solubility of UO 2 2+ by precipitation of solid phase in 0.001 molal NaCl, 5.2 molal NaCl, and saturated Na 2 SO 4 at pH values ranging from 5 to 12. The solution concentrations were measured by alpha particle liquid scintillation counting. The precipitated solids were characterized by powder x-ray diffraction, electron microscopy, infrared spectroscopy, and x-ray photoelectron spectroscopy

  3. Aggregation and ecotoxicity of CeO{sub 2} nanoparticles in synthetic and natural waters with variable pH, organic matter concentration and ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Van Hoecke, Karen, E-mail: karen.vanhoecke@ugent.be [Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Jozef Plateaustraat 22, B-9000 Gent (Belgium); De Schamphelaere, Karel A.C. [Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Jozef Plateaustraat 22, B-9000 Gent (Belgium); Van der Meeren, Paul [Particle and Interfacial Technology Group, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Gent (Belgium); Smagghe, Guy [Laboratory of Agrozoology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Gent (Belgium); Janssen, Colin R. [Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Jozef Plateaustraat 22, B-9000 Gent (Belgium)

    2011-04-15

    The influence of pH (6.0-9.0), natural organic matter (NOM) (0-10 mg C/L) and ionic strength (IS) (1.7-40 mM) on 14 nm CeO{sub 2} NP aggregation and ecotoxicity towards the alga Pseudokirchneriella subcapitata was assessed following a central composite design. Mean NP aggregate sizes ranged between 200 and 10000 nm. Increasing pH and IS enhanced aggregation, while increasing NOM decreased mean aggregate sizes. The 48 h-E{sub r}C20s ranged between 4.7 and 395.8 mg CeO{sub 2}/L. An equation for predicting the 48 h-E{sub r}C20 (48 h-E{sub r}C20 = -1626.4 x (pH) + 109.45 x (pH){sup 2} + 116.49 x ([NOM]) - 14.317 x (pH) x ([NOM]) + 6007.2) was developed. In a validation study with natural waters the predicted 48 h-E{sub r}C20 was a factor 1.08-2.57 lower compared to the experimental values. - Research highlights: > Algal ecotoxicity of CeO{sub 2} nanoparticles (NPs) depends on pH and NOM concentration. > Increasing pH and ionic strength enhanced CeO{sub 2} nanoparticle aggregation. > Increasing NOM concentration decreased mean CeO{sub 2} aggregate size. > An empirical model to predict 48 h-E{sub r}C{sub 20} values of CeO{sub 2} NPs was developed. > The model was validated using natural surface waters with various characteristics. - CeO{sub 2} nanoparticle aggregation and toxicity depend on abiotic factors such as pH, NOM and IS. Effect concentrations can be predicted as a function of pH and NOM.

  4. Zn2+ and Sr2+ Adsorption at the TiO2 (110)-Electrolyte Interface: Influence of Ionic Strength, Coverage, and Anions

    International Nuclear Information System (INIS)

    Zhang, Z.; Fenter, P.; Cheng, L.; Sturchio, N.; Bedzyk, M.; Machesky, M.; Anovitz, L.; Wesolowski, D.

    2006-01-01

    The X-ray standing wave technique was used to probe the sensitivity of Zn 2+ and Sr 2+ ion adsorption to changes in both the adsorbed ion coverage and the background electrolyte species and concentrations at the rutile (α-TiO 2 ) (110)-aqueous interface. Measurements were made with various background electrolytes (NaCl, NaTr, RbCl, NaBr) at concentrations as high as 1 m. The results demonstrate that Zn 2+ and Sr 2+ reside primarily in the condensed layer and that the ion heights above the Ti-O surface plane are insensitive to ionic strength and the choice of background electrolyte (with - , coupled with the insensitivity of Zn 2+ and Sr 2+ cation heights to changes in the background electrolyte, implies that anions do not play a significant role in the adsorption of these divalent metal ions to the rutile (110) surface. Absolute ion coverage measurements for Zn 2+ and Sr 2+ show a maximum Stern-layer coverage of ∼0.5 monolayer, with no significant variation in height as a function of Stern-layer coverage. These observations are discussed in the context of Gouy-Chapman-Stern models of the electrical double layer developed from macroscopic sorption and pH-titration studies of rutile powder suspensions. Direct comparison between these experimental observations and the MUltiSIte Complexation (MUSIC) model predictions of cation surface coverage as a function of ionic strength revealed good agreement between measured and predicted surface coverages with no adjustable parameters

  5. Sorption of Ni(II) on GMZ bentonite: effects of pH, ionic strength, foreign ions, humic acid and temperature.

    Science.gov (United States)

    Yang, Shitong; Li, Jiaxing; Lu, Yi; Chen, Yixue; Wang, Xiangke

    2009-09-01

    Bentonite has been widely studied in nuclear waste management because of its special physicochemical properties. In this work, the sorption of Ni(II) from aqueous solution onto GMZ bentonite as a function of contact time, pH, ionic strength, foreign ions, humic acid (HA) and temperature was investigated under ambient conditions. The results indicated that the pseudo-second-order rate equation simulated the kinetic sorption process well. The sorption of Ni(II) on GMZ bentonite was strongly dependent on pH and on ionic strength. At low pH, the sorption of Ni(II) was dominated by outer-sphere surface complexation and ion exchange with Na(+)/H(+) on GMZ bentonite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. A positive effect of HA on Ni(II) sorption was found at pH8. The Langmuir, Freundlich, and D-R models were used to simulate the sorption isotherms of Ni(II) at three different temperatures: 303.15, 318.15 and 333.15K. The thermodynamic parameters (DeltaH(0), DeltaS(0) and DeltaG(0)) of Ni(II) sorption on GMZ bentonite at the three different temperatures were calculated from the temperature-dependent sorption isotherms. The results indicated that the sorption process of Ni(II) on GMZ bentonite was endothermic and spontaneous. Experimental results indicate that GMZ bentonite is a suitable sorbent for pre-concentration and solidification of Ni(II) from large volume solutions.

  6. Sorption of Ni(II) on GMZ bentonite: Effects of pH, ionic strength, foreign ions, humic acid and temperature

    International Nuclear Information System (INIS)

    Yang Shitong; Li Jiaxing; Lu Yi; Chen Yixue; Wang Xiangke

    2009-01-01

    Bentonite has been widely studied in nuclear waste management because of its special physicochemical properties. In this work, the sorption of Ni(II) from aqueous solution onto GMZ bentonite as a function of contact time, pH, ionic strength, foreign ions, humic acid (HA) and temperature was investigated under ambient conditions. The results indicated that the pseudo-second-order rate equation simulated the kinetic sorption process well. The sorption of Ni(II) on GMZ bentonite was strongly dependent on pH and on ionic strength. At low pH, the sorption of Ni(II) was dominated by outer-sphere surface complexation and ion exchange with Na + /H + on GMZ bentonite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. A positive effect of HA on Ni(II) sorption was found at pH 8. The Langmuir, Freundlich, and D-R models were used to simulate the sorption isotherms of Ni(II) at three different temperatures: 303.15, 318.15 and 333.15 K. The thermodynamic parameters (ΔH 0 , ΔS 0 and ΔG 0 ) of Ni(II) sorption on GMZ bentonite at the three different temperatures were calculated from the temperature-dependent sorption isotherms. The results indicated that the sorption process of Ni(II) on GMZ bentonite was endothermic and spontaneous. Experimental results indicate that GMZ bentonite is a suitable sorbent for pre-concentration and solidification of Ni(II) from large volume solutions.

  7. Ionic liquids used in extraction and separation of metal ions

    International Nuclear Information System (INIS)

    Shen Xinghai; Xu Chao; Liu Xinqi; Chu Taiwei

    2006-01-01

    Ionic liquids as green solvents now have become a research hotspot in the field of separation of metal ions by solvent extraction. Experimental results of extraction of various metal ions with ionic liquids as solvents, including that of alkali metals, alkaline earths, transition metals rare earths and actinides are introduced. The extraction of uranium, plutonium and fission products that are involved in spent nuclear fuel reprocessing is also reviewed. The possible extraction mechanisms are discussed. Finally, the prospect of replacement of volatile and/or toxic organic solvents with environmentally benign ionic liquids for solvent extraction and the potency of applications of ionic liquids in solvent extraction are also commented. (authors)

  8. Formation of CaSO4(aq) and CaSeO4(aq) studied as a function of ionic strength and temperature by CE

    International Nuclear Information System (INIS)

    Philippini, V.; Aupiais, J.; Moulin, Ch.; Vercouter, Th.

    2009-01-01

    Ca 2+ complexation by both sulfate and selenate ligands was studied by CE. The species were observed to give a unique retention peak as a result of a fast equilibrium between the free ions and the complexes. The change in the corresponding retention time was interpreted with respect to the equilibrium constant of the complexation reaction. The results confirmed the formation of CaSO 4 (aq) and CaSeO 4 (aq) under our experimental conditions. The formation data were derived from the series of measurements carried out at about 15, 25, 35, 45 and 55 degrees C in 0.1 mol/L NaNO 3 ionic strength solutions, and in 0.5 and 1.0 mol/L NaNO 3 ionic strength solutions at 25 degrees C. Using a constant enthalpy of reaction enabled to fit all the experimental data in a 0.1 mol/L medium, leading to the thermodynamic parameters: Δ r G 0.1M (25 degrees C) = -(7.59±0.23) kJ/mol, Δ r H 0.1M = 5.57±0.80 kJ/mol, and Δ r S 0.1M (25 degrees C) = 44.0±3.0 J mol -1 K -1 for CaSO 4 (aq) and Δ r G 0.1M )(25 degrees C) = - (6.66±0.23) kJ/mol, Δ r H 0.1M = 6.45±0.73 kJ/mol, and Δ r S 0.1M (25 degrees C) = 44.0±3.0 J mol -1 K -1 for CaSeO 4 (aq). Both formation reactions were found to be endothermic and entropy driven. CaSO 4 (aq) appears to be more stable than CaSe O 4(aq) by 0.93 kJ/mol under these experimental conditions, which correlates with the difference of acidity of the anions as expected for interactions between hard acids and hard bases according to the hard and soft acids and bases theory. The effect of the ionic medium on the formation constants was successfully treated using the Specific ion Interaction Theory, leading to significantly different binary coefficients ε Na + ,SO 4 2- (0.15±0.06) mol/kg -1 and ε Na + ,SeO 4 2- -(0.26±0.10)mol/kg -1 . (authors)

  9. Ionic Liquids as Extraction Media for Metal Ions

    Science.gov (United States)

    Hirayama, Naoki

    In solvent extraction separation of metal ions, recently, many researchers have investigated possible use of hydrophobic ionic liquids as extraction media instead of organic solvents. Ionic liquids are salts of liquid state around room temperature and can act not only as solvents but also as ion-exchangers. Therefore, the extraction mechanism of metal ions into ionic liquids is complicated. This review presents current overview and perspective on evaluation of nature of hydrophobic ionic liquids as extraction media for metal ions.

  10. Origin of the correlation between the standard Gibbs energies of ion transfer from water to a hydrophobic ionic liquid and to a molecular solvent

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Záliš, Stanislav; Samec, Zdeněk; Bovtun, Viktor; Kempa, Martin

    2013-01-01

    Roč. 87, JAN 2013 (2013), s. 591-598 ISSN 0013-4686 R&D Projects: GA ČR GAP206/11/0707 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : ionic liquid s * cyclic voltammetry * standard Gibbs energy of ion transfer Subject RIV: CG - Electrochemistry Impact factor: 4.086, year: 2013

  11. A comparative study on the thermophysical properties for two bis[(trifluoromethyl)sulfonyl]imide-based ionic liquids containing the trimethyl-sulfonium or the trimethyl-ammonium cation in molecular solvents.

    Science.gov (United States)

    Couadou, Erwan; Jacquemin, Johan; Galiano, Hervé; Hardacre, Christopher; Anouti, Mérièm

    2013-02-07

    Herein, we present a comparative study of the thermophysical properties of two homologous ionic liquids, namely, trimethyl-sulfonium bis[(trifluoromethyl)sulfonyl]imide, [S(111)][TFSI], and trimethyl-ammonium bis[(trifluoromethyl)sulfonyl]imide, [HN(111)][TFSI], and their mixtures with propylene carbonate, acetonitrile, or gamma butyrolactone as a function of temperature and composition. The influence of solvent addition on the viscosity, conductivity, and thermal properties of IL solutions was studied as a function of the solvent mole fraction from the maximum solubility of IL, x(s), in each solvent to the pure solvent. In this case, x(s) is the composition corresponding to the maximum salt solubility in each liquid solvent at a given temperature from 258.15 to 353.15 K. The effect of temperature on the transport properties of each binary mixture was then investigated by fitting the experimental data using Arrhenius' law and the Vogel-Tamman-Fulcher (VTF) equation. The experimental data shows that the residual conductivity at low temperature, e.g., 263.15 K, of each binary mixture is exceptionally high. For example, conductivity values up to 35 and 42 mS·cm(-1) were observed in the case of the [S(111)][TFSI] + ACN and [HN(111)][TFSI] + ACN binary mixtures, respectively. Subsequently, a theoretical approach based on the conductivity and on the viscosity of electrolytes was formulated by treating the migration of ions as a dynamical process governed by ion-ion and solvent-ion interactions. Within this model, viscosity data sets were first analyzed using the Jones-Dole equation. Using this theoretical approach, excellent agreement was obtained between the experimental and calculated conductivities for the binary mixtures investigated at 298.15 K as a function of the composition up to the maximum solubility of the IL. Finally, the thermal characterization of the IL solutions, using DSC measurements, showed a number of features corresponding to different solid

  12. Ionic liquids as electrolytes

    International Nuclear Information System (INIS)

    Galinski, Maciej; Lewandowski, Andrzej; Stepniak, Izabela

    2006-01-01

    Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their physicochemical properties are the same as high temperature ionic liquids, but the practical aspects of their maintenance or handling are different enough to merit a distinction. The class of ionic liquids, based on tetraalkylammonium cation and chloroaluminate anion, has been extensively studied since late 1970s of the XX century, following the works of Osteryoung. Systematic research on the application of chloroaluminate ionic liquids as solvents was performed in 1980s. However, ionic liquids based on aluminium halides are moisture sensitive. During the last decade an increasing number of new ionic liquids have been prepared and used as solvents. The general aim of this paper was to review the physical and chemical properties of RTILs from the point of view of their possible application as electrolytes in electrochemical processes and devices. The following points are discussed: melting and freezing, conductivity, viscosity, temperature dependence of conductivity, transport and transference numbers, electrochemical stability, possible application in aluminium electroplating, lithium batteries and in electrochemical capacitors

  13. Supercritical fluids in ionic liquids

    NARCIS (Netherlands)

    Kroon, M.C.; Peters, C.J.; Plechkova, N.V.; Seddon, K.R.

    2014-01-01

    Ionic liquids and supercritical fluids are both alternative environmentally benign solvents, but their properties are very different. Ionic liquids are non-volatile but often considered highly polar compounds, whereas supercritical fluids are non-polar but highly volatile compounds. The combination

  14. The effect of the production method on the mechanical strength of an alumina porous hollow fiber

    NARCIS (Netherlands)

    de Wit, Patrick; van Daalen, Frederique S.; Benes, Nieck E.

    2017-01-01

    The mechanical strength of inorganic porous hollow fibers is an important property and is strongly affected by the production method. Three production methods for fibers are compared: non-solvent induced phase separation (NIPS), bio-ionic gelation with an internal multivalent ion source (BIG-I), and

  15. The dual exo/endo-type mode and the effect of ionic strength on the mode of catalysis of chitinase 60 (CHI60) from Serratia sp. TU09 and its mutants.

    Science.gov (United States)

    Kuttiyawong, K; Nakapong, S; Pichyangkura, R

    2008-11-03

    Mutations of the tryptophan residues in the tryptophan-track of the N-terminal domain (W33F/Y and W69F/Y) and in the catalytic domain (W245F/Y) of Serratia sp. TU09 Chitinase 60 (CHI60) were constructed, as single and double point substitutions to either phenylalanine or tyrosine. The enzyme-substrate interaction and mode of catalysis, exo/endo-type, of wild type CHI60 and mutant enzymes on soluble (partially N-acetylated chitin), amorphous (colloidal chitin), and crystalline (β-chitin) substrates were studied. All CHI60 mutants exhibited a reduced substrate binding activity on colloidal chitin. CHI60 possesses a dual mode of catalysis with both exo- and endo-type activities allowing the enzyme to work efficiently on various substrate types. CHI60 preferentially uses the endo-type mode on soluble and amorphous substrates and the exo-type mode on crystalline substrate. However, the prevalent mode of hydrolysis mediated by CHI60 is regulated by ionic strength. Slightly elevated ionic strength, 0.1-0.2M NaCl, which promotes enzyme-substrate interactions, enhances CHI60 hydrolytic activity on amorphous substrate and, interestingly, on partially N-acetylated chitin. High ionic strength, 0.5-2.0M NaCl, prevents the enzyme from dissociating from amorphous substrate, occupying the enzyme in an enzyme-substrate non-productive complex. However, on crystalline substrates, the activity of CHI60 was only inhibited approximately 50% at high ionic strength, suggesting that the enzyme hydrolyzes crystalline substrates with an exo-type mode processively while remaining tightly bound to the substrate. Moreover, substitution of Trp-33 to either phenylalanine or tyrosine reduced the activity of the enzyme at high ionic strength, suggesting an important role of Trp-33 on enzyme processivity.

  16. Dependency of the hydrogen bonding capacity of the solvent anion on the thermal stability of feruloyl esterases in ionic liquid systems

    DEFF Research Database (Denmark)

    Zeuner, Birgitte; Ståhlberg, Tim; Nguyen van Buu, Olivier

    2011-01-01

    acid with glycerol in four ionic liquid (IL) systems. The IL systems were systematically composed of two selected pairs of cations and anions, respectively: [BMIm][PF6], [C2OHMIm][PF6], [BMIm][BF4], and [C2OHMIm][BF4]. AnFaeA had activity in [PF6]--based ILs, whereas the AndFaeC and the FAE in Ultraflo...

  17. On the Chemical Stabilities of Ionic Liquids

    OpenAIRE

    Yen-Ho Chu; Ming-Chung Tseng; Venkatesan Srinivasadesikan; Subbiah Sowmiah

    2009-01-01

    Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transfor...

  18. Ionic liquid electrolytes for dye-sensitized solar cells.

    Science.gov (United States)

    Gorlov, Mikhail; Kloo, Lars

    2008-05-28

    The potential of room-temperature molten salts (ionic liquids) as solvents for electrolytes for dye-sensitized solar cells has been investigated during the last decade. The non-volatility, good solvent properties and high electrochemical stability of ionic liquids make them attractive solvents in contrast to volatile organic solvents. Despite this, the relatively high viscosity of ionic liquids leads to mass-transport limitations. Here we review recent developments in the application of different ionic liquids as solvents or components of liquid and quasi-solid electrolytes for dye-sensitized solar cells.

  19. Incubating Isolated Mouse EDL Muscles with Creatine Improves Force Production and Twitch Kinetics in Fatigue Due to Reduction in Ionic Strength

    Science.gov (United States)

    Head, Stewart I.; Greenaway, Bronwen; Chan, Stephen

    2011-01-01

    Background Creatine supplementation can improve performance during high intensity exercise in humans and improve muscle strength in certain myopathies. In this present study, we investigated the direct effects of acute creatine incubation on isolated mouse fast-twitch EDL muscles, and examined how these effects change with fatigue. Methods and Results The extensor digitorum longus muscle from mice aged 12–14 weeks was isolated and stimulated with field electrodes to measure force characteristics in 3 different states: (i) before fatigue; (ii) immediately after a fatigue protocol; and (iii) after recovery. These served as the control measurements for the muscle. The muscle was then incubated in a creatine solution and washed. The measurement of force characteristics in the 3 different states was then repeated. In un-fatigued muscle, creatine incubation increased the maximal tetanic force. In fatigued muscle, creatine treatment increased the force produced at all frequencies of stimulation. Incubation also increased the rate of twitch relaxation and twitch contraction in fatigued muscle. During repetitive fatiguing stimulation, creatine-treated muscles took 55.1±9.5% longer than control muscles to lose half of their original force. Measurement of weight changes showed that creatine incubation increased EDL muscle mass by 7%. Conclusion Acute creatine application improves force production in isolated fast-twitch EDL muscle, and these improvements are particularly apparent when the muscle is fatigued. One likely mechanism for this improvement is an increase in Ca2+ sensitivity of contractile proteins as a result of ionic strength decreases following creatine incubation. PMID:21850234

  20. Incubating isolated mouse EDL muscles with creatine improves force production and twitch kinetics in fatigue due to reduction in ionic strength.

    Directory of Open Access Journals (Sweden)

    Stewart I Head

    Full Text Available BACKGROUND: Creatine supplementation can improve performance during high intensity exercise in humans and improve muscle strength in certain myopathies. In this present study, we investigated the direct effects of acute creatine incubation on isolated mouse fast-twitch EDL muscles, and examined how these effects change with fatigue. METHODS AND RESULTS: The extensor digitorum longus muscle from mice aged 12-14 weeks was isolated and stimulated with field electrodes to measure force characteristics in 3 different states: (i before fatigue; (ii immediately after a fatigue protocol; and (iii after recovery. These served as the control measurements for the muscle. The muscle was then incubated in a creatine solution and washed. The measurement of force characteristics in the 3 different states was then repeated. In un-fatigued muscle, creatine incubation increased the maximal tetanic force. In fatigued muscle, creatine treatment increased the force produced at all frequencies of stimulation. Incubation also increased the rate of twitch relaxation and twitch contraction in fatigued muscle. During repetitive fatiguing stimulation, creatine-treated muscles took 55.1±9.5% longer than control muscles to lose half of their original force. Measurement of weight changes showed that creatine incubation increased EDL muscle mass by 7%. CONCLUSION: Acute creatine application improves force production in isolated fast-twitch EDL muscle, and these improvements are particularly apparent when the muscle is fatigued. One likely mechanism for this improvement is an increase in Ca(2+ sensitivity of contractile proteins as a result of ionic strength decreases following creatine incubation.

  1. Effect of ionic strength and cationic DNA affinity binders on the DNA sequence selective alkylation of guanine N7-positions by nitrogen mustards

    International Nuclear Information System (INIS)

    Hartley, J.A.; Forrow, S.M.; Souhami, R.L.

    1990-01-01

    Large variations in alkylation intensities exist among guanines in a DNA sequence following treatment with chemotherapeutic alkylating agents such as nitrogen mustards, and the substituent attached to the reactive group can impose a distinct sequence preference for reaction. In order to understand further the structural and electrostatic factors which determine the sequence selectivity of alkylation reactions, the effect of increase ionic strength, the intercalator ethidium bromide, AT-specific minor groove binders distamycin A and netropsin, and the polyamine spermine on guanine N7-alkylation by L-phenylalanine mustard (L-Pam), uracil mustard (UM), and quinacrine mustard (QM) was investigated with a modification of the guanine-specific chemical cleavage technique for DNA sequencing. The result differed with both the nitrogen mustard and the cationic agent used. The effect, which resulted in both enhancement and suppression of alkylation sites, was most striking in the case of netropsin and distamycin A, which differed from each other. DNA footprinting indicated that selective binding to AT sequences in the minor groove of DNA can have long-range effects on the alkylation pattern of DNA in the major groove

  2. Modeling and sensitivity analysis on the transport of aluminum oxide nanoparticles in saturated sand: effects of ionic strength, flow rate, and nanoparticle concentration.

