Green Tech Ct- 09-Varma-pm_red

Sustainable Technology DivisionNational Risk Management Research Laboratory

U. S. Environmental Protection AgencyCincinnati, Ohio 45268, USA

E-mail: [email protected]

Sustainable Synthesis of Nanomaterials for Environmental

Remediation

M. N. Nadagouda & Rajender S. Varma

Clean Chemical Synthesis Using Alternative Reaction Methods

Alternative Energy Sources★ Microwave ★ Ultrasound ★ Sunlight / UV

Alternative Reaction Media/Solvent-free★ Supercritical Fluids★ Ionic Liquids★Water ★ Polyethylene glycol (PEG)★ Solvent-free

Minimum Chemical Waste

BenignSolvents

EnergyEfficiency

SaferCatalysts

& Reagents

SustainableSyntheticMethod

Efficient IsolationProcesses

AtomEconomy

RenewableFeedstock

GreenOrganic

Chemistry

Microwave Assisted Green Chemistry in Aqueous Medium

Schematic model diagram of nanoparticle self-assembly in different solvents in the presence of vitamin B2

Nadagouda & Varma: Green Chemistry, 8, 516, (2006)

TEM image of Ag and Pd nanoparticles synthesized using vitamin B2.

Inset shows corresponding particle size distribution, electron diffraction andUV excitation


Reaction of vitamin B2 with silver nitrate over the time in aqueousmedia. The inset figure shows control vitamin B2 (from left), reducedsilver nanoparticles in water and NMP solvent media after 60 minutes


Aligned Pd nanoplates synthesized using vitamin B1 in water

Nadagouda, Polshettiwar & Varma: J. Mat. Chem., 19, 2026 (2009)

(a-b) Pd nanoplates and

(c-d) Pd-catalyzed polypyrrole & polyaniline

Aligned platinum nanoflowers synthesized using vitamin B1in aqueous media

Nadagouda, Polshettiwar & Varma: J. Mat. Chem., 19, 2026 (2009)

A Greener Synthesis of Core (Fe, Cu)-Shell (Au, Pt, Pd, and Ag) Nanocrystals Using Aqueous Vitamin C

Nadagouda & Varma: Crystal Growth and Design, 7, 2582-2587 (2007)

Photographic images of ascorbic acid reduced metallic nanostructures of (a) Ag, (b) Au, (c) Pd, (d) Pt, and (e) Cu.

Nadagouda & Varma: Crystal Growth and Design, 7, 2582 (2007)

TEM images of metallic (control) noble nanoparticles synthesized using ascorbic acid (vitamin C)

(a) Ag, (b) Pd, (c) Au, and (d) Pt


TEM images of metallic (control) noble nanoparticlessynthesized using ascorbic acid (vitamin C) (a) Cu and (b) Fe. Insetshows corresponding SAED pattern image.


TEM images of Core (Pd)-shell with (a) In, (b) Pt, (c) Cu, and (d) Au core–shell bimetallic nanostructures.


TEM images of core (Cu)-shell with (a) Pt, (b) Au, (c) Pd, and (d) selected area electron diffraction pattern of Cu-Pd core–shell nanoparticles.


TEM images of core (Fe)-shell with (a) Au, (b) SAED of Au, (c) Pd, and (d) Pt core–shell bimetallic nanostructures.


UV–visible spectra of core (Fe) shell with (a) Au, (b) Pd, and (c) Pt nanostructures synthesized using ascorbic acid.


Green synthesis of Ag and Pd nanoparticles at room temperature using coffee and tea extract

Ag nanoparticles

Pd nanoparticles

Nadagouda & Varma: Green Chemistry, 10, 859 (2008)

Bigelow Folgers Lipton

Luzianne Sanka Starbucks

Ag Nanoparticles Generated from Various Brands of Tea & Coffee


Pd Nanoparticles Generated from Various Brands of Tea & Coffee

Sanka Bigelow Luzianne

Starbucks Folgers Lipton


TEM images of Ag and Pd nanoparticles prepared in aqueous solution using pure catechin.


