1. Analysis of Actinide Elements from Large Environmental Samples
Guebuem Kim
Bill Burnett
Florida State University
and
E. Philip Horwitz
PG Research Foundation, Inc.

2. Need for Large Volumes Achieve low MDA's for environmental monitoring
Specialized scientific studies often require large volumes to obtain necessary sensitivity, e.g., Am/Pu in seawater, global fallout in recent soils

3. Analytical Challenges
Preconcentration of actinides from natural water samples may require handling up to liters
Large (5-10 grams or more) soil/sediment samples may require difficult and lengthy dissolution procedures
Separation chemistry, especially from large soil/sediment samples, suffers from “matrix effects.”

4. Actinides in Natural Waters
Precipitate
MnO2
pH = 2
KMnO4
NaOH, pH = 8
MnCl2
10's - 100's liters
+ tracers
Precipitate
Fe(OH)3
2M HCl/NH2OH.HCl
50 mg Fe
NaNO2
pH = 6-7
Resins:
UTEVA
TRU
Separation
Am, Pu, etc.
alpha spectrometry
ICP-MS

5. Marine Environment Laboratory Monaco

6. Am/Pu from 200-L Seawater
Supernatant seawater transferred from one plastic tank to another via pumping — this will be used for 90Sr and 137Cs.
MnO2 suspension withdrawn from bottom of conical-shaped plastic tanks — processed for Am and Pu.

7. Irish Sea Water Results

8. { Soils and Sediments Dissolution/ Leaching Ozonation
tracers
Fe(OH)3 ppt
0.1M HCl-0.3M HF, AA
0.5M HEDPA
Diphonix
"Matrix"
Ozonation
“Fenton’s Reagent”
oxidation
H3PO4
Resins:
TRU
TEVA
UTEVA
Am, Pu, etc.
alpha spectrometry
ICP-MS {
one or
more
Separation

9. Diphonix Ion Exchange Resin
Features of Diphonix:
diphosphonic & sulfonic acid groups
polystyrene/divinylbenzene matrix
extremely high actinide retention, low common ion adsorption
tolerant to HF

10. Actinide Retention on Diphonix Resin
Diphonix Resin shows high retention for all Actinides

11. Adsorption of actinides highest at pH ~1-2
Adsorption of 241Am
Adsorption of actinides highest at pH ~1-2

12. HEDPA 1-hydroxyethane-1, 1-diphosphonic acid Molecular weight = 206.03
Elution sequence: Th(IV) = Pu(IV) > U(VI) > Am(III)
Reagent-grade expensive (Fluka: 50 g ~ $165) — option to purify industrial grade (Albright & Wilson: “BRIQUEST” ADPA-60AW U)

13. Elution: HEDPA Acid Dependency Curves
Indicates that actinides should elute easily at concentrations ~0.5M

14. Elution of Am

15. HEDPA Destruction via Ozone
20-mL elution was diluted to 70 mL, H2O2 added (0.5M), pH adjusted to 9.0 with NaOH, and samples ozonated for variable lengths of time

16. Ozonation Process
sample
Ozone delivered from an ozone generator via a gas diffusion stone oxidizes the HEDPA

17. Oxidation by Fenton’s Reagent
finished
Treatment:
40 mL 0.5M HEDPA + 1 mL HNO mL H2O g Fe(NH4)2(SO4)2·6H2O
Temperature ~90oC
H2O2 + Fe2+ ® OH + OH- +Fe3+

18. Final clean-ups: Am/Ln on TEVA; U on UTEVA
Actinide Separations
Sample
(3M HNO3, 0.7M Al(NO3)3, FS, AA)
TRU
Resin 1 2 3 4 5 6
2.5M HNO3
2.5M HNO3/0.1M NaNO2
9M HCl
4M HCl
4M HCl/TiCl3
1M HCl
0.1M Ammonium Bioxalate
Discard Am Pu Th U
TRU·Resin tolerates high PO4
Final clean-ups: Am/Ln on TEVA; U on UTEVA

19. Sensitivity to PO4
TRU.Resin
UTEVA.Resin

20. Preliminary Tests
Am-241 and Th-234 spiked samples. Matrix = HNO3/HCl leach of 10-g NIST Rocky Flats II soil

21. Standard Samples: Yields
Samples (n=7):
3 EML soils
2 IAEA sediments
2 Fe-rich soils
5 intercomparison samples and 2 Fe-rich samples run through entire procedure and analyzed for Am, Pu, U, and Th. 10-gram samples were leached with HNO3/HCl.

22. Standard Samples: Results
Table 1: EML and IAEA intercomparison values.

23. Summary
Uptake of actinides onto Diphonix from complex matrices is very efficient
0.5M HEDPA easily elutes actinides
“Fenton’s Reagent” or O3 successfully oxidizes HEDPA
Separations starting with TRU·Resin prevent PO4 interference