Structural characterization of kaolinite-nicotinamide intercalation composite

A novel kaolinite-nicotinamide composite was prepared utilizing a kaolinite/N-methylformamide intercalation compound as a precursor material and examined the structural properties of the intercalated species. The X-ray powder diffraction pattern illustrated that intercalation of nicotinamide molecules between the layers of kaolinite caused an emergence of new peaks at 6.87 and 13.63(2θ) with the distance of 12.86 and 6.49 Å, respectively, belonging to the d001 and d002 planes of kaolinite-nicotinamide. The expansion of the d001 basal spacing (5.68 Å) point out the existence of nicotinamide species in the layers of kaolinite which are located as a monolayer arrangement. The aromatic rings of the nicotinamide molecules are perpendicular to the aluminum layers of kaolinite and also both top hydrogen atom of pyridine ring and oxygen atom of carbonyl is keyed into the ditrigonal holes in the silicate layers. The appearance of the peaks at 3630, 3533, 1596 and 1441 cm-1 and decrease of intensity of the inner-surface hydroxyls peak at 3696 cm-1 prove that nicotinamide molecules intercalated into kaolinite layers through forming H-bonds via pyridine ring nitrogen with inner-surface hydroxyls of kaolinite. The thermal stability of intercalated NAM molecules is up to 238°C. The organic molecules located in the interlayer spacing led to an appreciable decrease of particle size and differences in the morphology. The specific and mesoporous surface areas of intercalated composites increased whereas the average pore width of these species decreased with respect to that of pure kaolinite. © 2012 Elsevier B.V. All rights reserved.