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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Table of Contents
Introduction v
Executive Summary 1
Agenda 9
Participants List 13
Section 1. Sensors 19
Abstract: Nanosensors for Detection of Aquatic Toxins 21
Robert E. Gawley
Environmental Benefits: Nanosensors for Detection of Aquatic Toxins 22
Robert E. Gawley
Abstract: Real-Time Chemical Composition Measurements of Fine and Ultrafine Airborne Particles 23
Murray V. Johnston
Environmental Benefits: Real-Time Chemical Composition Measurements of Fine
and Ultrafine Airborne Particles 24
Murray V.Johnston
Abstract: Ultrasensitive Pathogen Quantification in Drinking Water Using Highly
Piezoelectric PMN-PT Microcantilevers 26
Wan Y. Shih, W.-H. Shih, R. Mutharasan, Y. Lee
Environmental Benefits: Ulrasensitive Pathogen Quantification in Drinking Water Using Highly
Piezoelectric PMN-PT Microcantilevers 27
Wan Y. Shih, W.-H. Shih, R. Mutharasan, Y. Lee
Abstract: ANanocontact Sensor for Heavy Metal Ion Detection 28
Nongjian Tao
Environmental Benefits: A Nanocontact Sensor for Heavy Metal Ion Detection 29
Nongjian Tao
Abstract: Nanostructured Porous Silicon and Luminescent Polysiloles as Chemical Sensors
for Carcinogenic Chromium(VI) and Arsenic(V) 30
William C. Trogler, Michael J. Sailor
Environmental Benefits: Nanostructured Porous Silicon and Luminescent Polysiloles as Chemical
Sensors for Carcinogenic Chromiuni(Vl) and Arsenic(V) 31
William. C. Trogler
Section 2. Treatment 33
Abstract: Nanoscale Biopolymers With Tunable Properties for Improved Decontamination
and Recycling of Heavy Metals 35
Wilfred Chen, Ashok Mulchandani, Mark Matsumoto
Environmental Benefits: Nanoscale Biopolymers With Tunable Properties for Improved
Decontamination and Recycling of Heavy Metals 36
Wilfred Chen
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Abstract: Synthesis, Characterization and Catalytic Studies of Transition Metal Carbide
Nanoparticlcs as Environmental Nanocatalysts 37
S. Ismat Shah, 3. G Chen
Environmental Benefits: Synthesis Characterization and Catalytic Studies of Transition Metal
Carbides Nanoparticles as Environmental Nanocatalysts 38
S. Ismat Shah, 3. G. Chen
Abstract: Simultaneous Environmental Monitoring and Purification
Through Smart Particles 39
Wolfgang M. Sigmund, Chang-Ju Wu, David Mazyck
Environmental Benefits: Simultaneous Environmental Monitoring and Purification
Through Smart Particles 40
Wolfgang M. Sigmund, Chang-Yu Wu, David Mazyck
Section 3. Remediation 41
Abstract: Membrane-Based Nanostructured Metals for Reductive Degradation of
Hazardous Organics at Room Temperature 43
Dibakar Bhattacharyya, I.eonidas G. Bachas, Stephen M. C. Ritchie
Environmental Benefits: Membrane-Based Nanostructured Metals for Reductive Degradation
of Hazardous Organics at Room Temperature 44
Dibakar Bhattacharyya
Abstract: Dendritic Nanoscale Chelating Agents: Synthesis, Characterization, Molecular
Modeling and Environmental Applications 45
Mamadou S. Diatto. Lqjos Balogh, William A. Goddardlll, James ff. Johnson, Jr.
Environmental Benefits: Dendritic Nanoscale Chelating Agents: Synthesis, Characterization, Molecular
Modeling and Environmental Applications 46
Mamadou S. Diallo, Lajos Balogh, William A. Goddard III, James H. Johnson, Jr.
Abstract: Photochemical Reactivity of Ferritin for Cr(VI) Reduction 48
Daniel R. Strongin, Ivan Kim, Hazel-Ann Hosein, Trevor Douglas, Martin A. A. Schoonen
Environmental Benefits: Photochemical Reactivity of Ferritin for Cr(VI) Reduction 49
Daniel R. Strongin
Abstract: Nanoscale Bimetallic Particles for In Situ Remediation 50
Wei-xicm Zhang, Tina Masciangioli
Environmental Benefits: Nanoscale Bimetallic Particles for In Situ Remediation 51
Wei-xian Zhang
Section 4. Other Areas 53
Abstract: Plasmon Sensitized Ti02 Nanoparticles as a Novel Photocatalyst for Solar
Applications 55
George Chumanov
Environmental Benefits: Plasmon Sensitized Ti02 Nanoparticles as a Novel Photocatalyst for Solar
Applications 56
George Chumanov
The Office of Research and Development's National- Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Abstract: Development of Nanocrystallinc Zeolite Materials as Environmental Catalysts:
From Environmentally Benign Synthesis to Emission Abatement 57
Sarah C. Larsen, Vickl H. Grassian
Environmental Benefits: Development of Nanocryslailine Zeolite Materials as Environmental Catalysts:
From Environmentally Benign Synthesis to Emission Abatement 58
Sarah C. Larsen, Vicki H. Grassian
Abstract: Ion-Induced Nuclcation of Atmospheric Aerosols 60
Peter H. McMurry, Fred Eisele
Environmental Benefits: Ion-Induced Nucleation of Atmospheric Aerosols 61
Peter H. McMurry
Abstract: Green Engineering of Dispersed Nanoparticles: Measuring and Modeling
Nanoparticle Forces 62
Darrell Velegol, Kris (en Fich thorn
Environmental Benefits: Green Engineering of Dispersed Nanoparticles: Measuring and Modeling
Nanoparticle Forces 63
Darrell Velegol
Section 5. SBIR 65
Abstract: Development of High Surface Area Material and Filter Media 67
Jayesh Doshi
Environmental Benefits: Development of High Surface Area Material and Filter Media 68
Jayesh Doshi
Abstract: Nanocomposite Anchored Plasticizers 70
Andrew Myers
Environmental Benefits: Nanoparticle Anchored Plasticizers 71
Andrew Myers
Abstract: Combinatorial Screening of High-Efficiency Catalysts for Large-Scale Production
of Pyrolytic Carbon Nanotubcs 72
Xiao-Dong Xiang
Environmental Benefits: Combinatorial Screening of High-Efficiency Catalysts for Large-Scale Production
of Pyrolytic Carbon Nanotubes 73
Xiao-Dong Xiang
Dinner Slide Presentation—Societal Implications of Nanobiotechnology 76
DebraRolison
Index of Authors, Plenary and Dinner Speakers 83
Cover image:
Copyright. Dr. V.H. Crespi, Penn State University. Distributed under the Open Content License
(http://opencoiitent.org/opl/shtml).
The Office of Research and Development's National Center for Environmental Research iii
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Introduction
Nanoscale science, engineering, and technology, collectively referred to as nanotechnology, is the ability to work at
the molecular level, atom by atom, to create large structures with fundamentally new molecular organization.
Nanotechnology is a crosscutting area involving disciplines such as chemistry, physics, biology, and engineering,
with truly revolutionary transformation potential for an entire host of products and processes, including those that
enhance environmental quality and sustainability through pollution prevention, treatment, and remediation.
The U.S. Environmental Protection Agency's (EPA) Office of Research and Development (ORD), National Center
for Environmental Research (NCER), as part of its Science to Achieve Results (STAR) program, supports research
leading to applications in nanotechnology. EPA is interested in advances in nanotechnology that can improve the
protection of human health and the environment, including significant improvements in cost or performance of our
capabilities to assess and solve environmental problems. EPA is also interested in predicting and understanding both
the positive and negative environmental effects of this new technological revolution and the changes it will bring to
our society.
EPA's objective in the nanotechnology research area is to support innovative research that could help us define and
understand significant emerging environmental problems. We seek novel approaches that can lead to significant
breakthroughs providing enhanced environmental benefits.
The results from the EPA-sponsored nanotechnology research outlined within this document have the potential to be
used to monitor and remediate environmental problems, curb emissions from a wide range of sources, and develop
new ''green" processing technologies that minimize the generation of undesirable by-product effluents. In addition,
the results offer fundamentally new ways to manufacture new chemicals and pharmaceutical products; measure,
control, and remediate contaminants in various media; and contribute to dematerialization resulting in less environ-
mental impact from the extraction, transport, manufacture, use. and disposal of materials.
This Progress Review Workshop brings together EPA's extramural scientists as well as scientists and policymakers
from government, academic, and non-government organizations to address both the environmental applications and
implications of the emerging area of nanotechnology. The research described in this report has not been subjected to
the Agency's required peer review and policy review, aid does not necessarily reflect the views of the Agency.
Therefore, no official endorsement should be inferred. Any opinions, findings, conclusions, or recommendations
expressed in this report are those of the investigators who participated in the research or others participating in the
Progress Review Workshop, and not necessarily those of EPA or the other federal agencies supporting the research.
For more information on EPA's nanotechnology research, please contact either Barbara Karn, Ph.D.,at
202-564-6824 (kam.barbara@cpa.gov); or Nora Savage, Ph.D., at 202-564-8228 (savagc.nora@cpa.gov).
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
U.S.EPA Centerfor Environmental
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Overview
The EPA Nanotechnology Grantees Workshop brought together researchers from academia, industry, and gov-
ernment to discuss ongoing research on nanotcchnology aid the environment. The 58 Workshop participants listened
to presentations by EPA grantees; the Director of the Center for Biological and Environmental Nanotechnology at Rice
University; the Chair of the Whitehouse Subcommittee on Nanoscale Science, Engineering and Technology; the
Director of the Woodrow Wilson Foresight and Governance Project; and EPA scientists. Participants had an oppor-
tunity to interact with presenters during a poster session. In addition, the group enjoyed a dinner presentation by Dr.
Debra Rolison of the Naval Research Laboratory. This report briefly summarizes the presentations.
AND INTRODUCTION
Barbara Kara, U.S. EPA
Dr. Karn welcomed participants to the workshop. She described EPA's research mission and the role of the
National Center for Environmental Research (NCER) in supporting extramural research, including the Science to
Achieve Results (STAR) program. The STAR program has issued two Requests for Applications targeted toward
nanotechnology—the first in FY 2001 that supported 16 grantees and the second in FY 2002 that received more than
130 applications. More information on STAR grants is available on the NCER Web Site at http://www.epa.gov/ncer.
Dr. Karn outlined the goals of the workshop. First, the meeting was designed to develop a community of scien-
tists and engineers who maintain an understanding mid appreciation for potential environmental implications and
applications while doing their research in nanotechnology. Second, the meeting was intended to serve as a stimulus
for increased research and knowledge of environmental aspects of nanotechnology.
PLENARY
Each day began with a plenary session in which experts discussed broader issues in nanotechnology research
and development.
Plenary Session Day I
Environmental Indications of Nanotechnology: Progress in Developing Fundamental Science as a Basis for Assessment
Vicki Colvin, Director, Center for Biological and Environmental Nanoteebnology, Rice University
Mark Wiesner, Center for Biological and Environmental Nanotechnology, Rice University
Dr. Wiesner opened with a cautionary note based on the current lack of information about the environmental
and health effects of nanotechnology. The Center for Biological and Environmental Nanotechnology (the
Center) risk assessment research on nanotcchnology focuses on exposure because little is known about
nanotechnology's health effects, impacts from nanoreagents, and impacts associated with colloidal materials.
The Center also is conducting research on fate and transport, including transport in porous media, adsorption
and desorption of known environmental contaminants on nanoparticles, and biodegradation of fullerenes.
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Dr. Colvin discussed the potential consequences of nanomaterials on public health. She noted that concern over
the effects of inorganic particles on health has existed since the industrial revolution, with a recent focus on asbestos.
The two current areas of concern are the effects of ultrafinc particles on lungs and wear debris from surgical
implants. Research on nanoparticles includes exploring potential exposure routes: inhalation was the primary expo-
sure route for classic particles, but nanoparticles do not aerosolize as readily so this route might be less likely.
Ingestion is a possible route as is dermal exposure; however, there is little information on dermal contact as a possible
route. Research is underway to explore the effects of material derived from wear damage of implants, because there
is concern that it could lead to autoimmune disease. Another concern is bioaccumulation of nanoparticles.
One of the potential positive implications of nanoparticles for the medical field is the ability of these particles to
pass through cell walls. Dr. Colvin closed by noting that researchers need to collaborate on a realistic public message
about nanotechnology, because some of the groups that oppose genetic engineering arc beginning to oppose
nanotechnology research. The message should emphasize that the nanotechnology research community is respon-
sible and proactive in exploring effects and potential risks, that nanoparticles are not altogether different from other
particles, and that many of the benefits have already been established.
Environmental Technologies at the Nanoscale
Tina Masciangioli, AAAS Fellow at the U.S. EPA
Wci-Xian Zhang, Lebigfa University
Dr. Masciangioli described the large environmental challenges in the 21st Century and the promising role of
nanotechnology in improved detecting and sensing techniques; removal of the finest contaminants from air. water,
and soil: and the discovery of new '"green"' industrial processes that reduce waste products. She stated that
nanotechnology could contribute to pollution prevention by making manufacturing processes environmentally be-
nign, by creating benign materials or manufactured products to replace toxic substances, or by reducing the use of
raw materials. This could enable production of smaller and lighter products with fewer by-products. Nanoscale
technologies can be used to detect biological pathogens, organics, heavy metals, and other contaminants in the
environment. In some cases, they can both sense and treat waste. Dr. Masciangioli pointed out that this multifunctionality
is one of the promising features of nanotechnology (or nanotechnology products).
Dr. Zhang discussed a few of the many questions about nanotechnology. An example includes what will be the
impact of the dark color (absorptivity) of nanoparticles on water quality, photosynthesis, air quality, and global
warming? Most current EPA research addresses larger particles—will there be a need for new technological research
on smaller particles? What will be the applications of fast reaction rates and high contaminant sorption? Dr. Zhang
listed three gaps that are important for nanotcchnology research: (1) gaps in knowledge, because nanoscalc science
and engineering is highly interdisciplinary; (2) gaps in tools, because conventional environmental laboratories are not
equipped for nanoscale work; and (3) gaps in education, because new courses, laboratories, and programs will be
needed to educate the next generation. He concluded by stating that new approaches are needed that offer capabilities
to prevent, treat, or remediate highly toxic or persistent pollutants and result in more effective monitoring of pollutants
or their impacts in ways not currently possible. Nanoscience, engineering, and technology hold great potential for the
continued improvement of technologies for environmental protection.
Plenary Session Day II
EPA Futures Program
Pasky Pascuai, U.S. EPA
EPA has established a "'Futures Program'" to help the Agency anticipate future environmental issues rather than
simply react to them. The program has three major components: (1) scanning for weak signals, consisting of literature
searches for "leads." and review of these items for novelty, scope, severity, visibility, timing, and probability7; (2) scoping
strong signals, which involves tapping expert knowledge and discussing issues with senior Agency managers so that
crises can be avoided in the future; and (3) developing better forecasting tools, such as the ecological indicators
developed in collaboration with the State of Pennsylvania. Nanotechnology is included in the EPA Futures Program.
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Background and Challenges of Nanotechnology for the United States
Mike Roco, National Science Foundation
Dr. Roco opened by stressing the broad societal goals of nanotechnology, and the expanding areas of
relevance to energy conversion, nanobiosystems, molecular system architecture, realistic multiphenomena
modeling, agriculture and food systems, and environmental issues. Dr. Roco described the National
Nanotechnology Initiative (NNI), which encourages innovative, interdisciplinary research. Several areas of
nanolechnology are moving from fundamental discover}' into technological innovation: advanced materials,
electronics, chemicals including catalysts, and Pharmaceuticals. Concerning the environmental implications,
it is important to present to the public a balanced view between advantages of a sustainable development
using nanotechnology and the unexpected consequences. The positive outcomes of nanotechnology far
outweigh the possible negatives. Nanotechnology has major implications for the environment—it is a means
for attaining sustainable development; it reduces waste through "exact manufacturing"; it addresses current
health and environmental issues as well as unintended consequences; it can be used to remove existing pollut-
ants; and it can provide more detailed monitoring capabilities over larger areas. The NNI is comprised of 16
governmental agencies and departments and was responsible for $604 million in Federal research programs in FY 2002.
He noted that Japan is the largest investor in nanotechnology in the world, and Asia is the fastest growing region. The
NNI's priorities for FY 2003 are: (1) tools for manufacturing; (2) detection/protection for biological, chemical, radio-
logical, and explosive hazards; and (3) instrumentation and metrology. More information and reports from the NNI arc
available on the Internet at http://www.nano.gov.
Getting Ahead of the Learning Curve
David Rejeski, Woodrow Wilson Center
The Woodrow Wilson Center has a cooperative agreement with EPA to identify "game changers"—things that
could change the way EPA might operate. A major challenge is how institutions and organizations learn and how they
will react to nanotechnology. In a conventional learning curve, as experience increases, performance is expected to
increase. There arc several types of environmental learning curves: (1) "learning too late"—this is how organizations
learned before EPA was established, making environmental errors/problems and then cleaning up the mess;
(2) "learning through mandate"—since 1970, organizations responded to mandates; (3) "learning by doing"—begin-
ning in 1990, many companies internalized a goal of having less environmental impact, often to avoid mandates; and
(4) '"learning before doing"—starting in 1995. companies have been able to make virtual prototypes and to identify
environmental issues before production begins. Learning about the environmental implications of nanotechnology
could go from one extreme of an absence of learning with all of the unintended consequences to the other extreme of
fast, anticipator}' learning in which the environmental aspects arc co-optimized as part of nanotechnology develop-
ment. He quoted a Kodak manager, "bad news is good as long as it's early." With new technologies coming to market
so quickly, EPA should begin working with research scientists in industry, not just the environmental health and safety-
people who are now the major contacts. There also will be a need for new types of communications and new tools.
DINNER SPEAKER
Societal Implications of Nanobiotechnology
Debra Rolison, Naval Research Laboratory
Dr. Rolison explored the broader scientific and societal context of integrating biomolecular function with nanoscale
objects—nanobiotechnology. She explained that nanobiotechnology is a vision on a nearby horizon—the initial pros-
pects of which are being imagined, designed, and created right now. Dr. Rolison emphasized that even at this early
juncture, we should contemplate what societal impacts might arise from a technology based on objects, devices, and
processes that blend biomolecular function with nanoscopic fabrication and manipulation. She urged scientists,
governmental program managers, policymakers, educators, industrialists—and citizens—to be involved in this un-
dertaking, because technology is rarely implemented without changing society in foreseen and disturbingly unfore-
seen ways.
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
BY EPA
STAR Grantees presented projects in four areas: sensors, treatment, remediation, and other areas of application.
Some grantees were just beginning their projects; others had preliminary results.
Session 1: Sensors
Moderators: Nora Savage (Day I) and Y'Vonne Jones-Brown (Day 2)
Ultrasensitive Pathogen Quantification in Drinking Water Using Highly Piezoelectric PMN-PTMicrocantttevers
Wan Y. Shih, Drexel University
The goal of this project is to develop highly piezoelectric microcantilever arrays for in situ, rapid, simultaneous
multiple pathogen quantification to replace current filtration culture and fluorescence-based methods. This new method
would enhance the capability to respond to terrorist threats and ensure the safety of water supplies. The project has
discovered that piezoelectric cantilevers less than 0.7 mm long are 20 times more sensitive than the Quartz Crystal
Microbalance (QCM). Rapid, real-time, in situ detection ofEscherichia coll via attachment and release using piezoelec-
tric cantilevers was demonstrated. Microfabrication of piezoelectric PZT/Mo microcautilevers and development of Sr-
doped lead titanate films that can be heat treated at 450 °C for better piezoelectric microcantilever fabrication also was
discussed.
