Separation of curium from americium using composite sorbents and complexing agent solutions
Kamila Šťastná, Jan John, Ferdinand Šebesta, Martin Vlk
Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical
University in Prague, Břehová 7, 115 19 Prague 1, Czech Republic e-mail: kamila.stastna@fjfi.cvut.cz, phone: +420 224 358 201, fax: +420 224 358 202
Abstract Two liquid-liquid extraction processes intended as a part of the Partitioning and Transmutation strategy have been used as bases for the development of chromatographic systems for separation of curium from americium. The liquid organic phase of the EXAm process was replaced by DMDOHEMA-PAN composite sorbent and TEDGA in nitric acid solution was employed as an aqueous-phase complexing agent. The liquid organic phase of the AmSel process was replaced by TODGA-PAN composite sorbent and sulfonated BTBP derivative in nitric acid solution was employed as an aqueous-phase complexing agent. The influence of aqueous phase complexing agent and nitric acid concentrations on weight distribution coefficients and separation factor as well as the kinetics of the actinide uptake were determined in batch experiments with trace amounts of 241 Am and 244 Cm. The efficiency of Cm separation from Am was evaluated in column experiment.
Keywords
Introduction americium, curium, separation, composite sorbent, complexing agent
The separation of curium from americium is recently in concern relating reprocessing of spent nuclear fuel and recycling of the actinides in MOX fuels. Whereas americium is supposed to be utilized in MOX fuels, curium, because of its neutron activity and high heat output, would place high security demands on the fabrication process. Hence, it is preferred to separate them and store curium to decay to plutonium. Furthermore, because of the safety of reactor operating and spent fuel storage, it is necessary to know the isotopic composition of the fuel. Isotopic composition determination by mass spectrometry requires the separation between americium and curium because of isobaric interferences of 242 and 243 isotopes. The mutual separation may be necessary also for their determination if one of the radionuclides is present in significantly lower amount.
First attempts to separate americium from curium, after americium first production, were carried out by selective elution with ammonium citrate solution from strong acid cation exchanger [1]. Later, many other hydroxy acids were employed, including tartaric and lactic acids [2]. By far the most
For the first time, LiNO resins.
3
was employed [14].
Comparison between separation efficiency of saturated nitrate solutions of different metals was published by Kraak and Heijden [15]. The alternative to the concentrated salt solution elution is the use of methanolic nitric acid solution [16-18].
Separation factor achieved ranged from 1.9 to 2.6.
The drawbacks of ion exchange are low separation factors and radiation instability of ion exchange
Separation in nitric acid/methanol mixed solvent system was also investigated using weak basic anion exchanger with tertiary pyridine function group embedded in highly porous silica beads which has high radiation resistance [19, 20].
While the separation using ion exchangers is carried out with trivalent ions of americium and curium, the precipitation and liquid-liquid extraction methods mostly use the existence of higher oxidation states of americium in solutions, but these are only achievable using strong oxidizing agents such as peroxydisulphate. Am(VI) remains in solution while curium is precipitated as CmF
3
[21, 22]. Americium can be released from hydroxide suspension in NaHCO
3
solution when oxidized to Am(VI) by bubbling ozone [23, 24]. frequently used hydroxy acid is alpha- hydroxy-isobutyric acid (HIB) for both macro and micro-scale quantity separations [3-8]. Also, its analogue alpha-hydroxy-alpha-methyl butyric acid
(HMB) was employed [9-11]. The use of other compexing agents such as ethylenediaminetetraacetic acid (EDTA) [12], diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA) [13] was less common.
Separation factors achieved using cation exchangers and complexing agent eluting solutions ranged from 1.2 to 2.
Separation using strong basic anion exchanger is much less common and requires elution with slightly acidic highly concentrated salt solutions.
The other possibility represents precipitation of
Am(V) in form of KAmO
2
CO
3
after americium oxidation by KClO in K
2
CO
3
solution while
Cm(III) remains in solution Horwitz [25].
Am(VI) can be separated from Cm by extraction with bis(2,6-dimethyl-4-heptyl)phosphoric
(HD(DIBM)P) [26, 27], tributyl phosphate (TBP)
[28, 29], or dibutyl butyl phosphonate (DBBT)
[30]. On the other hand Am(V) is not extracted under the condition when curium is, for example by
2-thenoyltrifluoroacetone synergistic mixture with tri-
(TOPO) [32].
(TTA) n
[31] or acid its
-octylphosphine oxide

