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In this study, we demonstrate the first example of a MgAl layered double hydroxide intercalated by a ketoxime compound (dimethylglyoxime, DMG), that is, MgAl-DMG-LDH (abbr. DMG-LDH), which exhibits excellent capture of uranium (U(VI)) both at high (ppm) and low (ppb) concentrations. The as-formed DMG-LDH shows an enormous maximum U(VI) sorption capacity (q Um) of 380 mg g−1 and an exceptionally rapid sorption rate (k2 = 2.97 g mg−1 min−1), reaching a high uptake of 99.14% within 5 min. For natural and contaminated seawater with high concentrations of Na+, Ca2+, Mg2+ and K+ concomitant cations, the DMG-LDH still can trap ∼85% U, displaying highly effective sorption toward U. The interaction mechanism between UO22+ and DMG2− provides an important reference for the development of highly effective capture of U(VI) by ketoxime materials. The DMG-LDH is currently the best ketoxime material for uranium extraction from nuclear waste and seawater. [ABSTRACT FROM AUTHOR]

Oxygen-rich pyromellitic acidic anions (PMA4−) have been intercalated into MgAl-layered double hydroxides to fabricate the MgAl–PMA–LDH (abbr. PMA–LDH) composite exhibiting excellent adsorption performance toward uranium (U(VI)). Benefiting from the large number of functional groups of –COO−, the PMA–LDH displays an extremely large maximum U adsorption capacity (q Um) of 352 mg g−1 and an ultra-fast sorption rate, reaching uptakes of ∼97% within 30 min and >99% in 1 h at the initial U concentration (C U0) of 113 ppm. Over a very wide pH range of 5–11, high U removals (>93%) are achieved at C U0 = 105 ppm. Moreover, in the presence of highly concentrated competitive ions, ultra-high selectivity of UO22+ is observed, giving a very large distribution coefficient (Kd) of ∼106 mL g−1. Moreover, the PMA–LDH exhibits effective capture of UO22+ in contaminated simulated seawater, showing high uptakes of >93% at C U0 ∼ 10 ppm and >98% at C U0 ∼ 100 ppm. The dispersion effect of LDH layers may contribute to the increase of U adsorption capacity, and the confinement effect of LDH is conducive to the improvement of sorption selectivity toward U. The exploration of the interaction mechanism of UO22+ with PMA4− confined within the LDH gallery offers an important basis for the fabrication of new kinds of organic/inorganic hybrid materials. The PMA–LDH is a highly effective adsorbent which can be applied to uranium extraction from seawater and uranium disposal in nuclear wastewater. [ABSTRACT FROM AUTHOR]