Novel water-soluble aromatic bisdiglycolamide masking agents for the separation of trivalent americium over lanthanides by NTAamide(n-Oct) extractant

Two novel water-soluble aromatic bisdiglycolamides (BisDGAs) of SO 3 -TEX( m )-BisDGA (sodium bis((2-(2-(diethylamino)− 2-oxoethoxy)acetamido)methyl)benzenesulfonate) and SO 3 -TEX( p )-BisDGA (sodium 2,5-bis((2-(2-(diethylamino)− 2-oxoethoxy)acetamido)methyl)benzenesulfonate) were synthesized and used as masking agents for the selective extraction and separation of Am 3+ over Eu 3+ in HNO 3 solutions by N,N,N′,N′,N′′,N′′ -hexaoctylnitrilotriacetamide (NTAamide( n -Oct)) in n -dodecane. Their influences on the separation effect of Am 3+ over Eu 3+ were investigated and compared with that of a water-soluble aliphatic bisdiglycolamide of N,N,N′′′,N′′′ -tetraethyl- N′,N′′ -ethidene bisdiglycolamide (TEE-BisDGA) reported by our previous work. SO 3 -TEX( m )-BisDGA and SO 3 -TEX( p )-BisDGA exhibit significantly better masking effects than TEE-BisDGA. The masking selectivity for Eu 3+ over Am 3+ follows the order of SO 3 -TEX( m )-BisDGA > SO 3 -TEX( p )-BisDGA > TEE-BisDGA. During the extraction process, the three BisDGA masking agents form the 1:2 complexes, while the NTAamide ( n -Oct) extractant forms the 1:1 complexes with Am 3+ and Eu 3+ . Meanwhile, the conditional stability constants (log β ) for the three masking agents with Eu 3+ were calculated using the least squares method, which are also in line with those obtained from fluorescence spectrometry (FS). By means of FS, time-resolved laser-induced fluorescence spectrometry (TRLFS), Fourier Transform infrared spectrometry (FT-IR), conductivity, and electrospray ionization mass spectrometry (ESI-MS) analyses, the composition of the complex of Eu 3+ with water-soluble BisDGAs (L) was determined to be [Eu(NO 3 ) 2 (H 2 O)∙2L](NO 3 ). Furthermore, a batch simulation of multistage countercurrent extraction with 12-stage extraction, 4-stage scrubbing and 8-stage stripping was carried out and demonstrates a highly efficient separation of Am 3+ over Lns 3+ with the recovery rates above 99.9 % for all metal ions in the simulated feed solution, and with the decontamination factors more than 500 between Am 3+ and most of the lanthanide ions.