Effect of chemical modification of ion-exchange membrane MA-40 on its electrochemical characteristics

Lopatkova, G. Yu.; Volodina, E. I.; Pismenskaya, Natalia; Fedotov, Yu. А.; Cot, Didier; Nikonenko, Victor

doi:10.1134/s1023193506080064

Cited by 20 publications

(12 citation statements)

References 9 publications

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“…At the same time, on modified membrane MA 40M, virtually no gener ation of Н + and ОН -ions occurs (the transport num ber of ОН -ions reaches 0.1 only for high disk rotation rates (500 rpm) and high voltages Δϕ > 8 V). The low catalytic activity of membrane MA 40M was observed [9] in an electrodialysis cell with a smooth channel formed by membranes MK 40 and MA 40M.…”

Section: Methodsmentioning

confidence: 90%

“…Using the model of the overlimiting state of electromembrane systems [7], the decrease in the water dissociation rate in a membrane was associated with the decrease in the space charge region size and weakening of the electric field at the membrane/solution interface. A decrease in the water dissociation rate can also be achieved by replacing ion ogenenic groups in a thin surface layer by equipolar groups with lower catalytic activity [8,9].…”

Section: Introductionmentioning

confidence: 99%

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Transfer of electrolyte ions and water dissociation in anion-exchange membranes under intense current conditions

et al. 2012

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Polarization characteristics of electromembrane systems (EMS) based on the Russian commer cial heterogeneous membranes MA 40 and MA 41, the anion exchange heterogeneous membrane AMH (Mega, Czech Republic), and the modified membrane MA 40M are studied by the method of rotating mem brane disk in dilute sodium chloride solutions. The effective transport numbers of ions are found; the partial voltammetric characteristics (VAC) with respect to chloride and hydroxyl ions are measured; the limiting cur rent densities are calculated as a function of the membrane disk rotation rate. In terms of the theory of the overlimiting state of EMS, based on experimental VAC and the dependences of the effective transport num bers on the current density, the following internal parameters of systems under study are calculated: the space charge and electric field strength distribution over the diffusion layer and the membrane. It is shown that water dissociation can be virtually completely eliminated by substituting chemically stable quaternary ammo nium groups inert with respect to water dissociation in the surface layer of a heterogeneous anion exchange membrane MA 40 for the active ternary and secondary functional amino groups. The maximum electric field strength values at the membrane/solution interface, which were found in the framework of the theory of over limiting state, turned out to be close for all anion exchange membranes studied, namely, (7-9) × 10 6 V/cm. This suggests that it is the nature of ionogenic groups in the surface layer rather than the field effect that plays the decisive role in the membrane ability to accelerate the water dissociation reaction. It is proved experimen tally that in highly intense current modes of the electrodialysis process, the thermal hydrolysis of quaternary ammonium bases occurs in strongly basic MA 41 and AMH membranes by the Hofmann reaction to form ternary amino groups catalytically active in water dissociation reaction. Based on the concept on the catalytic mechanism of water dissociation, the fraction of ternary amino groups formed by thermal hydrolysis in the surface layer (the space charge region) of monopolar anion exchange membranes MA 41 and AMH is assessed quantitatively as 0.7 and 6.5%, respectively.

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Section: Methodsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Transfer of electrolyte ions and water dissociation in anion-exchange membranes under intense current conditions

et al. 2012

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“…The inten sity of H + , OH -ion generation at anion exchange membranes can be lowered by treating their surfaces with bifunctional polyelectrolytes containing a num ber of carboxyl groups and aliphatic chains with qua ternary ammonium bases, as it was shown by example of the membrane MA 40, a commercial product of OAO Shchekinoazot [87][88][89]. In Figs.…”

Section: Control Of Limiting and Overlimiting Mass Transfer By The Mementioning

confidence: 98%

Effect of the ion-exchange-membrane/solution interfacial characteristics on the mass transfer at severe current regimes

et al. 2012

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In the electrodialysis of dilute solutions, performed at intense current regimes, the membrane electrical conductance and diffusion permeability are no more crucial. Of more importance become the membrane properties that control increase in the overlimiting mass transfer of salt ions, as well as H + and OH -ions in membrane systems. In this work different methods of the improving of mass exchange charac teristics of commercial ion exchange membranes intended for operation at intense current regimes are dis cussed. They are based on modern concepts of mechanisms of the electroconvection (which proceeds as elec troosmosis of 2nd kind), as well as mechanisms of H + and OH -ions generation at the membrane/solution interface. Influence on the membrane electrochemical and mass exchange characteristics is possible via (a) control of chemical nature of fixed groups at membrane surfaces, in order to weaken their catalytic activity with respect to water dissociation reaction, (b) increase in the surface hydrophobicity, and (c) design of elec trical inhomogeneity of the membrane/solution interface; the purpose is the facilitating of intense develop ment of electrical convection.

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“…The use of a polyelectrolyte as a modifier is reported as an effective way to improve the electrochemical properties of heterogeneous IEMs . The modification leads to enrichment of fixed charge density, improvement of electrical conductivity, reduction of water dissociation rate, and enhanced current efficiency.…”

Section: Surface‐modified Ion‐exchange Membranesmentioning

confidence: 99%

Surface modification of ion‐exchange membranes: Methods, characteristics, and performance

Khoiruddin

Ariono

Subagjo

et al. 2017

J of Applied Polymer Sci

109

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Considerable effort has been made to improve ion-exchange membrane (IEM) properties in order to achieve better performance of IEM-based processes in various applications. Surface modification is one of the effective ways to improve IEM properties. Various methods have been used to modify IEM surfaces, for example, plasma treatment, polymerization, solution casting, electrodeposition, and ion implantation. These methods are able to produce a thin and fine distributed layer and also to modify the chemical structure of the surface. The new layer can be adsorbed, deposited, or chemically bonded on a membrane surface. By using these methods, IEM properties are improved, and the desired or specific characteristics such as high monovalent ion permselectivity, low fuel crossover, and anti-organic-fouling property can be obtained. In this paper, methods for surface modification of IEMs are reviewed. Moreover, the effects of modification on IEM properties and performance are discussed.

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Effect of chemical modification of ion-exchange membrane MA-40 on its electrochemical characteristics

Cited by 20 publications

References 9 publications

Transfer of electrolyte ions and water dissociation in anion-exchange membranes under intense current conditions

Transfer of electrolyte ions and water dissociation in anion-exchange membranes under intense current conditions

Effect of the ion-exchange-membrane/solution interfacial characteristics on the mass transfer at severe current regimes

Surface modification of ion‐exchange membranes: Methods, characteristics, and performance

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