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Low Secondary Organic Aerosol Production from Oxygenated Volatile Chemical Products
MACKENZIE HUMES, Mingyi Wang, Sunhye Kim, Jo Machesky, Drew Gentner, Allen Robinson, Neil Donahue, Albert A. Presto, Carnegie Mellon University
Abstract Number: 424
Working Group: Aerosol Chemistry
Abstract
Traditional anthropogenic Secondary Organic Aerosol (SOA) research has focused on emissions from combustion sources, including components of emissions from factories, vehicles, and biomass burning. Emissions of Volatile Chemical Products (VCP) and Intermediate Volatility Chemical Products (IVCP) such as cleaning solvents, pesticides, coatings, and personal care products are now larger than emissions from more traditional sources, in part because of control measures on those sources and due to their large emission factors. Current models under-predict SOA formation and the oxidation products of I/VCPs are likely an overlooked source. Various I/VCPs containing oxygen groups such as glycol ethers, esters, and oxygenated-aromatics have SOA formation potentials which have not been previously studied. I/VCPs containing oxygen groups may have a greater probability of undergoing fragmentation and inhibiting intramolecular hydrogen shifts when oxidized, resulting in less polar, lower molecular weight products. As the volatility is inversely dependent on both molecular weight and polarity, the addition of these groups may prevent SOA formation. In this study, we oxidized common I/VCPs containing oxygen groups under high and low-NOx conditions in an oxidation flow reactor to determine their potential as SOA precursors.
We oxidized four glycol ether I/VCPs, two oxygenated-aromatic VCPs, and two ester VCPs at 50% RH with and without NOx present. The two aromatic ring-containing compounds (2-phenoxyethanol and 1-phenoxy-2-propanol) had SOA mass yields of approximately 15%. CIMS data demonstrated this was due to the formation of lower volatility products from the aromatics. SOA composition varied with NOx level despite similar mass yields. Higher oxidation occurred under low-NOx, though nitrogen content remained low under high-NOx. All non-aromatic species had SOA mass yields below the detection limit. Overall, this supports the idea that oxygen groups can inhibit SOA formation in non-aromatic compounds and that some oxygenated VCPs may be used in consumer products without resulting in SOA production.