The boosting 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 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 U(VI) by FMU-P (697.78 Vs. 367.16 mg/g 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 played 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, 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 the uranium-containing wastewater due to the high adsorption capacity, excellent chemical stability and simple magnetic separation.