Studies with model membranes. : XI. Evaluation of thermodynamic parameters for diffusion and fixed charge density by methods based on thermodynamics of irreversible processes

Abstract

The various ionic processes occurring in membrane systems notably (i) ionic transport, (ii) membrane potential, (iii) electrical conductivity, and (iv) ionic distribution and the potentials within the membrane have been thoroughly studied with a parchment-supported silver phosphate membrane. By applying the theory of absolute reaction rates, various thermodynamic parameters, namely Δ H ≠, Δ F ≠ and Δ S ≠ were evaluated. The Δ S ≠ values were found to be negative, indicating that diffusion takes place with partial immobilization in the membrane phase. The effective fixed charge density was also evaluated by methods based on the thermodynamics of irreversible processes.