Separation of oxidized Am from Cm was also studied using extraction chromatography with bis(2-etylhexyl)phosphoric acid (HDEHP) [33, 34].
The preparation and characterization of higher oxidation states of americium and their use for separations have been recently reviewed by Runde and Mincher [35].
The drawback of the methods using oxidation of
Am is the instability of its higher oxidation states which requires fast process and very high purity of chemicals used.
Until recently, among rare attempts not using americium oxidation, tertiary or quaternary amines were the most studied agents for liquid-liquid extraction and extraction chromatography [36-38].
Recently developed extraction processes try to separate americium and curium as trivalent ions, for example by synergic mixture of bis(chlorophenyl)dithiofosfinic acid ((ClPh)
2
PSSH) and tris(2-etylhexyl)phosphate (TEHP) in LUCA process [39]. In Europe two such liquid-liquid extraction processes are under development now.
The EXAm process, intended also for the separation of Am from Ln, uses bidentate malonamide extractant N,N´-dimethyl-N,N´dioctylhexylethoxymalonamide (DMDOHEMA) which preferably extracts Am over Cm (SF
Am/Cm
~
1.6). The efficiency of the process is improved by using aqueous phase tridentate complexing agent
N,N,N´,N´-tetraethyldiglycolamide (TEDGA) which forms stronger complexes with Cm. Process employed 0.65 mol L -1 DMDOHEMA in alcane as an organic phase and 0.3 mol L -1 TEDGA in 4.5 mol L -1 HNO
3
as an aqueous phase consists of 32 stages [40, 41]. AmSel process employs tridentate
N,N,N´,N´-tetraoctyldiglycolamide
(TODGA) which preferably extracts Cm (SF
Cm/Am
~ 1.5) and tetradentate 6,6´-bis(5,6-di(sulphophenyl)-1,2,4triazin-3-yl)-2,2´-bipyridine (SO
3
-Ph-BTBP) as aqueous phase complexing agent (expected SF
Am/Cm derived from extraction with lipophilic CyMe
4
-
BTBP ~ 1.6). Expected SF in 0.2mol L -1 TODGA in 5% 1-octanol in TPH and 18 mmol L -1 SO
3
-Ph-
BTBP in 0.55 – 0.7 mol L -1 nitric acid system was
2.5. [42]. These two processes have been used as bases for development of chromatographic systems for separation of curium from americium. The liquid organic phases were replaced by composite sorbents with polyacrylonitrile (PAN) as a binding matrix. PAN was proposed as a binding polymer for inorganic ion-exchangers [43] and later used also as a support material for extraction agents [44-
48].
Experimental
Reagents, materials and instrumentation
The solutions of 241 Am were prepared by dissolution of americium dioxide AmO
2
(37 MBq,
Isotope Products Cesio s.r.o. Prague) in
5mol L -1 HNO
3
with subsequent dilutions with distilled water. The solutions of 241 Cm were prepared by dissolution of curium nitrate Cm(NO
3
)
3
(37 MBq, reference date 16 February, 2007,
TENEX Russia) in 0.01mol L -1 HNO
3
with subsequent dilutions with distilled water.
Composite sorbents DMDOHEMA-PAN and
TODGA-PAN (33% active component, grain size <
0.300 mm) were prepared by Ferdinand Šebesta at the Department of Nuclear Chemistry FNSPI CTU.
TEDGA was prepared by Martin Vlk at the
Department of Nuclear Chemistry FNSPI CTU.
3,3’,3’’,3’’’-[3-(1,10-phenanthroline-2,9-diyl)-
-1,2,4-triazine-5,5,6,6-tetrayl] tetrabenzensulfonic acid ((PhSO
3
H)
2
-BTPhen) was supplied by the
University of Reading, United Kingdom.
Nitric acid 65% (Lach-Ner, Ltd., Czech Republic) was of analytical grade.
Sorbents and solid chemicals were weighted using analytical balances SA 210D (ANSELMA-
INDUSTRIE, Germany). Solutions were pipetted using Eppendorf Research pipette with epTIPS
(Eppendorf AG, Germany).
Batch experiments were carried out in 1.5mL screw cap PP micro tubes with silicone seal (BRAND
GMBH + CO KG, Germany) by using Grant Bio
PTR-30 360 Degree Vertical Multi-Function
Rotator (Grant Instruments, United Kingdom).
Liquid phase was separated from sorbent by filtration through small round of Whatman Glass
Microfiber Filter Grade GF/C: 1,2 µm (GE
Healthcare Life Sciences, UK) placed in Injekt™ 2 mL LS Syringe (B. BRAUN, USA) into 1.5 mL PP microcentrifuge tubes with lid closure (BRAND
GMBH + CO KG, Germany). Aliquots of aqueous phase before and after contacting with sorbent were deposited on flat bottom cupped stainless steel planchets with overall diameter 31.8 mm and overall height 2.4 mm (GA-MA & ASSOCIATES,
INC., USA).
Samples were measured using ORTEC
®
OCTETE
Plus Integrated Alpha-Spectroscopy System equipped with ion-implanted-silicon ULTRA Alpha
Detector Model BU-020-450-AS, and the spectra were evaluated by AlphaVision-32 Alpha Analysis
Software (ORTEC, Advanced Measurement
Technology, Inc., USA).
Column experiments were carried out in 1mL capacity polyethylene disposable Pasteur pipette
BRAND™ PLASTIBRAND™ pipette (Brand
GmbH & Co. KG), from which the top of the bulk was removed to make a funnel and the tip was shorten to eliminate the dead volume of the column.
The fractions were collected using Model 2110
Fraction Collector (Bio-Rad Laboratories, USA) into Polypropylene 12 x 75mm Round Bottom
Screw Cap Test Tubes (Globe Scientific Inc.,
USA).

