Degradation of Orange II by Fe2O3 and CeO2 nanocomposite when assisted by NaHSO3

Fe2O3@CeO2 nanocomposites were synthesized by water bath heating method to activate NaHSO3 for Orange II dye (50 mg L−1) degradation, which reached up to 98.2% within 120 min. The Fe2O3@CeO2 and NaHSO3 dosages and the molar ratios of Ce and Fe in Fe2O3@CeO2 were investigated to obtain the optimum conditions as follows: 0.02 g Fe2O@CeO2, 0.1 g NaHSO3 and the molar ratio of Ce and Fe was 5:2 (designated as Ce-Fe-1, or simply Fe2O3@CeO2). In addition, Fe2O3@CeO2 catalyst displayed superior catalytic performance to those materials that were previously reported, as verified by the good stability (reached 90.9% after three cycles) and high degradation rate of Orange II (98.2%) of the currently developed material. Existence of ·SO4– and ·OH radicals were verified by Electron Spin Resonance Spectroscopy during degradation, and these radicals are proposed to have high degradation efficiency of Orange II. On the basis of the detected radicals, a possible degradation mechanism was proposed to provide more choices for the application of sulfite in advanced oxidation processes (AOPs).