Study On Photolysis And Photocatalytic Degradation Of VOCs By Novel Excimer Lamps

Four kinds of excilamps with different wavelengths(Xe Cl*, Kr Cl*, Xe Br* and Kr Br*) were used for photolytic and photocatalytic degradation of volatile organic compounds in gas phase. The effects of gas flow rate, initial concentration and light power on removal efficiency and energy yield were investigated and carbon balance and carbon dioxide(CO2) selectivity were calculated. The gas chromatography mass spectrometry instrument(GC- MS) was used to analyze the byproduct of degradation and the reaction mechanism and degradation pathways are inferred.First of all, Kr Br* and Kr Cl* excilamps were used to directly degradate the organic amine(methylamine and dimethylamine) gases.The experiment results show that the MA and DMA can be degradated by Kr Br*and Kr Cl* excilamps to some extent. The higher initial concentration of organic amine gas results in the higher energy yields. The removal rate increased with the lamp power, but the energy yield first rise then fall. The removal rate, energy and carbon balance and CO2 selectivity all decreased with the gas flow rate increasing. The results of experiment showed that energy yield reached 441.5 g/k Wh for 3520 mg/m3 DMA at input lamp power of 65.1W and gas flow rate of 14.9 m3/h for Kr Br* excilamp. Both carbon balance and the selectivity of CO2 were 83.3% under initial concentration of 2387 mg/m3 and lamp power of 28.7 W.Secondly, Four kinds of excilamps with different wavelengths(Xe Cl*, Kr Cl*, Xe Br* and Kr Br*) were used for removing ethyl acetate in gas phase. Comparisons between three loaded catalysts(Ti O2 loaded on organic film, graphene loaded on organic film, and Ti O2 loaded on mesh) on removal efficiency of ethyl acetate were studied, and the effects of lamp sources, irradiation power and initial concentration on removal efficiency were also investigated. Moreover, irradiation spectrum and power of light sources were determined, and photonic efficiencies under different reaction conditions were calculated. The experimental results showed that removal efficiency of ethyl acetate decreased in the order: Kr Br*>Kr Cl*>Xe Cl*>Xe Br*, while photonic efficiency seems to higher with both Xe Cl* and Kr Br* excilamps. In the presence of catalyst of Ti O2 loaded on organic film, both removal efficiency and photonic efficiency were higher than that with no catalyst, but they presented not so distinct. Photonic efficiency increased with increasing initial concentration and gas flow rate. With Kr Br* excilamp, photonic efficiency of 5.63% was obtained when experiment conditions were set as: irradiation power of 0.76 W, initial concentration of 946 mg/m3, gas flow rate of 600 m L/min.In all, excialmps can effectively degradate methylamine, dimethylamine and ethyl acetate gases. The photocatalytic degradation of ethyl acetate by excimer lamps combined with film loaded Ti O2 catalyst was better. The experimental results can provide valuable information for industrial organic gas treatment.