Cristin-resultat-ID: 1248878
Sist endret: 10. august 2015, 15:41
NVI-rapporteringsår: 2015
Resultat
Vitenskapelig artikkel
2015

Interfacial properties of asphaltenes at toluene-water interfaces

Bidragsytere:
  • Sharli Zarkar
  • Vincent Pauchard
  • Umer Farooq
  • Alexander Couzis og
  • Sanjoy Banerjee

Tidsskrift

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

Om resultatet

Vitenskapelig artikkel
Publiseringsår: 2015
Volum: 31
Hefte: 17
Sider: 4878 - 4886

Importkilder

Scopus-ID: 2-s2.0-84928963889

Beskrivelse Beskrivelse

Tittel

Interfacial properties of asphaltenes at toluene-water interfaces

Sammendrag

Asphaltenes are “n-alkane insoluble” species in crude oil that stabilize water-in-oil emulsions. To understand asphaltene adsorption mechanisms at oil–water interfaces and coalescence blockage, we first studied the behavior in aliphatic oil–water systems in which asphaltenes are almost insoluble. They adsorbed as monomers, giving a unique master curve relating interfacial tension (IFT) to interfacial coverage through a Langmuir equation of state (EoS). The long-time surface coverage was independent of asphaltene bulk concentration and asymptotically approached the 2-D packing limit for polydisperse disks. On coalescence, the surface coverage exceeded the 2-D limit and the asphaltene film appeared to become solidlike, apparently undergoing a transition to a soft glassy material and blocking further coalescence. However, real systems consist of mixtures of aliphatic and aromatic components in which asphaltenes may be quite soluble. To understand solubility effects, we focus here on how the increased bulk solubility of asphaltenes affects their interfacial properties in comparison to aliphatic oil–water systems. Unlike the “almost irreversible” adsorption of asphaltenes where the asymptotic interfacial coverage was independent of the bulk concentration, an equilibrium surface pressure, dependent on bulk concentration, was obtained for toluene–water systems because of adsorption being balanced by desorption. The equilibrium surface coverage could be obtained from the short- and long-term Ward–Tordai approximations. The behavior of the equilibrium surface pressure with the equilibrium surface coverage was then derived. These data for various asphaltene concentrations were used to determine the EoS, which for toluene–water could also be fitted by the Langmuir EoS with Γ∞ = 3.3 molecule/nm2, the same value as that found for these asphaltenes in aliphatic media. Asphaltene solubility in the bulk phase only appears to affect the adsorption isotherm but not the EoS. Further support for these observations is provided by dilatational rheology experiments for the EoS and contraction experiments in which desorption to the equilibrium surface pressure was observed.

Bidragsytere

Sharli Zarkar

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

Vincent Pauchard

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

Umer Farooq

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

Alexander Couzis

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

Sanjoy Banerjee

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