Diffusion-Exchange of Exchange Ions and Nonexchange Electrolyte in Ion-Exchange Membrane Systems

Abstract

The following parameters of cation‐ and anion‐permeable membrane systems were measured: water content; ohmic resistance; exchange capacity; diffusible electrolyte content; concentration potential; rate of exchange‐diffusion of electrolytes; rate of diffusion of nonelectrolytes; effect of rate of stirring on diffusive flux. From these were calculated: the thickness of the unstirred film, which varied from 1 to 30 microns; the diffusion coefficient of the potassium ion in a sulfonic acid cation‐permeable membrane, which was found to vary from to twice that value as the ambient solution concentration was changed from 0.001 to 0.1M; the diffusion coefficient of the chloride ion which remained at about 3 × 10⁻⁷; the diffusion coefficients of non‐electrolytes. A theoretical treatment showed that diffusion coefficients and other parameters could be estimated from a consideration of pore diameters, a tortuosity factor, and water contents.