In this study, uniform Fe3O4 magnetic nanorings (Fe3O4-MNRs) were prepared through a simple hydrothermal method. The morphology, magnetic properties, and structure of the product were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. The Fe3O4-MNRs were used as Fenton-like catalysts in the presence of hydrogen peroxide (H2O2) and showed excellent Fenton-catalytic activity for degradation of organic dyes such as Methylene blue (MB), Rhodamine B (RhB), and Bromophenol blue (BPB). Furthermore, the obtained Fe3O4-MNRs could be recycled after used for several times and still remained in a relative high activity and could rapidly be separated from the reaction medium using a magnet without considerable loss. All results reveal that Fe3O4-MNRs have potential for the treatment of dyes pollutants.

In this work, Prussian blue (PB) coated magnetic hollow Fe3O4 nanoparticles (PB@Fe3O4NPs) were fabricated to degrade two modal dyes in wastewater via a typical peroxidation. Typically, the as-prepared PB@Fe3O4NPs were found to present intrinsic Fenton-like catalytic capacity and could catalyze the modal peroxidatic reaction for dyes degradation. Meanwhile, the obtained PB@Fe3O4NPs could be easily separated from the reaction solution by an external magnet since the magnetic Fe3O4 core for cyclic utilization. The relative removal efficiency of the PB@Fe3O4NPs was still above 80% after 10 cycles, which showing excellent recycling performance.