Study on Combustion Characteristics and Thermodynamic Parameters of Thermal Degradation of Guinea Grass (Megathyrsus maximus) in N2-Pyrolytic and Oxidative Atmospheres

Abstract

This study provides an extensive investigation on the kinetics, combustion characteristics, and thermodynamic parameters of the thermal degradation of guinea grass (Megathyrsus maximus) in N2-pyrolytic and oxidative atmospheres. A model-fitting technique and three different iso-conversional techniques were used to investigate the kinetics of the thermal process, after which an analysis of the combustion characteristics and thermodynamic parameters was undertaken. Prior to this, experiments on the physico-chemical characterization, thermogravimetric, and spectroscopic analyses were carried out to provide insight into the compositional structure of the guinea grass. The volatile matter, fixed carbon, and total lignin contents by mass were 73.0%, 16.1%, and 21.5%, respectively, while the higher heating value was 15.46 MJ/kg. The cellulose crystallinity index, determined by XRD, was 0.43. The conversion of the GG in air proceeded at a relatively much higher rate as the maximum mass-loss rate peak in a 20 K/min read was −23.1 and −12.3%/min for the oxidative and the pyrolytic, respectively. The kinetics investigation revealed three distinctive stages of decomposition with their corresponding values of activation energy. The average values of activation energy (FWO) at the latter stages of decomposition in the pyrolytic processes (165 kJ/mol) were higher than those in the oxidative processes (125 kJ/mol)—an indication of the distinctive phenomenon at this stage of the reaction. The Coats–Redfern kinetic model revealed that chemical reactions and diffusional models played a predominant role in the thermal decomposition process of the GG. This study showed that the thermodynamic parameters varied with the conversion ratio, and the combustion performance increased with the heating rates. The use of GG as an energy feedstock is recommended based on the findings from this work.

Guinea Grass (Megathyrsus maximus) Fibres as Sorbent in Diesel Bioremediation

“…Meanwhile, the aromatic ring of lignin's stretching (C=C) exhibited a peak wavelength of 1400-1600 cm −1 , whereas untreated GG after sorption had a greater reflectance than untreated GG before sorption [33]. The peak in the fingerprint region, 1200-900 cm −1 range corresponded to the C-O deformation band caused by the ether group, which can be found in hemicellulose, cellulose, or lignin [34].…”

Physicochemical Characterization of Woody Lignocellulosic Biomass and Charcoal for Bio-energy Heat Generation

“…The biomass (~ 4 g) was Soxhlet extracted with dichloromethane (CH 2 Cl 2 ) for 16 h, in duplicate, and the extractives content determined gravimetrically after concentrating to dryness according to ASTM D1108-96. The Klason and acid soluble lignin were determined on extractived raw biomass (200 mg, in duplicate) according to ASTM D1106 and TAPPI technique T-222, respectively 11 . The lignin concentration was measured by a two-step acid hydrolysis (72%, 2 mL for 60 min at 30 °C, diluted to 4% H 2 SO 4 , and autoclaved for 30 min at 120 °C) and the yield was gravimetrically measured after oven drying.…”