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Sustainable Technology DivisionNational Risk Management Research Laboratory
U. S. Environmental Protection AgencyCincinnati, Ohio 45268, USA
E-mail: Varma.Rajender@epa.gov
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
Nadagouda & Varma: Green Chemistry, 8, 516, (2006)
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
Nadagouda & Varma: Green Chemistry, 8, 516, (2006)
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
Nadagouda & Varma: Crystal Growth and Design, 7, 2582 (2007)
TEM images of metallic (control) noble nanoparticlessynthesized using ascorbic acid (vitamin C) (a) Cu and (b) Fe. Insetshows corresponding SAED pattern image.
Nadagouda & Varma: Crystal Growth and Design, 7, 2582 (2007)
TEM images of Core (Pd)-shell with (a) In, (b) Pt, (c) Cu, and (d) Au core–shell bimetallic nanostructures.
Nadagouda & Varma: Crystal Growth and Design, 7, 2582 (2007)
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.
Nadagouda & Varma: Crystal Growth and Design, 7, 2582 (2007)
TEM images of core (Fe)-shell with (a) Au, (b) SAED of Au, (c) Pd, and (d) Pt core–shell bimetallic nanostructures.
Nadagouda & Varma: Crystal Growth and Design, 7, 2582 (2007)
UV–visible spectra of core (Fe) shell with (a) Au, (b) Pd, and (c) Pt nanostructures synthesized using ascorbic acid.
Nadagouda & Varma: Crystal Growth and Design, 7, 2582 (2007)
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
Nadagouda & Varma: Green Chemistry, 10, 859 (2008)
Pd Nanoparticles Generated from Various Brands of Tea & Coffee
Sanka Bigelow Luzianne
Starbucks Folgers Lipton
Nadagouda & Varma: Green Chemistry, 10, 859 (2008)
TEM images of Ag and Pd nanoparticles prepared in aqueous solution using pure catechin.
Nadagouda & Varma: Green Chemistry, 10, 859 (2008)
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
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80
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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.
Nadagouda, Castle, Murdock, Hussain & Varma: Green Chemistry, 11, in press (2009)
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.
Nadagouda, Castle, Murdock, Hussain & Varma: Green Chemistry, 11, in press (2009)
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.
Nadagouda, Castle, Murdock, Hussain & Varma: Green Chemistry, 11, in press (2009)
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.)
Nadagouda, Castle, Murdock, Hussain & Varma: Green Chemistry, 11, in press (2009)
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
Nadagouda, Hoag, Collins & Varma: Crystal Growth & Design, 9, in press (2009)
SEM Images of Au Nanostructures Synthesized Using Plant Surfactants
Nadagouda, Hoag, Collins & Varma: Crystal Growth & Design, 9, in press (2009)
TEM Images of Au Nanostructures Synthesized Using Plant Surfactants
Nadagouda, Hoag, Collins & Varma: Crystal Growth & Design, 9, in press (2009)
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.
J. Mater. Chem. in press (2009)
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
J. Mater. Chem. in press (2009)
0.0
1.0
2.0
3.0
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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; varma.rajender@epa.gov Dr. George Hoag, Senior Vice President, Director of Research & Development; Phone 860-617-5106; ghoag@verutek.com
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
Nadagouda & Varma: J. Smart Materials and Structures, 15, 1260 (2006)
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
Nadagouda & Varma: J. Smart Materials and Structures, 15, 1260 (2006)
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
Nadagouda & Varma: J. Smart Materials and Structures, 15, 1260 (2006)
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
Nadagouda & Varma: Crystal Growth and Design, 7, 686 (2007)
Gold Nanostructures
TEM image of (a-d) gold nanostructures obtained using low concentration of sugar solution under microwave irradiation
Nadagouda & Varma: Crystal Growth and Design, 7, 686 (2007)
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
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
Schematic of experimental mechanisms that generate: Silver (a) Nanoparticles, (b) Nanorods, and (c) Nucleated Nanorods and Nanoparticles.
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
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).
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
(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.
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
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).
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
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
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
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
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
(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.
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
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).
Nadagouda & Varma: Crystal Growth and Design, 8, 291-295 (2008)
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
Nadagouda & Varma: Green Chemistry, 9, 632-637, (2007)
Polypyrrole Nanocomposites
Pd Pt
Au Ag
Nadagouda & Varma: Green Chemistry, 9, 632-637, (2007)
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)
Nadagouda & Varma: Macromol. Rapid Commun., 28, 842–847 (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.
Nadagouda & Varma: Macromol. Rapid Commun., 28, 842–847 (2007)
SEM images of (a-b) 75 mg SWNT cross-linked PVA nanocomposites
Nadagouda & Varma: Macromol. Rapid Commun., 28, 842–847 (2007)
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
Nadagouda & Varma: Biomacromolecules, 8, 2762-2767 (2007)
UV spectra of CMC-reduced (a) Au, (b) Pt, and (c) Pd synthesized using MW irradiation for 5 min at 100 °C.
Nadagouda & Varma: Biomacromolecules, 8, 2762-2767 (2007)
TEM images of CMC-reduced (a) Au and (b) Pd, and SAED pattern of (c) Au and (d) Pd nanostructures.
Nadagouda & Varma: Biomacromolecules, 8, 2762-2767 (2007)
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
Nadagouda & Varma: Macromol. Rapid Commun., 28, 155-159 (2007)
C-60 dispersion in CMC and coating of platinum nanoparticles on the surface
Dispersion of C-60 nanotubes in carboxymethyl cellulose (CMC) and decoration with noble metals under MW irradiation conditions
Nadagouda & Varma: Macromol. Rapid Commun., 28, 155-159 (2007)
C-60 dispersion in CMC and coating of gold nanoparticles on the surface
Dispersion of C-60 nanotubes in carboxymethyl cellulose (CMC) and decoration with noble metals under MW irradiation conditions
Nadagouda & Varma: Macromol. Rapid Commun., 28, 155-159 (2007)
C-60 dispersion in CMC and coating of palladium nanoparticles on the surface
Dispersion of C-60 nanotubes in carboxymethyl cellulose (CMC) and decoration with noble metals under MW irradiation conditions
Nadagouda & Varma: Macromol. Rapid Commun., 28, 155-159 (2007)
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
Baruwati, Varma, ChemSusChem, 2, in press (2009)
Gold Nanoparticles Using Red Grape Pomace
MW 50 W for 1 Minute Room Temp. for 3 hours
Baruwati, Varma, ChemSusChem, 2, in press (2009)
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 azrefi@astrazeneca.com
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