Methods
Batch experiments
For TEDGA concentration dependency studies, calculated amount of 0.1mol L -1 TEDGA in
4mol L -1 HNO
3
stock solution was mixed with
4mol L -1 HNO
3
to obtain 1 mL of solution of required TEDGA concentration. For acid dependency studies, 100 μL of 0.1mol L -1 TEDGA in 4mol L -1 HNO
3
was mixed with calculated amount of 4mol L -1 HNO
3
so that after adding water to 1 mL, required concentration of HNO
3
was achieved, except for 5mol L -1 HNO
3
when 8mol L -1
HNO
3
was used. For kinetics studies, 100 μL of
0.1mol L -1 TEDGA in 4mol L -1 HNO
3
was mixed with 900 μL of 4mol L -1 HNO
3
.
For (PhSO
3
H)
2
-BTPhen concentration dependency studies, calculated amount of (PhSO
3
H)
2
-BTPhen was dissolved in 1 mL of 0.3 mol L -1 HNO
3
. For acid dependency studies, 10 mg of
(PhSO
3
H)
2
-BTPhen was dissolved in HNO
3
of desired concentration. For kinetics studies, 3 mg of
(PhSO
3
H)
2
-BTPhen was dissolved in 0.3 mol L -1
HNO
3
. The dissolution of (PhSO
3
H)
2
-BTPhen in nitric acid solutions was carried out using rotorator at 30 rpm and 360° for 10 minutes.
Complexing agent solutions were spiked with 8 μL of 241 Am solution and 12 μL of 244 Cm solution (app.
4 kBq each). Two 10μL aliquots of spiked solution were deposited on pretreated planchets and treated as published earlier [49]. Then, 10 mg of composite sorbent was added to spiked complexing agent solution, DMDOHEMA-PAN to TEDGA solution and TODGA-PAN to (PhSO
3
H)
2
-BTPhen solution.
Solutions with sorbents were shaken using rotorator at 30 rpm, 30° for 10 minutes in case of
DMDOHEMA-PAN and at 30 rpm, 360° for 1 hour in case of TODGA-PAN, with the exception of kinetics studies. Liquid phase was separated by filtration, and two 10μL aliquots were deposited on planchets.
Weight distribution coefficients were calculated according the formula
D w

A
0

A
A

V m
, where A
0
denotes count rate in alpha spectrum peak of respective radionuclide determined by measuring the aqueous phase aliquot before sorbent added, A denotes count rate in alpha spectrum peak of respective radionuclide determined by measuring the aqueous phase aliquot after shaking and sorbent separation, V is the liquid phase volume, and m is the composite sorbent weight. Separation factor was calculated according the formulas
SF

