EFFECT OF TRIVALENT CATION ON THE PHYSICOCHEMICAL PROPERTIES OF COBALT CONTAINING ANIONIC CLAYS

A series of cobalt containing hydrotalcites having the general formula CoMCO(3)-HT where M = Al, Fe and Cr were synthesized by sequential an d coprecipitation methods. The samples were primarily characterized by X-ray diffraction (XRD), infrared absorption studies, transmission el ectron microscopy-energy dispersive X-ray analysis (TEM-EDAX), thermog ravimetry-differential scanning calorimetry (TG-DSC) and BET surface a rea measurements. The lattice parameters, FTIR stretching wavelengths for O-H bonds and thermal stability depended on the ionic radius of th e trivalent M cation. Thermal calcination of these materials yielded a non-stoichiometric spinel-type phase whose crystallinity was also aff ected by the nature of the trivalent cation.