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Title: Solid-State Recrystallization Pathways of Sodium Aluminate Hydroxy Hydrates

Abstract

Crystallization of Al-bearing solid phases from highly alkaline Na 2O:Al 2O 3:H 2O solutions commonly necessitates an Al 3+ coordination change from tetrahedral to octahedral, but intermediate coordination states are often difficult to isolate. Here, a similar Al 3+ coordination change process is examined during the solid-state recrystallization of sodium oxohydroxoaluminate hydrate (MSA) to nonasodium bis(hexahydroxy aluminate) trihydroxide hexahydrate (NSA) at ambient temperature. While the MSA structure contains solely polymerized tetrahedral Al 3+, the NSA structure is a molecular aluminate salt solely based upon monomeric octahedral Al 3+. Spontaneous recrystallization of MSA and excess sodium hydroxide hydrate into NSA over 3 days of reaction time was clearly evident in X-ray diffractograms and in Raman spectra. In situ 27Al multiple quantum MAS NMR spectroscopy showed no evidence of intermediate aluminates, suggesting that intermediates, such as pentacoordinate Al 3+, are short-lived and require more highly time resolved spectroscopies to detect. Such research is advancing upon detailed mechanistic understanding of Al 3+ coordination change mechanisms in these highly alkaline systems, with relevance to aluminum refining, corrosion sciences, and nuclear waste processing.

Authors:
ORCiD logo [1];  [2]; ORCiD logo [1]; ORCiD logo [1];  [3]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Washington State Univ., Pullman, WA (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Washington State Univ., Pullman, WA (United States)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1631324
Report Number(s):
PNNL-SA-150728
Journal ID: ISSN 0020-1669
Grant/Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 59; Journal Issue: 10; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; NMR, Sodium Aluminate

Citation Formats

Graham, Trent R., Gorniak, Rafal, Dembowski, Mateusz, Zhang, Xin, Clark, Sue B., Pearce, Carolyn I., Clark, Aurora E., and Rosso, Kevin M. Solid-State Recrystallization Pathways of Sodium Aluminate Hydroxy Hydrates. United States: N. p., 2020. Web. doi:10.1021/acs.inorgchem.0c00258.
Graham, Trent R., Gorniak, Rafal, Dembowski, Mateusz, Zhang, Xin, Clark, Sue B., Pearce, Carolyn I., Clark, Aurora E., & Rosso, Kevin M. Solid-State Recrystallization Pathways of Sodium Aluminate Hydroxy Hydrates. United States. doi:10.1021/acs.inorgchem.0c00258.
Graham, Trent R., Gorniak, Rafal, Dembowski, Mateusz, Zhang, Xin, Clark, Sue B., Pearce, Carolyn I., Clark, Aurora E., and Rosso, Kevin M. Tue . "Solid-State Recrystallization Pathways of Sodium Aluminate Hydroxy Hydrates". United States. doi:10.1021/acs.inorgchem.0c00258.
@article{osti_1631324,
title = {Solid-State Recrystallization Pathways of Sodium Aluminate Hydroxy Hydrates},
author = {Graham, Trent R. and Gorniak, Rafal and Dembowski, Mateusz and Zhang, Xin and Clark, Sue B. and Pearce, Carolyn I. and Clark, Aurora E. and Rosso, Kevin M.},
abstractNote = {Crystallization of Al-bearing solid phases from highly alkaline Na2O:Al2O3:H2O solutions commonly necessitates an Al3+ coordination change from tetrahedral to octahedral, but intermediate coordination states are often difficult to isolate. Here, a similar Al3+ coordination change process is examined during the solid-state recrystallization of sodium oxohydroxoaluminate hydrate (MSA) to nonasodium bis(hexahydroxy aluminate) trihydroxide hexahydrate (NSA) at ambient temperature. While the MSA structure contains solely polymerized tetrahedral Al3+, the NSA structure is a molecular aluminate salt solely based upon monomeric octahedral Al3+. Spontaneous recrystallization of MSA and excess sodium hydroxide hydrate into NSA over 3 days of reaction time was clearly evident in X-ray diffractograms and in Raman spectra. In situ 27Al multiple quantum MAS NMR spectroscopy showed no evidence of intermediate aluminates, suggesting that intermediates, such as pentacoordinate Al3+, are short-lived and require more highly time resolved spectroscopies to detect. Such research is advancing upon detailed mechanistic understanding of Al3+ coordination change mechanisms in these highly alkaline systems, with relevance to aluminum refining, corrosion sciences, and nuclear waste processing.},
doi = {10.1021/acs.inorgchem.0c00258},
journal = {Inorganic Chemistry},
issn = {0020-1669},
number = 10,
volume = 59,
place = {United States},
year = {2020},
month = {4}
}

Journal Article:
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