SCIENCE OF THE TOTAL ENVIRONMENT
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2024
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IF 8.2
Song Gao,Xinghao Wang,Xinhao Wang,Xiru Chen,Sijia Liang,Ziyan Zhou,Shuxia Xu,Yanfen Fang,Juan Gao,Cheng Gu
Aqueous trivalent manganese [Mn(III)], an important reactive intermediate, is ubiquitous in natural surface water containing humic acid (HA). However, the effect of low-molecular-weight organic acids (LMWOAs) on the formation, stability and reactivity of Mn(III) intermediate is still unknown. In this study, six LMWOAs, including oxalic acid (Oxa), salicylic acid (Sal), catechol (Cat), caffeic acid (Caf), gallic acid (Gal) and ethylene diamine tetraacetic acid (EDTA), were selected to investigate the effects of LMWOAs on the degradation of BPA induced by in situ formed Mn(III)-L in the HA/Mn(II) system under light irradiation. The chromophoric constituents of HA could absorb light radiation and generate superoxide radical to promote the oxidation of Mn(II) to form Mn(III), which was further involved in transformation of BPA. Our results implied that different LMWOAs did significantly impact on Mn(III) production and its degradation of BPA due to their different functional group. EDTA, Oxa and Sal extensively increased the Mn(III) concentration from 50 to 100 μM compared to the system without LMWOAs, following the order of EDTA > Oxa > Sal, and also enhanced the degradation of BPA with the similar patterns. In contrast, Cat, Caf and Gal had an inhibitory effect on the formation of Mn(III), which is likely because they consumed the superoxide radicals generated from irradiated HA, resulting in the inhibition of Mn(II) oxidation and further BPA removal. The product identification and theoretical calculation indicated that a single electron transfer process occurred between Mn(III)-L and BPA, forming BPA radicals and subsequent self-coupling products. Our results demonstrated that the LMWOAs with different structures could alter the cycling process of Mn via complexation and redox reactions, which would provide new implications for the removal of organic pollutants in surface water.
研究领域:
环境科学
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化学
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产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Guiyuan Cai,Yu Tian,Lipin Li,Wenxuan Zhang,Rui Huang,Jun Zhang,Qinyu Wang,Hua Xu,Yifeng Zhang
The activation of sulfite [S(IV)] by transition metals, a new generation of advanced oxidation processes, has been widely studied for water purification. However, the application of this process to oxidize and remove arsenite [As(III)] from water through Fe-based S(IV) activation and the associated mechanisms are not fully understood. In particular, rapid removal of As(III) and secondary metal contamination have presented challenges. Herein, we develop a novel sea urchin-like magnetic Fe-Mn bimetallic oxides (FeMnO)-activated S(IV) process to address these issues. Under neutral pH, the FeMnO/S(IV) system achieved a 99.2 % removal of As(III) within only 10 min with residual arsenic concentration below 10 µg/L, and the removed As(III) was fully oxidized to arsenate [As(V)]. Additionally, FeMnO was recyclable and capable of treating actual arsenic-contaminated water. Furthermore, the oxidation mechanism of non-radical active trivalent manganese [Mn(III)] was discovered during the reaction between the FeMnO/S(IV) system and As(III). The FeMnO catalyst activated S(IV) to generate oxysulfur radicals (i.e., SO 5 •– , SO 4 •– and SO 3 •– ), but they were not the primary oxidizing species for As(III). Instead, As(III) oxidation was mainly attributed to the active Mn(III) generated by the electron transfer between the FeMnO catalyst and SO 5 •– radicals. The discovery of active Mn(III) species in this work may provide a new avenue for developing novel Fe-Mn-type adsorbents to purify arsenic-contaminated water.
研究领域:
环境科学
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水处理技术
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化学工程
✓ 已验证
DOI
高影响因子
Journal of Water Process Engineering
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2023
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IF 7
Jinbing Huang,Xiaoyan Liu,Shiwei Xie
Although electrochemical activation of permanganate ( E -PM) is a green and efficient method to degrade refractory organics by in-situ generated reactive Mn( III ) aq , this process highlights on the presence of promoter and/or stabilizer. Oxalate (OA) is a widespread organic chelate in natural water bodies (with concentrations up to 1 mM), but whose effect on the E -PM process is still unclear. In this study, we found electrolysis and the presence of OA both promote the activation of PM for the degradation of diclofenac (DCF), showing a high synergistic coefficient (3.23) and elevated reaction constant (0.1395 min −1 ). Nevertheless, this process is highly pH-dependent, behaving decreased reactivity as pH value increasing from 3 to 11. Sufficient concentration of OA (≥0.5 mM in this study) is required for stabilizing Mn(III). UV–vis spectra, visual evidence and quenching experiments identified the presence and dominant role of Mn(III)-OA on the degradation of DCF. Using chronoamperometry, we confirmed Mn(III)-OA was primarily generated from the electro-reduction of PM in the presence of OA at pH 5.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
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