Surface Areas and Pore Volume Calculations

According the x theory, the parameter G is indicative of the total surface area, inside and outside the pores, whereas H indicates the pore volume. The difference between G and H yields the external surface area, that is the surface area excluding the pore surface area. Thus, the total surface area is given by 

The external surface area includes at least two types of surfaces, the surface of the adsorbent that is not in the pores, which will be referred to as the wall area, A, and the surface area of the filled pore openings, A. Thus, 

This can cause problems in the analysis of porosity unless the external surface area is very small compared to the surface area within the pores. If one subtracts the wall surface area from the total surface area one may obtain the surface area inside the pores, A. Unfortunately, the quantity A is unknown, therefore 

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