Convenient sorption of uranium by Amidoxime-functionalized mesoporous silica with magnetic core from aqueous solution

The use of inexpensive and biocompatible sorbents for effective removal of uranium from water environment is still an open challenge for many researchers. Herein, the magnetic amidoxime-functionalized mesoporous silica (MMS-AO) has been prepared by a combination of soft template method and co-condensation method in weak alkali oil/water phase. A feature of MMS-AO is core–shell configuration with Fe3O4 service as core, which makes the material easy to be recovered by an external magnetic field after sorption. Various characterization techniques of SEM, TEM, N2 sorption–desorption, FT-IR, TGA, Zeta potential and VSM were applied to evaluate MMS-AO. Batch sorption experiments confirmed that there were some good behavior to U(VI) removal on MMS-AO from aqueous including sorption capacity, selectivity and reusability. The experimental data fitted well to Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum sorption amount at 298 K and pH 5.50 was 236.70 mg·g−1 and the dynamic equilibrium can be reached in 90 min. The sorption process is spontaneous and endothermic via thermodynamic study. The analysis of XPS provided three insights on mechanism based on the chelation of U(VI) with amidoxime groups.