Steady-state and transient electrical properties of ion-exchange membrane systems in asymmetric arrangements

The steady-state and transient electrical properties of ion-exchange membranes placed between two solutions with different values of the electrolyte concentration, have been simulated using the network simulation method. The ionic transport processes are theoretically described on the basis of the Nernst-Planck and Poisson equations. The system under study is constituted by a cation-exchange membrane in which the fixed-charge is homogeneously distributed in space and two diffusion boundary layers on both sides of the membrane, the electric double layers at the interfaces being included. The steady-state voltage-current characteristic and the profiles of the ionic concentrations and the electric potential, are analysed. Also, the choronopotentiometric response of the system has been discussed and the time evolution of the electric energy consumption evaluated. In particular, the influence of the ratio of the bathing concentrations on the permselectivity and the chronopotentiometric response of the ion-exchange membrane systems, has been established.