Preparation And Photocatalytic Properties Of Anion-modified Titanium Dioxide

Dyes brought human beings a colorful world,but they also caused serious pollution.In the field of photocatalytic pollutants treatment,titanium dioxide dominates due to its excellent performance and compatibility.However,titanium dioxide can only absorb a small part of solar spectrum,and nano-scale titanium dioxide is difficult to be separated and recycle,which limits its application in environmental management.In this paper,TiO₂ is modified by anion doping,and the influence of anion species,dissociation constant,and hydrothermal temperature on structure and performance of TiO₂are studied.Then,the anion doped TiO₂ is calcined for carbon-doped Titania,relation between calcination temperature and photocatalytic activity is studied.Finally,superparamagnetic nanoparticles were used to facilitate the post-treatment separation of anion doping TiO₂,and the structure-performance relation of the catalysts were studied.（1）Preparation and photocatalytic activity of anion-doped titanium dioxide.Tetrabutyl titanate（TBT）is used as titanium source.Formic acid,acetic acid,propionic acid,oxalic acid,hydrochloric acid,nitric acid,sulfuric acid,and phosphoric acid are used as anion precursors and hydrolysis inhibitors.An improved sol-gel method-solvothermal method was used for synthesis of anion-doping TiO₂ nanoparticles.Results indicate that crystalline of anion-doped TiO₂ is anatase.Propionic acid doped titanium dioxide has the best photocatalytic performance.Average particle size of the TiO₂ is 100 nm,and the specific surface area is 188.5 m²/g.The degradation rate of Rh B by propionic acid-dope TiO₂ was60.4%in 180 min,which was 3.4 times that of P25（commercial titanium dioxide,with degradation rate of 17.5%）.The photocatalytic activity remained stable after 8 cycles.（2）Preparation and photocatalytic activity of carbon-doped titanium dioxide.Using tetrabutyl titanate（TBT）as raw material and propionic acid as carbon source precursor,anion-doped modified TiO₂ was prepared by improved sol-gel and solvothermal methods,and then carbon was obtained by high-temperature oxygen-free calcination.Doped with TiO₂.The results show that the photocatalytic activity of propionic acid-doped TiO₂ after high temperature carbonization is 1.6 times that of P25.It shows that carbon doping modification is also an effective means to improve the visible light photocatalytic performance of TiO₂.（3）Preparation and photocatalytic activity of superparamagnetic nanoparticles supported anion-modified TiO₂.Taking Fe₃O₄@Si O₂ with core-shell structure as the core,tetrabutyl titanate（TBT）as the raw material,and propionic acid as the anion precursor,Fe₃O₄ was first prepared by co-precipitation method;then Fe₃O₄ was coated by the improved St（?）ber method to obtain Fe₃O₄@Si O₂ core-shell particles;finally,anion-modified TiO₂ was grown on the surface of Fe₃O₄@Si O₂ by improved sol-gel and solvothermal methods.The morphology,crystal structure and surface functional groups of Fe₃O₄@Si O₂@Pro/TiO₂ were analyzed.The effects of reaction time and solvothermal temperature on TiO₂ loading and visible light photocatalytic performance were investigated by single factor experiments.The results show that the maximum loading of Pro/TiO₂ in the prepared Fe₃O₄@Si O₂@Pro/TiO₂particles is 22.2%,and the formation of Ti-O-Si bonds not only fixes TiO₂,but also enhances its photocatalytic performance.The degradation rate of Rh B within 180 min of photocatalytic reaction was 44.8%.