MnO2 Resin: Concentration of Radium Isotopes

Deok-Soo MoonBill Burnett

Department of OceanographyFlorida State University

Tallahassee, Florida

Applications in Oceanography

Mixing rates between near-shore and offshore waters

Assessment of submarine groundwater discharge

Collection/Processing

“Mn- fiber” concentrates radium: count 223/224Ra via delayed coincidence; 226/228Ra via gamma spect (Dulaiova, 2002)

Ra-223 Distribution Offshore

Distance (km)0 1 2 3 4 5 6

Ln 22

3 Ra

(dpm

/100

L)

1.6

2.0

2.4

2.8

3.2

3.6

Kh = 18±6 m2/sec

slope = -0.200±0.035 km-1

r2 = 0.836n = 9

h

x KxAA

0lnln

hKm

Submarine spring

Mixing coefficient calculated from slope of 223Ra gradient (Moore, 2000)

Scale for Laboratory Use

“MnO2 Resin” Developed by PGRF 80-160 mesh Preconcentration approach in batch,

column, or pump (filtration) modes High adsorption of Ra, trivalent and

tetravalent actinides (Ac, Am, Pu, Th)

MnO2 Resin Experiments

Uptake studies: 133Ba and Ra; batch and column modes; kinetics; optimum conditions

Evaluate difference in chemical behavior, if any, between Ba and Ra

Evaluate use of MnO2 Resin cartridge with pump for processing

Tracers, Analytical Approach

Ba-133 (commercial, nominal activity)

Ra-228 (separated from Th-232 solution)

Ba-133 via -spect (NaI) and LSC Ra-228 via Ac-228 separation

(Diphonix), HEDPA elution, LSC counting

Batch ExperimentsBa-133 spike, adjust pH, react

Mn Resin with measured vol, vary time, resin, pH

Filter using syringe

Measure resin with NaI detector

Measure fluid with LSC

Perform experiments with both deionized water and seawater

Distribution Coefficient

W

V

A

AAD

f

fo

Ao = initial activity solution

Af = final activity solution

V = volume solution

W = weight of resin

Counting Solution & Resin

0 200 400 600 800 10000

500

1000

1500

2000

2500

3000 pH = 3

X0=1067

Y0=3188

Y=3188-2.99*X R=-0.99

133 B

a A

ctiv

ity in

so

lutio

n (

CP

M-L

SC

)

133Ba Activity in MnO2 resin (CPM-NaI)

• pH = 3• Variable mass

ratios• Variable reaction

times

Same Experiment, pH =7•pH = 7•Variable mass

ratios•Variable reaction

times

Kinetics, pH 3

• pH = 3• Resin = 25 mg• Solution = 10

mL

Kinetics, pH = 7

• pH = 7• Resin = 25 mg• Solution = 10

mL

Optimize Amount of Resin

• pH = 3 or 7• Resin =

variable• Solution = 10

mL DDW• Reaction time

= 90 min

0 20 40 60 80 100

200

400

600

800

1000

1200

133 B

a a

ctiv

ity in

Mn

O2

resi

n (

cpm

)

Weight of Mn resin (mg)

pH=3 pH=7

pH Variation

• pH = variable• Resin = 25 mg• Solution = 10

mL• Reaction time

= 90 min

0 2 4 6 8 10 12 14

0

200

400

600

800

1000

1200

DDW SW

133 B

a a

ctiv

ity in

Mn

O2

resi

n (

CP

M)

pH

Column ExperimentsW ater

sam p le1 L

A d d B a & R a trace r1 3 3 22 8

A d ju st p H = 7

M n res inC o lu m n

1 .0 g L eac h w ith 2 M H C l/H O2 2

1 3 3B a Yie ld w ith N aI d e te c to r

A g in g > 3 0 h rs : A c2 2 8

2 M H C l L o ad , R in se 1 M H E D PA 5 .0 m l

D ip h o n ix res in

H E D PA + C o ck ta ilC o u n t L S C A C2 2 8

Column Results

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

T e s t1 T e s t2

C o lumn E xp e rime nt(F lo w ra te = 1 .0 ml/min, p H = 7 )

Rec

over

y(%

)

BaRa

• pH = 7• Resin = 1 g• Solution = 1

liter DDW• Flow rate 0.65

mL/cm2.min (gravity flow 1 mL/min)

Pump Tests

Peristaltic pump; cartridge loaded with 1 g MnO2 Resin;

single pass

Ba Recovery vs Flow Rate

0 50 100 150 200 250 3000

20

40

60

80

100

120

DDW (pH=7) SW (pH=7)

133 B

a r

eco

very

(%

)

Flow rate (ml/min)

96.22.7%• pH = 7• Resin = 1g• Solution =

1L DDW or SW

• Variable flow

Ra Recovery vs Flow Rate

0 50 100 150 200 250 30020

40

60

80

100

DDW(pH=7) SW (pH=7)

228 R

a r

eco

very

(%

)

Flow rate (ml/min)

• pH = 7• Resin = 1g• Solution =

1L DDW or SW

• Variable flow

95.25.1%

Ba/Ra Recovery Ratio

0 50 100 150 200 250 3000.0

0.2

0.4

0.6

0.8

1.0

1.2

DDW SW

133 B

a/22

8 Ra

re

cove

ry r

atio

Flow rate (ml/min)

• pH = 7• Resin = 1g• Solution =

1L DDW or SW

• Variable flow

1.010.05

Summary/Future Work

MnO2 Resin adsorbs Ra and Ba very well Little difference in uptake between Ra and

Ba except in sw Investigate intermediate salinities (typical

groundwaters, etc.) Mate to RAD-7 radon analyzer for Ra-224 Study adsorption of Am(III), Th(IV), etc.