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Atmospheric Degradation Initiated by OH Radicals of the Potential Foam Expansion Agent, CF3(CF2)2CHCH2 (HFC-1447fz): Kinetics and Formation of Gaseous Products and Secondary Organic Aerosols

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journal contribution
posted on 02.02.2016, 00:00 by Elena Jiménez, Sergio González, Mathieu Cazaunau, Hui Chen, Bernabé Ballesteros, Véronique Daële, José Albaladejo, Abdelwahid Mellouki
The assessment of the atmospheric impact of the potential foam expansion agent, CF3(CF2)2CHCH2 (HFC-1447fz), requires the knowledge of its degradation routes, oxidation products, and radiative properties. In this paper, the gas-phase reactivity of HFC-1447fz with OH radicals is presented as a function of temperature, obtaining kOH (T = 263–358 K) = (7.4 ± 0.4) × 10–13exp­{(161 ± 16)/T} (cm3·molecule–1·s–1) (uncertainties: ±2σ). The formation of gaseous oxidation products and secondary organic aerosols (SOAs) from the OH + HFC-1447fz reaction was investigated in the presence of NOx at 298 K. CF3(CF2)2CHO was observed at low- and high-NOx conditions. Evidence of SOA formation (ultrafine particles in the range 10–100 nm) is reported with yields ranging from 0.12 to 1.79%. In addition, the absolute UV (190–368 nm) and IR (500–4000 cm–1) absorption cross-sections of HFC-1447fz were determined at room temperature. No appreciable absorption in the solar actinic region (λ > 290 nm) was observed, leaving the removal by OH radicals as the main atmospheric loss process for HFC-1447fz. The major contribution of the atmospheric loss of HFC-1447fz is due to OH reaction (84%), followed by ozone (10%) and chlorine atoms (6%). Correction of the instantaneous radiative efficiency (0.36 W m–2·ppbv–1) with the relatively short lifetime of HFC-1447fz (ca. 8 days) implies that its global warming potential at a time horizon of 100 year is negligible (0.19) compared to that of HCFC-141b (782) and to that of modern foam-expansion blowing agents (148, 882, and 804 for HFC-152a, HFC-245fa and HFC-365mfc, respectively).