Modeling the kinetics of asphaltene flocculation in toluene–pentane systems for the case of sonicated crude oils

This work is concerned with the monitoring of ultrasound effects on inhibition, as well as the reversible kinetics modeling of asphaltene flocculation in toluene-n-alkane systems, which has been rarely reported in the literature. A crude oil sample was exposed to ultrasound waves, and then the colloidal structural evolutions of flocculated asphaltene particles induced by addition of n-alkane were studied, using a confocal microscopy. Observations confirmed that radiation of ultrasound can change the irreversibility of asphaltene flocculation in crude oil. To interpret the kinetics of asphaltene flock aggregation, the Smoluchowski model was used, and the time dependent size distribution of asphaltene flocks was predicted. Fractal analysis was applied and the parameters of the kinetic model were determined. The values for the regressed parameters of the kinetic model show that for sonicated oil, the formation coefficient decreases, while the disintegration coefficient did not considerably change. The reason might be that sonication prevents flocks from aggregating rather than disintegrating them into smaller flocks. It might be the reason for its lingering effect on flocculation. This work illustrates the successful application of the Smoluchowski model for predicting the kinetics of asphaltene flocks under the influence of ultrasonic radiation for the entire range of reversible flocculation processes.