Role of uniform pore structure and high positive charges in the arsenate adsorption performance of Al13-modified montmorillonite.
Role of uniform pore structure and high positive charges in the arsenate adsorption performance of Al13-modified montmorillonite.
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DOI：
10.1016/j.jhazmat.2011.12.035
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发表时间：
2012-02
影响因子：
13.6
通讯作者：
Shou Zhao;C. Feng;Xiangning Huang;Baohua Li;J. Niu;Zhenyao Shen
中科院分区：
文献类型：
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作者：
Shou Zhao;C. Feng;Xiangning Huang;Baohua Li;J. Niu;Zhenyao Shen
研究了四种不同Al 13含量的改性蒙脱石吸附剂（即，合成了Na-Mont、AC-Mont、PAC 20-Mont和Al 13-Mont），并通过N2吸附/脱附、X射线衍射和傅里叶变换红外分析对其进行了表征。还考察了四种吸附剂对砷酸盐的吸附性能，以确定插层Al 13的作用，特别是其高纯度、高正电荷（+7）和特殊的Keggin结构。随着Al 13含量的增加，表面积、结构均匀性、基底间距和孔体积）和吸附性能得到显著但不成比例的改善。吸附数据符合Freundlich和Redlich-Peterson等温模型，动力学数据符合准二级动力学模型。插层Al 13后，蒙脱石对砷酸盐的吸附机理由物理吸附转变为化学吸附。增加电荷的插层离子增强了砷酸盐的吸附动力学，但对蒙脱石的结构变化的影响很小。高纯Al 13插层形成的均匀孔道结构大大增强了孔隙扩散和砷酸根的吸附速率，从而使Al 13-Mont具有较高的吸附性能。
Four modified montmorillonite adsorbents with varied Al13contents (i.e., Na-Mont, AC-Mont, PAC20-Mont, and Al13-Mont) were synthesized and characterized by N2adsorption/desorption, X-ray diffraction, and Fourier-transform infrared analyses. The arsenate adsorption performance of the four adsorbents were also investigated to determine the role of intercalated Al13, especially its high purity, high positive charge (+7), and special Keggin structure. With increased Al13content, the physicochemical properties (e.g., surface area, structural uniformity, basal spacing, and pore volume) and adsorption performance of the modified montmorillonites were significantly but disproportionately improved. The adsorption data well fitted the Freundlich and Redlich–Peterson isotherm model, whereas the kinetic data better correlated with the pseudo-second-order kinetic model. The arsenate sorption mechanism of the montmorillonites changed from physical to chemisorption after intercalation with Al13. Increasing charges of the intercalated ions enhanced the arsenate adsorption kinetics, but had minimal effect on the structural changes of the montmorillonites. The uniform pore structure formed by intercalation with high-purity Al13greatly enhanced the pore diffusion and adsorption rate of arsenate, resulting in the high adsorption performance of Al13-Mont.