Importance of Surface in Colloidal Systems

FIGURE 2.18 The importance of surface area as the particle size beeomes smaller. Schematic drawing showing how the overall area increases as the particles are further divided. Each time the cube is cut in half along the three directions, the total area doubles, so that after n cuts, the area has increased by a factor of 2 . 

As a consequence, a relevant parameter in the characterization of particles is the specific surface area, or specific area—in short, which is the area per unit mass (m kg ). It depends not only on particle size but also on surface roughness that clearly inCTeases the actual area exposed to the surrounding medium. Surface roughness arises from the fact that actual particles, especially those found in natural environments, do not have perfectly flat surfaces (which is implied in the subdivision procedure giveu earlier in the text) but display defects and irregularities that increase the total area exposed to the surrounding phase. 

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