Bronsted acidic ionic liquid-catalyzed and ultrasound-promoted transesterification of fish oil with ethanol

Four typical Bronsted acidic ionic liquids (BILs) and concentrated sulphuric acid (H2SO4) were used to catalyze the transesterification of fish oil with ethanol to produce fatty acid ethyl ester (FAEE) in this work. The experimental results show that the imidazole BILs lead to fewer side reactions and higher product quality than H2SO4. Molecular dynamics (MD) simulations indicate that [PSMim][HSO4] molecules can be enriched at the interface and enhance the contact of eicosapentaenoic acid triglyceride (EPATG, a typical component of fish oil) and ethanol. And ester groups of EPATG tend to expose more to ethanol in the BILs system, which facilitates the occurrence of transesterification. However, H2SO4 has no positive effect on the distribution of the two reactants. For the transesterification, the interfacial property affects the catalytic activity a lot, instead of catalyst acidity. Also, the reaction rate is accelerated, obviously, by ultrasound-led liquid-liquid phase emulsification.

Automated summary

Four typical Bronsted acidic ionic liquids (BILs) and concentrated sulphuric acid (H2SO4) were used to catalyze the transesterification of fish oil with ethanol. The results showed that BILs led to higher product quality and fewer side reactions compared to H2SO4. Molecular dynamics simulations indicated that BILs enhanced the contact of fish oil and ethanol at the interface, promoting the transesterification reaction. Furthermore, ultrasound-led liquid-liquid phase emulsification significantly accelerated the reaction rate.