Ion exchange is a reversible chemical reaction wherein an ion from solution is exchanged for a similarly charged ion attached to an immobile solid particle.
7. Definition Ion Exchange
•Ion exchange is a reversible
chemical reaction wherein an ion
from solution is exchanged for a
similarly charged ion attached to
an immobile solid particle.
ION ~ an atom or molecule that
has lost or gained an electron
and thus acquired an electrical
charge
8. Ion Exchange
Applicability
Ion exchange was a standard method of purification water and
usually removes the pollutant from the water.
Since the offending pollutant is often present in low concentration,
ion exchange is frequently more efficient in treating large flows of
dilute hazardous waste stream.
Operating cost depend mainly on the amount of the pollutant to be
removed.
9. Ion Exchange
Applicability•Ion exchange have a ability to separate, or purify as well
as to concentrate pollutants.
•Some exchanger are selective for certain metals and can
remove low concentrations of toxic metal from a waste
water containing a high background level of nontoxic-
metal such as sodium or calcium.
•Ion exchange can also be utilized in some application to
purify a spent chemical concentrate by removal of low-
level contamination.
10. Ion Exchange
Applicability• The greatest utility of ion exchange has been in the
treatment of inorganic waste.
• There are a number of possible applications of ion
exchange to treatment of organic waste ~ phenol
removal and decolorization of kraft pulp-mill
effluents.
11. Ion Exchange
Applicability
• The greatest utility of ion exchange has been in the treatment of
inorganic waste.
• There are a number of possible applications of ion exchange to
treatment of organic waste ~ phenol removal and decolorization of kraft
pulp-mill effluents.
12. Ion Exchange
Applicability
The ion exchange limitation and advantages,
1. Chemical wastes are produced if excess,
regenerant is required.
2. There are limitations on the concentration of what
can be treated and produced.
3. Down time is required for regeneration.
4. Resins cannot yet be made which are specific to a
particular substance.
5. Ion exchange resins are prone to fouling by some
organic substances and are subject to chemical
oxidation by oxidants (chlorine, hydrogen
peroxide)
13. Ion Exchange Reaction
•These solid ion exchange
particles are either naturally
occurring inorganic zeolites or
synthetically produced organic
resins.
•The synthetic organic resins
are the predominant type
used today because their
characteristics can be tailored
to specific applications.
14. Ion Exchange Reaction
•An organic ion exchange resin is
composed of high-molecular-
weight polyelectrolyte's that can
exchange their mobile ions for
ions of similar charge from the
surrounding medium. Each resin
has a distinct number of mobile
ion sites that set the maximum
quantity of exchanges per unit of
resin.
15. Ion Exchange Reaction
•Ion exchange reactions are stoichiometric and reversible,
and in that way they are similar to other solution phase
reactions.
For example:
NiSO4 +Ca(OH)2 = Ni(OH)2 + CaSO4
16. Ion Exchange Reaction
• This reaction, the nickel ions of the nickel sulfate (NiSO4) are exchanged for
the calcium ions of the calcium hydroxide [Ca(OH)2 molecule. Similarly, a
resin with hydrogen ions available for exchange will exchange those ions for
nickel ions from solution. The reaction can be written as follows:
2(R-SO3H)+ NiSO4 = (R-SO3)2Ni+ H2SO4 (2)
17. Ion Exchange Resin
•Ion exchangers are either cation
exchangers that exchange positively
charged ions (cations) or anion
exchangers that exchange
negatively charged ions (anions).
There are also amphoteric
exchangers that are able to
exchange both cations and anions
simultaneously.
18. Ion Exchange Resin
• However, the simultaneous exchange of cations
and anions can be more efficiently performed in
mixed beds that contain a mixture of anion and
cation exchange resins, or passing the treated
solution through several different ion exchange
materials.
19. Ion Exchange ResinResin types,
•Strong Acid Cation Resins. Strong acid resins are so
named because their chemical behavior is similar to
that of a strong acid.
•Weak Acid Cation Resins. In a weak acid resin. the
ionizable group is a carboxylic acid (COOH) as opposed
to the sulfonic acid group (SO3H) used in strong acid
resins.
•Strong Base Anion Resins. Like strong acid resins.
strong base resins are highly ionized and can be used
over the entire pH range.
•Weak Base Anion Resins. Weak base resins are like
weak acid resins. in that the degree of ionization is
strongly influenced by pH.
20. Ion Exchange
Application• Groundwater remediation, heavy metal recovery.
• Heavy metal removal from waste water
• Water recycling (Water purification, Water softening, Production of high
purity water).
• Decationization system for the pharmaceutical and chemical industries.
Decationization ~ removes cations, usually sodium in exchange for H+ on
resin
21. Ion Exchange
Application•Ion exchange is widely used in the food & beverage,
hydrometallurgical, metals finishing, chemical &
petrochemical, pharmaceutical, sugar & sweeteners,
ground & portable water, nuclear, softening &
industrial water, semiconductor, power, and a host of
other industries.
•Ion exchange is a method widely used in household
(laundry detergents and water filters) to produce soft
water. This is accomplished by exchanging calcium
Ca2+ and magnesium Mg2+ cations against Na+ or H+
cations (water softening)
22. Ion Exchange
Application• Ion exchange resins in the form of thin membranes are used in chloralkali
process, fuel cells and vanadium redox batteries. Ion exchange can also
be used to remove hardness from water by exchanging calcium and
magnesium ions for hydrogen and chlorine ions in an ion exchange
column.
• Ion exchangers are used in nuclear reprocessing and the treatment of
radioactive waste.
23. Ion Exchange
Application• Ion-exchange processes are used to separate and purify metals, including
separating uranium from plutonium and other actinides, including thorium,
and lanthanum, neodymium, ytterbium, samarium, lutetium, from each
other and the other lanthanides.
• The ion-exchange process is also used to separate other sets of very similar
chemical elements, such as zirconium and hafnium, which incidentally is
also very important for the nuclear industry.