    Science.gov (United States)

    Rahman, Tanzina; Millwater, Harry; Shipley, Heather J

    2014-11-15

    Aluminum oxide nanoparticles have been widely used in various consumer products and there are growing concerns regarding their exposure in the environment. This study deals with the modeling, sensitivity analysis and uncertainty quantification of one-dimensional transport of nano-sized (~82 nm) aluminum oxide particles in saturated sand. The transport of aluminum oxide nanoparticles was modeled using a two-kinetic-site model with a blocking function. The modeling was done at different ionic strengths, flow rates, and nanoparticle concentrations. The two sites representing fast and slow attachments along with a blocking term yielded good agreement with the experimental results from the column studies of aluminum oxide nanoparticles. The same model was used to simulate breakthrough curves under different conditions using experimental data and calculated 95% confidence bounds of the generated breakthroughs. The sensitivity analysis results showed that slow attachment was the most sensitive parameter for high influent concentrations (e.g. 150 mg/L Al2O3) and the maximum solid phase retention capacity (related to blocking function) was the most sensitive parameter for low concentrations (e.g. 50 mg/L Al2O3). Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Sorption properties of Th(IV) on the raw diatomite-Effects of contact time, pH, ionic strength and temperature

    International Nuclear Information System (INIS)

    Sheng Guodong; Hu Jun; Wang Xiangke

    2008-01-01

    Diatomite has a number of unique physicochemical properties and has diversified industrial uses. Natural diatomite has been tested as a potential sorbent for the removal of Th(IV) from aqueous solutions. The results indicate that sorption of Th(IV) is strongly dependent on ionic strength at pH 3. Outer-sphere complexation or ion exchange may be the main sorption mechanism of Th(IV) to diatomite at low pH values, whereas the sorption of Th(IV) at pH>3 is mainly dominated by inner-sphere complexation or precipitation. The competition for Th(IV) between aqueous or surface adsorbed anions (e.g., herein ClO 4 - , NO 3 - and Cl - ) and surface functional groups of diatomite is important for Th(IV) sorption. The thermodynamic data (ΔH 0 , ΔS 0 , ΔG 0 ) are calculated from the temperature-dependent sorption isotherms. The results suggest that sorption process of Th(IV) on diatomite is spontaneous and endothermic

  4. Sorption properties of Th(IV) on the raw diatomite--effects of contact time, pH, ionic strength and temperature.

    Science.gov (United States)

    Sheng, Guodong; Hu, Jun; Wang, Xiangke

    2008-10-01

    Diatomite has a number of unique physicochemical properties and has diversified industrial uses. Natural diatomite has been tested as a potential sorbent for the removal of Th(IV) from aqueous solutions. The results indicate that sorption of Th(IV) is strongly dependent on ionic strength at pH3. Outer-sphere complexation or ion exchange may be the main sorption mechanism of Th(IV) to diatomite at low pH values, whereas the sorption of Th(IV) at pH>3 is mainly dominated by inner-sphere complexation or precipitation. The competition for Th(IV) between aqueous or surface adsorbed anions (e.g., herein ClO(4)(-), NO(3)(-) and Cl(-)) and surface functional groups of diatomite is important for Th(IV) sorption. The thermodynamic data (DeltaH(0), DeltaS(0), DeltaG(0)) are calculated from the temperature-dependent sorption isotherms. The results suggest that sorption process of Th(IV) on diatomite is spontaneous and endothermic.

  5. Induction of Ca2+-dependent cyclosporin A-insensitive nonspecific permeability of the inner membrane of liver mitochondria and cytochrome c release by α,ω-hexadecanedioic acid in media of varying ionic strength.

    Science.gov (United States)

    Dubinin, M V; Vedernikov, A A; Khoroshavina, E I; Samartsev, V N

    2014-06-01

    In liver mitochondria loaded with Ca2+ or Sr(2+), α,ω-hexadecanedioic acid (HDA) can induce nonspecific permeability of the inner membrane (mitochondrial pore) by the mechanism insensitive to cyclosporin A (CsA). In this work we studied the effect of ionic strength of the incubation medium on the kinetics of the processes that accompany Ca2+-dependent induction of the mitochondrial pore by fatty acid: organelle swelling, Ca2+ release from the matrix, changes in transmembrane potential (Δψ) and rate of oxygen consumption, and the release of cytochrome c from the intermembrane space. Two basic incubation media were used: sucrose medium and isotonic ionic medium containing KCl without sucrose. We found that 200 μM Ca2+ and 20 μM HDA in the presence of CsA effectively induce high-amplitude swelling of mitochondria both in the case of sucrose and in the ionic incubation medium. In the presence of CsA, mitochondria can rapidly absorb Ca2+ and retain it in the matrix for a while without reducing Δψ. Upon incubation in the ionic medium, mitochondria retain most of the added Ca2+ in the matrix for a short time without reducing the Δψ. In both cases the addition of HDA to the mitochondria 2 min after the introduction of Ca2+ leads to the rapid release of these ions from the matrix and total drop in Δψ. The mitochondrial swelling induced by Ca2+ and HDA in non-ionic medium is accompanied by almost maximal stimulation of respiration. Under the same conditions, but during incubation of mitochondria in the ionic medium, it is necessary to add cytochrome c for significant stimulation of respiration. The mitochondrial swelling induced by Ca2+ and HDA leads to the release of cytochrome c in a larger amount in the case of ionic medium than for the sucrose medium. We conclude that high ionic strength of the incubation medium determines the massive release of cytochrome c from mitochondria and liberates it from the respiratory chain, which leads to blockade of electron

  6. Influence of ionic strength in the adsorption and during photocatalysis of reactive black 5 azo dye on TiO{sub 2} coated on non woven paper with SiO{sub 2} as a binder

    Energy Technology Data Exchange (ETDEWEB)

    Aguedach, Abdelkahhar [Laboratoire de l' Eau et environnement, Universite Chouaib Doukkali, Faculte des Sciences, BP.20, El Jadida, Maroc (Morocco); Brosillon, Stephan [Laboratoire Science Chimiques de Rennes UMR 6226, Equipe Chimie et Ingenierie des Procedes, Ecole Nationale Superieure de Chimie, Universite Rennes 1, avenue du General Leclerc, 35700 Rennes (France)], E-mail: Stephan.Brosillon@ensc-rennes.fr; Morvan, Jean [Laboratoire Science Chimiques de Rennes UMR 6226, Equipe Chimie et Ingenierie des Procedes, Ecole Nationale Superieure de Chimie, Universite Rennes 1, avenue du General Leclerc, 35700 Rennes (France); Lhadi, El Kbir [Laboratoire de l' Eau et environnement, Universite Chouaib Doukkali, Faculte des Sciences, BP.20, El Jadida, Maroc (Morocco)

    2008-01-31

    Reactive black 5 (RB5), an azo dye, was degraded by using UV-irradiated TiO{sub 2} coated on non woven paper with SiO{sub 2} as a binder. The adsorption capacity of the photocatalyst was studied at natural pH, superior to pH{sub pzc} of the binder, for various ionic strengths. Different salts such as NaCl, KCl, CaCl{sub 2}, LiCl, Ca(NO{sub 3}){sub 2} were used to increase the ionic strength. The presence of salt increased the adsorption capacity. The electrostatic interactions between dye and oxide surface charges (TiO{sub 2}/SiO{sub 2}) is very important in the adsorption phenomena. The effect of the ionic strength of the solution on photocatalyst degradation was studied. The rate of degradation was increased by the presence of salts in the range of the experimental conditions. The increase of the initial decolorization rate was observed in the following order: Ca{sup 2+} > K{sup +} > Na{sup +} > Li{sup +}. Experiments with different anions (Cl{sup -}, NO{sub 3}{sup -}) had shown that nitrate was an indifferent electrolyte for the adsorption and photodegradation of the dye on SiO{sub 2}/TiO{sub 2}.

  7. Influence of ionic strength in the adsorption and during photocatalysis of reactive black 5 azo dye on TiO2 coated on non woven paper with SiO2 as a binder

    International Nuclear Information System (INIS)

    Aguedach, Abdelkahhar; Brosillon, Stephan; Morvan, Jean; Lhadi, El Kbir

    2008-01-01

    Reactive black 5 (RB5), an azo dye, was degraded by using UV-irradiated TiO 2 coated on non woven paper with SiO 2 as a binder. The adsorption capacity of the photocatalyst was studied at natural pH, superior to pH pzc of the binder, for various ionic strengths. Different salts such as NaCl, KCl, CaCl 2 , LiCl, Ca(NO 3 ) 2 were used to increase the ionic strength. The presence of salt increased the adsorption capacity. The electrostatic interactions between dye and oxide surface charges (TiO 2 /SiO 2 ) is very important in the adsorption phenomena. The effect of the ionic strength of the solution on photocatalyst degradation was studied. The rate of degradation was increased by the presence of salts in the range of the experimental conditions. The increase of the initial decolorization rate was observed in the following order: Ca 2+ > K + > Na + > Li + . Experiments with different anions (Cl - , NO 3 - ) had shown that nitrate was an indifferent electrolyte for the adsorption and photodegradation of the dye on SiO 2 /TiO 2

  8. The effect of ionic strength on the adsorption of H{sup +}, Cd{sup 2+}, Pb{sup 2+}, and Cu{sup 2+} by Bacillus subtilis and Bacillus licheniformis: A surface complexation model

    Energy Technology Data Exchange (ETDEWEB)

    Daughney, C.J. [McGill Univ., Montreal, Quebec (Canada). Earth and Planetary Sciences; Fein, J.B. [Univ. of Notre Dame, IN (United States)

    1998-02-01

    To quantify metal adsorption onto bacterial surfaces, recent studies have applied surface complexation theory to model the specific chemical and electrostatic interactions occurring at the solution-cell wall interface. However, to date, the effect of ionic strength on these interactions has not been investigated. In this study, the authors perform acid-base titrations of suspensions containing Bacillus subtilis or Bacillus licheniformis in 0.01 or 0.1 M NaNO{sub 3}, and they evaluate the constant capacitance and basic Stern double-layer models for their ability to describe ionic-strength-dependent behavior. The constant capacitance model provides the best description of the experimental data. The constant capacitance model parameters vary between independently grown bacterial cultures, possibly due to cell wall variation arising from genetic exchange during reproduction. The authors perform metal-B. subtilis and metal-B. licheniformis adsorption experiments using Cd, Pb, and Cu, and they solve for stability constants describing metal adsorption onto distinct functional groups on the bacterial cell walls. They find that these stability constants vary substantially but systematically between the two bacterial species at the two different ionic strengths.

  9. Synthetic Organic Electrochemistry in Ionic Liquids: The Viscosity Question

    Directory of Open Access Journals (Sweden)

    Scott T. Handy

    2011-07-01

    Full Text Available Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents and have noted that the viscosity of the medium is a major problem, although with the addition of sufficient co-solvent, good results and excellent recovery and recycling of the ionic liquid can be achieved.

  10. Evaluation of biochar-ultrafiltration membrane processes for humic acid removal under various hydrodynamic, pH, ionic strength, and pressure conditions.

    Science.gov (United States)

    Shankar, Vaibhavi; Heo, Jiyong; Al-Hamadani, Yasir A J; Park, Chang Min; Chu, Kyoung Hoon; Yoon, Yeomin

    2017-07-15

    The performance of an ultrafiltration (UF)-biochar process was evaluated in comparison with a UF membrane process for the removal of humic acid (HA). Bench-scale UF experiments were conducted to study the rejection and flux trends under various hydrodynamic, pH, ionic strength, and pressure conditions. The resistance-in-series model was used to evaluate the processes and it showed that unlike stirred conditions, where low fouling resistance was observed (28.7 × 10 12  m -1 to 32.5 × 10 12  m -1 ), higher values and comparable trends were obtained for UF-biochar and UF alone for unstirred conditions (28.7 × 10 12  m -1 to 32.5 × 10 12  m -1 ). Thus, the processes were further evaluated under unstirred conditions. Additionally, total fouling resistance was decreased in the presence of biochar by 6%, indicating that HA adsorption by biochar could diminish adsorption fouling on the UF membrane and thus improve the efficiency of the UF-biochar process. The rejection trends of UF-biochar and UF alone were similar in most cases, whereas UF-biochar showed a noticeable increase in flux of around 18-25% under various experimental conditions due to reduced membrane fouling. Three-cycle filtration tests further demonstrated that UF-biochar showed better membrane recovery and antifouling capability by showing more HA rejection (3-5%) than UF membrane alone with each subsequent cycle of filtration. As a result of these findings, the UF-biochar process may potentially prove be a viable treatment option for the removal of HA from water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Effect of pH and ionic strength on sorption of Eu(III) to MX-80 bentonite: batch and XAFS study

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, G.D.; Wang, X.K. [School of Nuclear Science and Engincering, North China Electric Power Univ., BJ (China); Key Lab of Novel Thin Film Solar Cells, Inst. of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Shao, D.D.; Fan, Q.H.; Xu, D. [Key Lab of Novel Thin Film Solar Cells, Inst. of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Chen, Y.X. [School of Nuclear Science and Engincering, North China Electric Power Univ., BJ (China)

    2009-07-01

    Sorption of radionuclides on MX-80 bentonite has been studied extensively because of its high sorption capacity and low penetrability. Herein, MX-80 bentonite was characterized by acid-base titration, XRD and FTIR in detail. The sorption of Eu(III) from aqueous solution to MX-80 bentonite was investigated as a function of contact time, solid content, ionic strength and pH under N{sub 2} conditions. The experimental data was performed with the diffuse layer model (DLM) with the aid of FITEQL 3.1 code. The site densities are 2.52 x 10{sup -4} mol/g for [{identical_to}XOH] and 1.54 x 10{sup -4} mol/g for [{identical_to}YOH], and acidity constants as pK{sub a} are pK{sub XO} = 6.772, pK{sub YOH{sub 2}{sup +}} = -1.68. and pK{sub YO} = 4.145. The sorption of Eu(III) on MX-80 bentonite consists of {identical_to}YOEu{sup 2+} species at low pH values and {identical_to}XOEu(OH){sup 2+} species at high pH values. The sorption isotherms were simulated by Langmuir, Freundlich and Dubini-Radushkevich (D-R) models, respectively, and the results indicated that Langmuir model fitted the sorption data better than the Langmuir and D-R models. XAFS technique was applied to characterize the local structural environment of the adsorbed Eu(III), and the results indicated that Eu(III) was bond to O atoms at a distance of about 2.43 A as {identical_to}Y/XO-Eu{sup 2+} at low pH values. (orig.)

  12. Transport and retention of 14C-perfluorooctanoic acid (PFOA) in saturated limestone and sand porous media: Effects of input concentration, ionic strength and cation type

    Science.gov (United States)

    Xueyan, L.; Gao, B.; Sun, Y.; Wu, J.

    2017-12-01

    Perfluorooctanoic acid (PFOA) has been used in a wide variety of industrial and consumer product applications. PFOA has been detected around the world at ng/L to μg/L levels in groundwater, and at ng/g levels in soil.The physicochemical properties of porous media were proven to play pivotal roles in determining the transport behavior of various pollutants. It is anticipated that physicochemical properties of porous media will strongly influence the transport behavior of PFOA. In addition, previous investigations have revealed that input concentration significantly influence the transport behavior of nanoparticles and antibiotics. Thus, this study was designed experimentally and fundamentally to gain insight into transport and retention of PFOA in various porous medias at different input concentrations, solution IS and cation type. Unlike in quartz sand porous media, the BTCs in limestone porous media exhibited increasing retention rate and high degree of tailing in limestone porous media. Results showed that higher relative retention occurred in limestone porous media than in quartz sand porous media under the same solution chemistry. This result was attributed to the less negative zeta-potentials, rougher surface and larger specific surface area, and the presence of hydroxyl groups and organic matters of limestone grains. Higher ionic strength and Ca2+ had little impact on the mobility of PFOA in quartz sand porous media, but significantly enhanced the retention of PFOA in limestone porous media. The difference is likely due to the compression of the electrical double layer, and the surface-charge neutralization and cation-bridging effect of Ca2+. Higher input concentration resulted in lower relative PFOA retention in limestone porous media, but the influence were insignificant in quartz sand porous media. This effect is likely because attachment sites in limestone responced to the variety of input concentration differently than quartz.

  13. Antibodies to co-trimoxazole (trimethoprim and/or sulfamethoxazole) related to the presence of the drug in a commercial low-ionic-strength solution.

    Science.gov (United States)

    Pham, Bach-Nga; Gien, Dominique; Bensaad, Farid; Babinet, Jérome; Dubeaux, Isabelle; Rouger, Philippe; Le Pennec, Pierre-Yves

    2012-04-01

    Drug-dependent antibodies have been associated with approximately 10% of acquired immune hemolytic anemia cases. These antibodies are a rare cause of interference in pretransfusion red blood cell (RBC) serologic testing. The aim of this work was to report three cases of subjects developing antibodies against co-trimoxazole, a combination of trimethoprim (TMP) and sulfamethoxazole (SMX). Blood samples of donor/patients were referred to our laboratory for the exploration of a positive antibody detection test. There was no recent history of drug taking. Antibody identification was performed by gel test using an indirect antiglobulin test, with reagent RBCs in low-ionic-strength solutions (LISS) containing co-trimoxazole or not. All three sera showed positive reactions when RBCs were resuspended in LISS containing co-trimoxazole, but negative reactions when RBCs were resuspended in LISS without antibiotic. We detected antibodies against co-trimoxazole showing three different antibody patterns: anti-TMP plus anti-SMX, anti-TMP alone, or anti-SMX alone. Anti-TMP showed an apparent anti-Ku specificity in the two cases where it was present. Anti-SMX showed an apparent anti-H specificity in one of the two cases described. The drug-dependent antibodies were not associated with acquired hemolytic anemia or other pathologies. Antibodies against co-trimoxazole may only be detected when using a diluent for reagent RBCs containing the drug in question. Antibody pattern (anti-TMP and/or anti-SMX) may vary according to individuals' immune response. Drug-dependent antibodies may react as antibodies against a high-prevalence antigen, supporting the hypothesis of antibodies to drug and membrane components. Drug-dependent antibodies such as anti-co-trimoxazole may be a serologic finding without clinical features. © 2011 American Association of Blood Banks.

  14. Continuum electrostatics for ionic solutions with non-uniform ionic sizes

    International Nuclear Information System (INIS)

    Li Bo

    2009-01-01

    This work concerns electrostatic properties of an ionic solution with multiple ionic species of possibly different ionic sizes. Such properties are described by the minimization of an electrostatic free-energy functional of ionic concentrations. Bounds are obtained for ionic concentrations with low electrostatic free energies. Such bounds are used to show that there exists a unique set of equilibrium ionic concentrations that minimizes the free-energy functional. The equilibrium ionic concentrations are found to depend sorely on the equilibrium electrostatic potential, resembling the classical Boltzmann distributions that relate the equilibrium ionic concentrations to the equilibrium electrostatic potential. Unless all the ionic and solvent molecular sizes are assumed to be the same, explicit formulae of such dependence are, however, not available in general. It is nevertheless proved that in equilibrium the ionic charge density is a decreasing function of the electrostatic potential. This determines a variational principle with a convex functional for the electrostatic potential

  15. Experimental Determination of Lead Interactions with Citrate and EDTA in NaCl and MgCl2 Solutions to High Ionic Strength and Its Applications.

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Yongliang [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Carlsbad Programs Group; Kirkes, Leslie Dawn [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Carlsbad Programs Group; Westfall, Terry [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Carlsbad Programs Group; Marrs, Cassandra [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Carlsbad Programs Group; Knox, Jandi [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Carlsbad Programs Group; Burton, Heather Lynn [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Carlsbad Programs Group

    2017-09-01

    For this study, the interactions of lead with citrate and ethylenediaminetetraacetate (EDTA) are investigated based on solubility measurements as a function of ionic strength at room temperature (22.5 ± 0.5°C) in NaCl and MgCl2 solutions. The formation constants (log β10 ) for Pb[C3H5O(COO)3]– (abbreviated as PbCitrate) and Pb[(CH2COO)2N(CH2)2N(CH2COO)2)]2– (abbreviated as PbEDTA2–) Pb2+ + [C3H5O(COO)3]3– = Pb[C3H5O(COO)3] (1) Pb2+ + (CH2COO)2N(CH2)2N(CH2COO)2)4- = Pb[(CH2COO)2N(CH2)2N(CH2COO)2)]2– (2) are evaluated as 7.28 ± 0.18 (2σ) and 20.00 ± 0.20 (2σ), respectively, with a set of Pitzer parameters describing the specific interactions in NaCl and MgCl2 media. Based on these parameters, the interactions of lead with citrate and EDTA in various low temperature environments can be accurately modelled.

  16. Generation and detection of the cyclohexadienyl radical in phosphonium ionic liquids.

    Science.gov (United States)

    Lauzon, J M; Arseneau, D J; Brodovitch, J C; Clyburne, J A C; Cormier, P; McCollum, B; Ghandi, K

    2008-10-21

    The formation of the cyclohexadienyl radical, C(6)H(6)Mu, in ionic and molecular solvents has been compared. This is the first time that a muoniated free radical is reported in an ionic liquid. In marked contrast to molecular liquids, free radical generation in ionic liquids is significantly enhanced. Comparison of the hyperfine interactions in the ionic liquid and in molecular solvents and with theoretical calculations, suggests significant and unforeseen solvent interaction with the cyclohexadienyl radical.

  17. On the Chemical Stabilities of Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Yen-Ho Chu

    2009-09-01

    Full Text Available Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transformations. However, synthetic chemists cannot ignore the stability data and intermolecular interactions, or even reactions that are directly applicable to organic reactions in ionic liquids. It is becoming evident from the increasing number of reports on use of ionic liquids as solvents, catalysts, and reagents in organic synthesis that they are not totally inert under many reaction conditions. While in some cases, their unexpected reactivity has proven fortuitous and in others, it is imperative that when selecting an ionic liquid for a particular synthetic application, attention must be paid to its compatibility with the reaction conditions. Even though, more than 200 room temperature ionic liquids are known, only a few reports have commented their effects on reaction mechanisms or rate/stability. Therefore, rather than attempting to give a comprehensive overview of ionic liquid chemistry, this review focuses on the non-innocent nature of ionic liquids, with a decided emphasis to clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions thereby affecting and promoting the yield and selectivity.

  18. On the chemical stabilities of ionic liquids.

    Science.gov (United States)

    Sowmiah, Subbiah; Srinivasadesikan, Venkatesan; Tseng, Ming-Chung; Chu, Yen-Ho

    2009-09-25

    Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transformations. However, synthetic chemists cannot ignore the stability data and intermolecular interactions, or even reactions that are directly applicable to organic reactions in ionic liquids. It is becoming evident from the increasing number of reports on use of ionic liquids as solvents, catalysts, and reagents in organic synthesis that they are not totally inert under many reaction conditions. While in some cases, their unexpected reactivity has proven fortuitously advantageous in others is has been a problem, it is imperative that when selecting an ionic liquid for a particular synthetic application, attention be paid to its compatibility with the reaction conditions. Even though, more than 200 room temperature ionic liquids are known, only a few reports have commented their effects on reaction mechanisms or rate/stability. Therefore, rather than attempting to give a comprehensive overview of ionic liquid chemistry, this review focuses on the non-innocent nature of ionic liquids, with a decided emphasis to clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions thereby affecting and promoting the yield and selectivity.

