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

Abstract

• NC-SiO 2 -PES/CRL-catalyzed esterification followed a ping-pong bi-bi mechanism. • CRL supported on NC-SiO 2 -PES membrane possess substantial thermal stability. • NC-SiO 2 -PES/CRL exhibited extended operational and storage stability. • Ultrasonic regeneration method successfully refreshed the NC-SiO 2 -PES/CRL. 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-SiO 2 -PES) and proved its stability in synthesizing pentyl valerate. The NC-SiO 2 -PES/CRL-catalyzed synthesis of the ester exhibited a ping-pong bi-bi mechanism, with a high V max value and low K m value over the free CRL, confirming the former's greater substrate affinity. The kinetics data demonstrated that the NC-SiO 2 -PES/CRL was catalytically more efficient than its free counterpart. The lower Michaelis-Menten constant of NC-SiO 2 -PES/CRL for pentanol (K m, B = 43.53 mM) than valeric acid (K m, A = 82.03 mM) indicates that pentanol was favored over the latter. Pertinently, the higher thermal deactivation values of NC-SiO 2 -PES/CRL indicated that the NC-SiO 2 -PES membrane successfully enhanced CRL thermal stability, and the process followed first-order kinetics (R 2 > 0.95). The NC-SiO 2 -PES/CRL has a slightly greater activation energy (E a ) and activation energy for thermal denaturation (E d ) over the free CRL. NC-SiO 2 -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-SiO 2 -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.