NOVEL EXTRACTION CHROMATOGRAPHIC RESINS BASED ONTETRAALKYLDIGLYCOLAMIDES: CHARACTERIZATION AND POTENTIALAPPLICATIONS
E. P. Horwitz*, D. R. McAlister, A. H. Bond, and R. E. Barrans, Jr.
PG Research Foundation, Inc., 8205 S. Cass Ave., Suite 106, Darien, IL 60561
ABSTRACT
Two new extraction chromatographic resins containing the diglycolamide class ofmolecules have been prepared, characterized and potential applications identified. The
new resins consist of 40 weight percent N,N,N′N′ tetraoctyldiglycolamide (TODGA) and
N,N,N′N′ tetrakis-2-ethylhexyldiglycolamide (TEHDGA) sorbed onto 50-100 µm particle
size Amberchrom® CG-71. The new resins have capacities for Eu of approximately
0.086 mmol/mL of bed and are quite stable to extractant leaching. The resins werecharacterized by measuring the batch uptake of actinides, lanthanides and yttrium,
alkaline earths and thirteen selected transition and post-transition elements from HNO3
and HCl. Based on the uptake data, a number of very efficient separations were achieved
using 0.5 to 2mL bed volume columns and room temperature operation.
Key words: Diglycolamide, Extraction Chromatography, Actinide and Lanthanide
Selectivities and Separations, Alkaline Earth Separations
INTRODUCTION
The extraction of trivalent actinides, particularly Am, from acidic nitrate media
has been the focus of many studies during the last 15 to 20 years. These studies have been
motivated by the need to develop processes for the treatment of high-level radioactive
waste (HLW) for disposal. A summary of solvent extraction processes developed up to
1999-2000 for the treatment of HLW is described in detail in (1) and references therein.
______________________* author for correspondenceRecently, a number of studies by Sasaki et al, (2-6) have described a class of extractants,
based on tetraalkyldiglycolamides, that show unusually effective extraction of trivalentactinides and lanthanides from nitric acid. The tetra-n-octyl derivative (TODGA) appears
to have the most favorable combination of properties (7) and has been the focus of further
study (8-10).
Recently, two studies have appeared that utilize TODGA as the stationary phasein extraction chromatographic (EXC) systems (11, 12). These references are directed at
the recovery of actinides and lanthanides from simulated low-level waste (LLW) andsimulated HLW, respectively. We also reported in 2004 on two new EXC resins
containing diglycolamides that confirmed the high uptake of Am and lanthanides from
HNO3 as well as HCl (13).
Our objective in this paper is to further evaluate the properties of EXC resins
employing TODGA and the tetra-(2-ethyl-1-hexyl)-DGA derivative (TEHDGA) as thestationary phase. We selected for study not only Am, lanthanides, and yttrium, but alsoTh(IV), U(VI), Pu(IV), alkaline earths and selected transition and post transition element
cations. Our purpose in this study was to primarily identify applications for these resins
other than in nuclear waste treatment.
EXPERIMENTAL
Synthesis
The tetraalkyldiglycolamides were synthesized by reaction of diglycolyl
chloride with dialkylamines and triethylamine in tetrahydrofuran (THF). All
chemicals were purchased from Aldrich and used as received, except for thetriethylamine that was freshly distilled from calcium hydride before use. All water
was deionized using a commercial purification system. All glassware was oven-driedprior to use and the reaction was carried out at ~23°C. A positive pressure inert
atmosphere of nitrogen was maintained with a latex balloon and the reaction mixture
was stirred magnetically. Reactions on a larger scale required mechanical stirringbecause of the large amount of triethylammonium chloride precipitate that formed. A
500-mL single-neck round bottom flask was charged with anhydrous (THF) (120 mL)
and diglycolyl chloride (15.0 mL, 126 mmol) and partially immersed in a water bathto dissipate the small amount of heat produced by the reaction. A dropping funnel
was charged with dioctylamine, bis(2-ethyl-1-hexyl)amine or didecylamine (235–250mmol) and triethylamine (37.2 mL, 265 mmol) in anhydrous THF (60 mL). The
amine solution was added dropwise to the diglycolyl/THF mixture over a period of
about 1.5 h. A white precipitate of triethylammonium chloride immediately formed
upon combining the solutions. After addition of the amine solution was complete, thedropping funnel was rinsed with an additional 10 mL THF, which was added to thereaction mixture. The mixture was stirred for an additional 1 h, after which 10 mL
H2O was added. The THF was subsequently removed by rotary evaporation, leaving ayellow residue.
To the yellow residue was added 100 mL of H2O, creating a viscous orange
upper phase and a colorless, cloudy lower phase. The phases were disengaged in a
separatory funnel and the lower phase was extracted twice with 10 mL petroleum
ether. The petroleum ether washes were added to the initial upper phase and extractedwith 15 mL H2O, 2 x 15 mL 1 M HCl, 15 mL H2O, and 6 x 20 mL 5% (w/w)
NaHCO3. The lower phases from the NaHCO3 extractions appeared to be emulsions
and were discarded. The upper phase was extracted with 10 mL 1 M HCl, 2 x 10 mL
H2O, and 25 mL saturated NaCl, dried over anhydrous MgSO4, filteredgravitationally through fluted paper, and concentrated by rotary evaporation.
The purified final products were characterized by 1H NMR and highperformance liquid chromatography-mass spectrometry (LC-MS). The 1H NMR
characterization was performed on a Varian Inova 500 MHz NMR spectrometer.
Chemical shift values are reported relative to an internal trimethylsilane (TMS)
standard. LC-MS characterization was performed on an API 150EX LC-MS
instrument with a single quadrupole mass spectrometer using a 100 mm x 4.6 mm 5µm particle size Luna C18(2) column (Phenomenex) and a mobile phase of 80:20(v:v) CH3CN : H2O.

N,N,N′N′-tetra-(1-octyl)-3-oxapentane-1,5-diamide, TODGA, F.W.: 580.98. This
compound was obtained as an orange oil in 94% yield. 1H NMR (CDCl3, δ relative to
TMS): 4.307 (s, 4 H); 3.291 (t, 4 H, J = 8.0 Hz); 3.177 (t, 4 H, J = 8.0 Hz); 1.519 (m,8 H); 1.272 (br, 40 H); 0.885 (t, 6 H, J = 6.0 Hz); 0.876(t, 6 H, J = 6.0 Hz). LC-

