Affordable clean water using nanotechnology
T. PradeepDepartment of Chemistry and Sophisticated Analytical Instrument Facility
Indian Institute of Technology MadrasChennai 600 036, INDIA
http://www.dstuns.iitm.ac.in/pradeep_research_group.php
Potential Environmental Benefits of Nanotechnology: Fostering safe innovation-led growth OECD July 15-17, 2009
Celebrating 50 years
It is the poor who drive our society.
Chapter by T. Pradeep and Anshup
O
H H
99.84 pm
104.45O
2 nm
Gas hydrates to ozone chemistry
Claude Monet, Waterlilies, 1906
Oil on Canvas, The Art Institute of Chicago
Water - prosperity, health, serenity, beauty, artistry, purity …..
Water - ―the vehicle of nature" ("vetturale di natura‖) – Leonardo Da Vinci
Subject: Leonardo, Old Man with Water Studies, c. 1513
Leonardo
Old Man with Water Studies, c. 1513
Leonardo
Machine for raising water
Mohenjodaro - well
Mohenjodaro – the great bath
Aqueducts - The Assyrians
- the first structure to carry
water from one place to
another - 7th century BC
Archimedes’ screw - 287 and 212
BC - in the Netherlands
Zoetermeer
Water and civilizations
http://dspace.rice.edu/bitstream/1911/9176/773/LanMa1890_135_a.jpg
hof.povray.org/River.html
Microbes Heavy metals Chemicals,
pesticides
Nitrates
Fluoride
Asbestos
……
Water filtration: various media
Year
1804 Setup of world's first city-wide municipal water treatment plant (Scotland, sand-filter technology)
1810 Discovery of chlorine as a disinfectant (Humphrey Davy)
1852 Formulation of Metropolis Water Act (England)
1879 Formulation of Germ Theory (Louis Pasteur)
1902 Use of Chlorine as disinfectant in drinking water supply (calcium hypo chlorite, Belgium)
1906 Use of ozone as disinfectant (France)
1908 Use of Chlorine as disinfectant in municipal supply, New Jersey
1914 Federal regulation of drinking water quality (USPHS)
1916 Use of UV treatment in municipal supplies
1935 Discovery of synthetic ion exchange resin (Adams, Holmes)
1948 Nobel Prize to Paul Hermann Müller (insecticidal properties of DDT)
1959 Discovery of synthetic reverse osmosis membrane (Yuster, Loeb, Sourirajan)
1962 Publishing of Silent Spring, first report on harmful effects of DDT (Rachel Carson)
1965 World's first commercial RO plant launched
1974 Reports on carcinogenic by-products of disinfection with chlorine
Formulation of Safe Drinking Water Act (USEPA)
1975 Development of carbon block for drinking water purification
1994 Report on use Zerovalent Iron for degradation of halogenated organics (Gillham, Hannesin)
1997 Report on use Zerovalent Iron nanoparticles for degradation of halogenated organics (Wang, Zhang)
1998 Drinking Water Directive applied in EU
2000 Adoption of Millennium Declaration during the UN Millennium Summit (UN Millennium Development Goals)
2003 Report on use Noble metal nanoparticles for degradation of pesticides (Nair, Tom, Pradeep)
2004 Stockholm Convention, banning the use of persistent organic pollutants
2007 Launch of world's first nanotechnology based domestic water purifier (Pradeep, Eureka Forbes Limited)
Milestone
Important milestones in the history of water purification (1800-2007)
Source: Multiple sources from internet
Credits to several governments, organizations and individuals, we have moved ahead. Now,
the journey of “pure water for all” calls for next big innovation.
Last globally big invention in
water purification
Economic and technical assessment of desalination technologies, Fawzi Banat, From Red Sea to Dead Sea — Water and Energy,
Geneva, June 6-8, 2007 www.desline.com/Geneva/Banat.pdf
The cost of RO solutions has seen a dramatic fall since the discovery, but
the costs have flattened recently.
Costs analysis of Reverse Osmosis Plants(converted to 1995 base year level)
Review of major contaminants in drinking waterMajor
pollutant
Sources of
origin
Permissible
limits
Affected countries Population at risk
(estimates)
Health effects Remarks
Pesticides - Farming,
effluents,
home use
DDT: 1 ppb
Carbofuran:
40ppb
Simazine: 4 ppb
US, Kenya, Egypt,
India, European Union,
Africa, China,
Australia
Poisoning: 28 million
agricultural workers in
developing countries.
