Sea Urchin-like NiCoO Catalyst Activated Peroxymonosulfate for Degradation of Phenol: Performance and Mechanism.

How to efficiently activate peroxymonosulfate (PMS) in a complex water matrix to degrade organic pollutants still needs greater efforts, and cobalt-based bimetallic nanomaterials are desirable catalysts. In this paper, sea urchin-like NiCoO nanomaterials were successfully prepared and comprehensively characterized for their structural, morphological and chemical properties via techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), among others. The sea urchin-like NiCoO nanomaterials exhibited remarkable catalytic performance in activating PMS to degrade phenol. Within the NiCoO/PMS system, the removal rate of phenol (50 mg L, 250 mL) reached 100% after 45 min, with a reaction rate constant k of 0.091 min, which was 1.4-times higher than that of the monometallic compound CoO/PMS system. The outstanding catalytic activity of sea urchin-like NiCoO primarily arises from the synergistic effect between Ni and Co ions. Additionally, a comprehensive analysis of key parameters influencing the catalytic activity of the sea urchin-like NiCoO/PMS system, including reaction temperature, initial pH of solution, initial concentration, catalyst and PMS dosages and coexisting anions (HCO, Cl, NO and humic acid), was conducted. Cycling experiments show that the material has good chemical stability. Electron paramagnetic resonance (EPR) and quenching experiments verified that both radical activation (SO, OH, O) and nonradical activation (O) are present in the NiCoO/PMS system. Finally, the possible degradation pathways in the NiCoO/PMS system were proposed based on gas chromatography-mass spectrometry (GC-MS). Favorably, sea urchin-like NiCoO-activated PMS is a promising technology for environmental treatment and the remediation of phenol-induced water pollution problems.