Generation of H+ and OH− ions in anion-exchange membrane/ampholyte-containing solution systems: A study using electrochemical impedance spectroscopy

Pismenskaya, Natalia; Rybalkina, Olesya; Kozmai, Anton; Tsygurina, Kseniia; Melnikova, Ekaterina; Nikonenko, Victor

doi:10.1016/j.memsci.2020.117920

Cited by 29 publications

(42 citation statements)

References 75 publications

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“…It corresponds to a state in which the AEM is almost completely saturated with doubly charged anions; the maximum rate of proton generation is achieved by the AD mechanism, and there are no other sources of increasing the electric charge carried by ions. According to estimates made previously [67], in the case of a NaH 2 PO 4 solution, the kinetic rate of proton generation by the AD mechanism is limited due to a low rate constant of phosphoric acid dissociation in the 3rd step (Table S2 in Supplementary Materials); tartaric acid does not have the 3rd dissociation step. An increase in i lim 1 exp and i lim 2 exp in comparison with theoretical values (Table 3) is caused by the exaltation of the limiting current [66].…”

Section: Current-voltage Curvesmentioning

confidence: 94%

“…This mechanism, which for brevity can be denoted as "acid dissociation" (AD), takes place under any current mode. Enhancing the proton current is controlled by the reaction rate constants, which limit the dissociation of the acid at stages 1, 2, and 3 [67], and the ion-exchange capacity of the membrane, IEC. The ion-exchange capacity controls the Donnan exclusion of coions (protons) [68] and limits the number of multiply charged anions that can participate in the transfer of electric charge in the membrane.…”

Section: Background: Proton Generation In Aem/ampholyte Solution Systemsmentioning

confidence: 99%

“…The minimum values of the proton transport numbers in the near-membrane NaCl solution are explained by the fact that only water splitting is a source of protons. Both the WS and AD mechanisms can occur simultaneously [67] in overlimiting current modes in the case of polybasic acid salt solutions (Figure 3b).…”

Section: Background: Proton Generation In Aem/ampholyte Solution Systemsmentioning

confidence: 99%

See 2 more Smart Citations

Influence of Electroconvection on Chronopotentiograms of an Anion-Exchange Membrane in Solutions of Weak Polybasic Acid Salts

Pismenskaya

Rybalkina

Moroz

et al. 2021

IJMS

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Visualization of electroconvective (EC) vortices at the undulated surface of an AMX anion-exchange membrane (Astom, Osaka, Japan) was carried out in parallel with the measurement of chronopotentiograms. Weak polybasic acid salts, including 0.02 M solutions of tartaric (NaHT), phosphoric (NaH2PO4), and citric (NaH2Cit) acids salts, and NaCl were investigated. It was shown that, for a given current density normalized to the theoretical limiting current calculated by the Leveque equation (i/ilimtheor), EC vortex zone thickness, dEC, decreases in the order NaCl > NaHT > NaH2PO4 > NaH2Cit. This order is inverse to the increase in the intensity of proton generation in the membrane systems under study. The higher the intensity of proton generation, the lower the electroconvection. This is due to the fact that protons released into the depleted solution reduce the space charge density, which is the driver of EC. In all studied systems, a region in chronopotentiograms between the rapid growth of the potential drop and the attainment of its stationary values corresponds to the appearance of EC vortex clusters. The amplitude of the potential drop oscillations in the chronopotentiograms is proportional to the size of the observed vortex clusters.

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Section: Current-voltage Curvesmentioning

confidence: 94%

Section: Background: Proton Generation In Aem/ampholyte Solution Systemsmentioning

confidence: 99%

Section: Background: Proton Generation In Aem/ampholyte Solution Systemsmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Electroconvection on Chronopotentiograms of an Anion-Exchange Membrane in Solutions of Weak Polybasic Acid Salts

