Effects of NOx on the volatility of secondary organic aerosol from isoprene photooxidation

Journal Article · Tue Jan 28 00:00:00 EST 2014 · Environmental Science & Technology, 48(4):2253–2262

DOI:https://doi.org/10.1021/es404842g· OSTI ID:1130242

Xu, Lu; Kollman, Matthew S.; Song, Chen; Shilling, John E.; Ng, L. N.

The effects of NOx on the volatility of the secondary organic aerosol (SOA) formed from isoprene photooxidation are investigated in environmental chamber experiments. Two types of experiments are performed. In HO2-dominant experiments, organic peroxy radicals (RO2) primarily react with HO2. In mixed experiments, RO2 reacts through multiple pathways. The volatility and oxidation state of isoprene SOA is sensitive to and displays a non-linear dependence on NOx levels. When initial NO/isoprene ratio is approximately 3 (ppbv:ppbv), SOA are shown to be most oxidized and least volatile, associated with the highest SOA yield. A High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) is applied to characterize the key chemical properties of aerosols. While the composition of SOA in mixed experiments does not change substantially over time, SOA become less volatile and more oxidized as oxidation progresses in HO2-dominant experiments. Analysis of the SOA composition suggests that the further reactions of organic peroxides and alcohols may produce carboxylic acids, which might play a strong role in SOA aging.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1130242
• Report Number(s): PNNL-SA-99633; KP1701000
• Journal Information: Environmental Science & Technology, 48(4):2253–2262, Journal Name: Environmental Science & Technology, 48(4):2253–2262
• Country of Publication: United States
• Language: English