Estudo do processo de micelização de líquido iônicos próticos para aplicação em recuperação avançada de petróleo

Abstract

The micelle formation has been studied in recent years due to the various applications of micellar systems in areas such as chemistry, petrochemistry, pharmaceuticals, and the environment. Micelles are formed by amphiphilic substances, denominated as surfactants. However, a notable evolution in this field is the increasing use of ionic liquids (ILs) as an alternative to commercial surfactants in enhanced oil recovery. Ionic liquids (ILs) are organic salts that have surfactant properties, which gives them several applications in the form of micelle, making them a promising option in enhanced oil recovery processes. Due to these characteristics, many studies have been dedicated to evaluating the micelle formation process using ionic liquids. However, most published works explore aprotic ionic liquids, and more published data on protic ionic liquids needs to be published. Ionic liquids can decrease interfacial and surface tension, showing potential for oil recovery. Therefore, this work proposes to study six ionic liquids based on hexanoic acid as anion and cations with different structures. To synthesize these liquids, substances with nitrogenous and hydrogenated groups were used as a base (cation) to evaluate their influence on the formation of micelles. Through a statistical design of experiments of the Rotational Central Composite Design (RCCD) type, it was possible to determine the influence of the concentration of ionic liquid and NaCl on the interfacial tension of a solution of ionic liquid and oil since this parameter is directly related to the tendency of micellization. The results showed that as their concentration increases, ionic liquids decrease the interfacial tension to a point where it increases again. This effect is mitigated by adding salt, which causes the interfacial tension to decrease even at higher ionic liquid concentrations. A thermodynamic approach was used to describe and predict the conditions for micelle formation from solutions of protic ILs studied in this work by minimizing the Gibbs free energy. The critical micellar concentration was obtained from this approach, which was compared with the experimental values for model validation. The proposed thermodynamic modeling agreed with the experimental data for the first critical micellar concentration value, describing a spherical geometry for the micelles.