Formation of intercalation compound of kaolinite–glycine via displacing guest water by glycine

Abstract 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 °C and 80 °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 °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 °C and the other 5.8 kJ/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 = −79.35 e − t /14.8  + 80.1 and v  = 5.37 e − t /14.8 , respectively.