Preparation And Photocatalytic Reactivity Of TiO₂ Nanoparticles Photochemical Catalyst With Broad Band Absorption

Objective:Based on the research on modificated TiO₂ nanoparticles photochemical catalyst,this thesis used the S doped TiO₂ system as its research subject. Using the new synthesis method and marerial, it aimed to optimize the microsructure of TiO₂ and study the photocatalytic degradation mechanism, to expand the band absorption area of photochemical catalyst and raise the catalytic activity in visible light. Besides, using the reaction of TiO₂ nanoparticles photochemical catalyst with broad band absorption degradating the Methylene Blue (MB) as a model, this thesis studied the synergistic effects of ultrasound wave in photocatalytic degradation using visible light and the influence on the efficacy of by various experiment conditions, so as to provide the instructions for the research and application of photochemical catalyst with broad band absorption and provide the experimental basis for effective use of solar energy and degradation of azo organics.contents:(1)Synthesize the modificated TiO₂ nanoparticles photochemical catalyst by coprecipitation-precipitation method.(2) Analysis the characteristics of modificated TiO₂ nanoparticles photochemical catalyst and mechanism of doping of catalyst by XRD, TEM, UV-Vis-DRs, and XPS.(3) Study the using period of modificated TiO₂ nanoparticles photochemical catalyst.(4) Make the photocatalytic degradation reactor with effective catalytic activity and stability. (5) Optimize the reaction system of photocatalytic degradation and study the synergistic effects of ultrasound wave in photocatalytic degradation in visible light and the influence on the efficacy of photocatalytic degradation by various experiment conditions.Results:When the S doped was 2.0% and the catalyst was deadburned under 500℃for 4 hours, the catalyst in visible light had fine catalytic activity and can be used longer. After doped, the crystal form of photochemical catalyst was smaller, the specific surface area was larger, its thermostability had increased, and its energy gap had narroweded. The photoresponse region in visible light had moved about 60nm. In the reaction system of photocatalytic degradation synergiaed with ultrasound wave in visible light, the best reaction conditions of photocatalytic degradation of MB were as follows: initial pH was 9, initial MB was 1×10^-6 mol·L^-1 , catalyst dosage was 4g·L^-1, the best reaction time was 90 minutes and initial H₂O₂ was 4mmol·L^-1.Conclusions:(1) S Doped TiO₂ nanoparticles with broad band absorption can be synthesized by coprecipitation-precipitation method. Many factors had great influence on the modificated effection , such as the deadburning temperature, the deadburning time and the content of S doped. The photocatalytic degradation activity of S-TiO₂ nanoparticles to MB in visible light was obviously higher than that of pure nanoparticles.(2) With the synergistic effect of Ultrasound wave on photocatalytic degradation, the degradation rate of MB in US/VIS/S-TiO₂ system was about 5 times than that of pure nanoparticles. This reaction system can shorten the degradation time, raise the degradation rate, simplify the operation, reduce the cost and extend the prospect.(3)The catalytic activity of US/VIS/S-TiO₂ system can be influenced by many factors, such as pH, MB, catalyst dosage, photocatalytic time and H2O2 density.