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

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 degrees 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 degrees C), heating rate (20-50 degrees 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 degrees C, 50 degrees 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. (C) 2017 Elsevier Ltd. All rights reserved.