Fe-Substituted Isoreticular Metal–Organic Framework for Efficient and Rapid Removal of Phosphate

Excessive phosphate can cause water eutrophication. Adsorption can remove excessive phosphate in water to alleviate eutrophication effectively. Herein, an isoreticular metal–organic framework (Fe-IRMOF-3-10) with bimetallic center and double ligand was successfully synthesized from a single metal center and single ligand isoreticular metal–organic framework (IRMOF-3) to remove phosphate in water effectively. In the four IRMOFs, Fe-IRMOF-3-10 shows higher adsorption capacity (177.0 mg g–1 at 25 °C) and faster adsorption kinetics (5 min) for phosphate. The adsorption capacity and removal efficiency remain stable in the range of pH 4–11. The adsorption capacity of Fe-IRMOF-3-10 for phosphate is not only not affected by a large number of coexisting anions (Cl–, F–, NO3–, and SO42–) but also not affected by the ionic strength. The adsorption mechanism study illustrated that the removal of phosphate by Fe-IRMOF-3-10 not only included the affinity of amine group and Fe3+ for phosphate but also involved the ion exchange between hydroxyl group and phosphate. The adsorption efficiency of Fe-IRMOF-3-10 for phosphate from actual water samples indicated the potential of Fe-IRMOF-3-10 for the removal of phosphate from natural water samples.