MS: 3.6 min (2%, m/z 358.2, calcd. for O[CH2C(O)N(C8H17)(H)]2, C20H40N2O3·H+:
357.52); 4.1 min (1%, m/z 469.3, calcd. for(H)(C8H17)NC(O)CH2OCH2C(O)N(C8H17)2, C28H56N2O3·H+: 469.73); 4.5 min (96%,m/z 581.4, calcd for O[CH2C(O)N(C8H17)2]2, C36H72N2O3·H+: 581.99).
N,N,N′N′-tetrakis-(2-ethyl-1-hexyl)-3-oxapentane-1,5-diamide, TEHDGA, F.W.:
580.93. This compound was obtained as a light yellow oil in 94% yield. 1H NMR(CDCl3, δ relative to TMS): 4.330 (s, 4 H); 3.370 (m, 4 H); 3.043 (d, 4 H, J = 7.0 Hz);1.669 (m, 3 H); 1.560 (m, 3 H); 1.250 (m, 30 H); 0.880 (m, 24 H). LC-MS: 3.6 min(1%, m/z 413.1, calcd for (C2H5)2NC(O)CH2OCH2C(O)N(C8H17)2, C24H48N2O3·H+:
413.62; 4.5 min (91%, m/z 581.4, calcd. for O[CH2C(O)N(C8H17)2]2, C36H72N2O3·H+:
581.99); 5.5 min (8%, m/z 920.4, calcd. for (HO)C(O)CH2OCH2C(O)N(C8H17)2 +O[CH2C(O)N(C8H17)2]2, C56H111N3O6·H+: 923.43).
N,N,N′N′-tetra-(1-decyl)-3-oxapentane-1,5-diamide, TDDGA, F.W.: 693.19. This
compound was obtained as a white waxy solid in 72% yield. 1H NMR (CDCl3, δrelative to TMS): 4.300 (s, 4 H); 3.289 (t, 4 H, J = 7.7 Hz); 3.171 (t, 4 H, J = 7.7 Hz);1.517 (m, 8 H); 1.260 (br, 56 H); 0.883 (t, 6 H, J = 7.0 Hz); 0.878 (t, 6 H, J = 7.0 Hz).
LC-MS: 3.3 min (2%, m/z every 44 amu from 532.2 to 796.2); 4.6 min (2%, m/z
581.4, calcd. for (C2H5)(C10H21)NC(O)CH2OCH2C(O)N(C10H21)2, C36H72N2O3·H+:
581.93); 5.4 min (95%, m/z 693.5, calcd. for O[CH2C(O)N(C10H21)2]2,
C44H88N2O3·H+: 694.20).
Preparation of Extraction Chromatographic Materials
The extraction chromatographic materials containing N,N,N′N′-tetra-(1-octyl)-3oxapentane-1,5-diamide (TODGA) or N,N,N′N′-tetrakis-(2-ethyl-1-hexyl)-3-oxapentane-1,5-diamide (TEHDGA) were prepared using a general procedure described previously(14, 15). A portion of TODGA or TEHDGA (4.0 g) was dissolved in about 30 mL of
CH3OH and combined with a slurry of 50-100 µm Amberchrom®-CG71 (6.0 g)(Eichrom Technologies, Inc.) in about 20 mL of CH3OH. The mixture was swirled tomix, and the methanol was removed by rotary evaporation at reduced pressure at 50 oC.
After condensate ceased to collect and no further bubbling was observed from the freeflowing solid, the resin was rotated under full vacuum at 40-50 oC for another 30 min toremove residual CH3OH. The resulting solid corresponds to 40% (w/w) loading ofextractant on 50-100 µm Amberchrom-CG71 (40 weight percent loading assumes 100%
purity of extractant). The resins are now commercially available from Eichrom
Technologies, Inc. as DGA Resin, normal (TODGA) and DGA Resin, branched(TEHDGA).
Analytical Reagents
Nitric and hydrochloric acid solutions were prepared from Trace Metal Gradeacids (Fisher Scientific) and deionized water obtained from a Milli-Q2 water purification
system. The radionuclides 85Sr, 90Sr, 133Ba, 139Ce, 147Pm, 152Eu, 207Bi, 226Ra, 230Th, 239Pu
and 241Am were obtained from Isotope Product Laboratories. 225Ac was provided by
MedActinium, Inc. and was separated from 229Th stocks at Oak Ridge National
Laboratory. 212Pb was milked from 228Th adsorbed onto a column of TRU Resin(Eichrom Technologies, Inc.) with 4 M HNO3. Residual 224Ra was removed using Sr
Resin (Eichrom Technologies, Inc.) to selectively retain the 212Pb. The 212Pb was strippedfrom the Sr Resin using 0.1 M ammonium oxalate, evaporated to dryness on a hotplate at~300oC (to destroy the ammonium oxalate) and dissolved in 0.5 M HNO3. 90Y wasmilked from 90Sr adsorbed onto a column of Sr Resin using 4 M HNO3. A secondary
column of Sr Resin was used to scavenge any 90Sr that may have channeled through thefirst Sr Resin column. The 90Y was evaporated to dryness and dissolved in 0.5 M HNO3
prior to use in batch uptake or column elution experiments. Metal ion solutions for ICPAES experiments were prepared from 1000-10,000 ppm standard solutions in nitric acid
(Al, Ba, Ca, Ce, Co, Cu, Dy, Er, Eu, Fe, Gd, Ho, La, Lu, Mg, Nd, Ni, Pr, Sm, Sr, Tb, Th,Tm, U, Y, Yb, Zn, Zr), hydrochloric acid (Cu, Ti, V) or water (Be, Cr, Nb) (Fisher
Scientific).
Batch Uptake of Metal Ions
The uptake of metal ions by the DGA resins from acidic solutions was measured
by contacting a known volume of solution (1.0 mL for radiotracer experiments and 5.07.5 mL for ICP-AES experiments) with a known weight of resin (10-20 mg forradiotracer experiments and 100-300 mg for ICP-AES experiments) in a borosilicate
glass culture tube. All experiments were performed at 22(1)oC using 50-100 µm particle
size resin. The exact ratio of resin to aqueous phase was varied to produce a measurable
difference in the initial and final activities (concentrations) of metal ion in the aqueous
phase and to ensure that the molar ratio of extractant to metal ion was at least 50:1. The
mixing of resin and the aqueous phase was performed by intermittent agitation on avortex mixer and by using a small magnetic stir bar rotated at a speed sufficient to keep
the resin beads suspended in the aqueous phase. Following equilibration with the resin,
the aqueous phase was filtered through a 0.45 µm PTFE syringe filter to remove any
resin particles.
A model E5003 Packard Cobra Autogamma counter, was used to assay for 85Sr,
Ba, 139Ce, 152Eu, 212Pb, 225Ac(221Fr) and 241Am. The radiotracers 90Y, 147Pm, 207Bi,

133
226

Ra, 230Th and 239Pu were measured on a Packard TriCarb 2550 TR/AB liquid

scintillation counter using Ultima Gold scintillation cocktail. Metal ion concentrations forall other elements were determined by inductively coupled plasma atomic emission
spectroscopy (ICP-AES) on a Varian Liberty Series II sequential inductively coupledplasma atomic emission spectrometer using the parameters listed in Table 1. The uptakeof the entire series of lanthanides (excluding Pm) and Y were determined from threestock solutions: 1) Eu, Er, Pr, Sm, Tm and Y; 2) Eu, Ce, Gd, Lu, Tb and Yb; 3) Eu, Dy,
Ho, La and Nd, as outlined in (16). Europium was employed as a common standard ineach lanthanide stock solution. The free column volume to peak maximum (k′) values for
Eu determined using each stock solution agreed within 5%, except for the highest acidconcentrations, where the aqueous phase was nearly completely depleted of metal ionsfollowing equilibration with the DGA resin and error between measurements was
substantially higher. The k' for macroscopic quantities of Eu measured by ICP-AES also
agreed within 5% of the k' value obtained using a 152Eu tracer. However, k′ values
obtained at tracer scale (radiometric) and using macroquantities of metal ions (ICP-AES)
can differ by as much as ±20% due to the consumption of resin capacity whenmacroquantities of metal ion are present. All comparisons of the uptake of different metal
ions were therefore made between k′ values obtained at the same scale, tracer or macro,
when possible. Preliminary experiments showed that the uptake of 152Eu approachedequilibrium after 10 minutes. An equilibration time of one hour was used in all
determinations of weight distribution ratios.
Weight distribution ratios (Dw) were calculated using the following equation:
Dw = [(Ao-As)/w]/(As/V)(1)

