Karla K. Mika

Date of Award


Document Type


Degree Name

Master of Science


Department of Systems Engineering and Management

First Advisor

Edward C. Heyse, PhD


Grain-scale sorption mass transfer is an important process that must be considered when predicting clean-up time and choosing remediation techniques for subsurface hazardous waste contamination. Rate-limited sorption is responsible for the rebound effect, where remediated groundwater is recontaminated by desorption. Sorbed contaminants are not available for microbial degradation, and the desorption rate may govern the effectiveness of natural attenuation by biodegradation. Grain-scale sorption nonequilibrium is generally attributed to diffusive transport, either in SOM or in mineral micropores. Typically used sorption mass transfer models either fail to reproduce long-term slow desorption (first-order models), or are based on diffusion in assumed (often spherical) grain geometries. New multisite models have been proposed that incorporate more realistic grain geometries. To validate these models, we have conducted sorption rate experiments with paraffin, nylon, and porous ceramic spheres. These synthetic surrogate soils were chosen for their differing, but known, sorption coefficients, diffusion coefficients, and geometries. Experiments were conducted in batch systems containing only a single material and size, as well as distributions of two or more materials and sizes. We tested the ability of the model to simulate the behavior of these systems and to fit system parameters from rate data.

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DTIC Accession Number