| Autor: |
Dobrogowska, C., Hepler, L. G., Ghosh, D. K, Yariv, Sh. |
| Zdroj: |
Journal of Thermal Analysis and Calorimetry; June 1991, Vol. 37 Issue: 6 p1347-1356, 10p |
| Abstrakt: |
Adsorption of the metachromic (colour depends on concentration) cationic dyes crystal violet (CV) and ethyl violet (EV) by Na-kaolinite and Na-montmorillonite has been studied by visible spectroscopy and titration calorimetry. In the kaolinite system, metachromasy stems from association of the dye cations on the external surface of the clay. Enthalpies of adsorption at small dye/clay ratios are −3.5 and −3.8 kJ/mol for CV and EV, respectively. In the montmorillonite system, which has been studied more thoroughly, metachromasy stems from theπ electron interactions between the dyes and the oxygen plane of the alumino-silicate. Enthalpies of adsorption (more exothermic than for kaolinite) depend on the dye/clay ratio in ways that are consistent with the spectra and the derived picture of dye/clay interactions. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
Full text from SpringerLink