Electrodeposition modification of heterogeneous cation exchange membrane using expanded polystyrene waste: Enhanced electrochemical properties and electrodialytic performance

•The electrochemical properties of CEM as well as its performance in electrodialytic desalination of NaCl solution can be improved due to the inserting sulfunic groups to the polymeric matrix of CEM.•At high polyelectrolyte concentrations, the electrochemical properties and performance of the modified CEM were declined owing to the increase in the thickness of modifier layer which causes isolation of membrane functional groups and blocking the paths of ions transfer.•The optimum electrodeposition conditions were obtained to be 2 g/L electrolyte concentration, 8 mA/cm2 applied current intensity and 30 min electrodeposition time under which membrane electrical resistance decreased up to 52 % and IEC increased up to 8 %.•The ionic flux of Na+ in electrodialytic desalination can be enhanced by 58 %. In this study, surface modification of a cation exchange membrane based on polyvinyl chloride was accomplished via electrochemical deposition of post-sulfonated waste-expanded polystyrene aiming to enhance its electrochemical properties and electrodialytic performance. The membrane was synthesized by the phase inversion method, modified with different concentrations of polyelectrolyte, characterized by FTIR and SEM analyses, and applied for electrodialytic desalination of NaCl solution. Deposition of sulfonated polystyrene with polyelectrolyte concentration of 2 g/l, current of 8 mA/cm2, and period time of 30 min caused a reduction in electrical resistance up to 52 %. Furthermore, the sodium ionic flux through electrodialytic desalination was improved by 58 % as a result of the promotion of the electrochemical properties of the membrane.