Reinforced degradation of ibuprofen with MnCo2O4/FCNTs nanocatalyst as peroxymonosulfate activator: Performance and mechanism

Abstract

In order to efficiently degrade ibuprofen (IBU) by peroxymonosulfate (PMS) activation, manganese cobalt oxide nanoparticles-decorated functionalized multi-walled carbon nanotubes (MnCo2O4/FCNTs) were prepared using a facile hydrothermal method. Comprehensive characterization of this PMS activator in multi-scale suggested that MnCo2O4 nanoparticles were uniformly decorated on FCNTs. The catalytic performance was systematical evaluated under various environmental conditions, including temperature, pH, and the presence of different common water matrix species (e.g., Cl-, HCO3-, and natural organic matter). The as-synthesized MnCo2O4/FCNTs demonstrated excellent catalytic activity with kapp ranging 0.285–0.327 min−1 under a wide pH range of 3–9 within 10 min, which achieved a complete removal of IBU and a mineralization rate higher than 90%. During oxidation process for stability and reusability test, recycled MnCo2O4/FCNTs was found durable with negligible leaching of metal ions from spent catalyst, exhibiting its high stability for PMS activation with merely slight decrease of kapp from 0.285 to 0.201 min−1 in the fourth cycle. Electron paramagnetic resonance analysis further confirmed that •OH, SO4•- and 1O2 were generated in the robust MnCo2O4/FCNTs-PMS system. Both radical and nonradical reactions were found to be responsible for the enhanced IBU degradation. Overall, this study sheds light on practical knowledge of IBU removal using MnCo2O4/FCNTs for PMS activation.