Limiting current densities in electromembrane systems with carboxyl-containing polyamidoimide membranes

Voltammetric characteristics of electromembrane systems with carboxyl-containing polyamidoimide membranes in 0.01 M solutions of sodium and hydrogen chlorides are studied using a rotating membrane disc. The limiting current density increases with the decrease in the exchange capacity and an increase in the generation temperature and imidization degree of membranes, due to variations in their structures. The difference in the structure of membranes with various exchange capacities is proved by the standard porosimetry method. The distinguishing feature of the limiting state in the HC1 solutions is that the generation of the hydrogen and hydroxyl ions in the near-surface layer occurs long before its concentration exhaustion.