Carbon nanofibers supported Co/Ag bimetallic nanoparticles for heterogeneous activation of peroxymonosulfate and efficient oxidation of amoxicillin

Abstract

The carbon nanofibers supported Co/Ag bimetallic nanoparticles (Co@CNFs-Ag) were synthesized for heterogeneous activation of peroxymonosulfate and efficient oxidation of amoxicillin in this work. Co nanoparticles with a diameter of 20–30 nm were encapsulated in the carbon nanofibers to reduce the loss of Co during the preparation and catalysis processes. Ag nanoparticles (5–10 nm) were distributed on the surface of CNFs. Complete removal of amoxicillin could be achieved within 30 min by Co@CNFs-Ag activated peroxymonosulfate system. The high catalytic performance could be attributed to the large aspect ratio (> 10,000) of the carbon nanofibers and the mutual reaction of the Co/Ag bimetallic nanoparticles with peroxymonosulfate. The optimal mass ratio of oxidant and catalyst was 10 and the optimized pH was 7. Co@CNFs-Ag exhibited stable catalytic activity and minimal metal leakage over a period of 5 cycles. The activation energy of the system was 29.51 kJ/mol derived by the Arrhenius equation. Both hydroxyl and sulfate radicals contributed to amoxicillin degradation and the latter were key to the degradation. Finally, the reaction mechanism of bimetallic synergistic catalytic system and possible amoxicillin degradation pathways were elucidated. The results of this study provide novel insights for application of sulfate radical-based advanced oxidation processes in environmental remediation.