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Continuity of electric displacement across liquid/liquid boundary
Posted Apr 20, 2011, 5:28 a.m. EDT Electrochemistry Version 3.5a 2 Replies
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I'm trying to model an interface between two immiscible electrolyte solutions (interface of oil phase and aqueous phase). I have 1D system and I'm currently using Nernst-Planck application modes, one for each phase.
Continuity of the electric displacement across the phase boundary has to be valid, but how to implement it with COMSOL? Or is Nernst-Planck mode taking care of the continuity (even though the model doesn't know the dielectric constants of the solvents)
Typically, cyclic voltammetry is implemented just with the diffusion application modes, and galvani potential difference is given in as a scalar expression. But in my case this approach is not valid because I want to model the polarization of the interface, also in the case where the interface potential is controlled with a common ion in both phases.
So basically I want to model cyclic voltammetry of a two electrode system with liquid-liquid interface between the electrodes.
Any help is appreciated.
Continuity of the electric displacement across the phase boundary has to be valid, but how to implement it with COMSOL? Or is Nernst-Planck mode taking care of the continuity (even though the model doesn't know the dielectric constants of the solvents)
Typically, cyclic voltammetry is implemented just with the diffusion application modes, and galvani potential difference is given in as a scalar expression. But in my case this approach is not valid because I want to model the polarization of the interface, also in the case where the interface potential is controlled with a common ion in both phases.
So basically I want to model cyclic voltammetry of a two electrode system with liquid-liquid interface between the electrodes.
Any help is appreciated.
2 Replies Last Post Apr 20, 2011, 6:48 a.m. EDT
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Posted:
1 decade ago
Hi,
As far as I understood, you are not using the Poisson equation since that the migration term is neglected in your case (a pure Diffusion process)!! So there is, no way, and no need to specify the continuity of your electric displacement because the electric field is supposed to vanish abruptly near the electrode (high concentration of your supporting electrolyte).
However, if the migration term is not neglected, so you have to combine the Poison equation to the NP equation. In this case, it is possible to set the continuity, which is taken by default when your boundary is an interior one I think!! This would correspond also to a flux continuity in the NP equation!!
I hope it helps and good luck
Cheers
As far as I understood, you are not using the Poisson equation since that the migration term is neglected in your case (a pure Diffusion process)!! So there is, no way, and no need to specify the continuity of your electric displacement because the electric field is supposed to vanish abruptly near the electrode (high concentration of your supporting electrolyte).
However, if the migration term is not neglected, so you have to combine the Poison equation to the NP equation. In this case, it is possible to set the continuity, which is taken by default when your boundary is an interior one I think!! This would correspond also to a flux continuity in the NP equation!!
I hope it helps and good luck
Cheers
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Posted:
1 decade ago
Thanks for your help.
I need to take migration into account, since the cation of my supporting electrolyte from the aqueous phase is transferring to oil phase. So I'll try to combine the Poisson equation to NP.
Let's see how this works.
I need to take migration into account, since the cation of my supporting electrolyte from the aqueous phase is transferring to oil phase. So I'll try to combine the Poisson equation to NP.
Let's see how this works.