Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province, China.
Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province, China.
Sci Total Environ. 2024 Mar 1;914:169860. doi: 10.1016/j.scitotenv.2023.169860. Epub 2024 Jan 8.
Halobenzoquinones (HBQs) are a class of disinfection byproducts with high cytotoxicity and potential carcinogenicity, which have been widely detected in chlorination of drinking water and swimming pool water. However, to date, the formation of HBQs upon ozonation and the HBQ precursors have been overlooked. This study investigated the formation of chlorinated and dechlorinated HBQs from six dichlorophenol (DCP) isomers. The monomeric and dimeric HBQs were identified in all the ozonation effluents, exhibiting 1-100 times higher toxicity levels than their precursors. The sum of detected HBQs intensity had a satisfactory linear relation with the maximum toxic unit (R = 0.9657), indicating the primary toxicity contribution to the increased overall toxicity of effluents. Based on density functional theory calculations, when ozone attacks the para carbon to the hydroxyl group of 2,3-DCP, the probability of producing chlorinated HBQs is 80.41 %, indicating that the para carbon attack mainly resulted in the formation of monomeric HBQs. 2,3-dichlorophenoxy radicals were successfully detected in ozonated 2,3-DCP effluent through electron paramagnetic resonance and further validated using theoretical calculation, revealing the formation pathway of dimeric HBQs. The results indicate that chlorinated phenols, regardless of the positions of chlorine substitution, can potentially serve as precursors for both chlorinated and dechlorinated HBQs formation during ozonation.
卤代苯醌（HBQs）是一类具有高细胞毒性和潜在致癌性的消毒副产物，已广泛存在于饮用水氯化和游泳池水氯化过程中。然而，迄今为止，臭氧化过程中 HBQs 的形成及其前体物尚未得到重视。本研究考察了六种二氯苯酚（DCP）异构体生成氯化和脱氯化 HBQs 的情况。在所有臭氧化产物中均鉴定出了单体和二聚体 HBQs，其毒性水平比前体物高 1-100 倍。所检测到的 HBQs 强度总和与最大毒性单位呈良好的线性关系（R=0.9657），表明主要毒性贡献是导致废水整体毒性增加的原因。基于密度泛函理论计算，当臭氧攻击 2,3-DCP 羟基的对位碳时，生成氯化 HBQs 的概率为 80.41%，表明对位碳攻击主要导致单体 HBQs 的形成。通过电子顺磁共振成功检测到臭氧化 2,3-DCP 产物中的 2,3-二氯苯氧自由基，并通过理论计算进一步验证，揭示了二聚体 HBQs 的形成途径。结果表明，氯化酚无论取代氯的位置如何，都有可能在臭氧化过程中作为氯化和脱氯化 HBQs 形成的前体物。
