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Recovery of clean energy precursors from Bambara groundnut waste via pyrolysis: Kinetics, products distribution and optimisation using response surface methodology

Mohammed, Isah Yakub, Abakr, Yousif Abdalla, Xing Hui, Jershen Nga, Alaba, Peter Adeniyi, Morris, Kenobi Isima, Ibrahim, Mustapha Danladi
Journal of cleaner production 2017 v.164 pp. 1430-1445
Vigna subterranea, activation energy, biochar, biocompatible materials, biofuels, clean energy, energy, food crops, kinetics, models, nitrogen, peanut hulls, pyrolysis, response surface methodology, temperature, wastes
This study presents first comprehensive thermochemical analysis of Bambara groundnut shell. Pyrolysis characteristics was examined under non-isothermal degradation in nitrogen atmosphere at different heating rates (10, 15 and 20 °C/min) using single-step global model kinetic model. The single-step global model average apparent activation energy was found to be 142.64 ± 5.7 kJ/mol. Pyrolysis was conducted in a fixed bed reactor. Effects of pyrolysis temperature (450–750 °C), heating rate (20–50 °C/min) and nitrogen flow rate (5–25 L/min) were investigated collectively. The process variables were optimized using response surface methodology with central composite design. Optimum bio-oil yield of 36.49 wt% was recorded at 600 °C, 50 °C/min and 11 L/min. The bio-oil, bio-char and non-condensable gas collected were comprehensively characterised. Energy analysis of the products was also evaluated. This study revealed that Bambara groundnut shell, a residue from food crop, is a potential source of energy precursors for development of a sustainable bioenergy system and biomaterials.