Chemosensors for Marine Toxins
Robert E. Gawley, University of Miami/University of Arkansas
The goal of this project is to design and prepare nanoscale bioraimetic receptor/sensors for the detection of
marine toxins (domoic acid, brevetoxin, ciguatoxin, cylindrospermopsin, and tetrodotoxin) based on research and
proof of principle conducted on saxitoxin. The project plan is to use combinatorial chemistry and incorporate a host
compound into a dendrimer. At present, mouse bioassay is the most common detection method for aquatic toxins.
The nanoscale sensors would be inexpensive and more rapid than current technology. Coumarin was found to be
both selective and sensitive as a fluorophore for saxitoxin. The project is proceeding to use these results to test
additional toxins with similar properties, including a good model of a protein binding site.
Nanostructured Porous Silicon and Luminescent PoiysUoles as Chemical Sensors for Carcinogenic ChromiumfVI)
and Arsenic (V)
William Trogler, University of California, San Diego
The goal of this project is to develop new selective solid-state sensors for carcinogenic and toxic chromium(VI)
and arsenic(V) in water, based on redox quenching of the luminescence from nanostructured porous silicon
and polysilolcs. Dr. Trogler applied principles derived from the investigation of sensors for explosives (TNT).
Results were presented concerning the use of polysilole nanoaggregates and aminosilole nanoaggregates as
well as incorporation of the nanoaggregates in a nanotextured microcavity between two porous silicon Bragg
stacks.
A Nanocontact Sensor for Heavy Metal Ion Detection
Nonjlan Tao, Arizona State University
The goal of this project is to develop a high-performance, low-cost sensor for initial onsitc screening of
surface and groundwater to detect heavy metal ion pollution. The sensor consists of an array of nanoelectrode
pairs on a silicon chip, separated by an atomic-scale gap. Electrochemical deposition of even a few metal ions
can bridge the gap and form a nanocontact, triggering a quantum jump in electrical conductance. The project
has successfully fabricated the nanoelectrodes, and a method for mass production is in progress. Additional
research is underway to develop a higher precision measurement method for the conductance.
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Real-lime Chemical Composition Measurements of Fine and Ultraftne Airborne Particles
Murray V. Johnston, University of Delaware
As concern over health effects of ultrafine particles increases, new methods are needed to determine the composi-
tion of these particles in air. The goal of this project is to develop a new technology that will determine chemical
composition of airborne particles down to about 5 run in diameter. Two problems that must be overcome are inefficient
sampling of particles and inefficient analysis of those particles that have been sampled. The project has discovered that
individual nanoparficles can be efficiently detected only if quantitatively converted to atomic ions.
Session 2: Treatment
Moderator: Y'Vonne Jones-Brown
Nanoscale Biopofymers 'With Tunable Properties for Improved Decontamination and Recycling of Heavy Metals
Wilfred Chen, University of California, Riverside
The goal of this project is to develop high-affinity, nanoscale biopolymers with tunable properties for the selective
removal of heavy metals such as cadmium, mercury, and arsenic. Conventional technologies often are inadequate to
reduce concentrations in wastewater to acceptable regulatory levels. The project found that biopolymers with aniino
acid His6 or His]2 tags can serve as a simple metal binding domain; both Tt and metal binding capacity can be regulated
easily, and biopolymers can be recycled. Metalloregulatory protein for mercury (MerR) can serve as a specific
mercury-binding domain.
Transition Metal Carbides as an Environmental Nanocatalyst
S. Ismat Shah, University of Delaware
Current catalytic converters will not be able to meet future emissions reduction targets without increasing the
amount of Pt-group precious metals to levels at which the converters might become prohibitively expensive. The goal
of this research project is to investigate synthesis, characterization, and application of nanoparticlcs of transition metal
carbides and oxycarbides as replacements for the Pt-group metals. The project has found that tungsten carbide
(WCj x) is a possible replacement for the Pt-group metals in automobile catalytic converters. WCj x nanoparticles
were produced by reactive magnetron sputtering and were characterized for their chemistry and structure.
Simultaneous Environmental Monitoring and Purification Through Smart Particles
Wolfgang M. Sigmund, University of Florida
The goal of this project is to investigate whether nano-engineered smart particles based on a modular building concept
enable simultaneous monitoring and purification of water and air. The smart particles undergo visible change in color when
a pollutant is present and are being developed to utilize magnetic and photocatalytic nanoparticles for treatment.
Session 3: Other Areas of Application
Moderator: Nora Savage
Plasmon Sensitized Ti()2 Nanoparticles as a Novel Photocatalystfor Solar Applications
George Chumanov, Clemson University
The goal of this project is to develop a novel hybrid photocatalyst that consists of silver or gold nanoparticles
encapsulated in a titanium dioxide (Ti02) shell. Ti02 is environmentally friendly, relatively inexpensive, and a poten-
tially efficient photocatalyst; however, wide technological use of this photocatalyst is largely hindered by the fact that
ultraviolet light, which does not constitute a significant fraction of the solar spectrum, is required for its activation.
Silver and gold are very efficient for capturing energy from the visible portion of the spectrum. In the initial research
phase, a TiO, shell on silver nanoparticles has been synthesized.
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Measuring and Modeling Nanopartide Forces
Darrell Velegol, Pennsylvania State University
A significant limitation of nanotechnology is the ability to produce bulk quantities of dispersed particles. The goal
of this project is to determine whether solvation or depletion forces can be manipulated to produce dispersed suspen-
sions of "bare" nanoparticles (i.e.. without adsorbed additives). Specifically, the research explores two questions:
(1) What are the magnitudes of the van der Waals, solvation. and depletion forces for nanoparticle systems? and
(2) What variables can we control to alter these forces? Comparing van der Waals and solvation forces, it has been
found that solvation forces are comparable to van der Waals forces and might be used to stabilize particles.
Development of Nanoaystattine Zeolite Materials as Environmental Catalysts: From Environmentally Benign
Synthesis to Emission Abatement
Sarah C. Larsen, University of Iowa
Zeolites are widely used in separations mid catalysis, but the crystal size formed during conventional synthesis
ranges from 1,000 to 10,000 ran. For some applications, it would be advantageous to use zeolite crystals in the range
of 10 to 100 ran. The goals of this project are to: (1) synthesize and characterize nanometer-sized zeolites and
nanostructures (films, fibers); and (2) determine the effectiveness of utilizing nanometer-sized zeolites as environ-
mental catalysts for use in N0x emission abatement, photocatalytic decomposition of organic contaminants, and
environmentally benign selective oxidation reactions with cation-exchanged zeolites.
Ion-Induced Nudeation of Atmospheric Aerosols
Peter H. McMurry, University of Minnesota
The goals of this project are to: (1) determine whether or not ion-induced nucleation leads to the formation of
significant numbers of particles in the atmosphere; and (2) explore the physics and chemistry of ion-induced nucle-
ation in the atmosphere. This is important in the identification of the effects of nucleation on climate and human
health. The project will involve atmospheric measurements to identify the composition of positive and negative ions
during nucleation events and the determination of ion mobility distributions. Preliminary results show that daytime
and night-time compositions are very different.
Session 4: Remediation
Moderator: Nora Savage
Dendritic Nanoscale Chelating Agents—Binding ofCu(II) Ions to PANAMDendrimers in Aqueous Solutions
Mamadou S. Diallo, Howard University
The goals of this project are to: (1) explore the fundamental science of metal ion uptake by dendrimers in aqueous
solutions; (2) assess the extent to which this fundamental knowledge can be used to develop high capacity and
reusable chelating agents for industrial and environmental separations; and (3) develop FeS dendrimer nanocomposiles
with enhanced reactivity, selectivity, and longevity for reductive detoxification of organic and inorganic pollutants in
aqueous solutions and subsurface formations. To date, the study has discovered that in aqueous solutions, dendrimers
such as Poly(amidoamine) (PANAM) can serve as nanoscale containers or high capacity chelating agents for transi-
tion metal ions such as Cu(II); the extent of Cu(II) binding depends on metal ion dendrimer loading, dendrimer
generation and surface chemistry, and solution pH and ionic strength; and the combination of the extended x-ray
absorption fine structure (EXAFS) and Cu(ll) uptake. Preliminary data suggest two primary mechanisms of binding.
Menibrane-Based Nanostructured'Metals for Reductive Degradation of Hazardous Organics at Room Temperature
Dibakar Bhattacharyya, University of Kentucky
The goal of this project is the development and fundamental understanding of reductive dechlorination of selected
classes of hazardous organics by immobilized nanosized metal particles in ordered membrane domains. Preliminary
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
results of chloride formation from trichloroethylene (TCE) dechlorination showed significantly better performance
results from iron nanoparticles in Poly-L-glutamic acid (PLGA) functionalized membranes as compared to using free
iron raicroparticlcs.
Bioengineered Nanoparticles for Environmental Remediation: The Photocatalytic Reduction ofCr(VI)
Daniel Strongin, Temple University
The goal of this project is to develop new nano-sized materials based on fenritin that may serve as catalysts in
photochemical degradation processes of common contaminants. This project has found that ferritin catalyzes Cr(VI)
reduction to Cr(IlI) using visible light. Electron transfer appears to occur both through contact with the inorganic
core and through the protein shell. Ferritin shows excellent stability as a photocatalyst as compared to protein free
particles, because photocorrosion is inhibited by the protein.
SMALL
Carbon Nanofiber-Based Solutions
Jayesh Dosbi, eSpin Technologies, Inc.
eSpin Technologies manufactures nanofibers that are 100 times smaller than human hair and miles long. The
company can produce 10,000 yards of fabric material even1 day from any material the client wants to use. The fibers
can be manufactured into mats that can filter very small particles (less than 3 microns) in water, air, oil, car exhaust,
and other media. They also can be made into insulation, cosmetic, and many other products. The company is testing
the use of carbon nanofiber for beverage filtration. It has found that nauofibers are fragile, so they pose unique
manufacturing and shipping problems, but they offer superior filtration and adsorbancy features.
Nanotube Composites for Clean Coatings
Ted Sun, Intematix
Plastic composites are replacing steel in manufacturing, and the composites need to be coated for protective or
decorative purposes. Current technologies involve spraying and applying an electrostatic coating over sprayed primer.
Carbon nanotube (CNT) filled conductive composites offer a primerless electrostatic coating process, which would
save more than 250 million pounds of spray-painted fascia material and corresponding volatile organic compounds
(VOCs) in the automobile industry alone. This project addresses two issues in CNT composite application: cost and
bonding.
Nanoparticle Anchored Plasticizers
Andrew Myers, TDA Research, Inc.
Plasticized plastics can lose plasticizers to air, water, solvents, and saliva. If the plasticizer could be immobilized
in the polymer, it would benefit the environment and human health. The goal of this project is to develop a method for
binding plasticizing compounds to nanoparticles. The results have shown that the nanoparticlc-bound plasticizers
soften polyvinyl chloride (PVC), do not escape, retain pliability over longer periods of time, lower or eliminate
migration of phthalates, are easy to process, and are inexpensive.
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
U.S. EPA National Center for Environmental Research
Hilton at Crystal City (IEEE Venue)
Arlington, WA
August 28-29,
AGENDA
Wednesday. August 28. 2002
1:00-1:30 Registration
1:30 - 2:00 Welcome and Introduction
Barbara Karn, National Center for Environmental Research, EPA
Purpose of the Workshop
2:00 - 2:45 Plenary Session
Nanotechnology: Environmental Friend or Foe
Vicki Colvin, Mark Wiesner, Rice University
2:45-3:00 Break
3:00 — 3:30 Environmental Technologies at the Nanoscale
Wei-Xian Zhang, Lehigh University
Tina Masciangioli, AAAS Fellow at EPA
3:30 - 4:30 Presentations by EPA/STAR Grantees
Moderator: Nora Savage
Sensors:
3:30 - 3:50 Wan Shih, Drexel University
Ultrasensitive Pathogen Quantification in Drinking Water Using Highly
Piezoelectric PMN-PT Microcantilevers
3:50 - 4:10 Robert Gawley, University of Miami
Nanosensors for Detection of Aquatic Toxins
4:10 - 4:30 William Troglcr, University of California, San Diego
Nanostructured Porous Silicon aid Luminescent Polysiloles as Chemical
Sensors for Carcinogenic Chroniium(Vl) and Arsenic(V)
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
4:30 - 4:45 Small Business Perspective I
cSpin Technologies, Inc. Jaycsh Doshi
4:45 - 6:15 Poster Sessions - Focus on Research Plans
4:45 - 5:30 Posters manned by Chen, Shall, Sigmund, Diallo, McMurry, Bhattacharyya,
Strongin, Zhang
5:30 - 6:15 Posters manned by Shih, Gawley. Trogler, Tao, Johnston, Chumanov. Larsen,
Velegol
6:30 Dinner
Thursday. August 29. 2002
8:30 - 8:40 Opening Remarks
Pasky Pascual, Futures Program, EPA
8:40 - 9:30 Plenary Session: Background and Challenges of Nanotedi for the U.S.
Mike Roco, NSF
EPA/Nan o Collaboration
Dave Rejeski, Wilson Center
9:30 - 10:10 Presentations by EPA/STAR Grantees
Moderator: Y'Vonne Jones-Brown
Sensors (continued):
9:30 - 9:50 Nongjian Tao, Arizona State University
A Nanocontact Sensor for Heavy Metal Ion Detection
9:50-10:10 Murray Johnston, University of Delaware
Elemental Composition of Freshly Nucleated Particles
10:10 -10:20 Break
10:20 - 11:20 Presentations by EPA/STAR Grantees
Treatment:
10:20 -10:40 Wilfred Chen, University of California, Riverside
Nanoscalc Biopolymers With Tunable Properties for Improved Decontamination
and Recycling of Heavy Metals
10:40 -11:00 Ismat Shah, University of Delaware
Synthesis, Characterization and Catalytic Studies of Transition Metal Carbide
Nanoparticles as Environmental Nanocatalysts
11:00 -11:20 Wolfgang Sigmund, University of Florida
Simultaneous Environmental Monitoring and Purification Through Smart
Particles
10 The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
11:20-12:00 Small Business Perspective II
Internatix Corporation Ted Sun
TDA Research, Inc. Andrew Myers
12:00-1:30 Lunch
1:30 - 4:00 Presentations by EPA/STAR Grantees
Moderator: John Barich
Other Areas of Application:
1:30 - 1:50 George Chumanov, Clemson University
Plasmon Sensitized Ti02 Nanoparticlcs as a Novel Photocatalyst for Solar
Applications
1:50-2:10 Darrell Velegol, Pennsylvania State University
Green Engineering of Dispersed Nanoparticles: Measuring and Modeling
Nanoparticles Forces
2:10-2:30 Sarah Larscn, University of Iowa
Development of Nanocrystalline Zeolite Materials as Environmental Catalysts:
From Environmentally Benign Synthesis Emission Abatement
2:30-2:50 Peter McMurry. Uni versity of Minnesota
Ion-Induced Nucleation of Atmospheric Aerosols
2:50 - 3:00 Break
3:00 - 4:00 Remediation:
3:00 - 3:20 Mamadou Diallo, Howard University
Dendritic Nanoscale Chelating Agents: Synthesis, Characterization. Molecular
Modeling and Environmental Applications
3:20 - 3:40 Dibakar Bhattacharyya, University of Kentucky
Membrane-Based Nanostructurcd Metals for Reductive Degradation of
Hazardous Organics at Room Temperature
3:40-4:00 Daniel Strongin, Temple University
A Bioengineering Approach to Nanoparticle Based Environmental Remediation
4:00-4:10 Wrap Up
4:10 Meeting Adjourns
The Office of Research and Development's National Center for Environmental Research 11
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
U.S. EPA National Center for Environmental
Hilton at Crystal City (IEEE Venue)
Arlington, ¥A
August
EHeenAbt
National Academy of Sciences
500 5th Street, NW
Washington, DC 20001
Tel: (202) 334-2756
Fax:(202)334-2752
Lajos Balogh
The University of Michigan
Department of Internal Medicine-Allergy
4010KiesgeII
200 Zina Pitcher Place
Ann Arbor, MI 48109
Tel: (734)615-0623
E-mail: baloghl@urnich.edu
Arup Bhattaeharyya
ADI Associates
Technical Consulting
18 Glenwood Drive
Essex Junction, VT 05452
Tel: (802) 879-3716
Fax:(802)879-3716
E-mail: adi-2001@msncom
Dibakar Bhattacharyya
University of Kentucky
Department of Chemical and Materials
Engineering
169-AAndersonHall 0046
Lexington, KY 40506-0046
Tel: (859) 257-2794,
Fax:(859)323-1929
E-mail: dbi@engr.ulw.edu
Scott Bordcricux
University of Florida
Department of Environmental Engineering
Sciences
3521SW 30th Terrace, #51A
Gainesville, FL 32608
Tel: (352)271-6381
E-mail: border@grove.ufl.edu
John Bucher
National Institute of Environmental
Health Sciences
Toxicology Operations Branch
4401 Building, Mail Drop EC-34
79 T.W. Alexander Drive
Research Triangle Park, NC 27709
Tel: (919)5414532
Fax: (919)5414255
E-mail: bucher@nichs.nih.gov
Wilfred Chen
University of California. Riverside
Bourns College of Engineering
Department of Chemical and Environmental
Engineering
Bourns Hall B319
Riverside, CA 92521
Tel: (909)787-2473
Fax: (909)787-5696
E-mail: wilfrcd@engr.ucr.edu
Alan Christiansen
Mitre Corporation
7515 Colshire Drive (W554)
Mclean,VA 22102-7508
Tel: (703) 883-6857
Fax: (703)883-6501
E-mail: adc@mitre.org
Si mone Christie
Howard University
Department of Civil Engineering
2300 Sixth Street, NW
Washington, DC 20001
Tel: (202) 8064803
Fax: (202)806-5271
E-mail: sische@hotmail.com
The Office of Research and Development's National Center for Environmental Research
13
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
George Chumanov
Clemson University
Department of Chemistry
363 Hunter Laboratory
Clemson, SC 29634
Tel: (864)656-2339
Fax: (864)656-6613
E-mail: gcliumak@clenisoiiedu
VicM Colvin
Rice University
Department of Chemistry
142 Butcher Hall, MS 60"
6100 Main Street
Houston, TX 77005
Tel: (713) 348-5741
Fax:(713)348-5155
E-mail: colvin@rice.edu
Mamadou Diallo
Howard University
Department of Civil Engineering
2300 6th Street NW
Washington, DC 20059
Tel: (202) 8064797
Fax: (202)8065271
E-mail: mdiallo@howard.edu
Jayesh DosM
eSpin Technologies, Inc.
