Efficient biodiesel production from recycled cooking oil using a NaOH/CoFe2O4 magnetic nano-catalyst: synthesis, characterization, and process enhancement for sustainability

[Display omitted] •Successful synthesis of ZnO nanoparticles by the solvothermal method.•Fruitful grafting reaction and the presence of coupling agents on ZnO NPs.•DFT calculations provided compelling evidence of strong OCA/ZnO-NPs interactions.•Potential applications of modified ZnO-NPs in polymer-based bionanocomposites. This research introduces an environmentally sustainable approach to biodiesel production, utilizing waste cooking oil (WCO) as a renewable feedstock. The focal point of this study is the synthesis and characterization of NaOH/CoFe2O4 magnetic nanoparticles, employed as an efficient catalyst for the transesterification reaction between WCO and methanol. Comprehensive analysis, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, magnetometry, temperature-programmed carbon dioxide and ammonia desorption, and X-ray photoelectron spectroscopy reveals nanoparticles with remarkable catalytic properties. The transesterification process catalyzed by NaOH/CoFe2O4 yields biodiesel at an impressive rate of 98.71%, complying with ASTM standards. Kinetic and thermodynamic evaluations elucidate reaction mechanisms, and density functional theory (DFT) calculations provide insights into the catalytic process. The magnetic catalyst's reusability enhances sustainability, making it a promising solution for large-scale biodiesel production, and lays the foundation for future catalyst optimization.