The influence of silver additives on titania photoactivity in the photooxidation of phenol

Photodeposition of small amounts of metal silver on the surface of titanium(IV) oxide enhances its photoactivity in phenol decomposition. The applied method of in situ metal photoreduction resulted in preparing better Ag/TiO2 systems than those already described in literature. Optimum silver loading on titania amounts to 0.5 wt%. The photoreaction, which finally leads to total phenol mineralization, proceeds via intermediate compounds. Hydroquinone, benzoquinone and catechol are the main intermediates determined quantitatively. Photooxidation of the compounds competes with the photooxidation of phenol. At higher phenol concentration, >6×104 mol dm3, the rate of the photocatalytic reaction is strongly retarded. The photoreaction was conducted in a specially designed, three-phase fluidal photoreactor.