Effects of molecular polarity on the adsorption and desorption behavior of asphaltene model compounds on silica surfaces

Abstract

Despite a large number of researches to understand the aggregation behavior and adsorption mechanism of asphaltene, the effects of asphaltene molecular structure on the adsorption/desorption behavior of asphaltene on rock surfaces remain scarce, which limits the understanding of the interaction mechanism under complex conditions and seriously restricts the development of heavy oil recovery technology. Here, in-situ adsorption/desorption experiments combined with molecular dynamics simulations were used to fill in the gap. The results show: 1) on hydrophilic surfaces, the heteroatoms or polar groups present in the symmetrical components of asphaltene mainly determine the adsorption behavior; 2) on intermediate wettability surfaces, the adsorption of asphaltene is driven primarily by π-π stacking and hydrogen bonding interactions; 3) on hydrophobic surfaces, it is difficult to adsorb asphaltene due to the lack of polar sites and steric effects, but once adsorption occurs, it is difficult to be stripped off by low salinity water. Our results provide a simple strategy to investigate the adsorption behavior of asphaltene on rock surfaces using laboratory experiments and theoretical simulations, which not only contributes to fundamental understanding but also helps to develop a new guide for practical applications.