Collaborative Research: ECLIPSE-PFAS: Interfacial Plasma-Liquid Transport and Reactivity with Surfactant Molecules for Efficient PFAS Removal

About This Grant

This award is made in response to Dear Colleague Letter 24-130, as part of the ECosystem for Leading Innovation in Plasma Science and Engineering (ECLIPSE) interdisciplinary program. Clean drinking water is very important, but it is beooming harder to find and keep clean because of pollution from factories and other industries. One type of dangerous pollution is from chemicals called PFAS (short for Per- and Polyfluoroalkyl Substances). These chemicals are made of carbon and fluorine, and even tiny amounts in drinking water can be harmful to people’s health. Because PFAS does not break down easily, they’re sometimes called "forever chemicals." However, scientists have discovered that plasma — a special state of matter made up of energetic gases — might help remove PFAS from water. When plasma touches water that has PFAS in it, it can break the PFAS into smaller and less harmful parts. In some cases, it might even destroy the PFAS completely. This happens because the plasma creates high-energy electrons, light, and ions (charged particles) that react with the PFAS at the surface of the water. The goal of this project is to better understand how plasma interacts with polluted water and how these reactions can be controlled to clean water more effectively. The project results should enable the design of better systems to remove PFAS and other pollutants from water. This project will also help train new scientists and engineers through a program called the US Low Temperature Plasma Summer School, which supports education and training in this technology. The investigation of plasma-water interactions leading to PFAS destruction will be a collaborative experimental and computational effort. The experiments will employ advanced laser diagnostics to measure electric fields and densities of reactant (and product) species in the gas phase and in the near water surface layers. The Electric Field Induced Second Harmonic generation measurements will quantify the effect of energetic electrons on surfaced-enhanced PFAS decomposition by the plasma. The PFAS decomposition and conversion will be monitored in situ, by surface Vibrational Sum Frequency Generation. Individual product species will be identified using high-resolution near-IR Tunable Diode Laser Absorption Spectroscopy. These measurements will be compared with the modeling predictions, to validate the kinetic model and infer the rates of the underlying kinetic processes. The computations will investigate the kinetic processes occurring at the interface of the atmospheric pressure plasma and the water surface, with an emphasis on acceleration of electrons and ions into the water surface. New algorithms to compute distributions of electron and ion energies onto the water surface will be implemented, and reaction mechanisms developed. Following their validation, the models will provide insights to quantities that are difficult to measure experimentally, such as the spectrum of plasma produced vacuum-ultra-violet fluxes onto the water. Although focused on remediation of PFAS from drinking water, the outcome of these investigations will provide guidance to a wide range of plasma-liquid interactions relevant to medicine, chemical conversion and materials synthesis. This project is supported by 1) Process Systems, Reaction Engineering and Molecular Thermodynamics program, 2) Environmental Engineering program and 3) Plasma Physics program, in response to Dear Colleague Letter 24-130, as part of the ECosystem for Leading Innovation in Plasma Science and Engineering (ECLIPSE) interdisciplinary program. 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.