Effect of hydroxyl radicals on the interaction between chlorinated volatile organic compounds and β-pinene under simulated and sunlight irradiation

Experiments are performed in atmospheric simulation chambers. First, reactions are carried out in a rigid ASC under simulated irradiation where different gaseous systems (OH center dot / TCE and MC / beta-pinene) are studied in mixtures (complete system), and separately (simple system). Second, interactions between TCE and beta-pinene are achieved in two flexible ASCs under solar irradiation in presence of artificial nitrogen oxides (NOx). The interest of these experiences is to simulate the arrival of a mass of industrial air charged with chlorinated VOC on a forest site, "naturally" rich in terpenic compounds. Results have shown that the presence of hydroxyl radicals can generate chlorine radicals, thus, an increase in the rate of degradation of the terpenic compounds. Constants of degradation rates (k(OH)) of TCE, MC and beta-pinene are determined. Degradation ways of beta-pinene and TCE by Cl-center dot and OH center dot that respectively lead to the formation of nopinone and phosgene, experimentally detected as by-products, are proposed. Finally, in order to characterize the reactivity of the photochemically studied system, various parameters are calculated and analyzed, in particular, the intensity of sunlight, the maximum of ozone concentration recorded, the maximum rate of ozone formation, the rate of nitrogen oxide consumption, the percentage of disappearance of beta-pinene after 1h of reaction, and the maximum of carbonyl produced VOC.