NRMRL/WSWRD-Aquatic Toxicity of Inorganic Nanoparticles-Silver

Coated Ag Nanoparticles ppb

Mor

talit

y

0.0

0.2

0.4

0.6

0.8

1.0

0.05 0.5 5 50

EC 10 = 7.07 +/- 1.33

EC 25 = 8.94 +/- 1.21

EC 50 = 11.31 +/- 1.04

Assay: DmagnaAcute 48HrNoFood3-2007_05_09.aToxicant: Coated Ag NanoparticlesDose Response Curve

UnCoated Ag Nanoparticles ppb

Mor

talit

y

0.0

0.2

0.4

0.6

0.8

1.0

0.5 1 2 5 10 20

EC 10 = 0.88 +/- 0.08

EC 25 = 0.94 +/- 0.06

EC 50 = 1.01 +/- 0.06

Assay: DmagnaAcute 48HrNoFood5-2007_07_16Toxicant: UnCoated Ag NanoparticlesDose Response Curve

Daphnia magna-48 hour exposure to commercially available nanoparticles

Coated Ag particle LC50=11.31±1.04µg/LUncoated particle LC50=1.01±0.06µg/L

These LC50 values are similar to those for ionic silver

Current studies emphasize:

Characterization of the Ag nanoparticles (collaboration with LRPCD and Argonne Nat’l Lab)

Identification of Ag species which cause toxic effects

Standard laboratory protocols for the analyses of nanoparticles in controlled aquatic systems

(Collaboration with NERL researchers on genotoxic effects of inorganic nanoparticles)

Toxicity of lab-synthesized Ag nanoparticles (Collaboration with Sustainable Technology Division)

(Uncoated Silver)

50ug/ml dose

0

20

40

60

80

100

120

140

160

1

% C

ontro

l

Control3.8nm and 25.9nm49.8nm6nm and 77nm9.2nm and 59.0nm47.0nm

100ug/ml Dose

020406080

100120140160180

1

% C

ontro

l

Control3.8nm and 25.9nm49.8nm6nm and 77nm9.2nm and 59.0nm47.0nm

*MTS measures mitochondrial function

0

20

40

60

80

100

120

0 10 25 50

Dose (µg/ml)

MTT

Red

uctio

n (

% o

f con

trol

)

Ag15Ag25Ag80

Toxicity of Silver NP in Mouse Keratinocytes: MTS Assay Viability

(Silver with Tea Extract)

Collaboration with Dr. Saber HussainAir Force Research LaboratoryDayton, Ohio

UV spectra of (a) Fe, (b) tea extract and (c) reaction product of Fe(NO3)3and tea extract. Inset shows the photographic image of the reaction.

Nadagouda, Castle, Murdock, Hussain & Varma: Green Chemistry, 11, in press (2009)

Representative XRD pattern of iron nanoparticles synthesized using tea extract

24h MTS results

• No significant decreases in cell proliferation after a 24h exposure to NZVI (Figure A.)

• No significant reductions in cell proliferation after a 24h exposure to control particles (Figure B.)

A.

B.


48h MTS results

• No significant decreases in cell proliferation after a 48h exposure to NZVI (Figure A.)

• No significant reductions in cell proliferation after a 48h exposure to control particles (Figure B.)

A.

B.


24h LDH results

• Some slight increases in LDH leakage in the T2 particles at 50µl/ml concentration after a24h exposure to NZVI ,but this could be due to size or the increases conc. (Figure A.)

• No significant changes in LDH leakage after a 24h exposure to control particles (Figure B.)

A.

B.


A.

B.

48h LDH results

• Increases in LDH leakage in the T6 and T7 particles at exposure to NZVI ,but this could be due to the large size of the particles or the increased concentration (Figure A.)

• No significant changes in LDH leakage after a 48h exposure to control particles (Figure B.)


