LAUSR

Recently, different investigations have been performed to study the inhibiting effect of metal nanoparticles, which have shown high competence in delaying the onset of asphaltene precipitation. The goal of this work is to investigate the effect of Fe 3 O 4 metal nanoparticles on the size variation of asphaltene aggregates. The size distribution of three types of asphaltenes at different heptane to toluene (heptol) volume ratios was analyzed using dynamic light scattering technique immediately after the separation of nanoparticles. With the successive increase of heptol volume ratio, the size distribution ranges of asphaltenes moved to higher values. The particle size of asphaltene A was more sensitive to heptol addition. The aggregate size showed a rise from 72 to 5600 nm when the heptol ratio increased from 0 to 40%. Fe3O4 nanoparticle presence reduced asphaltenes A and B aggregate size, inhibiting large particle formation. The mean particle size of asphaltene A reduced 37% for nanoparticle dosage of 0.1 wt% and heptol ratio of 40%. However, the size of asphaltene C aggregates did not significantly change. The results showed that the aromaticity of asphaltenes followed the trend of asphaltene A > asphaltene B > asphaltene C, indicating the inhibiting effect of nanoparticles for more aromatic asphaltene. The inhibiting effect of nanoparticles attributes to the adsorption of asphaltene on the surface of nanoparticles. With increasing the aromatic character, the self-association of asphaltene particles and interactions between the aromatic core of asphaltene and Fe atoms rise, which increases the adsorption of asphaltene.