Carbon Nanotubes: Environmental Dispersion States, Transport, Fate, and Bioavailability
|Principal Investigator||Walter J. Weber|
|Institution||University of Michigan|
|Relevance to Implications||High|
|Class of Nanomaterial||Engineered Nanomaterials|
|Broad Research Categories||
Generation, Dispersion, Transformation etc.|
|Anticipated Total Funding||$371,886.00|
|Anticipated End Year||2009|
Our overarching goal is to evaluate factors that control the environmental dispersion states, transport, fate, and bioavailability of carbon nanotubes, thereby providing a foundation for human and ecological risk assessment. Specifically, single-walled and multi-walled 14C-labeled carbon nanotubes will be synthesized, purified, and characterized using techniques previously established in our lab. These radio-labeled materials will then be used to systematically investigate i) the dispersion states of these nanomaterials under typical environmental conditions, ii) their transport behaviors within and through a series of different types of soil and sediment media, and iii) their bioavailability to selected critical aquatic and terrestrial food-chain organisms.
We have developed and refined a means for producing single-walled and multi-walled 14C-labeled carbon nanotubes by using radioactively labeled methane as a feedstock for the synthesis of carbon nanotubes via chemical vapor deposition methods. Carbon nanotubes will be mixed with natural organic matter and subjected to a wide range of aquatic conditions (i.e., pH, ionic strength, etc.) to elucidate their dispersion state in natural environments. Carbon nanotube transport through a series of soil and sediment sorbent materials having different geochemical properties will be tested in dynamic column studies, and relationships among the breakthrough behaviors and the properties of both the nanotubes and the geosorbent materials will be analyzed. Carbon nanotube bioavailability to a fish, an aquatic worm, and an earthworm will be tested in lab-scale systems to examine the potentials of these nanomaterials to enter food chains in different environments, and factors controlling ecological bioavailability will be determined.
The proposed study will provide: a) fundamental information regarding carbon nanotube dispersion states, transport, fate, and bioavailability in different environmental systems; b) identify factors controlling these environmental behaviors; and c) establish deterministic models capable of predicting behaviors under different environmental conditions. This information is critically needed by EPA and the research community for rigorous assessments of the environmental fate, transport, and ecological risks of carbon nanotubes in various soil/water/sediment systems.