Microwave (MW)-assisted design of cobalt anchored 2D graphene-like carbon nanosheets (Co@GCNs) as peroxymonosulfate activator for tetracycline degradation and insight into the catalytic mechanism

Developing a rapid and cost-effective strategy to design catalysts for advanced oxidation processes (AOPs) has significant implications for environmental remediation. In this study, cobalt anchored 2D graphene-like carbon nanosheets ([email protected]) catalysts were fabricated by simple coordination of metal precursors into agarose through microwave (MW)-assisted method to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. Among them, the [email protected] exhibited excellent dispersibility and catalytic performance. The [email protected]/PMS system could completely degrade TC (20 mg L–1) within 20 min, whose reaction rate constant (0.273 min−1) was about 6.5 times that of the Co3O4/PMS system (0.0362 min−1) and 14.1 times of the GCN/PMS system (0.0194 min−1), respectively. Additionally, the degradation performance was applicable in a wide pH range (3.84–9.03) and still reached an efficiency of>90% after five cycles. Non-radical pathway represented by 1O2 served as the main contributor to TC degradation besides radicals (i.e., SO4−, OH, and O2−). Density functional theory (DFT) calculations unveiled the synergistic interaction of [email protected], where 2D GCNs as electron mediators promoted the Co3+/Co2+ cycle. Based on the LC-MS analysis, three main degradation pathways of TC including fourteen possible intermediates were proposed based on different ROS reactions. This work provides a facilely prepared and promising 2D metal-based carbonous catalyst to activate PMS for the efficient degradation of TC.