GIST Scholar
College of Engineering
Department of Environment and Energy Engineering
1. Journal Articles
Transformation ofDissolved Organic Matter by AqueousFe(IV) under Acidic Conditions: Bulk-to-Molecular Insights into ReactionKinetics and Mechanisms
- Type
- Article
- Citation
- ENVIRONMENTAL SCIENCE & TECHNOLOGY
- Issued Date
- ACCEPT
- Abstract
- Aqueous Fe(IV) has emerged as a significant nonradical oxidant in iron-based oxidative water treatment, yet its reaction kinetics and mechanisms with dissolved organic matter (DOM) remain largely unexplored. Herein, second-order rate constants (k) for Fe(IV) reactions with DOM and DOM-relevant model compounds were determined under acidic conditions using a competition kinetics method performed on self-assembled quenched-flow apparatuses. At pH 3.0, k for 15 DOM isolates ranged from (2.1 +/- 0.2) & times; 104 MC -1 s-1 to (11.6 +/- 0.9) & times; 104 MC -1 s-1 and correlated strongly with the electron-donating capacity of DOM. Similarly, k for nine para-substituted phenolic compounds correlated linearly with the Hammett constant sigma+, E HOMO, and vertical ionization potential, supporting Fe(IV) selectivity toward electron-rich substrates. Across pH 1.0-3.5, k for DOM increased monotonically from the 104 to 105 MC -1 s-1 scale. In contrast, k for 11 model compounds representing major DOM moieties spanned 101-107 M-1 s-1 and exhibited moiety-specific pH dependences, indicating that individual DOM components contribute differently to overall Fe(IV)-DOM reactivity. Fluorescence spectroscopy revealed broad-spectrum oxidation of DOM fluorophores, whereas high-resolution mass spectrometry showed that Fe(IV) preferentially transformed unsaturated moieties, oxidized nitrogen/sulfur-containing functionalities, and fragmented moderate-molecular-weight molecules. These findings provide a bulk-to-molecular kinetic and mechanistic basis for predicting Fe(IV) fate in DOM-containing waters and optimizing Fe(IV)-based advanced oxidation processes.
- Publisher
- AMER CHEMICAL SOC
- ISSN
- 0013-936X
- Appears in Collections:
- Department of Environment and Energy Engineering > 1. Journal Articles
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