BIODIESEL PRODUCTION FROM MICROALGAE THROUGH NANOCATALYTIC TRANSESTERIFICATION PROCESS

Abstract

Biodiesel is an environmentally friendly, less hazardous biofuel that has been extensively investigated in the past few years to help us minimize our dependence on fossil fuels and cut radiations. The most significant criteria for effective biodiesel production are feedstock and catalyst selection. A variety of raw materials can be utilized to produce biodiesel, including several types of oils of vegetable, microbes, animal fats, algae and waste materials. Microalgae is an ideal feedstock for biodiesel production due to its rapid growth and high lipid content. The influence of nanocatalysts in increasing biodiesel production is an emerging field due to its high catalytic efficiency. The nanocatalyst can be utilized in the different stages of the biodiesel production process from microalgae, such as during the stages of cultivation, harvesting, lipid extraction, and transesterification. The transesterification process can be carried out using various types of catalysts categorized as homogeneous, heterogeneous and enzymatic catalysts with some bottlenecks such as lower yield, difficulty in phase separation, mass transfer resistance, higher production cost, and slow reaction rate. Thus, biodiesel production by nanocatalyzed transesterification is preferable as it addresses the challenges raised by using homogeneous, heterogeneous, and enzymatic catalysts. because of its obvious advantage of higher specific surface area, high resistance to saponification and higher catalytic activity. The nanocatalytic transesterification on different feedstocks for biodiesel production has been discussed by various authors, but the approach of algae derived biodiesel using various nanocatalysts such as calcium methoxide Ca(OCH3)2 nanocatalyst, lithium impregnated calcium oxide 1.75Li-CaO nanocatalyst, and rice husk ash doped with sodium oxide and nickel oxide RHA/Na2O-20%/Ni-x% were explored and thus synthesized through wet impregnation technique and exploited in transesterification process. The synthesis methods, spectral and structural properties using characterization techniques, regeneration and reuse of nanocatalyst are discussed. Along with nanocatalyst modification, the role of optimization parameters such as methanol to oil molar ratio, catalyst loading, reaction temperature and time in enhancing the biodiesel yield are offered. The effect of transesterification parameters for Ca(OCH3)2 nanocatalyst on biodiesel yield were analyzed by employing a central composite design based response surface methodology. The fatty acid methyl esters yield was examined by using gas chromatography equipped with mass spectroscopy. The physical properties of microalgae based biodiesel through nanocatalytic transesterification were studied and compared with the conventional diesel based on international standards.