大气液相环境中典型氯代芳烃与活性氧(ROS)的光致反应机制研究

Combined with high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometer (LC-MS) as analytical methods, the project intends to study of photochemical reaction mechanisms of some representative chlorinated aromatic hydrocarbon with reactive oxygen species (ROS) in the atmospheric aqueous environment by through adopting a series of steady-state photochemical experiments and laser flash photolysis experiments, while various factors which may affect the efficiency of the photolysis or reactions with free radicals will be investigated systematically. Based on the kinetic parameters, the contribution of various reaction channels will be assessed, the impact of environmental factors on transformation of some representative chlorinated aromatic hydrocarbon with reactive oxygen species (ROS) in the atmospheric aqueous environment will be illuminated. The research results will be not only have an important theoretical significance for understanding chlorinated aromatic hydrocarbon conversions in the atmosphere, and will provide useful information to control and remove of chlorinated aromatic hydrocarbon for urban air pollution and regional fog- haze phenomena, but also have an important reference of discipline crossover for air pollution control, environmental chemistry and atmospheric chemistry.

本项目拟利用高效液相色谱(HPLC)、气相色谱-质谱联用仪(GC-MS)与液相色谱-质谱联用仪(LC-MS)等为分析手段，从光化学转化机制入手，采用稳态光化学反应实验和纳秒级瞬态吸收光谱分析技术相结合的方法，以典型氯代芳香烃作为研究对象，探讨其大气液相环境中与活性氧反应的表观反应动力学，依据反应动力学参数评估各种反应通道所占份额，阐明各种环境因素对氯代芳香烃转化规律的影响，建立氯代芳香烃与活性氧在大气液相环境条件下转化的动力学模型。开展这一研究项目，不仅可为了解氯代芳香烃在大气中的转化提供理论依据，也可为我国城市大气污染及区域性雾霾现象的控制提供有益信息。

大气液相为大气环境中的污染物转化提供了良好的液相介质。本项目采用稳态光化学反应实验和纳秒瞬态吸收光谱分析技术相结合的方法，利用GC/MS、LC/MS及HPLC等分析手段，以邻二氯苯(o-DCB)、4-氯联苯(4-PCB)、2-氯苯酚（2-CP）、2,6-二氯苯酚（2,6-DCP）及2,4,6-三氯苯酚（2,4,6-TCP)等代表性氯代芳烃类污染物为研究对象，探讨了典型氯代芳烃类污染物浓度、初始pH值、O2•−与HO•等活性氧物种前体物浓度、氯离子浓度及液滴直径等因素对光致反应产生的影响，并结合激光闪光光解技术分析了其瞬态中间产物性质，提出了其光化学反应机理。实验发现O2•−通过加成到2-CP、2,6-DCP、2,4,6-TCP、4C2MP（4-氯-2-甲氧基苯酚）、4C2AP（4-氯-2-氨基苯酚）的苯氧基自由基（PhO•）的苯环生成加合物PhO-OO−，其反应的二级速率常数分别为 (5.17 ± 0.68) × 109 L mol−1 s−1、(8.39 ± 0.99) × 109 L mol−1 s−1、(9.9 ± 0.9) × 109 L mol−1 s−1、(9.87 ± 0.91) × 109 L mol−1 s−1和 (9.12 ± 0.75) × 109 L mol−1s−1。o-DCB、2,4,6-TCP及4-PCB与HO•自由基的二级反应速率常数分别是(2.69 ± 0.3) × 109 L mol−1 s−1，(9.27 ± 0.2 ) × 109 L mol−1 s−1，(9.0 ± 1) × 109 L mol−1 s−1。大气氧化模型结果表明与活性氧的反应是大气液相中污染物转化的潜在途径。. 本项目从微观反应动力学角度揭示了大气液相中典型氯代芳烃类污染物光化学反应途径，阐明了典型氯代芳烃类污染物与O2•− 及HO•等活性氧自由基在大气液相环境中可能发生的转化反应，可为认识和理解实际大气环境中典型氯代芳烃类污染物的迁移、转化和污染防控提供有益信息。