Preparation and characterization of epoxy-functionalized magnetic chitosan beads: laccase immobilized for degradation of reactive dyes

Cross-linked magnetic chitosan beads were prepared by phase-inversion technique in the presence of epichlorohydrin under alkaline condition, and used for covalent immobilization of laccase. The activity of the immobilized laccase on the magnetic chitosan was about 260 U (g/dry beads) with an enzyme loading of about 16.33 ± 0.39 mg [(g/dry beads) mg/g]. Kinetic parameters, Vmax and Km values were determined as 21.7 U/mg protein and 9.4 μM for free enzyme, and 15.6 U/mg protein and 19.7 μM for the immobilized laccase, respectively. The operational and thermal stabilities of the immobilized laccase were improved compared to free counterpart. The immobilized laccase was operated in a batch reactor for the decolorization of reactive dyes from aqueous solution. The laccase immobilized on magnetic chitosan beads was very effective for removal of textile dyes from aqueous solution which creates an important environmental problem in the discharged textile dying solutions.