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Radiochemical separation of 131I from irradiated natural uranium and tellurium dioxide by solvent extraction using dibenzo-18-crown-6
Appl. Radial. ht. Vol. 41, No. 8, pp. 787-788, 1990 Inr. J. Radiar. Appl. Itwrum. Part A 0 Pergamon Press plc 1990. Printed in Great Britain 0883-2889/90
In this report we describe our extraction of iodine from uranium dioxide using DBC.
63.00 + 0.00
results related to the fission and tellurium
Experimental DBC was obtained from Fluka; 1,2-dichloroethane was analar grade BDH product; a solution of DBC in 1,2dichloroethane was prepared to obtain a concentration of 0.02 M. 50 mg samples of U,O, were irradiated for 1 h in the reactor (IRT-5000) with a neutron flux of 2 x 10” n cm-* s-’ , and dissolved in different concentrations (2, 4, 6, 8 and 10 M) of HCI. In the case of TeO,, 1 g samples were irradiated for 1h using the same flux, and then dissolved in 6 M HCl solution. Tellurium dioxide did not dissolve with lower acid concentrations. Equal volumes of organic and aqueous phase were used; the samples were shaken for about 20 min, centrifuged and the activity of equal aliquots from the aqueous and organic phase were measured using a solid state Ge/Li detector connected to a multichannel analyzer. Potassium iodide and sodium iodide solutions were prepared to a concentration of 5 mg/mL in 4 M HCI: 0.2 mL of each of these solutions (containing 1mg) were used. Sodium metabisulphite solutions were prepared to a concentration of 140 mg/mL in distilled water and 100 p L or 50 p L of this solution was applied as a reducing agent for the extraction of “‘I from uranium fission and TeO, targets, respectively. Different concentrations of sodium hydroxide solutions were used to strip the iodine from the organic to the aqueous layer.
Radiochemical Separation of 13’1from Irradiated Natural Uranium and Tellurium Dioxide by Solvent Extraction Using Dibenzo-l&crown-6 M. A. A. AL-JANABI
and A. H. M. KADEM
Nuclear Research Centre, Radioisotope Production Department, Tuwaitha, Baghdad, P.O. Box 765, Iraq (Received
16 October 1989; in revised form 1989)
19 December
After irradiation targets of natural uranium or tellurium dioxide were dissolved in hydrochloric acid and the extraction of “‘I into dibenzo-l8-crown-6 (DBC) in 1,2-dichloroethane was carried out. The concentration of the crown ether was 0.02 M. The effects of HCI concentration, reducing agent and carrier were studied. The extraction efficiencies were 90 and 98% for “‘I extracted from irradiated TeO, and U,O, respectively. The stripping of ‘)‘I into sodium hydroxide solutions was performed at a variety of different concentrations; best results were obtained using I-1.5 M solutions.
Results and Discussion Introduction
The extraction of iodine into DBC as a uranium fission product was studied as a function of HCl concentration (Table 1). It is evident that the percentage of iodine extraction did not vary significantly as the concentration of HCI increased. WMo and its daughter 99mTc were extracted with iodine. The iodine was quantitatively extracted with no impurities using the reducing agent. It seems that the iodine formed as a uranium fission product, existing in the iodide form and higher oxidation states. The addition of reducing agent, therefore, caused the percentage of extraction to increase from about 60% (Table 1) to 98% (Table 2). The addition of carrier was advantageous in the extraction of iodine but it did not affect the extraction of 99Mo and %Tc with iodine; neither of them were extracted with iodine in the presence of reducing agent, possibly due to their reduction to lower oxidation states or because of some complex formation.
Crown ethers were discovered by Pederson. He has synthesized many members of the family, and determined their properties and complexing abilities with several ions (Pedersen, 1967, 1970). It has been shown that the complexes of metal ions with crown ethers depending mainly on the polyether cavity, the size and charge of the cation, the solvent applied, the donor atoms in the main ring and the nature of the accompanied anion (Izaet et al., 1973; Parson and Wingfield, 1976). The cations in such complexes are held principally by electrostatic forces and the selective complexing of the metal ions by crown ethers depends on the match between ionic diameter and the cavity size of the ring (Pedersen. 1967, 1970; Frensdorff, 1971a,b). Authors have separated alkali metals and alkali earth metals by extraction chromatography and studied the molecular complexes in solutions containing crown ethers and iodine, and the solvent extraction of some divalent metallic ions as DBC complexes with picrate ions (Smutek and Tada, 1977; Tada and Smutek, 1978: Hopkins et ul., 1978; Sekine et al., 1979). Blasius et al. (1977) have applied crown ethers to chromatography. Other authors have introduced crown ethers of different ring sizes in polymer matrices to obtain special exchangers and pointed out that these exchangers can be applied in ion chromatography for fast separation of cations and anions in analytical chemistry, as well as for some other purposes (Blasius et al., 1980). Investigations were continued for the extraction of rare earth metals and the radiochemical separation of fission products (Tsay cl a/., 1983; Jalhoom et al., 1985; Jalhoom, 1986).
