The Surface-mediated Fe(Ⅱ) Reduction System of Iron-pillared Montmorillonite for Efficient Removal of 2-Nitrophenol
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摘要: 通过引入铁氧化物并煅烧处理对蒙脱石进行优化设计,成功合成了铁柱撑蒙脱石复合催化剂(FPMt).采用X射线衍射(XRD)、热重分析(TG)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、N2吸附-脱附(BET)等分析方法对FPMt样品结构与表面性质进行表征,以邻硝基苯酚(2-NP,22 μmol/L)作为代表性污染物研究FPMt的还原催化活性. 结果表明:与蒙脱石相比,FPMt表面电子传输活性得到明显提高,原因是引入赤铁矿的FPMt吸附位点增多同时酸位减少,从而显著增强材料表面的还原催化活性. 除溶液pH和Fe(Ⅱ)浓度外,催化剂的结构完整性、赤铁矿的结晶度等均为影响催化剂还原活性的重要因素. 最后提出了FPMt表面络合态Fe(Ⅱ)的还原催化活性显著提高的介导机制.Abstract: Iron-pillared montmorillonite composite catalyst (FPMt) was successfully synthesized by optimizing the design of montmorillonite through the introduction of iron oxides and the calcination treatment. The structural and surface properties of FPMt samples were characterized with X-ray diffraction (XRD), thermogravimetric analysis (TG), TEM, FT-IR, N2 adsorption and desorption isotherms, and 2-Nitrophenol (2-NP, 22 μmol/L) was used as a representative pollutant to identify the reduction catalytic activity of FPMt. The results showed that, compared to montmorillonite, the surface electron transport activity of FPMt was significantly improved due to the increase of adsorption sites of Fe(Ⅱ) and the corresponding reduction of acid sites on the surface of FPMt, significantly enhancing the reduction catalytic performance of the material. In addition to the solution pH and Fe(Ⅱ) concentration, the structural integrity of the catalyst and the crystallinity of hematite are important factors affecting the catalytic activity. Finally, a mediating mechanism for the significant increase in the reduction catalytic activity of complexed Fe(Ⅱ) on the surface of FPMt was proposed.
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Key words:
- iron-pillared montmorillonite /
- calcination /
- ferrous /
- catalytic reduction /
- 2-Nitrophenol /
- hematite
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表 1 不同FPMt样品的比表面积和孔结构数据
Table 1. The specific surface area and porosity data of different FPMt samples
样品 比表面积/(m2·g-1) 总孔容积/(cm3·g-1) 平均孔径/nm FPMt 126.875 3 0.101 4 5.346 7 FPMt100 112.736 3 0.078 8 4.792 6 FPMt200 138.538 7 0.112 8 4.462 9 FPMt300 144.010 8 0.123 0 4.344 1 FPMt400 165.693 8 0.136 9 4.198 7 FPMt500 155.070 2 0.142 1 4.380 7 表 2 不同FPMt样品的阳离子交换量
Table 2. The cation exchange capacity of different FPMt samples
催化剂 Na+交换量/(mol·(100 g)-1) Mt原样 99 FPMt 92 FPMt100 68 FPMt200 61 FPMt300 55 FPMt400 31 FPMt500 22 注:Na+交换量以每100 g材料吸附Na+的物质的量(mol)计算. -
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