Efficient activation of peroxymonosulfate by nanotubular Co3O4 for degradation of Acid Orange 7: performance and mechanism
2022
Qin, Qingdong | Yan, Lu | Liu, Zheming | Liu, Yahong | Gu, Jia | Xu, Yan
Morphology optimization of catalysts has been considered as a viable strategy to improve the catalytic efficiency for peroxymonosulfate (PMS) activation by providing high surface area and abundant active sites. In this study, nanotubular Co₃O₄ (NT-Co₃O₄) was successfully synthesized as a PMS activator for the rapid removal of acid orange 7 (AO7) in aqueous solutions. Characterization results showed that NT-Co₃O₄ presented as aggregated nanotubes, with an average pore diameter of 10 nm. The specific surface area of NT-Co₃O₄ was as high as 41.8 m² g⁻¹. Catalytic experiments demonstrated that the degradation rate of AO7 in the NT-Co₃O₄/PMS system was 15 times greater than that in commercially available Co₃O₄/PMS system. The effects of various experimental parameters, including catalyst dose, PMS dose, pH, and temperature, were comprehensively investigated. The reactive species in the NT-Co₃O₄/PMS system were identified as sulfate radical (SO₄•⁻) through both quenching tests and electron paramagnetic resonance (EPR) technology, and ≡CoOH⁺ played an important role in PMS activation. N atoms in the AO7 molecule were found to be preferentially attacked by SO₄•⁻. Moreover, the good stability and reusability of NT-Co₃O₄ were confirmed by a five-cycle AO7 removal experiment. This study provides a broader view of the potential applications of nanotubular materials to achieve highly efficient PMS activation in treating dyes in wastewater.
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