The zeta potential arising from cationic surfactant adsorption in non-aqueous dispersions of carbon black

✍ Scribed by S.R. Vasconcellos; R.L. Rowell

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 760 KB
• Volume: 25
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(87)90045-5

✦ Synopsis

The effect of counterion size of the cationic surfactants CTAC, CTAB and CTAS on the sign and magnitude of the zeta potential on Austin black dispersions in n-heptane and benzene were investigated. Zeta potentials were determined using single-particle microelectrophoresis.

Velocities were measured at the stationary levels; all the conditions for true electrophoresis were satisfied. The measured electrophoretic mobilities were converted to zeta potentials using the Htickel equation, corrected for relaxation effects. Results for n-heptane dispersions and a series on quaternary ammonium salts differing only in the size of the counterions, indicated a dependence on the sign and magnitude of the zeta potential on the nature of the counterion. The smallest counterion (chloride) gave negative zeta potentials, while the larger counterions yielded positive zeta potentials which increased with increasing size of the counterions. Similar trends were observed with the benzene dispersions. An ion-induced surface dipole mechanism was postulated to explain the observed phenomena.