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4/26/2011 1 Opportunities and Challenges of Opportunities and Challenges of Nanomaterials for the Drinking Nanomaterials for the Drinking Water Community Water Community Water Community Water Community Mary Ellen Tuccillo and Glen Boyd Mary Ellen Tuccillo and Glen Boyd The Cadmus Group Inc. The Cadmus Group Inc. The Cadmus Group Inc. The Cadmus Group Inc. Related Foundation Projects Related Foundation Projects Project 4334 Project 4334 - Constructed Wetlands Constructed Wetlands for Treatment of Organic and for Treatment of Organic and for Treatment of Organic and for Treatment of Organic and Nanomaterial Pollutants Nanomaterial Pollutants Project 3077 Project 3077 - Arsenic Removal with Arsenic Removal with Agglomerated Nanoparticle Media Agglomerated Nanoparticle Media

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Page 1: Opportunities and Challenges of Nanomaterials for … · Opportunities and Challenges of Nanomaterials for the Drinking Water CommunityWater Community ... Removal depends on pH alk

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Opportunities and Challenges of Opportunities and Challenges of Nanomaterials for the Drinking Nanomaterials for the Drinking

Water CommunityWater CommunityWater CommunityWater Community

Mary Ellen Tuccillo and Glen BoydMary Ellen Tuccillo and Glen Boyd

The Cadmus Group Inc.The Cadmus Group Inc.The Cadmus Group Inc. The Cadmus Group Inc.

Related Foundation ProjectsRelated Foundation Projects

•• Project 4334 Project 4334 -- Constructed Wetlands Constructed Wetlands for Treatment of Organic andfor Treatment of Organic andfor Treatment of Organic and for Treatment of Organic and Nanomaterial Pollutants Nanomaterial Pollutants

•• Project 3077 Project 3077 -- Arsenic Removal with Arsenic Removal with Agglomerated Nanoparticle MediaAgglomerated Nanoparticle Media

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Opportunities and Challenges of Nanomaterials for the Drinking Water CommunityWater Community

Mary Ellen TuccilloGlen R. BoydThe Cadmus Group, Inc.

Water Research Foundation Project 4311

Project’s Goal

To provide information on the state of knowledge regarding nanomaterials in the environment and identify knowledge gaps relevant to the drinking water communityrelevant to the drinking water community

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• Currently no uniform definition• Most common criterion is size:

What are nanomaterials?

• Most common criterion is size:▫ At least one dimension that measures less than 100 nm▫ Includes both nano-sized particles and materials with

nano-sized features• ASTM E2456-06 definition of nanotechnology:▫ Technologies that “measure, manipulate, or incorporate

materials and/or features with at least one dimension between approximately 1 and 100 nm ” between approximately 1 and 100 nm.

• Properties differ from bulk materials:▫ High surface area relative to volume▫ Enhanced reactivity▫ Optical, electrical, disinfectant properties

References: Batley and McLaughlin, 2010;

Types of Nanomaterials

• Naturally occurring or inadvertently producedNaturally occurring or inadvertently produced▫ Ubiquitous in the environment, and common in

soils▫ Within size range for colloids (1 nm to 1 um)▫ Amorphous silica, Fe and Mn oxyhydroxides,

clays, natural organic matter, viruses▫ Anthropogenic (inadvertently produced)

combustion products (e.g., soot)

Reference: Buffle & Leppard, 1995; Hochella et al., 2008; Nowack and Bucheli, 2007

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• Nanosilver▫ About 20% of products that use nanomaterials▫ Disinfectant properties and odor control

Metals and Metal Oxides

Disinfectant properties and odor control▫ Can be surface bound, suspended in liquids or solids,

sprayed as a coating, integrated into fibers▫ Commonly coated with citrate - negative surface charge

• Nano TiO2▫ Photocatalytic, disinfectant, UV-blocking properties▫ Potential for use in degrading organics, breakdown of

cyanotoxins and pathogens for drinking water treatmentZi id• Zinc oxide▫ Similar properties to TiO2 and used in similar products▫ UV-blocking, photocatalytic, and disinfectant properties

Lowry and Casman, 2009; Choi et al, 2008, Kiser et al., 2009, Davis et al., 2009; kllaine et al., 2008.

