Jeremy Smith - Aqueous benzene-diols react with an organic triplet excited state and hydroxyl radical to form secondary organic aerosol

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      Publication Details (including relevant citation   information):

      Physical Chemistry Chemical Physics; 2015; DOI:10.1039/c4cp06095d



      Chemical processing in atmospheric aqueous   phases, such as cloud and fog drops, can play a significant role   in the production and evolution of secondary organic aerosol   (SOA).   In this work we examine aqueous   SOA production via the oxidation of benzene-diols   (dihydroxy-benzenes) by the triplet excited state of   3,4-dimethoxybenzaldehyde, 3DMB*, and by hydroxyl radical,  OH.  Reactions of the three benzene-diols   (catechol (CAT), resorcinol (RES) and hydroquinone (HQ))   with 3DMB* or OH proceed rapidly, with rate constants near   diffusion-controlled values.  The two oxidants exhibit different behaviors   with pH, with rate constants for 3DMB* increasing as pH decreases from pH 5 to   2, while rate constants with OH decrease in more acidic   solutions.  Mass yields of SOA were near 100% for all   three benzene-diols with both oxidants. We also examined the   reactivity of atmospherically relevant mixtures of phenols and   benzene-diols in the presence of 3DMB*.  We find that the kinetics of phenol and   benzene-diol loss, and the production of SOA mass, in mixtures   are generally consistent with rate constants determined in   experiments containing a single phenol or   benzene-diol.  Combining our aqueous kinetic and SOA mass   yield data with previously published gas-phase data, we estimate   a total SOA production rate from benzene-diol oxidation in a   foggy area with significant wood combustion to be nearly 0.6 µg   mair-3  hr-1, with approximately half from the aqueous   oxidation of resorcinol and hydroquinone, and half from the   gas-phase oxidation of catechol.


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