| Laccase can act on a variety of substrates,but laccase is extremely easily deactivated in aqueous solution,and it is difficult to recover,which makes it difficult to apply it to industrialization.In order to better solve the above disadvantages of laccase.In this paper,magnetic nanomaterials are used to immobilize laccase,which not only solves the problem of laccase inactivation in solution,but also realizes the recycling of laccase.First,the carrier was prepared by hydrothermal synthesis and the relevant material was characterized.The optimal glutaraldehyde concentration,reaction p H,and reaction time were investigated.Secondly,the acid-base stability,thermal stability,storage stability,recyclability of the immobilized laccase were explored and the thermal inactivation mechanics of the immobilized laccase in polar nonpolar / sex / toxic systems were explored.The effects of immobilized laccase on 2,4-dichlorophenol under different conditions were investigated.The main conclusions are as follows:(1)Magnetic nano Fe3O4-Si O2 support was prepared by hydrothermal synthesis.Scanning electron microscopy(SEM)showed that the prepared material was a microsphere with a diameter of about 500 nm.X-ray energy scattering element distribution map(EDS Mapping)showed that It contains Fe,Si,and O.X-ray diffraction(XRD)indicates that the phases are Fe3O4 and Si O2.Transmission electron microscopy(TEM)shows that the outer layer of Fe3O4 microspheres is coated with a thin layer of Si O2.Magnetic field strength characterization(VSM)indicates Fe3O4-Si O2 has paramagnetism and good magnetic response.The characteristic absorption peaks of Si-O-Fe,a company unique to Fe3O4-Si O2,appear in Fourier transform infrared spectroscopy(FTIR).Fe3O4-Si O2 material is completely suitable as an immobilized support.(2)The results of immobilization of laccase by magnetic nanomaterials showed that: when the concentration of glutaraldehyde was 2%,p H=6,and the immobilization time was 6h,the laccase’s immobilization capacity was the largest.(3)Investigate the properties of immobilized laccase,and compare with free laccase,find that the optimal p H value rises from 3 to 4,and the optimal temperature changes from 65°C to 45°C,which reduces the cost of industrialized application of laccase;fixed After 20 days of laccase storage,the enzyme activity was 1.3 times that of free laccase enzyme under the same storage conditions.Recovery experiments showed that the relative enzyme activity remained at 40% after repeated use 5 times,indicating that the storage stability of immobilized laccase was good and has good recyclability;The mechanical equation of heat loss and thermodynamic constants of immobilized laccase in polar/nonpolar/toxic systems were studied,which provided references for the application of immobilized laccase in different solutions.(4)Degradation of 2,4-dichlorophenol by using immobilized laccase,it was found that the degradation rate of immobilized laccase at p H=6,temperature 65°C,and initial concentration of 2,4-dichlorophenol 10mg/L Highest,and the reusability of the immobilized laccase is good.Even after repeated use 7 times,the removal rate of 59% can be maintained. |
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