Pathway to reduce free fatty acid formation in Calophyllum inophyllum kernel oil: A renewable feedstock for biodiesel production

Abstract

Calophyllum inophyllum kernels is a source of non-edible oil and possessed up to 73% oil content but its oil is usually marked with a high level of up to 30% free fatty acid (FFA), which is an hindrance to the effective conversion of the oil to biodiesel. This study therefore, proffers a pathway to achieve low levels of free fatty acids in the oil extracted from the kernels by adjustment of its drying conditions, leading to easier conversion of the oil to biodiesel. This is expected to enhance the industrial processes for production of biodiesel from Calophyllum inophyllum kernels oil. Oil was extracted from the kernels, which were previously dried under varied conditions, using Soxhlet extraction technique with n-hexane as solvent. The oil extracted was converted to biodiesel through acid esterification and base-catalysed transesterification. The properties of biodiesel that was subsequently produced was assessed using standard methods. Satisfactory results were obtained for important parameters that have been established to play significant roles in the quality of oil and biodiesel, such as FFA content (0.23), Iodine value (77.01 (gI2/100g), cloud point (−1.40 °C), pour point (−6.24 °C), and higher heating value (40.65 MJ/kg) for biodiesel obtained from kernels dried at 75 °C. The variations in the levels of FFA in the oils differ by as much as 69% and more than 10% improvement in the quantity of the biodiesel produced was obtained. The results demonstrated that drying conditions played a significant role in the quantity and properties of both the oil and biodiesel obtainable from the kernels. The resulting biodiesel met the Australian, ASTM and EN standards. The economical prospect of the proposed method would be seen in the higher quantity of viable dry kernels which will increase the volume of biodiesel obtainable and a drop in the cost of resources that would have been required for such chemical processes and time needed for dewaxing and degumming. The adoption of the right drying technique in a large scale industrial process is capable of improving the quantity and the properties of biodiesel that might be produced from the kernel.