HR: 0800h
AN: H51G-0855    [Abstracts]
TI: Refining Colloid Filtration Theory for Nanoparticle Transport in Porous Media
AU: * Nelson, K E
EM: knelson@ucdavis.edu
AF: Department of Civl & Environmental Engineering, University of California at Davis, One Shields Avenue, Davis, CA 95616, United States
AU: Ginn, T R
EM: trginn@ucdavis.edu
AB: Classical colloid filtration theory (CFT) was developed in the 1970's for predicting the rate of particle removal in deep-bed filtration water treatment systems. Over the past two decades CFT has been widely applied to address subsurface colloid transport research questions, but current concerns on the environmental risks of nanoparticles coupled with the uncertainties of CFT validity for nanoscale colloids calls for development of new constitutive theory for nanoparticle transport. The premise of CFT is that macroscopic transport can be inferred from a mechanistic analysis of particle transport within a single pore space. It has been demonstrated recently by two independent studies (Tufenkji and Elimelech, TE; Nelson and Ginn, NG) that the classic Rajagopalan and Tien (RT) formula significantly overestimates the collector efficiency (rate of contact with porous media surface) for submicron particles due to its assumption of independence between Brownian motion and the other components of particle motion. However, the NG study suggests that the RT equation overestimates the collector efficiency for all submicron particles while the new TE equation converges with RT as particle size decreases (i.e., enters the nanoparticle range). We hypothesize that the reason for this discrepancy is an uncaptured particle size effect on hydrodynamic retardation and van der Waals forces. We present preliminary results aimed at testing this hypothesis and providing a new collector efficiency equation that is more robust for predicting the transport of nanoparticles in porous media.
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1847 Modeling
DE: 1849 Numerical approximations and analysis
SC: Hydrology [H]
MN: 2007 Fall Meeting