Remediation using Nanomaterials Synthesized Under Green Conditions

• New CRADA with VeruTEK Technologies, Inc.

• VeruTEK’s focus is to develop sustainable and green remediation, water and waste treatment processes

• VeruTEK’s core uses food grade cosolvents and surfactants from citrus and plant extracts to simultaneously solubilize LNAPLs and DNAPLs and destroy with free radical chemistries (S-ISCOTM Process)

• CRADA involves advancing green synthesis manufacture of nanomaterials for application to remediation, water and waste treatment and biological and chemical agent treatment

Formation of Nanoscale Zero Valent IronGreen Tea Extract with Ferric Nitrate

Formation of Nanoscale Zero Valent IronGreen Tea Extract with Ferric Chloride

nZVIFormed

nZVIFormed

Manufacture of Nanoscale Zerovalent Iron Particles with Ferric Chloride and Ferric Nitrate using Green Tea

Notes: Green Tea extract made by heating a 20 g/L solution of Dry Chumnee Tea for 20 minutes at 90oC then filtering with paper filter. Green Tea extract added to 0.1 M Ferric solutions on a 1:2 (v/v) basis.

In Situ Formation of Nanoparticle Zerovalent Iron in Soils with Lemon Balm Extract and Fe(NO3)3

nZVI Formation in Soil Column Control

Column

Lemon Balm Extract

Feed Pump

Fe(NO3)3Feed Pump

In Situ Generated Nanoparticle Zerovalent Iron in Effluent of Soil Column

100 nm

Zerovalent Iron Nanoparticles Synthesized using Green Tea with 0.1 M Ferric Chloride and 0 g/L VeruSOLTM-3

100 nm

Zerovalent Iron Nanoparticles Synthesized using Green Teawith 0.1 M Fe(III)-EDTA and 5 g/L VeruSOLTM-3

Green Synthesis of Au Nanostructures at Room Temperature using Biodegradable Plant Surfactants

Representative photographic images of Au Nanostructures

Nadagouda, Hoag, Collins & Varma: Crystal Growth & Design, 9, in press (2009)

XRD pattern of Au nanostructures obtained using various surfactants


SEM Images of Au Nanostructures Synthesized Using Plant Surfactants


TEM Images of Au Nanostructures Synthesized Using Plant Surfactants


UV-Vis Spectra (Absorbance v Wavelength) of bromothymol blue in the absence of a catalystNotes: 1) No Reaction of uncatalyzed hydrogen peroxide (2%) with bromothymol blue. Initial bromothymol blue concn. was 500 mg/L in the acidic pH range (<6).

J. Mater. Chem. in press (2009)

UV-Vis Spectra (Absorbance v Wavelength) of bromothymol blue over time for an initial solution containing 500 ppm bromothymol blue (pH 6), 2% H2O2, and 0.06 mM GT-nZVI.


y = -0.5182x + 5.9788R² = 0.9998

y = -0.2712x + 6.0927R² = 0.9988

y = -0.0449x + 6.2459R² = 0.9938

y = -0.1448x + 6.3966R² = 0.9925

4

4.5

5

5.5

6

6.5

7

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0

ln[B

TB]

Time (min)

Bromothymol Blue Degradation with 2% HP, GT-nZVI and GT-nZVI + 0.02M PdCl2

ln[BTB] vs TimeE1 - 0.33mM GT-nZVI + 0.02M PdCl2E2 - 0.12mM GT-nZVI + 0.02M PdCl2A3 - 0.12mM GT-nZVI

A4 - 0.33mM GT-nZVI


0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 5 10 15 20 25 30

Hydr

ogen

Per

oxid

e (%

)

Time (hour)

(a)

(b)

(c)

(d)(e)

Decomposition of H2O2 catalyzed with green-tea synthesized zero valent iron (GT-nZVI). (a) 5% peroxide solution control, (b) 5% peroxide treated with 0.26mM (as Fe)GT-nZVI, (c) 5% peroxide treated with 0.53mM (as Fe) GT-nZVI, (d) 5% peroxidetreated with 1.33mM (as Fe) GT-nZVI, (e) 5% peroxide treated with 2.66mM (as Fe)GT-nZVI.