where Ao and As are the aqueous phase metal ion concentrations (parts per million) or
activity (counts per minute) before and after equilibration, w is the weight of the resin ingrams and V is the volume of aqueous phase in milliliters. Duplicate experiments showedthat the reproducibility of the Dw measurements was generally within 10%, although theuncertainty was somewhat higher for the Dw values >103. The Dw values were converted
to the number of free column volumes to peak maximum, k′ (the resin capacity factor),by first calculating the volume distribution ratio (Dv, a value calculated from equation 1
in which the weight of the resin, w, is replaced by the volume of extractant) using thefollowing equation:
Dv = Dw x dextr/0.4(2)where dextr is the density of the extractant and 0.4 is the extractant loading in grams ofextractant per gram of resin. The Dv values were then converted to k′ by using thefollowing equation:k′ = Dv x (vs/vm)(3)where vs and vm are the volumes of stationary phase (extractant) and mobile phase,respectively, for a slurry packed column of DGA Resin. The physical constants necessary
to convert Dw to k′ for slurry packed columns of 50-100 µm particle size DGA Resin in
0.1 M HNO3 are listed in Table 2. The bed density for dry packed columns is somewhat
higher than for slurry packed columns, so k′ values for dry packed columns are ≈ 5%
higher than corresponding values for slurry packed columns. By combining equations (2)and (3) and using the values reported in Table 2 for dextr and vs/vm, one obtains:k′ = Dw x 0.57

(4)Thus, for each weight distribution ratio measured on DGA Resin, the corresponding k′value can be obtained by multiplying the Dw value by 0.57.
Column Elution of Metal Ions
Column chromatographic experiments were performed with slurry-packed
columns of the DGA resins. The resin was slurried by gently swirling or vortexing theresin in 0.1 M HNO3. However, the DGA resins frequently floated on top of the HNO3
solution and did not appear to wet readily. Since wetting of the EXC material is critical tooptimal chromatographic performance, methods to better wet the DGA resins were
explored. Placing the resin into a sealed container and equilibrating with 0.1 M HNO3
over an extended period of time (2-3 h or even overnight) was found to effectively wet
the resin. Sonication and occasional swirling of the resin/HNO3 mixture and increasing
the concentration to 1-2 M HNO3 helped to speed the wetting of the resin. Additionally,
the application of weak vacuum pressure helped to remove air bubbles and facilitate thewetting of the resin. Even after the above measures were taken, a small portion of the
DGA resin did not appear to wet and floated on top of the nitric acid solution. This
portion of the resin was not used to pack the chromatographic columns. The slurried,wetted resin was packed into polypropylene or glass chromatographic columns (BioRad)with 10 mm inner diameters. Medium porosity polyethylene frit material (Fisher
Scientific) was used for the bottom and top bed supports.
The slurry-packed columns of DGA resin were then preconditioned with 5 bed
volumes of the desired load solution free of metal ions, and solutions of metal ions were
subsequently eluted through the column at a flow rate of 1-2 mL/min (1.3-2.5
mL/cm2/min). Flow rates were either gravity or adjusted by over-pressure applied bysyringe. Aliquots of the eluate were collected into tared polypropylene gamma counting
tubes, 7 mL liquid scintillation vials or 15 mL polypropylene centrifuge tubes andanalyzed for metal ions as described above.
Metal Ion Capacity
The capacity of the TODGA and TEHDGA resins were determined by loading a
0.5 mL slurry packed column of the resin with a solution of 0.0274 M Eu in 4.0 M HNO3
spiked with 152Eu. Loading was continued until the concentration of Eu in the effluent
was the same as the concentration of Eu in the load. The column was then rinsed with 5
bed volumes of 4.0 M HNO3, stripped with 0.1 M HCl and aliquots of the eluate
collected into tared polypropylene gamma counting tubes. The resin capacity wasdetermined from the 152Eu activity depleted from the load fractions and from the 152Eu
activity recovered in the strip fractions. The two capacity determinations agreed within
5%.
Resin Leaching
The leaching of the TODGA and TEHDGA extractants from the extraction
chromatographic materials was studied by passing large volumes of 6 M HNO3, 0.1 M
HNO3 and 0.1 M HCl through 12 mL bed volume columns of the DGA resin (1.0 cm
internal diameter, 15.3 cm bed height) at 25oC and 50oC to simulate typical load, rinseand strip conditions. The resin was slurry packed into a jacketed 30 mL column (Ace
Glass) and medium porosity polyethylene frit material was used for the bottom and top
bed supports. The temperature of the column was maintained using a circulating

water/ethylene glycol bath. A peristaltic pump was used to achieve a flow rate of 11
mL/min (14 mL/cm2/min) and aliquots of the eluate were collected into glass roundbottom flasks. The eluate was extracted with 3 x 2 mL of CH2Cl2. The CH2Cl2 extracts
were then washed with 5 mL of H2O, and the H2O washes later extracted with 2 x 2 mL
of CH2Cl2. The combined CH2Cl2 extracts were then dried over anhydrous MgSO4 andevaporated to dryness on a rotary evaporator. The leachate residue was submitted for LCMS analysis as described in the synthesis section above. N,N,N′,N′-tetra-(1-decyl)-3oxapentane-1,5-diamide was used as an internal standard for the quantitation of DGA in
the leachates by LC-MS.
RESULTS AND DISCUSSION
Kinetics of Uptake of Eu on TODGA
Figure 1 depicts the kinetics of uptake of tracer-level Eu(III) from 3 M HNO3 atroom temperature by TODGA resin. It can be seen that equilibrium is essentially reachedwithin 10 minutes, which is consistent with kinetics data reported for a similar TODGAEXC resin (11) and generally consistent with prior kinetic data reported for other EXC
resins studied by Horwitz et al (14). (The variation in k' after 25 minutes is within
experimental error.)
Nitric and Hydrochloric Acid Dependencies of Capacity Factor, k'Comparison with TRU-EXC resin
Figures 2 and 3 compare the uptake, as measured by k', of selected actinides as afunction of nitric and hydrochloric acid for TRU-, TODGA-, and TEHDGA-EXC resins.
TRU Resin contains 40 weight percent of a solution of 0.75 M CMPO in undiluted TBPsorbed onto Amberchrom® GT-71. The data for the TRU Resin is from (15). The
difference in the DGA and TRU Resins is striking. For TRU Resin, the order of uptake istypical of a neutral hard donor extractant containing a phosphoryl oxygen; that is, tetra- >hexa- > tri-valent. In comparison to TRU Resin, the uptake of U(VI) is significantly
suppressed and the uptake of Am(III) significantly enhanced relative to each other and toTh(IV) and Pu(IV) for both DGA resins. The k′Am values for the DGA resins are ordersof magnitude higher than those of TRU Resin above one molar acid concentrations. A
comparison of the uptake of Am with that of Th and Pu is also noteworthy. With TRU
Resin, the k' values for Th and Pu are orders of magnitude greater than the k' of Am, but
in the case of the DGA resins, the k's of tri- and tetra-valent actinides above 0.5 M acidare much closer. This is especially the case at high nitric acid concentrations. In general,our data are consistent with data reported for similar EXC resins in (11,12) where valid
comparisons can be made.
The differences between the TRU and DGA resins lay in the number of donor
oxygens and the configuration of the extractant. As described in (17, 18), thecarbamoylmethylphosphoryl group acts as a monodentate ligand with metal ions at thetracer-scale level. The DGA group has been shown to be tridentate in configuration (2-6),
complexing trivalent metal ions through two carbonyl oxygen donors and an ether
oxygen donor forming two stable five-membered chelate rings. Although the carbonyl
oxygen is less electronegative than a phosphoryl oxygen, the coordination of DGA to a
tri-positive actinide probably involves less liquid strain and/or rearrangement, which may
compensate for the lower electron density of the donor groups in DGA. The higher
extraction constants of the DGA class of extractants compared to the corresponding
bifunctional malonamide extractants (7) is also noteworthy and supports the importanceof the tridentate coordination of the DGA. Based on the data in Figures 2 and 3, thecoordination of a tridentate DGA to uranyl ion appears significantly less favorable thancoordination to a trivalent or tetravalent actinide.
An interesting feature of the data for DGA-EXC resins shown in Figure 2 is thelack of the so-called hyperstoichiometry (sixth power HNO3 dependency) observed fortrivalent f-element cations when extracted by TODGA in a liquid-liquid extraction
system (19). Nitric and hydrochloric acid dependencies are closer to second and third
power for the EXC system; however, comparisons between EXC and conventionalliquid-liquid extraction frequently show such significant differences. This is not
surprising when one takes into consideration that the thickness of an extractant sorbed

