Construction of a graphene/cellulose aerogel embedded with UiO-66-CN for highly efficient uranium capture via electro-adsorption

Abstract

Uranium capture is essential for the sustainable advancement of the nuclear industry and the management of uranium contamination, but the presence of various co-existing ions and low uranium concentrations pose a substantial challenge for uranium extraction from natural water sources. Herein, the cyano-functionalized UiO-66 anchored on a graphene/cellulose aerogel (UiO-66-CN/GCA) was successfully prepared for capturing uranium efficiently via an electro-adsorption procedure. Combining the advantages of the cyano-functionalized UiO-66 and graphene/cellulose aerogel, UiO-66-CN/GCA demonstrated excellent uranium selectivity and high uranium extraction capacity. With a voltage of 1.2 V, the saturated electro-adsorption capacity of UiO-66-CN/GCA reached 3092.3 mg g⁻¹, which was around 10.7 times the physicochemical adsorption capacity. Meanwhile, the adsorption equilibrium time at 1.2 V was also 1.5 h shorter than that without an applied voltage. In addition, UiO-66-CN/GCA was highly stable and still achieved a high uranium electro-adsorption capacity of 916.1 mg g⁻¹ after 10 cycles. Noteworthily, the physicochemical adsorption capacity of UiO-66-CN/GCA in natural seawater was 14.9 mg g⁻¹ in 28 days, while UiO-66-CN/GCA electro-adsorbed 110.1 mg g⁻¹ uranium in natural seawater within only 24 h. Furthermore, UiO-66-CN/GCA exhibited exceptional electro-adsorption abilities for uranium in various lake and river waters. This work not only offers an effective electrode material for uranium extraction, but also introduces an innovative electrochemical method for the separation of additional contaminating ions.