Wood-biomimetic microfluidic enzymatic reactor for intensified continuous-flow synthesis of flavor esters

Natural woods are abundant and renewable biomass resources, the inherent microchannels and micropores make woods the ideal microfluidic device. In this study, a wood-biomimetic microfluidic enzymatic reactor (CALB@BW-C₈) was proposed by hydrophobically functionalizing balsa wood column (BW) using octyltrimethoxysilane (C₈) and immobilizing lipases for the continuous-flow catalytic synthesis of flavor esters. Results indicate that C₈ modification improved the water contact angles of BW from 52.0° to 122.7°, thus providing the hydrophobic microenvironment to enhance enzyme activity and stability. When two CALB@BW-C₈ reactors were connected in series, the continuous-flow conversion of hexyl hexanoate reached 91% under solvent-free conditions. Besides, the superior thermal stability, long-term reusability, broad applicability, mechanical strength and porous stability of CALB@BW-C₈ also highlighted its industrial potential. Finally, computational fluid dynamics (CFD) simulations revealed that liquid substrates could migrated through intervessel pits to achieve cross-channel mass transfer, while the vessel perforation plates further enhanced local turbulence to promote the sufficient substrate-enzyme contacted. Hence, this paper innovatively combined the natural microfluidic wood with enzymatic catalysis, to achieve the continuous and sustainable production of flavor esters.