A general method is proposed to obtain adsorption isotherms for heterogeneous surfaces from the arbitrary energy distribution functions if the Langmuir isotherm represents the individual homotattic sites. The method is limited to the temperature dependent distribution functions only. It is observed that the number of distribution functions, yielding physically meaningful isotherms, is extremely restricted on mathematical grounds. The method yields only one adsorption isotherm that is new and simple; the corresponding distribution function, however, seems to be more characteristic of homogeneous surfaces having a strictly limited energy distribution rather than that of heterogeneous surfaces with a wide variation of distributive energies.
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