The Fundamental Research On The Preparation,structure And Application Of Visible-light Response Diatomite@?C+TiO₂?Nano-Sized Photocatalyst

TiO₂ photocatalysis technology is a new type of environmental treatmenttechnology,which can be widely used in sewage treatment,air purification,antibacterial and other fields.TiO₂ has become a research hotspot in the field of environmental protection because of its advantages such as non-toxic and harmless,economical price,high photocatalytic efficiency and no secondary pollution.However,there are still many problems in the actual application of TiO₂ photocatalysts.Nano-TiO₂ photocatalysts are easy to agglomerate and have super-hydrophilicity and high dispersion after ultraviolet light,which is difficult to recycle;Anatase TiO₂photocatalyst can only use about 5%of visible light,and its response to visible light is extremely low.In view of the above problems,the use of loading and doping is an effective method.Using refined diatomaceous earth as a carrier,TBOT as a titanium source,andanhydrous CaCl₂ as a barrier for TiO₂ dispersion,a diatomite@TiO₂ composite photocatalyst was prepared by sol-gel method.Experiments show that inorganic barrier agent can make titanium dioxide well dispersed in the surface and pores of diatomaceous earth.When calcined at high temperature,titanium dioxide will undergo crystal transformation,and the crystal form of titanium dioxide is best at550?.The combination of TiO₂ and diatomaceous earth has both physical and chemical bonding,making the combination of the two better.Therefore,the best preparation process is that the mass ratio of TBOT/CaCl₂ is 1:1.25,the calcination temperature is 550?,and the degradation rate of the composite photocatalyst produced is 94.7%.After the composite photocatalyst was recovered and degraded for5 times,the degradation rate of the composite photocatalyst obtained was 88.3%,which was still better than that of the pure TiO₂ photocatalyst.Using TBOT as the titanium source,carbonized glucose as the carbon source,and refined diatomaceous earth as the carrier,the diatomite@?C+TiO₂?composite photocatalyst was prepared by the sol-gel method and the in-situ carbonization method.Experiments show that the addition of Carbon can further reduce the band gap of the composite photocatalyst to 2.74eV.And Carbon has a characteristic adsorption effect on the methylene blue solution,which can significantly improve the adsorption performance of the composite photocatalyst,so that the concentration of the methylene blue solution near the photocatalyst increases,and the catalytic activity of the photocatalyst is improved.Carbon and titanium dioxide are combined by C-O-Ti bond,with good stability.The best preparation process is that the amount of loaded Carbon is 20%,the loaded method is first loaded with Carbon and then loaded with TiO2,and the calcination method is carbon buried method.The degradation rate of the prepared composite photocatalyst is 96.4%.The degradation rate of the composite photocatalyst was 86.3%.