Decomposition of hydrogen peroxide using green tea synthesized nano-scale zero valent iron catalysts

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0 5 10 15 20 25 30

(a)

(b)(c)(d)(e)

(f)

Concentration of HP (%) vs Time with GT-nZVI at 1.33 mM as Fe (a) Control 1 – 5%H2O2 (no GT-nZVI) (b) 10 g/L VeruSOL-3™, (c) 5 g/L VeruSOL-3™, (d) 2 g/LVeruSOL-3™, (e) 1 g/L VeruSOL-3™, and (f) Control 2 – 5% peroxide with GT-nZVI at1.33 mM as Fe (no VeruSOL-3™)

Problem: There are over 500,000 contaminated sites across the United States. Current cleanup technology requires excavation and may even generate toxic by-products. Remediating or destroying various organic and inorganic environmental toxins in the subsurface and in water at or around these sites is a complex challenge.

Description: EPA’s world-renown scientists in Cincinnati are trained and educated to develop innovative cleanup strategies that restore contaminated sites to productive use, reduce associated costs, and promote environmental stewardship. Through a Cooperative Research and Development Agreement (CRADA) between EPA’s National Risk Management Research Laboratory (NRMRL) and the private company VeruTEK in Bloomfield, Connecticut, EPA green-synthesis technology is being used to further improve VeruTEK’s green remediation and treatment technologies used in environmental cleanup. This project combines EPA’s expertise in green synthesis of nanoparticles with VeruTEK’s expertise with surfactant enhanced in situ chemical oxidation and reduction methods. As a result, new environmentally-friendly applications and methods have been developed. The anticipated benefits from the new green-synthesis methods over conventionally used processes are: only natural materials are used; no hazardous waste is produced; reduced processing is required; materials are more stable, easily stored, and transported; and, materials can be more easily produced around the world.

Impact: The Cooperative Research and Development Agreement between the EPAand VeruTEK will provide:-Production of nanoiron using various plant extracts and iron sources-Catalytic activation of hydrogen peroxide-Destruction of contaminated soils

IP Position: VeruTEK filed a provisional U.S. Patent with co-inventors from theEPA in 2008. The project covers the method of synthesis of metal nanoparticles using plant extracts and their application as catalysts for oxidation reactions, and also as reductants to treat organic and inorganic chemicals.

Technology Status: The CRADA reinforces the collaboration between the EPA and VeruTEK and will greatly enhance how nanoscale technologies are applied for site remediation. It is anticipated that using the new greener synthetic pathways, the cost of nanoscale iron and other nanoscale metals will be reduced, along with the elimination of toxic byproducts often generated in the conventional process. While the green-synthesis process is new, it is expected that it will be used in the field in 2009.

Use of Green Methods and Applications to Destroy ToxicOrganics and Inorganic Compounds in the Environment

Dr. Rajender S. Varma, National Risk Management Research Laboratory; Phone 513-487-2701; [email protected] Dr. George Hoag, Senior Vice President, Director of Research & Development; Phone 860-617-5106; [email protected]

The EPA’s National Risk Management Research Laboratory and its partners are developing new environmental technologies that provide unique opportunities for green job creation and enhanced protection of human health and the environment.

MW Heating Mechanism

+-

+ + + + + + + +

_ _ _ _ _ _ _ _+-

~

~ ~

~ ~

~

Noconstraint Continuouselectric field Alternatingelectric fieldwithhighfrequency

Two mechanisms: Dipolar rotation / polarization Ionic Conduction mechanism

Microwave Dielectric Heating Mechanisms

Dipolar Polarization Mechanism

Dipolar molecules try to align to an oscillating field by rotation

Conduction Mechanism

Ions in solution will move by the applied electric field

Dextron Templated Microwave-Assisted Synthesis

of Porous Titanium DioxideThe synthesis of carbon coated titania as well as spongy kind of titania by microwave combustion method

The process is very simple and eco-friendly protocol which utilizes renewable polymer dextrose to create spongy kind of materials.

