Abstract: The composite photocatalysts of TiO₂·Al₂O₃ attached to the hollow glass microbeads were prepared by a Sol gel technique. The photocatalyst was characterized by XRD, TEM, SEM and nitrogen adsorption, and the catalyst’s photoactivity was evaluated by the photodegradation of a organophosphorous pesticide DDW. The results show that the photocatalytic activity is affected by the mole ratio of the composite photocatalysts. The best photocatalyst among those studied 13 the one which has a mole ratio of 97/3(TiO₂:Al₂O₃), and its photoactivity is 1.5 times as that of Degussa P25 TiO₂. The results suggest that the nano particles TiO₂ and the adsorption of TiO₂·Al₂O₃/beads are the primary factors that improve photoactivity, while the calcination conditions and surface area are the second factors.

Key words: TiO₂·Al₂O₃, composite photocatalyst, microbeads, photoactivity