Solution Chemistry of Radium Artem Matyskin [email protected] PhD student Nuclear Chemistry Industrial Materials Recycling group Chemistry and Chemical Engineering Department Chalmers University of Technology

Stockholm 19th of November 2015

Outline

• • • • • • •

Introduction Hydrolysis of Radium/Barium Conversion of RaSO4 into soluble form EXAFS study of RaCO3 Radium sulfate solubility Radium carbonate solubility Future work

2

Radium in the enviroment Radium – Decay product of Uranium and Thorium, Naturally Occurring Radioactive Material

Radium and Radon – half the total exposure from all sources [WAT05] Material

Activity of 226Ra

Subterranean waters of Sweden

2,5 Bq∙l-1 [SSI96]

Brazil nuts

17-27 Bq∙kg-1 [PAR08]

[WAT05] S.J. Watson, A.L. Jones etc all, Ionizing radiation exposure of the UK population: 2005 review. HPA-RPD-001 (2005) [SSI96] SSI Report, (1996). Radon in water, SSI i96-03, ISSN 0281-2339 [PAR08] Parekh, P. P., Khan, A. R., Torres, M. A., & Kitto, M. E. (2008). Concentrations of selenium, barium, and radium in Brazil nuts. Journal of Food Composition and Analysis, 21(4), 332-335.

3

Radium in industrial wastes [ANN15] Industry

226Ra

specific activity, Bq∙kg-1

Uranium mining tailings

10000 - 140000

Phosphate fertilizers

75

Rare-earth metals industry wastes

33000

Fly ash produced by coal-fired power plant

142 - 605

Peat fly ash

200

Oil equipment

1∙106

Geothermal wastes

9000

[ANN15]

Annual report 2015 SSM Chalmers University of Technology and references therein

4

Long-term contribution of used nuclear fuel radionuclides to the effective dose [SKB11]

[SKB11] Waste Management Company (2011). Long-term safety for the final repository for spent nuclear fuel at Forsmark: Main report of the SR-Site project. Sweden: Swedish Nuclear Fuel and Waste Management Company. SKB TR 11-01.

5

Modelling of radium migration in the environment Phenomena which can have influence on Radium mobility in waters [LAN85]: • Co-precipitation of sulfates: Ba(Ra)SO4 • Co-precipitation of carbonates: Ba(Ra)CO3 • Complexation of Ra2+ with OH-, Cl-, CO32- and SO42Only a few thermodynamic properties of radium were determined experimentally. Almost all were estimated theoretically. Main approaches: • Electrostatic • Empirical equations

Problems: secondary periodicity phenomenon, relativistic effect etc [LAN85]

Langmuir, D., & Riese, A. C. (1985). The thermodynamic properties of radium. Geochimica et cosmochimica acta, 49(7), 1593-1601.

6

Radium hydrolysis [ZIE05]

0  1 10 K  [OH  ] D 1  10 K  [OH  ] 1

1

[ZIE05] Zielińska, B., & Bilewicz, A. (2005). Influence of relativistic effects on hydrolysis of Ra 2+. Journal of Radioanalytical and Nuclear Chemistry, 266(2), 339-341.

7

Barium hydrolysis: ion interaction model [SPA98]

•

D

Ra2+ + 2·NaRsolid → RaR2solid + 2·Na   [ Ra 2 ]   [ Ra 2 ] [ RaR2 ]solid   [2Na ] 2    [ Ra [ RaR2 ]solid   [ Ra ]   [ Ra ] 1 [ Ra 2 ]



2

 [2Na





]

[ Ra 2 ]



 [2Na



2

]

]

lg  Na    DH   Na OH  [OH  ]   Na ClO4  [ClO4 ]   DH   Na OH  [OH  ]   Na ClO4  ( I  [OH  ])    DH   Na OH  [OH  ]   Na ClO4  I   Na ClO4  [OH  ] lg  Ra 2  4  DH   Ra OH  [OH  ]   Ra ClO4  [ClO4 ]  4  DH   Ra OH  [OH  ]   Ra ClO4  ( I  [OH  ])   4  DH   Ra OH  [OH  ]   Ra ClO4  I   Ra ClO4  [OH  ]

D   10

2DH  I  Ra ClO 4 2I  Na ClO 4 [ OH  ]( Ra OH  Ra ClO 4 2 Na OH  2 Na ClO 4 )

D    10

a b[ OH  ]

lg( D)  lg(  )  a  b  [OH  ] [SPA98] Spahiu, K., & Puigdomenech, I. (1998). On weak complex formation: re-interpretation of literature data on the Np and Pu nitrate complexation.Radiochimca Acta, 82(Supplement), 413-420.

8

Barium hydrolysis: ion interaction model fit lg( D)  lg(  )  a  b  [OH  ]

9

Barium hydrolysis: ion association model       [ Na ]total  [ Na ]  [ NaOH ]  [ NaClO ]  [ Na ]  K  [ Na ]  [ OH ]  K  [ Na ]  [ ClO aqueous 4 NaOH NaClO4 4]    [ Na ]total  [ Na ]  ( 1  K  [ OH ]  K  [ ClO aqueous NaOH NaClO4 4 ])  0

    [ClO4 ]total aqueous  [ClO4 ]  [ NaClO4 ]  [ClO4 ]  K NaClO4  [ Na ]  [ClO4 ]   [ClO4 ]total aqueous  [ClO4 ]  (1  K NaClO4  [ Na ])  0

    [OH ]total aqueous  [OH ]  [ NaOH ]  [OH ]  K NaOH  [ Na ]  [OH ]   [OH ]total  [ OH ]  ( 1  K  [ Na ])  0 aqueous NaOH

D 1 K

BaOH  1

0  1  [ClO4 ]total aqueous 1  total ( )  [ OH ]aqueous NaOH  total 1 K  [ Na ]aqueous 10

Barium hydrolysis: ion association model fit D 1  K1BaOH



0  1  [ClO4 ]total aqueous 1  total ( )  [ OH ]aqueous NaOH  total 1 K  [ Na ]aqueous

11

Barium hydrolysis: extrapolation to zero ionic strength

According to the plots stability constants of NaOH and BaOH+ complexes at zero ionis strength are 0,28 and 0,67 which is in agreement with literature data [EKB15] (-0.4 ± 0.2 for NaOH and 0.68 ± 0.07 for BaOH+) “The chief criterion for [classifying] an electrolyte [as nonassociated] is the absence of valid evidence for any form of association. Since the validity of such evidence can be a matter of personal opinion...there can be no general agreement.” – Robinson and Strokes “However, if K