Electrostatic self-assembly of nanoscale FeS onto MXenes with enhanced reductive immobilization capability for U(VI) and Cr(VI)

Herein, a MXenes decorated nanoscale FeS composites were developed via electrostatic self-assembly strategy to achieve efficient U(VI)/Cr(VI) adsorption-reduction. Different analytical techniques were applied to adequately characterize all as-prepared materials to determine the formation of species with the desired morphology and properties. Results revealed that the special chemical structure of MXenes could improve the dispersion of FeS nano-particles and suppress its aggregation. Meanwhile, the adsorption data closely well tailored with the Langmuir isotherm and Pseudo-second-order equation, and the maximum removal efficiencies were 88.5 and 107.2 mg/g for uranium(VI) and chromium(VI). It was also found that the presence of other cations and anions had no obvious influence on removal of U(VI)/Cr(VI), whereas the elimination process was a spontaneous endothermic reaction. More importantly, according to the spectroscopic analysis and DFT calculation, both FeS and surface functional groups on Ti3C2@FeS-PDA/PEI exhibited strong chemical affinities to the targeted pol-lutants, while FeS could effectively reduce Uranium(VI) to Uranium(IV) and Chromium(VI) to Chromium(III). This work facilitated the omnidirectional improvement of MXenes-based materials for the de-pollution of practical radionuclide or heavy metals wastewater.

Automated summary

MXenes-decorated nanoscale FeS composites were prepared via electrostatic self-assembly strategy for efficient U(VI)/Cr(VI) adsorption-reduction. Different analytical techniques characterized the materials and confirmed the desired morphology and properties. MXenes improved the dispersion of FeS nano-particles and suppressed aggregation. The adsorption data followed the Langmuir isotherm and Pseudo-second-order equation, with maximum removal efficiencies of 88.5 and 107.2 mg/g for uranium(VI) and chromium(VI). The presence of other cations and anions had no significant influence on U(VI)/Cr(VI) removal, and the elimination process was spontaneous and endothermic. The work demonstrated the potential of MXenes-based materials for wastewater decontamination.