Kinetics and mechanism of the atmospheric photonucleation of chlorinated aromatic compounds: o-dichlorobenzene
S.N. Dubtsov1,2, A.S. Khlynova1, L.V. Kuibida1, G.G. Dultseva1,2
1V.V. Voevodsky Institute of Chemical Kinetics and Combustion of the Siberian Branch of the RAS, Novosibirsk, Russia
2Institute of Computational Mathematics and Mathematical Geophysics of the Siberian Branch of the RAS, Novosibirsk, Russia
Keywords: mechanism of photonucleation, chlorinated aromatic compound, functional group, kinetics of photonucleation
Abstract
Aerosol particles formed during the atmospheric photooxidation of organic compounds have reactive functional groups on their surface, which may be responsible for the biological action of the organic aerosol. This work studies the kinetics and mechanism of atmospheric photonucleation of o-dichlorobenzene as a compound modeling chlorinated aromatic hydrocarbons, known for their stability against environmental factors. The concentrations and sizes of the formed particles were measured using a diffusion spectrometer of aerosol; the composition of gas and aerosol products of photonucleation was determined by high-performance liquid chromatography and gas chromatography - mass spectrometry. The effect of water vapor and hydrogen peroxide on the yield and composition of aerosol products was studied. The pathways leading to the formation of identified products were determined relying on the data on the rate constants of elementary stages involved in nucleation. It is shown that atmospheric photonucleation of dichlorobenzene does not lead to the photochemical generation of ozone in the surface air layer. Quite contrary, the products of dichlorobenzene photolysis participate in the processes that cause ozone destruction. On the basis of the data obtained, the contribution from emissions containing chlorinated aromatics into the formation of organic aerosol in urban air is assessed qualitatively. The presence of reactive functional groups in the aerosol products allows us to assume that the aerosol may cause negative biological action. The results of investigation can be used to model photochemical processes in polluted urban air.
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