The non-isothermal kinetic analysis of the thermal decomposition of kaolinite by thermogravimetric analysis

Abstract

The dehydroxylation of the medium ordered kaolinite was investigated under non-isothermal conditions. Samples of industrially treated (washed) kaolin with high content of kaolinite were calcined using heating rate from 1 to 40 °C min −1. The results of thermogravimetric analysis (TGA) were supplemented by differential thermal analysis (DTA), infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) results. The mechanism and pertinent kinetic parameters, i.e. overall activation energy ( E A) and pre-exponential (frequency) factor ( A), were evaluated from the series of thermogravimetric experiments. The obtained results show that dehydroxylation of kaolinite is controlled by the rate of third-order reaction (F 3) under applied condition. The median values of E A and A correspond to 227 ± 1 kJ mol −1 and (9.4 ± 0.3) × 10 9 s −1, respectively.