Electrolytic Reduction of Chromium (VI) and Copper Using Coke Electrodes.
McDonald-HO; Soboroff-DM; Cochran-AA
Solutions containing cr6+ and sulfuric acid are used in a number of surface-finishing operations. Substantial quantities of chromium and copper are lost and pollution problems are created when the spent solutions are discarded. To minimize the undesirable environmental effects while improving secondary resource recovery technology, the Bureau of Mines is conducting research to detoxify and recover metals from these solutions. Spent etchants are treated to remove copper and reduce cr6+ to cr3+ in an electrolytic cell. The anodes and cathodes are granulated coke. The spent solution is continuously pumped through the electrodes. Hexavalent chromium is reduced to trivalent chromium, and copper is recovered at the cathode. Reoxidation of cr3+ at the anode was not observed. The removal and recovery of copper and reduction of cr6+ lessen chemical demand and increase efficiency in waste treatment operations associated with the use of these solutions.
IH; Report of Investigation;