Kinetic study of the OH and Cl-iniciated oxidation, lifetimes and atmospheric acceptability índices of three halogenated ethenes

JAVIER A. BARRERA, PABLO R. DALMASSO, JUAN P. ARANGUREN ABRATE, RAÚL A. TACCONE AND S. I. LANE

RSC Advances

The Royal Society of Chemistry

Año: 2015 vol. 5 p. 73501 - 73509

The gas-phase kinetics for the reactions of OH radicals and Cl atoms with (E/Z)-CHCl]CHF, (E/Z)-CFCl]CFCl, and CCl2]CF2 were investigated at room-temperature and atmospheric pressure. A conventionalrelative-rate technique was used to determine the rate coefficients k(OH + (E/Z)-CHCl]CHF) ¼ (6.3 1.2) 1012, k(OH + (E/Z)-CFCl]CFCl) ¼ (1.6 0.2) 1012, k(OH + CCl2]CF2) ¼ (5.0 0.7) 1012,k(Cl + (E/Z)-CHCl]CHF) ¼ (11 2) 1011, k(Cl + (E/Z)-CFCl]CFCl) ¼ (5.4 1.3) 1011, and k(Cl +CCl2]CF2) ¼ (6.3 1.5) 1011 cm3 per molecule per s. These rate coefficients were compared withprevious literature data to analyze the effect of halogen substitution in ethenes on the reactivity towardsOH and Cl, and used to estimate the global atmospheric lifetimes for the studied haloethenes. Thecalculated lifetimes, using average global concentrations of OH radicals and Cl atoms, indicate that theatmospheric loss of these compounds is determined by the OH-initiated oxidation. Also, theatmospheric implications of the halogenated ethenes studied were evaluated by estimating acceptabilityindices such as the global warming potential (GWP) and the ozone depletion potential (ODP). Fromthese potentials, the contribution of (E/Z)-CHCl]CHF, (E/Z)-CFCl]CFCl, and CCl2]CF2 to radiativeforcing of climate change and to ozone layer depletion is expected to be negligible.