Conductivity study of heterogeneous ion-selective membranes in concentrated sodium chloride solutions

Membrane conductivity was studied as a function of concentration of the equilibrium sodium chloride solution and of the pretest conditioning of the membranes. The electrical resistance of the membranes was determined by the difference method in a cell with platinized platinum electrodes. The results indicate that the higher conductivity of the membranes saturated consecutively derives from the higher moisture capacities of these membranes and from the larger number of carriers present in them. The optimum values of moisture capacity are 11.5-12.0 for the MK-40 cation-exchange membrane, and 7.0-7.5 mg-mode of H2O per mg-mole for the MA-40 anion-exchange membrane.