A simple model to determine the trends of electric field enhanced water dissociation in a bipolar membrane

This work is concentrated on elucidating the mechanism of the electric fiel d enhanced water dissociation. A simple model was established for the theor etical current-voltage characteristics in water dissociation process on a b ipolar membrane based on the existence of a depletion layer and Onsager's t heory. Particular attention was given to the influence of applied voltage o n depletion thickness and the dissociation constant. The factors on the wat er splitting process, such as water diffusivity, water content, ion exchang e capacity, temperature, relative permittivity, etc. were adequately analys ed based on the derived model equations and several suggestions were propos ed for decreasing the applied voltage in practical operation. The water dis sociation tests were conducted and compared with both the theoretical calcu lation and the measured current-voltage curves reported in the literature, which showed a very good prediction to practical current-voltage behavior o f a bipolar membrane at high current densities when the splitting of water actually commenced.