State Key Laboratory of Biochemical Engineering, Key Laboratory of Biopharmaceutical Preparation and Delivery, Chinese Academy of Sciences, Beijing 100190, China.
National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Beijing 100190, China.
Environ Sci Technol. 2023 Sep 12;57(36):13625-13634. doi: 10.1021/acs.est.3c03698. Epub 2023 Aug 31.
In this work, we demonstrate for the first time the abatement of sulfamethoxazole (SMX) induced by stabilized -semiquinone radicals (-SQ) in the MnO-mediated system in the presence of humic acid. To evaluate the performance of different MnO/mediator systems, 16 mediators are examined for their effects on MnO reactions with SMX. The key role of the bidentate Mn(II)--SQ complex and MnO surface in stabilizing SQ is revealed. To illustrate the formation of the Mn(II)--SQ complex, electron spin resonance, cyclic voltammetry, and mass spectra were used. To demonstrate the presence of -SQ on the MnO surface, EDTA was used to quench Mn(II)--SQ. The high stability of -SQ on the MnO surface is attributed to the higher potential of -SQ (0.9643 V) than the MnO surface (0.8598 V) at pH 7.0. The SMX removal rate constant by different stabilized -SQ at pH 7.0 ranges from 0.0098 to 0.2252 min. The favorable model is the rate constant ln () = 6.002(-Q) + 33.744((-Q) - (-Q)) - 32.800, whose parameters represent the generation and reactivity of -SQ, respectively. Moreover, aniline and cystine are competitive substrates for SMX in coupling -SQ. Due to the abundance of humic constituents in aquatic environments, this finding sheds light on the low-oxidant-demand, low-carbon, and highly selective removal of sulfonamide antibiotics.
在这项工作中，我们首次证明了在存在腐殖酸的情况下，MnO 介导的系统中稳定的半醌自由基 (-SQ) 可以消除磺胺甲恶唑 (SMX)。为了评估不同 MnO/介体系统的性能，研究了 16 种介体对 MnO 与 SMX 反应的影响。揭示了双齿 Mn(II)--SQ 配合物和 MnO 表面在稳定 SQ 中的关键作用。为了说明 Mn(II)--SQ 配合物的形成，使用了电子顺磁共振、循环伏安法和质谱。为了证明 MnO 表面上存在 -SQ，使用 EDTA 来猝灭 Mn(II)--SQ。-SQ 在 MnO 表面上的高稳定性归因于 -SQ 的更高电位（0.9643 V）比 pH 7.0 下的 MnO 表面（0.8598 V）高。不同稳定 -SQ 在 pH 7.0 下去除 SMX 的速率常数范围为 0.0098 至 0.2252 min。有利的模型是速率常数 ln () = 6.002(-Q) + 33.744((-Q) - (-Q)) - 32.800，其参数分别代表 -SQ 的生成和反应性。此外，苯胺和半胱氨酸是 SMX 在偶联 -SQ 中的竞争性底物。由于水生环境中腐殖质成分丰富，这一发现为低氧化剂需求、低碳和高度选择性去除磺胺类抗生素提供了思路。
