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Colloid transport with wetting fronts: interactive effects of solution surface tension and ionic strength
Jie Zhuang1, Nadine Goeppert, Ching Tu
1Institute for a Secure and Sustainable Environment, Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, TN 37996-4134, USA. jzhuang@utk.edu
Water Research
|January 9, 2010
Summary
Colloid transport in soil is affected by surface tension and ionic strength. Lowering these factors reduces colloid deposition and alters migration patterns in the vadose zone.
Area of Science:
- Environmental Science
- Soil Science
- Colloid Science
Background:
- Colloid transport is a key factor in contaminant migration within the vadose zone.
- Understanding colloid behavior under varying flow conditions is crucial for environmental risk assessment.
Purpose of the Study:
- To investigate the influence of solution surface tension and ionic strength on colloid transport and deposition.
- To evaluate colloid behavior under both steady-state saturated and transient unsaturated flow conditions.
Main Methods:
- Utilized steady-state saturated and transient unsaturated flow columns.
- Employed fluorescent latex microspheres (980 nm) as model colloids.
- Varied solution surface tension and ionic strength, measuring colloid recovery and zeta potentials.
Main Results:
- Decreased surface tension and ionic strength reduced colloid deposition and increased effluent recovery.
- Colloid retention decreased exponentially with travel distance under unsaturated flow.
- Lowering surface tension and ionic strength enhanced electrostatic repulsion between colloids and sand.
Conclusions:
- Surface tension and ionic strength nonlinearly influence colloid transport, with potential critical thresholds.
- Reduced capillary forces at lower surface tension decreased colloid migration velocity.
- Findings provide insights into contaminant transport mechanisms in porous media.
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