Arsenic uptake by gypsum and calcite: Modeling and probing by neutron and x-ray scattering - Physics > Chemical PhysicsReportar como inadecuado




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Abstract: Here we report on two structural studies performed on As-doped gypsum CaSO42H2O and calcite CaCO3, using neutron D20-ILL and x-ray ID11-ESRFdiffraction data and EXAFS BM8-ESRF. The aim of this study is to determinewhether As gets into the bulk of gypsum and calcite structures or is simplyadsorbed on the surface. Different mechanisms of substitution are used ashypotheses. The combined Rietveld analysis of neutron and x-ray diffractiondata shows an expansion of the unit cell volume proportional to the Asconcentration within the samples. DFT-based simulations confirm the increase ofthe unit cell volume proportional to the amount of carbonate or sulphate groupssubstituted. Interpolation of the experimental Rietveld data allows us todistinguish As substituted within the structure from that adsorbed on thesurface of both minerals.



Autor: Alejandro Fernandez-Martinez ILL, LGIT, Gabriel J. Cuello ILL, Gabriela Roman-Ross LGIT, Mark R. Johnson ILL, Fabrizio Bardelli G

Fuente: https://arxiv.org/







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