Effective and sustainable Cs+ remediation via exchangeable sodium-ion sites in graphene oxide fibers

Abstract

A monovalent sodium-functionalized graphene oxide fiber (Na-GO) structure was synthesized via facile and simple liquid coagulation of a graphene oxide solution. Supported by the stable GO framework, the readily accessible sodium site of this alkali-metal-carbon heterostructure allows effective removal of Cs+ in aqueous medium with a rapid equilibrium time (similar to 30 min) and a large adsorption capacity (220 mg g(-1)). Na-GO possesses physical and chemical integrity in a broad pH range (4-10), and the adsorption behavior is influenced by the hydration radius of the targeting cation, charge effect, pi-M+ interaction, and pH-dependent GO hydrophilicity. In utilizing the chemical potential effect of Na-GO, a simple regeneration process with NaOH solution selectively releases captured Cs+ and replenishes functional sodium sites within the Na-GO structure, providing a rechargeable Cs+ remediation functionality. This study demonstrates the successful adaptation of the alkali-metal-induced reversible ion-exchange principle for a versatile GO fiber structure.