Unsaturated ethers in the atmosphere: reactivity towards OH radicals, response under the sunlight and contribution to the global warming

ELENA JIMÉNEZ, MARÍA ANTIÑOLO, ANTONIO J. OCAÑA, BERNABÉ BALLESTEROS, JUAN P. ARANGUREN, SILVIA I. LANE AND JOSÉ ALBALADEJO

Conferencia; Chemistry in the Urban Atmosphere: Faraday Discussion; 2016

Unsaturated ethers are used as precursors in some industrial processes such as the synthesis of coatings, fragrances, pharmaceuticals, inks or copolymers.1,2As a consequence of this usage, they can be released into the atmosphere, where they are expected to be removed by different processes. The aim of this work is to understand the role of the reactivity towards hydroxyl (OH) radicals in the removal of three unsaturated ethers: 2-chloroethyl vinyl ether (2ClEVE), allyl ether (AE), and allyl ethyl ether (AEE). Ultraviolet-visible (UV-vis) and infrared (IR) absorption cross-sections (). are also presented to have a broader picture of the behaviour of these three unsaturated ethers in terms of their exposure to sunlight and their contribution to global warming, respectively.Reaction rate coefficients for the gas-phase reaction between OH and the investigated unsaturated ethers (kOH) are known at room temperature.3 In this work,absolutekOHare determined for the first time as a function of pressure (P = 50 ? 300 Torr) and temperature (T = 263 ? 358 K) using the well-known Pulsed Laser Photolysis-Laser Induced Fluorescence (PLP-LIF)technique. OH radicals are generated by pulsed photolysis of H2O2 or HNO3 at 248 nm and detected by LIF at ca.308 nm. The negative temperature dependency of kOH found for the studied range will be discussed, as well as the lack of pressure dependency. UV-vis absorption spectra between 200 and 375 nm have been recorded at room temperature for 2ClEVE, AE, and AEE in order to determine the absolute absorption cross-sections (UV). Once known UV, the rate coefficient for the photolysis process sunlight conditions of Ciudad Real (J) has been estimated and compared with the removal by OH reaction.Absorption cross-sections (IR) in the IRrangebetween 500 and 4000 cm 1 have also been determined. From this information, the estimation of the global warming potential at a certain time horizon (GWPTH) for 2ClEVE, AE, and AEE and their contribution to the global warming will be presented and discussed.