Surface Electric Properties of the Na-Bentonite/Cetylpyridinium Chloride System as Studied by Reversing-Pulse Electric Birefringence
✍ Scribed by Viktor Peikov; Ryo Sasai; Stoyl P. Stoylov; Kiwamu Yamaoka
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 205 KB
- Volume
- 197
- Category
- Article
- ISSN
- 0021-9797
No coin nor oath required. For personal study only.
✦ Synopsis
as realistic models for dispersed systems in practical use. The adsorption of a cationic surfactant, cetylpyridinium chlo-Various experimental techniques such as static and dynamic ride (CPC), on disklike Na-bentonite particles has been studied light scattering, rheology, turbidimetry, etc., have been used in very dilute suspensions by reversing-pulse electric birefringence in these studies. In this aspect, the electro-optic methods (RPEB). The electric parameters of the particle/surfactant system (electric light scattering, electric birefringence, and rewere evaluated from signals taken at extremely low degrees of versing-pulse electric birefringence (RPEB)) give a unique orientation by using the ion-fluctuation RPEB theory. The electric opportunity for determining the surface electric properties field orientation of the particles was found to result from the and dipole moments of the colloid particle/additives comsimultaneous action of the polarizability anisotropy Da and the plex and provide useful information on the adsorption and ion-atmosphere polarizability a 3 caused by ion fluctuation. Two different CPC concentration ([CPC]
) ranges could be distin-desorption process of the additives, the thickness and conforguished according to the magnitude of the induced dipole moment mation of the adsorbed layers, the orientation of the adsorbed of the particles. When [CPC] was lower than 0.01 mM, the orientamolecules, and so forth (2).
tion of the particles was mainly due to the covalent polarizability
The process of adsorption of a cationic surfactant, cetylanisotropy Da. When [CPC] was higher than 0.01 mM, the ionic pyridinium chloride (CPC), on the surface of Na-bentonite polarizability a 3 was predominant over Da, the particles being particles was studied previously by electric light scattering oriented with the symmetric axis parallel to the direction of the (3). At low frequencies of the applied electric field and electric field. Values of the electric parameters of the particles higher CPC concentrations, the sign inversion of the electrochanged upon reversal of the sign of the applied reversing-pulse optic effect was observed. This so-called anomalous electroelectric field. The change was probably due to the reordering and/ optic effect corresponds to the orientation of a particle with or redistribution of the multilayer structure of adsorbed CPC molthe symmetric axis parallel to the direction of the electric ecules. Such effects were negligible below the critical [CPC] of 0.01 mM, where the adsorbed molecules may form a loose monolayer on field. The authors (3) showed that both the electro-optic the bentonite surface.