Nanoscale Characterization of Thin Films at Oil/Water Interfaces and Implications to Emulsion Stability

Goual, Lamia; Zhang, Bingjun; Rahham, Youssra

doi:10.1021/acs.energyfuels.0c03466

Cited by 21 publications

(40 citation statements)

References 56 publications

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“…The kinetical stability of water-in-oil emulsions is mainly attributed to the formation of an interfacial film or elastic layer at the oil−water interface by indigenous surface-active agents in the crude oil 1 including asphaltenes. 1,[7][8][9][10][11][12][13]15,16 Aspects of increased emulsion stability due to asphaltenes have been investigated 1,8,12,13,15,16 (also see ref 18 and references therein).…”

Section: Introductionmentioning

confidence: 99%

“…Many aspects of emulsion stability due to asphaltenes have been studied. 1,8,12,13,15,16,18 Stable emulsions are formed in oils with high asphaltene fraction, because of the affinity of the asphaltenes to the interface. 1,8,12,13,26 Asphaltenes are defined by a solubility classification, not by chemical structure.…”

Section: Introductionmentioning

confidence: 99%

“…45,48 The interfacial material responsible of the stability of water-in-oil emulsions has been isolated using solvent washing by centrifugation, and it was found that this interfacial material is a subfraction of asphaltenes and constitutes <2 wt % of the total asphaltene present in oil. 4,15,16 This subfraction of asphaltenes exhibit interface activity due to an abundance of acidic oxygen and sulfur. 15,16 The isolated interfacial material is similar to naphthenic acids with a small polycyclic aromatic hydrocarbon region with a fatty acid chain, 15,24,25,47 which have a tendency to orient perpendicular to the oil−water interface and also to stack.…”

Section: Introductionmentioning

confidence: 99%

“…4,15,16 This subfraction of asphaltenes exhibit interface activity due to an abundance of acidic oxygen and sulfur. 15,16 The isolated interfacial material is similar to naphthenic acids with a small polycyclic aromatic hydrocarbon region with a fatty acid chain, 15,24,25,47 which have a tendency to orient perpendicular to the oil−water interface and also to stack. 15 Computational simulations have been used to study asphaltenes at the oil−water interface.…”

Section: Introductionmentioning

confidence: 99%

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Mesoscale Dissipative Particle Dynamics to Investigate Oil Asphaltenes and Sodium Naphthenates at the Oil−Water Interface

Ruiz‐Morales

Alvarez-Ramírez

2021

Energy Fuels

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The effect of the structure of oil asphaltenes and sodium naphthenates at the oil–water interface on the reduction of the oil–water interfacial tension and the formation of stable emulsions is investigated by dissipative particle dynamics (DPD). The coarse-grained model molecules at the mesoscale level are adopted instead of using atomistic models. DPD can process a much larger spatial and temporal scale system than molecular dynamics (MD) can. Two types of island asphaltene model structures are used in the calculations: one with O atoms and the other one without O atoms. A small sodium naphthenate (benzoic acid sodium salt) is included in the simulations. The interfacial tension (IFT) is evaluated at different concentrations of sodium naphthenate while maintaining the asphaltene concentration fixed to conclude on the stability of the emulsions formed. The IFT results obtained for both asphaltene models are compared to reach conclusions regarding the relationships between asphaltene structure, surface activity and coverage, orientation at the oil–water interface, and stability of the emulsion formed by the asphaltenes and sodium naphthenates. Initially, when there is no sodium napthenates in the systems but only asphaltenes, the IFT decreases from 45 mN/m to 40 mN/m, because of the presence of asphaltene molecules at the oil−water interface. With the addition of sodium naphthenates to the systems, it is found that the asphaltene with no O atoms in the structure is less oil−water interface active and it is required to add a concentration of 0.363 M of sodium naphthenate to lower the IFT from 40 mN/m to 35 mN/m. The reduction of the IFT is mainly due to the formation of a uniform film of sodium naphthenates that covers the oil−water interface and displaces most of the asphaltenes with no heteroatoms to the oil region. This would explain why only <2 wt % of the total content of asphaltenes in some oils is found in the material extracted from the oil−water interface. For the asphaltene with O atoms in the structure, only a concentration of 0.033 M of sodium naphthenate is required to lower the IFT from 40 mN/m to 35 mN/m, i.e., a 10 times less sodium naphthenate concentration is required to lower the interfacial tension. The asphaltene with O atoms in the structure is more oil−water interface active and forms stable emulsions with sodium naphthenates by creating a uniform film at the oil−water interface with the sodium naphthenates. Once the film is formed, the asphaltenes with oxygen in the structure do not desorb from the interface, in agreement with experimental observations. A detailed knowledge of the chemical structure of interfacial active asphaltenes and other interfacial materials such as naphthenates can help in the design of a new generation of demulsifiers to resolve water-in-oil emulsions problems in the oil industry.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mesoscale Dissipative Particle Dynamics to Investigate Oil Asphaltenes and Sodium Naphthenates at the Oil−Water Interface

