Surfactants have caused serious harm to the human body and the environmental ecosystem in the process of production and use. Adding a certain amount of surfactant solvent to the detergent can enhance the solubility and detergency of the detergent, but due to the toxicity of these solvents, it will have a significant irritating effect on the skin. Extensive use of surfactants is also potentially harmful to ecosystems. For example, the biodegradability of sodium alkyl benzene sulfonate (ABS) is poor, and the large amount of foam generated by its extensive use in detergents has caused the flooding of urban sewers and rivers. Water quality produces "eutrophication"; dioxane in sulfur dioxide, sulfur trioxide and fatty alcohol polyoxyethylene ether sulfate (AES) products produced in the process of producing linear alkyl benzene sulfonate (LAS) These substances are not easy to biodegrade and cause great harm to the environment.
In order to meet people's increasing health care needs and ensure the sustainable development of human living environment, it is imperative to develop surfactants that are as non-toxic and harmless to the human body as possible and non-polluting to the ecological environment.
01 Classification and performance of green surfactants
Green surfactants refer to surfactants that are processed from natural or renewable resources, are less irritating to the human body and are easily biodegradable. Green surfactants can be divided into non-ionic green surfactants and ionic green surfactants according to whether they dissociate in water. Ionic green surfactants can be divided into cationic, anionic and zwitterionic according to the dissolved active ingredients.
Green surfactants are processed from natural or renewable resources, that is, they have excellent characteristics such as naturalness, mildness, and low irritation. Like traditional surfactants, green surfactants have hydrophilic and hydrophobic groups. Compared with traditional surfactants, green surfactants have high-efficiency and strong detergency, excellent compatibility and good environmental compatibility, and show good emulsifying, washing, solubilizing, wetting, and dissolving properties. stability and stability.
In addition, each green surfactant has its own unique properties, such as α-sulfofatty acid ester salt (MEC) has surface activity at low concentration, resistance to hard water, monoalkyl phosphate ester has excellent Foaming emulsification, antistatic properties and unique skin affinity. Common green surfactants are α-sulfofatty acid methyl ester (MEC), alkyl polyglycoside (APG), glucose amide (APA), alcohol ether carboxylate (AEC), monoalkyl phosphate (MAP) , Alkyl Glucamide (MECA).
02Performance, application and status quo of several types of green surfactants
Green surfactants have excellent characteristics such as naturalness, mildness and little irritation. Like traditional surfactants, green surfactants have hydrophilic and hydrophobic groups. Compared with traditional surfactants, green surfactants have high efficiency and strong detergency, excellent compatibility and good environmental compatibility, and show good emulsifying, washing, solubilizing, wetting, and dissolving properties. stability and stability.
●Alkyl polyglucosides (APGs)
Alkyl glycoside (APG) is a new generation of environmentally friendly green surfactants. It is a new type of non-ionic surface active agent. Active agent has the characteristics of excellent foaming performance, less irritation to the human body, easy to be biodegraded, low surface tension, good detergency, rich and delicate foam, strong compatibility, and obvious synergistic effect with any type of surfactant, It has strong broad-spectrum antibacterial activity, the product is easy to dilute, has no cloud point, no glue phenomenon, is easy to use, and has strong alkali resistance and salt resistance.
The raw materials used in the production of alkyl glycosides are oral glucose and fatty alcohols. This product will be a substitute for traditional surfactants because of its non-toxic and non-irritating properties, and has broad application prospects. Widely used in pesticide intermediates, detergents, cosmetics, food, medicine, fire protection, textiles, printing and dyeing, petroleum and other industrial fields.
●Aliphatic alcohol polyoxyethylene ether sulfate (AES)
Fatty alcohol polyoxyethylene ether sulfate (AES) is obtained by the addition reaction of higher aliphatic alcohol and ethylene oxide to obtain fatty alcohol polyoxyethylene ether and then sulfated. AES is an important class of anionic surfactants. It has excellent anti-hard water foaming properties and low temperature performance, rapid biodegradation, little skin irritation, good compatibility with enzymes, and the solution is transparent and stable and easy to be dissolved by electrolytes. It is widely used in liquid detergents, low-phosphorus and non-phosphorus detergents and personal protection products by adjusting and increasing the viscosity. It is also the mainstream product of anionic green surfactants in my country. Such new products include isomeric fatty alcohol sulfates (GAS) and phosphates (GAP) and isomeric fatty alcohol polyoxyethylene ether sulfates and phosphates (GAES and GAEP).
