Tc removal by mineral transformation of Fe(OH)2(s)
EMSL Project ID
48989
Abstract
The objective of this work is to provide additional fundamental understanding of the Tc removal by the mineral transformation process of ferrous hydroxide, Fe(OH)2(s) in solution. The data generated by the laboratory tests described in this effort will provide both empirical and scientific information to increase our understanding of the Tc removal process. Recent tests have shown that Tc can be removed from a simulated caustic off-gas scrubber and low-level waste solutions by a process that reduces pertechnetate, Tc(VII) to Tc(IV) which then co-precipitates with the magnetite and goethite mixture [1]. The final product also exhibits very slow weathering and low Tc leachability in subsurface environment conditions [2,3]. However, the process of Tc immobilization is not simple and cannot be applied in the field engineering tests for Tc removal. Despite the positive results obtained to date, both fundamental understanding at the molecular level and developing of the process that controls Tc(VII) reduction and immobilization of Tc(IV) in the final Fe oxide mineral product are necessary. Finally, the mechanism and kinetics of reoxidation of Tc(IV) in the final Fe oxide mineral product also needs to be determined to be certain that this Tc sequestration process will be sustained within various waste forms for the thousands of years required in shallow land burial environments such as the Hanford’s Integrated Disposal Facility (IDF).
Project Details
Start Date
2015-05-04
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Saslow S.A., W. Um, C.I. Pearce, M.E. Bowden, W.W. Lukens, M.H. Engelhard, and D. Kim, et al. 2018. "Cr(VI) Effect on Tc-99 Removal from Hanford Low-Activity Waste Simulant by Ferrous Hydroxide." Environmental Science & Technology 52, no. 20:11752-11759. PNNL-SA-135971. doi:10.1021/acs.est.8b03314