Quality assessment of biodiesel produced from Caesalpinia pulcherrima (Pride of Barbados)

Abstract

Alternative energy sources from vegetable products are developing as a response to the depleting fossil fuel reserves and the environmental damage caused by their burning. Among these different possible resources, biodiesel has received a lot of interest as a diesel engine fuel substitute because it is renewable, non-toxic, eco-friendly, etc. This study evaluated the quality assessment of production of biodiesel from Caesalpinia pulcherrima. The sample oil was extracted from the seeds of Caesalpinia pulcherrima using a soxhlet extractor with n-hexane; the results obtained showed low yield of 27 ± 0.1 % for the extracted oil. The physicochemical properties of the oils sample were found to be as follows: Saponification value: 142.87 mgKOH/g, peroxide value: 7.70 mEq O2/kg, acid value : 30.49 mg KOH/g, iodine value (IV): 23.15 g I2/100g, viscosity: 5.83 mm2 /sec, specific gravity: 0.90. The value of free fatty acid gotten was 15.43. The oil was transesterified using two-step transesterification due to their high free fatty acid (FFA) using sodium hydroxide as catalyst. The biodiesel produced was analyzed for its fatty acid profile using GC-MS and fuel properties using ASTM Methods. The Caesalpinia pulcherrima oil obtained for use in the production of biodiesel was clear, viscous, and yellowish in color. The result of the transesterification reaction was a transparent yellowish color liquid (biofuel) and the percentage yield was 71.73 %. The density of 0.86, pour point of -5.03 oC, cloud point of 5.83 oC, the specific gravity of 0.895, the kinematic viscosity of 5.37 mm2 /s, and an acid value of 1.1 MgKOH/g were all within the ASTM D6751 specification for biodiesel fuel. respectively. Results obtained infer that oil from Caesalpinia pulcherrima possesses properties that are suitable for biofuel production using ASTM standard.