Facile synthesis of Fe3O4@MOF-100(Fe) magnetic microspheres for the adsorption of diclofenac sodium in aqueous solution

In this research, the adsorptive removal of diclofenac sodium, one of the representative pharmaceuticals and personal care products, from aqueous solution using Fe3O4@MOF-100(Fe) magnetic microspheres was studied for the first time. The Fe3O4@MOF-100(Fe) microspheres exhibit strong magnetism and stability, which were observed as a core-shell structure. The maximum adsorption capacity of Fe3O4@MOF-100(Fe) for diclofenac sodium can reach 377.36 mg L-1, which was higher than most of the adsorbents reported. The adsorption kinetics follows the pseudo-second-order kinetic equation. And the adsorption equilibrium of DCF can be described with Langmuir isotherm. In the cycle experiment, Fe3O4@MOF-100(Fe) material performed high adsorption efficiency for low-concentration diclofenac sodium solution, and the removal rate can still reach 80% after 5 cycles of adsorption without desorption. The mechanisms including electrostatic interaction, H-bond interaction, and pi-pi interaction that coexisted in the adsorption processes would be of benefit to enhance the adsorption capacity. The Fe3O4@MOF-100(Fe) magnetic microspheres offer exciting opportunities for further application.