| Most organic pollutants in aqueous and gaseous state can be oxided or reduced into innoxious minerals without the secondary pollutants. The photocatalytic technology is becoming green purifying environment technology. Recently titanium dioxide has been extensively studied as a photocatalyst. According to the impregnation method and homo-precipitation method , a homo-precipitation coating method without any high temperature treatment was introduced in this study. And some influence factors on the decomposition rate were studied. These included iron content and pH etc. The results indicated that Fe(OH)3/TiO2 catalyst owned high photocatalytic activities, and the decomposition rate of methyl-orange(MO) over 0.05%Fe(OH)3/TiO2 catalyst was about 5 times compared to pure TiO2 in nearly neutral(pH 5~7) solutions. The Fe(OH)3/TiO2 photocatalysis had a strong mineralization ability, and organic pollutants with benzene rings can been mineralized thoroughly. The photocatalysis reaction rate has nothing with the original reacting concentration. That is the character of zero order kinetics. The application condition of Fe(OH)3/TiO2 was mild. The optical pH was weakly acid; and neutral(pH 5~7), at which the corrosion of equipment was small. The photocatalyst can been used circularly. The methyl-orange was used as the substrate compound degradated in this paper. The degradation efficiency and by-product were determined with UV-VIS and GC. The catalytic ability of several types catalysts were evaluated by the degradation efficiency of methyl-orange as the matrix compound. At the same time, the structure and character were measured and studied with TEM,XRD,FT-IR,TG-DSC, UV-VIS and so on. The results indicated that these particles had a core-shell structure, and Fe(OH)3 was deposited onto the surface of pure TiO2. The crystalline structure of TiO2 was unchangeable after modification. And the size of TiO2 particles become a little larger. The Fe(OH)3/TiO2 photocatalyst with homo-precipitation coating method had stronger ability of absorbing visible light. Thus we can see that the absorbing range to visible light of such composited photocatalyst become a little broader. Although BET surface area of 0.05% Fe(OH)3/TiO2 was small in comparison with the pure TiO2, the porosity of it was larger. And the efficiency of MO removal over Fe(OH)3/TiO2 photocatalyst was improved largely. The combined water of Fe(OH)3 was linked with the surface of TiO2 as indicated by FT-IR measurement. This is beneficial to the capture of h+ coming from the excitated TiO2, in order to chang fastly to ·OH. Probably this was the most important that the photocatalytic ability of Fe(OH)3/TiO2 improved mostly. The photocatalysis reactivity of 0.05%Fe(OH)3/TiO2 treated at 250℃for 1h degreased largely, and the photodegrading kinetics of this phoptocatalyst was first order kinetics. Probably the photocatalysis reactivity of photocatalyst degreaded and the photodegrading kinetics become first order kinetics arise out of Fe(OH)3 changed into Fe2O3 with removal of the combined water of Fe(OH)3/TiO2 photocatalyst.. From those, we can see that the united water of Fe(OH)3/TiO2 photocatalyst can largely influence of the photocatalysis reactivity of photocatalyst and the photodegrading kinetics. In a word, The catalytic activities of composited nano-photocatalysts with homo-precipitation coating method were super to pure TiO2 in this paper. And the composited nano-photocatalysts would have good application.
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