The important role the hydrophilic−lipophilic ability of the surfactant played in interfacial tension (IFT) behavior has been recognized early. The thermodynamic model based on the surfactant affinity difference (SAD) concept has been developed and successfully employed to microemulsions. However, according to the theoretical models developed by Blankschtein et al., the molecular size of the surfactant is another important factor on IFT, which can be reflected by the crosssectional area of the adsorbed surfactant molecules, a s . In this paper, based on the concept of a s , the influences of temperature and electrolyte on IFT were expounded. The experimental results show that ultralow IFTs can be obtained only when the surfactant has appropriate hydrophilic−lipophilic ability and a s . The addition of electrolyte can enhance the hydrophobic ability of the surfactant, which improves the n min value. However, the IFT min values pass through a minimum with increasing NaCl concentration, resulting from the responsible mechanisms of enhancement of adsorption amounts and reducing the size of the hydrophilic part during the low and high NaCl concentration range, respectively. An increase in the temperature appears to cause an increase in the surfactant solubility and a consequent decrease in the n min value. Moreover, the IFT min increases with increasing temperature until a plateau because the molecular motion speeds up, which increases the solvent molecules in the adsorbed layer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.