ANODIC-DISSOLUTION OF CRYSTALLINE LEAD SULFIDE IN SIMPLE ELECTROLYTE-SOLUTIONS

The electrochemical oxidation of lead sulfide is studied by using a rotating ring-disk electrode. The effect of pH, light intensity, and mass transfer on the dissolution of PbS(s) is examined. The major oxidation reaction is: PbS(s) --> Pb2+ + S(s) + 2e-, which is independent of pH. However, the elemental sulfur formed from this reaction inhibits further PbS(s) oxidation. The semiconducting properties of lead sulfide cause the oxidation to be photosensitive. The presence of aqueous lead inhibits the dissolution, and diffusion of released Pb(II) from the surface may control the reaction. The type of anion in the supporting electrolyte influences the dissolution.