The photocatalytic reaction of benzhydrol on CdS in MeCN was studied. It was found that O, H2O, H2O2, Me viologen, which can scavenge an electron from the conduction band of a semiconductor, initiated or promoted the reaction. The reaction was quenched completely by a radical quencher. The photocatalytic feature of CdS is revealed and the mechanism discussed. There are 2 distinct processes in the photocatalytic reactions, a heterogeneous process on the surface of the catalyst, which initiates the reaction, and a homogeneous process in the solution which propagates the reaction.

Key words: CADMIUM SULFIDE, WATER, PHOTOOXIDATION, BENZALCOHOL P, PHOTOCATALYSIS, HYDROGEN PEROXIDE, QUENCHING EFFECTS, METHYL VIOLOGEN