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• The magnetic Fe 3 O 4 @NH 2 -La-MOF were synthesized for selective phosphate removal. • The introduction of amino groups enhanced the sorption capacity of phosphate. • The incorporated Fe 3 O 4 particles favored easy separation after phosphate sorption. • Fe 3 O 4 @NH 2 -La-MOF showed good performance in sorption selectivity and regeneration. • The sorption mechanisms included ligand exchange and electrostatic attraction. 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 (Fe 3 O 4 /NH 2 -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. Fe 3 O 4 /NH 2 -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. [ABSTRACT FROM AUTHOR]

Finding a good sorbent for phosphorus (P) recovery from the aquatic environment is critical for preventing eutrophication and providing P resources. The activated iron system (mainly consisted of zero-valent iron (ZVI), Fe 3 O 4 and Fe 2+ ) has been reported to exhibit a favorable performance towards various contaminants in wastewater, but its effect on P recovery has not been studied systematically. In this study, we used Fe 2+ -nitrate pretreatment reaction to prepare the activated iron system and then applied it to P recovery. Results show that more than 99% P was removed from water in 60 min; co-existing anions (NO 3 − , Cl − and SO 4 2− ) and natural organic matter (NOM) had little effect on P removal. The P removal capacity of activated iron system is very high compared with currently reported sorbents. Externally-supplied Fe 2+ plays an important role on P removal in the system. Regeneration study shows that the activated iron system exhibited stable P recovery ability by using 0.1 M NaOH solution. Various methods were applied to characterize the ZVI and iron corrosion, and results conclude that sorption precipitation, and co-precipitation contribute to P removal. This method will be promising and have an application potential in the field for efficient and cost-effective recovery of P with cheap microscale zero valent iron. [ABSTRACT FROM AUTHOR]