Thermal, kinetic and thermodynamic study for co-pyrolysis of pine needles and styrofoam using thermogravimetric analysis

Abstract

This study investigate the thermal decomposition behavior of pine needles (PN), styrofoam (SF) as well as their mixture at ratio of 1:1 (w/w), determine the kinetic and thermodynamic parameters for co-pyrolysis of PN and SF using thermogravimetric analysis (TGA) data. The co-pyrolysis experiments were performed in an inert environment (N2) at three variable heating rates of 5, 10 and 20 °C/min in TG analyzer from 35 to 850 °C. TGA outcomes represent that the thermal degradation of PN occurred in three stages, while SF degradation took place in a single stage and degradation of their mixture occurred in three stages. Model-free methods such as Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) were employed to findout the activation energy (Ea) for co-pyrolysis of PN and SF. Moreover, the thermodynamic parameters (changes in enthalpy, Gibbs free energy and entropy) were also determined by OFW method. The pre-exponential factors were also evaluated by model-fitting (Coats-Redfern) method. The average of Ea for co-pyrolysis of PN and SF determined by KAS and OFW methods was 96.44 and 109.73 kJ/mol, respectively. The results of this study suggest that PN and SF mixture has potential to be used as a pyrolysis feedstocks.