Electron-buffering rechargeable microelectrode adsorbents for rapid environmental remediation of uranium-containing wastewater

Abstract

Environmental remediation of uranium-containing wastewater has emerged as a critical challenge in the nuclear industry, addressing both ecological protection and resource sustainability concerns. However, conventional adsorption methods suffer from slow kinetics, whereas electrochemical approaches are limited by the direct coupling between electron injection and uranyl ion reduction, leading to ion-blocking layers that severely impede remediation efficiency. Here we develop an electron-buffering rechargeable microelectrode adsorbent system that operates through a three-step cycle: electron storage, uranium extraction and adsorbent regeneration. This sequential process decouples electron injection from uranyl ion reduction by separating them in time and space. The microelectrode stores electrons in an environment free of competing ions and releases them in a controlled manner during uranium extraction. The Fe–O bonds on the surface serve as active sites for capturing uranyl ions and lowering their reduction overpotential, whereas the release of charge-balancing cations maintains surface electronegativity for efficient mass transfer. This synergistic integration achieves an initial extraction rate of 1,062 mg g−1 h−1 and a uranium capacity of 854 mg g−1, with nearly 100% electron utilization efficiency. Most importantly, when tested with actual uranium mine wastewater containing 0.545 ppm uranium, the system achieves 97.1% extraction efficiency and a capacity of 78.5 mg g−1 within 6 h, demonstrating its practical viability for environmental remediation. A synergistic approach for uranium extraction, a rechargeable microelectrode adsorbent system, integrates the functions of adsorption and electrochemical reduction, leading to an excellent extraction rate and high adsorption capacity.