We are interested in understanding the complex physical, chemical and biological processes that govern flow and transport of contaminants in the environment systems across multiple scales. Particularly, we focused on investigating fate and transport of engineered nanomaterials, and modeling multiphase flow and multispecies reactive transport in porous media, at both pore- and continuum scales.
Example Research Topics
Analysis of nanoparticle transport in the subsurface using a response surface methodology
A Modular Three-Dimensional Multispecies Transport Model (MT3DMS) was modified to evaluate the transport and retention of nanoparticles in multiple dimensions. Hypothetical scenarios for the release of nanoparticles into an aquifer were simulated numerically .
Based on advanced statistical methodologies (i.e., response surface methodology (RSM)), we explore simple relationships between key factors that control nanoparticle transport (collision efficiency factor, particle size, hydraulic gradient, and initial release concentration) and key parameters that describe the nanoparticle concentration distribution in porous media (maximum standardized concentration, the mass percentage of injected nanoparticle attached in the aquifer, the x-centroid of aqueous phase plume, and the x-centroid of attached phase distribution).
- Bai, C. Eskridge, K.M. and Li, Y*. (2013) Analysis of the Fate and Transport of nC60 Nanoparticles in the Subsurface using Response Surface Methodology, Journal of Contaminant Hydrology (aceepted)
- Bai, C. and Y. Li*, (2012) Modeling the transport and retention of nC60 nanoparticles in the subsurface under different release scenarios. Journal of Contaminant Hydrology, 136-137: p. 43-55.
Measure particle transport and retention in microfluidic device
Laser Scanning Cytometer (LSC) is an emerging technology used in the biomedical field to image and quantitatively analyze individual cells in tissues. An innovative technique was developed in our lab wherein an LSC was incorporated with a microfluidic flow cell to measure the spatial distribution of nanoscale particles in a porous medium domain at the centimeter scale. Briefly, fluorescent particle suspension was pumped into a microfluidic flow cell packed with glass beads, followed by a background solution flush. LSC then scanned the microfluidic cell. For each scan, the LSC measured the emitted fluorescence of the attached particles and also precisely recorded the x and y coordinates of each event. This techique was used to investigate the influence of nanoparticle size and shape on their transport.
- May, R. and Li, Y*. (2013) The effects of particle size on the deposition of fluorescent nanoparticles in porous media: Direct observation using laser scanning cytometry. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 418, pg. 84-91
- May, R., Akbariyeh, S., and Li, Y*. (2012) Pore-Scale Investigation of Nanoparticle Transport in Saturated Porous Media Using Laser Scanning Cytometry. Environ. Sci. Technol., DOI:10.1021/es301749s.
Influence of particle shape on their transport and retention
Mechanistic understanding of transport and retention of nanoparticles in porous media is essential both for environmental applications of nanotechnology and assessing the potential environmental impacts of engineered nanomaterials. Engineered and naturally occurring nanoparticles can be found in various shapes, for example, rod-shape carbon nanotubes. Although it is expected that the nonspherical shape could play an important role on particle transport and retention, current theoretical models for particle transport in porous media are all based on spherical shape.
The effect of particle shape on its transport and retention in porous media was evaluated by stretching carboxylate-modified fluorescent polystyrene spheres into rod shapes with aspect ratios of 2:1 and 4:1. Quartz crystal microbalance with dissipation experiments (QCM-D) were conducted to measure the deposition rates of spherical and rod-shaped nanoparticles to the collector (poly-L-lysine coated silica sensor) surface under favorable conditions. Under unfavorable conditions, the retention of nanoparticles in a microfluidic flow cell packed with glass beads was studied with the use of laser scanning cytometry (LSC). Our work highlighted the importance to consider particle shape for accurate transport modeling.
- Seymour, M., Chen, G., Su, C., and Li, Y*. (2013) Influence of particle shape on nanoparticle retention and release in saturated porous media. Environ. Sci. Technol (accepted)
Three dimensional modeling of vapor intrusion process.
Simulation of viscosity modification based in situ chemical oxidation for groundwater remediation.
University of Nebraska - Lincoln
Department of Civil Engineering
362R Whittier Building
Lincoln NE 68583-0856
Phone: (402) 472-5972
Fax: (402) 472-8934
Office: 362B Whitter Building
2200 Vine Street
Lincoln NE 68583-0856
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