Clays and Clay Minerals, Vol. 56, No. 2, 144–154, 2008.
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Authors
Zhu, Jianxi
Zhu, Lizhong
Zhu, Runliang
Chen, Baoliang
Issue Date
2008
Type
Article
Language
Keywords
Periodicals , Geology , Organo-bentonite , Microstructure , Steric Hindrance Mechanisms , Sorption Efficiency , Surfactant Loadings
Alternative Title
Microstructure Of Organo-bentonites In Water And The Effect Of Steric Hindrance On The Uptake Of Organic Compounds
Abstract
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 TransformInfra red (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 from0.20 to 2.56 times the CEC. However, the increase in packing density (r) 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.
Description
Clays and Clay Minerals, Vol. 56, No. 2, 144–154, 2008. Microstructure Of Organo-bentonites In Water And The Effect Of Steric Hindrance On The Uptake Of Organic Compounds. Jianxi Zhu, Lizhong Zhu; Runliang Zhu; Baoliang Chen. DOI: 10.1346/CCMN.2008.0560202. Copyright © 2008, The Clay Minerals Society.
Citation
Clays and Clay Minerals, Vol. 56, No. 2, 144–154, 2008.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018, The Clay Minerals Society