Back to Search
Start Over
Structure of organoclays—an X-ray diffraction and thermogravimetric analysis study
- Source :
-
Journal of Colloid & Interface Science . Sep2004, Vol. 277 Issue 1, p116-120. 5p. - Publication Year :
- 2004
-
Abstract
- X-ray diffraction has been used to study the changes in the surface properties of a montmorillonitic clay through the changes in the basal spacings of montmorillonite (SWy-2) and surfactant-intercalated organoclays. Variation in the <f>d</f>-spacing was found to be a step function of the surfactant concentration. High-resolution thermogravimetric analysis (HRTG) shows that the thermal decomposition of SWy-2-MMTs modified with the surfactant octadecyltrimethylammonium bromide takes place in four steps. A mass-loss step is observed at room temperature and is attributed to dehydration of adsorption water. A second mass-loss step is observed over the temperature range 87.9 to 135.5 °C and is also attributed to dehydration of water hydrating metal cations such as Na+. The third mass loss occurs from 178.9 to 384.5 °C and is assigned to a loss of surfactant. The fourth mass-loss step is ascribed to the loss of OH units through dehydroxylation over the temperature range 556.0 to 636.4 °C. A model is proposed in which, up to 0.4 CEC, a surfactant monolayer is formed between the montmorillonitic clay layers; up to 0.8 CEC, a lateral-bilayer arrangement is formed; and above 1.5 CEC, a pseudotrimolecular layer is formed, with excess surfactant adsorbed on the clay surface. [Copyright &y& Elsevier]
- Subjects :
- *SURFACE active agents
*SMECTITE
*SURFACE chemistry
*CLAY
Subjects
Details
- Language :
- English
- ISSN :
- 00219797
- Volume :
- 277
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Journal of Colloid & Interface Science
- Publication Type :
- Academic Journal
- Accession number :
- 13905603
- Full Text :
- https://doi.org/10.1016/j.jcis.2004.04.053