COMPARATIVE ANALYSIS OF THE OPTIMIZATION OF BIODISEL PRRODUCTION FROM NEEM OIL AND SHEA NUT OIL BY SUPERCRITICAL TRANSESTERIFICATION
Abstract
This study investigated the optimization and comparative analysis of biodiesel production from neem oil (Azadirachta indica) and shea nut oil (Vitellaria paradoxa) using supercritical transesterification. Both oils were characterized for physicochemical properties, with neem oil showing higher (9.66% FFA) compared to shea nut oil (4.675% FFA). A Box-Behnken Design under Response Surface Methodology was employed to optimize three critical process parameters: reaction temperature (100-320°C), methanol-to-oil molar ratio (10:1-50:1), and reaction time (10-30 minutes). The optimization yielded maximum biodiesel of 99.28% for shea nut oil at optimal conditions of 210°C, 30:1 molar ratio, and 20 minutes’ reaction time. These optimized conditions of above process parameters were successfully utilised in the production of biodiesel from neem oil, achieving 99.31% yield. ANOVA analysis revealed the quadratic model was highly significant (F-value = 76.00, p < 0. 0001) with excellent fit statistics (R² = 0.9899, Adjusted R² = 0.9768). Gas Chromatography -Mass Spectrometry (GC-MS) analysis confirmed successful transesterification, with shea biodiesel dominated by methyl dodecanoate (30.47%), methyl oleate (19.76%), and methyl stearate (19.70%), while Neem biodiesel was primarily composed of methyl linoleate (48.73%) and methyl palmitate (19.99%). It was found that Both biodiesels met most ASTM D6751 specifications, and comparable to the standard for automobile petroleum diesel though neem biodiesel required additional purification to reduce acid value (2.218 mg KOH/g) and flash point enhancement.. The supercritical pprocess demonstrated superior tolerance to high FFA feedstocks, eliminated catalyst-related complications, and achieved rapid conversion rates.
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