EFFICIENCY OF THE GENERATION OF PROTONS AND HYDROXYL IONS IN BIPOLAR MEMBRANES BY ELECTRIC-FIELD ENHANCED WATER DISSOCIATION

The efficiency of the production of protons and hydroxyl ions generated by electric field enhanced water dissociation within bipolar membranes is studied as function of the electrolyte concentration. Two types of bipolar membranes are used for the experiments: (a) A bipolar membrane formed by an anion and a cation exchange membrane which are held together by adhesion. The volume of the transition region between the two ion exchange membranes is varied systematically by inserting stacks of Nucleopore membranes. (b) A bipolar membrane formed by an anion and a cation exchange membrane are bound together permanently. The results are discussed in terms of the model of the membrane with narrow pores. The space charge model proposed in the literature to describe the electrochemical properties of bipolar membranes is modified to interprete the properties of the bipolar membranes of type (a) with a stack of Nucleopore membranes in the enlarged transition zone between the anion and the cation exchange membrane.