Ionothermal synthesis of Cu-doped Fe3O4 magnetic nanoparticles with enhanced peroxidase-like activity for organic wastewater treatment

The intrinsic peroxidase-like activity of magnetite magnetic nanoparticles (Fe3O4 MNPs) has to be improved to activate H2O2 under mild conditions for practical applications. Herein copper-doped Fe3O4 (Fe3-xCuxO4, x: 0.06-0.23) MNPs were successfully prepared by oxidative precipitation-combined ionothermal synthesis and characterized by XRD, VSM, XPS, BET, etc. The Cu2+ dopants are mainly substituted for Fe2+ ions at octahedral sites and significantly surface-enriched, which expedite the Fe3+/Fe2+ redox cycling and enhance the H2O2-activation ability of Fe3-xCuxO4 MNPs. Kinetic study showed that the decomposition of H2O2 on Fe2.88Cu0.12O4 was much faster than that on the undoped Fe3O4 (0.584 vs. 0.153 h(-1) at 25 degrees C) due to the lower activation energy of the former (55.3 vs. 62.1 kJ/mol). The enhanced H2O2-activation ability upon copper doping was exploited to efficiently degrade recalcitrant organic pollutants (e.g., rhodamine B) with H2O2 at pH similar to 7 and 25 degrees C on Fe2.88Cu0.12O4 with good stability and reusability (16 h tested in eight cycles). (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.