Extraction is defined as a process where one or more solute(s) are removed from one liquid phase (technically called a diluent) by transferring that/those the solute(s) to another liquid phase (or a solvent).
A method of multiple liquid-liquid extractions is
counter current extraction, which permits the separation
of substances with different distribution coefficients
A clever design known as Craig apparatus is used for
this purpose (Lyman C. Craig, 1943).
• It consists of 300-400 such chambers.
• The organic solvent and the aqueous solution is
introduced to tube and then it passes to B.