| Currently, the issue of environmental pollution is more and more serious, so environmental cleaning and environmental remediation is an urgent task. Among various techniques for purifying environment, the photocatalytic degradation technology is paid greater attention as a new environment-purifying technique. However, we will continue research and development on improving the photocatalytic efficiency, recovering and reusing the photocatalyst, designing and fabricating reasonable and applied photocatalytic reactor and otherwise, in order that the heterogeneous photocatalysis is widely used for the practical water and air purification. In this dissertation, above-mentioned issues were studied on the base of previous researches. At the same time, the photocatalytic degradation of two kind common air pollutants (chlorinated hydrocarbon and carbonyl compound) was investigated. Some valuable results were obtained, and they will be significative for the practical application of the gas-solid heterogeneous photocatalysis.Firstly, a coupled oxide ZnO-SnO2, which was prepared using the co-precipitation method, was immobilized to porous nickel mesh by coating, and a coupled oxide ZnO-SnO2 supported photocatalyst was prepared. The photocatalytic degradation performance of the supported photocatalyst on gaseous model chemical trichloroethylene (TCE) was investigated in a flow through photocatalytic reactor. Some factor such as the gas flow rate, the relative humidity etc., which influence the photocatalytic conversion efficiencies of TCE, were studied, and the lifetime of the supported photocatalyst also was tested. At the same time, the surface character of the supported photocatalyst during the test was observed by the scanning electron microscope (SEM). It is found that the gaseous photocatalysis over the supported photocatalyst is an efficient method for chlorinated hydrocarbon abatement, and ca.100% conversion was found for TCE with a concentration examined up to 400 ppmv in flow-through dry synthetic gas stream. Moreover, the experiments of repeated run indicated the supported photocatalyst displayed long lifetime, and the deactivation of the supported photocatalyst had not been observed within the 205 h tested period in the present experiment, although the surface of photocatalyst changed greatly during the use of the photocatalyst.Secondly, a coupled oxide ZnO-SnO2 was prepared using the co-precipitation method, ZnSO4-7H2O and SnCl4-5H2O were used as the starting materials and NH3 ?H2O as the precipitant. The coupled oxide was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and UV diffuse reflectance spectrum (DRS). The photocatalytic activity of the coupled oxide was studied using methyl orange as a mode organic pollutant. The relationship between the photocatalytic activity and the microstructure of nanometer coupled oxides was also discussed in the dissertation. Experimental results showed that the coupled oxide mainly consist of nanometer ZnO and SnO2, and they have the same excellent photocatalytic activity as Degussa P25 Ti02 for the degradation of methyl orange (MO). But the photocatalytic activity of the coupled oxides decreases rapidly with the increase of the calcination temperature, and a small amounts of nanometer Zn2SnO4 was formed in the mixture of coupled oxides when the calcination temperature is higher than 700 ℃.Finally, a nano-sized titania (anatase) was immobilized to silica gel in the acetic acid solution by the sol-gel technique and the repeated dip coating method using the tetra-n-butylDoctoral Dissertation, Gangzhou Institute of Geochemistry, Chinese Academy of Sciencestitanate as main raw material and acetic acid as the acid catalyst to prepare a coupled photocatalyst TiC>2/SiO2. Meanwhile the structure and properties of the coupled photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD, BET. The photocatalytic degradation of four carbonyl compounds mixture was carried out by using a coaxial triple-cylinder-type...
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