Coadsorption of two organic substances within the framework of a system of two mixed Frumkin isotherms

Within the framework of a system of two mixed Frumkin isotherms, the shape of the Gibbs energy surface for an adsorption layer formed by two coadsorbed organic substances is analyzed as a function of their degrees of surface coverage θ1 and θ2. It is shown that, for displacement coefficients n1=n2=1, an increase in the parameter of intermolecular interaction a12 results in a decrease in the number of possible solutions of the aforementioned system of equations. At the same time, for n1=n2=2, there exists a region of a12 parameters, in which the system of equations can have seven solutions, so that the number of possible solutions passes through a maximum with an increase in a12. The results obtained are important for simulating unstable states, which can be realized on the electrode ∣ solution interface during coadsorption of two different organic substances.