Advertisement

Thermal Effects on Chemical Diffusion in Multicomponent Ionic Systems

  • Hywel R. ThomasEmail author
  • Majid Sedighi
Conference paper

Abstract

A theoretical formulation for diffusion of multiple ions is presented in this paper which considers the effects of electrochemical and thermal diffusion potentials. The work presented is of relevance to applications such as the geological disposal of high level radioactive waste, where limited experimental information is available on ionic transfer in compacted clay buffer under non-isothermal conditions. The proposed approach incorporates the overall charge conservation in the formulation of multicomponent chemical diffusion. Thermal diffusion, i.e. Soret effect is studied in more detail by considering an explicit approach to include this process in the formulation. A detailed description of the theoretical developments is provided. A series of simulations using the proposed formulation is presented which involves pure diffusion of multiple ions under thermal gradients. The results are compared with experimental data reported in literature.

Keywords

Multicomponent chemicals Thermal diffusion Clay barrier Theoretical modeling 

References

  1. Agar JN, Mou CY, Lin J (1989) Single-ion heat of transport in electrolyte solutions: a hydrodyamic theory. J Phys Chem 93:2079–2082CrossRefGoogle Scholar
  2. Appelo CAJ, Wersin P (2007) Multicomponent diffusion modeling in clay systems with application to the diffusion of tritium, iodide and sodium in Opalinus clay. Environ Sci Technol 41:5002–5007CrossRefGoogle Scholar
  3. Balluffi RW, Allen SM, Carter WC (2005) Kinetics of materials. Wiley Interscience, WileyCrossRefGoogle Scholar
  4. Lasaga AC (1979) The treatment of multicomponent diffusion and ion pairs in diagenetic fluxes. Am J Sci 279:324–346CrossRefGoogle Scholar
  5. Leaist DG, Hui L (1990) Conductometric determination of the Soret coefficients of a ternary mixed electrolyte, Reversed thermal diffusion of sodium chloride in aqueous sodium hydroxide solutions. J Phys Chem 94:45–447Google Scholar
  6. Pusch R, Yong RN (2006) Microstructure of smectite clays and engineering performance. Taylor and Francis, LondonGoogle Scholar
  7. Sedighi, M (2011) An investigation of hydro-geochemical processes in coupled thermal, hydraulic, chemical and mechanical behaviour of unsaturated soils. Ph.D. Thesis, Cardiff University, UKGoogle Scholar
  8. Thomas HR, He Y (1995) Analysis of coupled heat, moisture, and air transfer in a deformable unsaturated soil. Géotechnique 45:677–689CrossRefGoogle Scholar
  9. Thomas HR, Sedighi M, Vardon PJ (2012) Diffusive reactive transport of multicomponent chemicals under coupled thermal, hydraulic, chemical and mechanical conditions. Geotech Geol Eng 30(4):841–857CrossRefGoogle Scholar

Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  1. 1.Geoenvironmental Research CentreCardiff UniversityCardiffUK

Personalised recommendations