Preconcentration of Uranium(VI) from Aqueous Solution by Amidoxime‐Functionalized Microspheres Silica Material: Kinetics, Isotherm and Mechanism Study

In present study, amidoxime‐functionalized MCM‐41 microspheres silica materials (denoted as MCM‐41‐AO) were synthesized and applied to enrich uranium from aqueous mediums. The adsorbents were characterized in detail by SEM, TEM, EDS, FT‐IR, elemental analysis and the zero point of change (pHzpc) test. The effects of the pH, ionic strength, contact time, coexisting cations and temperature on the adsorption properties of U(VI) were investigated. The highest sorption capacity of U(VI) on MCM‐41‐AO was evaluated to be 384.59 mg⋅g −1 by Langmuir isotherms model at pH=5.00 ± 0.05 and T =298 ± 2 K. The adsorption thermodynamics and thermodynamic studies suggest that the U(VI) adsorbed on the amidoxime functionalized microspheres silicas is a chemisorption, spontaneous and endothermic process. In addition, the adsorption mechanism for U(VI) on MCM‐41‐AO also has been explored by the XPS and FT‐IR. The results manifest that the effective adsorption U(VI) is mainly ascribed to the steady formation of surface complexes between uranium ions and the amidoxime ligands.