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

Thank you for your attention

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)+