USPIO assisting degradation of MXC by host/guest-type immobilized laccase in AOT reverse micelle system

Abstract

The laccase and ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) have been assembled inside the tubular mesoporous silica via co-adsorption technology to prepare host/guest-type immobilized laccase, which is applied to degrade methoxychlor (MXC) in aqueous and reverse micelle environments. The effects of various parameters on degradation of MXC were studied. Under the optimum conditions, the degradation rate could reach maximum value of 45.6 % and remain at 20.8 % after seven cycles. Moreover, the addition of small molecular compound 2, 2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) to the system could greatly improve the degradation efficiency. The MXC degradation process is a first-order reaction, and the activation energy of MXC degradation catalyzed by immobilized laccase (41.46 kJ mol(-1)) is relatively lower than that catalyzed by free laccase (44.91 kJ mol(-1)). Based on the degradation products measured by gas chromatograph-mass spectrometer (GC-MS) and nuclear magnetic resonance (NMR), the degradation mechanism of MXC has also been proposed.

Immobilizing white‐rot fungi laccase: Toward bio‐derived supports as a circular economy approach in organochlorine removal

“…For the degradation of chlorpyrifos, Nandabalan et al (2017) observed that at a loading rate of 20 mg Lac immobilized on magnetic nanoparticles, the enzyme retained 95% of its activity after five consecutive cycles and degraded 99% of the insecticide within 12 h of incubation at pH 7°C and 60°C. In the case of methoxychlor, Yang et al (2016) reported a degradation rate of methoxychlor of about 46% under optimal conditions with Lac immobilized on tubular mesoporous silica containing ultrasmall superparamagnetic iron oxide nanoparticles as catalyst. The authors observed that the degradation rate was 20.8% after seven cycles.…”