Bi-ionic system: theoretical investigation on the ionic fluxes through an ion-exchange membrane

We have established a theoretical description of the co-ion and counter-ion fluxes through an ion-exchange membrane (IEM) used in a bi-ionic system. T his study is based on the modified Nernst-Planck equation applied to three parallel homogenous phases: two diffusion boundary layers (DBLs) and an IEM . The role of the IEM and of the DBLs in the control of the interdiffusion process is discussed. The influence of the common concentration, the co-ion and counter-ion diffusion coefficients in the membrane, the membrane selec tivity and affinity, the concentration of functional sites and the convecti on velocity are evaluated.