Grantee Research Project Results
Kurt D. Pennell
Georgia Institute of Technology, Atlanta, GA
Widespread production and application of manufactured nanomaterials is expected to increase dramatically over the next decade, which will inevitably lead to the release of carbon-based nanoparticles into the environment. Our current understanding of nanomaterial fate and transport in subsurface systems is extremely limited. For example, it is not known how nanomaterials will interact with soil matrices, whether or not nanoparticle transport can be accurately modeled using classical filtration theory, and how unsaturated soil conditions will impact nanomaterial transport and retention. The overall goal of this project is to expand our knowledge of carbon (C60) nanomaterial fate and transport in natural soils. The three specific objectives of this project are to: (1) investigate the fate and transport of C-60 nanomaterials in water-saturated soils as a function of soil properties and systems parameters; (2) assess the effects of C-60 nanomaterials on soil water retention, water flow and transport in unsaturated soils; and (3) develop and evaluate a numerical simulator to describe C-60 nanomaterial transport, retention and release in subsurface systems.
The research will focus on two relative well-characterized, commercially available carbon nanomaterials: C-60 fullerene, which is very insoluble in water but forms nanoscale aggregates (20-150 nm diameter) that are stable in solution, and fullerol, a relatively water-soluble fullerene derivative that exists as nanoparticles (1-2 nm diameter) in solution. Detailed laboratory experiments will be conducted to explore the fate and transport of these nanomaterials in natural soils. Experimental variables to be considered include soil organic carbon content, grain size, and water content. Fate and transport experiments will be performed in one- and two-dimensional flow systems, under both water-saturated and unsaturated conditions. Experimental results will be used to evaluate conceptual models of nanomaterial retention and release in porous media, and will be directly coupled to the development and validation of a numerical simulator for prediction of nanomaterial fate and transport in subsurface systems.
The proposed research is expected to greatly improve fundamental knowledge of engineered nanomaterial transport, retention, and release in natural porous media. The coupling of detailed experimental research and mathematical modeling will provide for rigorous testing of conceptual models of nanomaterial behavior in subsurface systems, and will culminate in the development of numerical simulator capable of predicting nanomaterial fate and transport over a range of conditions that might be encountered in natural systems. It is further anticipated that the experimental methods, mathematical models and numerical simulator can be adapted or directly used to predict the fate and transport of other nanomaterials, such as ferroxane and single-wall carbon nanotubes, in subsurface systems.