Magnetic S-Functionalized Nanoporous Zr-Metal Organic Frameworks with Defect-Induced Performance in Hg(II) Removal

Defect engineering has been widely used in improving metal–organic framework (MOF) performance. Herein, magnetic nanoporous S-functionalized MOF-808 (MMOF-808-S-D) was synthesized through a large mixed-ligand defect constructing strategy with modulated synthesis. Defect was constructed due to the existence of a larger heterogeneous ligand (tetracarboxyporphyrin, TCPP), which leads to loss of connection between the metal cluster and the original ligand of MOF-808 based on the steric hindrance effect. The proportion of TCPP was optimized as 10% with little influence on crystallization of MOF-808, but more unsaturated Zr–O binding sites were exposed to connect to the S-containing modulator, which makes more S modified on the framework. MMOF-808-S-D exhibits high S content (10.6% wt.) and considerable adsorption performance for Hg(II) in terms of high adsorption capacity (350 mg g–1), fast adsorption kinetics (0.95 g mg–1 min–1), and good regeneration ability among reported magnetic framework materials. MMOF-808-S-D can be used for removing Hg(II) in different aqueous solution matrixes effectively, while the magnetism makes phase separation simple, exhibiting great potential in environmental remediations. Besides, the defect construction-involved functionalization strategy can be universally extended to other types of MOFs and improve the performance of defected MOFs in practical application.