Percolation Behavior in W/O Emulsions Stabilized by Interfacially Active Fractions from Crude Oils in High External Electric Fields

Fördedal, Harald; Sjöblom, Johan

doi:10.1006/jcis.1996.0416

Cited by 13 publications

(5 citation statements)

References 10 publications

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“…An alternative method for measuring emulsion stability is the determination of the critical electric field (CEF) for emulsion breakdown. ,,,,− This method was used as a check of the water-resolved tests and a clarification of the trends observed in emulsion stability. CEF was measured with a sample cell consisting of two gold-coated copper electrodes separated by a Mylar spacer.…”

Section: Methodsmentioning

confidence: 99%

The Effects of Inorganic Solid Particles on Water and Crude Oil Emulsion Stability

Sullivan

Kilpatrick

2002

Ind. Eng. Chem. Res.

298

197

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Small inorganic particles strongly enhance water-crude oil emulsion stability when interactions with asphaltenes promote particle adsorption at the oil-water interface. A variety of particle types have been studied to investigate the controlling factors for particle-stabilization effectiveness. Emulsion stabilities were determined by the extent of water resolved after centrifugation and the electric field required for emulsion breakdown. All particles used were hydrophilic and stabilized oil-in-water emulsions if small enough to be interfacially active. When dried and exposed to asphaltene-containing oil phases, the particles stabilized water-in-oil emulsions. Decreased extents of preadsorbed water, decreased particle sizes, and increased particle concentrations enhanced water-in-oil emulsion stability. Investigations with model emulsions showed that an intermediate state of asphaltene aggregation, near the point of incipient precipitation, is required for particle modification and emulsion stabilization. Increased asphaltene-particle interactions increased emulsion stabilization effectiveness.

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Section: Methodsmentioning

confidence: 99%

The Effects of Inorganic Solid Particles on Water and Crude Oil Emulsion Stability

Sullivan

Kilpatrick

2002

Ind. Eng. Chem. Res.

298

197

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“…Asphaltenes attract particular attention for their ability to form elastic films that sheath water droplets and prevent coalescence. Thus, evaluating emulsion stability has been a consistent focus of many studies, including resistance to coalescence under heating, , centrifugation, , microwave-induced destabilization, , or an electric field. − Recent investigations have focused on measurable mechanical properties of the films by interfacial tensiometry − and rheological techniques. − A key criticism of these latter experiments is the length scale discrepancy between the experimental O/W interface and that of real-life emulsions (with particular implications on the diffusion, adsorption, and coalescence time scales during emulsion aging) and the difficulty in resolving that discrepancy. The use of micropipets to create micrometer scale droplets and test their interfacial properties is an example of an elegant solution to this issue. − However, despite the expanding knowledge base regarding asphaltenic film properties, the current literature is limited regarding the measurement of some critical aspects of these emulsion-stabilizing films: the film thickness and its composition.…”

Section: Introductionmentioning

confidence: 99%

Water-in-Model Oil Emulsions Studied by Small-Angle Neutron Scattering: Interfacial Film Thickness and Composition

Verruto

Kilpatrick

2008

Langmuir

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The ever-increasing worldwide demand for energy has led to the upgrading of heavy crude oil and asphaltene-rich feedstocks becoming viable refining options for the petroleum industry. Traditional problems associated with these feedstocks, particularly stable water-in-petroleum emulsions, are drawing increasing attention. Despite considerable research on the interfacial assembly of asphaltenes, resins, and naphthenic acids, much about the resulting interfacial films is not well understood. Here, we describe the use of small-angle neutron scattering (SANS) to elucidate interfacial film properties from model emulsion systems. Modeling the SANS data with both a polydisperse core/shell form factor as well as a thin sheet approximation, we have deduced the film thickness and the asphaltenic composition within the stabilizing interfacial films of water-in-model oil emulsions prepared in toluene, decalin, and 1-methylnaphthalene. Film thicknesses were found to be 100-110 A with little deviation among the three solvents. By contrast, asphaltene composition in the film varied significantly, with decalin leading to the most asphaltene-rich films (30% by volume of the film), while emulsions made in toluene and methylnaphthalene resulted in lower asphaltenic contents (12-15%). Through centrifugation and dilatational rheology, we found that trends of decreasing water resolution (i.e., increasing emulsion stability) and increasing long-time dilatational elasticity corresponded with increasing asphaltene composition in the film. In addition to the asphaltenic composition of the films, here we also deduce the film solvent and water content. Our analyses indicate that 1:1 (O/W) emulsions prepared with 3% (w/w) asphaltenes in toluene and 1 wt % NaCl aqueous solutions at pH 7 and pH 10 resulted in 80-90 A thick films, interfacial areas around 2600-3100 cm (2)/mL, and films that were roughly 25% (v/v) asphaltenic, 60-70% toluene, and 8-12% water. The increased asphaltene and water film composition at pH 10 versus pH 7, along with unique dynamic interfacial tension profiles, suggested that the protonation state of carboxylic moieties within asphaltenes impacts the final film properties. This was further supported when we characterized similar asphaltenic emulsions that also contained 9-anthracence carboxylic acid (ACA). Addition of this aromatic acid led to slightly thinner films (70-80 A) that were characteristically more aqueous (up to 20% by volume) and 5-6% (v/v) ACA. This unique in situ characterization (deduced entirely from SANS data from emulsion samples) of the entire film composition calls for further investigation regarding the role this film-based water plays in emulsion stability.

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“…NaCl in water (0.7 M) as a disperse phase [22][23][24]. The dielectric absorption was on a similar level, however at much higher contents of water droplets.…”

Section: Discussionmentioning

confidence: 89%

The microwave absorption of emulsions containing aqueous micro- and nanodroplets: A means to optimize microwave heating

Holtze

Sivaramakrishnan

Antonietti

et al. 2006

Journal of Colloid and Interface Science

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Percolation Behavior in W/O Emulsions Stabilized by Interfacially Active Fractions from Crude Oils in High External Electric Fields

Cited by 13 publications

References 10 publications

The Effects of Inorganic Solid Particles on Water and Crude Oil Emulsion Stability

The Effects of Inorganic Solid Particles on Water and Crude Oil Emulsion Stability

Water-in-Model Oil Emulsions Studied by Small-Angle Neutron Scattering: Interfacial Film Thickness and Composition

The microwave absorption of emulsions containing aqueous micro- and nanodroplets: A means to optimize microwave heating

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