Multiscale characterization of asphaltenes and their extrography fractions titrated with n-heptane was performed. Chemical characterization via FT-ICR MS and GPC ICP HR-MS, stability monitoring via QCR, and AFM images of deposits indicate that "island"-enriched samples tend to form fewer, well-organized deposit aggregates, whereas samples with abundant "archipelago"-like molecules produce larger aggregates and less well-organized deposits. The combination of QCR and AFM leads to the conclusion that "island"-enriched samples lead to smaller deposits compared to "archipelago"-like molecules.
The processes in which crude oil asphaltenes aggregates are adsorbed onto surfaces have been the subject of debate in recent years. Different thermodynamic, theoretical and empirical models have been proposed to explain the interaction of asphaltenes with these surfaces and have found different behaviors. In this work, asphaltene adsorption onto SiO2 biogenic nanoparticles was experimentally monitored by studying it through two analytical techniques, namely, Gel Permeation Chromatography coupled with Inductively Coupled Plasma and High Resolution Mass Spectrometry (GPC-ICP HR MS) to follow the changes in aggregates size distributions in solutions and a Quartz Crystal Resonator (QCR) sensor to detect and follow the destabilization with n-heptane, thus allowing the correlation of the different stabilities and deposition tendencies with the changes in aggregate size distributions. The results show that the nanoparticles interact in a preferential way with the larger asphaltene aggregates, and, once these large aggregates are adsorbed, there is no tendency for new large aggregate formation.Thus, a reduction in the deposition is observed. This indicates that, in this range of concentration, there is no equilibrium for aggregate formation and that these larger aggregates can be effectively removed. This finding opens new methodologies for study regarding asphaltene removal.
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