The boosted adsorption of uranium( vi ) on phosphorylated Fe ₃ O ₄ @MnO ₂ @UiO-66-(OH) ₂

In this study, a phosphorylated Fe₃O₄@MnO₂@UiO-66-(OH)₂ magnetic nanocomposite (FMU-P) was synthesized by a hydrothermal method and post-synthetic modification. The characterization results indicated that the adsorption performance of FMU-P could be maintained at a high level under acidic and alkaline conditions. Compared to Fe₃O₄@MnO₂@UiO-66 (FMU), the higher adsorption capacity of FMU-P for U(VI) (697.78 vs. 367.16 mg g^-1 at pH 6.0, 298.15 K) was mainly due to the stronger inner-sphere surface complexation with various phosphoryl functional groups (e.g., P-O, PO groups). According to XPS analysis, chemisorption and electrostatic interactions play an important role in U(VI) adsorption. The almost unchanged adsorption capability (>90% after five consecutive cycles) proved the excellent reusability of FMU-P. Moreover, a magnetic test indicated that adsorbed materials can be separated under an applied magnetic field, enabling the use of FMU-P across diverse environments. These findings suggest the potential of FMU-P in treating uranium-containing wastewater due to its high adsorption capacity, excellent chemical stability and simple magnetic separation.