AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Missing Urban Aerosol Source: Secondary Organic Aerosol Formation from Glycol Ethers Photooxidation under Low NOx Conditions
LIJIE LI, Mary Kacarab, David R. Cocker III, University of California, Riverside
Abstract Number: 271 Working Group: Urban Aerosols
Abstract Missing SOA precursor sources may significantly contribute to the underestimation of urban SOA. Glycol ethers are widely used as a solvent in the consumer product industries. It is observed that even glycol ethers (e.g. Diethylene glycol ethyl ether) categorized as low vapor pressure-volatile organic compounds (LVP-VOCs) are available for atmospheric oxidation and SOA formation. Previous studies only focus on the gas phase oxidation of ethers and seldom address the potential of SOA formation from ethers. This study investigates SOA formation from selected glycol ethers and their structurally related ethers photooxidized in UCR CE-CERT environmental chamber under low NOx conditions (~20-40 ppb NO$_x or <1ppb NO$_x). Further, chemical composition, volatility and particle density of ether SOA measured by HR-ToF-AMS, VTDMA, and APM-SMPS respectively are reported. First, SOA yields from these ethers are observed to vary from <1 e$^-4 to 2 e$^-2. Glycol ethers with HO-CH$_2CH$_2-O-CH$_2-R are observed to have higher SOA formation potential compared those without. Representative dioxolane ring fragment m/z73 C$_3H$_5O$_2$^+ is observed in aerosol phase of HO-CH$_2CH$_2-O-CH$_2-R containing ethers. Significant ester fragments (e.g. m/z61 C$_2H$_5O2$^+ and m/z87 C$_4H$_7O$_2$^+) are also found in SOA formed by different ethers. Effect of photooxidation conditions on SOA yields and SOA composition from ethers are discussed. The important SOA formation pathways from glycol ethers are then proposed.