Evolution of adsorbed layers of asphaltenes at oil-water interfaces: A novel experimental protocol

Sefatallah Ashoorian; Aliyar Javadi; Negahdar Hosseinpour; Maen Husein

doi:10.1016/j.jcis.2021.02.123

Evolution of adsorbed layers of asphaltenes at oil-water interfaces: A novel experimental protocol

J Colloid Interface Sci. 2021 Jul 15:594:80-91. doi: 10.1016/j.jcis.2021.02.123. Epub 2021 Mar 9.

Authors

Sefatallah Ashoorian¹, Aliyar Javadi², Negahdar Hosseinpour³, Maen Husein⁴

Affiliations

¹ Institute of Petroleum Engineering, School of Chemical Engineering, College of Engineering, University of Tehran, 11155-4563 Tehran, Iran.
² Institute of Petroleum Engineering, School of Chemical Engineering, College of Engineering, University of Tehran, 11155-4563 Tehran, Iran; Institute of Process Engineering and Environmental Technology, TU Dresden, 01062 Dresden, Germany. Electronic address: Aliyar.javadi@tu-dresden.de.
³ Institute of Petroleum Engineering, School of Chemical Engineering, College of Engineering, University of Tehran, 11155-4563 Tehran, Iran. Electronic address: nhosseinpour@ut.ac.ir.
⁴ Department of Chemical & Petroleum Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada.

PMID: 33756371
DOI: 10.1016/j.jcis.2021.02.123

Abstract

Hypothesis: Asphaltenes can form rigid interfacial films surrounding water droplets rendering water separation from crude oil sluggish. Therefore, the quantitative characterization of such complex film formation is of great importance. As the adsorbed layers of asphaltene illustrate crumpling under compression at certain conditions, the evolution process from soft to rigid states of the film can be evaluated considering standard deviations from Young-Laplace shape fitting.

Experimental: In this study, novel experimental protocols are introduced to investigate the evolution of adsorbed asphaltene layer to a film of aggregates at model oil/water interface by means of dynamic interfacial tension (IFT) and dilational surface rheology measurements. In particular, the surface elasticity and standard deviation from the Young-Laplace shape fitting (YL-SD) are introduced as important indicators for the transformation of a regular asphaltene adsorbed layer to a film of aggregates. Different parameters affecting the film formation and stability, such as aging time, asphaltene concentration, and history of interfacial dynamics, are discussed and linked to emulsion stability.

Findings: It is shown for the first time that the standard deviation of drop profile fitting from the Young-Laplace equation can be used as a rigorous parameter to reveal the properties of the interfacial asphaltene film, which cannot be recognized by regular IFT measurements. Via this novel technique, it is revealed that the transformation of an asphaltene adsorbed layer to a rigid film depends not only on the asphaltene concentration but also on the aging time and the interfacial area perturbations. The results of this new method are supported by measurements of the dilational surface elasticity, which is known as an important parameter for the characterization of complex adsorbed layers, and further verified by an emulsion stability analysis.

Keywords: Asphaltene adsorbed layer; Dynamic interfacial tension; Emulsion stability; Interfacial rheology; Young-laplace profile analysis.