Elimination mechanisms of U(VI) and Se(IV) by MBenes supported Fe3S4 micro-crystal: Synergy of adsorption, reduction and transformation

Herein, a MBene based composite (Fe3S4@MBenes) was constructed by loading Fe3S4 on MBenes via an in-situ growth method and investigated for elimination of U(VI) and Se(IV). Advanced characterization technology and batch experiments were used to explore the structure-activity relationship between the structure and performance. Results showed that the addition of MBenes could not only restrain the aggregation of Fe3S4, but also could enhance the antioxidant ability of Fe3S4. Meanwhile, the presence of humic acid significantly decreased the removal of U(VI)/Se(IV), while a high ionic strength generally did not impact their adsorption. Kinetic and isotherm studies showed that adsorption of U(VI)/Se(IV) was a chemical rate-limiting process and conformed to the Langmuir isothermal model, and the maximum adsorption amounts of U(VI)/Se(IV) were 160.9 and 143.3 mg/g, respectively. Characterization analysis and DFT calculation revealed that U(VI)/Se(IV) were removed on the adsorbents through synergistic adsorption-reduction effect, in which U(VI) was reduced to U(IV) and Se(IV) was converted into Se(0). The findings presented herein revealed that Fe3S4@MBenes was a feasible radionuclides removal method for the practical remediation.