Interfacial structure of silica sols

Ramsay et al. Formation and Interfacial Structure of Silica Sols... 

Furthermore, the particle core has a density consistent with amorphous silica. The adsorption of oligomers around the core of the particles has implications that may explain the high charge density and exceptional stability of silica sols (9). Enhanced stability may also arise from solvation forces. Such an interfacial structure has important consequences in both determining the mechanism and enhancing the capacity for sorption of other ionic species from solution. 

In this chapter we wUI describe some recent investigations of the formation and interfacial structure of a series of commercially produced sUica sols (Nalco, Dupont, and Ludox) with different diameters in the range 1-30 nm. This type of sol, which has wide industrial applications, has been used as a model system in numerous studies of coUoidal silica, although in general, the nature of the silica-water interface has received little attention. The interfacial structure may well explain some of the unusual properties of silica sols, such as the high surface charge and exceptional colloidal stability together with the enhanced capacity for sorption and com-plexation of ionic species in solution. Indeed in the past these features have been ascribed to a surface gel layer ... 

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