The kinetic parameters of thermal decomposition hydrated iron sulphate

Abstract

The thermal decomposition of iron sulphate hexahydrate was studied by thermogravimetry at a heating rate of 5°C min⁻¹ in static air. The kinetic parameters were evaluated using the integral method by applying the Coats and Redfern approximation. The thermal stabilities of the hydrates were found to vary in the order. Fe₂(SO₄)₃·6H₂O → Fe₂(SO₄)₃·4.5H₂O → Fe₂(SO₄)₃·0.5H₂O

The dehydration process of hydrated iron sulphate was found to conform to random nucleation mass loss kinetics, and the activation energies of the respective hydrates were 89.82, 105.04 and 172.62 kJ mol⁻¹, respectively. The decomposition process of anhydrous iron sulphate occurs in the temperature region between 810 and 960 K with activation energies 526.52 kJ mol⁻¹ for the D3 model or 256.05 kJ mol⁻¹ for the R3 model.