Herein, we report the preparation of magnetic CoFe 2 O 4 nanoparticles and CoFe 2 O 4 /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 CoFe 2 O 4 nanoparticles and CoFe 2 O 4 /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 CoFe 2 O 4 /GO hybrids exhibited much better catalytic activity than CoFe 2 O 4 nanoparticles or CoFe 2 O 4 /reduced graphene oxide (rGO) hybrids, suggesting that GO plays an important role in CoFe 2 O 4 /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 CoFe 2 O 4 /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 CoFe 2 O 4 /GO hybrid exhibited good reusability and stability in successive degradation experiments in PMS solution.

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