Thermal Effects on Chemical Diffusion in Multicomponent Ionic Systems
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.
KeywordsMulticomponent chemicals Thermal diffusion Clay barrier Theoretical modeling
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