Papaya leaf extract-mediated synthesis and characterization of magnetite nanoparticles with application in diesel engine performance analysis

This study presents the green synthesis of magnetite (Fe3O4) nanoparticles using papaya (Carica papaya) leaf extract as an eco-friendly reducing and stabilizing agent. Ferric chloride hexahydrate (FeCl3+6 H2O) and ferrous sulfate heptahydrate (FeSO4+7 H2O) were reacted in a 2:1 molar ratio with the plant extract under controlled conditions. The resulting brown-colored precipitate was thoroughly dried, collected, and stored for characterization. FESEM analysis revealed agglomerated nanoparticles with an average size of ~ 280 nm, while EDX confirmed the presence of iron (72.52%) and oxygen (15.92%), validating Fe3O4 formation. For practical application, the synthesized nanoparticles were dispersed at 50 ppm in an M20 biodiesel blend (20% mahua biodiesel, 80% diesel) and tested in a single-cylinder, four-stroke diesel engine under varying loads. The nanoparticle-enriched blend demonstrated a 1.93% increase in Brake Thermal Efficiency (BTE) and a 1.18% decrease in Specific Fuel Consumption (SFC), alongside reductions in NOx (5.25%), HC (6.02%), CO (16.13%), and smoke opacity (23.26%). These findings highlight the dual advantages of green-synthesized Fe3O4 nanoparticles in improving combustion efficiency while mitigating harmful emissions, supporting sustainable diesel engine operation.