Study On The Binding Ability And Photocatalytic Performance Of Nanometer Titanium Dioxide With High Silica Fiber

Nanometer TiO₂ is a kind of excellent photocatalysts, doping with it can improve the photocatalytic activity, and the practicality could be improved by loading and curing nano TiO₂ powder. First, the nano TiO₂ powder doped dysprosium were prepared by sol-gel method using tetrabutyl titanate and dysprosium nitrate as material, and the doping improve its photocatalytic activity. Dy-doped TiO₂ films were prepared on high silica glass-fiber by dip-coating method. Methyl orange solution was chosen as the degradation product, the effects of calcining temperature, calcining time, doping amount on photocatalytic activity of nano TiO₂ powder and properties were investigated in this study. And the effects of calcination temperature, times of loading, pretreatment solution on the photocatalytic activity of TiO₂ thin films were discussed, and the binding ability of TiO₂ thin films and substrates were studied.（1） In the preparation process of nano TiO₂, the rare earth content is 1.3%（nDy/nTi）, the calcination temperature is 550 ℃, the calcination time is 4 h. Under these conditions, the particle size of nano TiO₂ is 20 nm, the BET is 78.45 m2.g-1, the phase ratio of anatase and rutile is 79:21. The initial concentration of methyl orange photodegradation process is 10 mg/L, powder dosage is 1.0 g/L, the degradation rate of Dy/TiO₂ is 92%, while the degradation rate of the powder which is undoped is 47%. It showed that Dy doping can improve the photocatalytic activity of nanometer TiO₂.（2） Through the study of the morphology and photocatalytic activity of nanometer TiO₂ thin films, the optimum preparation process was determined. The rare earth content is 1.3%, coating times is 5 with activation treatment by alcohol solution, calcination temperature is 500 ℃ by one time. Under these conditions, continuous, uniform, compact and mainly composed of anatase TiO₂ thin film was prepared. Under stirring condition, the degradation rate of methyl orange on the film is 98%, higher than the case of tile conditions. After recycled by 5 times, the degradation rate of methyl orange is 86%, which has great value in usecycle.（3） Through the study on the binding properties of nano Dy doping TiO₂ with high silica glass fibersubstrate, the results were shown as follows: In the process of heat treatment, a gradient interface is formed between the TiO₂ precursor and high silica glass fiber substrate through the mutual diffusion, an electric double layer may produced at the interface. And a large number of Si in the substrate diffused to nano TiO₂ precursor film during heat treatment, which combined with Ti by-O- bond. Then the adsorption performance of fiber surfaces in the precursor was improved and a continuous, uniform and compact Dy doping TiO₂ film was formed.（4） The samples were analyzed by X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, Transmission electron microscope（TEM）, et al. The results showed: The doping of Dy inhibited the grain growth and phase transformation of nano TiO₂, and as amorphous oxide entered into TiO₂ lattice gap, then the TiO₂/Dy2O3 hybrid system has been formed. At the same time, the electronic state of TiO₂ was changed by the doping, and a new doping level was formed, the TiO₂ energy band gap was reduced, and the excitation light wavelength was then reduced, so the absorption and utilization of wavelength range were broadened. A large number of defect locations were introduced by Dy doping onto the surface of TiO₂, the recombination of photogenerated electrons and holes were inhibited. while the content of hydroxyl groups on the surface of nano TiO₂ powder were increased, it not only improves the hole utilization ratio, but also generates more highly reactive hydroxyl radicals, which participated in photocatalytic oxidation reaction, and improved the photocatalytic performance of nanometer TiO₂.