Chemistry at the hematite-technetium interface. Implication for technetium mobility
EMSL Project ID
48518
Abstract
Assessments of nuclear waste disposal options and remediation of contaminated sites start with accurate knowledge of radionuclide mobilization. Technetium-99 (Tc) (t1/2 = 200,000 y), as part of the 6% of the 99 isobar for the thermal yield of each U 235 and Pu-239, remains a challenge for waste management and remains a priority for the U.S. DOE and agencies of other countries. Tc has been found in groundwaters, sediments, and seas in the vicinity of nuclear processing sites, because of the high mobility of some Tc species and the complexity of its chemistry. The oxidation of state of Tc is the primary driver for Tc mobilization in the environment and it is greatly influence by the presence of iron (Fe). The oxidation of the sparingly soluble Tc(IV) to the highly mobile Tc(VII) by hematite (Fe(III)2O3) was recently observed and quantified, but this work lacks crucial data that would help further understand the system. The specific aim of this proposal is to utilize new capabilities in the EMSL radiochemistry annex to both confirm and extend preliminary results on Tc interactions with hematite initially found at WSU. Our objectives are:Objective A: Quantify Tc(IV) oxidation in presence of hematite, under sub-ppm level of O2.
Objective B: Determine the oxidation state of Tc on the surface on hematite using XPS.
The impact of this innovative research project is to provide fundamental understanding of Tc environmental chemistry, crucial for nuclear waste management and contaminated site remediation. The project is relevant to BER mission "to provide innovative solutions to the nation's environmental and energy production challenges [...] in subsurface science" and the fundamental understanding of Tc chemistry in the subsurface has been identified by DOE/BER to be of particular importance.
The state-of-the-art equipment capable to analyze radioactive samples at EMSL is essential for the success of this project and the fundamental understanding of Tc geochemical behavior. Additionally, the geographical proximity of Washington State University to PNNL will facilitates the completion of this work.
Project Details
Project type
Special Science
Start Date
2014-07-25
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Gribat L.C., J.T. Babauta, H. Beyenal, and N.O. Wall. 2017. "New Rotating Disk Hematite Film Electrode for Riboflavin Detection." Journal of Electroanalytical Chemistry 798. doi:10.1016/j.jelechem.2017.05.008