Reduction of Se(IV) in Boom Clay: XAS Solid Phase Speciation

• Published in: Environmental science & technology 2010-09, Vol.44 (17), p.6649-6655
• Main Authors: Breynaert, Eric, Scheinost, Andreas C, Dom, Dirk, Rossberg, André, Vancluysen, Jacqueline, Gobechiya, Elena, Kirschhock, Christine E. A, Maes, André
• Format: Article
• Language: English
• Subjects: Aluminum Silicates - chemistry; Applied sciences; Clay; Environmental Processes; Exact sciences and technology; Factor Analysis, Statistical; Geochemistry; Nuclear reactors; Oxidation-Reduction; Pollution; Selenium; Selenium - chemistry; Solutions; Sorption; Toxicity; X-Ray Absorption Spectroscopy; X-Ray Diffraction
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es100569e

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).