Journal of Colloid and Interface Science, Vol.432, 278-284, 2014
Formation of intercalation compound of kaolinite-glycine via displacing guest water by glycine
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 1.03 nm. The proper intercalation temperature range was between 20 degrees C and 80 degrees C. An intercalation time of 24 h 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 degrees C for 48 h. There were two activation energies for the intercalation of glycine into kaolinite, one being 21 kJ/mol within the temperature range of 20-65 degrees C and the other 5.8 kJ/mai between 65 degrees C and 80 degrees 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. (C) 2014 Elsevier Inc. All rights reserved.