Degradation of MXC by host/guest-type immobilized laccase on magnetic tubular mesoporous silica

• Immobilized laccase was prepared by SPMNPs-enzyme co-adsorbing in the mesopores.
• Optimal conditions, reusability and kinetics for degradation of MXC were discussed.
• The degradation mechanism of MXC by immobilized laccase was studied.

In this paper, magnetic host/guest-type immobilized laccase was prepared by co-adsorption of super-paramagnetic particles (SPMNPs) and laccase into the pore channels of tubular mesoporous SiO2 by the “size-matching effect”. After immobilization, the thermal stability and repetition usage-ratio of immobilized laccase were improved significantly, the loading amount of enzyme and SPMNPs was determined by Lowry’s method and EDS (Energy Dispersive Spectroscopy), respectively. Under the optimal conditions, the removal efficiency of MXC (Methoxychlor) by immobilized laccase reached 69.4% and the removal efficiency still remained 45.4% after six cycles of operations. The studies on degradation kinetics of MXC by free and immobilized laccase were also carried out, respectively. In virtue of GC–MS, 1H NMR and 13C NMR analysis, (CH3OC6H5)2CCHCl and 1,1-diphenylethylene were identified as intermediate and final degradation products of MXC, respectively, further demonstrating the degradation mechanism of MXC by the immobilized laccase.

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