Conversion of nylon-6 into nitrogen-doped graphitized nanodiamonds for efficient persulfate activation and enrofloxacin degradation

초록

Nitrogen-doped nanodiamond (N-ND) composites were synthesized via co-pyrolysis of Nylon-6 and nanodiamond as a dual-functional strategy for plastic waste valorization and metal-free catalyst fabrication. Thermogravimetric analysis revealed a synergistic thermal interaction, evidenced by a negative shift in decomposition temperature and enhanced generation of energy-carrying gaseous products (H2 and CH4). Comprehensive characterization confirmed the successful incorporation of pyridinic, pyrrolic, and graphitic nitrogen functionalities into the composite, which collectively contributed to improved graphitic ordering, a high specific surface area (263.2 m2 g−1), and a well-developed mesoporous architecture. The N-ND composite demonstrated superior persulfate (PS) activation for enrofloxacin degradation, achieving a pseudo-first-order rate constant of 0.215 min−1 at pH 7. Radical quenching identified SO4•− and •OH as the dominant reactive oxygen species, with additional contribution from 1O2 through non-radical pathways. Electrochemical analysis further confirmed enhanced interfacial electron transfer, as evidenced by a 0.42 V anodic shift observed upon PS injection. The composite also exhibited robust operational stability, maintaining excellent degradation performance across multiple consecutive reaction cycles. Collectively, these findings establish co-pyrolysis of plastic waste with nanodiamond as a sustainable and energy-efficient platform coupling waste valorization with scalable production of high-performance catalytic materials, offering promising applicability within circular economy frameworks.

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