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GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 234-25
Presentation Time: 9:00 AM-6:30 PM

STRUCTURAL STABILITY AND THERMODYNAMICS OF URANYL VANADATE MINERALS


SPANO, Tyler L., Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 301 Stinson Remick Hall, Notre Dame, IN 46556, DZIK, Ewa, Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 301 Stinson-Remick Hall, Notre Dame, IN 46556, SHARIFIRONIZI, Melika, Civil and Environmental Engineering and Earth Science, Uni of Notre Dame, 301 Stinson Remick Hall, Notre Dame, IN 46637, DUSTIN, Megan K., Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, TURNER, Madison, Department of Geology, University of Maryland, College Park, MD 20742 and BURNS, Peter C., Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556, tspanofr@nd.edu

Uranyl vanadate minerals are highly insoluble and are widely disseminated in uranium ore deposits and mine and mill tailings in which primary uranium and vanadium minerals are undergoing oxidation. Understanding the crystal chemistry, materials properties, and thermodynamics of uranyl vanadate minerals is an essential step for predicting and controlling the long term environmental behavior of uranium. Delineating crystal chemical changes as related to thermodynamic properties enables prediction of stable structural arrangements. Uranyl vanadate mineral analogues have been synthesized using mild hydrothermal methods. Synthetic uranyl vanadate mineral analogues were investigated using high-temperature drop solution calorimetry. Calculated standard-state enthalpies of formation were found to be -5233.97 ± 14.594, -6028.41 ± 9.36, and -4908.78 ± 12.59 kJ•mol-1 for carnotite (K2[(UO2)2(V2O8)]•3H2O), francevillite (Ba[(UO2)2(V2O8)]•5H2O), and curienite (Pb[(UO2)2(V2O8)]•5H2O), respectively. Enthalpies of formation from oxides for uranyl vanadate minerals exhibit a positive linear correlation as a function of the acidity of oxides. Overall charge deficiency (OCD) is presented as a quantification of the balance of bond strengths between structural units and interstitial complexes. A negative exponential correlation was observed between OCD and structural stability (enthalpy of formation from oxides) for the studied minerals. Additionally, OCD and oxide acidity exhibit a positive exponential correlation where decreasing oxide acidity results in an exponential decrease in OCD. The number of occurrences of uranyl vanadate mineral species is found to correlate with both enthalpy of formation from oxides and OCD.

Session No. 234--Booth# 30

T14. Geologic Energy Research (Posters)
Tuesday, 27 September 2016: 9:00 AM-6:30 PM
Exhibit Hall E/F (Colorado Convention Center)
Geological Society of America Abstracts with Programs. Vol. 48, No. 7
doi: 10.1130/abs/2016AM-279636
© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
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