Asphaltene Adsorption on Functionalized Solids

Asphaltenes, heavy aromatic components of crude oil, are known to adsorb on surfaces and can lead to pipe clogging or hinder oil recovery. Because of their multicomponent structure, the details of their interactions with surfaces are complex. We investigate the effect of the physicochemical properties of the substrate on the extent and mechanism of this adsorption. Using wetting measurements, we relate the initial kinetics of deposition to the interfacial energy of the surface. We then quantify the longterm adsorption dynamics using a quartz crystal microbalance and ellipsometry. Finally, we investigate the mechanism and morphology of adsorption with force spectroscopy measurements as a function of surface chemistry. We determine different adsorption regimes differing in orientation, packing density, and initial kinetics on different substrate functionalizations. Specifically, we find that alkane substrates delay the initial monolayer formation, fluorinated surfaces exhibit fast adsorption but low bonding strength, and hydroxyl substrates lead to a different adsorption orientation and a high packing density of the asphaltene layer.