Optimizing Environmental Perfluoroalkyl Acid Degradation by Elucidating Mechanisms: A Coupled Computational and Experimental Approach

该项目由国家科学基金会化学部环境化学科学计划资助。 Shubham Vyas教授和他的学生研究了全氟烷基酸（PFAAs）在环境中转化的机制。PFAA是合成化学品，用作地毯，纺织品和纸张的涂层以及灭火泡沫。由于PFAAs是非常不活泼的化学物质，它们在环境中是非常持久的化合物。它们还对人类和生态健康构成威胁，例如作为饮用水中的污染物。该项目的总体目标是测试各种化学条件，在这些条件下，人们可以改善PFAAs在水环境中的破坏。与此同时，这种过程的能源需求应该减少。一些本科生和研究生在这个项目期间接受培训，因为他们从事环境化学的多学科研究。此外，研究人员积极使用研究策略和该项目的发现，以达到K-12学生和教育工作者。Vyas教授和他的团队采用了实验和计算相结合的方法来执行这个项目。它们使用两种具有代表性的全氟辛酸，即全氟辛酸和全氟辛烷磺酸。使用密度泛函理论和基于Hartree-Fock的计算的化学计算为实验工作提供了指导。这些实验反复地将发现反馈到化学计算中。这改进了模型，并解释了不寻常的实验结果。Vyas实验室研究了在过渡金属阳离子存在下使用超氧阴离子自由基、羟基自由基和过硫酸根阴离子自由基降解全氟辛酸。这些反应可能是由热或外部光促进的。时间分辨吸收光谱测量提供了活性中间体和光触发反应效率的信息。质谱和色谱测量用于监测反应产物。参加这个固有的跨学科研究项目的学生将获得一套独特的技能，其中包括计算和实验环境化学的元素，为他们未来的职业生涯提供技能。这个项目也被用来作为一种工具，将环境计算化学的概念纳入本科和研究生化学课程。

This project is funded by the Environmental Chemical Sciences Program in the Chemistry Division at the National Science Foundation. Prof. Professor Shubham Vyas and his students investigate the mechanisms by which perfluoroalkyl acids (PFAAs) are transformed in the environment. PFAAs are synthetic chemicals that are used as coating for carpets, textiles and paper, and fire extinguishing foams. Because PFAAs are very unreactive chemicals, they are extremely persistent compounds in the environment. They also pose threats to human and ecological health, for instance as pollutants in drinking water. The overall goal of this project is to test various chemical conditions in which one can improve the destruction of PFAAs in aqueous environment. At the same time, the energy demand for such a process should be reduced. Several undergraduate and graduate students are getting trained during this project as they engage in multidisciplinary research in environmental chemistry. Furthermore, the investigators actively use research strategies and findings from this project to reach out to K-12 students and educators.Professor Vyas and his team employ a coupled experimental and computational approach to carry out this project. They use two representative PFAAs, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS). Chemical computations using density functional theory and post-Hartree-Fock-based calculations provide guidance for experimental efforts. The experiments iteratively feed findings back into the chemical computations. This improves the models and explains unusual experimental findings. The Vyas lab studies the degradation of PFAAs using superoxide radical anion, hydroxyl radical, and persulfate radical anion in the presence of transition metal cations. These reactions are likely facilitated by heat or by external light. Time-resolved absorption spectroscopic measurements provide information on reactive intermediates and the efficiency of light triggered reactions. Mass spectrometric and chromatographic measurements are used to monitor reaction products. Students participating in this inherently interdisciplinary research project acquire a unique skill set that incorporates elements of computational and experimental environmental chemistry, providing them with skills for their future careers. This project is also used as a vehicle to incorporate concepts of environmental computational chemistry into undergraduate and graduate chemistry curricula.