The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Hiroyuki Ohshima - One of the best experts on this subject based on the ideXlab platform.
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Discrete charge effects on the Donnan Potential and surface Potential of a soft particle
Colloid and Polymer Science, 2013Co-Authors: Hiroyuki OhshimaAbstract:The Donnan Potential and surface Potential of soft particles (i.e., polyelectrolyte-coated hard particles) in an electrolyte solution play an essential role in their electric behaviors. These Potentials are usually derived via a continuum model in which fixed charges inside the surface layer are distributed with a continuous charge density. In this paper, for a plate-like soft particle consisting of a cubic lattice of fixed point charges, on the basis of the linearized Poisson–Boltzmann equation, we derive expressions for the electric Potential distribution in the regions inside and outside the surface layer. This expression is given in terms of a sum of the screened Coulomb Potentials produced by the point charges within the surface layer. We show that the deviation of the results of the discrete charge model from those of the continuous charge model becomes significant as the ratio of the lattice spacing to the Debye length becomes large.
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Approximate expression for the Potential energy of the double-layer interaction between two parallel ion-penetrable membranes at small separations in an electrolyte solution.
Journal of colloid and interface science, 2010Co-Authors: Hiroyuki OhshimaAbstract:Abstract An approximate expression for the Potential energy of the double-layer interaction between two parallel similar ion-penetrable membranes in a symmetrical electrolyte solution is derived via a linearization method, in which the nonlinear Poisson–Boltzmann equations in the regions inside and outside the membranes are linearized with respect to the deviation of the electric Potential from the Donnan Potential. This approximation works quite well for small membrane separations h for all values of the density of fixed charges in the membranes (or the Donnan Potential) and gives a correct limiting form of the interaction energy (or the interaction force) as h → 0.
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Theory of electrostatics and electrokinetics of soft particles
Science and technology of advanced materials, 2009Co-Authors: Hiroyuki OhshimaAbstract:We investigate theoretically the electrostatics and electrokinetics of a soft particle, i.e. a hard particle covered with an ion-penetrable surface layer of polyelectrolytes. The electric properties of soft particles in an electrolyte solution, which differ from those of hard particles, are essentially determined by the Donnan Potential in the surface layer. In particular, the Donnan Potential plays an essential role in the electrostatics and electrokinetics of soft particles. Furthermore, the concept of zeta Potential, which is important in the electrokinetics of hard particles, loses its physical meaning in the electrokinetics of soft particles. In this review, we discuss the Potential distribution around a soft particle, the electrostatic interaction between two soft particles, and the motion of a soft particle in an electric field.
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The Donnan Potential-surface Potential relationship for a cylindrical soft particle in an electrolyte solution.
Journal of colloid and interface science, 2008Co-Authors: Hiroyuki OhshimaAbstract:Transcendental equations, which avoid integration of the nonlinear Poisson-Boltzmann equations, are presented for obtaining the relationship between the Donnan Potential and surface Potential of a cylindrical soft particle (i.e., a polyelectrolyte-coated cylindrical particle) in a symmetrical electrolyte solution. Numerical results obtained by the present method are in excellent agreement with exact results obtained by solving the nonlinear cylindrical Poisson-Boltzmann equations both inside and outside the polyelectrolyte layer.
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Donnan Potential and surface Potential of a spherical soft particle in an electrolyte solution.
Journal of colloid and interface science, 2008Co-Authors: Hiroyuki OhshimaAbstract:Abstract A simple numerical method, which does not involve numerical integration of the Poisson–Boltzmann equations, is presented for obtaining the relationship between the Donnan Potential and surface Potential of a spherical soft particle (i.e., a polyelectrolyte-coated particle) in a symmetrical electrolyte solution. We assume that a soft particle consists of the particle core of radius a covered with an ion-penetrable surface layer of polyelectrolytes of thickness d and that ionized groups of valence Z are distributed at a uniform density of N in the polyelectrolyte layer and the relative permittivity takes the same value in the regions outside and inside the polyelectrolyte layer. The Donnan Potential and surface Potential are determined by the values of a , d , Z , N , and the Debye–Huckel parameter κ of the electrolyte solution. Numerical results obtained by the present method are in excellent agreement with exact results obtained by solving the nonlinear spherical Poisson–Boltzmann equations for the both regions inside and outside the polyelectrolyte layer.
Kazuo Nomura - One of the best experts on this subject based on the ideXlab platform.
