Enhanced adsorption of naproxen from aquatic environments by β-cyclodextrin-immobilized reduced graphene oxide

Abstract

In this study, a one-step hydrothermal method synthesized β-cyclodextrin-immobilized reduced graphene oxide composite (β-CD/rGO) was employed to remove naproxen from aquatic environments. The β-CD/rGO had a porous structure with abundant hydroxyl groups, and acetalization between the β-CD and rGO provided a more stable three-dimensional structure. The maximum equilibrium adsorption capacity of naproxen on β-CD/rGO at 313 K was 361.85 mg g−1. The adsorption of naproxen onto the β-CD/rGO fit well with the pseudo-second-order kinetics and the Langmuir adsorption model. The ΔH was higher than 40 kJ mol−1, which indicated that this adsorption was chemisorptive and endothermic. Host-guest interaction, hydrogen bonding, and π-π interactions were uncovered as three main mechanisms involved in binding between naproxen and the β-CD/rGO. Moreover, used β-CD/rGO could be regenerated with ethanol, making this an attractive method for naproxen adsorption in aquatic environments.