Aqueous Chemistry of Rf and Db Y. Nagame for JAEA-RIKEN-Osaka-Niigata-TMU-Tsukuba- Kanazawa-Shizuoka-GSI-Mainz collaboration 7 th Workshop on the Chemistry of the Heaviest Elements Mainz, Germany, October 12-13, 2009
Contents 1. Introduction Aqueous chemistry of Rf at JAEA 2. Fluoro complex formation of Rf Anion-exchange chromatography in HF and in HF/HNO 3 Cation-exchange chromatography in HF/HNO 3 3. Fluoro complex formation of Db AIX in HF AIX in HF/HNO 3 with AIDA-II Kasamatsu 4. Conclusions JAEA Tandem Accelerator
1. Introduction Systematic investigation on aqueous chemistry of Rf Comparative study of Rf with the homologues Zr, Hf, and Th 1. Chloro complex formation: [MCl 6 ] 2- Anion-exchange chromatography: Rf Zr > Hf EXAFS spectroscopy: [RfCl 6 ] 2-2. TBP extraction (complex): MCl 4 (TBP) 2 Reversed-phase chromatography: Rf < Zr Hf 3. Nitrate complex formation Anion-exchange chromatography: Rf Zr Hf Th 4. Fluoro complex formation 5. Sulfate complex formation: in progress
2. Fluoro complex formation of Rf Anion-exchange chromatography in HF and HF/HNO 3 Cation-exchange chromatography in HF/HNO 3 1 18 1 2 H 2 13 14 15 16 17 3 4 5 6 7 8 9 10 Li 11 12 13 14 15 16 17 18 Na Be B C N O F Ne Mg 3 4 5 6 7 8 9 10 11 12 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Zr Hf 87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 118 Fr Ra Ac Rf 248 Cm( 18 O, 5n) 261 Rf = 13 nb Nb Ta Mo W Tc Re Db Sg Bh Ru Rh Pd Ag Os Ir Pt Au Hs Mt Ds Cd Al In Si P S Sn Sb Te Cl Hg Tl Pb Bi Po At Rg 112 113 114 115 116 I He Ar Xe Rn 118 Lanthanides Actinides 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Ac Th Tm Pa U Np Pu Am Cm Bk Cf Es Fm Md Yb No Lu Lr
18 O beam He cooling gas 248 Cm target (645 g/cm 2 ) on Be backing Water cooling Beam stop HAVAR Window foil Recoils Gas-jet transport 2.0 mg/cm 2 Irradiation cave 248 Cm( 18 O, 5n) 261 Rf (68 s) Gd( 18 O, xn) 169 Hf (3.24 min) Experimental set-up at JAEA Signal out Chemistry laboratory Gas-jet transport Pulse motor AIDA PIPS detectors Pre-amp. Air cylinder ARCA Eluent bottles Micro-columns Sampling table Halogen lamp He gas heater Ta disk reservoir
Anion-exchange procedure in HF with AIDA 1. Collection of 261 Rf and 169 Hf for 125 s 2. Dissolution with 250 L of HF solution and feed onto the column at 740 L/min 3. 200 L of 4.0 M HCl at 1.0 ml/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) Fraction 1 (A 1 ) Fraction 2 (A 2 ) -spectrometry Adsorption probability = 100 A 2 / (A 1 + A 2 ) K d 169 Hf : elution behavior and chemical yields (~ 60%) Anion-exchange experiments with 85 Zr and 169 Hf from the Ge/Gd target: Ge( 18 O, xn) 85 Zr, Gd( 18 O, xn) 169 Hf
K d / ml g -1 Anion-exchange behavior of Rf in HF 10 3 10 2 10 1 10 0 slope = -2 [RfF 6 ] 2-? Rf Hf Zr slope = -3 [MF 7 ] 3- (M = Zr and Hf) 10-1 10 0 [HF 2 -] / M HF H + + F - HF + F - HF - 2 4226 cycles of anionexchange experiments 266 events form 261 Rf and 257 No, 25 time correlations log K d = C - n log[hf 2- ] K d s linearly decrease with [HF 2- ]. displacement of the metal fluoro complexes from the binding sites of the resin by the counter anion HF 2 - R n -MF 4+n + n HF 2- n R-HF 2 + MF 4+n n- (M=Rf, Zr, and Hf), R: resin H. Haba et al., J. Am. Chem. Soc. 126, 5219 (2004).
