Affordable clean water using nanotechnology T. Pradeep Department of Chemistry and Sophisticated Analytical Instrument Facility Indian Institute of Technology Madras Chennai 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.
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Affordable clean water using nanotechnology · 2007 Launch of world's first nanotechnology based domestic water purifier (Pradeep, Eureka Forbes Limited) Milestone Important milestones
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Affordable clean water using nanotechnology
T. PradeepDepartment of Chemistry and Sophisticated Analytical Instrument Facility
Indian Institute of Technology MadrasChennai 600 036, INDIA
• 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
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
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,