onto a porous solid support having a surface area of 400-500 m2/g (e.g. Amberchrom®
CG-71m) containing 40 weight percent of an extractant with a density of 0.8-0.9 g/mL, isonly about 1-2 x 10-3 µm. Furthermore, the stationary phase in EXC systems is frequently
a neat extractant. Thus, the physical and chemical properties, such as aggregation andmetal ion/extractant stoichiometry, in EXC systems may deviate from those of thecorresponding liquid-liquid extraction systems.
The data in Figures 2 and 3 also show that the EXC resin using the stericallyhindered TEHDGA extractant has lower uptake of actinides in both HNO3 and HCl,
except at the highest acid concentrations, where the differences are minimal. Uptake ofcations by TODGA and TEHDGA are lower from HCl than from HNO3, which isconsistent with the behavior of neutral extractants, i.e., nitrato complexes are usually (butnot always) more extractable than chloro complexes (15). A clear comparison of TODGA
and TEHDGA for Am(III) in both HNO3 and HCl is depicted in Figure 4.
In general, the TODGA resin gives higher uptakes and is more selective than
TEHDGA, as will be shown below for other metal ion systems. The data in Figures 2-4
suggest the conditions for a number of novel and practical chromatographic separationsof actinides. These separations will be shown and discussed in a later section of thismanuscript.
Comparison of lanthanides, yttrium and americium
Figures 5 and 6 compare the HNO3 and HCl dependencies of Ce, Eu and Y withamericium for both TODGA and TEHDGA resins. The HNO3 data are consistent withthe results reported for TODGA in (6,11,12). As expected, the uptake of Am is similar tothe lanthanides and close to the uptake of Eu. The data in Figures 5 and 6 again
demonstrate that one obtains higher k's and higher selectivity with TODGA and higher
k's and selectivity for both TODGA and TEHDGA from HNO3 versus HCl.
Figure 7 shows k's obtained for the entire lanthanide series and yttrium by
TODGA resin from 0.5 M and 0.05 M and by TEHDGA resins from 1.0 M. The data in
Figure 7 for the TODGA resin approximately parallels the liquid-liquid extraction data
for the TODGA-dodecane system reported in (6) where selectivity changes very little

among the heavy lanthanides. However, the selectivity obtained with the TODGA resin
for La through Gd from 0.05 M HNO3 is noteworthy and actually slightly higher than theselectivity obtained for the same lanthanides using an extraction chromatographic
material containing bis(2-ethyl-1-hexyl)phosphoric acid (HDEHP) (20). The trend in k's
may be explained by a combination of electrostatic and steric effects. From atomic
numbers 57 to 66 electrostatic effects appears to dominate whereas above Z = 66, thedecreasing ionic radii of the lanthanide cation introduces a steric issue that levels the k'values.
Alkaline earths, strontium and yttrium
Figure 8 shows the HNO3 and HCl dependencies for the entire series of alkaline
earth cations, Be through Ra. Most of the alkaline earth cations show negligible uptake,especially from HCl, however, the retention of Ca and Sr from 0.5 M to 3 M HNO3 issignificant. Reference 8 reports similar behavior for the corresponding liquid-liquid
extraction system. The trend in k' (Ca>Sr>Ba) may be explained by the fact that the
cation with the smaller ionic radius is more readily complexed by the TODGA, as wasobserved with the lanthanides. The lower uptake of Be and Mg is likely a continuation ofsteric effects and the inability of the donor groups in DGA to dehydrate Be2+ and Mg2+,
which have much higher hydration energies than Ca2+, Sr2+, and Ba2+. Although theuptake of Ca and Sr is not particularly strong relative to the lanthanides, the k' values are
sufficiently high to enable one to achieve some novel separations. An example of such a
separation will be shown in a later section.
The separation of Y from Sr is a frequently performed separation because of the
production of 90Y from 90Sr for application in nuclear medicine. Figure 9 depicts theconditions in which TODGA resin could be utilized to carry out this separation.
Selected transition and post transition elements
Figure 10 shows the nitric and hydrochloric acid dependencies of selectedtransition and post transition elements with TODGA resin. The elements selected for thisstudy are those that most likely could be present in matrices of environmental or nuclear
waste samples. The behavior of Al and Fe in nitric acid is particularly noteworthy
because of their frequent presence in soil samples. The low uptake of both Al and Fe by
TODGA can be exploited in a number of actinide separations. An example will be
described below.
Column Studies
Column capacity
The calculated capacity of a slurry-packed column (packing density 0.38g/mL)
containing 40 weight percent of 94% pure TODGA or TEHDGA is 0.246 mmol ofextractant per mL of bed. The measured capacity for a trivalent actinide, using Eu(III) asa stand-in for Am(III), was 0.077 and 0.095 mmol of Eu/mL of bed for TODGA andTEHDGA, respectively. These Eu capacities represent approximately a 3 to 1
stoichiometry. Solvent loading studies reported by Tachimori et al (9) using Nd in 3 M
HNO3 and the liquid-liquid extraction system TODGA-dodecane in the presence of a
monoamide, N, N-dihexyloctanamide (to prevent third phase formation) also gave a 3 : 1
stoichiometry.
Actinide separations
Figure 11 shows an efficient separation of U, Pu and Am in the presence of 0.45
M Fe(III) using a 2.0 mL TODGA column. The conditions used for the separation werebased on the uptake data in Figures 2, 3 and 10. Although the recovery of uranium was
82% in the presence of 250 mg of Fe(III), the recovery of uranium improved to over 90%
when the Fe(III) concentration was < 100 mg. The difference in the k's of Am and Pu at
low acidity was exploited in performing their separation. Plutonium can also be
efficiently eluted with dilute HCl or HNO3 – HF mixtures. Another, perhaps more
efficient way to use the TODGA column, is to precede the TODGA column with a TEVA
resin column. The TEVA resin, which contains a quaternary amine, selectively removes

