One-Step mechanochemical preparation of magnetic covalent organic framework for the degradation of organic pollutants by heterogeneous and homogeneous Fenton-like synergistic reaction

• The magnetic COFs was prepared by ball milling method. • The magnetic COFs showed high superparamagnetic properties. • Fenton-like catalytic activity of magnetic COFs was higher than other catalysts. • The heterogeneous and homogeneous Fenton reaction mechanism was also explored. • It provides a new strategy for magnetic COFs prepared by ball milling method. The practical application of covalent organic frameworks (COFs) is limited because of the difficulties in rapid separation. This issue is expected to be solved with the emergence of magnetic nanoparticles. However, it remains challenging to quickly prepare magnetic COFs with high catalytic activity. In this study, a magnetic COF material (Fe 3 O 4 @TpMA) was prepared using a ball milling method based on grinding amino-functionalized magnetic nanoparticles (Fe 3 O 4 -NH 2 ) and COFs (TpMA). The -C = N bond were as a bridge between Fe 3 O 4 and COFs. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) characterizations showed that the doping of Fe 3 O 4 nanoparticles did not destroy the structure of the COFs. In addition, Fe 3 O 4 @TpMA exhibited excellent superparamagnetic properties that were conducive to the magnetic separation of pollutants and catalysts. In the Fe 3 O 4 @TpMA + H 2 O 2 system, 88.1% of methyl orange (MO) was degraded within 40 min. The degradation rate of MO in the Fe 3 O 4 @TpMA + H 2 O 2 system was 4.2, 8.0, and 11.8 times that in the Fe 3 O 4 -NH 2 + H 2 O 2 , TpMA + H 2 O 2 , and mixed material (Fe 3 O 4 -NH 2 /TpMA) + H 2 O 2 systems, respectively. Furthermore, experimental parameters such as pollutant concentration, and catalyst dosage played an important role in the degradation of MO. The Fe 3 O 4 @TpMA catalyst also achieved highly efficient degradation of MO under weakly acidic conditions (pH = 6.38). The degradation mechanism is complex, involving the heterogeneous Fenton mechanism as the main step, and the homogeneous Fenton mechanism as the auxiliary step. This study aims to provide a new strategy for the preparation of magnetic COFs via mechanical grinding.