- Email: [email protected]
Chemical state of 35S formed by the 35Cl(n, p) reaction
1332
Notes
J. Inorg. Nucl. Chem., 1964, Vol. 26, pp. 1132 to 1134. Pergamon Press Ltd. Printed in Northern Ireland
Chemical state of s~S formed by the S~Cl(n, p) reaction (Received 1 January 1964) VARIOUS authors ~1-9~ who dealt with the production of 85S and its chemical state in KCI crystals, reported that on dissolving the irradiated KC1 in water, the 3sS is obtained in its maximum oxidation state, that is, in the form of SOt ~- ion. Supposing that the oxidation of the 85S is produced by the oxygen incorporated in the KCI crystals, CROATTO and MADDOCK¢a) degassed the target material before irradiation but, nevertheless, on dissolving in water after irradiation, they only obtained radioactive SOt s- ions. Working also with previously degassed KCI irradiated by thermal neutrons, KOSKI~4~dissolved it in de-aerated solutions of SOt s-, SOs2- and S2- carriers, and obtained 65 per cent of the 8sS in form of SOt 2- and the remainder as S2- and SO8s-. Later, MILHAMtT~ using KC1 crystals sublimed in vacuum for irradiation and dissolving in a carefully de-aerated aqueous solution of the carriers, succeeded in obtaining 90 per cent of the sulphur activity in form of sulphide, when the crystals were dissolved in sulphide solutions. But when the carrier was added after dissolving the potassium chloride in water, only 30 per cent of the activity appeared as sulphide, and the remainder in the form of sulphate. The difference of 60 per cent was due--in the author's opinion--to a very active form, possibly St °, which undergoes immediate oxidation on dissolving in water. M. CHEMLAtl°~ showed that on warming, the 85S atoms, as well as the 82p atoms (generated in the same time by irradiation of NaCI) move towards the surface of the crystallites. The valency of 32p produced in the reaction ssCl(n, ~)32p has been studied also by P. Si3E and R. CAILLAT.O1) More recently, MADDOCK and PEARSONIls) showed that the ratio ssSS-:ssSOta- increase with the defect density and is affected probably also by the nature of the defects in the crystals. BOTTERWORTI4and CAMPBELLOa} as well as ADAMSand CAMPBELLIltl studied the dependence between the chemical behaviour of asP, obtained from 8~S by the (n,p) reaction, and the composition of the crystal lattice, the irradiation conditions and the post-irradiation-treatment. The aim of this work is to study this problem and to separate the s~S from the irradiated KCI in elementary form, if possible. Experimental KCI samples, with or without elementary sulphur added as carrier, were irradiated in the nuclear reactor at Bucharest. The target material was dried and degassed before irradiation in sealed quartz tubes. The samples, irradiated for 40 hr at a thermal neutron flux. of 1 × 10TMcm -2 sec-I were kept for 7 days to allow decay of the 42K. To avoid oxidation of the 35S atoms, we tried extraction with trichloroethylene (TCE) and only after that, we dissolved the KCI in aqueous solutions of the carriers (SO42-, SO32-, S 2-) and then separated the 85S on BaSOt. ~J J. E. WmLARD, Conference on the Chemical Effects of Nuclear Transformations at B.N.L. Aug. 19-20 (1948). ~ G. LEVEY, R. MILHAM, W. RICE and J. E. WILLARD,A.E.C.U. 50 (1948). la~ U. CROATTOand A. G. MADDOCK,J. Chem. Soc. 1, 351 (1949): Nature, Lond. 164, 613 (1949). ~4~W. S. KOSKI, J. Amer. Chem. Soc. 71, 4042 (1949). cs~ W. S. KosKI, Nature Lond. 165, 565 (1950). t6~ M. B. WILK, Canad. J. Res. 2713, 475 (1949). t¢~ R. MILHAM, Doctoral Thesis, University of Wisconsin 1952, in: Ann. Rev. NucL ScL 3, 212 (1953) (by J. E. WILLARD). ts~ A. N. NESMEIANOVet al., UspehiHimiiXX1 2, 133 (1953). t,~ A. N. MUPONet al., Uspehi Himii XXIV 5, 527 (1955). tl0l M. CHEMLA,C.R. Acad. Sci. Paris 232, 1553, 2424 (1951). tn~ p. S0E et R. CAILLAT, C. R. Acad. Sci. Paris 230, 1666, 1864 (1950). cls~ A. G. MADDOCKand M. PEARSON,Proc. Chem. Soc. Aug. 275 (1962). ~laJ j. S. BLrrTERWORTI-Iand J. C. CAMPBELL, Nature, Lond. 196, 982 (1962). tlt~ A. ADAMSand J. C. CAMPBELL,Trans. Faraday Soc. 59, 2001 (1963).
