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Study on the mechanism of asphaltenes reducing oil-water interfacial tension

As high polar components of crude oil, asphaltenes play a significant role in reducing oil-water interfacial tension (IFT). In this paper, the effects of asphaltenes on reducing IFT in presence of surfactant were compared, and the mechanism of asphaltenes reducing the IFT was studied by the dynamic interfacial tension (DIFT) equation. Whether asphaltenes were added into the oil or 2, 5-dimethyl-4-(4-dodecyl) benzene sodium sulfonate (p-S14-4) added into the water phase, either of all results in the IFT reducing and the IFT is related to the coverage and the mass of asphaltenes adsorption at the interface. In presence of asphaltenes, the adsorption of the active substances to the interface is not entirely dependent on diffusion, and the process can be divided into three regions. Region I: the IFT rapidly reducing, this process is controlled by diffusion of surfactant; Region II: the IFT reducing slowly, resulting from the lower diffusion rate that is limited due to the aggregates formed by the interaction of asphaltene-asphaltene; Region III: the interaction of asphaltene-asphaltene is broken by the interaction of surfactant-asphaltene. The asphaltene aggregates reduce and adsorb rapidly at the interface. Furthermore, the results reveal that the asphaltenes concentration affects coverage rate and adsorption at the interface.#br#   

  1. Institute of Physical Chemistry, College of Chemistry, Jilin University, Changchun 130023, PR China
  • Contact: Zhou Guangdong E-mail:zhougd@jlu.edu.cn

Abstract: As high polar components of crude oil, asphaltenes play a significant role in reducing oil-water interfacial tension (IFT). In this paper, the effects of asphaltenes on reducing IFT in presence of surfactant were compared, and the mechanism of asphaltenes reducing the IFT was studied by the dynamic interfacial tension (DIFT) equation. Whether asphaltenes were added into the oil or 2, 5-dimethyl-4-(4-dodecyl) benzene sodium sulfonate (p-S14-4) added into the water phase, either of all results in the IFT reducing and the IFT is related to the coverage and the mass of asphaltenes adsorption at the interface. In presence of asphaltenes, the adsorption of the active substances to the interface is not entirely dependent on diffusion, and the process can be divided into three regions. Region I: the IFT rapidly reducing, this process is controlled by diffusion of surfactant; Region II: the IFT reducing slowly, resulting from the lower diffusion rate that is limited due to the aggregates formed by the interaction of asphaltene-asphaltene; Region III: the interaction of asphaltene-asphaltene is broken by the interaction of surfactant-asphaltene. The asphaltene aggregates reduce and adsorb rapidly at the interface. Furthermore, the results reveal that the asphaltenes concentration affects coverage rate and adsorption at the interface.

Key words: Asphaltenes, Dynamic Interfacial Tensions, Synergistic Interaction, Adsorption, Equilibrium Interfacial Tension