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 (Mn= 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 (tNa+) for the NaCl concentrations examined have also been determined. These values vary from 0.99 to 0.83 with increasing solution concentration.