Ultrasonic-assisted biodiesel generation from waste chicken fat utilizing a novel and reusable Ce-doped Fe₂O₃ nanocatalyst: Optimization by CCD, kinetics, and nano-additive on emissions and performance of a diesel engine

The present study aimed at the fabrication of an efficient nanocatalyst utilizing cerium doped on hematite (Ce-doped Fe₂O₃) as a highly reactive catalyst in biodiesel generation from waste chicken fat (WCF) under ultrasonication and also as nano-additive to improve diesel engine features. The surface features of Fe₂O₃ and Ce@Fe₂O₃ nanoparticles were investigated utilizing several analyses. The characterization outcomes demonstrated that the Ce element was successfully incorporated into the Fe₂O₃ structure. RSM-assisted experimental design was utilized to optimize effective parameters on biodiesel efficiency. According to the CCD results, the maximum biodiesel yield employing Fe₂O₃ and Ce-doped Fe₂O₃ nanocatalysts was 91.57% and 95.38%, respectively, which were obtained after 30 min of ultrasonic irradiation time. Also, various proportions of petrodiesel and biodiesel as well as adding Ce@Fe₂O₃ nanoparticles to the fuel blend at different torques (20–100%) were tested on diesel engine parameters. The outcomes revealed that adding biodiesel to petrodiesel diminished CO (10.02%) and UHC (6.34%). Further, increasing biodiesel content in the fuel composition enhanced BSFC (8.29%) and EGT (14.17%) parameters and declined BTE (13.37%). Besides, increasing the percentage of torque enhanced EGT and BTE and reduced BSFC. Also, adding Ce@Fe₂O₃ nanoparticles to biodiesel/diesel blends reduced CO, NO_x, and UHC concentrations, and enhanced BTE and BSFC values. Kinetic and thermodynamic analyses reveal that the transesterification reaction is first-order and endothermic. Furthermore, the activation energy for biodiesel generation using Fe₂O₃ and Ce-doped Fe₂O₃ nanocatalysts were attained at 46.61 and 46.58 kJ/mol, respectively, which are considerable amounts. Besides, the reusability investigation showed that Ce-doped Fe₂O₃ nanoparticles have high stability, so that after the 7th cycle, the biodiesel yield was 87.26% (only a 7.5% decrease in efficiency). Generally, owing to unique features including high catalytic performance, considerable reusability, and high biodiesel yield, Ce-doped Fe₂O₃ nanoparticles are highly recommended for industrial applications.