Transport of trivalent and hexavalent chromium through different ion-selective membranes in acidic aqueous media

The aim of this work was io evaluate the transport of trivalent and hexavalent chromium through anion- and cation-selective membranes using two- and three-compartment electrodialysis cells. Tests were done with acidic solutions of trivalent chromium ions, Cr3+ and hexavalent chromium ions, Cr2O72-. In each situation the transport of metallic ions through the membrane was evaluated. In the tests with trivalent chromium, Nafion 417 and Selemion CMT cation-selective membranes were used, and in the tests with hexavalent chromium, Selemion AMT membrane was used. The influence of SO42- ions and of the concentration of H+ ions in the solutions was also analyzed. Results showed the oxidation of the Cr3+ ion at the anode and the reduction of the Cr2O72- ion at the cathode. The maximum yield in the process was reached when hexavalent chromium solutions were used in the absence of sulfate ions and a Selemion AMT membrane in a three-compartment cell.