Excess Charge Associated with the Specific Adsorption of Ionic Porphyrins

Excess Charge Associated with the Specific Adsorption of Ionic Porphyrins 

At constant temperature and pressure, the changes in surface tension y are related to the surface excess (F) of the various species in the system by the Gibbs 

In order to semi-quantitatively illustrate the effect of porphyrin adsorption on the differential capacitance at the polarisable liquid/liquid interface, let us redefine the potential distribution as discussed in Section 2.2. We shall simply assume one adsorption plane located at the interfacial boundary and a given concentration of 1 1 electrolytes in both phases. It follows  

Furthermore, the coverage Op can be computed by combining Equations (11.10) and (11.11) in the case of a Langmuir isotherm, 

The differential capacitance is simply defined as the first derivative of the 

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