Enzymatic catalysis: An environmentally friendly method to enhance the transesterification of microalgal oil with fusel oil for production of fatty acid esters with potential application as biolubricants

Abstract

This work aimed at the enzymatic synthesis of fatty acid esters with potential application as biolubricants from microalgae oil and fusel oil using Burkholderia cepacia lipase immobilized on Nb2O5. The lipid-bearing Dunaliella salina biomass was grown in bubble column photobioreactors, yielding 100 g of biomass and 20 g of oil containing high content of saturated (37.8%) and monounsaturated fatty acids (41.2%) and a low content of polyunsaturated fatty acids (20.9%). The reaction assays were carried out in 50 mL glass reactor containing 10 g of medium composed by microbial oil and fusel oil components (ethyl, butyl, or isoamyl alcohols) and fusel oil as acyl acceptors at a fixed molar ratio of 1:8 (oil to alcohol) using iso-octane as solvent. Batch runs were performed at 45 °C under constant magnetic stirring (150 rpm) for a maximum of 120 h. Macaw palm oil was used as a control under the same reaction conditions. The biocatalyst was found to be efficient in converting the microalgal oil fatty acids into their corresponding alkyl esters attained yields ranging from 70.8 to 89.0% at 120 h reaction, depending on size of the alcohol chain. The kinematic viscosities of the esters produced confirmed the high transesterification yields, considering the viscosity of microalgae oil decreased from 60.1 to a range of 8.9–11.3 m2 s−1 (40 °C) after the enzymatic modification.