Constructing new Fe3O4@MnOx with 3D hollow structure for efficient recovery of uranium from simulated seawater

Enrichment of uranium from seawater is a promising method for addressing the energy crisis. Current technologies are generally not effective for enriching uranium from seawater because its concentration in seawater is low. In this study, new Fe3O4@MnOx with 3D hollow structure, which is capable of enriching low concentration uranium, was prepared via a novel redox etching method. The physicochemical characteristics of Fe3O4@MnOx were studied with TEM, HRTEM, SEAD, FTIR, XRD, and N2 adsorption-desorption analysis. Dynamic kinetic studies of different initial U(VI) concentrations revealed that the pseudo-second-order model fit the sorption process better, and the sorption rates of Fe3O4@MnOx in 1, 10, and 25 mg/L U(VI) solution were 0.0124, 0.00298, and 0.000867 g/mg·min, respectively. Isothermal studies showed that the maximum sorption amounts were 50.09, 56.27, and 64.62 mg/g for 1, 10, and 25 mg/L U(VI), respectively, at pH 5.0 and 313 K, suggesting that Fe3O4@MnOx could effectively enrich low concentration U(VI) from water. The sorption amount of U(VI) did not significantly decrease in the presence of Na+, Mg2+, and Ca2+. HRTEM, FTIR, and XPS results demonstrated that Fe(II) and Mn/Fe–O–H active sites in Fe3O4@MnOx were accounted for the high and specific enrichment efficiency. A column experiment was conducted to evaluate the U(VI) sorption efficiency of Fe3O4@MnOx in simulated seawater. The U(VI) sorption efficiency remained above 80% in 28 days run. Our findings demonstrate that Fe3O4@MnOx has extraordinary potential for the enrichment of uranium from simulated seawater. [Display omitted] •Fe3O4@MnOx was constructed via a novel self-sacrifice template method.•Fe3O4@MnOx exhibited 3D hollow structure and Mn/Fe–O–H active sites.•Fe3O4@MnOx showed excellent sorption capacity for low concentration U(VI).•U(VI) was mainly enriched in the forms of UO2 and Mn/Fe-O-UO22+.•The U(VI) sorption rate remained above 80% with simulated seawater.