all tetravalent actinides and rejects Am and U (14). TEVA resin is also insensitive tomacroconcentrations of Fe(II) and Fe(III). Individual columns can be coupled together
on loading and rinsing, then separated for stripping. In this manner, the TODGA is used
to remove U and Am from the matrix constituents and then to separate U and Am fromeach other by selective elution as shown in Figure 11.
Another potential application of the DGA resins is in the recovery of 241Am fromlarge volumes of concentrated HNO3 and HCl wastes. For example, a frequently used
procedure to purify Pu is by anion exchange in 7 to 8 M HNO3, in which small quantitiesof 241Am are present from the decay of 241Pu. The 241Am is not retained by the anionexchange resin and, therefore, passes with the HNO3 effluent. Figure 2 shows that bothTODGA and TEHDGA resins retain Am from high nitric acid concentrations. Dilute HClmust be used to efficiently strip Am from TODGA resin (see Figure 11), but dilute HNO3
can be used to strip Am from TEHDGA resin. Figure 12 shows the concentration profiles
for the elution of Am from a 0.50 mL TEHDGA column using dilute HNO3. The Am wasinitially loaded from 10 mL (20 B.V.) of 7 M HNO3. Clearly, the 0.01 M HNO3 elutes the
Am more efficiently than the 0.1 M HNO3. The elution of Eu showed similar behavior.
The broad elution curve obtained with 0.1 M HNO3 is most likely due to slow kinetics
but we have no explanation why this phenomenon occurs under these conditions. Other
acids, such as formic or acetic acid can be used to efficiently strip Am from either
TODGA or TEHDGA.
Radium/actinium separation
The separation of Ra from Ac is frequently performed in the analysis of 228Ra andin the purification of 225Ac for the preparation of 213Bi generators. Although the HNO3
and HCl dependencies of Ac(III) were not measured, the extraction of Ac follows that of
La and Ce for acidic organophosphorus extractants, but is generally a factor of 2 to 3
times lower (21). Therefore, the conditions for separating Ac from Ra using either
TODGA or TEHDGA resins can be ascertained from the data in Figures 5 and 8. Figure
13 shows an efficient separation of 226Ra (a stand-in for 225Ra) and 225Ac using only a 0.5
mL bed volume column. Total separation time was 5 minutes. The load solution was theeffluent from a UTEVA column (diamyl amylphosphonate on Amberchrom® CG-71)
used to remove 229Th parent and any trace quantities of 233U.
Strontium/yttrium separation
An earlier publication by Horwitz, et al described the use of a strontium selective
resin for the isolation of 90Y from multicurie quantities of 90Sr (22). In this process the90

Y is recovered from the Sr selective resin in 5 M HNO3 and then put through a final

step using TRU Resin in which the 90Y is concentrated and further purified. Figure 14
shows a particularly effective concentration and recovery of 90Y from 5 M HNO3 using
TODGA resin. The 90Y is recovered in dilute HCl which is the preferred medium for
subsequent processing procedures. In addition to the concentration and recovery of the90

Y, additional decontamination from 90Sr and many other possible trace contaminants(e.g., Fe) is achieved.
The chemistry of Sr and Y on the DGA resins and the Sr selective resin is an
example of selectivity inversion; that is, in the former case Y is selectively retained andin the latter case, Sr is selectively retained. By using two such columns sequentially,
selectivity inversion can be exploited to achieve multiplication of decontamination
factors to conveniently give very high purity analytes (23).
The TODGA and TEHDGA resins can also be used to separate 90Y from macro
quantities of Sr. Figure 15 shows the separation of 90Y from a load solution of low
specific activity 90Sr. In this experiment, the quantity of Sr (250 mg) exceeded thecapacity of the column for Sr by a factor of 30. The figure clearly shows that the 90Y is
effectively removed and decontaminated from the Sr and efficiently recovered in dilute
HCl.
Calcium and strontium separation
Figure 16 depicts a most unusual separation in which Sr and Ca are separated
from all other alkaline earths and then selectively eluted from each other. This separation
validates the uptake data shown in Figure 8. In addition to achieving the separation

depicted in Figure 16, the same column run conditions could be used to separate Sr and
Ca from a host of other metals; for example, Fe, Al, Ni, Co, Cu, Zn and Pb (see Figure10).
If one is interested only in purifying Ca, a selectivity inversion system could be
used in which the TODGA resin column is preceded by a Sr resin column. Calcium is notretained by Sr Resin in 4 M HNO3, but Sr and Pb are strongly retained. The load andrinse effluent from the Sr Resin column is loaded onto the TODGA resin column and thebalance of the separation proceeds as shown in Figure 16. The selectivity inversion
system would produce a Ca fraction more highly purified from Sr and Pb than would beobtained by a single TODGA column run.
Column stability
Table 3 summarizes the results of leaching experiments carried out with 12 mL
bed volume columns packed with TODGA and TEHDGA resins. Both resins
demonstrated very low levels of extractant leaching; however, duplicate runs showed
fluctuations and in most cases the results shown in Table 3 represent the average of two
or more determinations. In no case was extractant loss greater than 3 x 10-4% per bed
volume. Elevating the temperature to 50°C did not appear to have any significant effecton extractant loss. The presence of incomplete alkylation products mentioned in theexperimental section were not detected in the leachates. The high stability of the DGA
resins with respect to extractant loss shows that such columns could be used a number oftimes without a major diminution in capacity.
CONCLUSION
The liquid extractants N,N,N′N′ tetraoctyl-1,5-diglycolamide (TODGA) and
N,N,N′N′ tetrakis-(2-ethyl-1-hexyl)-1,5-diglycolamide (TEHDGA) sorbed on
Amberchrom® CG71 produces excellent extraction chromatographic resins. Forty weightpercent of the extractants sorbed onto 50-100 µm particle size polyacrylate polymer
beads forms EXC resins with a good capacity and an unusually high stability with regards

to extractant leaching. The most noteworthy chemical property of the resins is their highuptake of trivalent actinides and lanthanides from high concentrations of HNO3 and HCl
acids. Although the uptake of tetravalent actinides is comparable to that of trivalentactinides especially at high HNO3 concentrations, the retention of uranyl ion is marginal.
The insensitivity of the uptake of actinides and lanthanides to common elements present
in soil and water; for example, Fe, is an important property of the DGA resins.
We believe that the major application of the resins is primarily in analyticalchemistry and in the purification of radionuclides for use in nuclear medicine. The highselectivity of TODGA resin shown for lanthanides from La through Dy could be
exploited to separate adjacent lanthanides. Most likely, a smaller resin size and longer
columns would be required. The versatile DGA resins can be of particular value whenused in conjunction with other EXC resins to perform multiple radionuclide separations
using the selectivity inversion concept. Application of the resin in the treatment ofradioactive waste is also a possibility but stability to radiation and leaching over a periodof time is a major issue which would need to be studied. Both resins are commerciallyavailable from Eichrom Technologies, Inc as DGA Resin, normal (TODGA) and DGA
Resin, branched (TEHDGA).

