| Photo-catalytic oxidation technology is a new water treatment technology which is developing gradually in recent years. The titanium dioxides received extensive attention of the researchers since it has been found because of its unique advantages of non-toxic and harmless. But TiO2 can’t be activated by visible light and the recombination rate of electron and holes is high, which limits its application. Researchers tried many methods to modified titanium dioxide, and doping ions and semiconductor compound are two important methods. Recently, there are reports about combing the two methods, for example, the synthesis of N-doped TiO2/ZnO, which has a better performance in the degradation of benzene, toluene and xylene than N-doped TiO2 and TiO2/ZnO.The band gap of ZnTiO3 is 3.06 eV and its valence band and conduction band are close to that of TiO2. Based on TiO2/ZnTiO3 as substrate and the chromium nitrate, sodium molybdate, sodium tungstate as the doping agent, we synthesized Cr or Mo or W doped TiO2/ZnTiO3 and characterized them by XRD, XPS, SEM, UV-Vis and FT-IR.(1)The Cr-TiO2/ZnTiO3 with the ability of been activated by visible light was synthesized by sol-gel method. The size of the particles was about 10-50 nm. We studied the mole ration of materials, the influence of catalyst dosing quantity, the pH of solution and the stability of the catalyst using rhodamine B as the goal pollutant. The catalyst with molar ration of Cr:Ti:Zn=0.0075:1:0.3 has better performance when degraded RhB. And we investigate the effect of initial concentration, optimal catalyst concentration and pH when degrade butyl rhodamine B. Cr-TiO2/ZnTiO3 has better performance than Cr-TiO2 and TiO2/ZnTiO3. The COD was removed 88% while the concentration was 95%, when degradate 50 mg/L RhB in 8 h.(2) The Mo-ZnTiO3/TiO2 was synthesized by sol-gel method using tetrabutyl titanate as titanium source, zinc source of zinc acetate, ethanol as solvent and sodium molybdate as the source of molybdenum. Mo-TiO2/ZnTiO3 has stronger visible light absorption than Mo-TiO2, TiO2/ZnTiO3 and TiO2. With 500 W xenon lamp as light source, rhodamine B solution as simulation of pollutants, we studied the Mo and Zn content, the influence of calcining temperature and concentration of RhB and catalyst. The catalyst is stable. For the degradation of RhB, the rate of Mo-TiO2/ZnTiO3 is higher than Mo-TiO2, TiO2/ZnTiO3. Using Mo-TiO2/ZnTiO3 degradation butyl rhodamine B at pH=4, the degradation rate could reach 89%. (3) We synthesized W-ZnTiO3/TiO2 by sol-gel method and the particles were in nanoscale agent. We examined the influence of calcining temperature, additive ratio of material, catalyst dosing quantity and the stability of the catalyst. The results show the catalyst with molar ration of W:Ti:Zn=0.01:1:0.3 which was calcined at 500℃ had better performance when degraded RhB and it was stable. The best degradation conditions of Mo-ZnTiO3/TiO2 in the degradation of butyl rhodamine B were as follows:the concentration of butyl rhodamine B was 3 mg/L and the catalyst dosing quantity is 0.75 g/L and the initial solution pH was 4. |
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