This presentation is all about the Electro Dialysis mechanism.

1. Electrodialysis(ED)
Group members:
• CH19BTECH11008 (Veekshith)
• CH19BTECH11015(Afnan)
• CH19BTECH11026(Ashish)

2. Topics
• Introduction
• Design
• Working Principles
• Applications
• Summary
• Modern Day Research
• References

3. Introduction
• Electrodialysis is used to transport salt ions
from one solution through ion-exchange
membranes to another solution under the
influence of an applied electric potential
difference.
• This is done in a configuration called an
electrodialysis cell.
• Multiple electrodialysis cells are arranged
into a configuration called an
electrodialysis stack, with alternating
anion and cation exchange membranes
forming the multiple electrodialysis cells.

4. Design
1. Membranes
Membrane is defined as a selective barrier between two
phases and it can be formed from natural and synthetic
material including organic and inorganic polymer,
ceramic and metal material.
There are two types ion exchange membranes used in ED
are
(i) Anion transfer membranes:
This membrane allows the passage of anions while
blocking the passage of water and cations.
(ii) Cation transfer membranes:
This membrane allows the passage of cations while
blocking the passage of water and anions.

5. Design...
2. Spacers:
• Spacers are die-cut polypropylene flow
channels with manifold cutouts similar to
those for membranes.
• Spacers are alternately positioned between
membranes in the stack to create
independent flow paths.

6. Working Principles
• Consider feed solution containing sodium
chloride passes through ED system and focus
on one compartment.
• Under the influence of an electrical potential
difference, the anions migrate toward the
positively charged anode by passing through
the positively charged anion exchange
membrane, but are prevented from
further migration toward the anode by the
negatively charged cation exchange
membrane and therefore stay in the stream,
which becomes concentrated with the anions
and vice versa with the positively
charged species.

7. • As a result of the anion and cation
migration, electric current flows between the
cathode and anode.
• Only an equal number of anion and
cation charge equivalents are transferred so
the charge balance is maintained.
• Cathode and Anode Reactions:
At Cathode: 2e- + 2 H2O → H2 (g) + 2OH-
At Anode: H2O → 2H+ + ½ O2 (g) + 2e- (or) 2Cl- →
Cl2(g) +2e-
Working Principles...

8. Since the applied electric potential acts as a driving
force for the ED process. The electric current
requirement depends upon the number of ions
transported through the ion exchange membrane.
Electric current required=Z × F × Q × ΔC/𝜺
where,
Z=Charge on ion;
F=Faraday’s constant;
Q=Feed solution flow rate;
ΔC=Change in solute concentration;
𝜺=Current utilization factor that accounts for energy
efficiency.
Working Principles...

9. Efficiency
• Current efficiency is a measure of how effective ions are transported across the ion exchange
membranes for a given applied current.(Nearly 80%)
• £=(zFQf(Cd
inlet - Cd
outlet))/NI
• £= current utilization efficiency
• z= charge of the ion
• F= Faraday constant, 96,485 Amp-s/mol
• Qf=dilute flow rate, L/s
• Cd
inlet = dilute ED cell inlet concentration, mol/L
• Cd
outlet= dilute ED cell outlet concentration, mol/L
• N= number of cell pairs
• I= current, Amps.

10. Applications
Industrial applications:
Brackish water desalination:Sheet flow, tortuous path stack, reverse
polarity
Boiler feedwater production: Sheet flow, tortuous path stack, reverse
polarity
Waste and process water treatment:Sheet flow stack, unidirectional
Demineralization of food products:Sheet flow or tortuous path stack,
unidirectional
Table salt production:Sheet flow stack, unidirectional
Concentration of reverse osmosis brine:Sheet flow stack, unidirectional

11. Applications...
• Another important application for electrodialysis
is the production of pure water and ultrapure
water by electrodeionization (EDI).
• In EDI, the purifying compartments and
sometimes the concentrating compartments of
the electrodialysis stack are filled with ion
exchange resin.
• When fed with low TDS feed the product can
reach very high purity levels.
• The main usage of EDI systems are in
electronics, pharmaceutical, power generation,
and cooling tower applications.

12. Modern Research & Development
• Electrodialysis (ED) is a new advanced separation process that is commonly utilized
for producing drinking water from water bodies as well as for the treatment of
industrial effluents.
• ED process is applied on commercial scale.
• Hybrid technologies: The future of energy efficient desalination
• Waste-Water Treatment
• Food processing
• Water reuse (desalination brine treatment, industrial laundry wastewater,
produced water from oil/gas production)
• Agricultural water (water for greenhouses, hydroponics, irrigation, livestock)
• Glycol desalting, Glycerin purification

13. Summary
• ADVANTAGES:
• Low energy consumption
• High conversion ratio(nearly 80%)
• Low space and material
requirements(Low-cost setup)
• High brine concentration can
be achievable.
• No need of osmotic pressure
• Environment friendly
• DISADVANTAGES
• Neutral toxic components such as
viruses or bacteria are not removed
from a feed stream
• Only removes ions, organics and
colloids are not removed.
• Purity effected by feed water
• Selection of membranes highly
dependent on the quality of feed
water.

14. Conclusion
• ED process has been found reliable treatment method for waste-
water since more than half-a-century. In comparison to other
separation techniques such as reverse osmosis, ultra-filtration,
nano-filtration and ion exchange, ED has shown more benefits.
• ED process can help in recycling of reuse valuable products and
it has regarded as an important technique for sustainable
development because it is an environment friendly process.
• More research is required for improvement of ED process and for
developing new cleaning methods in order to prevent fouling.

15. References & Supporting content
• https://en.wikipedia.org/wiki/Electrodialysis
• MANUAL OF WATER SUPPLY PRACTICES ---- M38, First Edition
Electrodialysis and Electrodialysis Reversal
• https://www.climate-policy-watcher.org/reverse-
osmosis/applications-of-electrodialysis.html
Thank You....