MEMBRANE DIFFUSION-CONTROLLED KINETICS OF IONIC TRANSPORT

A computer algorithm based on the Nernst-Planck equation has been developed for digital simulation of ionic transport in an ion exchange system with a membrane separating two electrolyte solutions. The Na+-H+ couple has been studied experimentally with a cation-exchange membrane to test the numerical algorithm. The optimum diffusion coefficients of the counter-ions are determined for the membrane diffusion controlled exchange rate. The measured external solution concentrations agree satisfactorily with the numerical results. This procedure allows the treatment of unsteady state transport through membranes and avoids the numerical instabilities which are frequently encountered in numerical methods.