• Spherical carbon atoms (C60 is )

Fullerenes - Buckyballs

most common)• Not soluble in water unless

functional groups added• Very stable in environment

and in human body• Antioxidant, antiviral,

tib t i l antibacterial, superconductive at high temperatures when doped with metals

Courtesy of Paul Kent , Oak Ridge National Laboratory

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Fullerenes – Carbon Nanotubes• Rolled-up graphene sheet. Single-

walled or multi-walled• Can behave as metallic or semi-

conducting solids. • High strength, flexibility, low elastic

deformability• Used for ultra-strong, ultra-light

materials• Ropes, tear-free fabrics, reinforced p , ,

concrete, sports equipment, may be usable in batteries, capacitors. Used in electric motor brushes in cars, medical applications

iStock Photo, 2011

Other Nanomaterials

• Quantum dots• Nanostructured materials▫ Zeolites▫ Nano-clays▫ Chitosan▫ Dendrimers

Zeolite structure with metal atoms( f lk l lif i(Courtesy of Volkan Ortalan, California Institute of Technology)

DendrimerSource: National Cancer Institute: http://ncl.cancer.gov/working_ncl-nano.asp

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Nanomaterial Applications

Nano-TiO2Paint , cosmetics, textiles, coatings Potential for water treatment

Nano-ZnO2Cosmetics, sunscreen, textiles, coatings, antimicrobial agents

Nano-Ag

Containers, toys, bedding, clothing, pain, cosmetics, medical itemsAntibacterial agents Potential for water treatment

Fullerenes (buckyballs) Antimicrobial agents, cosmetics, drug delivery

C b b Antimicrobial agents, textiles, sports

Carbon nanotubes t c ob al age ts, te t les, spo ts

equipment, medical applications

Nano-clay Textiles

Chitosan Potential for water treatment

Quantum dots Electronics

Dendrimers Medical applications (drug delivery)

Health Risks - Challenges• Difficult to generalize about toxicological effects• Differs from toxicity testing for chemicals – uncertain

which attributes affect toxicitywhich attributes affect toxicity• Studies complicated by limitations in analytical

methodsHuman Health Risks

• Most studies done in-vitro, and systems may not have been validated for use with NMs

• Few studies in tests systems relevant for mammalian exposure exposure

• Materials may not be adequately characterized• Studies generally not conducted at environmental

concentrations

Oberdorster et al., 2005; Sayes and Ivanov, 2010

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Human Health Risks• Inhalation studies▫ Most human health studies done for inhalation

exposureC h i f i f ti f ▫ Common mechanism of response is formation of reactive oxygen species

▫ Some evidence NPs can move from lungs to other organs

▫ Studies conducted at high doses

(Source: NIOSH, 2009. Approaches to Safe Nanotechnology:Managing the Health and Safety Concerns Associated with Engineered Nanomaterials . www.cdc.gov/niosh.)

Photomicrographs of airborne exposure to ultrafine (nanoscale) particles of welding fumes, diesel exhaust, and cerium oxide

Human Health Risks• Oral exposure▫ More relevant for environmental exposure

V f t di f l t NP h ▫ Very few studies of oral exposure to NPs on human health

▫ Suggest some types of NPs can be absorbed across gut

▫ Smaller particles distribute more widely than larger particles

▫ Speciation chemistry renders evaluation difficult• Dermal exposure• Dermal exposure▫ Healthy skin should limit absorption▫ Role of skin condition, particle coating, aqueous

media unknown

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Ecological Health Risks• Microorganism studies

▫ Nanoscale metal oxides can be antibacterialNanoscale metal oxides can be antibacterial▫ Toxicity to microorganisms may be by ROS or photocatalytic activity▫ Test media can affect toxicity▫ Tests not conducted at environmentally relevant concentrations▫ Cell numbers and organic carbon can affect toxicity

• Macroinvertebrates and Fish▫ Some indication nanoTiO2 can be transported to other parts of organism▫ Silver toxic to fish and invertebrates▫ Arsenic bound to nanoTiO can be taken up in fish▫ Arsenic bound to nanoTiO2 can be taken up in fish▫ Possible developmental defects from CNTs

• Toxicity affected by:▫ Preparation methods▫ Particle size and aggregation▫ Sensitivity of the species

Health Risks – Data Needs

• Importance of particle size in toxicity – as p p ycompared to aggregation, surface area, etc.