  19. Radiation Chemistry and Photochemistry of Ionic Liquids

    International Nuclear Information System (INIS)

    Wishart, J.F.; Takahaski, K.

    2010-01-01

    As our understanding of ionic liquids and their tunable properties has grown, it is possible to see many opportunities for ionic liquids to contribute to the sustainable use of energy. The potential safety and environmental benefits of ionic liquids, as compared to conventional solvents, have attracted interest in their use as processing media for the nuclear fuel cycle. Therefore, an understanding of the interactions of ionizing radiation and photons with ionic liquids is strongly needed. However, the radiation chemistry of ionic liquids is still a relatively unexplored topic although there has been a significant increase in the number of researchers in the field recently. This article provides a brief introduction to ionic liquids and their interesting properties, and recent advances in the radiation chemistry and photochemistry of ionic liquids. In this article, we will mainly focus on excess electron dynamics and radical reaction dynamics. Because solvation dynamics processes in ionic liquids are much slower than in molecular solvents, one of the distinguishing characteristics is that pre-solvated electrons play an important role in ionic liquid radiolysis. It will be also shown that the reaction dynamics of radical ions is significantly different from that observed in molecular solvents because of the Coulombic screening effects and electrostatic interactions in ionic liquids.

  20. Application of Ionic Liquids in Hydrometallurgy

    Science.gov (United States)

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Lee, Jinyoung; Kwon, Kyungjung; Lee, Churl Kyoung

    2014-01-01

    Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry. PMID:25177864

  1. Polypyrrole for Artificial Muscles: Ionic Mechanisms

    DEFF Research Database (Denmark)

    Skaarup, Steen

    2006-01-01

    the matrix of a polymer electrode – thereby causing volume expansion which can be converted into work. Solvent molecules are able to penetrate the polymer too. A precise description of the nature of these ionic and solvent movements is therefore important for understanding and improving the performance....... This work examines the influence of solvent, ionic species and electrolyte concentration on the fundamental question about the ionic mechanism involved: Is the actuation process driven by anion motion, cation motion, or a mixture of the two? In addition: What is the extent of solvent motion? The discussion...... is centered on polypyrrole (PPy), which is the material most used and studied. The tetraethyl ammonium cation (TEA) is shown to be able to move in and out of PPy(DBS) polymer films, in contrast to expectations. There is a switching between ionic mechanisms during cycling in TEACl electrolyte....

  2. Study of thioglycosylation in ionic liquids

    Directory of Open Access Journals (Sweden)

    Ragauskas Arthur

    2006-06-01

    Full Text Available Abstract A novel, green chemistry, glycosylation strategy was developed based upon the use of ionic liquids. Research studies demonstrated that thiomethyl glycosides could readily be activated with methyl trifluoromethane sulfonate, using 1-butyl-3-methylimidazolium tetrafluoroborate as a solvent. This green chemistry glycosylation strategy provided disaccharides with typical yields averaging 75%. The ionic liquid solvent could be readily reused for five sequential glycosylation reactions with no impact on product yield.

  3. Magnetic Solid-phase Extraction with Fe3O4/Molecularly Imprinted Polymers Modified by Deep Eutectic Solvents and Ionic Liquids for the Rapid Purification of Alkaloid Isomers (Theobromine and Theophylline from Green Tea

    Directory of Open Access Journals (Sweden)

    Guizhen Li

    2017-06-01

    Full Text Available Different kinds of deep eutectic solvents (DES based on choline chloride (ChCl and ionic liquids (ILs based on 1-methylimidazole were used to modify Fe3O4/molecularly imprinted polymers (Fe3O4/MIPs, and the resulting materials were applied for the rapid purification of alkaloid isomers (theobromine and theophylline from green tea with magnetic solid-phase extraction (M-SPE. The M-SPE procedure was optimized using the response surface methodology (RSM to analyze the maximum conditions. The materials were characterized by Fourier transform infrared spectroscopy (FI-IR and field emission scanning electron microscopy (FE-SEM. Compared to the ILs-Fe3O4/MIPs, the DESs-Fe3O4/MIPs were developed for the stronger recognition and higher recoveries of the isomers (theophylline and theobromine from green tea, particularly DES-7-Fe3O4/MIPs. With RSM, the optimal recovery condition for theobromine and theophylline in the M-SPE were observed with ratio of methanol (80% as the washing solution, methanol/acetic acid (HAc (8:2 as the eluent at pH 3, and an eluent volume of 4 mL. The practical recoveries of theobromine and theophylline in green tea were 92.27% and 87.51%, respectively, with a corresponding actual extraction amount of 4.87 mg•g−1 and 5.07 mg•g−1. Overall, the proposed approach with the high affinity of Fe3O4/MIPs might offer a novel method for the purification of complex isomer samples.

  4. Magnetic Solid-phase Extraction with Fe₃O₄/Molecularly Imprinted Polymers Modified by Deep Eutectic Solvents and Ionic Liquids for the Rapid Purification of Alkaloid Isomers (Theobromine and Theophylline) from Green Tea.

    Science.gov (United States)

    Li, Guizhen; Wang, Xiaoqin; Row, Kyung Ho

    2017-06-25

    Different kinds of deep eutectic solvents (DES) based on choline chloride (ChCl) and ionic liquids (ILs) based on 1-methylimidazole were used to modify Fe3O4/molecularly imprinted polymers (Fe3O4/MIPs), and the resulting materials were applied for the rapid purification of alkaloid isomers (theobromine and theophylline) from green tea with magnetic solid-phase extraction (M-SPE). The M-SPE procedure was optimized using the response surface methodology (RSM) to analyze the maximum conditions. The materials were characterized by Fourier transform infrared spectroscopy (FI-IR) and field emission scanning electron microscopy (FE-SEM). Compared to the ILs-Fe3O4/MIPs, the DESs-Fe3O4/MIPs were developed for the stronger recognition and higher recoveries of the isomers (theophylline and theobromine) from green tea, particularly DES-7-Fe3O4/MIPs. With RSM, the optimal recovery condition for theobromine and theophylline in the M-SPE were observed with ratio of methanol (80%) as the washing solution, methanol/acetic acid (HAc) (8:2) as the eluent at pH 3, and an eluent volume of 4 mL. The practical recoveries of theobromine and theophylline in green tea were 92.27% and 87.51%, respectively, with a corresponding actual extraction amount of 4.87 mg•g-1 and 5.07 mg•g-1. Overall, the proposed approach with the high affinity of Fe3O4/MIPs might offer a novel method for the purification of complex isomer samples.

  5. Ionic Liquids in HPLC and CE: A Hope for Future.

    Science.gov (United States)

    Ali, Imran; Suhail, Mohd; Sanagi, Mohd Marsin; Aboul-Enein, Hassan Y

    2017-07-04

    The ionic liquids (ILs) are salts with melting points below 100°C. These are called as ionic fluids, ionic melts, liquid electrolytes, fused salts, liquid salts, ionic glasses, designer solvents, green solvents and solvents of the future. These have a wide range of applications, including medical, pharmaceutical and chemical sciences. Nowadays, their use is increasing greatly in separation science, especially in chromatography and capillary electrophoresis due to their remarkable properties. The present article describes the importance of ILs in high-performance liquid chromatography and capillary electrophoresis. Efforts were also made to highlight the future expectations of ILs.

  6. Theoretical modeling of cationic surfactant aggregation at the silica/aqueous solution interface: Effects of pH and ionic strength

    NARCIS (Netherlands)

    Drach, M.; Andrzejewska, A.; Narkiewicz-Michalek, J.; Rudzinski, W.; Koopal, L.K.

    2002-01-01

    A theory of ionic surfactant aggregation on oppositely charged surfaces is presented. In the proposed model the adsorbed phase is considered as a mixture of singly dispersed surfactant molecules, monolayered and bilayered aggregates of various sizes and the ions of simple electrolyte added to the

  7. Into the depths of deep eutectic solvents

    NARCIS (Netherlands)

    Rodriguez, N.; Alves da Rocha, M.A.; Kroon, M.C.

    2015-01-01

    Ionic liquids (ILs) have been successfully tested in a wide range of applications; however, their high price and complicated synthesis make them infeasible for large scale implementation. A decade ago, a new generation of solvents so called deep eutectic solvents (DESs) was reported for the first

  8. Selection and design of solvents

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    and design of solvents will be presented together with application examples. The selection problem is defined as finding known chemicals that match the desired functions of a solvent for a specified set of applications. The design problem is defined as finding the molecular structure (or mixture of molecules....... With increasing interest on issues such as waste, sustainability, environmental impact and green chemistry, the selection and design of solvents have become important problems that need to be addressed during chemical product-process design and development. Systematic methods and tools suitable for selection......) that match the desired functions of a solvent for a specified set of applications. Use of organic chemicals and ionic liquids as solvents will be covered....

  9. Learning Ionic

    CERN Document Server

    Ravulavaru, Arvind

    2015-01-01

    This book is intended for those who want to learn how to build hybrid mobile applications using Ionic. It is also ideal for people who want to explore theming for Ionic apps. Prior knowledge of AngularJS is essential to complete this book successfully.

  10. Solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, D.M.; Latimer, E.G.

    1988-01-05

    It is an object of this invention to provide for the demetallization and general upgrading of heavy oil via a solvent extracton process, and to improve the efficiency of solvent extraction operations. The yield and demetallization of product oil form heavy high-metal content oil is maximized by solvent extractions which employ either or all of the following techniques: premixing of a minor amount of the solvent with feed and using countercurrent flow for the remaining solvent; use of certain solvent/free ratios; use of segmental baffle tray extraction column internals and the proper extraction column residence time. The solvent premix/countercurrent flow feature of the invention substantially improves extractions where temperatures and pressures above the critical point of the solvent are used. By using this technique, a greater yield of extract oil can be obtained at the same metals content or a lower metals-containing extract oil product can be obtained at the same yield. Furthermore, the premixing of part of the solvent with the feed before countercurrent extraction gives high extract oil yields and high quality demetallization. The solvent/feed ratio features of the invention substanially lower the captial and operating costs for such processes while not suffering a loss in selectivity for metals rejection. The column internals and rsidence time features of the invention further improve the extractor metals rejection at a constant yield or allow for an increase in extract oil yield at a constant extract oil metals content. 13 figs., 3 tabs.

  11. Membrane separation of ionic liquid solutions

    Science.gov (United States)

    Campos, Daniel; Feiring, Andrew Edward; Majumdar, Sudipto; Nemser, Stuart

    2015-09-01

    A membrane separation process using a highly fluorinated polymer membrane that selectively permeates water of an aqueous ionic liquid solution to provide dry ionic liquid. Preferably the polymer is a polymer that includes polymerized perfluoro-2,2-dimethyl-1,3-dioxole (PDD). The process is also capable of removing small molecular compounds such as organic solvents that can be present in the solution. This membrane separation process is suitable for drying the aqueous ionic liquid byproduct from precipitating solutions of biomass dissolved in ionic liquid, and is thus instrumental to providing usable lignocellulosic products for energy consumption and other industrial uses in an environmentally benign manner.

  12. Supported Ionic Liquid Phase (SILP) catalysis

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco

    2006-01-01

    Applications of ionic liquids to replace conventional solvents in homogeneous transition-metal catalysis have increased significantly during the last decade. Biphasic ionic liquid/organic liquid systems offer advantages with regard to product separation, catalyst stability, and recycling...... but utilise in the case of fast chemical reactions only a small amount of expensive ionic liquid and catalyst. The novel Supported Ionic Liquid Phase (SILP) catalysis concept overcomes these drawbacks and allows the use of fixed-bed reactors for continuous reactions. In this Microreview the SILP catalysis...

  13. Ionic liquid marbles.

    Science.gov (United States)

    Gao, Lichao; McCarthy, Thomas J

    2007-10-09

    Liquid marbles have been reported during this decade and have been argued to be potentially useful for microfluidic and lab-on-a-chip applications. The liquid marbles described to date have been composed of either water or glycerol as the liquid and hydrophobized lycopodium or silica as the stabilizing particles. Both of these components are potentially reactive and do not permit the use of organic chemistry; the liquids are volatile. We report the use of perfluoroalkyl particles (oligomeric (OTFE) and polymeric (PTFE) tetrafluoroethylene, which are unreactive) to support/stabilize a range of ionic liquid marbles. Ionic liquids are not volatile and have been demonstrated to be versatile solvents for chemical transformations. Water marbles prepared with OTFE are much more robust than those prepared with hydrophobized lycopodium or silica.

  14. Disentangled solid state and metastable polymer melt; a solvent free route to high-modulus high-strength tapes and films of UHMWPE

    Science.gov (United States)

    Rastogi, Sanjay

    2013-03-01

    Ultra High Molecular Weight Polyethylene (UHMWPE) having average molar mass greater than a million g/mol is an engineering polymer. Due to its light-weight, high abrasion resistance and biocompatibility it is used for demanding applications such as body armour, prostheses etc. At present, because of its high melt viscosity to achieve the uniaxial/biaxial properties in the form of fibers/films the polymer is processed via solution route where nearly 95wt% of the solvent is used to process 5wt% of the polymer. In past several attempts have been made to process the polymer without using any solvent. However, compared to the solvent processing route the achieved mechanical properties were rather poor. Here we show that by controlled synthesis it is feasible to obtain UHMWPE that could be processed free of solvent to make uniaxial tapes and biaxial films, having unprecedented mechanical properties, exceeding that of the solution spun fibers. We address some of the fundamental aspects of chemistry, physics, rheology and processing for the development of desired morphological features to achieve the ultimate mechanical properties in tapes and films. The paper will also address the metastable melt state obtained on melting of the disentangled crystals and its implication on rheology in linear and nonlinear viscoelastic region. Solid state NMR studies will be applied to establish disentangled state in solid state to the polymerisation conditions. References: Macromolecules 2011, 44(14), 5558-5568; Nature Materials 2005, 4, 635-641; Phys Rev Lett 2006, 96(21), 218303-218205. The authors acknowledge financial support by the Dutch Polymer Institute.

  15. Ionic and Molecular Liquids

    DEFF Research Database (Denmark)

    Chaban, Vitaly V.; Prezhdo, Oleg

    2013-01-01

    Because of their outstanding versatility, room-temperature ionic liquids (RTILs) are utilized in an ever increasing number of novel and fascinating applications, making them the Holy Grail of modern materials science. In this Perspective, we address the fundamental research and prospective...... applications of RTILs in combination with molecular liquids, concentrating on three significant areas: (1) the use of molecular liquids to decrease the viscosity of RTILs; (2) the role of RTIL micelle formation in water and organic solvents; and (3) the ability of RTILs to adsorb pollutant gases. Current...

  16. Polyethersulfone flat sheet and hollow fiber membranes from solutions in ionic liquids

    KAUST Repository

    Kim, Dooli

    2017-06-10

    We fabricated flat-sheet and hollow fiber membranes from polyethersulfone (PES) solutions in two ionic liquids: 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM]DEP) and 1,3-dimethylimidazolium dimethyl phosphate ([MMIM]DMP). The solvents are non-volatile and less toxic than organic solvents, such as dimethylformamide (DMF). The membranes morphologies were compared with those of membranes prepared from solutions in DMF, using electron microscopy. Water permeance, solute rejection and mechanical strengths were evaluated. Membranes were applied to DNA separation. While membranes based on PES were successfully prepared, polysulfone (PSf) does not dissolve in the same ionic liquids. The discrepancy between PES and PSf could not be explained using classical Flory-Huggins theory, which does not consider the coulombic contributions in ionic liquids. The differences in solubility could be understood, by applying density functional theory to estimate the interaction energy between the different polymers and solvents. The theoretical results were supported by experimental measurements of intrinsic viscosity and dynamic light scattering (DLS).

  17. Ionic Liquid Epoxy Resin Monomers

    Science.gov (United States)

    Paley, Mark S. (Inventor)

    2013-01-01

    Ionic liquid epoxide monomers capable of reacting with cross-linking agents to form polymers with high tensile and adhesive strengths. Ionic liquid epoxide monomers comprising at least one bis(glycidyl) N-substituted nitrogen heterocyclic cation are made from nitrogen heterocycles corresponding to the bis(glycidyl) N-substituted nitrogen heterocyclic cations by a method involving a non-nucleophilic anion, an alkali metal cation, epichlorohydrin, and a strong base.

  18. Deasphalting solvents

    International Nuclear Information System (INIS)

    Carrillo, J. A; Caceres, J; Vela, G; Bueno, H

    1996-01-01

    This paper describes how the deasphalted oil (DMO) or demetalized oil (DMO) quality (CCR, Ni, V end asphaltenes contents) changes with: DAO or DMO yield, solvent/feed ratio, type of vacuum reside (from paraffinic to blends with vis breaking bottoms), extraction temperature and extraction solvent (propane, propylene, n-butane and I butane)

  19. Recent developments in biocatalysis in multiphasic ionic liquid reaction systems.

    Science.gov (United States)

    Meyer, Lars-Erik; von Langermann, Jan; Kragl, Udo

    2018-06-01

    Ionic liquids are well known and frequently used 'designer solvents' for biocatalytic reactions. This review highlights recent achievements in the field of multiphasic ionic liquid-based reaction concepts. It covers classical biphasic systems including supported ionic liquid phases, thermo-regulated multi-component solvent systems (TMS) and polymerized ionic liquids. These powerful concepts combine unique reaction conditions with a high potential for future applications on a laboratory and industrial scale. The presence of a multiphasic system simplifies downstream processing due to the distribution of the catalyst and reactants in different phases.

  20. Probing the Interaction of Ionic Liquids with CO2: A Raman Spectroscopy and Ab Initio Study

    National Research Council Canada - National Science Library

    Eucker, IV, William

    2008-01-01

    ...) with selected ionic liquids (ILs). Raman spectroscopy and first principle quantum mechanical calculations were performed on selected IL solvents in contact with CO2 in the effort to discover how the solvents interact with the gas. ILs are salts...

  1. Solvent substitution

    International Nuclear Information System (INIS)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general ''Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated

  2. Solvent substitution

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  3. Towards understanding the effects of van der Waals strengths on the electric double-layer structures and capacitive behaviors

    Science.gov (United States)

    Yang, Huachao; Bo, Zheng; Yang, Jinyuan; Yan, Jianhua; Cen, Kefa

    2017-10-01

    Solid-liquid interactions are considered to play a crucial role in charge storage capability of electric double-layer capacitors (EDLCs). In this work, effects of van der Waals (VDW) strengths on the EDL structures and capacitive performances within two representative electrolytes of solvated aqueous solutions and solvent-free ionic liquids are illuminated by molecular dynamics simulations. Single crystalline metals with similar lattice constant but diverse VDW potentials are employed as electrodes. Upon enhancing VDW strengths, capacitance of aqueous electrolytes first increases conspicuously by ∼34.0% and then descends, manifesting a non-monotonic trend, which goes beyond traditional perspectives. Such unusual observation is interpreted by the excluded-volume effects stemmed from ion-solvent competitions. Stimulated by predominant coulombic interactions, more ions are aggregated at the interface despite of the increasing VDW potentials, facilitating superior screening efficiency and capacitance. However, further enhancing strengths preferentially attracts more solvents instead of ions to the electrified surface, which in turn strikingly repels ions from Helmholtz layers, deteriorating electrode capacitance. An essentially similar feather is also recognized for ionic liquids, while the corresponding mechanisms are prominently ascribed to the suppressed ionic separations issued from cation-anion competitions. We highlight that constructing electrode materials with a moderate-hydrophilicity could further advance the performances of EDLCs.

  4. Ionic liquids in the synthesis of nanoobjects

    International Nuclear Information System (INIS)

    Tarasova, Natalia P; Smetannikov, Yurii V; Zanin, A A

    2010-01-01

    Data on the usage of the novel green solvents, ionic liquids, in the synthesis of nanoobjects and their stabilization are considered. The information is structured according to the resulting products of the synthetic processes: nanoparticles of noble metals, nanoparticles of non-metals, nanoparticles of metal oxides and chalcogenides, nanocomposites, and highly dispersed polymers. The conclusion is made that the ionic liquids might determine the structure and the properties of the nanoobjects, thus opening new fundamental and technological horizons in nanochemistry.

  5. Recent development of ionic liquid membranes

    OpenAIRE

    Wang, Junfeng; Luo, Jianquan; Feng, Shicao; Li, Haoran; Wan, Yinhua; Zhang, Xiangping

    2016-01-01

    The interest in ionic liquids (IL) is motivated by its unique properties, such as negligible vapor pressure, thermal stability, wide electrochemical stability window, and tunability of properties. ILs have been highlighted as solvents for liquidâliquid extraction and liquid membrane separation. To further expand its application in separation field, the ionic liquid membranes (ILMs) and its separation technology have been proposed and developed rapidly. This paper is to give a comprehensive ov...

  6. New electrolytes for aluminum production: Ionic liquids

    Science.gov (United States)

    Zhang, Mingming; Kamavarum, Venkat; Reddy, Ramana G.

    2003-11-01

    In this article, the reduction, refining/recycling, and electroplating of aluminum from room-temperature molten salts are reviewed. In addition, the characteristics of several non-conventional organic solvents, electrolytes, and molten salts are evaluated, and the applicability of these melts for production of aluminum is discussed with special attention to ionic liquids. Also reviewed are electrochemical processes and conditions for electrodeposition of aluminum using ionic liquids at near room temperatures.

  7. The Solubility Parameters of Ionic Liquids

    Science.gov (United States)

    Marciniak, Andrzej

    2010-01-01

    The Hildebrand’s solubility parameters have been calculated for 18 ionic liquids from the inverse gas chromatography measurements of the activity coefficients at infinite dilution. Retention data were used for the calculation. The solubility parameters are helpful for the prediction of the solubility in the binary solvent mixtures. From the solubility parameters, the standard enthalpies of vaporization of ionic liquids were estimated. PMID:20559495

  8. The Solubility Parameters of Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Andrzej Marciniak

    2010-04-01

    Full Text Available The Hildebrand’s solubility parameters have been calculated for 18 ionic liquids from the inverse gas chromatography measurements of the activity coefficients at infinite dilution. Retention data were used for the calculation. The solubility parameters are helpful for the prediction of the solubility in the binary solvent mixtures. From the solubility parameters, the standard enthalpies of vaporization of ionic liquids were estimated.

  9. Lipid processing in ionic liquids

    DEFF Research Database (Denmark)

    Lue, Bena-Marie; Guo, Zheng; Xu, Xuebing

    2007-01-01

    Ionic liquids (ILs) have been touted as “green” alternatives to traditional molecular solvents and have many unique properties which make them extremely desirable substitutes. Among their most attractive properties are their lack of vapour pressure, broad liquid range, strong solvating power and ...... and the ability to tailor properties of individual ILs to meet specific requirements. This article highlights current research as well as the vast potential of ILs for use as media for reactions, separation and processing in the lipid area....

