Mines Douai , Département SAGE, 59500 Douai, France.
Université de Lille , 59655 Villeneuve d'Ascq, France.
Environ Sci Technol. 2015 Oct 20;49(20):12178-86. doi: 10.1021/acs.est.5b02721. Epub 2015 Oct 7.
Hydroxyketones are key secondary reaction products in the atmospheric oxidation of volatile organic compounds (VOCs). The fate of these oxygenated VOCs is however poorly understood and scarcely taken into account in atmospheric chemistry modeling. In this work, a combined investigation of the photolysis and temperature-dependent OH radical reaction of 4-hydroxy-2-butanone (4H2B) is presented. The objective was to evaluate the importance of the photolysis process relative to OH oxidation in the atmospheric degradation of 4H2B. A photolysis lifetime of about 26 days was estimated with an effective quantum yield of 0.08. For the first time, the occurrence of a Norrish II mechanism was hypothesized following the observation of acetone among photolysis products. The OH reaction rate coefficient follows the Arrhenius trend (280-358 K) and could be modeled through the following expression: k4H2B(T) = (1.26 ± 0.40) × 10(-12) × exp((398 ± 87)/T) in cm(3) molecule(-1) s(-1). An atmospheric lifetime of 2.4 days regarding the OH + 4H2B reaction was evaluated, indicating that OH oxidation is by far the major degradation channel. The present work underlines the need for further studies on the atmospheric fate of oxygenated VOCs.
羟基酮是挥发性有机化合物（VOCs）在大气氧化过程中的关键次级反应产物。然而，这些含氧 VOC 的命运却知之甚少，在大气化学模型中几乎没有考虑到。在这项工作中，我们对 4-羟基-2-丁酮（4H2B）的光解和温度依赖的 OH 自由基反应进行了综合研究。目的是评估光解过程相对于 OH 氧化在 4H2B 大气降解中的重要性。通过观察光解产物中的丙酮，我们估计其光解寿命约为 26 天，有效量子产率为 0.08。首次提出了 Norrish II 机制的发生，这是在观察到光解产物中的丙酮之后提出的。OH 反应速率系数遵循阿仑尼乌斯趋势（280-358 K），可以通过以下表达式进行建模：k4H2B(T) = (1.26 ± 0.40) × 10(-12) × exp((398 ± 87)/T) 在 cm(3)分子(-1) s(-1) 中。根据 OH + 4H2B 反应，其大气寿命为 2.4 天，这表明 OH 氧化是主要的降解途径。本工作强调了需要进一步研究含氧 VOC 在大气中的命运。
