Industrial & Engineering Chemistry Research, Vol.58, No.19, 8072-8079, 2019
Experimental and Computational Study on the Adsorption Mechanism of 2-Arylpropionic Acids on Graphene: Solvent Effects and Aromatic Features Affecting the Adsorption Performance
Adsorption of five 2-arylpropionic acids on graphene indicated that there was a competition between the solute molecules remaining in water solution and depositing on the graphene surface. The pH-dependent experiments showed that the adsorption of five 2-arylpropionic acids on graphene was significantly restrained by the effects of solvent-solute interactions. To find out the relevance between the adsorption capacity and solvent effects, a distribution coefficient (Log D) was introduced and employed to reflect the variation of solvent effects with different pH. An unexpected accordance was observed between the curves of adsorption capacity and Log D values. Then, we extended our work to probe the interactions between 2-arylpropionic acids and graphene. It was found that the experimental adsorption coefficients (K-d) of five adsorbates were closely related to their aromatic features, such as the numbers and distribution of the aromatic rings in their structures, rather than their hydrophobicity, suggesting that the pi-pi stacking between the aromatic systems and graphene was the dominant interaction. For further investigation of the interactions involved in the adsorption mechanism, the molecular simulation technique was used to present the possible interaction models between five 2-arylpropionic acids and graphene, which also helped to understand the pi-pi stacking interaction at the molecular level.