The influence of activation of heterogeneous ion-exchange membranes on their electrochemical properties

The aim of this work was to find optimal conditions of activation of heterogeneous ion-exchange membranes. Commercial both cation-exchange and anion-exchange membranes were used in this study. The activation procedure consists in alternating immersion of a heterogeneous membrane into aqueous solutions of 1 M HCl and 1 M NaOH. The activation procedure of cation-exchange membranes consists in a multiple conversion of the Na+ membrane form to the H+ form and back and that of anion-exchange membranes in a multiple conversion of the Cl− membrane form to the OH− form and back. An efficient activation of anion exchange membranes strongly depends on the total time of treatment and on the number of exchange steps and requires at least a 5-d treatment and two exchanges of ions or 4.5 h treatment and four exchanges of ions. An efficient activation of cation exchange membranes is a rather fast process requiring about 3.5 h and three exchanges of ions.