Heterogeneous activation of persulfate by carbon nanofiber supported Fe3O4@carbon composites for efficient ibuprofen degradation.

Heterogeneous catalysts for persulfate activation were synthesized using ferrocene and carbon nanofiber as precursor by one-pot hydrothermal method and their performances of catalysts for persulfate activation were evaluated via ibuprofen degradation efficiencies. The structure of the catalyst was identified as carbon encapsulated Fe3O4 grafted on carbon nanofibers (Fe3O4@C/CNFs) by multiple characterization methods. The CNF supporter could greatly reduce the magnetization of Fe3O4 and increase the coercivity, which effectively avoided agglomeration. The specific surface area of the Fe3O4@C/CNFs was determined as 65.36 m2/g. The Fe3O4@C/CNFs exhibited high catalytic performances for persulfate activation and ibuprofen could be completely removed in the system with an activation energy of 23.51 kJ/mol. The degradation efficiencies increased with the Fe loading, catalyst dosage and persulfate concentration. The catalysts also showed stable activity with minimal metal leaking over five cycles. Hydroxyl and sulfate radicals were verified by spin-trapping and scavenger experiments and principally contributed to ibuprofen degradation. The possible ibuprofen degradation pathways were elucidated based on intermediate analysis. This work would promote the applications of sulfate radical based advanced oxidation processes for the environmental remediation.