MnO2 Resin
UGM06 - 10/11/06 - Bratislava
Outline
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
pH dependency of Dw
Kinetics
Capacity / Amount of resin
Interferences
Flow-rate
Applications
2
Information on MnO2
Bill Burnett et al:
Use of de-ionised , ground and sea waters
ƒ Study with variation of
–
–
–
–
–
pH
Kinetics
Ratio resin mass vs volume of solution
Salinity
Flow rates
ƒ Use of 133Ba as Ra homologue
Josue Moreno (TU Munich):
ƒ Dw values of natural radionuclides
ƒ Capacities
ƒ Interferences
3
pH dependency
Experimental
ƒ Batch experiments
ƒ 5 mL aqueous phase and 100 mg MnO2 Resin OR
10 mL aqueous phase and 25 mg MnO2 Resin
ƒ pH adjustment with HCl or NaOH
ƒ Magnetic stirring, 60 minutes, room temperature
ƒ Phase separation by filtration (0,1 µm)
Observation
ƒ Strong shift of the pH in aqueous phase
Measurement
ƒ filtered MnO2 via γ-spec or LSC (after resin elution)
ƒ aqueous phase via γ-spec or LSC
4
pH dependency Ba-133
Burnett et al.
5
Dw - Ra-226
Dw
1,0E+05
1,0E+04
1,0E+03
1,0E+02
1,0E+01
1,0E+00
0
pH (mean)
1
2
3
4
5
6
Dw Radium1
7
8
9
10
11
12
13
14
Dw Radium2
ƒ High retention over the whole pH range
ƒ Radium adsorption greater than 99% for pH>3
Moreno
6
Dw - Ba-133
Dw
1,0E+05
1,0E+04
1,0E+03
1,0E+02
1,0E+01
1,0E+00
0
pH (mean)
1
2
3
4
5
Dw Barium1
6
7
8
9
10
11
12
13
14
Dw Barium2
ƒ Overall high retention above pH 4
ƒ Barium adsorption greater than 99% for pH>5
Moreno
7
Dw - Pb-210/ Po-210
Dw
1,0E+05
1,0E+04
1,0E+03
1,0E+02
1,0E+01
1,0E+00
0
pH (mean)
1
2
3
4
Lead
5
6
7
8
9
Polonium
Moreno
ƒ Pb: High Dw values (500 > Dw > 1000)
ƒ Po: Similar to the behaviour of Pb
ƒ Dw(Po) overall lower (factor 10)
8
Dw - Th and U
Dm
1,0E+04
1,0E+03
1,0E+02
1,0E+01
1,0E+00
0
pH (mean)
1
2
3
Uranium
4
5
6
7
8
9
Thorium
Moreno
ƒ U: good retention in near neutral pH range (Dw ≈ 100)
ƒ Th: overall very good retention 300 < Dw < 1000
9
Kinetics
ƒ 10 mL water samples spiked with Ba-133 (0, 0.2,
3.5 and 35‰ salinities)
ƒ 25 mg MnO2 resin
ƒ Magnetic stirrer
ƒ pH = 7.0
ƒ 1.0 to 90 minutes contact
ƒ Measurement of filtered MnO2 in NaI well-type
gamma counter
10
Kinetics
Burnett et al.
ƒ Uptake kinetics depend on salinity
11
Ba/Ra homology
ƒ Batch experiments
– 100 mg MnO2 / 5 mL solution
ƒ Column
– 1 g MnO2 resin
– Geometry: ∅i = 0.9 cm, H = 6,5 cm
– Water samples: de-ionised and synthetic sea water
12
Ba/Ra homology
Dw
1,0E+05
1,0E+04
1,0E+03
1,0E+02
1,0E+01
1,0E+00
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
pH (mean)
Dw Barium
Dw Radium
Moreno
ƒ High retention above pH 5
ƒ Good correspondence between Ra and Ba for pH values > 6-7
ƒ Significant deviation for low pH
13
Ba/Ra homology on columns
Burnett et al.