D w
( Am )
and
D w
( Cm )
SF

D w
( Cm )
D w
( Am ) for DMDOHEMA-PAN/TEDGA
TODGA-PAN/(PhSO
3
H)
2
-BTPhen respectively. and system,
In case of kinetics studies, the sorbed fraction was calculated according the formula f

1

A
.
A
0
Column experiments
A small glass microfiber filter plug was inserted at the bottom of the column to support the sorbent.
The column was filled with dry sorbent and a small amount of glass wool was placed at the top. The column was conditioned by passing 10 mL of nitric acid solution. Then, 50 μL of nitric acid solution spiked with trace amounts of 241 Am and 244 Cm
(app. 3 kBq each) was loaded on the top of the column, following with two 50 μL pure nitric acid rinses. The elution of the radionuclides from the column was carried out using complexing agent in nitric acid solution selected based on batch experiments results. The mobile phase was passed through the column by gravity (app. 0,100 mL min -1 ) and six-drop fractions (0,200 mL) were collected. 10 μL aliquots of each fraction were deposited on the planchets and measured. The separation factor was calculated according the formula
SF

V
Am
V
Cm

V d

V d
, where V
Am
and V
Cm
denote the effluent volume at the elution peak of respective radionuclide and V d is column dead volume.
Results and discussion
Kinetics for DMDOHEMA-PAN/TEDGA system
Measurement of the influence of shaking time on americium and curium uptake, carried out using
0.01mol L -1 TEDGA in 4mol L -1 HNO
3
in the range of 2 minutes to 2 hours, showed that the kinetics of the process is fast, the equilibrium was reached in less than 10 minutes. Thus, the kinetics of radionuclides uptake on DMDOHEMA based sorbents from TEDGA in HNO
3
solutions seems to be as fast as from pure HNO
3
solutions [50].
Acid dependency for DMDOHEMA-PAN/TEDGA system
Weight distribution coefficients determined at
0.01mol L -1 TEDGA and varied HNO
3
(0.4 to 5 mol L -1 ) concentrations are shown in Fig. 1. Weight distribution coefficient values ranged between units and tens mL g -1 and increased with nitric acid concentration in the range of 2 to 5 mol L -1 but decreased in the range of 0.4 to 2 mol L -1 . In the study of actinides uptake on DMDOHEMA-
Amberchrom CG-71C from pure HNO
3
solutions,
D w
values increased with increasing HNO
3

concentration at all HNO
3
concentrations [50]. On the other hand, in the study of actinides uptake on
DMDOHEMA-PAN from 0.1mol L -1 NaNO
3
at varied HNO
3
concentration, the increase of D w
with decreasing HNO
3
concentration was observed for
HNO
3
concentrations lower than 0.5 mol L -1 [47].
Possible explanation for this phenomenon may be sorption of ions on PAN matrix at low nitric acid concentrations. The increase of D w
with decreasing
HNO
3
concentration in the range of 0.4 to 2 mol L -1 observed in this study might be caused also by sorption of An-TEDGA complexes on PAN matrix.
The sorption properties of PAN polymer are still under the study at the CTU. The maximum separation coefficient, reached at 0.01mol L -1
TEDGA and 4mol L -1 HNO
3
concentration, had a value of 1.8.
Am Cm SF
Am Cm SF
100
80
60
40
20
0,9
0,6
0,3
0
0 2 4 6 8 10 12 14 16 18 20 22
0,0
2,1
1,8
1,5
1,2
SF
TEDGA concentration (m m ol L
-1
)
100
80
60
40
20
0
0 1 2 3 4 5
HNO
3
concentration (m ol L
-1
)
Fig. 1 Sorption of Am and Cm on DMDOHEMA-PAN from 0.01mol L -1 TEDGA solution at varied HNO
3 concentration (V/m = 100, rotorator: 30 rpm, 30°, 10 min, room temperature)
TEDGA concentration dependency for
DMDOHEMA-PAN/TEDGA system
Weight distribution coefficients, determined at varied TEDGA (0.001 to 0.02mol L -1 ) and 4mol L -1
HNO
3
concentration, are shown in Fig. 2. They ranged between units and tens mL g -1 and decrease with increasing TEDGA concentration.
6
0,9
0,6
0,3
0,0
2,1
1,8
1,5
1,2
SF
Fig. 2 Sorption of Am and Cm on DMDOHEMA-PAN from 4mol L -1 HNO
3
at varied TEDGA concentration
(V/m = 100, rotorator: 30 rpm, 30°, 10 min, room temperature)
Column experiment for DMDOHEMA-PAN/TEDGA system
Based on batch experiments, the 0.01mol L -1
TEDGA in 4mol L -1 HNO
3
was selected as eluting solution for column chromatographic experiment.
Effluent volumes at the peak maximum, calculated from D w
values from batch experiments (31 ± 2 and
17 ± 2 for Am and Cm, respectively) and column characteristics, had values of 4.7 and 2.6 BV. As can be seen from Fig. 3, the data obtained from column experiment confirmed the assumptions, and the separation factor calculated from americium and curium effluent volumes measured at the column experiment was in good agreement with the batch experiment one having a value of 1.8 ± 0.2. The collected fraction containing 60 % of Cm contained also 6 % of Am.
Am Cm
3000
2500
2000
1500
1000
500
0
0 1 2 3 4 5 6 7 8 9
Effluent volum e (BV)
Fig. 3 Elution curve of Cm separation from Am in
DMDOHEMA-PAN/0,01mol L -1 TEDGA in 4mol L -1
HNO
3
solution system (column: 0.4 x 6.5 mm, sorbent