2
1 '72
1'72 1"72 1"72 1'72 1'72 1'72 1"72 1"72 1"72
1
2 3 4 5 6 7 8 9 10
No.
1 1 "72 1-72
1
1 1
KCI (g)
m
m
S added ~ from KCI
The irradiated sample
2 5 5 2 2 2 5 2 2
S added from KCI
No.
KC1 (g)
The irradiated sample
--920 920 800 500 500 500 500 500
--
Temp(°) 500 500 500 500 170 170
(hr)
5 5 5 5 4"45 4'45
The heating after irradiation
9 9 2 4"45 4'45 4"45 4"45 4"45
--
Temp(°)
(hr)
The heating after irradiation
2"20 1"94 2"15 2"10 0"26 0"25
(mCu)
4"39 4'05 0"17 0'24 0"41 0"20 0"21 0"30 0"33 0"27
(mCu) 81"67 82"01 2'64 3"76 6"40 3"30 3"39 4"96 5"17 4"63
% from total
in aqueous sol.
4"19 4'06 --0"10 0'08 0'17 0'15 0"19 0"15
(mCu)
62"32 61"20 64"09 64'42 5"72 5"79
~ from total
1'33 1"23 1"22 1"16 4'63 4"22
(mCu)
37"67 38"80 36'20 35"61 94"68 94"36
~ from total
in aqueous sol.
0"51 0"52 0"59 0"49 3'69 3"49
(mCu)
14"58 16"34 17"38 14"93 75"46 78"10
~o from total
as BaSO4
78"03 82"30 --1"55 1"32 2"68 2"50 2"91 2"55
% from total
as BaSO4
The activity of the obtained 35S
TABLE 2
18'26 17"10 91"45 96"23 95'14 96"69 96"61 93"69 94"83 95'96
% from total
In T.C.E.
0"98 0"88 6"19 6"15 6'02 5"90 6"15 5"71 6"09 5"49
(mCu)
In T.C.E.
1
The activity of the obtained 3sS
TABLE
6"11 5"45 5"80 5"61 4"89 4"47
The total activity calculated for 1.72 g KC1 (mCu)
5"37 4"93 6'36 6"39 6'43 6'10 6"36 6'01 6"42 5"76
The total activity calculated for 1'72 g KCI (mCu)
U~ t.o
~7
o
Z
1334
Notes
The solution of radiosulphur in TCE was boiled for 3 hr with a 10 per cent solution of HCI, for the removal of 82p, and after that, its activity was measured. In this way only a little part of the 85S (about 18~) was found in the TCE (Table 1). Operating in the same way with other irradiated material, but heating after irradiation at 920 °, 800 ° and 500°C, we succeeded in extracting with TCE 95 per cent of the total activity, the remainder being in other forms, soluble in water. The results are shown in Table 1. To demonstrate that the 85S in the TCE comes directly from the irradiated target and is not a result of isotopic exchange with the sulphur added as carrier, we treated in the same way four samples of KCI irradiated without carrier and heated, after irradiation, to 500°C. The results in Table 2 show that in this case 60-65 per cent of the activity was extracted with TCE as elementary sulphur, and the remainder was found in the aqueous solutions, in which 14.58-17"38 per cent was found as sulphate.
Discussion These results show that on heating the KC1 after irradiation at 920 ° (above the melting point of KC1) as well as at 500°C (above the boiling point of sulphur) the ssS atoms receive sufficient kinetic energy to migrate, from the point where they were formed, to the surface of the KC1 crystals, where they can be extracted, with elementary sulphur as carrier, or directly, by dissolving in TCE. This suggests an incompatibility of the 35S atoms with the crystalline lattice of KC1, and therefore that they cannot exist as ions, but in elementary form, a very reactive state which can easily change to another chemical form, by reaction with the solvent medium. The proportion of 35S extracted in elementary form from the KCI irradiated without carrier, nearly coincides with the value of 65 per cent found by KosKI for the radiosulphur as sulphate. At the same time, the results confirm Milham's supposition that about 60 per cent of the radiosulphur activity is in a reactive form--probably Sl°--which undergoes immediate oxidation on dissolving in water. The experimental fact that 90 per cent of radiosulphur can be found as S2- by dissolving the degassed and in vacuum sublimed KCI, in alkaline sulphide solutions, can be explained, in our opinion, by the reaction of the elementary 85S atoms with the S ~- ion to form disulphide ion $22-, or by an isotopic exchange of 36S atoms with the S 2- sulphide ions.
