Enhancement of Adsorption Performance for Organic Molecules by Combined Effect of Intermolecular Interaction and Morphology in Porous rGO-Incorporated Hydrogels

Abstract

In this study, we developed reduced graphene oxide (rGO)-incorporated porous agarose (Ar-rGO) composites that were prepared via a "one-pot" sol-gel method involving a mixing and vacuum freeze-drying process. These composites represent an easy-to-use adsorbent for organic contaminant removal. Ar-rGOs can efficiently adsorb organic molecules, especially aromatic organic compounds from wastewater, because of the synergistic effect between the agarose bundles, which function as a water absorption site, and the rGO sheets, which function as active sites for pollutant binding. The pore structures and morphology of the Ar-rGO composites varied according to the added rGO, resulting in effective water infiltration into the composites. The main adsorption mechanism of the aromatic organic compounds onto Ar-rGOs involved pi-pi interactions with the rGO sheets. The surface interaction was more effective for adsorbing/desorbing the aromatic pollutants than the electrostatic interaction via the O-containing functional groups. In addition, we confirmed that Ar-rGO is highly stable over the entire pH range (1-13) because of the presence of the rGO sheets.