ADSORPTION OF DODECYLTRIMETHYLAMMONIUM CHLORIDE-DECYLAMMONIUM CHLORIDE MIXTURES AT WATER/AIR INTERFACE.

Abstract

The surface tension of the aqueous solution of dodecyltrimethylammonium chloride and decylammonium chloride mixture has been measured as a function of the total concentration and composition of the surfactants at 298. 15 K under atmospheric pressure. It has been observed that the surface tension decreases with an increase in the composition of dodecyltrimethylammonium chloride at a fixed total concentration. A break point has been observed on the surface tension vs. total concentration curve. By applying the thermodynamic relations, the surface densities of surfactants have been evaluated numerically. It is proved that the phase transition of the mixed adsorbed film takes place from a gaseous to an expanded state at the break point.