Liquid-liquid extraction is a separation process where one or more components of a liquid mixture are preferentially dissolved into another immiscible liquid solvent based on factors like distribution coefficient, selectivity, density, and chemical reactivity. Solvent choice depends on these factors as well as properties like insolubility, recoverability, viscosity, vapor pressure, freezing point, availability, and cost. Extraction is often preferred over distillation when relative volatility is near unity, azeotropes would limit separation, heating must be avoided, or components are very different in nature.

1. COMSATS LAHORE
CHEMICAL ENGINEERING DEPARTMENT
PRESENTED BY:
UMER FAROOQ
BEC-FA11-093
Liquid Liquid Extraction

2. What is liquid liquid extraction?
 The separation of the components of a liquid
mixture by treatment with a solvent in which one
or more of the desired components is preferentially
soluble is known as liquid–liquid extraction.

3. Choice of solvent
 Distribution coefficient
 Selectivity (Separation Factor)
 Insolubility of Solvent
 Density
 Recoverability
 Viscosity, Vapour Pressure, Freezing Point
 Chemical Reactivity
 Availability and Cost

4. Single stage Batch Extraction

5. Extraction is preferred on Distillation
 Distillation would require excessive amounts of heat,
such as, e.g, when the relative volatility is near unity.
 When the formation of azeotropes limits the degree
of separation obtainable in distillation.
 When heating must be avoided.
 When the components to be separated are quite
different in nature.