Thermodynamic properties of autunite, uranyl hydrogen phosphate, and uranyl orthophosphate from solubility and calorimetric measurements

Drew Gorman-Lewis, Tatiana Shvareva, Karrie Ann Kubatko, Peter C. Burns, Dawn M. Wellman, Bruce Mcnamara, Jennifer E.S. Szymanowski, Alexandra Navrotsky, Jeremy B. Fein

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

In this study, we use solubility and drop-solution calorimetry measurements to determine the thermodynamic properties of the uranyl phosphate phases autunite, uranyl hydrogen phosphate, and uranyl orthophosphate. Conducting the solubility measurements from both supersaturated and undersaturated conditions and under different pH conditions rigorously demonstrates attainment of equilibrium and yields well-constrained solubility product values. We use the solubility data and the calorimetry data, respectively, to calculate standard-state Gibbs free energies of formation and standard-state enthalpies of formation for these uranyl phosphate phases. Combining these results allows us also to calculate the standard-state entropy of formation for each mineral phase. The results from this study are part of a combined effort to develop reliable and internally consistent thermodynamic data for environmentally relevant uranyl minerals. Data such as these are required to optimize and quantitatively assess the effect of phosphate amendment remediation technologies for uranium contaminated systems.

Original languageEnglish (US)
Pages (from-to)7416-7422
Number of pages7
JournalEnvironmental Science and Technology
Volume43
Issue number19
DOIs
StatePublished - Oct 1 2009
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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