• Studies at anticipated environmental concentrations

• Enhanced toxicity from associated contaminants

• Are existing assays valid for nanomaterials?• Do particulate aspects of NMs cause toxicity

beyond the chemical aspects?

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Releases to the Environment

• Intentional releases▫ e.g., use for environmental remediation

• Unintentional releases – point sources▫ Releases from spills ▫ Wastewater treatment plants and landfills

• Nonpoint releases▫ e.g., sunscreens during swimming▫ Wear of nanomaterial-bearing products and

transport in runoff

• Data lacking on concentrations of ENPs in natural

Occurrence in Environmental Waters

waters• Occurrence and exposure largely unknown• Limited by detection methods and confounded by

naturally occurring nanoparticles• How to estimate?▫ Models based on substance flow from products into ▫ Models based on substance flow from products into

air, soil, and water to obtain estimates of environmental concentrations

Mueller and Nowack, 2008; Gottschalk et al., 2009

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Environmental Fate and TransportSame processes important in fate and transport of

colloids in soils and waterscolloids in soils and waters• Aggregation and sedimentation• Biological transformations (microbial activity)• Photolysis and hydrolysis• Adsorption of substances to NP surface

These may all affect mobility, bioavailability, and toxicityy

Aggregation and sedimentation especially important in governing size and mobility in both surface and subsurface

Also important for treatment

Aggregation and SedimentationWhat governs?• Nanoparticle properties▫ Solubility in water▫ Coatings and functional groups▫ Humic substances

• Water chemistry▫ Ionic strength, composition

(di l i )

Nanoparticle properties

(divalent cations)▫ Natural organic matter▫ pH

Partially representative TEM (A, C, E) and AFM (B, D, F) images showing nanoparticles as individuals, small aggregates,and large colloidal aggregates

(Reprinted in part with permission from Environ. Sci. Technol.2009, 43, 7277–7284, Copyright 2009, American Chemical Society)

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• Information needed on concentrations and

Data Gaps – Occurrence and Fate and Transport

characteristics of natural and engineered NPs in groundwater, surface water, drinking water, WWTP effluent, soils

• Ongoing research needed on surface properties:▫ Effects of organic coatings on aggregation, transport,

and fate during treatment and fate during treatment • Microbial transformations – bioavailability of

surface coatings on ENPs in natural systems• NP-facilitated transport of contaminants

▫ Different from analyzing for dissolved chemicals –

Detection and Analysis

need more information than mass concentration because other attributes affect toxicity and transport

▫ Which properties to measure? Chemical composition, size distribution, surface

area, state of aggregation, structure, surface area, state of aggregation, structure, surface charge

▫ May need a combination of methods

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Challenges in Detection and Analysis▫ Nanoparticle samples are dynamic in terms of Nanoparticle samples are dynamic in terms of

size and size distribution▫ Matrix effects from complex waters▫ Low anticipated environmental concentrations of

ENPs (may need to be able to detect below 1 ug/L)

▫ Naturally occurring NPs may dominate▫ Sample handling and storage may change state of

aggregation▫ Loss of constituents to walls of sample bottles?

