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Geoelectrical Response of Surfactant Solutions in a Quartzitic Sand Analog Aquifer
Citation:
Magill, M. T. Geoelectrical Response of Surfactant Solutions in a Quartzitic Sand Analog Aquifer. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-10/041, 2010.
Impact/Purpose:
This thesis was not completed in a vacuum. There are many people to whom I owe many thanks, which I can only begin to list. First and foremost, I would like to thank my advisors, Drs. Dave Kreamer and Dale Werkema for keeping me on track and helping me develop a project that I came to truly enjoy. I am very appreciative to UNLV and the U.S. EPA for funding and support, particularly John Zimmerman at EPA for his invaluable help and wisdom in the lab. Thanks to Lisa Hancock, Ryan Joyce, Alan Williams, and Danney Glaser for logistical help in the laboratory, whether teaching me how to use a drill press or helping me find tubing after moving lab space 3 times.
Description:
In this project, the resistivity and phase shift of ten surfactant aqueous solutions in a sand matrix were measured using spectral induced polarization (SIP). In addition, specific conductivity, pH, dissolved oxygen, and dielectric constant measurements of the solutions were also evaluated. The frequency range assessed was 0.091-12000Hz. The surfactants, which are typically used in the remediation of tetrachloroethylene, were Aerosol MA 80-I, Dowfax 8390, and Steol CS-330. The surfactants were mixed into solutions of both deionized and tap water at varying concentrations and injected into a closed system of silica sand. The surfactant treatments altered resistivity, specific conductivity, and pH to varying degrees. Increased real and specific conductivities associated with surfactant presence support the work of Werkema (2008), and the correlation between real and specific conductivities indicates that the primary electrical conduction mechanism in quartz sand-water environment. A decrease in the pH response associated with high concentration surfactant solutions could impact subsurface organisms, potentially affecting bioremediation. Phase, dissolved oxygen, and dielectric constant response to surfactant showed little change from the control. The positive results suggest that geoelectrical changes may be an applicable property to map and monitor surfactant floods in the subsurface. In order to better understand how the geoelectrical response of surfactant solutions would respond in a field situation, it will be necessary to increase the complexity of the experimental set-up. Increasing the heterogeneity of both the solid materials and pore fluid through the addition of clays and chlorinated solvents are potential avenues to follow.