Graphical abstract. Credit: Journal of the American Chemical Society (2023). DOI: 10.1021/jacs.2c10963
With government agencies, including the U.S. Environmental Protection Agency (EPA), ramping up restrictions on per- and polyfluoroalkyl substances (PFAS) in recent years, technologies to detect and remove these substances from key matrices like drinking water and wastewater have become more important than ever. And while long-chain PFAS are being phased out of many industries, short-chain PFAS, often used as alternatives, pose many of the same health and environmental concerns, and can be even more difficult to remediate due to their higher mobility and hydrophilic properties. A team led by researchers from the University of Illinois Urbana-Champaign have recently designed an electrode that uses a combination of molecular and electrostatic interactions to effectively capture short-chain PFAS from water.
The researchers leveraged molecular dynamics simulations to aid in the design of an electrode material that would facilitate the capture of multiple short-chain PFAS with between four and seven carbon atoms. The optimized electrode chemistry includes fluorine groups in order to enhance affinity with the PFAS through fluorophilic interactions, as well as secondary amine groups that helped modulate the electrochemical interactions enabling the capture – and eventual release – of the short-chain chemicals. A variety of electrode designs were tested in electrosorption experiments, including in experiments involving wastewater samples spiked with low concentrations of PFAS. Liquid chromatography-mass spectrometry (LC-MS) was used to quantify the PFAS remaining in the sample solution after electrosorption treatment.
The team found that the fluorinated electrodes improved the uptake of the shortest-chain PFAS (C5 or shorter) while the secondary amine groups enabled the capture of larger PFAS (C6 or longer). The optimized fluorinated redox-active amine-functionalized copolymer electrodes showed potential as a means of removing a range of short-chain PFAS at relevant concentrations from environmental samples such as wastewater. Additionally, the adsorbed PFAS can be subsequently desorbed from the electrode with an induced electric field, allowing the electrodes to be regenerated and reused. This study was published in the Journal of the American Chemical Society.
“We still have much work to do. Future studies will focus on coupling the electrodes developed in this study with electrochemical degradation methods to ensure removal of these persistent contaminants from the environment,” said corresponding author Xiao Su, a chemical and biomolecular engineering professor at the University of Illinois Urbana-Champaign.