Methods are available to separate particles in aqueous medium –must be coupled to a detection method

▫ Field flow fractionation –similar to chromatography. Produces continuous size distribution Has been used

Separation and Quantification

method▫ Filtration – need series of

steps. Clogging and electrostatic interactions

▫ Cross-flow filtration – avoids clogging. Commonly used with colloids

▫ Size exclusion chromatography – column packed with beads - has

distribution. Has been used with colloids and ENPs Flow-field flow

fractionation (F1FFF) promising for nanomaterials. Especially good in size range < 50 nm

packed with beads - has been used with nanomaterials

Lead and Wilkison, 2006; Tiede et al., 2008. Hasselov et al., 2008

FlFFF fractogram(Reprinted in part with permission from Environ. Sci.

Technol.2007, 41, 1111-1117, Copyright,2007, American Chemical Society).

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Separation and Quantification cont’dAfter separation, can couple sample to a detection

method:method:• UV-vis detector – for estimating mass in size fractions.

Does not provide chemical analysis• Atomic absorption spectroscopy (AAS) – provides

chemical analysis • Inductively coupled plasma – mass spectrometry –

provides chemical analysis – extremely sensitive• F1FFF coupled with ICP-MS shows promise for use with

nanomaterials• Fullerenes in water analyzed using liquid

chromatography/mass spectrometry

Electron Microscopy

• Provides imaging and analysis of individual NPs and Provides imaging and analysis of individual NPs and aggregates

• Can evaluate: aggregation, dispersion, adsorption, structure, shape, particle size

• Most popular methods:• Scanning electron microscopy (SEM)• Transmission electron microscopy (TEM)Transmission electron microscopy (TEM)• Atomic force microscopy (AFM)

• SEM and TEM allow chemical analysis• AFM provides 3D profiles of surface

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Electron MicroscopyDrawbacks• Can only analyze a small amount of material – not

t ti f l lrepresentative of larger samples• Operate under vacuum; samples must be dried and/or

embedded in resin – preparation changes the sample

TEM image of MWNTs(Reprinted in part with permission from Environ. Sci. Technol., 2008, 42, 7963—7969. Copyright, 2008, American Chemical Society)

Cryo-TEM image of 4.4-5.5 nm nano-TiO2(Reprinted in part with permission from Environ. Sci. Technol., 2009, 43, 1354-1359, Copyright, 2009, American Chemical Society)

Dynamic Light Scattering

Benefits: Allows for rapid analysis in real timep yProduces a distribution of hydrodynamic diameters

Drawbacks:• Cannot confirm identity of particles• Difficulty interpreting data from polydisperse samples• Interference from dust• Low concentrations may not provide enough light y p g g

scattering for analysis• May need to preconcentrate, which can affect

aggregation

Bootz et al., 2004; Domingos et al., 2009

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• Methods are needed that are:

Detection Method Data Gaps

▫ Rapid, cost effective, have low detection limits• More research needed on sample preparation

and storage• Characterization of heterogeneous samples –

needs to distinguish natural from engineered NPs

• Well-characterized reference standards are needed

Glen R. Boyd, PhD, PEThe Cadmus Group, Inc.Seattle, Washington

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Nanomaterials and Drinking Water Treatment• Removal of Nanoparticles (NPs) by Treatment▫ Existing treatment effectiveness Conventional treatment, membranes, sorption

▫ More research needed• Potential Uses of Nanomaterials in Treatment

l b d h l▫ Filtration-based technologies▫ Adsorbents▫ TiO2 photocatalysis▫ Nanotechnology-based sensors

Removal of NPs Conventional Treatment Effectiveness

• Jar tests

▫ Various nanomaterials (TiO2, ZnO, etc.) and inlet conc of 10 mg/L▫ Alum dosage 20-60 mg/L▫ Simulated inlet, after sedimentation, and after filtration

• Findings

▫ Alum coagulation removed 20-80% of nanoparticles (90-95% with filtration)▫ Removal depends on pH alk alum dosage divalent cations and NOM ▫ Removal depends on pH, alk, alum dosage, divalent cations, and NOM ▫ Removal efficiency depends on zeta potentials (or surface charges)

Ref: Westerhoff et al (2006; 2007; 2008); Zhang (2007a,b); Zhang et al (2008 a,b); Hyung & Kim (2009)

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Removal of NPs Membrane Processes Effectiveness

