Amidoxime-grafted hydrothermal carbon microspheres for highly selective separation of uranium

A new amidoxime-functionalized carbonaceous sorbent has been successfully prepared using hydrothermal carbon microsphere as solid matrix and diaminomaleonitrile as precursor of amidoxime ligand. Effects of pH, sorbent dosage, contact time, temperature, initial U(VI) concentration and ionic strength on U(VI) sorption were investigated in detail through batch experiments. Sorption of U(VI) on the sorbent was pH-dependent. Sorption equilibrium was reached in 5 min. Distinctively, higher temperature was beneficial to the sorption of U(VI) in the range of 15-60 degrees C, high ionic strength up to 1 mol L(-1) NaNO3 had almost no effect on the sorption, and the maximum U(VI) sorption capacity of 466 mg g(-1) was observed under the conditions tested. The as-synthesized sorbent exhibited a high selectivity for U(VI) over other 12 competing ions coexisting in a simulated nuclear industrial effluent sample and the U(VI) sorption amount reached up to 1.09 mmol g(-1), accounting for about 52% of the total sorption amount.