Upcycling waste plastics into FeNi@CNTs chainmail catalysts for effective degradation of norfloxacin: The synergy between metal core and CNTs shell

Upcycling waste plastics into valuable products for eliminating hazardous contaminants in aquatic matrixes represents an attractive approach to addressing the urgent environmental crisis. Herein, the magnetic FeNi@CNTs chainmail catalysts were successfully fabricated from waste plastics via catalytic pyrolysis and employed for peroxymonosulfate (PMS) activation to efficiently degrade norfloxacin (NOR) during the advanced oxidation process. Results revealed that the amount of metal loading played a critical role in the physicochemical properties and catalytic activities of FeNi@CNTs. The optimal NOR removal efficiency (100%) was achieved via FeNi30@CNTs with moderate metal content, which was attributed to the synergy between metal core and CNTs shell. Fe-Ni alloy not only catalyzed the growth of CNTs, but also activated PMS to generate more reactive oxygen species. Furthermore, CNTs acted as quick electron transfer routes to speed up the catalytic reactions and protected the metal core from agglomeration. However, excess metal led to the agglomeration of particles outside CNTs, thus inhibiting NOR degradation. Moreover, FeNi30@CNTs exhibited good stability and reusability during the cyclic experiments. The possible mechanism was deeply discussed by quenching experiments, EPR, XPS, and LC-MS characterizations. This study provides a novel route of waste-to-waste remediation, making FeNi@CNTs an inexpensive and sustainable candidate in antibiotic degradation, and simultaneously opens up a new perspective to alleviate the environmental problems caused by waste plastics.