Micellization in solutions of anionic surfactants with two ionogenic groups

Conductometry is employed to measure the critical micellization concentrations of homologous sodium monoalkyl sulfosuccinates with double-charged surface-active anions and alkyl radicals R containing 10-14 carbon atoms (ROOCCH2CH(SO3Na)COONa). The degrees of counterion binding with micelles and the Gibbs energy Delta G(m) of micellization are calculated. The incorporation of an additional ionogenic group into a surfactant molecule somewhat decreases Delta G(m). For the examined series of surfactants, the increment of Delta G(m) due to one methylene group is -4.44 kJ/mol.