Thermal transformation of trinuclear FeIII/ acetato complex intercalated montmorillonite

Abstract

FeIII. pillared montmorillonite was prepared using trinuclear acetato complex of FeIII. as the pillaring agent and the resulted material was characterised by different analytical techniques. Basal spacing of the material is found to be 18 A° even after calcination at 5008C indicating the formation of stable pillars. Thermal analysis indicate that the complex decomposes slowly from the silicate layer at higher temperature to form metal oxyhydroxide pillars. Sample calcined at 5008C shows the highest surface area of 284 m2rg. Mo¨ssbauer analysis was carried to identify the exact phase of FeIII. formed during thermal treatment. From the Mo¨ssbauer spectra recorded at 298 and 77 K, it is observed that the species formed from the decomposition of the acetyl group of the complex is g-FeOOH even at 5008C; whereas, the pure complex decomposed directly to a-Fe2O3 at 3008C. This confirmed the role played by the silicate layer in directing the phase formation of FeIII. during the heat treatment.