Solvent extraction

Solvent extraction, also known as liquid-liquid extraction or partitioning, is a method to separate compounds based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent. It is an extraction process where a solvent is used to separate a substance from a mixture. The process is often used in the chemical industry and in laboratories for the purification of a substance or for the isolation of a compound from a mixture.

Process

The process of solvent extraction involves four main steps: mixing, phase separation, solute partitioning, and solvent recovery.

In the mixing stage, the two phases (solvent and feed) are brought into contact. The solute or the component to be extracted transfers from the feed to the solvent phase.

During phase separation, the two phases are allowed to separate by gravity.

In solute partitioning, the solute partitions between the two phases according to the distribution law.

Finally, in the solvent recovery stage, the solute is recovered from the solvent phase.

Applications

Solvent extraction is used in numerous fields, including chemistry, biochemistry, and petroleum refining. In the chemical industry, it is used for the purification and concentration of organic compounds. In biochemistry, it is used to separate complex mixtures of proteins and to remove specific components from cell extracts. In petroleum refining, it is used to remove unwanted compounds from crude oil.

Advantages and Disadvantages

The main advantage of solvent extraction is that it provides a high degree of purification, making it a preferred method for the separation of valuable substances from mixtures. However, the process can be expensive and requires the use of large amounts of solvent, which can be harmful to the environment.

See Also

• Liquid-liquid extraction
• Chemistry
• Biochemistry
• Petroleum refining