Analysis of asphaltene nano-aggregates formation using dynamic light scattering: Experimental and kinetic modeling

Abstract

In this study, the kinetics of the aggregate behavior of asphaltene particles in a very dilute concentration range of 6.25-50 mg/L in toluene was investigated using the dynamic light scattering (DLS) technique. Then, the kinetics of asphaltene aggregation was analyzed by a proposed model based on the mass action law concept. Also, the presence of silica nanoparticles, SiO₂-NPs, was investigated for the analysis of asphaltene aggregation behavior. The DLS results showed that by selecting the optimum sonication time of 6 min, asphaltene monomers (1 nm) at concentrations of 6.25, 12.5, and 25 mg/L did not incline to form asphaltene nano-aggregates over time. However, at a concentration of 50 mg/L, at the initial moments, the asphaltene particles began to form large clusters and clots. The results obtained by model optimization showed good agreement with experimental data with acceptable accuracy and mean absolute percentage errors of 10.41% and 5.21% for concentrations of 6.25 and 12.5 mg/L, respectively. Also, the results showed that in the mixing ratios of $R_{a,n}=0.25$ and $0.5$ of asphaltene concentration to the concentration of nanofluid, SiO₂-NPs were placed between the polar particles of asphaltene and created a new structure in the colloidal solution that prevented the self-association of asphaltene molecules and increased the kinetic stability of the asphaltene particles.

Graphical Abstract

Keywords:

• Asphaltene
• aggregation
• dynamic light scattering
• mass action
• kinetic modeling
• silica nanoparticles