Electrocatalytic water treatment of per- and polyfluoroalkyl substances reduces adsorbable organofluorine and bioaccumulation potential

Abstract

Per- and polyfluoroalkyl substances (PFAS) are pervasive in industrial processes, eliciting public concern upon their release into municipal sewers or the environment. Removing PFAS from the environment has become an urgent need. However, because potential endpoints span from energy-intensive complete mineralization to partial PFAS transformation, understanding and developing metrics for evaluating PFAS treatment can be a challenge. The goal of this study was to evaluate and compare the effectiveness of electrocatalytic degradation of PFAS with boron-doped diamond (BDD) electrodes using four techniques: LC-MS/MS target analysis, fluoride ion (F⁻), adsorbable organofluorine (AOF), and bioaccumulation potential using lipid-bilayer partition (LBP) tests. After 3 hours of electrocatalysis, >99% perfluorooctanoic acid (PFOA) degradation was achieved and corresponded with 84% conversion to F⁻, which was substantial – though intentionally not complete – defluorination. For the same 3 hour treatment time, AOF and LBP coefficient were reduced by 95% and 83%, respectively. LBP's detection limit was 2 orders of magnitude higher than that of AOF, so the positive correlation observed between LBP and AOF (r = 0.86) suggests AOF's practical utility as a design metric for assessing bioaccumulation potential of various organofluorine transformation by-products.