Effect of thermal dehydration and rehydration on Na-magadiite structure
| Autor: | Aline O. Moura, Alexandre G.S. Prado |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Chemistry
Scanning electron microscope Thermal decomposition Analytical chemistry Thermal treatment medicine.disease Exfoliation joint Surfaces Coatings and Films Electronic Optical and Magnetic Materials Biomaterials Thermogravimetry Colloid and Surface Chemistry medicine Dehydration Swelling medicine.symptom Thermal analysis Nuclear chemistry |
| Zdroj: | Journal of colloid and interface science. 330(2) |
| ISSN: | 1095-7103 |
| Popis: | The effect caused by dehydration and rehydration of the synthetic Na-magadiite was investigated by TGA, XRD, SEM, and (29)Si NMR. Thermal analysis of Na-magadiite presented two well-defined loss mass stages between 20 and 150 degrees C and another between 270 and 310 degrees C, both related to the removal of interlayer water. The swelling behavior of Na-magadiite was studied by thermal dehydration data obtained at 150 and 300 degrees C, and respective rehydration by water addition. X-ray patterns showed that the dehydration of Na-magadiite at 150 and 300 degrees C provoked the basal spacing decrease. The XRD also showed that only the material treated at 150 degrees C returned to the original structure with the rehydration. (29)Si NMR spectra showed that after rehydration, the Q(3)/Q(4) relationship presented the same value for Na-magadiite treated at 150 degrees C. However, this Q(3)/Q(4) value decreased when the treatment was done at 300 degrees C. Kinetic studies of thermal decomposition showed that the dehydration of magadiite is based on a phase boundary-controlled reaction, caused by contracting areas. The exfoliation of lamellas with thermal treatment can explain this behavior, as observed in SEM images. |
| Databáze: | OpenAIRE |
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