CURRENT-VOLTAGE CURVE OF A BIPOLAR MEMBRANE AT HIGH-CURRENT DENSITY

The potential drop across a bipolar membrane was measured as a functio n of the applied current density. As a result, an inflection point was observed in the obtained current-voltage curve at high current densit y. This inflection point indicates that at high current densities wate r supply from outside of the bipolar membrane to the interface between a cation and an anion exchange layer is the rate limiting step for th e water dissociation process. The dependence of the current-voltage cu rve on external conditions such as temperature and feed solution conce ntration was also investigated. The position of the inflection point c hanged with the temperature and the concentration of the external solu tion.