~18,000 deaths
Cancer, cardiovascular/
reproductive/
neurological disorders,
Liver/kidney problems
Pesticide
contamination in soft
drinks, Union Carbide
Bhopal tragedy (India)
Halogenated
organics
Chlorination,
effluents,
home
insecticide
CCl4: 5 ppb
TCE: 5 ppb
TTHMs: 80 ppb
Japan, Central Asia,
Arabian Peninsula,
Sweden, Poland,
Germany, USA, Egypt,
China
~180 million people in
US consume
chloraminated water
-CCl4: High toxicity to
liver and kidney,
carcinogenic. TCE:
Lung/liver tumor
- 25 million pounds
TCE were released in
the U.S. environment
by manufacturing
plants in 1995
Fluoride - Geological
origin,
mineral
weathering,
coal mining
2 ppm Asia, Mexico,
Australia, Argentina,
Africa, New Zealand
62 million (India) - Dental and skeletal
fluorosis, Muscle fibre
regeneration, nervous
system malfunction
A union of 1,200
scientists, doctors and
lawyers announced
opposition to water
fluoridation (1999)
Arsenic - Geological
origin
10 ppb Bangladesh, India,
China, Pakistan,
Nepal, Myanmar,
Vietnam
65 million (Asia) High blood pressure,
glucosuria,
hyperpigmentation,
keratoses, cancer
- Death rate: 1 in 100
people (Conc: 50 ppb)
and 10 in 100 people
(Conc: 500 ppb)
Mercury - Industrial
pollution,
dental filling,
Food (fish)
2 ppb Indonesia, China,
Africa, Philippines,
Japan, Kazakhstan,
USA, Brazil, Australia,
Taiwan, EU
~630,000 infants are
born with high Hg
content in the blood
every year (EPA)
Neurotoxicant, tremors,
respiratory failure,
gastrointestinal failures,
and kidney damage
- ~30% of the mercury
in US comes from
abroad e.g. China -
Unilever plant,
Kodaikanal. Minamata,
Niigata, River Nura.
Lead - Old piping
lines, mineral
weathering,
paint
15 ppb Egypt, EU, USA,
Thailand, China,
Cambodia
>300,000 US children
and 65% of Shanghai
children have high lead
concentration
Delays in physical or
mental development,
Kidney problems, high
blood pressure
- Incidence of Gout due
to leaded wine and
rum- Use of lead in
paints and discharge in
environment
Review of major drinking water contaminants, their health impacts and a few associated eventsmultiple sources from internet
Fluoride contamination: Indian Scenario
• 25 million people are suffering from fluorosis and 62 million are
at the risk of fluorosis
Quantum of Fluoride Contamination
Despite being a global contaminant, fluoride is still a unresolved mystery.
A.K. Susheela, Fluorosis management programme in India, Current Science 77 (10) (1999) 1250–1256
0.47 Subernarekha River, West Bengal
0.59 Hugli River, West Bengal
0.85 Saptamukhi River, West Bengal
0.68 Matla River, West Bengal
0.70 Bellandur Lake, Bangalore
Conc(mg/l)
Location
0.47 Subernarekha River, West Bengal
0.59 Hugli River, West Bengal
0.85 Saptamukhi River, West Bengal
0.68 Matla River, West Bengal
0.70 Bellandur Lake, Bangalore
Conc(mg/l) Conc(mg/l)
LocationLocation
Fresh water (Source: PCB)
0.013NTDelhiNazafgarh
0.042<0.005RajasthanJodhpur
0.2240.005RajasthanPali
0.150NTHimachal PradeshKala Amb
0.062NTHimachal PradeshParwanoo
0.08NTPunjabGobindpur
0.01NTUtter PradeshSingrauli
0.01NTMadhya PradeshKorba
MaxMin
Cd (mg/l)StateLocation
0.013NTDelhiNazafgarh
0.042<0.005RajasthanJodhpur
0.2240.005RajasthanPali
0.150NTHimachal PradeshKala Amb
0.062NTHimachal PradeshParwanoo
0.08NTPunjabGobindpur
0.01NTUtter PradeshSingrauli
0.01NTMadhya PradeshKorba
MaxMaxMinMin
Cd (mg/l)Cd (mg/l)StateStateLocationLocation
Ground water (1995-96) (Source: PCB)
NT-2.9 (1999)East Coast
2-25 (1994)Parangipettai Coast
0.98 (1991)River Coovum
1.4 (1987)Madras Coast
2-27 (1994)Cuddalore
0.1-0.6 (1991)Point Calimere
80.00 (1980)Off Bombay
Conc.(μg/l)Location
NT-2.9 (1999)East Coast
2-25 (1994)Parangipettai Coast
0.98 (1991)River Coovum
1.4 (1987)Madras Coast
2-27 (1994)Cuddalore
0.1-0.6 (1991)Point Calimere
80.00 (1980)Off Bombay
Conc.(μg/l)Location
Coastal water (Source: PCB)
• The Palakkad controversy showed that excessive withdrawal of ground water can also expose us to high metal contamination
• The above figures are just a tip of the iceberg (itai-itai)
– India produces 1.46L tons of e-waste annually
– In India, 2M of computers become obsolete every year
– 67,000 tons of computer waste contributed 1.1 tons Hg, 4.5 tons Cd and 3012 tons Pb into landfills (Canada, 05)
– The average Cd generation per computer is 2.8 g
How much of our environment is polluted by cadmium?
