<i>In situ</i> measurement-based partitioning behavior of perfluoroalkyl acids in the atmosphere

Abstract

Environmental fate of ionizable organic pollutants such as perfluoroalkyl acids (PFAAs) are of increasing interest but has not been well understood because of uncertain values for parameters related with atmospheric interphase partitioning behavior. In the present study, not only the values for air-water partition coefficient (K AW) and dissociation constant (pK a) of PFAAs were induced by adjusting to in situ measurements of air-water distribution coefficient between vapor phase and rainwater but also gas-particle partition coefficients were also estimated using three-phase partitioning model of ionizable organic pollutants, in situ measurements of PFAAs in aerosol and air vapor phase, and obtained parameter values. The pK a values of PFAAs we obtained were close to the minimum values suggested in literature except for perfluorooctane sulfonic acids, and COSMOtherm-modeled K AW values were assessed to more appropriate among suggested values. When applying parameter values we obtained, it was predicted that air particle-associated fate and transport of PFAAs could be negligible and PFAAs could distribute ubiquitously along the transection from urban to rural region by pH-dependent phase transfer in air. Our study is expected to have some implications in prediction of the environmental redistribution of other ionizable organic compounds

PFAS on atmospheric aerosol particles: a review

“…In general, eld measurements of PFAS conrm that partitioning from the gas phase to the particle phase is more favorable with increasing chain length and decreasing temperature (i.e., decreasing vapor pressure). 19,30,31,34,50,[60][61][62][63] To compare partitioning of PFAS from different chemical classes, Ahrens et al 50 quantied the particle-bound fraction of 29 PFAS at an urban site in Toronto, Canada (entry 50 in Tables 2-4) using annular diffusion denuders coated with XAD-4 to sample the gas phase and a lter pack containing glass ber lters and sorbent-impregnated lters with XAD-4 to sample the particle phase. The average particle-bound fraction followed the trend: FTACs (uorotelomer acrylates, 0%) < FTOHs (uorotelomer alcohols, 8%) < FASAs (peruoroalkane sulfonamides, 21%) < PFSAs (peruoroalkane sulfonic acids, 29%) < FASEs (peruoroalkane sulfonamido ethanols, 66%).…”

Electrochemical Advanced Oxidation of Perfluorooctanoic Acid: Mechanisms and Process Optimization with Kinetic Modeling

“…Past studies also investigated experimentally that PFOA oxidation was only achieved when the anode potential was higher than 3.00 V/SHE, 5 and this was consistent with our simulation result. Since the pH was above 3.5 throughout the electrolysis, and the pK a for PFOA was below 1, 33,34 C 7 F 15 COO − was the dominant PFOA species. Consequently, the first step for PFOA mineralization should be the direct oxidation of C 7 F 15 COO − to generate C 7 F 15 COO • .…”

Exploring controls on perfluorocarboxylic acid (PFCA) gas–particle partitioning using a model with observational constraints

“…, ref. 8, 15 and 21–24). However, about half of the studies that have examined gas–particle partitioning of PFCAs with chain lengths ≥ 4 have relied upon the collection of particles prior to gases ( e.g.…”

“…However, about half of the studies that have examined gas–particle partitioning of PFCAs with chain lengths ≥ 4 have relied upon the collection of particles prior to gases ( e.g. , in high volume air samplers 21,22,24 ). Sampling in this way is well established to lead to artifacts for long-studied atmospheric acids like HNO 3 , 25–27 and has been shown to cause blow-on effects and an over-estimate of PFCAs in the particle phase.…”