Estudo e desenvolvimento de emulsões-modelo multifuncionais que simulam o petróleo e algumas de suas características e propriedades

Abstract

This study investigated the formulation of stable emulsions using model fluids with physicochemical properties and chemical profiles similar to a reference crude oil. After evaluating the physicochemical properties and mid-infrared absorption spectra of four model fluids, one fluid with potential for producing stable emulsions was selected. Water-in oil emulsions were prepared with this model fluid, containing 10% v/v of a saline solution at 35 g/L, and evaluated based on several parameters such as surfactant concentration, stirring speed, flow type, kinetic stability time, and droplet size distribution. It was observed that the medium lubricating oil (ρ = 0.8885 g/cm3) exhibited a compositional profile compatible with the reference oil and was capable of forming emulsions stable for over 48 hours. Model emulsions were prepared using different oil phases and surfactants (Span 60, Span 80, Triton X-100, and Triton X-114), with 10% and 30% v/v of aqueous phase. The kinetic stability of the emulsions was evaluated in terms of aqueous phase separation, droplet size distribution, dynamic viscosity, and interfacial tension. In addition, an analysis of the homogenization process was conducted to identify the emulsification regime (inertial or viscous) by calculating the smallest vortices formed. The study also included an investigation of the maximum superficial flow velocity to provide a better understanding of the produced emulsions. Seven formulations were found suitable for application in laboratory-scale flow loops, presenting a maximum superficial velocity below 3.9 m/s. Span 80 surfactant was particularly effective in stabilizing emulsions, keeping them stable for more than 72 hours, with droplet sizes ranging from 0.2 µm to 100.0 µm. As a novel contribution, this study evaluated the use of Triton X-100 and Triton X-114 surfactants in the formulation of W/O emulsions under different homogenization conditions, representing the first report of these compounds used in model fluid systems similar to crude oil. It was observed that, in addition to providing good stability, these surfactants significantly influenced the emulsification regime and hydrodynamic behavior of the emulsions. In the case of Span 80, although widely known, it was found that increasing its concentration simultaneously improved stability, reduced droplet size, and decreased average flow velocity under viscous turbulent emulsification conditions in axial f low. These findings contribute to advancing the understanding of the factors that influence the stability and dynamics of emulsions applicable to industrial processes and experimental f low circuits