Influence of Microscopic Mass Transfer on the Reactivity and Stability of Uranium
EMSL Project ID
4691a
Abstract
This proposed project will investigate microscopic U(VI) mass transfer under influence of biogeochemical reactions in representative Hanford U(VI)-contaminated sediments. Recent research by our group has revealed that solid phase U(VI) exists in complex, microscopic, intragrain domains in Hanford sediments. The fate and transport of in-ground U(VI) is expected to be controlled by the coupling of intragrain U(VI) desorption/dissolution with intergrain biogeochemical reactions through diffusive mass transfer that controls mass exchange between the intra- and inter- grain regions. The research strives to understand this coupled process under chemical/activity gradients as driven by three types of biogeochemical reactions that are relevant to engineered remediation and natural attenuation: 1) aqueous U(VI) complexation; 2) microbially induced reduction of U(VI) to U(IV); and 3) ligand-promoted U(VI) dissolution and reprecipitation. Batch and flow-through experiments will be performed to explore U(VI) mass transfer under influence of biogeochemical reactions. Microscopic and spectroscopic characterization will be used to provide insights on process mechanisms. The experiments and characterization will provide data to: 1) quantify the rates of microscopic U(VI) mass transfer and its coupling with biogeochemical reactions; 2) develop numerical models for description of individual and coupled processes; and 3) evaluate the stability and reactivity of in-ground U(VI).
Project Details
Project type
Exploratory Research
Start Date
2007-03-14
End Date
2008-03-23
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Molecular simulation of the diffusion of uranyl carbonate species in aqueous solution
Kerisit SN, and C Liu. 2010. "Molecular Simulation of the Diffusion of Uranyl Carbonate Species in Aqueous Solution." Geochimica et Cosmochimica Acta 74(17):4937-4952. doi:10.1016/j.gca.2010.06.007
Microbial Reduction of Intragrain U(VI) in Contaminated Sediment
Liu C, JM Zachara, L Zhong, SM Heald, Z Wang, BH Jeon, and JK Fredrickson. 2009. "Microbial Reduction of Intragrain U(VI) in Contaminated Sediment." Environmental Science & Technology 43(13):4928-4933. doi:10.1021/es8029208
A cryogenic fluorescence spectroscopic study of uranyl carbonate, phosphate and oxyhydroxide minerals
Wang Z, JM Zachara, C Liu, PL Gassman, AR Felmy, and SB Clark. 2008. "A cryogenic fluorescence spectroscopic study of uranyl carbonate, phosphate, and oxyhydroxide minerals." Radiochimica Acta 96(9-11):591-598. doi:10.1524/ract.2008.1541