ƒ Good correspondence between Ba and Ra recoveries for
de-ionized and Seawater
ƒ Recoveries > 90% for both matrices
14
Interferences - Ca
Dw
1,0E+04
1,0E+03
1,0E+02
0
50
100
150
200
250
300
350
ppm Calcium
Barium
Radium
Moreno
ƒ For [Ca] ≤ 300 ppm no interference on Ba and Ra
retention (Dw) observed
15
Interferences - carbonate
1,00E+05
Dw
1,00E+04
1,00E+03
1,00E+02
0
100
200
300
400
500
600
700
800
900
1000
1100
2-
Ra inCO3
Ba in CO3
Conc. CO3 ppm
Moreno
ƒ Increase of Dw values with increasing carbonate concentration
ƒ Increase of pH
16
Selectivity over other
earth-alkalines
Dw of the elements of the 2nd group relative to the Dw of Ra
0,20
Dw Ratio
0,15
0,10
0,05
0,00
pH 0
2
4
Dw Sr/Ra
6
Dw Ca/Ra
8
10
12
Dw Mg/Ra
Moreno
ƒ Overall good selectivity for Ra over Sr, Ca and Mg
ƒ Sr and Ca show similar behaviour
17
Capacities
Element
Ba
Capacity [mg/g resin]
~ 10
pH value (mean)
5,6
Ba
Pb
Th
~ 10
~9
~ 1,0
4,5
6,5
5,2
(300 ppm Ca)
ƒ Capacities in the order of 1 mg/g (Th) and 10 mg/g (Ba) at given
pH values
ƒ Capacities might change when working at other pH values
18
Flow rate
ƒ
ƒ
ƒ
ƒ
ƒ
1.0 L sample water spiked with 133Ba and 228Ra
1.0 g MnO2 resin cartridge
pH = 7.0
Peristaltic pump, flow rate 0 -300 mL/min
Samples: de-ionized and seawater
19
Flow rates - results
133Ba
• deionized water
o
sea water
228Ra
Burnett et al.
¾ Problematic: Flow rates for sea water
20
Flow rates – results: 133Ba/228Ra
• deionized water
o
Burnett et al.
sea water
21
Summary
- Characterisation I ƒ Very high Dw (~1000) for Ra, Ba, Th and Pb
ƒ Ba and Ra uptake kinetics depend on salinity
ƒ Good Ba/Ra correspendence for pH >6
ƒ No interference on Ba/Ra uptake from Ca
and CO32ƒ Good selectivity for Ra over Ca, Sr and Mg
22
Summary
- Characterisation II ƒ Capacities between 1 mg/g (Th) and 10 mg/g
(Ba)
ƒ Flow rates should be kept < 20 mL.min-1
especially for high salt samples to assure:
– High yields
– Ba/Ra homology
ƒ Planned / in work:
– Artificial radionuclides and Ac
– Additional interferences
23
Applications
ƒ Ra-226/8 → two column draft procedure
– MnO2/DGA
– Ca rich water samples (BaSO4 microprecipitation)
ƒ Preconcentration of Pb-210
ƒ Preconcentration of Ba and Ra from 5L water
samples for gamma spectrometry
ƒ Preconcentration of Th (and U)
– Tests not yet started
– Evaluation of carbonate interferences
24
New Ra-226/8 method
ƒ Why need for new method
– Great interest for Ra isotopes (European DW directive)
– Current methods are lengthy and time consuming
ƒ Advantages of the new method
– High adsorption of Ra, Ra and other natural radionuclides
onto MnO2 resin from neutral pH solutions
– Rapid preconcentration from large water samples
– Selective and robust uptake and seperation of Ac and other
actinides on DGA Resin
¾ Two Resin Method
– MnO2 Resin for pre-concentration
– DGA-Normal Resin for separation of Ac from Ra and Ba25
Ra-226/8 Procedure
ƒ
ƒ
ƒ
