Estimating diffusion coefficients in low-permeability porous media using a macropore column

Journal Article · Tue Sep 01 04:00:00 EDT 1998 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es9711324· OSTI ID:655399

Young, D F; Ball, W P ^[1]

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1. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Geography and Environmental Engineering

Diffusion coefficients in an aquitard material were measured by conducting miscible solute transport experiments through a specially constructed macropore column. Stainless steel HPLC columns were prepared in a manner that created an annular region of repacked aquitard material and a central core of medium-grained quartz sand. The column transport approach minimizes volatilization and sorption losses that can be problematic when measuring hydrophobic organic chemical diffusion with diffusion-cell methods or column-sectioning techniques. In the transport experiments, solutes (triated water, 1,2,4-trichlorobenzene, and tetrachloroethene) were transported through the central core by convection and hydrodynamic dispersion and through the low-permeability annulus by radial diffusion. All transport parameters were independently measured except for the effective diffusion coefficient in the aquitard material, which was obtained by model fitting. Batch-determined retardation factors agreed very closely with moment-derived retardation factors determined from the column experiments, and no evidence of pore exclusion was found. A model with retarded diffusion was found to apply, and the effective tortuosity factor of the aquitard material was estimated at an average value of 5.1.

• OSTI ID: 655399
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 17 Vol. 32; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AQUIFERS
CHLORINATED ALIPHATIC HYDROCARBONS
CHLORINATED AROMATIC HYDROCARBONS
ENVIRONMENTAL TRANSPORT
LIQUID COLUMN CHROMATOGRAPHY
MATHEMATICAL MODELS
WATER POLLUTION