Preparation Of Carbon Adsorped Tio2- Based Materials And Their Photocatalytic Degradation Of Pollutants In Water

With the development of social economy,many environmental problems?such as wastewater treatment,air purification,etc.?caused by excessive energy consumption have attracted wide attention from governments,experts and scholars all over the world.At present,there are various ways of wastewater treatment,and the most widely used one is membrane separation technology.However,this technology has problems of separate selective separation,limited stability,drug resistance,and heat resistance,and membrane surface contamination.Semiconductor photocatalytic oxidation technology has a wide application prospect in removing organic and inorganic pollutants from air or water due to its advantages of high catalytic efficiency,mild reaction conditions,simple operation and non-selective degradation of pollutants in aqueous solution.In a variety of semiconductor photocatalysts,titanium dioxide?TiO₂?has relatively high quantum yield,low cost and high stability.It has proved to be the most widely used material in photocatalysts.However,TiO₂ has a high carrier recombination rate and no response in the visible light range,which restricts its further application.Therefore,it is of great economic and environmental significance to seek new semiconductor photocatalytic materials with high conversion efficiency or to modify TiO₂ semiconductor.?1?In this paper,using carbon adsorption precipitation method,isopropyl titanate and zinc acetate as raw materials to prepare ZnO/TiO₂ nanocomposite powder;isopropyl titanate and ethyl silicate as raw materials to prepare SiO₂/TiO₂ nanocomposite powder;tetrabutyl titanate and lanthanum acetate as raw materials to prepare La₂O₃/TiO₂nanocomposite powder.These samples were characterized by thermogravimetric analyzer?TG-DTA?,X-ray diffraction?XRD?,transmission electron microscopy?TEM?and ultraviolet visible spectrophotometer?UV-vis?,respectively.The results show that the addition of carbon black during the reaction effectively prevents the agglomeration and sintering of the particles during the preparation,drying and roasting processes.Meanwhile,the prepared powder has high crystallinity,uniform particle dispersion and small particle size.?2?Moreover,methyl orange?MO?aqueous solutions was selected as the target degradant to evaluate the photocatalytic activity of the prepared nanocomposite powders.The photocatalytic degradation results show that the ZnO/TiO₂ composite powder prepared by carbon adsorption precipitation method,and the powder obtained by calcination at 600?has the smallest average grain size of 24 nm and the largest specific surface area of 80.35m²/g.The photocatalytic effect is the best,the degradation rate of methylene blue can reach as high as 96%after 60min under ultraviolet light illumination,which is more than 6 times as that of ZnO/TiO₂ prepared by ordinary precipitation method;The SiO₂/TiO₂ composite powder prepared by carbon adsorption precipitation method,the powder obtained by calcination at 600?has an average grain size of 12 nm and a specific surface area of80.32 m²/g.The methyl orange is almost completely decomposed after 50 minutes under ultraviolet light irradiation,and the degradation rate is as high as 98%,which is more than 4 times as that of pure TiO₂ as a catalyst.The La₂O₃/TiO₂ composite powder prepared by the carbon adsorption precipitation method has the best photocatalytic effect after calcination at 600?.The degradation rate of methyl orange is 92.25%after 60 minutes under visible light illumination,which was more than three times as that of La₂O₃/TiO₂prepared by precipitation method,and the photocatalytic activity was significantly improved.