Copper-promoted heterogeneous Fenton-like oxidation of Rhodamine B over Fe3O4 magnetic nanocatalysts at mild conditions

Rhodamine B (RhB) is used in various industries and its effluent must be effectively treated because of its harmful and carcinogenic nature. In this work, ionothermally synthesized Cu-doped Fe3O4 magnetic nanoparticles (Cu-Fe3O4 MNPs) were found to be a highly efficient heterogeneous Fenton-like catalyst for complete decolorization of the RhB solution with H2O2 at pH ~ 7 and 25 °C. The effects of the catalyst loading, initial concentrations of RhB and H2O2, co-existing natural organic matter and inorganic salts, reaction temperature, and radical scavengers on the catalytic performance of Cu-Fe3O4 were investigated. Monte-Carlo simulations revealed that copper dopants facilitated the activation of H2O2 via adopting a terminal end-on adsorption mode and increased collision frequency by bringing the RhB molecules closer to H2O2 and the magnetite surface. These theoretical calculations provide new insight into the promotional effect of copper dopants in magnetite at molecular level.