Kelli Sikorski  - Investigating the Mechanism of Phenol Photooxidation by Humic Substances

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      Publication Details (including relevant citation   information):

      Golanoski, K.S.; Fang, S.; Del Vecchio, R.; Blough, N.V.   Investigating the Mechanism of Phenol Photooxidation by Humic   Substances. Environ. Sci. Technol. 2012, 46, 3912−3920.


      To probe the mechanism of the photosensitized loss of phenols by   humic substances (HS), the dependence of the initial rate of   2,4,6-trimethylphenol (TMP) loss (RTMP) on dioxygen concentration   was examined both for a variety of untreated as well as   borohydride-reduced HS and C18 extracts from the Delaware Bay and   Mid-Atlantic Bight. RTMP was inversely proportional to dioxygen   concentration at [O2] > 50 μM, a dependence consistent with   reaction with triplet excited states, but not with 1O2 or RO2.   Modeling the dependence of RTMP on [O2] provided rate constants   for TMP reaction, O2

      quenching, and lifetimes compatible with a triplet intermediate.   Borohydride reduction significantly reduced TMP loss, supporting   the role of aromatic ketone triplets in this process. However,   for most samples, the incomplete loss of sensitization following   borohydride reduction, as well as the inverse dependence of RTMP   on [O2] for these samples, suggests that there remains another   class of oxidizing triplet sensitizer, perhaps quinones.

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