Transcript Document 7351194

Analysis of Actinide Elements from
Large Environmental Samples
Guebuem Kim
Bill Burnett
Florida State University
and
E. Philip Horwitz
PG Research Foundation, Inc.
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
Analytical Challenges
Preconcentration of actinides from
natural water samples may require
handling up to 100-400 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.”
Actinides in Natural Waters
10's - 100's liters
+ tracers
pH = 2
KMnO4
NaOH, pH = 8
MnCl2
Precipitate
MnO2
Resins:
• UTEVA
• TRU
Separation
Precipitate
Fe(OH)3
2M HCl/NH2OH.HCl
50 mg Fe
NaNO2
pH = 6-7
Am, Pu, etc.
• alpha spectrometry
• ICP-MS
Marine Environment Laboratory
Monaco
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MnO2 suspension withdrawn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.
Irish Sea Water Results
IAEA
IAEA
MEL/FSU MEL/FSU
Parameter Recommended Confidence Result
Yield
Value
Interval
mBq/k g
%
mBq/k g
mBq/k g
239,240
Pu
13.2
12.4-14.0 1 4.1±0.8 99.0
238
Pu
241
Am
3.16
16.0
2.80-3.82
3 .0 ±0 .2
8.40-20.0
1 7.0±1.1 95.0
99.0
Soils and Sediments
Dissolution/
Leaching
Diphonix
0.5M HEDPA
tracers
Fe(OH)3 ppt
0.1M HCl-0.3M HF, AA
"Matrix"
• Ozonation
• “Fenton’s Reagent”
oxidation
one
or
more
{
Resins:
• TRU
• TEVA
• UTEVA
Separation
H3PO4
Am, Pu, etc.
• alpha spectrometry
• ICP-MS
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
Actinide
Retention on
Diphonix Resin
Diphonix Resin
shows high
retention for all
Actinides
Adsorption of
241Am
1
0
0
9
0
8
0
241 Amdsorptin(%)
7
0
6
0
5
0
2
1
0
1
1
0
0
1
0
H
C
l
(
M
o
l
a
r
i
t
y
)
Adsorption of actinides highest at pH ~1-2
1
1
0
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” ADPA60AW U)
Elution:
HEDPA
Acid
Dependency
Curves
Indicates that
actinides should
elute easily at
concentrations
~0.5M
Elution of Am
1
0
0
8
0
P
r
i
o
r
R
e
s
u
l
t
I
n
c
r
e
m
e
n
t
a
l
6
0
AmRecovry(%)
4
0
2
0
0
051
0
1
5
2
0
2
5
3
0
3
5
4
0
0
.
5
M
H
E
D
P
A
E
l
u
t
i
o
n
V
o
l
u
m
e
(
m
L
)
HEDPA Destruction via
Ozone
120%
Efficiency %
100%
80%
60%
40%
20%
0%
50
70
90
110
130
150
170
Time (min)
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
Ozonation Process
sample
Ozone delivered from an ozone generator via a gas
diffusion stone oxidizes the HEDPA
Oxidation by Fenton’s
Reagent
finished
Treatment:
40 mL 0.5M HEDPA + 1 mL
HNO3 + 40 mL H2O2 + 0.17 g
Fe(NH4)2(SO4)26H2O
Temperature ~90oC
H2O2 + Fe2+ OH + OH- +Fe3+
Actinide Separations
Sample
(3M HNO3, 0.7M Al(NO3)3, FS, AA)
3
4
5
2
6
1
2.5M HNO3
1 2.5M HNO3/0.1M NaNO2
2.5M HNO3
2
4M HCl
4 2.5M HNO3
2.5M HNO3/0.1M
NaNO2
2.5M HNO3
9M HCl
5 1M HCl
TRU

9M HCl
4M HCl
Resin
3 4M HCl/TiCl3
Discard
TRUResin
tolerates
high PO4
6 0.1M Ammonium Bioxalate
1
Am
6
2
Pu
5
3
4
U
Th
Discard
Final clean-ups: Am/Ln on TEVA; U on UTEVA
Sensitivity to PO4
UTEVA.Resin
TRU.Resin
Preliminary Tests
Fe(OH)3 ppt
Diphonix Adsorption
Am
Th
HEDPA Elution
HEDPA Destruction
TRU.Resin
50
60
70
80
90
Yield (%)
Am-241 and Th-234 spiked samples. Matrix =
HNO3/HCl leach of 10-g NIST Rocky Flats II soil
100
Standard Samples: Yields
Yield(%)
0
0
1
0
9
Samples (n=7):
•3 EML soils
•2 IAEA sediments
•2 Fe-rich soils
0
8
0
7
0
6
0
5
u
m P
A
h
T
U
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.
Standard Samples: Results
Activity Ratio: FSU/Standard
0.60
0.70
0.80
0.90
1.00
1.10
EML-9409
Table 1: EML and IAEA
intercomparison values.
EML-9509
Sample
EML-9803
9409
9509
9803
300
135
IAEA-300
IAEA-135
Am-241
Pu-239/240
241
Am
mBq/g
1.73
1.76
2.68
1.38
318
239/240
Pu
mBq/g
7.78
5.17
5.31
3.55
213
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