A HOLISTIC APPROACH TO MULTICOMPONENT EXAFS: SR COMPLEXATION IN CLAYEY SOIL (Invited Presentation)
In this study we investigated the geochemical speciation of Sr in clayey soils by performing a comprehensive set of adsorption experiments (on single minerals and a clayey soil) and subsequent X-ray absorption spectroscopy analyses. Furthermore, in order to fully benefit from such experimental and analytical methodologies, we developed and utilized a comprehensive dual/holistic approach to fitting multicomponent EXAFS. First, a shell-by-shell fitting strategy enabled us to determine Sr complexation with anatase and illite-smectite through bidentate edge sharing complexes and with kaolinite at the silicon vacancy sites on the basal surface . Subsequently, we utilized a holistic approach to determine predominance of each of these complexes within a composite clayey soil to inform that Sr complexation with kaolinite (25-30%) and illite-smectite (72-76%) governs Sr speciation in clayey soils . The presented surface complexation and dual/holistic approach to fitting EXAFS spectra will strengthen predictive modelling on the behaviour of elements of interest.
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