Photooxidation reactions of polycyclic aromatic hydrocarbons over pure and Ag-loaded BiVO4 photocatalysts

Photooxidative degradations of nine polycyclic aromatic hydrocarbons (PAHs) using pure and Ag-loaded BiVO4 photocatalysts have been examined in acetonitrile under visible light irradiation. Photoproducts have been identified by means of gas chromatography-mass spectrometry (GC-MS). Silver fine particles loaded on BiVO4 surface improved the reaction rates of all PAHs degradations. In particular, anthracene and benz[a]anthracene (Bz[a]A) are efficiently oxidized to anthraquinone and benz[a]anthracene-7,12-dione, respectively. Photooxidation mechanism of anthracene and Bz[a]A has been clarified by the GC-MS analyses by the use of H218O as a reactant. It has been proved that OH radicals are generated through the oxidation of water by valence band holes on the Ag-BiVO4 surface in acetonitrile, and greatly contribute to the degradations of these PAHs. The OH radical attack to PAHs probably determines the overall rates of oxidation of PAHs on Ag-BiVO4 photocatalyst.