Extraction and immediate solidification of uranium (VI) using malonamide functionalized ionic liquids from H2SO4 leaching liquor by specific self-assembly process

Abstract

A novel self-assembly process for simultaneous extraction and solidification of uranium (VI) from H2SO4 leaching liquor was pioneered using malonamide-based distearyldimethylammonium ionic liquids ([D1821]+[MA]−), which exhibited the good affinity and excellent extraction efficiency for uranium compared to 18 main elements, including Ca, Na, K, Al, Mg, Fe, Cu, Se, Sr, W, Mn, Zn, V, Co, Cr, Ba, Pb and Cd in real leaching liquor. The simultaneous separation and recovery of uranium (VI) was firstly realized by the selective self-assembly extraction of complex anion to form the solid by [D1821]+[MA]−, while leaving the other sulfates in aqueous solution. More than 99 % of uranium(VI) was extracted and enriched as self-assembly solid in one-step process, which could be easily recovered by filtration without further stripping and final precipitation. The self-assembly solid was characterized by XPS, FT-IR, 1H NMR, DLS and SEM-EDS methods. Based on the slope analysis and ESI-HRMS data, an unusual extraction mechanism was proposed in three-step process. [D1821]+[MA·UO2SO4]− was confirmed as the predominant component of self-assembly solid. The maximum loading capacity reached as high as 0.52 mol U(VI) per mole of the ionic liquid. The fewer steps, low cost, high extraction efficiency and excellent selectivity endowed the present strategy with the significant value in uranium hydrometallurgy, which could be employed as a potential alternative for recovery of uranium from real leaching liquor.