Solvent extraction, which is also called a liquid-liquid extraction, is a separation process in which two immiscible solvents are combined so that a compound or solute in one of the solvents can be isolated. The technique is dependent upon the different solubilities of the two solvents mixed.
Two immiscible solvents will separate into two layers, such as when there is a mixture of oil and vinegar. The process entails using a container to combine solvent B with solvent A, which contains a compound or solute C that must be extracted from it. The container is agitated to mix the solvents together. When agitation stops, the two liquids separate into two different layers.
However, because of the difference in solubilities of the solvents, compound C is transferred from solvent A into solvent B. Similarly, the two solvents have different densities, such that the lower liquid layer is denser than the top liquid layer that forms.
An apparatus called a separatory funnel is used for solvent extraction. This process is used in different sectors, such as the petroleum, pharmaceutical and biochemical industries.