Fe@Fe2O3 Core−Shell Nanowires as the Iron Reagent. 2. An Efficient and Reusable Sono-Fenton System Working at Neutral pH

In this study, we developed an efficient and reusable sono-Fenton system with Fe@Fe 2 O 3 core−shell nanowires as the iron reagent. Similar to our previous sono-Fenton system working at pH = 2, this system could also much more effectively degrade rhodamine B than those with Fe 2+, Fe 2+ /Fe 2 O 3, or commercial zerovalent iron particles as the iron reagents at neutral pH. The nature of the Fe@Fe 2 O 3 nanowire Fenton iron reagent was examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). It was found that this novel Fenton iron reagent could be recycled in this sono-Fenton system working at neutral pH. More importantly, the efficiency of this neutral-pH sono-Fenton system with adding 0.001 mol L -1 of Fe 2+ even reached 92% for degrading RhB at neutral pH. This efficiency was close to that of our previous sono-Fenton system working at pH = 2. We proposed a possible mechanism for the sono-Fenton degradation of RhB over Fe@Fe 2 O 3 core−shell nanowires at neutral pH, which involved an in situ recycling of iron species (Fe 0 → Fe n + → Fe 2 O 3 ). We believe that this economical and facile sono-Fenton system based on an Fe@Fe 2 O 3 core−shell nanowire iron reagent may be applied to practical wastewater treatment.