Understanding Molecular Interactions of Asphaltenes in Organic Solvents Using a Surface Force Apparatus

Natarajan, Anand; Xie, Jing-Gang; Wang, Shengqun; Masliyah, Jacob H.; Zeng, Hongbo; Xu, Zhenghe

doi:10.1021/jp2039674

Cited by 95 publications

(137 citation statements)

References 63 publications

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“…Of these, it is the formation of W/O emulsions that can dramatically change the character of a mass of spilled crude oil from a low-viscosity liquid to sticky, cohesive mixtures having a relatively high viscosity (Fingas 2011a). The ability of O/W and W/O emulsions to remain stable over time has been attributed to the presence of amphiphilic asphaltenes, a naturally occurring component of crude oils (Buckley 1998;Buckley and Wang 2002;Natarajan et al 2011; A further challenge with respect to complete handling of spilled oils involves the fact that finite concentrations of oil can be present in the aqueous phase in solubilized, phase-separated, or emulsified forms (Bobra 1992;NRC 2002;Ibrahim et al 2009). Oil can be emulsified as droplets in water if there are sufficient surface-active species present along with agitation (Johansen et al 2003).…”

Section: Definitionsmentioning

confidence: 99%

“…Asphaltenes are a class of compounds that contain paraffin and aromatic structures, as well as heteroatoms such as nitrogen, sulfur, or oxygen (Simanzhenkov and Idem 2003;Varadaraj and Brons 2007a-d;Silva et al 2011). In practical terms, asphaltenes can be defined as the part of the crude oil that is soluble in toluene but insoluble in simple alkanes such as n-pentane (Natarajan et al 2011). Figure 2 shows some typical structures of each class of compound in crude petroleum oil.…”

Section: Properties Of the Oilmentioning

confidence: 99%

“…Due to the ubiquitous presence of wave action, but also dependent on the presence and details of surface-active components in the oil (Natarajan et al 2011), it is common for droplets of water to become incorporated into the bulk oil phase, forming W/O emulsions (Fingas 2011a), which are typically highly viscous. Wave action also can promote formation of O/W emulsion droplets, which then tend to be dispersed into the water column.…”

Section: State Of Emulsificationmentioning

confidence: 99%

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Cellulosic Substrates for Removal of Pollutants from Aqueous Systems: A Review. 3. Spilled Oil and Emulsified Organic Liquids

Hubbe

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Fingas³

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Section: Definitionsmentioning

confidence: 99%

Section: Properties Of the Oilmentioning

confidence: 99%

Section: State Of Emulsificationmentioning

confidence: 99%

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Cellulosic Substrates for Removal of Pollutants from Aqueous Systems: A Review. 3. Spilled Oil and Emulsified Organic Liquids

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“…Mica, because it can be cleaved to provide uniform and molecularly smooth surfaces has been used to study asphaltene adsorption. 14,30 Recently, Adams published a comprehensive review on the chemical and physical nature of asphaltenes and corresponding characteristics of asphaltene adsorption. 37 The above research provided valuable information on stabilization mechanisms and adsorption kinetics of asphaltenes.…”

Section: Introductionmentioning

confidence: 99%

Understanding Mechanisms of Asphaltene Adsorption from Organic Solvent on Mica

et al. 2014

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The adsorption process of asphaltene onto molecularly smooth mica surfaces from toluene solutions of various concentrations (0.01 -1 wt%) was studied using a Surface Forces Apparatus (SFA). Adsorption of asphaltenes onto mica was found to be highly dependent on adsorption time and concentration of the solution. The adsorption of asphaltenes led to an attractive bridging force between the mica surfaces. The adsorption process was identified to be controlled by diffusion of asphaltenes from the bulk solution to the mica surface with a diffusion coefficient on the order of 10 -10 m 2 /s at room temperature, depending on asphaltene bulk concentration. This diffusion coefficient corresponds to a hydrodynamic molecular radius of approximately 0.5 nm, indicating that asphaltene diffuses to mica surfaces as individual molecules at very low concentration (e.g. 0.01 wt%). Atomic force microscopy (AFM) images of the adsorbed asphaltenes on mica support the results of the SFA force measurements. The results from the SFA force measurements provide an insight on the molecular interactions (e.g. steric interaction, bridging attraction as a function of distance) of asphaltenes in organic media and hence their roles in crude oil and bitumen production.

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“…Increased layer compressibility contributes to higher adhesion forces due to increased interpenetration and contact area between asphaltene layers. 48,51 The force measurements presented in the current study were conducted at a fixed slow cantilever …”

Section: Force Interactions Between Rigid and Deformable Interfacesmentioning

confidence: 99%

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

et al. 2017

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Atomic force microscopy (AFM) is frequently used to elucidate complex interactions in emulsion systems. However, comparing results obtained with "model" planar surfaces to curved emulsion interfaces often proves unreliable, since droplet curvature can affect adsorption and arrangement of surface-active species, while droplet deformation affects the net interaction force.In the current study, AFM was utilized to study the interactions between a colloidal probe and water droplet. Force magnitude and water droplet deformation were measured in asphaltene and bitumen solutions of different concentrations at various droplet aging times. Interfacial stiffening and an increase in particle-droplet adhesion force were observed upon droplet aging in bitumen solution. As reported in our previous study (Kuznicki, N. P.; Harbottle, D.; Masliyah, J.; Xu, Z. Dynamic Interactions between a Silica Sphere and Deformable Interfaces in Organic SolventsStudied by Atomic Force Microscopy. Langmuir 2016, 32 (38), 9797−9806), a viscoelasticity parameter should be included in the high force Stokes-Reynolds-Young-Laplace (SRYL) equations to account for the interfacial stiffening and non-Laplacian response of the water droplet at longer aging times. However, following the addition of a biodegradable demulsifier, ethyl cellulose (EC), an immediate reduction in both the particle-droplet adhesion force and the rigidity of the water droplet occurred. Following EC addition, the interface reverted back to a 2 Laplacian response and droplet deformation was once again accurately predicted by the classical SRYL model. These changes in both droplet deformation and particle-droplet adhesion, tracked by AFM, imply a rapid asphaltene/bitumen film displacement by EC molecules. The colloidal probe technique provides a convenient way to quantify forces at deformable oil/water interfaces and characterize the in-situ effectiveness of competing surface active species.

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Understanding Molecular Interactions of Asphaltenes in Organic Solvents Using a Surface Force Apparatus

Cited by 95 publications

References 63 publications

Cellulosic Substrates for Removal of Pollutants from Aqueous Systems: A Review. 3. Spilled Oil and Emulsified Organic Liquids

Cellulosic Substrates for Removal of Pollutants from Aqueous Systems: A Review. 3. Spilled Oil and Emulsified Organic Liquids

Understanding Mechanisms of Asphaltene Adsorption from Organic Solvent on Mica

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

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