Efficient enrichment of uranium(VI) on amidoximated magnetite/graphene oxide composites

Amidoximated magnetite/graphene oxide (AOMGO) composites were synthesized and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transformed infrared (FTIR) spectroscopy. The synthesized AOMGO composites were applied to adsorb uranium(VI) from aqueous solutions and could be easily separated by an external magnetic field. The kinetic process of U(VI) sorption on AOMGO composites reached equilibrium within 2 h. Effects of pH, ionic strength and coexisted ions on the sorption of U(VI) on AOMGO composites were investigated. The results indicated that U(VI) sorption on AOMGO composites was strongly dependent on pH and independent of ionic strength. The sorption isotherm agreed well with the Langmuir model, having a maximum sorption capacity of 1.197 mmol g(-1) at pH = 5.0 +/- 0.1 and T = 298 K. Thermodynamic parameters calculated from the temperature-dependent sorption isotherms suggested that the sorption of U(VI) on AOMGO composites was an endothermic and spontaneous process. The fast and efficient sorption performance suggests that AOMGO composites are potential and suitable candidates for the preconcentration and separation of U(VI) from contaminated wastewater and seawater.