The Adsorption And Desorption Behavior Of Interfacially Active Asphaltenes On The Mineral Surface In The Non-aqueous Phase

Emulsification is commonly in the process of unconventional oil extraction and sludge treatment.The rigid interfacial film formed by the synergy of oil and solid in the emulsion tends to make the emulsion stable and difficult to separate.In this paper,the ad-sorption mechanism and configuration of asphaltene and its interfacial active compo-nent-Interfacially Active Asphaltene（IAA）on the surface of silica were studied,the de-sorption behavior of IAA adsorbed on the surface of silica by an oxygen-rich non-ionic demulsifier-TJU-2 was explored.The aim is to reveal the mechanism of oil-solid syner-gistic emulsification and the action mode of TJU-2 on the demulsification with sol-id-containing emulsions.In this paper,the differences in the adsorption characteristics between IAA and as-phaltenes on the silica surface are explored through Quartz Crystal Microbalance with Dissipation（QCM-D）,Atomic Force Microscopy（AFM）,and molecular dynamics simu-lation.Experiments have found that the adsorption of asphaltenes on the silica surface conforms to the Langmuir adsorption model,and the adsorption layer is uniform（surface aggregates are 20-60 nm）.The adsorption of IAA on the silica surface conforms to the Freundlich adsorption model,and the adsorption surface aggregates are larger（20-150 nm）and more dispersed.IAA has a stronger affinity for solid surfaces than asphaltenes(F_ad（IAA）=～0.0943 m N/m,F_{ad（asphaltenes）}=～0.0264 m N/m).Molecular dynamics simulations found that the adsorption of asphaltenes on the silica surface is mainly due to the com-bined effect of hydrogen bonds and van der Waals forces.By comparison,the adsorption of IAA is mainly due to the hydrogen bond interaction between sulfoxide and silanol.The interaction between IAA and silica surface is stronger than asphaltenes.Besides,the polar groups of IAA adsorbed on the surface of silica are exposed to the solvent,and it is easy to interact with the IAA molecules in the solvent to form larger agglomerates,forming a multilayer adsorption film structure.In contrast,asphaltenes tend to agglomerate in the solvent and form a limited uniform film adsorption structure on the silica surface.Through the QCM-D desorption experiment,the law of the IAA desorbed by a novel oxygen-rich non-ionic demulsifier-TJU-2 was explored.The best-desorbed conditions（50°C,1000 ppm）were obtained.It was found that the process of desorption can be di-vided into three main stages:the demulsifier molecules adsorb and penetrate the IAA ad-sorption membrane;the demulsifier molecules replace the IAA molecules to desorb the IAA molecules;the demulsifier molecules further adsorb on the solid surface to modify the solids again（from hydrophobic to hydrophilic）.AFM test found that after adding TJU-2,the surface force between IAA and silica decreases(F_ad（IAA）=～0.0589 m N/m).Us-ing molecular simulation to calculate the desorption of IAA,it was found that van der Waals force dominates the interaction between TJU-2 and IAA.But van der Waals force only promotes the adsorption of demulsifier molecules on the IAA membrane,does not promote the desorption of IAA.The hydrogen bond competition between the TJU-2 and IAA is the main mechanism of desorption.On this basis,the asphaltene emulsions containing and not containing Si O₂ solid par-ticles were formulated respectively.It was found that the droplet size of the emulsion containing Si O₂ particles（7μm）was significantly smaller than that of the emulsion with-out Si O₂ particles（26μm）.The demulsification test showed that the optimal concentration of TJU-2 was 800 ppm.The wettability and morphology of the solid particles in the emul-sion and the residual emulsion after demulsification was tested.It was found that during the demulsification process,the demulsifier has a modification effect on the surface of the solids and promotes the occurrence of demulsification.