Increasing concern over the use of nanomaterials in an expanding variety of consumer products requires a frank assessment of the potential risk to human and environmental health. Typical risk assessment scenarios require an understanding of 1) the source of the hazard, 2) transport in either natural or engineered systems resulting in 3) exposure of a receptor. This research award will focus on the these three components of this assessment. Characterization and quantification of physical/chemical changes in nanoparticles when transferred from engineered to natural systems will be achieved using a series of unique experimental procedures to observe rates and extent of ligand exchange, changes in particle morphology, and transport through subsurface media.
The objective of this research to define the potential source term of nanoparticles in natural systems to be used in a quantitative risk assessment. This will be achieved by quantifying the rate and extent of physical and chemical changes in nanoparticles during transitions from engineered to natural systems (e.g. nanoparticle behavior when released into natural waters). Research results can be used to inform risk analysis by identifying the nanoparticles likely to be mobile in natural environments and biologically available in natural waters.
As part of the broader impact of this work, the researchers will create an Undergraduate Creative Inquiry (UCI) research group at Clemson. UCI is a Clemson wide focus on team-based undergraduate research that transcends both class and discipline. The researchers will recruit motivated undergraduate students from all disciplines, especially those in the PI?s departments of Environmental Engineering and Earth Science, Chemical and Biomolecular Engineering, and Material Science and Engineering to target a group of eight students at different stages in their education with priority given to women and minority students. The goals of the UCI group will be to initially perform an exhaustive literature search on all published literature pertaining to the toxicity and hazards associated with different classes of nanomaterials, as well as the transport and routes of potential exposure. This data will be critically evaluated and classified based on the chemical and morphological properties of the nanomaterials.
The objective of this project is to define the potential source term of nanoparticles in natural systems for use in a quantitative risk assessment. This is being achieved by quantifying the rate and extent of physical and chemical changes in nanoparticles during transitions from engineered to natural systems (e.g. nanoparticle behavior when released into natural waters). Research results will be used to inform risk analysis by identifying the nanoparticles likely to be mobile in natural environments and biologically available in natural waters and characterize physical/chemical changes that nanoparticles undergo in natural systems. Specific objectives of this project are to: Examine the rate and extent of exchange between naturally occurring ligands (NOM, carbonate, and phosphate) and anthropogenic ligands. Quantify the influence of pH, ionic strength, and NOM on aggregation and morphology of nanoparticles introduced either as "bare" or ligand stabilized nanoparticles. Characterize the morphology of aggregated nanoparticles formed in natural systems via aggregation. Characterize and quantify the interactions between nanoparticles and naturally occurring macroscale mineral phases. Further develop analytical tools for the characterization of nanoparticle behavior in natural and engineered systems. Use ligand exchange rates and aggregation kinetics to predict the fate of functionalized nanomaterials in waste treatment systems and experimentally verify results. Provide experimental evidence that exchange with natural ligands that stabilized nanoparticles (as determined in objective 1 and 2) will result in enhanced mobility through packed sediment column studies under advective flow. This project has thus far resulted in 4 publications with 3 more in the final stages of development.
