Adsorption of Per- and Polyfluoroalkyl Substances (PFASs) and Other Polar Organic Contaminants on Pristine and Organic-Coated Clay Mineral Surfaces

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Per- and Polyfluoroalkyl Substances (PFAS) are a class of synthetic compounds that have been widely dispersed in the environment. Recent evidence indicates that PFAS can lead to adverse health outcomes in humans. These compounds are being found increasingly in drinking water and soils. These developments have led to numerous legal and regulatory actions regarding their use. Despite numerous studies over the past few decades, there remain significant gaps in our knowledge of the environmental persistence of PFAS. This project aims to gain deep insight into the molecular-scale attachment of PFAS and other organic contaminants to solid surfaces using molecular dynamics simulations on supercomputers. Generalizable knowledge of the affinity of PFAS for solid surfaces has the potential to transform our understanding of the environmental fate of these compounds. Successful completion of the research will lead to better models of environmental persistence of PFAS, and the potential development of novel water treatment and soil remediation technologies to protect human and ecological health. A web-based science gateway will produce visualizations of results for the K-12 and broader educational community, thus increasing the scientific literacy of the Nation.The goal of this project is to understand the adsorption of organic contaminants on pristine and organic-coated smectite clay surfaces. The research focuses on polar or anionic organic contaminants, including many compounds of emerging concern such as per- and polyfluoroalkyl substances (PFAS). These compounds exhibit a more diverse range of functional groups and more complex adsorption behaviors than legacy pollutants such a polychlorinated biphenyls or polycyclic aromatic hydrocarbons. The focus on PFAS is timely and relevant given the acute challenges these compounds pose for site remediation and water treatment. The research will develop a novel computational chemistry methodology that can accurately predict the affinity of polar or anionic organic contaminants for pristine and organic-coated smectite clay surfaces at the molecular scale. Variables include the influence on adsorption of compound structure for a diverse range of 53 compounds, aqueous chemistry, and organic clay surface coatings. This methodology will be validated using laboratory sorption experiments to develop new geochemical modeling tools. The project team will develop a web-based interface that will enable the broader educational community of high school students and teachers to visualize and explore simulation results stored on the high-performance data storage systems at the National Energy Research Scientific Computing Center (NERSC).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.