Characterization and Langmuir film properties of asphaltenes extracted from Arabian light crude oil

Abstract

The film forming properties at the air–water interface of asphaltenes from Arabian light crude oil have been investigated experimentally in a Langmuir trough. The stability and dynamical behavior of the films have been studied in compression–decompression cycles and at different temperatures and concentrations of the toluene spreading solution. The results are interpreted in terms of models for the microscopic structure of the films, where the asphaltene molecules are assumed to be arranged in a tilted or nearly edge-on orientation, and it is concluded that aggregation processes play a fundamental role in the interfacial properties of the asphaltenes. This conclusion is supported by measurements of the weight distribution of the asphaltene extract employing laser desorption/ionization and time-of-flight mass spectrometry, which show neat evidence for asphaltene aggregation for sufficiently high concentrations.