Ion conducting spacer for improved ed

Abstract Polarization in electrodialysis systems can be suppressed by suitably shaped ion-conducting spacers. Cation- and anion-exchange fibers were used for the preparation of such spacers. In a laboratory cell pair, performance of the conducting spacer was compared to that of a geometrically similar inert one. High coulombic efficiency, stable pH, and low resistance were found with the conducting spacer at low dialysate concentration, high current density and low flow rate. With the inert spacer, water splitting was evident in this region, shown by acidification of diluate, and decrease of efficiency. The effective thickness of the dialysate cell containing the conducting spacer was found to be smaller than the actual geometrical one.