Study On Preparation Of Nano-TiO₂ Photocatalysts And It's Photocatalytic Activity

At recent years, the semiconductor photo-catalytic oxidation technique applied in degradation of environment pollution is one of the researching hotspot by environmental investigator in the whole world; namo-TiO₂ has been the focus of the investigations, particularly because of its advantages of stability, low cost, high photo-catalytic efficiency and extensive application.But at present photocatalyst TiO₂'s appling has such difficulties that TiO₂'s responding spectrum area is narrow and suspended TiO₂ powder's retrieve and reuse are different.In this paper, TiO₂ powder doped different metal ions by hydrolysis method was prepared, the photo-catalytic activity was evaluated by using Rhodamine 6G as an objective degradation organic under UV. XRD shows the TiO₂ powder is anatase phase. TEM shows that the diameter of TiO₂ is about 17.40nm. The result of activity evaluation indicates the photocatalytic activity of TiO₂ powder can be enhanced efficiently by doping with the Ce3+, Sn4+ ,Ag+. Comparing with pure TiO₂ ,their rate of degradation of Rhodamine 6G enhances 15.82%,11.11%,4.43% respectively. It can be seen from UV-VIS spectra of samples that doping with metal ions can expand TiO₂'s responding spectrum area. The result of activity evaluation indicates doped TiO₂ has higher photocatalytic activity than pure TiO₂ powder under sunlight.The TiO₂/zeolite photocatalysts were prepared by natural zeolites using sol-geltechnique in this study. SEM and it's energy spectra shows TiO₂ has loaded on zeolite successfully. XRD indicates TiO₂ loaded on zeolite is anatase phase. TiO₂ loaded on zeolite has higher photocatalytic activity than equivalent pure TiO₂. The reuse ability experiment of TiO₂/zeolite under UV and sunlight shows the TiCVzeolite which was prepared in this paper is easy to recover and has good reuse ability. And the TiCVzeolite has good photocatalysis activity under sunlight.The reaction kinetic laws of the photocatalytic degradation of active black were studied.It was found that the procedure of photocatalytic degradation of active black in both TiO₂ suspension system and TiCVzeolite system follows the first order kinetic relationship.Finally the kinetics of degradation of Rhodamine 6G under UV was studied overTiO₂.The reaction order is defined to be the first, Pre-exponential factor is k₀ = 3.994x 1015 min-1 and the activation energy is E_a= 97.04KJ.mol-1Rhodamine 6G degraded in different time was analyzed by IR and UV-VIS spectra analysis. According to result, the mechanism of Rhodamine 6G degradation is inferred: at first the conjugated radical is destroyed, and Rhodamine 6G changes into N-ethyl hydroxy aniline and phthalic anhydride. Next two aromatic rings are cracked and changes into aliphatic hydrocarbon. Finally Rhodamine 6G photodegradates into H₂O CO₂ and NH3 completely.