Differences in bulk and microscale yttrium speciation in coal combustion fly ash
Abstract
Coal combustion ash is a promising alternative source of rare earth elements (REE; herein defined as the 14 stable lanthanides, yttrium, and scandium). Efforts to extract REE from coal ash will depend heavily on the location and speciation of these elements in the ash. This study sought to identify the major chemical forms of yttrium (Y), as a representative REE in coal fly ash samples selected from major coal sources in the United States. Y speciation was evaluated using both bulk scale analyses (sequential extractions, Y K-edge X-ray absorption near-edge spectroscopy – XANES) and complementary analyses at the micron scale (micro-focus X-ray fluorescence and micro-XANES). Sequential selective extractions revealed that the REE were primarily in the residual (unextracted fraction) of coal fly ash samples. Extraction patterns for yttrium resembled those of the lanthanides, indicating that these elements were collectively dispersed throughout the aluminosilicate glass in fly ash. Bulk XANES analysis indicated that Y coordination states resembled a combination of Y-oxides, Y-carbonate, and Y-doped glass, regardless of ash origin. However, in the microprobe analysis, we observed “hotspots” of Y (~10–50 μm) in some samples that included different Y forms (e.g., Y-phosphate) not observed in bulk measurements. Overall, this study demonstrated thatmore »
- Authors:
-
[1];
[2];
[2];
[3];
[1]
- Duke Univ., Durham, NC (United States). Department of Civil and Environmental Engineering
- Aix Marseille Univ, CNRS, IRD, INRA, Coll France, CEREGE, Aix-en-Provence (France)
- Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research
- Publication Date:
- Research Org.:
- Duke Univ., Durham, NC (United States)
- Sponsoring Org.:
- USDOE Office of Fossil Energy (FE)
- OSTI Identifier:
- 1474753
- Alternate Identifier(s):
- OSTI ID: 1483484
- Grant/Contract Number:
- FE0026952
- Resource Type:
- Published Article
- Journal Name:
- Environmental Science: Processes & Impacts
- Additional Journal Information:
- Journal Volume: 20; Journal Issue: 10; Journal ID: ISSN 2050-7887
- Publisher:
- Royal Society of Chemistry
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE
Citation Formats
Taggart, Ross K., Rivera, Nelson A., Levard, Clément, Ambrosi, Jean-Paul, Borschneck, Daniel, Hower, James C., and Hsu-Kim, Heileen. Differences in bulk and microscale yttrium speciation in coal combustion fly ash. United States: N. p., 2018.
Web. doi:10.1039/c8em00264a.
Taggart, Ross K., Rivera, Nelson A., Levard, Clément, Ambrosi, Jean-Paul, Borschneck, Daniel, Hower, James C., & Hsu-Kim, Heileen. Differences in bulk and microscale yttrium speciation in coal combustion fly ash. United States. doi:10.1039/c8em00264a.
Taggart, Ross K., Rivera, Nelson A., Levard, Clément, Ambrosi, Jean-Paul, Borschneck, Daniel, Hower, James C., and Hsu-Kim, Heileen. Fri .
"Differences in bulk and microscale yttrium speciation in coal combustion fly ash". United States. doi:10.1039/c8em00264a.
@article{osti_1474753,
title = {Differences in bulk and microscale yttrium speciation in coal combustion fly ash},
author = {Taggart, Ross K. and Rivera, Nelson A. and Levard, Clément and Ambrosi, Jean-Paul and Borschneck, Daniel and Hower, James C. and Hsu-Kim, Heileen},
abstractNote = {Coal combustion ash is a promising alternative source of rare earth elements (REE; herein defined as the 14 stable lanthanides, yttrium, and scandium). Efforts to extract REE from coal ash will depend heavily on the location and speciation of these elements in the ash. This study sought to identify the major chemical forms of yttrium (Y), as a representative REE in coal fly ash samples selected from major coal sources in the United States. Y speciation was evaluated using both bulk scale analyses (sequential extractions, Y K-edge X-ray absorption near-edge spectroscopy – XANES) and complementary analyses at the micron scale (micro-focus X-ray fluorescence and micro-XANES). Sequential selective extractions revealed that the REE were primarily in the residual (unextracted fraction) of coal fly ash samples. Extraction patterns for yttrium resembled those of the lanthanides, indicating that these elements were collectively dispersed throughout the aluminosilicate glass in fly ash. Bulk XANES analysis indicated that Y coordination states resembled a combination of Y-oxides, Y-carbonate, and Y-doped glass, regardless of ash origin. However, in the microprobe analysis, we observed “hotspots” of Y (~10–50 μm) in some samples that included different Y forms (e.g., Y-phosphate) not observed in bulk measurements. Overall, this study demonstrated that yttrium (and potentially other REEs) are entrained in the glass phase of fly ash and that microscale investigations of individual high-REE regions in fly ash samples do not necessarily capture the dominant speciation.},
doi = {10.1039/c8em00264a},
journal = {Environmental Science: Processes & Impacts},
number = 10,
volume = 20,
place = {United States},
year = {2018},
month = {9}
}
DOI: 10.1039/c8em00264a
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