Using in situ X-ray diffraction and the Rietveld method combined with the maximum entropy method, we investigated the interaction of water with sodium faujasite and determined the sodium and water… Click to show full abstract
Using in situ X-ray diffraction and the Rietveld method combined with the maximum entropy method, we investigated the interaction of water with sodium faujasite and determined the sodium and water sorption sites as a function of water content. From the information contained in the lowest diffraction-angle peaks, we found that water also interacts with faujasite, forming a shell-like layer inside the supercages located at a mean distance of 2.8 A from the pore-wall oxygens. For water-saturated faujasite, this shell has a surface density comparable to liquid water. The ion-exchange sites and ordered water found inside the supercage are embedded in this layer. We included the water shell contribution in Rietveld refinements by modeling it as a hollow sphere scatterer inside the faujasite supercages, and the refined water and cation quantities have agreed with nominal values.
               
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