Removal of Cr(III) and Cr(VI) through the plasma modified and unmodified ion-exchange membranes

Abstract

The removal of trivalent and hexavalent chromium ions through charged ion-exchange membranes by using two detachable compartments was studied under Donnan dialysis conditions. The surfaces of ion-exchange membranes were treated by electron cyclotron resonance plasma (ECR) to increase the performance. The effects of plasma modified ion-exchange membranes and pH on removal chromium ions were investigated at 25 °C. The flux values ( J) and recovery factor (RF) of trivalent and hexavalent chromium ions before and after the plasma modification were obtained. The flux values and recovery factors for plasma modified SA 3S, SA 3T and SB-6407 ion-exchange membranes are higher than that of unmodified membrane. This can be explained by change of morphology of pores in the plasma modified membranes. The surface morphology of the plasma modified and unmodified ion-exchange membranes are characterized by SEM and AFM. Ion-exchange capacity, membrane potential measurement and sorption capacity measurements were carried out in order to understand how the plasma treatment affected on the membrane charge selectivity. As a result no change for charge selectivity was observed.