Magnetic Nitrogen-Rich UiO-66 Metal-Organic Framework: An Efficient Adsorbent for Water Treatment

The postsynthetic modification of metal-organicframeworks(MOFs) has opened up a promising area to widen their water treatmentapplication. However, their polycrystalline powdery state still restrictstheir widespread industrial-scale applications. Herein, the magnetizationof UiO-66-NH2 is reported as a promising approach to facilitatethe separation of the used MOFs after water treatment. A two-steppostmodification procedure employing 2,4,6-trichloro-1,3,5-triazine(TCT) and 5-phenyl-1H-tetrazole (PTZ) agents wasintroduced to level up the adsorption performance of the magneticnanocomposite. Despite a decrement in porosity and specific surfacearea of the designed MOFs (m-UiO-66-TCT) compared to neat UiO-66-NH2, it outweighs in adsorption capacity. It was observed thatm-UiO-66-TCT has an adsorption capacity of & AP;298 mg/g for methylorange (MO) with facile MOF separation using an external magnet. Pseudo-second-orderkinetic model and Freundlich isotherm models suitably interpret theexperimental data. Thermodynamic studies showed that MO removal usingm-UiO-66-TCT is spontaneous and thermodynamically favorable at highertemperatures. The m-UiO-66-TCT composite exhibited easy separation,high adsorption capacity, and good recyclability, rendering it anattractive candidate for the adsorptive removal of MO dye from aqueousenvironments.