Nadagouda & Varma: J. Smart Materials and Structures, 15, 1260 (2006)

Objective

An alternative route to the preparation and formationof porous titania powders and carbon coated titaniausing microwave irradiation

Dextrose was used as a capping agent or atemplate for the following reasons:

High water solubility when compared to other sugar templates or capping agents

Combustible material at low temperature Inexpensive material


SEM images of TiO2 synthesized using (a-c) 1:1, 1:3 and 1:5 (titania:dextrose) by conventional heating furnace, (d) EDX spectra

SEM images of TiO2 synthesized using (a-c) 1:1, 1:3 and 1:5 (titania:dextrose) by MW initiated combustion, (d) EDX spectra

(a-c) X-ray mapping images of 1:1, 1:3 and 1:5 (titania: dextrose molar ratio) carbon coated titania synthesized using MW combustion synthesis.

Green region shows titania and red region shows carbon


SEM images of ZrO2 synthesized using:

(a) MW-initiated followed by conventional heat treatment at 850 0C for 1 h and(b) Only conventional heating furnace at 850 0C for 1 h


Microwave-Assisted Reactions Using Sugar Solutions

Noble Nanostructures

Noble salt (0.1 M) SugarMW

30-40 sec

Examples : Sucrose, Maltose, glucose etc.

Nadagouda & Varma: International Microwave Power Institute Symposium Proceedings, Boston, pp 217-219 (2006).

TEM image of gold nanostructures obtained using high concentration of sugars under microwave irradiation condition

(a) Glucose, (b) Maltose and (c) Sucrose


Gold Nanostructures

TEM image of (a-d) gold nanostructures obtained using low concentration of sugar solution under microwave irradiation


Comparison of Microwave and Oil Bath Heating Methods

• Fast reaction rate (30-40 sec)

• Uniform size and shape

• Less energy consumption

• Slow reaction rate (minimum 2 h)

• Particle size growth

• More energy consumption

MW Method Oil Bath Method

Bulk Synthesis of Silver Nanorodsin Poly(ethylene glycol)

using Microwave Irradiation


Schematic of experimental mechanisms that generate: Silver (a) Nanoparticles, (b) Nanorods, and (c) Nucleated Nanorods and Nanoparticles.


SEM image of Ag nanoparticles prepared via MW methodUsing (a) PG-6 (6 mL PEG + 2 mL AgNO3), and

(b) PG-1 (1 mL PEG + 7 mL AgNO3).


(A)

(B)

(A) UV spectra of (a) PG-8, (b) PG-4 and (c) PG-1, and (B) SEM image of mixture of Ag nanorods and particles prepared from PG-4 for 2 minutes under MW irradiation.


SEM image of Ag nanorods prepared via MW irradiation for one hour using PG-9 composition

(4 mL of PEG + 3 mL of AgNO3 + 1 mL of HAuCl4).


SEM image of Ag-Pd composite (PG-10, 4 mL of PEG with 3 mL of AgNO3 and 1 mL of PdCl2)prepared using MW irradiation at 100 0C for 1h


Bulk Synthesis of Silver Nanorods in Poly(ethylene glycol) using Microwave Irradiation

SEM images of silver nanorods synthesized via MW irradiation using (a) 4/4, (b) 5/3 , (c) 3/5 and (d) 2/6 PEG:AgNO3 volume (mL) ratio


(a) Precipitated silver nanorods under MW irradiation for 2 min using PEGand

(b) Control reaction of the same reaction compositionusing oil bath at 100 0C for 1 hr.


TEM images of Ag nanorodsfrom (a) 4 mL PEG with 4mL of aqueous AgNO3under MW conditions and(b) its SAED patternobtained from a bundle ofsilver nanorods randomlydeposited on the TEM grid.

