Studies On Photocatalytic Oxidation Of Organic Wastewater By Immobilized TiO₂

This thesis mainly studies the photocatalytic oxidation of organic wastewater by fixed TiO₂ film.Firstly, there was a presentation on the preparation method and process of TiO₂ thin film indetail. Choices were taken among many methods of preparation for TiO₂ thin film and different supporters for thin film, and TiO₂ photocatalytic thin films on fiberglass nets were prepared successfully via the sol-gel method. Morever, we analyzed the factors affected the photocatalytic efficiency by statical experiments of phenol. Such as the number of coating cycle, the heat-treatment temperature, the methods of coating cycle. Experimental results showed that the films in the condition of using 450 ℃ heat-treatment temperature, 5 coating cycle, procumbent 2 beds and the distance between TiO₂ thin film and light sourceis near, after 4 h, the efficiency of phenol is 33.6%, the efficiency of TOC is 76%.Secondly, we modified the properties of the catalysts by doping transition metal ions. And the catalysts of doping Mn (â…¦) were mainly researched. Experimental results showed that the films in the condition of doping Mn (â…¦) 0.25%, using 450℃ heat-treatment temperature, 5 coating cycle, procumbent 2 beds and the distance between TiO₂ thin film and light sourceis near, after 4 h, the efficiency of phenol is 85.1%, the efficiency of TOC is 36.64%. In addition, we compared catalysts of doping Mn (â…¦) with catalysts of doping Ag⁺, and optimized the best.Thirdly, we used phenol as adsorbate, and fiberglass nets as absorbent, studied the contribution from adsorption in the process of the degradation wastewater. In additional, adsorption isotherm curves as well as adsorption isothermal curves were research.Fourly, we used TNT as handle objects, the catalysts of doping Mn (â…¦) as the best catalysts, and considered the rules of dynamic experiments. The effects of the initial TNTconcentration, the initial pH, the dosage of TiC^ thin films, the reaction time on photocatalytic oxidation, additional oxygenants were investigated, and the TNT% TOC degradation efficiency were discussed. The research established that the efficiency of TNT is 97.06%, the efficiency of TOC is 49.54% when the initial TNT concentration is 70 mg/L, the initial pH is 3, the dosage of TiC>2 thin films is 1 bed, the dosage of H2O2 is 1 Qth after 2 h.Finally, on the base of the TNT dynamic experiments, kinttic modles were established forUV. H2C^ UV/Ti(V UV/H2O2^ UV/TiO2/H2O2 systems respectively.