DETERMINATION OF KINETIC PARAMETERS FOR TRANSESTERIFICATION REACTION OF NEEM OIL TO PRODUCE FATTY ACID ETHYL ESTER

The transesterification of neem oil using ethanol to produce Fatty Acid Ethyl Ester (FAEE) was investigated in this study with emphasis on determining the kinetic behavior and understanding the interactions among key process variables. Neem oil, a non-edible and sustainable feedstock, was subjected to ethanolysis under varying temperatures (45–65°C), catalyst concentrations (0.75–1.50 wt% KOH), ethanol-to-oil molar ratios (6:1, 7.5:1, and 9:1), and reaction times (15–90 min). Experimental results showed consistently high biodiesel yields ranging from 90.64% to 99.58%, with maximum yield achieved at 65°C, 1.5 wt% catalyst, and a 7.1 ethanol-to-oil ratio. The produced biodiesel exhibited acceptable physicochemical properties, including viscosity values between 3.55–6.42 mm²/s, densities of 875–888 g/L, and specific gravities of 0.877–0.890, confirming compliance with standard biodiesel quality ranges. ANOVA results indicated that temperature, catalyst loading, and ethanol-to-oil molar ratio did not individually exert statistically significant effects on yield (p > 0.05). However, interaction assessments revealed meaningful trends: the AC interaction (Temperature × Catalyst wt%) showed that catalyst efficiency was highest at lower temperatures (45°C), where reduced soap formation enhanced conversion, whereas higher temperatures weakened catalytic benefit due to ethanol volatility and side reactions. The BC interaction (Catalyst wt% × Ethanol-to-Oil ratio) demonstrated that catalyst effectiveness increased with ethanol availability; higher ethanol ratios favored lower catalyst loadings by improving mass transfer and reducing phase separation challenges. Kinetic interpretation suggests that the reaction generally followed pseudo-first-order behavior due to ethanol excess, though deviations occurred under extreme catalyst or alcohol conditions due to mass-transfer limitations and reversible triglyceride–diglyceride transitions. These findings address several gaps identified in previous literature, including the scarcity of ethanol-based kinetic studies for neem oil, limited mechanistic insight into catalyst–feedstock interactions, and inadequate evaluation of process-variable interactions. Overall, this study confirms neem oil’s viability for high-yield FAEE production and provides critical foundational data for developing comprehensive kinetic models and scaling up ethanol-based biodiesel systems.