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Aqueous Chemistry of Rf and Db
7th Workshop on the Chemistry of theHeaviest ElementsMainz, Germany, October 12-13, 2009
Y. Nagamefor
JAEA-RIKEN-Osaka-Niigata-TMU-Tsukuba-Kanazawa-Shizuoka-GSI-Mainz
collaboration
Contents1. Introduction – Aqueous chemistry of Rf at JAEA2. Fluoro complex formation of Rf
Anion-exchange chromatography in HF andin HF/HNO3
Cation-exchange chromatography in HF/HNO3
3. Fluoro complex formation of Db – AIX in HFAIX in HF/HNO3with AIDA-II
Kasamatsu4. Conclusions
JAEA Tandem Accelerator
1. Chloro complex formation: [MCl6]2-
Anion-exchange chromatography: Rf Zr > HfEXAFS spectroscopy: [RfCl6]2-
2. TBP extraction (complex): MCl4(TBP)2Reversed-phase chromatography: Rf < Zr Hf
3. Nitrate complex formationAnion-exchange chromatography: Rf Zr Hf Th
4. Fluoro complex formation
5. Sulfate complex formation: in progress
Systematic investigation on aqueous chemistry of RfComparative study of Rf with the homologues Zr, Hf, and Th
1. Introduction
2. Fluoro complex formation of RfAnion-exchange chromatography in HF and HF/HNO3Cation-exchange chromatography in HF/HNO3
1 181 2
2 13 14 15 16 173 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18
3 4 5 6 7 8 9 10 11 1219 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 118
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
89 90 91 92 93 94 95 96 97 98 99 100 101 102 103
118
Al
Ni Cu Zn Ga
Si P S
H
Li
Na Mg
He
Be B NeFONC
Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ge As Se Br Kr
Rb XeITeSbSnInCd
Cs Ba La
MoNbZrY
Ta W
Sr
RnHg Tl Pb Bi AtPo
PdRhRuTc
Hf Re
Ag
116
Os Ir Pt Au
113 115
Lu
Mt
Tb Dy Ho ErEu
Rg 112 114
Lanthanides
DsHsDb Sg BhFr Ra Ac Rf
Ac ThActinides
YbLa Pr Nd Pm Sm GdCe Tm
No LrAm BkCm Cf Es FmPa U Np MdPu
248Cm(18O, 5n)261Rf= 13 nb
He cooling gas248Cm target (645 g/cm2) on Be backing
18O beam
HAVARWindow foil2.0 mg/cm2
Recoils Gas-jet transport
Irradiation cave248Cm(18O, 5n)261Rf (68 s)Gd(18O, xn)169Hf (3.24 min)
Gas-jet transport
Pulse motor
Eluent bottles
Air cylinder
Micro-columns
Ta disk reservoir
Signal out
PIPS detectorsPre-amp.
He gas heaterHalogen lamp
Chemistry laboratory
Experimental set-upat JAEA
Beam stop
Water cooling
Sampling table
AIDA
ARCA
AnionAnion--exchange procedure in HF with AIDAexchange procedure in HF with AIDA1. Collection of 261Rf and 169Hf for 125 s2. Dissolution with 250 L of HF solution
and feed onto the column at 740 L/min
AIX column: MCI GEL CA08Y resin (20 m)1.6 mm i.d. 7.0 mm (1.0 mm i.d. 3.5 mm)
3. 200 L of 4.0 M HCl at 1.0 mL/min
Fraction 1 (A1) Fraction 2 (A2) -spectrometry
Adsorption probability = 100 A2 / (A1 + A2) Kd
169Hf : elution behavior and chemical yields (~ 60%)
Anion-exchange experiments with 85Zr and 169Hffrom the Ge/Gd target: Ge(18O, xn)85Zr, Gd(18O, xn)169Hf
Anion-exchange behavior of Rf in HF
100
101
102
103
10-1 100
Rf
ZrHf
K d /
mL
g-1
[HF2-] / M
slope = -3[MF7]3- (M = Zr and Hf)
slope = -2[RfF6]2- ?
