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Describe all terms related to solvent extraction?


What do you know about solvent extraction?




Solvent extraction is a procedure of separation of liquid (by a special designed funnel known as separating funnel ) according to the nature of their polarity .In this technique polar solvent remains on the top and non polar solvent remains on the bottom and comes or separated at a faster speed.


First we will discuss history of solvent extraction

In Ancient times solvent extraction was applied for the separation of rare earth metals for complete or best separation like with ketones, alcohols and ethers. By using this single stage separation different rare earth metals were also separated by showing the phenomena of equilibrium.
Principle of solvent extraction:

Addition of any solute (either in liquid form or in solid state ) to a heterogeneous system with two immiscible liquids,then the solute distributes itself among two liquids.
Law on which above process is based:
Distribution in solvent extraction is lies on the basis of Nernst law of distribution.

Nernst law of distribution:
Nernest distribution law state that
“At the stage of the equilibrium between two liquids concentration ratio of the third component always remains same”.

Importance of Solvent extraction:

Extraction of metals :
Solvent extraction is mainly helpful in the extraction of rare earth metals such as Neodymium ,Yttrium, Lanthanum and Scandium.
Use as in-expensive method:
Solvent extraction is also an in-expensive method.
Separation by the use of  smaller amount of solvent :
In solvent extraction separation is done by using smaller amount of sample rather than using a large quantity of sample in one separation.

Types of Solvent extraction:

Solvent extraction can be classified in to following main types :
Anionic extraction
Cationic extraction
Chelating extraction
Solvating extraction
Important terms of Solvent extraction:
Solvent extraction is although a dramatic technique and works on following principle which mainly consists of following two phases:
1)Polar phase (First phase)
This phase always move after the second phase and often a polar solvent .
2)Non-polar phase (Aqueos phase)
Non polar phase is always present in liquid form or may be a water which comes first from the separating funnel.

 Characteristics of a good solvent extraction:
Solute distributes itself among two phases by depending on their partition coefficients.
It should have less solubility of impurities.
Target or selected solvent should be soluble at a greater range.
It should have fewer amounts of toxic substances.

Factors affecting the solvent extraction:

There are following factors from which solvent extraction can be affected :
Masking agents
pH value
Salting out agents
Modifiers
Synergistic agents
Oxidation state


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