Abstract:
Composite briquettes from agricultural residues are a potential sustainable domestic solid fuel resource. This study aimed
to develop and characterize composite briquettes developed from cassava rhizomes and groundnut stalks with jackfruit
waste binder as an alternative sustainable fuel for domestic cooking applications. Cassava rhizomes and groundnuts
stalks feedstock were carbonized in a step-down kiln under slow pyrolysis conditions at temperatures between 400
and 500 ℃. Thermogravimetric analysis was used to determine the proximate and thermal properties of the developed
composite briquettes. Bomb calorimetry was used to determine their heating values. Relaxed density, drop strength and
compressive strength results were used to determine the mechanical properties of the developed briquettes. Design
of Experiments (Box Behnken design) was used to evaluate the efect of factors (biochar amount, jackfruit waste binder
amount, and amount of water) on the mechanical and thermal properties of the developed composite briquettes. The
Coats-Redfern kinetic model was used to determine the activation energy for the developed briquettes. Calorifc values and drop strength of developed composite briquettes ranged from 18.1 to 24.0 MJ/kg and 92–99%, respectively.
Combustion performance results indicated that ignition temperature increased from 155.1 to 184 ◦C, when heating rate
was increased from 10 to 15 ◦C/min. However, burnout temperature decreased from 618.1 to 453 ◦C/min with a similar
corresponding increase in heating rate. Optimum biochar amount, amount of water, and jackfruit waste binder amount
for optimal mechanical and thermal properties were 89.3%, 893.0 ml, and 29.5 g, respectively. Composite briquettes
developed from cassava rhizomes and groundnut stalks with jackfruit waste as binder are suitable potential domestic
cooking fuels.
