The magnetic covalent organic framework as a platform for high-performance extraction of Cr(VI) and bisphenol a from aqueous solution

The magnetic covalent organic framework with β-ketoenamine linkage (Fe3O4@COF(TpPa-1)) was fabricated by the hydrothermal method. The obtained Fe3O4@TpPa-1 integrated four advantages, namely easy preparation, high stability, excellent adsorption performance (485.2 m2/g) and good recoverability (19.5 emu/g), which enabled it an ideal sorbent for wastewater treatment. Fe3O4@TpPa-1 exhibited excellent adsorption capacities for Cr (VI) (245.45 mg/g) and bisphenol A (1220.97 mg/g). The adsorption kinetics and isotherms were in alignment to the pseudo-second-order and Langmuir model, respectively. After five times cycles, the adsorption capacity of Fe3O4@TpPa-1 still retained at a high level. According to Materials Studio simulation and XPS analysis, the adsorption mechanism was attributed to the presence of the homogeneously distributed imine and carbonyl functional groups in the framework of TpPa-1, allowing them to serve as platforms for anchoring heavy metals and organic pollutants. Besides, the hydrophobic skeleton structures of TpPa-1 endowed them good adsorption performance towards organic pollutants via hydrogen -bonding (NH…O…HO) and π-π interaction. Therefore, the recyclable Fe3O4@TpPa-1 showed a broad application prospects in environmental remediation.