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Atmospheric degradation of oxygenated Volatile Organic Compounds

Abstract : Oxygenated Volatile Organic Compounds (OVOCs), mainly released from biogenic sources, play a major role in atmospheric chemistry, climate change, environment, and health. These emissions have been recently shown to increase in the case of biotic and/or abiotic stresses. Biogenic OVOCs may undergo a wide variety of reactions, both chemical and photolytic, and they contribute in the formation of Secondary Organic Aerosols (SOAs). These compounds have been detected in various areas, but little is known about their degradation processes under tropospheric conditions. Understanding the oxidation mechanisms of these species is of fundamental interest and yields crucial data for atmospheric models used by policymakers in formulating and deciding strategies for improving air quality. This dissertation aims to improve the current knowledge of those OVOCs behaviors to better understand their impact on atmospheric chemistry. This work reports a detailed study of the atmospheric degradation of C5-C7 unsaturated aldehydes and C5-C8 unsaturated alcohols by ozone, Cl atom, and OH radical. The main objectives were to better understand the reaction mechanism and to feature the SOA formation potential. To achieve these objectives, we focused on four topics: (i) determination of IR and UV spectrum of C5-C7 unsaturated aldehydes, (ii) determination of the rate constant for the studied OVOCs + Oxidant at room temperature, (iii) identification and quantification of the gas-phase products, (iv) determination of the SOA yields. The product studies were investigated both with and without adding an OH radical scavenger. Experiments were performed in eight different static (chambers) or dynamic (flow) reactors, and various analytical techniques were used to investigate the reaction products (FTIR, GC-FID/MS, SPME-GC/MS, HPLC, PTR-ToF-MS, SIFT-MS, PLP-LIF) and SOA formation (SMPS, FMPS).
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Submitted on : Friday, September 17, 2021 - 4:34:11 PM
Last modification on : Wednesday, November 17, 2021 - 3:19:46 AM

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  • HAL Id : tel-03348008, version 1

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Asma Grira. Atmospheric degradation of oxygenated Volatile Organic Compounds. Other [cond-mat.other]. Université Rennes 1, 2021. English. ⟨NNT : 2021REN1S017⟩. ⟨tel-03348008⟩

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