ROLE OF HS- AND S2- IN PASSIVATION OF NI IN C1- + H2S SOLUTIONS

Potentiokinetic studies of the anodic dissolution of Ni in chloride solutions (pH 4·65) containing small concentrations of H2S indicate that passivation is due to the formation of a sulphide film. The potential at which the film forms indicates that it is NiS, and this observation has been confirmed by x-ray diffraction. At low concentrations of H2S, the HS- ion is the dominant species in the formation of NiS, whereas at higher concentrations the S2- ion becomes dominant. © 1969.