Accelerating peroxymonosulfate activation over fiber-shaped Fe@Fe₃C/CNF for ultrafast tetracyclines degradation: Active site synergy and mechanisms

The development of robust catalysts for degradation of recalcitrant pollutants via peroxymonosulfate (PMS) activation is a promising opportunity for environmental protection. Herein, novel Fe@Fe₃C/CNF nanocomposites with a fiber-shaped morphology were synthesized via electrospinning technology combined with a temperature-controlled pyrolysis process. The iron species composed of a zero-valent iron core and iron carbide shell, uniformly embedded within the matrix of carbon nanofibers. The Fe@Fe₃C/CNF composite demonstrated excellent capacity for PMS activation, along with ultrafast efficiency for the degradation of tetracycline (TC). The complete degradation of TC was achieved within a mere 21 minutes in the Fe@Fe₃C/CNF/PMS system, with a rate constant of 244.1 × 10⁻³ min⁻¹, which exceeds the performance of most transition metal catalysts reported in the literature. Moreover, the Fe@Fe₃C/CNF/PMS system showed high catalytic performance across a broad pH range, resistance to inorganic anions, and effectiveness in degrading various pollutants. Both free radicals and non-radical species were involved in the PMS activation and TC degradation process, and the mechanism of TC degradation was finally hypothesized. This research provides valuable insights for the design of robust non-noble metal catalysts for PMS activation, and broadened their potential applications for the elimination of hard-to-degrade pollutants.