Kaolinites structural defects related to urea and dimethyl sulfoxide intercalation
Résumé
In this study, the influence of structural defects in kaolinites on the intercalation processes of urea and dimethyl sulfoxide (DMSO) is explored. Four samples of kaolins with kaolinite having variable levels of crystallinity were subjected to DMSO and Urea intercalation. Analyses including X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and differential scanning calorimetry coupled to thermogravimetric analysis (DSC-TGA) were used for characterization. From these analyses, structural defects of the samples were evaluated using Hinckley index (HI), Slope Ratio (SR), factor P0 and R2 test. The change in the size of the coherent scattering domain almost keep constant the number of layer per crystallite in each sample, indicating a preservation of the structural order and the same intercalation mechanism for both molecules. For both urea and DMSO intercalation, the intercalation ratios (IR) were positively correlated to HI, P0 and SR. The correlation to defect type shows that the defects due to random translation of the layer, that are associated to the R2 factor, have almost no influence on the intercalation ratio. Hence, only defects in the plane affect the intercalation ratio and this is in line with the crystallinity influence.
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