Characterizing Diamylamylphosphonate (DAAP) as an Americium Ligand for Nuclear Fuel-Cycle Applications

Mincher, Bruce J.; Schmitt, Nicholas C.; Tillotson, Richard D.; Elias, Gracy; White, Byron M.; Law, Jack D.

doi:10.1080/07366299.2013.850288

Cited by 27 publications

(28 citation statements)

References 14 publications

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“…The distribution ratios for the lanthanides and Y are in excellent agreement with those previously measured for the FPEX simulant at this acidity. [6] As expected, Zr and Ru were well extracted, with distribution ratios slightly higher than those seen previously from the oxidized FPEX simulant (D Ru = 5.4); D Zr = 20 [6,7]. However, the extraction of Am and Ce were less efficient than expected.…”

Section: Alsep Simulant and Rusupporting

confidence: 67%

Am(VI) Extraction Final Report: FY17

Mincher

Grimes

Schmitt

et al. 2017

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This report summarizes activities related to hexavalent Am extraction for FY16, in completion of FCR&D Milestone M3FT-16IN030103027. Activities concentrated on three areas of research: 1) centrifugal contactor hot testing, 2) Am(VI) stability studies, and 3) alternative oxidant studies. A brief summary of each task follows.Hot Testing: A new engineering-scale oxidation and solvent extraction test bed was built at Idaho National Laboratory to allow for solvent extraction testing of minor actinide separation concepts. The test bed consists of an oxidation vessel, filtration apparatus, four, 3D printed, 2-cm diameter centrifugal contactors, feed/product vessels, and sample ports. This system replaced the previous 3 stage, 5-cm contactor test bed that was used for the initial testing in FY14. In the FY16 hot test, a feed simulant was spiked with 243 Am and 139 Ce and treated with 60 g/L sodium bismuthate for two hours to oxidize the Am(III) to Am(VI). This solution was then pumped through a filter and into the four-stage centrifugal contactor setup. The organic phase solvent formulation was 1 M diethylhexylbutyramide (DEHBA)/dodecane. The test showed that Am(VI) was produced by bismuthate oxidation and the residual oxidant was successfully filtered without back pressure buildup. Sixty-four percent of Am was extracted in the contactors using DEHBA. Both Am and Ce were quantitatively stripped by 0.1 M H 2 O 2 . Successful demonstration of the utility of small, printable contactors suggests that hot testing of separations concepts can now be conducted more often, since it is cheaper, generates less waste, and entails much less radcon risk than previous testing. Am(VI) stability:A rigorous examination of reagents was conducted to determine if contaminants could interfere with Am oxidation and extraction. An series of D Am measurements showed that bismuthate particle size, water source, acid quality, and DAAP batch or pre-treatment had little effect on extraction efficiency, with a mean distribution ratio of 3.74 ± 0.5, using 1 M DAAP extraction. Additionally, the purposeful addition of millimolar amounts of nitrite or H 2 O 2 to bismuthate-treated Am solutions did not prevent oxidation, as long as residual solid bismuthate was present. Finally, a series of irradiation experiments using a Nordion Gammacell 220E 60 Co source was performed, and kinetic data for the radiolytic reduction of Am(VI) were obtained. Unsurprisingly, it was found that radiolysis reduces Am(VI), but that the presence of Ce(IV) acts as a radioprotection agent, to scavenge radiolyticallyproduced reducing agents, thereby enhancing the stability of the higher Am oxidation state.Alternative oxidants: To date, sodium bismuthate is the only practical oxidant for Am with utility in solvent extraction. While successful oxidation has been demonstrated with sodium peroxydisulfate, it is impractical for solvent extraction because it is only useful in dilute acid and it introduces sulfate into the process. Oxidation has been demonstrated using silver and cobalt ...

