Harvesting of Surfactant-Solubilized Asphaltenes by Magnetic Nanoparticles

Asphaltenes are a severe problem for the oil industry. The high content of aromatic and aliphatic hydrocarbons in asphaltenes poses a challenge for efficient methods of the solubilization and degradation of their components. The main goal of this study was to investigate an efficient and innovative method for asphaltene solubilization with surfactants to produce supramolecular aggregates with affinity by magnetic nanoparticles (Fe3O4) for magnetic separation and degradation. Asphaltene mixed with the cationic surfactant cetyltrimethylammonium bromide (CTAB) was both solubilized in chloroform and the solvent dried with N2 to produce a film that was resuspended in water and formed a stable colloid with asphaltene incorporated in CTAB micelles. The suspensions of CTAB/asphaltene supramolecular aggregates obtained at different surfactant/asphaltene ratios were characterized by dynamic and static light scattering (DLS and SLS) and by electrophoretic mobility for ζ potential determination. CTAB concentrations of 30 and 60 mM produced spherical supramolecular aggregates (SMAs) of size between 100 and 200 nm with polydispersity. The ζ potential of CTAB micelles loaded with asphaltenes increased from +9.17 +/– 4.6 to +56.7 +/– 5.8 eV. Electron paramagnetic resonance revealed that asphaltene forms stable free radicals in CTAB micelles. Classical molecular dynamics simulations were also used to study interactions of the functional groups of asphaltenes. The association with CTAB micelles provided the binding affinity of asphaltenes for nanoparticulate magnetite (Fe3O4) and precipitation of the most CTAB content. In this condition, Fe3O4 promoted the degradation of asphaltenes to low molecular mass products. Therefore, incorporation in CTAB micelles is a simple and innovative method contributing to asphaltene removal, degradation, and possible conversion to products with aggregated value