ERASE-PFAS: Bottom-up synthesis of polymeric membranes for PFAS sequestration

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Anti-corrosion and anti-stain coatings have been increasingly present in our daily lives facilitating the cleaning of objects and/or materials, slowing down material’s deterioration, and protecting them against chemical or thermal stress. Naturally, as these coatings increase in performance, they become more attractive to the public increasing demand, and thus driving forward their manufacture. One large class of molecules forming part of these coatings are the per- and polyfluoroalkyl substances (PFAS). Several thousands of PFAS have been identified, some of which are made in a very large scale. The inherent chemical properties of PFAS makes them essentially unbreakable when they leak into ecosystems. Unfortunately, the presence of PFAS in drinking water across the U.S. is now well-documented and human ingestion of PFAS has been associated with a number of diseases and cancer. The grand challenge ahead of us is to find ways of removing PFAS from the environment, especially when these substances contaminate drinking water sources. The goal of this project is to develop synthetic membranes capable of filtering water to remove the majority of the PFAS to well below the threshold of 70 parts-per-trillion, as established by the U.S. Environmental Protection Agency. Successful completion of the proposed research will develop the chemical pathways and basic understanding to create high-performing membranes to remove PFAS from water, ultimately with the goal of protecting public health. Additional benefits to society will be accomplished through education and training including the mentoring of two graduate students at Rice University.Per- and polyfluoroalkyl substances (PFAS) are molecules generally composed of 1) an anionic head group, carboxylate or sulfonate; and 2) a fluorinated backbone, which are incredibly resistant to environmental degradation. Their chemical and thermal stability made them ideal substances to use to protect materials from degrading or from events such as fires. Enormous quantities of FPAS were produced until health-related effects initiated the ban of certain species around the turn of the century. However, the large quantity that was produced coupled with their environmental persistence has resulted in widespread contamination of the environment, especially drinking water sources. Documented health risks posed by PFAS to humans include severe malformations in pregnant women, cancer in adults, liver malfunction, thyroid disease, decreased fertility, high cholesterol, and obesity. Given that PFAS have weak affinity and binding towards most chemical adsorbents, the challenge ahead is to design membranes capable of removing them from contaminated water. The overarching goal of this project is to design recognition sites for anionic PFAS, which will be later developed and incorporated into membranes used to filter water that would sequester long- and short-chain PFAS. To accomplish this central objective, the project will 1) design recognition sites embedded within supramolecular scaffolds; 2) synthesize, characterize, and determine the anion binding properties of the most promising scaffolds; and 3) polymerize the most promising architectures via olefinic and/or epoxide functional groups incorporated into the supramolecular scaffold, and test their PFAS sequestration properties in aqueous samples. The successful completion of this project will establish the fundamental parameters to enhance PFAS binding within molecular scaffolds to later translate this knowledge into the design of polymeric filtration materials. Education and outreach activities include creating seminars and hands-on workshops for high school and undergraduate students.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.