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The Nano-TiO₂/Diatomite compound photocatalyst is used to degrade rhodamine B dye wastewater in photochemical reactor. The test result indicates that the rate of photodegradation of rhodamine B is influenced by reactive conditions. The best technical conditions are concentration of rhodamine B solution 10mg/L, ultraviolet light 300W, the compound photocatalyst amount used 1g/L, the pH 5.8, reaction time 20min. Under these conditions the rate of photodegradation of rhodamine B may reach as high as 97.80%. And the efficiency of photodegradation of catalyst only has a little changed in recycling.

The starting nano-TiO₂ feedstock was agglomerated by spray-drying process. Nano-TiO₂ coatings on transparent glasses were prepared by atmospheric plasma spraying (APS). The variation of the anatase content, porosity and grain size with the arc current is investigated extensively. Result shows that the nano-TiO₂ phase is composed of anatase and rutile phase. The content of anatase in the sprayed coatings decreased and the grain size increased with the arc current increasing, and the porosity first increased and then decreased. As-sprayed nano-TiO₂ coatings obtained at the spraying current of 400 A have the best photocatalytic property due to the synergistic effect of the fractions of anatase phase and the rate of porosity.

The goal of this paper is to improve the technical level of preparing composite photocatalysts with SiO₂-supported nano-TiO₂, expand the selection range of SiO₂ carriers, reduce expenses and understand the influence of SiO₂ crystallization behavior. Natural quartz (Q/SiO₂) powder was used as a carrier to prepare a Q/SiO₂-TiO₂ composite photocatalyst by hydrolyzing a butyl titanate solution and performing high-temperature calcination of the hydrolysate. The performance, morphology, structure and mechanism were tested and characterized. In addition, the as-prepared photocatalyst was compared with other amorphous SiO₂ carrier composite photocatalysts. The results showed that the Q/SiO₂ surface of Q/SiO₂-TiO₂ contained a uniform load of TiO₂ with a 26.98% proportion. Anatase-type TiO₂ was mainly present, and the size was 5–10nm. Moreover, Q/SiO₂ and TiO₂ were firmly combined in the form of Si–O–Ti bonds between the interfaces. The degradation rate of Q/SiO₂-TiO₂ to methyl orange solution was 99.59% under UV irradiation for 60min, which was equivalent to that of pure nano-TiO₂. The degradation performance remained stable after four cycles. Compared with other amorphous SiO₂ carriers, Q/SiO₂ exhibited a higher load of TiO₂. Furthermore, Q/SiO₂ played a more significant role in inhibiting the phase transition of TiO₂ to rutile and improving the photocatalytic performance.

With Ti(OBu)₄ as precursor, and HAc as complexing agent, pure and W-doped TiO₂ gelatins were prepared by a sol-gel method. During the process of gel formation, metal ions were dispersed in the porous TiO₂ matrix. Then, powders of nano-TiO₂ and W-doped nano-TiO₂ were prepared by drying, grinding and heat treatment at different temperatures. The grain size and structure of the samples, pure TiO₂ and W-doped, and treated at different temperatures, were studied by X-ray diffraction (XRD), Beckman Coulter Sorption Analysis and TEM. Results showed that, with increasing temperature, the TiO₂ transformed from anatase to rutile and the grain size increased. This transformation and grain growth of TiO₂ could be retarded by doping with W.