Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

1 Publication
Uptake of selenium(VI) and selenium(IV) onto anatase and rutile
Jordan, N.; Foerstendorf, H.; Scheinost, A. C.; Lützenkirchen, J.; Schild, D.; Weiß, S.; Heim, K.; Brendler, V.;
In the context of nuclear waste management, long-term safety assessments have shown that selenium-79 could be one of the major isotopes contributing to the global radioactivity potentially reaching the biosphere. The present study focuses on the sorption of selenium oxyanions, i.e. selenium(VI) and selenium(IV), onto pure anatase and rutile phases, in order to complete the thermodynamic databases used for safety assessments of water contamination. A combination of both macroscopic (batch sorption and zeta potential measurements) and microscopic measurements (ATR FT-IR, EXAFS) have been used. To avoid an activation of anatase photocatalytic properties, all tubes were covered by aluminum foil. Results showed that both phases have higher affinity towards selenium(IV) compared to selenium(VI). Sorption of both oxyanions was at a maximum in the acidic pH range and decreased when the pH became more alkaline Batch experiments evidenced ionic strength dependence of the selenium(VI) sorption, while no impact was noticed for selenium(IV). No reduction of Se oxyanions at both homogenous and heterogeneous levels was noticed during HG-AAS and XPS measurements. During electrophoretic mobility measurements, no shift of the isoelectric point of anatase (pHIEP) upon selenium(VI) sorption was observed, while selenium(IV) retention decreased the pHIEP to lower pH values. Based on ATR FT-IR and EXAFS spectroscopic observations, we concluded that selenium(VI) is sorbed onto TiO2 as outer-sphere surface complexes, while selenium(IV) forms primarily inner-sphere complexes. Finally, selenium sorption onto TiO2 was described by a multisite surface complexation model (CD-MUSIC).
  • Contribution to proceedings
    Geological Disposal of Radioactive Waste: Underpinning Science and Technology, 18.-20.10.2011, Loughborough, United Kingdom
    Uptake of selenium(VI) and selenium(IV) onto anatase and rutile

Publ.-Id: 15801 - Permalink