NSF Award
2427921
This EArly-concept Grant for Exploratory Research (EAGER) project focuses on new fundamental understanding and early technology development related to energy- and cost-saving defluorination of per- and polyfluoroalkyl (PFAS) chemicals. PFAS are harmful to human health and challenging to break down into stable, benign substances. Emerging efforts to remediate PFAS from water resources have been hampered by high cost and high energy requirements. The project utilizes sustainable solar-assisted electrocatalysis enabled by non-precious materials and highly-basic aqueous electrolytes to achieve complete defluorination of PFAS. The insights gained from this EAGER project will provide fundamentally new strategies for designing electrocatalytic anodes and novel electrolytes, thereby advancing technologies for energy- and cost-saving aqueous defluorination of PFAS. In addition to the fundamental mechanistic outcomes, the project will provide support to the investigator’s contributions to electrocatalysis engineering, and integration of the research with undergraduate education and outreach to high-school students.<br/><br/>The project aims to transform aqueous PFAS remediation by providing a fundamentally new quantitative understanding of PFAS defluorination electrocatalysis, while enhancing anode stability, to enable wide-spread use of cost- and energy-effective technology developed in the investigator’s laboratory. The project builds on the investigator’s experience in using pulsed laser liquid-phase synthesis to prepare surfactant-free OH-terminated [NiFe]-(OH)2 nanocatalysts, to ensure well-defined surface conditions in the catalyst microenvironment. Use of hydrophilic carbon fiber paper as the electrode support provides a high anode surface area, to facilitate PFAS adsorption, without restricting mass transport. The project will identify how high concentrations of alkali metal ions, especially Li+, and high basicity aid PFAS defluorination via mechanistic studies in aqueous LiOH electrolytes with systematically varied Li+ or OH- concentrations, while keeping the counter ion concentration constant. In addition, PFAS with different pKa’s (e.g., PFOS, perfluorooctanoic acid, perfluorooctanephosphonate, perfluoroheptan-1-ol, and GenX) - controlled by their sulfonate, carboxylate, phosphonate, and alkoxide headgroups, respectively – will be evaluated with respect to their adsorption properties at the anode and related defluorination efficiency. To enhance anode stability, new approaches will be developed to immobilize surfactant-free [NiFe]-(OH)2 nanocatalysts on hydrophilic carbon fiber paper by maximizing the catalyst–support contact area via sonication and pulsed laser liquid-phase grafting. Taken together, the knowledge gained from the EAGER project will provide fundamentally new strategies for designing anodes and electrolytes, advancing technologies for energy- and cost-saving aqueous defluorination of PFAS.<br/><br/>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.
