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  • Author or Editor: M. Ruiz Cruz x
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Abstract  

The thermal behaviour of the intercalation complex of a dickite from Tarifa, Spain, with dimethylsulfoxide was studied by high-temperature X-ray diffraction, differential thermal analysis and thermogravimetry, and attenuated total reflectance infrared spectroscopy. The ATR-FTIR study indicated that the heating between room temperature and 75C produced the elimination of adsorbed molecules. Above this temperature the elimination of intercalated molecules occurs through several stages. Loss of 6.5% of the intercalated DMSO first causes a slight contraction of the basal spacing at 90şC due to a rearrangement of the DMSO molecules in the interlayers positions. This contraction is followed by the formation of a single layer complex and the restoring of the dickite structure, at 300C, when the loss of intercalated species have been completed.

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Abstract  

A dickite from Tarifa (Spain) was used to study the influence of the intercalation and the later deintercalation of hydrazine on the dehydroxylation process. The dehydroxylation of the untreated dickite occurs through three overlapping endothermic stages whose DTA peaks are centred at 586, 657 and 676C. These endothermic effects correspond, respectively, to the loss of the inner-surface, the inner hydroxyl groups, and the loss of the water molecules, product of dehydroxylation process, which has been trapped in the framework of the dehydroxylated dickite. The intercalation of hydrazine in the interlayer space of dickite and the later deintercalation affect the dehydroxylation process. It occurs through only two endothermic stages which DTA peaks are centred at 575 and 650C. The first corresponds to the simultaneous loss of both the inner and the inner-surface hydroxyl groups, whereas the second one is analogous to that at 676C observed in the DTA curve of untreated dickite. These effects appear shifted to lower temperatures compared to those observed in the untreated dickite.

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