An experimental study of the gas-phase reaction between Cl atoms and trans-2-pentenal: Kinetics, products and SOA formation. (August 2021)

• Record Type: Journal Article
• Authors: Grira, Asma; Antiñolo, María; Canosa, André; Tomas, Alexandre; Jiménez, Elena; El Dib, Gisèle
• Is Part Of: Chemosphere. Volume 276(2021)
• Publication Date: 2021-08
• Subjects: Unsaturated aldehyde -- Kinetics -- Mechanism -- Organic aerosols -- Atmospheric lifetimes; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.130193
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The gas-phase reaction of trans-2-pentenal (T2P) with Cl atoms was studied at atmospheric pressure and room temperature. A rate coefficient of (2.56 ± 0.83) × 10 -10 cm 3 molecule -1 s -1 was obtained using the relative rate method and isoprene, cyclohexane and ethanol as reference compounds. The kinetic study was carried out using a 300-L Teflon bag simulation chamber (IMT Lille Douai-France) and a 16-L Pyrex cell (UCLM-Ciudad Real-Spain), both coupled to the Fourier transform infrared (FTIR) technique. Gas-phase products and secondary organic aerosol (SOA) formation were studied at UCLM using a 16-L Pyrex cell and a 264-L quartz simulation chamber coupled to the FTIR and gas-chromatography-mass spectrometry (GC-MS) techniques. HCl, CO, and propanal were identified as products formed from the studied reaction and quantified by FTIR, the molar yield of the latter being (5.2 ± 0.2)%. Formic acid was identified as a secondary product and was quantified by FTIR with a yield of (6.2 ± 0.4)%. In addition, 2-chlorobutanal and 2–pentenoic acid were identified, but not quantified, by GC-MS as products. The SOA formation was investigated using a fast mobility particle sizer spectrometer. The observed SOA yields reached maximum values of around 7% at high particle mass concentrations. This work provides the first study of the formation of gaseous and particulate products for the reaction of Cl with T2P. A reaction mechanism is suggested to explain the formation of the observed gaseous products. The results are discussed in terms of structure-reactivity relationship, and the atmospheric implications derived from this study are commented as well. Highlights: A rate coefficient of (2.56 ± 0.83) × 10 −10 cm 3 molecule −1 s −1 was obtained for the reaction of T2P with Cl. This work is the first study of the gas-phase products and the SOA formation from the reaction of T2P with Cl. The T2P + Cl reaction may contribute to the acidity of marine atmospheres. The T2P + Cl reaction proceeds mainly by H-abstraction of the aldehydic group and by β-addition of Cl atoms to the double bond. Atmospheric lifetimes of T2P toward chemical removals are of few hours.