Porosity Determinations from the Isotherm

There are three classifications of porosity. Officially the lUPAC has classified these according to pore diameter as follows  

How to exactly calculate porosity from the isotherms is a matter of much discussion at this time. The following is one method of interpreting the isotherm with respect to porosity. It is a more detailed and advanced method than presented in Chapter 6. 

Some typical data which indicate microporosity are in Fig. 36. The data used are from Goldman and Polanyi [22] for CS2 adsorption on activated charcoal. Not much can be deduced from this isotherm as presented. A transformation of the plot (Fig. 37) using a standard isotherm begins the process. 

Leave the y-axis as amount adsorbed, preferably in units of moles. Transform the PIP using a standard plot. Here the analytical [23] x plot equation is being used for the standard plot. 

Fit the high and low values to a straight line. These are labeled in the figure as 5 and 5/,. 

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