ALUMINUM SULFATE HYDRATES - KINETICS OF THE THERMAL-DECOMPOSITION OF ALUMINUM SULFATE USING DIFFERENT CALCULATION METHODS

Three different calculation methods of deriving kinetic parameters (ac tivation energy and preexponential factor) from dynamic TG data have b een applied for the sulphate decomposition stage of the aluminum sulph ate octadecahydrate. The constant rate experiments were carried out by Derivatograph and DuPont thermobalances. The three parameters estimat ion methods included a simple differential method, the classical Coats -Redfern and a new direct integral method. The fits of the curves obta ined by these procedures were compared both graphically and numericall y. It was found that the direct integral method gave the most satisfac tory results. With the order type reaction models this method in each case produced the smallest residual deviation values and the best fitt ing curves compared to those obtained by the other two methods. The ac tivation parameters calculated by the differential method were not acc eptable at all, for the estimated curves were very far from the measur ed ones.