The Preparation And Characterization Of TiO₂ Nano Photocatalyst

With the development of modern industry, water resource pollution becomes increasingly serious. Many toxic pollutants are very hard to be degraded and have threaten human s survival and development. How to deal with these pollutants has become a global research hot spot. Using photocatalyst to degrade the pollutants is an effective and feasible method. TiO₂ is a typical photocatalyst with advantages of low price, pollution-free, strong stability and great photocatalytic performance. And its photocatalytic efficiency may improve greatly through reasonable modification.Two modification methods were used in this paper for the preparation of TiO₂ nano photocatalyst. The first one:S-doped TiO₂ （S-TiO₂） photocatalyst was synthesized by sol-gel method with tetrabutyl titanate and thiourea as precursors. SEM, EDS and XRD were used to characterize the surface morphology, component, phase and microstructure of S-TiO₂.The effect of the preparation parameters including the molar ratio of S:Ti and calcination temperature （T） on the microstructure and photocatalytic performance were investigated. Results show that the distribution of S in the TiO₂ is uniform. Controlling the doping amount and calcination temperature can affect the particle size of S-TiO₂ nano photocatalyst as well as their photocatalytic activity. The doping of S improves the TiO₂ crystal transition temperature. When the ratio of S:Ti is 1:20, T=500℃, the TiO₂ photocatalyst has the best photocatalytic activity with the particle size of 18 nm.After UV light irradiation for 3 h, the degradation rate of methyl orange reached 99.7%, which is 52.6% higher than that of the pure TiO₂ prepared under the same conditions. The second one:Silica microspheres were first prepared by stober method. Then SiO₂@ZnO/TiO₂ core-shell photocatalyst was synthesized by electrostatic attraction-adsorption phase reaction method. SEM, TEM, XRD and FT-IR were used to characterize the surface morphology, phase constitution and microstructure. Effects of preparation perameters including the ratio of Ti:Zn, pH value and calcination temperature （T） on catalyst performance were discussed at the same time. Results show that the SiO₂ microspheres have smooth surface and uniform size （300 nm）. The Ti:Zn, pH value and T obviously affect the photocatalytic activity of SiO₂@ZnO/TiO₂ core-shell photocatalyst. When the preparation of photocatalyst in Ti:Zn=14:1, pH=9, T=600℃, the sample performances the best photocatalytic activity and the thickness of the coating layer is about 10～30 nm, the TiO₂ particle size is about 10 nm. After UV light irradiation for 4 h, the degradation rate of methyl orange is 97.5%, which is respectively 41.6% and 57.5% higher than those of SiO₂@TiO₂ and SiO₂@ZnO prepared under the same conditions.