(442b) Secondary Organic Aerosol Formation from Methylfurans By Nitrate Radical Oxidation

An activity that is an important source of both gas- and particle-phase carbon in the atmosphere is biomass burning. Biomass burning contributes to both primary organic aerosol (POA) and secondary organic aerosol (SOA) formation. Recent literature about SOA formation from biomass burning emphasized the importance of the unidentified reaction pathways that contribute to a large fraction of SOA mass. These studies suggested that furan derivatives can be an important contributing factor of nontraditional precursors to SOA formation from biomass burning. One of the main furan derivatives that are emitted by biomass burning is methylfuran isomers. Our current understanding of SOA formation from methylfurans, however, is extremely limited, especially under nighttime oxidation conditions. Here, we investigate SOA formation from 2- and 3-methylfuran by nitrate radical (NO₃) oxidation at the Georgia Tech Environmental Chamber (GTEC) facility. We used High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) coupled with a Filter Inlet for Gases and AEROsols (FIGAERO) for the real-time measurement of oxidation products. This setup allowed us to measure both gas- and particle-phase composition during the oxidation process. The increase of aerosol mass concentration was measured with a Scanning Mobility Particle Sizer (SMPS) and the methlfuran decay was measured with Gas Chromatography Flame Ionization Detector (GC-FID). Aerosol mass continued to increase after all 2- and 3-methylfuran were consumed, indicating a large contribution of higher-generation oxidation products to SOA mass. Organic nitrate (RONO₂) contribution was around 25% to the total organics measured by HR-ToF-AMS. Multiple monomer and dimer species that contain an -ONO₂ functional group were detected by FIGAERO-ToF-CIMS. These results indicate that the RONO₂ species are also important in terms of SOA formation, which have not yet been considered in 2- and 3-methylfuran SOA studies to date.