Factors Affecting Colloid Behavior and Importance

Colloid behavior in natural soil-water systems is controlled by dispersion-flocculation processes, which are multifaceted phenomena. They include surface electrical potential (El-Swaify, 1976 Stumm and Morgan, 1981), solution composition (Quirk and Schofield, 1955 Arora and Coleman, 1979 Oster et al., 1980), shape of particles, initial particle concentration in suspension (Oster et al., 1980), and type and relative proportion of clay minerals (Arora and Coleman, 1979). When suspended in water, soil colloids are classified according to their settling characteristics into settleable and nonsettleable solids. 

Nonsettleable solids are composed of solids that will not settle out within an hour. However, colloidal suspensions are very dynamic, and since the size of the particles distinguishes settleable from nonsettleable solids, the ratio between them depends on several variables (e.g., pH, type of cations in solution, and salt concentration). This is because colloids may unite (flocculate) via various mechanisms to form larger particles 

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In the field of surface and colloid science, characterization of surfaces has become an important utility in accounting for the observed behavior of any two-phase system. Many factors can affect the state of an interfacial region including van der Waals, electrostatic, acid-base, and covalent interactions between phase components. A complete account of the forces operating at an interface does much to predict and clarify the behavior of a system. In this context surface characterization is essential. 

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