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化学学报
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化学学报 ›› 2010, Vol. 68 ›› Issue (23): 2429-2435. 上一篇    下一篇

研究论文

苯乙烯-NOx光照的二次有机气溶胶生成

贾龙1,2，徐永福*,1   

  1. (1中国科学院大气物理研究所 大气边界层物理和大气化学国家重点实验室 北京 100029)
    (2中国科学院研究生院 北京 100049)
  • 投稿日期:2010-04-13 修回日期:2010-06-30 发布日期:2010-07-26
  • 通讯作者: 徐永福 E-mail:xyf@mail.iap.ac.cn
  • 基金资助:

    中国科学院知识创新工程项目

Formation of Secondary Organic Aerosol from the Styrene-NOx Irradiation

Jia Long1,2 Xu Yongfu*,1   

  1. (1 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029)
    (2 Graduate University of Chinese Academy of Sciences, Beijing 100049)
  • Received:2010-04-13 Revised:2010-06-30 Published:2010-07-26

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在烟雾箱内研究了温度为(301±2) K时苯乙烯-NOx-air光照体系生成的二次有机气溶胶(SOA). 分别探讨了高相对湿度(RH＝72%)对SOA的化学组分、数浓度、产率等的影响. 通过长光程傅立叶红外(FTIR)得到苯乙烯-NOx光照体系的气相产物主要有甲醛、苯甲醛、甲酸和CO等. 采用聚四氟乙烯(PTFE)膜对SOA进行富集, 用FTIR对其化学组分进行分析, 推得SOA的主要物种有过氧苯甲酸硝酸酯、苯甲酸羟基苯基甲酯和苯甲酸. 高相对湿度时气相产物中甲酸量显著提高, 同时SOA红外谱图中新增加了苯甲酸, 而酯中的羰基吸收峰却比低相对湿度时降低了, 从而证实了H2O与Criegee双自由基反应生成苯甲酸的路径, 同时也间接地说明了Criegee双自由基与苯甲醛反应生成苯甲酸羟基苯基甲酯的存在. 高相对湿度时SOA的数浓度比低相对湿度时降低了约36%～44%, 但根据在膜上的SOA质量得到高相对湿度时SOA产率比低相对湿度时提高了约40%, 说明高相对湿度增大了SOA的粒子尺度.

关键词: 二次有机气溶胶, 光化学, 烟雾箱, 苯乙烯, 湿度

The formation of secondary organic aerosol (SOA) of the styrene-NOx-air under irradiation at a room temperature of (301±2) K has been investigated in a smog chamber. The effects of high relative humidity (72%) on the chemical components, number concentrations and yield of SOA have been investigated, respectively. The gas-phase products were determined to be formaldehyde, benzaldehyde, formic acid, CO, etc. SOA was collected on the polytetrafluoroethylene (PTFE ) filter and analyzed with FTIR. The main products of SOA were found to be perbenzoyl nitrate, 2-nitrophenol, benzoic acid hydroxy-phenyl-methyl ester, peroxybenzoic acid and benzoic acid. It was found that at high relative humidity, gas-phase formic acid and benzoic acid are considerably increased, and the IR spectrum of SOA reveals a new absorption of benzoic acid, whereas the C＝O absorbance from benzoic acid hydroxy-phenyl-methyl ester is decreased. This confirms the pathway of the reaction between H2O and Criegee biradical to produce benzoic acid hydroxy-phenyl-methyl ester. The SOA number concentration is decreased by about 36%～44% at high RH, whereas the SOA yield obtained from the mass collected by the PTFE membrane is increased by about 40% at high RH, compared with that at low RH, which demonstrates the increase in particle size at high RH.

Key words: secondary organic aerosol, photochemistry, smog chamber, styrene, relative humidity