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Xu J.-F.,Zhejiang University | Liang Y.-Y.,Zhejiang University | Ma N.,Zhejiang University | Chen L.-K.,China Kaolin Clay Company | And 2 more authors.
Chinese Journal of Inorganic Chemistry

The hydrated kaolinite with d001=0.85 nm was prepared with simple direct displacement intercalation method by using kaolinite-urea intercalation compound as an intermediate. The microstructure and morphology of kaolinite before and after intercalation were characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The results show that the basal spacing of the kaolinite increases from d001=0.72 nm to d001 =1.08 nm after intercalation with urea. After being grafted with water through washing with acid or water at different temperatures, the hydrated kaolinite with d001=0.85 nm is obtained. And the grain thickness of kaolinite decreases significantly from 25 nm to about 10 nm. The highest content of the hydrated kaolinite appears at high temperature, which is nearly 70% by washing with water at 90 °C. The d001=0.85 nm hydrated kaolinite derived from kaolinite-urea compound has further intercalation ability, and may serve as an excellent precursor for preparing other kaolinite intercalation compounds. The transformation rate of about 100% can be obtained for kaolinite- ethylene glycol intercalation compound from the hydrated kaolinite. Source

Zhou J.,Zhejiang University | Zheng W.,Zhejiang University | Xu J.,Zhejiang University | Chen L.,China Kaolin Clay Company | And 4 more authors.
Clays and Clay Minerals

Creating an environmentally friendly precursor to form a kaolinite intercalation compound is important for promoting the applications of nanohybrid kaolinite in electrochemical sensors, low- or zerotoxicity drug carriers, and clay-polymer nanocompounds. In the present study, a stable hydrated kaolinite pre-cursor with d001 = 0.84 nm was prepared successfully by heating the transition phase, the as-prepared kaolinite-hydrazine intercalate, at temperatures between 40 and 70°C. The structure of the hydrated kaolinite was characterized by X-ray diffraction and infrared spectroscopy. The morphology was examined using scanning electron microscopy. The results showed that the hydrated hydrazine of the transition phase was easy to decompose to hydrazines and water molecules in the interlayer at 40-70°C. Hydrazine molecules de-intercalated gradually, and water molecules remained in the ditrigonal holes of the silicate layer with sufficient stability, finally forming the stable 0.84 nm hydrated kaolinite in the system with a success rate of 80-90%. The 0.84 nm hydrated kaolinite may become an excellent precursor for the preparation of other kaolinite intercalates. A degree of intercalation of ~100% was obtained for the kaolinite-ethylene glycol intercalate, and a degree of intercalation of ~80% was obtained for the kaoliniteglycine intercalate from the 0.84 nm hydrated kaolinite precursor. Source

Zheng W.,Zhejiang University | Zhou J.,Zhejiang University | Zhang Z.,Zhejiang University | Chen L.,China Kaolin Clay Company | And 4 more authors.
Journal of Colloid and Interface Science

The kaolinite-glycine intercalation compound was successfully formed by displacing intercalated guest water molecules in kaolinite hydrate as a precursor. The microstructure of the compound was characterized by X-ray diffraction, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope. Results show that glycine can only be intercalated into hydrated kaolinite to form glycine-kaolinite by utilizing water molecules as a transition phase. The intercalated glycine molecules were squeezed partially into the ditrigonal holes in the silicate layer, resulting in the interlayer distance of kaolinite reaching 1.03nm. The proper intercalation temperature range was between 20°C and 80°C. An intercalation time of 24h or above was necessary to ensure the complete formation of kaolinite-glycine. The highest intercalation degree of about 84% appeared when the system was reacted at the temperature of 80°C for 48h. There were two activation energies for the intercalation of glycine into kaolinite, one being 21kJ/mol within the temperature range of 20-65°C and the other 5.8kJ/mol between 65°C and 80°C. The intercalation degree (N) and intercalation velocity (v) of as a function of intercalation time (t) can be empirically expressed as N=-79.35e-t/14.8+80.1 and v=5.37e-t/14.8, respectively. © 2014 Elsevier Inc. Source

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