Permselectivity of bilayered ion-exchange membranes in ternary electrolyte

Zabolotsky, V. I.; Achoh, Aslan; Лебедев, К. А.; Melnikov, Stanislav

doi:10.1016/j.memsci.2020.118152

Cited by 32 publications

(18 citation statements)

References 65 publications

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“…The main purpose of the work was to evaluate the possibility of the application of the PANI-modified CEMs for the separation of cations in the electrodialysis. The theoretical ratio of fluxes of doubly and singly charged cations in limiting conditions for ideally selective membrane (limiting permeability coefficient

) could be estimated on the basis of diffusion coefficients of the cations in the solution according to the formula [ 46 ]:

where J 1 and J 2 are fluxes of 1 and 2 counter-ions, correspondingly; z 1 and z 2 are charges of 1 and 2 counter-ions, correspondingly; z A is a charge of co-ion; D 1 and D 2 are diffusion coefficients of 1 and 2 counter-ion in the solution, correspondingly. The diffusion coefficients for H + , Na + and Ca 2+ ions in the solution are 9.34 × 10 −9 , 1.34 × 10 −9 and 0.79 × 10 −9 m 2 /s [ 47 ].…”

Section: Resultsmentioning

confidence: 99%

Section: Heterogeneous Membranesmentioning

confidence: 99%

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Permselectivity of Cation Exchange Membranes Modified by Polyaniline

Фалина

Loza

et al. 2021

Membranes

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This work discusses the applicability of polyaniline-modified cation exchange membranes for the separation of monovalent/divalent cations by electrodialysis. A novel method of membrane modification directly in the electrodialysis unit is used to prepare permselective membranes. Complex characterization of the membranes before and after modification allows revealing the influence of membrane matrix on the modification efficiency. The characterization of the membranes includes determination of the diffusion permeability, specific conductivity and current–voltage curves in HCl, NaCl and CaCl2 solutions, as well as transport-structural parameters of the extended three-wire model. The characterization results are used to predict the influence of the modification on membrane permselectivity. The competitive mass transfer of singly and doubly charged cations in the electrodialysis process is investigated in underlimiting and overlimiting currents. Electrodialysis desalination of a solution containing Na+/Ca2+ or H+/Ca2+ cations shows that the modification leads to an increase in membrane permselectivity to single-charged cations due to the repulsion of Ca2+ ions from the positively charged membrane surface. The permselectivity of the polyaniline-modified perfluorinated membrane to H+ in the mixture of H+/Ca2+ cations is observed in all current regimes.

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) could be estimated on the basis of diffusion coefficients of the cations in the solution according to the formula [ 46 ]:

Section: Resultsmentioning

confidence: 99%

Section: Heterogeneous Membranesmentioning

confidence: 99%

Permselectivity of Cation Exchange Membranes Modified by Polyaniline

Фалина

Loza

et al. 2021

Membranes

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“…The effect of diffusion boundary layer thickness on ions transport across bilayer membranes were studied using a rotating membrane disk. The rotating membrane disk setup and methodology are explained in detail in a number of publications [ 77 , 78 ].…”

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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“…When the current density increased, the driving force became stronger and this led to a suppression of the electrostatic interaction and steric hindrance effects. Moreover, according to the mathematical models developed by Zabolotsky et al [41,42], the perm-selectivity of monovalent ions against divalent ions would approach to a stable value that was independent of the membrane properties and the space charge region when the current density applied was close to or higher than the limiting current density. This means that the perm-selectivity of the membrane at a high current density was controlled solely by the diffusivity of the ions in the solution.…”

Section: Effect Of Current Densitymentioning

confidence: 99%

In-Situ Combination of Bipolar Membrane Electrodialysis with Monovalent Selective Anion-Exchange Membrane for the Valorization of Mixed Salts into Relatively High-Purity Monoprotic and Diprotic Acids

Yan

Li²,

Zhou

et al. 2020

Membranes

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The crystalized mixed salts from the zero liquid discharge process are a hazardous threat to the environment. In this study, we developed a novel electrodialysis (SBMED) method by assembling the monovalent selective anion-exchange membrane (MSAEM) into the bipolar membrane electrodialysis (BMED) stack. By taking the advantages of water splitting in the bipolar membrane and high perm-selectivity of MSAEM for the Cl− ions against the SO42− ions, this combination allows the concurrent separation of Cl−/SO42− and conversion of mixed salts into relatively high-purity monoprotic and diprotic acids. The current density has a significant impact on the acid purity. Both the monoprotic and diprotic acid purities were higher than 80% at a low current density of 10 mA/cm2. The purities of the monoprotic acids decreased with an increase in the current density, indicating that the perm-selectivity of MSAEM decreases with increasing current density. An increase in the ratio of monovalent to divalent anions in the feed was beneficial to increase the purity of monoprotic acids. High-purity monoprotic acids in the range of 93.9–96.1% were obtained using this novel SBMED stack for treating simulated seawater. Therefore, it is feasible for SBMED to valorize the mixed salts into relatively high-purity monoprotic and diprotic acids in one step.

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Permselectivity of bilayered ion-exchange membranes in ternary electrolyte

Cited by 32 publications

References 65 publications

Permselectivity of Cation Exchange Membranes Modified by Polyaniline

Permselectivity of Cation Exchange Membranes Modified by Polyaniline

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

In-Situ Combination of Bipolar Membrane Electrodialysis with Monovalent Selective Anion-Exchange Membrane for the Valorization of Mixed Salts into Relatively High-Purity Monoprotic and Diprotic Acids

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