100 Cherokee Boulevard. Suite 325
Chattanooga, TN 37405
Tel: (423)267-6266
Fax: (423)267-6265
E-mail: nano.fiber@aol.com
HarisDoumanidis
National Science Foundation
Division of Design, Manufacture, and Industrial
Innovation
4201 WilsonBoulevard, Room 550
Arlington, VA 22230
Tel: (703)292-7088
Fax: (703)292-9056
E-mail: cdoumani@nsf.gov
Stiven Foster
U.S. Environmental Protection Agency
Office of Research and Development
Ariel Rios Building (8104R)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-2239
E-mail: foster.stiven@epa.gov
Bob Gawky
University of Miami
Chemistry Department
P.O. Box 249118
315 Cox Science Center
Coral Gables. FL 33124-0431
Tel: (305)284-3279
Fax: (305)668-3313
E-mail: rgawley@miami.edu
Gretehen Holtzer
Pennsylvania State University
Department of Chemical Engineering
178 Fenske Laboratory
University Park, PA 16802
Tel: (814)863-7622
Fax: (814)865-7846
E-mail: glhl23@psu.edu
Murray Johnston
University of Delaware
Department of Chemistry and Biochemistry
LammotDuPont Laboratory 102
Academy and Lovett Streets
Newark. DEI 9716
Tel: (302) 831-8014
Fax: (302)831-6335
E-mail: mvj@udel.edu
Y' Vbnne Jones-Brown
U.S. Environmental Protection Agency
Office of Prevention, Pesticides and Toxic
Substances
Office of Pollution Prevention and Toxics
Economics, Exposure and Technology Division
Ariel Rios Building (7401M)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-8568
E-mail: jones-brown.yvonne@epa.gov
Barbara Kam
U.S. Environmental Protection Agency
National Center for Environmental Research
Ariel Rios Building (8722R)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-6824
Fax: (202)565-2446
E-mail: kani.barbara@epa.gov
DetlefKnappe
North Carolina State University
Department of Civil Engineering
Campus Box 7908
Raleigh, NC 27695-7908
Tel: (919) 515-8791
Fax: (919)515-7908
E-mail: knappe@eos.ncsu.edu
14
TJte Office of Research and Development's National Center for Environmental Research
-------
Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
MarthaKrebs
University of California, Los Angeles
Associate Vice Chancellor for Research
2139 Kew Drive
Los Angeles, CA 90046
Tel: (323)656-6750
Fax: (323)656-6240
E-mail: makpec(a)att.net
Sarah Larsen
University of Iowa
Department of Chemistry
305 Chemistry Building
Iowa City, IA 52242-1294
Tel: (319) 335-1346
Fax:(315)335-1270
E-mail: sarah-larsen@uiowa.edu
Clifford Lau
U.S. Navy
Office of Naval Research
800 N.Quincy Street
Arlington, VA 22217
Tel: (703)6964)431
Fax:(703)588-1013
E-mail: lauc@onr.navy.mil
Xlao-qlnLi
Lehigh University
Department of Civil and Environmental
Engineering
13 E. Packer Avenue
Bethlehem, PA 18015
Tel: (610)758-5318
Fax:(610)758-6405
E-mail: xql2@lehigh.edu
Chih-HwaWallyLIn
Ministry of Economic Affairs
Department of Industrial Technology
# 15 Fu-Chou Street Room D202
Taipei, Taiwan, R.O.C.
Tel: (886) 2-2321-2200, ext. 124
Fax: (886)2-2341-2173
E-mail: cMn@moea.gov.tw
Stephen Lingle
U.S. Environmental Protection Agency
National Center for Environmental Research
Ariel Rios Building (8722R)
1200 Pennsylvania Avenue, NW
Washington, NA 20460
Tel: (202) 564-6820
Fax:(202)565-2446
E-mail: lingle.stephen@epa.gov
Ru-Shi Liu
National Taiwan University
Department of Chemistry
Roosevelt Road Section, 4
Taipei, Taiwan, R.O.C. 106
Tel: (886) 2-2369-0152, ext. 148
Fax: (886)2-2369-3121
E-mail: rstiu@ccms.ntu.edu.tw
Michael Loughran
U.S. Environmental Protection Agency
Office of Resources Management
and Administration
Ariel Rios Building (8102R)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-6686
E-mail: loughran.micliael@epa.gov
Bruce MacLeniiaii
University of Tennessee
Department of Computer Science
203 Claxton Complex
1122 Volunteer Boulevard
Knoxville,™ 37996-3450
Tel: (865) 974-5067
Fax: (865)974-4404
E-mail: maclennan@cs. utli.edu
Tina Masdangioli
U.S. Environmental Protection Agency
National Center for Environmental Research
Ariel Rios Building (8722R)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-6791
Fax: (202)565-2446
E-mail: masciangioli.tina@cpa.gov
Peter MeMu rry
University of Minnesota
Department of Mechanical Engineering
111 Church Street, SE
Minneapolis. MN 55455-0111
Tel: (612)624-2817
E-mail: mcmiirry@me.umri.edu
David Meyer
University of Kentucky
Department of Chemical and Materials
Engineering
169-A Anderson Hall
Lexington, KY 405064)046
Tel: (859) 323-2976
E-mail: demevelf3luky.edu
The Office of Research and Development's National Center for Environmental Research
15
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Peter Montague
Science and Environmenlal Heal 111 Network
826 Boucher Avenue
P.O. Box 5036
Annapolis, MD 21403
Tel: (410)2634584
Fax: (732)7914603
E-mail: peter@jachel.oig
Ashok Mufchandani
University of California, Riverside
Bourns College of Engineering
Department of Chemistry and Environmental
Engineering
Bourns Hall B317
Riverside, CA 92521
Tel: (909)787-6419
Fax: (909)787-5696
E-mail: adani@engr.ucr.edu
Andrew Myers
TDA Research, Inc.
12345 W. 52nd Avenue
Wheat Ridge, CO 80033
Tel: (303) 940-2339
Fax: (303)422-7763
E-mail: amycrs@tda.com
Bob Olson
Institute for Alternative Futures
100 N. Pitt Street, Suite 235
Alexandria, VA 22314
Tel: (703)684-5880
Fax: (703)684-0640
E-mail: bolson@altfutines.com
PaskyPascual
U.S. Environmental Protection Agency
Office of Science Policy
Ariel Rios Building (8104R)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-2259
E-mail: pascual.pasky@epa.gov
Ari Rcquicha
University of Southern California
941W. 37th Place
Los Angeles, CA 90089-0781
Tel: (213) 7404502
Fax: (213)740-7512
E-mail: requiclia@usc.edu
MiliailMoeo
National Science Foundation
4201 WrlsonBoulevard, Room 505
Arlington, VA 22230
Tel: (703)292-8301
Fax: (703)292-9013
E-mail: mroco@aisf.gov
Debra Rolison
Naval Research Laboratory
Surface Chemistry Branch
4555 Overlook Avenue, SW
Code6170
Washington, DC 20375
Tel: (202)767-3617
Fax: (202)767-3321
E-mail: rolison@nrl.navy.mil
Jennifer Saunders
National Academy of Sciences
500 5th Street, NW, Room 231
Washington, DC 20001
Tel: (202) 334-2616
Fax: (202)334-1393
E-mail: jsaunder@nas.edu
Nora Savage
U.S. Environmental Protection Agency
National Center for Environmental Research
Ariel Rios Building (8722R)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-8228
Fax: (202)565-2446
E-mail: savagc.nora@cpa.gov
SyedLsmatShah
University- of Delaware
Department of Materials Science
210 Sharp Laboratory
Newark DE 19716
Tel: (302) 831-1618
Fax: (302)8314545
E-mail: ismat@udel.edu
Wan Shih
Drexel University
Department of Materials Engineering
Le Bow Engineering Center 27-332
Philadelphia, PA 19104
Tel: (215) 895-2325
Fax: (215)895-6760
E-mail: shihwy@drexel.edu
Wolfgang SigniuncI
University of Florida
Department of Materials Science and Engineering
225 Rhines Hall
P.O. Box 116400
Gainesville, FL 32611-6400
Tel: (352) 846-3343
Fax: (352)392-6359
E-mail: wsigm@mse.ufl.edu
16
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Metin Sitti
University of California, Berkeley
Department of Electrical Engineering and
Computer Sciences
333 Cray Hall
Berkeley, CA 94720-1770
Tel: (510)643-5795
E-mail: sitti@robotics.eecs.berkeley.edu
Lowell Smith
U.S. Environmental Protection Agency
National Center for Environmental Assessment
Ariel Rios Building (8601D)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-3389
E-mail: snitklowell@epa.gov
Richard Smith
Institute for Alternative Futures
100 N.Pitt Street, Suite 235
Alexandria, VA 22314
Tel: (703)684-5880
Fax: (703)684-0640
E-mail: dsmith@altfutures.com
Anita Street
U.S. Environmental Protection Agency
Office of Research and Development
Ariel Rios Building (8104R)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Tel: (202) 564-3626
Fax:(202)565-2925
E-mail: street.anita@epa.gov
Daniel R. Strongin
Temple University
Department of Chemistry
190 IN. 13th Street
Philadelphia, PA 19122
Tel: (215)204-7119
Fax: (215)204-1532
E-mail: dstrongii@nimbus.ocis.temple.edu
Ted Sun
Intematix Corporation
3 51 Rheem Boulevard
Moraga, CA 94556
Tel: (925)631-9005,ext.l05
Fax: (925)631-7892
E-mail: tsun@intematix.com
NongjianTao
Arizona State University
Department of Electrical Engineering
P.O. Box 876206
Tempe,AZ 85287
Tel: (480) 9654456
Fax: (480)965-8118
E-mail: nongjian.tao@asu.edu
William Trogler
University of California, San Diego
School of Medicine
Department of Chemistry and Biochemistry
UCSD Mail Code 0358 "
9500 Oilman Drive
LaJolkCA 92093-0358
Tel: (858) 534-6175
Fax: (858)534-5383
E-mail: wtrogler@ucsd.edu
Darrell Velegol
Pennsylvania State University
Department of Chemical Engineering
111 Fenske Laboratory
University Park, PA 16802
Tel: (814) 865-8739
Fax: (814)865-7846
E-mail: velegol@psu.edu
MarkWiesner
Rice University
Environmental and Energy Systems Institute
104 Mechanical Laboratory
6100 Main Street
Houston, TX 77005
Tel: (713)348-5129
Fax: (713)348-5203
E-mail: wicsncr@ricc.edu
Chang-YuWu
University of Florida
Department of Environmental Engineering
Sciences
5400 NW 39thAvenue, Apt. L-100
Gainesville. FL 32606
Tel: (352) 3924)845
Fax: (352)392-3076
E-mail: OTwu@ufl.edu
Wei-xian Zhang
Lehigh University
Department of Civil and Environmental
Engineering
13 E. Packer Avenue
Bethlehem, PA 18015
Tel: (610) 758-5318
Fax: (610)758-6405
E-mail: wez3@leliigh.edu
The Office of Research and Development's National Center for Environmental Research
17
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
1.
Sensors - Novel sensing technologies or devices for pollutant antimicrobial detection.
Protection of human health mid ecosystems requires rapid, precise sensors capable of detecting pollutants at the
molecular level. Major improvement in process control, compliance monitoring, and environmental decisionmaking
could be achieved if more accurate, less costly, more sensitive techniques were available.
Examples of research in sensors include the development of nanoscnsors for efficient aid rapid in situ biochemical
detection of pollutants and specific pathogens in the environment; sensors capable of continuous measurement over
large areas, including those connected to nanochips for real-time continuous monitoring; and sensors that utilize lab-
on-a-chip technology. Research also may involve sensors that can be used in monitoring or process control to detect
or minimize pollutants or their impact on the environment.
The Office of Research and Development's National Center for Environmental Research 19
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for of
Robert E. Gawley
University of Miami, Coral Gables, PL
Abstract
This project will design and prepare nanoscale sensors
for the detection of marine toxins domoic acid, brevetoxin,
ciguatoxin, cylindrospermopsin, and tetrodotoxin. Most of
these marine toxins bind specifically to protein receptor sites
with a high affinity (Kd typically in the nM range). The
protein receptor sites for several of these toxins have been
characterized, and include two characteristic features. One
is an array of amino acid side chains that complement struc-
tural features of the toxin, which facilitates and strengthens
binding of the toxin into the receptor site. A second feature is
a solvent-excluded pocket in which the amino acid side
chains are arrayed. This preorganized feature of toxin re-
ceptor sites will be mimicked by design of synthetic recep-
tors at the nanoscale (nanoseiisors). To optimize the sensi-
tivity and the selectivity of the nanosensor. combinatorial
synthesis techniques will be used to oplimi/e binding in li-
braries of peptidic host molecules immobilized on solid sup-
port (polystyrene beads). Unlike side chain arrays in the
native (protein) receptors, the combinatorial synthesis tech-
niques will not be limited to L-amino acids, or even to natu-
ral ammo acids. In this way. short peptide sequences will be
produced that wrap around toxins and bind them by provid-
ing an array of side chains similar to the native receptor. To
mimic the solvent-excluded pocket of protein receptor sites.
the combinatorially designed peptide will be incorporated at
the core of a dendritic polymer, still on a solid support.
The marriage of combinatorial design and dcndrimcr
synthesis on solid support will provide large libraries (up
to 100,000 members) of polypeptide hosts inside den-
dritic polymers, with each individual host molecule at-
tached uniquely to a polystyrene bead. This is a novel
approach in nanosensor design. To our knowledge, this is
the first time combinatorial!}' designed peptidic hosts have
been incorporated into a dendrimer. Qualitative evaluation
of toxin binding can be done simply with a fluorescence
microscope. Quantitative analysis will be done with a spe-
cific host after it has been synthesized in bulk.
At present, environmental monitoring for aquatic tox-
ins is most commonly done by mouse bioassay. Alterna-
tive methods, such as liquid chromatography coupled with
mass spectroscopy (LC-MS), are extraordinarily expen-
sive and not suitable for high-throughput analysis. To move
away from mouse bioassay, an inexpensive, fast method
is needed. It is anticipated that this project will identify
nanoscale sensors attached to polystyrene beads that can
detect toxins using only a hand-held UV lamp and a mag-
nifying glass.
The science behind the design of toxin sensors will lead
to further developments as well. These synthetic receptors
also could be used to immobilize the toxins. Although be-
yond the scope of the present work, the same design fea-
tures used for mimicking toxin receptor sites also can be
used to mimic enzyme receptor sites. Thus, by using mod-
els of enzyme active sites, it is anticipated that this method-
ology could be used to mimic enzyme reactions to produce
solid phase catalysts.
The Office of Research and Development's National Center for Environmental Research
21
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for of
Robert E. Gawley
University of Miami, Coral Gables, FL
Environmental
This project addresses the STAR-K1 initiative, "Ex-
ploratory Research on Nanotechnology;' by working
at the molecular level to create large structures with
fundamentally new molecular organization. Among the
possible future applications of this technology, but be-
yond the scope of the present project, could be appli-
cations such as molecular synthesis of new catalysts
for industrial processes, and reactive surface coat-
ings that destroy or immobilize toxic compounds.
The specific pollutants (toxins) for which chemo-
sensors are being developed are: tetrodotoxin,
cylindro-spermopsin, domoic acid, brevetoxin, and
ciguatoxin. There are alarmingly increased quantities
of these toxins in parts of the environment as never
seen before. As an example, recent issues (May 27.
2001) of the Orlando Sentinel and the Miami Her-
ald include articles entitled ''Poisons from algae lurk in
the water we drink:' In the spring of 2002, another se-
ries of stories detailed poisonings by saxitoxin that en-
tered the human food chain via pufferfish caught near
Cape Canaveral. Florida. This is the first occurrence of
saxitoxin poisoning in the Atlantic south of New En-
gland.
These stories also went to other newspapers via the
Associated Press (AP) wire service. They refer to the
recently detected presence of toxins never seen before
in Florida—even alligators have succumbed to recent
algal blooms. Why are these blooms occurring? Were
the algae always present but now are blooming in larger
quantities because of some stimulus? This is unknown.
As a result, fast, cheap ways to detect the toxins are
needed.
22
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
Murray V. Johnston
University of Delaware, Newark, I)E
Abstract
For more than a decade, mass spectrometry has been
used to determine the chemical composition of individual
airborne particles in real time. It has been coupled with
various size measurement or size selection methods to
provide correlated size-composition information of am-
bient aerosols. Most of these methods work well for
particles down to approximately 500 nm in diameter; a
few methods work well down to approximately 50 nm
in diameter. Currently, none are acceptable for particles
smaller than approximately 30 nm in diameter.
Over the last few years, our emphasis has been on
the analysis of particles between approximately 30 and
500 nm in diameter. Correlated size-composition infor-
mation is obtained by sampling the aerosol with a size-
selective inlet and ablating individual particles on-the-fly
with a pulsed laser. This approach has been used to ob-
tain size-resolved mass spectra of several hundred thou-
sand ambient particles at multiple urban sampling sites.
Extending these measurements to particles down to
approximatlcy 5 nm in diameter requires the develop-
ment of new technology. Two specific problems must
be overcome: (1) efficient sampling of particles into the
mass spectrometer, and (2) efficient analysis of those
particles that have been sampled.
In this presentation, the current state-of-the-art in
fine particle analysis will be discussed along with ambi-
ent particle data from several urban sampling sites in the
United States. New instruments that are capable of ex-
tending these measurements to ultrafinc particles also
will be described.
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
Murray V. Johnston
University of Delaware, Newark, I)E
The technology developed in this research project
will permit the chemical composition of airborne
nanoparticles (down to about 5 nm in diameter) to be
determined. Knowledge of the chemical composition
will provide a better understanding of the sources of
these particles and how to control their formation in a
manner that reduces their impact on human health.
It is now well established that long-term exposure
to fine particulatc matter is a significant risk factor for
cardiopulmonary and lung cancer mortality in humans.1
In urban air, fine particulates typically exhibit a maxi-
mum in both number and mass in the 100 to 300 nm
diameter range. Most of these particles are produced
directly from combustion sources. However, a signifi-
cant fraction of particles in this size range also may
arise from growth and/or coagulation of much smaller
particles. Indeed, particle formation events have been
identified in a variety of locations around the world,
including urban locations such as Atlanta.2 These events
are characterized by sudden bursts of ultrafine particles
10 nm diameter and smaller, usually early in the day,
followed by growth to larger sizes. The mechanism of
particle formation is difficult to assess without chemi-
cal composition measurements during these events.
Technology already exists for chemical analysis of fine
particles.3 Our group has characterized particles in this size
range at the Atlanta, Houston, Baltimore, and Pittsburgh
supcrsitcs. An example of the information that can be
gained from these measurements is shown in Figure I.
The spectrum shows a signature indicative of iron. Par-
ticles containing iron at this particular site are normally
observed when the wind is blowing from the south-south-
west and most likely correspond to emission from a spe-
cific source. Other particle compositions correspond to
other emission sources. Thus, size- and time-resolved
measurements of particle composition potentially allow
the ambient aerosol to be apportioned into the various
sources of particle emission.
Unfortunately, these methods cannot characterize
particles smaller than about 30 nm in diameter. The
technology to be developed in this work addresses the
two fundamental limitations associated with nanoparticle
analysis. First, an improved size-selective sampling
method will be developed for particles down to about 5
nm in diameter. Second, an improved particle analysis
method will be developed that allows the elemental com-
position of these particles to be detennined.
The technology developed in this project will fill
an important gap in particle analysis, allowing par-
ticles within the entire range of sizes finally to be
handled so that the ambient aerosol can be fully char-
acterized.
