CPO‐Fe 3 O 4 @ mTiO 2 nanocomposite with integrated magnetic separation and enzymatic and photocatalytic activities in efficient degradation of organic contaminants in wastewater

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 (Fe 3 O 4 @mTiO 2 ) with mesoporous structure were prepared and used to construct an enzymatic nanocomposite (CPO‐Fe 3 O 4 @mTiO 2 ). This material can combine magnetic separability, photocatalytic property of TiO 2 and enzymatic activity of chloroperoxidase (CPO) when applied in the degradation of aqueous organic contaminants diphenylamine and pesticide residue isoproturon. Moreover, CPO‐Fe 3 O 4 @mTiO 2 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‐Fe 3 O 4 @mTiO 2 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‐Fe 3 O 4 @mTiO 2 can be regenerated ‘online’, obviating complicated procedures for regeneration. CONCLUSIONS The results indicate that CPO‐Fe 3 O 4 @mTiO 2 has potential for practical application in the treatment of wastewater. © 2021 Society of Chemical Industry