Evaluation of diesel engine performance and emissions using biodiesel from waste oils synthesized with Fe₃O₄-SiO₂...

Biodiesel is a non-toxic, renewable, and environmentally friendly fuel used in compression ignition engines. This work aimed to develop Fe₃O₄/SiO₂ as a cheap, magnetic, and easy separable catalyst for biodiesel production from waste oil by sono-catalytic transesterification.

Fe₃O₄-SiO₂ was prepared using a modified Stober method and used as a heterogeneous catalyst in an ultrasound-assisted transesterification reaction to produce biodiesel. The tests were designed by the Response surface methodology by considering the molar ratio of methanol to oil (M/O), catalyst weight percentage, and sonication time as independent factors. The produced biodiesel in diesel generator engines and the emission of pollutants were evaluated.

The optimal production conditions were determined using the response surface methodology, which included a molar ratio of 8.30, a catalyst weight percentage of 5.30, and a sonication time of 30.02 min. The Pareto analysis indicated that the sonication time is the most important factor in the sono-catalytic transesterification of waste oil. The evaluation of the produced fuel showed that with an increase in the percentage of biodiesel in the engine's fuel input, CO emissions decreased by 0.027 % and smoke levels by 24 %, while NOx levels increased by 495 ppm. Additionally, the increase in biodiesel percentage led to a rise in brake-specific power by 44.6 kW and brake-specific fuel consumption by 89 g/kWh though brake torque decreased by 87 Nm.

The study introduces significant advancements in biodiesel production technology through combining heterogeneous catalysis and ultrasound processing, optimizing production parameters for efficiency and sustainability while demonstrating improved environmental performance in diesel engines.