TiO₂/ACF Composite Photocatalytic Preparation And Its Photocatalytic Degradation Property

The special superiority of light catalyst technology exhibited when coped with toxic and hard degradation organic contaminant. Titanium dioxide has many advantages, such as high catalytic activity, chemical stability, non-toxicity, cheapness and easy to get etc. But because of the pure TiO₂ have high band gap, the holes in the valence band are easy to recombine, poor absorption of pollutants, difficult to separate and retrieve in water treatment, which restricts the application of TiO₂. Therefore, in order to improve photocatalytic capability of TiO₂ and develop composite photocatalyst which have higher surface, this thesis focuses on the following works.TiO₂/ACF composite photocatalyst was prepared by powder sintering. The effect of P25 slurry dispersion mode and residence time were investigated. The composite photocatalyst were characterized by SEM and BET.Ca2+ doped titanium dioxide particles (Ca-TiO₂) was prepared by sol-gel method. The effect of n(Ti)/n(Ca),nitric acid amount,calcination temperature,calcination time of the photocatalyst were investigated, the photocatalyst were characterized by XRD,TEM,IR,UV-Vis.Ca-TiO₂/ACF composite photocatalyst was prepared in order to improve TiO₂ photocatalytic reaction area. The effect of residence time were investigated. The composite photocatalyst were characterized by XRD,SEM,BET. The photocatalyst which was prepared in optimal preparation conditions was used to degrade methylene blue in aquaous solution, in which the effects of light way, pH value of initial solution and initial concentration of methylene blue are investigated. The synergistic effect between ACF and nano TiO₂ was proved.The result showed that after doped with calcium, the crystal remained the anatase phase, the absorbtion in the ultraviolet region enhanced, and absorbing boundary produced a red shift. The photocatalytic activity of Ca-TiO₂/ACF composite photocatalyst was the highest when the doped molar content of Ca2+was 0.42at%, the calcinated temperature was 470℃and the calcinated time was 2h. This composite also had better load capacity and load intensity. The synergistic effect between ACF and nano TiO₂ was proved.The Ca-TiO₂/ACF composite photocatalyst had reuse property. It had the better degradation efficiency in alkaline conditions than in acidic conditions. The reaction of photocatalysis degradation to methylene blue is Pseudo first order reaction.