Estudo das propriedades interfaciais de líquidos iônicos próticos

Abstract

The world’s energy matrix still focuses on the exploitation of fossil fuels. Thus, most producing companies are dedicated to maximizing the oil recovery factor, especially from mature fields. Production is declining and lack new technologies, such as advanced oil recovery (EOR), to maintain oil production in the reservoir. In this perspective, one of the most promising EOR techniques is the injection of surface-active agents or surfactants. The major benefit of using these compounds is to increase oil mobility in the reservoir by reducing the interfacial tension (IFT) between the oil/water system. However, there are several drawbacks to the use of surfactants, such as high cost, insoluble residues and low efficiency in harsh environments of high salinity and high temperature. Thus, studies point to a new class of surfactant that promises to circumvent the problems mentioned above: the ionic liquids (ILs). The ILs are organic salts, with melting point lower than 100 °C, which have high thermal stability and negligible vapor pressure. Moreover, the category of protic ionic liquids (PILs) is formed from the transfer of an acidic proton to a base, this class has gained increasing attention due to its low cost and simple synthesis. These are considered as an alternative to surfactants for their application in EOR, due to their high surface activity, since the intermolecular interactions between the surfactant molecules and the oil increase the mobility of the oil in the reservoir, reducing the IFT and, consequently, increasing the recovery factor. Therefore, this work proposes to study the surface activity of two PILs and a commercial surfactant through the pendant drop technique using as disperse phase an oil of 28 °API. The results on the surface activity were successful to minimize the surface forces in the presence of water and ions, both effects could be attributed to the adsorption tendency and compact arrangement at the interface. The ILs that showed the highest surface activity was the one with the largest alkyl chain [H2EA][C10OO], the minimum IFT value was 11.90mN/m and the surface tension value was 34.44mN/m at 1,000ppm in formation brine. LI [H2EA][C8OO] showed better performance in brine than water solution. This phenomenon is related to the electrostatic stabilization of the cations and anions of the ionic liquid with the salt, which improves adsorption and provides a more suitable positioning of the interface molecules. Therefore, the protic ionic liquid has potential to be applied as a chemical EOR method because there is success in minimizing the effect of surface forces.