Title:
Transport and retention of colloids in saturated and unsaturated porous media
Transport and retention of colloids in saturated and unsaturated porous media
Author(s)
Gray, Christopher Scott
Advisor(s)
Burns, Susan E.
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Abstract
The transport of colloidal particles in subsurface geological deposits plays an important role in many natural and engineered processes, from geochemical cycling of elements in aquifers to the transport of highly mobile bacteria and viruses. This study explored the transport and retention of colloids in saturated and unsaturated silica sand, iron oxide coated sand, and natural zeolite, all of which are common components in permeable reactive barriers. Column flow cell studies demonstrate that colloid mobility is significantly affected by porewater chemistry and theoretical DLVO calculations elucidate differing colloid retention mechanisms in the three geomaterials. Results reveal that colloid transport in geomaterials is reduced in steady-state unsaturated flow, with zeolite significantly enhancing colloid retention. Studies exploring the mobilization of colloids from reactive geomaterials by a downward propagating drying front indicate that reactive geomaterials can enhance colloid retention. This work also investigated the role of colloid shape on transport and retention in saturated and unsaturated silica sand using spherical and ellipsoidal colloids. Theoretical DLVO interaction potential energies calculated using surface element integration reveal that colloid shape affects interaction with the soil surface, while column studies demonstrate colloid shape affects transport, retention, and mobilization in saturated and unsaturated sand.
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Date Issued
2016-01-15
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Text
Resource Subtype
Dissertation