In this study,cage-like mesoporous silica was used as the carrier to immobilize laccase by a physical approach,followed by encapsulating with chitosan/alginate microcapsule membranes to form microcapsules of immobilized laccase based on layer-by-layer technology.The relationship between laccase activity recovery/leakage rate and the coating thickness was simultaneously investigated.Because the microcapsule layers have a substantial network of pores,they act as semipermeable membranes,while the laccase immobilized inside the microcapsules acts as a processing plant for degradation of2,4-dichlorophenol.The microcapsules of immobilized laccase were able to degrade 2,4-dichlorophenol within a wide range of 2,4-dichlorophenol concentration,temperature and p H,with mean degradation rate around 62%.Under the optimal conditions,the thermal stability and reusability of immobilized laccase were shown to be improved significantly,as the removal rate and degradation rate remained over 40.2% and 33.8% respectively after 6 cycles of operation.Using mass spectrometry(MS) and nuclear magnetic resonance(NMR),diisobutyl phthalate and dibutyl phthalate were identified as the products of 2,4-dichlorophenol degradation by the microcapsules of immobilized laccase and laccase immobilized by a physical approach,respectively,further demonstrating the degradation mechanism of 2,4-dichlorophenol by microcapsule-immobilized laccase.
Junya YangYan HuangYuxiang YangHongming YuanXiangnong Liu
