The Rates of Interexchange of Ions Across Fixed Charge Membranes in Bi-Ionic Systems

This paper examines the applicability of the Nernst-Planck approach in treating the relationship between the initial rates at which critical ions interexchange across permselective membranes in bi-ionic systems and the rates of self-exchange of these ions across the same membranes. Data are presented for five species of univalent cations with two types of cation permeable membranes, a polystyrene sulfonic acid-collodion matrix membrane, and an oxidized collodion membrane; five species of univalent anions were studied with a protamine-collodion matrix anion permeable membrane. Except with systems involving H+ ion, the experimentally found relationships between the rates of interexchange and the rates of self-exchange were in agreement, in most cases within ±5%, with the values calculated from an expression in which interaction between the critical ions in the membrane is not taken into account. In systems with H+ ion, the experimental rates of interexchange were from 27% to 40% less than calculated values