Catalytic Performance and Emission Profiling of <i>Sterculia foetida</i> Biodiesel Enhanced with CaO Nanoparticles: A Nanoengineering Approach to Sustainable Fueling

The increasing demand for clean and renewable energy sources has expedited the advancement of biodiesel as a sustainable alternative to fossil fuels. This research examines the production and performance of biodiesel derived from Sterculia foetida oil, a nonedible feedstock and catalyzed by means of Calcium Oxide (CaO) nanoparticles. The biodiesel was synthesized through transesterification under optimized conditions (65[Formula: see text]C, 3[Formula: see text]wt.% CaO catalyst and a methanol-to-oil molar ratio of 9:1), achieving a conversion efficiency of 96%. Characterization confirmed exceptional fuel properties, including a cetane number of 55, a viscosity of 4.2[Formula: see text]mm 2 /s and a sulfur content below 0.02%, adhering to ASTM D6751 and EN 14214 standards. Performance evaluation was executed utilizing a single-cylinder diesel engine. The results indicated that nano-enhanced biodiesel augmented Brake Thermal Efficiency (BTE) by 4% and diminished Specific Fuel Consumption (SFC) by 6% in comparison to standard biodiesel. Emission analysis revealed substantial reductions in Carbon Monoxide (CO) by 28%, unburned Hydrocarbons (HC) by 32% and Particulate Matter (PM) by 20%, relative to conventional diesel. A minor increase in Nitrogen Oxides (NO x ) emissions (6%) was ascribed to elevated combustion temperatures. Combustion analysis illustrated improved in-cylinder pressure (80[Formula: see text]bar) and heat release rate (HRR: 26[Formula: see text]J/[Formula: see text]CA) for nanocatalyzed biodiesel, in contrast to diesel (70[Formula: see text]bar; 20[Formula: see text]J/[Formula: see text]CA). These findings substantiate the viability of Sterculia foetida biodiesel enhanced with CaO nanoparticles as a high-efficiency, low-emission biofuel, providing a scalable pathway for cleaner engine technologies and sustainable energy systems.