Peroxymonocarbonate activation via carbon nanofibers supported manganese for efficient norfloxacin degradation

Peroxymonocarbonate (PMC) activation system has been investigated for its ability to remove antibiotics due to its effectiveness, environmental friendliness and cost-effectiveness. Herein, carbon nanofibers supported with manganese (Mn/CNFs) were synthesized by an electrospinning-stabilization-carbonization method to activate PMC for efficient norfloxacin (NOR) degradation. The manganese oxide nanoparticles were distributed in the carbon nanofibers, which effectively prevented the metal leaching. The catalytic activity of the metal/CNFs for NOR removal in the PMC activation system followed: Mn/CNFs > Cu/CNFs > Co/CNFs > W/CNFs > V/CNFs, which might provide important information for PMC activation. In addition, Mn is more environmentally friendly and abundant than other metals. The Mn/CNFs exhibited higher catalytic activity for PMC activation than other peroxides (e.g., peroxymonosulfate, H₂O₂ and persulfate). The NOR degradation efficiency was 90.6 % in the Mn/CNF-activated PMC system within 60 min, and this efficiency only decreased by 3.8 % after the third cycle, indicating the good recyclability of the Mn/CNFs. The reactive species (¹O₂, CO₃^·−, O₂^·− and ·OH) were responsible for NOR removal, and ¹O₂ played the dominant role. Fourteen intermediates were identified, and three degradation pathways of NOR were proposed, including piperazine ring opening, the quinolone ring opening, decarboxylation and deethyl groups. Furthermore, 92.8 % of the NOR degradation intermediates were nonharmful according to the ecological structure–activity relationship model. This study provides important information to design efficient metal catalysts for PMC activation.