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

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.