Gouy-Chapman model of the double layer

Fig. 3.6 The Gouy-Chapman model of the double layer, (a) Arrangement of the ions in a diffuse way (b) Variation of the electrostatic potential, 0, with distance, x, from the electrode, showing effect of ion concentration, c. (c) Variation of Cd with potential, showing the minimum at the point of zero charge Ez.

Figure 1.15 Gouy-Chapman model of the double layer...

Considering all the assumptions and approximations involved in the derivation of the Gouy-Chapman model of the double layer, it should be obvious that a real situation is likely to be much more complex. Nevertheless, results obtained based on that model have served (and continue to serve) well in furthering our understanding of electrical phenomena in colloidal systems. Further refinements of double layer theory have succeeded in explaining a number of bothersome observations in specific situations, especially very high surface potentials. However, the complications involved in their application, and the benefits derived, do not generally warrant such effort in most practical situations. 

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