IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 122 NOM and Aquatic Systems Thursday, 27 August 2026 / Hall C SL58 The Hidden „Reductive Face“ of TripletState Dissolved Organic Matter: A New Electron Donor Mechanism in AOPs Xin Yang1, Qingqing Kong1, Liaoliao Yao1 Sun Yat-sen University, School of Environmental Science and Engineering, Guangzhou, 510275, China yangx36@mail.sysu.edu.cn Dissolved organic matter (DOM) is traditionally viewed as a major inhibitor in advanced oxidation processes (AOPs), both acting as a scavenger of reactive species and competing for photons [1]. This study challenges this conventional paradigm by unveiling the „reductive face“ of the excited triplet state of DOM (3DOM*), demonstrating its potential as a potent endogenous electron donor for oxidant activation. We propose a synergistic oxidation mechanism where 3DOM∗ directly transfers electrons to oxidants (e.g., free chlorine, chlorine dioxide, and monochloramine), triggering the generation of reactive radicals without the need for exogenous catalysts. To decipher this hidden mechanism, we employed laser flash photolysis (LFP) to capture the ultrafast electron transfer kinetics between the triplet states of DOM (and model photosensitizers) and oxidants. Kinetic analysis revealed that 3DOM∗ reacts with these oxidants via a single electron transfer (SET) mechanism with near-diffusioncontrolled rate constants (108– 109 M−1s−1) . Crucially, this interaction does not merely consume the oxidant; rather, it „activates“ it, yielding highly reactive radicals (e.g., HO•, Cl•, and NH2•) [2-4]. In real water matrices, this DOM-sensitized pathway was found to account for a significant proportion of contaminant degradation, effectively transforming the DOM from a passive „scavenger“ into an active „radical generator.“ Our findings indicate that under regulated conditions, the net effect of DOM can be inverted from inhibition to promotion. This work not only provides fundamental insights into the reductive photochemistry of DOM but also suggests a paradigm shift in water treatment: moving from „removing DOM“ to „exploiting DOM“ as a sustainable, metal-free auxiliary photocatalyst. References 1. U. von Gunten, Oxidation Processes in Water Treatment: Are We on Track? Environmental Science & Technology 52 (2018) 5062. 2. Q. Kong, L. Ye, Y. Pan, Y. Zhou, Y. Lei, Z. Zeng, S. Chen, L. Yao, X. Zhang, P. Westerhoff, X. Yang, Photochemical Transformation of Free Chlorine Induced by Triplet State Dissolved Organic Matter, Environmental Science & Technology 57 (2023) 10849.
RkJQdWJsaXNoZXIy NDA4Mjc=