The main function of surfactants

1. Emulsification
Due to the high surface tension of oil in water, when the oil is dropped into the water and stirred vigorously, the oil is crushed into fine beads and mixed with each other to form an emulsion, but the stirring stops and the layers are re-stratified. If you add surfactant and stir vigorously, it will not be easy to separate for a long time after stopping. This is emulsification. The reason is that the hydrophobicity of the oil is surrounded by the hydrophilic groups of the surfactant, forming a directional attraction, which reduces the work required to disperse the oil in water and makes the oil well emulsified.
2. Moisturizing effect
There is often a layer of wax, grease or scaly substances adhered to the surface of parts, which are hydrophobic. Due to the contamination of these substances, the surface of the parts is not easily wetted by water. When surfactant is added to the aqueous solution, the water droplets on the parts will be easily dispersed, greatly reducing the surface tension of the parts and achieving the purpose of wetting.
3. Solubilization
Oils can be dissolved after surfactants are added to them, but this dissolution can only occur when the concentration of surfactants reaches the critical concentration of the colloid. The solubility is determined by the solubilization object and properties. In terms of solubilization, long hydrophobic hydrocarbon chains are stronger than short hydrocarbon chains, and saturated hydrocarbon chains are stronger than unsaturated hydrocarbon chains. The solubilization effect of nonionic surfactants is generally more significant.
4. Dispersion
Solid particles such as dust and dirt particles are easier to gather together and settle in water. The molecules of surfactant can divide the solid particle aggregates into fine particles, causing them to be dispersed and suspended in the solution, which can promote the uniformity of solid particles. The role of dispersion.
5. Foam effect
The formation of foam is mainly due to the directional adsorption of active agents, which is caused by the reduction of the surface tension between the gas and liquid phases. Generally, low molecular active agents are easy to foam, while high molecular active agents have less foam. Myristate yellow has the highest foaming property, and sodium stearate has the worst foaming property. Anionic active agents have better foaming properties and foam stability than non-ionic active agents. For example, sodium alkyl benzene sulfonate has strong foaming properties. Commonly used foam stabilizers include fatty alcohol amides, carboxymethyl cellulose, etc., and foam inhibitors include fatty acids, fatty acid esters, polyethers, etc. and other nonionic surfactants.