Jpurnal o f Radioanalytical Chemistry Vol. 51, No. 2 (1979) 191-196

RAPID SEPARATIONS OF CORROSION AND FISSION PRODUCTS

I. SELECTIVE LIQUID-LIQUID EXTRACTIONS WITH METAL DIETHYLDITHI OCARBAMATES

D. VAN~O, M. FOJTIK, M. SZLAUROVA, P. GALAN

Institute o f Industrial Hygiene and Occupational Diseases, Bratislava (Czechoslovakia}

(Received January 3, 1979)

A separation scheme of a complex mixture of radiohygienically important radionuelides of corrosion and fission products has been worked out. Rapid separation by means of solvent extractions with metal (sodium, antimony, zinc) diethyldithiocarbamates has been achieved. Chloroform containing metal diethyldithiocarbamates has been used as the organic phase. The procedure permits to separate selectively the representative radionuclides. The selectivity of separation was verified by gamma spectrometry.

Introduction

During our work on procedures for the evaluation of accidental contamination in nuclear establishments, we were faced with the practical problem of the rapid separation of a complicated mixture of radionuclides. One of the possible approaches to this problem is the utilization of the rapid establishment of both extraction and ion exchange equilibria.

Exchange reactions of metal ions Mn§ the aqueous phase with the chelate of

another metal M'An in the organic phase are frequently used for analytical and radiochernical procedures. 1 To estimate the course of exchange, it is necessary to know the extractability order of individual metals for a given system. The extracta- bility order of diethyldithiocarbamates into chloroform and carbon tetrachloride were established by various authors) -7 As reagents for the extraction of several

metals into chloroform, various metal diethyldithiocarbamates were used. In most cases the exchange reaction was completely finished within several minutes.

In this work, the diethyldithiocarbamates of a n t i m o n y - Sb(DDC)3, z i n c - Zn(DDC)2 and sodium - NaDDC were used for the separation of a mixture of ra- dionuclides: 46Sc, S4Mn, 59Fe, 6~ 64Cu, 6SZn, 95Nb, 99M0, 137Cs , 144Ce and I S2Eu.

Z Radioanal. Chem. 51 (1979) 191 2

D. VAN~O et al.: RAPID SEPARATIONS, I.

Experimental

All reagents were of analytical grade purity. Metal diethyldithiocarbamates in chloroform were prepared according to WYTTENBACH and BAJO. s The zinc con- tent in Zn(DI)C)2, as determined by atomic absorption spectrometry, was 18.2% (theoretical 18.1%). The radionuclides used were of commercial radiochemical purity.

The aqueous phase contained 10-SM chloride of each element of the mixture of radionuclides (except Me, used as sodium molybdate), radionuclide spikes and other components (Table 1).

The pH was adjusted with sodium hydroxide. The organic phase (chloroform) contained 5" 10-SM Sb(DDC)3 or Zn(DDC)2. The aqueous phase was shaken by a mechanical shaker with the same volume of the organic phase (10 ml) at room temperature. After equilibration, the count rates of 1 ml aliquots of both phases were measured. In the case of single radionuclide extraction, the measurement was performed using a NAG 232 well-type NaI(TI) scintillation detector with an NZQ 717 T single channel analyzer. In the case of extraction of a mixture of radio- nuclides, a semiconductor Ge(Li) detector (efficient volume 20 cm 3) with an NTA 512 multichannel analyzer was used.

Results

Based on literature data and on our experimental results, a scheme for the sepa- ration of 12 radionuclides using metal diethyldithiocarbamates is proposed. The con- ditions of this scheme are presented in Table I. Under these conditions, the ex- traction separation of single nuclides and mixtures has been performed.

In the first extraction stage, copper was selectively extracted with Sb(DDC)a in chloroform. Extraction was in both cases quantitative (more than 99%). The extraction of the remaining mixture was in both cases less than 1%.

In the second stage, molybdenum was selectively extracted with Zn(DDC)2 in chloroform. Extraction was in both cases quantitative. Extraction of the remainder was in both cases less than 1%.

In the third stage, iron, cobalt, manganese and zinc were quantitatively extracted with NaDDC. Extraction of the remainder was in both cases less than 1%.

