Functional graphene oxide nanosheets modified with cyclodextrins for removal of Bisphenol A from water

A novel type of functional graphene oxide nanosheets (GNs) modified with β-cyclodextrins (β-CDs) have been developed by coating dopamine-functionalized cyclodextrin (DACD) molecules on GNs for removing Bisphenol A (BPA) molecules from water. The DACD molecules with both β-CD groups for achieving adsorption property and dopamine (DA) groups for achieving adhesion property are synthesized by grafting DA onto carboxymethyl-β-cyclodextrin (CmβCD). The proposed DACD molecules can be firmly coated on the surfaces of various inorganic and organic substrates. Due to the large specific surface area of GNs, DACD-coated GNs (DACD@GNs) are proposed for efficient adsorption separation of BPA molecules from water. Due to the host-gust complexation between the BPA molecules in water and β-CDs on DACD@GNs, the fabricated DACD@GNs exhibit excellent adsorption performances. The adsorption kinetics can be explained via the pseudo-second-order model effectively. The experimental adsorption capacity of DACD@GNs is 11.29 mg·g−1 for BPA. Furthermore, after the adsorption process, the DACD@GNs can be easily separated from aqueous solutions via vacuum filtration with porous membranes, and then regenerated by simply washing with ethanol. The proposed strategy in this study can be used for effectively functionalizing the surfaces of various substrates with functional β-CDs, which is highly promising in applications in the field of adsorption separations, especially water treatments.