Reduction of Se(IV) in boom clay: XAS solid phase speciation.
The geochemical fate of selenium is of key importance for today's society due to its role as a highly toxic essential micronutrient and as a significant component of high level radioactive waste (HLRW) originating from the operation of nuclear reactors. Understanding and prediction of the long-term behavior of Se in natural environments requires identification of the in situ speciation of selenium. This article describes an XAS-based investigation into the solid phase speciation of Se upon interaction of Se(IV) with Boom Clay, a reducing, complex sediment selected as model host rock for clay-based deep geological disposal of HLRW in Belgium and Europe. Using a combination of long-term batch sorption experiments, linear combination XANES analysis and ITFA-based EXAFS analysis allowed for the first time to identify Se0 as the dominant solid phase speciation of Se in Boom Clay systems equilibrated with Se(IV).
Breynaert
Eric
E
K.U.Leuven, Center for Surface Chemistry and Catalysis, Department M2S, Kasteelpark Arenberg 23-bus 2461, B-3001 Leuven, Belgium. eric.breynaert@biw.kuleuven.be
Scheinost
Andreas C
AC
Dom
Dirk
D
Rossberg
André
A
Vancluysen
Jacqueline
J
Gobechiya
Elena
E
Kirschhock
Christine E A
CE
Maes
André
A
D000538:Aluminum Silicates / Q000737:chemistry*; D000077215:Clay; D005163:Factor Analysis, Statistical; D010084:Oxidation-Reduction; D012643:Selenium / Q000737:chemistry*; D012996:Solutions; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
D000538:Aluminum Silicates; D012996:Solutions; D012643:Selenium; D000077215:Clay