' Pope CA, Burnett RT, ThunMJ, Calle EE, Krewski D, Ito K. Thurston GD. Lung cancer, cardiopulmonary
mortality, and long-term exposure to fine particulatc air pollution. JAm A'fedAssoc 2002:2^1:1132-1141.
2 Woo KS. Chen DR, Pui DYH, McMurry PH. Measurement of Atlanta aerosol size distributions: observations of
ultrafine particle events. AerosolSci Tec/iwo/2001 ;34:75-87.
3 Johnston MV. Sampling and analysis of individual particles by aerosol mass spectrometry. JMass Speciromeiry
2000:35:585-595.
24
'lite Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Figure 1. Characteristics of a class of ambient particles containing iron: size, date, time of day, and wind
direction.
The Office of Research and Development's National Center for Environmental Research
25
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
In
PHHN-PT
Wan Y. Shift, W.-H. SMh, K Mutharasan, and Y. Lee
Drexel University, Philadelphia, PA
Abstract
The goal of the proposed research is to develop highly
piezoelectric microcantilever arrays for in situ rapid, si-
multaneous multiple pathogen quantification using electri-
cal means in source water with unprecedented sensitivity
(1()"15 g). The proposed piezoelectric microcantilevers—
sm aller than 10 micrometers in length with antibodies spe-
cific to the target pathogens immobilized at the cantilever
tip—will measure the presence of pathogens with
femtogram (a small fraction of a cell's mass) sensitivity in
source water. Binding of target pathogens is detected by
monitoring the resonance frequency shift. This represents
the ability to detect a single cell. The use of the highly
piezoelectric microcantilever for simultaneous quantifica-
tion of model pathogens, Escherichia coll 0157, Ciypto-
sporidium parvum. and Helicobacler pylori will be dem-
onstrated.
To achieve the proposed piezoelectric microcantilever
sensor arrays, parallel efforts will be conducted in the
following major task areas: (1) microfabrication of min-
iaturized piezoelectric cantilevers for femtogram mass
detection sensitivity, (2) demonstration of pathogen quan-
tification in source water by selective antigen-antibody
binding, and (3) characterization of the robustness of
various cantilever designs for optimal performance.
On the selectivity front, initial results on antibody-
antigen binding and antibody-gold surface binding will
be presented using piezoelectric lead zirconate titanate
(PZT)/stainless steel cantilevers of millimeter length with
a stainless steel tip. The unique design of such cantile-
vers allows picogram detection capabilities, and permits
the quantification of both binding of antibody with or
without linkers to the gold-coated cantilever tip surface
and that of E. coll to the immobilized antibody by di-
rectly minitoring the cantilever's resonance frequency
shift. The resonance frequency shift transient of anti-
body-coated cantilever can be used to characterize the
amount of pathogens present in the water. This will al-
low characterization of antibody immobilization and E.
coli detection in low to moderate concentrations.
On the miniaturization front, the most critical step in
the microfabrication of piezoelectric microcantilevers is
the development of highly piezoelectric thin layers that
have a low sintering temperature that are compatible with
the standard silicon microfabrication processes. Devel-
opment of piezoelectric thin layers will result in stron-
tium-doped lead titanate (PST) thin layers that can be
sintered at 450 °C.
As a result of the proposed study, it is anticipated
that ultrasensitive, rapid, specific, multiple pathogen quan-
tification of drinking water will be achieved using arrays
of highly piezoelectric PST unimorph microcantilevers
of less than 10 micrometer in length with better than 10~15
g/Hz sensitivity, coupled with antibodies specific to the
target pathogens immobilized at the cantilever tip. Be-
cause the proposed piezoelectric cantilever sensors use
electrical signal for actuation and detection, the sensor
and all necessary electronics can be organized in a com-
pact form that is easily usable in such broad ranging
applications as environmental monitoring and genomics-
inspired proteomics.
26
'lite Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
In
PHHN-PT
Wan Y. Shift, W.-H. SMh, K Mutharasan, and Y. Lee
Drexel University, Philadelphia, PA
Current development of pathogen detection in water
relies on filtration culture methods, and fluorescence-
based methods (e.g., fluorescence probes methods aid
DNA microarray methods). These techniques, however,
are not effective for in situ, rapid, quantitative measure-
ments. With filtration culture methods, sample water is
passed through a filter that is pretreated for visualization
of the target pathogen. Growth of colonies on the filter
indicates the presence of the target pathogen in the test
water. Both the fluorescently labeled probe methods and
the DNA microarray methods rely on detection using
fluorescence spectroscopy, which is not quantitative.
There is a need for rapid, quantitative, and specific-
pathogen detection to ensure the safety of natural and
manmade water supplies, including source, treated, dis-
tributed, and recreational waters. The proposed technol-
ogy uses arrays of a highly piezoelectric (e.g., strontium-
doped lead titanate) niicrocantilever smaller than 10
micrometers in length coupled to antibody proteins im-
mobilized at the cantilever tip for in situ rapid, simulta-
neous multiple pathogen quantification in source water,
with the ability to detect pathogens using electrical means
with feintograni sensitivity (10~15 g).
Binding of target pathogens is detected by monitoring
the resonance frequency shift. The cantilever allows an
unprecedented sensitivity, better than 10~15g/Hz. This rep-
resents the ability to detect a single cell. The current pro-
posed work will demonstrate the use of the highly piezo-
electric niicrocantilever for sim ultaneous detection of model
pafaogens,Cryptosporictiumparvwn,Helicobacterpylori,
and Escherichia coti O157.
Because the proposed piezoelectric cantilever sensors
use an electrical signal for actuation and detection, the
sensor and all necessary electronics can be organized in a
compact form and easily usable in such broad ranging
applications as environmental monitoring.
In addition to the proposed pathogen quantification in
water, the proposed array piezoelectric niicrocantilever sen-
sor technology also offers the potential for a wide spectrum
of toxin monitoring, ranging from small molecular-weight
gaseous species to bacteria in low concentrations both in air
and in liquid because of the ultra high detection sensitivity.
The Office of Research and Development's National Center for Environmental Research
27
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
A for Ion
Nongjian Tao
Arizona State 'University, Tempe, AZ
Abstract
As materials and devices shrink to the nanometer
scale, various quantum phenomena become important.
This may lead to novel applications, including those that
are important to environmental analysis aid protection.
This project exploits the phenomena of conductance
quantization and quantum tunneling to fabricate nano-
electrodes for in situ detection of metal ion pollution. The
goal is to develop a high-performance and low-cost sen-
sor for initial onsite screening tests of surface and ground-
water to provide early warning and prevention of heavy
metal ion pollution. The existing analytical techniques
usually require prcconccntration of samples to detect trace
metal ions, which can be time-consuming and prone to
cross-contamination. Moreover, many of the sensitive
techniques, such as inductively coupled plasma-mass
spectrometry, are not suitable for onsite monitoring. In
contrast, the nanocontact sensor has the potential for
detecting even a few metal ions without preconcentration
and is particularly suitable for onsite detection of ultratrace
levels of heavy metal ions, including radioactive elements.
The sensor consists of an array of nanoclcctrodc pairs
on a silicon chip. The nanoeledrodes in each pair are sepa-
rated with an atomic scale gap, which is achieved with the
help of quantum tunneling phenomenon. Electrochemical
deposition of even afew metal ions into the gap can bridge
the gap and form a nanocontact between the nanoelec-
trodes, thus triggering a quantum jump in the electrical
conductance. The sensor can achieve high specificity by
combining several different measurements, such as redox
potentials, point-contact speclroscopy, and electrochemi-
cal potential-modulated conductance changes.
It is anticipated that this project will lead to a proto-
type nanocontact sensor for detecting heavy metal ion
pollution in water. In addition to the unprecedented sen-
sitivity, the sensor will be miniaturized and cost effec-
tive, which should be particularly suitable for an initial
onsite screening test of polluted samples, thus leading to
early warning and prevention of heavy metal ion pollu-
tion. The capability to measure and control electrochemical
deposition/stripping of a single or a few metal ions, to be
fully developed in this project, may provide opportuni-
ties for a better understanding of electroanalytical chem-
istry of metal ions aid lead to new environmentally be-
nign fabrication methods for nanoelectronics.
28
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
A for Ion
Nongjian Tao
Arizona State 'University, Tempe, AZ
The threat of heavy metal pollution is a serious environ-
mental concern because of the toxicity of such metals on a
broad range of living organisms, including humans, and the
consequence of heavy metals not being biodegradable. Due
to flic difficulty in the remediation of sites contaminated
with heavy metals, there is an urgent demand for an in situ
sensor capable of detecting heavy metal ions before the
concentration reaches a dangerous level. To date, heavy
metals in the environment are usually measured with spec-
troscopic techniques, including atomic absorption and in-
ductively coupled plasma-mass spectroscopy (ICP-MS).
These techniques are well established but require that samples
be collected aid transported to the laboratory for analysis,
because the instrumentation is bulky, expensive, and re-
quires significant maintenance and operator expertise. Sample
preservations and pretreatments, generally required by these
techniques, may cause sample contamination. In situ mea-
surements, performed in the natural environment, are highly
desirable because they provide an early detection of trace
metal contaminants while minimizing errors, labor, and cost
associated with collection, transport, and storage of samples
for subsequent laboratory analysis.
Supported by the U.S. Environmental Protection
Agency's Nanotechnology Exploratory Research Program,
this project includes the development of a iianocoiitact
sensor for in situ detection of heavy metal ion pollution in
water. It has already revealed that the sensor can be ex-
tremely sensitive with the potential capability of detecting
a few metal ions. High specificity will be based on differ-
ent redox potentials of metal ions, a principle that has been
successfully used in anodic stripping technique. In addi-
tion, point-contact spectroscopy and electrochemical po-
tential-induced conductance change will be used to fur-
ther improve the specificity. The sensor will be miniaturized
and automated, making it conducive to onsite field appli-
cations. The sensor head used in preliminary experiments
is a 0.5 in. x 0.5 in silicon chip, on which 15 pairs of nano-
electrodes are fabricated. Because the sensor is fabricated
with conventional microelectronic fabrication facilities and
relatively simple electrochemical techniques, it also should
be cost effective. It is anticipated that the sensor will be
particularly suitable for initial onsite screening tests of pol-
luted samples, thus leading to early warning and preven-
tion of heavy metal ion pollution.
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
as
for
William C. Trogler and Michael J. Sailor
University of California, San Diego, CA
Abstract
The goal of this research project is to develop new
selective solid-state sensors for carcinogenic and toxic
chromium(VI) and arsenic(V) in water based on redox
quenching of the luminescence from nanostructured
porous silicon and polysiloles.
Nanostnicturcd porous silicon, as well as polysilole
nanowire coatings, will be chemically modified to en-
hance binding of the chromate and arsenate anions.
Chemical modification to vary the redox potential of the
polysilole excited state also will be used as a way to
impart chemical selectivity. Both sensor approaches will
be combined by encapsulating the polysilole in a nano-
textured microcavity between two Bragg stacks con-
structed from porous silicon. Such optical devices have
been shown to provide significant detection sensitivity
enhancements. The nanoporous material will readily ad-
mit small inorganic analytes, such as chromate and ar-
senate, and exclude biomolecules that might confound
the measurements. Sensors based on silicon wafer and
polymer technologies are readily adaptable to fabrica-
tion. The fluorescence quenching detection modality also
is inanufacturable. The essential electronics requires a
blue or UV LED as the excitation source and an inexpen-
sive photodiode detector.
Potential applications of such real time solid-state
sensors include remote sensing and industrial process
control. The focus on chromium(VI) and arsenic(V)
detection is dictated by the redox quenching mechanism
that is being used, as well as by the importance of
chromium(Vl) and arsenic(V) as regulated chemicals
under the Safe Drinking Water Act. The results address
the needs identified in the solicitation as nanotechnology
is applied to the development of solid-state sensors that
can be used to monitor pollutants in water that are cur-
rently of great concern to the U.S. Environmental Pro-
tection Agency's regulator}'" mission.
30
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
as
for
'William C. Trogler
University of California, San Diego, CA
The chief goal of this research project is to develop
new selective solid state sensors for carcinogenic and toxic
chromium (VI) and arsenic(V) based on redox quenching
of the luminescence from nano-structured porous silicon
and polysiloles. Nano-structured porous silicon as well as
polysilole nanowire coatings will be chemically modified
to enhance the binding of the chromate and arsenate an-
ions. Chemical modification to vary the redox potential of
the polysilole excited state also will be used as a way to
impart chemical selectivity. Both approaches will be com-
bined by encapsulating the polysilole in a nanotex-tured
microcavity between two Bragg stacks constructed from
porous silicon. Such optical devices have been shown to
provide significant detection sensitivity enhancements. The
nanoporous material will readily admit small inorganic
analytes, such as chromate and arsenate, and exclude
biomolecules that might confound the measurements.
Sensors based on silicon wafer and polymer technologies
also are readily adaptable to fabrication. The fluorescence
quenching detection modality also is manufacturable. The
essential electronics require a blue or ultraviolet LED as
the excitation source and an inexpensive photodiode de-
tector. Potential applications of such real-time detection
devices include remote sensing and industrial process con-
trol. The focus on cliromium(VI) and arsenic(V) detec-
tion is dictated by the redox quenching mechanism that is
being used, as well as by the importance of chromium (VI)
and arsenic(V) as regulated chemicals under the Safe
Drinking Water Act.
Chromium(Vl) detectors will be developed that can
sense the analyle at concentrations at least as low as the
0.1 ppm action level mandated by the Safe Drinking Water
Act with at least a 10 percent accuracy. For arsenic(V),
the target range is 10-5 0 ppb at the same level of analyti-
cal accuracy. The deployment of remote sensors for
natural waters and for industrial wastewater that could
be used to signal alerts in real time would become pos-
sible. An electronic sensor method would prove more
beneficial thai the grab-sampling procedure currently
used for detecting these problematic water contaminants.
A second goal of the project is the development of poly-
mer coated 'litmus paper"' for qualitative detection of
chromiumfVI) and arsenic(V). Given the low expense
of polymer-coated paper, this could prove to be a useful
adjunct to current qualitative methods.
Those that benefit from remote sensing applications
would include research scientists trying to understand
the variations in chromium and arsenic pollutants in
natural waters, municipal source water monitoring, as
well as federal regulator}' monitoring. Because electronic
sensors can be engineered either wired or wireless, the
range of possible applications is truly immense. Indus-
tries involved in metal working and electroplating also
would benefit from the ability to monitor waste streams
for continuous compliance (in real time) with pollution
regulations. Electronic sensors also could be employed
to monitor mine runoff for the presence of toxic soluble
chromium and arsenic that could enter ground or natural
water systems. Chromium is widely used as a corrosion
inhibitor in closed water boilers and chillers. Electronic
sensors could be used to monitor leaks into nearby ground-
water as well as into heat exchange systems.
The simple 'litmus paper" application of the thin film
polymer indicators could prove useful for field studies
and monitoring. Such test strips also would find applica-
tion in science education (both K-12 and university level)
for informing the public about metals in water supplies.
Qualitative test strips would be most economically fea-
sible for monitoring water supplies for compliance at the
tap, which is the ultimate measure of safety.
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
2.
Treatment - Technologies to effectively treat environmental pollutants.
Cost-effective treatment poses a challenge for the EPA and others in the development of effective risk management
strategies. Pollutants that are highly toxic, persistent, and difficult to treat, present particular challenges. EPA supports
research that addresses new treatment approaches that arc more effective in reducing contaminant levels and more
cost effective than currently available techniques. For example, nanoteclinology research that results in improved
treatment options might include removal of the finest contaminants from water (under 300 nm) and air (under 50 nm)
and ''smart" materials or reactive surface coatings that destroy or immobilize toxic compounds.
The Office of Research and Development's National Center for Environmental Research 33
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for
of
Wilfred Chen, Ashok Mulchandani, and Mark Matsumoto
University of California, Riverside, CA
Abstract
Nanoscale materials have been gaining increasing inter-
est in the area of environmental remediation because of
their unique physical, chemical and biological properties.
One emerging area of research has been the development
of novel materials with increased affinity, capacity, and se-
lectivity for heavy metals because conventional technolo-
gies are often inadequate to reduce concentrations in waste-
water to acceptable tegulatory standards. Genetic and protein
engineering have emerged as the latest tools for the con-
struction of nanoscalc materials that can be controlled pre-
cisely at the molecular level. With the advent of recombi-
nant DNA techniques, it is now possible to create "artificial''
protein polymers with fundamentally new molecular orga-
nization. The most significant feature of these nanoscale
biopolymers is that they are specifically pre-programmed
within a synthetic gene template and can be controlled pre-
cisely in terms of sizes, compositions and functions at the
molecular level. In this manner, it is possible to specifically
design protein-based nano-biomaterials with both metal-bind-
ing and tunable properties that can be used to selectively
remove heavy metals from dilute solutions in one single
process. The overall objective of this research is to develop
high-affinity, nanoscale biopolymers with tunable proper-
ties for the selective removal of heavy metals such as cad-
mium, mercury, and arsenic.
The elastin domain, which has been shown to un-
dergo a reversible phase transition upon temperature
changes, will be used to generate fusion biopolymers with
various metal-binding domains. Several metal-binding do-
mains such as Gly-His-His-Pro-His-Gly, MerR (a repres-
ser for the mercury resistance operon), and ArsR (a re-
presser for the arsenic resistance operon) will be used to
provide high affinity and selective removal of mercury
and arsenic. Synthetic genes encoding for the tunable
biopolymers will be specifically tailored for the desired
properties. By tuning the process pH and temperature,
reversible network formation between the individual
biopolymers will enable the recovery of sequestered met-
als by precipitation. The use of these metal-binding do-
mains has significant advantages over existing chemical
chelators, including higher specificity and affinity. The
potential lower limit for heavy metal removal could be on
the order of 10~10M, or approximately 8 parts per trillion,
depending on the metal-binding domain employed.
The ability of these biopolymers to self assemble as
aggregates and their metal binding capability will be elu-
cidated. Experiments will be conducted to determine the
selectivity and metal uptake capacity of the tunable
biopolymers. The potential of the biopolymers for re-
peated metal removal will be investigated by subjecting
to several cycles of binding and stripping. The perfor-
mance of the tunable biopolymers for heavy metal re-
moval will be compared to the commercially available
ion exchange sorbents such as Duolite GT-73, Amberlite
IRC-718, Dovvex SBR-1, and Amberlite IRA 900X.
The proposed tunable biopolymers extend ideas from
nature toward entirely new objectives. Molecular-level
protein-protein recognition is tailored specifically into
tunable metal-binding biopolymers. These biopolymers
can be easily and continuously applied with other exist-
ing technologies for bulk heavy metal removal. This op-
eration is environmentally friendly because no toxic
chemical is required for synthesis of the biopolymers
and regeneration can be achieved easily. This strategy, if
successful, will provide a low-cost and environmentally
benign technology for heavy metal removal.
The Office of Research and Development's National Center for Environmental Research
35
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for
of
Wilfred Chen
University of California, Riverside, CA
Environmental Benefits
A variety of metals requiring removal and concentra-
tion exist in many contaminated sites and in ground or
process waters. Increasingly restrictive Federal regula-
tion of allowable levels of heavy metal discharge into
harbors and coastal water and the need for rapid cleanup
of contaminated sites has prompted the development of
novel approaches and technologies for heavy metal re-
moval. Although existing technologies arc adequate to
remove the bulk of the heavy metal contamination, they
fail to meet the low concentration limits required by regu-
latory standards. It becomes clear that a robust, polish-
ing process is required to effectively remove and re-
cover hazardous metals in dilute waste streams. The
tunable biopolymers proposed here are extensions of ideas
from nature with entirely new objectives.
