Analysis of thermal behavior and pyrolytic characteristics of vetiver grass after phytoremediation through thermogravimetric analysis

In this work, pyrolysis experiments of vetiver grass (Vetiveria zizanioides) after phytoremediation of arsenic, fluoride and manganese were carried out in a thermogravimetric analyzer under inert atmosphere at three heating rates of 5, 10 and 20 °C min⁻¹ in order to investigate the thermal degradation behavior of vetiver grass. The physicochemical properties of vetiver grass were investigated by proximate and ultimate analysis, lignocellulosic composition, Bomb calorimetry and FTIR spectroscopy. The results showed that vetiver grass has high volatile matter content and high calorific value. Kinetic parameters for pyrolysis of vetiver grass were evaluated using three different kinetic models suggested by Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW) and Coasts–Redfern using TGA data. The average activation energy values of vetiver grass calculated by using KAS and OFW models are found as 151.23 and 161.33 kJ mol⁻¹, respectively. Coasts-Redfern model has been used to compute the pre-exponential factor. The physicochemical properties and kinetic parameters verify the suitability of vetiver grass as a potential feedstock for pyrolysis.