Clean production of CTAB-montmorillonite: formation mechanism and swelling behavior in xylene

Yu, Wei Hua and Ren, Qian Qian and Tong, Dong Shen and Zhou, Chun Hui and Wang, Hao (2014) Clean production of CTAB-montmorillonite: formation mechanism and swelling behavior in xylene. Applied Clay Science, 97-98. pp. 222-234. ISSN 0169-1317

Abstract

Organo-montmorillonite (OMt) with high swellability in a hydrophobic medium such as xylene was successfully prepared. The process was realized by clean and simple modification of Ca2+-montmorillonite (Ca2+-Mt) with cetyltrimethylammonium bromide (CTAB) dispersed in very small amounts of water and ethanol. In the process, there were no needs for the steps of a Na+-exchange reaction and washing. The mechanisms of formation of OMt and its swellability in xylene were investigated. The distribution of cetyltrimethylammonium (CTA+) cations and CTAB molecules adsorbed in the interlayer spaces, CTAB molecules adsorbed on the external surfaces and free CTAB molecules in the resultant OMt products was determined by the thermogravimetric (TG) and differential thermogravimetry (DTG) of the washed and unwashed OMt. The arrangement models of CTA+ cations in the interlayer spaces were deduced from powder X-ray diffraction (XRD) patterns and Fourier transform infrared (FT-IR) spectra. The results suggested that CTA+ cations and CTAB molecules adsorbed in the interlayer spaces and CTAB molecules adsorbed on the external surfaces of OMt played a role in the modification of Ca2+-Mt by ion exchange, hydrophobic interactions and van der Waals forces. Addition of ethanol into the preparation mixture was favorable for binding more CTA+ cations and CTAB molecules in the interlayer spaces of OMt and enhanced dispersion of clay particles. A maximal 64.0% colloid yield in xylene for the OMt sample, which was higher than that of the commercial OMt produced by a multistep process, was achieved. The formation of good gel-like structure of OMt in xylene depended on proper distribution of CTAB molecules and CTA+ cations on the external and internal surfaces of OMt, ordered arrangements of CTA+ cations in the interlayer spaces of OMt and the small sizes of dispersed OMt particles. A large volume of the networks of OMt particles in xylene was formed by edge-to-edge, face-to-face and face-to-edge between neighboring Mt particles and multifacial linking.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2014 Elsevier B.V. Permanent restricted access to published version due to publisher copyright policy.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - No Department
Date Deposited: 16 Jan 2015 02:06
Last Modified: 07 Jul 2016 06:04
Uncontrolled Keywords: cetyltrimethylammonium bromide; intercalation; modification; montmorillonite; organoclay; xylene
Fields of Research : 09 Engineering > 0912 Materials Engineering > 091299 Materials Engineering not elsewhere classified
09 Engineering > 0905 Civil Engineering > 090503 Construction Materials
03 Chemical Sciences > 0305 Organic Chemistry > 030504 Organic Green Chemistry
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970103 Expanding Knowledge in the Chemical Sciences
Identification Number or DOI: 10.1016/j.clay.2014.06.007
URI: http://eprints.usq.edu.au/id/eprint/26561

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