Emulsions, Microemulsions, and Lyotropic Liquid Crystals - Surface and Colloid Chemistry: Principles and Applications - page 185

FIGure 9.5 Two oil drops (top); flocculation step (middle); coalescence (bottom).

surfactant AOT at constant temperature and water concentration. The results show
that there are transition points on the cloud point curve in a very narrow range of
concentration of surfactant AOT. The transition points changed with temperature
and water concentration. These phenomena show that a lower temperature is suitable
for forming microemulsion droplets, and that a microemulsion with high water con-
centration is likely to absorb more surfactants into the structure at the interface.

9.3.1 d I f f e r e n T e m u l S I of n r e c I p e S

9.3.1.1 cleaning and Polishing emulsions
In the application of emulsions for cleaning and polishing, a water phase and an oil
phase (a selected halogenated solvent) are needed. The emulsions are used in clean-
ing and polishing the surfaces of metals and other hard surfaces (glass, etc.).
For cleaning grease from metal surfaces, a strong alkali media (soda ash, borax,
or alkali phosphates or silicates) are needed. However, these alone cannot effectively
remove baked-on grease from metal surfaces. However, mixtures of soda and emul-
sifiers are found to be effective.

9.3.1.2 microemulsion detergent
The following examples indicate the methodology of applying micromemulsions.
Liquid detergent formulation: A light-duty microemulsion liquid detergent com-
position, useful for removing greasy soils from surfaces with both concentrated and
diluted forms, has been reported. It consists of the following components:
A moderately water-soluble complex of anionic and cationic surfactants (1 to
10%), in which the complex (the anionic and cationic moieties) are in essentially
equivalent or equimolar proportions, an anionic detergent,

A cosurfactant (1 to 5%)
An organic solvent (1 to 5%)
Water (70%)

This recipe is based on the following considerations. It is known that if an anionic
detergent (such as SDS) is mixed with a cationic detergent (such as CTAB), then a