Preparation and characterization of an aluminosilicate material with layer expansion structure

Abstract

The aluminosilicate material with layer expansion structure was prepared by the first urea intercalation and subsequent rapid calcination of kaolinite-urea intercalation complex with urea and potassium chlorate. The driving force for expanding kaolinite layer to obtain the aluminosilicate material was the energy released by the reaction of added urea and KClO3 at high temperature. The mass ratio of urea to KClO3 (U/P ratio) had a positive correlation with the energy released by the reaction. The expansion degree of kaolinite layer could be controlled by adjusting U/P ratio through the control of released energy. When U/P ratio exceeded 0.49, the 001 reflection of kaolinite completely disappeared, indicating the full expansion of aluminosilicate layers. The SEM and TEM images revealed that the layers were expanded to form a fishing net-like porous structure with the layer thickness in the range of about 20 to 190 nm. The specific surface area and the total pore volume of the aluminosilicate material was found to be 2.5 and 2.7 times larger, respectively, than that of the raw kaolin. The aluminosilicate material surface was more negatively-charged with higher absolute ζ-potential and higher methylene blue adsorption capacity than the raw kaolinite. The expansion treatment of layer structure was an efficient and facile method to expand the application field of kaolinite.