COMBUSTION PERFORMANCE OF PALM KERNEL SHELL BIOCHAR BRIQUETTE MODIFIED WITH ACID-LEACHED NEEM LEAF ASH

Abstract

Wood fuel contributes significantly to air pollution and deforestation. Agro-waste briquetting as solid fuel has emerged to reduce the burden on forest resources, but its adoption is hindered by poor combustion performance and high pollutant emissions. This study developed biomass briquettes from Palm Kernel Shell (PKS) biochar modified with Acid-Leached Neem Leaf Ash (ALNLA) and rendered beef tallow. This is to target improved combustion efficiency and reduced harmful emissions, for household cookstove applications. Neem leaves were calcined at 750°C and then leached with 2M HCl at 45°C for 2 hours, thereby achieving a leachability percentage of 91.24% and producing a silica-enriched residue (SiO₂ = 57.86 wt%; Fe₂O₃ = 8.20 wt%; CaO = 7.52 wt%). PKS biochar was produced by slow pyrolysis at 550°C. Six briquette formulations (B1–B6) were prepared and characterized using XRF, FT-IR, XRD, TGA, and proximate analysis. Water boiling test (WBT), and measurement of burn duration, combustion temperature and some Toxic Air Pollutants (TAP) (CO, SO₂, NO₂ and particulate matter) emission, heating value and fixed carbon, were carried out. All formulations outperformed commercial charcoal in burn duration by factors of 1.97 – 4.02%. Formulation B6 (90% biochar, 1.0% ALNLA, 10% starch) achieved the longest burn duration (378 minutes), highest combustion temperature (1109°C), and lowest stabilized TAP emissions. Formulation B5 recorded the highest estimated higher heating value (5.78 MJ/kg) and fixed carbon (15.59%). These results demonstrate the viability of acid-leached neem leaf ash as a low-cost, waste-derived modifier for producing cleaner-burning briquettes suited to Sub-Saharan African household energy needs.