  10. Effect of temperature and ionic strength on volumetric and acoustic properties of solutions of urea alkyl derivatives in aqueous NaCl

    International Nuclear Information System (INIS)

    Krakowiak, Joanna; Wawer, Jarosław

    2015-01-01

    Highlights: • Urea and its alkyl derivatives in aqueous NaCl solutions were studied. • The density and the speed of sound were measured for presented systems. • The strongest impact of NaCl on obtained quantities is noticed for apparent molar compression. • Bigger hydrophobic character of the solute results in bigger changes of calculated quantities with concentration. • The geometry of the solute is a crucial condition for hydrophobic hydration to happen. - Abstract: The present work was undertaken to study volumetric and acoustic properties for diluted solutions of tetramethylurea in pure water and for urea, n-propylurea, n-butylurea and tetramethylurea in 0.5 or 1 mol · dm −3 aqueous solutions of sodium chloride. This paper presents measured values of densities and sound velocities at T = (288.15, 298.15 and 308.15) K. From these data the apparent molar volumes, V Φ , adiabatic compressibilities, κ S , and apparent molar adiabatic compressions, K S,Φ , were obtained. The values of apparent molar volumes for infinite dilution and limited apparent adiabatic compressions were calculated from extrapolation of the concentration dependence. Further, the corresponding transfer data as well as hydration number of urea and its derivatives in the studied systems were estimated. The obtained parameters are discussed in terms of various solute-solvent and solute-cosolute interactions

  11. Dissolution of cellulose in ionic liquid: A review

    Science.gov (United States)

    Mohd, N.; Draman, S. F. S.; Salleh, M. S. N.; Yusof, N. B.

    2017-02-01

    Dissolution of cellulose with ionic liquids (IL) and deep eutectic solvent (DES) lets the comprehensive dissolution of cellulose. Basically, cellulose can be dissolved, in some hydrophilic ionic liquids, such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-allyl-3-methylimidazolium chloride (AMIMCl). Chloride based ionic liquids are suitable solvents for cellulose dissolution. Although the ILs is very useful in fine chemical industry, its application in the pharmaceutical and food industry have been very limited due to issues with toxicity, purity, and high cost. Seeing to these limitations, new green alternative solvent which is DES was used. This green solvents, may be definitely treated as the next-generation reagents for more sustainable industrial development. Thus, this review aims to discuss the dissolution of cellulose either with ionic liquids or DES and its application.

  12. Poly (ether imide sulfone) membranes from solutions in ionic liquids

    KAUST Repository

    Kim, Dooli; Nunes, Suzana Pereira

    2017-01-01

    A membrane manufacture method based on non-volatile solvents and a high performance polymer, poly (ether imide sulfone) (EXTEM™), is proposed, as greener alternative to currently industrial process. We dissolved EXTEM™ in pure ionic liquids: 1-ethyl

  13. Applications of ionic liquids in polymer science and technology

    CERN Document Server

    2015-01-01

    This book summarizes the latest knowledge in the science and technology of ionic liquids and polymers in different areas. Ionic liquids (IL) are actively being investigated in polymer science and technology for a number of different applications. In the first part of the book the authors present the particular properties of ionic liquids as speciality solvents. The state-of-the art in the use of ionic liquids in polymer synthesis and modification reactions including polymer recycling is outlined. The second part focuses on the use of ionic liquids as speciality additives such as plasticizers or antistatic agents.  The third part examines the use of ionic liquids in the design of functional polymers (usually called polymeric ionic liquids (PIL) or poly(ionic liquids)). Many important applications in diverse scientific and industrial areas rely on these polymers, like polymer electrolytes in electrochemical devices, building blocks in materials science, nanocomposites, gas membranes, innovative anion sensitive...

  14. Key Developments in Ionic Liquid Crystals

    OpenAIRE

    Fernandez, A.A.; Kouwer, P.H.J.

    2016-01-01

    Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a...

  15. Application of Alkaline Ionic Liquids in the Pretreatment Process of Eucalyptus Kraft Pulping

    Directory of Open Access Journals (Sweden)

    Yi Hou

    2016-09-01

    Full Text Available In order to explore the potential application of green solvent ionic liquids (ILs in the kraft pulping process, eucalyptus wood was pretreated by [Mmim]DMP before normal pulping. The results showed that materials pretreated shortly by the ionic liquid had a higher yield and viscosity coupled with a lower potassium permanganate value and residual lignin content in the pulp, as a result of the cooking process. It was also inferred that alkaline [Mmim]DMP pretreatment could dissolve lignin effectively from fiber to result in a stronger binding force and more entangled properties. Paper tensile and burst strength were improved by about 40% and 60%, respectively. These results provide a new way for eucalyptus to be utilized in the kraft pulping process.

  16. Application of Ionic Liquids in Hydrometallurgy

    Directory of Open Access Journals (Sweden)

    Jesik Park

    2014-08-01

    Full Text Available Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry.

  17. Solvent substitutes

    International Nuclear Information System (INIS)

    Evanoff, S.P.

    1995-01-01

    The environmental and industrial hygiene regulations promulgated since 1980, most notably the Superfund Amendments and Reauthorization Act (SARA), the Hazardous and Solid Waste Amendments to the Resources Conservation and Recovery Act (RCRA), and the Clean Air Act Amendments of 1990, have brought about an increased emphasis on user exposure, hazardous waste generation, and air emissions. As a result, industry is performing a fundamental reassessment of cleaning solvents, processes, and procedures. The more progressive organizations have made their goal the elimination of solvents that may pose significant potential human health and environmental hazards. This chapter discusses solvent cleaning in metal-finishing, metal-manufacturing, and industrial maintenance applications; precision cleaning; and electronics manufacturing. Nonmetallic cleaning, adhesives, coatings, inks, and aerosols also will be addressed, but in a more cursory manner

  18. Significant Improvement of Catalytic Efficiencies in Ionic Liquids

    International Nuclear Information System (INIS)

    Song, Choong Eui; Yoon, Mi Young; Choi, Doo Seong

    2005-01-01

    The use of ionic liquids as reaction media can confer many advantages upon catalytic reactions over reactions in organic solvents. In ionic liquids, catalysts having polar or ionic character can easily be immobilized without additional structural modification and thus the ionic solutions containing the catalyst can easily be separated from the reagents and reaction products, and then, be reused. More interestingly, switching from an organic solvent to an ionic liquid often results in a significant improvement in catalytic performance (e.g., rate acceleration, (enantio)selectivity improvement and an increase in catalyst stability). In this review, some recent interesting results which can nicely demonstrate these positive 'ionic liquid effect' on catalysis are discussed

  19. Microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid for the determination of sulfonamides in environmental water samples.

    Science.gov (United States)

    Song, Ying; Wu, Lijie; Lu, Chunmei; Li, Na; Hu, Mingzhu; Wang, Ziming

    2014-12-01

    An easy, quick, and green method, microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid, was first developed and applied to the extraction of sulfonamides in environmental water samples. 1-Ethy-3-methylimidazolium hexafluorophosphate, which is a solid-state ionic liquid at room temperature, was used as extraction solvent in the present method. After microwave irradiation for 90 s, the solid-state ionic liquid was melted into liquid phase and used to finish the extraction of the analytes. The ionic liquid and sample matrix can be separated by freezing and centrifuging. Several experimental parameters, including amount of extraction solvent, microwave power and irradiation time, pH of sample solution, and ionic strength, were investigated and optimized. Under the optimum experimental conditions, good linearity was observed in the range of 2.00-400.00 μg/L with the correlation coefficients ranging from 0.9995 to 0.9999. The limits of detection for sulfathiazole, sulfachlorpyridazine, sulfamethoxazole, and sulfaphenazole were 0.39, 0.33, 0.62, and 0.85 μg/L, respectively. When the present method was applied to the analysis of environmental water samples, the recoveries of the analytes ranged from 75.09 to 115.78% and relative standard deviations were lower than 11.89%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Metal retention in human transferrin: consequences of solvent composition in analytical sample preparation methods.

    Science.gov (United States)

    Quarles, C Derrick; Randunu, K Manoj; Brumaghim, Julia L; Marcus, R Kenneth

    2011-10-01

    The analysis of metal-binding proteins requires careful sample manipulation to ensure that the metal-protein complex remains in its native state and the metal retention is preserved during sample preparation or analysis. Chemical analysis for the metal content in proteins typically involves some type of liquid chromatography/electrophoresis separation step coupled with an atomic (i.e., inductively coupled plasma-optical emission spectroscopy or -mass spectrometry) or molecular (i.e., electrospray ionization-mass spectrometry) analysis step that requires altered-solvent introduction techniques. UV-VIS absorbance is employed here to monitor the iron content in human holo-transferrin (Tf) under various solvent conditions, changing polarity, pH, ionic strength, and the ionic and hydrophobic environment of the protein. Iron loading percentages (i.e. 100% loading equates to 2 Fe(3+):1 Tf) were quantitatively determined to evaluate the effect of solvent composition on the retention of Fe(3+) in Tf. Maximum retention of Fe(3+) was found in buffered (20 mM Tris) solutions (96 ± 1%). Exposure to organic solvents and deionized H(2)O caused release of ~23-36% of the Fe(3+) from the binding pocket(s) at physiological pH (7.4). Salt concentrations similar to separation conditions used for ion exchange had little to no effect on Fe(3+) retention in holo-Tf. Unsurprisingly, changes in ionic strength caused by additions of guanidine HCl (0-10 M) to holo-Tf resulted in unfolding of the protein and loss of Fe(3+) from Tf; however, denaturing and metal loss was found not to be an instantaneous process for additions of 1-5 M guanidinium to Tf. In contrast, complete denaturing and loss of Fe(3+) was instantaneous with ≥6 M additions of guanidinium, and denaturing and loss of iron from Tf occurred in parallel proportions. Changes to the hydrophobicity of Tf (via addition of 0-14 M urea) had less effect on denaturing and release of Fe(3+) from the Tf binding pocket compared to changes

  1. Ionic Liquid-Based Ultrasonic/Microwave-Assisted Extraction of ...

    African Journals Online (AJOL)

    Conclusion: Compared with traditional methods, IL-UMAE method uses Ionic liquid-solvent which greatly shortens the extraction time. IL-UMAE as a simple, effective and environmentally friendly approach shows a broad prospect for active ingredient extraction. Keywords: Dioscorea zingiberensis Steroidal saponins, Ionic ...

  2. Ionic Liquids and Green Chemistry: A Lab Experiment

    Science.gov (United States)

    Stark, Annegret; Ott, Denise; Kralisch, Dana; Kreisel, Guenter; Ondruschka, Bernd

    2010-01-01

    Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few investigations have actually assessed the degree of…

  3. Ionic liquids and green chemistry : a lab experiment

    NARCIS (Netherlands)

    Stark, A.; Ott-Reinhardt, D.; Kralisch, D.; Kreisel, G.; Ondruschka, B.

    2010-01-01

    Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few

  4. Synthesis and Characterization of Novel Dimeric Ionic Liquids by Conventional Approaches

    Directory of Open Access Journals (Sweden)

    Yatimah Alias

    2008-07-01

    Full Text Available The 1H-NMR shifts of the imidazolium protons of some novel dimeric ionic liquids were examined in various deuterated solvents. Interactions between the solvent and the imidazolium salt of butyl substituted ionic liquids were observed to give higher chemical shifts than methyl substitution.

  5. Ionic thermometers

    International Nuclear Information System (INIS)

    Strnad, M.

    1975-01-01

    An original method of temperature measurement based on conductivity changes near the phase transition point of ionic compounds and suitable for the range from 200 to 700 0 C according to the thermometric compound used, is given. By choosing between two approaches it is posible to evaluate either a discrete value of temperature or continuous measurement in a range to about 50 0 C below the phase transition point of thermometric compounds. The extreme nonlinearity of conductivity of the chosen group of ionic crystals used as well as the technical applications developed in the laboratories have not previously been published. The aim of the research is the application of this measuring method for temperature indication in nuclear reactors. Preliminary tests in radiation fields in an experimental reactor are yielding a real hope in this direction. (author)

  6. Ionic polarization

    International Nuclear Information System (INIS)

    Mahan, G.D.

    1992-01-01

    Ferroelectricity occurs in many different kinds of materials. Many of the technologically important solids, which are ferroelectric, can be classified as ionic. Any microscopic theory of ferroelectricity must contain a description of local polarization forces. We have collaborated in the development of a theory of ionic polarization which is quite successful. Its basic assumption is that the polarization is derived from the properties of the individual ions. We have applied this theory successfully to diverse subjects as linear and nonlinear optical response, phonon dispersion, and piezoelectricity. We have developed numerical methods using the local Density approximation to calculate the multipole polarizabilities of ions when subject to various fields. We have also developed methods of calculating the nonlinear hyperpolarizability, and showed that it can be used to explain light scattering experiments. This paper elaborates on this polarization theory

  7. Comparative study on sorption/desorption of radioeuropium on alumina, bentonite and red earth: effects of pH, ionic strength, fulvic acid, and iron oxides in red earth

    International Nuclear Information System (INIS)

    Dong Wenming; Wang Xiangke; Bian Xiaoyan; Wang Aixia; Du Jingzhou; Tao, Z.Y.

    2001-01-01

    The sorption and desorption of Eu(III) as a representative of trivalent lanthanides and actinides on bentonite, alumina, red earth and red earth treated to remove free iron oxides were comparatively investigated by using batch technique and radiotracer 152+154 Eu. The effects of pH, ionic strength, fulvic acid, iron oxides in red earth and the sorption mechanism were also discussed. As compared to alumina and red earth, Eu(III) presents a considerable distribution coefficient (K d ) onto bentonite. It was found that the pH and the presence of clay minerals are the main factors dominating the sorption/desorption characteristic of Eu 3+ in the soil, and that a sorption-desorption hysteresis on bentonite and red earth actually occurs. Furthermore, the main sorption mechanism of lanthanides onto bentonite, alumina and red earth is the formation of bridged hydroxo complexes with the surface, and there are negative effects of fulvic acid and free iron oxides in red earth on the sorption of Eu(III). The results of this paper indicate that the additivity rule on the sorption characteristic of a soil from the individual component's characteristics is not general

  8. Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology.

    Science.gov (United States)

    Brown, Leslie; Earle, Martyn J; Gîlea, Manuela A; Plechkova, Natalia V; Seddon, Kenneth R

    2017-08-10

    Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous character of ionic liquid-based solvent systems to be used in a wide variety of separations (including transition metal salts, arenes, alkenes, alkanes, bio-oils and sugars).

  9. Theory of polyelectrolytes in solvents.

    Science.gov (United States)

    Chitanvis, Shirish M

    2003-12-01

    Using a continuum description, we account for fluctuations in the ionic solvent surrounding a Gaussian, charged chain and derive an effective short-ranged potential between the charges on the chain. This potential is repulsive at short separations and attractive at longer distances. The chemical potential can be derived from this potential. When the chemical potential is positive, it leads to a meltlike state. For a vanishingly low concentration of segments, this state exhibits scaling behavior for long chains. The Flory exponent characterizing the radius of gyration for long chains is calculated to be approximately 0.63, close to the classical value obtained for second order phase transitions. For short chains, the radius of gyration varies linearly with N, the chain length, and is sensitive to the parameters in the interaction potential. The linear dependence on the chain length N indicates a stiff behavior. The chemical potential associated with this interaction changes sign, when the screening length in the ionic solvent exceeds a critical value. This leads to condensation when the chemical potential is negative. In this state, it is shown using the mean-field approximation that spherical and toroidal condensed shapes can be obtained. The thickness of the toroidal polyelectrolyte is studied as a function of the parameters of the model, such as the ionic screening length. The predictions of this theory should be amenable to experimental verification.

  10. Ionic Liquids in Biomass Processing

    Science.gov (United States)

    Tan, Suzie Su Yin; Macfarlane, Douglas R.

    Ionic liquids have been studied for their special solvent properties in a wide range of processes, including reactions involving carbohydrates such as cellulose and glucose. Biomass is a widely available and renewable resource that is likely to become an economically viable source of starting materials for chemical and fuel production, especially with the price of petroleum set to increase as supplies are diminished. Biopolymers such as cellulose, hemicellulose and lignin may be converted to useful products, either by direct functionalisation of the polymers or depolymerisation to monomers, followed by microbial or chemical conversion to useful chemicals. Major barriers to the effective conversion of biomass currently include the high crystallinity of cellulose, high reactivity of carbohydrates and lignin, insolubility of cellulose in conventional solvents, as well as heterogeneity in the native lignocellulosic materials and in lignin itself. This combination of factors often results in highly heterogeneous depolymerisation products, which make efficient separation difficult. Thus the extraction, depolymerisation and conversion of biopolymers will require novel reaction systems in order to be both economically attractive and environmentally benign. The solubility of biopolymers in ionic liquids is a major advantage of their use, allowing homogeneous reaction conditions, and this has stimulated a growing research effort in this field. This review examines current research involving the use of ionic liquids in biomass reactions, with perspectives on how it relates to green chemistry, economic viability, and conventional biomass processes.

  11. Solvent effects on extraction of aluminum(III), gallium(III), and indium(III), with decanoic acid

    International Nuclear Information System (INIS)

    Yamada, Hiromichi; Hayashi, Hisao; Fujii, Yukio; Mizuta, Masateru

    1986-01-01

    Extraction of aluminum(III) and indium(III) with decanoic acid in 1-octanol was carried out at 25 deg C and at an aqueous ionic strength of 0.1 mol dm -3 (NaClO 4 ). Monomeric and tetrameric aluminum(III) decanoates and monomeric indium(III) decanoate are responsible for the extraction. From a comparison of the present results with those obtained from the previous works, the polymerization of the extracted species was found to be more extensive in benzene than in 1-octanol, and the metal decanoates were highly polymerized in the following order in both solvents: Al > Ga > In. (author)

  12. Apparent formation constants of Pu(IV) and Th(IV) with humic acids determined by solvent extraction method

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, T.; Aoyama, S.; Yoshida, H.; Kobayashi, T.; Takagi, I. [Tokyo Univ. (Japan). Dept. of Nuclear Engineering; Kulyako, Y.; Samsonov, M.; Miyasoedov, B. [Russian Academy of Sciences, Moscow (Russian Federation). V. I. Vernadsky Institute of Geochemistry and Analytical Chemistry (GEOKHI); Moriyama, H. [Kyoto Univ. (Japan). Research Reactor Inst.

    2012-07-01

    Apparent formation constants of Pu(IV) and Th(IV) with two kinds of humic acids were determined in 0.1 M NaClO{sub 4} at 25 C using a solvent extraction method with thenoyltrifluoroacetone in xylene. The acid dissociation constants of humic acids were also measured by potentiometric titration and used as the degree of dissociation for calculating the formation constants. The effect of solution conditions, such as the pH, the initial metal and humic acid concentrations, and the ionic strength, on the formation constants was examined. The obtained data were compared with the ones in the literature. (orig.)

  13. Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology

    OpenAIRE

    Brown, Leslie; Earle, Martyn J; Gilea, Manuela; Plechkova, Natalia V; Seddon, Kenneth R

    2017-01-01

    Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous char...

  14. Use of ionic liquids as coordination ligands for organometallic catalysts

    Science.gov (United States)

    Li, Zaiwei [Moreno Valley, CA; Tang, Yongchun [Walnut, CA; Cheng,; Jihong, [Arcadia, CA

    2009-11-10

    Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

  15. Affinity of hemoglobin for the cytoplasmic fragment of human erythrocyte membrane band 3. Equilibrium measurements at physiological pH using matrix-bound proteins: the effects of ionic strength, deoxygenation and of 2,3-diphosphoglycerate.

    Science.gov (United States)

    Chétrite, G; Cassoly, R

    1985-10-05

    The cytoplasmic fragment of band 3 protein isolated from the human erythrocyte membrane was linked to a CNBr-activated Sepharose matrix in an attempt to measure, in batch experiments, its equilibrium binding constant with oxy- and deoxyhemoglobin at physiological pH and ionic strength values and in the presence or the absence of 2,3-diphosphoglycerate. All the experiments were done at pH 7.2, and equilibrium constants were computed on the basis of one hemoglobin tetramer bound per monomer of fragment. In 10 mM-phosphate buffer, a dissociation constant KD = 2 X 10(-4)M was measured for oxyhemoglobin and was shown to increase to 8 X 10(-4)M in the presence of 50 mM-NaCl. Association could not be demonstrated at higher salt concentrations. Diphosphoglycerate-stripped deoxyhemoglobin was shown to associate more strongly with the cytoplasmic fragment of band 3. In 10 mM-bis-Tris (pH 7.2) and in the presence of 120 mM-NaCl, a dissociation constant KD = 4 X 10(-4)M was measured. Upon addition of increasing amounts of 2,3-diphosphoglycerate, the complex formed between deoxyhemoglobin and the cytoplasmic fragment of band 3 was dissociated. On the reasonable assumption that the hemoglobin binding site present on band 3 fragment was not modified upon linking the protein to the Sepharose matrix, the results indicated that diphosphoglycerate-stripped deoxyhemoglobin or partially liganded hemoglobin tetramers in the T state could bind band 3 inside the intact human red blood cell.

  16. Analysis of polycyclic aromatic hydrocarbons in water and beverages using membrane-assisted solvent extraction in combination with large volume injection-gas chromatography-mass spectrometric detection.

    Science.gov (United States)

    Rodil, Rosario; Schellin, Manuela; Popp, Peter

    2007-09-07

    Membrane-assisted solvent extraction (MASE) in combination with large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was applied for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The MASE conditions were optimized for achieving high enrichment of the analytes from aqueous samples, in terms of extraction conditions (shaking speed, extraction temperature and time), extraction solvent and composition (ionic strength, sample pH and presence of organic solvent). Parameters like linearity and reproducibility of the procedure were determined. The extraction efficiency was above 65% for all the analytes and the relative standard deviation (RSD) for five consecutive extractions ranged from 6 to 18%. At optimized conditions detection limits at the ng/L level were achieved. The effectiveness of the method was tested by analyzing real samples, such as river water, apple juice, red wine and milk.

  17. Heat Effect of the Protonation of Glycine and the Enthalpies of Resolvation of Participating Chemical Species in Water-Dimethylsulfoxide Solvent Mixtures

    Science.gov (United States)

    Isaeva, V. A.; Sharnin, V. A.

    2018-02-01

    Enthalpies of the protonation of glycine in water‒dimethylsulfoxide (DMSO) mixed solvents are determined calorimetrically in the range of DMSO mole fractions of 0.0 to 0.9, at T = 298.15 K and an ionic strength μ = 0.3 (NaClO4). It is established that the protonation of glycine becomes more exothermic with an increasing mole fraction of DMSO, and the enthalpies of resolvation of glycine and glycinium ions in water‒DMSO solvent mixtures are calculated. It is shown that the small changes in the enthalpy of protonation observed at low mole fractions of DMSO are caused by the contributions from the solvation of proton and protonated glycine cancelling each other out. The enthalpy term of the Gibbs energy of the reaction leading to the formation of glycinium ion is estimated along with the enthalpy of resolvation of the reacting species in the water‒DMSO mixed solvent.