Ruiz‐Morales

Alvarez-Ramírez

2021

Energy Fuels

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“…The promoting effect of polar molecules such as asphaltene and resin on the formation and stabilization of oil-water emulsion has been confirmed in many experiments. Goual et al used a transmission electron microscope to characterize the oil-water interface film at nanoscale and found that the thin film consisted of vertically accumulated wormlike clusters of asphaltene, and one side of the film was rough and hydrophobic, while the other side was smooth and hydrophilic [12]. Rocha et al extracted different types of asphaltenes to prepare emulsions and tested their stability.…”

Section: Introductionmentioning

confidence: 99%

Effect of Polar Molecule Aggregation on the Stability of Crude Oil/Water Interface: A Molecular Simulation Study

Zhao¹,

Xia²,

Wang³

et al. 2021

Lithosphere

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To ensure the efficient operation of crude oil dehydration and sewage treatment technology in oilfield surface production system, the effect mechanism of polar components represented by asphaltene and resin on the formation and stability of oil-water emulsion needs to be revealed at nanoscale. In this paper, the molecular dynamics simulation method was used to construct the crude oil/polar component/water system models with different molar ratios of asphaltene to resin by adjusting the number of asphaltene and resin molecules, so as to reveal the molecular arrangement and aggregation process and film forming characteristics of asphaltene, resin, and their mixture at the oil-water interface. The simulated results showed that the aggregation process of asphaltene molecules under the influence of hydrogen bonds can be divided into three stages. The addition of resin molecules enhanced the connection between molecules of all polar components at the interface. The π−π stacking and T-shaped stacking structures were found in all aggregations, and the higher the molar ratio of asphaltene molecules, the higher the proportion of π−π stacking structure. With the increase of the molar ratio of asphaltene to resin increases from 0 : 1 to 1 : 0, the interfacial film thickness and interface formation energy increase from 2.366 nm and -143.89 kJ/mol to 3.796 nm and -304.09 kJ/mol, respectively, which indicated that asphaltene molecules play a more significant role in promoting the formation of interfacial film and maintaining its structural stability than resin molecules. The investigations in this study provide theoretical support for demulsification of the crude oil emulsion.

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Characteristics of Asphaltene Fractions Responsible for the Formation of Stable Water‑Oil Emulsions

Ganeeva,

Barskaya,

Okhotnikova

et al. 2024

Chem Technol Fuels Oils

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Nanoscale Characterization of Thin Films at Oil/Water Interfaces and Implications to Emulsion Stability

Cited by 21 publications

References 56 publications

Mesoscale Dissipative Particle Dynamics to Investigate Oil Asphaltenes and Sodium Naphthenates at the Oil−Water Interface

Mesoscale Dissipative Particle Dynamics to Investigate Oil Asphaltenes and Sodium Naphthenates at the Oil−Water Interface

Effect of Polar Molecule Aggregation on the Stability of Crude Oil/Water Interface: A Molecular Simulation Study

Characteristics of Asphaltene Fractions Responsible for the Formation of Stable Water‑Oil Emulsions

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