Phosphate-based Ce(IV) Ion-Imprinted Polymers for Separation of Berkelium: Testing the Homologue Imprinting Approach for Heavy Actinides

Abstract

The present study focuses on the synthesis of phosphate-based ion imprinted polymers (IIPs) using a chemical homologue (cerium­(IV)) for the fast and selective separation of Bk­(IV) from a large number of fission products. Two imprinted phosphate-based gels, poly­(bis­[2-(methacryloyloxy)­ethyl] phosphate) (poly-BMEP) and poly­(bis­[2-(methacryloyloxy)­ethyl] phosphate-co-acrylic acid) (poly-(BMEP-AA)) have been prepared by in situ UV polymerization. The imprinting has been achieved by complexation of the phosphate-based monomers with the Ce­(IV) ion. The desorption of Ce­(IV) ions from the imprinted gels has been studied with H2O2. The prepared gels have been characterized by FE-SEM, FT-IR, XRD, and XPS. The imprinted gels have been shown to extract Ce­(IV) ions selectively from an 8 mol L–1 HNO3 medium in the presence of fission products (Ba, Ru, Tb). DFT calculations show formation of a 1:4 Ce­(IV):BMEP complex. The presence of acrylic acid (AA) has been shown to improve the kinetics of Ce­(IV) uptake owing to the decrease in the tortuosity of the polymeric structure due to the AA presence. The imprinted gels though do not show kinetic selectivity toward Ce­(IV) compared to non-imprinted gels; they show thermodynamic selectivity toward Ce­(IV), indicating the inability of the non-imprinted gels to retain Ce­(IV) for longer periods. Also, the imprinted gels have been found to be more selective compared to solvent extraction with BMEP as the complexing agent. These two imprinted gels were used to extract Bk, which was produced in 11B + 238U at a 66 MeV beam energy. The extraction by IIPs have been found to be much faster with the reduction in overall extraction time by ∼80% relative to the earlier reported method though with a lesser selectivity for some elements. The present approach, as guided by DFT calculations, offers a possibility of preparing IIPs for the selective extraction of heavy actinides and trans-actinides using their chemical homologues as the imprinting ion.

Synthesis of Ion Imprinted Polymers (IIPs) Adsorbent Materials Using Fe(III) Leaching Process with Variation of Hydrochloric Acid Solvent Concentration and Heat Treatment

“…In addition, IIPs find applications as both adsorbents and electrochemical sensors, making them functional components with high selectivity, relatively low cost, and efficient processing time (Sala et al, 2022) . This has led to the widespread development of these materials by several studies to eliminate or adsorb various heavy metals in water, such as Al(III), Be(II), Ce(IV), Ni(II), As(III), Ru(III), Cr(VI), Cd(II), Cu(II), Co(II), Hg(II), Pb(II) (Ahmadi et al, 2021;Cao et al, 2021;Chi et al, 2021;Kong et al, 2021;Mhatre et al, 2021;Rais et al, 2021;Taheri et al, 2021;Wang et al, 2022;Zhang et al, 2021;Zhao et al, 2022) including Fe(III) metal ions (Mitreva et al, 2017) .…”