surfactant refers to a substance with fixed hydrophilic and oilophilic groups, which can be oriented on the surface of the solution and reduce the surface tension significantly.
The molecular structure of surfactants is amphiphilic: one end is a hydrophilic group, the other end is a hydrophobic group; Hydrophilic groups are often polar groups, such as carboxylic acid, sulfonic acid, sulfuric acid, amino or amine groups and their salts, but also hydroxyl, amide, ether bonds; Hydrophobic groups are often non-polar hydrocarbon chains, such as hydrocarbon chains with more than 8 carbon atoms. Surfactants are divided into ionic surfactants and non-ionic surfactants. There are many ways to classify surfactants, according to the structure of hydrophobic groups, including straight chain, branched chain, aromatic chain, fluorine-containing long chain, etc. According to the hydrophilic group, it can be divided into carboxylate, sulfate, quaternary ammonium salt, PEO derivative, lactone, etc. Some researchers are divided into ionic and non-ionic types according to the ionic nature of its molecular composition, as well as various classification methods according to its water solubility, chemical structure characteristics, and raw material sources. It is generally believed that it is more appropriate to classify it according to its chemical structure. That is, when the surfactant is dissolved in water, it is divided into ionic surfactants and non-ionic surfactants according to whether ions are generated and their electrical properties. According to the dissociation properties of polar groups:
1, anionic surfactant: stearic acid, sodium dodecyl benzene sulfonate
2, cationic surfactant: quaternary ammonium
3, zwitterionic surfactant: lecithin, amino acid type, betaine type
4, non-ionic surfactants: fatty acid glyceride, fatty acid sorbitan (Pan), polysorbate (Tween)
The application and effect of surfactants: surfactants have a series of physical and chemical effects such as wetting or anti-viscosity, emulsification or breaking milk, foaming or defoaming, solublization, dispersion, washing, corrosion prevention, antistatic, etc., and the corresponding practical applications, becoming a flexible and versatile fine chemical products with wide uses. Surfactants in addition to daily life as detergents, other applications can cover almost all fine chemical fields. Surfactant action: 1. Solubilization; 2. Emulsification; 3. Wetting effect; 4. Suspension effect; 5. Foaming and defoaming effect; 6. Disinfection and sterilization; 7. Descaling and washing effect.