Click the "defoamer net" above to pay attention to us
In the process of industrial production, a lot of harmful bubbles will be generated, and defoamer should be added. There are many kinds of defoamers, such as organosiloxane, polyether, grafting of silicon and ether, containing amines, imines and amides, which have the characteristics of faster defoaming speed, longer foam inhibition time, wider applicable medium range, and even harsh medium environment such as high temperature, strong acid and strong base. It is widely used to remove harmful foam produced in latex, textile sizing, food fermentation, biological medicine, coating, petrochemical, paper making, industrial cleaning and other industries.
1. Natural oil (i.e. soybean oil, corn oil, etc.)
Advantages: easy source, low price, easy to use;
Disadvantages: if the storage is not good, it is easy to deteriorate and increase the acid value.
2. High carbon alcohol
High carbon alcohol is a strong hydrophobic and weak hydrophilic linear molecule, which is an effective defoamer in water system. In the early 1970s, Soviet Union scholars experimented in the aqueous solution of anionic, cationic and non-ionic surfactants, and proposed that the defoaming effect of alcohol was related to its solubility and diffusion degree in the foaming solution. C7 ~ C9 alcohol is the most effective defoamer.
The high alcohols of C12~C22 are made up of suitable emulsifiers, which are made up of water emulsions with a particle size of 4~9 m and 20~50% content, that is, the defoamer of water system.
Some esters, such as phenylethanol oleate and lauryl phenylacetate, have antifoaming effects in penicillin fermentation, and the latter can also be used as a precursor.
3. Polyether defoamer
There are many kinds, including:
a. GP defoamer
It is prepared by addition polymerization of propylene oxide or mixture of ethylene oxide and propylene oxide with glycerol as initiator
GP defoamer has poor hydrophilicity and low solubility in foaming medium, so it should be used in thin fermentation broth. Its antifoaming ability is superior to that of defoaming, and it is suitable to be added in the basal medium to inhibit the foaming process of the whole fermentation process.
b. GPE defoamer, namely, foam enemy
At the end of the PP chain link of GP defoamer, ethylene oxide is added to form a hydrophilic polyoxyethylene propylene glycerin, also known as polyoxyethylene propylene glycerin. According to the addition amount of ethylene oxide, 10%, 20% 50% is called gpe10, gpe20 GPE50。
GPE defoamer has good hydrophilicity, easy spreading in foaming medium, strong defoaming ability, but also large solubility, and short defoaming activity maintenance time, so it has better effect in viscous fermentation liquid.
c. GPEs defoamer: there is a new kind of polyether defoamer. The end of GPE defoamer chain is capped with hydrophobic stearate to form block copolymers with hydrophobic chain at both ends and hydrophilic chain at intervals. The molecules with this structure tend to accumulate on the gas-liquid interface in a supine state, so the surface activity is strong and the defoaming efficiency is high.
4. Silicones
The most commonly used is polydimethylsiloxane, also known as dimethylsilicone oil. It has low surface energy, low surface tension, low solubility and high activity in water and general oil. Its main chain is a silicon oxygen bond, which is a nonpolar molecule. It is not compatible with polar solvent water and general oil. It has low volatility, chemical inertness, stability and low toxicity. Pure polydimethylsiloxane is difficult to be used as defoamer without dispersing. It may be due to its high interfacial tension with water and low spreading coefficient, which is not easy to disperse on the foaming medium. Therefore, the complex formed by mixing silicone oil with SiO2 aerosol, i.e. the hydrophobic SiO2 aerosol mixed with dimethylsilicone oil, can be prepared after a certain temperature and a certain time treatment.
Organosilicon defoamer is made of silicone grease, emulsifier, waterproof agent, thickener, etc. with appropriate amount of water by mechanical emulsification. It is characterized by low surface tension, high surface activity, strong defoaming power, low consumption and low cost. It is immiscible with water and most organic matters, and can defoaming most bubble media. It has good thermal stability and can be used in a wide temperature range of 5 ℃ - 150 ℃; it has good chemical stability and is difficult to react with other substances. It can be used in acid, alkali and salt solutions as long as the configuration is appropriate, without damaging the product quality; it also has physiological inert ld250g / kg mice, which are usually used in food and medicine industries. It has the functions of inhibiting and breaking bubbles for all bubble systems and belongs to the category of broad-spectrum defoamer. It is widely used for defoaming in detergent, papermaking, pulp, sugar making, electroplating, chemical fertilizer, additives, wastewater treatment and other production processes. In the petroleum industry, it is widely used in the desulfurization of natural gas, accelerating the separation of oil and gas; it is also used in the drying of glycol, extraction of aromatic hydrocarbon, processing of asphalt, dewaxing of lubricating oil and other devices to control or inhibit bubbles. In textile industry, it is used for defoaming in dyeing, refining, sizing and other processes; in chemical industry, it is used for defoaming in synthetic resin, latex, paint, ink and other processes; in food industry, it is used for defoaming in various concentration, fermentation, distillation processes. The silicone grease can be applied on the wall, the outlet or on the metal net for defoaming. It can be used for defoaming in oil system. Silicone grease and low viscosity silicone oil can be used as water emulsion, which can be used for defoaming in various aqueous systems. In medicine, it is usually used to remove the flatulence of organs or stomach organs before operation, X-ray and gastroscopy.
Defoamers can be roughly divided into two categories: one can eliminate the generated bubbles, such as ethanol; the other can inhibit the formation of bubbles, such as emulsified silicone oil. The defoamers approved for use in China are emulsified silicone oil, high carbon alcohol fatty acid ester complex, polyoxyethylene polyoxypropylene pentaerythritol ether, polyoxyethylene polyoxypropanol amine ether, polyoxypropylene glycerin ether and polyoxypropylene
5. Polyether modified silicon
Combined with the advantages of polyether and organosilicon defoamer, it is non-toxic and harmless, harmless to bacteria, with little addition, and is a high cost-effective product.
Defoamer net
WeChat official account: zgxpjw