Removal Of Toluene And Hydrogen Sulfide By Non-thermal Plasma Coupled With Photocatalyst

As a typical volatile organic compound, toluene was chosen to be decomposed inthis paper by non-thermal plasma coupled with photocatalysis technology. Wire-tubecold plasma reactor was used in the experiment, which BaTiO₃and TiO₂materialswere put into the reacto.The experiment results showed that toluene removal efficiency increased withapplied voltage increasing. Catalyst had distinct advantages in toluene decompositioncompared with empty reactor, and the toluene degradation ability of four reactors wasas follows: BaTiO₃-TiO₂/γ-Al₂O₃catalyst> BaTiO₃/γ-Al₂O₃catalyst> TiO₂/γ-Al₂O₃catalyst> empty tube. When the applied voltage was20kV, the decompositionefficiency of them was69%、44%、43%and35%, and the corresponding energyefficiency was14.7、4.0、3.4and7.7g/kW·h, respectively. Synthetically consideringthe toluene degradation and energy efficiency, the BaTiO₃-TiO₂/γ-Al₂O₃catalyst hadthe best degradation effect of toluene. Futhermore, the BaTiO₃-TiO₂/γ-Al₂O₃catalyst,which BaTiO₃and TiO₂mass ratio of2.38:1was the optimal catalyst. The ability oftoluene degradation effect of non-thermal plasma coupled with photocatalysistechnology was better than non-thermal plasma or photocatalysis alone.The results of orthogonal experiment showed that the effect degree relation offive factors was: catalyst filling length, gas flow rate, applied voltage, frequency anddischarge zone length. The better toluene degradation conditions in our experimentwere: catalyst filling length of220mm, gas flow rate of12.6cm/s, applied voltage of19kV, frequency of350Hz, discharge zone length of100mm, and toluene removalrate could reach82%under these conditions. The results of single factor experimentshowed that toluene removal rate increased with discharge zone length, catalyst fillinglength, applied voltage and frequency increasing, while decreased with gas flow rateincreasing.The products of toluene decomposition were analyzed by GC, GC-MS andFT-IR, and the results showed that there were many by-products besides CO₂andH2O such as derivatives with benzene ring. The results of ozone detectionshowed thatthe ozone concentration in three catalyst reactors increased firstly, and then decreasedwith applied voltage increasing, but the voltage value of the maximum ozoneconcentration was different. The results of SEM and TEM showed that the surfacemorphologies of BaTiO₃and TiO₂did not change during the reaction process. The first toluene decomposition constant of various catalysts were:BaTiO₃-TiO₂/γ-Al₂O₃catalyst> BaTiO₃/γ-Al₂O₃catalyst> TiO₂/γ-Al₂O₃catalyst; andthe BaTiO₃-TiO₂/γ-Al₂O₃catalyst, which BaTiO₃and TiO₂mass ratio of2.38:1hadthe maximum decomposition constant.As a typical malodorous gas, hydrogen sulfide was chosen to be decomposed bynon-thermal plasma technology with power supply （50Hz,0¹00kV） in Beijing XiaoWuji Refuse Transfer Station. The results showed that the maximum of hydrogensulfide removal rate could reach60%. The pilot-scale experiment results indicatedthat the technology had a feasibility of practical application for decomposingmalodorous gas with low concentration.