Table I. The effect of HCI concentration on the extraction of lx’1 into DBC as a uranium fission product HCI (M)
% of extractmn
2 4 6 8 IO
61.4 62.3 64.4 60.0 59.0
Aqueous phase: HCI solution. Organic phase: DBCa.02 M in I ,2-dichloroethane.
787
Technical
788 Table 2. The relatmn between the time after target dissolution and the percent of extraction of ‘“‘I as a uranium fiwon product (6 M HCI) into DBC Time (days) Immediately 2 4 Immediately , 4
Reducing agent, carrier
% of extraction
Na>S,O, Na,S,O, Na,&O, KI KI KI
98.0 88.0 46.0 96.X 61.9 51.9
Table 3. The extraction of “‘I from TeO, target in 6 M HCI. The effect of reducmg agent and that of the carrier on the extraction is indicated % of extraction
Reducing agent. carrier
11.2
Extraction (DBC) only With Na,S,O, With Nal only
90.6 23.5
Tbble 4 ExtractIon of 13’1from the TeO, target as a function of tone after dissolving the target (in the presence of Na, S20,) Time (days)
% of extraction
immediately 3.0 4.0 7.0
90.6 87.3 61.0 51.5
Fable 5. The stripping of “‘I from the organic phase usmg various concentrations of NaOH NaOH
(M)
0.00 I 0.010 0.100 I.000 1.500 2.000
% of stripping 13 6 16.6 17.7 92.2 93.9 86.0
When the uranium target was dissolved in 6 M HCI the iodine in this acidic medium may be oxidized after a period of time and. therefore, it was important to study this parameter. The results in Table 2 indicate that the percentage of extraction was remarkably decreased with time after the uranium target dissolution. It is. therefore, recommended to perform the extraction immediately after the dissolution of the target.
Note The results related to the extraction of iodine from the irradiated target of tellurium dioxide are shown in Table 3. The addition of carrier reduced the iodine extraction while the addition of reducing agent is required as the percentage of extraction was increased from 77 to 90%. due to the reduction of higher iodine oxidation states. Table 4 shows that the extraction of iodine from the tellurium dioxide target decreased appreciably within a few days, therefore it was necessary to carry out the extraction procedure immediately after the dissolution of the target. The stripping of iodine from the organic phase to the aqueous phase was studied using different sodium hydroxide concentrations (Table 5) We conclude that DBC is a selective extractant for iodine from irradiated natural uranium and irradiated tellurium dioxide at 6 M HCI in the presence of reducing agent. The maximum stripping was associated with 1-I .5 M sodium hydroxide solution. This extraction procedure may be used for the production of “‘I. AcknoMLdgements-The authors would like to thank Dr M. G. Jalhoom for useful discussions and the Iraqi Atomic Energy Organization for the support of this work.
References Blasuis E., Janzen K. P., Andrian W., Klautke G., Scholten G. and Strockenen J. (1977) 2. Anal. Chem. 284, 377. Blasuis E., Janzen K. P., Klein W., Klotz H., Hguyen V. B.. Nguyen T., Pfeiffer R., Scholten G., Simon H., Stockemer H. and Toussaint A. (1980) J. Chromatogr. 201, 147. Frensdorff H. K. (197la) J. Am. Chem. Sot. 93, 4684. Frensdorff H. K. (1971b) J. Am. Chem. Sot. 93, 600. Hopkins H. P., Jahagirdar D. V. Jr and Windler F. J. (1978) J. Phys. Chem. 82, 1254. lzaet R. M., Eatough D. J. and Christensen J. J. (1973) Struct. Bond. 16, 161. Jalhoom M. G. (1986) Radiochem. Acta 40, 203. Jalhoom M. G., Mani I. A. and Hassan J. A. (1985) Radiochem. Acta 38, 219. Parson D. G. and Wingfield J. N. (1976) Inorg. Chrm. Acts 18, 263. Pedersen C. J. (1967) J. Am. Chem. Sot. 89, 7017. Pedersen C. J. (1970) J. Am. Chem. Sot. 92, 386. Sekine T., Shioda K. and Hasegawa Y. (1979) J fnorg. Nucl. Chem. 41, 571. Smutek W. and Tada W. (1977) Radiochem. Rudiounal. Lett. 30, 199. Tada W. A. and Smutek W. (1978) Radiochem. Rudiounul. Lett. 34, 41. Tsay L. M., Shinh J. S. and Wu S. C. (1983) Anal.vst 108, 1108.
