10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Gas and Particle Phase Products of the Reaction of 1-Decanol with OH Radicals in the Presence of NOx
ALLISON DAVIS, Xiaoxi Liu, Jose-Luis Jimenez, Paul Ziemann, University of Colorado-Boulder
Abstract Number: 1565 Working Group: Aerosol Chemistry
Abstract The products and mechanism of secondary organic aerosol (SOA) formation from the OH radical-initiated reaction of 1-decanol in the presence of NOx were investigated in an environmental chamber. Controlled environmental chamber studies provide data concerning gas-phase chemistry as well as gas-particle partitioning and particle-phase reactions, which are necessary for developing detailed chemical models for use in predicting atmospheric fate of volatile organic compounds (VOCs) and SOA formation. Understanding the fate of alcohols in the atmosphere is of increasing importance in rural and urban environments. Alcohols are widely used in industrial solvents and as fuel sources and are emitted into the atmosphere by vegetation. In this study, particle-phase products were analyzed in real time with a thermal desorption particle beam mass spectrometer and off-line following collection onto filters. Subsequent analysis of functional groups by derivatization-spectrophotometric methods developed in our lab allowed quantification of carbonyl, hydroxyl, carboxyl, ester, nitrate, and peroxide functional groups. Derivatized products were also separated by high performance liquid chromatography for molecular quantitation by UV absorbance and identification using chemical ionization-ion mass spectrometry. Identified products consist of highly multi-functional compounds containing various combinations of functional groups and include hydroxydinitrates and dihydroxynitrates, and some also contain an aldehyde group which may promote the formation of low volatility oligomers and cyclic hemiacetals. A suite of experiments employing these methods probed the role of functional groups in aging SOA. Identification and quantification of first, second, and older generation products is necessary for understanding the influence of particle composition on gas-particle partitioning, particle-phase reactions, and SOA properties such as viscosity. Measurements of gas and particle phase products of alcohol oxidation also offer insight into the chemical mechanism and physical processes leading to SOA formation.