Noble metal nanoparticles for water purification-a ... metal... · Noble metal nanoparticles for...

December 12, 2008

Noble metal nanoparticles for water purification: A critical reviewThin Solid Films

Professor Pradeep’s Research Group

DST Unit on Nanoscience

IIT Madras

Content of the review article

1. Introduction

2. Drinking water purification – a historical perspective

3. Need for nanomaterials in water purification – the need to look at molecular technologies

4. Noble metal nanoparticle based chemistry

4.1 Synthesis protocols

4.2 Origin of reactivity

4.3 Heterogeneous catalysis - methods for nanoparticle deposition on support

4.4 Drinking water purification: Novel reactions at the nano-scale

4.4.1 Chemistry of organic compounds with noble metal nanoparticles

4.4.2 Detection of pesticides in drinking water with noble metal nanoparticles

4.4.3 Chemistry of heavy metal ions with noble metal nanoparticles

4.4.4 Detection of heavy metals in drinking water with noble metal nanoparticles

4.4.5 Chemistry of micro-organisms with noble metal nanoparticles

5. Case study: Nanoparticles based chemistry for pesticides removal

6. Other nanomaterial based approaches for water purification

7. Commercial interests in drinking water purification

8. Environmental implications of the use of noble metal nanoparticles

9. Summary and conclusions

10. Acknowledgements

11. References

Introduction – relationship of life and human civilization with

water

- Water has been the most vital component of life during its existence on earth for last 3.5 billion years.

- The earliest form of life appeared in sea water (3.5 billion years ago) and

transferred to land only 380 million years ago.

- Despite of this transfer to land, an ocean, in terms of fluidic composition, continues to exist within us. Similarly keeping a very high proportion of living organisms’ body weight as water (~70%), Nature has iterated the vitality of water

for life.

- Water is one of the purest signs of prosperity, health, serenity, beauty, artistry, purity and many other attributes. Leonardo Da Vinci had described water as “the

vehicle of nature" ("vetturale di natura”).

- The Nile was the lifeline of the Egyptian civilization. The Indus Valley civilization flourished on the banks of the Indus river.

Noble metals in human life

- Gold and silver belong to the family of “metals of antiquity”, having their history with mankind dating back to 6,000 BC and 4,000 BC respectively. They have been

associated with the gods, with immortality, and with wealth across the human civilizations.

- Use of noble metals in medicines is aplenty: swarna bhasma, tears of the sun,

arthritis and anti-bacterial.

Drinking water purification – a historical perspective

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)multiple sources from internet

Review of major contaminants in drinking water

- Incidence of Gout due to leaded wine and rum- Use of lead in paints and discharge in environment

Delays in physical/ mental development, Kidney problem, high blood pressure

>300,000 US children and 65% of Shanghai children have high lead concentration

Egypt, EU, USA, Thailand, China, Cambodia

15 ppb- Old piping lines,

mineral weathering, paint

Lead

- ~30% of the mercury in US comes from abroad e.g. China- Unilever plant, Kodaikanal(India). Minamata, Niigata (Japan), River Nura(Kazakhstan).

Neurotoxicant, tremors, respiratory failure, gastrointestinal failures, and kidney damage

~630,000 infants are born with high Hg content in the blood every year (EPA)

Indonesia, China, Africa, Philippines, Japan, Kazakhstan, USA, Brazil, Australia, Taiwan, EU

- 2 ppb- Industrial pollution,

dental filling, Food (fish)

Mercury

- 1 in 100 people (Conc: 0.05 mg/l) and 10 in 100 people (Conc: 0.5 mg/l) die due to cancer in long-term

High blood pressure, glucosuria, hyperpigmentation, keratoses, cancer

65 million (Asia)Bangladesh, India, China,

Pakistan, Nepal, Myanmar, Vietnam

10 ppb- Geological originArsenic

- In 1999, a union of 1,200 scientists, doctors and lawyers announced their opposition to water fluoridation (USA)

- Dental and skeletal fluorosis, Muscle fibre regeneration, nervous system malfunction

62 million (India)Asia, Mexico, Australia,

Argentina, Africa, New Zealand

- 2 ppm

- Geological origin, mineral weathering, coal mining

Fluoride

- 25 million pounds of TCE were released into the U.S. environment by manufacturing plants in 1995

CCl4: High toxicity to liver and kidney, carcinogenic.TCE: Lung/liver tumor

- ~180 million people in US consume chloraminatedwater

Japan, Central Asia, Arabian Peninsula, Sweden, Poland, Germany, USA, Egypt, China

CCl4: 5 ppbTCE: 5 ppbTTHMs: 80 ppb

Chlorination, effluents, home insecticide

Halogenated organics

Pesticide contamination in soft drinks, the Union Carbide Bhopal tragedy (India)

Cancer, cardiovascular/ reproductive/ neurological disorders, Liver/kidney problems

Poisoning: 28 million agricultural workers in the developing countries. ~18,000 deaths.

