Selectivity of Transport of Sodium, Magnesium, and Calcium Ions through a Sulfo-Cationite Membrane in Mixtures of Solutions of Their Chlorides

Abstract

The transport numbers and the selectivity of transport of sodium, magnesium, and calcium ions through a heterogeneous sulfo-cationite membrane in solutions of sodium, magnesium, and calcium chlorides and their mixtures are studied at various current densities. Equations for calculating the selectivity of transport of the ions through the membrane are suggested for two extreme cases. One case corresponds to low currents, when one can assume that the membrane is at equilibrium with the outside solution. The selectivity of transport of the ions is defined in this case by their migration through the membrane. The other case occurs at currents that are close to a limiting value. Under these conditions the transport of the ions through the membrane is defined by their transport through a diffusion layer that forms near the membrane surface. Calculations with the aid of these equations satisfactorily conform to experiment. The deviation from calculation in the case of the magnesium cation is connected probably with its hydration being substantially greater as compared with sodium and calcium. It is established that the selectivity of transport of the ions through the membrane may be controlled to a certain extent by varying the current density.

Mussel-Inspired Monovalent Selective Cation Exchange Membranes Containing Hydrophilic MIL53(Al) Framework for Enhanced Ion Flux

“…37 In addition, the great affinity of Mg 2+ for the functional groups of the CEMs gives the membrane a high electroconductance. 38 The only difference of the geometric arch at high frequencies is the diameter of the additional arch, which indicates the formed functional layer on membrane surface can restrict the ions transport. 39 With insight into the second diffusional arc at low frequencies, despite no significant difference being observed concerning the diameter of arch, the slight reduction trend for membrane after modification confirms the restriction of the ion migration through the diffusion layer, electrical double layer, and the CEMs.…”

“…The smaller resistance in these circumstances may be related to the enhanced shielding effect of double layer compression between the positive PDA/PEI modified layer and the negative CEMs, which reduced the electrostatic repulsion between the modified layer and Mg 2+ . In addition, the great affinity of Mg 2+ for the functional groups of the CEMs gives the membrane a high electroconductance . The only difference of the geometric arch at high frequencies is the diameter of the additional arch, which indicates the formed functional layer on membrane surface can restrict the ions transport .…”

Diagnostics of the Structural and Transport Properties of an Anion-Exchange Membrane MA-40 after Use in Electrodialysis of Mineralized Natural Waters

“…The hydration numbers of Ca 2+ and Mg 2+ ions are 8 and 10, respectively [73]. These parameters facilitate the migration of calcium ions in the solution of the pore space of the membrane in comparison with magnesium ions [7,74,75].…”

Influence of Flow Rate on the Removal of Copper, Lead and Nickel From Solutions in Electrodialysis Process

“…In addition, at very high flow rates, deterioration or rupture The hydration energy is the energy change that occurs as a result of the hydration of one mole of ion in gas form (Whitten, Peck, Stanley, Davis, & Keeney-Kennicutt, 2009). It is stated that an ion with lower hydration energy has higher removal efficiency (Greben & Rodzik, 2005).…”