Conclusions The results obtained show that the 35S produced from ssC1 by the (n,p) reaction, is present in the elementary form in the KCI and that the results obtained by K o s ~ - - 6 5 per cent of the 85S as sulphate--represent, in our opinion, a subsequent oxidation of the 35S. C. CHIOTAN Institute for Atomic Physics I. ZAMFIR Bucharest, Roumania M. SZABO
Notes
J. Inorg. Nucl. Chem., 1964, Vol. 26, pp. 1132 to 1134. Pergamon Press Ltd. Printed in Northern Ireland
Chemical state of s~S formed by the S~Cl(n, p) reaction (Received 1 January 1964) VARIOUS authors ~1-9~ who dealt with the production of 85S and its chemical state in KCI crystals, reported that on dissolving the irradiated KC1 in water, the 3sS is obtained in its maximum oxidation state, that is, in the form of SOt ~- ion. Supposing that the oxidation of the 85S is produced by the oxygen incorporated in the KCI crystals, CROATTO and MADDOCK¢a) degassed the target material before irradiation but, nevertheless, on dissolving in water after irradiation, they only obtained radioactive SOt s- ions. Working also with previously degassed KCI irradiated by thermal neutrons, KOSKI~4~dissolved it in de-aerated solutions of SOt s-, SOs2- and S2- carriers, and obtained 65 per cent of the 8sS in form of SOt 2- and the remainder as S2- and SO8s-. Later, MILHAMtT~ using KC1 crystals sublimed in vacuum for irradiation and dissolving in a carefully de-aerated aqueous solution of the carriers, succeeded in obtaining 90 per cent of the sulphur activity in form of sulphide, when the crystals were dissolved in sulphide solutions. But when the carrier was added after dissolving the potassium chloride in water, only 30 per cent of the activity appeared as sulphide, and the remainder in the form of sulphate. The difference of 60 per cent was due--in the author's opinion--to a very active form, possibly St °, which undergoes immediate oxidation on dissolving in water. M. CHEMLAtl°~ showed that on warming, the 85S atoms, as well as the 82p atoms (generated in the same time by irradiation of NaCI) move towards the surface of the crystallites. The valency of 32p produced in the reaction ssCl(n, ~)32p has been studied also by P. Si3E and R. CAILLAT.O1) More recently, MADDOCK and PEARSONIls) showed that the ratio ssSS-:ssSOta- increase with the defect density and is affected probably also by the nature of the defects in the crystals. BOTTERWORTI4and CAMPBELLOa} as well as ADAMSand CAMPBELLIltl studied the dependence between the chemical behaviour of asP, obtained from 8~S by the (n,p) reaction, and the composition of the crystal lattice, the irradiation conditions and the post-irradiation-treatment. The aim of this work is to study this problem and to separate the s~S from the irradiated KCI in elementary form, if possible. Experimental KCI samples, with or without elementary sulphur added as carrier, were irradiated in the nuclear reactor at Bucharest. The target material was dried and degassed before irradiation in sealed quartz tubes. The samples, irradiated for 40 hr at a thermal neutron flux. of 1 × 10TMcm -2 sec-I were kept for 7 days to allow decay of the 42K. To avoid oxidation of the 35S atoms, we tried extraction with trichloroethylene (TCE) and only after that, we dissolved the KCI in aqueous solutions of the carriers (SO42-, SO32-, S 2-) and then separated the 85S on BaSOt. ~J J. E. WmLARD, Conference on the Chemical Effects of Nuclear Transformations at B.N.L. Aug. 19-20 (1948). ~ G. LEVEY, R. MILHAM, W. RICE and J. E. WILLARD,A.E.C.U. 50 (1948). la~ U. CROATTOand A. G. MADDOCK,J. Chem. Soc. 1, 351 (1949): Nature, Lond. 164, 613 (1949). ~4~W. S. KOSKI, J. Amer. Chem. Soc. 71, 4042 (1949). cs~ W. S. KosKI, Nature Lond. 165, 565 (1950). t6~ M. B. WILK, Canad. J. Res. 2713, 475 (1949). t¢~ R. MILHAM, Doctoral Thesis, University of Wisconsin 1952, in: Ann. Rev. NucL ScL 3, 212 (1953) (by J. E. WILLARD). ts~ A. N. NESMEIANOVet al., UspehiHimiiXX1 2, 133 (1953). t,~ A. N. MUPONet al., Uspehi Himii XXIV 5, 527 (1955). tl0l M. CHEMLA,C.R. Acad. Sci. Paris 232, 1553, 2424 (1951). tn~ p. S0E et R. CAILLAT, C. R. Acad. Sci. Paris 230, 1666, 1864 (1950). cls~ A. G. MADDOCKand M. PEARSON,Proc. Chem. Soc. Aug. 275 (1962). ~laJ j. S. BLrrTERWORTI-Iand J. C. CAMPBELL, Nature, Lond. 196, 982 (1962). tlt~ A. ADAMSand J. C. CAMPBELL,Trans. Faraday Soc. 59, 2001 (1963).
