Characterization of secondary aerosol from the photooxidation of toluene in the presence of NOx and 1-propene.
Characterization of secondary aerosol from the photooxidation of toluene in the presence of NOx and 1-propene.
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DOI：
10.1021/es010676
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发表时间：
2001-08
影响因子：
11.4
通讯作者：
M. Jang;R. Kamens
中科院分区：
文献类型：
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作者：
M. Jang;R. Kamens
二次有机气溶胶（SOA）从光氧化的甲苯在烃-NOx混合物中产生在一个190 m3的室外聚四氟乙烯室。甲苯在气相中的光氧化反应导致取代的芳香族化合物（TOL-AR）、非芳香族环保留产物（TOL-R）和开环产物（TOL-RO）。在这项工作中，以下开环氧基羧酸是新鉴定的：乙醛酸，甲基乙醛酸，4-氧代-2-丁烯酸，氧代-C5-烯酸，二氧代戊烯酸，氧代-C7-链二烯酸，二氧代-C6-烯酸，羟基二氧代-C7-烯酸，和羟基三氧代-C6-链烷酸。新的TOL-R和TOL-RO产物包括甲基环己烯三酮、羟甲基环己烯三酮、2-羟基-3-戊烯-1，5-二醛、羟基氧代-C6-烯醛、羟基-C5-三酮、羟基二氧代-C7-烯醛和羟基-C6-四酮。在气相和气溶胶相的产品进行衍生化与O-（2，3，4，5，6-五氟苄基）羟胺盐酸盐（PFBHA）的羰基和五氟苄基溴（PFBBr）的羧酸和苯酚基团，并使用气相色谱/质谱（GC/MS）在电子碰撞模式（EI）和气相色谱/离子阱质谱（GC/ITMS）在化学碰撞和EI模式进行分析。为了确认不同的异构体，使用N，O-双（三甲基甲硅烷基）三氟乙酰胺（BSTFA）通过甲硅烷基化对产物的PFBHA衍生物进行再衍生。傅里叶变换红外光谱（FTIR）被用来获得额外的功能团信息的SOA产品的影响硒化锌FTIR磁盘。在上述实验的高NOx条件下的主要SOA产物包括甲基硝基苯酚、甲基二硝基苯酚、甲基苯醌、甲基环己烯三酮、4-氧代-2-丁烯酸、氧代-C5-烯酸、羟基-C3-二酮、羟基氧代-C5-烯醛、羟基氧代-C6-烯醛和羟基二氧代-C7-烯醛。在主要的SOA产物中，醛产物的实验分配系数（iKp）要高得多，并且与预测的iKp值偏离得更多。这是一个极其重要的结果，因为它表明醛类产物可以通过非均相过程进一步反应，这可能是大气中芳烃氧化的一个非常重要的SOA生成机制。
Secondary organic aerosol (SOA) from the photooxidation of toluene in a hydrocarbon-NOx mixture was generated in a 190 m3 outdoor Teflon chamber. The photooxidation reaction of toluene in the gas phase leads to substituted aromatics (TOL-AR), nonaromatic ring retaining (TOL-R), and ring opening products (TOL-RO). In this work, the following ring opening oxycarboxylic acids were newly identified: glyoxylic acid, methylglyoxylic acid, 4-oxo-2-butenoic acid, oxo-C5-alkenoic acids, dioxopentenoic acids, oxo-C7-alkadienoic acids, dioxo-C6-alkenoic acids, hydroxydioxo-C7-alkenoic acids, and hydroxytrioxo-C6-alkanoic acids. The newly characterized TOL-R and TOL-RO products included methylcyclohexenetriones, hydroxymethylcyclohexentriones, 2-hydroxy-3-penten-1,5-dial, hydroxyoxo-C6-alkenals, hydroxy-C5-triones, hydroxydioxo-C7-alkenals, and hydroxy-C6-tetranones. Products in both the gas and aerosol phases were derivatized with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) for carbonyls and pentafluorobenzyl bromide (PFBBr) for carboxylic acid and phenol groups and analyzed using a gas chromatograph/mass spectrometry (GC/MS) in an electron impact mode (EI) and a gas chromatograph/ion trap mass spectrometry (GC/ITMS) in both chemical impact and EI modes. To confirm different isomers, the PFBHA-derivatives of products were rederivatized by silylation using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). The Fourier transform infrared spectroscope (FTIR) was used to obtain additional functional group information for SOA products impacted on a zinc selenide FTIR disk. The major SOA products under the high NOx conditions of the above experiment included methylnitrophenols, methyldinitrophenols, methylbenzoquinones, methylcyclohexenetriones, 4-oxo-2-butenoic acid, oxo-C5-alkenoic acids, hydroxy-C3-diones, hydroxyoxo-C5-alkenals, hydroxyoxo-C6-alkenals, and hydroxydioxo-C7-alkenals. Of the major SOA products, the experimental partitioning coefficients (iKp) of aldehyde products were much higher and deviated more from predicted iKp values. This is an extremely important result, because it shows that aldehyde products can further react through heterogeneous processes, which may be a very significant SOA generation mechanism from the oxidation of aromatics in the atmosphere.