US, Kenya, Egypt, India, European Union, Africa, China, Australia

DDT: 1 ppbCarbofuran: 40 ppbSimazine: 4 ppb

- Farming, effluents, home use

Pesticides

RemarksHealth effectsPopulation at riskAffected countriesPermissible

limitsOriginMajor pollutant

Review of major drinking water contaminants, their health impacts and a few associated eventsmultiple sources from internet

Important reasons for use of nanotechnology in drinking water

purification

10

100

50

100

50

50

200

0

50

100

150

200

1950

1960

1970

1980

1990

2000

Year

Concentration (in ppb)

Lead

Arsenic

Membrane preparation

Synthetic lipid bilayer

Calculated non-mediated diffusion

Intact human erythrocyte

D-Glucose

Permeability coefficient (cm.s-1

)

D-Mannitol

2.4 X 10-10

4.4 X 10-11

4 X 10-9

2 X 10-4

3 X 10-9

5 X 10-9

Science, 2001, 2353-57 Nature, 2008, 301-10

Origin of nobility at bulk scale

79Au

Z60 100

<r>

rel/<r>

non-rel, for 6s

1

80

0.95

0.9

0.85

(a) Ni(111) Cu(111) Pt(111) Au(111)

Projected DOS (arb. units)

-10

-50

5

ε(eV) H 1s-d

antibonding

H 1s-d bonding

(b)

Acc. Chem. Res., 1979, 276-81 Nature, 1995, 238-40

Origin of reactivity at nanoscale

400 600 800 10000.0

0.2

0.4

0.6

(a)

(c)

(b)

Intensity (arb. u

nits)

Wavelength (nm)(a) (b) (c) (d)

s

p

UV Visible IR

Abso

rban

ce

Fermi

bands

Metallic

absorption

Inter-band

absorption

Plasmon

Wavelength (nm)

Surface plasmon

absorption

(ii)

(i)

(iii)

(a)

UV Visible IR

Abso

rban

ce

UV Visible IR

Abso

rban

ce

Z(E)

E

D1d(E)

E

nz = 1

nz = 2

nz = 3

nz = 4

D2d(E)

E(b)

(c)

(d)

D0d(E)

E(e)

A

20nm

A

20nm

Gold Bullet. (submitted) Adv. Mat.,2008, 980-83 Langmuir 2008, 4589-99

Phys. Rev. A, 1976, 2287-98

Catal. Today, 2002, 63–78

Origin of re

activity at nanoscale (continued)

J. Phys. Chem., 1993, 5457-71

Nature, 1998, 396, 444–446

Phys. Chem. Chem. Phys., 2007, 725–30

Drinking water purification: Novel reactions at the nano-scale

Chemistry of organic compounds with noble metal nanoparticles

Chem. Mater., 1998, 444-50J. Phys. Chem. B, 1998, 8364-66

Environ. Sci. Techno. 1995, 1511-17


Chemistry of organic compounds with noble metal nanoparticles

(b)

Intensity (arb. u

nits)

a

b

2 Theta (degree)10 30 50 70

Wavelength (nm)1800 1600 1400 1200 1000

12881550

(c)

Intensity (X10

-3)

0

4

8

12

400 600 800 10000.0

0.5

1.0

1.5

Abso

rban

ce

Wavelength (nm)

p

o

ba(a)

A B

Curr. Sci., 2003, 1560-64

Wavenumber (cm-1)

3000 2000 1000

Transm

ittance (a.u.)

a

b

c

400 600 800 10000.0

0.2

0.4

ba

Abso

rban

ce

Wavelength(nm)400 600 800

0.00

0.05

0.10

b-e

a

Abso

rban

ce

Wavelength (nm)

(B)(A)

a

b

c(C)

J. Environ. Monit., 2003, 363–65 J Nanosci Nanotechnol. 2007, 1871-7


Detection of pesticides in drinking water with noble metal nanoparticles

a b c d e fa b c d e fa b c d e fa b c d e f

BB CCa b c

(A)

