Pyrolysis of castor seed shells: Kinetic and thermodynamic study using thermogravimetric analysis (TGA)

Abstract

The present work focused on the kinetics and thermodynamics of unexplored and unutilised material (Castor Seed Shells) at Slow and Intermediate Pyrolytic conditions. Thermogravimetric experiments were performed at two heating rate ranges i.e., at lower range (2.5–10 °C/min) and higher range (50–80 °C/min). The maximum devolatization observed below 500 °C, with the maximum weight loss ranging between 62 and 65 %. The average activation energy was determined to be 219.14, 217.42, 217.78, and 251.42 kJ/mol for the lower heating rate range, and 169.89, 171.27, 168.95, and 242.66 kJ/mol for the higher heating rate range, using Isoconversional methods including Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, Starink, and Friedman. Reaction mechanism along with thermodynamic parameters was also estimated. The CSS pyrolysis follows diffusional and nucleation reaction mechanism model and does not show significant change with the mode of pyrolysis.