Ultrafine TiO₂ Nanoparticles And Their Composites Photocatalyst For Degradation Of Organic Compounds

Industrial wastewater contains a variety of organic pollutants and dyes,which is harmful to water environment and human health.Therefore,it is of great theoretical and practical significance to eliminate organic compounds in wastewater.Photocatalytic oxidation is considered as an effective pathway that is clean,nontoxic,high efficiency,mild reaction conditions,and no secondary pollution,in which the key issue is the development of high-efficiency photocatalytic materials.Among various semiconductors investigated,TiO₂ and g-C₃N₄ attract great public concerns due to their low cost,high photocatalytic performance,and environmentally benign property.However,due to the poor reactivity of TiO₂ in visible light,the particle tend to aggregate,and undistribution in organic solvents.Therefore,the application value is not high in industry.We prepares TiO₂ semiconductor catalysts with high reactivity and dispersion by controlling different conditions,through the combination with g-C₃N₄,increasing the light absorption range of TiO₂ catalyst and the efficiency of photocatalytic degradation of organic pollutants.The content of this paper two parts:?1?The solvothermal method was used to prepare ultrafine TiO₂ nanoparticles,and TiO₂ nanoparticles with different morphological were obtained under controlled conditions to improving the catalytic efficiency and particle aggregation of TiO₂.?2?Using g-C₃N₄ as a carrier,The ultrafine TiO₂ nanorods are loaded on the g-C₃N₄ nanosheets,form a heterostructure between TiO₂ and g-C₃N₄,reduce the bandgap of photocatalysts,broaden the light absorption range of the catalyst,to promoting the effect of the separation photo-generated electrons and holes in the catalyst.Physicochemical properties of the catalysts were characterized by means of numerous analytical techniques,and their photocatalytic activities were evaluated for the photodegration of Rhodamine B and phenol.The relationship between physicochemical properties and photocatalytic performance of the materials has been established.The main results obtained in the thesis are as follows:1.TiCl₃ as a titanium source,the spherical and rod-like TiO₂ ultrafine nanoparticles were obtained by controlling different conditions in a hydrothermal pot.The nanoparticle size is less than 10nm,And through the introduction of surfactants show higher water solubility,disperse it into organic solvents.By comparing the degradation efficiency of different morphologies of the catalyst,The rod photocatalyst TiO₂ nanocatalyst showed higher photocatalytic activity for the degradation of rhodamine B under light irradiation?The conversion of rhodamine B achieve 90%within 25 min of full spectrum?.2.g-C₃N₄ and TiO₂/?x mg?g-C₃N₄?x=90,120,150 mg?containing different contents of g-C₃N₄ were prepared by roasting and solvothermal methods,respectively,Characterization surface area of the TiO₂/g-C₃N₄ photocatalyst is 240-242 m²/g,band gap energy 2.95-3.02 eV,It was proved by TEM and other means that TiO₂ nanorods?1-8nm?were evenly dispersed on the surface of g-C₃N₄.The degradation experiment shows that 120mg TiO₂/g-C₃N₄ photocatalyst shows the highest photocatalytic activity for Rhodamine B degradation under visible light irradiation?degradation of rhodamine B achieve 90%in 12 min under visible light?.The excellent photocatalytic activity of TiO₂ NR/g-CN NS is related to its unique two-dimensional layered structure,TiO₂/g-C₃N₄ heterogeneous junction structure,high surface adsorbed oxygen concentration and effective separation of light electron and hole.