Pyrolysis characteristics and kinetic analysis of Indian almond fruit biomass by thermogravimetric analysis for the potential source of bioenergy

Pyrolysis has recently emerged as a viable and sustainable approach for assessing the bioenergy potential of agricultural waste. Indian almond fruit (IAF) has the potential for bioenergy recovery for heat and electricity generation, whereas, the characterization and the kinetics data of IAF have never been explored. In this research, the IAF biomass was involved in proximate, ultimate and chemical analysis for the complete characterization of biomass. Further, the pyrolysis behaviour and kinetic analysis of IAF were investigated by thermogravimetric analysis (TGA) technique using five heating rates such as 5°C/min, 10°C/min, 15°C/min, 20°C/min and 25°C/min, respectively. Kinetic analysis was performed on the IAF biomass using different kinetic models such as Kissinger, Friedman, Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). Furthermore, thermodynamic parameters were determined using the decomposition data obtained from the TGA curve. A characterization study revealed that the IAF biomass displayed a heating value of 18.31 MJ/kg. The carbon and hydrogen contents were noted as 50.72% and 4.98%, respectively, and no traces of sulphur were observed. The IAF biomass exhibited the maximum lignin content of 21.14%. TGA results revealed that the IAF biomass decomposed in three stages, stage 1: 35°C to 110°C, stage 2: 110 °C to 240°C and stage 3: 240°C to 400°C. Higher mass loss was seen in stage 3 due to the simultaneous degradation of cellulose, hemicelluloses and lignin. Activation energy calculated by Kissinger, Friedman, KAS and FWO exhibited as 12.23 and 9.15 kJ/mol – 19.09 and 26.10 kJ/mol – 132.57 and 32.60 kJ/mol – 142.33 kJ/mol, respectively. Furthermore, thermodynamic analysis of IAF biomass displayed that the pyrolysis process was a spontaneous and endothermic process. In addition, the pyrolysis characterization of various biomass investigated by the previous researchers has been compared with the present results.