TEM image of Pt nanocubes decorated on Ag nanorods by metal displacement reaction using PG-11 composition (PG-4 Nanorods + 4 mL of Na2PtCl6 XH2O).


SEM images of Fe nanorods obtained from PG-12 composition (4 mL of PEG + 4 mL Fe(NO3)3 XH2O) under MW conditions;

inset shows SAED pattern.

Noble Metal Polymer Nanocomposites

Polymer nanocomposites are the class ofreinforced polymers with low quantities ofnanometric-sized metal nanoparticles.

Applications:

- fire resistance and strength

- coating materials in automobile

- improved barrier properties

- civil and electrical engineering

- Packaging etc.

SEM image of polyaniline synthesized using (a-b, low and highmagnification) 3M, (c) 1M and (d) 1M acetic acid (TEM image)

Nadagouda & Varma: Green Chemistry, 9, 632-637, (2007)

TEM images of different shape noble metal-polyaniline nanocomposites obtained from polyaniline nanofibers (synthesized using 1M acetic acid):

(a) Ag, (b) Pd, (c) Au and (d) Pt Nanocomposites.(b) Inset shows corresponding electron diffraction patterns


Polypyrrole Nanocomposites

Pd Pt

Au Ag


Preparation of Novel Metallic, Bimetallic and Carbon Nanotube Cross-Linked Poly(vinyl alcohol)

Nanocomposites under Microwave Irradiation

Poly (vinyl alcohol)-reduced metals: (a–b) Ag after 1 and 5 h reaction,(c–d) Pd and Fe after 1 h reaction time at 100 0C (maximum pressure ~280 Psi)

Nadagouda & Varma: Macromol. Rapid Commun., 28, 842 (2007)

Cross-linked poly (vinyl alcohol)- with various metallic and bimetallic systems: (a) Pt, (b) Pt-In, (c) Ag-Pt, (d) Cu, (e) Pt-Fe, (f) Pt with higher concentration ratio, (g) Cu-Pd, (h) In, (i) Pt-Pd and (j) Pd-Fe.

Nadagouda & Varma: Macromol. Rapid Commun., 28, 465 (2007)

Novel Metallic, Bimetallic Cross-Linked Poly(vinyl alcohol) Nanocomposites under Microwave Irradiation Conditions

SEM image of bimetallic (a) Pt-In, (b) Pt-Fe, and (d) Pd-Fe in 3 wt.-% PVA matrix. (c) X-ray-mapping image of Pt-Pd in 3 wt.-% PVA matrix. Inset in (a) shows X-ray mapping of In-Pt (green: In, red: Pt).

Nadagouda & Varma: Macromol. Rapid Commun., 28, 465–472 (2007)


SEM images of (a) pure SWNT carbon nanotubes, (b-c) 25 mg SWNT cross-linked PVA and (d) 50 mg SWNT cross-linked PVA nanocomposites.


SEM images of (a-b) 75 mg SWNT cross-linked PVA nanocomposites


PVA coating

TEM images of (a) pure SWNT carbon nanotubes obtained from Bucky Inc., USA, (b) 25 (c) 50, (d) 75 mg SWNT cross-linked PVA nanocomposites.

Synthesis of Thermally Stable CarboxymethylCellulose/Metal Biodegradable Nanocomposite

Films for Potential Biological Applications

(a) (b) (c) (d)

Carboxymethyl cellulose nanocomposites with(a) Cu, (b) In, (c) Fe and (d) Ag

Nadagouda & Varma: Biomacromolecules, 8, 2762-2767 (2007)

Carboxymethyl cellulose (CMC) reduced Au, Pt and Pd(from left to right) synthesized using MW at 100 0C for 5 minutes


UV spectra of CMC-reduced (a) Au, (b) Pt, and (c) Pd synthesized using MW irradiation for 5 min at 100 °C.


TEM images of CMC-reduced (a) Au and (b) Pd, and SAED pattern of (c) Au and (d) Pd nanostructures.


