As a new type of surfactant produced by microorganisms, biosurfactants have many advantages over chemical surfactants, such as low toxicity, degradability, ecological compatibility, high efficiency and stability. Therefore, biosurfactants are widely used not only in the fields of oil exploitation and transportation, pharmaceutical industry, food industry, textile industry and cosmetics industry, Moreover, more and more attention has been paid to its application in the field of environmental engineering, especially in soil remediation.

In the production of wet process phosphoric acid, adding surfactant can improve the habit of crystallization process and obtain coarse and easily filtered calcium sulfate crystal. For example, adding alkylbenzene sulfonic acid (ABS), isopropyl naphthalene sulfonate or decyl benzene sulfonate into the reaction system can inhibit the formation of dihydrate crystal nucleus, make the crystal grow coarser, and promote the dielectric stability of hemihydrate crystal at lower temperature, so as to improve the filtration rate of phosphogypsum crystal and reduce the loss of P2O5.

Fluorine surfactant refers to the surfactant whose hydrogen on the hydrophobic group of hydrocarbon chain is completely replaced by fluorine atom. It is often used as emulsification, dispersion, defoaming, penetration, antistatic, acid and alkali resistance and lubricant. According to the structure of hydrophilic groups, fluorine surfactants can also be divided into cationic, anionic, amphoteric and non-ionic surfactants. Because the structure of its hydrophilic group is the same as that of hydrocarbon surfactant, the characteristics of fluorine surfactant are determined by carbon fluorine chain.

Ionic surfactants ionize in water. If they form positively charged hydrophobic groups, they are called cationic surfactants; If a negatively charged hydrophobic group is formed, it is called anionic surfactant. If there are anion and cation groups in a molecule at the same time, that is, after dissolving in water, it generates two kinds of charges: positive charge and negative charge, it is called amphoteric surfactant. Nonionic surfactants do not ionize in water and are electrically neutral.

Surfactant can reduce the interfacial tension and reduce the wetting angle θ Close to zero, the solid powder can be spontaneously dispersed in the surfactant solution. At the same time, the surfactant can help the liquid to wet the inner surface of the solid, make the liquid penetrate into the channels and voids between the aggregates inside the particles, provide a certain pressure, and destroy the strengthening bond force of the particle aggregates under the action of machinery.

Some achievements have been made in the research of plant-derived pesticides at home and abroad, but few dosage forms have been formed. The reason is that there are still many deficiencies in the research process of plant-derived pesticides, such as the complexity of active components and the instability of content. The stability of natural products and the active components extracted and separated from plants are no different from traditional chemical pesticides in structure, but the essence of it and traditional chemical synthetic pesticides lies in its poor stability. The complex composition of active components extracted and separated from plants exceeds people's expectations, which not only makes it difficult to extract and separate, but also makes it difficult to determine whether the relationship between components is synergy, synergy or antagonism, It is difficult to study the mechanism of insecticidal and disease resistance. It often appears that the insecticidal effect is good, but the root cause is unclear.

Surfactant is an indispensable and important material in pesticide processing and application. For the selection of surfactants, we should not only consider their compatibility with pesticides, but also consider the factors such as efficiency, stability, appropriate price and safety, so that they can better play the role of pesticides when sprayed with pesticides. At the same time, they also have a certain activity. Therefore, the choice of surfactants also has a lot of knowledge.

When the emulsion is used, water is added to form a white emulsion, and the pesticide particles are generally several to dozens μ m。 Its efficacy is better than that of solid preparations, but it is also prone to drug damage. At present, emulsion is the most widely used dosage form in liquid preparations. In order to reduce environmental pollution and improve safety, people have recently developed to the dosage form of organic solvent-free, microemulsion and suspension.

For example, 10% AEG, which is easy to penetrate into alkaline ether, is suitable for cleaning with 10% APG, which is easy to penetrate into alkaline ether. In the textile printing and dyeing industry, if the silk fiber is refined to remove too much fibroin, it will damage the strength, luster and softness of the silk fiber. If APG is added, it can prevent over refining.

