Stabilized magnetic enzyme aggregates on graphene oxide for high performance phenol and bisphenol A removal

Abstract

We develop a magnetically-separable and stabilized method for the remediation of phenol and bisphenol A in water by the biocatalysis of magnetic enzyme aggregates on graphene oxide (GRO). Both magnetic nanoparticles (MNPs) and tyrosinase (Tyr) were covalently attached on GRO (Mag-CA-Tyr/GRO), and additional glutaraldehyde treatment was performed to construct multi-layers of cross-linked MNPs and Tyr aggregates on GRO (Mag-EC-Tyr/GRO). Mag-EC-Tyr/GRO consisted of thicker layers than the covalent attached method according to atomic force microscopy analysis, and degraded both phenol and bisphenol A in high efficiency. Over broad ranges of temperature and pH, the Mag-EC-Tyr/GRO degraded phenol more efficiently than free and covalent attached Tyr. Mag-EC-Tyr/GRO was more stable than the covalent attached Tyr, and retained over 56% of its initial activity after five cycles of repeated uses for phenol degradation. Owning to the high stability and robustness property, Mag-EC-Tyr/GRO enabled successful degradation of bisphenol A in the environmental water. (C) 2016 Elsevier B.V. All rights reserved.