Magnetic Co-based carbon materials derived from core-shell metal-organic frameworks for organic contaminant elimination with peroxymonosulfates.

The exploitation of highly efficient and reusable catalysts based on peroxymonosulfate (PMS) activation has attracted considerable attention in the environmental catalysis field. Herein, Co-doped graphitic carbon (Co-GC) on nitrogen-doped carbon (NC@Co-GC) was constructed and first employed as an efficient heterogeneous catalyst to activate PMS for the removal of organic contaminants. Coupled with only 0.5 mM PMS, NC@Co-GC could achieve 96.7% removal of reactive brilliant red within 14 min. Most importantly, the rate constant of NC@Co-GC was 7 times higher than that of commercial CoO. Additionally, NC@Co-GC with PMS could also exhibit high elimination rates of other dyes and organic contaminants including 8-hydroxy-quinoline, ciprofloxacin and phenol for the same condition. Benefiting from the magnetic properties, the catalyst could be separated and recycled by a magnet. Through the combination of the electron paramagnetic resonance (EPR) technology and the radical quenching experiments, it could be concluded that four types of ROS including O, SO˙, ˙OH and O˙ were involved and O played a dominant role in 3BF elimination. Interestingly, the catalytic efficiency remarkably improved and the rate constant increased by 3-fold in the presence of Cl, which always played a negative role and functioned as a ROS scavenger in a previous study. This report will inspire new studies for the development of a Co-based catalyst with both high efficiency and extraordinary reusability.