SEM image of CMC nanocomposite films with (a) Cu, (b) In, (c) Feand (d) Ag. Red spotted area corresponds to metal and greenarea represents carbon. Inset corresponds to their respectiveenergy dispersive X-ray analysis (EDX).

Noble Metal Decoration and Alignment of Carbon Nanotubes in Carboxymethyl Cellulose

X-ray mapping image of Ag metal decorated CMC SWNT at room temperature.

Nadagouda & Varma: Macromol. Rapid Commun., 28, 155-159 (2007)

Dispersion of C-60 nanotubes in carboxymethyl cellulose (CMC) and decoration with noble metals under MW irradiation conditions

Control : Pure CNT nanotubes


C-60 dispersion in CMC and coating of platinum nanoparticles on the surface



C-60 dispersion in CMC and coating of gold nanoparticles on the surface



C-60 dispersion in CMC and coating of palladium nanoparticles on the surface



Synthesis of Single-Crystal Micro-Pine Structured Nano-Ferrites and Their Application in Catalysis

Polshettiwar, Nadagouda & Varma, Chem. Commun. 2008, 6318

3D Nano-Metal Oxides MW Synthesis in Water from Simple Salts

Polshettiwar, Baruwati & Varma, ACS Nano, 3, 728 (2009)

Fe2O3

CoO

Mn2O3

Cr2O3

Synthesis of Monodispersed Ferrite Nanoparticles at Water-Organic Interface

Under Conventional/MW Hydrothermal Conditions

Monodispersed MFe2O4 (M=Fe, Mn, Co, Ni) nanoparticles have beensynthesized via a water organic interface under both hydrothermal and MWconditions starting with readily available and inexpensive metal nitrate andhalide precursors. The single phase particles are obtained at a temperatureas low as 150 oC under MW conditions. The as-synthesized particles aredispersible in nonpolar organic solvents.

NiFe2O4 CoFe2O4 γ-Fe2O3

Baruwati, Nadagouda & Varma, J. Phys. Chem. C, 112, 18399 (2008)

Surface functionalization renders the particles dispersible in water

TEM of the particlesdispersed in water

Photographic image of theparticles in water and hexane

NiFe2O4CoFe2O4

Baruwati, Nadagouda & Varma, J. Phys. Chem. C, 112, 18399 (2008)

Nano-Catalyst, What is it?We envisioned a catalyst system,

“which can bridge the Homogenous and Heterogeneous system”

Also Keeping in mind;1. It should be cheaper2. Easily accessible (sustainable)3. No need of catalyst filtration

Synthesis of Nano-Catalysts

NH2HO

HO Sonication

RT, H2O

=O

O

Metal (M)

NH2

NH2

NH2

NH2

H2N

H2NH2N

H2N

H2N

H2NH2N NH2

NH2

NH2

NH2

NH2

H2N NH2

NH2

NH2

NH2

NH2

H2N

H2NH2N

H2N

H2N

H2NH2N NH2

NH2

NH2

NH2

NH2

H2N NH2

MM

M

M

M

M

MM

M

M

M

M

Magnetic Nanoparticles

Fe3O4 Fe3O4

Fe3O4

V. Polshettiwar, M. N. Nadaguda & R. S. Varma, Chem. Commun. 2008, 6318.

Magnetically Recoverable Pd Nano-Catalyst for Oxidation

Polshettiwar & Varma, Org. Biomol. Chem., 7, 37 (2009)

Magnetically Recoverable Ruthenium Hydroxide Nano-Catalyst

Polshettiwar & Varma, Chem. Eur. J. 15, 1582 (2009)

No Organic Solvent-Even in the Work-Up Step

Reaction in Pure Aqueous Medium

Synthesis of Ni-Nano-Catalysts

Single-phase Fe3O4 nanoparticles Size range = 10-13 nm Nickel concentration = 8.3 % (ICP-AES)

