ECLIPSE-PFAS: Engineering Liquid-phase Plasma Discharge for Complete Destruction of Poly- and Perfluoroalkyl Substances

About This Grant

Poly- and perfluoroalkyl substances (PFAS), also called “forever chemicals,” are a serious problem in water across the United States. These toxic chemicals do not break down naturally, build up in people and animals, and are linked to major health risks. Current water treatment methods cannot destroy PFAS because of their very strong carbon-fluorine bonds. This project will develop and test a new method called Continuous-flow Liquid-phase Plasma Discharge (CLPD). The CLPD system creates powerful chemical reactions in water to break apart PFAS completely, without making new harmful byproducts. If successful, this could be a simple, chemical-free, and low-energy way to clean PFAS from water. The project integrates educational outreach and workforce development components, including new course offerings, research opportunities for high school, undergraduate, and graduate students, and dissemination to stakeholders through professional development resources. This project aims to engineer and investigate a Continuous-flow Liquid-phase Plasma Discharge (CLPD) process designed for the complete defluorination and mineralization of poly- and perfluoroalkyl substances (PFAS) in water. PFAS represent a persistent class of contaminants due to their strong carbon-fluorine (C-F) bonds, which resist conventional chemical and biological degradation, leading to bioaccumulation and significant health concerns. While nonthermal plasma discharge shows promise for degrading recalcitrant pollutants, existing gas-phase plasma approaches cleave carbon-carbon (C-C) bonds in dissolved PFAS, generating shorter-chain perfluoroalkyl acids (PFAAs) like PFBA and PFPeA that resist further degradation but offer limited defluorination. The CLPD process overcomes this limitation by enabling in-situ generation of highly reactive species, particularly hydrated electrons, within the PFAS solution without requiring bulk gas phases. These hydrated electrons can selectively attack and break the strong C-F bonds in the liquid phase without preferentially cleaving C-C bonds, thereby achieving defluorination without producing short-chain intermediates. Preliminary results with CLPD demonstrated 62.8% defluorination of perfluorooctanoic acid (PFOA) with no detectable shorter-chain byproducts within one hour without catalysts or gas, and 99% defluorination of PFAS in aqueous film-forming foam (AFFF) with minimal argon flow and high energy efficiency. The objectives for this project are: a) Establish theoretical modeling of CLPD in PFAS solutions to quantify energy delivery, reactive species generation (focusing on hydrated electrons), and plasma-liquid interactions; b) Investigate the fundamental mechanisms and kinetics governing the interaction of plasma-generated reactive species with PFAS molecules, specifically targeting C-F bond cleavage while avoiding C-C scission; and c) Elucidate the detailed reaction pathways leading to quantitative defluorination and mineralization of PFAS (including long-chain precursors and shorter-chains) under CLPD treatment and define optimal process control strategies. The expected outcomes include theoretical and thermodynamic models for CLPD energy transfer, mechanistic understanding of species-specific defluorination reactions, and optimized process control strategies. These insights will enable the design of plasma-based systems that can be scaled from laboratory to field for real-world PFAS remediation applications. The findings will contribute broadly to the fields of plasma chemistry, environmental engineering, and advanced oxidation/reduction technologies for emerging contaminants. 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.