Magnetic CoFe₂O₄ nanoparticles supported on graphene oxide (CoFe₂O₄/GO) with high catalytic activity for peroxymonosulfate activation and degradation of rhodamine B

Abstract

Herein, we report the preparation of magnetic CoFe₂O₄ nanoparticles and CoFe₂O₄/graphene oxide (GO) hybrids and evaluate their catalytic activity as heterogeneous peroxymonosulfate (PMS) activators for the decomposition of rhodamine B. The surface morphologies and structures of both CoFe₂O₄ nanoparticles and CoFe₂O₄/GO hybrids were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption-desorption isotherms. The magnetic properties of the samples were assessed using a SQUID magnetometer at 298 K. Catalytic oxidation experiments demonstrated that CoFe₂O₄/GO hybrids exhibited much better catalytic activity than CoFe₂O₄ nanoparticles or CoFe₂O₄/reduced graphene oxide (rGO) hybrids, suggesting that GO plays an important role in CoFe₂O₄/GO hybrids in the decomposition of rhodamine B. The influence of various reaction conditions such as temperature, concentration of PMS, pH and decomposition time of rhodamine B over the CoFe₂O₄/GO catalyst were investigated and optimized. The rhodamine B degradation process was found to fit a pseudo-first order kinetics model. The catalyst could be easily separated from the reaction mixture by applying an external magnet. In particular, the as-prepared CoFe₂O₄/GO hybrid exhibited good reusability and stability in successive degradation experiments in PMS solution.