Synergistic performance of a Gemini nano ionic liquid and sodium dodecyl sulfate surfactants at the crude oil–water interface

Abstract

Gemini surface active ionic liquids (GSAILs) are known as effective and environmentally friendly materials. Conventional anionic surfactants like sodium dodecyl sulfate (SDS), on the other hand, can establish desired properties in solutions. This study reports investigation on the influence of the mixtures of an imidazolium cationic GSAIL, [C4im-C6-C4im][Br]2, and the SDS anionic surfactant on the interfacial tension (IFT), emulsification, and wettability alteration of the crude oil–water system. Results demonstrate amazing synergistic effects, resulting in 97.1 % more IFT reductions compared to what could be achieved with the linear contribution of surfactants. Under the GSAIL mole fraction of 0.4 and the mixture concentration of 0.25 molˑdm−3 in aqueous phase, a low IFT of 0.18 mNˑm−1 was attained. This is attributed to the attractive interaction between the involved surfactants. Synergisms of 52.0 and 59.8 % were also achieved in emulsification and wettability alteration with the mixture of surfactants under the optimum GSAIL mole fraction of 0.4. The obtained data for the individual and the mixture of surfactants were analyzed based on, respectively, Frumkin adsorption isotherm and the “non-ideal interactions in binary mixtures” theory. Corresponding consistent parameters were determined and discussed.