HF H+ + F-
HF + F- HF2-
HF H+ + F-
HF + F- HF2-
log Kd = C - n log[HF2-]
H. Haba et al., J. Am. Chem. Soc. 126, 5219 (2004).
4226 cycles of anion-exchange experiments
266 events form261Rf and 257No, 25
time correlations
Kds linearly decrease with [HF2-].
displacement of the metal fluoro complexes from the binding sitesof the resin by the counter anion HF2
-
Rn-MF4+n + n HF2- n R-HF2 + MF4+n
n- (M=Rf, Zr, and Hf), R: resin
Anion-exchange behavior of Rf in HF/HNO3
Kds linearly decrease with [NO3-].
displacement of the metal fluoro complexes from the binding sitesof the resin by the counter anion NO3
-
Rn-MF4+n + n NO3- n R-NO3 + MF4+n
n- : n = -2 [MF6]2-
100
101
102
103
104
105
10-2 10-1 100
K d /
mL
g-1
[NO3-] / M
Rf: slope = -2[RfF6]2-
Zr, Hf: slope = -2[MF6]2- (M=Zr, Hf)
closed (on-line)open (off-line)
[F-] = 3 x 10-3 M
HF H+ + F-
(HF + F- HF2-)
HNO3 H+ + NO3-
HF H+ + F-
(HF + F- HF2-)
HNO3 H+ + NO3-
A. Toyoshima et al., Radiochim. Acta 96, 125 (2008).
3788 cycles of anion-exchange experiments
334 events from261Rf and 257No, 46correlations
HF2-
counter ion101
102
103
104
10-6 10-5 10-4 10-3 10-2 10-1
Kd
/ mL
g-1
[F-] / M
0.01 M HNO3(AIX)
0.03 M HNO3(AIX)
0.01 M HNO3(AIX)
0.015 M HNO3(AIX)
0.1 M HNO3(AIX)
0.1 M HNO3(CIX)
Rf (on-line)Zr (off-line)Hf (off-line)
Rf (on-line)Zr (off-line)Hf (off-line)
Formation of [MF6]2- : Zr Hf > Rf
A. Toyoshima et al., Radiochim. Acta 96, 125 (2008).
There is about two-orders of magnitude difference in the fluoride ionconcentration of Rf and the homologues for the formation of [MF6]2-.
Anion-exchange behavior of Rf in HF/HNO3
10-1
100
101
102
103
104
105
10-7 10-6 10-5 10-4 10-3 10-2 10-1
88Zr Batch Exp.175Hf Batch Exp.85Zr Column Exp.175Hf Column Exp.234Th Batch Exp.261Rf Column Exp.261Rf Strub et al.K
d / m
L g-1
[F-] / M
Cation-exchange behavior of Rfin HF/0.1 M HNO3
M4+ + F- MF3+
MF3+ + F- MF22+
MF22+ + F- MF3
+
MF3+ + F- MF4
(M= Rf, Zr, Hf and Th)
The fluoro complex formation of Rf successively proceeds as those withthe homologues.The strength of the coordination of the fluoride ions to Rf is significantlyweaker than that to Zr and Hf. consistent with the anion-exchange study
Y. Ishii et al.,Chem. Lett. 37, 288 (2008).
Formation of anionic fluoro complexes
2d loglog DK]NO-[R
][NO2log3
-3
6
1n
nn ][F1
][Flog6
6
Consecutive formation reactions of Zr4+ and Hf4+ (M4+)M4+ + F- MF3+ K1
MF4 + F- [MF5]- K5
[MF5]- + F- [MF6]2- K6
Anion-exchange reactions between [MF6]2- and NO3-
R2-MF6 + 2NO3- 2R-NO3 + [MF6]2- : D2
n
iin K
1
stability constant
n of Zr and Hf : literature valuesA. Toyoshima et al., Radiochim. Acta 96, 125 (2008).
100
101
102
103
104
105
106
10-5 10-4 10-3 10-2
ZrHfRf
Kd /
mL
g-1
[F-] / M
0.03 M [NO3-]
0.01 M [NO3-]
0.1 M [NO3-]
0.3 M [NO3-]
0.01 M [NO3-]
0.015 M [NO3-]
Results of the calculation (solid lines)
Chemical reactionsHNO3 H+ + NO3
-
HF H+ + F-
HF + F- HF2-
acting as acounter anion
lowering Kd
The data of Zr and Hf are well reproduced by the calculations.
To reproduce the data of Rf, we carried out the same calculations byusing the consecutive formation constants as parameters: K5 and K6.
well reproduced
0
2
4
6
8
10
0 1 2 3 4 5 6 7
logK
n
n
ZrHf
Th
Rf
Consecutive formation constants of Rf[MF(n-1)]5-n + F- [MFn]4-n : Kn
The K6 value of Rf should be at least more than one-order ofmagnitude smaller than those of Zr and Hf.
