Effect of Intercalation Agents on Morphology of Exfoliated Kaolinite

Xiaochao Zuo,Shilong Zhang,Huaming Yang,Ding Wang,Qinfu Liu

doi:10.3390/min7120249

Xiaochao Zuo, Shilong Zhang + Show 3 more

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https://doi.org/10.3390/min7120249

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Abstract

Kaolinite intercalation compounds were prepared by intercalating fatty acids and quaternary ammonium salts into kaolinite layers, using methanol-grafted kaolinite as the precursor. Meanwhile, massive lamellas were exfoliated during the intercalation process. The interlayer structure, chemical bonding and morphology of kaolinite before and after intercalation were characterized in detail. As the alkyl chain length increases, the basal spacing of kaolinite increases gradually. The morphology analysis indicated that the ionic type of intercalation agent has a more important influence on the morphology change of kaolinite than their alkyl chain length. The initial kaolinite layers were mostly transformed into nanoscrolls in the product intercalated with stearyl trimethyl ammonium chloride (STAC). The present study demonstrates the arrangement model of intercalated molecules between kaolinite layers using X-ray diffraction (XRD) in conjunction with Fourier transform infrared (FTIR) and stereochemical calculation. On the basis of a probed arrangement model, the mechanism of effect of the alkyl chain length and ionic type of intercalation agent on the morphology of exfoliated kaolinite is suggested.

Highlights

Kaolinite is a widely studied and applied class of phyllosilicate minerals [1,2,3,4,5,6]
X-ray diffraction (XRD) data of the intercalation products show that their basal spacings are expanded to a length much longer than 0.72 nm, the basal spacing of kaolinite/fatty acid intercalation compounds (K-Fas) and kaolinite/quaternary ammonium salts intercalation compounds (K-Qas), indicating that Fas and Qas intercalate into kaolinite layers
The morphology, and chemical bondingbonding of kaolinite compounds compounds with different species are investigated in detail

Summary

Introduction

Kaolinite is a widely studied and applied class of phyllosilicate minerals [1,2,3,4,5,6]. The exfoliation of kaolinite has received a lot of attention because of its ability to greatly enhance certain properties of the resulting nano kaolinite. Existing exfoliating methods include high-pressure extrusion, mechanical grinding, chemical intercalation, and so on [12,13,14]. Chemical intercalation is considered the most effective way to achieve the exfoliation of kaolinite. The negligibly small cation-exchange capacity of kaolinite makes it very difficult to intercalate organic guest species into basal space. This is because any two contiguous layers of kaolinite are linked through strong hydrogen bonds arising from the interactions between Al–OH and Si–O groups

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