Emulsification and dispersion

Emulsification and dispersion
In the washing process, with the help of surfactant physicochemical effect and mechanical agitation, the oil is emulsified to form an O/W emulsion. Most aqueous solutions of detergents with good performance have low surface tension and oil/water interfacial tension.

In the lower interfacial tension at the same time, the surfactant in the oil / water interface to form a certain strength of the interfacial film, can prevent the aggregation of oil beads, is conducive to the stabilization of the emulsion, so that the oil stains are not easy to deposit on the surface of the goods again. The lower interfacial tension is conducive to the emulsification of the liquid dirt, and therefore conducive to the removal of liquid dirt.
Of course, the liquid dirt in the washing process is not directly dissolved in the medium, but in the role of surfactants, the first “shrinkage”, and then under the action of the water flow from the surface of the goods and be emulsified, suspended in the medium.
Solubilization
When the surfactant concentration is higher than the critical micelle concentration (cmc), micelles are formed in the solution. Some substances that are insoluble or slightly soluble in the aqueous medium will diffuse into the micelles, thus increasing their solubility in the medium significantly, an effect known as solubilization of micelles.

In addition to emulsification, the solubilization of micelles on oil, may be another major way to remove liquid dirt from solid surfaces.
Nonpolar oil is generally solubilized in the nonpolar core of micelles; polar oil may be solubilized in the polar group region of the micellar shell according to its polar size and molecular structure; for amphiphilic oil, the polar group of the oil molecule will be “anchored” on the surface of the micelles, while the nonpolar hydrocarbon chain will be inserted into the core of the micelles.
Studies have shown that when the surfactant concentration is greater than cmc, the increase in detergency is very limited, so solubilization is not a major factor affecting the washing effect in the washing process.

However, in the local washing process (such as clothing local smear soap or other detergents scrubbing, as well as soap wash face, hand washing, etc.), the amount of detergent is large, the surfactant concentration is very high, at this time, the solubilizing effect of the oil in the micelles will be the main mechanism for the removal of oil.
Foaming effect
Detergent reduces the interfacial tension between the medium / air, so that the air can be dispersed in the medium and the formation of bubbles. At the same time, the surfactant in the bubble surface to form a solid layer of directional arrangement of the film, to maintain the stability of the foam, which is foaming, bubble stabilization.
Although the foam and washing effect has no corresponding direct relationship, but it can adsorb the dirt has been dispersed so that it gathered in the foam, and dirt to the surface of the media solution.
However, in the industrial washing process or family washing machine washing process, the emergence of foam gives the impression that it is not rinsed clean, the need to increase the number of rinsing, so the machine washing is often used in low-foaming detergent.