Ultrasound-enhanced rapid in situ transesterification of marine macroalgae Enteromorpha compressa for biodiesel production

In situ transesterification of Enteromorpha compressa algal biomass was carried out for the production of biodiesel. The maximum methyl esters (ME) yield of 98.89% was obtained using ultrasonic irradiation. Tetra hydro furan (THF) and acid catalyst (H2SO4) was found to be an appropriate co-solvent and catalyst for high free fatty acids (FFA) content E. compressa biomass to increase the efficiency of the reactive in situ process. The optimization study was conducted to obtain the maximum yield and it was determined as 30 vol% of THF as a co-solvent, 10 wt% of H2SO4, 5.5:1 ratio of methanol to algal biomass and 600 rpm of mixing intensity at 65 °C for 90 min of ultrasonic irradiation time. The produced biodiesel was characterized by 1H nuclear magnetic resonance spectroscopy (1H NMR) analysis. Kinetic studies revealed that the reaction followed the first-order reaction mechanism. Rapid in situ transesterification was found to be suitable technique to produce biodiesel from marine macroalgae feedstock.