Dissertation
Effect of centrifugal and interfacial forces on colloid transport and mobilization
Washington State University
Doctor of Philosophy (PhD), Washington State University
12/2007
DOI:
https://doi.org/10.7273/000005729
Abstract
Knowledge of colloid fate and transport in saturated and unsaturated porous media
is important for management of ground- and surface-water contamination, because many
contaminants attach and migrate with colloids. In this dissertation, I applied theoretical
and experimental techniques to evaluate the forces responsible for deposition and removal of
colloids in saturated and unsaturated porous media.
The main objectives of this dissertation were:
1. To test the suitability of geocentrifuges for studying colloid transport in porous media
and to determine the critical accelerations when colloid transport through a saturated
porous media is altered compared to normal gravity;
2. To study the effect of different boundary conditions imposed at the column outflow on
in situ colloid mobilization in porous media and to elucidate the mechanisms of colloid
mobilization; and
3. To quantify the effect of moving liquid-gas interfaces on the detachment of colloidal
particles from collector surfaces.
I studied the suitability of geocentrifuges for investigating colloid transport. Forces exerted
by centrifugation and the thermodynamic energy were considered to develop a theoretical
relationship to determine the critical centrifugal acceleration at which sedimentation
dominates diffusion. Experiments using a geocentrifuge were carried out to verify the theory.
I demonstrated the importance of the lower boundary of unsaturated porous media on
colloid mobilization. Several column experiments were conducted to identify the effect of
the boundary conditions. The hydrological conditions and solution chemistry were also
varied. In unsaturated porous media, liquid-gas interface played an important role in colloid
mobilization. This research demonstrated the paramount role of liquid-gas interfaces on
colloid mobilization.
To obtain mechanistic information on the role the liquid-gas interface, I used confocal
microscopy to directly visualize and quantify how many colloids can be removed from a solid
surface by a moving liquid-gas interface. Theoretical calculations using adhesive forces and
surface tension forces were used to support the experimental results.
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Details
- Title
- Effect of centrifugal and interfacial forces on colloid transport and mobilization
- Creators
- Prabhakar Sharma
- Contributors
- Markus Flury (Chair) - Washington State University, Department of Crop and Soil SciencesJoan Qiong Wu (Committee Member) - Washington State University, Department of Biological Systems EngineeringEarl D MATTSON (Committee Member)DAVID R YONGE (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Electrical Engineering and Computer Science
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 157
- Identifiers
- 99901054940701842
- Language
- English
- Resource Type
- Dissertation