Selective extraction of americium(III) over europium(III) ions in nitric acid solution by NTAamide(C8) using a novel water-soluble bisdiglycolamide as a masking agent

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.