真空紫外光解乙苯废气的工艺特性及转化机理研究.docVIP

  真空紫外光解乙苯废气的工艺特性及转化 机理研究# 成卓韦，曾斐，蒋轶锋，陈建孟** 5 10 15 20 （浙江工业大学生物与环境工程学院，杭州，310032） 摘要：采用真空紫外光解（UV185nm）乙苯废气，研究了工艺参数（进气浓度、反应时间、 相对湿度等）对乙苯转化率的影响，并初步考察了该工艺对混合废气的转化特性。结果表明， 光解时间 60s 时，初始浓度 50-200 mg/m3 的乙苯转化率达到 60%以上。反应介质的相对湿 度影响光解体系中臭氧的产生量，进而影响乙苯的转化率，适合乙苯转化的最佳湿度为 55-60%。乙苯的转化机制主要有直接光解、羟基自由基氧化和臭氧氧化三种，其中羟基自 由基氧化贡献最大。建立了不同湿度条件下乙苯浓度和臭氧量之间的动力学模型，较好地预 测了某瞬时时刻乙苯的光解剩余浓度。碳平衡和光解产物分析表明，当湿度 60%时，产物 的水溶性较好，光解时间 30s 时，59.4%的乙苯转化为水溶性的碳，主要的光解产物为乙酰 苯，苯甲酸，邻甲基酚等。 关键词：环境科学；真空紫外光解；乙苯；光解产物；混合废气 中图分类号：X511 Conversion characteristics and mechanism analysis of gaseous ethylbenzene degraded by vacuum ultraviolet photodecomposition CHENG Zhuowei, ZENG Fei, JIANG Yifeng, CHEN Jianmeng (College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032) Abstract: In the present study, a vacuum ultraviolet technology was applied to convert gaseous 25 30 35 ethylbenzene (EB). The effects of process parameters (such as the initial concentration, reaction time, the relative humidity, etc.) on EB conversion were investigated and the conversion characteristics of mixed gaseous mixture were also studied. When the reaction time was controlled at 60s, the conversion efficiency of 50-200mg?m-3 EB arrived over 60%. The relative humidity of reaction media influenced the production of ozone (O3), and thus had an effect on EB conversion; the optimal relative humidity was 55-60%. The conversion of EB resulted from the combination of direct photolysis, hydroxyl radical (OH?) oxidation and O3 oxidation, in which OH? oxidation played a dominant role. The kinetic models including the initial EB concentrations and the produced ozone amounts under different relative humidities were developed to describe their mutual relationships, and the models could better predict the remaining EB concentration at a certain time. Analysis of carbon balance and intermediates suggested that about 59.4% EB could be converted to water soluble intermediates when the relative humidity of reacti