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Sasaki, Yuji
Bunri Gijutsu, 52(2), p.103 - 107, 2022/03
We develop all-inclusive partitioning method for actinides and fission products in high-level radioactive waste. This process is based on the sequential solvent extraction. In order to recover Cs and Sr for the management by interim storage, crown ether compounds are employed. For the removal of Pd and Mo due to production of a stable vitrified object, methylimino-dioctylacetamide (MIDOA) is taken as an extractant. DGA can extract both actinides and trivalent lanthanides. In order to separate each other, dietylenetriamine-triacetic-diamide (DTBA) for the stripping reagent of MA. For the mutual separation of Am/Cm, DGA and DOODA extraction system is taken into consideration.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Separation Science and Technology, 57(16), p.2543 - 2553, 2022/00
Times Cited Count：3 Percentile：40.16(Chemistry, Multidisciplinary)The mutual separation of actinides (An) from lanthanides (Ln) using the masking agent of DTPA (diethylenetriamine-pentaacetic acid) or DTBA (diethylenetriamine-triacetic acid-bis(diethylacetamide)) in the aqueous phase through DGA extraction, referring TALSPEAK method, is focused. We investigate to obtain the same separation performance using commercially available DTPA on that using DTBA. In this work, we select lactic acid (LA) of pH buffer from 10 organic acids and ethylenediamine (ED) for the pH adjustment. Almost the same D and SF values are obtained among the conditions: TODGA-DTPA-LA-NaOH, TODGA-DTPA-LA-ED, and TODGA-DTBA-LA. The experimental results using batchwise multi-stage extractions show the average yields of Ln (La to Gd) and Am to be 3.73 and 98.1% in the aqueous phase using DGA-DTPA-LA-ED, to be 3.1 and 97.0% using DGA-DTPA-LA-NaOH, and to be 1.61 and 98.7% using DGA-DTBA-LA.
Sasaki, Yuji; Kaneko, Masashi; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*
Solvent Extraction and Ion Exchange, 40(6), p.620 - 640, 2022/00
Times Cited Count：1 Percentile：13.58(Chemistry, Multidisciplinary)Owing to the chemical behavior of trivalent lanthanide and actinide ions with similar ionic radii, realizing this separation is still challenging. All lanthanides, Am, and Cm can be extracted using diglycolamide (DGA), and relatively high An/Ln separation efficiencies have been obtained using diethylenetriamine-triacetic-bisamide (DTBA). To improve the previous results as well as the separation conditions, we used organic acids for pH adjustment. The advantages of this modification included low HNO
, DTBA concentrations and pH stability owing to the addition of lactic acid. Under these modified conditions, the recovery rates observed were as follows: 97.1% for Nd with the co-existence of 1.59% Am in organic phase, and 98.4% for Am with the co-existence of 2.95% Nd in aqueous phase.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi
no journal, ,
A selective back-extraction method using DTPA and DTBA as complexants has been developed for mutual separation of actinides and lanthanides (Ln) extracted by TODGA. A novel complexant of DTBA (diethlenetriamine-triaceticdiamide) had high solubility in water and strongly coordinated to Am under lower pH condition than that of DTPA. Multi-stage extraction experiments using DTPA and DTBA showed that the back-extraction ratios of Am and Ln were over 97% and under 3%, respectively. The effects of organic amines, such as ethlenediamine, on the complexation of Am and pH adjustment in the aqueous phase will also be presented.
Sasaki, Yuji; Ban, Yasutoshi; Kaneko, Masashi
no journal, ,
DTBA, developed by JAEA, shows the comparatively high solubility in water, affinity with Ln and An, thus applicable in industrial use. DTBA have relatively high SF(= An/Ln, 8.3) in TODGA extraction system, by DTBA employment An can be separated from Ln through back-extraction from TODGA phase. Here, Ln contents in high-level radioactive waste are several ten times higher than An, it requests higher SF in order to achieve the satisfied separation. In this work, we investigate carefully to obtain higher SF under TODGA-DTBA system. In addition, based on Ln and An having high coordination numbers, we study the possibility of the synergistic back-extraction using DTBA and another masking agent, in order to obtain high SF(An/Ln).
