CAREER: ERASE-PFAS: Mechanistic Investigation of Thermal Decomposition of Poly- and Perfluoroalkyl Substances in the Soil Environment

全氟烷基物质和多氟烷基物质对土壤和水的污染是国家关注的问题。超过95%的美国人的血液中检测到了某些全氟辛烷磺酸化学物质。土壤对地下水和农作物的质量有很大贡献，它们是人类接触这些化学物质的潜在途径。处理全氟化铵污染的挑战源于它们的化学结构，这种结构导致对环境中的生物降解具有很强的抵抗力。然而，众所周知，森林火灾等热过程会引起土壤中全氟辛烷磺酸化学物质的物理和化学变化。这个职业项目的目标是了解土壤中全氟辛烷磺酸化学物质在热处理过程中的稳定性和分解情况。为了保护人类和生态健康，有必要更深入地了解这些过程，以开发热能技术来清理受全氟辛烷磺酸污染的土壤。这项研究的成功完成将使科学家能够准确预测全氟辛烷磺酸在各种热过程中的分解产物。通过参加土壤化学和物理动手实验，对工科本科生进行培训和加强学习，对社会产生了其他好处。通过外联、会议报告和期刊出版物向公众、补救专业人员和其他利益攸关方传播成果将带来进一步的好处。该项目由CBET环境工程项目和已建立的激励竞争性研究项目(EPSCoR)共同资助。该职业项目的目标是阐明土壤中全氟辛烷磺酸在热处理过程中的转化机理。通过在不同土壤和参考土壤成分中评估不同气相下不同全氟辛烷磺酸的热处理的逐步实验，将确定高温下全氟辛烷磺酸的反应路径。结果将被用来确定土壤性质、全氟辛烷磺酸分子结构和环境大气对退化途径的综合影响；对于评估热处理作为全氟辛烷磺酸污染土壤的潜在修复方法至关重要的信息。这项研究的一个新方面来自于使用一种创新的识别方法，该方法基于飞行时间质谱仪的低碰撞能和高碰撞能下的连续交错扫描。这项研究的成功完成将有助于深入了解各类全氟化肥的热稳定性，加深对森林火灾期间全氟化肥在土壤环境中的去向的理解，并有助于阐明全氟化肥的热分解机理。这一知识具有潜在的变革性，因为在当前的环境命运和传输模型中，全氟辛烷磺酸的高热稳定性是一个隐含的假设。该项目的教育目标是通过本科生参与精心设计的项目来促进对STEM的理解。学生将运用课堂上学到的知识来解决有趣和相关的现实世界问题。国家STEM劳动力的多样性将通过代表不足的群体参与研究而扩大。该项目由CBET的环境工程项目和既定的激励竞争性研究项目(EPSCoR)共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The contamination of soil and water by per- and polyfluoroalkyl substances (PFAS) is a national concern. Certain PFAS chemicals have been detected in the blood of more than 95% of the US population. Soil largely contributes to the quality of groundwater and crops, which are potential human exposure pathways for these chemicals. The challenge of dealing with PFAS contamination results from their chemical structure that leads to strong resistance to biological degradation in the environment. However, thermal processes such as forest fires are known to induce physical and chemical changes of PFAS chemicals in soil. The goal of this CAREER project is to understand the stability and decomposition of PFAS chemicals in soil during thermal treatment. A deeper understanding of these processes is necessary for the development of thermal technologies to clean up soils contaminated by PFAS for the protection of human and ecological health. Successful completion of this research will enable scientists to accurately predict decomposition products of PFAS in various thermal processes. Additional benefits to society result from the training of engineering undergraduates and enhanced learning through participation in hands-on experiments in soil chemistry and physics. Further benefits will accrue from the dissemination of results to the public, remediation professionals, and other stakeholders through outreach, conference presentations, and journal publications. This project is jointly funded by the CBET Environmental Engineering program and the Established Program to Stimulate Competitive Research (EPSCoR).The goal of this CAREER project is to elucidate transformation mechanisms of PFAS in soil during thermal treatment. PFAS reaction pathways at elevated temperatures will be identified through stepwise experiments assessing the thermal treatment of various PFAS classes under different gas phases in various soils and reference soil components. Results will be used to determine the combined effects of soil properties, PFAS molecular structure, and ambient atmosphere on degradation pathways; information critical to assessing thermal treatment as a potential remediation method for PFAS-contaminated soils. A novel aspect of this research arises from the use of an innovative identification approach based on continuously interleaving scans at low and high collision energies of time-of-flight mass spectrometry. Successful completion of this research will yield critical insight into the thermal stability of various classes of PFAS, enhanced understanding of the fate of PFAS in the soil environment during forest fires, and elucidation of mechanisms of thermal decomposition of PFAS. This knowledge is potentially transformative because the high thermal stability of PFAS is an implicit assumption in current environmental fate and transport models. The educational objectives of this project are focused on advancing STEM understanding through the involvement of undergraduate students in well-designed projects. Students will apply knowledge learned in class to address interesting and relevant real-world problems. The diversity of the Nation’s STEM workforce will be broadened through the participation of underrepresented groups in the research. This project is jointly funded by Environmental Engineering program of CBET and the Established Program to Stimulate Competitive Research (EPSCoR).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.