AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Secondary Organic Aerosol Formation from OH-and Cl- Initiated Photo-oxidation of Non-combustion Intermediate Volatility Organic Compounds
SURYA VENKATESH DHULIPALA, Lea Hildebrandt Ruiz, University of Texas at Austin
Abstract Number: 594 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Intermediate volatility organic compounds (IVOCs) are known to contribute significantly to secondary organic aerosol (SOA) in the atmosphere, but their emission, atmospheric concentrations and SOA formation potential remain poorly characterized. Most current air-quality models only account for SOA formation from IVOCs originating from mobile sources or biomass burning. In this work, we focus on Butyl CarbitolTM (Diethylene glycol monobutyl ether) and TexanolTM (ester alcohol), both oxygenated IVOCs which are important constituents in industrial solvents.
TexanolTM was not found to form a significant amount of SOA even after multiple injections of hydroxyl radical precursors as well as chlorine. Butyl CarbitolTM was found to form significant amounts of SOA under all experimental conditions: OH-initiated and Cl-initiated photo-oxidation as well as different levels of NOx. An aerosol chemical speciation monitor (ACSM) was used to quantify the amount of organic aerosol formed and to characterize its composition. A thermodenuder was used to partially evaporate the organic aerosol, and an evaporation model was used to estimate its volatility. A high resolution-time of flight -chemical ionization mass spectrometer (HR-Tof-CIMS) was used to track consumption of precursor IVOCs as well as identify gas-phase products. We found that the presence of NOx resulted in an increase in oxidation state of organic aerosol as compared to low NOx OH-initiated photo-oxidation systems. Overall, our results indicate that Butyl CarbitolTM has a high SOA formation potential and that this class of IVOCs can contribute significantly to SOA formation, which may need to be represented in chemical transport models.