Rheology of Asphaltene−Toluene/Water Interfaces

Sztukowski, Danuta M.; Yarranton, Harvey W.

doi:10.1021/la051921w

Cited by 129 publications

(172 citation statements)

References 48 publications

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“…The presence (formation) of solid-like (elastic dominant) asphaltene films at the oil-water interface has been shown to significantly hinder the coalescence of two contacting water droplets, as such that when two droplets interact and undergo significant compression, they continue to remain stable without coalescence. 48,51 The correlation between interfacial dilatational elasticity and overall emulsion stability has been qualitatively proven by several researchers, 49,50,[52][53][54][55][56] although there is clear disagreement at high asphaltene concentrations where emulsion stability increases and E' decreases. The discrepancy between the interfacial rheology and emulsion stability is believed to be associated with a change in the interfacial layer structure, transitioning from a compact and rigid monolayer, to a collapsed interfacial layer dominated by threedimensional structures.…”

Section: Asphaltene Adsorptionmentioning

confidence: 96%

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

et al. 2017

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SARA fractionation separates the oil into fractions of saturates (S), aromatics (A), resins (R), and asphaltenes (A) based on the differences in their polarizability and polarity.Defined as a solubility class, asphaltenes are normally considered as a menace in the petroleum industry mainly due to their problematic precipitation and adsorption at oil water and oil-solid interfaces. As a broad range of molecules fall within the group of asphaltenes with distinct sizes and structures, considering the asphaltenes as a whole was noted to limit the deep understanding of governing mechanisms in asphaltene-induced problems.Extended-SARA (E-SARA) is being proposed as a concept of asphaltene fractionation according to their interfacial activities and adsorption characteristics, providing critical information to correlate specific functional groups with certain characteristics of asphaltene aggregation, precipitation and adsorption. Such knowledge obtained is essential to addressing asphaltene-related problems by targeting specific subfractions of asphaltenes for selective removal.2

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Section: Asphaltene Adsorptionmentioning

confidence: 96%

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

et al. 2017

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“…In addition, it was reported that the diffusion coefficient of Athabasca asphaltenes in toluene was in the range of 2−7.5 × 10 −11 m 2 /s. 53 Although the diffusion time of asphaltene molecules from the oil phase to the oil/water interface is short in practice, it would be a very long time in the simulation. To save calculation time, the asphaltene molecules were randomly placed in a shell with a specific radius from the water surface.…”

Section: Energy and Fuelsmentioning

confidence: 99%

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

2015

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It is well known that asphaltene molecules play a significant role in stabilizing emulsions of water in crude oil or diluted bitumen solutions. Molecular dynamics simulations were employed to investigate the aggregation and orientation behaviors of asphaltene molecules in a vacuum and at various water surfaces. Two different continental model asphaltene molecules were employed in this work. It was found that the initially disordered asphaltenes quickly self-assembled into ordered nanoaggregates consisting of several molecules, in which the aromatic rings in asphaltenes were reoriented to form a face-to-face stacked structure. More importantly, statistical analysis indicates that most of the stacked polycyclic aromatic planes of asphaltene nanoaggregates tend to be perpendicular to the water surface. If the asphaltene molecules are considered as "stakes", then the asphaltene nanoaggregate can be regarded as a "fence". All the fence-like nanoaggregates were twined and knitted together, which pinned them perpendicularly on the water surface to form a steady protective film wrapping the water droplets. The mechanism of stabilization of the water/oil emulsions is thereby well understood. Demulsification processes using a chemical demulsifier were also studied. It was observed that the asphaltene protective film was destroyed by a demulsifier of ethyl cellulose molecules, leading to exposure of the water droplet. The results obtained in this work will be of significance in guiding the development of demulsification technology.

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“…The literature regarding interfacial dilatational rheological studies of asphaltene films at the liquid-liquid interface is extensive 17,18,19,20,21,22 . It is imperative to emphasize that in such experiments, depending on the dominating phenomena, the nature of the measured quantities will vary.…”

Section: Introductionmentioning

confidence: 99%

Sorption and Interfacial Rheology Study of Model Asphaltene Compounds

et al. 2016

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The sorption and rheological properties of an acidic polyaromatic compound (C5PeC11), which can be used to further our understanding in the behavior of asphaltenes, are determined experimentally. The results show that C5PeC11 exhibits the type of pH-dependent surface activity and interfacial shear rheology observed in C6-asphaltenes with a decrease in the interfacial tension concomitant to the elastic modulus when the pH increases. Surface pressure-area (Π-A) isotherms show evidence of aggregation behavior and π-π stacking at both the air/water and oil/water interfaces. Similarly, interactions between adsorbed C5PeC11 compounds are evidenced through desorption experiments at the oil/water interface. Contrary to indigenous asphaltenes, adsorption is reversible, but desorption is slower than for noninteracting species. The reversibility enables us to create layers reproducibly, whereas the presence of interactions between the compounds enables us to mimic the key aspects of interfacial activity in asphaltenes. Shear and dilatational rheology show that C5PeC11 forms a predominantly elastic film both at the liquid/air and the liquid/liquid interface. Furthermore, a soft glassy rheology model (SGR) fits the data obtained at the liquid/liquid interface. Yet, it is shown that the effective noise temperature determined from the SGR model for C5PeC11 is higher than for indigenous asphaltenes measured under similar conditions. Finally, from a colloidal and rheological standpoint, the results highlight the importance of adequately addressing the distinction between the material functions and true elasticity extracted from a shear measurement and the apparent elasticity measured in dilatational-pendant drop set-ups.

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Rheology of Asphaltene−Toluene/Water Interfaces

Cited by 129 publications

References 48 publications

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

Fractionation of Asphaltenes in Understanding Their Role in Petroleum Emulsion Stability and Fouling

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

Sorption and Interfacial Rheology Study of Model Asphaltene Compounds

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