Effect of interface structure and amino groups on water splitting and rectification effects in bipolar membranes

Bipolar membranes consist of a layered structure involving a cation selective membrane joined to an anion selective membrane. This is of practical interest in a new process for the commercial production of acids and bases. In this study, the mechanism of water splitting and the characteristics of the bipolar membranes were examined. It was suggested that water splitting occurred due to the second Wien effect in the intermediate region, because the potential drop was very large. If amines exist in the intermediate region, the water splitting is accelerated, because protonation and deprotonation reactions occur between H2O and the amines. Current-voltage characteristics were correlated with water splitting effects. The efficiency of water splitting was increased by controlling the positions of the amino groups in the anion-selective polymer. (C) 1997 Elsevier Science Ltd.