Electrolytic destruction of cyanide on bare and MNO2 coated 304 stainless steel electrodes

Abstract

MnO2 coated lead and ANSI-304 stainless steel anodes were evaluated for use in electrolytic cyanide waste effluent treatment. Cyclic voltametry experiments revealed that MnO2 on lead was too resistive to be a feasible substrate. Cyclic voltammetry on bare and MnO2 coated steel shows evidence of cyanide destruction just prior to the onset of massive oxygen evolution, suggesting a reaction mechanism in which cyanide is oxidized via reaction with hydroxide radical species on the electrode surface. Galvanostatic experiments showed little difference in cyanide oxidation performance behaviour between bare steel and the MnO2 coating. However, copper ion were found to catalyse cyanide oxidation for bare steel, but had no observed effect for MnO2 coated steel. A cost analysis was done comparing electrolytic cyanide destruction using bare steel anodes to the INCO SO2/Air process. Electrolytic cyanide oxidation was concluded to have significantly lower operating costs, but is infeasible due to prohibitive capital costs.