  18. Dopamine-Mediated Sclerotization of Regenerated Chitin in Ionic Liquid.

    Science.gov (United States)

    Oh, Dongyeop X; Shin, Sara; Lim, Chanoong; Hwang, Dong Soo

    2013-09-06

    Chitin is a promising structural material for biomedical applications, due to its many advantageous properties and abundance in nature. However, its usage and development in the biomedical field have been stagnant, because of chitin's poor mechanical properties in wet conditions and the difficulties in transforming it into an applicable form. To overcome these challenges, we created a novel biomimetic chitin composite. This regenerated chitin, prepared with ionic liquid, showed improved mechanical properties in wet conditions by mimicking insect cuticle and squid beak sclerotization, i.e. , catechol-meditated cross-linking. By ionic liquid-based heat treatment, dopamine oxidation produced melanin-like compounds and dopamine-meditated cross-links without any solvent evaporation and oxidant utilization. The dopamine-meditated sclerotization increased the ultimate tensile strength (UTS) of the regenerated chitin by 2.52-fold, measured after six weeks of phosphate-buffered saline (PBS) submersion. In addition, the linear swelling ratio (LSR) of the chitin film was reduced by about 22%. This strategy raises a possibility of using regenerated chitin as an artificial hard tissue in wet conditions.

  19. Dopamine-Mediated Sclerotization of Regenerated Chitin in Ionic Liquid

    Directory of Open Access Journals (Sweden)

    Dongyeop X. Oh

    2013-09-01

    Full Text Available Chitin is a promising structural material for biomedical applications, due to its many advantageous properties and abundance in nature. However, its usage and development in the biomedical field have been stagnant, because of chitin’s poor mechanical properties in wet conditions and the difficulties in transforming it into an applicable form. To overcome these challenges, we created a novel biomimetic chitin composite. This regenerated chitin, prepared with ionic liquid, showed improved mechanical properties in wet conditions by mimicking insect cuticle and squid beak sclerotization, i.e., catechol-meditated cross-linking. By ionic liquid-based heat treatment, dopamine oxidation produced melanin-like compounds and dopamine-meditated cross-links without any solvent evaporation and oxidant utilization. The dopamine-meditated sclerotization increased the ultimate tensile strength (UTS of the regenerated chitin by 2.52-fold, measured after six weeks of phosphate-buffered saline (PBS submersion. In addition, the linear swelling ratio (LSR of the chitin film was reduced by about 22%. This strategy raises a possibility of using regenerated chitin as an artificial hard tissue in wet conditions.

  20. Recent development of ionic liquid membranes

    Directory of Open Access Journals (Sweden)

    Junfeng Wang

    2016-04-01

    Full Text Available The interest in ionic liquids (IL is motivated by its unique properties, such as negligible vapor pressure, thermal stability, wide electrochemical stability window, and tunability of properties. ILs have been highlighted as solvents for liquid–liquid extraction and liquid membrane separation. To further expand its application in separation field, the ionic liquid membranes (ILMs and its separation technology have been proposed and developed rapidly. This paper is to give a comprehensive overview on the recent applications of ILMs for the separation of various compounds, including organic compounds, mixed gases, and metal ions. Firstly, ILMs was classified into supported ionic liquid membranes (SILMs and quasi-solidified ionic liquid membranes (QSILMs according to the immobilization method of ILs. Then, preparation methods of ILMs, membrane stability as well as applications of ILMs in the separation of various mixtures were reviewed. Followed this, transport mechanisms of gaseous mixtures and organic compounds were elucidated in order to better understand the separation process of ILMs. This tutorial review intends to not only offer an overview on the development of ILMs but also provide a guide for ILMs preparations and applications. Keywords: Ionic liquid membrane, Supported ionic liquid membrane, Qusai-solidified ionic liquid membrane, Stability, Application

  1. HIGH IONIC STRENGTH OR PRESENCE OF INOSITOL ...

    African Journals Online (AJOL)

    Preferred Customer

    CysG11(104)α is at the α1β1 subunit interface in both the T and R quaternary structures. It is therefore ... The static titration of guinea pig haemoglobin with DTNB has shown that the haemoglobin ..... Okonjo, K.O.; Okia, T.O. J. Protein Chem.

  2. Development of an ionic-liquid-based dispersive liquid-liquid microextraction method for the determination of antichagasic drugs in human breast milk: Optimization by central composite design.

    Science.gov (United States)

    Padró, Juan M; Pellegrino Vidal, Rocío B; Echevarria, Romina N; Califano, Alicia N; Reta, Mario R

    2015-05-01

    Chagas disease constitutes a major public health problem in Latin America. Human breast milk is a biological sample of great importance for the analysis of therapeutic drugs, as unwanted exposure through breast milk could result in pharmacological effects in the nursing infant. Thus, the goal of breast milk drug analysis is to inquire to which extent a neonate may be exposed to a drug during lactation. In this work, we developed an analytical technique to quantify benznidazole and nifurtimox (the two antichagasic drugs currently available for medical treatment) in human breast milk, with a simple sample pretreatment followed by an ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography and UV detection. For this technique, the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate has been used as the "extraction solvent." A central composite design was used to find the optimum values for the significant variables affecting the extraction process: volume of ionic liquid, volume of dispersant solvent, ionic strength, and pH. At the optimum working conditions, the average recoveries were 77.5 and 89.7%, the limits of detection were 0.06 and 0.09 μg/mL and the interday reproducibilities were 6.25 and 5.77% for benznidazole and nifurtimox, respectively. The proposed methodology can be considered sensitive, simple, robust, accurate, and green. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Active chemisorption sites in functionalized ionic liquids for carbon capture.

    Science.gov (United States)

    Cui, Guokai; Wang, Jianji; Zhang, Suojiang

    2016-07-25

    Development of novel technologies for the efficient and reversible capture of CO2 is highly desired. In the last decade, CO2 capture using ionic liquids has attracted intensive attention from both academia and industry, and has been recognized as a very promising technology. Recently, a new approach has been developed for highly efficient capture of CO2 by site-containing ionic liquids through chemical interaction. This perspective review focuses on the recent advances in the chemical absorption of CO2 using site-containing ionic liquids, such as amino-based ionic liquids, azolate ionic liquids, phenolate ionic liquids, dual-functionalized ionic liquids, pyridine-containing ionic liquids and so on. Other site-containing liquid absorbents such as amine-based solutions, switchable solvents, and functionalized ionic liquid-amine blends are also investigated. Strategies have been discussed for how to activate the existent reactive sites and develop novel reactive sites by physical and chemical methods to enhance CO2 absorption capacity and reduce absorption enthalpy. The carbon capture mechanisms of these site-containing liquid absorbents are also presented. Particular attention has been paid to the latest progress in CO2 capture in multiple-site interactions by amino-free anion-functionalized ionic liquids. In the last section, future directions and prospects for carbon capture by site-containing ionic liquids are outlined.

  4. Ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction and derivatization of sulfonamides in river water, honey, milk, and animal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xu; Su Rui; Zhao Xin; Liu Zhuang; Zhang Yupu; Li Dan; Li Xueyuan; Zhang Hanqi [College of Chemistry, Jilin University, Changchun 130012 (China); Wang Ziming, E-mail: analchem@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China)

    2011-11-30

    Graphical abstract: The extraction and derivatization efficiency of SAs is dependent on type and volume of extraction solvent, type and volume of disperser, microwave power and irradiation time, volume of derivatization reagent, pH of sample solution as well as ionic strength. Highlights: Black-Right-Pointing-Pointer A new, rapid and sensitive method for determining sulfonamides (SAs) was proposed. Black-Right-Pointing-Pointer Derivatization, extraction and preconcentration of SAs were performed in one step. Black-Right-Pointing-Pointer IL-based MADLLME and derivatization were first applied for the determination of SAs. Black-Right-Pointing-Pointer Trace SAs in river water, honey, milk, and pig plasma were determined. - Abstract: The ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction (IL-based MADLLME) and derivatization was applied for the pretreatment of six sulfonamides (SAs) prior to the determination by high-performance liquid chromatography (HPLC). By adding methanol (disperser), fluorescamine solution (derivatization reagent) and ionic liquid (extraction solvent) into sample, extraction, derivatization, and preconcentration were continuously performed. Several experimental parameters, such as the type and volume of extraction solvent, the type and volume of disperser, amount of derivatization reagent, microwave power, microwave irradiation time, pH of sample solution, and ionic strength were investigated and optimized. When the microwave power was 240 W, the analytes could be derivatized and extracted simultaneously within 90 s. The proposed method was applied to the analysis of river water, honey, milk, and pig plasma samples, and the recoveries of analytes obtained were in the range of 95.0-110.8, 95.4-106.3, 95.0-108.3, and 95.7-107.7, respectively. The relative standard deviations varied between 1.5% and 7.3% (n = 5). The results showed that the proposed method was a rapid, convenient and feasible method for the determination

  5. Ionic liquid-based microwave-assisted dispersive liquid–liquid microextraction and derivatization of sulfonamides in river water, honey, milk, and animal plasma

    International Nuclear Information System (INIS)

    Xu Xu; Su Rui; Zhao Xin; Liu Zhuang; Zhang Yupu; Li Dan; Li Xueyuan; Zhang Hanqi; Wang Ziming

    2011-01-01

    Graphical abstract: The extraction and derivatization efficiency of SAs is dependent on type and volume of extraction solvent, type and volume of disperser, microwave power and irradiation time, volume of derivatization reagent, pH of sample solution as well as ionic strength. Highlights: ► A new, rapid and sensitive method for determining sulfonamides (SAs) was proposed. ► Derivatization, extraction and preconcentration of SAs were performed in one step. ► IL-based MADLLME and derivatization were first applied for the determination of SAs. ► Trace SAs in river water, honey, milk, and pig plasma were determined. - Abstract: The ionic liquid-based microwave-assisted dispersive liquid–liquid microextraction (IL-based MADLLME) and derivatization was applied for the pretreatment of six sulfonamides (SAs) prior to the determination by high-performance liquid chromatography (HPLC). By adding methanol (disperser), fluorescamine solution (derivatization reagent) and ionic liquid (extraction solvent) into sample, extraction, derivatization, and preconcentration were continuously performed. Several experimental parameters, such as the type and volume of extraction solvent, the type and volume of disperser, amount of derivatization reagent, microwave power, microwave irradiation time, pH of sample solution, and ionic strength were investigated and optimized. When the microwave power was 240 W, the analytes could be derivatized and extracted simultaneously within 90 s. The proposed method was applied to the analysis of river water, honey, milk, and pig plasma samples, and the recoveries of analytes obtained were in the range of 95.0–110.8, 95.4–106.3, 95.0–108.3, and 95.7–107.7, respectively. The relative standard deviations varied between 1.5% and 7.3% (n = 5). The results showed that the proposed method was a rapid, convenient and feasible method for the determination of SAs in liquid samples.

  6. Thermotropic Ionic Liquid Crystals

    Science.gov (United States)

    Axenov, Kirill V.; Laschat, Sabine

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed. PMID:28879986

  7. Thermotropic Ionic Liquid Crystals.

    Science.gov (United States)

    Axenov, Kirill V; Laschat, Sabine

    2011-01-14

    The last five years' achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  8. Thermotropic Ionic Liquid Crystals

    OpenAIRE

    Axenov, Kirill V.; Laschat, Sabine

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  9. Ionic liquids for addressing unmet needs in healthcare

    Science.gov (United States)

    Agatemor, Christian; Ibsen, Kelly N.; Tanner, Eden E. L.

    2018-01-01

    Abstract Advances in the field of ionic liquids have opened new applications beyond their traditional use as solvents into other fields especially healthcare. The broad chemical space, rich with structurally diverse ions, and coupled with the flexibility to form complementary ion pairs enables task‐specific optimization at the molecular level to design ionic liquids for envisioned functions. Consequently, ionic liquids now are tailored as innovative solutions to address many problems in medicine. To date, ionic liquids have been designed to promote dissolution of poorly soluble drugs and disrupt physiological barriers to transport drugs to targeted sites. Also, their antimicrobial activity has been demonstrated and could be exploited to prevent and treat infectious diseases. Metal‐containing ionic liquids have also been designed and offer unique features due to incorporation of metals. Here, we review application‐driven investigations of ionic liquids in medicine with respect to current status and future potential. PMID:29376130

  10. Thermochemistry of ionic liquid heat-transfer fluids

    International Nuclear Information System (INIS)

    Van Valkenburg, Michael E.; Vaughn, Robert L.; Williams, Margaret; Wilkes, John S.

    2005-01-01

    Large-scale solar energy collectors intended for electric power generation require a heat-transfer fluid with a set of properties not fully met by currently available commercial materials. Ionic liquids have thermophysical and chemical properties that may be suitable for heat transfer and short heat term storage in power plants using parabolic trough solar collectors. Ionic liquids are salts that are liquid at or near room temperature. Thermal properties important for heat transfer applications are melting point, boiling point, liquidus range, heat capacity, heat of fusion, vapor pressure, and thermal conductivity. Other properties needed to evaluate the usefulness of ionic liquids are density, viscosity and chemical compatibility with certain metals. Three ionic liquids were chosen for study based on their range of solvent properties. The solvent properties correlate with solubility of water in the ionic liquids. The thermal and chemical properties listed above were measured or compiled from the literature. Contamination of the ionic liquids by impurities such as water, halides, and metal ions often affect physical properties. The ionic liquids were analyzed for those impurities, and the impact of the contamination was evaluated by standard addition. The conclusion is that the ionic liquids have some very favorable thermal properties compared to targets established by the Department of Energy for solar collector applications

  11. Electrochemical behavior of ionically crosslinked polyampholytic gel electrolytes

    International Nuclear Information System (INIS)

    Chen Wanyu; Tang Haitao; Ou Ziwei; Wang Hong; Yang Yajiang

    2007-01-01

    An ionic complex of anionic and cationic monomers was obtained by protonation of (N,N-diethylamino)ethylmethacrylate (DEA) with acrylic acid (AAc). Free radical copolymerization of the ionic complex and acrylamide (AAm), yielded the ionically crosslinked polyampholytic gel electrolytes [poly(AAc-DEA-AAm), designated as PADA] using two types of organic solvents containing a lithium salt. The PADA gel electrolyte exhibited good thermal stability shown by the DSC thermogram. The impedance analysis at temperatures ranging from -30 to 75 deg. C indicated that the ionic conductivities of the PADA gel electrolytes were rather close to those of liquid electrolytes. The temperature dependence of the ionic conductivities was found to be in accord with the Arrhenius equation. Moreover, the ionic conductivities of PADA gel electrolytes increased with an increase of the molar ratios of cationic/anionic monomers. The ionic conductivities of PADA gels prepared in solvent mixtures of propylene carbonate, ethyl methyl ether and dioxolane (3:1:1, v/v) were higher than those of PADA gels prepared in propylene carbonate only. Significantly, the ionic conductivities of two kinds of PADA gel electrolytes were in the range of 10 -3 and 10 -4 S cm -1 even at -30 deg. C. The electrochemical windows of PADA gel electrolytes measured by cyclic voltammetry were in the range from -1 V to 4.5 V

  12. Investigation of toxic effects of imidazolium ionic liquids, [bmim][BF4] and [omim][BF4], on marine mussel Mytilus galloprovincialis with or without the presence of conventional solvents, such as acetone.

    Science.gov (United States)

    Tsarpali, Vasiliki; Belavgeni, Alexia; Dailianis, Stefanos

    2015-07-01

    This study investigated the cytotoxic, oxidative and genotoxic effects of two commonly used imidazolium ionic liquids (ILs), [bmim][BF4] (1-butyl-3-methylimidazolium) and [omim][BF4] (1-methyl-3-octylimidazolium tetrafluoroborate), on the marine mussel Mytilus galloprovincialis, as well as whether acetone could mediate their toxic profile. In this context, mussels were firstly exposed to different concentrations of [bmim][BF4] or [omim][BF4], with or without the presence of acetone (at a final concentration of 0.06% v/v), for a period of 96h, in order to determine the concentration that causes 50% mussel mortality (LC50 values) in each case. Thereafter, mussels were exposed to sub- and non-lethal concentrations of ILs for investigating their ability to cause lysosomal membrane impairment (with the use of neutral red retention assay/NRRT), superoxide anion and lipid peroxidation byproduct (malondialdehyde/MDA) formation, as well as DNA damage and formation of nuclear abnormalities in hemocytes. The results showed that [omim][BF4] was more toxic than [bmim][BF4] in all cases, while the presence of acetone resulted in a slight attenuation of its toxicity. The different toxic behavior of ILs was further revealed by the significantly lower levels of NRRT values observed in [omim][BF4]-treated mussels, compared to those occurring in [bmim][BF4] in all cases. Similarly, [bmim][BF4]-mediated oxidative and genotoxic effects were observed only in the highest concentration tested (10mgL(-1)), while [omim][BF4]-mediated effects were enhanced at lower concentrations (0.01-0.05mgL(-1)). Overall, the present study showed that [bmim][BF4] and [omim][BF4] could induce not only lethal but also nonlethal effects on mussel M. galloprovincialis. The extent of [bmim][BF4] and/or [omim][BF4]-mediated effects could be ascribed to the length of each IL alkyl chain, as well as to their lipophilicity. Moreover, the role of acetone on the obtained toxic effects of the specific ILs was

  13. Green solvents and technologies for oil extraction from oilseeds.

    Science.gov (United States)

    Kumar, S P Jeevan; Prasad, S Rajendra; Banerjee, Rintu; Agarwal, Dinesh K; Kulkarni, Kalyani S; Ramesh, K V

    2017-01-01

    Oilseeds are crucial for the nutritional security of the global population. The conventional technology used for oil extraction from oilseeds is by solvent extraction. In solvent extraction, n -hexane is used as a solvent for its attributes such as simple recovery, non-polar nature, low latent heat of vaporization (330 kJ/kg) and high selectivity to solvents. However, usage of hexane as a solvent has lead to several repercussions such as air pollution, toxicity and harmfulness that prompted to look for alternative options. To circumvent the problem, green solvents could be a promising approach to replace solvent extraction. In this review, green solvents and technology like aqueous assisted enzyme extraction are better solution for oil extraction from oilseeds. Enzyme mediated extraction is eco-friendly, can obtain higher yields, cost-effective and aids in obtaining co-products without any damage. Enzyme technology has great potential for oil extraction in oilseed industry. Similarly, green solvents such as terpenes and ionic liquids have tremendous solvent properties that enable to extract the oil in eco-friendly manner. These green solvents and technologies are considered green owing to the attributes of energy reduction, eco-friendliness, non-toxicity and non-harmfulness. Hence, the review is mainly focussed on the prospects and challenges of green solvents and technology as the best option to replace the conventional methods without compromising the quality of the extracted products.

  14. Lead-Salt Quantum-Dot Ionic Liquids

    KAUST Repository

    Sun, Liangfeng

    2010-03-08

    PbS quantum dots (QDs) are functionalized using ionic liquids with thiol moieties as capping ligands. The resulting amphiphilic QD ionic liquids exhibit fluidlike behavior at room temperature, even in the absence of solvents. The photostability of the QDs is dramatically improved compared to the as-synthesized oleic acid-capped QDs dispersed in toluene. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Interfacial Structure and Double Layer Capacitance of Ionic Liquids

    NARCIS (Netherlands)

    Jitvisate, Monchai

    2018-01-01

    Ionic liquids are organic salts that are in liquid phase at room temperature. Their wide liquidus range, particularly at room temperature, results from the liquids’ large and asymmetric molecular geometry. This leads to a collection of unique properties, such as, high ionic strength, extremely low

  16. Key Developments in Ionic Liquid Crystals.

    Science.gov (United States)

    Alvarez Fernandez, Alexandra; Kouwer, Paul H J

    2016-05-16

    Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?

  17. Key Developments in Ionic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Alexandra Alvarez Fernandez

    2016-05-01

    Full Text Available Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?

  18. Investigation of toxic effects of imidazolium ionic liquids, [bmim][BF{sub 4}] and [omim][BF{sub 4}], on marine mussel Mytilus galloprovincialis with or without the presence of conventional solvents, such as acetone

    Energy Technology Data Exchange (ETDEWEB)

    Tsarpali, Vasiliki; Belavgeni, Alexia; Dailianis, Stefanos, E-mail: sdailianis@upatras.gr

    2015-07-15

    Highlights: • The toxic effects of [bmim][BF{sub 4}] and [omim][BF{sub 4}] on mussels were investigated. • Both ILs could induce lethal and nonlethal effects on Mytilus galloprovincialis. • Different extent of IL-mediated adverse effects was observed in mussel hemocytes. • The alkyl chain length and lipophilicity of ILs are crucial for their toxicity. • Acetone influences the oxidative and genotoxic effects of [omim][BF{sub 4}]. - Abstract: This study investigated the cytotoxic, oxidative and genotoxic effects of two commonly used imidazolium ionic liquids (ILs), [bmim][BF{sub 4}] (1-butyl-3-methylimidazolium) and [omim][BF{sub 4}] (1-methyl-3-octylimidazolium tetrafluoroborate), on the marine mussel Mytilus galloprovincialis, as well as whether acetone could mediate their toxic profile. In this context, mussels were firstly exposed to different concentrations of [bmim][BF{sub 4}] or [omim][BF{sub 4}], with or without the presence of acetone (at a final concentration of 0.06% v/v), for a period of 96 h, in order to determine the concentration that causes 50% mussel mortality (LC{sub 50} values) in each case. Thereafter, mussels were exposed to sub- and non-lethal concentrations of ILs for investigating their ability to cause lysosomal membrane impairment (with the use of neutral red retention assay/NRRT), superoxide anion and lipid peroxidation byproduct (malondialdehyde/MDA) formation, as well as DNA damage and formation of nuclear abnormalities in hemocytes. The results showed that [omim][BF{sub 4}] was more toxic than [bmim][BF{sub 4}] in all cases, while the presence of acetone resulted in a slight attenuation of its toxicity. The different toxic behavior of ILs was further revealed by the significantly lower levels of NRRT values observed in [omim][BF{sub 4}]-treated mussels, compared to those occurring in [bmim][BF{sub 4}] in all cases. Similarly, [bmim][BF{sub 4}]-mediated oxidative and genotoxic effects were observed only in the highest

  19. Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources.

    Science.gov (United States)

    Clark, James H; Farmer, Thomas J; Hunt, Andrew J; Sherwood, James

    2015-07-28

    The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents.

  20. Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources

    Science.gov (United States)

    Clark, James H.; Farmer, Thomas J.; Hunt, Andrew J.; Sherwood, James

    2015-01-01

    The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents. PMID:26225963

  1. Capturing CO2: conventional versus ionic-liquid based technologies

    International Nuclear Information System (INIS)

    Privalova, E I; Mäki-Arvela, P; Murzin, Dmitry Yu; Mikkhola, J P

    2012-01-01

    Since CO 2 facilitates pipeline corrosion and contributes to a decrease of the calorific value of gaseous fuels, its removal has become an issue of significant economic importance. The present review discusses various types of traditional CO 2 capture technologies in terms of their efficiency, complexity in system design, costs and environmental impact. The focus is hereby not only on conventional approaches but also on emerging 'green' solvents such as ionic liquids. The suitability of different ionic liquids as gas separation solvents is discussed in the present review and a description on their synthesis and properties in terms of CO 2 capture is provided. The bibliography includes 136 references.

  2. Acidic Ionic Liquids.

    Science.gov (United States)

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition.