In this report we describe our extraction of iodine from uranium dioxide using DBC.
63.00 + 0.00
results related to the fission and tellurium
Experimental DBC was obtained from Fluka; 1,2-dichloroethane was analar grade BDH product; a solution of DBC in 1,2dichloroethane was prepared to obtain a concentration of 0.02 M. 50 mg samples of U,O, were irradiated for 1 h in the reactor (IRT-5000) with a neutron flux of 2 x 10” n cm-* s-’ , and dissolved in different concentrations (2, 4, 6, 8 and 10 M) of HCI. In the case of TeO,, 1 g samples were irradiated for 1h using the same flux, and then dissolved in 6 M HCl solution. Tellurium dioxide did not dissolve with lower acid concentrations. Equal volumes of organic and aqueous phase were used; the samples were shaken for about 20 min, centrifuged and the activity of equal aliquots from the aqueous and organic phase were measured using a solid state Ge/Li detector connected to a multichannel analyzer. Potassium iodide and sodium iodide solutions were prepared to a concentration of 5 mg/mL in 4 M HCI: 0.2 mL of each of these solutions (containing 1mg) were used. Sodium metabisulphite solutions were prepared to a concentration of 140 mg/mL in distilled water and 100 p L or 50 p L of this solution was applied as a reducing agent for the extraction of “‘I from uranium fission and TeO, targets, respectively. Different concentrations of sodium hydroxide solutions were used to strip the iodine from the organic to the aqueous layer.
Radiochemical Separation of 13’1from Irradiated Natural Uranium and Tellurium Dioxide by Solvent Extraction Using Dibenzo-l&crown-6 M. A. A. AL-JANABI
and A. H. M. KADEM
Nuclear Research Centre, Radioisotope Production Department, Tuwaitha, Baghdad, P.O. Box 765, Iraq (Received
16 October 1989; in revised form 1989)
19 December
After irradiation targets of natural uranium or tellurium dioxide were dissolved in hydrochloric acid and the extraction of “‘I into dibenzo-l8-crown-6 (DBC) in 1,2-dichloroethane was carried out. The concentration of the crown ether was 0.02 M. The effects of HCI concentration, reducing agent and carrier were studied. The extraction efficiencies were 90 and 98% for “‘I extracted from irradiated TeO, and U,O, respectively. The stripping of ‘)‘I into sodium hydroxide solutions was performed at a variety of different concentrations; best results were obtained using I-1.5 M solutions.
Results and Discussion Introduction
The extraction of iodine into DBC as a uranium fission product was studied as a function of HCl concentration (Table 1). It is evident that the percentage of iodine extraction did not vary significantly as the concentration of HCI increased. WMo and its daughter 99mTc were extracted with iodine. The iodine was quantitatively extracted with no impurities using the reducing agent. It seems that the iodine formed as a uranium fission product, existing in the iodide form and higher oxidation states. The addition of reducing agent, therefore, caused the percentage of extraction to increase from about 60% (Table 1) to 98% (Table 2). The addition of carrier was advantageous in the extraction of iodine but it did not affect the extraction of 99Mo and %Tc with iodine; neither of them were extracted with iodine in the presence of reducing agent, possibly due to their reduction to lower oxidation states or because of some complex formation.
Crown ethers were discovered by Pederson. He has synthesized many members of the family, and determined their properties and complexing abilities with several ions (Pedersen, 1967, 1970). It has been shown that the complexes of metal ions with crown ethers depending mainly on the polyether cavity, the size and charge of the cation, the solvent applied, the donor atoms in the main ring and the nature of the accompanied anion (Izaet et al., 1973; Parson and Wingfield, 1976). The cations in such complexes are held principally by electrostatic forces and the selective complexing of the metal ions by crown ethers depends on the match between ionic diameter and the cavity size of the ring (Pedersen. 1967, 1970; Frensdorff, 1971a,b). Authors have separated alkali metals and alkali earth metals by extraction chromatography and studied the molecular complexes in solutions containing crown ethers and iodine, and the solvent extraction of some divalent metallic ions as DBC complexes with picrate ions (Smutek and Tada, 1977; Tada and Smutek, 1978: Hopkins et ul., 1978; Sekine et al., 1979). Blasius et al. (1977) have applied crown ethers to chromatography. Other authors have introduced crown ethers of different ring sizes in polymer matrices to obtain special exchangers and pointed out that these exchangers can be applied in ion chromatography for fast separation of cations and anions in analytical chemistry, as well as for some other purposes (Blasius et al., 1980). Investigations were continued for the extraction of rare earth metals and the radiochemical separation of fission products (Tsay cl a/., 1983; Jalhoom et al., 1985; Jalhoom, 1986).
