Atmospheric Fate of a New Polyfluoroalkyl Building Block, C3F7OCHFCF2SCH2CH2OH.

ABSTRACT

Many per- and polyfluoroalkyl substances (PFAS) have been regulated or phased-out of usage due to concerns about persistence, bioaccumulation potential, and toxicity. We investigated the atmospheric fate of a new polyfluorinated alcohol 2-(1,1,2-trifluoro-2-heptafluoropropyloxy-ethylsulfanyl)-ethanol (C3F7OCHFCF2SCH2CH2OH, abbreviated FESOH) by assessing the kinetics and products of the gas-phase reaction of FESOH with chlorine atoms and hydroxyl radicals. Experiments performed in a stainless-steel chamber interfaced to an FTIR were used to determine reaction kinetics and gas-phase products. We report reaction rate constants of k(Cl + FESOH) = (1.5 ± 0.6) × 10-11 cm3 molecule-1 s-1 and k(OH + FESOH) = (4.2 ± 2.0) × 10-12 cm3 molecule-1 s-1. This leads to a calculated FESOH gas-phase lifetime of 2.8 ± 1.3 days with respect to reaction with OH, assuming [OH] = 106 molecule1 cm-3. Gas-phase products of FESOH oxidation included at least two aldehydes, likely C3F7OCHFCF2SCH2C(O)H and C3F7OCHFCF2SC(O)H, and secondary products including COF2, SO2 and C3F7OC(O)F. Additional gas-phase experiments performed in a Teflon chamber were used to assess aqueous products by collecting gaseous samples offline into an aqueous sink prior to analysis with ultrahigh performance liquid chromatography-tandem mass spectrometry, resulting in four acidic products C3F7OCHFCF2SCH2C(O)OH, C3F7OCHFCF2S(O)(O)OH, C3F7OCHFC(O)OH, and perfluoropropanoic acid (C2F5C(O)OH).