Esterification by immobilized lipase in solvent-free media: kinetic and thermodynamic arguments

The aim of this study is to characterize, in solvent-free systems (SFS), the kinetic and thermodynamic performance of batch lipase-catalyzed esterification. SFS are compared to a conventional organic solvent, n-hexane. The esterification of oleic acid with ethanol was chosen as a model reaction. The TABEK (thermodynamic activity-based enzyme kinetics) approach was used to rationally analyze kinetics. Influence of the reaction medium on final conversions was also studied. Several factors, such as initial molar ratio of substrates, reactant availability, initial water content, and quantity of immobilized enzyme, were examined. Special attention was also turned to enzyme stability and reuse after reaction, this last item being a prerequisite in the development of industrial processes. SFS proved to be almost as efficient as n-hexane from a kinetic and thermodynamic point of view and offered a better volumetric production.