Molecular-level protein-protein recognition is tailored
specifically into tunable metal-binding nanoscale biopoly-
mers. The biosynthetic approach is environmentally
friendly; provides precise and independent control of the
length, composition, and charge density of the interacting
end blocks and metal-binding domains; and allows for the
flexibility in designing tunable biopolymers that can un-
dergo transition from water-soluble to aggregate forms
under a wide-range of conditions. Such precise control
satisfies the needs of different process conditions. If the
metal-binding proteins associated with As and Hg resis-
tance are used, the expected lower limit for As and Hg
removal using tunable biopolymers could be on the order
of 1010M, or approximately 8 parts per trillion. Because of
their unique properties and selectivity, it is anticipated that
the new biopolymers will result in a wide range of applica-
tions for heavy metal removal/recovery. Compared to con-
ventional chemical chelators or chelating polymers, the
proposed biopolymers are environmentally friendly because
no toxic chemical is required for their synthesis, and re-
generation can be achieved easily. This strategy, if suc-
cessful, will provide a low-cost mid environmentally be-
nign technology for heavy metal removal.
36
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
as
S. Ismat Shah and J. G Chen
University of Delaware, Newark, DE
Abstract
The future targets for the reductions of emission gases
from automobile exhaust are very demanding. For ex-
ample, the 2004 Ultra Low Emission Vehicle (ULEV) Act
requires that the level of N0x must be reduced to 0.05 g/
mile (i.e., one-quarter of the currently allowed value).
The current catalytic converter technology is incapable
of achieving such goals without increasing the amount
of Pt-group precious metals to levels at which the con-
verters might become prohibitively expensive. This project
will investigate the synthesis, characterization, and ap-
plication of nanoparticles of transition metal carbides and
oxycarbides as replacement for Pt-group metals (Ru.
Rh, Ir, Pd, and Pt). The choice of materials is based on
recent results that show strong similarities in the cata-
lytic properties between transition metal carbides and
the more expensive Pt-group metals. In addition to of-
fering a very high surface/volume ratio, nanoparticles
offer the flexibility of tailoring the structure and catalytic
properties on the nanometer scale.
In the first phase of the research, iianostructured WCx
thin films were prepared by reactive sputtering of a pure
tungsten target in an argon-methane discharge. A DC
magnetron gun was used. Nanostructured thin films were
deposited on glass, quartz, silicon and sapphire substrates
at temperatures up to 400 °C. The carbon content in the
film was varied by changing the partial pressure of meth-
ane. The carbon content in the films was analyzed using
Energy Dispersive X-ray Analysis (EDAX). The effect of
temperature on the grain size also was studied using Trans-
mission Electron Microscope (TEM). The TEM results
showed that the average grain size is approximately 1.5-
2.0 nm and that the grain size is constant for temperatures
up to 600 °C. In reactive sputtering, compound formation
occurs above a critical concentration of the reactive gas
in the sputtering gas mixture leading to, among other ef-
fects, a sharp reduction in the deposition rate. The target
poisoning behavior was studied by measuring the target
current. The critical methane concentration at which the
metal-poison mode transition occurs was measured to be
around 38 percent of CH( in Ar. Preliminary results on the
catalytic properties of nanostructured WCx also will be
presented.
The Office of Research and Development's National Center for Environmental Research
37
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
as
51 Ismat Shah and J. G. Chen
University of Delaware, Newark, I)E
One of the major environmental pollution sources is
automobile exhaust, which causes smog and acid rain.
Since 1975, the automobile manufacturers have taken a
variety of steps to reduce the level of harmful emission
gases, including N0x, CO, and unburned hydrocarbons
(HC). At present, the emission levels of these gases can
be reduced by catalytic reactions in the catalytic con-
verter via the following chemical reactions:
CO + 0, -> CO, CO Oxidation
HC + Q\ -> OX + H^O HC Oxidation
N0x + HC -> N* + H20 + CO, M\ Reduction by HC
X " NO'" Reduction bv CO
In these reactions, the harmful pollutants are converted
into relatively harmless molecules such as C02, N2 and
H20. These reactions occur inside the automobile cata-
lytic converters in the presence of catalysts, which con-
sist of mixtures of platinum-group metals such as rhodium
(Rh), platinum (Pi), and palladium (Pd). Due to their lim-
ited natural abundance in the Earth's crust, the platinum-
group metals are among the most expensive elements.
For example, the current price for a troy ounce of Rh is
approximately $2,500, which is about three times more
expensive than gold. For cost-effectiveness reasons, the
Pt-group metals in the catalytic converter are always kept
at a minimum amount, but sufficient enough to reduce the
emission levels that meet the government regulations.
Recently, the U.S. Environmental Protection Agency
(EPA) and the California Air Resource Board (CARB) have
defined specific future targets for the reduction of emis-
sion gases of N0x, CO, and HC. For example, the target
emission levels for the 1997-2003 Ultra Low Emission
Vehicle (ULEV) are 0.04, 1.7, and 0.2 g/mile of HC, CO,
and N0x, respectively. A more stringent target, set by the
2004 ULEV2 Act, requires that the level of N0x be further
reduced to 0.05 g/mile. The current catalytic converter
technology is able to reach the 1997-2003 targets. How-
ever, it is insufficient to achieve a further decrease, by a
factor of four, in the level of N0x by the year 2004. Al-
though an obvious solution is to increase the concentra-
tions of the Pt-group metals in the catalytic converter, the
cost effectiveness eventually would become a major issue
for automobile manufacturers and catalyst vendors.
Our current research attempts to explore the possibil-
ity of using alternative catalytic materials, transition metal
carbides and oxycarbides (defined as oxygen-modified
carbides), to replace Pt-group metals for the reduction of
N0x. The carbides and oxycarbides of Groups 4-6 early
transition metals are characterized by many unique and
intriguing catalytic properties. Since the landmark paper
by Levy and Boudart regarding the Pt-like properties of
tungsten carbides, the catalytic properties of transition metal
carbides (TMC) and oxycarbides (TMOC) have been the
subject of many investigations in the fields of catalysis
and surface science. This catalysis literature has estab-
lished that the catalytic properties of TMC and TMOC
often show strong similarities to those of the more expen-
sive Pt-group metals (Ru, Rh, Ir, Pd, and Pt). hi recent
years, several surface science groups have performed
fundamental investigations of the catalytic properties of
TMC and TMOC. For example, our research group has
performed extensive studies aimed at directly comparing
the chemical reactivity of carbide surfaces with that of
Pt-group metals. The results provided conclusive evidence
that the decomposition of a variety' of hydrocarbon mol-
ecules on TMC occurs via reaction mechanisms that are
characteristic of Pt, Rh. and Pd. Furthermore, compara-
tive studies of the decomposition of NO on the bulk sur-
faces of Mo and W carbides and oxycarbides have been
performed recently. The preliminary results clearly dem-
onstrate that carbides aid oxycarbides of Mo and W are
very efficient in the conversion of the toxic NO pollutants
into the harmless N2 molecules, with catalytic activity and
selectivity' being similar or better than those of the expen-
sive Pt-group metals. Nanoparticles of TMC and TMOC
offer means of obtaining the phase and crystal surface
required for efficient NO reduction.
If successful, the replacement of Pt-group metals by
TMC or TMOC nanoparticles would offer enormous eco-
nomic incentives for the effective reduction of N0x. More
importantly, it might offer one of the more realistic ways to
achieve the N0x emission level, 0.05 g/mile, without the
use of prohibitively high priced Pt-group metal catalysts.
38
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Wolfgang M. Sigmund, Chang-Yu Wu, and David Mazyck
University of Florida, Gainesville, FL
Abstract
This project involves a multidisciplinary synthesis of
technologies to design mid fabricate smart particles that
can purify and monitor the environment. This multi-
disciplinary synthesis of technologies includes self-
organized structural control and smart materials with a
focus on environmental purification and monitoring to
create intelligent surfaces and structures that not only sense
and interact with their environment, but also can funda-
mentally alter their own behavior and deactivate them-
selves as preprogrammed or as desired. The hypothesis
to be tested is: Will nano-engineered smart particles based
on a modular building concept enable simultaneous moni-
toring and purification of the water and air environment?
The project's approach is to: (1) define and synthe-
size smart particles that purify and monitor by indicating
through a simple visible change such as color or size; (2)
make particles easily separable by auto-flocculation and/
or by magnetic removal; (3) synthesize ferromagnetic
particles with high specific surface area that increase the
specific surface area by at least two orders of magnitude
compared to current magnetic photocatalysts; and
(4) strongly reduce the mass of photocatalyst required
for treatment and further improve pollutants mass trans-
fer and exposure to UV-lighl through magnetically agi-
tated fluidization.
The expected results of the project include: (1) atomic
and molecular control of material building blocks and re-
quired engineering tools to provide the means to assemble
and utilize these tailored building blocks for assembling
novel smart particles for environmental applications as
purifiers and sensors, which are environmentally benign;
and (2) reduction of the amount of photocatalyst and an
increase in the specific surface area of magnetic photo-
catalyst composites by two orders of magnitude.
The Office of Research and Development's National Center for Environmental Research
39
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Wolfgang M. Sigmund, Chang-Yu Wu, and David Mazyck
University of Florida, Gainesville, FL
In addition to providing a better understanding of
atomic and molecular control of material building blocks,
this research project provides numerous environmen-
tal benefits. For example, future commercialization
would provide efficient water and air purification sys-
tems capable of removing pollutants to below ppm lev-
els, and provide notification when the pollutants are
removed or when the active sites are no longer avail-
able.
The smart nanoraaterials developed in this study are
significantly smaller as compared to the current particles
of a few hundred micrometers. Their greater surface
area of two orders of magnitude will provide destruction
of pollutants in fractions of the time it takes the current
particles. The magnetically agitated design can signifi-
cantly improve the contact of the particles with pollut-
ants, resulting in the reduction of reactor size. The small
size would be ideal for purification onboard the Interna-
tional Space Station (ISS), in homes, or onboard air-
planes or ocean vessels where space is a concern. The
sensing capability will result in efficient and optimized
usage of energy, with minimum extraction of natural
resources, and will prove to be beneficial to systems
where energy sources are limited.
The mixed smart particles (photocataly tic active par-
ticles plus sensing particles) will offer a novel way of
sensing and monitoring the environment. The modular
concept involving a sensing module and a photocata-
lytic module being united in one smart particle also will
open novel opportunities for sensing and monitoring. If
the modular concept (either in smart mixtures or in smart
particles) is successful, there will be a huge new field of
applications. The modular concept would allow an ex-
change of sensing units as needed. Sensing modules are
exchangeable and thus can be very specific in design
towards a molecule/organism (bactcria/virus/protcin) or
any other matter ranging in size from 5 nm to 300 nm.
In addition and perhaps most importantly, the de-
struction of pollutants is environmentally benign, focus-
ing on solving the problem rather than transferring one
pollution form for another. For example, in groundwaler
remediation, several implemented technologies transfer
a water pollution problem into an air pollution problem
(e.g., activated carbon adsorption and regeneration).
40
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
3.
Remediation - Technologies to effectively remediate environmental pollutants.
Cost-effective remediation techniques also pose a major challenge for the EPA in the development of adequate
remedial techniques that protect the public and safeguard the environment. EPA supports research that addresses new
remediation approaches that arc more effective in removing contamination in a more cost-effective manner than
currently available techniques. Substances of significant concern in remediation of soils, sediment, and groundwater,
both because of their cancer and non-cancer hazards, include heavy metals (e.g., mercury, lead, cadmium) and
organic compounds (e.g.. benzene, chlorinated solvents, creosote, toluene). Reducing releases to the air and water,
providing safe drinking water, and reducing quantities and exposure to hazardous wastes also are areas of interest.
The Office of Research and Development's National Center for Environmental Research 41
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for
of at
Dibakar Bh attach aiyy a', Leonidas G. Backus', and Stephen. M. C. Ritchie?
University of Kentucky, Lexington, KY;2University of Alabama, Tuscaloosa, AL
Abstract
The overall objective of this project is the develop-
ment and fundamental understanding of reductive dechlo-
rinalion of selected classes of hazardous organics by im-
mobilized nanosized metal particles (single and bimetallic
systems) in ordered membrane domains. This integrated
research will examine nanoparticle synthesis in a mem-
brane domain, the role of metal surface area and surface
sites, the potential role of ordered nanometal domains in
membranes, membrane partitioning, and reaction kinetics
with the main emphasis on obtaining highly enhanced
dechlorination rates and selectivity from dilute aqueous
solutions. The overall hypothesis to be tested is that
nanosized (< 50 run) zero-valent metal domains can be
created in an ordered membrane matrix by the use of
novel, polypeptide-based biomolecules with helix-coil form-
ing ability or by di-block copolymers. The specific objec-
tives are hypothesis based and will lead to greater insight
into hazardous organics dechlorination by providing a highly
.flexible membrane platform containing nanosized metals.
Some of the main hypotheses to be tested include: use of
polyfunctional metal binding ligands (such as polyamino
acids [PAA]) will lead to high loadings of nanosized reac-
tive metals in ordered membrane domains; PAA's proven
helix-forming ability will lead to ordered zero-valent metal
entrapmentfor potential dechlorination selectivity; dissolved
metals (a consequence of dechlorination reactions) can
be recaptured in these membranes and thus reused; use of
block copolymers will lead to the development of very
small size and mono-disperse nanoparticles; and mem-
brane partitioning of chlorinated organics will lead to high
reaction rates and selectivity.
The approach for this project is to examine immobilized
nanostructured metals for dechlorination of hazardous or-
ganics. The uniqueness of the project is that, in contrast to
literature reported data, membrane partitioning and in situ
synthesis of naioparticles in a membrane phase will pro-
vide highly enhanced dechlorination rates (200 to 1,000-
fold) and selectivity. This project will establish the role of
selected nanoscale particles (Fe, Zn, Pd, selected bimetallic
systems) in membrane platforms, rate of dehalogenation
reactions, and selectivity' for the formation of particular rate-
controlling intermediates, and determine the effects of
nanoparticle surface area/chemistry and membrane parti-
tioning. Significant efforts will be placed on the degradation
of TCE to its intermediates, as well as the degradation of
selected chlorinated aromatics. The specific organic degra-
dation studies in dilute solutions will include: TCE and inter-
mediates such as cis-and trans-DCE (with Fe and Zn), mono-
/dichlorophenol (bimetallic systems), and 1.2 dichloro- and
1,2,4 trichlorobcnzencs (M° - Pd nanoparticles). Because
the reductive dechlorination results (in metal particle dis-
persed solution phase) of some of these compounds are
available, direct quantitative comparisons of these mem-
brane-based nanometal systems would be possible.
The development of the proposed membrane-based
nanostructured metals synthesis for reductive dechlorina-
tion of various hazardous organics will provide a novel tech-
nique for the rapid and selective degradation of hazardous
organics at room temperature. The development of this
technology will have a significant impact on the role of
nanostructured materials in the environmental field for cur-
rent aid future needs. The fundamentally new technique
for creating environmentally applicable nanoparticles in an
ordered fashion by immobilization in a membrane matrix
provides a versatile platform to address diverse needs in
both industrial manufacturing and remediation. Kinetic mod-
eling aid correlations with molecular descriptors should
establish an excellent foundation for fundamental under-
standing of nanotechnology-based reaction systems. The
additional benefits of this work will lead to reduction of
materials usage and miniaturization of dechlorination reac-
tor svstems by more efficient use of metals and selectivity.
The Office of Research and Development's National. Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for
of at
Dibakar Bhattacharyya
University of Kentucky, Lexington, KY
Many chlorinated orgaiiics are toxic, even at low con-
centrations, and exert a cumulative, deleterious effect on
receiving streams. Chlorinated aroraatics and aliphatics
represent a class of commercially important, but particu-
larly toxic, chemicals that enter the environment from
manufacturing operations and user applications. Reduc-
tive dcchlorination of organics by various bulk metals (par-
ticularly Fe) in aqueous phase has been well documented.
This research project involving nanostructured metals
immobilized in membrane phase is expected to have sig-
nificant positive impact on pollution remediation through
compact and flexible dechlorination technology develop-
ment with high reaction rates at room temperature, sig-
nificant reduction of metals usage, waste minimization
through possible recover}- of nonchlorinatedproducts (i.e..
cthylcnc from TCE), and improvement in water quality.
The use of nontoxic. polypeptide-based membrane as-
semblies to create nano-sized metal domains has signifi-
cant environmental importance.
Although nanoparticles possess several advantages
(i.e.. high surface area and surface energy), sustainability
requires particle immobilization to avoid particle loss,
agglomeration, and broad size distribution. The funda-
mentally new technique—creating environmentally ap-
plicable nanoparticles in an ordered fashion by immobili-
zation in a membrane matrix—provides a versatile plat-
form to address diverse needs in both industrial manu-
facturing and remediation. The benefits of this work will
lead to a reduction of materials usage and miniaturization
of dechlorination reactor systems through more efficient
use of metals and selectivity. Selective sorption of model
organics and their intermediates should minimize com-
peting reactions with natural hydrophilic solution com-
ponents (e.g., nitrate reaction with zero-valent metals).
Another benefit includes simultaneous organic dcchlori-
nation and recapture of reacted metals (as a consequence
of dechlorination) by polypeptide acid groups in a com-
posite material. Thus, higher value metals providing en-
hanced selectivity could be incorporated, thereby mak-
ing the process environmentally sustainable.
The discharge and leaching (from contaminated soil)
of chlorinated organic pollutants to various surface and
groundwater is an area of considerable concern in terms
of degradation of water quality. Chlorinated organics and
many pesticides/herbicides are toxic to aquatic life, even
at low concentrations, and exert a cumulative, deleteri-
ous effect on receiving streams. Thus, research dealing
with highly improved reductive dechlorination techniques
should lead to substantial improvement in environmental
quality.
44
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Mamadou S. Diatto'-3, Lajos Balogh2, William A. Goddard'IIP, and James H. Johnson, Jr.'
'Howard University, Washington, DC; 2The University of Michigan, Ann Arbor, MI; 3Califorma Institute of
Technology, Pasadena, CA
Abstract
Dendrimers are monodisperse and highly branched
nanostructures with controlled composition and archi-
tecture. Poly(ainidoamine) (PAMAM) dendriiners pos-
sess functional nitrogen and amide groups arranged in
regular "branched upon branched" patterns. This high
density of nitrogen ligands enclosed within a nanoscale
container makes PAMAM dendrimers particularly attrac-
tive as high capacity chelating agents for toxic metal
ions [Cu(II)], electron transfer mediators [Fe(II)], rc-
dox active metal clusters [FeS], and metal clusters with
catalytic properties [Pt (11) j. PAMAM dendrimers also
can be functionalized with surface groups that make them
soluble in appropriate media or bind onto appropriate
surfaces. This project explores the fundamental science
of metal ion uptake by PAMAM dendrimers in aqueous
solutions and assesses the extent to which this funda-
mental knowledge can be used to develop: (1) high ca-
pacity and reusable chelating agents for industrial and
environmental separations; and (2) FeS laden nanoparticles
with enhanced reactivity, selectivity, and longevity for
reductive detoxification of perchloroethylene (PCE) in
aqueous solutions and subsurface formations.
