Effect of ethanol additive on bio-mix biodiesels from a raw mixture of various feedstocks

This study presents a simple oil dilution method, known as the bio-mix approach, to enhance the saturated fatty acid levels of non-edible oils by mixing them with highly saturated edible oils. Five raw bio-mix test samples were produced from a blend of unsaturated raw tamarind oil and saturated raw waste cooking oil at different compositions. Among these five samples, raw bio-mix oil with 30% tamarind and 70% waste cooking oil and raw bio-mix oil with 20% tamarind and 80% waste cooking oil were identified as optimum blends based on their lower values of free fatty acids (FFAs). These raw bio-mix oils were then transesterified into bio-mix biodiesel samples using KOH as a catalyst in a transesterification reaction method. A systematic method was employed to enhance the quality and properties of the optimal bio-mix test samples by using ethanol as an additive. The composition of fatty acids and properties of additive blended bio-mix fuels, including viscosity, density, flash point, iodine value, oxidation stability, cetane number, and heating values, were analyzed and compared with the optimal bio-mix samples. The results indicated that 10% of ethanol blended optimum bio-mix fuels had higher levels of saturated fatty acid as well as oxidation stability. However, the flash point, viscosity, unsaturated fatty acids, and higher heating value were decreased when compared to the optimum bio-mix samples. The properties of ethanol blended bio-mix biodiesels were found within the standard limit values specified by the Bureau of Indian Standards and European norms and standards. Graphical abstract