Phosphonate-functionalized polystyrene microspheres with controlled zeta potential for efficient uranium sorption

Abstract

It is significant to develop new methods to capture uranium from aqueous solution for environment and human health benefits. We report here phosphonate-functionalized polystyrene microspheres with controlled zeta potentials for efficient sorption of uranium(VI) from aqueous solution. The microspheres are prepared by emulsion polymerization with diethyl-(4-vinylbenzyl) phosphonate as a comonomer and emulsifier, and the zeta potentials can be controlled with different kinds of initiators. The sorbents with high positive zeta potentials show faster rate and higher selectivity than the negative ones. The process follows a second-order kinetics model, and can reach equilibrium with a capacity of 83.4 mg U g⁻¹ in a single-element solution of uranium (200 ppm) within 200 min at pH 8.0 and 298.15 K. There are relatively larger capacities for sorbents with a high zeta potential than the neutral ones. Furthermore, the sorbents can be efficiently regenerated and reused well after five cycles. This work may provide a new approach for highly efficient sorption of uranium(VI) from aqueous solution.