In this study, Fe@Fe 2 O 3 core-shell nanowires were first used as a novel Fenton iron reagent. The nanowires were synthesized through the reduction of ferric chloride aqueous solution by sodium borohydride at ambient atmosphere, without protection of inert gases or vacuum. Rhodamine B (RhB) could be efficiently degraded in aqueous media by a novel sonochemical-assisted Fenton (sono-Fenton) system based on these Fe@Fe 2 O 3 core-shell nanowires. The RhB degradation processes were monitored by UV-vis spectroscopy and total organic carbon (TOC) analysis. Fe@Fe 2 O 3 core-shell nanowires showed much higher activity in the sono-Fenton system than other iron reagents such as commercial zerovalent iron powders (Fe 0 ), ferrous ions (Fe 2+ ), and ferric ions (Fe 3+ ). It was found that near 100% decoloration and over 60% TOC removal of RhB (5 mg‚L -1 ) could be achieved in 60 min by this novel sono-Fenton system with 0.018 mol‚L -1 Fe@Fe 2 O 3 coreshell nanowires. This new iron reagents before and after the sono-Fenton reaction were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The characterizations found that the nanowires were transferred to nanotubes/nanoparticles covered with Fe 3 O 4 / Fe 2 O 3 after the sono-Fenton process. A possible mechanism of sono-Fenton degradation of RhB with Fe@Fe 2 O 3 nanowires was proposed on the basis of the experimental results. It involved homogeneous Fenton and heterogeneous Fenton oxidative degradation simultaneously. The high activity of core-shell Fe@Fe 2 O 3 nanowires and the success of their mass production make them attractive for the treatment of organic pollutants in water.

Fe−Fe2O3 core−shell nanowires and nanonecklaces were obtained simply through controlling the reduction rate of Fe3+ ions by sodium borohydride in aqueous solution at ambient atmosphere. The resulting materials were characterized by X-ray powder diffraction, scanning electron microscopy images and energy dispersive X-ray spectrum, transmission electron microscopy, elemental mapping, X-ray photoemission spectroscopy, and magnetization measurements. A possible formation mechanism was proposed on the basis of characterization results. It was interesting to find that the core−shell nanowires used in electrochemical-assisted and ultrasound-assisted Fenton-like reaction systems could much more efficiently degrade organic pollutant in aqueous solutions than traditional Fenton reagent Fe2+ ions under neutral pH and pH 2, respectively. This study indicates that the resulting iron-containing nanostructures are promising materials in magnetic, environmental, and catalytic fields.