Synthesis and characterization of a new ion-imprinted polymer for the selective separation of thorium(IV) ions at high acidity

A new ion-imprinted polymer (IIP) was synthesized by thermal copolymerization of bis(2-methacryloxyethyl) phosphate as functional ligand and ethylene glycol dimethacrylate as cross-linker in the presence of Th4+ as a template ion. The molar ratio of the functional ligand to Th4+ was optimized to be 4 by P-31 NMR titration, elemental analysis, and EXAFS, which was verified by comparing the adsorption capacities and selectivities of IIPs with different composition. Thorium(IV) ions were leached out using 0.1 mol L-1 ethylenediaminetetraacetic acid disodium salt and the prepared IIP was characterized by infra-red spectroscopy, thermogravimetric analysis and Brunauer-Emmett-Teller surface area measurement. It was found that the IIP could extract Th4+ from high acidity solution. The maximum adsorption capacity was as high as 33.3 mg g(-1) in 1.0 mol L-1 HCl. Even in 6.0 mol L-1 HCl, its adsorption capacity was still considerable. Moreover, the IIP exhibited good selectivity towards Th4+, especially in the presence of competing ions such as La3+, Eu3+, Yb3+, UO22+, and Fe3+.