Affordable Drinking Water Purifier – Market needs
Mercury contamination, Minamata,
Japan, 1956
Fluoride contamination, India, 2003Pesticide contamination, Kerala, 2001
Microbial contamination, Zimbabwe, 2009
Unsolved technology problems
Images collected from arsenic, fluoride and pesticide affected areas in India
For 8-month old Sainaba to 18-year old Ramaswamy, science still has to deliver its benefits
Pictures from the web
Affordable Drinking Water Purifier – Market needs
Commercial unviability – Pricing issues
Brand Aquasana Amway Culligan Kenmore GE Ever Pure Aqua-Pure PUR Brita Brita
Model
Number
AQ-4000 E-5199 SY-2300 Deluxe
38465
Smart Water
GXSV10C
H-54 DWS1000 Plus FM-
3000
Faucet Filter Pitcher
Filter
Retail
Price
$124.99 $420.00 $159.99 $149.99 $139.99 $149.99 $349.95 $49.95 $34.95 $24.95
Replacem
ent Cost
&
Capacity
$48.00 /
500 Gal.
$120.00 /
1250 Gal.
$50.39 /
500 Gal.
$49.00 /
500 Gal.
$60.00 / 540
Gal.
$79.95 / 750
Gal.
$79.99 / 625
Gal.
$20.00 / 100
Gal.
$20.00 / 100
Gal.
$7.70 / 30
Gal.
Cost per
gallon
9.6 ¢ Per
Gal.
9.6 ¢ Per
Gal.
10¢ Per
Gal.
9.8¢ Per
Gal.
11¢ Per Gal. 10.6¢ Per
Gal.
13¢ Per Gal. 20¢ Per
Gal.
20¢ Per Gal. 25¢ Per
Gal.
Chlorine >99% 97.9% 97% 99% 97% 96% 97% 98% 99% >75%
Lead >99% 98% 95% 92% 98% 97% 95% 96% 99% 93%
Cysts >99.99% 99.5% 99% NO >99% >99% >99% 99.99% 99.99% NO
THMs >99% >99% 95% 99% 95% NO 92% NO NO NO
VOCs >99% >99% 95% 95% 99% NO 92% NO NO NO
Lindane >99% 72.7% 99% 99% 99% NO >99% 97% 99% NO
Alachlor >98% 95% 98% 95% 98% NO 98% NO 99% NO
Atrazine >97% >97% 97% 97% 97% NO 97% 96% 92% NO
Benzene >99% >97% 99% 83% 99% NO >99% NO 96% NO
TCE >99% >98% 99% 98% 99% NO >99% NO 99% NO
MTBE >97% NO 90% NO NO NO NO NO NO NO
Cost per
1000 gals.
$172.99 $420.00 $210.38 $198.99 $199.99 $229.90 $349.95 $229.95 $214.95 $273.91
Our goals of a socially relevant science has largely failed due to
our inability to serve people at bottom-of-the-pyramid
Affordability of Technology
• What does this cost-of-ownership for access to pure water and income-based societal structure mean
to us?
– Need for a revolutionary theme for guaranteeing access to pure water to everybody - under INR
1,000 water purifier (<$20)
• Universal purifier: Remove suspended particles, pesticides, microbes, metals and anions
• Zero electricity
• Minimum maintenance and low-cost of annual replacement (< INR 450/-) (<$10)
• Indeed, early signs of success of nanotechnology gives a ray of hope
INR 7590
($ 168)
Turbidity, Chlorine, Bacteria, Virus,
OdorINR 7690
($ 171)
Turbidity, Chlorine, Bacteria, Virus,
OdorINR 9,590
($ 213)
Turbidity, Chlorine, Bacteria,
Virus, Odor, Pesticides
INR 15,500
($ 345)
TDS, Taste, Heavy metals,
pesticides, F-/NO3
-
INR 2,000
($ 45)Turbidity, Chlorine, Bacteria, Virus
INR 650
($ 15)Turbidity, Chlorine, Bacteria, Virus
- Bacteria, Virus
INR 250
($ 6)-
Reference: Eureka Forbes Ltd, Bangalore (2008)
Bottled Water
Rs 0.61
Rs 0.70
Rs 0.94
Rs 1.86
Rs 0.33
Rs 0.18
Rs 2.0
Aquasure on Tap Rs 0.12
Aquaguard Gold
Nova
Aquaguard RO
Aquasure 4-in-1
Boiling
Average cost
per liter (10 yrs)
Aquaguard Classic
Aquaguard Nova and I-
Nova
Product
Price
Products from
Eureka Forbes LtdFunctions
Income
Segment
Annual Household
Income ($)
# of
Households
(in '000)Community <$ 2,000 132,249
$2,000-$4,500 53,276
$4,500-$11,000 13,183
$11,000-$22,000 3,212
$22,000-$44,000 1,122
$44,000-$111,000 454
$111,000-$222,000 103
$222,000 52
Source: www.ncaer.org - Year 2005
High-Budget
Low-Budget
An object for the nanotechnology - nanomaterials
2 nm
5 nm5 nm5 nm
20 nm
A
0 100 200 300 400
0
5
10
15
20
Hei
ght (
nm)
Distance (nm)
B
C
200 nm
100 nmDD400 600 800 10000.0
0.2
0.4
0.6
Abs
orba
nce
I
II
III
Wavelength (nm)
Range of nanostructured materials
http://www.nano-
lab.com/imagegallery.html
http://www.physics.upenn.edu/~dr
ndic/group/graphene.html
PJF Harris et. al., J. Phys.: Condens.
