A new spectrometric technique for measuring diffusion coefficients of Ordovician Queenston Formation shale from the Michigan Basin of southwest Ontario, Canada is presented; in this case pore diffusion coefficients (Dp) were determined for the conservative (iodide, I^-) and reactive (cesium, Cs^+) tracers in porous media. Furthermore, diffusion-reaction parameters such as Cation exchange capacity (CEC) were obtained for the reactive tracer, Cs^+ by the reactive-transport modeling.
The principle of X-ray absorption spectrometry (XAS) is based on the attenuation of high atomic number of diffusive species (e.g. Cs^+and I^-) in porous media, allowing for the quantification of the resulting spatial changes. The technique employs a 1.1 mm collimated X-ray beam to resolve the tracer presence in a slice; small region of a rotating sample for a fixed time.
The x-ray beam is incident on a sample of porous rock while the transmitted beam is detected on the opposite side of the sample, allowing acquisition of a transmitted X-ray energy spectrum vs intensity (counts).
Additional analyses such as mineralogical studies by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) were conducted to improve the understanding of solute transport.
The comparison of the data obtained by the XAS method indicating a good agreement with established radiography and other conventional diffusion methods provide an alternate approach for quantifying the diffusion coefficient of porous media.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/43305 |
| Date | 18 February 2022 |
| Creators | Hafezian, Golrokh |
| Contributors | Al, Tom |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Attribution-NonCommercial-NoDerivatives 4.0 International, http://creativecommons.org/licenses/by-nc-nd/4.0/ |
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