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Coupled effects of solution chemistry and hydrodynamics on the mobility and transport of quantum dot nanomaterials in the Vadose Zone
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To investigate the coupled effects of solution chemistry and vadose zone processes on the mobility of quantum dot (QD) nanoparticles, laboratory scale transport experiments were performed. The complex coupled effects of ionic strength, size of QD aggregates, surface tension, contact angle, infiltration and water content on the mobility and transport of QDs were demonstrated. As ionic strength increased, the QD retention increased; however this retention was significantly suppressed in the presence of non-ionic surfactant in the infiltration solution, regardless of the chemical transport conditions. Non-ionic surfactant limited the formation of QD aggregates by impacting steric forces and enhanced the solubility and transport of QDs in porous media. When changing from favorable to unfavorable chemical transport conditions, the dominating phenomena for mobility and transport of QDs in the vadose zone shifted from the meso scale process, where infiltration by preferential flow allowed rapid transport of QDs, to the pore scale process governed by gas-water interfaces (GWI) that impacts the mobility of QDs. Retention of QDs was controlled by electrostatic and capillary forces, with the latter being the most influential. GWI were found to be the dominant mechanism and site for QD removal compared with solid-water interfaces (SWI) and pore straining.
Christophe J.G. Darnault
Preston T. Snee
Astrid R. Jacobson
Robert R. Wells
USDA Scientist Submission
Journal of contaminant hydrology 2010 11 25 v.118
Journal Articles, USDA Authors, Peer-Reviewed
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
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