N-Alkyl calix[4]azacrowns for the selective extraction of uranium. Issue 41 (27th September 2018)

• Record Type: Journal Article
• Authors: Wehbie, Moheddine; Arrachart, Guilhem; Le Goff, Xavier F.; Karamé, Iyad; Pellet-Rostaing, Stéphane
• Is Part Of: Dalton transactions. Volume 47:Issue 41(2018)
• Page Start: 14594
• Page End: 14603
• Publication Date: 2018-09-27
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt03140a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Novel N -substituted calix[4]azacrown extractants display selective extraction properties in regards to uranium from sulfuric acid solution. Abstract : The selective extraction of uranium by N -octylcalix[4]azacrown (NOCAC) and N -ethylhexylcalix[4]azacrown (NEHCAC) was investigated. The ligands were synthesised in three steps through the functionalisation of t -butyl calix[4]arene at the distal-1, 3-positions of the lower rim with ethyl acetate groups followed by cyclisation with (imino)bis(ethane-2, 1-diyl)diamide. A detailed investigation on the effect of various parameters, such as the aqueous phase acidity (sulfuric acid), the ionic strength, and ligand concentration, on the extraction of uranium(vi ) has been conducted. The effect of the H2 SO4 concentration has been studied from 0.02 to 3 M. Preliminary studies carried out on NOCAC in dodecane/octanol diluents showed that the uranium extraction from sulfuric acid is more efficient at a low H2 SO4 concentrations. The stoichiometry of complexation was estimated from the slope method, NMR titration, and electrospray ionisation-mass spectrometry analysis. Both ligands were found to be highly selective for uranium(vi ) over other competitive cations present in a simulated leach solution containing seven competitive cations. The successful recovery of the uranium from the organic phase has been performed thanks to stripping steps involving ammonium oxalate, ammonium carbonate, and sodium carbonate as stripping agents.