Evaluating the Microheterogeneous Distribution of Photochemically Generated Singlet Oxygen Using Furfuryl Amine

• DOI: 10.1021/acs.est.3c01726
• Publication Date: 2023-05-02T21:24:54Z
• Authors: Kai Cheng; Lizhong Zhang; Garrett McKay
• Keywords: Furfuryl alcohol; Aqueous two-phase system

Singlet oxygen (1O2) is an important reactive species in natural waters produced during photolysis of dissolved organic matter (DOM). Prior studies have demonstrated that 1O2 exhibits a microheterogeneous distribution, with [1O2] the interior DOM macromolecules ∼30 to 1000-fold greater than bulk solution. The profile for DOM-containing solutions has been determined mainly by use hydrophobic probes, which are not commercially available. In this study, we employed dual-probe method combining widely used hydrophilic probe furfuryl alcohol (FFA) and its structural analogue amine (FFAm). FFAm exists as cation at pH <9 was therefore hypothesized enhanced local concentration near-DOM phase, whereas FFA will be distributed homogeneously. pair quantify apparent samples from different isolation procedures (humic acid, fulvic reverse osmosis) diverse origins (aquatic terrestrial) function ionic strength, all studied exhibited reactivity relative FFA, especially 7 8. To spatial distribution [1O2], combined electrostatic models Latch McNeill's three-phase model. Modeling results Suwannee River humic acid (SRHA) yield surface ∼60 pM, ∼96-fold higher aqueous-phase measured FFA. This value agreement prior reports 1–3 orders magnitude phase compared Overall, work expands knowledge base photochemistry showing isolates exhibit phenomenon. addition, approach modeling offer new way gain mechanistic insight into potentially other photochemically intermediates.