Biopolymeric transitions under pyrolytic thermal degradation of Pigeon pea stalk

Abstract

In this article, thermogravimetric analysis (TGA) is used to explore biopolymeric transitions in Pigeon pea stalks (PPS) at various heating rates (10, 20, 30 and 40 °C/min). The appeared transitions of TG-signals were analyzed in depth and discussed critically in terms of biopolymeric changes occurring within the major bioconstituents of PPS due to the influence of different heating rates. The intersection points of the deconvoluted conversion rate spectrum were taken as the stage transition points from one biopolymeric region to another. The stage transition points for hemicellulose to cellulose were at 328 °C and from cellulose to lignin at 356 °C, respectively, at a heating rate of 10 °C/min. This article is presenting the stage transition points first time and highlights the procedure of obtaining them using the conversion rate spectrum. The kinetics of individual bioconstituents of the PPS was also thoroughly investigated. The average activation energy was highest for hemicellulose 283–287 kJ/mol, followed by cellulose (134–137 kJ/mol) and lignin (30–41 kJ/mol). The pyrolysis of PPS followed the multistage reaction mechanism (F1 and A4) based on the Z-master plot technique.