Biodiesel production from selected seed oils: Characterization, effect of process variables on biodiesel yield and engine performance testing

This study investigates the production of biodiesels from Cyperus esculentus ( C. esculentus ), Sesamum indicum ( S. indicum ), and Colocynthus vulgaris ( C. vulgaris ) seed oils through sulfuric acid-catalyzed transesterification. The fuel properties and engine performance of these biodiesels and their blends with hydrocarbon-based diesel (B10–B100) were analyzed. The transesterification process showed conversion efficiencies exceeding 80% for C. vulgaris and S. indicum biodiesels. The viscosity, flash point, and pour point of the biodiesel blends were evaluated and the result demonstrated compliance with American Society for Testing and Materials (ASTM) standards. Notably, the B60 blends of all biodiesels show significantly reduced acidic emissions, with C. vulgaris biodiesel recording the lowest value of 0.0015 g/dm³. The fatty acid profile analysis revealed that C. vulgaris biodiesel, with its higher polyunsaturated fatty acids, exhibits better cold flow properties but reduced oxidative stability. Similarly, the S. indicum biodiesel had enhanced oxidative stability due to a higher percentage of saturated fatty acids. Furthermore, all the biodiesel blends showed improved engine performance, with a noticeable reduction in greenhouse gas emissions. This makes them viable alternatives to conventional diesel fuels and the blending these biodiesels with hydrocarbon diesel could further improve fuel efficiency and emissions.