THE MICELLAR DISSOCIATION CONCENTRATION OF SOME COMMERCIAL SURFACTANTS CONTAINING CARBOXYMETHYL ETHOXYLATES

This paper will give some illustration of a method of determination of the micellar dissociation concentration (m.d.c.) of some commercial surfactants containing carboxymethyl ethoxylates (CME). These surfactants have a common structure of RO(CH2CH2O)itnCH2COONa, characterized by high electrolyte tolerance and thermal stability, which are very desirable for detergent application and enhanced oil recovery. Three samples with R = C9H19(C6H4 and n = 4,5 and 6 were used in this study. Turbidity and surface tension measurements were performed in the sample solutions with and without the addition of KCl or CaCl2. Complicated figures were obtained by these measurements. It is difficult to determine the critical micellar concentration (c.m.c.) for these surfactants. However, it is possible to determine the m.d.c. values from the measured curves. The m.d.c. values determined in this study follow the same order as one would normally expect for the c.m.c. values. It seems more practical to determine the m.d.c. value than the c.m.c. value for an impure surfactant system. © 1990.