Gemini ionic liquid (IL) type surfactants, with high interfacial activity and environment friendly nature have revealed desired potentials for enhanced oil recovery (EOR). In this study, a long chain gemini imidazolium IL, namely [C12im-C4-imC12]Br2, was synthesized and its effect on different properties of the crude oil-water system was investigated. Significant changes in the system interfacial tension (IFT), micellization, emulsification and wettability were observed. A drastic reduction in IFT under the IL bulk concentrations of less than 0.2 mol dm 3 and achieving the ultra-low IFTs to about 8.2 � 10 3 mN m 1 (99.97% reduction) were appropriate. Increasing temperature (within 298.2–323.2 K) favored the function of the IL. Moreover, achieving stable emulsion of more than 52% after one week and oil displacement phenomenon at elevated IL concentrations were observed. Comparison of the results with two homolog shorter alkyl chain ILs, revealed the superior impact of the used IL. The Frumkin adsorption isotherm nicely reproduced the IFT data and the corresponding parameters as well as thermodynamic quantities were obtained.
