Modification Of Nano-TiO₂ And Fe₂O₃ And Study On Their Photocatalytic Degradation Of Organic Pollutants Under Visible Light

With the rapid economic development,especially the random discharge,causes water pollution to become more and more serious.Heavy metal ions,organic dyes,phenolic substances,antibiotics and other non-degradable pollutants will flow along the groundwater to the lake,the ocean,pollute the water body,and finally it poses a serious threat to human health and even life safety.With the continuous improvement of emission standards,various methods such as membrane separation technology,catalytic technology and adsorption technology for the treatment of organic pollution in water need to be continuously updated.Among them,the photocatalytic in the catalytic technology can directly use sunlight to convert of substances into non-toxic carbon dioxide and water,which has been widely concerned.The core of photocatalytic technology is the preparation of highly efficient photocatalysts.As the most studied photocatalyst,TiO2 has the disadvantages of wide band gap and only response to ultraviolet light.Therefore,a series of nanocomposites based on titanium dioxide and ferric oxide are prepared by simple method and successfully used as photocatalysts.The catalyst is applied to the removal of water-soluble organic pollutants.This paper mainly completed the following works:(1)Black TiO2 with a narrow band gap and the ability to respond to the visible light region can cover the shortage of white TiO2.As a result,black TiO2 was grown in situ in the porous carbon material with high specific surface area.The porous carbon material not only enlarge the surface area of black TiO2,but also acts as an electron acceptor,which could inhibit the recombination of electron-hole pairs.Such hybrid materials showed excellent performance in the photocatalytic degradation of tetracycline,especially 10%BTN@PC.And the degradation effect can reach 90%,which is much higher than that of other reported hybrid materials,such as P25(34%),black Ti02(42%),etc.(2)Considering the electron-deficient properties of the-SO2F group of Ethylsulfonyl fluoride(ESF),it was grafted onto the surface of TiO2 nanorods by silane coupling agent KH550.The experimental results show that methyl orange with low concentration can be removed quickly.TiO2-ESF reached adsorption equilibrium within 5 minutes,and the adsorption efficiency is much better than that of unmodified TiO2.However,the successful graft of ESF inhibited the mobility of electrons and brought a sharp decline in the photocatalytic ability of TiO2.As a result,taking advantage of the excellent carrier mobility of benzothiophene,it was grafted onto the surface of black TiO2 through simple organic reactions,improving the separation efficiency of photogenerated electron-hole pairs.And the experimental result showed that the organic small molecular acid containing benzothiophene had been successfully grafted onto the surface of TiO2.Obviously,the photocurrent of BTN@BQTCH is 2 times higher than that of BTN,proving the success of photocatalytic degradation of tetracycline.(3)The N element of 2,2-bipyridyl dicarboxylic acid can strongly coordinate with Fe atom,so we synthesized a new crosslinking polymer and quickly pre-adsorbed Fe3+ ions(heavy metal pollution),then polymer-doped Fe2O3 hybrid material was prepared through hydrothermal method.Such materials exhibited a strong ability to catalyze the degradation of contaminants,which removed tetracycline by 90%within 4 hours.