Magnetic COFs for the adsorptive removal of diclofenac and sulfamethazine from aqueous solution: Adsorption kinetics, isotherms study and DFT calculation

Covalent organic frameworks (COFs) are emerging and promising adsorbents for the adsorptive removal of many types of pollutants. However, most COFs fabricated by various methods are in the form of microcrystalline powders, making them difficult in separation. In this study, magnetic COFs were prepared by a simple impregnation method. The as-prepared samples with Ms = 5.2 emu g-1 showed a good magnetic separation capability. Additionally, the adsorption performance of magnetic COFs towards antibiotics (e.g., diclofenac and sulfamethazine) was also studied. Various adsorption kinetic models (e.g., the pseudo first-order, the pseudo second-order, and mixed-order models) and adsorption isotherm models (e.g., the Freundlich, the Langmuir, and the Sips models) were used to study their adsorption kinetics and isotherms. Furthermore, density functional theory (DFT) was utilized to predict the interaction between adsorbents and adsorbates and to explain the partial adsorption mechanisms.