MOF-derived hierarchically ordered porous carbon for the immobilization of Eversa® Transform 2.0 and its post-immobilization hydrophobization in biodiesel production

Abstract

MOF-derived carbon has extraordinary advantages including highly ordered morphology inherited from MOFs and improved chemical stability arising from its carbon nature, which may be a promising immobilized enzyme carrier. Herein, we prepared two MOF-derived carbon materials of different structures for the immobilization of lipase from Eversa® Transform 2.0 and systematically evaluated their application potential in biodiesel production system. Compared with C-C (derived from conventional microporous ZIF-8), 3DOM-C (derived from 3D ordered macro-microporous ZIF-8) exhibited superior immobilization performance with an 145.1% increase in enzyme loading and an 130.2% increase in activity. Moreover, lipase immobilized on 3DOM-C (3DOM-C@TLL) showed better catalytic performance than C-C@TLL, with faster conversion rate in lipase-mediated biodiesel production. Remarkably, the higher surface hydrophobicity of the 3DOM-C@TLL was proved to be the key factor in its improved catalytic performance. Meanwhile, we found that the affinity between immobilized enzyme molecules and water significantly weakened the hydrophobicity of C-C@TLL and 3DOM-C@TLL, which could be of adverse effect on their application in biodiesel production. To enhance the hydrophobicity of immobilized lipase biocatalyst, a facile post-immobilization hydrophobic modification strategy was proposed by coating the 3DOM-C@TLL with polydimethylsiloxane (PDMS). The as obtained super hydrophobic 3DOM-C@TLL@PDMS biocatalyst showed excellent catalytic performance in biodiesel production, with a much higher initial reaction rate, which was 3.3 folds of that catalyzed by C-C@TLL, and 1.8 folds of that catalyzed by 3DOM-C@TLL. This work shed light on the great potential of constructing MOF-derived hierarchically ordered porous carbon for enzyme immobilization in extensive practical applications.