大气液相中对苯二甲酸与氯自由基的光转化反应

文章研究对苯二甲酸(TPA)与氯自由基在大气液相中的光化学转化机理, 利用 355 nm 激光闪光光解实验探究瞬态物种的生长和衰减动力学, 反应产物由气相色谱-质谱联用技术进行分析。激光闪光光解实验测得 $ Cl^{-} $、 $ Cl_{2}\cdot^{-} $与 TPA 反应的二级速率常数分别为 $ 4.04 \times 10^{10} $、 $ 5.49 \times 10^{6} \mathrm{~L}/(\mathrm{mol}\cdot\mathrm{s}) $。TPA 与氯自由基的反应产物主要有对苯醌、2-硝基对苯二甲酸、对氯苯甲酸、2-氯对苯二甲酸和 2,6-二氯对苯二甲酸, 结合激光闪光光解实验可知, TPA 的光转化有形成 Cl- 加合物、脱羧和硝化 3 种反应途径。

In this work, the photochemical transformation mechanism between terephthalic acid (TPA) and chlorine radicals in the atmospheric liquid phase was investigated. The growth and decay kinetics of the transient species were examined using 355 nm laser flash photolysis experiments, and the reaction products were analyzed by gas chromatography-mass spectrometry (GC-MS) technique. Through the laser flash photolysis experiments, the secondary rate constants for the reaction of $ Cl \cdot $ and $ Cl_{2} \cdot^{-} $with TPA were measured to be $ 4.04 \times 10^{10} $ L/(mol·s) and $ 5.49 \times 10^{6} $ L/(mol·s), respectively. The products of reaction were mainly p-benzoquinone, 2-nitro-terephthalic acid, p-chlorobenzoic acid, 2-chloro-terephthalic acid, and 2,6-dichloro-terephthalic acid. Based on the laser flash photolysis experiments, it was found that the photoconversion of TPA involved three reaction pathways: formation of Cl-adducts, decarboxylation, and nitration.