NTAamide(C8) exhibits high selectivity for the extraction of Pu(IV) across a wide range of nitric acid concentrations. To separate trace Pu(IV) from radioactive liquid stream generated during the PUREX process in spent nuclear fuel reprocessing, a novel silica-polymer-based adsorbent, NTAamide(C8)/SiO 2 -P, was synthesized via vacuum impregnation using NTAamide(C8) as the extractant and SiO 2 -P as the support. The adsorption performance of Pu(IV) were systematically evaluated. Batch experiments revealed that adsorption equilibrium was achieved within 2 h, with a maximum adsorption capacity of 143.2 mg/g for Pu(IV). The material demonstrated high selectivity for Pu(IV) and exhibited excellent radiation resistance and hydrolytic stability. The adsorption mechanisms were further elucidated using X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations, confirming the formation of 1:1 complexes between NTAamide(C8) and the metal ions. Column experiments using actual uranium product solution from the PUREX process verified the material's performance in trace Pu(IV) removal. After column treatment, the Pu content in the uranium product solution was reduced to below 10 Bq/gU, with no significant loss of uranium. These results demonstrate that NTAamide(C8)/SiO 2 -P is a promising adsorbent for the efficient and selective separation of Pu(IV) from radioactive liquid stream under a wide range of nitric acid concentrations.
Zhipeng Wang,Songdong Ding,Xiaoyang Hu,Shimeng Li,Dongping Su,Lirong Zhang,Ying Liu,Yongdong Jin
A novel water-soluble ligand of N,N,N‴,N‴ -tetraethyl- N ′ ,N ″-ethidene bisdiglycolamide (TEE-BisDGA) was synthesized and used as a masking agent for selective extraction of Am(III) over Eu(III) from HNO 3 solution by N,N,N ′, N ′ ,N ″ ,N ″-hexaoctylnitrilotriacetamide (NTAamide(C8)) in kerosene. Influences of acidity, concentration of water-soluble ligands and extractant as well as nitrate ions on the distribution ratios ( D ) and separation factors ( SF ) of Am(III) and Eu(III) were investigated. In the range of examined acidity from 0.001 to 0.2 mol/L, D Am and D Eu decreased with the increase of HNO 3 concentration. Using 0.1 mol/L NTAamide(C8) as an extractant, the maximum SF Am/Eu of 26 can be obtained in the presence of 0.01 mol/L TEE-BisDGA in aqueous phase with pH of 3.0, which was significantly higher than that case with no TEE-BisDGA. Job's method and mole ratio method were employed for extraction mechanism research. It has been shown that Am(III) and Eu(III) formed di-solvated species with TEE-BisDGA and mono-solvated species with NTAamide(C8), respectively. Moreover, the stability constants logβ values were obtained from UV–vis adsorption spectroscopic titration for Nd(III) complexes with TEE-BisDGA and N,N,N ′ ,N ′-tetraethyldiglycolamide (TEDGA), which indicated that TEDGA had a stronger complex ability than TEE-BisDGA.
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