Shear strength of interfacial films of asphaltenes

Experimental and modeling approach to study separation of water in crude oil emulsion under non-uniform electrical field

“…These molecules can interact with each other and reorganize at oil/water interfaces and produce a mechanically strong, rigid, viscoelastic stagnant film that resists droplet coalescence. This skin is formed through the interactions of surface-active molecules in the crude, which fall into two main categories, asphaltenes and resins [19][20][21][22].…”

“…Many excellent studies have discussed the role the asphaltene and asphaltene-resin interactions play in the stabilization of waterin-oil emulsions [7,20,22,[32][33][34][35][36].…”

Interfacial Phenomena of Purified Petroporphyrins and Their Impact on Asphaltene Interfacial Film Formation

“…This problematic class of compounds is defined as the portion of the crude oil that is soluble in toluene but not heptane, and it makes up a significant portion of heavy petroleum sources such as oil sands. Asphaltenes, with their high aromatic (H/C ratio of ∼0.8–1.5) and heteroatomic (∼1.9–10.8% S, ∼0.5–3.0% N, ∼0.7–6.6% O) contents, are surface active, both on solid surfaces and at liquid–liquid, specifically water–oil, interfaces where they adsorb to stabilize water-in-oil emulsions. − They self-assemble and entangle, forming discoidal nanoaggregates in solution , and strong, stable films at oil–water interfaces. − Asphaltene–asphaltene intermolecular interactions principally comprise dipole–dipole, Coulombic, and van der Waals dispersion interactions, hydrogen bonding, and π–π stacking. In addition to these major contributors, steric and inductive interactions and intermolecular charge transfer are less common but still relevant. ,,− …”

“…Simpler petroporphyrins are likely to be active at the interface but also highly labile, and may rapidly adsorb and desorb at the interface as well as onto asphaltene intermolecular interaction sites. Dodd and Dunning both found a definitive presence of metalated petroporphyrins at petroleum–water interfaces, and Dunning found a strong correlation between the interfacial activity of the petroleum and its petroporphyrin content. , Mansurov used a purification process to remove porphyrins, waxes, and acids from asphaltenes and found that asphaltenes with high porphyrin content lost 50% of their film strength from this purification procedure, while asphaltenes with low porphyrin content were basically unchanged …”

“…86,87 Mansurov used a purification process to remove porphyrins, waxes, and acids from asphaltenes and found that asphaltenes with high porphyrin content lost 50% of their film strength from this purification procedure, while asphaltenes with low porphyrin content were basically unchanged. 9 Our lab has developed a process of extraction and enrichment for purifying petroporphyrins using a series of solvent extractions, extrographic columns, chromatographic columns, and cooling-induced precipitation. This method was used to purify petroporphyrins (specifically vanadyl petroporphyrins, or VOPPs) at a preparatory scale for use in studies of both petroporphyrin and asphaltene self-assembly.…”