Doctor of Philosophy
Groundwater serves as a major source of drinking water for many people across the world. Aquifer properties have been studied extensively, as well as contaminant transport within aquifers and remediation of contaminated aquifers. A common component of alluvial aquifers is sediment deposition. ASTM-D2419-14 defines sand as particle of rock with size range of between 0.075 mm and 4.75 mm. Sand is mostly composed of silica and has physical and chemical attributes which cause its specific characteristics. Silica is considered chemically inert, unable to enter most chemical reactions in aqueous geochemistry field. However, would it be wise to disregard the potential effect that sand may have on the adsorption process of contaminants, or do researchers need to take a closer look at the sand characteristics specific to the research location or remediation site? The aim of this dissertation is to first determine if sand characteristics, physical and chemical, can influence the adsorption patterns of various contaminants. Secondly, to provide a standard method with high reliability and reproducibility by which others can also test the sand they have at their disposal to determine if and how the sand specific to their location interacts with their chosen contaminant. The third goal was to utilize such method on three different contaminants: Hexavalent Chromium as a heavy metal and oxyanion, Trichloroethylene (TCE) as a chlorinated volatile organic solvent, and Bromide as a conservative tracer which passes through the system with no interaction. These three contaminants are significantly different from each other, and not only do they represent a wide range of behaviors expected from contaminants, but they are also commonly found in urban or industrial superfund sites. During this study, six different sand samples were collected from three different core samples drilled. The six sand samples covered both geographical and depth variations. The method was developed, optimized, validated, and the reproducibility was calculated using %RSD values, which were recorded for <1% for bromide, indicating a high reproducibility value. Furthermore, when the three types of chemicals were interacted with the sand samples, the results confirmed that the sand characteristics do in fact impact the adsorption behaviors. In short, it is paramount for the purposes of modeling contaminant transport as well as remediation specialists to study the effects of sand specific to their region on the contaminant they are working with. The experiments performed consist of pH studies, kinetic studies, isotherm studies, and additional experiments. These experiments differentiated the sand samples into three distinct groups behaviorally. One cluster of sand samples showed no interaction with the contaminants, one group showed minimal interaction, and the other group showed distinguishable adsorption patterns. The influential factors on the adsorption behaviors found to be the organic carbon content, the iron content, grain size, and percentage of fine material (silt and clay). Also, it is worth mentioning that a specific sand sample can exhibit different adsorption patterns when interacted with different chemicals.
Dissertation or thesis originally submitted to ProQuest
Embargoed until 12/9/2023
Sharafoddinzadeh, Donya, "Natural Attenuation of Chromium and TCE on Memphis Aquifer Sand, a Bench-Scale Study" (2023). Electronic Theses and Dissertations. 3062.