EVALUATION OF DIESEL ENGINE PERFORMANCE AND EMISSIONS USING BIODIESEL FROM NEEM OIL SYNTHESIZED WITH CALCIUM OXIDE CATALYST DERIVED FROM WASTE BONES

Abstract

The present study investigates the synthesis of neem oil methyl ester (NOME) biodiesel using a heterogeneous calcium oxide (CaO) catalyst derived from waste animal bones. Waste bones were calcined at 900°C to produce an active, low-cost, and environmentally benign catalyst. Transesterification optimization was performed using response surface methodology (RSM) with a central composite design (CCD), considering five key process variables: catalyst concentration, methanol-to-oil molar ratio, temperature, reaction time, and agitation speed. The quadratic model demonstrated excellent fit (R² = 0.9967) and predicted a maximum yield of approximately 93% under optimized conditions. The produced NOME satisfied ASTM D6751 and EN 14214 quality standards, exhibiting favorable density, viscosity, flash point, acid value, and cetane number. Engine performance and emission tests on a single-cylinder diesel engine revealed that higher biodiesel blends reduced brake thermal efficiency and increased brake-specific fuel consumption compared to neat diesel, while significantly lowering carbon monoxide (CO) and hydrocarbon (HC) emissions. Nitrogen oxides (NOx) emissions increased with biodiesel content and engine load. The utilization of bone-derived CaO integrates waste valorization with renewable fuel production, offering a sustainable pathway for biodiesel synthesis with improved environmental performance.