Colloids surface area considerations

Stability Energy and Surface Area Considerations in Colloids... 

It is self-evident that the more finely subdivided a given weight of material is, the higher the surface area will be for that weight of sample. In the following section we discuss this in considerable detail since it is the basis for combining a discussion of surface and colloid science in a single book. 

The occurrence of some materials in the form of a colloidal dispersion can introduce or enhance safety hazards. Considering that the dispersion of a material down to colloidal size results in a high specific surface area, chemical reactivity in this state may differ considerably from that of the identical macroscopic material with less surface area. 

The relative motion of the two sides of the mobile double layer in electrokinesis transports electricity consequently the presence of any surface in a fluid ought to increase the conductivity of that fluid this effect is called surface conductivity . When the area of surface is considerable, as with a suspension or colloidal solution, the increase should be appreciable. Smoluchowski predicted this effect, which has been shown to exist by a good many workers,3 but the theory and its verification by experiment appear at the present time to be in a state of considerable confusion. Some workers, indeed, claim that there is no correlation4 between the potential and the surface conductivity, which seems improbable. The reader must draw his own conclusions from the litera-... 

Most of the ensuing part of this book deals with dispersed systems. These generally have one or more kinds of interface, often making up a considerable surface area. This means that surface phenomena are of paramount importance, and they are discussed in Chapter 10. Colloidal interaction forces between structural elements are also essential, as they determine rheological properties and physical stability these forces are the subject of Chapter 12. The various kinds of physical instability are treated in Chapter 13, and the nucleation phenomena involved in phase transitions in Chapter 14. Specific dispersed systems are discussed in Chapters 11 and 17. The present chapter explains important concepts and discusses geometrical aspects. 

The characterization of colloids depends on the purposes for which the information is sought because the total description would be an enormous task. Among the properties to be considered are the nature and/or distributions of purity, crystallinity, defects, size, shape, surface area, pores, adsorbed surface films, internal and surface stresses, stabUity and state of agglomeration [1, 2]. In general, the same broad characterization considerations apply whether the dispersed species are of colloidal size or nanosize (i.e. microscale or nanoscale), although clearly such things as imaging are much more difficult at the nanoscale. Some discussions of this can be found in References [3, 4]. 

Theoretically, colloidal-crystal-templated macroporous structures should have a relatively low surface area because of the dominant presence of large pores. However, macroporous carbons prepared by this mechanism can possess a high surface area because a considerable number of micropores may be present as... 

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