Activation of peroxymonosulfate by novel magnetically recyclable CoFe 2 O 4 /MXene quantum dots composites for rapid degradation of tetracycline: Synergistic performance and mechanisms.

Tetracycline (TC), a commonly used antibiotic in wastewater, poses environmental and health risks, thus demanding advanced catalysts for its effective removal. In this work, for the first time, we integrated cobalt ferrite (CoFe 2 O 4 ) and MXene quantum dots (MQDs) to form magnetic heterojunctions for rapid degradation of TC in the presence of peroxymonosulfate (PMS). Anchoring MQDs on the CoFe 2 O 4 nanoparticles remarkably promoted the overall degradation rate of TC to 98.2% within 20 min via both radical and non-radical pathways. The first-order kinetic constant was 0.170 min -1 , 3.5 and 15.5 times higher than that of CoFe 2 O 4 and MQDs alone, respectively. Quenching experiments revealed that the addition of p-benzoquinone (p-BQ) and furfuryl alcohol (FFA) reduced the degradation of TC within 20 min to 56.2% and 28.4%, respectively, indicating that the primary reactive oxygen species for TC degradation in the CoFe 2 O 4 /MQDs + PMS system are •O 2 - and 1 O 2 . CoFe 2 O 4 /MQDs also exhibited superparamagnetic property, which enabled their effective recovery by external magnetic field. Their reusability was verified by retaining 81.4% of catalytic efficacy in the consecutive 8th cycle. The CoFe 2 O 4 /MQDs + PMS system also exhibited excellent practicability in natural water samples as the degradation rates in both tap water and lake water environments exceeded 90%. Three potential pathways for TC degradation were proposed based on the liquid chromatography-mass spectrometry (LC-MS) characterizations and TC progressively transformed into 13 intermediates. This work may contribute to the ongoing efforts to develop advanced catalysts and strategies for mitigating the environmental impact of antibiotic pollution, offering a pathway toward sustainable and efficient water treatment technologies.