AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Secondary Organic Aerosol Formation from Reaction of 3-Methylfuran with Nitrate Radicals
TAEKYU JOO, Jean Rivera-Rios, Masayuki Takeuchi, Matthew Alvarado, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 393 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract Biomass burning is an important source of both primary and secondary organic aerosol (SOA). Recent studies demonstrate that a large fraction of SOA is produced from nontraditional precursors that are highly reactive to hydroxyl (OH) and nitrate (NO3) radicals such as furan derivatives. Here, we investigate gas-phase oxidation and SOA formation from 3-methylfuran via NO3 reaction. Experiments are performed under dry conditions (RH<5%) with different initial concentrations of 3-methylfuran (from 95.9 to 562.8 ppb) at the Georgia Tech Environmental Chamber facility. SOA yield ranges from 1.6 to 2.4% for organic mass loading ranging from 5.1 to 45 μg/m3. More than half of the SOA mass is generated after complete depletion of 3-methylfuran, underlining the importance of higher-generation or heterogeneous reactions to aerosol formation. Particle-phase organic nitrates contribute 39.4% of organics and their volatility (average C* = 10-2.9 μg/m3) is higher than that of non-nitrate organic compounds (average C* = 10-3.3 μg/m3). A reaction mechanism is proposed based on the compounds that are identified using a Filter Inlet for Gases and AEROsols coupled with time-of-flight chemical ionization mass spectrometer (FIGAERO-HR-ToF-CIMS) and C5H5NO5 and C5H6O3 are determined to be the major species in the gas and particle phases, respectively. Thermogram of particle-phase species suggest that oligomer formation determine the SOA composition and formation rate. Both gas-phase ROOR’ formation via RO2 + RO2 (acylperoxy radical) reactions and particle-phase accretion reactions can lead to the formation of the dimeric and higher molecular weight compounds. Results from this study can contribute to our understanding of nighttime NO3 oxidation of furan compounds and aerosol formation in biomass burning plumes.