Matter 20 (2008) 362201
Y. Xia et. al., Adv. Mater 2002,
14,11,833
STM image of MoS2 nanoflakes. From, Nanotechnology
14, pp. 385-389 (2003)
Nanocatalysis
USEPA has played a key role in determining the
regulations for many toxic species found in drinking water
Regulatory coverage of USEPA for safe drinking water has increased over 4times since its inception, with revisions in regulations of many old contaminants
1
3
1
4
2
9
1
5
1 1 1 1 1 1 1
6 67
9
15
21
10
5
2
44
65
13
4
0
5
10
15
20
25
r q p o n m l k j i h g f e d c b a
Label for contaminants
Nu
mb
er o
f co
nta
min
ants
1
3
1
4
2
9
1
5
1 1 1 1 1 1 1
6 67
9
15
21
10
5
2
44
65
13
4
0
5
10
15
20
25
r q p o n m l k j i h g f e d c b a
Label for contaminants
Nu
mb
er o
f co
nta
min
ants
Candidate contaminant list
Contaminants regulated by EPA
(a): Halogenated organic (b): Metal (c): Organochlorine pesticide (d): Inorganic
salt (e): Biological contaminant (f): Nuclear (g): Benzo derivative (h): Carbamate
pesticide (i): Pesticides (others) (j): Unclassified (k): Triazine derivative pesticide
(l): Organophosphorus pesticide (m): Organobromine pesticide (n): Non-metal
(o): Nitrophenol derivative, (p): Dioxin, (q): Benzo and halogenated organic (r):
Organometallics
Category-wise distribution of contaminants regulated by USEPA and future contaminants
Future of water purification: An enigma with some pointers
Continued focus of USEPA regulatory activities on various other halogenated organics found
in drinking water. The allowed concentration limits for a number of species may shift to sub-
ppb range.
Source: www.epa.org and www.who.int
10
100
50
100
50
50
200
0
50
100
150
200
1950
1960
1970
1980
1990
2000
Year
Co
nce
ntr
atio
n (
in p
pb
)
Lead
Arsenic
Changes in maximum allowable concentration for lead and arsenic in drinking
water, based on WHO advisory
Future of water purification: Shrinking limits for allowed concentration of
contaminants in water
Nanotechnology holds the future for effectively
removing many drinking water contaminants
- Number of contaminants present in extremely low concentration range (<1015 molecules per glass of water) are quite significant
- Many of those contaminants contain C-Cl bond or are metallic in nature
Perm
issib
le co
nta
min
ation
Time
Permissible contamination reaches limits of detection
1012 molecules
Organics
Pesticides
Traditional methods (activated carbon, membranes)
Nanomaterials
Metals, oxides, clays, dendrimers
Tansel and Nagarajan, Advances in Environmental Research 8, 2004, 411–415
Plakas, Karabelas, Wintgens and Melin, Journal of Membrane Science 284, 2006, 291–300
Illustration of metal adsorption on nanoparticle surface (ZVI surface)
XPS wide-scan survey of iron nanoparticles after exposure to a metal
salt containing solution, Sequestration of Metal Cations with Zerovalent
Iron Nanoparticless A Study with High Resolution X-ray Photoelectron
Spectroscopy (HR-XPS), Xiao-qin Li and Wei-xian Zhang, J. Phys.
