Pioneering NTA-Chelating Resin Methodology for Sequential Th(IV) Capture from Highly Acidic Media

High-level radioactive liquid waste (HLW) from nuclear fuel reprocessing poses significant challenges for selective recovery of thorium(IV) due to its trace concentration in highly acidic, irradiated, and complex matrices. In this work, we developed a novel solid-phase extraction resin by immobilizing nitrilotriacetamide (NTA amide (C8)) onto a styrene-divinylbenzene support via vacuum impregnation and characterized its morphology, surface area, and functional groups using SEM, BET, FT-IR and XPS, Brunauer-Emmett-Teller method, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Batch studies demonstrated this resin had rapid Th(IV) uptake kinetic (equilibrium ≤ 2 h) and high maximum capacities of 32.0 mg/g at 0.01 M HNO₃ and 73.3 mg/g at 7 M HNO₃, following a pseudo-second-order kinetic model and Langmuir isotherm, with excellent selectivity against 200-fold excess competing ions. The resin retained over 90% performance after exposure to 10 M HNO₃, 800 kGy β-radiation, and five acid-desorption cycles. Density functional theory calculations confirmed favorable 2:1 ligand-to-Th coordination with strong covalent character, and dynamic column tests using an automated system yielded a breakthrough volume of ∼180 mL and a dynamic capacity of 12.8 mg/g. These results highlight the resin's high capacity, robustness, and selectivity for efficient Th(IV) separation from HLW, offering a promising solution for reducing long-term radiotoxicity and enabling resource recycling in advanced nuclear waste management.