Amidoxime-functionalized cellulose nanofibers/MXene aerogel for electric field enhanced uranium extraction from seawater

As a green and economical energy, nuclear power plays a significant role in the global energy supply. Uranium extraction from seawater is a highly promising strategy to utilize unconventional uranium resources and ensure the sustainability of the nuclear industry. However, the current uranium absorbents still suffer from long extraction time, low adsorption capacity, and poor selectivity. In this study, an amidoxime-functionalized cellulose nanofibers/MXene aerogel (MCA) with a three-dimensional porous structure was fabricated for efficient uranium extraction from seawater through electro-/physicochemical adsorption processes. The abundant porous structures and functional groups endowed the MCA with a high adsorption capacity of 515.46 mg/g in the physicochemical adsorption process. Furthermore, the MCA adsorbed 13.82 mg/g of uranium from natural seawater after 28 days with a superior selectivity for uranyl ions. Encouragingly, the uranium extraction performance was significantly boosted via the assistance of an electric field. By applying a voltage of 1.0 V, the MCA presented an improved extraction capacity of 1826.38 mg/g and accelerated adsorption kinetic. Meanwhile, the MCA electrode possessed good stability and high reusability of 84.30% after five adsorption–desorption cycles, which insured that MCA was a promising uranium adsorbent in long-term application. This work offers a universal paradigm for the design of highly efficient electro-adsorbents and also expands the scope of external field enhancement in the area of uranium extraction.