School of Environmental Studies, China University of Geosciences, Wuhan, 430074, People's Republic of China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, People's Republic of China.
Environ Sci Pollut Res Int. 2022 Jun;29(29):44732-44745. doi: 10.1007/s11356-022-18901-z. Epub 2022 Feb 9.
Pollutant degradation via periodate ([Formula: see text]) and transitional metal oxides provides an economical, energy-efficient way for chemical oxidation process in environmental remediation. However, catalytic activation of periodate by manganese dioxide and the associated mechanism were barely investigated. In this study, four MnO polymorphs (α-, β-, γ- and δ-MnO) were synthesized and tested to activate [Formula: see text] for the degradation of sulfamethoxazole (SMX). The reactivity of different MnO structures followed the order of α-MnO > β-MnO > γ-MnO > δ-MnO, suggesting that the particular crystalline structure in α-MnO would exhibit higher activities via [Formula: see text] activation. Herein, in α-MnO/[Formula: see text] system, 91.1% of SMX was eliminated within 30 min with degradation rate constant of 0.0649 min, and the neutral pH exhibited higher efficiency in SMX degradation compared with acidic and alkaline conditions. Singlet oxygen (O) was unveiled to be the dominant ROS according to the results of electron paramagnetic resonance, chemical probes and radical quenching experiments, whereas [Formula: see text] and OH were mainly acted as a free-radical precursor. Six oxidation products were identified by LC-MS, and the elimination of sulfonamide bond, hydroxylation and direct oxidation were found to be the important oxidation pathways. The study dedicates to the mechanistic study into periodate activation over alpha-MnO and provides a novel catalytic activation for selective removal in aqueous contaminants.
过碘酸盐 ([Formula: see text]) 和过渡金属氧化物通过化学氧化过程为环境修复提供了一种经济、节能的污染物降解方法。然而，二氧化锰对过碘酸盐的催化活化及其相关机制几乎没有被研究过。在这项研究中，合成了四种 MnO 多晶型物（α-、β-、γ-和 δ-MnO）并进行了测试，以用于激活 [Formula: see text] 来降解磺胺甲恶唑 (SMX)。不同 MnO 结构的反应活性顺序为 α-MnO > β-MnO > γ-MnO > δ-MnO，表明 α-MnO 中的特殊晶体结构通过 [Formula: see text] 活化会表现出更高的活性。在此，在 α-MnO/[Formula: see text] 体系中，SMX 在 30 分钟内被消除了 91.1%，降解速率常数为 0.0649 min，中性 pH 比酸性和碱性条件下具有更高的 SMX 降解效率。根据电子顺磁共振、化学探针和自由基猝灭实验的结果，揭示了单线态氧 (O) 是主要的活性氧物种，而过碘酸盐和 OH 主要作为自由基前体。通过 LC-MS 鉴定了 6 种氧化产物，发现磺胺基键的消除、羟化和直接氧化是重要的氧化途径。该研究致力于探讨过碘酸盐在 α-MnO 上的活化机制，并为水中污染物的选择性去除提供了一种新的催化活化方法。
