School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, PR China.
Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong, PR China.
J Hazard Mater. 2021 Apr 15;408:124445. doi: 10.1016/j.jhazmat.2020.124445. Epub 2020 Nov 12.
Chlorinated organic compounds are ubiquitously detected in saline waters. The photochlorination of organic compounds is one possible source, and chlorine radicals originating from other photosensitive substances have been reported to be responsible for organic compounds chlorination in previous reports. In this study, benzo[a]pyrene (BaP) chlorination in 10% acetonitrile/NaCl aqueous solution was initiated by self-sensitization of BaP, while chlorine radicals were not involved in the reaction. After 45 min of photoreaction in four seawater samples, chlorinated product (6-ClBaP) accounted for 10-17% of the fraction of transformed BaP, which was higher than that previously reported. The influences of Cl, pH, humic acid, electron donors, and particulate matter on the formation of chlorobenzo[a]pyrene were systematically investigated. A self-sensitized photochlorination reaction mechanism was proposed as follow: photoexited BaP was activated to singlet state and then transformed to triplet state through inter-system crossing. Then the excited triplet state and oxygen formed [BaP*-O] or [BaP-O] complex, which further reacted with Cl to produce 6-ClBaP.
氯代有机化合物广泛存在于盐水中。有机化合物的光氯化是一种可能的来源，而先前的报道表明，源自其他光敏物质的氯自由基是导致有机化合物氯化的原因。在这项研究中，10%乙腈/NaCl 水溶液中的苯并[a]芘（BaP）氯化是由 BaP 的自敏化引发的，而反应中不涉及氯自由基。在四个海水样本中进行 45 分钟的光反应后，氯化产物（6-ClBaP）占转化的 BaP 分数的 10-17%，高于先前的报道。系统研究了 Cl、pH 值、腐殖酸、电子供体和颗粒物对氯苯并[a]芘形成的影响。提出了一种自敏化光氯化反应机理：光激发的 BaP 被激活到单重态，然后通过系间窜跃转化为三重态。然后，激发的三重态和氧气形成[BaP*-O]或[BaP-O]配合物，进一步与 Cl 反应生成 6-ClBaP。
