Asphaltene Adsorption using Nanoparticles with Different Surface Chemistry: Equilibrium and Thermodynamics Studies

This study investigates the equilibrium adsorption of asphaltene onto several nanoparticles (NiO, MgO, Fe3O4) with different surface chemistry at various temperatures by UV-Vis spectroscopy. The NiO had acidic surface; however the MgO and Fe3O4 had basic and amphoteric surfaces respectively, which were determined by titration method. The isotherm data of the nanoparticles were best modeled by Langmuir model that indicated monolayer asphaltene adsorption onto the nanoparticles. The maximum asphaltene adsorption capacities of the nanoparticles were obtained at minimum temperature (25 degrees C) in the range of 0.6364-1.0545 mg/m(2) that decreased in the order of NiO > MgO > Fe3O4. The results confirm the potential application of nanoparticles with acidic surface for adsorption and removing of asphaltene. Moreover, the thermodynamic parameters at different temperatures showed that the adsorption of asphaltene onto the nanoparticles was spontaneous (Delta G(0) < 0), exothermic (Delta H-0 < 0) and physical (2.1< |Delta H-0| <20.9 kJ/mol).