Performance of candida rugosa lipase supported on nanocellulose-silica-reinforced polyethersulfone membrane for the synthesis of pentyl valerate: kinetic, thermodynamic and regenerability studies

Abstract

The present study reports the groundwork for preparing a greener catalyst, Candida rugosa lipase (CRL), supported on biomass-based nanocellulose-silica-reinforced polyethersulfone membrane (NC-SiO2-PES) and proved its stability in synthesizing pentyl valerate. The NC-SiO2-PES/CRL-catalyzed synthesis of the ester exhibited a ping-pong bi-bi mechanism, with a high Vmax value and low Km value over the free CRL, confirming the former's greater substrate affinity. The kinetics data demonstrated that the NC-SiO2-PES/CRL was catalytically more efficient than its free counterpart. The lower Michaelis-Menten constant of NC-SiO2-PES/CRL for pentanol (Km,B = 43.53 mM) than valeric acid (Km,A = 82.03 mM) indicates that pentanol was favored over the latter. Pertinently, the higher thermal deactivation values of NC-SiO2-PES/CRL indicated that the NC-SiO2-PES membrane successfully enhanced CRL thermal stability, and the process followed first-order kinetics (R2 > 0.95). The NC-SiO2-PES/CRL has a slightly greater activation energy (Ea) and activation energy for thermal denaturation (Ed) over the free CRL. NC-SiO2-PES/CRL also exhibited extended operational stability, with a robust half-life of ∼150 h and the absence of leached protein after 60 min of agitation. The NC-SiO2-PES/CRL's ability to be regenerated chemically and ultrasonically and reused without significant loss in enzyme activity denotes its potential cost-saving to produce pentyl valerate.