A phytic acid-functionalized graphene oxide/chitosan composite as a high-performance electrode for electrosorptive removal of uranium(vi) from aqueous solutions

Abstract

The development of high-performance materials for the selective recovery of uranium from aqueous solutions is crucial for both environmental remediation and resource recycling. Herein, we report the rational design and synthesis of a novel ternary composite, phytic acid-functionalized graphene oxide/chitosan (PA–GO–CS), as a high-performance electrode for the electrosorptive removal of uranium(VI). In this composite, phytic acid (PA) uses its phosphonate groups to chelate uranyl ions (UO₂²⁺), graphene oxide (GO) provides a conductive and high-surface-area substrate, and positively charged chitosan (CS) acts as a binder to link the other two negatively charged components into a stable, 3D porous network. The electrochemical studies revealed that the PA–GO–CS electrode exhibits significantly enhanced electron transfer kinetics and a surface-controlled reduction mechanism. The electrode demonstrated an outstanding maximum electrosorption capacity of 760.36 mg g⁻¹ for uranium, as determined by the Langmuir isotherm model, with rapid kinetics reaching equilibrium in approximately 40 minutes. Mechanistic investigations using XPS and XRD confirmed a synergistic removal process involving initial chelation of U(VI) by PA followed by in situ electrochemical reduction to U(VI) and deposition of uranium oxides on the electrode surface. Furthermore, the composite electrode showed remarkable selectivity for uranium over competing ions and excellent reusability, retaining over 83.1% of its capacity after five cycles. This work presents a powerful strategy for fabricating multifunctional composite electrodes with synergistic effects for the highly efficient recovery of uranium.