FORMATION OF MIXED AGGREGATES AT THE ALUMINA-AQUEOUS SURFACTANT SOLUTION INTERFACE

The mixed critical hemimicelle concentrations of dodecyl benzenesulfon ate and dodecyl sulfate adsorbed on alumina from an aqueous solution h ave been determined using zeta potential measurements. The critical mi celle concentrations of aqueous solutions of mixed surfactants have be en determined using surface tension measurements. It is found that whe reas mixed micelle formation shows ideal behavior, the mixed hemimicel le formation shows positive deviation from ideality. The results have been explained based on the equivalent contribution of 3.5 methylene g roups by the aromatic benzene ring in dodecyl benzenesulfonate. Rubing h theory has been applied to the formation of the hemimicelle.