Bentonite is a kind of clay with montmorillonite as the main mineral component. As shown in the data of this book [see the chapter “Montmorillonite (Bentonite),” Fig. 1], the strong covalent bonds and ionic bonds within the structural layers of montmorillonite, and the weak ionic bonds between the structural layers make montmorillonite have good exfoliation and dispersion. Because montmorillonite has both expansibility and ion exchangeability at the same time, its layer structure is controllably transformable. This creates unique conditions for the processing and preparing functional materials of bentonite minerals through chemical modification and transformation methods. Comparatively typical functional materials of bentonite minerals include activated clay, sodium bentonite, and organic bentonite (Zheng and Yuan 2005).