Synergistic behaviour of ZnO nanoparticles and gemini surfactants on the dynamic and equilibrium oil/water interfacial tension.

In this work the effect of ZnO nanoparticles on the interfacial behaviour of gemini surfactants (12-3-12 and 14-3-14) at the oil/water interface was investigated. Equilibrium and dynamic interfacial tension in the absence and presence of ZnO was measured and compared. The results show that the synergistic interactions between the surfactants and nanoparticles decrease the interfacial tension beyond that observed for each component, alone. Modelling of dynamic data with two different models indicates that the mechanism of surfactant migration (with and without ZnO) is mixed diffusion-kinetic-control. The Gibbs free energy of micellization and the Gibbs free energy of adsorption in the absence and presence of ZnO were calculated and compared. Finally the effect of addition of ZnO nanoparticles on emulsion stability was also examined.