Atmospheric oxidation of unsaturated hydrofluoroethers initiated by OH radicals

Abstract

Hydrofluoroethers (HFEs) are perfluorinated chemicals that were developed as alternative for chlorofluorocarbons (CFCs) in various applications. Among notable unsaturated HFEs are perfluoro methyl vinyl ether (PMVE, CF3OCFCF2) and perfluoro ethyl vinyl ether (PEVE, C2F5OCF = CF2). During the implementation of PMVE and PEVE, they spill and release to the atmosphere. Due to the tendency of perfluorinated compounds to have strong infrared absorption features and long atmospheric lifetimes, they are among the most potent greenhouse gases. Thus, it is important to accurately assess their atmospheric sink routes in order to assess their impact on climate change. Herein, we illustrated detailed mechanistic pathways and developed kinetic models with the underlying aim to comprehend the atmospheric fate of the title HFEs and the likely products of decomposition. It was found that the production of main products to stem from the addition of OH radical to the inner carbon-carbon double bond atoms. Atmospheric lifetimes of PMVE and PEVE were calculated to be ∼23 and ∼56 h; respectively. Time-dependent molar yields are acquired for the experimentally major products; namely carbonyl fluoride (CF2O), perfluorinated glyoxal (CFOCFO), perfluorinated methylformates (CF3OCFO and CF3CF2OCFO). Photochemical Ozone Creation Potentials (POCPs) of PMVE and PEVE were calculated to be 1.78 and 1.18, respectively. Obtained results tap into efforts that aim to understand the atmospheric chemistry cycles of perfluorinated chemicals in general.