Laccase immobilized on functionalized cellulose nanofiber/alginate composite hydrogel for efficient bisphenol A degradation from polluted water

Enzyme immobilization technique has a broad application prospect in the area of biotechnology, biochemistry, and environmental remediation. In this study, the composite hydrogel consisting of dopamine functionalized cellulose nanofiber and alginate was fabricated for immobilization of laccase. Infrared spectra, scanning electron micrographs, and energy dispersive X-ray analysis demonstrated that the laccase molecules were covalently immobilized onto the surface of composite hydrogel. The immobilized laccase exhibited the highest enzymatic activity about 462 U·g−1. Compared with free laccase, the pH, temperature, and storage stabilities of immobilized laccase were improved dramatically. Moreover, the immobilized enzyme can be easily separated from reaction system and reused. It retained 79.6% of its initial activity after 14 cycles of operation. Immobilized laccase was utilized for efficient degradation of bisphenol A (BPA) from polluted water, and the affecting factors on BPA removal efficiency were analyzed. Greater than 82% of BPA was removed under optimum conditions. A small amount of ABTS was added into BPA degradation; the removal efficiency had reached up to 98.7%. Results indicated that the immobilized laccase has great potential for industrial applications.Graphical abstract