A study of the thermal decomposition of cobalt(II) and nickel(II) oxalate dihydrate using direct current electrical conductivity measurements

Abstract

The feasibility of using direct current electrical conductivity measurements to study the solid state reactions involved in the preparation of cobalt oxide and nickel oxide from cobalt(H) and nickel(II) oxalate dihydrate have been analysed. Investigations were carried out using atmospheres of static air, dynamic air and dry nitrogen. The study of the isothermal decomposition of cobalt(II) and nickel(II) oxalate dihydrate at different temperatures in these three atmospheres revealed that the anhydrous complexes are formed first. In static air and dynamic air atmospheres, the cobalt oxalate then undergoes oxidation decomposition to Co 3O 4 with the probable intermediate formation of CoO along with the anhydrous complex. In dry nitrogen also, the formation of CoO is well characterized. For nickel(II) oxalate dihydrate, the final decomposition product in all three atmospheres was found to be NiO. The conductivity measurements were supplemented with data obtained by chemical, thermal (TGA and DTA), IR spectroscopic and X-ray powder diffraction analyses. The gaseous decomposition products were characterized by gas-liquid chromatography.