References:
1. Horwitz, E.P.; Schulz, W.W. Solvent Extraction in the Treatment of Acidic HighLevel Liquid Waste: Where do We Stand? in “Metal Ion Separation andPreconcentration: Progress and Opportunities,” Bond, A.H.; Dietz, M.L.; Rogers,
R.D.; Editors, ACS Symposium Series 716, American Chemical Society,
Washington, D.C., 1999, 20-50.
2. Sasaki, Y.; Choppin, G.R. Solvent extraction of europium, thorium, uranium,
neptunium and americium with N,N′-dimethyl-N,N′-dihexyl-3-oxapentanediamide
and its analogous compounds. Anal. Sci. 1996, 12, 225-230.
3. Sasaki, Y.; Choppin, G.R. Extraction behaviors of Eu, Th, U and Am withdiamides + thenoyltrifluoroacetone, J. Radioanal. Nucl. Chem. 1996, 207, 383-394.
4. Sasaki, Y.; Choppin, G.R. Extraction of Np(V) by N,N′-dimethyl-N,N′-dihexyl-3oxapentanediamide. Radiochim. Acta. 1998, 80, 85-88.
5. Sasaki, Y.; Choppin, G.R. Extraction and mutual separation of actinide(III), (IV)and (VI) ions by N,N′-dimethyl-N,N′-dihexyl-3-oxapentanediamide andthenoyltrifluoroacetone, J. Radioanal. Nucl. Chem. 2000, 246, 267-273.
6. Sasaki, Y.; Sugo, Y.; Suzuki, S.; and Tachimori, S. The novel extractants,
diglycolamides, for the extraction of lanthanides and actinides in HNO3-n-dodecane
system, Solvent Extr. Ion Exch. 2001, 19, 91-103.
7. Sasaki, Y.; Tachimori, S. Extraction of actinides(III), (IV), (V), (VI) andlanthanides(III) by structurally tailored diamides, Solvent Extr. Ion Exch. 2002, 20,
21-34.
8. Tachimori, S.; Suzuki, S.; Sasaki, Y.; Apichaibukol, A. Solvent extraction ofalkaline earth metal ions by diglycolic amides from nitric acid solutions, Solvent Extr.
Ion Exch. 2003, 21, 707-715.
9. Tachimori, S.; Sasaki, Y.; Suzuki, S. Modification of TODGA-n-dodecane solventwith a monoamide for high loading of lanthanides(III) and actinides(III), Solvent
Extr. Ion Exch., 2002, 20, 687-699.
10. Sugo, Y.; Sasaki, Y.; Tachimori, S. Studies on hydrolysis and radiolysis of
N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide, Radiochim. Acta. 2002, 90, 161-165.
11. Van Hecke, K.; Modolo, G. Separation of actinides from low level liquid
wastes(LLLW) by extraction chromatography using novel DMDOHEMA andTODGA impregnated resins, J. Radioanal. Nucl. Chem. 2004, 261, 269-275.

12. Hoshi, H.; Wei, W.-Z.; Kumagai, M.; Asakura, T.; Morita, Y. Group separationsof trivalent minor actinides and lanthanides by TODGA extraction chromatography
for radioactive waste management, J. Alloy Compds. 2004, 374, 451-455.
13. Horwitz, E.P.; Bond, A.H.; Barrans, Jr., R.E.; McAlister, D.R.; Jassin, L.E.;
Thakkar, A.H.; Williamson, J.M. New extraction chromatographic resins for recovery
of TRUs and lanthanides from acidic and nitrate and chloride wastes. 227th American
Chemical Society National Meeting, Anaheim, CA, March 28-April 1, 2004, IE&C226.
14. Horwitz, E.P.; Dietz, M.L.; Chiarizia R.; Diamond, H.; Maxwell, III, S.L.;
Nelson, M.R.; Separation and preconcentration of actinides by extraction
chromatography using a supported liquid anion exchanger: application to thecharacterization of high-level nuclear waste solutions, Anal. Chim. Acta. 1995, 310,
63-78.
15. Horwitz, E.P.; Chiarizia, R.; Dietz, M.L.; Diamond, H. Separation andpreconcentration of actinides from acidic media by extraction chromatography, Anal.
Chim. Acta. 1993, 28, 361-372.
16. Huff, E.A.; Horwitz, E.P. Inductively coupled plasma-atomic emission
spectrometry (ICP-AES) in support of nuclear waste management, Spectrochimica
Acta. 1985, 408, 279-286.
17. Horwitz, E.P.; Muscatello, A.C.; Kalina, D.G.; Kaplan, L. The extraction of
selected transplutonium(III) and lanthanide(III) ions by dihexyl-N,Ndiethylcarbamoylmethylphosphonate from aqueous nitrate media, Sep. Sci. Technol.
1981, 16, 417-437.
18. Horwitz, E.P.; Kalina, D.G.; Kaplan, L.; Mason, G.W.; Diamond, H. Selectedalkyl(phenyl)-N,N-dialkylcarbamoylmethylphosphine oxides as extractants forAm(III) from nitric acid media, Sep. Sci. Technol. 1982, 17, 1261-1279.
19. Yaita, T.; Herlinger, A.W.; Thiyagarajan, P.; Jensen, M.P. Influence of extractant
aggregation of trivalent f-element cations by a tetraalkyldiglycolamide, Solvent Extr.
Ion Exch. 2004, 22, 553-571.
20. Peppard, D.F., Bloomquist, C.A.A.; Horwitz, E.P.; Lewey, S.; Mason, G.W.
Analogous actinide(III) and lanthanide(III) tetrad effects, J. Inorg. Nucl. Chem.1970,
32, 339-343.
21. Horwitz, E.P.; Bloomquist, C.A.A. Chemical separations for super-heavy
searches in irradiated uranium targets, J. Inorg. Nucl. Chem. 1975, 37, 425-434.
22. Dietz, M.L.; Horwitz, E.P. Improved chemistry for the production of yttrium-90
for medical applications, Appl. Radiat. Isotopes. 1992, 43, 1093-1101.

23. Horwitz, E.P.; Bond, A.H. Purification of radionuclides for nuclear medicine: themulticolumn selectivity inversion generator concept, Czech. J. Phys. 2002, 53, A717723.

List of Figures:
Figure 1. k′ for Eu(III) vs. time on TODGA resin (50-100 µm) from 3.0 M HNO3,
22(1)oC.
Figure 2. k′ for Th(IV), U(VI), Am(III) and Pu(IV) on TRU, TODGA and TEHDGA
resins (50-100 µm) versus HNO3, 1 hour equilibration time, 22(1)oC.
Figure 3. k′ for Th(IV), U(VI), Am(III) and Pu(IV) on TRU, TODGA and TEHDGA
resins (50-100 µm) versus HCl, 1 hour equilibration time, 22(1)oC.
Figure 4. k′ for Am(III) on TODGA and TEHDGA resins (50-100 µm) versus HNO3 andHCl, 1 hour equilibration time, 22(1)oC.
Figure 5. k′ for Y(III), Eu(III), Am(III) and Ce(III) on TODGA resin (50-100 µm) versus
HNO3 and HCl, 1 hour equilibration time, 22(1)oC.
Figure 6. k′ for Y(III), Eu(III), Am(III) and Ce(III) on TEHDGA resin (50-100 µm)
versus HNO3 and HCl, 1 hour equilibration time, 22(1)oC.
Figure 7. k′ for Ln(III) cations and Y(III) on TODGA resin (50-100 µm) from 0.50 M
and 0.05 M HNO3 and on TEHDGA from 1.0 M HNO3 versus atomic number, 1 hour
equilibration time, 22(1)oC
Figure 8. k′ for alkaline earth cations on TODGA resin (50-100 µm) versus HNO3 andHCl, 1 hour equilibration time, 22(1)oC.
Figure 9. k′ for Y(III) and Sr(II) on TODGA resin (50-100 µm) versus HNO3 and HCl, 1
hour equilibration time, 22(1)oC.
Figure 10. k′ for selected transition and post transition elements on TODGA resin (50100 µm) vs. HNO3 and HCl, 1 hour equilibration time, 22(1)oC.
Figure 11. Separation of U(VI), Am(III) and Pu(IV) on TODGA resin (50-100 µm), 2.0
mL bed volume, flow rate equals 2 mL/min load/rinse, 1 mL/min strip, 22(1)oC.
Figure 12. Elution of Am(III) on TEHDGA resin (50-100 µm) with 7.0, 0.1 and 0.01 M
HNO3, 0.5 mL bed volume, flow rate equals 2 mL/min load/rinse, 1 mL/min strip,
22(1)oC.
Figure 13. Separation of Ac(III) and Ra(II) on TODGA resin (50-100 µm) with 6.0 M
HNO3 and 0.1 M HCl, 0.5 mL bed volume, flow rate equals 2 mL/min load/rinse, 1
mL/min strip, 22(1)oC.

