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Title: Formation of calcium and magnesium molybdate complexes in dilute aqueous solutions and evaluation of powellite solubility in spent oil shale

Abstract

In order to increase our understanding of the chemistry of molybdenum (Mo) in spent oil shale disposal environments, predict fate and behavior, and assess the effectiveness of proposed mitigation techniques, we feel that is imperative to understand the processes controlling Mo aqueous- and solid-phase distribution. Recent research supports the significance of alkaline earth and alkali metal ion pairs with molybdate in aqueous solutions. The objectives of this study were to measure the ion association constants (log Q) for the formation of calcium and magnesium molybdate ion pairs by potentiometric titration at pH 7 and 25{degree}C in NaNO{sub 3} ionic media. The measured values were then used to examine the equilibrium solubility of powellite (CaMoO{sub 4}) in KNO{sub 3} solutions and spent oil shale systems. Powellite solubility data were evaluated using log Q for CaMoO{sub 4}{sup 0} formation, resulting in a calculated log K{sub sp} for powellite dissolution of -7.84. Application of an ion association model that used the molybdate ion pair formation data shows that spent oil shale leachates are undersaturated with respect to powellite. The results of this study show that molybdate ion pair formation in spent oil shale solutions may be significant and that soluble Mo concentrations maymore » not be supported by powellite dissolution. 31 refs., 10 figs., 4 tabs.« less

Authors:
;
Publication Date:
Research Org.:
Western Research Inst., Laramie, WY (USA)
Sponsoring Org.:
DOE/FE
OSTI Identifier:
6554591
Report Number(s):
DOE/MC/11076-2851
ON: DE90009663
DOE Contract Number:  
FC21-86MC11076
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
04 OIL SHALES AND TAR SANDS; CALCIUM COMPOUNDS; SOLUBILITY; MOLYBDATES; SPENT SHALES; LEACHING; AQUEOUS SOLUTIONS; ENVIRONMENTAL TRANSPORT; EQUILIBRIUM; ION PAIRS; MAGNESIUM COMPOUNDS; POTASSIUM NITRATES; POTENTIOMETRY; REGRESSION ANALYSIS; ALKALI METAL COMPOUNDS; ALKALINE EARTH METAL COMPOUNDS; DISPERSIONS; DISSOLUTION; MASS TRANSFER; MATHEMATICS; MIXTURES; MOLYBDENUM COMPOUNDS; NITRATES; NITROGEN COMPOUNDS; OXYGEN COMPOUNDS; POTASSIUM COMPOUNDS; REFRACTORY METAL COMPOUNDS; SEPARATION PROCESSES; SOLUTIONS; STATISTICS; TITRATION; TRANSITION ELEMENT COMPOUNDS; 040500* - Oil Shales & Tar Sands- Properties & Composition; 041000 - Oil Shales & Tar Sands- Environmental Aspects

Citation Formats

Essington, M E, and Huntington, G S. Formation of calcium and magnesium molybdate complexes in dilute aqueous solutions and evaluation of powellite solubility in spent oil shale. United States: N. p., 1990. Web.
Essington, M E, & Huntington, G S. Formation of calcium and magnesium molybdate complexes in dilute aqueous solutions and evaluation of powellite solubility in spent oil shale. United States.
Essington, M E, and Huntington, G S. Thu . "Formation of calcium and magnesium molybdate complexes in dilute aqueous solutions and evaluation of powellite solubility in spent oil shale". United States.
@article{osti_6554591,
title = {Formation of calcium and magnesium molybdate complexes in dilute aqueous solutions and evaluation of powellite solubility in spent oil shale},
author = {Essington, M E and Huntington, G S},
abstractNote = {In order to increase our understanding of the chemistry of molybdenum (Mo) in spent oil shale disposal environments, predict fate and behavior, and assess the effectiveness of proposed mitigation techniques, we feel that is imperative to understand the processes controlling Mo aqueous- and solid-phase distribution. Recent research supports the significance of alkaline earth and alkali metal ion pairs with molybdate in aqueous solutions. The objectives of this study were to measure the ion association constants (log Q) for the formation of calcium and magnesium molybdate ion pairs by potentiometric titration at pH 7 and 25{degree}C in NaNO{sub 3} ionic media. The measured values were then used to examine the equilibrium solubility of powellite (CaMoO{sub 4}) in KNO{sub 3} solutions and spent oil shale systems. Powellite solubility data were evaluated using log Q for CaMoO{sub 4}{sup 0} formation, resulting in a calculated log K{sub sp} for powellite dissolution of -7.84. Application of an ion association model that used the molybdate ion pair formation data shows that spent oil shale leachates are undersaturated with respect to powellite. The results of this study show that molybdate ion pair formation in spent oil shale solutions may be significant and that soluble Mo concentrations may not be supported by powellite dissolution. 31 refs., 10 figs., 4 tabs.},
doi = {},
url = {https://www.osti.gov/biblio/6554591}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1990},
month = {2}
}

Technical Report:
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