Membrane potential and ion transport in inhomogeneous ion-exchange membranes

Abstract

The Nernst–Planck equation is modified for the transport of uni-univalent ions in inhomogeneous membranes, which contain continuous gradients of partition and activity coefficients of the ions and/or fixed charge density. Standard chemical-potential gradients in the membranes are employed in the equation as a new force. Numerical solutions of membrane potential and ion fluxes for 10 model membranes are obtained from simulation at the condition of zero current. Various potential and concentration profiles are observed, which depend on the partition coefficients and/or the fixed charge density in the membranes.