The synergism of mixtures of anionic and non-ionic surfactants adsorbed at the water/alkane interface was studied using mesoscopic Dissipative Particle Dynamic simulations. The effect of the mixtures of sodium m, p-exylbenzenesulfonate and sodium m, p-octylbenzenesulfonate with the nonionic surfactant lauryl alcohol polyoxyethylene (9) ether on the surface tension of the water/alkane interface was explored. Alkane scanning curves for n-alkanes from hexane to tetradecane are reported. Our results suggest that dissolution of lauryl alcohol polyoxyethylene (9) ether in the hydrocarbon phase is the origin of this behavior. For the sodium m, p-octylbenzenesulfonate case, the mixture with lauryl alcohol polyoxyethylene (9) ether induces a synergism for alkanes with low carbon number. A moderate lipophilic behavior of the mixture was observed for hexane and as a result 95% of the mixture stays at the interface forming a really compact layer at the interface. Additionally, increase on the carbon number alkane produces an increase in the hydrophilic behavior of lauryl alcohol polyoxyethylene (9) ether inducing higher interfacial tension values.

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