Surfactants (Soaps and Detergents) and Physicochemical Properties - Surface and Colloid Chemistry: Principles and Applications - page 68

W Oil Phase

FIGure 3.19 Structure of the inverted micelle.

CMC

Detergency

Density

Surface Tension

Interfacial Tension

Concentration of Detergent

FIGure 3.20 Change in detergent solution properties as related to CMC (schematic).

formation of the so-called inverted micelles (Figure 3.19). In inverted micelles , polar
dirt is solubilized inside the water phase.
Detergents used for rug cleaning are tailor made. In the case of the process where
detergent solution is applied in a highly foaming state, the principle is as follows.
As the dirt is removed by the detergent solution and is present in the foam, the latter
dries and can be vacuum cleaned. This requires that the detergent is not hygroscopic
and thus easily removed. Appropriate salts (such as Li) of alkyl sulfates, which are
very weakly hygroscopic, can be used.
In general, in all such systems, an enhanced detergency is observed when the
concentration of detergent is greater than its CMC (Figure 3.20).