Synergistic Removal of U (VI), Pb(II), and HA on nZVI/MoS₂ Composites Investigated by Batch, Spectroscopic, and Modeling Techniques

The simultaneous adsorption of U(VI), Pb(II), and humic acid (HA) in water solutions on a nanoscale zerovalent iron/molybdenum disulfide (nZVI/MoS2) composite was investigated using batch, spectroscopic, and modeling techniques. An increased removal of U(VI) and Pb(II) and a gradual decrease in HA removal on nZVI/MoS2 was observed with increasing pH from 2.0 to 7.0. The adsorption capacities of U(VI), Pb(II), and HA under ternary systems were 57.72, 40.43, and 55.43 mg/g (298 K, pH 4.0), respectively. In addition, nZVI/MoS2 exhibited good regeneration due to the high surface area and uniform distribution of nZVI. The interaction mechanism was demonstrated to be inner-sphere surface complexation by XPS analysis and surface complexation modeling (SCM). The presence of Pb(II) and HA inhibited U(VI) reduction into U(IV) by nZVI according to XPS analysis; meanwhile, two inner-sphere complexation reactions (weak and strong sites) rather than redox reactions were demonstrated by SCM. These findings showed that nZVI/MoS2 could be used as an efficient adsorbent for the high elimination of radionuclides, heavy metals, and organics in actual compound pollution of wastewater.