Magnetic amino-functionalized lanthanum metal-organic framework for selective phosphate removal from water

Developing a sorbent with high sorption capacity, selectivity, and ease of separation is critical in achieving ultra-low phosphate concentrations. In this study, the magnetic amino-functionalized lanthanum metal-organic framework (Fe3O4/NH2-La-MOF nanocomposite) were successfully fabricated via a solvothermal method. A variety of methods were used to characterize its morphology, porous characteristics, and magnetic property. Batch experiments were conducted to evaluate the sorption behaviors, such as pH effect, sorption kinetics, sorption isotherms, matrix effect, and regeneration. Results showed that the introduction amino groups enhanced phosphate sorption performance and the max sorption capacity was 111.22 mg P/g. Besides, this sorbent showed high selectivity towards phosphate in the presence of co-existing ions, which was due to forming the inner-sphere complex. Fe3O4/NH2-La-MOF also exhibited a favorable sorption capacity after 10 times of sorption-desorption cycles. The phosphate sorption mechanisms included ligand exchange and electrostatic attraction. This study provides a promising magnetic sorbent with high sorption capacity and selectivity for potential advanced phosphate removal applications in the future.