Sodium percarbonate (SPC) activation by magnetic cobalt-based catalysts for organic pollutants degradation: Performance and mechanism

Abstract

Herein, a magnetic composite material, Co-CoO@BC, was prepared by loading Co and CoO with coffee grounds as biochar support. A water purification system of Co-CoO@BC activated sodium percarbonate (SPC) was constructed to degrade acid orange 7 (AO7) rapidly. The experimental results demonstrated that Co-CoO@BC exhibited excellent performance in activating SPC to degrade AO7, achieving a degradation efficiency of nearly 95 % within 20 min. Characterization and analysis of the Co-CoO@BC were conducted to investigate its physicochemical properties. The findings indicated that introducing cobalt enhanced the defects, specific surface area, and pore volume of the catalyst, which provided more active sites for the catalytic reaction, thereby improving the degradation of AO7. Subsequently, the oxidation mechanism of radical and non-radical pathways in the Co-CoO@BC/SPC system was studied through quenching experiments, electron paramagnetic resonance (EPR), and electrochemical tests. Furthermore, this study identified the intermediates of AO7 degradation, tentatively proposed a possible degradation pathway, and assessed the biological toxicity of AO7 and its degradation intermediates. The research expands the application of transition metal-biochar composites in SPC activation and deepens the comprehension of the SPC activation mechanism.