Kinetic and mechanistic study of the gas-phase reaction of CxF2x+1CHCH2 (x=1, 2, 3, 4 and 6) with O3 under atmospheric conditions. (June 2018)

• Record Type: Journal Article
• Authors: Soto, A.; Ballesteros, B.; Jiménez, E.; Antiñolo, M.; Martínez, E.; Albaladejo, J.
• Is Part Of: Chemosphere. Volume 201(2018)
• Page Start: 318
• Page End: 327
• Publication Date: 2018-06
• Subjects: Hydrofluoroolefins (HFOs) -- Rate coefficients -- Mechanism -- Perfluorinated carboxylic acids (PFCAs) -- Perfluoroaldehydes (PFALs); Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.02.183
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The relative-rate technique has been used to determine the rate coefficient for the reaction of Cx F2x+1 CHCH2 (x = 1, 2, 3, 4 and 6) with ozone at (298 ± 2) K and (720 ± 5) Torr of air by FTIR (Fourier Transform Infrared Spectroscopy) and by GC-MS/SPME (Gas Chromatography-Mass Spectroscopy with Solid Phase Micro Extraction) in two different atmospheric simulation chambers. The following rate coefficients, in units of 10 −19 cm 3 molecule −1 s −1, were obtained: (3.01 ± 0.10) for CF3 CHCH2, (2.11 ± 0.35) for C2 F5 CHCH2, (2.34 ± 0.42) for C3 F7 CHCH2, (2.05 ± 0.31) for C4 F9 CHCH2 and (2.07 ± 0.39) for C6 F13 CHCH2, where uncertainties represent ±2σ statistical error. The atmospheric lifetime of Cx F2x+1 CHCH2 due to reaction with ozone was estimated from the reported rate coefficients. Additionally, the gaseous products formed in these reactions were investigated in the presence of synthetic air simulating a clean atmosphere. Perfluoroaldehydes, Cx F2x+1 C(O)H (PFALs), formaldehyde, formic acid and CF2 O were identified as reaction products in the investigated reactions. The identified products made possible to propose a reaction mechanism that justifies the observed products. The atmospheric implications of these results are discussed in terms of the potential contribution of the atmospheric degradation of these species to PFAL and PFCA burden. Graphical abstract: Image 1 Highlights: Rate coefficients for ozone reaction with Cx F2x+1 CHCH2 (HFOs) at 298 K and 720 Torr of air are experimentally determined. Main reaction products are Cx F2x+1 C(O)H and formaldehyde, while minor products 4 are formic acid and CF2 O. Reaction with OH and O3 are expected to be the major loss mechanism for these 6 HFOs. The global tropospheric lifetimes are estimated on the order of 7 days that is sufficient 8 for their transport to remote locations. The title HFOs, apparently, do not contribute to the PFCA burden in remote locations.