Study on a Ternary Surfactant System of Disodium Hexadecyl Diphenyl Ether Disulfonate, Dodecyldimethyl Hydroxyethyl Ammonium Chloride and Fatty Alcohol Polyoxyethylene Ether

This study was focused on a ternary complex system composed of hexadecyl diphenyl ether disulfonate (C-16-MADS), dodecyl dimethyl hydroxyethyl ammonium chloride (K-3) and fatty alcohol polyoxyethylene ether (AEO(9)). The binary mixture C-K consisting of C-16-MADS and K-3 was investigated and the maximum synergism was obtained when the mole ratio was 0.33:0.67. Subsequently, AEO(9) was added to the binary C-K complex system to investigate whether the behavior of the new complex system, in which C-K is thought to be a surfactant, can be explained by the theory of regular solution. The maximum synergism was achieved when the molar ratio of C-K and AEO(9) was 7:3. The regular solution theory could well explain the synergism in mixed micelle formation and the synergism in surface tension reduction efficiency, but the synergism in surface tension reduction effectiveness did not match with the experimental data. So, there still exist some deficiencies in the application of the regular solution theory to a complex system of three surfactants.