Extraction of Uranium from Aqueous Solution of Nitric Acid and Organic Solvent Using Ionic Liquid

In present study, tri-n-butylphosphate (TBP), a classical complexing agent for metallic cations, has been studied for the extraction of uranium into ionic liquids (ILs): 1-butyl-3-methylimidazoliumbis( tri-fluoromethylsulfonyl)imide ([BMIM][TF2N]) and trihexyl-tetradecylphosphonium-bis(trifluoromethylsulfonyl) imide ([P(14)666][TF2N]). Increasing HNO3 acidity of aqueous solution from 0.01 to 1 M the distribution ratio, DU decreases from 16 to 1.2 for 1.1 M TBP in [BMIM][TF2N] and the corresponding extraction efficiency (% E) varies from ~94 to 55. In the acidic range of 1 to 8 M DU and % E shows reversal trend of giving a local maximum at 8 M. This behaviour is compared and validates by literature. In contrast, on increasing in aqueous acidity from 0.01 to 8 M the extraction of uranium into [P(14)666][TF2N] ionic liquid, DU enhances from 2 to 39 and (%E) goes up from ~ 51 to 95. Since, [P(14)666][TF2N] works better than [BMIM][TF2N] in the acidic range > 0.1. This ionic liquid has been used for selective separation of uranium from strontium giving a DU of 63 and DSr of 2 with 98% E of uranium at 8 M acidity. To confirm the various species and groups in the formed complex, FTIR studies have been conducted.

Complexation of a macrocyclic ligand, 2,6-di (N-methyl)formamide-calix[4]pyridine, with Eu(III) and extraction of Eu(III) and Am(III)

Complexation of a new macrocyclic compound, 2,6-dimethylformamide-calix[4]pyridine (L1), with Eu(III) was studied by spectrophotometry. Stability constants of the Eu(III)/L1complex in different solvents were determined. The results reveal thatL1forms moderately strong complexes with Eu(III) and other lanthanides in aprotic solvents and shows little binding ability with transition metals. Moreover, the binding strength ofL1weakens significantly in protic solvents. Using 2-bromodecanoic acid as the synergistic reagent,L1extracts Am(III) and Eu(III) successfully with a separation factor of SFAm/Eu=1.3, and the distribution ratios of Am(III) and Eu(III) increases as the aqueous acidity is decreased. DFT computational studies were conducted to corroborate the solvent extraction data, and compare the coordination properties of Am(III)/Eu(III) complexes withL1and a related, 2,6-diformamide-calix[4]pyridine (L2). The computational results suggest thatL2could form stable complexes [ML]3+and ML(NO3)3[where M represent Am(III) or Eu(III)] in aqueous phase, in sharp contrast to the case ofL1where such complexes in aqueous phase are not stable.

Solvent Extraction of Fe(III) from Aqueous Chloride Solution by Cyanex 301 Dissolved in Kerosene

The title system has been investigated over a wide range of aqueous acidity. The equilibration time is 1 h. The extraction ratio (D) is independent of [Fe(III)] provided equilibrium [HCl] and [HA] are kept constant. At a constant equilibrium extractant concentration, the [HCl] dependences are -1.6, ~0 and -3 in the [HCl] regions of >3, 2-0.5 and <0.3 M; respectively; whilst at constant [HCl], the [HA] dependence is 3.0. On the other hand, [Cl-] dependence varies within -0.5 to -3 at constant [HCl] of 0.3 M; whereas its values are ~ -1 and ~ 0.63 at constant [HCl] of 3 and 1 M, respectively. Based on these results the extraction mechanisms have been suggested to be + 3 HA(o) ? FeA3(o) + n Cl- + 3 H+ in the low [HCl] region, + 3 HA(o) + n Cl- ? FeCl3.3HA(o) in the intermediate [HCl] region and HFeCl4 + 3 HA(o) ? FeCl3.3HA(o) + HCl in the high [HCl] region under investigation. The Kex and ΔH values have been evaluated. Loading capacity is 5.5 g Fe(III)/100 g Cyanex 301. The stripping can be made effective by a mixture of 6 M H2SO4 and 1 M Na2C2O4.Keywords: Extraction equilibrium; Fe(III) extraction; Cyanex 301; chloride medium.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi:10.3329/jsr.v3i1.6263 J. Sci. Res. 3 (1), 97-109 (2011)