Synergism in mixtures of nano benzimidazolium Gemini ionic liquid and sodium dodecyl sulfate surfactants in tuning interfacial properties of crude oil−water system.

[Display omitted] • The benzimidazolium Gemini surface active ionic liquid could strongly reduce the system interfacial tension. • Synergisms of 97.6 and 83.9% in interfacial tension and critical micelle concentration reductions with mixtures. • Mixtures could create stable dispersions of crude oil in water and alter the wettability. • Reproducing the interfacial tension data with theories of Frumkin and non-ideal interactions in binary mixtures. • Mixtures of benzimidazolium Gemini surface active ionic liquid work stronger than those of imidazolium ionic liquid. The high price of newly explored surfactants is a concern in applications, but their mixture with conventional surfactants can bring about desired outcomes. Gemini surface active ionic liquids (GSAILs) have emerged as unique materials in tuning interface properties. Surfactants like sodium dodecyl sulfate (SDS), on the other hand, are known effective and commercially available. This study investigates the simultaneous effects of a benzimidazolium cationic GSAIL, [C 4 benzim-C 6 -benzimC 4 ][Br 2 ], and SDS surfactants on the interfacial tension (IFT), emulsification, and wettability alteration of the crude oil−water system. The results demonstrate amazing synergies up to 97.6 % in the IFT reduction. An ultra-low IFT of 0.16 mN·m−1 was achieved with an optimum GSAIL mole fraction of 0.4, attributed to the attractive interaction between the cationic GSAIL and the anionic SDS. Mixtures also give 54.3 and 72.8 % synergies in emulsification and wettability alteration, respectively. The adsorption of individual and mixture of surfactants were theoretically analyzed using the Frumkin adsorption isotherm and the non-ideal interactions of the binary mixtures (NIBM) theory. The corresponding determined parameters were consistent. To have a more comprehensive analysis, the results were compared with those obtained with an analogous structure imidazolium GSAIL. [ABSTRACT FROM AUTHOR]