Biodiesel Production by Enzymatic Transesterification of Papaya Seed Oil and Rambutan Seed Oil

Biodiesel production from vegetable oil has gained attention as an alternative fuel to minimize the usage of fossil fuels and reduce greenhouse gases pollution. In Malaysia, oils from local fruit seeds of papaya and rambutan are potential feedstock for biodiesel production due to their high lipid contents and easily available. In the present study, papaya and rambutan seed oils were extracted via soxhlet apparatus using n-hexane and the oil yields were in between 34–40%. The extracted oils were subjected to enzymatic transesterification by the immobilized Candida rugosa lipase as a catalyst under room temperature with varies molar ratios of methanol to oil. The highest biodiesel yield for papaya seed oil and rambutan seed oil was found to be 96% and 89% at methanol-to-oil ratios of 6:1 and 8:1, respectively. Results also showed a higher biodiesel yield using lipase immobilized on the magnetic particles as the heterogeneous catalyst compared to the yield obtained using free enzyme as the homogeneous catalyst. The properties of biodiesel such as density, acid value, iodine value and cetane number were analyzed and found to meet the European Standard of Biodiesel. The study shows that papaya and rambutan seed oils have the potential to be used as alternative feedstock for biodiesel production than the full dependence on palm oil in Malaysia. Keyword Biodiesel, papaya seed oil, rambutan seed oil, enzymatic transesterification, lipase