Unraveling chemical speciation and interfacial dynamics in complex, heterogeneous
environments to efficiently process high-level radioactive wastes
EMSL Project ID
51194
Abstract
We propose to use NMR in combination with computational modeling, to study the conversion of soluble tetrahedral aluminum (Al) species to octahedrally coordinated Al-bearing mineral precipitates under strongly basic conditions typical of high-level nuclear wastes such as those at the Hanford Site. Key to efficient processing of these wastes is the ability to control the reaction mechanisms and kinetics that lead to stable solid precipitates, such as the Al-bearing minerals gibbsite and boehmite, in highly alkaline systems of concentrated electrolytes. We hypothesize that this control can be achieved by (i) manipulating solvation structures of key cations and anions; (ii) understanding solvent dynamics and solute organization; and (iii) determining the extent to which fluid phase dynamics influence pre-nucleation species, nucleation, and interfacial reactivity. We will test this hypothesis by conducting in-situ analyses under conditions of variable solution composition, pH and temperature. The complexity of these wastes is further exacerbated by the addition of megatons of organic compounds, such as glycolate and ethylenediaminetetraacetic acid (EDTA). We further hypothesize that the breakdown products of these organic compounds, such as CO2, HCO3- etc., will affect the reactivity and kinetics of Al tetrahedral to octahedral transformations, through incorporation into the solvation structures of electrolytes.
Project Details
Start Date
2019-10-15
End Date
2020-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Graham T.R., M. Dembowski, J.Z. Hu, N.R. Jaegers, X. Zhang, S.B. Clark, and C.I. Pearce, et al. 2020. "Intermediate Species in the Crystallization of Sodium Aluminate Hydroxy Hydrates." Journal of Physical Chemistry C 124, no. 23:12337-12345. PNNL-SA-150266. doi:10.1021/acs.jpcc.0c00205
Jones B.M., A. Aleksandrov, X. Zhang, K.M. Rosso, and T.M. Orlando. 2019. "Electron- and Thermal-Stimulated Synthesis of Water on Boehmite (y-AlOOH) Nanoplates." Journal of Physical Chemistry C 123, no. 31:18986-18992. PNNL-SA-145568. doi:10.1021/acs.jpcc.9b03927