NiCl2,NH2NH2

NH2

NH2

NH2

NH2

H2N

H2NH2N

H2N

H2N

H2NH2N NH2

NH2

NH2

NH2

NH2

H2N NH2

NH2

NH2

NH2

NH2

H2N

H2NH2N

H2N

H2N

H2NH2N NH2

NH2

NH2

NH2

NH2

H2N NH2

NiNi

Ni

Ni

Ni

NiNiNi

Ni

Ni

Ni

Ni

Fe3O4

Fe3O4

Magnetically Recoverable Ni Nano-Catalyst for Reduction

Polshettiwar, Baruwati & Varma, Green Chem., 11, 127 (2009)

Glutathione as a Reducing and Capping agent for the Synthesis of Metal Nanoparticles

O

HN

HO O

HN

H2NOH

O

O

HSGlutathione reduced

An ubiquitous tripeptide and antioxidant present in human and plant cells

Presence of a highly reactive thiol group that can be used to reduce the metal salts

Completely benign nature

Choice of Glutathione because …

Baruwati, Polshettiwar, Varma, Green Chem. 11, p 926 (2009)

Metal nanoparticles in less than a minuteunder MW conditions

Optimized condition 50 W power level

45-60 seconds exposure time

1:0.15 silver nitrate to glutathione mole ratio

Silver Nanoparticles

50 Watt, 60 seconds withsilver nitrate to glutathionemole ratio 1.0:0.15

100 Watt, 60 seconds withmole ratio 1.0:0.15

75 Watt, 60 seconds withmole ratio 1.0:0.15

Baruwati, Polshettiwar, Varma, Green Chem. 11, p 926 (2009)

Silver trees formed on the TEM grid when silver nitrate is not fully reduced

Formation of dendritic structures are due to the carbon and copper in the TEM grid

Gold, Platinum and Palladium Nanoparticles

Silver trees: Dendritic nanostructures

Gold Platinum Palladium

Pd Nanostructures (green) Ag Nanostructures from Sorghum

X-Ray Mapping Images of Various Nanostructures Obtained Using Sorghum Bran

Ag Nanoparticles from Sorghum Bran

Au Nanowires from Sorghum Bran

XRD Pattern of Au Nanostructures from Sorghum Bran

XRD Pattern of Ag Nanostructures from Sorghum Bran

Baruwati, Varma, ChemSusChem, 2, in press (2009)

Gold Nanoparticles Using Wine

Red Wine White Wine


Gold Nanoparticles Using Red Grape Pomace

MW 50 W for 1 Minute Room Temp. for 3 hours


Acknowledgements

Green Chemistry and Engineering, Sustainable Technology Division, NRMRL, U.S. EPA, Cincinnati, Ohio, USA

CRADA with VeruTEK Technologies, Inc.

CRADA with CEM Corporation.

Dr. George Hoag (VeruTEK, CT)Dr. Saber Hussain (WPAFB, Dayton, OH)

Dr. Babita Baruwati Dr. Vivek PolshettiwarDr. Dalip Kumar Dr. Mallikarjuna NadagoudaDr. Harshadas Meshram Dr. Sudhir KumarDr. Vasu Namboodiri Dr. Unnikrishnan R. PillaiDr. Yuhong Ju Dr. Yong-Jin Kim

Dr. Raj Varma with Mrs. Patil,The President of India & Dr. Shekhawat in Rashtrapati Bhawan, Delhi, Feb. 2008

Dr. Varma Presenting Green Chemical Approaches to Mrs. Patil, the President of

India in Rashtrapati Bhawan, Delhi, Feb. 2008

Dr. Varma Presenting ‘Green Nano’ Concepts to Mrs. Patil, the President of India in Rashtrapati Bhawan, Delhi, Feb. 2008

Rajender S. Varma, Microwave Technology -Chemical Synthesis Applications2003 John Wiley & Sons, Inc

Astra Zeneca Research Foundation Kavitha Printers, Bangalore, India, 2002 [email protected]

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