Current-voltage curve for the space charge region of a bipolar membrane

Equations for the current-voltage curve (CVC) of the space charge region (S CR) of a bipolar membrane are derived. The equations differ from traditiona l ones by allowing for the recombination of ions H+ and OH-. The derivation allowed for both the catalytic function of ionogenic groups in the reactio n of water dissociation and the acceleration of this reaction in SCR due to the effect of an electrical field of high strength E. The two types of the derived equations differ in the shape of the dependence of the rate consta nt of this reaction on E. In one case, the rate constant depends exponentia lly on E. In the other, the dependence is more complicated and involves the Bessel function. The equations are used to approximate experimental depend ences of the overvoltage of the bipolar region on the current density for m embranes MB-1, MB-2, and MB-3. The approximation allowed the rate constants of the above reaction to be calculated at a zero strength of the electrica l field.