The molecular structure of surfactants is characterized by two parts with completely different properties. One part is the lipophilic group with affinity with oil, and the other part is the hydrophilic group with affinity with water. The hydrophilicity and lipophilicity of different kinds of surfactants are different. An important performance index of surfactants is hydrophilic lipophilic equilibrium value (HLB value). The surfactant with higher HLB value has higher hydrophilicity, while the surfactant with lower HLB value has higher lipophilicity.

Surfactants can also be used in the cleaning of plastic surfaces. Liu Yali] studied cleaning agents for plastic surfaces. The cleaning agent is composed of Las (sodium dodecylbenzene sulfonate), TX (octylphenol polyoxyethylene ether) and Ta (polyether non-ionic surfactant). It has good cleaning effect on ABS, PVC, PP and phenolic plastics.

Surfactants are also widely used in the production of finishing materials. When preparing pigment paste and polishing paste, sulfated oil should be added as dispersant and wetting agent; When preparing acrylic resin emulsion and nitrocellulose emulsion, adding a certain amount of surfactant can make emulsion stable, fine particles, uniform film formation and good gloss.

Surfactants have different classification methods. One is to classify by ion type. Surfactants dissolved in water can be divided into ionic surfactants and non-ionic surfactants according to dissociation and non dissociation. Ionic surfactants can be divided into anionic, cationic and amphoteric types according to the nature of charge. Secondly, according to the classification of solubility, it is divided into water-soluble surfactant and oil-soluble surfactant. The third is classified into low molecular surfactant and high molecular surfactant according to molecular weight. Fourth, according to the classification of uses, it is divided into wetting agent, emulsifier, antistatic agent, softener, leveling agent, etc.

Surfactants can also be used to clean plastic surfaces. Liu Yali] studied cleaning agents for plastic surfaces. The cleaning agent is composed of Las (sodium dodecylbenzene sulfonate), TX (octylphenol polyoxyethylene ether) and Ta (polyether non-ionic surfactant). It has good cleaning effect on ABS, PVC, PP and phenolic plastics.

There are cationic, anionic and non-ionic surfactants used as antistatic agents. Cationic antistatic agents include antistatic agent Sn, antistatic agent SP, etc., anionic antistatic agents include antistatic agent P, etc., and non-ionic antistatic agents include antistatic agent ECH, etc.

In the textile industry, many dyeing and finishing auxiliaries often use the complex of surfactants. However, the combination of surfactants produces synergistic effects and synergistic effects, and there are functions that a single surfactant does not have. Therefore, the compounding technology and synergistic effect of surfactants, as well as the relationship between the surface characteristics and application properties after compounding, have become an important research direction in the field of printing and dyeing auxiliaries, and also an extremely important research content to improve the quality of printing and dyeing.

The main purpose of the application of surfactant in leather soaking is to help soften the raw leather and restore the fresh skin state. Therefore, surfactants with good wetting and permeability should be selected, among which the effect of non-ionic surfactants is better. Most commonly used are carboxylate type anionic surfactants and polyoxyethylene type non-ionic surfactants, such as ramibang, Pingjia, etc.

Surfactants are also widely used in the production of finishing materials. When preparing pigment paste and polishing paste, sulfated oil should be added as dispersant and wetting agent; When preparing acrylic resin emulsion and nitrocellulose emulsion, adding a certain amount of surfactant can make emulsion stable, fine particles, uniform film formation and good gloss.

When the surfactant solution contains homologues or adds another surfactant or organic or inorganic electrolyte, the physicochemical or surface properties of the solution will change significantly and its application performance will be changed.

Surfactant is an important chemical material, which is called "industrial monosodium glutamate". Its application in leather industry has penetrated into all processes, which affects the quality and performance of finished leather to a great extent. In leather production, its functions of wetting, emulsification, dispersion, penetration and leveling are mainly used to promote or improve the physical and chemical effects of each leather making process, so as to shorten the production time, save chemical materials, improve the production efficiency and improve the quality of leather.