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 ( [email protected] ) showed better catalytic performance than [email protected] , with faster conversion rate in lipase-mediated biodiesel production. Remarkably, the higher surface hydrophobicity of the [email protected] 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 [email protected] and [email protected] , 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 [email protected] with polydimethylsiloxane (PDMS). The as obtained super hydrophobic [email protected] @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 [email protected] , and 1.8 folds of that catalyzed by [email protected] . This work shed light on the great potential of constructing MOF-derived hierarchically ordered porous carbon for enzyme immobilization in extensive practical applications.
Efficient solvent-free synthesis of CO-based bio-surfactants was established. • Liquid lipase overcomes diffusion barriers of immobilized lipases in glycerolysis. • High DAG yields are rapidly achieved (99 min) under remarkably mild conditions. • DSP and MSP were isolated via two-stage molecular distillation. • Bio-surfactants outperform commercial benchmarks in surface activity. Monoglycerides and diglycerides are high value-added sustainable bio-surfactants. However, their synthesis is limited due to the high energy consumption of chemical catalysts and mass transfer limitation of the immobilized enzymes. To circumvent these bottlenecks, a highly efficient, solvent-free strategy was established for the biocatalytic synthesis of bio-based surfactants through the glycerolysis of castor oil using liquid lipases. Results showed that Eversa® Transform 2.0 was the best biocatalyst. Under the optimal conditions (29 °C, 99 min, 1:6 oil-to-glycerol ratio), 42.30 ± 2.11% MAG yield and 49.84 ± 0.58% DAG yield were achieved. An activation energy 31.24 kJ/mol and a K m value of 0.701 were obtained via kinetic analysis. Furthermore, a two-stage molecular distillation was engineered to successfully fractionate the crude mixture into customized products: a DAG-enriched surfactant (DSP, containing 49.90 ± 1.00% DAGs and 42.30 ± 2.10% MAGs) and a high-purity MAG-enriched surfactant (MSP, containing 91.30 ± 1.70% MAGs and 4.90 ± 1.30% DAGs). Finally, molecular docking confirmed that the ET 2.0 lipase constructed a multidimensional hydrophobic network primarily via the key amino acid residues (e.g., Leu206, Trp89, and Phe113). Triricinolein is stably bound by this hydrophobic configuration, which precisely positions the target ester bond near the catalytic center to promote efficient cleavage and biocatalysis. Download: Download high-res image (273KB) Download: Download full-size image
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