(B)400 500 600 700 800 900

0.0

0.1

0.2

0.3 f

e

d

c

b

a

Ab

so

rban

ce

Wavelength (nm) Wavelength (nm)400 600 800

Abso

rban

ce

0

0.1

0.2

0.3

a

b

c

de

f

(c)(C)

J. Environ. Health (submitted)


Chemistry of heavy metal ions with noble metal nanoparticles

(A)

Abso

rban

ce

Wavelength (nm)300 400 500 600

(A)

Abso

rban

ce


2θ (degrees)30 50 70 806040

Intensity

a

bc

d

(111) (200) (220) (311)

(311)(220)(200)(111)

(200) (220)(311)

(222)

(400)(331)

(420)

(311)(220)(200)(111)

(111)

(B)

2θ (degrees)30 50 70 806040

Intensity

a

bc

d

(111) (200) (220) (311)

(311)(220)(200)(111)

(200) (220)(311)

(222)

(400)(331)

(420)

(311)(220)(200)(111)

(111)

(B)

J. Colloid Interf. Sci. 2006, 415–18

Ag (s) + H+ + Cl- → AgCl (s) + H2 E°= -0.22 V

The non-reactivity of bulk silver can again be understood from the absence of driving

force for the reaction. However, at the nano-scale, the feasibility of the reaction (i.e. E

> 0) confirms the increasing reducing nature of the silver nanoparticle surface.



200 400 6000.00

0.05

0.10

(viii)(ix)

(ii)

(i)

Wavelength (nm)

Absorban

ce

(a) (b)

Ag → Ag + e- E°oxidation = -0.8 V Hg2+ + 2e-

→ Hg E°reduction = 0.85 V

2Ag + Hg2+→ Hg + 2Ag+ E°= 0.05 V

Chem. Mater., 1998, 444-50

Agn + Cu2+→ Agn-1 + Ag+ + Cu+

followed by similar reaction of Agn-1,Cu+ + Agn+m → Cu2+ + Ag-

n+m

Ag+ + Ag-n+m → Agn+m+1

Chem. Phys. Lett., 1989, 473-76

J. Phys. Chem., 1992, 2411-14



C

20nm


Abso

rban

ce

0

0.2

0.4

0.6A BA Bba

ab

C

20nm


Abso

rban

ce

0

0.2

0.4

0.6A BA Bba

ab

20 nm

(A)

100nm

(B)

(C)

+++++

+

+*

*

b

+

+

(100) (002)

(101)

(102

)

(110)

(103)

(112)(201)(004)

(222)

(111

)

(111)

(200)

(220)

(311

)(222)

a

2θ (degrees)30 50 70 806040

Intensity

+++++

+

+*

*

b

+

+

(100) (002)

(101)

(102

)

(110)

(103)

(112)(201)(004)

(222)

(111

)

(111)

(200)

(220)

(311

)(222)

a

2θ (degrees)30 50 70 806040

Intensity

(D)

Gold Bullet. (submitted)

Chem. Mater., 1998, 444-50


Detection of heavy metal ions with noble metal nanoparticles

Raman Shift (cm-1)300 500 700 900

SERS In

tensity

(a) Ag sputtered filmAg sol (citrate)Ag sol (PVP)CubesCuboctahedraOctahedra

Particle shape

Na 2HSO

4detec

tion (ppb)

0

100

200

2000

(c)

SERS In

tensity

Raman Shift (cm-1)500 600 700 800 900 1000

AsIII + AsV

AsV(d)

Raman Shift (cm-1)300 500 700 900

SERS In

tensity

PVPBTHDTMDA

(b)

Ange

w.

Che

m. In

t. E

d.

2008,

645

6 –

60

Inorg

. C

he

m. 2

008,

47,

293

4-2

936


Chemistry of micro-organisms with noble metal nanoparticles

Concentration of silver (µg)0 40 80 0 40 80

0 40 80 0 40 80log(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 80log(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)

20 nm

(C)a b

c d

a b

c d

a b

c d

a b

c d

(A) AgNO3 Rod

Sphere Triangle

Other nanomaterial based approaches for water purification

Iron-based nanoparticles

Binding energy (eV)859 856 853 850

Counts (X 104)

0

0.6

1.2

1.8

2.4

Ni2+ Ni0

24 hrs

3 hrs

1 hr

15 min

(b) (c)

100 nm

(a)

Carbon nanotubes

0 sec 15 sec 30 sec

45 sec 60 sec 80 sec

Pt wire(a) (b)

Commercial interests in drinking water purificationiw

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

- - -

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