Study Of Preparation Of Sr₁₀Bi₆O_24-y,Sr₆Bi₂O_12-y,Ni-doped Sr₁₀Bi₆O_24-y And Ni-doped Sr₆Bi₂O_12-y And Their Photocatalyti

Environmental pollution and the lack of energy sources are the most serious problems of recent environmental problems in the world. A large number of investigations had been focused on how to solve these two problems. Among various oxide semiconductor photocatalysts, titania appears to be a promising and important prospect for using in environmental purification due to its strong oxidizing power, photoinduced hydrophilicity, nontoxicity and long-term photostability. However, the fast recombination rate of photogenerated electron/hole pairs hiders the commercialization of this technology in a certain extent. Recently, many compounds contained Bi ion have been well known as new photocatalysts, such as Bi₂InNbO₇,Bi₄Ti₃O₁₂,Bi₂Ti_O7,Bi₁₂TiO₂₀,Bi₂WO₆ and BiVO₄. Nevertheless, there are still such inherent limitations as reduced photocatalysts' activity due to high synthesizing temperature and other shortcomings in the preparation process of photocatalysts. Therefore, this thesis, based on new ideas in synthesizing process, mainly focuses on the following research works to prepare highly active photocatalytic materials contained Bi ion:Sr₁₀Bi₆O_24-y and Sr₆Bi₂O_12-y were successfully synthesized by solid-state reaction using Bi₂O₃and Sr(NO₃)₂ as raw materials. Ni-doped Sr₁₀Bi₆O_24-y and Sr₆Bi₂O_12-y were also synthesized. And the samples obtained were characterized by X-ray diffraction(XRD), scan electron microscopy (SEM), X-ray photoelectron spectrum (XPS), and so on.Acid red G was selected to simulate organic dye wastewater which was treated by photocatalytic oxidation using the Sr₁₀Bi₆O_24-y and Sr₆Bi₂O_12-y as photocatalyst. Affect factors, such as catalyst dosage, initial concentration of acid red G solution, etc. Experiments indicated Sr₁₀Bi₆O_24-y photocatalyst which is prepared at 900℃for 2 h shows high photocatalystic activity to photodegrade acid red G under UV irradiation. The degradation rate of acid red G decreases with the increasing of its concentration, but the changes of degradation rate of them were not very visible. And Sr₆Bi₂O_12-y photocatalyst which is prepared at 900℃for 6 h shows high photocatalystic activity to photodegrade acid red G under UV irradiation. The degradation rate could reach 95.8% when the initial concentration of acid red G was 50mg/L. The preliminary research of modification photocatalyst is found that doping low concentration nickel can significantly enhance the photocatalytic activity of Sr₁₀Bi₆O_24-y and Sr₆Bi₂O_12-y, the 0.5wt.% Ni-doped Sr₁₀Bi₆O_24-y and 0.3wt.% Ni-doped Sr₆Bi₂O_12-y show the highest activity but the photodegradation rate of acid red G was found decreased with the increase of the doping concentration.The kinetics of photocatalytic oxidation reactions for acid red G by Sr₆Bi₂O_12-y,Sr₁₀Bi₆O_24-y and Ni-doped Sr₆Bi₂O_12-y,Sr₁₀Bi₆O_24-y were studied. The results show that the reaction belong to the first order kinetics and were coincident with Langmuir-Hinsheluwood (L-H) equation. Through the analysis of UV-Vis spectrophotometer, the mechanism of acid red G degradation was discussed, also, the effects of Ni ions in the photocatalytic reaction were studied in the thesis.In this paper, the compound Sr₁₀Bi₆O_24-y,Sr₆Bi₂O_12-y,Ni-doped Sr₁₀Bi₆O_24-y and Ni-doped Sr₆Bi₂O_12-y were first studied. Many new data and results of them were obtained here, which will help us to do the further research, development and application.