Membrane Pore Size

Microfiltration 100 to 200 nm

Ultrafiltration 10 to 50 nm

• MF/UF expected to remove aggregated nanoparticles

• NF/RO expected to remove non-aggregated nanoparticles

Nanofiltration 2 to 10 nm

Reverse OsmosisRemoves most dissolved constituents

nanoparticles

• Few published studies on membrane removal effectiveness

(Ref: Zhang et al 2008a)

Removal of NPs Sorption Processes Effectiveness

• NPs have high surface area and adsorption capacity

• Sorption technologies expected to remove NPs

TechnologyPotential

Application

Ion ExchangeSelective removal of NPs based on charge characteristics

Activated Alumina & Iron

Possible NPs removal by physical/ chemical p

with high efficiency

• Few published studies on sorption removal effectiveness

(Ref: USEPA 2007b)

Alumina & Iron-Based Media

by physical/ chemical adsorption

Granular Activated Carbon (PAC/GAC)

PAC may remove aggregated NPs;GAC may provide additional NPs removal

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Removal of NPs More Research Needed

ff l d• Are NPs effectively removed in drinking water treatment? ▫ If yes, by what mechanism?

• Does the presence of NPs ▫ Impact treatment of other

constituents?▫ Affect performance of treatment Affect performance of treatment

facilities?

• How effective are existing treatment processes (coag/floc/settling, filtration, sorption) for NPs removal?

(Ref: USEPA 2007b)

Removal of NPs More Research Needed cont’d• What are removal efficiencies of ▫ Various treatment processes (conventional,

membranes, sorption, softening) for▫ Wide range of NPs?

• What water quality factors affect aggregation, settling, filtration, and removal of NPs?

• How do reagent grade nanomaterials differ from NPs occurring in the environment?

• How does pre-oxidation change NPs properties and NPs treatability?

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Potential Uses of Nanomaterials Filtration-Based Technologies• Nanostructured Membranes

▫ Macroscopic structures with controlled geometric shapes, density, and dimensions developed for specific filtration applications

▫ Includes carbon nanotubes, nanocapillary array membranes, and nanoceramic membranes

(Ref: Choi et al, 2006a; 2006b; Theron et al, 2008; Choi et al 2006a, 2006b)

SEM image of TiO2 nanotubes shown as lateral and top view (inset). (Reprinted in part with permission from Environ. Sci. Technol., 2010, 44: 7884-7889. Copyright 2010 American Chemical Society)

Potential Uses of Nanomaterials Filtration-Based Technologies• Nanoreactive Membranes

▫ Chemically functionalized to increase affinity, selectivity, and capacity for targeted organic and inorganic solutes and ions

• Example

UF/NF b b dd d ▫ UF/NF membranes embedded with nanoparticles (e.g., zero-valent iron) and used to selectively remove targeted constituents (e.g., reductive dehalogenation of TCE)

(Ref: Theron et al, 2008; Nurmi et al, 2005)

TEM image of Fe particles composed of aggregates of faceted plates and smaller irregular particles. (Reprinted in part with permission from Environ. Sci. Technol., 2005, 39: 1221-1230. Copyright 2005 American Chemical Society)

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Potential Uses of Nanomaterials Filtration-Based Technologies• Dendrimers and Polymer-Supported

Filtration

▫ Highly branched macromolecules with repeating interior units and terminal functional groups

• Examples

▫ Remove organic molecules from

External functional groups determine chemical behavior of macromolecule

e o e o ga c o ecu es o water

▫ Deliver antimicrobial agents (e.g., Ag, NH3Cl)

▫ Remove Cu(II) from solution and recover Cu ions by pH adjustment

(Ref: Theron et al, 2008; Savage & Diallo, 2005)

Internal repeating units determine solubilization properties of dendrimer

Dendrimer. Reproduced in part with permission from Environ. Sci. Technol., 2005, 39: 1366-1377. Copyright 2005 American Chemical Society

