Qualifying Interfacial Properties of Crude Oil−water System with the Synergistic Action of a Nano Gemini Ionic Liquid and Conventional Surfactants

Surface-active ionic liquids (SAILs) have gained much attention due to their green, stable, and efficient properties. The high costs associated with SAILs have raised concerns in their applications; however, blending with conventional surfactants like sodium dodecyl benzene sulfonate (SDBS) can bring about desired outcomes. Gemini surface-active ionic liquids (GSAILs) have been recognized as more efficient surfactants. Accordingly, this study investigates the influence of a mixture of an imidazolium-based GSAIL, [C4im-C6-imC4][Br2], and SDBS on different aspects of crude oil-water interfacial properties. The findings show remarkable synergy in interfacial tension (IFT) reduction up to 98.8% together with incredibly low IFT value of 0.05 mN m-1. This was with an optimal GSAIL mole fraction of 0.2 in the mixture. Further, the surfactant mixture gives synergies of 52.6% in emulsification and 51.8% in wettability of a quartz surface. These amazing results can be explained by the dominant interactions between the oppositely charged components. In theoretical study, the adsorption of individual surfactants and their mixtures was analyzed based on the Frumkin isotherm and the Rosen model, respectively, further supporting the findings.