Derivation of the Isotherm for a Uniform Surface

Because all sites on a uniform surface are identical, it is sufficient to insert in the Langmuir isotherm the condition that 6 varies linearly according to an equation 

This isotherm characterized by linear variation of In p with 0 is known as the Temkin isotherm. The Temkin isotherm for nonuniform surfaces can be derived by dividing the surface into a number of uniform elanents, on each of which the heat of these elements obeys the Langmuir isotherm. The isotherm equation obtained after certain assumptions 

The isotherm Equation 2.110 appears to show that 9 may he increased indefinitely by increasing p, suggesting that there is no saturation state. This is, of course, because the equation does not apply at higher pressures and at high surface coverages. 

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