武汉市汽修行业不同环节VOCs排放水平及组分特征

为识别武汉市汽修行业涂装工艺环节废气中VOCs（volatile organic compounds，挥发性有机物）浓度水平及组分特征，采集和分析了武汉市10家典型汽修企业喷（烤）漆房治理设施排放环节、喷（烤）漆环节、调漆环节和刮腻子环节共4个环节的含VOCs废气样品.结果表明:①武汉市10家汽修企业喷（烤）漆房治理设施排放环节的VOCs浓度（82.18 mg/m3）最高，其次是调漆环节、喷（烤）漆环节和刮腻子环节，分别为11.37、7.76和5.57 mg/m3.②喷（烤）漆房治理设施排气环节有组织排放以及喷（烤）漆环节与调漆环节无组织排放的VOCs均以OVOCs（oxygenated volatile organic compounds，含氧挥发性有机物）为主，其占比分别为54.4%、50.8%、43.4%；其次为芳香烃，其占比分别为27.0%、22.9%和24.6%；3个环节排放的VOCs物种中质量分数排名前3位的物种均为乙酸丁酯、间/对-二甲苯和1，2-二氯甲烷.刮腻子环节排放的VOCs物种中以芳香烃和OVOCs为主，质量分数排名前3位的物种为苯乙烯、乙酸丁酯和1，2-二氯甲烷.③喷（烤）漆房治理设施排气筒有组织排放以及喷（烤）漆环节、调漆环节无组织排放的VOCs废气中乙酸丁酯含量均远大于苯、甲苯和间/对-二甲苯的含量，且远高于早期武汉市和其他地区的研究结果.研究显示:喷漆（烤）房排气筒有组织排放的VOCs废气浓度最高，应加强对喷漆（烤）房排气筒有组织排放的关注，提高处理设施的“三率”，加强企业喷（烤）漆房的封闭性管理；各环节VOCs废气中乙酸丁酯含量均最高，可考虑将乙酸丁酯作为汽修行业VOCs源示踪物. 

Emission Levels and Composition Characteristics of VOCs from Different Process Links in Automobile Maintenance Industry in Wuhan City

It is very important to understand the concentration levels and composition characteristics of volatile organic compounds (VOCs) emissions during the painting processes of automobile repair industry in Wuhan City. Hence, ten typical automobile repair enterprises in Wuhan City were selected and gas samples were collected from four different processes of exhaust vent of facility (EV), spray (bake) paint (SBP) process, paint mixing (PM) process and putty scraping (PS) process for VOCs analysis. The VOCs results showed that: (1) The highest VOCs concentration (82.18 mg/m3) was observed at the EV, while the VOCs concentration in the unorganized emission such as SBP, PM and PS was relatively low, being 11.37, 7.76 and 5.57 mg/m3, respectively. (2) The chemical composition of VOCs was dominated by the oxygenated volatile organic compounds (OVOCs) in the processes of EV, SBP and PM, accounting for 54.4%, 50.8% and 43.4% of the total VOCs respectively. Moreover, aromatic hydrocarbons were the second large group, and their proportions in the total VOCs in the EV, SBP and PM processes were 27.0%, 22.9% and 24.6%, respectively. The three highest components of VOCs in three processes were butyl acetate, m/p-xylene and 1, 2-dichloromethane. In addition, aromatic hydrocarbons and OVOCs were the main components of VOCs in the PS, of which styrene, butyl acetate and 1, 2-dichloromethane were the major components. (3) The contents of butyl acetate in the VOCs emission from the processes of EV, SBP and PM were much higher than those of benzene, toluene and m/p-xylene, which was much higher than the previous results in Wuhan City and other regions. Our results indicated that because of the highest concentration of VOCs from the exhaust vent, the efficiency of VOCs collection and treatment in the exhaust system should be improved and the sealing management of the paint spraying and baking room should be strengthened. In addition, butyl acetate has the highest proportion in the VOCs in all gas samples of these processes, and can be used as an indicator for monitoring VOCs emission from auto repair industry. It was recommended to improve the solvent products in auto repair industry to reduce the emission of toxic substances and OVOCs, establish the optimal management of VOCs, and minimize the secondary pollution (i.e., ozone pollution).