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Separation of the Intramembrane Diffusion Potential and the Donnan Potential on the Basis of the Potential Transient Measurement: Application to the Analysis of Reverse Ion Permeation Driven by pH Difference
Journal of Colloid and Interface Science, 1998Co-Authors: Kazuo Nomura, Tsutomu KogaAbstract:Abstract In the perfluorocarboxylate ion exchange membrane–aqueous sodium chloride system, the diffusional flux of sodium ions against their own concentration difference was observed in the presence of a pH difference across the membrane. The internal solution contained 1 × 10−1mol dm−3NaOH and 1 × 10−1mol dm−3NaCl, and the external solution contained 2 × 10−1mol dm−3NaCl and HCl of various concentrations in the range of 1 × 10−2to 1 × 10−1mol dm−3. In these membrane systems, it was observed that the membrane Potential rapidly changed in response to a pH jump in the external side of two aqueous phases to reach an intermediate stage and then the subsequent step started to relax slowly to the final membrane Potential at the other steady state. On the basis of the assignment that the earlier fast step and subsequent slow step observed in the generation process of the membrane Potential are the generation processes of the Donnan Potential at the membrane/solution interface and the intramembrane diffusion Potential, respectively, the total membrane Potential has been divided into these two constituents. By using the observed Donnan Potential, the ion concentration at the membrane surface in the membrane was obtained. The ion flux was analyzed to obtain the diffusion coefficient of ions within the membrane by using the ion concentration at the membrane surface in the membrane and the intramembrane diffusion Potential. The pH dependence of the diffusion coefficient and that of the ion concentration at the surface in the membrane showed a break point near the apparent pKa, where the transition of the ion cluster structure in the membrane would occur.
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Separation of the Diffusion Potential within a Membrane and the Donnan Potential on the Basis of a Measurement of Transient Membrane Potentials
Bulletin of the Chemical Society of Japan, 1996Co-Authors: Kazuo NomuraAbstract:In the perfluoro carboxylate cation exchange membrane–aqueous electrolyte systems, two steps appeared in the time course of the membrane Potential in response to a pH jump in the external solution. LiCl, NaCl, and KCl were used as the electrolytes. According to the experimentally observed curve of the Potential transient, the membrane Potential was divided in two portions: the Potential difference at the membrane/solution interface (Donnan Potential) and the intramembrane diffusion Potential. It was found that the differences among the total membrane Potentials for three kinds of alkali metal ion systems were mainly attributed to the generation process of the diffusion Potential within the membrane. The pH dependencies of the Donnan Potential and intramembrane diffusion Potential were calculated on the basis of a theory starting at the Nernst–Planck equation for the ion diffusion. Calculations were carried out taking into account the association/dissociation reaction of hydrogen ions and ion exchange grou...
Vincent Ball - One of the best experts on this subject based on the ideXlab platform.
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Donnan Potential of polyelectrolyte multilayer films made from poly l glutamic polyallylamine hydrochloride and the stability of hexacyanoferrate retained in the films
Physical Chemistry Chemical Physics, 2013Co-Authors: Vincent BallAbstract:Polyelectrolyte multilayer films are a versatile surface functionalization method of solid–liquid interfaces and appear to be interesting reservoirs to load/release drugs and to act as permselective membranes. For the latter applications critical parameters are the porosity of the film and its Donnan Potential. In this investigation the Donnan Potential of PEI–(PGA–PAH)n (PEI, PGA and PAH stand for polyethyleneimine, poly-L-glutamic acid and polyallylamine) films will be determined as a function of the number of deposition steps and the concentration of the redox probe, hexacyanoferrate anions, for films made from 10 layer pairs. Complementarily, it will be shown that the retention of the redox probe in the films in the presence of 150 mM NaCl electrolyte depends on both the film thickness and the scan rates at which the electrochemical experiments are performed.
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Donnan Potential of polyelectrolyte multilayer films made from poly-L-glutamic/polyallylamine hydrochloride and the stability of hexacyanoferrate retained in the films
Physical chemistry chemical physics : PCCP, 2013Co-Authors: Vincent BallAbstract:Polyelectrolyte multilayer films are a versatile surface functionalization method of solid–liquid interfaces and appear to be interesting reservoirs to load/release drugs and to act as permselective membranes. For the latter applications critical parameters are the porosity of the film and its Donnan Potential. In this investigation the Donnan Potential of PEI–(PGA–PAH)n (PEI, PGA and PAH stand for polyethyleneimine, poly-L-glutamic acid and polyallylamine) films will be determined as a function of the number of deposition steps and the concentration of the redox probe, hexacyanoferrate anions, for films made from 10 layer pairs. Complementarily, it will be shown that the retention of the redox probe in the films in the presence of 150 mM NaCl electrolyte depends on both the film thickness and the scan rates at which the electrochemical experiments are performed.
