Pyrite-Assisted Degradation of Mxc by Laccase Immobilized on Fe3s4/Ew-Msio2

Abstract

Abstract ： Laccase, immobilized and cross-linked on Fe3S4/earthworm-like mesoporous SiO2 (Fe3S4/EW-mSiO2 ), was used to degrade methoxychlor (MXC) in aqueous environments. The effects of various parameters on the degradation of MXC were determined using free and immobilized laccase. Immobilization improved the thermal stability and reuse of laccase significantly. Under the optimum conditions, the degradation rate of MXC by immobilized laccase reached a maximum value of 40.99% and remained at 1/3rd after six cycles. The excellent degradation performance of Fe3S4 /EW-mSiO2 might be attributed to the pyrite (FeS2 ) impurity in Fe3S4 acting as an electron donor in reductive dehalogenation. Sulfide groups and Fe2+ reduced the activation energy of the system resulting in pyrite-assisted degradation of MXC. The degradation mechanism of MXC in aqueous environments by laccase immobilized on Fe3S4 /EW-mSiO2 was determined via mass spectroscopy of the degradation products.

Keywords: methoxychlor· immobilized laccase· Fe3S4/earthworm-like mesoporous SiO2