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Immiscible liquids, including chlorinated solvents, have proven to be a lasting source of subsurface contamination at many hazardous waste sites. Continued improvement of site characterization and determination of applicable remediation technologies can be achieved by further understanding of the transport and fate of these contaminants. The transport and fate of trichloroethene (TCE) was investigated through miscible displacement and dissolution experiments. Miscible displacement experiments were conducted using homogeneously packed columns with several porous media encompassing a range of particle size distributions. Immiscible liquid dissolution was investigated using homogeneously packed columns containing a residual saturation of trichloroethene. The same porous media were used for immiscible liquid dissolution experiments. Mathematical modeling of miscible displacement and dissolution experiments was conducted using a one-dimensional single region or multi-region model. Imaging of immiscible liquid dissolution was also conducted, using Synchrotron X-ray Microtomography imaging at Argonne National Laboratory, Argonne, IL. Dissolution experiments exhibited nonideal dissolution behavior that was apparent in observed effluent data and in collected imaging data. Nonideal behavior was manifested as secondary regions of relatively constant aqueous concentrations occurring for a number of pore volumes. This behavior was observed to increase in magnitude as particle size distribution of the porous media increased. During imaging, immiscible liquid blobs were observed to dissolve throughout the column during dissolution. This behavior is also indicative of nonideal dissolution, as it would be expected that dissolution would first occur for the blobs nearest the inlet and then proceed upward through the column as dissolution progressed. In many cases, a multi-region modeling approach was necessary to successfully represent the nonideal behavior observed. Comparisons were made between the natural porous media used for this research and a well-sorted sand. Nonideal dissolution was not observed in the well-sorted sand.

abstract: This study explores how bulk composition and oxygen fugacity (fO2) affect the partitioning of sulfur between the molten mantle and core of an early planetesimal. The model can be used to determine the range of potential sulfur concentrations in the asteroid (16) Psyche, which is the target of the National Aeronautics and Space Administration/Arizona State University Psyche Mission. This mission will be our visit to an M-type asteroid, thought to be dominantly metallic. The model looks at how oxygen fugacity (fO2), bulk composition, temperature, and pressure affect sulfur partitioning in planetesimals using experimentally derived equations from previous studies. In this model, the bulk chemistry and oxygen fugacity of the parent body is controlled by changing the starting material, using ordinary chondrites (H, L, LL) and carbonaceous chondrites (CM, CI, CO, CK, CV). The temperature of the planetesimal is changed from 1523 K to 1873 K, the silicate mobilization and total melting temperatures, respectively; and pressure from 0.1 to 20 GPa, the core mantle boundary pressures of Vesta and Mars, respectively. The final sulfur content of a differentiated planetesimal core is strongly dependent on the bulk composition of the original parent body. In all modeled cores, the sulfur content is above 5 weight percent sulfur; this is the point at which the least amount of other light elements is needed to form an immiscible sulfide liquid in a molten core. Early planetesimal cores likely formed an immiscible sulfide liquid, a eutectic sulfide liquid, or potentially were composed of mostly troilite, FeS. / Dissertation/Thesis / Masters Thesis Geological Sciences 2020