Because Ga shares many physicochemical properties with Al and Fe, Ga may be able to incorporate into Al and Fe oxy-hydroxides. Understanding how Ga incorporates into these oxy-hydroxides may be crucial for finding Ga-rich bauxite deposits. In order to find the difference in Ga inclusion rates into oxy-hydroxides, as well as understand the mechanisms for this Ga inclusion, Al and Fe oxy-hydroxides were synthesized in the lab with Ga additions of 2 mol % Ga and 20 mol % Ga for a low-Ga and high-Ga treatment, respectively, along with a no added Ga control. X-Ray diffraction analyses confirmed the formation of bayerite (α-Al(OH)3) and goethite (FeOOH) after 100 days (goethite long synthesis [LS]). A second batch of goethite was synthesized in the lab and aged for 60 hours (goethite short synthesis [SS]). Results showed the highest Ga inclusion rates in goethite LS minerals at 0.89 mol % / mol % Ga, then 0.17 mol % / mol % Ga in goethite SS, and 0.50 mol % / mol % Ga in bayerite. Scanning electron microscopy and electron microprobe analyses determined co-precipitation of Ga was the dominant Ga incorporation mechanism in bayerite over isomorphic substitution, where needle-like mineral assemblages began to form in the high-Ga treatments. Isomorphic substitution vii was dominant in both goethite batches. Additionally, Ga mol % in the high-Ga goethite LS and goethite SS minerals revealed a temporal aspect to Ga inclusion in goethite. Goethite LS high-Ga treatment minerals had Ga mol % of 16.8 ± 0.23 % compared to 3.34 ± 0.03 % for high-Ga treatment goethite SS minerals. This study highlights an advance in knowledge of Ga incorporation mechanisms into Al and Fe oxy-hydroxides and provides a basis for future studies to expand on these efforts.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:masters_theses_2-2072 |
| Date | 02 April 2021 |
| Creators | Palmer, Corey A |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Masters Theses |
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