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Title: The apparent solubility of aluminum (III) in Hanford high-level waste

Abstract

The solubility of aluminum in Hanford nuclear waste impacts on the process ability of the waste by a number of proposed treatment options. For many years, Hanford staff has anecdotally noted that aluminum appears to be considerably more soluble in Hanford waste than the simpler electrolyte solutions used as analogues. There has been minimal scientific study to confirm these anecdotal observations, however. The present study determines the apparent solubility product for gibbsite in 50 tank samples. The ratio of hydroxide to aluminum in the liquid phase for the samples is calculated and plotted as a function of total sodium molarity. Total sodium molarity is used as a surrogate for ionic strength, because the relative ratios of mono, di and trivalent anions are not available for all of the samples. These results were compared to the simple NaOH-NaAl(OH{sub 4})H{sub 2}O system, and the NaOH-NaAl(OH{sub 4})NaCl-H{sub 2}O system data retrieved from the literature. The results show that gibbsite is apparently more soluble in the samples than in the simple systems whenever the sodium molarity is greater than two. This apparent enhanced solubility cannot be explained solely by differences in ionic strength. The change in solubility with ionic strength in simple systems ismore » small compared to the difference between aluminum solubility in Hanford waste and the simple systems. The reason for the apparent enhanced solubility is unknown, but could include. kinetic or thermodynamic factors that are not present in the simple electrolyte systems. Any kinetic explanation would have to explain why the samples are always supersaturated whenever the sodium molarity is above two. Real waste characterization data should not be used to validate thermodynamic solubility models until it can be confirmed that the apparent enhanced gibbsite solubility is a thermodynamic effect and not a kinetic effect.« less

Authors:
Publication Date:
Research Org.:
Hanford Site (HNF), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Environmental Management (EM)
OSTI Identifier:
1047871
Report Number(s):
WRPS-52968 Rev.0
Journal ID: ISSN 1093-4529; TRN: US1204058
DOE Contract Number:  
AC27-08RV14800
Resource Type:
Journal Article
Journal Name:
Journal of environmental science and health. Part A, Toxic/hazardous substances and environmental engineering
Additional Journal Information:
Journal Volume: 47; Journal Issue: 14; Journal ID: ISSN 1093-4529
Publisher:
Taylor & Francis
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ALUMINIUM; ANIONS; ELECTROLYTES; GIBBSITE; HYDROXIDES; KINETICS; RADIOACTIVE WASTES; SODIUM; SOLUBILITY; TANKS; THERMODYNAMICS; WASTES

Citation Formats

Reynolds, Jacob G. The apparent solubility of aluminum (III) in Hanford high-level waste. United States: N. p., 2012. Web. doi:10.1080/10934529.2012.707538.
Reynolds, Jacob G. The apparent solubility of aluminum (III) in Hanford high-level waste. United States. doi:10.1080/10934529.2012.707538.
Reynolds, Jacob G. Sat . "The apparent solubility of aluminum (III) in Hanford high-level waste". United States. doi:10.1080/10934529.2012.707538. https://www.osti.gov/servlets/purl/1047871.
@article{osti_1047871,
title = {The apparent solubility of aluminum (III) in Hanford high-level waste},
author = {Reynolds, Jacob G.},
abstractNote = {The solubility of aluminum in Hanford nuclear waste impacts on the process ability of the waste by a number of proposed treatment options. For many years, Hanford staff has anecdotally noted that aluminum appears to be considerably more soluble in Hanford waste than the simpler electrolyte solutions used as analogues. There has been minimal scientific study to confirm these anecdotal observations, however. The present study determines the apparent solubility product for gibbsite in 50 tank samples. The ratio of hydroxide to aluminum in the liquid phase for the samples is calculated and plotted as a function of total sodium molarity. Total sodium molarity is used as a surrogate for ionic strength, because the relative ratios of mono, di and trivalent anions are not available for all of the samples. These results were compared to the simple NaOH-NaAl(OH{sub 4})H{sub 2}O system, and the NaOH-NaAl(OH{sub 4})NaCl-H{sub 2}O system data retrieved from the literature. The results show that gibbsite is apparently more soluble in the samples than in the simple systems whenever the sodium molarity is greater than two. This apparent enhanced solubility cannot be explained solely by differences in ionic strength. The change in solubility with ionic strength in simple systems is small compared to the difference between aluminum solubility in Hanford waste and the simple systems. The reason for the apparent enhanced solubility is unknown, but could include. kinetic or thermodynamic factors that are not present in the simple electrolyte systems. Any kinetic explanation would have to explain why the samples are always supersaturated whenever the sodium molarity is above two. Real waste characterization data should not be used to validate thermodynamic solubility models until it can be confirmed that the apparent enhanced gibbsite solubility is a thermodynamic effect and not a kinetic effect.},
doi = {10.1080/10934529.2012.707538},
journal = {Journal of environmental science and health. Part A, Toxic/hazardous substances and environmental engineering},
issn = {1093-4529},
number = 14,
volume = 47,
place = {United States},
year = {2012},
month = {12}
}