Preparation, Characterization And Photocatalytic Activities Of Bi-Ti-O Serial Semiconductor

Nowadays, the global environment pollution is getting more and more serious. The utilization of semiconductors in heterogeneous photocatalysis to solve the problem becomes a very important research hot spot in pollutants treatment. Especially in water purification concerns the oxidation of organic substrates which are poisonous or difficult to degrade, the semiconductors have unique advantages. But the problem which limits its practical application is also obvious. The use of single semiconductor usually cannot meets actual needs due to the low quantum efficiency. In order to overcome the shortcoming, many attempts such as ion doping and semiconductor combining have been made. In this thesis, the work mainly involved three aspects:Firstly, a series of Ti-doped Bi2O3photocatalysts with different amounts of titanium were prepared by activated carbon (AC) impregnation-autocombustion method. The as prepared samples were characterized by many different techniques such as XRD, BET, SEM and UV-Vis DRS in order to get their crystal form, specific surface area, morphology and light response. The photocatalytic activities were evaluated by degrading azo dye methyl orange in aqueous solutions as a model wastewater. The photodegradation system was irradiated by a UV light (λmaxx=365nm). The results show that:when the Ti doping is lower than3%(including3%), the main crystal form is Bi2O3. But when Ti doping is more than3%, Bi12Ti02o was also found in the samples. The UV-Vis DRS shows the optical absorption edge shifts towards the shorter wavelength side attributed to the doping of Ti. When the calcination temperature is300℃, and doping with3%(n) titanium, the particles of the sample are in nanometer scopes. It has the best photocatalytic activity, the degradation rate of methyl orange reaches96.4%within120min.Secondly, a series of compound semiconductor with different Bi/Ti molar ratio were prepared by sol-activated carbon (AC) impregnation method. The as prepared samples were characterized by XRD, SEM and UV-Vis DRS. The results show that, with the Bi/Ti molar ratio and the calcination temperature increases, the particle morphologies change greatly because of agglomeration and sintering. The photon adsorption properties are also reduced in ultraviolet band with the rise of calcination temperature, and so is the photodegradation rate of methyl orange.Thirdly, two kinds of nano composite oxide (Bi4Ti3012and Bi2Ti4O11) particles were prepared by sol-gel method. The as prepared samples were characterized by XRD, SEM and TPR. When the calcination temperature is500℃(Bi4Ti3O12) or700℃(Bi2Ti4O11), the particles are in nanometer scopes. The degradation rates of methyl orange are93.5%(Bi4Ti3O12) in120min and97.2%(Bi2Ti4O11) in90min.