ƒ
Load sample (0,5 – 1L, pH 7) on 1g MnO2
Strip MnO2 with 12 mL 5 M HCl-1.5% H2O2
Load 12 mL strip solution on DGA, Normal (2 mL)
DGA: U, Th and Ac-228 retention, Ra and Ba pass
– Collect load + 5 mL 5 M HCl rinse for Ra-226 and Ba-133
• Microprecipitation with BaSO4
• Yield by gamma spectrometry (Ba-133)
• Ra-226 by α-spectrometry
– Strip Ac-228 from DGA with 15 mL 2 M HCl
• Microprecipitation with CeF3
• Gas proportional counting
synopRa226_MnO2
26
Ra/Ba preconcentration
on MnO2 resin
cpm/mL vs. mL of Eluate
o
1.5 grams MnO 2 Resin, slurry packed from Deionized water, Flow rate = 10 mL/min, 22(1) C
10
5
Load 1L ground water simulant +
10
133
Strip
2 M HCl
+ H 2O 2
Ba tracer
lot# MNA05106
4
cpm /mL
97%
Recovery
10
3
10
2
10
1
10
0
10
activity of load solution
Background
-1
0
100
200
300
400
500
600
700
800
900
1000
1100
mL
ƒ Elution profile Ba-133, 1L spiked ground water, 1.5 g MnO2 resin
27
Retention profiles - I
Dw vs. HCl for DGA Resin, Normal
o
50-100 µm, 1 hr contact time, 25(2) C
5
10
Ra
Th
Ba
4
10
3
Dw
10
2
10
1
10
0
10
-1
10
-2
10
-1
10
0
[HCl]
10
1
10
ƒ Retention of Ra, Th and Ba on DGA, normal in HCl
ƒ Strong Th uptake at high HCl concentration
ƒ Ba and Ra show low uptake
28
Retention profiles - II
Dw vs. [HCl] on DGA Resin, Normal
o
50-100 µm, 1 h Contact Time, 25(2) C
6
10
Sr(II)
Y(III)
Bi(III)
5
10
4
10
3
Dw
10
2
10
1
10
0
10
-1
10
-2
10
-1
0
10
10
1
10
[HCl]
ƒ Retention of Sr, Y and Bi on DGA, normal in HCl
ƒ Y and Bi show high uptake at elevated HCl concentration
29
ƒ Potential interferents since chemistry similar to Ac
Retention profiles - III
k ' v s. [H C l] on D G A R esin , N o rm a l
50-100 µ m resin, 1 h contact tim e, 22(2) o C
10
4
10
3
10
2
10
1
10
0
Ac
Th
k'
10
-1
10
-1
10
0
10
1
[H C l]
ƒ Retention of Ac and Th on DGA, normal in HCl
ƒ Ac: strong retention only for high HCl, significantly lower than Th
30
ƒ Th: overall good retention, especially for high HCl
Retention profiles - IV
K′ vs HCl DGA Resin, Normal
K'
10
6
10
5
10
4
10
3
10
2
10
1
10
0
A m (III)
10
-1
U (V I)
10
-2
U
Th
Am
T h (IV )
10
-2
10
-1
10
0
10
1
HCl
ƒ Retention of U, Th and Am on DGA, normal in HCl
ƒ Very similar for high HCl (> 2M HCl)
31
Measurement of
Ba-133, Ac-228 and Ra
ƒ Ac-228
– Ac-228 sample preparation via cerium fluoride
microprecipitation
– Count on GPC
ƒ Ra and Ba-133
– Sample preparation via barium sulphate microprecipitation
– Ba-133 counted by gamma spectrometry
– Ra isotopes counted by alpha spectrometry
32
Decontamination Study
ƒ Selectivity of the DGA resin
ƒ Decontamination of commonly occurring alpha and beta
emitters such as Pb/Bi, Th, Sr/Y were studied
ƒ 500 mL of tap water spiked with alpha and beta emitters
ƒ Samples processed using the complete method
Interference
added
Deconfactor
Ac-fraction
Th-228/U-232
>303
from potentially interfering elements
Pb-210/Bi-210
>1542
¾ Even for Y-90 and Bi-210 → MnO2?
