| A series of nanometer TiO2 photocatalysts were prepared from the solution of Ti(SO4)2 and Ti(SO4)2 with H2SO4 by hydrolyzation respectively. The effects of the concentration of Ti(SO4)2 and NH3·H2O solution, the time of hydrolyzation, the calcination temperature on the crystallographic form and the size of nano TiO2 photocatalyst were studied. Nanometer TiO2 was characterized by HRTEM, TEM, FS, XRD and determination of N2 adsorption analysis and pore distribution. The particles existed in the form of aggregate with the size of 0.1-2μm which was made up of uniform original grains with the size of 7-25 nm. The products were anatase when the calcination temperature was between 300-700℃.The photocatalytic activity of the series nanometer TiO2 photocatalyst was evaluated by the degradation of Xylenol Orange and Methyl Orange used as probe reaction respectively. The factors such as the initial concentration and pH value of the perylene dye solution, the irradiation time affecting photocatalytic oxidation were discussed in detail. The nanometer TiO2 photocatalyst prepared by the solution of Ti(SO4)2 with H2SO4 and calcinated at 300℃exhibited good photocatalytic activity to degrade Xylenol Orange. The nanometer TiO2 photocatalyst prepared with the solution of Ti(SO4)2 and calcinated at 300-700℃demonstrated good photocatalytic activity to degrade Methyl Orange. The catalyst calcinated at 400℃and 600℃respectively had better photocatalytic activity. When the photocatalyst calcinated at 400℃was used to degrade Methyl Orange, the decoloring rate reached 100% under UV(254nm) radiation for 20 min and sunlight for 90min respectively. When it was used to degrade the perylene dye solution, the removal rate of COD was up to 92.9% under UV (254nm) radiation for 40 min and 91.2% under sunlight for 210min respectively. The photocatalytic process of the degradation of Xylenol Orange solution was examined by ultraviolet-visible photometer and HPLC-MS. The regeneration of the catalyst and the relationship of the fluorescence intensity of the TiO2 with the photocatalytic activity were studied as well. The first order kinetic equation to describe the procedure of photocatalytic degradation of Methyl Orange solution under the sunlight was set up.
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