Abstract
The effect of different alkyl chains of anionic surfactants on properties of binary anionic‐nonionic mixed surfactant systems was studied. These systems included ocytldodecyl‐, and cetylsulfoacetates mixed with isooctyl phenol nonyl ethoxylate. The critical micelle concentration of mixed surfactants shifted to lower values compared to those of the single anionic surfactants. Effectiveness values increased with decreases in the mole fraction of anionic surfactants. The negative values of interaction parameter (β) increased with increases in the chain length of anionic surfactants.