Analysis of Actinide Elements from Large Samples

Henrieta DulaiovaGuebuem Kim

Bill BurnettFlorida State University

andE. Philip Horwitz

PG Research Foundation

Need for Large Volumes

•Achieve very 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

Protocol for 10-g Samples

Dissolution/Leaching

Dip

honi

x

HEDPAoxidation

Resins:• TRU• TEVA• UTEVA

tracers0.1M HCl-0.3M HF, AA

"Matrix"

0.5M HEDPA

H3PO4 + actinides, Ln’s

{oneor

more Sepa

rati

on Am, Pu, etc.• alpha spectrometry• ICP-MS

“Fenton’s Reagent”H2O2 + Fe2+ OH + OH- +Fe3+

Actinide Retention on Diphonix Resin

Diphonix Resin

•high retention of actinides, Ln•Low retention common ions•Tolerate to HF

Elution:HEDPA

Acid Dependency

Curves

Indicates that actinides should elute easily at

concentrations ~0.5M

0.5M HEDPA Elution Volume (mL)

0 5 10 15 20 25 30 35 40

Am

Re

cove

ry (

%)

0

20

40

60

80

100

Prior ResultIncremental

Elution of Am

Fenton’s Reagent Oxidation

finished

Treatment:

40 mL 0.5M HEDPA + 1 mL

HNO3 + 40 mL H2O2 + 0.17 g

Fe(NH4)2(SO4)26H2O

Temperature ~90oC

H2O2 + Fe2+ OH + OH- +Fe3+

Actinide Separations

TRUTRU

Resin

12

3 45

6

3

2

12.5M HNO3

2.5M HNO3/0.1M NaNO2

2.5M HNO3

9M HCl4M HCl

4M HCl/TiCl3 6

5

4

4M HCl2.5M HNO3

2.5M HNO3/0.1M NaNO2

2.5M HNO3

9M HCl1M HCl

0.1M Ammonium Bioxalate

12

3 45

6DiscardAm

Pu DiscardTh

U

Sample(3M HNO3, 0.7M Al(NO3)3, FS, AA)

Final clean-ups: Am/Ln on TEVA; U on UTEVA

TRUResin tolerates high PO4

10-g Samples: Yields

Am Pu Th U

Yie

ld (

%)

50

60

70

80

90

100 Samples (n=7):•3 EML soils•2 IAEA sediments•2 Fe-rich soils

10-gram samples were leached with

HNO3/HCl.

10-g Samples: Results

0.60 0.70 0.80 0.90 1.00 1.10

EML-9409

EML-9509

EML-9803

IAEA-300

IAEA-135

Activity Ratio: FSU/Standard

Am-241 Pu-239/240

Table 1: EML and IAEA intercomparison values.

Anal. Chem. Paper

Protocol for 50-g SamplesStep 10-gram* 50-gram

Leaching

70 mL each:6M HCl/8M HNO3

4 hrs., 90oC

150 mL each:6M HCl/8M HNO3

4 hrs., 90oC

Load Sol’n

Add HF (0.5M), AA, adjust pH=1

ppt Fe(OH)3

HCl, HF, AA, H2O to ~300 mL2M HCl – 0.5M HF

*Kim, Burnett, & Horwitz ( 2000)

Conditions - Diphonix

Step 10-gram 50-gram

DiphonixColumn

1.2-cm diameter10 mL resin

same13 mL resin

Elution 0.5M HEDPA35 mL

same40 mL

OxidHEDPA*

Fenton’s ReagentHNO3/H2O2/Fe2+

same

*Oxidation of HEDPA is done in a glass beaker on a hot plate – the reaction is complete in approx. 30 minutes

Conditions – Final

Step 10-gram 50-gram

TRUColumn

0.6-cm dia, 5 mL~15 mL HNO3-Al(NO3)3-FS-AA

0.6-cm dia, 6 mL~25 mL HNO3-Al(NO3)3-FS-AA

TEVA*(Am)

Thiocyanate separation

same

Source Prep

CeF3 microprecipitation

same*Am fraction purified of lanthanides on TEVA column to prevent

thick source; Pu is processed directly after TRU

Spike Tests (50-g Soil)

0 20 40 60 80 100

Source

TRU.Resin

HEDPA Oxid.

HEDPA Elution

Diphonix Adsorption

Fe(OH)3 ppt

Yield (%)

Am SCSPu EML-1Pu EML-2

Am-241 and Pu-239 spiked samples. Matrix = HNO3/HCl leach of 50-g soil and sediment

samples.

IAEA-300 (Baltic Sea Sediment)

•50-g sample, leached with 6M HCl/8M HNO3

•Run through entire procedure…

Analyte Yield%

FSUmBq/g

IAEAmBq/g*

Am-241 95 1.45±0.05

1.381.2-1.5

Pu-239/240 37 3.98±0.12

3.553.44-3.65

Pu-238 37 0.28±0.03

~0.15#

* recommended value/range

# information value only

EML Soil 0009:•50-g sample, leached with 6M HCl/8M HNO3

•Run through entire procedure…Analyte Yield

%FSUmBq/g

EMLmBq/g*

Am-241 100 6.8±0.2 1-100

Cm-244 100 124±3 ~100

Pu-239/240 49* 15.3±0.5 1-100

Pu-238 49* 17.3±0.6 --

*An additional 38% + ~15% recovered during 2nd and 3rd ppt; so total recovery through columns ~100%

Observations: 50-g Samples

•Solutions highly colored after HEDPA oxidation

•Load solution occasionally reacts with TRU.Resin – very strong oxidizing agent (CeIV?)

•Pu does not completely co-precipitate with CeF3 – hold-back effect?

Color in Load Solutions

Before loading… After ~20 minutes…

IAEA-300 Am

243Am

241Am

EML Soil 0009 Pu

238Pu239/240Pu

242Pu

EML 9603 Pu (electro)

238Pu

239/240Pu

242Pu

Summary

•Diphonix/HEPDA/oxidation process eliminates matrix

•Am/Pu separations work well via TRUResin

•Reaction on TRU indicates strong oxidizer present

•Hold-back phenomenon occurs during CeF3 co-precipitation