Effect of ZnO nanoparticles on the interfacial behavior of anionic surfactant at liquid/liquid interfaces

Dynamic and equilibrium interfacial tension of sodium dodecyl sulfate as anionic surfactant in the presence of ZnO nanoparticles was measured. The results show that the presence of ZnO nanoparticles makes the SDS molecules more efficient to decrease the interfacial tension. Simultaneous adsorption of nanoparticles and surfactants at the interface, make a synergistic effect for higher decrease of interfacial tension. By fitting of dynamic surface concentrations data (in the absence and presence of ZnO nanoparticles) with two different models it was found that the mechanism of surfactant migration is controlled with mixed diffusion–kinetic control model. Also the effects of ZnO nanoparticles on the contact angle and emulsions stability were investigated. Finally the effect of pH solution on the dynamic interfacial tension was studied, as well.