Principle of steam distillation

The principle of steam distillation is to make use of the difference of vapor pressure of each component in the mixture to make the vapor pressure of each component reach equilibrium by heating, so as to separate each component.

Steam distillation is a commonly used separation and purification method, which is suitable for separating substances that cannot or are difficult to distill under normal pressure.

Steam distillation is to put the substance to be separated into a distillation bottle, add a proper amount of water, and then heat it. With the increase of temperature, the low-boiling substances in the mixture gradually become steam and escape from the distillation bottle with the steam. Condense steam into liquid through condenser, and collect and separate low-boiling substances. However, high-boiling substances can't be changed into steam with water vapor because of the low steam pressure, so they stay in the distillation bottle.

The advantage of steam distillation is that it can separate substances that can't be distilled or are difficult to distill under normal pressure, especially for substances with high boiling point and poor thermal stability. In addition, this method can also be used to separate a small amount of desired substances from a large number of impurities. However, steam distillation also has some disadvantages, for example, it needs a lot of steam and is not suitable for separating substances that are easily destroyed by water.

Application scenarios of steam distillation;

1. Chemical production: In chemical production, steam distillation is usually used to separate and purify organic compounds. These compounds may have the properties of low boiling point, instability or reaction with water, which makes it impossible to effectively separate them by conventional distillation methods. By steam distillation, these substances can be separated from the mixture, and the purity and yield of the product can be improved.

2. Medical research: In medical research, steam distillation can be used to extract and separate active ingredients from natural medicines. The effective components in many natural medicines have the characteristics of low boiling point, instability and easy oxidation, and it is difficult to separate them by conventional methods. Through steam distillation, these active components can be extracted and separated efficiently, which provides key technical support for drug research and development.

3. Food processing: In the field of food processing, steam distillation is often used to extract and separate edible spices. For example, when making coffee, tea, spices and other products, the aroma components can be extracted from the raw materials by steam distillation to improve the aroma and taste of the products. In addition, steam distillation can also be used for food disinfection and deodorization to improve the quality and hygiene level of food.

4. Environmental analysis: In the field of environmental analysis, steam distillation can be used to separate and enrich volatile organic compounds in the atmosphere and water. These organic compounds may have negative effects on the environment and human health. They can be extracted from samples by steam distillation for qualitative and quantitative analysis, which provides support for environmental monitoring and pollution control.