Removal of PFAS and other fluorinated organic compounds by electrochemistry in water

Phillip Vershinin, Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel (phillip.vershinin@weizmann.ac.il)
Omri Seemann, Earth And Planetary Sciences, Weizmann Institute Of Science, Rehovot, Israel
Ishai Dror, Earth And Planetary Sciences, Weizmann Institute Of Science, Rehovot, Israel
Brian Berkowitz, Earth And Planetary Sciences, Weizmann Institute Of Science, Rehovot, Israel

Per- and polyfluoroalkyl substances (PFAS) are a class of fluorinated organic compounds (FOCs) widely recognized for their exceptional stability, attributed to the strong carbon-fluorine (C-F) bonds. This bond renders PFAS as significant environmental pollutants with well-documented adverse effects on human health, including developmental and immune system disruptions. PFAS persist in (active!) drinking water sources globally, necessitating continuous monitoring and removal strategies. Regulatory limits for PFAS are increasingly strict, ranging from 0.07 ppb (in the US, for PFOA and PFOS) to 0.1 ppb (in the EU, for 20 individual PFAS, 0.5 ppb for total PFAS) in drinking water. However, detection and treatment are complicated by typically low concentrations (~ 5 ppb) and interference from complex matrices such as saline environments, which contribute to noisy analytical results and insufficient transformation/degradation. We present a novel electrochemical method for FOC removal, addressing both detection and degradation challenges. Our approach achieves significant FOC removal, including PFAS mixtures (e.g., perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), perfluorosulfonic acid (PFOS); total PFAS < 40 ppb) and other FOCs such as 5-fluorouracil (5FU), enrofloxacin, and fluometuron. The method demonstrates robustness even in complex matrices. Complementary studies on 5FU elucidate a mechanism of C-F bond cleavage, providing insights into broader applicability. A broad range of advanced analytical techniques, including UPLC, LC-MS, and IC, were employed to confirm degradation products and ensure method reliability. These findings establish a scalable, efficient approach to PFAS removal from aqueous environments, addressing urgent regulatory and environmental concerns while laying the groundwork for broader FOC remediation strategies.