Removal Of Toluene By UV Coupling Catalytic O₃ Oxidation

The pollution caused by VOCs has seriously affected the environment where we live.Toluene,a representative of VOCs,is widely applied in various industries such as decoration,chemical industry,and pharmaceutical industry.It is urgent to explore the degradation methods of toluene in order to reducing the harm which can cause pollution to the atmosphere.In this study,coupling techniques of vacuum ultraviolet photolysis and O3 oxidation are adopted to investigate the degradation methods of toluene.UV185mn+254nm was chosen as light source in technology of UV degradation,with the conditions of air flowrant 4-7 L/min,RH 85%,toluene concentration of less than 100 mg/m3,UV lamp power of 40W.The results showed that the degradation of toluene was more than 95%.The results showed that Al2O3 was the optimum carrier and the optimal performance of catalyst was obtained when active component of Mn,Ce,and Mg were loaded by one-step method.The catalyst displayed different catalytic performance in the order of 0.5%Mn>1%Mn>5%Mn when different amount of Mn was loaded.The characterization results of XRD and XPS showed that 0.5%of Mn content was benefit to the formation of MnCeOx with good disparity and increased Ce3+/Ce4+.The optimum catalyst was used to the technology of catalyze O3 oxidation,with the conditions of toluene concentration 100 mg/m3,O3 concentration 171 mg/m3,RH between 48%and 62%,and air flowrant less than 7 L/min.The results showed that the degradation of toluene reached more than 85%.After running a long time with O3 in the concentration of 514 mg/m3,the degradation of toluene reached 100%and selectivity of CO2 reached 64%.In the coupling techniques,some H2O was consumed and the rest,which was right in the range of 48%-62%,was treated in the following step.And the degradation of toluene reached 100%when the concentration was less than 100 mg/m3.The selectivity of CO2 reached 90%after an enhancement by 30%compared with individual technology.