| As a new environment-purifying technique, the photocatalysis degradation technology is paid more attention while environment pollution is being more and more serious. Heterogeneous photocatalysis by semiconductors has unique advantages in water pollution control, especially in the treatment of wastewater containing poisonous organic compounds which are difficult to destroy. Aiming at the disadvantages of TiO2 powder, such as difficulty in separation, low using rate of transformation of photocatalytic technology, preparation process of nanoszied TiO2 powder and fixed TiO2 with nano-crystalline have been prepared by the sol-gel processing in this paper.In this thesis, using the tetra-n-butyl titauate as main raw material to prepare the TiO2 photocatalyst with the sol-gel hydrolytic method. The photocatalyst TiO2 was characterized by means of X-ray diffraction (XRD), scan election microscope(SEM), FI-IR and BET area. On this basis, using ultraviolet germicidal lamp with main wavelength of 253.7nm as light source, the contaminants removal efficiency in methyl orange water was study under the treatment of suspended nanosized TiO2 photocatalyst. Infulence of several factors such as temperature, titanium concentration, amount of dispersing agent added and the reaction time on the particle sizes, aggregation and the optimum preparation conditions were studied. The analyzing results showed that the mean diameter is about 10 nanometer, granularity is about 30 micron, and the specific area is 70-100 m2/g. Compared with other TiO2 photocatalyst, this TiO2 photocatalyst is featured by the characteristic of high catalytic activity , high degradation efficiency and low dosage.Another mwans to tackle the problem of separation is supported photocatalyst. Supported method of photocatalyst played a key role on photocatalytic performance. The nano-crystal TiO2 photocatalysts immobilized on flyash micro-sphere were prepared by different methods. The crystal phase and morphology of TiO2/ micro-sphere were investigated by XRD, SEM. The photocatalytic activities of TiO2/ microsphere under different prepared condition was evaluated by degradation of methyl orange.The results showed TiO2/ microsphere catalyst had higher activity for photocatalytic decomposition of methyl orange and the activity was superior to that of TiO2 powder. In addition, innovatively, magnetic photocatalysts, named TiO2/Ni-Ferrite or TiO2/SiO2/Ni-Ferrite were prepared by using Ni-Ferrite as support. This kind of photocatalyst is liable to be separated and recovered. Surface morphology and crystal pattern were investigated by means of SEM and XRD. The results showed that TiO2 directly wraps on the surface of Ni-Ferrite, the photocatalytic activity is low. However, when SiO2 wraps on the surface of Ni-Ferrite at first, and then TiO2 directly wraps on the surface of SiO2, the photocatalytic activity of TiO2/SiO2/Ni-Ferrite is improved.It is complex to study the kinetics for photocatalysis degradation of organic contaminants. Methyl orange of different primary concentration was used as mimic wastewater, with Large TiO2 particles with nano-crystalline in photocatalysis, and the results showed there were great influence of primary concentration. The kinetics of Methyl orange photodegradation is determinated. It is in accordance with langmiur-Hisheshood formula.
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