Preparation and physicochemical properties of naturally grown green spirogyra algae biodiesel

In this study, biodiesel was produced from a naturally grown green algae (spirogyra). The algae were cultivated in an open pond for 180 days without any fertilizers or nutrients. The dried algae powder to oil yield and significant fuel properties of viscosity, density, cetane number, calorific value, flash point, pour and cloud points are investigated for B10 to B100 blends. The results of solvent oil extraction show that at a 1:2 (algae powder to solvent) ratio and 65oC, algae oil yield was observed as 22.66%. Furthermore, Box-Behnken assisted response surface optimization technique was implemented. From the 29 random experiments, 96.24% spirogyra algae oil biodiesel (SAOBD) yield was achieved under the optimum conditions of 50oC, 180 minutes, the molar ratio of 9:1 and catalyst concentration of 0.5 wt%. The fatty acid composition (FAC) by gas chromatography reveals that 73.95 wt% saturated FAC was observed in SAOBD. The significant fuel properties are measured by following ASTM-D6751 standards and 40% SAOBD in diesel fuel could possibly be an optimum blend ratio for engine experimentation. Finally, regression equations with high correlation coefficients (R2) were developed for the fuel properties to predict the various blend ratios.