Ion- Exchange Technique :-
The required components can separated generally by two types of technique.
1. Batch Method :-
This is a single step method in which the resin and the solution are takes into a single container and is mixed till equilibrium is attained. Then the solution is filtered. This method is usually used for softening of water. The hardness of water is removed by Exchange of calcium and magnesium ion present in water with sodium ion of resin.
2RSO3¯ + Na + Ca → (RSO3)2Ca +2Na
The exhausted resin is treated with 15 % Solution of Nacl to regain exchange capacity.
Deionized or demineralized water can also be prepared by this method as follows :-
1. Cation of electrolyte are replaced by hydrogen ion.
RSO3 + H + M ⇔RSO3M + H
2. water is then treated with anion exchange
ROH + Cl → RCl + OH
Finally H + OH → H2O
Demineralized water is prepared as above which is widely used in conductance experiment and also in biological studies.
2. Column method :-
In this method, the resin is made into a slurry by using distilled water and is placed in column as in column Chromatography. The resin in dry form should not be used to pack the column. Care should be taken to prevent the Entrapment of air bubbles. The fine particle are removed from the column by back washing in which water is runned into the column both from top and bottom also this back washing is also useful in removal of air bubbles the particle size of resin used should be small to provide larger surface area for efficient Exchange the level of water should be maintained above the level of resins to prevent drying of resin.
The components are separated in the column according to their selectivity from the resin by technique like frontal analysis, Elution analysis and displacement development etc.
Regeneration of the Ion exchange Resin :-
After separation of components by using ion exchange Resin the resin is not useful for another separation as it losses its exchangeable functional group. Regeneration of anion exchange Resin is usually done by using strong alkali like sodium hydroxide and potassium hydroxide and cation exchange Resin by strong acid like hydrochloric acid
Application of Ion exchange Chromatography :-
- It is used for softening of water.
- It is used for demineralization of water.
- It is used for separation of similar ion in one sample.
- It can be used for separation of metal from complex mixture.
- It can be used for separation of organic and inorganic compound.
- It can be used for separation of amino acids .
1. Which sentence is true about batch method ?
A. It is multiple step process.
B. It is not used for preparation of the demineralized water.
C. In this process more than two containers.
D. This is single step process.
2. Which method are used for preparing of demineralized water?
A. Gas Chromatography
B. Batch method ( ion exchange)
C. Mass sepctroscopy
D. Complexometric Titration
3. Which is not application of ion Exchange ?
A.It is used for softening of water.
B.It is used for demineralization of water.
C.It is used for separation of similar ion in one sample.
D. It is used in preformulation.
4. Which is application of demineralized water ?
A. Biological studies
B. conductance experiment
C. A and B
D. None of the above
5. Which is not ion exchange technique ?
A. Batch method
B. Column method
C. Paper Chromatography
D. A and B
TEXT BOOK OF PHARMACEUTICAL ANALYSIS THIRD EDITION OF DR. RAVI SANKAR (16. 1TO16.10)