The anionic surfactant can undergo dissociation when being dissolved in water with the part of surface activity exhibiting hydrophobic anion effects. Typical anionic surfactants include soaps, alkylbenzene sulfonates, alkyl sulfonates, alkyl sulfonates, alkyl sulfates, salts of fluorinated fatty acids, silicones, fatty alcohol sulfates, polyoxyethylene fatty alcohol ether sulfates, α-olefin sulfonate, polyoxyethylene fatty alcohol phosphates ether, alkyl alcohol amide, alkyl sulfonic acid acetamide, alkyl succinate sulfonate salts, amino alcohol alkylbenzene sulfonates, naphthenates, alkylphenol sulfonate and polyoxyethylene monolaurate. Anionic surfactants are generally insoluble at low temperatures. If the concentration continued to increase, they will reach a threshold limit, then precipitating out active agent of hydration. Upon increased water temperature at a certain temperature, due to the dissolving of the micelles, leaving the solubility being rapid increased with this temperature point called as catastrophe point. This feature is hold by ionic surfactants.
There are limited numbers of hydrophilic groups in the anionic type surfactant, but there are many types of hydrophobic groups. The raw materials of important hydrophilic group include carboxylic acid, sulfonic acid ester, sulfonic acid, phosphoric acid esters; the raw materials of hydrophobic group include animal and vegetable greases and their hydrolysis products, such as fatty acids, higher alcohols and the synthesized alcohols as petrochemical raw materials, alkanes benzene, α- olefins, etc., animal and vegetable oils include coconut oil, castor oil, cottonseed oil, palm oil, sperm whale oil, beef tallow and fish oil, etc. Furthermore, the rosin acid, naphthenic acid of the natural processed products have also been frequently used. Anionic surfactants also have excellent penetration, wetting, emulsification, dispersion, solubilization, foaming, decontamination, anti-static and smoothing properties.
Anionic surfactants have the largest yield in different categories of surfactants and can’t be mixed together with cationic surfactants for application due to precipitated in the aqueous solution to become ineffective. It can be used in combination with nonionic and amphoteric surfactants. It is commonly used as detergents, wetting agents, emulsifiers and dispersing agents. It is widely used in industry. In daily chemical industry, it is used in various kinds of detergent; in the field of cosmetics, it is used as the foaming agents of shampoos, bath, various kinds of creams, toothpaste, dispersing and emulsifying agents; in the field of food, it can be used as an emulsifier, defoamers, dispersants, preservatives, solubilizers, thickening agents and protein stabilizing agents and so on; it can also be used as feed emulsifier, dispersant, stabilizer; in the field of medicine, it can be used as emulsifiers, thickeners, preservatives, antioxidants and so on;
in the textile industry, it can be used as oiling agent, dyeing auxiliaries, bleaching agents, soft processing agent; in the field of pesticides, it can be used as spraying agents, emulsifying agents and dispersants; it can be used as asphalt emulsifier in highway and urban road construction such as tall oil sulfonate; in the field of civil engineering, it can be used as the water reducing agent of cement; in the development of oil field, it can be used as emulsifier, oil displacement agent, lubricant, sand consolidation agent, blocking agent, demulsifier, corrosion inhibitor, reducing agent, fluid loss agent and son on; it can be used as an emulsifier and fuel additive in the petroleum products; in the polymer industry, it can used as an emulsifier and antistatic agents during the emulsion and polymerization, antistatic agents; metal cleaning agent; mining flotation agent; water treatment agent; the brighteners, dispersants, pitting inhibitor in the plating solution and may be added to copper plating bath and nickel plating solution; it also has applications in other fields such as paint, ink, transportation, ship-breaking and other industries.