Experimental insights into anodic oxidation of hexafluoropropylene oxide dimer acid (GenX) on boron-doped diamond anodes

Journal article (2022)

Authors

J.M.C. Mol Team Arjan Mol - Mechanical, Maritime and Materials Engineering
J.G. Buijnsters Micro and Nano Engineering - Mechanical, Maritime and Materials Engineering
Research Group
Team Arjan Mol (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2022 Diwakar Suresh Babu, J.M.C. Mol, J.G. Buijnsters
DOI: https://doi.org/10.1016/j.chemosphere.2021.132417
Hexafluoropropylene oxide dimer acid (HFPO-DA) GenX Hydroxyl radicals Perfluorooctanoic acid (PFOA) Boron-doped diamond (BDD) Electrochemical oxidation
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Published Date

2022

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Materials Science and Engineering

Research Group

Team Arjan Mol

Abstract

GenX is the trade name of the ammonium salt of hexafluoropropylene oxide dimer acid (HFPO-DA) and is used as a replacement for the banned perfluorooctanoic acid (PFOA). However, recent studies have found GenX to be more toxic than PFOA. This work deals with the electrochemical degradation of HFPO-DA using boron-doped diamond anodes. For the first time, an experimental study was conducted to investigate the influence of sulfate concentration and other operating parameters on HFPO-DA degradation. Results demonstrated that sulfate radicals were ineffective in HFPO-DA degradation due to steric hindrance by –CF3 branch. Direct electron transfer was found as the rate-determining step. By comparing degradation of HFPO-DA with that of PFOA, it was observed that the steric hindrance by –CF3 branch in HFPO-DA decreased the rate of electron transfer from the carboxyl head group even though its defluorination rate was faster. Conclusively, a degradation pathway is proposed in which HFPO-DA mineralizes to CO2 and Fˉ via formation of three intermediates.