Electrochemical properties of cation exchange membranes

Abstract

An investigation has been carried out on the effect of concentration and temperature of electrolytes on the conductivity and transport number of a cation-exchange membrane. The membrane was prepared by modification of high-molecular weight polyethylene (M_n= 1.19 × 10⁶) with styrene and divinylbenzene and following sulphonation. The investigation includes a determination of the membrane conductivity for sodium chloride and sodium hydroxide with 0.1 to 4.0 mol dm^–3 concentrations. The results obtained indicate that the membrane conductivity (_M) values for sodium chloride solutions decrease with an increase in the external solution concentration, while for NaOH solutions _M passes through a maximum at 0.5 mol dm^–3 solution and then decreases. Arrhenius activation energies were calculated for the corresponding concentrations and temperatures. The values of the transport number (t_Na⁺) for the NaCl concentrations examined have also been determined. These values vary from 0.99 to 0.83 with increasing solution concentration.