Study On Modification Of Titanium Dioxide Photocatalyst And Its Photocatalytic Characteristics

Since A. Fujishima and K. Honda first reported the photosensitized decomposition of water into hydrogen and oxygen by titanium dioxide (TiO₂) electrode in 1972, a lot of research works have focused on understanding the fundamental processes and on enhancing the photocatalytic efficiency of semiconductor catalysts. The technique of photocatalytic oxidation which utilizes a semiconductor as a catalyst is a new kind of water treatment process with great potential application in water treatment for its good ability to utilize natural resource-solar energy and its outstanding effect on degradation of organic substances.However, the use of conventional photocatalyst that is typically delegated by titanium dioxide results in disadvantages of low quanta efficiency and of separation after the reaction, which confined the industrial application. And different methods including surface modification of TiO₂, support, deposition of heavy metals, the compound semiconductors, the rare elements mixed into TiO₂ were studied abroad and at home.The aim of this dissertation is to initiate the research of the synthesis conditions of titanium dioxide based on Hangjin 2^# clay and the degradation of methylene blue (MB) aqueous solution in order to seek optimal condition and general degradation rules, by which we look forward to building up the base for further research.This thesis mainly consists of six major parts:Part 1: This part systemically reviewed the development and the advantages of the photochemical catalysis material. The application, modification, preparation and carrier research situation of the nanometer TiO₂ photochemical catalysis technology are described in detail.Part 2: After pre-treatment, acid activation, washing and dehydration, Hangjin 2^# clay changed into activated clay. Then the samples were characterized by XRD and FTIR.Part 3: A series of TiO₂ /Hangjin 2^# clay compounds were successfully synthesized by a sol-gel process using Ti (OC4H9)4 and activated clay as raw materials. The composite catalysts were characterized by means of XRD, FTIR, BET, SEM, XPS and TG.Part 4: TiO₂/Hangjin 2^# clay composites have been doped by lithium fluoride (LiF) and strontium (Sr) via sol-gel method. X-ray diffraction (XRD) and Fourier transformed infrared (FT-IR) spectroscopy were used to characterize composites.Part 5: The photocatalytic characteristics of composites were evaluated by measuring decomposition of methylene blue in aqueous solution under UV irradiation.Part 6: Conclusion and prospect.