Influences of thermal pretreatment temperature and solvent on the organosilane modification of Al13-intercalated/Al-pillared montmorillonite

Abstract

The grafting reactions between 3-aminopropyltriethoxysilane and Al13-intercalated/Al-pillared montmorillonites thermally pretreated at different temperatures were investigated by using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis and nitrogen adsorption-desorption isotherms. The porous structures and the grafting degree of the organosilane modified Al13-intercalated/Al-pillared montmorillonite products are significantly affected by the solvents. The product prepared in anhydrous ethanol has high specific surface area (~160m2g-1) and larger porous volume (0.134cm3g-1) but low degree of grafting modification, while the one prepared in cyclohexane has a high loading amount of silane (2.02mmolg-1) but low surface area (7m2g-1). Thermal treatment affects the grafting process by both reducing the water content in the interlayer space of the pillared montmorillonite and causing the transformation of the interlayer Al compounds from polycations to oxides. The hydrolyzed 3-aminopropyltriethoxysilane is mainly grafted onto the surface of the interlayer Al Keggin ions and/or Al oxides. This study demonstrates the functionalization of pillared clay to form inorganic-organic hybrid material that combines the high porosity of inorganic pillared clay and the lipophilicity of organoclay by adjusting the solvents and the pretreatment conditions, enabling potential applications in adsorption and environmental restoration. © 2010 Elsevier B.V.