Synthesis of invasive plant biochar catalyst with carbon nitride structure for peroxymonosulfate activation toward efficient ciprofloxacin degradation

Abstract In this work, an invasive plant (Aster subulatus Michx) mesopore laminar biochar loaded with transition metal Co (CoS@MLBC) was synthesized by a one-step hydrothermal carbonization way for activating peroxymonosulfate (PMS) to remove antibiotics in water. We characterized the structure and morphology of CoS@MLBC and tested its performance. The results showed that the carbon nitride structure was formed on CoS@MLBC, which improved its adsorption capacity for antibiotics and PMS. In addition, Co-doping significantly enhanced the PMS activity and efficiently degraded ciprofloxacin (CIP) over a wide pH range. It was identified that radical and non-radical synergistic action had a critical effect on the CIP degradation process. Furthermore, CoS@MLBC could completely remove CIP within 10 min and had a high removal efficiency (98%) after four cycles. Three possible pathways of the CIP degradation process with 12 intermediates were proposed and their ecotoxicity was analyzed. This work provides a new perspective for preparing biochar from invasive plants for the degradation of antibiotics in water, realizing the concept of “treating the wastes with wastes”. Graphical Abstract