Sustainable briquette production from jujube seed shells: Process optimization using response surface methodology

Abstract

This study explores the optimization of binder-free briquette production from jujube seed shells, an underutilized biomass resource in Nigeria, using Response Surface Methodology (RSM). The influence of key process variables—particle size, pre-heat temperature, and compaction pressure—on the mechanical and thermal properties of the briquettes was assessed. RSM results indicated that fine particle sizes (<0.6 mm), combined with pre-heat temperatures between 65 and 75°C and compaction pressures up to 100 MPa, yielded briquettes with optimal characteristics: a maximum density of 2108 kg/m³, compressive strength of 22.81 MPa, and a shatter index exceeding 98%. The briquettes showed excellent durability, with minimal relaxed density loss (1.95%) over 56 days. Thermal analysis revealed high energy content, with calorific values ranging from 6317 to 6495 kcal/kg (26.45–27.19 MJ/kg), low ash content (1.51%–1.68%), and significant fixed carbon (17.29%–18.39%). The optimization process underscored the effectiveness of natural lignin as an internal binder, eliminating the need for external binders. These findings offer a sustainable, cost-effective, and eco-friendly alternative to traditional fuels, with promising potential for rural energy solutions in West Africa.