Microstructure of organo-bentonites in water and the effect of steric hindrance on the uptake of organic compounds
Microstructure of organo-bentonites in water and the effect of steric hindrance on the uptake of organic compounds
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DOI：
10.1346/ccmn.2008.0560202
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发表时间：
2008-04
影响因子：
2.2
通讯作者：
Jianxi Zhu;Lizhong Zhu;Runliang Zhu;Baoliang Chen
中科院分区：
文献类型：
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作者：
Jianxi Zhu;Lizhong Zhu;Runliang Zhu;Baoliang Chen
为了进一步阐明不同表面活性剂负载量有机膨润土的吸附-分配过渡机理，研究了不同表面活性剂负载量有机膨润土层间表面活性剂聚集体的结构特征，（0.20-2.56倍阳离子交换容量，CEC）进行了原位X射线衍射（XRD）和傅立叶变换红外（FTIR）光谱研究。吸附性能和粘土夹层的结构根据表面活性剂的类型，表面活性剂的加载水平，和粘土中的水合状态而改变。硝基苯，苯酚和苯胺的有机膨润土的吸附的基础上，污染物的吸附系数（KSF），归一化与有机碳含量，显示出显着的依赖表面活性剂加载水平。Ksf值首先随着表面活性剂负载量的增加而增加，直到在CEC的1.0至1.2倍处达到最大值，然后下降。根据与层间空间相关的体积分数的理论计算，层间微环境成为更疏水的介质，有助于有机污染物的溶解，因为表面活性剂负载从CEC的0.20倍增加到2.56倍。然而，插层物的堆积密度（ρ）的增加和诱导的空间位阻都影响结果，即有机污染物可以位于的可接近自由空间的减少，这可能是吸附容量的负面因素。
To further elucidate adsorption-to-partition transitional mechanisms which have been proposed previously for organo-bentonites with different surfactant loadings, the structural characteristics of interlayer surfactant aggregates on organo-bentonite with different surfactant cetyltrimethylammonium bromide loading levels (0.20–2.56 times cation exchange capacity, CEC) have been investigated by in situ X-ray diffraction (XRD) and Fourier TransformInfrared (FTIR) spectroscopy. The sorption properties and the structure of the clay interlayers changed according to the type of surfactant, the surfactant loading level, and the state of hydration in the clays. Based on the sorption of nitrobenzene, phenol, and aniline to organobentonites, the contaminant sorption coefficients (Ksf), normalized with the organic carbon content, show a remarkable dependence on surfactant loading levels. The Ksf values first increased with surfactant loading until reaching a maximum at 1.0 to 1.2 times the CEC, and then decreased. According to the theoretical calculation of the volume fractions relating to the interlamellar space, the interlamellar microenvironment became a more hydrophobic medium, contributing to the dissolution of organic contaminants, as the surfactant loading increased from 0.20 to 2.56 times the CEC. However, the increase in packing density (ρ) for the intercalates, and induced steric hindrances both affect the result in terms of a reduction in the accessible free space where the organic contaminants can be located, which might be a negative factor in the sorption capacity.