Thermal behavior and pyrolysis kinetics of olive stone residue

In the last decades, one of the most ordinary challenges that countries of Southern Europe face is the management of wastes and by-products of olive oil production activities which are disposed into the environment and contribute to the enhancement of major ecological issues due to their organic loads. Exploitation of these olive residues wastes by thermochemical treatment has been proved a very popular way to generate a wide range of valuable products. In this concept, this work studies the thermal decomposition process of olive stone samples using thermogravimetric analysis (TGA) data obtained under inert atmosphere at various heating rates (5-20 degrees C) and their kinetic analysis conducted via model-free and model fitting methods. The changes in the crystal structure for various pyrolysis temperatures of the sample were examined by X-ray diffraction analysis (XRD), while the morphological characteristics were examined by scanning electron microscopy (SEM). Results indicated that the thermal behavior of olive stone sample was a typical one for a lignocellulosic material with the first mass loss being attributed to moisture removal while the following stages were assigned to lignocellulosic degradation substances. Vyazovkin (VYA) isoconversional method was performed to estimate effective activation energy (E-a) and the pre-exponential factor, while using a model fitting method the best fitting results were obtained by a three independent parallel reactions model, obeying the nth order with Fn code and described by the f(alpha) = (1 - alpha)(n) equation.

Automated summary

This study investigates the thermal decomposition process of olive stone samples through thermogravimetric analysis (TGA) and analyzes the changes in crystal structure and morphology at different pyrolysis temperatures. The results demonstrate that the thermal behavior of the olive stone samples is consistent with that of lignocellulosic materials.