Enhanced uranium removal from aqueous solution by core–shell Fe0@Fe3O4: Insight into the synergistic effect of Fe0 and Fe3O4

In this study, Fe 0 @Fe 3 O 4 was synthesized and used to remove U(VI) from groundwater. Different experimental conditions and cycling experiments were used to investigate the performance of Fe 0 @Fe 3 O 4 in the U(VI) removal, and the XRD, TEM, XPS and XANES techniques were employed to characterize the Fe 0 @Fe 3 O 4 . The results showed that the U(VI) removal efficiency of Fe 0 @Fe 3 O 4 was 48.5 mg/g that was higher than the sum of removal efficiency of Fe 0 and Fe 3 O 4 . The uranium on the surface of Fe 0 @Fe 3 O 4 mainly existed as U(IV), followed by U(VI) and U(V). The Fe 0 content decreased after reaction, while the Fe 3 O 4 content increased. Based on the results of experiments and characterization, the enhanced removal efficiency of Fe 0 @Fe 3 O 4 was attributed to the synergistic effect of Fe 0 and Fe 3 O 4 in which Fe 3 O 4 accelerated the Fe 0 corrosion that promoted the progressively formation of Fe(II) that promoted the reduction of adsorbed U(VI) to U(IV) and incorporated U(VI) to U(V). The performance of Fe 0 @Fe 3 O 4 at near-neutrality condition was better than at acidic and alkalic conditions. The chloride ions, sulfate ions and nitrate ions showed minor effect on the Fe 0 @Fe 3 O 4 performance, while carbonate ions exhibited significant inhibition. The metal cations showed different effect on the Fe 0 @Fe 3 O 4 performance. The removal efficiency of Fe 0 @Fe 3 O 4 decreased with the number of cycling experiment. Ionizing radiation could regenerate the used Fe 0 @Fe 3 O 4 . This study provides insight into the U(VI) removal by Fe 0 @Fe 3 O 4 in aqueous solution.