Photodegradation of dye pollutants on silica gel supported TiO2 particles under visible light irradiation

In this paper, silica gel supported titanium dioxide particles (TiO2/SiO2) prepared by acid-catalyzed sol–gel method was as photocatalyst in the degradation of acid orange 7 (AO7) in water under visible light irradiation. The particles were characterized by X-ray diffraction, BET specific surface area determination, and point of zero charge measurement. The supported catalyst had large surface area, high thermal stability and good sedimentation ability. The photodegradation rate of AO7 under visible light irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The photodegradation rate of AO7 using 31% TiO2/SiO2 particles was faster than that using P-25 and TiO2 (Shanghai) as photocatalyst by 2.3 and 12.3 times, respectively. The effect of the calcination temperature and the TiO2 loading on the photoactivity of TiO2/SiO2 particles was also discussed.