| As an important photocatalytic material, TiO2 has wide applications in many fields, such as waste water tratement, air purification, antibacterial, solar energy conversion. Titanium oxide has been widely used because it has very low cost, high chemical stability, large suface area, photocatalytic efficient and no secondary pollution. At the same time, TiO2 with distinct also have unique properties and have been extensively investigated in different fields. In this thesis, TiO2 was obtained by using different templates and metallic ion doping. The influences of structures and crystals transition temperature of TiO2 by templates and metallic ion doping have been discussed.Using chitosan as a template, the concentration of chitosan plays a controlling role on the formation of microspheres, and also can promote the transformation to rutile. It's found that chitosan playing the role of chelating agents in the reaction, could promote the combination of Ti-O bond, when added to a certain amount of value, under the action of sequestration and the interaction of the polymer chain itself, affected the titanium dioxide morphology. The enhancement of Ti-O binding force also made crystal transition temperature reduce. When the dosage of chitosan was 1 g, the product had the most regular shape, as spherical particles, diameter about 2.5μm; when the addition amount was 1.5g, rutile phase had emerged at the same calcination temperature.Different structures of TiO2 were obtained by using DBS as surfactant after calcined at high temperature. The results showed that the crystallinity of the product improved greatly by adding DBS. After calcining at 400°C, products generated spherical particles; while the large capillary force made the fibrous or needle-like morphology appear when rised to 500°C. At 600°C, the fibrous particles aggregated together and bonded with each other, leading to the grain grow bigger and forming the stripe structure. Photocatalytic results showed that, photocatalytic degradation rate was the highest at 500°C.Three different morphologies of brookite-type titanium dioxide, nano-tube, fiber assembled spindle, and the petal-shaped titanium dioxide respectively, were prepared in different hydrothermal conditions, using cheap Ti(SO4)2 and sodium acetate as raw materials. XRD analysis revealed that the crystal structure is the relatively pure brookite. The study showed that the morphology of the products was strongly dependent on the hydrothermal temperature, pH value and the concentration of reactants. Brookite nano-tubes were formed at low temperature with moderate concentration of reactants, the petal-shaped titanium dioxide were formed when the temperature is higher; When the concentration of reactants and the temperature were low, fiber assembled spindle was formed. Carboxyl oxygen in the CH3COO- and the coordination of Ti4+ had a critical influence on the morphology of the product, and the mechanism was still under explored. Preparation of brookite titanium dioxide had a higher photocatalytic activity.The metallic ion doping was used to modify TiO2. Nanometer TiO2 was obtained by selecting metallic ion Cr3+, Fe2+, Fe3+, W6+and using the sol-gel method. The crystal transition temperature all reduced by the three metallic ion doping. The grain growth of titanium dioxide obstruction by Cr3+ droping. Photocatalytic results showed that, the degradation rate of methyl orange was best by Cr3+ doping by calcining at 500°C. The degradation to acridine orange and nitrobenzene by Fe3+ doping was better than P25. |
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