Effects of isomeric alcohols on the phase behavior and solubilization of the microemulsion systems formed by anionic surfactants

The middle-phase ɛ-β fishlike phase diagrams of the pseudoquaternary microemulsion systems sodium dodecyl sulfate (sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate)/1-butanol (2-butanol, t-butanol)/n-octane/brine (5% NaCl) were plotted. The effect of three isomeric alcohols (1-butanol, 2-butanol, and t-butanol) on the phase behavior and solubilization was investigated. From the ɛ-β fishlike phase diagram, the composition of the interfacial layer, the solubilities of alcohols and the solubilization ability (the solubility parameter SP*, and the middle-phase volume fraction ϕ) of the microemulsion systems were calculated and discussed. The alcohol content in the interfacial layer and the solubilities of alcohols are in the order: 1-butanol < 2-butanol < t-butanol, but the solubilization ability is in the inverse order.