Colloidal systems ultracentrifugation

In the above definition of s, x is the distance of the particle from the rotation axis, and it has dimensions of time. It is often expressed in Svedberg units (1 S = 10 s), in honour of T. Svedberg who pioneered this field and introduced the use of ultracentrifugation in the study of colloidal systems. 

Similar ultracentrifugation experiments were carried out with systems at pH values below the precipitation region. However, the results were identical to those obtained using the lower speed centrifuge as shown in Figure 1. It is therefore concluded that over the low pH range and the concentrations used the solutions of hafnium tetrachloride are void of colloidal particles. 

An analytical ultra-centrifugation technique has been used in combination with a scanning optical absorption system for particle size distribution determination. The system was demonstrated for colloidal plulimim 0.4 to 2) nm and unstabilized zinc (4-9) nrn during particle growth [82], A review of examples of colloid analysis of nanosize particles by ultracentrifugation with a focus on multicomonent mixtures has been published.[83]... 

Miller, C.A., Reinan, H., Benton, W.J., Tomlinson, F., 1977. A mechanism for ultralow interfacial tension in systems containing microemulsion— theoretical consideration and experiments with ultracentrifuge. J. Colloid Interface Sd. 61, 554. 

Anyone who examines the outline of Volume I and the Contents of Volume II will decide that this work does not cover the whole of colloid science. This may readily be conceded and was done deliberately. We have been conscious from the beginning that a sufficiently expert collaborator was not to be found within our circle for every branch I may mention the disperse systems in gaseous media as an example. In such cases we have deliberately waived the treatment of them. In addition there are branches about which excellent monographs exist as an example I may mention the application of the ultracentrifuge. In such cases we arranged to treat the subject only in so far as it demanded discussion in a general way and for the rest to refer to these monographs. 

The (Theodor) Svedberg (1884—1971). .. was a Swedish chemist who early worked on colloidal materials and developed the ultracentrifuge, which became an important analytical technique for the characterisation of colloidal suspensions. He himself employed this technique to distinguish pure proteins. In 1926 he obtained the Nobel Prize in Chemistry for his work on disperse systems . 

---