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 (Fe 3 O 4 ) nanoparticles using papaya (Carica papaya) leaf extract as an eco-friendly reducing and stabilizing agent. Ferric chloride hexahydrate (FeCl 3 +6 H 2 O) and ferrous sulfate heptahydrate (FeSO 4 +7 H 2 O) 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 Fe 3 O 4 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 Fe 3 O 4 nanoparticles in improving combustion efficiency while mitigating harmful emissions, supporting sustainable diesel engine operation.