Potential Uses of Nanomaterials Filtration-Based Technologies

Dendrimer enhanced filtration. Reproduced with permission from Environ. Sci. Technol., 2005, 39: 1366-1377. Copyright 2005 American Chemical Society

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Potential Uses of Nanomaterials Filtration-Based Technologies• Disinfection

▫ Biocidal chemical agents in nanomaterials

• Examples

▫ Ag and MgO embedded nanomaterials (Theron et al, 2008; P l t l 2007 M khl f t l 2005)Pal et al, 2007; Makhluf et al, 2005)

▫ LP membranes remove viruses and incorporate nanobiocides (Botes and Cloete, 2010)

▫ Biocidal contact surfaces (N-halamines) (Bargmeyer et al, 2004)

Source: Innovative Biofilm Prevention Strategies ©2004 Awwa Research Foundation. Reprinted with permission.

Potential Uses of Nanomaterials Adsorbents• Zeolites

▫ Zeolite ion exchange capacity and hydrophobicity can be controlled by altering Si/Al ratio during synthesis, thus possibly customizing for specific types of pollutants (Theron et al, 2008; Savage & Diallo, 2005)

• Nanocarbon and Carbon Nanotubes

d f d b l▫ Adsorption of NOM and cyanobacterial toxins onto nanotubes is superior to GAC; however, potential release of CNTs into the environment is a concern (Upadhyayula et al, 2009)

▫ Sorption of TCE and benzene to CNTs is superior to activated carbon; however more research needed to optimize preparation (Kilduff et al, ongoing).

TEM of (upper) multi-walled and (lower) single-walled carbon nanotubes. (Reprinted in part with permission from Environ. Sci. Technol., 2008, 42: 3090-3095. Copyright 2008 American Chemical Society)

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Potential Uses of Nanomaterials Adsorbents• Self-Assembled Monolayers on

Mesoporous Supports (SAMMS)

▫ SAMMS for the removal of metals and radionuclides from water (Fryxell et al, 2004; Chouyyok et al, 2010)

• Option for Arsenic Removal

▫ Titanium-based nanofibers (e.g., MetsorbG, Adsorsia GTO) (Hristovski et al 2008)

▫ Nanoscale hydrous iron oxide impregnated into ion exchange beads (ArsenX) (Wang et al, 2008)

Nanoporous sorbent functionalized with chelating diamines for Cu capture. (Reprinted in part with permission from Environ. Sci. Technol., 2010, 44: 6390-6395. Copyright 2010 American Chemical Society)

Potential Uses of Nanomaterials TiO2 Photocatalysis• TiO2 is a semiconductor photocatalyst activated with

UV and visible light• Potential water treatment applications

▫ TiO2 slurry – requires additional treatment unit for separation from solution

▫ Immobilized TiO2 – might eliminate need for particle g premoval

Preparation of TiO2 nanoparticles on colloidal SiO2. (Reprinted with permission from Environ. Sci. Technol., 2007, 41: 4441-4446. Copyright 2007 American Chemical Society)

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Potential Uses of Nanomaterials TiO2 Photocatalysis

• Examples of TiO2 treatment applications

▫ UV-based TiO2 degradation of Lindane, methyl parathion, and

dichlorvos (Senthilnathan & Philip, 2010)

Mycrocystin-LR (MC-LR) cyanotoxin (Antoniou et al 2009)cyanotoxin (Antoniou et al, 2009)

▫ Sunlight-based TiO2 inactivation of C. parvum (Gumy et al 2006; Alrousan

et al 2009; Liga et al 2011) E. coli (Gumy et al, 2006; Alrousan et al

2009)

TiO2-coated glass plate illuminated with UV light from below. Results showed inactivation and degradation capabilities. (Reprinted with permission from Environ. Sci. Technol., 1998, 32: 726-728. Copyright 1998 American Chemical Society)

Potential Uses of Nanomaterials TiO2 Photocatalysis• More research ▫ Inactivation mechanisms ▫ Film properties (e.g., doping, porosity, particle size)▫ Process conditions (e.g., pH)▫ Reactor design and optimal operationsg p p

