LINKS BETWEEN BULK AND SURFACE-ACTIVITY IN MICELLAR SOLUTIONS

The surface tension of aqueous surfactant systems and its dependence o n the concentration of surfactant in micellar form, X(m) is-approximat ely-equal-to X- CMC, have been investigated. A modification of the ads orption equation, based on the introduction of activity coefficients, allows to get information on micelle aggregation numbers, [N], from th e slope of surface tension versus ln X(m). The resulting equation, tes ted on data relative to non ionic surfactants, gives aggregation value s in fair good agreement with those inferred from other methods. The l imits of the model are discussed in some detail.