SULFIDE ION ELECTROOXIDATION CATALYZED BY COBALT PHTHALOCYANINE MICROCRYSTALS

Electrooxidation of sulfide ion catalysed by microcrystals of cobalt p hthalocyanine was investigated by cyclic voltammetry in 0.5 M KNO3 at pH 9.22. Traces of catalyst were immobilized at the surface of a paraf fin-impregnated graphite electrode by the mechanical transfer of its p owder. The electrooxidation of HS- proceeds in two irreversible steps, with the first peak between 0 V and -0.12 V and the second at 0.17 V. The first step is second order in HS- and its product is the adsorbed disulfide, which may further dissociate to give adsorbed sulfur atoms . The reduction of sulfur occurs at -0.1 V.