●Fatty acid methyl ester sulfonate (MES)
MES is a new generation of green surfactants. The history of research and development of MES has been as long as half a century. For decades, almost all famous detergent companies have spent a lot of effort on MES, and highly affirmed and appreciated it. The superior performance of MES is based on natural raw materials, renewable resources, good biodegradability, and is an environmentally friendly green product. MES has mild performance, and its irritation and toxicity to human body are lower than that of linear alkyl benzene sulfonate LAS, which is equivalent to AS and AES. No oral toxicity, virtually non-toxic to aquatic organisms. It has good washing performance and can maintain good washing performance in cold water and hard water. The detergency is higher than that of LAS and AS, and the difference is more obvious in hard water, which is the main weakness of LAS. Phosphorus-free properties are better than LAS. In the absence of alkali and lack of sodium tripolyphosphate, the decontamination ability of LAS is greatly reduced, but MES has little effect, so it is especially suitable for the production of phosphorus-free/low-phosphorus environment-friendly detergents. Although MEs has the above advantages, its actual annual output has been hovering around 20,000 tons for a long time. Commercial promotion is mainly limited by the problems of production and formulation, that is, the color is dark, and it is easily hydrolyzed into by-products with poor washing performance during the bleaching process. Sodium salts have poor thermal stability under alkaline water conditions and are difficult to formulate.
●Biodegradable Gemini Surfactant
Gemini surfactants have a special separation (separation) substructure. The monomeric surfactant separation (ion) usually consists of one hydrophobic chain and one hydrophilic group, while the Gemini surfactant separation (ion) usually consists of two (or three) hydrophobic chains, two hydrophilic groups and one The linking group is composed (the linking group is close to the hydrophilic group site), and the linking group can be either hydrophilic or hydrophobic. Compared with monomeric surfactants, Gemini surfactants have many excellent properties: high surface activity; very low Krafft point and good water solubility; show higher efficiency in reducing the surface tension of water, Combination with monomer surfactants can produce stronger synergistic effect; good calcium soap dispersibility; stronger ability to reduce oil/water interfacial tension; stronger ability to solubilize oil; skin irritation less sex, etc. Gemini surfactant is the leader among new products, only because Gemini products have high cost and few industrialized products, so far there are only two industrialized products.
●Polyepoxysuccinic acid (PESA), polyaspartic acid (PASP)
Polyepoxysuccinic acid (PESA) is a green biodegradable corrosion and scale inhibitor without phosphorus and nitrogen first developed by Betz laboratory in the early 1990s. PESA not only has good scale inhibition performance, but also has no phosphorus, no nitrogen, and is easily biodegradable. It is suitable for high alkali and high solid water systems, and can be used in boiler water treatment, cooling water treatment, sewage treatment, seawater desalination, membrane separation, etc.
Its scale inhibition performance and corrosion inhibition performance are obviously better than those of sodium polyacrylate, polymaleic acid and tartaric acid. Due to the clean manufacturing process, the used PESA can be efficiently and stably degraded by microorganisms or fungi into environmentally harmless final products. Therefore, it is considered to be an "environmentally friendly" green chemical. It has become a hot spot in the research and development of water treatment agents at home and abroad. In recent years, foreign countries have developed rapidly in this area.
Polyaspartic acid is obtained by polymerization of aspartic acid or maleic acid under the action of a catalyst. Widely used in cooling water, boiler water treatment and water treatment in desalination, desugaring recovery, reverse osmosis and other processes, especially in oil well drilling equipment generated from petroleum, it is an inhibitor of calcium carbonate, barium sulfate and calcium sulfate precipitation . The synthesis, structure and properties of polyaspartic acid have been studied abroad, and industrial application has begun. Extensive research has also been carried out in China. Polyaspartic acid water treatment agent is considered to be a real green scale inhibitor because of its excellent biodegradability and high scale inhibition performance.