Catalyst-free activation of permanganate under visible light irradiation for sulfamethazine degradation: Experiments and theoretical calculation.
Catalyst-free activation of permanganate under visible light irradiation for sulfamethazine degradation: Experiments and theoretical calculation.
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DOI：
10.1016/j.watres.2021.116915
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发表时间：
2021-02
期刊：
影响因子：
12.8
通讯作者：
Chen Zhang;S. Tian;F. Qin;Yaling Yu;Danlian Huang;Abing Duan;Chengyun Zhou;Yang Yang-Yang;
中科院分区：
文献类型：
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作者：
Chen Zhang;S. Tian;F. Qin;Yaling Yu;Danlian Huang;Abing Duan;Chengyun Zhou;Yang Yang-Yang;
本研究采用可见光（VL）对高锰酸盐（PM）进行活化，无需添加催化剂，并选择磺胺甲基嗪（SMT）作为探针化合物。实验结果表明，通过拟一级反应动力学，VL/PM体系可以有效降解SMT。考察了PM用量、溶液pH、湿酸（HA）和共存阴离子（CO32−、SO42−、Cl−和NO3−）对SMT光降解的影响。焦磷酸盐（PP）由于与Mn （III）的络合作用，对SMT的降解具有抑制作用。电子自旋共振（ESR）光谱和紫外可见分光光度计证实，VL可以激活PM生成·O2−和Mn （III）活性物质。此外，基于活性位点预测、中间体鉴定和密度泛函数理论（DFT）计算，提出了SMT分子重排和S-N键裂解两种主要降解途径。此外，还计算了两种降解途径的能垒。本研究为水相SMT的去除提供了一种新的方法，并通过DFT计算加深了我们对SMT降解机理的理解，希望对VL/PM处理的未来发展有所启示。
In this study, visible light (VL) was adopted for permanganate (PM) activation without additional catalyst, where sulfamethazine (SMT) was selected as the probe compound. Experiment results showed that the VL/PM system can effectively degrade SMT through pseudo-first-order reaction kinetics. Influencing factors including PM dosage, solution pH, humid acid (HA) and coexisting anions (CO32−, SO42−, Cl−and NO3−) which affect SMT photo-degradation were also examined. Pyrophosphate (PP) had an inhibitory effect on SMT degradation due to the complexation of PP with Mn (III). Electron spin resonance (ESR) spectrometry and UV-Vis spectrophotometer proved that VL can activate PM to generate ·O2−and Mn (III) reactive species. Furthermore, based on the active site prediction, intermediates identification and Density Functional Theory (DFT) calculation, two main degradation pathways involving SMT molecular rearrangement and cleavage of S–N bond were proposed. Moreover, the energy barriers of the two degradation pathways were also calculated. This study offers a novel approach for aqueous SMT removal and deepens our understanding of the degradation mechanism of SMT through DFT calculation, which hopes to shed light on the future development of VL/PM treatment.