TY - JOUR
T1 - Vapor Pressure of Nine Perfluoroalkyl Substances (PFASs) Determined Using the Knudsen Effusion Method
AU - Zhang, Mengke
AU - Yamada, Kyle
AU - Bourguet, Stephen
AU - Guelfo, Jennifer
AU - Suuberg, Eric M.
N1 - Funding Information:
This project was financially supported by the Superfund Research Program of NIEHS grant 2P42 ES013660. We thank Chen Liu from Brown University for the LC-MS/MS measurement.
Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/5/14
Y1 - 2020/5/14
N2 - Sublimation vapor pressures of nine pure perfluoroalkyl substances, including ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), 1H,1H,2H,2H-perfluoro-1-decanol (8:2 FTOH), 1H,1H,2H,2H-perfluoro-1-dodecanol (10:2 FTOH), and C6 to C11 perfluorocarboxylic acids (PFCAs), were measured using the Knudsen technique at near-ambient temperatures. Melting temperatures and fusion enthalpies of these compounds were also measured by differential scanning calorimetry. The vapor pressure of GenX ammonium salt is comparable to that of the much higher molecular weight perfluoroundecanoic acid. GenX ammonium salt also did not show actual melting behavior but instead decomposed at around 470 K. The measured near-ambient temperature sublimation vapor pressures of the PFCAs and FTOHs were compared with some earlier reported liquid phase vapor pressures obtained at higher temperatures, and reasonable agreement exists between the data obtained in the different studies. The sublimation enthalpies of the PFCAs indicate that the contribution to the sublimation enthalpy of the CF2 group in the alkyl chain is comparable to that of the CH2 group in the corresponding nonfluorinated analogues, even though the PFCAs show consistently higher vapor pressures than do the corresponding carbon number alkanoic acids.
AB - Sublimation vapor pressures of nine pure perfluoroalkyl substances, including ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), 1H,1H,2H,2H-perfluoro-1-decanol (8:2 FTOH), 1H,1H,2H,2H-perfluoro-1-dodecanol (10:2 FTOH), and C6 to C11 perfluorocarboxylic acids (PFCAs), were measured using the Knudsen technique at near-ambient temperatures. Melting temperatures and fusion enthalpies of these compounds were also measured by differential scanning calorimetry. The vapor pressure of GenX ammonium salt is comparable to that of the much higher molecular weight perfluoroundecanoic acid. GenX ammonium salt also did not show actual melting behavior but instead decomposed at around 470 K. The measured near-ambient temperature sublimation vapor pressures of the PFCAs and FTOHs were compared with some earlier reported liquid phase vapor pressures obtained at higher temperatures, and reasonable agreement exists between the data obtained in the different studies. The sublimation enthalpies of the PFCAs indicate that the contribution to the sublimation enthalpy of the CF2 group in the alkyl chain is comparable to that of the CH2 group in the corresponding nonfluorinated analogues, even though the PFCAs show consistently higher vapor pressures than do the corresponding carbon number alkanoic acids.
M3 - Article
SP - 2332
EP - 2342
JO - Journal of Chemical and Engineering Data
JF - Journal of Chemical and Engineering Data
ER -