Small scale biodiesel production from <em>Sargassum</em> sp and optimization of conditions for yield enhancement

Production of biofuel from excessive natural resources and underutilized plant materials has drawn global attention due to its cost effectiveness, eco friendliness and sustainability compared to the conventional fossil fuels. This work was aimed to select the best marine flora available in the Northern Sri Lankan sea to produce biodiesel and to optimize the conditions to enhance the yield. Sargassum sp., Ulva fasciata, Turbinaria ornata, Gelidium sp. and Thalassia sp. were collected from the coastal region of the Jaffna peninsula and washed thoroughly sun-dried. The organic solvents used to extract oil from these algal and sea grass species were n-hexane and di-ethyl ether, while alkaline catalysts were used to convert the extracted oil into biodiesel via trans-esterification reaction. When the oil extraction was done separately from the five dried marine plant species using n-Hexane and Di-ethyl ether as solvents, significantly higher quantity of oil was obtained from Sargassum sp. than the other tested algal and plant species, hence Sargassum sp. was selected for further studies. When the conditions for the extraction of oil from Sargassum sp. such as Sargassum to solvent(n-Hexane: Di-ethylether) ratio (0:200), amount of algal biomass (100g), longer contact time (24h), molar ratio (4:1), catalyst amount (0.6%), temperature (600C), reaction time (25min) were optimized before the conversion of oil into biodiesel via trans-esterification reaction, there was a significant increase in the quantity of extracted oil by 11.7 times than the non-optimized conditions. Since the density of the biodiesel (867.3 kg/m3) meets the international standards, the quality of the biodiesel produced from Sargassum sp. could be recommended as satisfactory. Large scale multicenter studies need to be done in order to confirm and implement this finding.