Molecular Dynamics Study on the Adsorption of Heavy Oil Drops on a Silica Surface with Different Hydrophobicity

Abstract

Adsorption of oil droplets on different hydrophilic and hydrophobic silica surfaces was studied by molecular dynamics simulations. The surfaces included fully hydrophilic, 50% hydrophobic, and fully hydrophobic silica, and the oil droplet belongs to a heavy oil drop containing asphaltenes and resins. The simulated results showed that the oil droplet is easier to adsorb on the fully hydrophobic system, and the oil phase moves faster than that on the other silica surface. After adsorption of the oil drop finished, the asphaltene and resin molecules on different surfaces showed different aggregated structure. On the fully hydrophilic surface, the asphaltene and resin molecules aggregate through a face-to-face stacking interaction, and they adsorbed vertically on the silica surface. This is attributed to formation of hydrogen bonding between the model molecules (asphaltenes and resins) and the silica surface. This result indicates that the hydrophilic surface has a stronger interaction with the asphaltenes and resins than the other surfaces. The calculated free energy of adsorption of the model molecules on different surfaces further proves that the fully hydrophilic surface has a stronger adsorption capacity to heavy oil drop.

Molecular Dynamics Study on the Effect of Polyacrylamide on Electric Field Demulsification of Oil-in-Water Emulsion

“…Crude oil, as an extremely complex multicomponent mixture, is a heavy component composed of asphaltene and resin, and its light component is composed of hydrocarbons such as benzene and cyclic hydrocarbons. Based on the research of Zhang et al, − we chose two asphaltenes, six resin molecules, and a variety of hydrocarbons to form the oil droplet model. The types and quantities of the selected molecules are shown in Figure S1 and Table S1, and the dynamic formation process of the oil droplet model is also included in the Supporting Information (Figure S2).…”

New insight into the role of the self-assembly of heteroatom compounds in heavy oil viscosity enhancement

“…1). The original asphaltene molecule has been widely used in previous work, 21,22 and the construction of the modified asphaltene molecule was to replace the heteroatoms in the original asphaltene molecule with C atoms. We conducted geometry optimizations and frequency analyses using the Gaussian 16 (A.03) program, 23 employing the B3LYP/D3BJ functional in conjunction with the def2-TZVP basis set.…”

Data Mining Guided Molecular Investigations on the Coalescence of Water-in-Oil Droplets

“…These models aimed to reveal the effect of diverse molecular moieties and were first employed to investigate asphaltene aggregations that simultaneously accompany asphaltene interfacial activities. In this regard, π–π interactions between the cores, , hydrogen bonds between heteroatoms, , hydrophobic interactions, etc., have all been observed to favor asphaltene aggregation, and the aggregated structures range from parallel stacking to T-shaped stacking depending on the driving forces . Following these works, significant amounts of simulation works have been further performed on the interfacial properties of asphaltenes.…”