Reactive Exns:
•When the extracting solvents are apolar, their ability to extract the polar compounds such as organic acids, amino acids, and phenols is low.
•About 30 years ago extraction with the help of a chemical reaction or strong physical interaction between the extracting solvent and the sample was used to solve the problem in LLE.
In this method usually a small amount of a reactant is added to the extracting solvent to:
1) Increase solvent polarity
2) Have specific interactions with analyte
3) Increase the extraction selectivity
Applications of Reactive Extractions in LLE Systems:
1) Separation and purification of heavy metal ions such as platinum, Ga (e.g. selective extraction of Ga from coal), etc using organic ligands or strong Lewis bases
2) Extraction of organic compounds from aqueous solutions have also been extensively studied:
a) Separation of amino acids using bis(2-ethylhexyl) phosphoric acids
b) Separation of Penicillin using Amberlite LA-2
Mechanisms of Reactive Extraction of Organic Acids
Using Amines :
Four major mechanisms for extraction of organic acids with amines has been proposed:
1- Ion exchange mechanism; in an aquous solution of an organic acid or its salt and extractant including an amine
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