Effect of the Hydrophilic-Lipophilic Ability on Dynamic Interfacial Tensions of Alkylbenzene Sulfonates

Experimental studies have been conducted to explore the mechanisms responsible for the dynamic interfacial tension (IFT) behavior in surfactant/model oil systems. Two multi-n-alkylbenzene sulfonates with high purity were selected as model components, and the dynamic IFTs of the two surfactant solutions against a homologous series of alkanes were measured. The effect of n-octadecanol in oil phase on dynamic IFT behavior has been investigated. The experimental results show that there exist two types of the dynamic IFT curves: for one type of curve, the IFT value drops quickly to the stable value, and for the other type, the IFT value passes through a minimum quickly and soon increases to the stable value. The hydrophilic-lipophilic ability of the surfactant plays the most important role in dynamic IFT behavior. The addition of n-octadecanol will result in the appearance of the IFT minimum at hydrocarbons with a larger alkane carbon number, which can strongly support our explanation.