What role does surfactant play in washing process?

2019-06-26 08:50:07

The solubilization of oil contamination by surfactant micelles may be an important mechanism for removing a small amount of liquid contamination from solid surface. Organic substances insoluble in water are added to different parts of micelles to form transparent and stable solutions because of their different properties.

Non-polar oil contamination is added to the non-polar core of micelles, and polar oil contamination is added to the polar group area of the micelle shell according to its polar size and molecular structure, or the polarity of oil contamination molecule is anchored on the surface of micelles, while non-polar hydrocarbon chains are inserted into the core of micelles. Therefore, the solubilization effect of removing oil contamination is actually that oil contamination dissolves in the washing liquid, which makes it impossible for oil contamination to deposit on the surface of the object, and greatly improves the washing effect.

The adsorption of surfactant on the surface of dirt and detergent (from solution) has an important effect on washing. This effect is mainly due to the change of interface and surface properties (such as mechanical, electrical and chemical properties) caused by adsorption.

For liquid oil contamination, the adsorption of surfactants on the oil/water interface mainly leads to the decrease of interfacial tension, which is beneficial to the cleaning of oil contamination. The decrease of interfacial tension is also conducive to the formation of larger dispersion of emulsion. At the same time, the interfacial film formed by interfacial adsorption generally has greater strength, and the adsorption membrane may be charged (if adsorbed surface active ions), so the emulsion formed has high stability and is not easy to deposit on the surface of the detergent.

The solubilization of surfactant micelles may have an important influence on the washing process, but there are many facts that do not agree with this statement. However, the emulsification of surfactants, no matter how much oil is contaminated, is always very important in the washing process. In order to make the emulsification work smoothly, the surfactant with high surface activity must be added to reduce the interfacial tension to a great extent. In this way, it can be emulsified with only a little mechanical work (a little stirring). While reducing the interfacial tension, the interfacial adsorption is accompanied by the formation of a certain interfacial film, which prevents oil beads from coalescing, which is conducive to the stability of the emulsion. The oil particles are also deposited on the solid surface step by step. However, it is obvious that the emulsification and dispersion of the oil is not enough to complete the washing process effectively. The influence of various factors.