Sr-90/Y-90
>1208
¾ Overall very good decontamination
33
Method Performance Data
Replicate #
Yield
Yield
Ba-133 Ra-228
Yield ratio
Ba/Ra
Yield bias
/%
Yield
Ra-226*
1
89
86
1,04
3,4
106
2
76
74
1,03
2,6
93
3
83
77
1,08
7,2
100
Average
83
79
1,05
4,8
99.7
SD
7
6
0,12
0,5
7
RSD / %
8,4
7,6
11,3
11,3
7,0
*Yield corrected
ƒ Good correspondence between Ba-133 and Ra-228 yields
– Overall bias in the order of 5% → Ac-228 separation on DGA?
¾ Bias not significant within given uncertainties
– Ba-133 also internal standard for Ra-228/Ac-228
ƒ Corrected Ra-226 yield indicates absence of bias
ƒ Relative standard deviation (N=3) in the order of 7 – 8 %
34
Alpha Spectra:
Micro precipitation
Ra-226
Rn-220
Ra-224
Ra-226
1L, Spiked tap water (Ca ≈ 500 ppm)
35
Pb-210 preconcentration
ƒ Sample loading: 1.5 L, pH 5 – 7 on 2g MnO2
– Column mode, flow rate 15 mL.min-1
– Internal standards: 10 mg Pb and Po-208
ƒ Elution with 20 mL 2M HCl / 3 % H2O2
ƒ Separation on Pb Resin
– Load 2M HCl / 3 % H2O2, rinse 2M HCl
– Po Elution: 1M HNO3 and 0,1M HNO3 → α-spec
– Pb elution: 10 mL 0,1M citric acid → AAS, LSC
synopPb210_MnO2
36
Pb-210 preconcentration
ƒ Yield of Pb preconcentration step: 60 - 90%
– Optimisation of elution conditions and volumes
ƒ Overall Pb yield between 30 and 50%
– Interferences by Mn(II) on Pb Resin?
– Optimisation of Pb Resin loading conditions
• Load from HN03
ƒ No Po recovery
ƒ DLPb-210 (1.5L, tm=5h, CSL) = 40 – 50 mBq.L-1
ƒ No significant bias (Reference Material):
Determined activity
A(Pb-210) / Bq.L-1
Uncertainty
Uc (Pb-210) / Bq.L-1
Reference activity
A(Pb-210) / Bq.L-1
Uncertainty Uc
(Pb-210) / Bq.L-1
t-value
0,102
0,010
0,105
0,003
0,3
37
Ba/Ra preconcentration
for γ spectrometry
ƒ Special interest: Ra-228 determination
ƒ 5L water samples, pH 7
ƒ Ba-133 as internal standard
ƒ 3g MnO2 Resin
ƒ Stirring over night at room temperature
ƒ Filtration, drying of the filter
ƒ γ spectrometry after 48 h ingrowth period (Ac-228)
38
Ba/Ra preconcentration
for γ spectrometry
ƒ Ba-133 yield ~ 80%
ƒ Quicker, less hands-on time than evaporation / precipitation
method currently in use
ƒ Better reproducibility of source prep. for very Ca rich samples
ƒ DLRa-228 (t = 4h, 20% rel. Eff.) = 60 mBq.L-1 (via Ac-228, 911 keV)
ƒ No significant bias (Reference Material):
Determined activity
A(Ra-228) / Bq.L-1
Uncertainty
Uc (Ra-228) / Bq.L-1
Reference activity
A(Ra-228) / Bq.L-1
Uncertainty Uc
(Ra-228) / Bq.L-1
t-value
9,875
0,593
9,264
0,742
0,6
ƒ Extension to Pb-210 determination via γ spectrometry?
39
Summary
- Applications First tests and results for three applications:
ƒ Ra-226/8 via two column method
– Excellent decon factors for potential interferents
– No significant bias
ƒ Pb-210 preconcentration
– MnO2 preconcentration to be optimised
– Evaluation of Mn interference
– Not efficient for Po-210
ƒ Ra-228 determination via gamma spectrometry
– Good yields
– Application to larger volumes
– Smaller amounts of MnO2
40