Influence of temperature on the chemical removal of 3-methylbutanal,trans-2-methyl-2-butenal,and 3-methyl-2-butenal by OH radicals in the troposphere |
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| Authors: | Elena Jiménez Beatriz Lanza María Antiñolo José Albaladejo |
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| Institution: | 1. Faculté des Sciences Exactes et Informatique Département de Chimie, Université de Mohamed Seddik Ben Yahia, B.P. 98, Ouled Aissa, Jijle 18000, Algeria;2. Laboratoire LCCE, Faculté des sciences, Université de Batna, rue Boukhlouf El Hadi, 05000 Batna, Algeria;3. Institut de Physique de Rennes, UMR 6251 du CNRS, Université de Rennes 1, Bat. 11c, Campus de Beaulieu, 35042 Rennes Cedex, France;4. GSMA-UMR CNRS 7331, UFR Sciences, université Reims Champagne Ardenne, BP 1039, 51687 Reims Cedex 02, France;1. Departamento de Química Inorgánica y Química Técnica, Universidad Nacional de Educación a Distancia (UNED), Paseo Senda del Rey 9, 28040 Madrid, Spain;2. Adam Mickiewicz University, Faculty of Chemistry, Umultowska 89b, 61-614 Poznan, Poland;1. Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China;2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China;3. Grand Water Research Institute–Rabin Desalination Laboratory, Wolfson Faculty of Chemical Engineering, Technion–Israel Institute of Technology, Technion City, Haifa, 32000, Israel;4. Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States;1. Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla La Mancha, Avda. Camilo José Cela S/N, 13071, Ciudad Real, Spain;2. Instituto de Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla La Mancha, Camino Moledores S/N, 13071, Ciudad Real, Spain;1. Adam Mickiewicz University in Poznan, Faculty of Chemistry, Umultowska 89b, 61-614 Poznan, Poland;2. Departamento de Química Inorgánica y Química Técnica, UNED, Senda del Rey 9, E-28040 Madrid, Spain |
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| Abstract: | Absolute rate coefficients for the gas-phase reactions of OH radical with 3-methylbutanal (k1), trans-2-methyl-2-butenal (k2), and 3-methyl-2-butenal (k3) have been obtained with the pulsed laser photolysis/laser-induced fluorescence technique. Gas-phase concentration of aldehydes was measured by UV absorption spectroscopy at 185 nm. Experiments were performed over the temperature range of 263–353 K at total pressures of helium between 46.2 and 100 Torr. No pressure dependence of all ki (i = 1–3) was observed at all temperatures. In contrast, a negative temperature dependence of ki (i.e., ki increases when temperature decreases) was observed in that T range. The resulting Arrhenius expressions (±2σ) are: k1(T) = (5.8 ± 1.7)×10?12 exp{(499 ± 94)/T} cm3 molecule?1 s?1, k2(T)=(6.9 ± 0.9)×10?12 exp{(526 ± 42)/T} cm3 molecule?1 s?1, k3(T)=(5.6 ± 1.2)×10?12 exp{(666 ± 54)/T} cm3 molecule?1 s?1.The tropospheric lifetimes derived from the above OH-reactivity trend are estimated to be higher for 3-methylbutanal than those for the unsaturated aldehydes. A comparison of the tropospheric removal of these aldehydes by OH radicals with other homogeneous degradation routes leads to the conclusion that this reaction can be the main homogeneous removal pathway. However, photolysis of these aldehydes in the actinic region (λ > 290 nm) could play an important role along the troposphere, particularly for 3-methyl-2-butenal. This process could compete with the OH reaction for 3-methylbutanal or be negligible for trans-2-methyl-2-butenal in the troposphere. |
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