Membrane Structure and Ion Permeation

Abstract

This article considers the classification of membranes according to structure. Site-free membranes, liquid ion exchangers, and solid ion exchangers are discussed. Three theoretical approaches used in characterizing ion permeation are described: the Nernst-Planck flux equations and extensions thereof; the theory of irreversible thermodynamics; and the transition (rate-process) theory. The distinguishing features of ion permeation in these various systems are dealt with.