Study On The Mechanism Of Photocatalytic Treatment Of Benzene Series

The purpose of this study is to investigate the degradation rate and degradation mechanism of benzene series by photocatalysis technology,so as to provide effective theoretical support for practical applications.The photocatalyst?TiO₂?is prepared by sol-gel method,on this basis,the photocatalyst is loaded on the activated carbon fiber,alumina trioxide and silicon carbide by impregnation method and adhesive method.In addition,the modification experiments of precious metal?platinum and palladium?are carried out.The photocatalysts are characterized by BET,XRD and SEM,and photocatalytic degradation of toluene is carried out,in the end we can get concentration-time map and degradation rate-time map.The catalytic performance of each photocatalyst is evaluated comprehensively,and we can see the optimal carrier is activated carbon fiber and the doping of precious metals improves the catalytic performance to a degree.The result of three factors and three levels of orthogonal test of initial concentration of toluene,lamp distance and light source shows light source has the most impact on the degradation of toluene efficiency and multi-group uv lamps can improve photocatalytic capacity,the second is initial concentration of toluene,and the last is lamp distance.Under several experimental conditions,photocatalytic degradation of benzene series represented by toluene and o-xylene is carried out,and export gas components are detected by using GC/MSD.Degradation of toluene shows that benzaldehyde?C7H6O?,3,5-dimethyl-cyclohexanol(C₈H₁₆O),and diester(C₁₆H₃₀O₄)are detected in addition to undegraded toluene.Degradation of o-xylene shows that in addition to undegraded o-xylene,2-ethyl-hexyl phthalate(C₁₆H₂₂O₄)and dibutyl phthalate(C₁₆H₂₂O₄)are detected,which are isomers and esters.The result shows that the benzene series are not completely degraded,resulting in a variety of macromolecular organics,some of which are isomers,most of which are esters.Using the results of other researchers and combining MCM mechanism and FACSIMILE4 software,we simulates the formation mechanism of a total of 6 products,and the processes are demethylation,methylation,hydrogenation,hydroxyl oxidation,esterification,isomerization and other reactions,in the end large complex organic compounds instead of clean small molecular inorganic compounds are obtained.The degradation rate of photocatalytic degradation of high concentration?>1 000ppm?toluene is generally in the range of 20%⁴0%,and large complex organic compounds are generated.The result shows that photocatalytic technology has certain effects in the application of degrading VOCs,but its products are diverse and complex,so it should be highly valued in the application.