Magnetic COFs as catalyst for Fenton-like degradation of sulfamethazine

A novel magnetic covalent organic frameworks (COFs) (Fe₂O₃@COFs) composite was fabricated by restricting the growth of Fe₂O₃ in the nanoscale channel of COFs, which can be used as the Fenton-like catalyst for sulfamethazine (SMT) degradation in aqueous solution. The as-prepared catalyst had good crystallinity, porosity and nano-flower-shaped morphology, and the encapsulated Fe₂O₃ particles were well-distributed and restrained in the nano-channels of COFs. Furthermore, magnetic COFs could not only adsorb SMT, but also catalyze the Fenton-like degradation of SMT in the presence of H₂O₂ (about 100% of removal efficiency). Acidic condition (pH = 3) facilitated SMT degradation in Fe₂O₃@COFs/H₂O₂. system. In consecutive 5 cycles, the catalyst showed a good stability and reusability with a high removal efficiency (>96%), a good mineralization rate (about 35%)，and a very low Fe²⁺ leaching (below 0.1 mg L^-1). Electron spin resonance (ESR) and quenching tests proved that hydroxyl radicals were the main reactive species generated in the Fe₂O₃@COFs/H₂O₂ system for the degradation of SMT. In conclusion, Fe₂O₃@COFs is a promising Fenton-like catalyst for the degradation of SMT and other toxic organic pollutants in water and wastewater.