Immobilizing nZVI particles on MBenes to enhance the removal of U(VI) and Cr(VI) by adsorption-reduction synergistic effect

Abstract

Herein, a novel collaborative strategy for enhancing the removal of U(VI)/Cr(VI) was developed through loading nZVI into the inter-layer structure of MBenes. Spectroscopic analysis elucidated that MBenes not only inhibited the oxidation of nZVI, but also effectively improved its reactivity. Batch experiments showed that the removal rate of targeted pollutants by nZVI@MBenes was higher than that of nZVI or MBenes due to the increment of active sites and extension of interlayer space. With the aid of kinetics and isotherms, which manifested that the adsorption data were fitted for the Langmuir and Pseudo-second-order kinetic models. Meanwhile, nZVI@MBenes afforded the largest saturated capacity of 107.8 mg/g for U(VI) and 68.6 mg/g for Cr(VI). Synergistic adsorption-reduction occurred during the elimination process based on characterizationanalysis and DFT calculation. Namely, the targeted pollutants were rapidly adsorbed by the as-prepared composites via electrostatic interaction, then the surface-associated nZVI acted as an electron donor to reduce Cr(VI) to Cr(III) and U(VI) to U(IV). Thus, this work would open a new window for the practical application of nZVI-based materials in wastewater treatment.