Chem. C 2007, 6939-6946
TEM image of Fe nanoparticle and Cartoon representation of chemistry at Fe
nanoparticle, Iron Nanoparticles: the Core-Shell Structure and Unique
Properties for Ni(II) Sequestration, Xiao-qin Li and Wei-xian Zhang, Langmuir
2006, 4638-4642
Cartoon representation of chemistry at Fe nanoparticle surface (left) and metal ion removal efficiency for different adsorbents, Iron Nanoparticles: the Core-Shell
Structure and Unique Properties for Ni(II) Sequestration, Xiao-qin Li and Wei-xian Zhang, Langmuir 2006, 4638-4642
(L) HR-XPS survey on the Ni 2p3/2 of iron nanoparticles (R) a conceptual model for nickel deposition on
iron nanoparticles
Metal adsorption on nanoparticle surface (ZVI surface)
Binding energy (eV)859 856 853 850
Co
un
ts (
X 1
04 )
0
0.6
1.2
1.8
2.4
Ni2+Ni0
24 hrs
3 hrs
1 hr
15 min
(b) (c)Ni(II) Ni(II)
Reduction
Ni(0)
Fe(0)Fe(0) FeOOH
Sorption
Ni2+ + 2e- → Ni Eº = -0.25 V
Fe → Fe3+ + 3 e- Eº = 0.44 V
96 99 102 105 108 111
After 24 hrs
Ag@citrate-Hg(OAc)2
105.4
104.2100.2
101.4
100 ppm
7 ppm
50 ppm
10 ppm
Hg(II)
Hg(0)
Hg 4f5/2
Hg 4f7/2
Co
un
ts
Binding Energy (eV)
Bootharaju et al. Unpublished
(a) Schematic illustration of ceramic membranes and TEM images of the boehmite (top) and
titanate (bottom) nanofibers, (b) SEM image of feed water containing 60 nm latex spheres
and permeate water (inset). Filtration efficiency=96.8%
(a) (b) 1 μm
1 μm
X.B
. Ke,
Z.F
. Zhe
ng, H
.W. L
iu, H
.Y. Z
hu, X
.P. G
ao,
L.X
. Zha
ng, N
.P. X
u, H
. Wan
g, H
.J. Z
hao,
J. S
hi,
K.R
. Rat
inac
, J. P
hys.
Che
m. B
112
(20
08)
5000
.X
.B. K
e, H.Y. Z
hu, X.P. G
ao, J.W. Liu, Z
.F. Zheng,
Adv. M
ater. 19 (2007) 785
Metal oxide and MWNT assembly based membrane filtration
0 sec 15 sec 30 sec
45 sec 60 sec 80 sec
Pt wire(a) (b)
Images of water droplet shape change with a +2.6 V potential applied with a multiwalled
nanotube film as anode and Pt wire as cathode. The droplet sinks into the nanotube membrane
in about 90 s. (b) SEM image of a cylindrical macrostructure assembly showing the wall of the
bulk tube consisting of aligned MWNTs with lengths equal to the wall thickness (scale 100 μm)
G. H
umm
er, J
.C. R
asai
h, J
.P. N
owor
yta,
Nat
ure
414
(200
1) 1
88.
Z.W
ang, L. Ci, L. C
hen, S. N
ayak, P.M.
Ajayan, N
. Koratkar, N
ano Lett. 7 (2007) 697
--
+
+
+
+
+
+
+
-
-
----
-
-
-
++
++
++
++
++
++
++
400 600 800 10000.0
0.2
0.4
ba
Ab
sorb
ance
Wavelength(nm)
With
Endosulfan
A
B C
A
B C
Gold
nanoparticles
300 500 700 900
0.6
300 500 700 900A
bso
rban
ce0
0.2
0.4A
B C
A
B C
Gold
nanoparticles
With mercury
Wavelength (nm)300 500 700 900
0.6
300 500 700 900A
bso
rban
ce0
0.2
0.4A
B C
A
B C
Gold
nanoparticles
With mercury
Wavelength (nm)
Heavy metals
Halogenated organics & pesticides
Bacteria & virus
Noble metal nanomaterials: Novel chemistry for water purification
The novel chemistry of noble metal nanomaterials help them target broad range of toxic
contaminants. We will see a glimpse of it in the later slides.
Reactions with pesticides
Endosulfan
Color changes with pesticide concentrationGood response at lower concentrationsDown to 0.1 ppmAdsorbed pesticides can be removed from solution
Color of gold nanoparticles with endosulfan
Endosulfan concentration in ppm
02100 200
Example
Pesticide removalIndian Patent grantedInternational patent filedTechnology commercialized
J. Environ. Monitoring. 2003
Some of the pesticides contain halocarbons whereas others
have P or S, which can bind metal nanoparticles which is used
for pesticide detection and extraction.
