Improvement of the cloud point extraction of uranyl ions by the addition of ionic liquids.
The cloud point extraction (CPE) of uranyl ions by different kinds of extractants in Triton X-114 (TX-114) micellar solution was investigated upon the addition of ionic liquids (ILs) with various anions, i.e., bromide (Br(-)), tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)) and bis[(trifluoromethyl)sulfonyl]imide (NTf2(-)). A significant increase of the extraction efficiency was found on the addition of NTf2(-) based ILs when using neutral extractant tri-octylphosphine oxide (TOPO), and the extraction efficiency kept high at both nearly neutral and high acidity. However, the CPE with acidic extractants, e.g., bis(2-ethylhexyl) phosphoric acid (HDEHP) and 8-hydroxyquinoline (8-HQ) which are only effective at nearly neutral condition, was not improved by ILs. The results of zeta potential and (19)F NMR measurements indicated that the anion NTf2(-) penetrated into the TX-114 micelles and was enriched in the surfactant-rich phase during the CPE process. Meanwhile, NTf2(-) may act as a counterion in the CPE of UO2(2+) by TOPO. Furthermore, the addition of IL increased the separation factor of UO2(2+) and La(3+), which implied that in the micelle TOPO, NTf2(-) and NO3(-) established a soft template for UO2(2+). Therefore, the combination of CPE and IL provided a supramolecular recognition to concentrate UO2(2+) efficiently and selectively.
Beijing National Laboratory for Molecular Sciences (BNLMS), Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
Song
S
Gao
Taoxiang
T
Sun
Qingde
Q
Chen
Xinghai
X
Shen
D001881:Borates / Q000737:chemistry; D001965:Bromides / Q000737:chemistry; D005591:Chemical Fractionation; D004867:Equipment Design; D005461:Fluorine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007094:Imides / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D007477:Ions; D007554:Isotopes / Q000737:chemistry; D007811:Lanthanum / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry; D008823:Micelles; D017830:Octoxynol; D015125:Oxyquinoline / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D013501:Surface-Active Agents; D013696:Temperature; D014501:Uranium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis
D001881:Borates; D001965:Bromides; D007094:Imides; D052578:Ionic Liquids; D007477:Ions; D007554:Isotopes; D008670:Metals; D008823:Micelles; D010710:Phosphates; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; D005461:Fluorine; D011092:Polyethylene Glycols; D014501:Uranium; D015125:Oxyquinoline; D007811:Lanthanum; D017830:Octoxynol; C010615:Nonidet P-40
Cloud point extraction; Ionic liquids; Uranium