In order to realize the effective separation of palladium from high-level liquid waste (HLLW), a ligand-supported adsorbent (NTAamide(C8)/SiO₂-P) was prepared by the impregnation method in a vacuum. The SiO₂-P carrier was synthesized by in situ polymerization of divinylbenzene and styrene monomers on a macroporous silica skeleton. The NTAamide(C8)/SiO₂-P adsorbent was fabricated by impregnating an NTAamide(C8) ligand into the pore of a SiO₂-P carrier under a vacuum condition. The adsorption performance of NTAamide(C8)/SiO₂-P in nitric acid medium has been systematically studied. In a solution of 0.2 M HNO₃, the distribution coefficient of Pd on NTAamide(C8)/SiO₂-P was 1848 mL/g with an adsorption percentage of 90.24%. With the concentration of nitric acid increasing, the adsorption capacity of NTAamide(C8)/SiO₂-P decreases. Compared to the other 10 potential interfering ions in fission products, NTAamide(C8)/SiO₂-P exhibited excellent adsorption selectivity for Pd(II). The separation factor (SF_{Pd/other metals} > 77.8) is significantly higher than that of similar materials. The interference of NaNO₃ had a negligible effect on the adsorption performance of NTAamide(C8)/SiO₂-P, which maintained above 90%. The adsorption kinetics of Pd(II) adsorption on NTAamide(C8)/SiO₂-P fits well with the pseudo-second order model. The Sips model is more suitable than the Langmuir and Freundlich model for describing the adsorption behavior. Thermodynamic analysis showed that the adsorption of Pd(II) on NTAamide(C8)/SiO₂-P was a spontaneous, endothermic, and rapid process. NTAamide(C8)/SiO₂-P also demonstrated good reusability and economic feasibility.

The PUREX process is a key technology for spent fuel reprocessing, designed to selectively recover uranium and plutonium mainly through multiple chemical separation stages, minimizing high-level waste. Acetohydroxamic acid (AHA) enhances selectivity in this process but decomposes into acetic acid (HAc), which disrupts chemical equilibrium and reduces extraction efficiency. This study examines the extraction and separation of nitric acid (HNO₃) and HAc using 30% tributyl phosphate in organic kerosene (TBP-OK) under various conditions. Results show that 30%TBP-OK preferentially extracts HAc over HNO₃, especially in the low acid concentration range (HNO₃ < 1 mol/L, HAc < 0.2 mol/L). The selectivity coefficient drops from 3.05 in a 0.5 mol/L HNO₃-0.1 mol/L HAc system to 2.18 in a 1 mol/L HNO₃-0.2 mol/L HAc system. TBP forms stable 1:1 complexes with both acids, with equilibrium constants around 0.85 under typical conditions. Increasing TBP concentration enhances HNO₃ extraction, while phase ratio adjustments improve HAc separation. A 16-stage countercurrent extraction simulation confirms that optimizing these factors effectively separates HNO₃ and HAc, offering theoretical and technical support for refining the PUREX process.

Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a novel ligand was developed through a strategic application of the Hard and Soft Acids and Bases (HSAB) theory, integrating a soft donor nitrogen atom into the linear architecture of bis-diglycolamide. This groundbreaking ligand, named N,N′-bis[2-(2-(N,N-dioctylcarbamoyl)ethoxy)ethylacetamido]-N″-diethylenetriamine (TOMDEA-BisDGA), has demonstrated remarkable potential in the extraction of Pu(IV). The study unveils that the ligand demonstrates remarkable selectivity and separation efficiency towards Pu(IV) ions while maintaining an exceptionally low extraction capacity for U(VI) across a wide acidity spectrum of 0.1~6 mol/L. To explain the structure properties of complex formed by the ligand and Pu(IV), a systematic analysis was performed, including slope analysis, proton nuclear magnetic resonance (NMR) titration, and Fourier-transform infrared (FT-IR) spectroscopy. This study explores the coordination and separation behavior of diglycolamide ligands with actinide. This work is expected to provide important information and theoretical bases upon which advanced design and optimization of ligands for high-performance processes for the separation of plutonium might be carried out. Such findings will contribute to the understanding of actinide chemistry and further the design of improved separation methods for nuclear applications.