CHE ENGG.

1. NANOTECHNOLOGY
SEEMS SMALL BUT
COULD BE THE
SOLUTION TO THE
GLOBAL PROBLEM OF
WATER POLLUTION
RAJAT TIWARI
CSJMA14001390214
1

2. CONTENTS
• What is nanotechnology?
• Various applications of nanotechnology.
• Nanotechnology in water treatment.
• Nanobased materials, processes, and applications.
• Limitations of nanobased materials and processes
for water treatment applications.
• Conclusion and future prospects.
• References
2

3. What is NANOTECHNOLOGY?
3

4. Originated
from the
Greek word
‘nanos’
which
essentially
means
DWARF
4

5. One billionth of a metre
5

6. Conceptualized by Richard P
Feynman.
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7. 7

8. Various
applications of
nanotechnology
•Molecular Electronics
•Optical communications
•Medicines
•Fuel cells
•Space
•Better air quality
•Cleaner water
•Chemical sensors
•Fabrics
•Food 8

9. WE HAVE A PROBLEM
9

10. Nanotechnology in water treatment
10
Nanomaterial Properties Applications
Nanoadsorbents + high specific
surface, higher
adsorption rates
− high production
costs
Point-of-use, removal
of organics, heavy
metals, bacteria
Nanometals and
nanometal oxides
+ short intraparticle
diffusion distance,
abrasion-resistant
− less reusable
Removal of heavy
metals (arsenic) and
radionuclides, media
filters, slurry reactors,
powders

11. Nanomaterial Properties Applications
Membranes and
membrane
processes
+ reliable, largely
automated process
− relative high
energy demand
All fields of water
and wastewater
treatment processes
11

12. Carbon
Nanotubes
• Allotropes of carbon.
• Cylindrical nanostructure.
• Single -walled and multiwalled
nanotubes.
• Hydrophobic surface.
• Exhibit antimicrobial properties.
• Used for point-of-use water
purification devices.
• High production costs.
12

13. 13

14. Nanosilver and
Nano TiO2
• Nanosilver is used in the swimming
pool algaecides and drinking water
filters.
• No harmful effects in humans.
• Applied to point-of-use water
disinfection systems.
• Nano-titanium dioxide (TiO2) has high
chemical stability and low human
toxicity at cheap price.
• Nearly endless life time.
• Needs energy-consuming ultraviolet
lamps for activation.
• Nanosilver kills bacteria with no need
of additional energy-consuming devices.
• That makes nanosilver a favorable
disinfectant for remote areas. 14

15. Nanofiltration
Membranes
•Pressure driven process
•Charge based repulsion
mechanism
•Reduction of hardness,
color, odor, and heavy
metal ions
•Filters particles between
0.5 – 1 nm.
•Can be used in
desalination processes.
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16. PHOTOCATALYSIS
• Persistent compounds like
antibiotics or other micropollutants
can be photocatalytically eliminated
• Utraviolet A radiation is only
about 5% that of sunlight, the
photon efficiency is quite low,
limiting use on an industrial scale.
• Advanced oxidation
process
• TiO2 is widely utilized as a
photocatalyst
• TiO2 is irradiated by
ultraviolet light
• Electrons move into the
conduction band
• Electron hole pairs are
created
• Leads to a complex chain of
oxidative-reductive
reactions
16

17. Limitations of nanobased materials and
processes for water applications
• CNTs high production costs.
• Difficulties with adaption of the techniques to large-scale
membrane areas.
• Harmful effects on aquatic organisms
• No online monitoring systems exist that provide reliable real-
time measurement data on the quality and quantity of
nanoparticles present only in trace amounts in water.
• For photocatalysis the ultraviolet A radiation is only about 5%
that of sunlight, the photon efficiency is quite low, limiting use on
an industrial scale.
17

18. Conclusion and future prospects.
• There is a significant need for novel advanced water technologies.
• Nanoengineered materials offer the potential for novel water
technologies that can be easily adapted to customer-specific
applications.
• Nanomaterials enable higher process efficiency due to their unique
characteristics.
• High innovation potential still exists in the field of effluent
monitoring systems for nanomaterials.
• Nanoengineered water technologies are rarely adaptable to mass
processes.
• In many cases these are not competitive with conventional
treatment technologies.
• Nevertheless, nanoengineered materials offer great potential for
water innovations in the coming decades.
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19. REFERENCES
1. Textbooks :
- P. Ghosh, Colloid and Interface Science, PHI Learning, New Delhi, 2009, Chapter 11.
2. Online Journals:
- Innovations in nanotechnology for water treatment,
Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4294021/
- Introduction to Nanomaterials & Nanotechnology,
NPTEL Chemical Engineering Interfacial Engineering
Dr. Pallab Ghosh Associate Professor
Department of Chemical Engineering IIT Guwahati
- Encyclopaedia Britannica Adsorption,
Available from: www.britannica.com/EBchecked/topic/6565/adsorption
3. Image courtesy:
www.google.com 19

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And remember, The Next BIG THING is REALLY SMALL.