A novel support of sponge-like cellulose composite polymer for immobilizing laccase and its application in nitrogenous organics biodegradation

For the first time, the cellulose (Ce) composite polymer beads were fabricated by initiating polymerization of dopamine, glycidylmethacrylate and N,N-methylene bisacrylamide in Ce solution dissolved by ionic liquid. The beads were characterized by scanning electron microscopy, FT-IR spectroscopy and X-ray diffraction, and the results showed that the Ce composite polymer beads possessed the sections of the run-through sponge-like macropores and the reactive functional groups. The laccase (Lac) was covalently immobilized through the reaction between the amino groups of the enzyme and the epoxy groups and quinone groups as well as phenolic hydroxyls onto the beads. The effect of Lac concentration, temperature and pH stability on the activities of the biocatalyst was determined. The results showed that the immobilized Lac showed enhanced temperature and pH stability compared with free Lac. The biocatalyst was applied for nitrogenous organics biodegradation where the degradation efficiency reached 99.9% for indole and 97.4% for carbazole in present of 2 mg ABTS at pH 5.0 and 30 degrees C, which were far higher than that of indole and carbazole were degraded by Lac alone. In addition, 95.1% of indole and 66.2% of carbazole were eliminated after ten-cycle batch, which demonstrated that the immobilized Lac had excellent catalytic performance and reusability. Accordingly, the sponge-like Ce composite polymer beads were potential support for immobilizing enzyme.