weight 0.12 g, BV 0.82 mL, FBV 0.28 mL, flowrate
0.100 mL (0,12 BV) / min)
Kinetics for TODGA-PAN/(PhSO
3
H)
2
-BTPhen system
As can be seen from Fig. 4, the kinetics for
TODGA-PAN/(PhSO
3
H)
2
-BTPhen system is slower than for DMDOHEMA-PAN/TEDGA system. The quasi-equilibrium is attained in about 1 hour, followed by slight increase in uptake for further hours. This phenomenom is also known for sorption on TODGA-Amberchrom CG-71C from pure HNO
3
solution [50].
Am Cm
100
90
80
70
60
50
40
30
20
10
0
0 30 60 90 120 150 180 210 240 270 300 330 360
Tim e (m in)
Fig. 4 Sorption of Am and Cm on TODGA-PAN from
0.003mol L -1 (PhSO
3
H)
2
-BTPhen in 0.3mol L -1 HNO
3 solution at varied shaking time (V/m = 100, rotorator: 30 rpm, 360°, room temperature)
Acidity dependence for
TODGA-PAN/(PhSO
3
H)
2
-BTPhen system
Because of small amount of (PhSO
3
H)
2
-BTPhen available, only limited number of experiments could be carried out trying to find suitable conditions for column experiment.
Weight distribution coefficients determined at
0.01mol L -1 (PhSO
3
H)
2
-BTPhen solution at varied
HNO
3
concentration are shown in Fig. 5. As can be seen, D w
values increase with increasing HNO
3 concentration in the range of 0.1 to 0.7 mol L -1 which is in contrast with the increase od D w
with the decreasing HNO
3
concentration at these acidities in DMDOHEMA-PAN/TEDGA system.
The separation factor values decrease with increasing HNO
3
concentration which is in accordance with the observations from liquid-liquid extraction system 0.2mol L -1 TODGA + 5% vol. 1octanol in TPH and 18mmol L -1 SO
3
-Ph-BTBP
[51]. Using (PhSO
3
H)
2
-BTPhen, the sulphonated derivative of cis -locked tetradentate bis-triazine ligands containing 1,10-phenantroline moiety [52], instead of SO
3
-Ph-BTBP from about 2.5 up to 4.
lead to increase of SF
Am Cm SF
2000
1800
1600
1400
1200
1000
800
600
400
200
0
0 0,2 0,4 0,6
HNO
3
concentration (m ol L
-1
)
Fig. 5 Sorption of Am and Cm on TODGA-PAN from
0.01mol L -1 (PhSO
3
H)
2
-BTPhen solution at varied HNO
3 concentration (V/m = 100, rotorator: 30 rpm, 360°, 1 hr, room temperature)
(PhSO
3
H)
2
-BTPhen concentration dependence for TODGA-PAN/(PhSO
3
H)
2
-BTPhen system
Weight distribution coefficients determined at
0.3mol L -1 and varied (PhSO
3
H)
2
-BTPhen concentrations are shown in Fig. 6. As can be seen, the D w values decrease with increasing
(PhSO
3
H)
2
-BTPhen concentration while the separation factor values increase. So, it might seem that the suitable conditions for column experiment could be selected according the amount of ligand available by lowering HNO
3
concentration. During the batch experiments, it was observed that the D w values were highly influenced by the time for which the radionuclides and (PhSO
3
H)
2
-BTPhen solution had been in contact before the sorbent was added.
For example in TODGA-PAN/5mmol L -1
(PhSO
3
H)
2
-BTPhen in 0.3mol L -1 HNO
3
system,
D w
(Am) value was about 3 times lower if the radionuclides had been in contact with complexing agent solution for 10 minutes before the sorbent was added than the value derived from dependency curve for immediately added sorbent.
0,8
5,0
4,5
4,0
3,5
3,0
2,5
2,0
1,5
1,0
0,5
0,0
SF

