LEAF EXTRACTS

The global shift toward sustainable energy has intensified interest in biodiesel as an environmentally friendly alternative to fossil fuels. This study investigates the production of biodiesel from waste cooking oil (WCO) using calcined heterogeneous catalysts derived from waste materials, including pumpkin pods and turkey bones, and its subsequent preservation using natural extracts from Azadirachta indica (neem) and Ocimum gratissimum (African basil). Transesterification was carried out in a pilot-scale reactor at 60 °C for 75 minutes. Characterization of the WCO prior to transesterification showed an acid value of 2.41 mg KOH/g and a free fatty acid (FFA) content of 1.21%, indicating moderate degradation from repeated frying. Post-treatment analysis revealed a slight increase in acid value to 3.07 mg KOH/g, while other parameters, including saponification value (251.83 mg KOH/g), density (0.8948 g/cm³), and viscosity (9.50 mPa·s), remained within acceptable ranges for biodiesel feedstock. The produced biodiesel met key ASTM D6751 specifications, with a density of 0.87 g/cm³, acid value of 0.34 mg KOH/g, viscosity of 4.62 mm²/s, and a flash point of 220 °C, confirming its suitability for use as a fuel or in blends. GC-MS analysis revealed a fatty acid methyl ester (FAME) composition dominated by methyl oleate (48.68%) and methyl palmitate (37.48%). FTIR spectroscopy further confirmed successful transesterification through the presence of a characteristic ester carbonyl absorption peak at 1742.81 cm⁻¹. Stability studies conducted over six weeks showed that the combined treatment of neem and basil extracts (30 ml) resulted in the lowest final acid value of 0.78 mg KOH/g, indicating improved oxidative stability. This study demonstrates that waste cooking oil is a viable and cost-effective feedstock for biodiesel production. Furthermore, the use of locally sourced plant extracts as natural stabilizers offers a sustainable and biodegradable approach to enhancing biodiesel storage stability, supporting the advancement of renewable energy technologies in Nigeria.