2
1 '72
1'72 1"72 1"72 1'72 1'72 1'72 1"72 1"72 1"72
1
2 3 4 5 6 7 8 9 10
No.
1 1 "72 1-72
1
1 1
KCI (g)
m
m
S added ~ from KCI
The irradiated sample
2 5 5 2 2 2 5 2 2
S added from KCI
No.
KC1 (g)
The irradiated sample
--920 920 800 500 500 500 500 500
--
Temp(°) 500 500 500 500 170 170
(hr)
5 5 5 5 4"45 4'45
The heating after irradiation
9 9 2 4"45 4'45 4"45 4"45 4"45
--
Temp(°)
(hr)
The heating after irradiation
2"20 1"94 2"15 2"10 0"26 0"25
(mCu)
4"39 4'05 0"17 0'24 0"41 0"20 0"21 0"30 0"33 0"27
(mCu) 81"67 82"01 2'64 3"76 6"40 3"30 3"39 4"96 5"17 4"63
% from total
in aqueous sol.
4"19 4'06 --0"10 0'08 0'17 0'15 0"19 0"15
(mCu)
62"32 61"20 64"09 64'42 5"72 5"79
~ from total
1'33 1"23 1"22 1"16 4'63 4"22
(mCu)
37"67 38"80 36'20 35"61 94"68 94"36
~ from total
in aqueous sol.
0"51 0"52 0"59 0"49 3'69 3"49
(mCu)
14"58 16"34 17"38 14"93 75"46 78"10
~o from total
as BaSO4
78"03 82"30 --1"55 1"32 2"68 2"50 2"91 2"55
% from total
as BaSO4
The activity of the obtained 35S
TABLE 2
18'26 17"10 91"45 96"23 95'14 96"69 96"61 93"69 94"83 95'96
% from total
In T.C.E.
0"98 0"88 6"19 6"15 6'02 5"90 6"15 5"71 6"09 5"49
(mCu)
In T.C.E.
1
The activity of the obtained 3sS
TABLE
6"11 5"45 5"80 5"61 4"89 4"47
The total activity calculated for 1.72 g KC1 (mCu)
5"37 4"93 6'36 6"39 6'43 6'10 6"36 6'01 6"42 5"76
The total activity calculated for 1'72 g KCI (mCu)
U~ t.o
~7
o
Z
1334
Notes
The solution of radiosulphur in TCE was boiled for 3 hr with a 10 per cent solution of HCI, for the removal of 82p, and after that, its activity was measured. In this way only a little part of the 85S (about 18~) was found in the TCE (Table 1). Operating in the same way with other irradiated material, but heating after irradiation at 920 °, 800 ° and 500°C, we succeeded in extracting with TCE 95 per cent of the total activity, the remainder being in other forms, soluble in water. The results are shown in Table 1. To demonstrate that the 85S in the TCE comes directly from the irradiated target and is not a result of isotopic exchange with the sulphur added as carrier, we treated in the same way four samples of KCI irradiated without carrier and heated, after irradiation, to 500°C. The results in Table 2 show that in this case 60-65 per cent of the activity was extracted with TCE as elementary sulphur, and the remainder was found in the aqueous solutions, in which 14.58-17"38 per cent was found as sulphate.
Discussion These results show that on heating the KC1 after irradiation at 920 ° (above the melting point of KC1) as well as at 500°C (above the boiling point of sulphur) the ssS atoms receive sufficient kinetic energy to migrate, from the point where they were formed, to the surface of the KC1 crystals, where they can be extracted, with elementary sulphur as carrier, or directly, by dissolving in TCE. This suggests an incompatibility of the 35S atoms with the crystalline lattice of KC1, and therefore that they cannot exist as ions, but in elementary form, a very reactive state which can easily change to another chemical form, by reaction with the solvent medium. The proportion of 35S extracted in elementary form from the KCI irradiated without carrier, nearly coincides with the value of 65 per cent found by KosKI for the radiosulphur as sulphate. At the same time, the results confirm Milham's supposition that about 60 per cent of the radiosulphur activity is in a reactive form--probably Sl°--which undergoes immediate oxidation on dissolving in water. The experimental fact that 90 per cent of radiosulphur can be found as S2- by dissolving the degassed and in vacuum sublimed KCI, in alkaline sulphide solutions, can be explained, in our opinion, by the reaction of the elementary 85S atoms with the S ~- ion to form disulphide ion $22-, or by an isotopic exchange of 36S atoms with the S 2- sulphide ions.
Conclusions The results obtained show that the 35S produced from ssC1 by the (n,p) reaction, is present in the elementary form in the KCI and that the results obtained by K o s ~ - - 6 5 per cent of the 85S as sulphate--represent, in our opinion, a subsequent oxidation of the 35S. C. CHIOTAN Institute for Atomic Physics I. ZAMFIR Bucharest, Roumania M. SZABO