School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, P. R. China.
Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, P. R. China.
Environ Sci Technol. 2024 Oct 22;58(42):19048-19057. doi: 10.1021/acs.est.4c06303. Epub 2024 Oct 9.
Radical-induced disinfection byproduct (DBP) formation is drawing attention with increasing applications of advanced oxidation processes (AOPs). Cl represents one of the extensively generated radicals in AOPs, whose behavior in DBP formation remains unknown. In this study, we found that aromatic structures serve as the main DBP precursors in Cl reactions by employing diverse groups of model compounds. At a typical Cl exposure of 1.2 × 10 M·s, the sum concentrations of 7 regulated aliphatic DBPs (e.g., trichloromethane, chloroacetic acids) are ∼0.10 to 0.48 μM for aromatic precursors and <0.05 μM for aliphatic ones. The DBP formation mechanisms from Cl reactions involved the formation of chlorinated aromatics, radical-induced oxygen incorporation followed by ring cleavage, and the interactions of Cl with ring-cleavage intermediates. In reacting with DOM, Cl reactions produced much fewer aliphatic DBPs (5% of the total organochlorine vs 40% for chlorination) and chloroacetic acids dominated the aliphatic DBPs (usually trihalomethane for chlorination), which can be well interpreted by the precursors and mechanisms proposed. This work comprehensively reveals the precursors, formation patterns, and mechanisms of DBPs during the less-studied Cl reactions, highlighting the importance of eliminating the aromatic structures of DOM before the AOPs.
自由基诱导的消毒副产物（DBP）的形成随着高级氧化工艺（AOPs）的应用越来越广泛而受到关注。Cl 是 AOPs 中产生的广泛存在的自由基之一，但其在 DBP 形成中的行为仍不清楚。在本研究中，我们发现芳香族结构是 Cl 反应中主要的 DBP 前体，通过使用多种模型化合物来研究。在典型的 Cl 暴露量为 1.2×10 M·s 时，芳香族前体的 7 种受管制的脂肪族 DBP（如三氯甲烷、氯乙酸）的总浓度约为 0.10 至 0.48 μM，而脂肪族前体的浓度<0.05 μM。Cl 反应生成 DBP 的机制涉及氯化芳烃的形成、自由基诱导的氧掺入以及随后的环断裂，以及 Cl 与环断裂中间体的相互作用。在与 DOM 反应时，Cl 反应产生的脂肪族 DBP 较少（总有机氯的 5%，而氯化的为 40%），氯乙酸占主导地位（通常为氯化的三卤甲烷），这可以通过提出的前体和机制得到很好的解释。这项工作全面揭示了在研究较少的 Cl 反应中 DBP 的前体、形成模式和机制，强调了在 AOPs 之前消除 DOM 的芳香族结构的重要性。
