A model to calculate the average interaction energy and adhesion force between petroleum asphaltenes and some metallic surfaces

• Published in: Journal of colloid and interface science 2006-09, Vol.301 (2), p.352-359
• Main Authors: Ortega-Rodriguez, A., Alvarez-Ramirez, F., Cruz, S.A., Lira-Galeana, C.
• Format: Article
• Language: English
• Subjects: Adhesion force; Analytical model; Asphaltene adhesion; Chemistry; Exact sciences and technology; General and physical chemistry; Metallic surfaces; Surface physical chemistry
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2006.04.022

A model is proposed to account for the interaction energy and adhesion force between petroleum asphaltenes and metallic surfaces. It is assumed that the total molecule-surface interaction potential may be constructed through superposition of corresponding interactions with a relevant number of atomic layers forming the substrate and resorting to the Lindhard continuum planar potential (CPP) approximation, which requires only of knowledge of binary molecule-atom interactions. Molecular mechanics (MM) calculations are performed to generate the average binary interaction between the asphaltene molecule and an atom in the substrate, which in turn is represented by a parameterized analytical—physically sound—expression. The resulting CPP yields an analytical expression representing the interaction between the asphaltene molecule and each substrate layer. To validate the method, pilot calculations are performed for a sample asphaltene molecule with a fixed orientation relative to metallic surfaces of iron, aluminum, and chromium. Comparison between corresponding CPP and MM calculations for the asphaltene-plane (A-P) and asphaltene-substrate (A-S) interactions indicate reasonable agreement pointing to the adequacy of the CPP method to represent molecule-surface interactions. Also, the effect of a surrounding (i.e., solvent) medium is addressed with the use of a dielectric constant, ε, incorporated in the molecule-atom potential. Finally, a discussion is presented on the applicability of the method to generate an analytical universal expression for asphaltene-metallic wall interactions. A model based on the continuum planar potential approximation is proposed to account for the interaction energy and adhesion force between petroleum asphaltenes and metallic surfaces.