Green and efficient U(VI) uptake from saline lake brines by Ti3C2Tx nanosheets and their derived 3D antioxidant hydrogels

This study developed antioxidant Ti 3 C 2 T x hydrogel beads for extracting uranium resources in saline lakes. Various characterizations (XRD, SEM, TEM, FT-IR, XPS, and TGA) indicated that the introduction of sodium alginate (SA) and ascorbic acid (VC) was driven by hydrogen bonding. Subsequently, Ca 2+ induced the cross-linking of SA/Ti 3 C 2 T x to form a stable 3D structure. During these processes, VC effectively inhibited the oxidation of Ti layers. In batch experiments, VC-Ti 3 C 2 T x achieved rapid U(VI) equilibrium (2 h) with a maximum uptake of 439.5 mg/g (pH = 5.0, 35 °C). Moreover, VC-Ti 3 C 2 T x exhibited good regeneration in 0.1 M HCl and high selectivity in the presence of Na + , K + , Mg 2+ , Ca 2+ , SO 4 2− , and VO 4 3− ions. Besides, VC-Ti 3 C 2 T x had a superior ability to capture trace uranium from actual brines (1075.0 μg/g) compared to other adsorbents. The adsorption mechanism obtained from SEM-EDS, FT-IR and XPS mainly involved coordination with surface hydroxyl groups, redox reaction with VC, and ion exchange with Ca 2+ in alginate matrix. Overall, VC-Ti 3 C 2 T x exhibited excellent performance of U(VI) uptake in complex saline lake brines, highlighting its potential for application in uranium resource recovery. • A new VC-Ti 3 C 2 T x is developed for green and efficient U(VI) uptake in salt lakes. • VC prevents the oxidation of Ti 3 C 2 T x and jointly captures U(VI) with Ti 3 C 2 T x . • VC-Ti 3 C 2 T x exhibits good regeneration and trace U(VI) adsorption (1075.0 μg/g). • Adsorption mechanism involves coordination, redox reaction, and ion exchange.