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 characterized in detail. The as-prepared materials were applied for the removal of U(VI) from water solutions under various experimental conditions. The characterizations showed that nZVI/MoS2 composites exhibited a high surface area and uniform distribution of nZVI. The maximum adsorption capacities of nZVI/MoS2 obtained from the Langmuir model (71.8 mg/g at pH 4.0 and 25 °C) were higher than that of MoS2 (39.92 mg/g) due to the synergistic effect. According to the fitting of surface complexation modeling, U(VI) removal on nZVI/MoS2 included cation exchange and inner-sphere surface complexation at low and high pH, respectively, whereas the adsorbed U(VI) was partly reduced into U(IV) by nZVI/MoS2 composites. According to analysis of XPS analysis, the enhanced removal of U(VI) on nZVI/MoS2 was due to the complexation of U(VI) with various oxygenated functional groups (e.g., −OH, Fe–O, and Mo–O functional groups) and then adsorbed U(VI) was reduced to U(IV) by Fe0 and/or Fe(II). These findings showed that nZVI/MoS2 could be used as efficient adsorbents for the high elimination of U(VI) from contaminated wastewater in environmental pollution cleanup.