Lu Ying, Wang Se
School of Environmental Science and Engineering, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science and Technology, Nanjing 210044, China.
School of Environmental Science and Engineering, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Chemosphere. 2024 Feb;350:141136. doi: 10.1016/j.chemosphere.2024.141136. Epub 2024 Jan 4.
Tetrabromobisphenol S (TBBPS) is a widely used brominated flame retardant that has attracted environmental concern due to its abundant presence in water. The objective of this study is to systematically analyze the direct photolysis and degradation mechanisms of TBBPS in two different dissociation forms in water, as well as to evaluate their toxicological effects induced by •OH, O, and •NO radicals. The degradation mechanism of TBBPS is investigated with density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, and the toxicity of the degradation products is assessed through toxicological studies. The results of the study indicate that the OH-addition and H-abstraction reactions are favorable pathways for •OH-induced TBBPS degradation. The H-abstraction reaction of TBBPS with •OH was more favorable than the •OH addition reaction. However, in the degradation of TBBPS, the •OH addition reaction was favored over the H-abstraction reaction. Additionally, the indirect photolysis of TBBPS by O and •NO in water was found to be easier for TBBPS compared to TBBPS, with degradation mechanisms involving Br-substitution and NO-addition reactions. The higher E values calculated indicate that the degradation of TBBPS by O and •NO in water has been a secondary reaction. The direct photolysis reaction pathway of TBBPS in water has involved the cleavage of the S1-C7 and S1-C16 bonds. For TBBPS in the S/T states, the primary reaction pathway is the cleavage of the S1-C16 bond, while for TBBPS, the primary reaction pathway is the cleavage of the S1-C7 bond. Furthermore, the computational toxicology results indicate a slight increase in the toxicity levels of most products, highlighting the significance of investigating the degradation byproducts of TBBPS in greater detail.
四溴双酚 S（TBBPS）是一种广泛使用的溴化阻燃剂，因其在水中大量存在而引起环境关注。本研究的目的是系统分析 TBBPS 在水中两种不同解离形式的直接光解和降解机制，以及评估由 •OH、O 和 •NO 自由基诱导的毒理学效应。采用密度泛函理论（DFT）和含时密度泛函理论（TDDFT）方法研究 TBBPS 的降解机制，并通过毒理学研究评估降解产物的毒性。研究结果表明，OH 加成和 H 提取反应是 •OH 诱导 TBBPS 降解的有利途径。TBBPS 与 •OH 的 H 提取反应比 •OH 加成反应更有利。然而，在 TBBPS 的降解中，•OH 加成反应比 H 提取反应更有利。此外，发现水中 O 和 •NO 对 TBBPS 的间接光解比 TBBPS 更容易，降解机制涉及 Br 取代和 NO 加成反应。计算得到的较高 E 值表明，水中 O 和 •NO 对 TBBPS 的降解是二级反应。TBBPS 在水中的直接光解反应途径涉及 S1-C7 和 S1-C16 键的断裂。对于处于 S/T 态的 TBBPS，主要反应途径是 S1-C16 键的断裂，而对于 TBBPS，主要反应途径是 S1-C7 键的断裂。此外，计算毒理学结果表明大多数产物的毒性水平略有增加，突出了更详细研究 TBBPS 降解副产物的重要性。
