Extensions of Polanyis theory for micropore volume and area

3 Extensions of Polanyi s theory for micropore volume and area 

According to the potential theory the volume V, defined by the adsorbent s surface and the equipotential plane , can contain adsorbate in three different conditions depending upon the temperature. Above the critical temperature the adsorbate can not be liquified and the gas in the adsorption volume V simply becomes more dense near the surface. At temperatures near, but less than the critical temperature, the adsorbate is viewed as a liquid near the surface and a vapor of decreasing density away from the surface. Substantially below the critical temperature 

The potential theory asserts that the adsorption potential, when the adsorbate is in the liquid state, is given by 

According to the preceding equation, E is the isothermal work required to compress the vapor from its equilibrium pressure P to the saturated pressure Pq of the liquid in the adsorption volume. 

Using equations (9.1) and (9.2) both V and E can be calculated from an experimental isotherm. Therefore, 

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