Surfactant

Surfactant, also known as surfactant, is a substance that can significantly change the surface tension of a liquid or the interfacial tension between two phases. It was developed in the 1940s along with the development of petrochemicals, together with plastics, synthetic rubber and synthetic fibers. New chemical products. The molecule contains a hydrophilic polar group (such as a hydroxyl group, a sulfate group, a sulfonic acid group) and a hydrophobic or lipophilic, aerophilic non-polar group (such as a hydrocarbon group, which is a long-chain hydrocarbon). Gathering in the liquid at the interface of the liquid and the other phase, forming a thin molecular film so that the concentration in the surface layer of the solution is much larger than the inside of the solution, so that the surface tension thereof is greatly reduced, thereby causing wetting, emulsifying, Dispersion, foaming, etc. There are many types of surfactants, generally classified into anionic (such as alkylbenzene sulfonate), cationic (such as octadecylamine hydrochloride), nonionic (such as glyceryl stearate, etc.) and amphoteric surfactants. . This product is widely used. In daily life, washing powder is the most common surfactant. The oily oil on the clothes is gradually curled into oil beads by the oleophilic group, leaves the surface of the article, is dispersed, suspended in the medium, and removed after washing. In addition to being used for household life washing, it is often used as a wetting agent, emulsifier, dispersant, penetrant, foaming agent and bactericide in industrial and agricultural production. In terms of environmental protection, it can be used for seawater oil pollution treatment, wastewater treatment, flotation separation, dust prevention, fire fighting, etc. Anionic surfactants, such as pull-opening powder, sodium diisooctyl succinate, etc., can be used to uniformly coat the emulsion, and have sterilization, foaming and defoaming to prevent the occurrence of comets. Defects such as spots and dots. It can also be used for developing stabilizers. In the flotation of galena, a surfactant (such as sodium xanthate) in the flotation agent is adsorbed on the surface of the galena to form lead xanthate. The acid group is combined with the metal on the solid surface, and the hydrocarbon-based tail is arranged outward, so that the wettability of the galena is lowered, and the bubble is floated up to achieve separation and enrichment with the pulse surface. In agriculture, the leaf fertilizer containing surfactant is applied to the leaves of crops, which has the characteristics of quick fertilizer efficiency, low cost and remarkable yield increasing effect, and has been widely applied to crops such as tea, watermelon and grapes. Since there is a layer of wax on the surface of the crop, the water droplets are not easy to spread. After the leaf fertilizer is added, the water droplets spread rapidly on the leaf surface, so that the nutrients in the water are absorbed by the crop. Synthetic surfactants can enter the nearshore waters with sewage and are a type of marine pollutants. The pollution in the coastal areas of industrialized countries is particularly serious. The accumulation of such pollutants on the surface of the ocean not only affects the sea-air interface process, but also degrades the oxygen content of the coastal waters and endangers the marine ecosystem. Some of the naturally occurring organic substances in seawater are surface active, such as fatty acids, long-chain alcohols, proteinoids and certain water humic substances. In seawater, it tends to adsorb at the sea-air and seawater-particle interface, forming a surface film on the surface of the ocean. The physical and chemical properties of the film on the surface of the ocean, interfacial properties, material exchange at the sea-air interface, and marine aerosols. The formation of etc. has a direct impact. Surfactants are biodegraded in surface water, but concentrations above 4 mg/L can cause toxicity to aquatic organisms and fish, and can also cause eutrophication of water bodies. Sodium alkylbenzene sulfonate (ABS) is teratogenic to animals. When the concentration is 10 mg/L in water, fish is difficult to survive. At 45 mg/L, rice growth is seriously endangered.