Pickett 's equation for limited layer adsorption, which is simpler than the original three parameter
BET equation, is derived with new assumptions. After dividnig the surface of an adsorbent into external and in tern al areas, we can apply the new equation only to the intern al Surface
where the number of layers of the adsorbate can not exceed n. The two _ parameter .
- layer Bet equation is obviously applicable to the extern al surface area .
After obtaining V and C in the usual manner, n is estimated graphically by plotting a logarithmic transform against colog x . Then V . external monolayer capacity, is computed by
assimilating a derived expression to a par a bola .
The strict applicabilixy of Pickett 's equation to the volumes of gas adsorbed internally
IS tested subsequently. To illustrate, an example of numerical calculations is given by using the
experimental data that we obtained for the adsorption isotherm of 0 2 on Woolly Albestos at - 184°,4 C.
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