The Photocatalytic Degradation Of Organic Contaminants With H₂O₂ By Modified Rutile TiO₂ Under Visible Irradiation

It is necessary to enhance the absorption of TiO2 and increase the efficiency of photocatalysis under visible light because of the characteristic that TiO2 has wide band-gap (Eg>3.2eV) and only the ultraviolet light which has high energy and wavelength less than 380nm can be excited to produce electron-hole.The properties of photocatalytic degradation of atrazine and the photocatalytic reaction mechanism are studied with H2O2 under visible light, when anatase, Degussa P25 and home-made rutile are used as photocatalysts and the organic pollutants atrazine or phenol are used as model contaminations in this paper.The photocatalytic experiments indicate that atrazine can't be photodecomposed by the three types of TiO2 under visible light irradiation and the rutile TiO2 has the lowest activity,howerver, atrazine can be degraded under the condition of Vis/H2O2 by any of the three photocatalysts and rutile form exhibites the best photocatalytic activity.The absorption of H2O2 on TiO2 surface to form active species extends the light absorption range of TiO2 into the visible light region.Moreover,the fluorescence spectrum analysis indicates that the-OH radical free from rutile TiO2 surface can be constantly produced under visible light irradiation with addition of H2O2.the presence of hydroxyl free radical inhibitors (carbonate or bicarbonate) led to a significant decrease in the degradation efficiency of rutile TiO2 The further studies about rutile TiO2 synergizes with the homogeneous system Fe3+/H2O2 to the photodegradate atrazine are completed. The results shows that the photocatalytic efficiency can be improved rapidly in synergetic system and atrazine degradation ratio and COD removal rate reach to 99% and 80% after 4min reaction. Lots of hydroxyl radicals can be detected in this system under the condition of Vis/H2O2.Besides,Fe modifies rutile TiO2 are prepared from rutile TiO2 and FeC2O4,The catalysts are characterized by XRD,BET and UV-Vis,and the calcine process is analyzed.The affecting factors of this catalyst are investigated when atrazine is used as model contamination.The results indicates that atrazine degradation ratio and TOC removal rate reach to 95% and 70% after 60min reaction and the catalyst still has good catalytic activity after recycling with existence of H2O2 under visible light irradiation;Basing on those studies, rutile TiO2 modified by iron and carbon is prepared when the calcination is controlled in argon atmosphere. The properties of phenol degradation by this composite catalyst under visible light irradiation via HPLC,TG-DSC and TOC analysis. The results show that the visible-light catalytic efficency of phenol degradation by the catalyst rutile TiO2 modified by iron and carbon is increased.