The Environmental Implications of Nanotechnology
Fate, Transport and Removal of Nanomaterials in Aquatic Environments
Sharon Walker Department of Chemical & Environmental Engineering University of California, Riverside
April 5, 2011 Office of Basic Energy Sciences Office of Science, U.S. DOE Version 05-26-06, pmd http://wilsoncenter.org/nano Introduction - Novelty • Unusual physicochemical properties
o Small size, surface structure, chemical composition, bulk vs. nano
o May be a dry powder suspended in a gas (nanoaerosol), suspended in liquid (nanohydrosol), or embedded in a matrix (nanocomposite)
• Applications
o Medicine
o Energy
o Electronics
o Consumer products
o Environmental applications Quantum Dots Quantum dot TiO2
Fullerene(Buckey ball) Carbon Nanotube Chen and Elimelech, Langmuir 2006; Saleh et. al, ES&T 2010; Quevedo and Tufenkji, ES&T 2009 Introduction - Toxicity • Evidence of toxicity
o Carbon nanotubes, ZnO and TiO2 cytotoxic to bacteria, mice, rats (Xia et. al, ACS Nano 2008; Kang et. al, Langmuir 2007)
o Fullerene “bucky balls” toxic to fish and humans (Wiesner et. al, ES&T 2006)
o Quantum dots (Cd) and nanosilver (Ag) toxic due to metal release (Mahendra et. al, ES&T, 2008; Benn and Westerhoff, ES&T 2008) Growth of Nanotechnology
Robichaud et al, ES&T, 2009 Growth of Nanotechnology
http://wilsoncenter.org/nano Framing the Research Strategy
Risk Assessment Process 2011 NNI Environment, Health, and Safety Research Strategy
www.nano.gov Integrated Research Framework Life Cycle Stages
Adapted from UC CEIN Traditional Toxicological Approach
Hazard Identification Failure to address Industrial Chemical Toxicology at the scale of production
Exposure Assessment 50,000 + chemicals registered for commercial use in the US
< 1,000 have undergone toxicity testing Risk Characterization Overwhelming of resources: each test • $2-$4 million (for in vivo studies) Risk Management • > 3 years to complete Mission of the UC Center for the Environmental Implications of Nanotechnology (UC CEIN)
The mission of the UC CEIN is to insure that nanotechnology is introduced and implemented in a responsible and environmentally-compatible manner to allow the US and the International community to leverage the benefits of nanotechnology for global economic and social benefit Objectives of the UC CEIN
• Develop a library of reference NMs
• Understand the impacts of different types of NMs on organisms and ecological systems
• Develop a predictive model of toxicology and environmental impacts of NMs
• Develop guidelines and decision tools for safe design and use of NMs Collaborations with Institutions Worldwide Shared Facilities
UC CEIN Central Facilities Synthesis & Characterization • High Throughput Screening • Molecular Foundry (LBNL) • CNSI (UCLA & UCSB) • Shareable Database • Center for Accel Mass Spec (LLNL) • Modeling Framework • CNSE (UCR) • NCEAS infrastructure • I/UCRC (Columbia U) • FIMS (Bremen U) • NYU (Singapore)
Fate & Transport Ecotox • Nano-Bio Interfacial Forces Lab (UCLA) • Micro-Environ Imaging Facility (UCSB) • Fate & Transport Labs (UCR, UCSB) • Bodega Bay Marine Lab (UC Davis) • Water Quality Research Lab (UCLA) • Sandia Biocharacterization lab • Somasundaran’s Lab (Columbia U) • Subcell to Organism In Vivo Imaging • Ecotox Lab at UCSB • New shared lab space at UCSB Research has a Goal…..