K d / ml g -1 Anion-exchange behavior of Rf in HF/HNO 3 10 5 10 4 10 3 10 2 10 1 10 0 Zr, Hf: slope = -2 [MF 6 ] 2- (M=Zr, Hf) Rf: slope = -2 [RfF 6 ] 2- closed (on-line) open (off-line) 10-2 10-1 10 0 [NO 3 -] / M HF H + + F - (HF + F - HF 2- ) HNO 3 H + + NO - 3 [F - ] = 3 x 10-3 M K d s linearly decrease with [NO 3- ]. displacement of the metal fluoro complexes from the binding sites of the resin by the counter anion NO 3 - R n -MF 4+n + n NO 3- n R-NO 3 + MF 4+n n- : n = -2 [MF 6 ] 2-3788 cycles of anionexchange experiments 334 events from 261 Rf and 257 No, 46 correlations A. Toyoshima et al., Radiochim. Acta 96, 125 (2008).
Anion-exchange behavior of Rf in HF/HNO 3 10 4 0.01 M HNO 3 (AIX) K d / ml g -1 10 3 10 2 0.1 M HNO 3 (CIX) 0.03 M HNO 3 (AIX) 0.1 M HNO 3 (AIX) Rf (on-line) Zr (off-line) Hf (off-line) 0.01 M HNO 3 (AIX) 0.015 M HNO 3 (AIX) 10 10 1 10-5 10-4 10-3 10-2 10-1 [F - ] / M HF 2 - counter ion There is about two-orders of magnitude difference in the fluoride ion concentration of Rf and the homologues for the formation of [MF 6 ] 2-. Formation of [MF 6 ] 2- : Zr Hf > Rf A. Toyoshima et al., Radiochim. Acta 96, 125 (2008).
K d / ml g -1 10 5 10 4 10 3 10 2 10 1 10 0 Cation-exchange behavior of Rf in HF/0.1 M HNO 3 88 Zr Batch Exp. 175 Hf Batch Exp. 85 Zr Column Exp. 175 Hf Column Exp. 234 Th Batch Exp. 261 Rf Column Exp. 261 Rf Strub et al. M 4+ + F - MF 3+ MF 3+ + F - MF 2+ 2 MF 2+ 2 + F - MF + 3 MF + 3 + F - MF 4 (M= Rf, Zr, Hf and Th) 10-1 10-7 10-6 10-5 10-4 10-3 10-2 10-1 [F - ] / M Y. Ishii et al., Chem. Lett. 37, 288 (2008). The fluoro complex formation of Rf successively proceeds as those with the homologues. The strength of the coordination of the fluoride ions to Rf is significantly weaker than that to Zr and Hf. consistent with the anion-exchange study
Formation of anionic fluoro complexes Consecutive formation reactions of Zr 4+ and Hf 4+ (M 4+ ) M 4+ + F - MF 3+ K 1 MF 4 + F - [MF 5 ] - K 5 [MF 5 ] - + F - [MF 6 ] 2- K 6 stability constant n n K i i 1 Anion-exchange reactions between [MF 6 ] 2- and NO 3 - R 2 -MF 6 + 2NO 3-2R-NO 3 + [MF 6 ] 2- : D 2 logk d logd 2 [NO3 ] 2log [R -NO n of Zr and Hf : literature values - 3 ] log 1 6 6 n 1 [F n ] 6 [F A. Toyoshima et al., Radiochim. Acta 96, 125 (2008). ] n
Results of the calculation (solid lines) K d / ml g -1 10 6 10 5 10 4 10 3 10 2 Zr Hf Rf 0.3 M [NO 3 -] 0.1 M [NO 3 -] 0.03 M [NO 3- ] 0.01 M [NO 3 - ] 0.01 M [NO 3 -] Chemical reactions HNO 3 H + + NO 3 - HF H + + F - HF + F - HF 2 - acting as a counter anion lowering K d 10 1 0.015 M [NO 3 -] 10 0 10-5 10-4 10-3 10-2 [F - ] / M The data of Zr and Hf are well reproduced by the calculations. To reproduce the data of Rf, we carried out the same calculations by using the consecutive formation constants as parameters: K 5 and K 6. well reproduced
Consecutive formation constants of Rf 10 [MF (n-1) ] 5-n + F - [MF n ] 4-n : K n logk n 8 6 4 Th Hf Zr K n : Zr, Hf and Th literature values 2 Rf 0 0 1 2 3 4 5 6 7 n The K 6 value of Rf should be at least more than one-order of magnitude smaller than those of Zr and Hf. A. Toyoshima et al., Radiochim. Acta 96, 125 (2008).
