Chronopotentiometric studies of bipolar membrane in sodium chloride solution

The electrical properties of bipolar membrane (BPM), have been examined in sodium chloride solution by chronopotentiometry. In this method, the and membrane is placed between the two current carrying electrodes while its potential is recorded against the electrolysis time using two SCE electrodes closely placed on either side. An inflection is observed in the membrane potential at the transition time, tau. The inflection which is fairly sharp in milli-molar concentrations of NaCl and becomes ill-defined as the concentration of the latter is increased to 0.05 M, and is not obtained in 0.1 M or higher concentration of NaCl. The measured value of i tau(1/2) is found to be independent of the current density applied at the electrodes but it increases linearly as the concentration of the electrolyte increases as predicted by theoretical equations.