Thesis
Physical and chemical weathering of illite in the presence of oxalate
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/102788
Abstract
Clay minerals in the rhizosphere are subject exposed to organic exudates, such as the oxalate anion, which are metabolites of both plant roots and microorganisms. Silver Hill illite particles (diameter 0.1 to 1µm) were treated with 0.01 and 0.1 M Li-oxalate at pH 8 and 60º C. Lithium chloride treatments as well as untreated illite were used as controls. Chemical analysis of the supernatant did not show selective weathering of aluminum from the illite and did not show a difference between chloride-treated and oxalate-treated samples. X-ray diffraction (XRD) analysis patterns of all samples were analyzed with MudMaster, a software that uses the BertautWarren-Averbach method to determine crystalline strain and sizes of mineral particles. The fundamental illite particle thickness decreased, indicating fewer numbers of 2:1 layers per particle. Increased strain after reaction with oxalate indicated that weathering was not uniform throughout the particle. The SEM and AFM micrographs showed little visual variation among treatments, but subsequent AFM image analysis with GIS showed higher surface area, volume, thickness, and diameter for the untreated particles compared to both LiCl and Li-oxalate (LiOx) treated illite. The AFM analysis also showed a reduction in the average number of layers per particle for both LiCl and LiOx treated samples compared to the untreated illite. Lithium oxalate appears to aid in the separation of illite layers, most likely due to a reduction of charge due to the loss of tetrahedral aluminum. It is not clear if the reduction in particle thickness resulted from the expansion of illite layers or better dispersion of the illite fundamental particles.
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Details
- Title
- Physical and chemical weathering of illite in the presence of oxalate
- Creators
- Jennifer Michelle Latimer
- Contributors
- James Birney Harsh (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900524802901842
- Language
- English
- Resource Type
- Thesis