IRG1 NM characterization Interactions at molecular, IRG2 cellular, organ and Public systemic levels
Academia IRG3 Organismal & community ecotoxicology Knowledge Education IRG4 NM fate & transport Outreach
Industry HT screening (Data IRG5 generation for NM QSARs) Government IRG6 Modeling of the Environmental Multimedia IRG7 NM Distribution & Toxicity Risk perception High Throughput Screening and Data Mining based on QSAR relationships that can be used to rank NM for risk and priority in vivo testing
100’s/year
1000’s/year 10,000’s/day 100,000’s/day Immediate Relevance High Throughput Cellular or Molecular Screening Prioritize in vivo testing Predictive Mechanism-based Toxicological Approach
Hazard In vitro testing: • Mechanisms/pathways Representative in vivo testing: • Material Libraries • different trophic levels • Bacteria/Cells/Embryos • Food webs • High content or HTS • DEB Modeling etc
Emerging Hazard Identification patterns & scoring Transport & Fate: • Material Libraries • Phys chem features Advanced computational • Sources modeling and expert system • Life cycle
Risk Reduction & Prediction • Safe Design • Probabilistic Risk Modeling • Limit exposure • Risk Perception Predictive Mechanism-based Toxicological Approach
Hazard In vitro testing: • Mechanisms/pathways Representative in vivo testing: • Material Libraries • different trophic levels • Bacteria/Cells/Embryos • Food webs • High content or HTS • DEB Modeling etc
Emerging Hazard Identification patterns & scoring Transport & Fate: • Material Libraries • Phys chem features Advanced computational • Sources modeling and expert system • Life cycle
Risk Reduction & Prediction • Safe Design • Probabilistic Risak Modeling • Limit exposure • Risk Perception Transport and Fate of Nanomaterials in Aquatic Environment
Transport through porous media
Source: UC CEIN (modified) Objectives
Goal: To shed a light on fundamental mechanisms governing fate, transport and removal of engineered nanomaterials in both natural and engineered environment
Objective 1: Development of standard handling approach for consistent nanoparticle dispersion: Effects of sonication, NP type and concentration
Objective 2: Determination of fundamental mechanisms in transport and removal of nanoparticle: Role of nanoparticle concentration, solution chemistry, and hydrodynamic effects
Objective 3: Evaluation of influence of natural organic matter and bacteria in transport and removal of nanoparticle Experimental Approach - Transport
System 1: Packed-Bed Column System 2: Radial Stagnation Point Flow Inlet Inlet
Outlet
Ideal Spherical Collector
Saturated only Outlet
System 3: Parallel Plate Flow k Inlet Outlet RSPF
kPP
Saturated 40x kd = - (u/εL) ln (C/C0) Experimental Approach - Characterization
• Transmission Electron Microscopy (TEM) • Electrokinetic Characterization (ZetaPALS) • Potentiometric Titration • Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) • Thermogravimetric analysis • Stability
o Aggregation (Dynamic Light Scattering)
o Sedimentation (Absorbance) Representative Results
1 mM 10 mM 1 mM 10 mM
1.0 No SRHA1.0 No SRHA
A SRHA 1 mg/L B • NP transport in SRHA 1 mg/L 0.8 0.8 soils depends on groundwater 0.6 0.6 0 constituents 0
0.4 0.4 CaCl • Transport C/C KCl C/C 2 reduced in the 0.2 0.2 presence of Ca2+ • Humic acid 0.0 0.0
(NOM) is 0 2 4 6 8 10 12 0 2 4 6 8 10 12 important when Pore Volume Pore Volume Column K+ present, less 8.0x10-7 2+ 7.0x10-7 for Ca pH 7 10 mM KCl only • Parallel plate 6.0x10-7 setup can 5.0x10-7 10 mM KCl + 1 mg/L SRHA
-7
(m/s) 4.0x10 produce rapid 10 mM CaCl only
pp 2 results that k 3.0x10-7 10 mM CaCl + 1 mg/L SRHA correlate with soil 2.0x10-7 2 -7 Parallel Plate column studies 1.0x10 0.0
Overall Summary and Ongoing Work • Microscope-based transport approach is promising to understand fundamental mechanisms • Overall, transport and removal of nanomaterials is a function of several parameters including NP type, NP concentration, solution chemistry (pH, IS, valence) and presence of organic matter • NOM, pH, and aggregation of NP seem to be the most significant parameters for transport of metal oxide nanomaterials • In future, influence of primary particle size and bacteria on NP transport will be investigated. Acknowledgements • Walker lab: • Indranil Chowdhury • Dr. Yongsuk Hong • Ryan J. Honda, James Kim, Chad Thomsen • Funding
o UC CEIN (NSF & EPA)
• UC CEIN
o Andre Nel, UCLA School of Medicine ([email protected])
o Arturo Keller, UCSB Bren School for the Environment ([email protected])
o Hilary Godwin, UCLA Public Health ([email protected])
o David Avery, Chief Administrative Officer ([email protected])
NSF: EF-0830117 Thank you Carbon Nanotubes