Laccase Immobilization with Silica/Chitosan Macroporous Composites and its Application in 2,4-Dichlorophenol Degradation

A new macroporous silica/chitosan(Si O_2/CS) composite was prepared by adsorbing CS on pore wall of a large-sized macroporous silica, and it was employed as the support for the immobilization of commercial Novozymes laccase by using glutaraldehyde as the crosslinking agent. The best activity recovery of the immobilized laccase is 85.5% under conditions of buffer solution p H 4.5, initial laccase concentration 40 mg×m L~(-1) and immobilizing time of 4 h. The p H and thermal stabilities of the immobilized laccase are significantly improved comparing to free laccase. Moreover, the immobilized laccase has good operational stability. The immobilized laccase was used to remove 2,4-dichlorophenol(2,4-DCP), and the effects of degradation time, p H value, temperature and initial concentration of 2,4-DCP on 2,4-DCP removal rate were investigated. Up to 83.2% of 2,4-DCP(20 mg×L~(-1)) was removed under optimized conditions. The immobilized laccase has good reusability and can be easily recovered from the reaction system.