Facile synthesis of hydrotalcite and its thermal decomposition kinetics mechanism study with masterplots method

Abstract

Abstract The hydrotalcite, Mg4Al2(OH)12CO3·3H2O, was synthesized via low-heating solid-state reaction at 80 °C. The thermal decomposition of Mg4Al2(OH)12CO3·3H2O experienced two stages. The apparent activation energy Ea was estimated with Vyazovkin procedure. The average values of Ea associated with the two stages were determined to be 110.9 ± 10.3, 140.3 ± 4.2 kJ mol−1, respectively, which the two stages are single-step kinetic processes. Masterplots and nonlinear methods were used to define the most probable reaction mechanisms of the two stages. The results show that the reaction mechanism functions of the two stages are as follows: (i) g(α) = (1 − α)−2 − 1, (ii) g(α) = (1 − α)−1/2 − 1, respectively. The values of pre-exponential factor A for the two stages were obtained on the basis of Ea and g(α). Besides, some thermodynamic functions (ΔS#, ΔH# and ΔG#) of the transition state complexes for the two stages were also calculated.