Electric field-assisted proton transfer and water dissociation at the junction of a fixed-charge bipolar membrane

Abstract

Electric field-enhanced (EFE) water dissociation can occur at the interfacial space charge junction of both biological and synthetic fixed-charge bipolar membranes. This dissociation has so far been analysed on an electrochemical basis using modified second Wien effect and absolute rate theories. We propose a statistical thermodynamics model to describe the cooperative orientation of the water molecules by the electric field at the bipolar junction. The approach is simple and retains some of the essential aspects of the phenomenon. In particular, the EFE water dissociation can now be rationalised on the basis of a field-assisted proton transfer mechanism involving the membrane fixed charge and the water molecules at the space charge region of the bipolar junction.