Cobalt Oxides Grown In-Situ on Carbon Nitride Nanosheets for Efficient Peroxymonosulfate Activation and Organic Contaminants Degradation: Performance, Mechanism, and Application Study

Abstract

Heterogeneous peroxymonosulfate (PMS) activation processes are considered promising Fenton-like oxidation technologies, and the design of heterogeneous catalysts is key to enhancing their practical applicability. In this study, a catalyst consisting of cobalt oxides grown in situ on carbon nitride nanosheets (CoOx-CN) was designed for PMS activation and the degradation of emerging organic pollutants. The unique structure of CoOx-CN enriched its specific surface area and the exposure of reactive sites, while the CN substrate's influence on CoOx nucleation promoted the formation of sub-valent CoO crystal planes and oxygen vacancies (OV). As a result, the CoOx-CN/PMS system demonstrated efficient tetracycline removal efficiency, reaching 99.4% within 21 min, with a specific catalytic kinetic constant (Kspecific) reaching 0.016 L·min-1m-2. Mechanistic studies indicated efficient generation of reactive species and degradation of organic pollutants induced by the strong interaction between CoOx-CN and PMS. Based on theoretical calculations, intermediate identification, and toxicity analysis, a degradation pathway and toxicity evolution for tetracycline were proposed. Additionally, the application of CoOx-CN in a membrane system and its performance in treating natural water bodies confirmed its potential for real-scale applications. This work provides a reference for the design of Fenton-like catalysts and their application in actual wastewater treatment scenarios.

Keywords: Peroxymonosulfate activation, Emerging organic pollutants, Cobalt oxides, Carbon nitride nanosheets, Membrane system