  3. Fluorescent probe studies of polarity and solvation within room temperature ionic liquids: a review.

    Science.gov (United States)

    Pandey, Shubha; Baker, Sheila N; Pandey, Siddharth; Baker, Gary A

    2012-09-01

    Ionic liquids display an array of useful and sometimes unconventional, solvent features and have attracted considerable interest in the field of green chemistry for the potential they hold to significantly reduce environmental emissions. Some of these points have a bearing on the chemical reactivity of these systems and have also generated interest in the physical and theoretical aspects of solvation in ionic liquids. This review presents an introduction to the field of ionic liquids, followed by discussion of investigations into the solvation properties of neat ionic liquids or mixed systems including ionic liquids as a major or minor component. The ionic liquid based multicomponent systems discussed are composed of other solvents, other ionic liquids, carbon dioxide, surfactants or surfactant solutions. Although we clearly focus on fluorescence spectroscopy as a tool to illuminate ionic liquid systems, the issues discussed herein are of general relevance to discussions of polarity and solvent effects in ionic liquids. Transient solvation measurements carried out by means of time-resolved fluorescence measurements are particularly powerful for their ability to parameterize the kinetics of the solvation process in ionic liquids and are discussed as well.

  4. Nitropyrroles, Diels-Alder reactions assisted by microwave irradiation and solvent effect. An experimental and theoretical study

    Science.gov (United States)

    Mancini, Pedro M. E.; Kneeteman, María N.; Cainelli, Mauro; Ormachea, Carla M.; Domingo, Luis R.

    2017-11-01

    The behaviors of N-tosylnitropyrroles acting as electrophilic dienophiles in polar Diels-Alder reactions joint to different dienes of increeased nucleophilicity are analyzed. The reactions were developed under microwave irradiation using toluene or protic ionic liquids (PILs) as solvents and in free solvent conditions. In all the cases explored we observed good yields in short reaction times. For these reactions, the free solvent condition and the use of protic ionic liquids as solvents offer similar results. However, the free solvent conditions favor environmental sustainability. The role of PILs in these polar Diels-Alder reactions has been theoretically studied within the Molecular Electron Density Theory.

  5. Thermotropic Ionic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Sabine Laschat

    2011-01-01

    Full Text Available The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  6. Recent Developments in Chemical Synthesis with Biocatalysts in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Mahesh K. Potdar

    2015-09-01

    Full Text Available Over the past decade, a variety of ionic liquids have emerged as greener solvents for use in the chemical manufacturing industries. Their unique properties have attracted the interest of chemists worldwide to employ them as replacement for conventional solvents in a diverse range of chemical transformations including biotransformations. Biocatalysts are often regarded as green catalysts compared to conventional chemical catalysts in organic synthesis owing to their properties of low toxicity, biodegradability, excellent selectivity and good catalytic performance under mild reaction conditions. Similarly, a selected number of specific ionic liquids can be considered as greener solvents superior to organic solvents owing to their negligible vapor pressure, low flammability, low toxicity and ability to dissolve a wide range of organic and biological substances, including proteins. A combination of biocatalysts and ionic liquids thus appears to be a logical and promising opportunity for industrial use as an alternative to conventional organic chemistry processes employing organic solvents. This article provides an overview of recent developments in this field with special emphasis on the application of more sustainable enzyme-catalyzed reactions and separation processes employing ionic liquids, driven by advances in fundamental knowledge, process optimization and industrial deployment.

  7. Fullerol ionic fluids

    KAUST Repository

    Fernandes, Nikhil; Dallas, Panagiotis; Rodriguez, Robert; Bourlinos, Athanasios B.; Georgakilas, Vasilios; Giannelis, Emmanuel P.

    2010-01-01

    ®). The ionic fluid was compared to a control synthesized by mixing the partially protonated form (sodium form) of the fullerols with the same oligomeric amine in the same ratio as in the ionic fluids (20 wt% fullerol). In the fullerol fluid the ionic bonding

  8. A study of new anhydrous, conducting membranes based on composites of aprotic ionic liquid and cross-linked SPEEK for fuel cell application

    International Nuclear Information System (INIS)

    Malik, Rajender Singh; Verma, Pawan; Choudhary, Veena

    2015-01-01

    Highlights: • New composite membranes based on SPEEK/EG/IL were fabricated. • Composite membranes exhibit good thermal stability than neat SPEEK and XSPEEK membrane. • Proton conductivity of all composite membranes increased with temperature and amount of ionic liquid. • Proton conductivity was measured under anhydrous condition in the temperature ranging from 30–140 °C. - Abstract: The present study describe the preparation and characterisation of anhydrous proton conducting composite membranes based on sulfonated poly(ether ether ketone) [SPEEK–degree of sulfonation 70–72%]/ethylene glycol [EG]/ionic liquid by solution casting method using water: ethanol (50:50) as solvent. For this purpose several composite membranes were prepared by mixing solution of SPEEK/ethylene glycol (67:33 wt %) in water:ethanol with varying amounts of 1-butyl-3-methyl-imidazolium trifluromethanesulfonate [bmim][OTf] ionic liquid. The cross-linking of SPEEK was carried out by thermal treatment i.e. by heating in vacuum oven at 80 °C (2 h), 100 °C (2 h), 120 °C (2 h) and 135 °C for 16 h. Ethylene glycol was used as a cross-linker for SPEEK to reduce the leaching out of ionic liquid and enhance the mechanical strength of SPEEK membranes. The membranes were characterized for thermal [thermogravimetry analysis], structural [FTIR–ATR], proton conductivity, morphology (XRD, SEM) and leaching out of ionic liquid with water. FTIR studies clearly showed the interactions between SPEEK, EG and ionic liquid. The proton conductivity and dynamic mechanical properties of the composite membranes were investigated at elevated temperature and under anhydrous conditions. Proton conductivity of all the membranes measured in the temperature range of 30–140 °C under anhydrous conditions was in the range of 10 −3 Scm −1 which showed an increase with increase in temperature and amount of ionic liquid

  9. Calculation of thermodynamic properties of multicomponent ionic reciprocal systems

    International Nuclear Information System (INIS)

    Saboungi, M.

    1980-01-01

    Thermodynamic properties of multicomponent ionic reciprocal systems are derived using the conformal ionic solution theory. The equations obtained are more general than previous equations and depend solely on the properties of the components and on those of the binary subsystems. The behavior of dilute solutions is carefully studied leading to a priori predictions of solubility products in multicomponent systems. The solubility products and the specific bond free energy for making an ion pair, e.g., the pair (A--X) in the binary solvent BY--CY, are shown to depend upon specific ionic interactions in the binary subsystems. The equations presented are compared with equations derived from prior theories

  10. Imidazolium Ionic Liquid Modified Graphene Oxide: As a Reinforcing Filler and Catalyst in Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Qing Lyu

    2017-09-01

    Full Text Available Surface modification of graphene oxide (GO is one of the most important issues to produce high performance GO/epoxy composites. In this paper, the imidazole ionic liquid (IMD-Si was introduced onto the surface of GO sheets by a cheap and simple method, to prepare a reinforcing filler, as well as a catalyst in epoxy resin. The interlayer spacing of GO sheets was obviously increased by the intercalation of IMD-Si, which strongly facilitated the dispersibility of graphene oxide in organic solvents and epoxy matrix. The addition of 0.4 wt % imidazolium ionic liquid modified graphene oxide (IMD-Si@GO, yielded a 12% increase in flexural strength (141.3 MPa, a 26% increase in flexural modulus (4.69 GPa, and a 52% increase in impact strength (18.7 kJ/m2, compared to the neat epoxy. Additionally the IMD-Si@GO sheets could catalyze the curing reaction of epoxy resin-anhydride system significantly. Moreover, the improved thermal conductivities and thermal stabilities of epoxy composites filled with IMD-Si@GO were also demonstrated.

  11. Characterization and Functionality of Immidazolium Ionic Liquids Modified Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ying Li

    2013-01-01

    Full Text Available 1,3-Dialkylimidazolium-based ionic liquids were chemically synthesized and bonded on the surface of magnetic nanoparticles (MNPs with easy one-step reaction. The obtained six kinds of ionic liquid modified MNPs were characterized with transmission electron microscopy, thermogravimetric analysis, magnetization, and FTIR, which owned the high adsorption capacity due to the nanometer size and high-density modification with ionic liquids. Functionality of MNPs with ionic liquids greatly influenced the solubility of the MNPs with organic solvents depending on the alkyl chain length and the anions of the ionic liquids. Moreover, the obtained MNPs showed the specific extraction efficiency to organic pollutant, polycyclic aromatic hydrocarbons, while superparamagnetic property of the MNPs facilitated the convenient separation of MNPs from the bulks water samples.

  12. Numerical modeling of ultrasonic cavitation in ionic liquids

    Science.gov (United States)

    Calvisi, Michael L.; Elder, Ross M.

    2017-11-01

    Ionic liquids have favorable properties for sonochemistry applications in which the high temperatures and pressures achieved by cavitation bubbles are important drivers of chemical processes. Two different numerical models are presented to simulate ultrasonic cavitation in ionic liquids, each with different capabilities and physical assumptions. A model based on a compressible form of the Rayleigh-Plesset equation (RPE) simulates ultrasonic cavitation of a spherical bubble with a homogeneous interior, incorporating evaporation and condensation at the bubble surface, and temperature-varying thermodynamic properties in the interior. A second, more computationally intensive model of a spherical bubble uses the finite element method (FEM) and accounts for spatial variations in pressure and temperature throughout the flow domain. This model provides insight into heat transfer across the bubble surface and throughout the bubble interior and exterior. Parametric studies are presented for sonochemistry applications involving ionic liquids as a solvent, examining a range of realistic ionic liquid properties and initial conditions to determine their effect on temperature and pressure. Results from the two models are presented for parametric variations including viscosity, thermal conductivity, water content of the ionic liquid solvent, acoustic frequency, and initial bubble pressure. An additional study performed with the FEM model examines thermal penetration into the surrounding ionic liquid during bubble oscillation. The results suggest the prospect of tuning ionic liquid properties for specific applications.

  13. Stabilization of gold nanoparticles by 6-mercaptopurine monolayers. Effects of the solvent properties.

    Science.gov (United States)

    Viudez, Alfonso J; Madueño, Rafael; Pineda, Teresa; Blázquez, Manuel

    2006-09-14

    6-Mercaptopurine-coated gold nanoparticles (6MP-AuNPs) have been prepared by modification of the nanoparticle surface with 6MP upon displacement of the protective layer of citrate anions. The modification has been studied by UV-vis and FTIR spectroscopies. A study of the stability of these 6MP-AuNPs in aqueous solutions as a function of ionic strength and pH has shown the importance of the charges on the stabilization. The protonation of N9 of the 6MP molecules brings about a sudden flocculation phenomenon. However, the flocculation is reversible upon changing the pH to values where the molecules become newly charged. Evidence of the competence between the interaction of capping solvent molecules and the attractive forces between particles is also shown in this paper.

  14. Ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction and derivatization of sulfonamides in river water, honey, milk, and animal plasma.

    Science.gov (United States)

    Xu, Xu; Su, Rui; Zhao, Xin; Liu, Zhuang; Zhang, Yupu; Li, Dan; Li, Xueyuan; Zhang, Hanqi; Wang, Ziming

    2011-11-30

    The ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction (IL-based MADLLME) and derivatization was applied for the pretreatment of six sulfonamides (SAs) prior to the determination by high-performance liquid chromatography (HPLC). By adding methanol (disperser), fluorescamine solution (derivatization reagent) and ionic liquid (extraction solvent) into sample, extraction, derivatization, and preconcentration were continuously performed. Several experimental parameters, such as the type and volume of extraction solvent, the type and volume of disperser, amount of derivatization reagent, microwave power, microwave irradiation time, pH of sample solution, and ionic strength were investigated and optimized. When the microwave power was 240 W, the analytes could be derivatized and extracted simultaneously within 90 s. The proposed method was applied to the analysis of river water, honey, milk, and pig plasma samples, and the recoveries of analytes obtained were in the range of 95.0-110.8, 95.4-106.3, 95.0-108.3, and 95.7-107.7, respectively. The relative standard deviations varied between 1.5% and 7.3% (n=5). The results showed that the proposed method was a rapid, convenient and feasible method for the determination of SAs in liquid samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Reactions of carbon acids and 1,3-dipoles in the presence of ionic liquids

    International Nuclear Information System (INIS)

    Zlotin, Sergei G; Makhova, Nina N

    2010-01-01

    The review is devoted to the use of ionic liquids as solvents, immobilized organocatalysts and reagents in reactions involving carbon acids and 1,3-dipoles, which are widely used to prepare practically valuable organic compounds of various classes. The characteristic features of processes in the presence of ionic liquids, the effects of the structure of cations and anions on the regio-, stereo- and enantioselectivities of reactions and methods of recovery of ionic liquids are considered.

  16. Molecular interactions in the betaine monohydrate-polyol deep eutectic solvents: Experimental and computational studies

    Science.gov (United States)

    Zahrina, Ida; Mulia, Kamarza; Yanuar, Arry; Nasikin, Mohammad

    2018-04-01

    DES (deep eutectic solvents) are a new class of ionic liquids that have excellent properties. The strength of interaction between molecules in the DES affects their properties and applications. In this work, the strength of molecular interactions between components in the betaine monohydrate salt and polyol (glycerol or/and propylene glycol) eutectic mixtures was studied by experimental and computational studies. The melting point and fusion enthalpy of the mixtures were measured using STA (Simultaneous Thermal Analyzer). The nature and strength of intermolecular interactions were observed by FT-IR and NMR spectroscopy. The molecular dynamics simulation was used to determine the number of H-bonds, percent occupancy, and radial distribution functions in the eutectic mixtures. The interaction between betaine monohydrate and polyol is following order: betaine monohydrate-glycerol-propylene glycol > betaine monohydrate-glycerol > betaine monohydrate-propylene glycol, where the latter is the eutectic mixture with the lowest stability, strength and extent of the hydrogen bonding interactions between component molecules. The presence of intra-molecular hydrogen bonding interactions, the inter-molecular hydrogen bonding interactions between betaine molecule and polyol, and also interactions between polyol and H2O of betaine monohydrate in the eutectic mixtures.

  17. Dependence of the enthalpies of formation of glycylglycinate complexes of nickel(II) on the composition of a mixed water-dimethylsulfoxide solvent

    Science.gov (United States)

    Naumov, V. V.; Kovaleva, Yu. A.; Isaeva, V. A.; Usacheva, T. R.; Sharnin, V. A.

    2014-06-01

    The heat effects of the complexation reactions of nickel(II) with a glycylglycinate ion in a water-dimethylsulfoxide solvent in a range of compositions of 0.00-0.60 molar parts of dimethylsulfoxide (DMSO) (an ionic strength of 0.1 was maintained using sodium perchlorate) were determined by means of calorimetry at 298.15 K. It is established that the exothermicity of complexation reactions rises by the first two steps and falls upon the addition of a third glycylglycinate anion with an increase in the concentration of DMSO. It is shown that the formation of mono- and bis-glycylglycinate complexes of nickel(II) in a water-DMSO solvent is determined mostly by the enthalpic contribution. It is concluded that the formation of tris-ligand complexes is more associated with the entropic contribution.

  18. Solvents and solvent effects in organic chemistry

    National Research Council Canada - National Science Library

    Reichardt, C; Welton, T

    2011-01-01

    .../guest complexation equilibria and reactions in biphasic solvent systems and neoteric solvents, respectively. More than 900 new references have been added, giving preference to review articles, and many older ones have been deleted. New references either replace older ones or are added to the end of the respective reference list of each chapter. Th...

  19. Infrared spectroscopy of ionic clusters

    International Nuclear Information System (INIS)

    Price, J.M.

    1990-11-01

    This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm -1 region. The species studied include: the hydrated hydronium ions, H 3 O + (H 2 O) 3 -10 , ammoniated ammonium ions, NH 4 + (NH 3 ) 1 -10 and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH 4 + (NH 3 ) n (H 2 O) m (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs

  20. Infrared spectroscopy of ionic clusters

    Energy Technology Data Exchange (ETDEWEB)

    Price, J.M. (California Univ., Berkeley, CA (USA). Dept. of Chemistry Lawrence Berkeley Lab., CA (USA))

    1990-11-01

    This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm{sup {minus}1} region. The species studied include: the hydrated hydronium ions, H{sub 3}O{sup +} (H{sub 2}O){sub 3 {minus}10}, ammoniated ammonium ions, NH{sub 4}{sup +}(NH{sub 3}){sub 1 {minus}10} and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH{sub 4}{sup +}(NH{sub 3}){sub n}(H{sub 2}O){sub m} (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs.

  1. Synthesis of Porous Inorganic Hollow Fibers without Harmful Solvents

    NARCIS (Netherlands)

    Shukla, Sushumna; de Wit, Patrick; Luiten-Olieman, Maria W.J.; Kappert, Emiel; Nijmeijer, Arian; Benes, Nieck Edwin

    2015-01-01

    A route for the fabrication of porous inorganic hollow fibers with high surface-area-to-volume ratio that avoids harmful solvents is presented. The approach is based on bio-ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal

  2. Catalytic asymmetric dihydroxylation of olefins using a recoverable and reusable OsO(4)2- in ionic liquid [bmim][PF6].

    Science.gov (United States)

    Branco, Luís C; Afonso, Carlos A M

    2002-12-21

    The use of the solvent systems water/ionic liquid or water/ionic liquid/tert-butanol provides a recoverable, reusable, robust and simple system for the asymmetric dihydroxylation of olefins, based on the immobilization of the osmium-ligand catalyst in the ionic liquid phase.

  3. Single component, reversible ionic liquids for energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Vittoria Blasucci; Ryan Hart; Veronica Llopis Mestre; Dominique Julia Hahne; Melissa Burlager; Hillary Huttenhower; Beng Joo Reginald Thio; Pamela Pollet; Charles L. Liotta; Charles A. Eckert [Georgia Institute of Technology, Atlanta, GA (United States). Chemical & Biomolecular Engineering

    2010-06-15

    Single component, reversible ionic liquids have excellent potential as novel solvents for a variety of energy applications. Our energy industry is faced with many new challenges including increased energy consumption, depleting oil reserves, and increased environmental awareness. We report the use of reversible ionic liquids to solve two energy challenges: extraction of hydrocarbons from contaminated crude oil and carbon capture from power plant flue gas streams. Our reversible solvents are derived from silylated amine molecular liquids which react with carbon dioxide reversibly to form ionic liquids. Here we compare the properties of various silylated amine precursors and their corresponding ionic liquids. We show how the property changes are advantageous in the two aforementioned energy applications. In the case of hydrocarbon purification, we take advantage of the polarity switch between precursor and ionic liquid to enable separations. In carbon capture, our solvents act as dual physical and chemical capture agents for carbon dioxide. Finally, we show the potential economics of scale-up for both processes. 20 refs., 1 fig., 3 tabs.

  4. Thermophysical properties and solubility of different sugar-derived molecules in deep eutectic solvents

    NARCIS (Netherlands)

    Dietz, C.H.J.T.; Kroon, M.C.; van Sint Annaland, M.; Gallucci, F.

    2017-01-01

    Deep eutectic solvents (DESs) are designer solvents analogous to ionic liquids but with lower preparation cost. Most known DESs are water-miscible, but recently water-immiscible DESs have also been presented, which are a combination of hydrogen bond donors and acceptors with long hydrophobic alkyl

  5. Deep eutectic solvents for highly efficient separations in oil and gas industries

    NARCIS (Netherlands)

    Warrag, S.E.E.; Peters, C.J.; Kroon, M.C.

    2017-01-01

    Deep eutectic solvents (DESs) have captured a great scientific attention as a new, ‘green’ and sustainable class of tailor-made solvents. DESs share many properties with ionic liquids (ILs) including low vapor pressure, wide liquid range, thermal stability, low flammability, and high solvation

  6. Organic Solvent Tropical Report

    International Nuclear Information System (INIS)

    COWLEY, W.L.

    2000-01-01

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an unmitigated organic solvent fire is within risk evaluation guidelines

  7. Canyon solvent cleaning

    International Nuclear Information System (INIS)

    Reif, D.J.

    1986-01-01

    The HM Process at the Savannah River Plant (SRP) uses 7.5% tributylphosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, produce decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown the carbonate washing, although removing residual solvent activity does not remove binding ligands that hold fission products in the solvent. Treatment of solvent by an alumina adsorption process removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale alumina adsorption process and the use of the process to clean HM Process first cycle solvent are presented

  8. Solvent wash solution

    International Nuclear Information System (INIS)

    Neace, J.C.

    1986-01-01

    This patent describes a process for removing diluent degradation products from a solvent extraction solution comprising an admixture of an organic extractant for uranium and plutonium and a non-polar organic liquid diluent, which has been used to recover uranium and plutonium from spent nuclear fuel. Comprising combining a wash solution consisting of: (a) water; and (b) a positive amount up to about, an including, 50 volume percent of at least one highly-polar water-miscible organic solvent, based on the total volume of the water and the highly-polar organic solvent, with the solvent extraction solution after uranium and plutonium values have been stripped from the solvent extraction solution, the diluent degradation products dissolving in the highly-polar organic solvent and the extractant and diluent of the extraction solution not dissolving in the highly-polar organic solvent, and separating the highly-polar organic solvent and the extraction solution to obtain a purified extraction solution

  9. THE INFLUENCE OF THE SOLVENT ON THE THERMODYNAMICS OF ION ASSOCIATION

    Directory of Open Access Journals (Sweden)

    Vitalii Chumak

    2011-03-01

    Full Text Available Abstract. Some approaches which allow to divide thermodynamic functions of the ion associationprocess in two components have been developed. The first component belongs to the process, the second oneis caused by the temperature dependence of the dielectric permittivity of the solvent. The theory is confirmedby numerous examples of the ion association process of different electrolytes in the binary mixed solvents.Keywords: covalent part of the constant of ionic association, electrostatic part of the constant of ionicassociation, enthalpy of the chemical equilibria in solution, enthropy of the chemical equilibria in solution,ionic association, ionic equilibrias, the equilibrium constant.

  10. Separation of Ionic Solutes: Abstracts of the sixth international conference

    International Nuclear Information System (INIS)

    1995-05-01

    The publication has been set up as a abstracts of the international conference dealing with separation of ionic solutes. The book consists of the sections: (A) Theory of solutions and processes; (B) Solvent extraction, liquid membranes and biphasic separations; (C) Capillary electrophoresis and isotachophoresis; (D) Selective and natural sorbents; (E) Fractionation of radionuclides and metals in natural systems - transfer and speciation

  11. Ionic liquid-facilitated preparation of lignocellulosic composites

    Science.gov (United States)

    Lignocellulosic composites (LCs) were prepared by partially dissolving cotton along with steam exploded Aspen wood and burlap fabric reinforcements utilizing an ionic liquid (IL) solvent. Two methods of preparation were employed. In the first method, a controlled amount of IL was added to preassembl...

  12. Separation of Ionic Solutes: Abstracts of the sixth international conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The publication has been set up as a abstracts of the international conference dealing with separation of ionic solutes. The book consists of the sections: (A) Theory of solutions and processes; (B) Solvent extraction, liquid membranes and biphasic separations; (C) Capillary electrophoresis and isotachophoresis; (D) Selective and natural sorbents; (E) Fractionation of radionuclides and metals in natural systems - transfer and speciation.