To achieve these objectives, an integrated project will
be used that combines: (1) materials synthesis and char-
acterization; (2) bench-scale measurements of metal ion
[Cu(II), Fe(II), Co(II), Ni(II), Cd(II), and AgQ] uptake
by PAMAM dendrimers in aqueous solutions; (3) x-ray
absorption spectroscopic (XAS) investigations of metal
ion-PAMAM dendrimer complexes in aqueous solutions;
(4) bench-scale measurements and spectroscopic inves-
tigations of the reduction of PCE by water soluble FeS-
PAMAM dendrimer nanoconiposites and solid particles
coated with FeS-PAMAM dendrimer nanoconiposites;
and (5) molecular modeling of (a) metal ion uptake by
PAMAM dendrimers in aqueous solutions and (b) PCE
reductive dechlorination by FeS clusters.
The successful completion of this research is ex-
pected to result in: (1) more effective functional materi-
als for recovering precious metal ions [e.g., Ag(I)] and
toxic metal ions [e.g., Cu(ll)| from industrial wastewa-
ter solutions by low cost membrane-based processes
[e.g., ultrafiltration]; and (2) more effective reactive me-
dia for reductive detoxification of PCE in aqueous solu-
tions and subsurface fonnations.
The Office of Research and Development's National Center for Environmental Research
45
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Mamadou S. Diatto'-3, Lajos Balogh2, William A. Goddard'IIP, and James H. Johnson, Jr.'
'Howard University, Washington DC; 2Universify of Michigan, Ann Arbor, MI;
California Institute of Technology, Pasadena, CA
Environmental
Dendriiners are monodisperse and highly branched
nanostructiires with controlled composition and archi-
tecture. Poly(amidoamine) (PAMAM) dendrimers pos-
sess functional nitrogen and amide groups arranged in
regular "branched upon branched" patterns as a func-
tion of generation level (see Figure 1).
This high density of nitrogen ligands enclosed within a
nanoscale container makes PAMAM dendrimers particu-
larly attractive as high capacity chelating agents for toxic-
metal ions [Cu(ll)], electron transfer mediators [Fe(ll)],
redox active metal clusters [FeS], and metal clusters with
catalytic properties [Pt (II)]. PAMAM dendrimers also
can be fuiictionalized with surface groups that make them
soluble in appropriate media or bind onto appropriate sur-
faces. This project explores the fundamental science of
metal ion uptake by PAMAM dendrimers in aqueous solu-
tions and assesses the extent to which this fundamental
knowledge can be used to develop: (1) high capacity and
reusable chelating agents for industrial and environmental
separations; and (2) redox active Fe laden nanoparticles
for environmental detoxification.
Although macrocyles and their "open chain" analogues
(unidentate and polydentate ligands) have been shown to
form stable complexes with a variety of metal ions, their
limited binding capacity (i.e., 1:1 complexes in most cases)
is a major impediment to their utilization as high capacity'
chelating agents for industrial and environmental sep-
arations.Their relatively low molecular weights also pre-
clude their effective recovery from solutions by low-
cost membrane-based techniques (e.g.. ultrafiltration).
During Phase I of this project, dendrimers are being
evaluated as high capacity chelating agents for transition
metal ions in aqueous solutions. Our research shows
that, in aqueous solutions, PAMAM dendrimers can serve
as high capacity chelating agents for a variety of transi-
tion metal ions, including Cu(II). Fe(II). aid Ag(l).
A variety of organic and inorganic pollutants are not
easily degraded to less toxic compounds in oxic envi-
ronments. These include chlorinated alkenes (e.g., per-
chloroelhylene [PCE]), poly(nitroaromatics) (e.g., 2, 4,
6-trinitrotoluene [TNT]), and Cr(VI). Most of these com-
pounds may, however, undergo rapid reductive trans-
formations to less toxic products in anoxic environments.
Reactive media such as Fc(0) and FeS that promote such
transformations under reducing conditions are being used
increasingly as functional materials to develop in situ
permeable reactive barriers (PRB) and packed bed reac-
tors for remediation of groundwater and surface water.
Dendritic nanoscale chelating agents provide unprec-
edented opportunities for synthesizing high surface areametal-
ladcn nanoparticles by reactive encapsulation (see Figure 2).
Phase II of this project will synthesize and character-
ize water-soluble and solid supported FeS laden dendrimer
nanocomposites (DNCs) with tunable redox activity. The
ability of these nanoparticles to reduce PCE in aqueous
solutions will be evaluated. The successful completion of
this research is expected to result in: (1) more effective
functional materials for recovering or removing precious
metal ions [e.g.. Ag (I)] or toxic metal ions [e.g.. Cu (II)]
from industrial wastewatcr solutions by low-cost, mem-
brane-based processes (e.g., ultrafiltration); and (2) more
effective reactive media for reductive detoxification of
chlorinated compounds (e.g., PCE) in aqueous solutions
and subsurface formations.
46
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
iFHE RATION * 31 •* #t i
Figure 1. Structures of PAMAM dendrimers with ethylene diamine core and tenninal NH groups.
+x
_ \
ssn;^ -1 no rtf;:i n j c
Figure 2. Synthesis of dendrimer nanocomposites by reactive encapsulation.
The Office of Research and Development's National Center for Environmental Research 47
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of for Cr(VI)
Daniel R. Strong'm1, Ivan Kim1, Hazel-Ann Hosein', Trevor Douglas2,
and Martin A. A. Schoonen3
'Temple University, Philadelphia;2Montana State University, Bozeman, MT;
3State University of New York-Stony Brook, Stony Brook, NY
Abstract
Ferritin. which is an iron storage protein, was used
to catalyze the photo-reduction of aqueous Cr(VI) spe-
cies to Cr(III). Ferritin is a 24 subuiiit protein of roughly
spherical shape with outer and inner diameters of ap-
proximately 12 and 8 nm, respectively. The native min-
eral core of ferritin is the ferric oxyhydroxide ferrihydrite
[Fe(0)OH]. Fe(0)OH particles, which ranged from 5 to
7.5 nm in diameter, were used in the experiments. Under
the experimental conditions, the ferritin protein without
the Fe(0)OH core (i.e., apoferritin) was inactive toward
Cr(Vl) reduction, suggesting that the Fe(0)OH provided
the active catalytic sites in the redox chemistry. Experi-
ments using photon band-pass filters suggested that the
reaction occurred out of a photo induced electron-hole
pair and the optical band gap for the Fe(0)OH semicon-
ductor was determined to be in the range of 2.5 to 3.5 cV.
Comparison of ferritin and protein-free Fe(0)OH mineral
nanoparticles indicated that ferritin provided a photocata-
lyst with significantly more stability to aggregation and the
loss of catalytic activity.
48
'lite Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of for Cr(VI)
Daniel R. Strongm
Department of Chemistry, Temple University, Philadelphia, PA
This research project is a mullidisciplinary effort to
develop a firm understanding of the properties of nano-
sized metal oxide compounds within the protein shell (or
cage) of the iron storage protein, ferritin (spherical with a
120 D diameter) (sec Figure 1). These systems arc unex-
plored in terms of their potential use in remediation pro-
cesses or as a method for synthesis of nanoscale particles
of metal compounds. The entire system, consisting of the
inorganic core material and protein shell, provides oppor-
tunities to develop new catalysts for beneficial environ-
mental chemistry by manipulating the composition and
size of the core material, as well as chemically func-
tionalizing the surrounding protein shell.
The proposed bioengineering approach will investi-
gate the reactivity of a variety of metal oxides, such as
Fe(0)OH, Co(0)OH, and Mn(0)OH with variable nano-
dimensions that may have great potential benefits to
chemical and photochemical remediation schemes (see
Figure 1). Both the thermal chemistry and photochemis-
try of the particles toward the degradation of aromatics
and chlorocarbons, as well as the particles rcdox chem-
istry, will be probed. These materials are ubiquitous com-
ponents of soils, aquatic systems, and related environ-
ments, and have found uses in remediation strategies,
but not at the nanoscale. Furthermore, results demon-
strate the ability to reduce the metal oxide core of ferritin
to yield nano-sized zero valent metal particles. Hence,
our bioengineering approach yields a synthetic route to
well-defined nano-metal particles for environmental
chemistry. At least one prior impediment to fully investi-
gating and ultimately testing the utility of nano-struc-
tures has been the difficulty that their preparation and
stabilization presents. Our bioengineering approach ad-
dresses and helps circumvent these difficulties in an en-
vironmentally benign and biodegradable system. The low
band gap energy of most Fe(IIl) bearing iron oxides
allows them to harness a significant amount of the solar
spectrum to carry out photochemical processes. Because
of their attractive semiconductor properties and low cost,
iron oxides have been investigated as photocatalysts for
the degradation of environmental toxins (e.g., chlorocarbons
and metals). Their potential use, however, is limited; they
undergo photoreduction (i.e., conversion of Fe(III)to
Fe(H)), resulting in the deterioration of the catalytic particle.
This research encapsulates the nano-catalyst in a pro-
tein cage that stabilizes the iron oxide against photoreduc-
tion. Because ferritin is engineered by nature to convert
Fe(II) to Fe(III, it is hypothesized that any Fe(II) pro-
duced by photoreduction will be rapidly converted back
to Fe(IlI) in the presence of 02. This stabilization by the
protein shell will be a significant advantage over, for ex-
ample, a freestanding iron oxide particle photocatalyst.
Although the protein cage stabilizes the core, its presence
still allows the iron oxide core to drive important environ-
mental chemistry. Our laboratory has demonstrated, for
example, that photoexcited ferritin mediates the rapid re-
duction of toxic Cr(VI) to the immobile Cr(III) species.
Figure 1. A schematic of the synthetic routes to
different nanoparticles. A variety of other
oxides can be assembled within the
protein cage of ferritin (cross-sectional
view shown).
The Office of Research and Development's National Center for Environmental Research
49
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for In
Wei-xian Zhang
Lehigh 'University, Bethlehem, PA
Abstract
Nanoscale bimetallic (Fe/Pd, 99.9% Fe) particles are
among the vanguard of a new generation of remediation
technologies that could provide cost-effective remedial
solutions to some of the most difficult sites. Nanoparticles
feature large surface areas and extremely high surface
reactivity. Equally important they provide enormous flex-
ibility for in situ remedial applications. The primary goal
of this research is to continue the research and develop-
ment of the nanoscale bimetallic particle technology for
in situ remediation.
Several key technical issues of the nanoscale bime-
tallic particle technology will be investigated—the most
important being the optimization and scaleup of the syn-
thesis processes. A system will be built with the capacity
to synthesize 500 to 1.000 grams of nanoparticles per
day. The major experimental tasks include: (1) synthesis
of various nanoscale particles (Fe/Pd, Fe/Ag. Fe/Ni, Fe/
Co, Fe/Cu, etc.); (2) feasibility studies (batch and col-
umn) of treatment of perchlorate (C104~) and chromium
(Cr(VI)) with various nanoparticles; (3) batch and col-
umn studies of treatment of mixed wastes, including
organic solvents and heavy metals; and (4) modeling
and column studies of injection, transport, and reactions
of nanoparticles in porous media.
The complete reduction of aqueous perchlorate to
chloride by nanoscale iron particles over a wide concen-
tration range (1 -200 mg/L) has been observed. The re-
action is temperature sensitive as evidenced by progres-
sively increasing rate constant values of 0.013, 0.10,
and 1.52 mg perchlorate per g iron per hour, respec-
tively, at temperatures of 25 °C, 40 °C, and 75 °C. The
large activation energy of 79.02 ± 7.75 kJ/mole partially
explains the stability of perchlorate in water. Iron
nanoparticles may represent a feasible remediation alter-
native for pcrchloratc-contaminatcd groundwaters, an
environmental concern of growing importance. In a more
general sense, the results illustrate the profound impact
of particle size in surface mediated reactions.
The results of this research will provide insight and
information that are essential for: (1) cost-effective pro-
duction of the nanoparticles in large quantity; (2) poten-
tial applications of the nanoparticles for in situ remediation;
and (3) education of students in environmental nanotech-
nologies.
50
'lite Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
for In
Wei-xlan Zhang
Lehigh 'University, Bethlehem, PA
Nanoscalc bimetallic (Fc/Pd, 99.9% Fc) particles arc
among the vanguard of a new generation of remediation
technologies that could provide cost-effective remedial
solutions to some of the most difficult sites. Nanoparticles
feature large surface areas and extremely high surface
reactivity. Equally important, they provide enormous .flex-
ibility for in situ remedial applications. The primary goal
of this research is to continue the research and develop-
ment of the nanoscale bimetallic particle technology for
in situ remediation.
Several key technical issues of the nanoscale bi-
metallic particle technology will be investigated, the
most important being the optimization and scaleup
of the synthesis processes. A system will be built with
the capacity to synthesize 500-1,000 grams of
nanoparticles per day. Major experimental tasks include:
(1) synthesis of various nanoscale particles (Fc/Pd, Fc/
Ag, Fe/Ni, Fe/Co, Fe/Cu etc); (2) feasibility studies
(batch and column) of treatment of perchlorate (C104~)
and chromium (Cr[VI]) with various nanoparticles;
(3) batch and column studies of treatment of mixed
wastes, including organic solvents and heavy met-
als; and (4) modeling and column studies of injec-
tion, transport, and reactions of nanoparticles in po-
rous media.
The complete reduction of aqueous perchlorate to
chloride by nanoscale iron particles over a wide concen-
tration range (1-200 mg/L) has been observed. The reac-
tion is temperature sensitive as evidenced by progressively
increasing rate constant values of 0.013, 0.10, and 1.52
mg perchlorate per g iron per hour, respectively, at tem-
peratures of 25 °C, 40 °C, and 75 °C. The large activation
energy of 79.02 ± 7.75 kJ/molc partially explains the sta-
bility of perchlorate in water. Iron nanoparticles may rep-
resent a feasible remediation alternative for perchlorate-
contaminated groundwaters, an environmental concern
of growing importance. In a more general sense, the re-
sults illustrate the profound impact of particle size in sur-
face-mediated reactions.
It is apparent that nanotechnology—the science and
art of manipulating matter at the atomic and molecular
level—has the potential to substantially enhance environ-
mental quality and sustainability through pollution pre-
vention, treatment, and remediation. Potential benefits
include improved detection and sensing techniques, re-
moval of the finest contaminants from air, water, and
soil, and the discover}- of new "green" industrial pro-
cesses that reduce waste products.
This research assesses the environmental implications
of nanotechnology with emphasis on research and devel-
opment of new nanotechnologies for treatment and
remediation. The results of this research will provide valu-
able information that is essential for: (1) cost-effective
production of the nanoparticles in large quantity;
(2) applications of the nanoparticles for in situ remedia-
tion; and (3) education of students in environmental nano-
technologies.
It is expected that results obtained from this research
will provide insights into the potential environmental fate
and transport of environmental nanoparticles. It is largely
unknown how nanostructured materials and other re-
lated nanotechnologies might affect human health and
interact with the environment. The eventual proliferation
and use of nanotechnology could cause unintended con-
sequences such as the creation of new classes of toxins
or related environmental hazards.
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
4.
Other Areas - Technologies to develop new processes and belter understand existing ones.
Nanotechnology has the potential to be used to develop new '"green" processing technologies that minimize or
eliminate the use of toxic materials and the generation of undesirable by-products and effluents. Research may
involve nanotechnology related to improved industrial processes and starting material requirements, development of
new chemical and industrial procedures, and materials to replace current hazardous constituents and processes,
resulting in reductions in energy, materials, and waste generation. This research could focus on the chemical,
electronic, or other sectors of the economy.
Potential examples of types of nanoteclinology research that may lead to reduction or elimination of pollutants of
concern include atomic-level synthesis of new and improved catalysts for industrial processes; adding information
into molecules (analogous to DNA) that build new molecules; self-assembling molecules as the foundation for new
chemicals and materials; and building molecules "just in time" in rnicroscale reactors.
EPA also is interested in furthering the scientific understanding of the microphysical phenomena of aerosol particles.
This will provide better data for models used in atmospheric and stratospheric particle concentration predictions.
Such understanding will lead to protection of human health in terms of providing mechanisms for minimizing respi-
ratory health effects, as well as providing protection from stratospheric ozone depletion that results from particle
deposition on cloud condensation nuclei (CCN).
The Office of Research and Development's National Center for Environmental Research 53
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
TiO2 as a
for
George Chumanov
Clemson University, Clentson, SC
Abstract
Efficient conversion of sunlight into electrical and/or
chemical energy is of great technological importance for
modern society and future generations. One possibility
for utilization of solar energy is based on the ability of
small semiconductor particles to Function as photocatalysts
promoting various oxidation and reduction reactions un-
der sunlight. Titanium dioxide (Ti02) is the most promis-
ing material for such applications because it is an efficient,
environmentally friendly, and relatively inexpensive pho-
tocatalyst. However, wide technological usage of this pho-
tocatalyst is largely hindered because ultraviolet light does
not constitute a significant fraction of the solar spectrum
that is required for its activation. Any improvement of
photocatalytic efficiency of Ti02 by shifting its optical
response from U V to the visible spectral range will have a
profoundly positive effect. The main objective of the pro-
posed research is to synthesize and test a novel photo-
catalyst that consists of small silver or gold nanoparticles
covered with a thin Ti02 shell. Silver and gold nanoparticles
arc very efficient systems for the interaction with \isiblc
light due to the excitation of plasmon resonances. It is
expected that, due to the coupling of plasmon resonances
in the core with the electron-hole pair generation in the
shell, these hybrid Ag/Au TiO, nanoparticles will exhibit
photocatalytic activity in the visible spectral range, thereby
more efficiently utilizing solar energy.
Coating of silver and gold nanoparticles of different
sizes with TiO, layers of various thickness will be ac-
complished by sol-gel chemical reactions. High tempera-
ture calcination and hydrothermal treatment will be used
to convert amorphous Ti02 layers into the anatase form.
Other hybrid nanoparticles include open Ti02 shell around
metal cores, hollow TiO, nanoparticles. and Ag/Au@Ti02
particles with small RuO, and Pt clusters attached to
their surface. All particles will be characterized by UV-
Vis absorption, luminescence and Raman scattering spec-
troscopy, electron and scanning tunneling microscopy,
and x-ray diffraction. The photocatalytic activity of hy-
brid nanoparticles will be assessed in model experiments
using photoreduction of methylviologen and photocata-
lytic degradation of 4-chlorophcnol.
Ag/Au@TiO, particles represent anew system with
unknown chemical and physical properties.These
nanoparticles will exhibit enhanced photocatalytic activ-
ity as compared to TiO., conventional catalyst. This new
material will have positive impact on the development of
new solar based technologies including (photo)remediation
of environmental pollutants, photovoltaic cells, photo-
chemical splitting of water, and artificial photosynthesis.
The synthetic approaches developed for the preparation
of Ag/Au@Ti02 hybrid nanoparticles particles can be
extended to include other metals and semiconductors.
The proposed research will answer the fundamental ques-
tion about the possibility of utilization of energy stored in
the form of plasmon resonances in metal nanoparticles
to carry different chemical reactions.