In the fourth stage, the mixture of SgFe, 6~ ~SZn and S4Mn was reextracted. With 6M nitric acid, iron, zinc and manganese were reextracted. Cobalt was reextract- ed less than I%.

In the fifth stage zinc was quantitatively separated by isotope exchange with Zn(DDC)~. The extraction of iron and manganese was less than 1%.

192 :. Raclioanal. Chem. 51 (1979]

D. VAN~O et al.: RAPID SEPARATIONS, I.

Table 1 Experimental conditions of extzaction procedures

Stage A q u e o u s Reagent

No . phase

0.1M HCI

4M HC1

pH 5.5

6M HCI

pH 4.0

Sh(DDC) 3

Zn(DDC) 2

NaDDC

Reextraet org. phase No 3

Zn(DDC) 2

Concentration in CHCl 3 , M

5 �9 10 -3

5 �9 10 -s

10 -3 in aqueous phase

5 �9 10 -3

Time, min

Extraction, %

Cu >99

Mo ..~ 99

Fe, Co Mn, Zn > 99

Co >99

Zn > 99

AqUL~.IS ~

Ex

Ex

Ex

~ X

Ce~ Eu~ Sc~ Zr~ Nb~ C$

Cu~ Mo~ Co~ Fe~ I~n~ Zn

1 1

t |

1 I ~ ' Mn7 Zn ~

[- . . . . . . "1 I Ion Pxchor~e I L. . . . . . . . -J

Fig. 1. Proposed separation scheme for 12 radionuclides

J. Radioanal. Chem. 51 H 9 79}

2*

193

D. VANCO et al.: RAPID SEPARATIONS. I.

�9 ~4C~ZEu

~ I ~ ~. L- o

0 100 ZOO 300 tOO 500

Channel nunllx~

Fig. 2. Gamma-spectrum of the organic (upper part) and aqueous phase (lower part) after the first extraction stagd

:f

L 1 I t ~ _ _ O 100 200 300 400 raO0 | I~.Ce.~S2Eu Ch~r~

~ I I ~ ; L '-. ~ I r ~ ~ ~ ~ " .o

Channel number

Fig. 3. Gamma-spectrum of the organic phase (upper part) and aqueous phase (lower part) after the second extraction stage

194 J.. Radioanal. Chem. 51 {1979)

D. VAN~O et al.: RAPID SEPARATIONS, I.

~ ~ I ~ , ~ ~ ~ I ~ I ~ ~

0 100 200 300 400 500 ~r

Channe~ number

Fig. 4. Gamma-spectrum of the organic (upper ParO and aqueous phase (lower part) after the third extraction stage

o

i0 o Channel number

Fig, 5. Gamma-spectrum of the organic (upper part) and aqueous phase (lower part) after the fourth extraction stage

,7.. Radioanal. Chem. 51 (1979) 195

D. YAHOO r aL: RAPID SEPARATIONS, I.

g

0 100 200 300 L I p .

4oo soo Channel number

i

_ 1

0 100 200 300 ~ 500 P" Chanr~l number

Fig. 6. Gamma-specu'um of the organic (upper part) and aqueous phase (lower part) after the fifth extraction stage

Such a separation scheme permits to perform the selective and quantitative sepa- ration of eaCu, 99Mo, e~ SgFe, S4Mn and 6SZn within a total of 20 minutes.

Separation of the group of radionuclides 46Sc, 9SZr, 9SNb, 137Cs, 144Ce and 1 s 2Eu ' remaining after the third extraction stage is the subject of the second part of this paper.

References

1. J. STARY, Ekstraktsiya khelatov, Mir Moskva, 1966. 2~ R. WICKBOLD, Z. Anal. Chem., 152 (1956) 259. 3. G. ECKERT, Z. Anal. Chem., 155 (1957) 23. 4. H. BODE, R. TUSCHE, Z. Anal. Chem., 157 (1957) 414. 5. A. WYTTENBACH, S. BAJO, Anal. Chem., 47 (1975) 2. 6. J. STAR3~, K. KRATZER, Anal. Chim. Acta, 40 (1968) 93. 7. J. STAR3(, R. BURCL, Radiochem. Radioanal. Letters, 7 (1971) 235. 8. A. WYTrENBACH, S. BAJO, Anal. Chem., 47 (1975) 1813.

196 d. Radioanal. Chem. 51 (1979)