  13. Ionic liquid performance in pilot plant contactors for aromatics extraction

    NARCIS (Netherlands)

    Onink, S.A.F.

    2011-01-01

    The main objectives of this study were an investigation into the applicability, in this case extraction capacity and equipment performance, of room temperature ionic liquids as solvent in the extraction of aromatics from aliphatics and a comparison of three types of contactors (a rotating disc

  14. Use of ionic liquids in synthesis of nanocrystals, nanorods and ...

    Indian Academy of Sciences (India)

    TECS

    chalcogen powder (Se and Te) and NaBH4 in imidazolium[BMIM]-based ionic liquids as solvents at 180–200°C. Nanorods and nanowires of Se and Te ... such as elemental chalcogens and metal chalcogenides. Nanoparticles of Rh and Ir have been ... Single crystalline Te nanotubes have been synthesized by the polyol ...

  15. Rapid, facile synthesis of conjugated polymer zwitterions in ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Page, Zachariah A. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Liu, Feng [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Russell, Thomas P. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Emrick, Todd [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA

    2014-01-01

    Ionic liquids (ILs) were utilized for the rapid air-stable Suzuki polymerization of polar zwitterionic thiophene monomers, precluding the need for volatile organic solvents, phosphine ligands and phase transfer catalysts typically used in conjugated polymer synthesis.

  16. Fullerol ionic fluids

    Science.gov (United States)

    Fernandes, Nikhil; Dallas, Panagiotis; Rodriguez, Robert; Bourlinos, Athanasios B.; Georgakilas, Vasilios; Giannelis, Emmanuel P.

    2010-09-01

    We report for the first time an ionic fluid based on hydroxylated fullerenes (fullerols). The ionic fluid was synthesized by neutralizing the fully protonated fullerol with an amine terminated polyethylene/polypropylene oxide oligomer (Jeffamine®). The ionic fluid was compared to a control synthesized by mixing the partially protonated form (sodium form) of the fullerols with the same oligomeric amine in the same ratio as in the ionic fluids (20 wt% fullerol). In the fullerol fluid the ionic bonding significantly perturbs the thermal transitions and melting/crystallization behavior of the amine. In contrast, both the normalized heat of fusion and crystallization of the amine in the control are similar to those of the neat amine consistent with a physical mixture of the fullerols/amine with minimal interactions. In addition to differences in thermal behavior, the fullerol ionic fluid exhibits a complex viscoelastic behavior intermediate between the neat Jeffamine® (liquid-like) and the control (solid-like).

  17. Activity and stability of feruloyl esterase A from Aspergillus niger in ionic liquid systems

    DEFF Research Database (Denmark)

    Zeuner, Birgitte; Riisager, Anders; Meyer, Anne S.

    in solvents that favour synthesis over hydrolysis, i.e. systems with low water content such as organic solvents or ionic liquids (ILs). The esterification of sinapic acid with glycerol catalysed by FAE A from Aspergillus niger (AnFaeA) in a series of ILs containing 15% (v/v) buffer showed that An...

  18. ALDOL- AND MANNICH-TYPE REACTIONS VIA IN SITU OLEFIN MIGRATION IN IONIC LIQUID

    Science.gov (United States)

    An aldol-type and a Mannich-type reaction via the cross-coupling of aldehydes and imines with allylic alcohols catalyzed by RuCl2(PPh3)3 was developed with ionic liquid as the solvent. The solvent/catalyst system could be reused for at least five times with no loss of reactiv...

  19. Ionic liquids in separations: applications for pyrolysis oil and emulsion systems

    NARCIS (Netherlands)

    Li, X.

    2017-01-01

    Solvent extraction is one of the main separation techniques and has been developed for a wide range of industrial applications. Ionic liquids (ILs) are often considered as environmentally friendly solvents and have been studied widely in various laboratory applications. Aiming to design effective

  20. Nanoscale Ionic Liquids

    Science.gov (United States)

    2006-11-01

    Technical Report 11 December 2005 - 30 November 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Nanoscale Ionic Liquids 5b. GRANT NUMBER FA9550-06-1-0012...Title: Nanoscale Ionic Liquids Principal Investigator: Emmanuel P. Giannelis Address: Materials Science and Engineering, Bard Hall, Cornell University...based fluids exhibit high ionic conductivity. The NFs are typically synthesized by grafting a charged, oligomeric corona onto the nanoparticle cores

  1. Hydrogen Sulfide and Ionic Liquids: Absorption, Separation, and Oxidation.

    Science.gov (United States)

    Chiappe, Cinzia; Pomelli, Christian Silvio

    2017-06-01

    Economical and environmental concerns are the main motivations for development of energy-efficient processes and new eco-friendly materials for the capture of greenhouse gases. Currently, H 2 S capture is dominated by physical and/or chemical absorption technologies, which are, however, energy intensive and often problematic from an environmental point of view due to emission of volatile solvent components. Ionic liquids have been proposed as a promising alternative to conventional solvents because of their low volatility and other interesting properties. The aim of the present review paper is to provide a detailed overview of the achievements and difficulties that have been encountered in finding suitable ionic liquids for H 2 S capture. The effect of ionic liquid anions, cations, and functional groups on the H 2 S absorption, separation, and oxidation are highlighted. Recent developments on yet scarcely available molecular simulations and on the development of robust predictive methods are also discussed.

  2. Ionic Liquids: An Environmentally Friendly Media for Nucleophilic Substitution Reactions

    International Nuclear Information System (INIS)

    Jorapur, Yogesh R.; Chi, Dae Yoon

    2006-01-01

    Ionic liquids are alternative reaction media of increasing interest and are regarded as an eco-friendly alternatives, of potential use in place of the volatile organic solvents typically used in current chemical processing methods. They are emerging as the smart and excellent solvents, which are made of positive and negative ions that they are liquids near room temperature. The nucleophilic substitution reaction is one of the important method for inserting functional groups into a carbon skeleton. Many nucleophilic substitution reactions have been found with enhanced reactivity and selectivity in ionic liquid. In this review, some recent interesting results of nucleophilic substitution reactions such as hydroxylations, ether cleavages, carbon-X (X = carbon, oxygen, nitrogen, fluorine) bond forming reactions, and ring opening of epoxides in ionic liquids are discussed

  3. Cellulose multilayer Membranes manufacture with Ionic liquid

    KAUST Repository

    Livazovic, Sara

    2015-05-09

    Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. By these methods porous supports could be easily coated with semi-crystalline cellulose. The membranes were hydrophilic with contact angles as low as 22.0°, molecular weight cut-off as low as 3000 g mol-1 with corresponding water permeance of 13.8 Lm−2 h−1 bar−1. Self-standing cellulose membranes were also manufactured without porous substrate, using only ionic liquid as green solvent. This membrane was insoluble in water, tetrahydrofuran, hexane, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and N,N-dimethylacetamide.

  4. Ionic-liquid materials for the electrochemical challenges of the future.

    Science.gov (United States)

    Armand, Michel; Endres, Frank; MacFarlane, Douglas R; Ohno, Hiroyuki; Scrosati, Bruno

    2009-08-01

    Ionic liquids are room-temperature molten salts, composed mostly of organic ions that may undergo almost unlimited structural variations. This review covers the newest aspects of ionic liquids in applications where their ion conductivity is exploited; as electrochemical solvents for metal/semiconductor electrodeposition, and as batteries and fuel cells where conventional media, organic solvents (in batteries) or water (in polymer-electrolyte-membrane fuel cells), fail. Biology and biomimetic processes in ionic liquids are also discussed. In these decidedly different materials, some enzymes show activity that is not exhibited in more traditional systems, creating huge potential for bioinspired catalysis and biofuel cells. Our goal in this review is to survey the recent key developments and issues within ionic-liquid research in these areas. As well as informing materials scientists, we hope to generate interest in the wider community and encourage others to make use of ionic liquids in tackling scientific challenges.

  5. Effect of ionic liquid on activity, stability, and structure of enzymes: a review.

    Science.gov (United States)

    Naushad, Mu; Alothman, Zied Abdullah; Khan, Abbul Bashar; Ali, Maroof

    2012-11-01

    Ionic liquids have shown their potential as a solvent media for many enzymatic reactions as well as protein preservation, because of their unusual characteristics. It is also observed that change in cation or anion alters the physiochemical properties of the ionic liquids, which in turn influence the enzymatic reactions by altering the structure, activity, enatioselectivity, and stability of the enzymes. Thus, it is utmost need of the researchers to have full understanding of these influences created by ionic liquids before choosing or developing an ionic liquid to serve as solvent media for enzymatic reaction or protein preservation. So, in the present review, we try to shed light on effects of ionic liquids chemistry on structure, stability, and activity of enzymes, which will be helpful for the researchers in various biocatalytic applications. Copyright © 2012. Published by Elsevier B.V.

  6. Ionic-liquid materials for the electrochemical challenges of the future

    Science.gov (United States)

    Armand, Michel; Endres, Frank; Macfarlane, Douglas R.; Ohno, Hiroyuki; Scrosati, Bruno

    2009-08-01

    Ionic liquids are room-temperature molten salts, composed mostly of organic ions that may undergo almost unlimited structural variations. This review covers the newest aspects of ionic liquids in applications where their ion conductivity is exploited; as electrochemical solvents for metal/semiconductor electrodeposition, and as batteries and fuel cells where conventional media, organic solvents (in batteries) or water (in polymer-electrolyte-membrane fuel cells), fail. Biology and biomimetic processes in ionic liquids are also discussed. In these decidedly different materials, some enzymes show activity that is not exhibited in more traditional systems, creating huge potential for bioinspired catalysis and biofuel cells. Our goal in this review is to survey the recent key developments and issues within ionic-liquid research in these areas. As well as informing materials scientists, we hope to generate interest in the wider community and encourage others to make use of ionic liquids in tackling scientific challenges.

  7. Effect of Organic Solvents on Microalgae Growth, Metabolism and Industrial Bioproduct Extraction: A Review.

    Science.gov (United States)

    Miazek, Krystian; Kratky, Lukas; Sulc, Radek; Jirout, Tomas; Aguedo, Mario; Richel, Aurore; Goffin, Dorothee

    2017-07-04

    In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted.

  8. Heterogeneous dynamics of ionic liquids: A four-point time correlation function approach

    Science.gov (United States)

    Liu, Jiannan; Willcox, Jon A. L.; Kim, Hyung J.

    2018-05-01

    Many ionic liquids show behavior similar to that of glassy systems, e.g., large and long-lasted deviations from Gaussian dynamics and clustering of "mobile" and "immobile" groups of ions. Herein a time-dependent four-point density correlation function—typically used to characterize glassy systems—is implemented for the ionic liquids, choline acetate, and 1-butyl-3-methylimidazolium acetate. Dynamic correlation beyond the first ionic solvation shell on the time scale of nanoseconds is found in the ionic liquids, revealing the cooperative nature of ion motions. The traditional solvent, acetonitrile, on the other hand, shows a much shorter length-scale that decays after a few picoseconds.

  9. Excimer Formation Dynamics of Dipyrenyldecane in Structurally Different Ionic Liquids.

    Science.gov (United States)

    Yadav, Anita; Pandey, Siddharth

    2017-12-07

    Ionic liquids, being composed of ions alone, may offer alternative pathways for molecular aggregation. These pathways could be controlled by the chemical structure of the cation and the anion of the ionic liquids. Intramolecular excimer formation dynamics of a bifluorophoric probe, 1,3-bis(1-pyrenyl)decane [1Py(10)1Py], where the fluorophoric pyrene moieties are separated by a long decyl chain, is investigated in seven different ionic liquids in 10-90 °C temperature range. The long alkyl separator allows for ample interaction with the solubilizing milieu prior to the formation of the excimer. The ionic liquids are composed of two sets, one having four ionic liquids of 1-butyl-3-methylimidazolium cation ([bmim + ]) with different anions and the other having four ionic liquids of bis(trifluoromethylsulfonyl)imide anion ([Tf 2 N - ]) with different cations. The excimer-to-monomer emission intensity ratio (I E /I M ) is found to increase with increasing temperature in sigmoidal fashion. Chemical structure of the ionic liquid controls the excimer formation efficiency, as I E /I M values within ionic liquids with the same viscosities are found to be significantly different. The excited-state intensity decay kinetics of 1Py(10)1Py in ionic liquids do not adhere to a simplistic Birk's scheme, where only one excimer conformer forms after excitation. The apparent rate constants of excimer formation (k a ) in highly viscous ionic liquids are an order of magnitude lower than those reported in organic solvents. In general, the higher the viscosity of the ionic liquid, the more sensitive is the k a to the temperature with higher activation energy, E a . The trend in E a is found to be similar to that for activation energy of the viscous flow (E a,η ). Stokes-Einstein relationship is not followed in [bmim + ] ionic liquids; however, with the exception of [choline][Tf 2 N], it is found to be followed in [Tf 2 N - ] ionic liquids suggesting the cyclization dynamics of 1Py(10)1Py

  10. Preparation and transport properties of novel lithium ionic liquids

    International Nuclear Information System (INIS)

    Shobukawa, Hitoshi; Tokuda, Hiroyuki; Tabata, Sei-Ichiro; Watanabe, Masayoshi

    2004-01-01

    Novel lithium salts of borates having two electron-withdrawing groups (either 1,1,1,3,3,3-hexafluoro-2-propoxy or pentafluorophenoxy group) and two methoxy-oligo(ethylene oxide) groups (number of repeating unit: n = 3, 4, 7.2) were prepared by successive substitution-reactions from LiBH 4 . The obtained lithium salts were clear and colorless liquids at room temperature. The density, thermal property, viscosity, and ionic conductivity were measured for the lithium ionic liquids. The pulsed-gradient spin-echo NMR (PGSE-NMR) method was used to independently determine self-diffusion coefficients of the lithium cation ( 7 Li NMR) and the anion ( 19 F NMR) in the bulk. The ionic conductivity of the new lithium salts was 10 -5 to 10 -4 S cm -1 at 30 deg. C, which was lower than that of typical ionic liquids by two orders of magnitude. However, the degree of self-dissociation of the lithium ionic liquids; the ratio of the molar conductivity determined by the complex impedance method to that calculated from the self-diffusion coefficients and the Nernst-Einstein equation, ranged from 0.1 to 0.4, which are comparable values to those of a highly dissociable salt in an aprotic polar solvent and of typical ionic liquids. The main reason for the meager conductivity was high viscosities of the lithium ionic liquids. It should be noted that the lithium ionic liquids have self-dissociation ability and conduct the ions in the absence of organic solvents

  11. Design of Separation Processes with Ionic Liquids

    DEFF Research Database (Denmark)

    Peng-noo, Worawit; Kulajanpeng, Kusuma; Gani, Rafiqul

    2015-01-01

    A systematic methodology for screening and designing of Ionic Liquid (IL)-based separation processes is proposed and demonstrated using several case studies of both aqueous and non-aqueous systems, for instance, ethanol + water, ethanol + hexane, benzene + hexane, and toluene + methylcyclohexane....... The best four ILs of each mixture are [mmim][dmp], [emim][bti], [emim][etso4] and [hmim][tcb], respectively. All of them were used as entrainers in the extractive distillation. A process simulation of each system was carried out and showed a lower both energy requirement and solvent usage as compared...

  12. Nanoconfinement-enhanced conformational response of single DNA molecules to changes in ionic environment

    DEFF Research Database (Denmark)

    Reisner, Walter; Beech, J. P.; Larsen, Niels Bent

    2007-01-01

    100×100 nm in dimension. Surprisingly, we find that the variation of the persistence length alone with ionic strength is not enough to explain our results. The effect is due mainly to increasing self-avoidance created by the reduced screening of electrostatic interactions at low ionic strength......We show that the ionic environment plays a critical role in determining the configurational properties of DNA confined in silica nanochannels. The extension of DNA in the nanochannels increases as the ionic strength is reduced, almost tripling over two decades in ionic strength for channels around....... To quantify the increase in self-avoidance, we introduce a new parameter into the de Gennes theory: an effective DNA width that gives the increase in the excluded volume due to electrostatic repulsion....

  13. Influence of Solvent-Solvent and Solute-Solvent Interaction Properties on Solvent-Mediated Potential

    International Nuclear Information System (INIS)

    Zhou Shiqi

    2005-01-01

    A recently proposed universal calculational recipe for solvent-mediated potential is applied to calculate excess potential of mean force between two large Lennard-Jones (LJ) or hard core attractive Yukawa particles immersed in small LJ solvent bath at supercritical state. Comparison between the present prediction with a hypernetted chain approximation adopted for solute-solute correlation at infinitely dilute limit and existing simulation data shows high accuracy for the region with large separation, and qualitative reliability for the solute particle contact region. The calculational simplicity of the present recipe allows for a detailed investigation on the effect of the solute-solvent and solvent-solvent interaction details on the excess potential of mean force. The resultant conclusion is that gathering of solvent particles near a solute particle leads to repulsive excess PMF, while depletion of solvent particles away from the solute particle leads to attractive excess PMF, and minor change of the solvent-solvent interaction range has large influence on the excess PMF.

  14. Thermodynamics of ionic processes in solutions

    International Nuclear Information System (INIS)

    Krestov, G.A.

    1984-01-01

    The present nitions about the mechanism of solvation of atomic-molecular particles and the structure of electrolyte and non electrolyte solutions are given. From common positions a wide range of interrelated problems (general and thermodynamic characteristic of ions, thermodynamic characteristic of ion solvation and various ionic reactions in solutions, structural changes of the solvent in the above processes etc...) is considered. The latest scientific data including those on the effect on the thermodynamio properties of low temperatures, various impurities (air, water), large ions, peculiarities of the structure of solvent molecules reflected. Considerable attention is given to new conceptions definitions, structural notions as well as theoretical and experimental methods of obtaining quantitative characteristics of ion solvation

  15. Ionic Liquid and Supercritical Fluid Hyphenated Techniques for Dissolution and Separation of Lanthanides, Actinides, and Fission Products

    International Nuclear Information System (INIS)

    Wai, Chien M.; Mincher, Bruce

    2012-01-01

    This project is investigating techniques involving ionic liquids (IL) and supercritical (SC) fluids for dissolution and separation of lanthanides, actinides, and fission products. The research project consists of the following tasks: Study direct dissolution of lanthanide oxides, uranium dioxide and other actinide oxides in [bmin][Tf 2 N] with TBP(HNO 3 ) 1.8 (H 2 O) 0.6 and similar types of Lewis acid-Lewis base complexing agents; Measure distributions of dissolved metal species between the IL and the sc-CO 2 phases under various temperature and pressure conditions; Investigate the chemistry of the dissolved metal species in both IL and sc-CO 2 phases using spectroscopic and chemical methods; Evaluate potential applications of the new extraction techniques for nuclear waste management and for other projects. Supercritical carbon dioxide (sc-CO 2 ) and ionic liquids are considered green solvents for chemical reactions and separations. Above the critical point, CO 2 has both gas- and liquid-like properties, making it capable of penetrating small pores of solids and dissolving organic compounds in the solid matrix. One application of sc-CO 2 extraction technology is nuclear waste management. Ionic liquids are low-melting salts composed of an organic cation and an anion of various forms, with unique properties making them attractive replacements for the volatile organic solvents traditionally used in liquid-liquid extraction processes. One type of room temperature ionic liquid (RTIL) based on the 1-alkyl-3-methylimidazolium cation [bmin] with bis(trifluoromethylsulfonyl)imide anion [Tf 2 N] is of particular interest for extraction of metal ions due to its water stability, relative low viscosity, high conductivity, and good electrochemical and thermal stability. Recent studies indicate that a coupled IL sc-CO 2 extraction system can effectively transfer trivalent lanthanide and uranyl ions from nitric acid solutions. Advantages of this technique include operation at

  16. Transition metal oxide nanopowder and ionic liquid: an efficient system for the synthesis of diorganyl selenides, selenocysteine and derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Narayanaperumal, Senthil; Gul, Kashif; Kawasoko, Cristiane Y.; Singh, Devender; Dornelles, Luciano; Rodrigues, Oscar E.D. [Universidade Federal de Santa Maria (UFSC), RS (Brazil). Dept. de Quimica. LabSelen-NanoBio; Braga, Antonio L. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica. LabSelen

    2010-07-01

    We have developed an efficient method for the synthesis of diorganyl selenides and {beta}-seleno amines using Zn, catalytic amounts of ZnO nanopowder, as a catalyst and ionic liquid as a recyclable solvent. This ZnO/ionic liquid system shows high efficiency in catalyzing these transformations with the formation of the desired products in high yields. (author)

  17. Synthesis of (3-Methoxycarbonyl)coumarin in an Ionic Liquid: An Advanced Undergraduate Project for Green Chemistry

    Science.gov (United States)

    Verdía, Pedro; Santamarta, Francisco; Tojo, Emilia

    2017-01-01

    An experiment for an undergraduate organic chemistry class based on the application of an ionic liquid as solvent and catalyst of an organic reaction is reported. The whole experiment requires three 3-h lab sessions. First, students prepare the ionic liquid dimethylimidazolium methylsulfate, which is then used as a recyclable catalyst/reaction…

  18. Thermodynamically based solvent design for enzymatic saccharide acylation with hydroxycinnamic acids in non-conventional media

    DEFF Research Database (Denmark)

    Zeuner, Birgitte; Kontogeorgis, Georgios; Riisager, Anders

    2012-01-01

    as well as other enzymatic hydroxycinnamate acylations in ionic liquid systems. The choice of solvent system is highly decisive for enzyme stability, selectivity, and reaction yields in these synthesis reactions. To increase the understanding of the reaction environment and to facilitate solvent screening......-free microemulsions of a hydrocarbon, a polar alcohol, and water are interesting solvent systems because they accommodate different substrate and product solubilities and maintain enzyme stability. Ionic liquids may provide advantages as solvents in terms of increased substrate and product solubility, higher...... of their amphiphilicity and antioxidative potential. Synthetic reactions using mono- or disaccharides as one of the substrates may moreover direct new routes for biomass upgrading in the biorefinery. The paper reviews the available data for enzymatic hydroxycinnamate saccharide ester synthesis in organic solvent systems...

  19. Ionic liquids: an x-ray reflectivity study

    International Nuclear Information System (INIS)

    Sloutskin, E.; Deutsch, M.; Tamam, L.; Ocko, B.; Kuzmenko, I.; Gog, T.

