Assessing the pyrolysis potential of redgram stalk: Thermo-kinetic study, empirical modelling and product characterization

Abstract

Pyrolysis characteristics, thermal properties and kinetics of redgram stalk were studied for effective energy generation through pyrolysis process. Thermogravimetric experiments were carried out at five heating rates (10, 20, 30, 40 and 50 °C min−1) and particle sizes (<0.2, 0.2–0.5, 0.5–1, 1–1.5 and 1.5–2 mm). Effect of particle size on functional, morphological and structural characteristics of biochar were studied. The activation energy of redgram stalk was calculated by KAS and FWO methods and was in the range of 132.16–175.76 kJ mol−1 and 113.12–152.53 kJ mol−1. Sestak and Berggren's model revealed that the redgram stalk pyrolysis was dominated by diffusion mechanism. Thermodynamic analysis (ΔG, ΔH, ΔS) indicated the endothermic and non-spontaneous nature of the redgram stalk pyrolysis. Characterization of biochar revealed the well-defined pore structure, progressive stacking of graphene sheets and the formation of aromatic crystallites in smallest particle biochar. The kinetic results and biochar characteristics elucidate the feasibility of redgram stalk for energy and environmental applications.

Keywords

• Redgram stalk
• Pyrolysis
• Thermogravimetric analysis
• Isoconversional methods
• Biochar