Endosulfan Chlorpyrifos Malathion
400 500 600 700 800 900 1000 1100
0.0
0.1
0.2
0.3
0.4
0.5
edcba
Abs
orba
nce
Wavelength(nm)400 500 600 700 800 900 1000 1100
0.0
0.1
0.2
0.3
0.4
c
b
t
a
Abs
orba
nce
Wavelength (nm)
UV-visible spectra of gold nanoparticles showing the detection
of endosulfan at different concentrations (b.2, c.10, d.100 and
e. 250 ppm). Inset (A-D): Color changes of the solutions
corresponding to traces a, b, c and d, respectively.
Time dependent adsorption of endosulfan on gold nanoparticles
and the corresponding spectral changes (a-t). The shifts in the
plasmon band are due to the binding of the pesticide on the
nanoparticle surface.
Endosulfan Chlorpyrifos Malathion
Activated alumina globules (A) and gold (B) and silver (C)
nanoparticles coated on the same.
4 cm
Supported nanoparticles for pesticide removal
Silver nanoparticles coated on activated alumina
(neutral) powder
These can be made in ton quantities.
Absorption spectra showing the time dependent removal of 1 ppm chlorpyrifos (left) and
malathion (right) by supported nanoparticles. The reduction in the absorbance feature
with time is due to the adsorption of the pesticides on the nanosurface. Inset shows
reduction in absorbance with time. Time interval between spectra was 20 minutes.
300 400 500 600 700 8000.00
0.05
0.10
0.15
Absorb
ance
Wavelength (nm)
s
r
c
b
a
0 100 200 300 400 500 6000.00
0.04
0.08
0.12
0.16
Ab
so
rba
nce
Time (minutes)
300 400 500 600 700 800
0.00
0.05
0.10
0.15
q
p
c
b
a
Absorb
ance
Wavelength (nm)
0 100 200 300 400 500 6000.00
0.04
0.08
0.12
Absorb
an
ce
Time (minutes)
Nanoparticle loaded alumina can remove pesticides
400 600 800 1000
0.00
0.05
0.10
b-e
a
Ab
so
rba
nce
Wavelength (nm) 3000 2500 2000 1500 1000 500
30
40
50
60
70B
a
% Tr
ansm
ittanc
e (Ar
b.Unit
s)
Wavenumber (cm-1)
b
3000 2500 2000 1500 1000 50020
40
60
80
100
A
% Tr
ansm
ittanc
e (Ar
b.Unit
s)
a
b
Absorption spectra showing the complete removal ofpesticides when contaminated water was passed througha column of the nanomaterial. Trace a is the spectrum ofthe parent pesticide solution, b-e after passing throughthe nanoparticle-loaded column, in repeated experiments.
Infrared spectra of the free pesticides (a) and that adsorbedon the nanoparticle surfaces (b) chlorpyrifos (A) andmalathion (B).
Other scientific tests conducted confirm the complete removal of commonly
occurring pesticides from water
Product of this reaction is amorphous carbon
400 600 800 10000.0
0.5
1.0
1.5
Ab
sorb
ance
Wavelength (nm)
p
o
ba
A B
Time (min)2 4
-600
-400
-200
0
200
400
0Time (min)
2 40
-0.5
0.0
0.5
[V]
2.14
2.5
2.93
3
3.30
7C
P
[mV]
(a) Time (min)2 4
-600
-400
-200
0
200
400
0Time (min)
2 40
-0.5
0.0
0.5
[V]
2.14
2.5
2.93
3
3.30
7C
P
[mV]
Time (min)2 4
-600
-400
-200
0
200
400
0Time (min)
2 40
-0.5
0.0
0.5
[V]
2.14
2.5
2.93
3
3.30
7C
P
[mV]
(a)
(b)
(c)(c)
Noble metal nanoparticles: removal of pesticides from water
Variation of the UV-visible absorption
spectrum of silver nanoparticles upon
the addition of CCl4
Gas chromatogram of chlorpyrifos solution (L) and after
treatment with silver nanoparticles (R)
(L) Silver nanoparticles coated on activated alumina (R) Photograph of a pesticide filter device using supported
nanoparticles (WQA certified)
A.S
. Nai
r, T.
