Atmospheric Fate of a New Polyfluoroalkyl Building Block, C3F7OCHFCF2SCH2CH2OH

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-ethylsulfany1)-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) X 10(-11) cm(3) molecule(-1) s(-1) and k(OH + FESOH) = (4.2 +/- 2.0) X 10(-12) cm(3) 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] = 10(6) molecule(1) 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).

Automated summary

This study investigated the atmospheric fate of a new polyfluorinated alcohol FESOH and assessed its reaction kinetics and products with chlorine atoms and hydroxyl radicals. The results showed that FESOH has a gas-phase lifetime of approximately 2.8 days and produces aldehydes and other gas-phase products.