Pismenskaya

Rybalkina

Moroz

et al. 2021

IJMS

View full text Add to dashboard Cite

show abstract

“…In the case of a low current density, a thin cation-exchange layer, or a high concentration of external solutions, the electrochemical impedance spectrum of the bilayer membrane is a combination of two distorted semicircles ( Figure 3 b). The analysis of the impedance of ion-exchange membranes in electromembrane systems complicated by the course of chemical reactions was carried out in [ 79 , 80 ]. The first semicircle lying in the mid-frequency region (100 kHz–10 Hz), as in the case of bipolar membranes, is the Gerischer impedance (element G).…”

Section: Methodsmentioning

confidence: 99%

Water Splitting and Transport of Ions in Electromembrane System with Bilayer Ion-Exchange Membrane

et al. 2020

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Bilayer ion-exchange membranes are mainly used for separating single and multiply charged ions. It is well known that in membranes in which the layers have different charges of the ionogenic groups of the matrix, the limiting current decreases, and the water splitting reaction accelerates in comparison with monolayer (isotropic) ion-exchange membranes. We study samples of bilayer ion-exchange membranes with very thin cation-exchange layers deposited on an anion-exchange membrane-substrate in this work. It was revealed that in bilayer membranes, the limiting current’s value is determined by the properties of a thin surface film (modifying layer). A linear regularity of the dependence of the non-equilibrium effective rate constant of the water-splitting reaction on the resistance of the bipolar region, which is valid for both bilayer and bipolar membranes, has been revealed. It is shown that the introduction of the catalyst significantly reduces the water-splitting voltage, but reduces the selectivity of the membrane. It is possible to regulate the fluxes of salt ions and water splitting products (hydrogen and hydroxyl ions) by changing the current density. Such an ability makes it possible to conduct a controlled process of desalting electrolytes with simultaneous pH adjustment.

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“…This phenomenon intensifies with an increase in the current density due to a decrease in the concentration of the depleted solution at the IEM surface [78,133]. It is known [10,126,134] that some of the precipitated substances, for example, magnesium hydroxide (which is a traditional component of milk whey) participate in protonationdeprotonation reactions and intensify the generation of H + and OHions.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

A Review on Ion-Exchange Membranes Fouling during Electrodialysis Process in Food Industry, Part 2: Influence on Transport Properties and Electrochemical Characteristics, Cleaning and Its Consequences

et al. 2021

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Ion-exchange membranes (IEMs) are increasingly used in dialysis and electrodialysis processes for the extraction, fractionation and concentration of valuable components, as well as reagent-free control of liquid media pH in the food industry. Fouling of IEMs is specific compared to that observed in the case of reverse or direct osmosis, ultrafiltration, microfiltration, and other membrane processes. This specificity is determined by the high concentration of fixed groups in IEMs, as well as by the phenomena inherent only in electromembrane processes, i.e., induced by an electric field. This review analyzes modern scientific publications on the effect of foulants (mainly typical for the dairy, wine and fruit juice industries) on the structural, transport, mass transfer, and electrochemical characteristics of cation-exchange and anion-exchange membranes. The relationship between the nature of the foulant and the structure, physicochemical, transport properties and behavior of ion-exchange membranes in an electric field is analyzed using experimental data (ion exchange capacity, water content, conductivity, diffusion permeability, limiting current density, water splitting, electroconvection, etc.) and modern mathematical models. The implications of traditional chemical cleaning are taken into account in this analysis and modern non-destructive membrane cleaning methods are discussed. Finally, challenges for the near future were identified.

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Generation of H+ and OH− ions in anion-exchange membrane/ampholyte-containing solution systems: A study using electrochemical impedance spectroscopy

Cited by 29 publications

References 75 publications

Influence of Electroconvection on Chronopotentiograms of an Anion-Exchange Membrane in Solutions of Weak Polybasic Acid Salts

Influence of Electroconvection on Chronopotentiograms of an Anion-Exchange Membrane in Solutions of Weak Polybasic Acid Salts

Water Splitting and Transport of Ions in Electromembrane System with Bilayer Ion-Exchange Membrane

A Review on Ion-Exchange Membranes Fouling during Electrodialysis Process in Food Industry, Part 2: Influence on Transport Properties and Electrochemical Characteristics, Cleaning and Its Consequences

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