% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@INPROCEEDINGS{Brandt:138578,
      author       = {Brandt, Felix and Klinkenberg, Martina and Vinograd, Victor
                      and Rozov, Konstantin and Bosbach, Dirk},
      title        = {{S}olid solution formation and uptake of {R}adium in the
                      presence of barite},
      reportid     = {FZJ-2013-04677},
      year         = {2013},
      abstract     = {The phase relations in the BaSO4-RaSO4-H2O system may
                      determine the solubility of radium in natural waters due to
                      the formation of a solid solution. In the near-field of
                      nuclear waste repositories for spent fuel, radium may enter
                      a system in which barite is in equilibrium with the aqueous
                      solution. Thermodynamically, a RaxBa1-xSO4 solid solution is
                      expected to form as solubility controlling phase rather than
                      RaSO4. However, due to a lack of reliable data, the solid
                      solution system RaSO4-BaSO4-H2O is currently not considered
                      in long term safety assessments for nuclear waste
                      repositories. The solubility product of the pure RaSO4
                      endmember is poorly constrained between pKRaSO4 = 10.26 to
                      10.41 by only very few experimental data [1,2]. Published
                      interaction parameters WBaRa of the RaSO4-BaSO4-H2O system
                      varies varies in different studies [3, 4] between 0.9 and
                      3.9 - 6.5 kJ/mol. In this study we have combined
                      experimental data, atomistic calculations and thermodynamic
                      modeling to study in detail how a radium containing solution
                      will equilibrate with solid BaSO4 under repository relevant
                      conditions. Batch sorption experiments at close to
                      equilibrium conditions indicate the formation of a
                      RaxBa1-xSO4 solid. Our first principles calculations based
                      on the single defect method [5] indicate a value of WBaRa =
                      2.5 ± 1.0 kJ/mol, implying a non-ideal solid solution.
                      Thermodynamic assessment calculations indicate that the
                      final experimental Ra(aq) concentration at room temperature
                      and 90 °C can be matched with WBaRa ≈ 1.5 kJ/mol and
                      pKRaSO4 ≈ 10.41. [1] Lind, S. C., et al (1918). J Am Chem
                      Soc 40, 465-472. [2] Paige, C. R. et al.(1998). Geochim.
                      Cosmochim. Acta 62, 15-23. [3] Zhu, C., 2004. Geochim.
                      Cosmochim. Acta 68, 3327-3337. [4] Curti, E., et al. (2010).
                      Geochim. Cosmochim. Acta 74, 3553-3570. [5] Sluiter $\&$
                      Kawazoe (2002) Europhys Lett. 57, 526-532.},
      month         = {Aug},
      date          = {2013-08-25},
      organization  = {Goldschmidt Conference 2013, Firenze
                       (Italy), 25 Aug 2013 - 30 Aug 2013},
      subtyp        = {Other},
      cin          = {IEK-6},
      cid          = {I:(DE-Juel1)IEK-6-20101013},
      pnm          = {142 - Safety Research for Nuclear Waste Disposal (POF2-142)
                      / SKIN - Slow processes in close-to-equilibrium conditions
                      for radionuclides in water/solid systems of relevance to
                      nuclear waste management (269688)},
      pid          = {G:(DE-HGF)POF2-142 / G:(EU-Grant)269688},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/138578},
}