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Degradation of PFOA Substitute: GenX (HFPO–DA Ammonium Salt): Oxidation with UV/Persulfate or Reduction with UV/Sulfite?

2018; American Chemical Society; Linguagem: Inglês

10.1021/acs.est.8b02172

1520-5851

Yixiang Bao, Shanshan Deng, Xinshu Jiang, Yingxi Qu, Yuan He, Liquan Liu, Qiwan Chai, Mehvish Mumtaz, Jun Huang, Giovanni Cagnetta, Gang Yu,

Atmospheric chemistry and aerosols

Hexafluoropropylene oxide dimer acid (HFPO-DA, ammonium salt with trade name: GenX) has been recently detected in river water worldwide. There are significant concerns about its persistence, and potential adverse effects to the biota. In this study, the degradability of GenX by typical advanced redox technologies (UV/persulfate and UV/sulfate) is investigated. Results demonstrate that 90% of fluoride ion is recovered 6 h later. This is attributed to the accumulation and subsequent degradation of CF3CF2COOH and CF3COOH, which are stable intermediates of GenX degradation. Mechanistic investigations suggest that the etheric bond in the molecule is a favorable attack point for the eaq-. Such finding is corroborated by quantum chemical calculations. The side CF3- at the α-carbon probably acts as an effective barrier that prevents GenX from being cleaved by SO4-• or OH• at its most sensible point (i.e. the carboxyl group). This study illustrates that reduction by UV/sulfite might be a promising technology to remove GenX from contaminated water.