Co₃O₄/CoO ceramic catalyst: Bisulfite assisted catalytic degradation of methylene blue

Here in, a system of Co₃O₄/CoO catalyst activated with the aid of bisulfite (NaHSO₃) was established for the decomposition of methylene blue (MB). The Co₃O₄/CoO material was designed by a two-step uniform precipitation and calcination method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy to detect the crystallinity, morphology, magnetic ability, element valence and the different types of free radicals, respectively. The efficient degradation of MB relies on the synergistic effect between the Co₃O₄/CoO catalyst and bisulfite (NaHSO₃) to generate some strongly oxidizing radicals, which could achieve a MB degradation rate of 90.7% within 40 min using this novel system. Additionally, the ferromagnetic property of Co₃O₄/CoO catalyst is expected to supply an excellent magnetic separation ability to help separate the solid catalyst from the aqueous solution. The novel catalyst system of Co₃O₄/CoO/NaHSO₃ may serve as a promising new system for wastewater treatment.