The aggregation and sedimentation stability of asphaltene solutions in toluene treated in an ultrasonic field (field intensity, 18 W/cm(2); frequency, 22 kHz) for 5 and 10 min was examined. To study the microstructure of the supramolecular formations of asphaltenes and the structural group composition of their averaged molecules, asphaltenes were repeatedly isolated from toluene solutions. It was found that the degree of dispersion of asphaltene aggregates and the aggregation and sedimentation stability increased as a result of ultrasonic treatment for 10 min. In this case, the relative concentration of aliphatic fragments and the numbers of rings in the naphthene-aromatic system, heteroatomic structural fragments, and blocks in the average asphaltene molecule decreased.
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