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Large distribution in the Donnan Potential of hexacyanoferrate anions permeating in and partially dissolving (PAH-HA)n polyelectrolyte multilayer films
Soft Matter, 2011Co-Authors: Cosette Betscha, Vincent BallAbstract:We investigate herein the electrochemical behavior of hexacyanoferrate anions in polyelectrolyte multilayer (PEM) films made from poly(allylamine) (PAH) as a polycation and from hyaluronic acid (HA) as a polyanion as a function of the ionic strength and the concentration of the redox probe. Our data show that the film undergoes a partial dissolution in the presence of hexacyanoferrate in the 0.1–1 mM concentration range. The fraction of the film undergoing dissolution is however dependant on the number of deposition steps and hence on the film thickness. Upon contact with the redox probe containing solutions, for films made from 10 layer pairs, cyclic voltammogram experiments show that there are at least 3 oxidation peaks reflecting the heterogeneity of the binding sites for hexacyanoferrate anions. This constitutes the major and original finding of this work. Upon rinsing with buffer only the strongly bound anions remain in the film and in the presence of 0.05 M supporting electrolyte, the amount of hexacyanoferrate retained in the film is almost independent of its solution concentration, reflecting a high affinity binding isotherm. The hexacyanoferrate containing (PLL-HA)10 films display also a markedly different surface morphology and roughness with respect to the pristine films. The distribution in the Donnan Potential of the redox probes and the partial but almost concentration independent film dissolution point to a large heterogeneity in the binding sites of ferrocyanide with the HA-PAH matrix. This heterogeneity as well as the partial film dissolution can be totally suppressed upon exposure of the film to a carbodiimide/N-hydroxysulfosuccinimide containing solution, allowing for the formation of amide bonds between the amino groups of PAH and the carboxylates of HA. We rationalize all our findings in the framework of the 3 zone model of PEM films.
O. V. Bobreshova - One of the best experts on this subject based on the ideXlab platform.
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Hybrid Materials Based on MF-4SC Membranes and Carbon Nanotubes: Transport Properties and Characteristics of DP-sensors in Hydrophobic Amino Acid Solutions
Membranes and Membrane Technologies, 2019Co-Authors: A. V. Parshina, O. V. Bobreshova, T. S. Titova, E. Yu. Safronova, D. D. Evdokimova, I. A. Prikhno, A. B. YaroslavtsevAbstract:Perfluorinated sulfonated cation-exchange membranes MF-4SC containing 0.5–3.0% of carbon nanotubes (CNTs) have been synthesized. A correlation between the water uptake and transport properties of the membranes in the K^+-form and the sensitivity of DP-sensors (with the analytical signal in the form of a Donnan Potential) to the analyte and interfering ions in solutions of hydrophobic amino acids (alanine, valine, and phenylalanine) has been found. Hybrid membrane samples that provide the highest sensitivity of DP-sensors to amino acid cations and zwitterions and the lowest sensitivity to hydroxonium ions at pH < 7 in a concentration range of 1.0 × 10^–4–1.0 × 10^–1 M have been selected. Membrane modification has led to a decrease in the relative error and the relative standard deviation in the determination of amino acid ions by a factor of 3 and 1.5, respectively.
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Donnan-Potential Sensors Based on Zirconia-Modified Nafion Membranes Treated under Different Conditions for the Determination of Amino Acids with Several Nitrogen-Containing Groups
Petroleum Chemistry, 2017Co-Authors: E. Yu. Safronova, O. V. Bobreshova, A. V. Parshina, E. A. Ryzhkova, D. V. Safronov, A. B. YaroslavtsevAbstract:The effect of heat treatment at varying relative humidity and mechanical deformation on the properties of Nafion perfluorosulfonic cation-exchange membranes and Nafion-based hybrid materials containing hydrated zirconia nanoparticles has been studied. It has been shown that the treatment of the materials makes it possible to change their water uptake, ionic conductivity, and diffusion permeability over wide ranges. Variations in the water uptake and intrapore space volume of the membranes provided by their treatment and modification have led to a decrease in the sensitivity of DP-sensors (the analytical signal is the Donnan Potential) to interfering hydroxonium cations in arginine and histidine solutions in 1.5−5 times. The material samples providing a high accuracy of determination of amino acid ions in a concentration range from 1.0 × 10–4 to 1.0 × 10–1 mol/L at pH < 7 have been selected.