(Left) methyl blue (MB) and TOC removal and (right) MF membrane flux over meso-porous F-TiO2 hollow microspheres and commercially available Degussa P25 TiO2 particles. (Reprinted with permission from J. Am. Chem. Soc., 2008, 130: 11256-11257. Copyright 2008 American Chemical Society)

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Potential Uses of Nanomaterials Nanotechnology-Based Sensors

• Nanomaterials make excellent candidates for environmental monitoring due to their ▫ small size ▫ optical, fluorescence, and magnetic properties T f t h l b d • Types of nanotechnology-based sensors▫ Electrochemical sensors▫ Optical sensors

Potential Uses of Nanomaterials Nanotechnology-Based Sensors

• Electrochemical Sensors▫ Oxidation/reduction rxn on surface

of electrodes▫ Immunosensors

• Examples ▫ Detect MC-LR using Ag

nanoparticles with DL of 7 0 pg/L nanoparticles with DL of 7.0 pg/L (Loyprasert et al 2008)

▫ Simultaneous monitoring of DO, pH, cond, turb, & temp using RuO2 nanostructures (Zhuiykov, 2010)

▫ Detect Cr(VI) using gold particles with DL of 5 μg/L (Liu et al, 2007)

Images of screen printed electrode (A) without and (B) with Au nanoparticles for Cr(VI) detection. (Reprinted with permission from Environ. Sci. Technol., 2007, 41: 8129-8134. Copyright 2007 American Chemical Society)

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Potential Uses of Nanomaterials Nanotechnology-Based Sensors

• Optical Sensors▫ Unique optical properties

of nanomaterials used to develop sensors

• Example▫ Detect heavy metal ions

(Cu2+, Hg2

+) as low as 5 μg/L using quantum dots and gold nanoparticles (Yang et al, 2007; Darbha et al, 2008)

SEM images of CdTe quantum dot-modified TiO2 nanotubes shown as lateral view and top view (inset). (Reprinted in part with permission from Environ. Sci. Technol., 2010, 44: 7884-7889. Copyright 2010 American Chemical Society)

• Strategies

Regulatory Issues

g▫ Extending existing regulations to cover

nanotechnology▫ Voluntary Initiatives

• Challenges Posed by Knowledge Gaps▫ Gaps in health or exposure data▫ Limitations in monitoring▫ Trigger concentrations unclear

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• Agencies with relevant authority ▫ FDA (Food, Drug, and Cosmetics Act)

Regulation in the U.S.

▫ DoL (Occupational Safety and Health Act)

▫ EPA (Clean Water Act (CWA), Toxic Substances Control Act (TSCA), Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), Safe Drinking Water Act (SDWA), and Clean Air Act (CAA))

• Challenges with Adopting Existing Regulations▫ No centralized authority

E i i l i l i d i h h l ▫ Existing legislation not created with nanotechnology in mind

▫ Lack of testing, manufacturing, and emissions guidelines

• Since 2008, EPA pursuing options under TSCA▫ Significant New Use Rule (SNUR)

Federal and State Regulatory Actions

▫ Significant New Use Rule (SNUR)▫ Testing Rule▫ Data Collection Rule

• In 2010: SNUR for carbon nanotubes- banned releases of CNTs into water

• Nanoclays, nanosilver, and some nanocarbons will be examined under the Testing Rule

• States: CA and WI have begun developing regulations

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• Research on analytical methods for environmental

Summary of Data Gaps

waters at relevant concentrations• Environmental occurrence data needed for utilities

to understand whether engineered NPs are present in their source waters

• Factors affecting fate and transport, including aggregation and disaggregationaggregation and disaggregation

• Effectiveness of conventional treatment processes in removing nanoparticles

• Health effects data at environmentally relevant i

Summary of Data Gaps

concentrations• Cause of nanomaterial toxicity – size effects vs.

chemical effects• Continued development of nanomaterial-based

drinking water treatment options – optimization of operational parameters and research on scaling up ope at o al pa a ete s a d esea c o scal g up for plant-scale use