Abstract: The photocatalytic activity of Pt/TiO₂ was higher than that of TiO₂ for the photdegra-dation of phenol, 4-chlorophenol, 2, 4-dichlorophenol and 2, 4, 6-trichlorophenol. Photodegra-dation of these four compounds in aqueous solution followed first-order when they wereirradiated in a Pt/TiO₂-coated photoreactor. The apparent first-order rate constants increasedin the order of phenol, 4-chlorophenol. 2, 4-dichlorophenol and 2, 4, 6-trichlorophenol. Addition of H₂O₂ (in 1.9×10^-2mol·L^-1) promoted the photodegradation. The phenols studiedwere almost completely degradated after a certain period of irradiation (λ≥345nm, 1.0～5.0 h) with photodegradation value up to 97% and COD value up to 95%.

Key words: platinum-modified titanium dioxide, photodegradation, phenol, chlorophenol