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Determination of glycine, alanine, and leucine at different solution ph with the aid of Donnan Potential sensors based on hybrid membranes
Journal of Analytical Chemistry, 2016Co-Authors: A. V. Parshina, O. V. Bobreshova, T. S. Titova, E. Yu. Safronova, A. B. YaroslavtsevAbstract:The cross sensitive sensors whose analytical signal is the Donnan Potential (PD-sensors) were developed for the determination of the amino acids glycine, alanine, and leucine in acidic and alkaline solutions. Hybrid materials based on perfluorinated sulfo cation-exchange membranes Nafion and MF-4SC with incorporated zirconium dioxide and silicon dioxide nanoparticles, including those with modified surfaces containing proton-acceptor groups, were used in the PD-sensors. The sensitivity of the PD-sensors to hydronium ions, which interfere with the determination of amino acids at pH 7 and the smallest sensitivity to the cations K+ were observed in hybrid membranes, which combined an increased rate of anion transfer and a low moisture capacity. The use of the PD-sensors based on hybrid membranes makes it possible to determine the cations, anions, and zwitterions of amino acids over a wide range of pH with a sufficiently high accuracy.
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Effect of the treatment of MF-4SC membranes on the cross sensitivity of Donnan Potential sensors to cations in the aqueous solutions of organic ampholytes
Mendeleev Communications, 2016Co-Authors: A. V. Parshina, O. V. Bobreshova, E. A. Ryzhkova, Ekaterina Yu. Safronova, Seraphim S. Chertov, D. V. Safronov, Andrey B. YaroslavtsevAbstract:Methods of directional variation of properties of perfluorinated sulfo cation-exchange membranes were proposed based on the use of the effect of ‘memory’ to changes in their structure under the influence of external factors (heat treatment at various humidity or mechanical effect). The relationship between water uptake, transport properties of MF-4SC membranes, and sensitivity of Donnan Potential (DP) sensors to the determined organic cations and interferent hydronium ions was established. Lowering sensitivity of DP-sensors to the interferent hydronium ions at a decrease in diffusion permeability and increase in conductivity of the membranes was reached.
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Potentiometric determination of glycine, alanine, and leucine anions and potassium cations in alkaline solutions using zirconia-modified nafion and MF-4SC membranes
Petroleum Chemistry, 2015Co-Authors: O. V. Bobreshova, A. V. Parshina, T. S. Titova, E. Yu. Safronova, A. B. YaroslavtsevAbstract:Cross sensitivity of potentiometric PD-sensors (sensors whose signal is Donnan Potential) based on MF-4SC and Nafion cation-exchange membranes containing hydrated ZrO_2 nanoparticles to amino acid (glycine, alanine, and leucine) ions in alkaline solutions has been investigated. By varying ZrO_2 concentrations, it is possible to select pairs of PD-sensors that have a sufficiently high sensitivity to the amino acid anions and K^+ cations in Gly + KOH, β-Ala + KOH, and Leu + KOH solutions, as well as the lowest correlation between responses of sensors. The pairs of PD-sensors were used for simultaneous determination of amino acid anions and K^+ cations in alkaline solutions.
Tsutomu Koga - One of the best experts on this subject based on the ideXlab platform.
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Separation of the Intramembrane Diffusion Potential and the Donnan Potential on the Basis of the Potential Transient Measurement: Application to the Analysis of Reverse Ion Permeation Driven by pH Difference
Journal of Colloid and Interface Science, 1998Co-Authors: Kazuo Nomura, Tsutomu KogaAbstract:Abstract In the perfluorocarboxylate ion exchange membrane–aqueous sodium chloride system, the diffusional flux of sodium ions against their own concentration difference was observed in the presence of a pH difference across the membrane. The internal solution contained 1 × 10−1mol dm−3NaOH and 1 × 10−1mol dm−3NaCl, and the external solution contained 2 × 10−1mol dm−3NaCl and HCl of various concentrations in the range of 1 × 10−2to 1 × 10−1mol dm−3. In these membrane systems, it was observed that the membrane Potential rapidly changed in response to a pH jump in the external side of two aqueous phases to reach an intermediate stage and then the subsequent step started to relax slowly to the final membrane Potential at the other steady state. On the basis of the assignment that the earlier fast step and subsequent slow step observed in the generation process of the membrane Potential are the generation processes of the Donnan Potential at the membrane/solution interface and the intramembrane diffusion Potential, respectively, the total membrane Potential has been divided into these two constituents. By using the observed Donnan Potential, the ion concentration at the membrane surface in the membrane was obtained. The ion flux was analyzed to obtain the diffusion coefficient of ions within the membrane by using the ion concentration at the membrane surface in the membrane and the intramembrane diffusion Potential. The pH dependence of the diffusion coefficient and that of the ion concentration at the surface in the membrane showed a break point near the apparent pKa, where the transition of the ion cluster structure in the membrane would occur.