TY - JOUR
T1 - Experimental insights into anodic oxidation of hexafluoropropylene oxide dimer acid (GenX) on boron-doped diamond anodes
AU - Suresh Babu, Diwakar
AU - Mol, Johannes M.C.
AU - Buijnsters, Josephus G.
PY - 2022
Y1 - 2022
N2 - 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.
AB - 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.
KW - Boron-doped diamond (BDD)
KW - Electrochemical oxidation
KW - GenX
KW - Hexafluoropropylene oxide dimer acid (HFPO-DA)
KW - Hydroxyl radicals
KW - Perfluorooctanoic acid (PFOA)
UR - http://www.scopus.com/inward/record.url?scp=85116762815&partnerID=8YFLogxK
U2 - 10.1016/j.chemosphere.2021.132417
DO - 10.1016/j.chemosphere.2021.132417
M3 - Article
AN - SCOPUS:85116762815
SN - 0045-6535
VL - 288
JO - Chemosphere
JF - Chemosphere
M1 - 132417
ER -