Facile fabrication of mesoporous carbon-anchored cobalt ferrite nanoparticles as a heterogeneous activator of peroxymonosulfate for efficient degradation of Congo red

Herein, mesoporous carbon-anchored cobalt ferrite nanocomposites (nano-CoFe2O4@MC) were fabricated using a hydrothermal method for application as heterogeneous catalysts to activate peroxymonosulfate (PMS), in order to solve the problems of low activation performance and secondary pollution caused by the inter-particle agglomeration, metal ion leaching, and difficult recovery of nano metal catalysts. Analysis techniques such as SEM, TEM, XRD, BET, FTIR, VSM, TGA, and Raman spectroscopy indicated that the prepared nanocomposites have excellent surface properties, structural stability, and magnetic properties. The performance of nano-CoFe2O4@MC for Congo red (CR) degradation was evaluated by comparison with other treatment systems and study of the influence of experimental parameters, including the anchoring ratios, catalyst dosage, PMS concentration, initial pH, CR concentration, coexisting anions, and humic acid. Both radical and nonradical pathways were observed in the activation process of PMS by nano-CoFe2O4@MC. The analysis results of the element composition and ionic state of the catalyst show that the redox cycle of two ion pairs, Co3+/Co2+ and Fe2+/Fe3+, could enhance the multipath electron transfer on the catalyst surface to promote the generation of reactive oxygen species. Identification of the intermediate products revealed CR was transformed into 12 intermediates through two branch pathways in the nano-CoFe2O4@MC/PMS system. After five cycles of use, the catalytic efficiency of the catalyst did not decrease significantly. Nanocomposites with high catalytic performance, stability, recyclability, and a low ion leaching rate have broad application prospects in the treatment of antibiotic wastewater.

Automated summary

Mesoporous carbon-anchored cobalt ferrite nanocomposites (nano-CoFe2O4@MC) were prepared via hydrothermal method as heterogeneous catalysts to activate peroxymonosulfate (PMS) for the treatment of antibiotic wastewater. The nanocomposites exhibited excellent surface properties, structural stability, and magnetic properties. The activation process of PMS by nano-CoFe2O4@MC involved both radical and nonradical pathways, and the redox cycle of Co3+/Co2+ and Fe2+/Fe3+ was found to enhance multipath electron transfer for reactive oxygen species generation. The catalytic efficiency of nano-CoFe2O4@MC remained high after five cycles of use.