The specific surface area is an important characteristic in determining
the chemical and physical interaction of the soil with its surroundings.
This is due to the fact that most of the chemical reactions
in soils take place at the surface of particles (Mitchell and Soga,
2005). One of the most common methods for determining the surface
area of finely divided materials is that of Brunauer et al. (1938), known
as the BET method. The method is based on collecting isotherm data
for the physical adsorption of an inert gas and modeling the adsorption
data using the following BET isotherm equation