| ABSTRACTTiO-based semiconductor photocatalysis technology has been shown to be potentially advantageous for environmental remediation as it may lead to complete mineralization of pollutants at ambient conditions with the use of ultraviolet light as the energy source. However, the large scale application of titanium dioxide as mutual photocatalyst is hampered by the fact that it absorbs only the very small ultraviolet part (3(?)4%) of solar light due to its wide band-gap of 3．2eV.An effective approach to shifting the optical response of TiO from the ultraviolet to the visible spectral range is the doping of TiO with nonmetal and Rare Earth Ions. In this paper, by using La and Ce as Rare Earth Ions , and N and S as nonmetal, many kinds of Rare Earth Ions-nonmetal co-doped TiO samples were prepared by precipitation-doping method. The photocatalytic degradation of Acid Blue 62 was used as model reaction to evaluate the visible light activity of these samples. The sample doped with La and S has the have the maximum photocatalytic activity. The structural and photics properties of such photocatalysts were characterized by UV-Vis DRS, XRD and BET. The results showed: the absorption edge of La/S/TiO shifted remarkably toward longer wavelength, and showed the strongest absorption for visible light. The average grain size 4．6nm for La/S/TiO, and dispersed equably. The sample is composed of anatase and rutile. S doping produced impurity midgap levels, involving the enhancement of visible light activity of TiO. The crystal size of the TiO particles was restrained and resulted in the separation of electrons and hole after the La doped into the crystal lattice. Co-doping with La and S showed a synergistic effect for improving the photocatalytic activity in visible light. As module reaction, the photocatalytic degradation of Acid Blue 62 and Reactive Blue 198 were investigated. The effects of calcining temperature, calcining time and concentration of La on the catalytic activity were evaluated. The photocatalytic properties were also influenced by the catalyst quantity, the initial concentration of the dyestuff solutions and initial pH value of the solutions. The result showed that the optimum preparation conditions and the optimum catalytic conditions for Acid Blue 62 and Reactive Blue 198 respectively were: the calcining temperature being 300(?)and 450(?), calcining time being 2 hour and lhour,and concentration of La being 2．5%, the dosage of catalyst being 1．0g/L and 0．5g/L, the concentration of dyestuff solutions being 50mg/L and 100 mg/L, the acidity of the solution being pH=7．The best decolor rate being 95．88% and 99．83%.At last, the reaction kinetics was studied. The reaction could be described by Langmuir-Hinshelwood equation, and was a pseudo-first-order.The innovations of this work included: (1) preparing several kinds of nonmetal and Rare Earth Ions co-doped TiO by precipitation-doping method, (2) the La/S/TiO photocatalyst has the best visible-light-activity was selected to study in-depth, and discussing the mechanism of the influence induced by La and S doping on photocatalytic, (3) the optimum preparation conditions and the optimum catalytic conditions were ascertained respectively.Xiao Dongchang (Environmental Science) Supervised by Prof. Zhuang Huisheng...
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