Nickel oxide (NiO) nanoparticles were synthesized via a solution growth method and evaluated as heterogeneous catalysts for biodiesel production from waste cooking oil. Characterization using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy confirmed the crystalline cubic phase, functional stability, and well-defined morphology of the NiO nanoparticles, making them suitable for catalytic applications. The produced biodiesel achieved a high yield of 96.7% and was blended with diesel to form DWB20 (20% biodiesel + 80% diesel), which was tested in a single-cylinder, 5.2 kW Kirloskar CI engine. Engine performance, combustion behavior, and emission parameters were systematically assessed. The DWB20 blend showed only a marginal 3.2% reduction in brake thermal efficiency compared to diesel. Hydrogen addition further enhanced combustion, increasing efficiency by 8.4% and reducing emissions, except for NO, which was effectively mitigated through the incorporation of the antioxidant A-tocopherol acetate. Overall, this study demonstrates that NiO nanocatalysts enable high-yield biodiesel production and that the combined use of hydrogen and antioxidants improves engine performance and emission characteristics, supporting the development of cleaner and more sustainable fuel systems.
Balaji et al. (Thu,) studied this question.