CPO‐Fe₃O₄@mTiO₂ nanocomposite with integrated magnetic separation and enzymatic and photocatalytic activities in efficient degradation of organic contaminants in wastewater

Abstract

BACKGROUND Immobilization of enzymes on a nanocarrier can improve their stability, but is often accompanied by a reduction of the initial catalytic activity. Meanwhile, inevitable mass loss during centrifugal separation inhibits reusability. It is still a challenge to design and prepare an immobilized enzyme with both improved catalytic activity and reusability simultaneously. RESULTS Core–shell magnetic microspheres (Fe3O4@mTiO2) with mesoporous structure were prepared and used to construct an enzymatic nanocomposite (CPO‐Fe3O4@mTiO2). This material can combine magnetic separability, photocatalytic property of TiO2 and enzymatic activity of chloroperoxidase (CPO) when applied in the degradation of aqueous organic contaminants diphenylamine and pesticide residue isoproturon. Moreover, CPO‐Fe3O4@mTiO2 showed good stability and reusability. It can keep 78.0% and 66.8% of its initial activity after incubation at 80 and 90 °C for 1 h, respectively, while free CPO only retained 18.3% and 6.9% of its original activity for the same conditions. After being used for eight cycles, CPO‐Fe3O4@mTiO2 can retain over 82.2% of activity. When applied in the degradation of isoproturon/diphenylamine in artificial wastewater, 60 μmol L−1 isoproturon can be completely degraded in 30 min; 82.2% of diphenylamine can be degraded at a concentration of 10 μmol L−1. Compared with the removal of aqueous contaminants using a porous adsorbent, CPO‐Fe3O4@mTiO2 can be regenerated ‘online’, obviating complicated procedures for regeneration. CONCLUSIONS The results indicate that CPO‐Fe3O4@mTiO2 has potential for practical application in the treatment of wastewater. © 2021 Society of Chemical Industry

Magnetic Nanoparticle-Containing Supports as Carriers of Immobilized Enzymes: Key Factors Influencing the Biocatalyst Performance

“…Magnetic porous supports were prepared by combining magnetic NPs and inorganic [13,41,51], polymeric [51,52] or carbon [53] porous materials. Magnetite NPs combined with reduced graphene oxide (rGO) plates were utilized as precursors for spray pyrolysis fabrication of nearly spherical porous magnetic supports for high efficiency enzyme immobilization [53].…”