Development of a Methodology Using GPC-ICP HR MS for Analysis of the Adsorption of Asphaltene Aggregates on SiO2 Nanoparticles

The aggregation and adsorption of asphaltenes is of great interest due to their negative effects on the oil industry. Asphaltenes form aggregates, even at low concentrations, producing groups of molecules with different molecular weights in equilibrium. Using GPC ICP HR MS, the different molecular weight fractions are separated. By monitoring the signals of S, V, and Ni ions, typical mass profiles are obtained. The V profile of asphaltene in toluene shows three zones corresponding to low, medium, and high molecular weight fractions in equilibrium. The present study describes the development of a method to study the adsorption of asphaltenes on SiO2 nanoparticles using GPC-ICP HR MS. Samples of asphaltenes in toluene were analyzed before and after adsorption onto nanoparticles (NPs). At low concentrations, the adsorption of larger aggregates predominates. The adsorption onto NPs increases the proportion of vanadium in the low molecular weight fraction of the solution.