Synthesis of Biodiesel from the Oily Content of Marine Green Alga Ulva fasciata

The present study is focused on the chemical transformation of oils derived from the marine green alga Ulva fasciata Delile to biodiesel. The transesterification of algal oil was performed with a variety of alcohols using Na metal and NaOH as catalysts. Transesterification of algal oil by mechanical stirring yielded significant biodiesel within an hour at 60 degrees C with NaOH and at room temperature with Na metal. In addition, microwave irradiated transesterification produced significant amount of biodiesel with NaOH and Na metal within 1-5 minutes. However, reaction of sodium metal in microwave oven was highly exothermic and uncontrollable that could also damage the radiation source. The reactivity order of alcohols was found to be methanol > ethanol > benzyl alcohol > 1-propanol > 1-butanol > 1-pentanol > 1-hexanol > 2-propanol. Isopropyl alcohol was found to be least reactive due to steric hindrance. Benzyl alcohol was found to be more reactive than 1-propyl alcohol due to the electron withdrawing effect of benzene ring. The highest % conversion of FAME and FAEE were found to be 97% and 98% respectively using Na metal through mechanical stirring. Biodiesel production was confirmed by thin layer chromatography (TLC). Furthermore, the fuel properties including density, kinematics viscosity, high heating value, acid value, free fatty acid (%), cloud point and pour point of U. fasciata oil and all the esters were determined and compared with the standard limits of biodiesel. Fatty acid methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 1-pentyl and 1-hexyl esters showed the fuel properties within the biodiesel standard limits therefore all of them were considered as the substitute of biodiesel. On the other hand, the fuel properties of benzyl ester were found to be above the limits of biodiesel specifications and thus it could not be considered as biodiesel. This research article will be helpful to overcome the current challenges of energy crisis, global warming and environmental pollution.