AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Secondary Organic Aerosol Produced from Aqueous Reaction of Phenols with an Organic Excited Triplet State and Hydroxyl Radical
JEREMY SMITH, Haley Kinney, Lu Yu, Kathryn George, Travis Ruthenburg, Ann Dillner, Qi Zhang, Cort Anastasio, University of California, Davis
Abstract Number: 322 Working Group: Aerosol Chemistry
Abstract While reactions in atmospheric condensed phases can form and transform secondary organic aerosol (SOA), these reactions are not well represented in many air quality models. Many of the previous studies of aqueous SOA focused on small, non-aromatic compounds such as glyoxal and methyglyoxal, but here we are interested in benzene diols (aka diphenols or dihydroxybenzenes), which are emitted from biomass burning and formed from the oxidation of anthropogenic aromatics. These compounds possess significant water solubility, with Henry’s Law constants above 1000 M atm-1, and thus are good candidates for precursors of aqueous SOA.
In this study we examined aqueous SOA production from the oxidation of three benzene- diols (catechol, resorcinol, and 1,4-hydroquinone) by OH and the triplet excited state of 3,4-dimethoxybenzaldehyde (DMB). We chose DMB as a model atmospheric photosensitizer because it is released in significant quantities during wood and biomass combustion. We measured two components in our reaction systems: (1) the kinetics of benzene diol oxidation and (2) the SOA mass yield from these reactions. Our results indicate that aqueous oxidation of benzene diols via triplet excited states proceeds rapidly under atmospherically relevant conditions. SOA formation is very efficient with both of these oxidants, with SOA yields near or above 100%. The SOA products absorb significant amounts of UV-A light and appear to be highly oxidized. We will discuss these results and compare them to our recent studies of the oxidation of other biomass-burning phenols (phenol, guaiacol, syringol).