期刊
ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 56, 期 24, 页码 17720-17731出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.est.2c06290
关键词
UVA-LED; Mn(VII); micropollutant; degradation mechanism
资金
- National Natural Science Foundation of China [52100013]
- Natural Science Foundation of Guangdong Province [2022A1515011207]
- Guangdong Provincial Department of Education Youth Innovation Talent Project (Natural Science) [2020KQNCX092]
- Student Innovation and Entrepreneurship Program of Wu y i University [2020CX12]
- Open Project of State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology [ES202222]
- Research Project of High-level Talents of Wuyi University [2019AL024]
This study introduced UVA-LED photolysis of Mn(VII) for degrading micropollutants and found that factors like light intensity, radiation wavelengths, pH, and water constituents affect the degradation rates of DCF and 4-CP. RMnS play a significant role in the degradation process.
Permanganate [Mn(VII)] has gained broad attention in water treatment. However, its limited reactivity toward some refractory micropollutants hinders its application for micropollutant degradation. Herein, we introduced UVA-LED photolysis of Mn(VII) (UVA-LED/Mn(VII)) to degrade micropollutants (diclofenac (DCF), 4-chlorophenol (4 -CP), atrazine, and nitrobenzene) by selecting DCF and 4-CP as target micropollutants. The effects of operating conditions (e.g., light intensity, radiation wavelengths, pH, and water constituents) on DCF and 4-CP degradation as well as the underlying mechanisms were systematically studied. The degradation rates of DCF and 4-CP linearly decreased with increasing radiation wavelengths (from 365 to 405 nm), likely due to the decreased molar absorption coefficients and quantum yields of Mn(VII). Reactive manganese species (RMnS), including Mn(V), Mn(III), and HO center dot, were generated in the UVA-LED/Mn(VII) process. Mn(V) and HO center dot were responsible for DCF degradation, while Mn(III), HO center dot, and likely Mn(V) accounted for 4-CP degradation. Competitive kinetic results revealed that contributions of RMnS and HO center dot decreased with increasing radiation wavelengths, wherein RMnS played the dominant role. Increasing pH displayed opposite effects on DCF and 4-CP degradation with higher degradation efficiency obtained at acidic pH for the former one but alkaline pH for the latter one. The presence of water background ions (e.g., Cl-, HCO3 -, and Ca2+) barely influenced DCF and 4-CP degradation. Finally, in comparison with Mn(VII) alone, enhanced degradation of DCF and 4-CP by UVA-LED/Mn(VII) was observed in real waters. This work advances the understanding of the photochemistry of manganese species in micropollutant degradation and facilitates Mn(VII) oxidation in practical application.
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