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Adsorption of Selenium and Strontium on Goethite: EXAFS Study and Surface Complexation Modeling of the Ternary Systems

Nie, Zhe; Finck, Nicolas; Heberling, Frank; Pruessmann, Tim; Liu, Chunli; Lützenkirchen, Johannes

Abstract (englisch):
Knowledge of the geochemical behavior of selenium and strontium is critical for the safe disposal of radioactive wastes. Goethite, as one of the most thermodynamically stable and commonly occurring natural iron oxy-hydroxides, promisingly retains these elements. This work comprehensively studies the adsorption of Se(IV) and Sr(II) on goethite. Starting from electrokinetic measurements, the binary and ternary adsorption systems are investigated and systematically compared via batch experiments, EXAFS analysis, and CD-MUSIC modeling. Se(IV) forms bidentate inner-sphere surface complexes, while Sr(II) is assumed to form outer-sphere complexes at low and intermediate pH and inner-sphere complexes at high pH. Instead of a direct interaction between Se(IV) and Sr(II), our results indicate an electrostatically driven mutual enhancement of adsorption. Adsorption of Sr(II) is promoted by an average factor of 5 within the typical groundwater pH range from 6 to 8 for the concentration range studied here. However, the interaction between Se(IV) and Sr(II) at the surface is two-sided, Se(IV) promotes Sr(II) outer-sphere adsorption, but competes ... mehr

Zugehörige Institution(en) am KIT Institut für Katalyseforschung und -Technologie (IKFT)
Institut für Nukleare Entsorgung (INE)
Publikationstyp Zeitschriftenaufsatz
Jahr 2017
Sprache Englisch
Identifikator DOI: 10.1021/acs.est.6b06104
ISSN: 0013-936X, 1520-5851
KITopen ID: 1000068765
Erschienen in Environmental science & technology
Band 51
Heft 7
Seiten 3751-3758
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