Research On The Immobilization And Modification Of TiO₂ Photocatalyst

With the advancement and development of human society, people have more and more attached importance to environmental problems. The multiphase photocatalysis for the degradation of contaminations of nano TiO2 is superior. This method has high catalyzed activity, quick disposing rate, no selectivity, complete oxidation and so on. America and Japan are in an advanced level in this research field, and they have made use of this technology of TiO2 photocatalysis for dealing with environmental contaminations. But now, the research level of this technology is limited in the laboratories in China. This thesis includes two parts of work: immobilized TiO2 photocatalysts are prepared and characterized with different materials, and the photocatalytic activities are studied systematically by decomposing toluene in gas-phase. The doped TiO2 photocatalysts are prepared and characterized with Ag+ and Ni2+, the catalytic activities of two doped photocatalysts are compared, the optimal adulteration amounts of two doped catalysts are confirmed, and the denatured mechanism of doped catalysts are discussed according to the result of characterization. Glass, silica gel and active carbon are selected for the catalysts' carrier, the immobilized TiO2 photocatalysts are prepared by sol-gel method. Three immobilized catalysts are characterized by SEM. On the basis of the characteristic results, the TiO2 film immobilized on glass was even and compact. But there were some cracks on the surface of the flake of silica gel and active carbon, especially the surface of silica gel. From the result of catalytic activities, glass does not suit the photocatalysis system as catalyst carrier in gas-phase. Simultaneously, the activity of TiO2/Ac catalyst is maximal compared with the other two catalysts. The Ag/TiO2 and Ni/TiO2 photocatalysts with variable Ag/Ni loadings were prepared by the sol-gel method and their photocatalytic activities were tested using gas-phase toluene degradation as the modal reaction. Two doped photocatalysts were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD) and fluorescence spectra (FS). From the result of the characterization and catalytic activities, it can be seen that the adulterate ions exist in the surface of TiO2 with oxide form. The activity of Ni/TiO2 was superior to Ag/TiO2, and the optimal doping amount of two photocatalysts was 0.4 %( mass percentages of metal ions relative to TiO2). The reason that adulterate catalysts enhance the photocatalytic activity is the adulterate ions accelerate the separate of electron and hole, at the same time reduce the reunite probability of electron and hole, and accordingly enhance the catalytic activity.