Photocatalytic degradation of 4-chlorophenol with combustion synthesized TiO₂ under visible light irradiation

Carbon-modified TiO₂ catalysts were synthesized from tetrabutyl titanate and glycine by a solution combustion method. The catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), XPS, UV-vis absorption and photocatalytic degradation of 4-chlorophenol (4-CP). The obtained catalysts show much high activities for degradation of 4-CP than that of Degussa P25 under irradiation at wavelengths longer than 400 nm. Hydroquinone (HQ), benzoquinone (BQ) and hydroxyhydroquinone (HHQ) were found to be the main intermediates of the photocatalytic 4-CP degradation with carbon-modified TiO₂ by HPLC measurement. Moreover, the calcination time of synthesized TiO₂ catalysts played a significant role in the photocatalytic activity.