Constructing a novel Ti3C2Tx nanocomposite via intercalation of guanidine phosphate to realize selective and effective uranyl extraction

Abstract

There are abundant uranium resources in salt lake brines, but the high salinity background brings huge challenges to the selective extraction of uranyl. In this work, a novel Ti₃C₂T_x nanocomposite was constructed by the intercalation of guanidine phosphate (GP) to achieve the selective and effective uranyl extraction. Characterization analyses showed that the intercalation of GP was driven by ion exchange or electrostatic interaction. At the temperature of 35 °C, the adsorption of GP-Ti₃C₂T_x quickly reached equilibrium after 2 h (q_max = 270.7 mg/g). Mechanism investigations showed that the adsorption of uranyl on GP-Ti₃C₂T_x mainly included electrostatic attraction of oxygen-containing functional groups, chemical reduction by GP, and the coordination of phosphate and guanidine groups. Noteworthy, the adsorption capacity of GP for trace uranium (296.3 ± 13.8 μg/L) in actual brine was 806.3 μg/g. Even if the concentrations of coexisting Na⁺, K⁺, Mg²⁺, Ca²⁺, VO₄³⁻ and SO₄²⁻ far exceeded the concentration of salt lake sample, GP-Ti₃C₂T_x exhibited satisfactory selectivity. Overall, this novel Ti₃C₂T_x nanocomposite provides new insights into the extraction of uranium from salt lake brines.