Pra
deep
, Cur
r. S
ci. 8
4 (2
003)
156
0A
.S. N
air,
R.T
. Tom
, V.R
. Raj
eev
Kum
ar,
C. S
ubra
man
iam
, T. P
rade
ep, C
osm
os
3, (
2007
) 10
3 June 2007
Product is marketed now
Cartridges are recovered after use
A pesticide test kit has been developed > 25 ppb
C
20nm
Wavelength (nm)300 500 700 900
Ab
sorb
ance
0
0.2
0.4
0.6A BA Bba
ab
C
20nm
Wavelength (nm)300 500 700 900
Ab
sorb
ance
0
0.2
0.4
0.6A BA Bba
ab
20 nm
(A)
100nm
(B)
(C)
+++++
+
+*
*
b
+
+
(100
) (00
2)
(101
)
(102
)
(110
)
(103
)
(112
)(2
01)
(004
)(2
22)
(111
)
(111
)(2
00)
(220
)
(311
)(2
22)
a
2θ (degrees)30 50 70 806040
Inte
nsi
ty
+++++
+
+*
*
b
+
+
(100
) (00
2)
(101
)
(102
)
(110
)
(103
)
(112
)(2
01)
(004
)(2
22)
(111
)
(111
)(2
00)
(220
)
(311
)(2
22)
a
2θ (degrees)30 50 70 806040
Inte
nsi
ty
(D)
C
20nm
Wavelength (nm)300 500 700 900
Ab
sorb
ance
0
0.2
0.4
0.6A BA Bba
ab
C
20nm
Wavelength (nm)300 500 700 900
Ab
sorb
ance
0
0.2
0.4
0.6A BA Bba
ab
20 nm
(A)
100nm
(B)
100nm
(B)
(C)
+++++
+
+*
*
b
+
+
(100
) (00
2)
(101
)
(102
)
(110
)
(103
)
(112
)(2
01)
(004
)(2
22)
(111
)
(111
)(2
00)
(220
)
(311
)(2
22)
a
2θ (degrees)30 50 70 806040
Inte
nsi
ty
+++++
+
+*
*
b
+
+
(100
) (00
2)
(101
)
(102
)
(110
)
(103
)
(112
)(2
01)
(004
)(2
22)
(111
)
(111
)(2
00)
(220
)
(311
)(2
22)
a
2θ (degrees)30 50 70 806040
Inte
nsi
ty
(D)
Noble metal nanoparticles: removal of heavy metals from water
(Left) Large area TEM image of gold nanoparticles (A) before Hg(0) treatment (B) after Hg(0) treatment
(Center) UV-vis absorption spectra of gold nanoparticles before and after mercury treatment (Inset: photographs)
(Right) XRD patterns of gold nanoparticles (D) before and (E) after mercury treatment (symbols: + Au3Hg, * Au)
K.P
. Lis
ha, A
nshu
p, T
. Pra
deep
, Gol
d B
ull.
42 (
2009
) 14
4
200 400 6000.00
0.05
0.10
(viii)(ix)
(ii)
(i)
Hg2+
(50ppm, 50ml) with Ag NP (5ml)
Wavelength (nm)
Ab
sorb
ance
(a)
(b)
5 μm
(b)
Ag|Si Hg|Si2 μm
(a) (b) (c)
Noble metal nanoparticles: removal of heavy metals from water
(a) UV-vis absorption spectra of silver nanoparticles (i) before Hg2+ treatment (ii-ix) after
Hg2+ treatment. (b) Large area SEM image of the Ag-Hg bimetallic nanoparticles
(a) SEM image of an Ag-Hg alloy nanoparticle, (b) elemental image of Ag and (c) elemental image
of Hg overlaid on Si (Si is from ITO substrate).
T. P
rade
ep e
t al (
unpu
blis
hed)
Concentration of silver (µg)0 40 80 0 40 80
0 40 80 0 40 80
log
(1+
X)
0
2
4
6
8
0
2
4
6
8
0
2
4
6
8
0
2
4
6
8
AgNO3
R2 = 0.98
Rod
R2 = 0.9689
Sphere
R2 = 0.9878
Triangle
R2 = 1
(B)
Concentration of silver (µg)0 40 80 0 40 80
0 40 80 0 40 80
log
(1+
X)
0
2
4
6
8
0
2
4
6
8
0
2
4
6
8
0
2
4
6
8
AgNO3
R2 = 0.98
Rod
R2 = 0.9689
Sphere
R2 = 0.9878
Triangle
R2 = 1
(B)a b
c d
a b
c d
a b
c d
a b
c d
(A) AgNO3 Rod
Sphere Triangle
Noble metal nanoparticles: removal of bacteria (E. coli) from water
(A) Petri dishes initially supplemented with 107 CFU/ml of E. coli and incubated with different forms of silver
nanoparticles at (a) 1, (b) 12.5, (c) 50, and (d) 100 μg. (B) Number of E. coli colonies, expressed as
log(1+number of colonies grown on plates under the conditions used for panel A) as a function of the amount of
silver nanoparticles in agar plates.J.R
. Mor
ones
, J.L
. Ele
chig
uerr
a, A
. Cam
acho
, K. H
olt,
J.B
. Kou
ri, J
.T. R
amire
z,
M.J
. Yac
aman
, Nan
otec
hnol
ogy
16 (
2005
) 23
46
Raman Shift (cm-1)300 500 700 900
SE
RS
Inte
nsi
ty
(a)
Raman Shift (cm-1)300 500 700 900
SE
RS
Inte
nsi
ty
PVPBTHDTMDA
(b)
SE
RS
Inte
nsi
ty
Raman Shift (cm-1)500 600 700 800 900 1000
