The Removal Mechanism of U(VI) on nZVI/MoS2 Composites Investigated by Batch, Spectroscopic, and Modeling Techniques

A novel nanoscale zero-valent iron/molybdenum disulfide(nZVI/MoS2) composite was synthesized and well characterizedin detail.The as-prepared materials were applied for the removal of U(VI) fromwater solutions under various experimental conditions. The characterizationsshowed that nZVI/MoS2 composites exhibited a high surfacearea and uniform distribution of nZVI. The maximum adsorption capacitiesof nZVI/MoS2 obtained from the Langmuir model (71.8 mg/gat pH 4.0 and 25 & DEG;C) were higher than that of MoS2 (39.92 mg/g) due to the synergistic effect. According to the fittingof surface complexation modeling, U(VI) removal on nZVI/MoS2 included cation exchange and inner-sphere surface complexation atlow and high pH, respectively, whereas the adsorbed U(VI) was partlyreduced into U(IV) by nZVI/MoS2 composites. According toanalysis of XPS analysis, the enhanced removal of U(VI) on nZVI/MoS2 was due to the complexation of U(VI) with various oxygenatedfunctional groups (e.g., -OH, Fe-O, and Mo-Ofunctional groups) and then adsorbed U(VI) was reduced to U(IV) byFe(0) and/or Fe(II). These findings showed that nZVI/MoS2 could be used as efficient adsorbents for the high eliminationof U(VI) from contaminated wastewater in environmental pollution cleanup.

Automated summary

A novel nanoscale zero-valent iron/molybdenum disulfide (nZVI/MoS2) composite was synthesized and applied for the removal of U(VI) from water solutions. The nZVI/MoS2 composites exhibited a high surface area, uniform distribution of nZVI, and higher adsorption capacities than MoS2 due to the synergistic effect. The removal of U(VI) on nZVI/MoS2 involved cation exchange and inner-sphere surface complexation and was enhanced by the complexation of U(VI) with various oxygenated functional groups and subsequent reduction to U(IV) by Fe(0) and/or Fe(II).