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| Titel |
Coulombic effects and multicomponent ionic dispersion during transport of electrolytes in porous media |
| VerfasserIn |
Muhammad Muniruzzaman, Christina Haberer, Peter Grathwohl, Massimo Rolle |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091765
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| Publikation (Nr.) |
 EGU/EGU2014-6074.pdf |
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| Zusammenfassung |
| We study the influence of Coulombic effects on transport of charged species in saturated
porous media in advection-dominated flow regimes. We focus on transverse hydrodynamic
dispersion and we performed quasi two-dimensional flow-through experiments in
homogeneous and spatially variable flow fields to investigate transport of dilute electrolyte
solutions. The experiments were conducted at flow velocities (1.0, 1.5 and 6 m/day) where
advection is the dominant mass transfer process. High-resolution measurements at the outlet
were performed to determine the concentration of different cations and anions. In order to
interpret the laboratory experiments we develop a two-dimensional numerical model. The
adopted modeling approach is based on a multicomponent formulation, charge conservation,
and the accurate description of local transverse dispersion. The latter entails a non-linear
dependence of the transverse dispersion coefficient on the flow velocity as well as a
compound-specific dependence on the molecular diffusion of the transported solutes. The
model was benchmarked by comparing the results of the 2D steady-state multicomponent
simulations with 1D transient results of PHREEQC in homogeneous scenarios, and it
was successively used to quantitatively evaluate the experimental results in both
homogeneous and heterogeneous porous media. Our experimental and modeling results
show that Coulombic cross-coupling of dispersive fluxes of charged species in
porous media significantly affects the lateral displacement of charged ions in both
homogeneous and heterogeneous flow-through systems. Such effects are remarkable
not only in diffusion-dominated but also in advection-dominated flow regimes. |
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