Magnetic Polyethyleneimine Nanoparticles Fabricated via Ionic Liquid as Bridging Agents for Laccase Immobilization and Its Application in Phenolic Pollutants Removal

In this study, polyethyleneimine was combined with magnetic Fe3O4 nanoparticles through the bridging of carboxyl-functionalized ionic liquid, and laccase was loaded onto the carrier by Cu2+ chelation to achieve laccase immobilization (MCIL-PEI-Cu-lac). The carrier was characterized by Fourier transform infrared spectroscopy, scanning electron microscope, thermogravimetric analysis, X-ray diffraction analysis, magnetic hysteresis loop and so on. MCIL-PEI-Cu-lac has good immobilization ability; its loading and activity retention could reach 52.19 mg/g and 91.65%, respectively. Compared with free laccase, its thermal stability and storage stability have been significantly improved, as well. After 6 h of storage at 60 degrees C, 51.45% of the laccase activity could still be retained, and 81.13% of the laccase activity remained after 1 month of storage at 3 degrees C. In the pollutants removal test, the removal rate of 2,4-dichlorophenol (10 mg/L) by MCIL-PEI-Cu-lac could reach 100% within 10 h, and the removal efficiency could still be maintained 60.21% after repeated use for 8 times. In addition, MCIL-PEI-Cu-lac also has a good removal effect on other phenolic pollutants (such as bisphenol A, phenol, 4-chlorophenol, etc.). Research results indicated that an efficient strategy for laccase immobilization to biodegrade phenolic pollutants was developed.

Automated summary

In this study, a highly efficient strategy for laccase immobilization to degrade phenolic pollutants was developed by combining polyethyleneimine with magnetic Fe3O4 nanoparticles and chelating laccase onto the carrier through Cu2+ chelation. The carrier demonstrated excellent immobilization ability and high activity retention. It showed improved thermal stability and storage stability compared to free laccase. The immobilized laccase also exhibited a good removal effect on various phenolic pollutants.