SREL Reprint #3503

Porous iron material for TcO4- and ReO4- sequestration from groundwater under ambient oxic conditions

Dien Li1, John C. Seaman2, Simona E. Hunyadi Murph1,3, Daniel I. Kaplan1, Kathryn Taylor-Pashow1,
Renfei Feng4, Hyunshik Chang5, and Madan Tandukar5

1Savannah River National Laboratory, Aiken, SC, 29808, USA
2Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, 29802, USA
3Department of Physics and Astronomy, University of Georgia, Athens, GA, 30602, USA
4Canadian Light Source, Saskatoon, SK, S7N 0X4, Canada
5Höganäs Environmental Solutions LLC, Cary, NC, 27513, USA

Abstract: Technetium-99 (99Tc) is a major contaminant at nuclear power plants and several US Department of Energy sites. Its most common aqueous species, pertechnetate (TcO4-), is very mobile in the environment, and currently there are no effective technologies for its sequestration. In this work, a porous iron (pFe) material was investigated for TcO4- and perrhenate (ReO4-) sequestration from artificial groundwater. The pFe was significantly more effective than granular iron for both TcO4- and ReO4- sequestration under oxic conditions. The Tc removal capacity was 27.5 mg Tc/g pFe at pH ˜6.8, while the Re removal capacity was 23.9 mg Re/g pFe at pH ˜10.6. Tc K-edge XANES and EXAFS analyses indicated that the removed Tc species was 70–80% Tc(IV) that was likely incorporated into Fe corrosion products (i.e., Fe(OOH), Fe3O4) and 20–30% unreduced TcO4-. In contrast, the removed Re species was ReO4- only, without detectable Re(IV). In addition, the sequestered ReO4- was not extracted (< 3%) by 0.1 M Na2SO4 and 1 M KI solution, which indicated that ReO4- and by chemical analogy, unreduced TcO4-, was likely incorporated into Fe corrosion products. This inexpensive pFe material may be applied to the sequestration and stabilization of 99TcO4- from contaminated environments and nuclear waste streams.

Keywords: Pertechnetate; Perrhenate; Porous iron; Synchrotron XANES and EXAFS

SREL Reprint #3503

Li, D., J. C. Seaman, S. E. Hunyadi Murph, D. I. Kaplan, K. Taylor-Pashow, R. Feng, H. Chang, and M. Tandukar. 2019. Porous iron material for TcO4- and ReO4- sequestration from groundwater under ambient oxic conditions. Journal of Hazardous Materials 374(2019): 177-185.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).