Am Cm Am 10 Cm 10 SF SF 10
100000
10000
1000
100
10
1
0,01 0,1 1 10 100
0,0
BTPhen concentration (m m ol L
-1
)
Fig. 6 Sorption of Am and Cm on TODGA-PAN from
0.3mol L -1 HNO
3 solution at varied
(PhSO
3
H)
2
-BTPhen concentration (V/m = 100, rotorator: 30 rpm, 360°, 1 hr, sorbent added immediately or after 10 min of radionuclides and complexing agent solution in contact)
Conclusions
Two systems employing composite sorbent and complexing agent solution have been studied in order to improve the separation between americium and curium. Column experiment in DMDOHEMA-
PAN/TEDGA solution system proved the observation from batch experiments regarding D w and SF values, but the peak resolution was not sufficient to achieve complete separation.
Batch experiments in TODGA-PAN/
(PhSO
3
H)
2
-BTPhen solution system were very encouraging regarding separation factor of curium over americium, but discrepancies occurred when the radionuclides were in contact with the ligand before sorbent was added . The more detailed kinetics studies of the system should be carried out to find suitable conditions for successful column experiment.
Acknowledgments
This research has been supported by the Grant
Agency of the Czech Technical University in
Prague, grants No. SGS11/071/OHK4/1T/14 and
SGS12/199/OHK4/3T/14.
References
1.
Seaborg GT, James RA, Morgan LO (1949)
The New Element Americium (Atomic Number
95) , THIN PPR 14 B The Transuranium
Elements: Paper No. 22.1, McGraw-Hill Book,
New York
2.
Glass RA (1955) J Am Chem Soc 77:807-809
3.
Choppin GR, Harvey BG, Thompson SG
(1956) J Inorg Nucl Chem 2:66-68
4.
Smith HL, Hoffman DC (1956) J Inorg Nucl
Chem 3:243-247
4,5
4,0
SF
3,5
3,0
2,5
2,0
1,5
1,0
0,5
5.
Thompson GH (1972) Ion Exch Membr 1:87-
89
6.
Billon A (1979) J Radioanal Chem 51:297-305
7.
Bigelow JE, Benker DE, Chattin FR, King LJ,
Knauer JB, Ross RG, Stacy RG, Wiggins JT,
Gram-scale separation of curium from americium using ammonium
α-hydroxyisobutyrate in high-pressure cation columns . International Symposium on
Actinide/Lanthanide Separations, Honolulu,
16-22 December 1984
8.
Vobecký M (1986) J Radioanal Nucl Chem
Letters 105:335-340
9.
Vobecký M (1989) J Radioanal Nucl Chem
Letters 135:165-169
10.
Chartier F, Aubert M, Pilier M (1999)
Fresenius J Anal Chem 364:320-327
11.
Goutelard F, Caussignac C, Brennetot R,
Stadekmann G, Gautier G (2009) J Radioanal
Nucl Chem 282:669-675
12.
Fuger J (1958) J Inorg Nucl Chem 5:332-338
13.
Hale WH, Lowe JT (1969) Inorg Nucl Chem
Letters 4:363-368
14.
Adar S, Sjoblom RK, Barnes RF, Fiels PR
(1963) J Inorg Nucl Chem 25:447-452
15.
Kraak W, Heijden van der WA (1966) J Inorg
Nucl Chem 28:221-224
16.
Morrow RJ (1966) Talanta 13:1265-1274
17.
Lebedev IA, Myasoedov BF, Guseva LI (1974)
J Radioanal Chem 21:259-266
18.
Osaka M, Koyama S, Mitsugashira T (2004) J
Nucl Sci Technol 41:907-914
19.
Suzuki T, Otake K, Sato M, Ikeda A, Aida M,
Fujii Y, Hara M, Mitsugashira T, Ozawa M
(2007) J Radioanal Nucl Chem 272:257-262
20.
Nogami M, Fujii Y, Sugo T (1996) J Radioanal
Nucl Chem 203:109-117
21.
Stephanou SE, Penneman RA (1952) J Am
Chem Soc 74:3701-3702
22.
Moore FL (1963) Anal Chem 35 :715-719
23.
Coleman JS, Keenan TK, Jones LH, Carnall
WT, Penneman RA (1963) Inorg Chem 2:58-61
24.
Shehee T, Martin LR, Zalupski PR, Nash KL
(2010) Separ Sci Technol 45:1743-1752
25.
Horwitz EP, Bloomquist CAA, Harvey HW,
Cohen D, Basile LJ (1965) ANL-6998
26.
Moore FL (1966) Anal Chem 38 :510-512
27.
Appelman EH, Diamond H, Horwitz EP,
Sullivan JC (1991) Radiochim Acta 55 :61-64
28.
Donnet L, Adnet JM, Faure N, Bros P,
Brossard P, Josso F, Development of the
SESAME process . SFEN, ENS 5th International
Conference on Recycling, Conditioning and
Disposal, Nice, 25-28 October 1998
29.
Martin LR, Mincher BJ, Schmitt NC (2009) J
Radioanal Nucl Chem 282:523-526
30.
Mincher BJ, Martin LR, Schmitt NC (2008)
Inorg Chem 47:6984-6989
31.
Stokely JR, Moore FL (1967) Anal Chem
39:994-997
32.
Fardy JJ, Buchanan JM (1976) J Inorg Nucl
Chem 38:149-154
33.
Hulet EK (1964) J Inorg Nucl Chem 26:1721-
1727
34.
Moore FL (1968) Anal Chem 40:2130-3133
35.
Runde WH, Mincher BJ (2011) Chem Rev
111:5723-5741

