A novel 3D adsorbent of reduced graphene oxide-beta-cyclodextrin aerogel coupled hardness with softness for efficient removal of bisphenol A

摘要

A novel three-dimensional (3D) adsorbent of reduced graphene oxide-beta-cyclodextrin (r-GO-CD) aerogel was firstly synthesized through a one-step hydrothermal reaction. Various physicochemical characterization results demonstrated that the cross-linking of "soft" beta-cyclodextrin among the "hard" graphene oxide nanosheets, simultaneously combining with self-assembly process of aerogel, contributed to the formation of superior structural and stable r-GO-CD aerogel. The adsorption of bisphenol A (BPA) onto r-GO-CD was chemisorption and endothermic, which fitted well with the pseudo-second-order kinetic and Langmuir isotherm. The saturated adsorption capacity of r-GO-CD towards BPA was 346.0 mg g(-1) at 298 K, which was similar to 11 times to that of conventional activated carbon. The r-GO-CD displayed a promising environmental application potential as revealed from the stable BPA adsorption efficiency in diverse interferences (H+/OH-, NaCl), presence of trace BPA and repeated cycling tests. The long-term dynamic filtration experiment conducted with raw surface water showed that the effective treated volume of r-GO-CD towards BPA (100 mu g L-1) was 270 mL which was similar to 30 times to that of r-GO due to the excellent selectivity and adsorptivity of beta-cyclodextrin for BPA. The distinct adsorption mechanism of r-GO-CD aerogel was demonstrated as synergistic effects of graphene oxide nanosheets and beta-cyclodextrin, along with pi-pi interaction and hydrogen bonding.