Summary of the fluoro complex formation of Rf 1. We clarified that Rf is present as the hexafluoro complex in dilute HF: [RfF 6 ] 2-. 2. The sequence of the fluoride complexation strength was clearly demonstrated: Zr Hf Rf Th. 3. A weaker fluoro complex formation of Rf as compared to the formation of Zr and Hf would be reasonable if the size of the Rf 4+ ion is larger than those of Zr 4+ and Hf 4+ as expected: Zr 4+ (72 pm) Hf 4+ (71 pm) Rf 4+ (78 pm) Th 4+ (94 pm). (prediction)
3. Anion-exchange behavior of Db in HF 248 Cm( 19 F, 5n) 262 Db (34 s) = 1.3 nb 1 18 1 2 H 2 13 14 15 16 17 3 4 5 6 7 8 9 10 Li 11 12 13 14 15 16 17 18 Na 3 4 5 6 7 8 9 10 11 12 19 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 Rb Be B C N O F Ne Mg K Ca Sc Ti V Cr Mn Fe Sr Y 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Zr Hf 87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 118 Fr Ra Ac Rf Nb Ta Mo W Tc Re Db Sg Bh Ru Hs Co Ni Cu Zn Ga Ge As Se Rh Mt Pd Ds Ag Os Ir Pt Au Cd Al In Si P S Sn Sb Hg Tl Pb Bi Po At Rg 112 113 114 115 Te 116 Cl Br I He Ar Kr Xe Rn 118 Lanthanides Actinides 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
Anion-exchange behavior of Db in 14 M HF 10 5 1702 cycles of anion-exchange experiments 1st effluent of 14 M HF: 6 events 2nd effluent of 6 M HNO 3 /0.015 M HF: 4 events 10 4 K d / ml g -1 10 3 10 2 10 1 10 0 Db Nb Ta Off-line with radiotracers 92m Nb (10.15 d) 177 Ta (56.6 h) 233 Pa (27.0 d) On-line 248 Cm( 19 F, 5n) 262 Db Gd( 19 F, xn) 170 Ta Pa 10-1 10 0 10 1 [HF] ini / M Nb Ta > Db Pa in 14 M HF K. Tsukada et al., Radiochim. Acta 97, 83 (2009).
4. Conclusions The formation of the hexafluoro complex of Rf was clarified, and the formation of Rf was significantly weaker than that of the lighter homologues, Zr and Hf. Adsorption of Db on the anion-exchange resin was evidently smaller than that of the homologues, Nb and Ta, in 14 M HF. The fluoro complex formation of Rf and Db is remarkably different from that of the homologues.
Acknowledgements JAEA - M. Asai, Y. Ishii, Z. J. Li, T. Kikuchi, N. Sato, T. K. Sato, A. Toyoshima, and K. Tsukada RIKEN - H. Haba and Y. Kasamatsu Osaka Univ. - H. Kikunaga and A. Shinohara Niigata Univ. - S. Goto and H. Kudo Tokyo Metropolitan Univ. K. Akiyama and Y. Oura Univ. Tsukuba - K. Sueki Kanazawa Univ. W. Sato and A. Yokoyama Shizuoka Univ. - H. Suganuma GSI - W. Brüchle, Ch. E. Düllmann, D V. Pershina, and M. Schädel Univ. Mainz - J. V. Kratz
Thank you for your attention
Cation-exchange behavior of Rf in HF/HNO 3 at [F - ] = 1.06 10-4 M (4-n)H + + MF n (4-n)+ Resin (4-n)H + Resin + MF n (4-n)+ K d / ml g -1 10 4 10 3 10 2 Slope -2.5 Rf Zr Hf Th logk d = -(4-n)log[H + ] + C n: average number of the coordinated fluoride ions to M 4+ [RfF] 3+ and [RfF 2 ] 2+ 10 1 10-3 10-2 10-1 10 0 [H + ] / M Y. Ishii et al., Ph. D. thesis (2008).