AsIII + AsV
AsV
(c)
SERS spectra of arsenate ion (1X10-6 M) on (a) LB films of silver nanocrystals (b) LB arrays of silver
octahedra coated with various organic species. BT: benzenethiol, HDT: hexadecanethiol, MDA:
mercaptodecanoic acid. (c) SERS-based speciation of arsenate and arsenite ions (18 ppb)
Noble metal nanomaterials: detection of toxic species
A
B C
A
B C
A
B C
A
B C
A
B C
A
B Ca b c
50 nm 50 nm 50 nm
a b c d e fa b c d e fa b c d e fa b c d e f(A)
(B)
400 500 600 700 800 9000.0
0.1
0.2
0.3 f
e
d
c
b
a
Ab
so
rban
ce
Wavelength (nm) Wavelength (nm)400 600 800
Ab
sorb
ance
0
0.1
0.2
0.3
a
b
c
de
f
(c)(C)
Colorimetric detection of chlorpyrifos using the gold nanoparticle-Na2SO4 system
Au a+Na2SO4 b+50 ppb
CP
b+100 ppb
CPb+500 ppb
CP
b+1 ppm
CP
M. M
ulvi
hill,
A. T
ao, K
. Ben
jaut
hrit,
J.
Arn
old,
P. Y
ang,
Ang
ew. C
hem
. Int
. Ed.
47 (
2008
) 64
56
K.P
. Lis
ha, A
nshu
p, T
. Pra
deep
, J. E
nviro
n. S
ci. H
ealth
B. (
in p
ress
)
PollutantsHarmless products
CO2
TiO2
HCs
Polluted water Purified water
As adsorption
Magnetic Fe3O4 nanopartilcles
Purification by circulation
Magnetic clays for oil cleanup
Antibody tagging
Magnetic hyperthermia
Magnetic batch separation of 16-nm water-soluble Fe3O4 nanocrystals
(A) Fe3O4 solution (B) After application of magnetic field (C) TEM images
of the nanocrystals
Low
-Fie
ld M
agne
tic S
epar
atio
n of
Mon
odis
pers
e F
e3O
4 na
nocr
ysta
ls, C
. T. Y
avuz
, J. T
. May
o, W
W Y
u,
A P
raka
sh, J
C F
alkn
er, S
Yea
n, L
Con
g, H
J S
hipl
ey, A
Kan
, M T
omso
n, D
Nat
elso
n, V
L C
olvi
n, S
cien
ce,
2006
, 314
, 964
iw
Product Name Nanomaterial utilized Contaminants removal Adsorption capacity Product life Product price
Aquaguard Gold Nova, Eureka
Forbes Limited
Silver nanoparticles supported on
alumina
Pesticides and halogenated organics- 6000 liters $50
Adsorbia Titania nanoparticles
Arsenic and disinfection
12-15 gm As(V) and 3-
4 gm As(III) per kg of
adsorbent
- -
AD33, Adedge Technologies, Inc. Iron oxide nanoparticles Heavy metals including arsenic, lead,
chromium, zinc, copper- 3,800-11,400 liters $50
Nanoceram, Argonide Electropositive alumina nanofibers
on a glass filter substrate
Disinfection, natural organic matter,
turbidity, salt, radioactivity, heavy metals - -$3-10 per sq m
2,
$75 per filter
ArsenX, SolmeteX, Inc. Hydrous iron oxide nanoparticles on
polymer substrate
Arsenic, vanadium, chromium, uranium 38 mg of Arsenic per
gm of adsorbent-
$0.07-0.20 per
1,000 liters
(amortized due to
reusability)
Nanopore, Nanovation AG Membrane filters based on ceramic
nanopowder supported on alumina
Disinfection
- - -
Examples of a few nanotechnology-based products in drinking water purification market (compiled from multiple sources
on the World Wide Web)
Commercial interests in drinking water purification
Current developments
Purifiers for specific areas – local issues – seasonal problems
All inclusive solutions
Local manufacture
Community involvement – NGOs
What OECD can do?
A white paper on available technologies
Act as a link between those who need the technology and those who have the solutions
Conduct discussions in places where technologies are needed
E. F. Schumacher
Pure water can be affordable…..
IIT Madras
Thank you all
Nano Mission, Department of Science and Technology
World Gold Council
Well-meaning individuals
Confocal Raman Microscope
Ultramicrotome
QTrap MS
Transmission
Electron Microscope
MALDI TOF MS
Nanoscience and Nanotechnology Initiative of the DST
Scanning Electron Microscope
XPS