Cristin-resultat-ID: 1038259
Sist endret: 14. august 2013, 13:31
NVI-rapporteringsår: 2013
Resultat
Vitenskapelig artikkel
2013

Interfacial Rheology of Asphaltenes at Oil-Water Interfaces and Interpretation of the Equation of State

Bidragsytere:
  • Jayant P. Rane
  • Vincent Pauchard
  • Alexander Couzis og
  • Sanjoy Banerjee

Tidsskrift

Langmuir
ISSN 0743-7463
e-ISSN 1520-5827
NVI-nivå 1

Om resultatet

Vitenskapelig artikkel
Publiseringsår: 2013
Volum: 29
Hefte: 15
Sider: 4750 - 4759

Importkilder

Isi-ID: 000317813300013
Scopus-ID: 2-s2.0-84876254656

Beskrivelse Beskrivelse

Tittel

Interfacial Rheology of Asphaltenes at Oil-Water Interfaces and Interpretation of the Equation of State

Sammendrag

In an earlier study,(1) oil–water interfacial tension was measured by the pendant drop technique for a range of oil-phase asphaltene concentrations and viscosities. The interfacial tension was found to be related to the relative surface coverage during droplet expansion. The relationship was independent of aging time and bulk asphaltenes concentration, suggesting that cross-linking did not occur at the interface and that only asphaltene monomers were adsorbed. The present study extends this work to measurements of interfacial rheology with the same fluids. Dilatation moduli have been measured using the pulsating droplet technique at different frequencies, different concentrations (below and above CNAC), and different aging times. Care was taken to apply the technique in conditions where viscous and inertial effects are small. The elastic modulus increases with frequency and then plateaus to an asymptotic value. The asymptotic or instantaneous elasticity has been plotted against the interfacial tension, indicating the existence of a unique relationship, between them, independent of adsorption conditions. The relationship between interfacial tension and surface coverage is analyzed with a Langmuir equation of state. The equation of state also enabled the prediction of the observed relationship between the instantaneous elasticity and interfacial tension. The fit by a simple Langmuir equation of state (EOS) suggests minimal effects of aging and of nanoaggregates or gel formation at the interface. Only one parameter is involved in the fit, which is the surface excess coverage Γ∞ = 3.2 molecules/nm2 (31.25 Å2/molecule). This value appears to agree with flat-on adsorption(2) of monomeric asphaltene structures consisting of aromatic cores composed of an average of six fused rings and supports the hypothesis that nanoaggregates do not adsorb on the interface. The observed interfacial effects of the adsorbed asphaltenes, correlated by the Langmuir EOS, are consistent with the asphaltene aggregation behavior in the bulk fluid expected from the Yen–Mullins model.(3, 4)

Bidragsytere

Jayant P. Rane

  • Tilknyttet:
    Forfatter
    ved City University of New York-City College
  • Tilknyttet:
    Forfatter
    ved Diverse norske bedrifter og organisasjoner

Vincent Pauchard

  • Tilknyttet:
    Forfatter
    ved Diverse norske bedrifter og organisasjoner
  • Tilknyttet:
    Forfatter
    ved Prosessteknologi ved SINTEF AS

Alexander Couzis

  • Tilknyttet:
    Forfatter
    ved City University of New York-City College

Sanjoy Banerjee

  • Tilknyttet:
    Forfatter
    ved Diverse norske bedrifter og organisasjoner
  • Tilknyttet:
    Forfatter
    ved City University of New York-City College
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