Experimental investigation on simultaneous production of bioethanol and biodiesel from macro-algae

Abstract

The present work compares the biofuel production efficiency of Padina tetrastromatica and Sargassum swartzii macro-algae biomass by fermentation with Saccharomyces cerevisiae and Zymomonas Mobilis. The optimal pretreatment factors were identified by studying the effect of temperature, pH, and enzyme concentration on the conversion of macroalgae biomass to fermentable reducing sugars. The Low concentration of enzyme did not help conversion of biomass to reducing sugars even after 15 h of treatment with enzyme, but when the enzyme concentration was increased, the desired conversion was completed within 4 h of enzyme treatment. Both Padina tetrastromatica and Sargassum swartzii had an ethanol yield of above 80% irrespective of the difference in the species used for the fermentation. The highest possible ethanol yield (95.12%) was achieved for Padina tetrastromatica biomass when it was fermented with Zymomonas Mobilis. From the above results, it is clear that both Padina tetrastromatica and Sargassum swartzii have the potential to be used as reliable feedstock for biofuel production. The spent biomass after the fermentation process was used for the lipid extraction process and the extracted lipid was used for biodiesel production. The percentage of biodiesel yield obtained by means of the Soxhlet extraction process from Padina tetrastromatica and Sargassum swartzii macro-algae with the conventional NaOH catalyst was found to be 84% and 89% respectively. MgO.La2O3 was synthesized by means of the co-precipitation method. With the introduction of MgO.La2O3 nano-catalyst biodiesel yield was improved up to 88% and 92% for Padina tetrastromatica and Sargassum swartzii macro-algae, respectively.