INFLUENCE OF MEDIUM ON THE PROPERTIES OF BOEHMITE INTERCALATED MONTMORILLONITE

Intercalation of boehmite species has been carried out in different me dia for the preparation of alumina pillared montmorillonite (PILC - pi llared clays). The effect of different media such as water, water-isop ropanol and water-butanol on the intercalation and thermal stability o f the resulting pillared montmorillonite is discussed. Montmorillonite intercalated from different media was characterised by chemical analy sis, XRD, BET, TGA and DTA. The d-spacing of the basal planes increase d from the initial value of 13 Angstrom in montmorillonite to 20-21 An gstrom irrespective of the specific medium, whereas upon heating to 70 0 degrees C the d-spacing decreased to 17-15 Angstrom. The minimum red uction of d-spacing is recorded in PILC prepared in water medium. Spec ific surface area for PILC (water) heated to 300 degrees C is 220 m(2) /g and is retained at 175 m(2)/g even after heating to 700 degrees C. In the case of PILC (methanol) the specific surface area is 225 m(2)/g and 117 m(2)/g after heating to 300 and 700 degrees C respectively. F urther, the surface areas in PILC (isopropanol) and PILC (butanol) are 79 m(2)/g and 94 m(2)/g respectively on samples heated at 700 degrees C. These results suggest the influence of different media of intercal ation on the thermal stability of the PILC. The solvent present in the interlayer region influences the reorientation of pillars during the dehydroxylation process. The high surface tension of the water-air int erface at the interlayer region compared to other solvent-air interfac es in the present study may be able to orient the boehmite species in between the montmorillonite layers to get a homogeneous distribution o f pillars and hence high surface area and porosity at higher temperatu re.