PHOTODEGRADATION OF PHENOL IN WATER USING SILICA-SUPPORTED TITANIA CATALYSTS

Titania-coated silica microspheres containing 0.5-3.0 theoretical laye rs of TiO2 have been prepared by homogeneous precipitation of TiCl3. A ll these x TiO2-SiO2 materials were characterized by X-ray diffraction and FT-Raman spectroscopy. TiO2 species are distributed on the surfac e as small anatase crystals and possess a titania-like behavior with a performance equivalent to that of bulk TiO2 for the photodegradation of phenol. The fraction of used titania is higher than that on bulk ca talysts and the absorption of the irradiation by excess titania is pre vented. The crystal size of titania particles is critical for optimum performance of the catalyst, since it determines the appropriate surfa ce exposure of titanium sites. A minimum size appears to be required t o efficiently mineralize phenol. (C) 1997 Elsevier Science B.V.