Figure 14. Separation of Y(III) and Sr(II) on TODGA resin (50-100 µm) with 5.0 M
HNO3, 0.1 M HNO3 and 0.1 M HCl, 1.0 mL bed volume, flow rate equals 2 mL/min
load/rinse, 1 mL/min strip, 22(1)oC.
Figure 15. Separation of Y(III) and Sr(II) on TODGA resin (50-100 µm) with 0.1 M
HNO3 and 0.1 M HCl, 1.0 mL bed volume, flow rate equals 2 mL/min load/rinse, 1
mL/min strip, 22(1)oC.
Figure 16. Separation of alkaline earth cations on TODGA resin (50-100 µm) with 4.0 M
HNO3, 0.25 M HNO3 and 0.1 M HCl, 2.0 mL bed volume, flow rate equals 2 mL/min
load/rinse, 1 mL/min strip, 22(1)oC.

510

3.0 M HNO3

4

10

k' forEu(III)
3

10

2

10

0

10
20
30
40
50
Equilibration Time (minutes)

60

Figure 1. k′ for Eu(III) vs. time on TODGA resin (50-100 µm) from 3.0 M HNO3, 22(1)oC.

TRU

6

10

TODGA

TEHDGA

Pu

5

10

Th
4

10

Pu

U

Pu

3

10
k'

Th

Am

2

10

Th

Am

Am

1

10

U

Pu(IV)
Th(IV)U(VI)
Am(III)

0

10

U

-1

10

-2

10

-1

10

0

10
[HNO3]

1

-2

10 10

-1

10

0

10
[HNO3]

1

-2

10 10

-1

10

0

10
[HNO3]

1

10

Figure 2. k′ for Th(IV), U(VI), Am(III) and Pu(IV) on TRU, TODGA and TEHDGA resins (50-100 µm) versus HNO3,
1 hour equilibration time, 22(1)oC.

TRU

6

10

TODGA

Pu(IV)
Th(IV)U(VI)
Am(III)

5

10

TEHDGA

Pu
Th

4

10

Pu
U

3

10

Pu

k'
2

10

U

Th

1

Am

10

0

Th

10

U

Am

Am

-1

10

-2

10

-1

0

10

10
[HCl]

1

-2

10 10

-1

0

10

10
[HCl]

1

-2

10 10

-1

0

10

10

1

10

[HCl]

Figure 3. k′ for Th(IV), U(VI), Am(III) and Pu(IV) on TRU, TODGA and TEHDGA resins (50-100 µm) versus HCl,
1 hour equilibration time, 22(1)oC.

10

6

10

6

10

5

10

4

10

5

4

10

TODGA
3

3

10

10

k' forAm(III) 102

10

2

TEHDGA

1

10

TODGA

1

10

10

0

10

0

-1

-1

TEHDGA
10

10
-2

10

-1

10

[HNO3]

0

10

1

10

-2

10

-1

10

0

10

1

10

[HCl]

Figure 4. k′ for Am(III) on TODGA and TEHDGA resins (50-100 µm) versus HNO3 and HCl,
1 hour equilibration time, 22(1)oC.

6

6

10

10
Ce(III)
Eu(III)
Y(III)
Am(III)

5

10

4

Y

5

10

Eu

4

10

10
Am

3

3

10

10
Ce

k'
10

2

10

1

1

Y

2

Am
10

10

10

0

10

-1

10

Ce

0

Eu

-1

10

-2

10

-1

0

10
10
[HNO3]

1

10

-2

10

-1

10

0

10

1

10

[HCl]

Figure 5. k′ for Y(III), Eu(III), Am(III) and Ce(III) on TODGA resin (50-100 µm) versus HNO3 and HCl,
1 hour equilibration time, 22(1)oC.

6

6

10

10
Ce(III)
Eu(III)
Y(III)
Am(III)

5

10

Y
Am
Eu

4

10

Ce

5

10

Y
Eu

4

10

Am

10

3

10

3

10

2

10

10

1

10

10

0

10

-1

10

Ce

k'
2

1

0

-1

10

-2

10

-1

10

0

10
[HNO3]

1

10

-2

10

-1

0

10

10

1

10

[HCl]

Figure 6. k′ for Y(III), Eu(III), Am(III) and Ce(III) on TEHDGA resin (50-100 µm) versus HNO3 and HCl,
1 hour equilibration time, 22(1)oC.

TODGA

5

10

TEHDGA

5

10

0.05 M HNO3
0.50 M HNO3
4

10

Dy

Eu Gd
Sm
Pm
Nd

3

10

Tb
Dy

Pr
La

1.0 M HNO3

Tm
Er

Lu
Y

Ho
Tm
Ho Er

Lu

10

Nd Pm

Y

Gd
Eu

2

k' 10

2

k' 10

Sm
Pm
Nd

1

10

0

10

Dy

3

Yb

Tb

Ce

4

10

Yb

Ce
La

La Ce

Pr

Eu

Gd

Ho

Tb

Tm
Er

Lu
Yb

Sm

1

10

Pr
0

10

From 0.1 M HNO3k' La-Tb and Y < 2
k' Dy - Lu < 4

-1

-1

10

10

56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72

56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72

Z

Z

Figure 7. k′ for Ln(III) cations and Y(III) on TODGA resin (50-100 µm) from 3.0 M and 0.1 M HNO3 and on TEHDGA from
1.0 M HNO3 versus atomic number, 1 hour equilibration time, 22(1)o.

Y

6

6

10

10
Ca(II)
Sr(II)
Ba(II)Ra(II)

5

10

5

10

4

4

10

3

10

10
k' for Be and Mg < 1

3

Cafor all [HNO3]

k'

10

2

k' for Be and Mg < 1

2

10

10

for all [HCl]

Sr
1

10

1

Ba

0

Sr
Ca

10
Ra

0

10

10
Ba

-1

Ra
-1

10

10
-2

10

-1

10

0

10
[HNO3]

1

10

-2

10

-1

10

0

[HCl]

10

1

10

Figure 8. k′ for alkaline earth cations on TODGA resin (50-100 µm) versus HNO3 and HCl,
1 hour equilibration time, 22(1)oC.

10

6

10

6

5

10

5

10

4

4

10

10

Y(III)

10

3

10

3

2

10

k'
2

10

Sr(II)

1

Y(III)

1

10

10

10

0

10

-1

10

0

Sr(II)

-1

10

-2

10

-1

10

[HNO3]

0

10

1

10

-2

10

-1

10

0

10

1

10

[HCl]

Figure 9. k′ for Y(III) and Sr(II) on TODGA resin (50-100 µm) versus HNO3 and HCl,
1 hour equilibration time, 22(1)oC.

5

5

10

10
Nb(V)
Zr(IV)
Bi(III)
Pb(II)

4

10

Bi(III)

Bi(III)Fe(III)
Cu(II)

4

10

Bi(III)

Zr(IV)
3

3

10

10

Pb(II)

2

k' 10

2

10

Fe(III)

Nb(V)
1

1

10

10

0

10

0

10

k' for V(V), Ti(IV), Al(III),
Fe(III), Co(II), Cu(II), Ni(II),Zn(II) < 2 for all [HNO3]-1

k' for Ti(IV), Al(III),
Co(II), Ni(II), Pb(II),Zn(II) < 2 for all [HCl]Cu(II)

-1

10

10
-2

10

-1

0

10
10
[HNO3]

1

10

-2

10

-1

10

[HCl]

0

10

1

10

Figure 10. k′ for selected transition and post transition elements on TODGA resin (50-100 µm) vs. HNO3 and HCl,
1 hour equilibration time, 22(1)oC.

