Enhancement of TiO2-photocatalyzed organic transformation by ZnO and ZnS. Oxidation of diphenylamine

TiO2 anatase photocatalyzes the oxidative transformation of diphenylamine (DPA) to N-phenyl-p-benzoquinonimine (PBQ) in ethanol. The PBQ formation increases with increase of [DPA], TiO2-loading, airflow rate and light intensity. The catalyzed formation of PBQ is larger with UV-C light illumination than with UV-A light illumination. The catalyst is recyclable. The photocatalytic reaction mechanism has been proposed and the kinetic parameters deduced. ZnO and ZnS enhance the TiO2-photocatalyzed DPA oxidation suggesting interparticle charge transfer in mixed semiconductors.