Efficient separation of Th(IV) from highly acidic solution by microporous resin materials containing two novel phenanthroline phosphonates

Two novel POPhen ligands functionalized macroporous resin for the highly efficient recognition of Th(IV) from molar concentrations of HNO 3 solutions was developed via a simple physical method . • Two novel adsorbents for highly efficient removal of Th(IV) were prepared by a simple but effective method. • Two adsorbents showed strong sorption ability and large adsorption capacities for Th(IV) from 4 M HNO 3 solution. • nBu-POPhen/XAD-7 had better reusability and the adsorbed Th(IV) can be completely recovered by 10 mM EDTA. • The sorption mechanism of Th(IV) was fully elucidated by AC-HAADF imaging, XPS, EXAFS analysis and DFT calculations. Seeking the cost-effective, highly efficient functional materials with simple preparation procedures have always been a goal in the field of nuclides separation. Due to the effects of protonation and stability, the recovery of actinides like Th(IV) from molar concentrations of acidic solutions for most present materials still a challenge. Herein, we have combined the recently reported phenanthroline phosphonate (POPhen) ligands holding strong selective affinity for actinides in molar concentrations of HNO 3 and the commonly used macroporous resin XAD-7 to develop two novel POPhen ligands functionalized XAD-7 composites for the highly efficient removal of Th(IV) from molar concentrations of HNO 3 solutions via a simple but effective method. The results of SEM, N 2 adsorption/desorption isotherms, FT-IR, solid state 13 C/ 31 P NMR and XPS spectra studies confirmed that two phenanthroline phosphonates nBu-POPhen ( n -butyl) and iBu-POPhen (isobutyl) were successfully loaded onto the pore structures of XAD-7 carrier through physical interactions. Both two adsorbents showed strong sorption ability, high selectivity and fast sorption rates for Th(IV) in 3–4 M HNO 3 solutions. The sorption capacities of Th(IV) by nBu-POPhen/XAD-7 and iBu-POPhen/XAD-7 (around 25 % ligand loading) were 167.5 and 161.4 mg/g respectively at 298 K in 3.0 M HNO 3 . Dynamic adsorption-stripping experiments, TOC and radiation stability studies further validated the practical application potential of the as-synthesized adsorbents. The sorption mechanism of Th(IV) was deeply elucidated by EDS-STEM, AC-HAADF imaging, XPS survey spectra, EXAFS analysis and DFT theoretical calculations.