Thermal decomposition kinetics of guarana seed residue through thermogravimetric analysis under inert and oxidizing atmospheres

Abstract

This work aims to analyze the thermal decomposition kinetics of guarana seed residue applying inert and oxidizing atmospheres. Thermal decomposition experiments were carried out in a thermogravimetric analyser using heating rates of 5, 10 and 15 °C/min. Three thermal decomposition stages were identified: dehydration; pyrolysis/oxidative pyrolysis, and carbonization/combustion, respectively. In order to obtain the estimation of the activation energies, the isoconversional method proposed by Vyazovkin (1997) was applied. Besides that, three and six independent parallel reactions schemes were applied for respective atmospheres. The ranges of activation energy were of 52–140 kJ/mol and 71–171 kJ/mol for inert and oxidizing atmosphere, respectively. The modeling of conversion rates presented a good agreement in relation to the experimental data (AD < 4%).