Preparation And Properties Of Modification Nanometer Titanium Dioxide/Attapulgite Photocatalyst

Semiconductor photocatalytic technology is an effective way to solve the problem of water pollution,especially the dye water,it has developed rapidly in recent years.Although titania is non-toxic,environmentally friendly,and stable in light irradiation,it still shows some disadvantages in the practical application,such as the comprehensive utilization of solar energy,the lower yield of photoelectron and hole,the poor adsorption performance and the difficulty of recycling.Therefore,it is significant to improve the photocatalytic activity of titania by modification.In the present thesis,TiO₂/attapulgite composite photocatalyst were prepared by the sol-gel method combined with supercritical drying using attapulgite as support,the aqueous solution of TiCl₄ as raw material,then the doping modification of non-metal and metal elements were applied to the photocatalyst.The composition,morphological properties and catalytic performance of catalysts were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,X-ray photoelectron spectroscopy?XPS?,and nitrogen adsorption-desorption measurements,finally,the photoactivity of composite materials were evaluated by the degradation of different dyes and phenol.The results show that:?1?there are no phase transformation from anatase to rutile about samples after supercritical drying,the specific surface area of materials were increased.The adsorption property of attapulgite is excellent,the quantity of active adsorption sites on the surface of the materials were increased.TiO₂ calcined at different temperatures are all anatase,they have smaller particle size and short clavite structure.The photoactivity of the samples under UV light were evaluated by photocatalytic degradation of methylene blue in aqueous solution.The maximum photodegradation rate was obtained in the samples calcined at 400?,it can reach98.4%under the irradiation of ultraviolet light for 3h.?2?The B-doped TiO₂/attapulgite composite photocatalyst were synthesized by boric acid.When the doping content of B is 2.3%,the maximum photodegradation rate was obtained in the samples calcined at 400?,it can reach99.3%under the irradiation of ultraviolet light.Active species were introduced by B-doping,they form impurity level which can improve the separation of photoelectron and hole.?3?The N-doped TiO₂/attapulgite composite photocatalyst were prepared by urea.The optimal value doping content of N is 5%,the nanoparticles disperse well and show higher phocatalytic activity.After N doped in materials,they exist by replacing lattice oxygen,the defects and impurity level formed by them can broaden the light absorption threshold of materials.?4?The Fe-doped TiO₂/attapulgite nano photocatalyst were prepared by ferric nitrate,the optimal doping content of Fe is 5%,the maximum photodegradation rate was obtained in the materials calcined at 500?.The lattice defects induced by Fe-doping can form shallow trap and prolong the service life of light quantum which improve the photocatalytic activity of samples.?5?The Cu-doped TiO₂/attapulgite composite photocatalyst were synthesized by copper nitrate,the optimal doping content of Cu is 5%,the maximum rate of phenol degradation was obtained in the materials calcined at 500?,it can reach 96.3%under the irradiation of ultraviolet light for 6h,the photocatalytic activity of recycling samples is still high.The risk of photoelectrons and holes of are reduced by Cu doping,and the photoabsorption sideband of catalyst redshift to 427 nm,the band gap of it decrease to 2.90 eV.