Kinetics of the photodegradation of substituted phenols by solution combustion synthesized TiO2

A nano-sized, high surface area phase pure anatase TiO2 synthesized by the solution combustion method was used to study the photocatalytic degradation of various chlorophenols and methylphenols. The photocatalytic degradation rates of o-chlorophenol, p-chlorophenol, dichlorophenol, trichlorophenol, pentachlorophenol, o- and m-methylphenol (cresol) under UV exposure were determined using the combustion synthesized TiO2 and compared with the degradation rates with commercial Degussa P-25. The chlorophenols degraded much faster than the methylphenols, which degraded faster than phenol. The photocatalytic activity of combustion synthesized TiO2 was significantly higher than that of Deeussa P-25 under similar conditions. No intermediates were observed when combustion synthesized TiO2 catalyst was used for the photocatalytic degradation of the phenols, while several intermediates were observed for the same reactions catalyzed by Degussa P-25. Because some of the intermediates are toxic, combustion synthesized TiO2 may be more beneficial in environmental catalysis. The mechanisms for the photocatalytic degradation were proposed and the kinetic parameters were determined by regressing the experimental data. (C) 2004 Elsevier B.V. All rights reserved.