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
TIO2 as a
for
George Chumanov
Clemson University, Clentson, SC
Environmental Benefits
Efficient conversion of sunlight into electrical aid/or
chemical energy is of great technological importance for
modern society and future generations. Intensive research
in this field in recent decades resulted in the fundamental
understanding of principles that govern photochemical
reactions. This knowledge provides a strong foundation
for the development of an artificial photosynthetic system
of practical significance. One attractive possibility is to
use the photoinduced heterogeneous electron transfer from
small semiconductor particles to drive different oxidation
and reduction reactions. Titanium dioxide (TiO,) is con-
sidered the most technologically promising material for
these applications because it is an environmentally friendly.
relatively inexpensive, and potentially efficient photocata-
lyst. However, the photocatalytic activity of TiO, requires
the scnsitization with ultraviolet radiation that comprises
only a small portion of the solar spectrum; thereby limiting
the solar efficiency of this material.
The main objective of this proposed research is to
develop a novel hybrid photocatalyst that consists of sil-
ver or gold nanoparticles encapsulated into Ti02 shell
(Ag/Au@TiO,). Silver and gold nanoparticles are very
efficient systems for capturing energy from the visible
portion of the spectrum due to the excitation of plasm on
resonances. Thus, the hybrid Ag/Au@TiO, nanoparticles
will utilize solar energy for photochemical reactions more
efficiently than bare TiO,.
It is expected that the development of this novel photo-
catalyst will have a positive impact on the advancement of
new, solar-based, environmentally friendly technologies. For
example: (1) The hybrid photocatalysts will be used for
photochemical destruction of the environmental pollutants,
polych formated phenols. Photooxidation of these pollutants
using bare TiO, particles was successfully accomplished in
the field under solar illumination. However, low solar effi-
ciency of these photocatalysts limits its wide practical ap-
plication. (2) Based on Ag/Au@Ti02 nanoparticles, more
procedures will be developed for photoremediation of a wide
range of organic and inorganic pollutants such as in the
removal of heavy metals in purification of water by sun-
induced photoreduction processes. (3) This hybrid photo-
catalyst can be used for producing oxygen and hydrogen
from water using solar energy. It is difficult to overempha-
size the importance of hydrogen-powered technologies for
the future. A vivid example is hydrogen-powered cars, an
area of Research & Development, in which governments
aid the private sector around the world put a great deal of
effort aid resources. (4)Ag/Au@TiO, hybrid nanoparticles
have a potential for the photovoltaic devices capable of di-
rect conversion of solar energy into electricity. Devices us-
ing Ti02 nanoparticles sensitized with organic chromophores
already have proven to be very efficient for photovoltaics.
However, their lifetime and durability is limited by
photobleaching of organic molecules under prolonged solar
irradiation. This problem is expected to be eradicated for
Ag/Au@Ti(X nanoparticles in which the inorganic metal
core functions as a light-capturing chromophoric species.
(5) Ag/Au@Ti02 nanoparticles representnew systems with
unknown chemical and physical properties. Further explo-
ration of these materials may result in novel application
in other areas such as photonics and microelectronics.
(6) The synthetic approaches developed for the preparation
of Ag/Au@Ti02 hybrid nanoparticles can be extended to
include other metals and semiconductors. Other hybrid/
semiconductor nanoparticles also may find applications in
various environmentally friendly, photochemical, solar tech-
nologies. The development of Ag/Au@TiO, nanoparticles
signifies anew field in material science with wide possibili-
ties for practical developments. (7) Finally, this proposed
study addresses the fundamental question about utilization
of optical energy stored in the form of plasmon resonaicc
for carrying various chemical reactions.
In summary, the potential impact of this research re-
lates to the advancement of currently existing technologies
and the development of new solar technologies, including
photoremediation of environmental pollutants, direct con-
version of solar energy into electricity in photovoltaic de-
vices, and splitting water to oxygen and hydrogen.
56
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
as
to
Sarah C. Larsen and Vickl H. Grassian
University of Iowa, Iowa City, IA
Abstract
This proposal describes the development of nanom-
eter-sized zeolites and zeolite nanostructurcs as environ-
mental catalysts. Zeolites, which are widely used in ap-
plications in separations and catalysis, are aluminosilicate
molecular sieves with pores of molecular dimensions.
The crystal size of zeolites formed during conventional
synthesis range in size from 1,000 to 10,000 nm. How-
ever, for some applications it would be advantageous to
employ much smaller nanometer-sized zeolite crystals,
in the range of 10 to 100 nm. Specific advantages to be
gained by using zeolite nanostnicturcs include facile ad-
sorption and desorption. the ability to form dense films
to facilitate separations applications, and optical trans-
parency. The proposed project has two hypotheses:
(1) the properties of zeolites with respect to reactant and
product diffusion and light scattering can be significantly
improved by using nanometer-sized zeolites and
nanostructurcs (fibers or thin films); (2) these zeolite
nanostructures will be superior materials for applications
in heterogeneous environmental catalysis.
To test the hypotheses, a two-pronged approach
based on the synthesis and application of nanozeolites as
environmental catalysts, is envisioned. The objectives of
the proposed project are to: (1) synthesize and charac-
terize nanometer-sized zeolites (X, Y, ZSM-5, Beta) and
nanostructures (films, fibers); (2) determine the effec-
tiveness of nanometer-sized zeolites for applications in
environmental catalysis, such as environmentally benign
selective oxidation reactions in cation-exchanged zeo-
lites, N0x emission abatement, and photocatalytic de-
composition of organic contaminants; and (3) investi-
gate intrazeolite reactions using in situ spectroscopic
methods, such as FTIR and solid state NMR spectros-
copy.
The development of nanozeolites for applications in
heterogeneous catalysis potentially can lead to solutions
of several important environmental problems. These
problems span from new methodologies in environmen-
tally benign synthesis to new methodologies in environ-
mental remediation. The results of these studies (e.g.,
the relationship between the properties of the nanozeolites
and catalytic activity) are not limited to the reactions
studied here. The results should extend to other types of
catalytic reactions and should be important in other ap-
plications of environmental catalysis and environmen-
tally benign synthesis.
The Office of Research and Development's National Center for Environmental Research
57
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
as
to
Sarah C. Larsen and Yicki H. Grassian
University of Iowa, Iowa City, LA
Environmental
Environmental catalysis involves the use of catalysts to
solve environmental problems, in areas such as emission
abatement and environmentally benign synthesis. Many new
catalysts and catalytic processes have been developed to
meet the challenges posed by environmental concerns. Re-
cently, zeolites have emerged as important materials for ap-
plications in environmental catalysis. Zeolites are alumino-
silicatc molecular sieves with pores of molecular dimensions.
Zeolites can be synthesized with a wide range of pore sizes
and topologies and are used in applications such as catalysis
and chemical separations. The crystal size of zeolites formed
during conventional synthesis range from 1.000 to 10.000
nm. However, for some applications it would be advanta-
geous to employ much smaller nanometer-sized zeolite crys-
tals ranging from 10 to 100 nm. Specific advantages to be
gained by using zeolite nanostructures include facile ad-
sorption aid desorption, the ability to form dense films to
facilitate separations applications and optical transparency.
Several applications of nanometer-sized zeolites to environ-
mental catalysis are described in the paragraphs that follow.
The partial oxidation of hydrocarbons is significant to
the chemical industry because the products are used to
convert petroleum hydrocarbon feedstocks into chemi-
cals important in the polymer and petrochemical indus-
tries. Liquid phase air oxidations generally are preferred
by the chemical industry because of the mild reaction con-
ditions. The conversions of the oxidation processes are
typically very low to maintain high selectivity. This is nec-
essary for the desired partial oxidation products to be fur-
ther oxidized easily under typical reaction conditions. A
major motivation for the development of new oxidation
routes is the desire to achieve high selectivities at high
conversions. These factors, combined with the emphasis
on cleaner and safer processes, provide the context for
the proposed studies.
This approach of this project to the partial oxidation of
hydrocarbons is to eliminate the use of organic solvents
through the use of gas phase reactants and products. A
clean, inexpensive oxidant, molecular oxygen is used in
these reactions. Thus, these reactions have the potential
to be green processes that use no solvents and minimal
energy with catalysts (i.e., zeolites) that have been used in
industry for many years.
Light scattering by the zeolite is a major obstacle to its
use as environmentally benign photooxidation catalysts. In
previous photooxidation work, it was found that the yield
of photooxidation reactions in zeolites strongly depends on
the thickness of the zeolite layer. The efficient use of light
energy in zeolites requires that light is able to propagate
through a long path of zeolite material. However, zeolite
crystallites strongly scatter visible light due to their small
dimension. Thus, only a thin photoreactive zone is obtained
regardless of the zeolite bed thickness. This project uses
coated optical fibers, zeolite fibers, and hollow fibers to
increase the photoactive region of the zeolite sanple.
The emission of N0x and N,0 from stationary and
automotive sources, such as power plants and lean-
burn engines, is a major environmental pollution issue.
N0x leads to the production of ground-level ozone and
acid rain, and N20 is a greenhouse gas. The catalytic re-
duction of nitrogen oxides to N2 is an important environ-
mental challenge for scientists and engineers. Recently,
the selective catalytic reduction of N0x and N,0 by hy-
drocarbons (SCR-HC) over transition-metal exchanged
zeolites, particularly in the presence of oxygen, has at-
tracted much interest for emission abatement applications
in stationary sources such as natural gas fueled power
plants. SCR-HC of N0x and'N20 show promise for appli-
cations to lean-bum gasoline and diesel engines where
noble-metal three-way catalysts are not effective at re-
ducing N0x in the presence of excess oxygen. Another
aspect of these transition metal-exchanged zeolites that
has been reported in the literature is the photocatalytic
activity for the direct decomposition of N0x aid N,0 and
the SCR-HC of N0x. The use of zeolite nanostructures
would provide some advantages similar to those discussed
for the oxidation reactions such as more efficient light
absorption, reactant diffusion, aid increased surface area.
Coating transparent objects, such as windows, with trans-
parent zeolite thin films may be an important application
for these materials. The zeolite thin film would then be
activated for NO. decomposition by sunlight.
58
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
The last system to be investigated involves the photo-
catalytic oxidation (PCO) of volatile organic compounds
(VOCs). Photocatalysts, such as Ti02, can be used to
degrade a wide range of organic compounds found in
polluted water and air. Much of the research in the last
decade has focused on aqueous solution photocatalysis
for the decontamination and purification of water. How-
ever, gas phase heterogeneous photocatalysis can be an
effective way to remove undesirable organic contaminants
from air. TiO, photocatalysis are active at ambient tem-
peratures and pressures in the presence of UV irradiation
and oxygen. Potential applications include purifying en-
closed atmospheres such as those found in spacecrafts,
offices, industrial plants, and homes. The major pollutants
in these applications are oxygenates and aromatics. Ti02
photo-catalysts have been shown to oxidize toluene, trichlo-
roethylene (TCE), methanol/ethanol, and a number of other
organic compounds. The use of nanometer-sized zeolite
Ti02 composites and nanometer-sized Ti02 will be evalu-
ated for applications in environmental remediation.
The Office of Research and Development's National Center for Environmental Research
59
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Peter H. McMurry'and Fred Eisele2
'University of Minnesota, Minneapolis, MN;2 Georgia Tech Research Corporation,
Atlanta, GA
Abstract
This project will study the role of ion-induced nucle-
ation as a mechanism for producing new nano-sized par-
ticles in the atmosphere. The hypotheses are that: (1) nucle-
ation processes in different locations are driven by different
gas phase species and can be homogeneous aid/or ion-
induced depending on time and locale; aid (2) ion-induced
nucleation events can be due to the growth of either positive
or negative ions, and different gas phase species are re-
sponsible for bursts of intermediate aid large positive and
negative ions. The ultimate goal is to develop experimentally
verified models for the formation of ultrafine atmospheric
particles by nucleation.
This study will include both laboratory aid field re-
search aid will involve the measurement of ion mobility
spectra (nominal ion sizes 0.4 to 15 nm) and ion compo-
sition. Ion composition will be measured by tandem mass
spectrometry, and will include measurements of both posi-
tive and negative ion composition during nucleation events,
which has not previously been done. Amicrophy sical model
to interpret the data will be developed. This model will
attempt to reconcile observed time-dependent trends in
ion mobility distributions and aerosol charge distributions.
Recent cpidcraiological research has suggested that,
on a mass basis, ultrafine particles can be more harmful
to human health than larger particles. Furthermore,
ultrafine particles formed by nucleation can grow into
cloud condensation nuclei that can impact on the earth's
radiation balance. This project complements other on-
going research in our laboratories that is focused on the
homogeneous nucleation by reactions of neutral mol-
ecules in the atmosphere. The results of this study will
be useful to modelers, who require experimentally veri-
fied models of microphysical processes to evaluate aerosol
climatic effects, human exposure, etc.
60
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Peter H. McMurry
University of Minnesota, Minneapolis, MN
Environmental Benefits
It is necessary to understand nucleation to establish
the relationship between anthropogenic and biogenic
emissions and atmospheric aerosol effects, including
their effects on human health and global climate. Nucle-
ation, for example, can produce high concentrations of
very small particles, and recent toxicology research has
shown that at a given mass concentration, particles in
the 20 nm diameter range have a much greater impact
on the lung function of laboratory test animals than ap-
proximately 200 nm particles. Nucleated particles also
can grow into cloud condensation nuclei (CCN), and
can thereby affect precipitation patterns and albedo. Un-
derstanding such raicrophysical phenomena is essential
to develop valid models for predicting atmospheric aero-
sol size distributions and the effects of aerosols on the
environment.
This research project focuses on measurements
pertinent to ion-induced nucleation. Whether or not ion-
induced nucleation actually occurs will be determined, and
if so, what species participate. Measurements of ion com-
position by mass spectrometry will provide the required
information on participating species, and measurements
of ion mobility spectra in the 0.5 to 5 nm diameter range
will provide quantitative information on rates at which
particles are formed by ion-induced nucleation.
With separate funding, the formation of new particles
by homogeneous nucleation (i.e., by the spontaneous nucle-
ation of low-vapor pressure neutral molecules) is being stud-
ied. Such homogeneous nucleation processes do not in-
volve the participation of ions. The work from these studies
will be combined to determine the relative roles of homoge-
neous and ion-induced nucleation in different environments.
The Office of Research and Development's National Center for Environmental Research
61
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
Barrett Velegol and Kristen Fichthom
Pennsylvania State University, University Park, PA
Abstract
Nanotechnology will be critical to advances in elec-
tronics, materials, medicine, and the environment. This
is due to their remarkable electronic, optical, magnetic,
and mechanical properties. However, a significant limi-
tation of nanotechnology is the ability to produce bulk
quantities of dispersed particles. One possibility for dis-
persing nanoparticles, which have a high area/mass ra-
tio, is to use adsorbed polymer, oligomer, or surfactant
molecules; however, disposal of the enormous quantity
of additives would involve huge environmental and fi-
nancial stresses. The expected engineering breakthrough
of the proposed research is to identify whether solvation
or depletion forces can be manipulated to produce dis-
persed suspensions of "bare" nanoparticles (i.e.. with-
out adsorbed additives).
This research project will address two central ques-
tions: (1) What are the magnitudes of the van der Waals,
solvation, and depletion forces for nanoparticle systems?,
and (2) What variables can we control to alter these forces?
To obtain measurements that can answer these questions,
the experimental technique of "particle force light scatter-
ing" is being developed. This is an experimental method
for measuring sub-piconewton nanoparticle forces. This
development requires solutions to the electrokinetic equa-
tions and the development of a Rayleigh scattering device
to measure aggregate breakup. The oral presentation will
emphasize: (1) how the electrokinetic theory has been ex-
tended to account for triplets, which will be used in the
forthcoming scattering experiments; and (2) the results
from the force measurements.
The interpretation of the measurements is being con-
ducted using molecular dynamics (MD) simulations. MD
simulations are used to characterize the interaction be-
tween two model nanoparticles (Lennard-Jones Au sol-
ids) immersed in solvent (Lennard-Jones spheres, n-al-
kanes, and water). Initial results compare solvation forces
to van der Waals forces, showing that solvation forces
might indeed be used to stabilize particles.
62
'lite Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
Darrell Vdegol
Pennsylvania State University, University Park, PA
Environmental
Nanotechnology will be critical to advances in elec-
tronics, materials, medicine, and the environment. This
is in large part due to their remarkable electronic, optical,
magnetic, and mechanical properties. However, a sig-
nificant limitation of nanotcchnology is the ability to pro-
duce bulk quantities of dispersed particles. One possibil-
ity for dispersing nanoparticles (which have a high area/
mass ratio) is to use adsorbed polymer, oligomer, or sur-
factant molecules; however, disposal of the enormous
quantity of additives would involve huge environmental
and financial stresses. The expected engineering break-
through of the proposed research is to identify whether
solvation or depletion forces can be manipulated to pro-
duce dispersed suspensions of "bare''nanoparticles (i.e.,
without adsorbed additives).
The central scientific questions to be answered are:
What are the magnitudes of the van der Waals, solva-
tion, and depletion forces for nanoparticle systems, and
what variables can we control to alter these forces? The
research will involve two primary components: (1) de-
velopment and use of '"particle force light scattering"
(PFLS). an experimental method for measuring sub-
piconewton nanoparticle forces; and (2) use of molecu-
lar dynamics (MD) simulations to predict the individual
forces. Synergy is essential to this research: PFLS is the
first technique capable of measuring the nanoparticle
forces, and MD enables the interpretation of exactly how
the forces are acting. Measured forces will be compared
with bulk stability and rheology measurements.
The expected engineering outcome of this research
is determining whether bare nanoparticles can be stabi-
lized by appropriately engineered solvation or depletion
force systems. A positive result will avert a huge waste
stream of additives that would otherwise be necessary
to stabilize nanoparticle systems. To achieve this out-
come, the following scientific objectives must be met:
(1) MD modeling will be done to delineate the magnitude
of van der Waals. solvation, and depletion forces for
nanoparticles systems; the modeling will demonstrate
the pertinent variables that control these forces. (2) PFLS
will be developed, and measurements of nanoparticle
forces between silica, titania, and barium titanate par-
ticles in water will be performed. Results from the MD
modeling will be tested.
The Office of Research and Development's National Center for Environmental Research
63
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
5.
SB1R - Nanomalerials and Clean Technology.
EPA is interested in research that applies the principles of nanotcchnology to the areas of environmental monitoring and
pollution control with commercialization possibilities. Nanotechnology is emerging as a field critical for enabling essential
breakthroughs mat may have tremendous potential for affecting several environmental areas. Moreover, nanotechnologies
developed in the next several years may well form the foundation of significant commercial platforms.
EPA's SBIR interests include development of: nanoporous filters for removal of gaseous pollutants and particulates
from contaminated air streams; nanofiltrarion membranes for organic solvent recover}-; nanoparticulate catalysts for
utilization in VOC treatment devices; microelectromechanical (MEMS) systems for use in environmental analytical
and monitoring devices; nanolaminated pigments and coating free of hazardous metal contaminants; technology for
solvent-free production of nanosizcd high performance ceramic powders; and technology for the synthesis, assem-
bly, and processing of nauostructured materials and devices for environmental applications.
