Adsorption kinetics of asphaltenes at liquid interfaces

When asphaltenes adsorb at liquid interfaces, after the rapid initial diffusion step toward the interface, a long reorganization and a progressive building of multilayers occur. The reorganization is faster at oil-water interfaces than at air-oil interfaces, but the multilayer formation takes similar times. In the case of oil-water interfaces, the time scales are similar for different oils, but the variation with asphaltene concentration is qualitatively different: adsorption becomes faster with increasing concentrations for oils that are good asphaltene solvents and slower in the case of poor solvents. The presence of surfactant changes significantly the adsorption process. (C) 2002 Elsevier Science (USA)