Demulsification technology after emulsification
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This post was last edited by Xiao Lang Wangyue on 2010-12-10 09:40. Emulsification is the process in which a liquid is uniformly dispersed as extremely small droplets within another liquid that is immiscible with it. Emulsification is a liquid-liquid interface phenomenon in which two immiscible liquids, such as oil and water, separate into two layers in a container, with the less dense oil on top and the denser water at the bottom. If an appropriate surfactant is added and the oil is dispersed in water under vigorous stirring to form an emulsion, this process is called emulsification. Emulsification often occurs during the separation of production materials, which necessitates demulsification. Common methods for demulsification are as follows: Common Demulsification Methods (1) Long-term standing: Leaving the emulsion to stand overnight usually results in its separation into two clear layers. (II) Horizontal rotation of the separatory funnel: When the interface between two liquid layers becomes unclear due to emulsification, the separatory funnel can be slowly rotated horizontally, which helps to eliminate the \"foam\" at the interface. Promote stratification. (III) Filtration with filter paper For emulsification caused by the presence of resinous or mucilaginous suspended particles, the material in the separatory funnel can be filtered under reduced pressure using filter paper with a dense texture. The material after filtration tends to stratify and separate easily. (IV) Add diethyl ether: A solvent with a specific gravity close to 1 tends to emulsify with the aqueous phase during extraction or washing processes. In such cases, a small amount of diethyl ether can be added to dilute the organic phase, thereby reducing its specific gravity and facilitating separation into layers. (5) Add water or solvent, then shake horizontally. Slowly add water or solvent to the emulsified mixture and then shake it horizontally; this facilitates the separation into two phases. As for whether it is more effective to add water or a solvent, a small amount of the emulsified mixture can be taken out and tested in a test tube first. (VI) Addition of ethanol: For emulsions formed with ether or chloroform, 5–10 drops of ethanol can be added, followed by gentle shaking, which will help the emulsion separate into layers. However, it should be noted at this point that the inclusion of ethanol in the extractant can sometimes have adverse effects due to the decrease in the distribution coefficient. (7) Centrifugal separation: The emulsified mixture is transferred into a centrifuge for high-speed centrifugal separation. (8) Addition of inorganic salts and reduced pressure For emulsions of ethyl acetate and water, the addition of inorganic salts such as table salt, sulfuric acid, or calcium chloride, which are dissolved in water, can promote stratification. Furthermore, removing the emulsified portion and carefully warming it to 50°C, or using a water pump to reduce pressure and remove gas, can both aid in separation. For the emulsion formed from diethyl ether, the emulsified portion can be separated and placed in an elongated cylindrical container; then, fully dehydrated sodium sulfate powder is evenly sprinkled on the surface of the liquid. As sodium sulfate absorbs water, it sinks, and a layer of aqueous solution is formed at the bottom of the container. However, based on my own practical experience, there is still no effective demulsification technique available at present. When emulsification occurs during the production process, it poses a serious problem. Let’s discuss together to see if anyone has a better method for demulsification.
What the original poster described were mainly demulsification methods used in laboratories. In industry, it is still somewhat difficult to demulsify without equipment such as ultrasonic waves, electric fields, and liquid-liquid centrifugal separation. Our products often experience emulsification during the production process, especially in systems with a high pH value, an organic phase density close to 1, and high viscosity. The demulsification methods are as follows: (1) Add more water to dilute the concentration of the surfactant substances, reduce viscosity, and enable the system to form more oil-in-water systems; in this way, the sedimentation of oil in the aqueous phase is less affected by the viscosity of the oil itself. (2) Lower the pH value of the system. Many systems become emulsified under strongly alkaline conditions due to the saponification of substances such as organic carboxylic acids, and the emulsion can break down upon acidification. (3) Add inorganic salts, but the effect seems to be limited.
I’ve tried the method of adding salt upstairs, but it wasn’t very effective; I also tried using alcoholic organic compounds, with little noticeable effect as well. In production, ultrasound and heating are relatively viable methods. Preventing emulsification is the key to the problem, as there is still no practical method available for demulsification.
Emulsification is the process of forming oil-in-water or water-in-oil systems; the key lies in identifying what type of amphoteric substance constitutes the oil/water interface formed by emulsification. Once this is determined, it becomes easier to address the issue. For example, if emulsification occurs as a result of proteins, heating can be an effective solution. Additionally, when organic solvents are used for extraction in antibiotic production, emulsification often occurs, but modern high-speed centrifuge equipment can solve this problem.
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