Bifunctional polymeric microspheres for efficient uranium sorption from aqueous solution: synergistic interaction of positive charge and amidoxime group

It is of strategic and ecological importance to capture uranium(VI) from aqueous solutions. A novel strategy is reported herein to synthesize bifunctional polymeric microspheres for efficient uranium removal from aqueous solution. Specifically, positively charged microspheres with amidoxime groups were prepared by emulsion polymerization. The high selectivity and fast kinetics for uranium(VI) can be achieved by the microspheres via the synergistic interaction of positive charge and coordinating ligand. The negative uranium tricarbonate complex would be adsorbed to the positively charged microspheres by coulombic interaction without interference of other metal cations, and the coordination may occur with amidoxime groups via ligand exchange. It is calculated that nearly 36% of the adsorbed uranium(VI) is due to coulombic interactions of the positive charge while 64% is due to coordination of amidoxime groups. To the best of our knowledge, this is the first report on colloidal particles with positive charges and ligand groups for uranium(VI) uptake from aqueous solution.