Table I. The effect of HCI concentration on the extraction of lx’1 into DBC as a uranium fission product HCI (M)
% of extractmn
2 4 6 8 IO
61.4 62.3 64.4 60.0 59.0
Aqueous phase: HCI solution. Organic phase: DBCa.02 M in I ,2-dichloroethane.
787
Technical
788 Table 2. The relatmn between the time after target dissolution and the percent of extraction of ‘“‘I as a uranium fiwon product (6 M HCI) into DBC Time (days) Immediately 2 4 Immediately , 4
Reducing agent, carrier
% of extraction
Na>S,O, Na,S,O, Na,&O, KI KI KI
98.0 88.0 46.0 96.X 61.9 51.9
Table 3. The extraction of “‘I from TeO, target in 6 M HCI. The effect of reducmg agent and that of the carrier on the extraction is indicated % of extraction
Reducing agent. carrier
11.2
Extraction (DBC) only With Na,S,O, With Nal only
90.6 23.5
Tbble 4 ExtractIon of 13’1from the TeO, target as a function of tone after dissolving the target (in the presence of Na, S20,) Time (days)
% of extraction
immediately 3.0 4.0 7.0
90.6 87.3 61.0 51.5
Fable 5. The stripping of “‘I from the organic phase usmg various concentrations of NaOH NaOH
(M)
0.00 I 0.010 0.100 I.000 1.500 2.000
% of stripping 13 6 16.6 17.7 92.2 93.9 86.0
When the uranium target was dissolved in 6 M HCI the iodine in this acidic medium may be oxidized after a period of time and. therefore, it was important to study this parameter. The results in Table 2 indicate that the percentage of extraction was remarkably decreased with time after the uranium target dissolution. It is. therefore, recommended to perform the extraction immediately after the dissolution of the target.
Note The results related to the extraction of iodine from the irradiated target of tellurium dioxide are shown in Table 3. The addition of carrier reduced the iodine extraction while the addition of reducing agent is required as the percentage of extraction was increased from 77 to 90%. due to the reduction of higher iodine oxidation states. Table 4 shows that the extraction of iodine from the tellurium dioxide target decreased appreciably within a few days, therefore it was necessary to carry out the extraction procedure immediately after the dissolution of the target. The stripping of iodine from the organic phase to the aqueous phase was studied using different sodium hydroxide concentrations (Table 5) We conclude that DBC is a selective extractant for iodine from irradiated natural uranium and irradiated tellurium dioxide at 6 M HCI in the presence of reducing agent. The maximum stripping was associated with 1-I .5 M sodium hydroxide solution. This extraction procedure may be used for the production of “‘I. AcknoMLdgements-The authors would like to thank Dr M. G. Jalhoom for useful discussions and the Iraqi Atomic Energy Organization for the support of this work.
References Blasuis E., Janzen K. P., Andrian W., Klautke G., Scholten G. and Strockenen J. (1977) 2. Anal. Chem. 284, 377. Blasuis E., Janzen K. P., Klein W., Klotz H., Hguyen V. B.. Nguyen T., Pfeiffer R., Scholten G., Simon H., Stockemer H. and Toussaint A. (1980) J. Chromatogr. 201, 147. Frensdorff H. K. (197la) J. Am. Chem. Sot. 93, 4684. Frensdorff H. K. (1971b) J. Am. Chem. Sot. 93, 600. Hopkins H. P., Jahagirdar D. V. Jr and Windler F. J. (1978) J. Phys. Chem. 82, 1254. lzaet R. M., Eatough D. J. and Christensen J. J. (1973) Struct. Bond. 16, 161. Jalhoom M. G. (1986) Radiochem. Acta 40, 203. Jalhoom M. G., Mani I. A. and Hassan J. A. (1985) Radiochem. Acta 38, 219. Parson D. G. and Wingfield J. N. (1976) Inorg. Chrm. Acts 18, 263. Pedersen C. J. (1967) J. Am. Chem. Sot. 89, 7017. Pedersen C. J. (1970) J. Am. Chem. Sot. 92, 386. Sekine T., Shioda K. and Hasegawa Y. (1979) J fnorg. Nucl. Chem. 41, 571. Smutek W. and Tada W. (1977) Radiochem. Rudiounal. Lett. 30, 199. Tada W. A. and Smutek W. (1978) Radiochem. Rudiounul. Lett. 34, 41. Tsay L. M., Shinh J. S. and Wu S. C. (1983) Anal.vst 108, 1108.