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Section: Alsep Simulant and Rusupporting

confidence: 67%

Am(VI) Extraction Final Report: FY17

Mincher

Grimes

Schmitt

et al. 2017

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“…In any of these cases, the challenge is oxidizing the Am and maintaining the higher oxidation state during the separation step. It was first demonstrated in the 1970s, and more recently confirmed, that Am(III) can be oxidized to Am(VI) by sodium bismuthate (NaBiO 3 ) in a nitric acid solution [3][4][5][6], which, unlike sodium persulfate, does not lose its oxidative efficiency at greater than 0.5 mol/L concentration of HNO 3 [7][8][9]. One of the disadvantages of NaBiO 3 as an oxidant for Am(III) is a slow dissolution rate and its limited solubility in HNO 3 .…”

Section: Introductionmentioning

confidence: 98%

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Sinkov¹,

Lumetta²

2015

Radiochimica Acta

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The oxidative action of a Cu(III) periodate compound toward Am(III) in nitric acid was studied. The extent of oxidation of Am(III) to Am(VI) was investigated using a constant initial Cu(III)-to-Am(III) molar ratio of 10 : 1 and varying nitric acid concentrations from 0.25 to 3.5 mol/L. From 0.25 to 3 mol/L HNO 3 , more than 98% of the Am(III) was oxidized to Am(VI); however, at 3.5 mol/L HNO 3 , the conversion to Am(VI) was only 80%. Increasing the Cu(III)-to-Am(III) molar ratio to 20 : 1 in 3.5 mol/L HNO 3 resulted in 98% conversion to Am(VI). For comparison, oxidation of Am(III) with NaBiO 3 was studied at 3.5 mol/L HNO 3 and the same stoichiometric excess of Bi(V) oxidant over Am(III) (stoichiometric ratio of 3.33 : 1). With NaBiO 3 , the extent of Am(III) conversion to Am(VI) was only 19%, while with the Cu(III) compound this value was found to be about 4 times higher under otherwise identical conditions. Similar results were obtained with other Bi(V) salts. These results show that the Cu(III) periodate compound is a superior oxidant to NaBiO 3 , yielding rapid conversion to Am(VI) in a homogeneous acidic solution, and is, therefore, an excellent candidate for further development of Am separation systems.

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“…The standard potential for the Am(III)/Am(VI) redox couple under acidic conditions is about 1.7 V, and thus strong oxidizing agents are required [1,11]. Several oxidants have been explored including peroxydisulfate [12,13], copper(III) periodate [14,15], electrochemical techniques [16], and sodium bismuthate [5][6][7][8]17]. Once oxidized the Am(VI) exists as the americyl AmO 2 2+ ion and behaves similarly to the other hexavalent actinyl cations.…”

Section: Theorymentioning

confidence: 99%

“…Of several oxidants that have been investigated, only sodium bismuthate has been used successfully for solvent extraction experiments [5]. Several ligands have been evaluated for Am(VI) extraction including conventional tributylphosphate (TBP) [6], its more basic analogues dibutylbutylphosphonate (DBBP) [5] and diamylamylphosphonate (DAAP) [7]. Prior development efforts have resulted in the demonstration of the extraction of Am(VI) in engineering-scale centrifugal contactors using DAAP [8].…”

Section: Introductionmentioning

confidence: 99%

Oxidation and extraction of Am(VI) using a monoamidic extractant in 3D printed centrifugal contactors

Law

Mincher

Tillotson

et al. 2018

J Radioanal Nucl Chem

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A series of tests were performed using centrifugal contactors to evaluate the separation of Am(VI) from cerium, as well as to determine the efficiency of the contactors. All experiments were performed using 2-cm, acrylic 3D-printed centrifugal contactors.Solvent extraction tests were performed using 1 M N,N-di(2-ethylhexyl)butyramide (DEHBA)/dodecane and a nitric acid feed solution spiked with 243 Am and 139 Ce and oxidized with 60 mg mL -1 sodium bismuthate. Approximately 72 % of the Am was extracted with a single contactor stage. Co-stripping of Am and Ce was demonstrated but attempts at selective stripping were not successful. Successful recycle of the used organic phase was demonstrated. Contactor efficiencies of 95 % to 100 % were obtained.

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Characterizing Diamylamylphosphonate (DAAP) as an Americium Ligand for Nuclear Fuel-Cycle Applications

Cited by 27 publications

References 14 publications

Am(VI) Extraction Final Report: FY17

Am(VI) Extraction Final Report: FY17

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Oxidation and extraction of Am(VI) using a monoamidic extractant in 3D printed centrifugal contactors

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