Evidence of selective asphaltene subfraction adsorption on SiO2 nanoparticles studied by UV-vis absorbance and fluorescence spectroscopy

The study of asphaltene adsorption onto nanoparticles is an area of great interest due to its ability to mitigate problems caused by asphaltenes in the oil industry. In this work, UV-vis absorbance and fluorescence spectroscopy were used to study asphaltene adsorption onto silica nanoparticles prepared from rice husk ash. The adsorption process followed a Dubinin-Radushkevich adsorption behavior, which suggested a progressive adsorption of larger aggregates onto the nanoparticles. From the Gaussian decomposition of the fluorescence emission spectra, it was determined that species of high molecular weight were preferentially adsorbed on the nanoparticles. These results have both academic and industrial importance since they help to propose more suitable thermodynamic models and methodologies to mitigate the issues related to adsorption and deposition of asphaltenes on surfaces.