Tese: Interfacial rheology and properties of island-type asphaltenes
Aluno(a) : Isabela Fernandes SoaresOrientador(a): Mônica Naccache
Área de Concentração: Termociências
Data: 25/01/2022
Link para tese/dissertação: https://doi.org/10.17771/PUCRio.acad.57587
Resumo: Adsorption of asphaltene molecules at the oil-water interface induces the formation of a complex microstructure, which stabilizes emulsions and impairs the efficiency of crude oil refining. In this work, we design a set of new shear rheology protocols to assess the effect of polar and non-polar solvents on indigenous Brazilian (BR) asphaltene adsorption. Moreover, the asphaltene morphology upon addition of solvents with distinct aromaticities is investigated by SEM microscopy. Our findings indicate that asphaltenes are a polycondensate aromatic island-type structure that forms reversible films when polar solvents are placed on top of the adsorbed film. The interfacial study also reveals that non-polar solvents induce precipitation/adsorption of asphaltenes at the oil-water interface. The asphaltene aggregates, upon the presence of weakly polar solvents, can consolidate into a more close-packed pattern, suggesting that network growth and asphaltene self-arrangement are directly related to the aromatic content. We explore the differences in asphaltene structuring and how it affects the extent of spontaneous emulsification. We find that the rate of emulsification is directly related to the chemical configuration of asphaltenes. Finally, we study the addition of stearic acid (SA) to asphaltene solutions in deionized water (DW) and synthetic water (SW) to better understand how surface and rheological properties are affected by competitive adsorption. We find that single SA are more prone to form liquid-like rather than solid-like films at the air-water interface. Furthermore, we show that the interfacial activity of our asphaltenes is enhanced in the presence of electrolytes and is dependent of the solvent aromaticity.