Ultrafast kinetics and efficient PMS activation using a 2D calcined Co-MOF nanoconfined catalytic membrane for continuous tetracycline degradation

Tetracycline has drawn extensive attention owing to its widespread application, carcinogenic risk, and strong ecotoxicity. Nanoconfined catalytic membranes (CM) are promising for tetracycline degradation due to their excellent catalytic activity, while the excessive consumption and low utilization of oxidants remain an overlooked issue. This study developed a novel 2D calcined Co-MOF (Co-NC) based nanoconfined CM (Co-NC-CM) for highly efficient peroxymonosulfate (PMS) activation for continuous tetracycline degradation, by extremely low dose of PMS. The Co-NC-CM exhibited ultrafast degradation kinetics of tetracycline with a k obs value of 2314 min −1 , 8507-fold that of Co-NC alone. Regarding PMS utilization, the continuous degradation process displayed two distinct stages: an activation stage and a stable stage. Strikingly, only 0.09 mM PMS (30% of original PMS) input in the stable stage (recorded as low dose treatment, LDT) still achieved 100% degradation, reducing PMS usage by 70% and increasing PMS utilization to 95%. Mechanistically, benefiting from the PMS enrichment effect, the Co-NC-CM in LDT system retained 94% of Co(IV)=O yield and around 100% of surface-bound radicals production capacity obtained with original PMS input. Importantly, the LDT system exhibited an ultrahigher k obs value of 3083 min −1 owing to directly effective collisions between tetracycline and actives sites. This system achieved complete tetracycline degradation in actual aquaculture wastewater. These results demonstrate that the newly developed catalytic material enables a substantial reduction in PMS dose while maintaining ultrahigh degradation performance.