Such surfactants are anionic, nonionic, cationic, zwitterionic, anionic-nonionic, cationic-nonionic and so on.
1, Gemini surfactant has two hydrophobic chains and hydrophilic groups;
2, the linking group can be a short-chain group; It can be a rigid group, a flexible group, a hydrophilic group or a hydrophobic group.
3. Hydrophilic headgroups can be anionic (sulfonate, sulfate, carboxylate) or cationic (ammonium salt) or nonionic (sugar, polyether).
4. Most of the reported Gemini surfactants are symmetrical, and asymmetric Gemini surfactants have also been reported.
5. There are also reports about the synthesis of surfactants with hydrophilic head groups and hydrophobic chain structures.
Molecular structure determines performance, and performance determines its application range. The unique structure of Gemini surfactants determines their unique properties, which makes them have special applications. For example, in cosmetics, low cmc means that Gemini surfactants are less irritating to the skin than ordinary surfactants. This is because the irritation to the skin comes from common surfactants that are not micellized, and the lower cmc value means that there are fewer single-radical surfactants in the solution. The low cmc value of Gemini surfactant shows that it can dissolve water-insoluble substances at a lower concentration than ordinary surfactants, because only when the solution concentration exceeds cmc, the water-insoluble substances will enter the micelle and be dissolved.
Compared with common surfactants, the adsorption capacity of Gemini surfactants at the solution interface is 100- 1000 times. This means that Gemini surfactants are more efficient than ordinary surfactants. For example, the concentration of Gemini surfactant required to reduce the surface tension of solution, foam or emulsion or microemulsion is lower than that of ordinary surfactant.
With the development of surfactant technology, special surfactants have been developed for emergency treatment of leakage, among which the patented technology of Besoft in the United States is relatively mature. It is water-based, non-flashpoint, non-flammable, non-enzymatic, non-microbial, non-detergent, non-phosphorus, non-toxic, non-corrosive and harmless to vegetation, animals, water and water layers. It is mainly used to safely control the pollution caused by oil and fuel leakage and other hydrocarbons.
Action principle: lipophilic and hydrophilic, it is an aqueous surfactant with a mixing ratio of 2%-6%. It does not react with oil, but physically wraps and locks the oil like a capsule. It can "capture" hydrocarbon molecules, keep them in solution to form latex, and release them from hard surfaces (such as metal, concrete and asphalt) in a form that can be removed by water. This latex is neither volatile nor biodegradable. It is an effective method to repair engine oil and remove fuel pollution.
Application fields: 1, emergency leakage treatment 2, steam suppression and odor control 3, soil remediation 4, tank cleaning 5, equipment decontamination.