Degradation of orange II by Fe@Fe₂O₃ core shell nanomaterials assisted by NaHSO₃

Fe@Fe₂O₃ core shell nanomaterials with different Fe₂O₃ shell thickness were synthesized and the Fe@Fe₂O₃/NaHSO₃ Fenton-like system was used for the decomposition of Orange II. The consequences are compared with traditional Fenton Fe@Fe₂O₃/H₂O₂ system. The Fe@Fe₂O₃/NaHSO₃ system showed extremely good applicability under both strongly acidic and alkaline conditions. The new Fe@Fe₂O₃-(2)/NaHSO₃ system led to more than 99% degradation in 30 s when the pH was 3, which indicated that the Fe@Fe₂O₃ material was not corroded during the process even under strongly acidic condition. The above Fe@Fe₂O₃-(2) material was prepared from nano-zero-valent iron aged in solution for 2 h to synthesize the Fe₂O₃ shell. The reaction mechanism of Fe@Fe₂O₃/NaHSO₃ Fenton-like system was also concluded. The oxidation efficiency was highly improved due to rapid electron transfer between Fe core and Fe₂O₃ shell, which promoted the direct recycling of ≡Fe³⁺ and ≡Fe²⁺ and thus accelerated the generation of SO₄^- and OH radicals.