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Electric Double Layer

Posted May 28, 2015, 9:55 a.m. EDT Version 5.1 0 Replies

Christoforos Panteli
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Hello,

I need some help and experience please, on modelling the Electrical Double Layer using the Electrochemistry module.

I need to extract the plots:
1. potential in solution Vs distance (from insulator) for different pH values of the solution
2. concentration of ions Vs distance (from insulator) for different pH values of the solution

I apply the Gouy - Chapmann - Stern theory to solve the problem. According to Nernst equation the pH sensitivity in solution is 59 mV per pH. I define the surface potential of the insulator in the solution to be 59 mV * pH and then I sweep the pH from 1 to 14.

I expect to see a 59 mV shift at the surface of the insulator per pH. When I plot the surface potential Vs pH in MATLAB, I do get the 59 mV per pH slope. When I plot the surface potential Vs distance from insulator in COMSOL I don't get 59 mV per pH shift (plot attached).

Can someone please help me with this strange result?

Thank you!
0 Replies Last Post May 28, 2015, 9:55 a.m. EDT
COMSOL Moderator

Hello Christoforos Panteli

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