Characterization of Crude Oil Interfacial Material Isolated by the Wet Silica Method. Part 2: Dilatational and Shear Interfacial Properties.
Résumé
To better understand the water-in-oil (w/o) emulsion stability problem, the interfacial material (IM) of four different crude oils was isolated using the wet silica method and analyzed by different techniques. In part 1 (10.1021/acs.energyfuels.6b02899), we used gel permeation chromatog. to analyze the mol. size distribution of S-, Ni-, and V-contg. compds. Here, we report the use of dilatational and shear interfacial rheol. to analyze the interfacial properties of the IM films. In the second part of this series of papers, it is shown that the wet silica isolation method is reproducible and concs. the most surface-active mols. present in crude oils. Shear interfacial rheol. results showed perfect correlation to emulsion stability; stronger mech. properties lead to more stable w/o emulsions. Dilatational rheol. revealed that successive IM exts. from a crude oil are composed of mols. that behave increasingly like insol. surfactants that aggregate at the w/o interface. Lastly, shear rheol. expts. with dild. IM and dild. crude oil showed some differences that were ascribed to a different partitioning between the bulk and interface.