Degradation of hexafluoropropylene oxide tetrameric acid (HFPO-TeA) using electrocatalytic ozone technique

Abstract

Hexafluoropropylene oxide tetrameric acid (HFPO-TeA) is an alternative to perfluorooctanecarboxylic acid (PFOA) and is commonly used in the production of perfluoropolymers. In this study, the performances of ozone oxidation, electrochemical oxidation, and electrocatalytic ozone techniques in the degradation of HFPO-TeA were compared. The experimental results indicated that the electrocatalytic ozone technique was best. The effects of different current densities, ozone concentrations, electrolyte types, and initial pollutant concentrations on HFPO-TeA degradation were investigated. The results showed that the ratio of HFPO-TeA degradation reached 95.9% after electrolysis for 120 ​min for an initial HFPO-TeA concentration of 100 ​mg/L, a reaction volume of 120 ​mL, an applied current density of 10 ​mA/cm2, and an ozone concentration of 20 ​mg/L. The intermediate products detected were hexafluoropropylene oxide dimeric acid [C3F7OCF(CF3)COO−], pentafluoropropionic acid [C2F5COO−], and trifluoroacetic acid [CF3COO−]. The mechanisms involved in HFPO-TeA degradation include direct electron transfer, indirect oxidation mediated by hydroxyl radicals (·OH), and ozone oxidation.

Keywords

• Electrocatalytic ozone
• Boron doped diamond (BDD) electrode
• Perfluorinated compounds
• Intermediate products
• Mechanism