Polymeric Consolidation in Briquetted Biofuel as Compared to Raw Biomaterial: A TG-Vision for Pigeon Pea Stalks

Abstract

The consolidation of different polymeric bioconstituents was clearly observed in briquetted biofuel produced from pigeon pea crop residues. Critical thermogravimetric diagnosis showed that the scattering of tail end segments of thermograms taken at different heating rates was remarkably low in briquetted biofuel as compared to the scattering in raw material. The consolidation of polymeric cellulose and lignin was discussed and explained. Kinetics was evaluated using isoconversional integral Ozawa−Flynn−Wall method. The activation energy profile of briquetted biofuel dominated over the raw pigeon pea stalks showing higher thermal stability, which was evidence, positive toward the consolidation of intrinsic biopolymers due to briquetting process.

Benefits of weakening in thermogravimetric signals of hemicellulose and lignin for producing briquettes from soybean crop residue

“…1 showing the polymeric consolidation in SB. This was the similar finding as obtained by Gangil [5], for briquettes of pigeon pea stalks.…”

“…Gangil / Energy xxx (2015) 1e9 5 enhance in SB which was explained using the activation energy analysis later in this writing. Gangil [4,5,30] stated that in case of stresses, either due to pressure or temperature or both, on the lignocellulosic biomaterials, the lignin in biomaterial first relaxed, then melted during stresses, and finally solidified in final-product (i.e., briquettes in present discussion). This article considered that the solidification of melted lignin was the one of the probable major causes of thermal stability in SB.…”

“…These signals were ascribed to release of methane or hydrogen by them. Gangil [4,5] stated that the region of 700e750 C could be represented by release of methane (700e730 C) and release of hydrogen (near 750 C) due to charring reactions in case of pigeon pea stalk and its briquetted biofuel, respectively. Abdullah et al [41] mentioned that the charring TGsignals might be due to the secondary reactions in lignin degradation.…”

“…During the TG-studies on plastic polymers and on specific biocomponents (like xylan, cellulose and lignin in extracted or separated or refined form), normally R 2 is taken as >0.9 for isoconversional kinetics. In case of biomaterials where one kind of biopolymeric molecules make complex linkages with other kind of molecules, the R 2 was taken as >0.8 considering the complexity in internal molecular networking during thermal degradation of biomaterials [4,5,30]. Activation energies for few apoints were not computed as shown in Table 3.…”

“…There are various methods for determination of kinetics [4,5,21e40] of thermal degradation, like Friedman method, CoatseRedfern method, Kissinger, KissingereAkahiraeSunose (KAS) method, and OzawaeFlynnewall (OFW), etc. The KAS, OFW and CoatseRedfern methods are integral isoconversional methods whereas Friedman is differential method [4,5,26,27,29]. Kissinger method is basically not an isoconversional method.…”