6

10

5

10

239

Rinse
3.0 M
HNO3

4

10
ppm U
241
239
cpm/mL Am and Pu

241

Load 0.5 mg U, Pu and Am in 10 mL of
3.0 M HNO3 + 0.1 M NaNO2 + 250 mg Fe(III)Rinse
0.1 M HNO3
0.03 M NaNO2

239

Pu

Strip
0.10 M HCl
0.03 M
NaNO2

U

3

10

Strip
0.10 Mammonium
oxalate

241

Am

2

10

1

10

Background

0

10

82% U
239
<0.1% Pu
in 3 BV

-1

10

241

97% Am239
0.3% Pu
in 4 BV

239

95% Puin 5 BV

-2

10

0

5

10

15

20
25
Bed Volumes

30

35

40

Figure 11. Separation of U(VI), Am(III) and Pu(IV) on TODGA resin (50-100 µm), 2.0 mL bed volume,
flow rate equals 2 mL/min load/rinse, 1 mL/min strip, 22(1)oC.

6

10Load 10.0 mL 7.0 M HNO3 spiked with

241

Am

5

10

4

[HNO3]
0.01
0.1

3

10

95%

241

Am
Strip 0.1 M HNO3

3 Bed Volumes
22 Bed Volumes

cpm/mL

241

Am

10

2

10

1

Strip 0.01 M HNO3

10

0

10

Background
-1

10

-2

10

0

5

10

15

20

25
30
Bed Volumes

35

40

45

50

55

Figure 12. Elution of Am(III) on TEHDGA resin (50-100 µm) with 7.0, 0.1 and 0.01 M HNO3, 0.5 mL bed volume,
flow rate equals 2 mL/min load/rinse, 1 mL/min strip, 22(1)oC.

6

10Load 5.0 mL 6.0 M HNO3 UTEVA load eluate
spiked with

226

225

Ra(II) or

Ac(III)

Strip
0.10 M
HCl

5

10

91%

226

Ra

4

cpm/mL

10

3

10

96%

225

Ac

2

10

1

Background

10

Rinse
6.0 M
HNO3

0

10

0

1

2

3

4

5

6

7

8

9 10 11 12 13 14 15 16 17 18 19 20
Bed Volumes

Figure 13. Separation of Ac(III) and Ra(II) on TODGA resin (50-100 µm) with 6.0 M HNO3 and 0.1 M HCl, 0.5 mL bed volume,
flow rate equals 2 mL/min load/rinse, 1 mL/min strip, 22(1)oC.

7

10Load 10.0 mL 5.0 M HNO3
6

10

85

90

spiked with Sr and Y

Rinse
0.1 M
HNO3

Strip
0.1 M
HCl

5

10

4

cpm/mL

10

90

99% Y
in 4 BV

3

10Quantitative
2

10

85

Recovery of Sr

1

10

Background

0

10

-1

10

0

2

4

6

8

10
12
14
Bed Volumes

16

18

20

22

24

Figure 14. Separation of Y(III) and Sr(II) on TODGA resin (50-100 µm) with 5.0 M HNO3, 0.1 M HNO3 and 0.1 M HCl,
1.0 mL bed volume, flow rate equals 2 mL/min load/rinse, 1 mL/min strip, 22(1)oC.

7

10

85

90

Load 10.0 mL 0.1 M HNO3+ 250 mg Sr spiked with Sr and Y
6

10

Rinse
0.1 M
HNO3

5

10

85

90

Y

Strip
0.1 M
HCl

Sr

4

10
cpm/mL

90

98% Y
3

10

in 3 BV
Quantitative

2

10

85

Recovery of Sr

1

10

Background

0

10

-1

10

0

2

4

6

8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Bed Volumes

Figure 15. Separation of Y(III) and Sr(II) on TODGA resin (50-100 µm) with 0.1 M HNO3 and 0.1 M HCl,
1.0 mL bed volume, flow rate equals 2 mL/min load/rinse, 1 mL/min strip, 22(1)oC.

3

10Load 25 ppm Mg, Ca, Sr and Ba
in 25.0 mL of 4.0 M HNO3
Rinse
4.0 M
HNO3
Ba

2

10

Sr

Rinse
0.25 M
HNO3

Ca
Strip
0.1 M
HCl

1

ppm

10

Mg

0

10

99% Mg and Ba

99% Srin 5 BV

99% Cain 1 BV

-1

10

-2

10

Background

-3

10

0

2

4

6

8

10 12 14 16 18 20 22 24 26 28 30 32 34
Bed Volumes

Figure 16. Separation of alkaline earth cations on TODGA resin (50-100 µm) with 4.0 M HNO3, 0.25 M HNO3 and 0.1 M HCl,
2.0 mL bed volume, flow rate equals 2 mL/min load/rinse, 1 mL/min strip, 22(1)oC.

Table 1. Parameters employed for metal ion determination by ICP-AES
PeakWindow
Peak
Window
Peak
Window
Analyte (nm)(nm)
Analyte (nm)(nm)
Analyte (nm)(nm)
Al 396.152
0.080
Fe 259.940
0.040
Sr407.771
0.080
Ba 455.403
0.080
Gd 342.247
0.040
Tb 350.917
0.040
Be 234.861
0.040
Ho 345.600
0.040
Th 283.730
0.040
Ca 393.366
0.080
La 379.478
0.040
Ti
334.941
0.080
Ce 413.765
0.080
Lu 339.707
0.040
Tm 313.126
0.040
Co 228.616
0.060
Mg 279.553
0.040
U
385.958
0.080
Cr 267.716
0.040
Nb 316.340
0.040
V292.4020.040
Cu 324.754
0.040
Nd 406.109
0.040
Y371.030
0.040
Dy 259.940
0.040
Ni 231.604
0.060
Yb 369.419
0.040
Er337.2710.040
Pr414.3110.040
Zn 213.856
0.027
Eu 381.967
0.040
Sm 359.260
0.040
Zr343.8230.040
Integration time: 3.00 seconds
Sample uptake delay:
25 seconds
Replicates:
3
Pump rate:
15 rpmPower:
1 kW
Instrument stabilization:
15 seconds
Viewing height: 10 mm
Rinse time:
30 seconds

Table 2. Physical Constants of Slurry-Packed Columns of DGA Resin

Extractant Density (g/mL)
Bed Density (g/mL)
Resin Density (g/mL)
vs

TODGA
0.88
0.38
1.13
0.17

TEHDGA
0.89
0.38
1.13
0.17

vm

0.66

0.66

vs/vm

0.26

0.26

a

2.20

2.23

b

0.57

0.58

Dv conversion factor (C1)k' conversion factor (C2)a

Dv = Dw x C1b

k' = Dw x C2

Table 3. Extractant leaching of TODGA and TEHDGA resins at 25oC

BV
a

Load/Rinseb10% Extractant Lost/Bed Volume
TODGA
TEHDGA-5
4.6 x 10-5
3.6 x 10Strip

53.6 x 10-5

1.3 x 10-5

Strip with guardb,c5

1.5 x 10-5

0.7 x 10-5

6 M HNO3b
0.1 M HCl for TODGA, 0.1 M HNO3 for TEHDGAac

The strip solution was passed through a column of Amberchrom CG71m