Kn: Zr, Hf and Thliterature values
A. Toyoshima et al., Radiochim. Acta 96, 125 (2008).
Summary of the fluoro complexSummary of the fluoro complexformation of Rfformation of Rf
1. We clarified that Rf is present as the hexafluoro complexin dilute HF: [RfF6]2-.
2. The sequence of the fluoride complexation strengthwas clearly demonstrated: Zr Hf Rf Th.
3. A weaker fluoro complex formation of Rf as compared tothe formation of Zr and Hf would be reasonable if the sizeof the Rf4+ ion is larger than those of Zr4+ and Hf4+ asexpected:Zr4+ (72 pm) Hf4+ (71 pm) Rf4+ (78 pm) Th4+ (94 pm).
(prediction)
3. Anion3. Anion--exchange behavior of Db in HFexchange behavior of Db in HF248Cm(19F, 5n)262Db (34 s)
= 1.3 nb1 181 2
2 13 14 15 16 173 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18
3 4 5 6 7 8 9 10 11 1219 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 118
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
89 90 91 92 93 94 95 96 97 98 99 100 101 102 103
Pa U Np MdPu No LrAm BkCm Cf Es Fm
YbLa Pr Nd Pm Sm GdCe Tm
Ac ThActinides
Lanthanides
DsHsDb Sg BhFr Ra Ac Rf
Lu
Mt
Tb Dy Ho ErEu
Rg 112 114
Hf Re
Ag
116
Os Ir Pt Au
113 115
PdRhRuTc
RnHg Tl Pb Bi AtPoCs Ba La
MoNbZrY
Ta W
Sr
Br Kr
Rb XeITeSbSnInCd
Co Ge As Se
Cl Ar
K Ca Sc Ti V Cr Mn Fe
He
Be B NeFONC
H
Li
Na Mg
118
Al
Ni Cu Zn Ga
Si P S
1702 cycles of anion-exchange experiments1st effluent of 14 M HF: 6 events2nd effluent of 6 M HNO3/0.015 M HF: 4 events
Off-line with radiotracers92mNb (10.15 d)177Ta (56.6 h)233Pa (27.0 d)
On-line248Cm(19F, 5n)262DbGd(19F, xn)170Ta
Nb Ta > Db Pa in 14 M HF10-1
100
101
102
103
104
105
Db
Nb
Ta
Pa
100 101
K d /
mL
g-1
[HF]ini / M
Anion-exchange behavior of Db in 14 M HF
K. Tsukada et al., Radiochim. Acta 97, 83 (2009).
4. ConclusionsThe formation of the hexafluoro complex of Rfwas clarified, and the formation of Rf wassignificantly weaker than that of the lighterhomologues, Zr and Hf.Adsorption of Db on the anion-exchange resinwas evidently smaller than that of thehomologues, Nb and Ta, in 14 M HF.
The fluoro complex formation of Rf and Dbis remarkably different from that of thehomologues.
AcknowledgementsAcknowledgementsJAEAJAEA -- M. Asai, Y. Ishii, Z. J. Li, T. Kikuchi, N. Sato,M. Asai, Y. Ishii, Z. J. Li, T. Kikuchi, N. Sato,
T. K. Sato, A. Toyoshima, and K. TsukadaT. K. Sato, A. Toyoshima, and K. TsukadaRIKENRIKEN -- H. Haba and Y. KasamatsuH. Haba and Y. KasamatsuOsaka UnivOsaka Univ.. -- H. Kikunaga and A. ShinoharaH. Kikunaga and A. ShinoharaNiigata UnivNiigata Univ.. -- S. Goto and H. KudoS. Goto and H. KudoTokyo Metropolitan UnivTokyo Metropolitan Univ.. –– K. Akiyama and Y. OuraK. Akiyama and Y. OuraUniv. TsukubaUniv. Tsukuba -- K. SuekiK. SuekiKanazawa UnivKanazawa Univ.. –– W. Sato and A. YokoyamaW. Sato and A. YokoyamaShizuoka Univ.Shizuoka Univ. -- H. SuganumaH. SuganumaGSIGSI -- W. BrW. Brüüchle, Ch. E. Dchle, Ch. E. Düüllmann, V. Pershina, andllmann, V. Pershina, and
M. SchM. SchäädeldelUniv. MainzUniv. Mainz -- J. V. KratzJ. V. Kratz
101
102
103
104
10-3 10-2 10-1 100
RfZrHfTh
Kd /
mL
g-1
[H+] / M
Slope -2.5
Cation-exchange behavior of Rfin HF/HNO3 at [F-] = 1.06 10-4 M
logKd = -(4-n)log[H+] + Cn: average number of
the coordinatedfluoride ions to M4+
[RfF]3+ and [RfF2]2+
Y. Ishii et al., Ph. D. thesis (2008).
(4-n)H+ + MFn(4-n)+
Resin (4-n)H+Resin + MFn
(4-n)+
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