Dependence of Bi-ionic Potential across Charged Membranes on Salt Concentration

Abstract

Measurements of bi-ionic potential were carried out across anion-exchange membranes for KCl/KIO₃ system and across cation-exchange membranes for KCl/NaCl system. The transport numbers of counterions in the membranes were nearly unity under the experimental conditions. The increase of bi-ionic potential was observed with an increase in the external electrolyte concentration. The electrolyte concentration dependence of bi-ionic potential would be due to both the changes in the mobility ratio of two counterions in the membrane and in the difference of standard chemical potentials between the membrane and the external solution.