Collaborative Research: Parabens as a Tool for Interrogating Halogenation in Environmental Systems: Products and Pathways

该项目由化学系环境化学科学项目资助，支持南加州大学（USC）的丹尼尔·麦柯里教授和陶森大学（TU）的约翰·西维和基思·雷伯教授研究与水消毒有关的化学反应。当水用氯消毒时，会发生卤化反应。这种反应可以降低水中有害化学污染物的水平。卤化反应还可以从水中的天然或人造前体产生有毒的氯化副产物。该项目旨在了解这些反应的速率和机制。重点是对羟基苯甲酸酯，它被用作洗发水，乳液和其他消费品的防腐剂。对羟基苯甲酸酯可以作为灰水的成分被冲下淋浴器和水槽的排水管。当灰水被回收时，对羟基苯甲酸酯可以进入饮用水。对羟基苯甲酸酯类似于由于植物物质分解而自然存在于湖泊和河流中的分子。因此，研究对羟基苯甲酸酯如何响应与饮用水处理相关的氯化过程，可以深入了解与其他分子的氯化反应。该研究是作为一个大型研究型大学（USC）和主要的本科院校（TU）之间的合作进行的。该项目还包括南加州大学研究生在TU的教学实习，以及南加州大学TU本科生的暑期研究实习。该团队研究了对羟基苯甲酸酯和其他芳族亲核试剂命运重要的水卤化的基本方面。该项目解决的具体问题包括：（1）在对羟基苯甲酸酯的卤化过程中，痕量、高活性、经常被忽视的卤化物质（如Cl2O和BrCl）的作用是什么？(2)在氯胺化过程中，当含氨的水被氯化时，单个氯胺物种的作用是什么？是一氯胺，占主导地位的氯胺形态，基本上是惰性的？(3)活性卤素消耗的哪一部分导致卤化与氧化以及惰性无机卤化物物质的形成？(4)取代酚（包括对羟基苯甲酸酯）形成卤仿的机理是什么？该研究任务既解决了基本的环境化学问题，也解决了对羟基苯甲酸酯命运的应用问题，特别是在饮用水再利用过程中。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project, funded by the Environmental Chemical Sciences Program within the Division of Chemistry, supports Professors Daniel McCurry of the University of Southern California (USC) and John Sivey and Keith Reber of Towson University (TU) to study chemical reactions related to water disinfection. When water is disinfected with chlorine, halogenation reactions occur. Such reactions can decrease levels of harmful chemical pollutants in water. Halogenation reactions can also generate toxic chlorinated byproduct from natural or man-made precursors in water. This project seeks to understand the rates and mechanisms of these reactions. The focus is on parabens, which are used as preservatives in shampoos, lotions, and other consumer products. Parabens can be washed down the drains of showers and sinks as components of greywater. When greywater is recycled, parabens can enter drinking water. Parabens resemble molecules that are naturally present in lakes and rivers due to the breakdown of plant matter. Therefore, studying how parabens respond to the chlorination process associated with drinking water treatment can lead to insights into chlorination reactions with other molecules. The research is conducted as a collaboration between a large research university (USC) and a primarily undergraduate institution (TU). The project also includes a teaching internship for a USC graduate student at TU, and a summer research internship for a TU undergraduate at USC.The team studies fundamental aspects of aqueous halogenation important for understanding the fate of parabens and other aromatic nucleophiles. Specific questions addressed by this project include: (1) What is the role of trace, highly reactive, often-overlooked halogenating species (such as Cl2O and BrCl) in the halogenation of parabens? (2) During chloramination, when ammonia-containing water is chlorinated, what is the role of individual chloramine species? Is monochloramine, which dominates chloramine speciation, essentially inert? (3) What fraction of active halogen consumption results in halogenation versus oxidation and formation of inert inorganic halide species? (4) What is the mechanism of haloform formation from substituted phenols (including parabens)? The research tasks address both fundamental environmental chemistry questions and applied concerns about the fate of parabens, particularly during potable water reuse.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.