Pyrolysis characteristics and kinetic investigation of waste groundnut shells using thermogravimetric analyzer, Py-FTIR, and Py-GC-MS

The objective of the present study was to investigate the bioenergy and resource recovery potential of groundnut shells (GNS) through pyrolysis. The release of vapours at short time scales and their composition were investigated using analytical pyrolysis coupled with Fourier transform infrared (FTIR) spectroscopy and gas chromatography/mass spectrometry (GC/MS). The thermal decomposition behaviour and kinetic evaluation were carried out using a thermogravimetric analyzer (TGA). Five iso-conversional models and master plots method were utilized to explore the kinetic parameters and reaction mechanism at dynamic heating rates (10, 20, and 30 °C min⁻¹). X-ray fluorescence spectroscopy (XRF) was employed to detect the ash composition, which is essential to evaluate the slagging and fouling potential of the biomass when used for bioenergy. TG data revealed three distinct stages of decomposition, while an immense amount of biomass disruption was observed at a higher heating rate (30 °C min⁻¹). Further, the average apparent activation energy of pyrolysis determined using KAS, ST, DAEM, and VZ were 223.26, 214.57, 207.97, and 117.24 kJ mol⁻¹, respectively. The extreme emission of carbon dioxide and carbonyl compounds was discovered through Py-FTIR. The increased formation of hydrocarbons (14.22–34.26%), alcohols (1.41–9.43%), and reduction in phenols (19.13–18.67%) at different temperatures (450, 550, and 650 °C) were validated by Py-GC-MS. Overall, the findings demonstrate that GNS is a promising feedstock for pyrolysis to produce valuable fuel molecules and chemicals.