Reload Index (ZRiChK UMCS)

 

 

STUDIES ON IMPROVEMENT OF 90SrDETERMINATION IN SOIL SAMPLES

 

STANIS£AW CHIBOWSKI, JAN SOLECKI,

DEPARTMENT OF RADIOCHEMISTRY AND COLLOID CHEMISTRY

 

 

Some experiments aimed on improving the determination of the extraction yield of strontium from soil samples are presented. Proposed method allows tracing extraction yield of strontium from soil samples treated with concentrated HNO3. The concentration of strontium before and after the extraction was determined by ED-XRF method.

An influence of the following factors on the extraction yield was studied:

n   type of the soil

n   density of the soil-solution suspension

n   concentration of Sr and Y

n   stirring intensity and duration of the process

The following conclusions may be drawn from the experiments:

n   The best extraction yield is obtained for soil to liquid (concentrated HNO3) ratio equal to 1:2.

n   Tracers should be added to solution after the extraction

n   Optimum heating time is two hours with moderate mixing of the suspension.

Experiments proved that extraction yield of strontium from soil samples should be determined for each analyzed sample.

On the basis of the performed experiments the following diagram was proposed:

 

Diagram forSr90 analysis in soil samples.

 

 

Collection and preparation
of the sample

 

 

 

 

 

 

 XRF analysis

 

Leaching

65%. HNO3, t = 80°C

 

 

 

 

 

 

Sediment to XRF analysis

 

Vacuum filtration

 

 


 

 

Saved for 90Y - 90Sr equilibrium

 (about 2 weeks)

 

 

 

 

Y carrier addition
 100 mg

 

 

 

 

Sr - Y separation
extraction with TBP

 

 

 

 

 

 

 

Discarded acid phase

with strontium

 

 Organic phase with Y

 

 

 

Y separation
 ethanol + ammonia 25%
heating to coagulate the sediment

 

 

 

Centrifugal separation and leaching the sediment in 6N HNO3

 

 

 

Precipitation of Y oxalate; 2% NH4C2O4; 25% ammonia to pH 2-2.5

 

 

 

Filtration and drying

 

 

 

Determination of Y yield

 

 

 

Measurement of Y radioactivity

 

 

This research is supported by KBN Grant No. 3T09C 034 15.

 

References:

[1] J.Solecki and S. Chibowski, J. Radioanal. Nucl. Chem., Vol. 247, No.1 (2001)

 

Grant KBN 3T09C 03415