Analysis of the interfacial tension of cationic imidazolium-based ionic liquid, twin-branched tailed anionic surfactant, and a non-ionic emulsifier in the presence of SiO2 nanoparticle and amphiphilic oleic components using response surface method

Abstract

Although various surface active agents have been proposed, there is still no straightforward and clear understanding of the effect of cationic imidazolium-based ionic liquid (IL), twin-branched tailed anionic surfactant, and a non-ionic emulsifier in the presence of SiO2 nanoparticle and amphiphilic oleic components on the interfacial tension (IFT) reduction. So, in this work, the performance of cationic imidazolium-based IL ([C12mim][Cl], anionic surfactant (AOT)), and non-ionic surfactant (Tween 80) on the IFT value were studied through the design of experiment approach and the response surface method. Experiments were designed using a face-centered composite design (FCCD) with the independent variables of surfactant concentration (175–525 ppm) and nanoparticle concentration (25–75 ppm) as numerical ones, and surfactant type and synthetic oil (8 wt% of asphaltene and resin fractions dissolved in heptol (mixture of n-heptane: toluene with the volume ratio of 30:70)) with various volume ratios of asphaltene to resin (1:0, 2:1, 1:1, and 1:2) as categorical ones. According to the analysis of variance (ANOVA) and 156 measured IFT experimental data points, the effects of each factor were evaluated. As a result, the suggested quadratic model with R2 (0.9986) and adjusted R2 (0.9984) values indicated that the fitted model can accurately predict the response variable (IFT) values. The best performance (lower IFT and critical micelle concentration) was obtained for [C12mim][Cl] without being affected by the amphiphilic nature of asphaltene and resin fractions and the concentration of SiO2 nanoparticles. The appropriate surface activity of IL was attributed to the effective polar head group of imidazolium and the presence of nitrogen in the aromatic ring.