Thermal transformation of trinuclear Fe(III) acetato complex intercalated montmorillonite

Fe(III) pillared montmorillonite was prepared using trinuclear acetato complex of Fe(III) as the pillaring agent and the resulted material was characterised by different analytical techniques. Basal spacing of the material is found to be 18 Å even after calcination at 500°C 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 500°C shows the highest surface area of 284 m2/g. Mössbauer analysis was carried to identify the exact phase of Fe(III) formed during thermal treatment. From the Mössbauer 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 γ-FeOOH even at 500°C; whereas, the pure complex decomposed directly to α-Fe2O3 at 300°C. This confirmed the role played by the silicate layer in directing the phase formation of Fe(III) during the heat treatment.