36.
Horwitz EP, Bloomquist CAA, Sauro LJ,
Henderson DJ (1966) J Inorg Nucl Chem
28 :2313-2324
37.
Mason GW, Bollmeier AF, Peppard DF (1970)
J Inorg Nucl Chem 32 :1011-1022
38.
Horwitz EP, Orlandini KA, Bloomquist CAA
(1966) Inorg Nucl Chem Letters 2: 87-91
39.
Modolo G, Kluxen P, Geist A (2010)
Radiochim Acta 98:193-201
40.
Warin D, Recent progress in Advanced
Actinide Recycling Processes . OECD NEA
11th Information Exchange Meeting on
Actinide and Fission Product Partitioning and
Transmutation, San Francisco, 1-4 November
2010
41.
Charbonnel M-C, Berthon C, Berthon L,
Boubals N, Burdet F, Duchesne M-T, Guilbaud
P, Mabille N, Petit S, Zorz N (2012) Procedia
Chem 7:20-26
42.
Geist A, Müllich U, KIT-INE DM1 WP2
Contribution . 4th ACSEPT Annual Meeting,
Karlsruhe, 20-22 March 2012
43.
Šebesta F (1997) J Radioanal Nucl Chem
220:77-88
44.
Mann NR, Todd TA, Tranter TJ, Šebesta F
(2002) J Radioanal Nucl Chem 254:41-45
45.
Tranter TJ, Mann NR, Todd TA, Šebesta F
(2003) Czech J Phys 53:A589-A594
46.
Kameník J, Šebesta F (2006) Czech J Phys
56:D493-D500
47.
Šuľaková J, John J, Šebesta F (2006) Czech J
Phys 56:D589-D597
48.
Šebesta F, Kameník J (2010) J Radioanal Nucl
Chem 283:845-849
49.
Šťastná K, Fiala V, John J (2010) J Radioanal
Nucl Chem 268:735-739
50.
Hecke Van K, Modolo G (2004) J Radioanal
Nucl Chem 261:269-275
51.
HYBAR-08 (2012) KIT-INE
52.
Lewis FW, Harwood LM, Hudson MJ, Drew
GB, Wilden A, Sypula M, Modolo G, Vu T-H,
Simonin J-P, Vidick G, Bouslimani N, Desreux
JF (2012) Procedia Chem 7:231-238