Whole-cell Mucor circinelloides immobilized on hydrophobically modified loofah sponge for sustainable biodiesel...

The low reusability of whole-cell biocatalysts caused by glycerol adsorption remains a critical challenge in biodiesel production. In this study, loofah sponge pellets (LSP) carriers were hydrophobically modified with different concentrations of rosin-based modifier (RM) to enhance the performance of immobilized Mucor circinelloides whole-cell biocatalysts. The modified carriers were characterized by multispectral analysis and water contact angle measurements, confirming the successful increase of surface hydrophobicity. Compared with unmodified LSP, the moderately modified carrier (3% RM) exhibited enhanced catalyst reusability while maintaining high cell loading and catalytic activity. After eight reaction cycles, the optimized MC@LSP-3%RM catalyst retained 71.58% relative biodiesel yield, whereas the unmodified MC@LSP retained only 48.16%. Moreover, glycerol adsorption was reduced by 22.08%, which effectively mitigated mass transfer limitations and enzyme deactivation. These findings indicate that moderate carrier hydrophobic modification represents an effective approach for alleviating glycerol inhibition, improving biocatalyst stability, and enhancing the reusability of whole-cell biocatalysts for sustainable biodiesel production.