Co@CoO encapsulated with N-doped carbon nanotubes activated peroxymonosulfate for efficient purification of organic wastewater

Abstract

Catalytic activation of peroxymonosulfate (PMS) for purifying organic wastewater has been widely studied. However, the activation mechanism either by free radicals or non-radicals alone is not satisfactory efficiency. In this work, a novel advanced oxidation system based on surface oxidized metallic cobalt nanoparticles (Co@CoO) encapsulated with N-doped carbon nanotubes (NCT), i.e., CCN, activated peroxymonosulfate (PMS) was designed. The CCN-PMS system showed excellent performance in the degradation for a wide range of organic pollutants, including antibiotics, dyes, and phenols. The degradation rate of 100 mL 80 mg·L-1 tetracycline hydrochloride (TC) in the system (10 mg CCN + 0.5 mM PMS) reached 92% within 30 min. The mechanism analysis of the CCN activation of PMS reveals that the NCT mainly provided the active sites for non-radical formation, while the Co@CoO mainly provided the active sites for radical formation. In addition, the NCT could not only effectively reduce the leaching of Cox+, but also play a synergistic role with Co@CoO in the degradation of organic pollutants. This work provides new insight into the mechanism of PMS activation by carbon-based catalysts for the efficient purification of organic wastewater.