Photooxidation of farnesene mixtures in the presence of NOx: Analysis of reaction products and their implication to ambient PM2.5

Description

Chemical analysis of SOA produced from the irradiation of a mixture of α/β-farnesene/NOx was conducted in a 14.5 cubic meter smog chamber. SOA collected on glass-fiber filters was solvent extracted, derivatized using BSTFA, and analyzed by GC-MS. Gas-phase products were analyzed using a combination of GC-FID and GC-MS. This analysis showed the occurrence of more than 30 SOA oxygenated species and more than 20 in the gas phase. The major SOA components measured include conjugated α farnesene trienols, C3–C7 linear dicarboxylic acids, carbonyl compounds, and hydroxy/carbonyl/carboxylic compounds. In the gas phase, the main species identified were formaldehyde, glyoxal, methylglyoxal, acetone, 2,3-dimethyl-oxirane, 2(3H)-furanone, 2-butenedioic acid, 4 oxopentanal, 4-methylenehex-5-enal, and 6-methylhept-5-en-2-one. Proposed reaction schemes are provided for selected compounds. H-atom abstraction and OH addition in α/β-farnesene oxidation seem to play an important role via the formation of unsaturated radicals containing different numbers of delocalized electrons. Allylic hydrogen abstraction and hydroperoxyalkyl radical channels might play a key role in the oxidation of α/β-farnesene. The contribution of farnesene SOA products to ambient PM2.5 was investigated by analyzing PM2.5 samples collected during SOAS 2013 field study at a site in Research Triangle Park (RTP), NC. The importance of these findings was supported by the occurrence of several organic species in both field and laboratory samples, suggesting the impact of farnesene on the ambient aerosol burden, mainly in areas where farnesene emissions are high. Although, pentanedioic acid and methylsuccinic acid appear to be candidate markers for farnesene SOA, additional chamber and mechanistic studies are required to estimate the contributions of farnesene to ambient SOA. This dataset is associated with the following publication: Jaoui, M., M. Lewandowski , K. Docherty, E. Corse, B. Lonneman, J. Offenberg , and T. Kleindienst. Photooxidation of farnesene mixtures in the presence of NOx: Analysis of reaction products and their implication to ambient PM2.5. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, USA, 130: 190-201, (2016).

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10 Figure%201%20metadata.docx https://pasteur.epa.gov/uploads/238/Figure%201%20metadata.docx
10 Figure%202%20metadata.docx https://pasteur.epa.gov/uploads/238/Figure%202%20metadata.docx
53 Figure1-3%20data.xlsx https://pasteur.epa.gov/uploads/238/Figure1-3%20data.xlsx
10 Figure%203%20metadata.docx https://pasteur.epa.gov/uploads/238/Figure%203%20metadata.docx

Tags

  • farnesene
  • sesquiterpenes
  • ozone
  • air-toxics
  • air-quality
  • secondary-organic-aerosol

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