Effect of pressure on the adsorption of dodecylammonium chloride at the aqueous micellar solution/hexane interface

The effect of pressure on the adsorption behavior of dodecylammonium chloride (DAC) at the aqueous micellar solution/hexane interface has been investigated by measuring the interfacial tension as a function of pressure at concentrations around the critical micelle concentration (CMC). It has been observed that the derivative of the interfacial tension with respect to pressure changes abruptly at the CMC and there is very little change above the CMC with increasing concentration in the range studied. The volume changes associated with the adsorption of DAC from micellar state as well as from monomeric state have been evaluated by making use of the thermodynamic relations. It has been concluded that the behavior of the micelle in the limited concentration range is controlled solely by temperature and pressure and the structure of the micelle bears a resemblance to that of the adsorbed film at the interface.