Tio <sub> 2 </ Sub>-h <sub> 2 </ Sub> The O <sub> 2 </ Sub> Optical Fenton Photocatalytic Activity Of Research

Based on the light stability and high photocatalysis properties, nanometer titanium dioxide has become a highlight to treat many kinds of organic contaminants in waste water.This technology is a promising process for wastewater detoxification.However,only the ultraviolet light which wavelength less than 387nm can be used by TiO₂. The utilization efficiency of solar energy is very low.So people make a lot of changes to expand the light absorption range of TiO₂ to visible region.Most methods that in common using are dye sensitization, semiconductor composition,metal ion doping,nonmetal doping and so on.Three types of TiO₂ powders were employed as TiO₂ photocatalysts in this paper:anatase,rutile and Degussa P25.TiO₂-H₂O₂ photo-Fenton system is formed by surface absorption of H₂O₂ which extend the photoresponse of TiO₂ to visible region.The photocatalytic of TiO₂ and the catalytic reaction mechanism of TiO₂-H₂O₂ photo-Fenton system under visible light irradiation are studied.Fe doping rutile TiO₂ is made on this basis.The main study of this thesis include following:(1)The visible light which wavelength longer than 400nm is used as light source.The photocatalytic of three types of TiO₂ in TIO₂-O₂ and TiO₂-H₂O₂ system are studied when reactive brilliant red X-3B and phenol are used as model contamination.Anatase TiO₂ and P25 have better performance when photodegradation of X-3B in TiO₂-O₂ system. However,phenol can't be photodecomposed by all three types of TiO₂ in this system.Both X-3B and phenol can be decomposed in TiO₂-H₂O₂ photo-Fenton system under visible light irradiation.Rutile TiO₂ has the best activity on photodegradation of phenol in TiO₂-H₂O₂ system and the optimal pH in this system is about 3.(2)The photocatalytic reaction mechanism of TiO₂-H₂O₂ system under visible light irradiation are studied.Analysis test methods like fluorescence spectrophotometer,UV-Vis spectrophotometer,high performance liquid chromatographic are used in the study.The effects of adsorbent CO₃^2- and hydroxyl free radical inhibitor(tert-butyl alcohol and methanol) on photodegradation of phenol and X-3B are studied.Two possible photocatalysis reaction mechanism of TiO₂-H₂O₂ system are proposed.Surface oxidation mechanism:The light absorption ranges of TiO₂ are expanding to visible region after H₂O₂ adsorbed.H₂O₂ can be photodegradated by TiO₂ under visible light irradiation.Reactive materials like surface hydroxyl free radical and O₂·^- are formed on the surface of anatase TiO₂ and the pollutants adsorbed on the surface of anatase are photodecomposed.Solution oxidation mechanism:The adsorption structure of H₂O₂ formed on the surface of rutile TiO₂ can produce hydroxyl free radicals which can dissolve into the solution and react with the pollutants in the solution.(3)Fe doped rutile TiO₂ is made by soakage when FeC₂O₄ used as Fe source.The amount of Fe doped,crystalline structure and the granular of Fe doped TiO₂ are detailed analyzed and tokened.The photocatalytic activity of rutile TiO₂ are remarkably advanced after Fe doped.The catalyst calcined at 673K has the best performance and holding the catalytic activity as the first time used when recycling use of it in the fifth time.