Chinese Journal of Catalysis ›› 2015, Vol. 36 ›› Issue (7): 961-968.DOI: 10.1016/S1872-2067(15)60856-7

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Enzymatic removal of chlorophenols using horseradish peroxidase immobilized on superparamagnetic Fe3O4/graphene oxide nanocomposite

Qing Changa, Guodong Jiangb, Heqing Tanga, Na Lia, Jia Huanga, Laiyan Wua   

  1. a Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Chemistry and Material Science, South-Central University for Nationalities, Wuhan 430074, Hubei, China;
    b College of Chemistry and Chemical Engineering, Hubei University of Technology, Wuhan 430068, Hubei, China
  • Received:2015-01-26 Revised:2015-04-08 Online:2015-06-12 Published:2015-07-30
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21107143, 21207033 and 21307164) and the Fundamental Research Funds for the Central Universities, South-Central University for Nationalities (CZY15003).

Abstract:

Magnetic Fe3O4 nanoparticles were successfully deposited on graphene oxide sheets by ultrasound-assisted coprecipitation. The nanoparticles were characterized using transmission electron microscopy, vibrating sample magnetometry, and X-ray photoelectron spectroscopy. The synthesized material was used as a support for the immobilization of horseradish peroxidase (HRP). The removals of 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol using the immobilized HRP were investigated. Batch degradation studies were used to determine the effects of the initial solution pH values, reaction temperature, reaction time, H2O2 and chlorophenol concentrations, and immobilized enzyme dosage on the removal of chlorophenols. The different numbers and positions of electron-withdrawing substituents affected the chlorophenol removal efficiency; the order of the removal efficiencies was 2-chlorophenol < 4-chlorophenol < 2,4-dichlorophenol. The oxidation products formed during chlorophenol degradation were identified using gas chromatography-mass spectrometry. The biochemical properties of the immobilized HRP were investigated; the results indicated that the storage stability and tolerance to changes in pH and temperature of the immobilized HRP were better than those of free HRP. The nanoparticles were recovered using an external magnetic field, and the immobilized HRP retained 66% of its initial activity for the first four cycles, showing that the immobilized HRP had moderate stability. These results suggest that the immobilized enzyme has potential application in wastewater treatment.

Key words: Magnetic nanoparticle, Immobilized enzyme, Horseradish peroxidase, Biodegradation, Chlorophenols, Wastewater treatment