Theory of concentration polarization effects in electrodialysis on counter-ion selectivity of ion-exchange membranes with differing counter-ion distribution coefficients

1990 ◽  
Vol 86 (10) ◽  
pp. 1857 ◽  
Author(s):  
Isaak Rubinstein
Keyword(s):  
Ion Exchange ◽  
Concentration Polarization ◽  
Ion Selectivity ◽  
Distribution Coefficients ◽  
Ion Exchange Membranes ◽  
Ion Distribution ◽  
Polarization Effects ◽  
Counter Ion

scholarly journals Ion mobility and partition determine the counter-ion selectivity of ion exchange membranes

2020 ◽  
Author(s):  
Matthias Wessling
Keyword(s):  
Ion Exchange ◽  
Ion Mobility ◽  
Ion Selectivity ◽  
Quantitative Relation ◽  
Ion Exchange Membranes ◽  
Membrane Conductivity ◽  
Counter Ion ◽  
Counter Ions ◽  
New Perspective ◽  
Two Parameters

Ion (perm)selectivity and conductivity are the two most essential properties of an ion exchange membrane, yet no quantitative relation between them has been suggested. In this work, the selectivity between two different counter-ions is correlated to the membrane conductivity. We show that the counter-ion selectivity measured by conventional electrodialysis (ED) can be expressed by the product of two parameters: (a) the mobility ratio between these two different counter-ions in the membrane and (b) their partition coefficient between the solution and the membrane. This is reminiscent of the classical solution-diffusion model. Via the counter-ion mobility in the membrane, the selectivity could be simply expressed with the membrane conductivity and dimensional swelling degree at pure counter-ion forms and at mixed counter-ion form when the membrane has been equilibrated with 1:1 equivalence ratio of the two counter-ions in the solution. This correlation is validated experimentally for the ion selectivity of K+/Na+ in two commercial hydrocarbon-based cation exchange membranes (CEMs). For K+/Na+ in a commercial perfluorosulfonic CEM, and for Mg2+/Na+ in all the three types of CEMs, the correlation could predict the counter-ion partition very well; but there is an underestimation of the K+/Na+ and Mg2+/Na+ mobility ratios afforded by this correlation, which might be due to simplification of the cation activity coefficients in CEMs. This work offers a convenient method to decouple experimentally the effect of partition and mobility in controlling the membrane selectivity, and also proposes a new perspective to study the selectivity as well as conductivity of ion exchange membranes.

Equilibrium Sorptions in Heterogeneous Ion Exchange Membranes

1992 ◽  
Vol 57 (9) ◽  
pp. 1905-1914
Author(s):  
Miroslav Bleha ◽  
Věra Šumberová
Keyword(s):  
Experimental Data ◽  
Ion Exchange ◽  
Total Content ◽  
Distribution Coefficients ◽  
Exchange Capacity ◽  
Ion Exchange Membranes ◽  
Ion Exchange Capacity ◽  
Equilibrium Sorption ◽  
Inhomogeneity Factor

The equilibrium sorption of uni-univalent electrolytes (NaCl, KCl) in heterogeneous cation exchange membranes with various contents of the ion exchange component and in ion exchange membranes Ralex was investigated. Using experimental data which express the concentration dependence of equilibrium sorption, validity of the Donnan relation for the systems under investigation was tested and values of the Glueckauf inhomogeneity factor for Ralex membranes were determined. Determination of the equilibrium sorption allows the effect of the total content of internal water and of the ion-exchange capacity on the distribution coefficients of the electrolyte to be determined.

scholarly journals Direct 3D observation and unraveling of electroconvection phenomena during concentration polarization at ion-exchange membranes

2021 ◽  
Vol 640 ◽  
pp. 119846
Author(s):  
Felix Stockmeier ◽  
Michael Schatz ◽  
Malte Habermann ◽  
John Linkhorst ◽  
Ali Mani ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Concentration Polarization ◽  
Ion Exchange Membranes

scholarly journals Asymmetric electroosmotic pumping across porous media sandwiched with perforated ion-exchange membranes

2017 ◽  
Vol 199 ◽  
pp. 175-193 ◽  
Author(s):  
A. Yaroshchuk ◽  
E. E. Licón ◽  
E. K. Zholkovskiy ◽  
M. P. Bondarenko ◽  
T. Heldal
Keyword(s):  
Ion Exchange ◽  
Concentration Polarization ◽  
Average Distance ◽  
Ionic Concentration ◽  
Hydraulic Permeability ◽  
Debye Screening Length ◽  
Ion Exchange Membranes ◽  
Lateral Direction ◽  
Non Linear ◽  
Electroosmotic Pumps

To have non-zero net flow in AC electroosmotic pumps, the electroosmosis (EO) has to be non-linear and asymmetric. This can be achieved due to ionic concentration polarization. This is known to occur close to micro-/nano-interfaces provided that the sizes of the nanopores are not too large compared to the Debye screening length. However, operation of the corresponding EO pumps can be quite sensitive to the solution concentration and, thus, unstable in practical applications. Concentration polarization of ion-exchange membranes is much more robust. However, the hydraulic permeability of the membrane is very low, which makes EO flows through them extremely small. This communication shows theoretically how this problem can be resolved via making scarce microscopic perforations in an ion-exchange membrane and putting it in series with an EO-active nano-porous medium. The problem of coupled flow, concentration and electrostatic-potential distributions is solved numerically by using finite-element methods. This analysis reveals that even quite scarce perforations of micron-scale diameters are sufficient to observe practically-interesting EO flows in the system. If the average distance between the perforations is smaller than the thickness of the EO-active layer, there is an effective homogenization of the electrolyte concentration and hydrostatic pressure in the lateral direction at some distance from the interface. The simulations show this distance to be somewhat lower than the half-distance between the perforations. On the other hand, when the surface fraction of perforations is sufficiently small (below a fraction of a percent) this “homogeneous” concentration is considerably reduced (or increased, depending on the current direction), which makes the EO strongly non-linear and asymmetric. This analysis provides initial guidance for the design of high-productivity and inexpensive AC electroosmotic pumps.

SELECTION OF ION-EXCHANGE RESIN FOR EXTRACTION OF REE FROM COMPLEX SOLUTIONS DURING PROCESSING OF OIL CRACKING CATALYST

2020 ◽  
Vol 25 (2) ◽  
pp. 39-43
Author(s):  
Mariya Pogodaeva ◽  
Alexandra Bogdanova ◽  
Lyudmila Adeeva
Keyword(s):  
Ion Exchange ◽  
Exchange Resin ◽  
Ion Exchange Resin ◽  
Distribution Coefficients ◽  
Ion Distribution ◽  
Ion Exchange Separation ◽  
Complex Solutions ◽  
Exchange Resins ◽  
Oil Cracking ◽  
Selection Of

It was found that the ion exchange resins Purolite C100 H and Purolite S-957 can be used to extract lanthanum (III) ions from solutions. The values of the resin capacities for lan-thanum (III), iron (III) and aluminum and the ion distribution coefficients for both resins were determined. It is shown that according to the values of the separation coefficients, Purolite C100 H resin can be used for ion exchange separation of lanthanum ions from complex solutions

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