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Updated: Sep 15, 2025
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Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
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Quantitative Profiling of Elementary Reaction Steps in Sulfate Radical-Based Treatment Processes: A Two-Loop
Kanying Miu1,2, Yunxiang Meng1,2, Yiqi Yan1,2
1Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China.
Environmental Science & Technology
|July 16, 2025
Summary
Understanding radical reaction mechanisms in advanced oxidation processes is key for contaminant degradation. This study quantifies sulfate and carbonate radical decay kinetics, revealing key reactions and lifetime discrepancies between systems.
Area of Science:
- Environmental Chemistry
- Water Treatment Technologies
- Chemical Kinetics
Background:
- Advanced oxidation processes (AOPs) utilize radical reactions for organic contaminant degradation.
- Elucidating complex radical reaction mechanisms is crucial for optimizing AOP performance.
- Transient radical species and branched pathways present significant challenges in kinetic analysis.
Purpose of the Study:
- To investigate the decay kinetics of sulfate (SO4•-) and carbonate (CO3•-) radicals.
- To identify and quantify the elementary reactions governing radical consumption in different AOP systems.
- To compare radical lifetimes and reaction pathways between UV/persulfate (PS) and UV/hydrogen peroxide (H2O2) systems.
Main Methods:
- Utilized time-resolved spectroscopy to monitor radical decay.
- Employed a two-loop self-consistent approach to test mechanistic hypotheses.
- Directly quantified the contribution of individual elementary reactions to overall radical loss.
Main Results:
- Identified four dominant elementary reactions controlling SO4•- decay in UV/PS systems.
- Found CO3•- kinetics in UV/PS/HCO3- systems are primarily governed by self-termination.
- Determined CO3•- kinetics in UV/H2O2/HCO3- systems involve self-termination and reaction with H2O2.
- Observed a 2-order of magnitude difference in CO3•- lifetime between the two systems (9.07 ms vs. 70.2 μs).
Conclusions:
- Provided direct evidence for specific elementary reactions governing sulfate and carbonate radical decay.
- Quantified the contribution of each reaction to radical consumption, enhancing mechanistic understanding.
- Highlighted how different AOP chemistries lead to significant variations in radical lifetimes and degradation efficiencies.
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