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Synergism in binary mixtures of surfactants

1982; Elsevier BV; Volume: 90; Issue: 1 Linguagem: Inglês

10.1016/0021-9797(82)90414-3

1095-7103

Xi Yuan Hua, Milton J. Rosen,

Electrostatics and Colloid Interactions

Nonideal solution theory is used to derive equations for the conditions under which synergism can exist in aqueous binary mixtures of surfactants. For synergism in surface tension reduction efficiency, β, the experimentally obtained molecular interaction parameter at the aqueous solution/air interface, must be negative and ∥ln (C10C20)∥ must be <∥βM∥, where C10 and C20 are the solution phase molar concentrations of surfactants 1 and 2, respectively, required to produce a given surface tension (reduction). For synergism in mixed micelle formation, βM, the molecular interaction parameter in mixed micelle, must be negative and ∥ln (CIMC2M)∥ must be <∥βM∥, where C1M and C2M are the respective critical micelle concentrations (CMC) of surfactants 1 and 2. For synergism in surface tension reduction effectiveness, the condition is: f1,cXc < f1MXM, where XM and Xc are the mole fractions of surfactant 1 in the total surfactant in the mixed micelle and in the mixed monolayer at the aqueous solution/air interface, respectively, and f1,c and f1M are the activity coefficients in the surface phase at the CMC and in the micelle, respectively.