New technique for removing hexavalent chromium from waste water and energy generation via galvanic reduction with scrap iron

Indirect reduction of hexavalent chromium to trivalent chromium with scrap iron and simultaneous generation of electrical energy via the galvanic cell: Fe/Fe2+ : Cr6+, Cr3+(C) was studied using a divided parallel plate cell. Measurement of cell voltage vs cell current has shown that the rate of reduction of hexavalent chromium (represented by the cell current) and the electrical energy output increases with increasing the initial concentration of hexavalent chromium and solution temperature. The performance of the cell was also tested using fixed bed electrodes instead of the hat plate electrodes. Thermodynamic calculations have shown that the present technique can reduce Cr6+ below the maximum permissible value adopted by the USEPA. The advantages of the present technique over other methods is that it neither consumes energy nor expensive chemicals. A practical application and methods for improving the present technique are discussed. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.