principles of ion exchange process

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3. Principles of Ion-Exchange
process
Ion exchange is an exchange of ions between two electrolytes or
between an electrolyte solution and a complex
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4. Ion Exchange
Ion exchange is an adsorption phenomenon where the mechanism of adsorption is
electrostatic. Electrostatic forces hold ions to charged functional groups on the surface of
the ion exchange resin. The adsorbed ions replace ions that are on the resin surface on a
1:1 charge basis. For example:
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5. Applications of ion exchange in water & wastewater
• Ca, Mg (hardness removal) exchange with Na or H.
• Fe, Mn removal from groundwater.
• Recovery of valuable waste products Ag, Au, U
• Demineralization (exchange all cations for H all anions for OH)
• Removal of NO3, NH4, PO4 (nutrient removal).
In Addition - purification, separation, and decontamination of aqueous
and other ion-containing solutions
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7. Ion Exchangers (types)
Natural
• Proteins,
• Soils,
• Lignin,
• Coal,
• Metal oxides,
• Aluminosilicates (zeolites)
(NaOAl2O3
.4SiO2).
Synthetic
• zeolite gels and
• Most common -polymeric resins
(macroreticular, large pores).
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8. Ion Exchange Resin
 Higher molecular weight & cross linked polymer
 Contain exchangeable Cation & Anion
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9. Polymeric resins are made in 3-D networks by cross-linking hydrocarbon chains. The
resulting resin is insoluble, inert and relatively rigid. Ionic functional groups are
attached to this framework.
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10. These resins are generally manufactured by polymerizing neutral organic molecules
such as sytrene (to form polystrene) and then cross-linked with divinyl benzene
(DVB). Functional groups are then added according to the intended use. For example
the resin can be sulfonated by adding sulfuric acid to get the structure shown above.
Divinylbenzene:
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sjhgfhdghhvghvjhgfh
v

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13. Cation exchange Resin,
 contains -COO-, - SO (negative group by covalent bond)
 Neutralized by equivalent amount of free Cation (By Ionic bond)
Salt of solution contact with Resin & Cation exchange between solution and resin
(Res-SO3
-)M+ + M’+
(aq) ↔ (Res-SO3
-) M’+ + M+X-
(aq)
Anion exchange Resin,
 Contains -R3N+ in it’s molecular structure (positive group by covalent bond)
 Neutralized by equivalent amount of free anion (By Ionic bond)
 Salt of solution contact with Resin then anion exchange between solution
and resin
(Res-NR3
+)X- + M+ Y-
(aq) ↔ (Res-NR3
+)Y- + M+X-
(aq)
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14. Principle Actions of Cation exchanger
Cation exchanger are generally denotes (Res-A-)B+
Where, Res is hydrocarbon structure
A- is anion part
B+ is exchangeable cation
(Res.A-)B+ + C+ (solution) ↔ (Res.A-)C+ + B+ (solution)
(Res-SO3
-)Na+ + Ca+ +
(solution) ↔ (Res-SO3
-) Ca + + + Na+
(solution)
Sodium sulfonated
styrene resin
• Always reversible reaction
Na are separated in
solution
Ca are barge
into the rtesin
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15. Similarly
Resin of hydrogen condition in neutral salt solution
(Res.SO3
-)H+ + Na+ Cl-
(solution) ↔ (Res.SO3
-) Na+ + H2O (solution)
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16. Principle Actions of Anion exchanger
Anion exchanger are generally denotes (Res-B+)A-
Where, Res is hydrocarbon structure
A- is anion part
B+ is exchangeable cation
(Res. B+) A-+ D- (solution) ↔ (Res. B+) D- + A- (solution)
2(Res.NMe3
+)Cl- + SO4- -
(solution) ↔ (Res. NMe3
+)2 SO4- - + 2 Cl-
(solution)
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Quartarnary
amonium resin Anion wants to
barge into resin

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