The Office of Research and Development's National Center for Environmental Research 65
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
Jayesh Doshi
eSpin Technologies, Inc., Chattanooga, TN
Abstract
The 21st Century has begun with the promise of
nanotechnology, which is expected to harness novel prop-
erties of materials and unique features of phenomena at
the nanometer scale. This is likely to lead to significant
breakthroughs that will have major implications for envi-
ronmental protection. Nanotechnologies developed in the
coining years will form the foundation of significant
commercial platforms. This project focuses on provid-
ing a feasibility demonstration of producing nonwovcn
webs of electrospun nanofibers at a commercial scale
for specific environmental applications. The applications
targeted are those that require the use of webs such as
high surface area material or filtration media. These ap-
plications are well suited to address the problems of
adsorbing gaseous pollutants (where high surface area
of nanowcbs is very attractive) or filtering particles
smaller than 3 microns from effluent gases or liquids
economically (where superior efficiency of nanowebs
in capturing submicron particles is very attractive). Al-
ternatively, such filters will increase the particle-loading
capacity of the filters, or reduce the pressure drop for a
variety of filtration end uses.
Initially, the nanofibers will be electrospun from a
solution of polyacrylonitrile in dimethylforni amide in the
form of a nonwoven mat. This mat will be further pro-
cessed to convert it into activated carbon fiber NanoFilter
media. The web architecture will be tailored to achieve
the desired filter performance and gas adsorption by vary-
ing fiber diameter, fiber orientation, fiber-packing frac-
tion within the nanoweb, activation level, and nanoweb
thickness.
This project will be carried out by eSpin Technolo-
gies—a small, high-technology startup company based
in Chattanooga, TN, that specializes in providing cus-
tom-made electrospun nanofibers—in collaboration with
academic centers and major corporations. Together, this
group possesses the skills and facilities needed to suc-
cessfully conduct the work under this project.
At the end of the Phase I and Phase II efforts, eSpin
will have successfully developed nanofibcr-bascd high
surface area NanoFilters made from activated carbon
for the removal of gaseous pollutants. With the active
collaboration of eSpin's partners, these products will be
commercialized in the United States and in the interna-
tional marketplace. Apart from providing technology lead-
ership to U.S. companies, the proposed effort also will
help fulfill the mission of the U.S. Environmental Protec-
tion Agency to improve the quality of air and water.
The Office of Research and Development's National Center for Environmental Research
67
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
Jayesh Doshi
eSpin Technologies, Inc., Chattanooga, TN
eSpin's nanofibers can be considered an •'infra-
structural" technology spawning many potential indus-
tries and applications; therefore, the total health and
environmental benefit of the technology can be hard to
predict. However, some estimates can be offered based
on potential impacts of the technology in one example
application—air filtration.
Volatile organic compound (VOC) contamination and
general indoor air pollution are a growing concern due to
adverse effects on health and worker productivity, re-
sulting in a need for an effective means of VOC emis-
sion reduction and control to address phenomena such
as "sick building syndrome." U.S. Environmental Pro-
tection Agency (EPA) studies of human exposure to air
pollutants indicate that indoor air levels of many pollut-
ants may be two to five times, and occasionally more
than 100 times, higher than outdoor levels.1 According
to the EPA and other sources such as the National En-
ergy Management Institute, Indoor Air Quality (IAQ)
problems are on the rise and are causing billions of dol-
lars in lost productivity and health care costs; this makes
IAQ one of the most important environmental and health
concerns facing Americans today. Therefore, there is a
present and growing need for an effective means of VOC
emission reduction and control. Government and end-
user guidelines are becoming more strict as the costs for
noncoinpliance continue to grow (e.g.. health, produc-
tivity, insurance, lawsuits, etc.), and governmental em-
phasis on reducing people's exposure to indoor air pollu-
tion is rapidly mounting.
Fortunately, there is an opportunity for activated car-
bon nanofiber technology to be incorporated into air fil-
tration equipment for enhanced VOC control. Indoor air
quality concerns continue to drive the air filter and air
cleaner markets. According to an EPA IAQ fact sheet,
improving the quality of indoor air environments is likely
to boost employee morale and worker productivity, mak-
ing IAQ controls an important component of operation,
maintenance, and energy conservation strategies.2 Cost-
effective technologies are particularly needed for air deal-
ers with improved ability to remove carbon monoxide
and selected VOCs from indoor air systems, for which
conventional technology is inadequate.
Beyond the immediate air filtration applications, there
also are many similar application possibilities in other
complementary industry sectors where pollution and VOC
control are important. For example, most military bases
pose a threat to the environment where fuels, cleaning
solvents, and degreasers have seeped into the ground
due to past disposal practices, spills, or leaking storage
tanks. Municipal wastewater treatment plant effluents
pose serious hazards to populated communities. Leak-
age from landfills is another concern. eSpin's technol-
ogy can have dramatic positive environmental impacts if
it is adopted aid utilized effectively in solving these press-
ing problems.
Under EPA (SBIR) funding, eSpin has produced a very
high surface area activated carbon nanofiber with many
significant advantages: (1) Activated carbon nanofiber is
effective in absorbing toxic organic compounds from air.
(2) The technology has demonstrated its ability to cap-
ture particles in water filtration that are smaller than 3
microns. This implies a new benchmark in water filtra-
tion. Activated carbon nanofiber also has shown high af-
finity for chlorinated compounds in water. (3) The inte-
gration of eSpin's nanofibers into filter products creates
impressive improvements in filler performance—be it par-
ticle capture levels, pressure drop, or filter longevity.
(4) The cost/benefit ratio of activated carbon nanofiber
versus conventional media is economically favorable.
(5) An appropriately optimized integrated filtration system
would offer m any benefits and can be designed to occupy
a smaller overall footprint when installed. The compact de-
sign and long service life of the filter modules should make
them ideal for many traditional and new applications.
Activated carbon nanofiber membranes can provide
a filtration system applicable for micro to ultrafine par-
ticles in the 100-angstrom range. Such systems can be
used to remove carbon black, tobacco smoke, virus,
bacteria, pigments, and pyrogcns from air and liquid
without contributing particle (broken fiber) or out-gas-
sing contamination.
Additionally, providing a small improvement in pro-
cess yields and product performance over a wide range
of separation tasks will have a large financial impact. A
platform technology is needed that can be routinely
68
'lite Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
tailored to function under a wide range of conditions,
that is robust, cost effective, reliable, and easily dissemi-
nated. eSpin Technologies has the potential of fulfilling
all of these needs. The current high-value markets for
such filter media are ultraclean manufacturing rooms,
barriers for use in biotechnology, and medical/pharma-
ceutical.systems. Over the long term, new demands will
likely come from micro- and iiano-machine markets
where separations will be needed to isolate and purify
these machines in bulk quantities. The lower value, high-
volume markets include food, agriculture, paints, pigments,
coatings, chemicals, petroleum, automotive, aerospace,
environment, and water treatment. Ultimately, this will set
new performance standards for the filtration process, with
obvious implications for a broad range of applications—
civil, industrial, and governmental.
1 U.S. EPA, Office of Air and Radiation. Targeting indoor air pollution. U.S. EPA's Approach and Progress.
http: //www. epa. go v/iaq/pub s/targetng .html.
2 EPA Web Site, http://www.epa.gov/iaq/pubs/veiitilat.html.
The Office of Research and Development's National Center for Environmental Research
69
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Andrew Myers
TDA Research, Inc., Wheat Ridge, CO
Abstract
Plasticizers are small, often volatile molecules that
are added to hard, stiff plastics to make them softer and
more flexible. Because they are not directly bound to the
polymer chain, they can migrate to the surface and es-
cape from the plasticizcd material. Many plasticizcrs are
toxic and they create a health risk when they leach out.
This is a particular problem for polyvinyl chloride (PVC),
which often is used in toys for infants. Plasticizer loss
also leads to brittle and unusable materials. A system that
immobilized the plasticiziiig agent within a polymer with-
out compromising other necessary physical properties
would find a ready market.
Permanence characterizes the tendency of a plasti-
cizer to remain in a polymer. The proposed research
effort will develop a new plasticizer system that is char-
acterized by high permanence and longer product life-
times, and eliminates the potential for hazardous dermal
and/or ingestive exposure from plasticized polymers. The
initial effort will target PVC, the highest-volume plasti-
cized commodity plastic, but methods developed by TDA
Research, Inc. (TDA) will be easily transferable to other
commodity plastics.
TDA proposes to increase the permanence of plasti-
cizers by attaching the plasticizer to the surface of a
nanoparticle. The anchored plasticizer still affects the
glassy-to-rubbery transition of the host material, yet the
permanence of the plasticizer is substantially increased.
An added benefit is that the plasticizer-functionalized
nanoparticle also improves the barrier properties of the
host material and may improve other mechanical and
physical properties as well. Phase I research will pre-
pare, incorporate, and test a new plasticizer system for
PVC. Phase II efforts will optimize the modified PVC
and prepare the material for commercialization through
collaborations with TDA's industrial partners.
Plasticizers increase the flexibility and softness of a
material, are incorporated into many modern high-vol-
ume plastics, and are one of the largest segments of the
plastics additives market. Plastic modifiers, including plas-
ticizers and impact modifiers, were a $9 billion business
in 1997. If successful, the iianoparticle-anchored plasti-
cizers could have an extremely large commercial impact
and enable the production of safer, longer lived plastic
materials.
70
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
Andren'Myers
TDA Research, Inc., Wheat Ridge, CO
Environmental
Plastici/ers are small, often volatile molecules added
to hard, stiff plastics to make them softer and more flex-
ible. Plasticizers are not directly bound to the polymer
chain and can be lost by volatilization to air. migration to
a solid, or extraction into water or organic solvents. This
leaves a brittle, cracked polymer and shortens the useful
performance lifetimes of plasticized materials. From an
environmental, health, and safer)' standpoint, the loss of
plasticizcrs to the surrounding medium—whether it is
air, water, or soil in the environment or saliva in the mouth
of an infant —is an undesired event.
To protect children's health, the U.S. Environmental
Protection Agency has proposed a plan to systematically
test the toxicity of a number of high-produclion-volume
(HPV) chemicals. The initial focus is on 50 chemicals
that pose risks of exposure to children. Included in this
list are phthalate esters, which are used to plasticize PVC.
Loss of plasticizcrs is particularly a problem for PVC, as
it is the most highly plasticized commodity polymer. Plas-
tic modifiers, including plasticizers and impact modifi-
ers, were a $9 billion business in 1997. Plasticizers rep-
resent the largest volume additive for PVC. and widespread
use has distributed PVC and phthalate esters around the
globe. As such, it is one of the most likely plastic addi-
tives to be extracted into the environment. PVC is used
in toys for infants, geomembranes, and medical prod-
ucts (e.g., tubing and solution bags).
The efforts of environmental groups have made the
public very aware of the presence and potential threat of
phthalate esters. The evidence of the carcinogenic nature of
phthalates in rodents and the lack of an understanding of
the long-term effects of pMialates in the human body have
focused attention on products made from plasticized PVC.
Although recent studies have indicated the safe nature of
several common plasticizers—the International Agency for
Research on Cancer (IARC), part of the World Health Or-
ganization (WHO), has reclassified di(2-ethylhexyl) phtha-
late (DEHP) as "not classifiable as to carcinogenicity to
humans"—public concern remains high. Some pacifiers
and chewable toys are now being marketed with the phrase
"PVC Free" to allay parental concerns over the possible
ingestion of plasticizers.
A system that immobilized the plasticizing agent within
a polymer without compromising other necessary physi-
cal properties would reduce environmental and health con-
tamination, improve consumer acceptance of PVC, and
create longer lived plasticized materials. One solution is to
anchor the plasticizing moiety to the surface of a nano-
particle. If properly designed, the plasticizing nanoparticles
would show good compatibility with the host polymer
without the loss in physical properties observed with larger
particle fillers. The "anchored" plasticizers also would dis-
play high permanence—they would remain in the poly-
mer for longer time periods, perhaps indefinitely. In a suc-
cessful Phase I project (Phase II awarded June 2002),
TDA Research demonstrated that plasticizing groups could
be anchored to the surface of a nanoparticle. that these
nanoparticles were compatible with PVC, and that they
had a plasticizing affect on the bulk polymer. TDA's
nanoparticles are based on a safe, nontoxic mineral-based
core. These inorganic nanoparticles are then surface modi-
fied to contain plasticizing and possibly compatibilizing
groups. All of these materials can be selected from non-
toxic products.
The Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
for of
Xiao-Dong Xiang
Intematix Corporation, Moraga, CA
Abstract
Plastic composite materials are increasingly used in
manufacturing industries (e.g., in automobile compo-
nents). They need to be coated for protective and deco-
rative purposes. It has been found that electrostatic painting
offers approximately four times higher paint transfer ef-
ficiency than regular spray painting. This will result in
significant reduction of paint usage and volatile organic
compound (VOC) emission in the automobile manufac-
turing process. For this process to work, a conductive
plastic with appropriate fillers is required. Of the con-
ductive fillers available, carbon nanotube has proven to
be the only viable filler to make strong and conductive
plastic parts; however, its prohibitively high cost has
deterred broad commercial applications. In this project,
Intematix Corporation will address this critical issue us-
ing the pyrolytic production of iiaiiotubes. The key to
reaching the target cost of $100/kg using the pyrolytic
method is the highly efficient catalyst. Existing catalysts
are not efficient in reaching the target cost.
Intematix Corporation will leverage its unique exper-
tise in high-throughput screening technologies to develop
efficient catalyst compositions that will deliver high-qual-
ity nanotubes at the lowest possible cost in Phase I. This
will pave the way for broad applications of carbon nano-
tubes as fillers in conductive plastic parts manufacturing.
Preliminary results indicate that the high-throughput screen-
ing technologies are dramatically faster and more effec-
tive in large-scale screening and identification of promis-
ing catalyst leads than the conventional research and
development approach.
72
'lite Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
for of
Xiao-Dong Xiang
Imtematix Corporation, Moraga, CA
Environmental
Plastic composite materials are increasingly used in
manufacturing industries. Compared to steel, they have
the advantages of lighter weight, easier to mold or pro-
cess, better corrosion resistance, and potentially low cost.
Recently, there is tremendous interest in applying plastic
composites to automobile body panels, mirror shells, door
handles, bumper fascias, and other auto parts. The pro-
jected demands for the plastic composite GTX (a nylon
and PPO mixture) from the automobile manufacturer
alone will exceed 30 million pounds in the year 2004.
The surface of plastic composite parts for automo-
biles needs to be finished with either a hard coating for
scratch and ultraviolet (UV) resistance, and /or color paints
for decorative purposes. Currently, 100 percent of the
plastic parts are either painted with a sprayer, or electro-
statically coated over a spray-painted conductive primer.1
Electrostatic painting offers about four times the paint
transfer efficiency over regular spray painting. This means
a significant reduction of paint usage and volatile organic
compounds (VOC) emission in the automobile manu-
facturing process.1 Electrically conductive plastics will
convert the current industrial spray coating process into
a much cleaner and efficient primerless electrostatic coat-
ing process. Therefore, a conductive plastic composite
with adequate mechanical properties is highly desirable
for a primerless and environmentally friendly electro-
static coating process. It is estimated that such a primerless
electrostatic coating process will save more than 250
million pounds of spray-painted fascia material and cor-
responding VOC emission used in automobiles alone. A
study conducted by United Technologies Automotive
(UTA) in Berne, Indiana, indicates that if the current pro-
cess to produce mirrors for automobiles was converted
to electrostatic coating on conductive plastics, the Bcme
plant alone would cut the VOC emission by 84 tons per
year. This will drop their current EPA ceiling to 50 per-
cent.1
Because the intrinsically conductive polymers cur-
rently available do not yet have adequate mechanical prop-
erties (e.g., impact resistance) and environmental stabil-
ity (e.g., UV resistance), nonconductivc plastics with
external conductive filler materials currently are chosen
to produce conductive plastics. The commonly used
conductive fillers are carbon blacks, stainless steel fi-
bers, carbon fibers, and recently, carbon iianotube. Car-
bon nanotubes are conductive, strong nanometer diam-
eter graphitic tubes with an extremely large aspect ratio.
Because of the large aspect ratio and tendency to be-
come entangled into a three-dimensional network in the
molten plastic, the fibrils are exceptionally efficient as a
conductive additive. It takes less than about 2 percent of
fibrils, by weight, to attain the level of conductivity needed
for electrostatic painting, about 10° ohm-cm. For the same
conductivity, about 15 percent carbon powder or car-
bon fiber, or 7-8 percent stainless steel fibers would be
required.1
Darrin Keiser, Environmental Manager at UTA's Berne
plant, stated that "It was clear that conductive plastics
would eliminate the need for a conductive primer and
might give us other benefits as well. The problem was
that conductive compounds based on the traditional con-
ductive fillers, typically carbon powder and stainless steel
fibers, have their limitations.'" Keiser notes that the 15
percent loadings typical of carbon black degrade the
mechanical properties of the base plastic, especially im-
pact and processability. In addition, stainless steel fibers,
though used at lower loadings (5-7%), tend to increase
tool wear, affect surface quality, reduce processability,
and are expensive. UTA demonstrated that for the 2 per-
cent carbon nanotube loaded conductive plastic parts,
the paint durability was equal to or better than the finish
on the current mirrors. Most importantly, there was no
significant difference in mechanical properties between
the nanotube loaded conductive and nonconductive parts.
The only problem for application of the environmentally
friendly carbon nanotube loaded conductive plastic com-
posite, or the nanocomposite, he acknowledged, is the
high cost of carbon nanotubes.1 Therefore, the critical
hurdle to proliferate the wide industrial application of
cleaner coating technology with carbon nanotube filled
conductive plastics is to dramatically reduce the cost of
carbon nanotube. The existing price of high quality and
The Office of Research and Development's National Center for Environmental Research
73
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
purity (>90%) CNT is between $100-l,000/gm, pro-
duced mostly for academic and research and develop-
ment purposes. The industry would need tonnage quan-
tities of CNT and about 2 to 3 orders of magnitude
lowered price for commercial scale applications.2 For
example, a market study from Ferro Corporation (a
Intcmatix's commercial partner) suggests that elimina-
tion of the priming step for automobile coating would
be commercially feasible if nanotube composites are
priced near $5/lb at 3 percent CNT loading, which will
translate to a target CNT price in the order of $100/lb.
After screening all of the existing methods of syn-
thesizing CNT, we have identified the catalytic conver-
sion of hydrocarbons with a pyrolytic chemical vapor
deposition reactor as the only possible approach to reach
the $100/lb target. Furthermore, the key to reach the
cost target of approximately $100/lb with this catalytic
synthesis approach is to develop highly efficient cata-
lysts and a scaled up "continuous" CNT production
process to dramatically increase the yield and lower the
cost of CNT. In Phase I of this EPA SBIR project,
Intematix has discovered the most efficient CNT cata-
lyst ever known with our established combinatorial
synthesis and high throughput screening tools. We will
develop a scaled up catalytic pyrolysis reactor and pro-
cess in Phase II to directly produce high-quality CNT
at a target cost of $100/lb, using the advanced cata-
lysts discovered in Phase I.
1 Miller B. (Consulting ed., from Plastics J-f&r/c/magazine). Tiny graphite "'tubes'" create high-efficiency conductive
plastics. From the Web site of Hyperion Catalyst International, http:www.fibrils.com/.
2 Ajayan P, Zhou 0. Application of carbon nanotubes. In: Dresselhaus M, Dresselhaus Q Avouris P (eds.). Carbon
Nanotubes, Synthesis, Structure, Properties, and Applications. Springer: 2001.
74
TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
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TJte Office of Research and Development's National Center for Environmental Research
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Nanotechnology and the Environment: Applications and Implications STAR Progress Review Workshop
of
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