Thermal degradation of Tunisian olive stones using thermogravimetric analysis (TGA)
The aim of this paper is to study of the thermal degradation of Tunisian olive stones by non isothermal thermogravimetric analysis (TGA) device, under nitrogen atmosphere. Thermogravimetric analysis of different particles sizes (0.63 2.5mm) was evaluated. The effect of heating rates has been performed. Results showed that particles sizes don't have any effect on the pyrolysis of olive stones whereas the decomposition process is shifted to higher temperature zone with heating rate increasing. Three different kinetic models, the iso conversional; kissinger Akahira Sunose, Ozawa Flynn Wall methods and Coats Redfern model were applied on TGA data of olive stones (OS) to calculate the kinetic parameters including activation energy, pre exponential factor and reaction order. Simulation of olive stones pyrolysis using data obtained from TGA analysis showed good agreement with experimental data for all models. The dependence of the apparent activation energy determined using kissinger Akahira Sunose (KAS) and Ozawa Flynn Wall (OFW) methods, on the conversion degree reveals that pyrolysis progress rather through multi steps kinetics.