The boosted adsorption of uranium(vi) on phosphorylated Fe3O4@MnO2@UiO-66-(OH)2

Abstract

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, PO 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.