Department of Environmental Health and Engineering, Johns Hopkins University , 313 Ames Hall, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Institute of the Environment and Sustainability, University of California, Los Angeles , La Kretz Hall, 619 Charles E. Young Drive East #300, Los Angeles, California 90024, United States.
Environ Sci Technol. 2016 Dec 20;50(24):13291-13298. doi: 10.1021/acs.est.6b03539. Epub 2016 Dec 6.
The aqueous chlorination of (chloro)phenols is one of the best-studied reactions in the environmental literature. Previous researchers have attributed these reactions to two chlorine species: HOCl (at circum-neutral and high pH) and HOCl (at low pH). In this study, we seek to examine the roles that two largely overlooked chlorine species, Cl and ClO, may play in the chlorination of (chloro)phenols. Solution pH, chloride concentration, and chlorine dose were systematically varied in order to assess the importance of different chlorine species as chlorinating agents. Our findings indicate that chlorination rates at pH < 6 increase substantially when chloride is present, attributed to the formation of Cl. At pH 6.0 and a chlorine dose representative of drinking water treatment, ClO is predicted to have at best a minor impact on chlorination reactions, whereas Cl may contribute more than 80% to the overall chlorination rate depending on the (chloro)phenol identity and chloride concentration. While it is not possible to preclude HOCl as a chlorinating agent, we were able to model our low-pH data by considering Cl only. Even traces of chloride can generate sufficient Cl to influence chlorination kinetics, highlighting the role of chloride as a catalyst in chlorination reactions.
（氯代）酚的水相氯化是环境文献中研究得最多的反应之一。先前的研究人员将这些反应归因于两种氯物种：HOCl（在近中性和高 pH 值条件下）和 HOCl（在低 pH 值条件下）。在本研究中，我们试图研究两种在很大程度上被忽视的氯物种 Cl 和 ClO 在（氯代）酚氯化中的可能作用。系统地改变溶液 pH 值、氯离子浓度和氯剂量，以评估不同氯物种作为氯化剂的重要性。我们的研究结果表明，当存在氯离子时，pH 值 < 6 的氯化速率会大幅增加，这归因于 Cl 的形成。在 pH 值为 6.0 且氯剂量代表饮用水处理时，预计 ClO 对氯化反应的影响最小，而 Cl 可能根据（氯代）酚的特性和氯离子浓度对总氯化速率的贡献超过 80%。虽然不能排除 HOCl 作为氯化剂的可能性，但我们仅通过考虑 Cl 就可以对我们的低 pH 值数据进行建模。即使痕量的氯离子也可以产生足够的 Cl 来影响氯化动力学，这突出了氯离子在氯化反应中作为催化剂的作用。
