•Special Fe3O4/CD nanocomposite was prepared by low-temperature plasma technique.•Fe3O4/CD nanocomposite showed favorable adsorption efficiency towards Ni(II) ions.•Fe3O4/CD nanocomposite can be easily separated using an external magnet.•Fe3O4/CD nanocomposite can be repeatedly applied in cost-effective disposal of Ni(II)-bearing wastewater.Herein, β-cyclodextrin (β-CD) was conjugated on the surfaces of Fe3O4 particles to synthesize magnetic Fe3O4/CD nanocomposite using a novel low temperature plasma technique. The Fe3O4/CD samples were applied in the removal of radionuclides and heavy metal ions contaminations from aqueous solutions. The synthesized Fe3O4/CD nanocomposite which showed high saturation magnetization could be likely separated by using an external magnet. The adsorption performance and underlying mechanism of Fe3O4/CD nanocomposite toward nickel ions were studied using batch technique. The adsorption kinetic of nickel ions on Fe3O4/CD surfaces could be obtained within the time period of 8 h. The surface conjugated CD can obviously improve adsorption performance towards Ni(II) ions. The Fe3O4/CD samples show propitious adsorption property toward Ni(II) ions from wastewater. The experimental findings showed that Fe3O4/CD nanocomposite could be used as a highly effective adsorbent for the removal of Ni(II) ions from large volumes of aqueous solution.Download high-res image (135KB)Download full-size image

•The inner-sphere surface complexes dominated U(VI) adsorption at low pH values.•Strong inner-sphere surface complexes and co-precipitation dominated U(VI) adsorption at high pH values.•MRGO composites showed favorable adsorption efficiency towards U(VI) ions.•MRGO composites can be easily separated using an external magnet.•MRGO composites can be repeatedly applied in the removal of actual U(VI)-bearing wastewaters.Comprehension the extent and rate of U(VI) adsorption on some mineral surfaces are significant to predict their migration and transformation properties in the environmental systems. Herein, iron oxides particles supported reduced graphene oxide composites (MRGO) were successfully synthesized by in-situ chemical precipitation approach. The MRGO composites which illustrated high saturation magnetization could be likely separated using an external magnet. The experimental data illustrated that U(VI) ions could be interacted with MRGO composites through different interaction mechanisms depending on different environmental conditions. The adsorption kinetic results can be well simulated using the pseudo-second-order pattern. The pH-dependent adsorption behavior illustrated an favorable pH value of 7.5 for removal of U(VI) ions using MRGO composites. Furthermore, the adsorption regeneration of MRGO composites in simulated wastewater disposal systems was tested. Based on above mentioned, it was clear that MRGO composites could be potentially used as adsorbent for removal of actual U(VI)-bearing wastewaters.

Nine optimized conformers of 2,4-dinitroimidazole with methanol have been obtained at B3LYP/6-31++G(2d,p) level. The intermolecular interaction energies are predicted by using MP2/6-31++G(2d,p), B3LYP/6-31++G(2d,p) and B3LYP/aug-cc-pVTZ methods with basis set superposition error (BSSE) and zero-point energy (ZPE) correction, and natural bonding analysis has also been carried out. The four main types of hydrogen bonds, which are N–H⋯O, C–H⋯O, O–H⋯O and O–H⋯π, are investigated. The results indicate that only two of the conformers are the stable ones with the intermolecular interaction energies of 42.39 and 26.27 kJ/mol at B3LYP/aug-cc-pVTZ level, respectively. For these two conformers, the N–H⋯O or C–H⋯O hydrogen bonding interaction is dominant and the hydroxyl oxygen offers lone pairs to the contacting σ(N–H)* or σ(C–H)* antibond orbital of 2,4-dinitroimidazole and electrons transfer from methanol to 2,4-dinitroimidazole, while for the other conformers, the O–H⋯O or O–H⋯π hydrogen bonding interaction is dominant and the nitro oxygen offers p electrons or imidazole ring offers part of the π electrons to the σ(O–H)* antibond orbital and the electrons transfer reversely. Intermolecular binding interaction between the nitro oxygen and hydroxylic hydrogen is relatively weak, as is in accordance with the literature.