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

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Presentation on theme: "Analysis of Actinide Elements from Large Environmental Samples Guebuem Kim Bill Burnett Florida State University and E. Philip Horwitz PG Research Foundation,"— Presentation transcript:

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 zAchieve low MDA's for environmental monitoring zSpecialized scientific studies often require large volumes to obtain necessary sensitivity, e.g., Am/Pu in seawater, global fallout in recent soils

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

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

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 90 Sr and 137 Cs. MnO 2 suspension withdrawn from bottom of conical-shaped plastic tanks processed for Am and Pu.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 Diphonix oxidation Resins: TRU TEVA UTEVA tracers Fe(OH) 3 ppt 0.1M HCl-0.3M HF, AA "Matrix" 0.5M HEDPA H 3 PO 4 { one or more Separation Am, Pu, etc. alpha spectrometry ICP-MS Ozonation Fentons Reagent

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

12 HEDPA z1-hydroxyethane-1, 1-diphosphonic acid zMolecular weight = zElution sequence: Th(IV) = Pu(IV) > U(VI) > Am(III) zReagent-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, H 2 O 2 added (0.5M), pH adjusted to 9.0 with NaOH, and samples ozonated for variable lengths of time

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

17 Oxidation by Fentons Reagent finished Treatment: 40 mL 0.5M HEDPA + 1 mL HNO mL H 2 O g Fe(NH 4 ) 2 (SO 4 ) 2 6H 2 O Temperature ~90 o C H 2 O 2 + Fe 2+ OH + OH - +Fe 3+

18 Actinide Separations TRU Resin M HNO 3 2.5M HNO 3 /0.1M NaNO 2 2.5M HNO 3 9M HCl 4M HCl 4M HCl/TiCl M HCl 2.5M HNO 3 2.5M HNO 3 /0.1M NaNO 2 2.5M HNO 3 9M HCl 1M HCl 0.1M Ammonium Bioxalate Discard Am Pu Discard Th U Sample (3M HNO 3, 0.7M Al(NO 3 ) 3, FS, AA) Final clean-ups: Am/Ln on TEVA; U on UTEVA TRU Resin tolerates high PO 4

19 Sensitivity to PO 4 UTEVA. Resin TRU. Resin

20 Preliminary Tests Am-241 and Th-234 spiked samples. Matrix = HNO 3 /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 HNO 3 /HCl.

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

23 Summary zUptake of actinides onto Diphonix from complex matrices is very efficient z0.5M HEDPA easily elutes actinides zFentons Reagent or O 3 successfully oxidizes HEDPA Separations starting with TRU Resin prevent PO 4 interference


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