Photodegradation of xylene isomers:Kinetics,mechanism,secondary pollutant formation potential and health risk evaluation  

作　　者：Xiaoyan Chen Weikun Zhu Sufen Feng Jiangyao Chen 

机构地区：[1]Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control,Guangdong Technology Research Center for Photocatalytic Technology Integration and Equipment Engineering,Institute of Environmental Health and Pollution Control,Guangdong University of Technology,Guangzhou 510006,China [2]Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control,Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health,School of Environmental Science and Engineering,Guangdong University of Technology,Guangzhou 510006,China

出　　处：《Journal of Environmental Sciences》2024年第2期658-669,共12页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos.42177354 and 21777032);the National Key R&D Program of China (No.2019YFC0214402);the Guangdong Basic and Applied Basic Research oundation (No.2019B151502064)。

摘　　要：Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health risk is still unclear.Here,the photodegradation processes of three xylenes were compared under designed reaction atmospheres and light sources.Xe lamp showed poor photodegradation ability toward xylenes,no matter in N_(2) or N_(2)+O_(2)system,while much higher photodegradation performance of xylenes were obtained under ultraviolet(UV)and vacuum ultraviolet(VUV)irradiation,especially in N_(2)+O_(2)+VUV system,where 97.9%of m-xylene,99.0%of o-xylene or 87.5%of p-xylene with the initial concentration of 860 mg/m^(3) was removed within 240 min.The xylenes underwent three processes of photo-isomerization,photodecomposition and photo-oxidation to produce intermediates of aromatics,alkanes and carbonyls.Among them,the photo-isomerization products showed the highest concentration percentage(e.g.,≥50%in o-xylene system),confirming that photo-isomerization reaction was the dominated photodegradation process of xylenes.Moreover,these isomerized products not only contributed about 97%and91%to the formation potential of O3(OFP)and secondary organic aerosols(SOAFP),but also displayed obvious non-carcinogenic risk,although one of photodecomposition product—benzene showed the highest occupational exposure risk.Therefore,the secondary pollution and health risks of photodegradation products of xylenes were non-ignorable,although the OFP,SOAFP and health risks of the generated products reduced at least 4.5 times in comparison with that of the degraded xylenes.The findings are helpful for the appropriate application of this technology in the purification of industrial organic waste gas.

关 键 词：Isomer aromatics PHOTODEGRADATION Ozone formation Secondary organic aerosols Health risk 

分 类 号：X51[环境科学与工程—环境工程] X820.4