In-cloud processes of methacrolein under simulated conditions – Part 1: Aqueous phase photooxidation 1Universités d'Aix-Marseille I, II et III – CNRS, UMR 6264, Laboratoire Chimie Provence, Equipe: IRA, 3 place Victor Hugo, 13331 Marseilles Cedex 3, France
2Laboratoire Interuniversitaire des Systèmes Atmosphériques (UMR 7583), Université Paris, France
Received: 22 January 2009 – Published in Atmos. Chem. Phys. Discuss.: 10 March 2009 Abstract. The photooxidation of methacrolein was studied in the aqueous phase under
simulated cloud droplet conditions. The obtained rate constant of
OH-oxidation of methacrolein at 6°C in unbuffered solutions was 5.8(±0.9)×109 M−1 s−1.
The measured rate coefficient is
consistent with OH-addition on the C=C bond. This was confirmed by the
mechanism established on the study of the reaction products (at 25°C in
unbuffered solutions) where methylglyoxal, formaldehyde, hydroxyacetone and
acetic acid/acetate were the main reaction products. An upper limit for the
total carbon yield was estimated to range from 53 to 85%, indicating that
some reaction products remain unidentified. A possible source of this
mismatch is the formation of higher molecular weight compounds as primary
reaction products which are presented in El Haddad et al. (2009) and Michaud et al. (2009).
Revised: 30 June 2009 – Accepted: 01 July 2009 – Published: 28 July 2009
Citation: Yao Liu, El Haddad, I., Scarfogliero, M., Nieto-Gligorovski, L., Temime-Roussel, B., Quivet, E., Marchand, N., Picquet-Varrault, B., and Monod, A.: In-cloud processes of methacrolein under simulated conditions – Part 1: Aqueous phase photooxidation, Atmos. Chem. Phys., 9, 5093-5105, doi:10.5194/acp-9-5093-2009, 2009.