▎ 摘　　要

Hypothesis.: Organic co-solvents, which are universally employed in adsorption studies of hydrophobic organic chemicals (HOCs), can inhibit HOC adsorption by competing for active sites on the adsorbent. The adsorbent structure can influence co-solvent interference of HOC adsorption; however, this effect remains unclear, leading to an incomplete understanding of the adsorption mechanism. Experiments.: In this study, dioctyl phthalate (DOP) was used to investigate competitive adsorption on functionalized graphene sheet in a water-methanol co-solvent system through molecular dynamics sim-ulations and quantum chemical calculations. Findings.: The simulations showed that the functional groups in the graphene defects had a strong adsorption affinity for methanol. The adsorbed methanol occupied a large number of active sites at the graphene center, thereby weakening DOP adsorption. However, the methanol adsorbed at the graphene edges could not compete with DOP for the active sites. -COOH had the strongest binding affinity for methanol among the functional groups and thus predominantly controlled the interaction between gra- phene and methanol. This study makes an innovative contribution toward understanding the competitive adsorption of methanol and DOP on functionalized graphene sheet, especially in visualizing the compe- tition for active sites, and provides theoretical guidance for the removal of HOCs and practical application of graphene. (c) 2021 Elsevier Inc. All rights reserved.