Dilatational Rheological Properties of Asphaltenes in Oil–Water Interfaces: Langmuir Isotherm and Influence of Time, Concentration, and Heptol Ratios

Abstract

The dilatational rheological interfacial properties are important in colloidal systems due to the possibility of studying changes in the interfacial tension because of interface relaxation and diffusion. Information on these properties enables analyses on the interfacial activity and mechanical behavior of surfactants in the interfaces for different colloidal systems such as petroleum emulsions. The determination of elastic modulus is crucial for characterizing the interfacial behavior of films containing asphaltenes at interfaces. In this study, the pendant drop tensiometry technique was used to describe the rheological interfacial properties of asphaltenes extracted from two Brazilian oils at toluene/water and heptol (heptane + toluene)/water interfaces under varying proportions of organic solvents (1:1 and 1.5:1) and asphaltene concentrations. The applicability of adsorption isotherm models for involving Gibbs theory and Langmuir equation was investigated for the systems studied. For systems containing...