Transient electrical response of ion-exchange membranes with fixed-charge due to ion adsorption. A network simulation approach

The transient electrical properties of ion-exchange membranes with inhomogeneous fixed-charge distributions due to ion adsorption processes, have been investigated using the network simulation method. A network model is proposed for the Nernst–Planck and Poisson equations describing the transport of a binary electrolyte through an ion-exchange membrane and the two diffusion boundary layers on both sides of the membrane. An electric circuit simulation program is used to solve the network model in order to obtain the transient electrical properties of a system where the fixed-charge concentration of the membrane is due to an anion adsorption process. The chronoamperometric and chronopotentiometric responses of the whole membrane system have been simulated for the case of a membrane with surface charge described by a Langmuir kinetics.