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

Abstract

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. † Electronic supplementary information (ESI) available: Experimental details for synthesis of block copolymers and functional microspheres; sorption kinetics and thermodynamics. NMR spectra; SEM images, particle size distributions, zeta potentials for characterizations. See Scheme 1 The schematic for the synthesis of poly(ionic liquid)functionalized microspheres. This journal isFig. 4 The characterization after sorption. (A) The sorption of uranium versus time for the PSt microspheres with (a) PEI 40 , and (b) PAOBI 40 (experimental conditions: 200 mL solution, 5 Â 10 À5 mol L À1 uranyl ion, 88 mg L À1 sorbent, pH 7.00, 298.15 K). (B) The desorption of uranium by EDTA versus time for uranium-PSt microspheres with PAOBI 40 . (C) FT-IR spectra (a) before and (b) after the sorption onto PSt microspheres. (D) Zeta potential of PSt microspheres-uranium complex.This journal is

Uranium(VI) and zirconium(IV) sorption on magnetic chitosan derivatives – effect of different functional groups on separation properties

“…26,34 In the case of seawater, uranium is negatively charged (being under the form of carbonate species) which can be readily sorbed by positively charged amidoxime-functionalized polymers. 33 Wei et al 55 reported the interest of bi-functionality of polymer sorbents on the recovery of uranium from complex solutions: the presence of uranyl carbonate species may be bound by positively charged reactive groups while neutral species can be bound by chelation on amidoxime groups. The protonation of reactive groups has also been reported as a limiting step in the sorption properties of hydrazide-bearing resins.…”

Polymer sequestrants for biological and environmental applications

“…) for the sequestration of U(VI) using charged amidoxime‐containing polymers, the most widely used material for the adsorption of uranium from seawater . The mechanism of sorption was confirmed using Fourier transform infrared spectra and zeta potential: a portion of the coordination of U(VI) is due to ionic interactions between the positively charged polymer and metal ion, while the majority of adsorption occurs through coordination with the amidoxime side chains . U(VI) sorption did not appear to be effected by pH changes over the pH range 5–8, and the uptake of U(VI) increased with increasing temperature …”

“…Wei et al described the synthesis of a poly(ionic liquid) macromolecular surfactant (Fig. ) for the sequestration of U(VI) using charged amidoxime‐containing polymers, the most widely used material for the adsorption of uranium from seawater . The mechanism of sorption was confirmed using Fourier transform infrared spectra and zeta potential: a portion of the coordination of U(VI) is due to ionic interactions between the positively charged polymer and metal ion, while the majority of adsorption occurs through coordination with the amidoxime side chains .…”

Influence of solubility parameter difference between monomer and porogen on structures of poly (acrylonitrile–styrene‐divinylbenzene) resins

“…Among them, the amidoxime reaction is the use of a nucleophilic addition reaction of a cyano group and a hydroxylamine reagent to obtain a compound having an amidoxime group. These kinds of porous spherical resins could be used as the precursors of the amidoxime resin which have been adopted in the field of dissipated metal recycling …”