Chapter 12.9 Surface Area and Porosity

This chapter describes the measurement of important surface properties, such as surface area and porosity. The specific surface area (SSA) of clay minerals and related materials is one of their most important properties controlling surface phenomena. The SSA of nonswelling and nonmicroporous phyllosilicates ranges from a fraction to more than one hundred square meters per gram. Higher values are obtained with microporous clay minerals (sepiolite and palygorskite) and swelling (expanding) clay minerals. Clay minerals play an important role in natural and industrial processes as they can take up organic and inorganic molecules at solid–liquid or solid–gas interfaces. The surface properties of these minerals have to be precisely determined to gain an insight into the underlying mechanisms. The chapter has two parts: the first is concerned with the determination of the SSA of clay minerals and related topics and the second part is specific to swelling clay minerals.