    2005-01-01

    Full Text:Ionic liquids are non-volatile, non-flammable and thermally stable solvents, and as such are promising 'green' replacements for traditional volatile organic solvents. In the last years hundreds of Ionic liquids were synthesized. Due to the Ionic liquids great industrial potential, this number is growing at an exceedingly fast rate. Despite the great importance of the interfacial properties of materials for technological applications and basic science, the atomic-scale surface structure of the Ionic liquids has never been studied previously. In our study, synchrotron x-ray reflectivity and surface tensiometry were employed to obtain the surface structure and thermodynamics of two ionic liquids, based on the 1-alkyl-3-methylimidazolium cations. A molecular layer of a density ∼18% higher than that of the bulk is found to form at the free surface of these liquids. The excess concentration of the oppositely charged ions within the surface layer is determined by chemical substitution of the anion. Finally, the observed layering at the surface is contrasted with our measurements on the behavior of classical aqueous salt solutions

  20. Novel developments in hydrogen storage, hydrogen activation and ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Doroodian, Amir

    2010-12-03

    This dissertation is divided into three chapters. Recently, metal-free hydrogen activation using phosphorous compounds has been reported in science magazine. We have investigated the interaction between hydrogen and phosphorous compounds in presence of strong Lewis acids (chapter one). A new generation of metal-free hydrogen activation, using amines and strong Lewis acids with sterically demanding nature, was already developed in our group. Shortage of high storage capacity using large substitution to improve sterical effect led us to explore the amine borane derivatives, which are explained in chapter two. Due to the high storage capacity of hydrogen in aminoborane derivatives, we have explored these materials to extend hydrogen release. These compounds store hydrogen as proton and hydride on adjacent atoms or ions. These investigations resulted in developing hydrogen storage based on ionic liquids containing methyl guanidinium cation. Then we have continued to develop ionic liquids based on methyl guanidinium cation with different anions, such as tetrafluoro borate (chapter three). We have replaced these anions with transition metal anions to investigate hydrogen bonding and catalytic activity of ionic liquids. This chapter illustrates the world of ionic liquid as a green solvent for organic, inorganic and catalytic reactions and combines the concept of catalysts and solvents based on ionic liquids. The catalytic activity is investigated particularly with respect to the interaction with CO{sub 2}. (orig.)

  1. Fabrication of Greener Membranes from Ionic Liquid Solutions

    KAUST Repository

    Kim, DooLi

    2017-06-01

    Membrane technology plays a crucial role in different separation processes such as biotechnology, pharmaceutical, and food industries, drinking water supply, and wastewater treatment. However, there is a growing concern that solvents commonly used for membrane fabrication, such as dimethylformamide (DMF), dimethylacetamide (DMAc), and 1-methyl-2-pyrrolidone (NMP), are toxic to the environment and human health. To explore the possibility of substituting these toxic solvents by less toxic or safer solvents, polymers commonly used for membrane fabrication, such as polyacrylonitrile (PAN), cellulose acetate (CA), polyethersulfone (PES), and poly(ether imide sulfone) (EXTEMTM), were dissolved in ionic liquids. Flat sheet and hollow fiber membranes were then fabricated. The thermodynamics of the polymer solutions, the kinetics of phase inversion and other factors, which resulted in significant differences in the membrane structure, compared to those of membranes fabricated from more toxic solvents, were investigated. Higher water permeance with smaller pores, unique and uniform morphologies, and narrower pore size distribution, were observed in the ionic liquid-based membranes. Furthermore, comparable performance on separation of peptides and proteins with various molecular weights was achieved with the membranes fabricated from ionic liquid solutions. In summary, we propose less hazardous polymer solutions to the environment, which can be used for the membrane fabrication with better performance and more regular morphology.

  2. Enhanced Mixed Feedstock Processing Using Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Blake A [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

    2016-10-22

    Biomass pretreatment using certain ionic liquids (ILs) is very efficient, generally producing a substrate that is amenable to saccharification with fermentable sugar yields approaching theoretical limits. Although promising, several challenges must be addressed before IL pretreatment technology becomes commercially viable. Once of the most significant challenges is the affordable and scalable recovery and recycle or the IL itself. Pervaporation is a highly selective and scalable membrane separation process for quantitatively recovering volatile solutes or solvents directly from non-volatile solvents that could prove more versatile for IL dehydration than traditional solvent extraction processes, as well as efficient and energetically more advantageous than standard evaporative techniques. In this study we evaluated a commercially available pervaporation system for IL dehydration and recycling as part of an integrated IL pretreatment process using 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) that has been proven to be very effective as a biomass pretreatment solvent. We demonstrate that >99.9 wt% [C2C1Im][OAc] can be recovered from aqueous solution and recycled at least five times. A preliminary techno-economic analysis validated the promising role of pervaporation in improving overall biorefinery process economics, especially in the case where other IL recovery technologies might lead to significant losses. These findings establish the foundation for further development of pervaporation as an effective method of recovering and recycling ILs using a commercially viable process technology.

  3. Ionic Liquids in Tribology

    Directory of Open Access Journals (Sweden)

    Ichiro Minami

    2009-06-01

    Full Text Available Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided.

  4. Ionic liquids in tribology.

    Science.gov (United States)

    Minami, Ichiro

    2009-06-24

    Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided.

  5. Photophysics of ionic biochromophores

    CERN Document Server

    Brøndsted Nielsen, Steen

    2014-01-01

    This concise guide to studying ionic biochromophores features the first integrated overview of the photophysics of differing classes of biomolecules, from single amino acids to DNA. It includes an appraisal of the latest theories and experimental techniques.

  6. Extraction of triazole fungicides in environmental waters utilizing poly (ionic liquid)-functionalized magnetic adsorbent.

    Science.gov (United States)

    Liu, Cheng; Liao, Yingmin; Huang, Xiaojia

    2017-11-17

    This work prepared a new poly (ionic liquid)-functionalized magnetic adsorbent (PFMA) for the extraction of triazole fungicides (TFs) in environmental waters prior to determination by high performance liquid chromatography/diode array detection (HPLC-DAD). A polymerizable ionic liquid, 1-methyl-3-allylimidazolium bis(trifluoromethylsulfonyl)imide was employed to copolymerize with divinylbenzene on the surface of modified magnetite to fabricate the PFMA. The morphology, spectroscopic and magnetic properties of the new adsorbent were investigated by different techniques. A series of key parameters that influence the extraction performance including the amount of PFMA, desorption solvent, adsorption and desorption time, sample pH value and ionic strength were optimized in detail. Under the optimum conditions, the prepared PFMA could extract targeted TFs effectively and quickly under the format of magnetic solid-phase extraction (MSPE). Satisfactory linearities were achieved in the range of 0.1-200.0μg/L for triadimenol and 0.05-200.0μg/L for other TFs with good coefficients of determination above 0.99 for all analytes. The limits of detection (S/N=3) and limits of quantification (S/N=10) for TFs were in the range of 0.0050-0.0078μg/L and 0.017-0.026μg/L, respectively. Environmental waters including lake, river and well waters were used to demonstrate the applicability of developed MSPE-HPLC-DAD method, and satisfactory recoveries and repeatability were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Hazardous solvent substitution

    International Nuclear Information System (INIS)

    Twitchell, K.E.

    1995-01-01

    This article is an overview of efforts at INEL to reduce the generation of hazardous wastes through the elimination of hazardous solvents. To aid in their efforts, a number of databases have been developed and will become a part of an Integrated Solvent Substitution Data System. This latter data system will be accessible through Internet

  8. Effect of solvent and temperature on the size distribution of casein micelles measured by dynamic light scattering.

    Science.gov (United States)

    Beliciu, C M; Moraru, C I

    2009-05-01

    The objectives of this study were to investigate the effect of the solvent on the accuracy of casein micelle particle size determination by dynamic light scattering (DLS) at different temperatures and to establish a clear protocol for these measurements. Dynamic light scattering analyses were performed at 6, 20, and 50 degrees C using a 90Plus Nanoparticle Size Analyzer (Brookhaven Instruments, Holtsville, NY). Raw and pasteurized skim milk were used as sources of casein micelles. Simulated milk ultrafiltrate, ultrafiltered water, and permeate obtained by ultrafiltration of skim milk using a 10-kDa cutoff membrane were used as solvents. The pH, ionic concentration, refractive index, and viscosity of all solvents were determined. The solvents were evaluated by DLS to ensure that they did not have a significant influence on the results of the particle size measurements. Experimental protocols were developed for accurate measurement of particle sizes in all solvents and experimental conditions. All measurements had good reproducibility, with coefficients of variation below 5%. Both the solvent and the temperature had a significant effect on the measured effective diameter of the casein micelles. When ultrafiltered permeate was used as a solvent, the particle size and polydispersity of casein micelles decreased as temperature increased. The effective diameter of casein micelles from raw skim milk diluted with ultrafiltered permeate was 176.4 +/- 5.3 nm at 6 degrees C, 177.4 +/- 1.9 nm at 20 degrees C, and 137.3 +/- 2.7 nm at 50 degrees C. This trend was justified by the increased strength of hydrophobic bonds with increasing temperature. Overall, the results of this study suggest that the most suitable solvent for the DLS analyses of casein micelles was casein-depleted ultrafiltered permeate. Dilution with water led to micelle dissociation, which significantly affected the DLS measurements, especially at 6 and 20 degrees C. Simulated milk ultrafiltrate seemed to give

  9. Fullerol ionic fluids

    KAUST Repository

    Fernandes, Nikhil

    2010-01-01

    We report for the first time an ionic fluid based on hydroxylated fullerenes (fullerols). The ionic fluid was synthesized by neutralizing the fully protonated fullerol with an amine terminated polyethylene/polypropylene oxide oligomer (Jeffamine®). The ionic fluid was compared to a control synthesized by mixing the partially protonated form (sodium form) of the fullerols with the same oligomeric amine in the same ratio as in the ionic fluids (20 wt% fullerol). In the fullerol fluid the ionic bonding significantly perturbs the thermal transitions and melting/crystallization behavior of the amine. In contrast, both the normalized heat of fusion and crystallization of the amine in the control are similar to those of the neat amine consistent with a physical mixture of the fullerols/amine with minimal interactions. In addition to differences in thermal behavior, the fullerol ionic fluid exhibits a complex viscoelastic behavior intermediate between the neat Jeffamine® (liquid-like) and the control (solid-like). © 2010 The Royal Society of Chemistry.

  10. Sensitivities of ionic explosives

    Science.gov (United States)

    Politzer, Peter; Lane, Pat; Murray, Jane S.

    2017-03-01

    We have investigated the relevance for ionic explosive sensitivity of three factors that have been demonstrated to be related to the sensitivities of molecular explosives. These are (1) the maximum available heat of detonation, (2) the amount of free space per molecule (or per formula unit) in the crystal lattice and (3) specific features of the electrostatic potential on the molecular or ionic surface. We find that for ionic explosives, just as for molecular ones, there is an overall tendency for impact sensitivity to increase as the maximum detonation heat release is greater. This means that the usual emphasis upon designing explosives with large heats of detonation needs to be tempered somewhat. We also show that a moderate detonation heat release does not preclude a high level of detonation performance for ionic explosives, as was already demonstrated for molecular ones. Relating the free space per formula unit to sensitivity may require a modified procedure for ionic explosives; this will continue to be investigated. Finally, an encouraging start has been made in linking impact sensitivities to the electrostatic potentials on ionic surfaces, although limited so far to ammonium salts.

  11. Aerogels from Chitosan Solutions in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Gonzalo Santos-López

    2017-12-01

    Full Text Available Chitosan aerogels conjugates the characteristics of nanostructured porous materials, i.e., extended specific surface area and nano scale porosity, with the remarkable functional properties of chitosan. Aerogels were obtained from solutions of chitosan in ionic liquids (ILs, 1-butyl-3-methylimidazolium acetate (BMIMAc, and 1-ethyl-3-methyl-imidazolium acetate (EMIMAc, in order to observe the effect of the solvent in the structural characteristics of this type of materials. The process of elaboration of aerogels comprised the formation of physical gels through anti-solvent vapor diffusion, liquid phase exchange, and supercritical CO2 drying. The aerogels maintained the chemical identity of chitosan according to Fourier transform infrared spectrophotometer (FT-IR spectroscopy, indicating the presence of their characteristic functional groups. The internal structure of the obtained aerogels appears as porous aggregated networks in microscopy images. The obtained materials have specific surface areas over 350 m2/g and can be considered mesoporous. According to swelling experiments, the chitosan aerogels could absorb between three and six times their weight of water. However, the swelling and diffusion coefficient decreased at higher temperatures. The structural characteristics of chitosan aerogels that are obtained from ionic liquids are distinctive and could be related to solvation dynamic at the initial state.

  12. Cyano-containing ionic liquids for the extraction of aromatic hydrocarbons from an aromatic/aliphatic mixture

    NARCIS (Netherlands)

    Meindersma, G.W.; Haan, de A.B.

    2012-01-01

    Ionic liquids can replace conventional solvents in aromatic/aliphatic extractions, if they have higher aromatic distribution coefficients and higher or similar aromatic/aliphatic selectivities. Also physical properties, such as density and viscosity, must be taken into account if a solvent is

  13. Notre Dame Geothermal Ionic Liquids Research: Ionic Liquids for Utilization of Geothermal Energy

    Energy Technology Data Exchange (ETDEWEB)

    Brennecke, Joan F. [Univ. of Notre Dame, IN (United States)

    2017-03-07

    The goal of this project was to develop ionic liquids for two geothermal energy related applications. The first goal was to design ionic liquids as high temperature heat transfer fluids. We identified appropriate compounds based on both experiments and molecular simulations. We synthesized the new ILs, and measured their thermal stability, measured storage density, viscosity, and thermal conductivity. We found that the most promising compounds for this application are aminopyridinium bis(trifluoromethylsulfonyl)imide based ILs. We also performed some measurements of thermal stability of IL mixtures and used molecular simulations to better understand the thermal conductivity of nanofluids (i.e., mixtures of ILs and nanoparticles). We found that the mixtures do not follow ideal mixture theories and that the addition of nanoparticles to ILs may well have a beneficial influence on the thermal and transport properties of IL-based heat transfer fluids. The second goal was to use ionic liquids in geothermally driven absorption refrigeration systems. We performed copious thermodynamic measurements and modeling of ionic liquid/water systems, including modeling of the absorption refrigeration systems and the resulting coefficients of performance. We explored some IL/organic solvent mixtures as candidates for this application, both with experimentation and molecular simulations. We found that the COPs of all of the IL/water systems were higher than the conventional system – LiBr/H2O. Thus, IL/water systems appear very attractive for absorption refrigeration applications.

  14. Redox potentials of PuO{sub 2}{sup 2+}/PuO{sub 2}{sup +} and Pu{sup 4+}/Pu{sup 3+} at different ionic strengths and temperatures; entropy and heat capacity; Potentiels Redox des couples PuO{sub 2}{sup 2+}/PuO{sub 2}{sup +} et Pu{sup 4+}/Pu{sup 3+} a force ionique et temperature variables. Entropie et capacite calorifique

    Energy Technology Data Exchange (ETDEWEB)

    Capdevila, H.; Vitorge, P.

    1994-05-01

    The reversible redox potentials of the Plutonium couples are measured by using cyclic voltammetry, in perchloric media at ionic strength, I from 0,5 M to 3M, and temperature, T, from 5 deg C to 65 deg C. At each T, experimental results, E(T,I), are extrapolated to I = O by applying the Specific Interaction Theory (S.I.T.) to get interaction coefficients, {Delta} is element of (T), and E(T,O) (e.g. standard potentials when T = 25 deg C). At T = 25 deg C the numerical values of the potentials of all the Pu couples are nearly the same. It is then not easy to detect a systematic error due to disproportionation or redox impurity. This can explain some discrepancy on numerical values already published. We finally propose ``recommended values`` of the reversible redox potentials. As a first approximation, the variations of these potentials seem to be quite linear versus temperature: entropy variation versus T is small. But taking into account heat capacity that is involved in the E(T,I) second order derivative, usually improves the fitting. A second order expansion of {epsilon}(T) and of the Debye Huckel term, D(T) are used to propose equations that account for simultaneous ionic strength and temperature influences on G, S, Cp, H, and lg K. These equations, in particular those modelling the ionic strength influence on {Delta}S, {Delta}Cp, and {Delta}H are first checked for published mean activity coefficients of HCI and NaCI. Small discrepancy between the numerical values of entropy changes of actinides redox couples, deduced from electrochemical and calorimetric techniques are discussed. (authors). 27 refs., 6 tabs., 10 figs.

  15. Radiation induced ionic polymerisation and grafting of vinyl monomers

    International Nuclear Information System (INIS)

    Stannett, V.T.

    1981-01-01

    Some special aspects of the radiation induced ionic polymerisation and grafting of vinyl monomers will be described. In particular the effects of solvents on the cationic polymerisation of the vinyl ethers will be discussed in detail. The unequivocal free ion nature of the polymerisation makes such information of considerable general interest. Estimates of the propagation rate constants with free cation polymerisation in solvents of different dielectric constants and solvation powers will be presented. Finally, some observations on the radiation induced graft polymerisation of ethyl vinyl ether to poly(vinyl chloride) and to polypropylene will be presented. (author)

  16. Canopy Dynamics in Nanoscale Ionic Materials

    KAUST Repository

    Jespersen, Michael L.

    2010-07-27

    Nanoscale ionic materials (NIMS) are organic - inorganic hybrids in which a core nanostructure is functionalized with a covalently attached corona and an ionically tethered organic canopy. NIMS are engineered to be liquids under ambient conditions in the absence of solvent and are of interest for a variety of applications. We have used nuclear magnetic resonance (NMR) relaxation and pulse-field gradient (PFG) diffusion experiments to measure the canopy dynamics of NIMS prepared from 18-nm silica cores modified by an alkylsilane monolayer possessing terminal sulfonic acid functionality, paired with an amine-terminated ethylene oxide/propylene oxide block copolymer canopy. Carbon NMR studies show that the block copolymer canopy is mobile both in the bulk and in the NIMS and that the fast (ns) dynamics are insensitive to the presence of the silica nanoparticles. Canopy diffusion in the NIMS is slowed relative to the neat canopy, but not to the degree predicted from the diffusion of hard-sphere particles. Canopy diffusion is not restricted to the surface of the nanoparticles and shows unexpected behavior upon addition of excess canopy. Taken together, these data indicate that the liquid-like behavior in NIMS is due to rapid exchange of the block copolymer canopy between the ionically modified nanoparticles. © 2010 American Chemical Society.

  17. Canopy Dynamics in Nanoscale Ionic Materials

    KAUST Repository

    Jespersen, Michael L.; Mirau, Peter A.; Meerwall, Ernst von; Vaia, Richard A.; Rodriguez, Robert; Giannelis, Emmanuel P.

    2010-01-01

    Nanoscale ionic materials (NIMS) are organic - inorganic hybrids in which a core nanostructure is functionalized with a covalently attached corona and an ionically tethered organic canopy. NIMS are engineered to be liquids under ambient conditions in the absence of solvent and are of interest for a variety of applications. We have used nuclear magnetic resonance (NMR) relaxation and pulse-field gradient (PFG) diffusion experiments to measure the canopy dynamics of NIMS prepared from 18-nm silica cores modified by an alkylsilane monolayer possessing terminal sulfonic acid functionality, paired with an amine-terminated ethylene oxide/propylene oxide block copolymer canopy. Carbon NMR studies show that the block copolymer canopy is mobile both in the bulk and in the NIMS and that the fast (ns) dynamics are insensitive to the presence of the silica nanoparticles. Canopy diffusion in the NIMS is slowed relative to the neat canopy, but not to the degree predicted from the diffusion of hard-sphere particles. Canopy diffusion is not restricted to the surface of the nanoparticles and shows unexpected behavior upon addition of excess canopy. Taken together, these data indicate that the liquid-like behavior in NIMS is due to rapid exchange of the block copolymer canopy between the ionically modified nanoparticles. © 2010 American Chemical Society.

  18. IONIC LIQUIDS MATERIAL AS MODERN CONTEXT OF CHEMISTRY IN SCHOOL

    Directory of Open Access Journals (Sweden)

    Hernani Hernani

    2016-04-01

    Full Text Available One way to improve students’ chemistry literacy which is demanded in the modernization of modern technology-based chemistry learning is by studying ionic liquids. Low level of scientific literacy of students in Indonesia as revealed in the PISA in 2012 was the main reason of the research. Ionic liquids-based technology are necessary to be applied as a context for learning chemistry because: (1 the attention of the scientific an technology community in the use of ionic liquids as a new generation of green solvent, electrolyte material and fluidic engineering in recent years becomes larger, in line with the strong demands of the industry for the provision of new materials that are reliable, safe, and friendly for various purposes; (2 scientific explanations related to the context of the ionic liquid contains a lot of facts, concepts, principles, laws, models and theories can be used to reinforce the learning content as a media to develop thinking skill (process/competence as demanded by PISA; (3 The modern technology-based ionic liquid can also be used as a discourse to strengthen scientific attitude. The process of synthesis of ionic liquid involves fairly simple organic reagents, so it deserves to be included in the chemistry subject in school.

  19. Direct current dielectrophoretic manipulation of the ionic liquid droplets in water.

    Science.gov (United States)

    Zhao, Kai; Li, Dongqing

    2018-07-13

    The ionic liquids (ILs) as the environmentally benign solvents show great potentials in microemulsion carrier systems and have been widely used in the biochemical and pharmaceutical fields. In the work, the ionic liquid-in-water microemulsions were fabricated by using two kinds of hydrophobic ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF 6 ] and 1-Hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF 6 ] with Tween 20. The ionic liquid droplets in water experience the dielectrophoretic (DEP) forces induced by applying electrical field via a nano-orifice and a micron orifice on the opposite channel walls of a microchannel. The dielectrophoretic behaviors of the ionic liquid-in-water emulsion droplets were investigated under direct current (DC) electric field. The positive and negative DEP behaviors of the ionic liquid-in-water droplets varying with the electrical conductivity of the suspending medium were investigated and two kinds of the ionic liquid droplets of similar sizes were separated by their different DEP behaviors. In addition, the separation of the ionic liquid-in-water droplets by size was conducted. This paper, for the first time to our knowledge, presents the DC-DEP manipulation of the ionic liquid-in-water emulsion droplets by size and by type. This method provides a platform to manipulate the ionic liquid droplets individually. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Solvent Composition is Critical for Carbodiimide Cross-Linking of Hyaluronic Acid as an Ophthalmic Biomaterial

    Directory of Open Access Journals (Sweden)

    Jui-Yang Lai

    2012-10-01

    Full Text Available Hyaluronic acid (HA is one of the most important ophthalmic biomaterials, while also being used for tissue engineering and drug delivery. Although chemical cross-linking is an effective way to improve the material performance, it may as a consequence be detrimental to the living cells/tissues. Given that the cross-linking efficiency is mediated by the solvent composition during the chemical modification, this study aims to explore the stability and biocompatibility of carbodiimide cross-linked HA in relation to material processing conditions by varying the acetone/water volume ratio (from 70:30 to 95:5 at a constant 1-ethyl-3-(3-dimethyl aminopropyl carbodiimide (EDC concentration of 100 mM. Our results indicated that after the EDC treatment in the presence of an acetone/water mixture (85:15, v/v, the HA hydrogel membranes have the lowest equilibrium water content, the highest stress at break and the greatest resistance to hyaluronidase digestion. Live/Dead assays and pro-inflammatory cytokine expression analyses showed that the cross-linked HA hydrogel membranes, irrespective of the solvent composition, are compatible with human RPE cell lines without causing toxicity and inflammation. However, it should be noted that the test samples prepared by the cross-linking in the presence of acetone/water mixtures containing 70, 75, and 95 vol % of acetone slightly inhibit the metabolic activity of viable ARPE-19 cultures, probably due to the alteration in the ionic interaction between the medium nutrients and polysaccharide biomaterials. In summary, the water content, mechanical strength and RPE cell proliferative capacity strongly depends on the solvent composition for carbodiimide cross-linking of HA materials.