Recovery of rare-earth elements from nitric acid solutions by fullerene black impregnated with diphenyl(dibutylcarbamoylmethyl)phosphine oxide

The distribution of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO₃ solutions and fullerene black impregnated with diphenyl(dibutylcarbamoylmethyl)phosphine oxide (L) was studied. The influence exerted on the efficiency of REE recovery by the HNO₃ concentration in the aqueous phase and concentration of L in the sorbent phase was examined. The degree of REE recovery increases on adding HClO₄ to the aqueous phase.     

Preconcentration of rare earth elements(III) by sorption from nitric acid solutions using carbamoylmethylphosphine oxide and an ionic liquid

Sorption of microamounts of rare earth elements(III) from HNO₃ solutions with complexing sorbents prepared by noncovalent immobilization of diphenyl(dibutylcarbamoylmethyl)phosphine oxide and an ionic liquid, 1-methyl-3-butylimidazolium bis[(trifluoromethyl)sulfonyl]imide, on the surface of carbon nanotubes was studied in relation to the component ratio in the sorbent and to the HNO₃ concentration in the aqueous phase. The efficiency of the recovery of rare earth elements considerably increases when the sorbent phase contains the ionic liquid.     

Bis(Diphenylcarbamoylmethylphosphine Oxide) Ligand Containing 4, 7, 10 – Trioxatridecane Spacer: Novel Effective Extractant for Actinides and Lanthanides

A novel polydentate neutral organophosphorus ligand 1 containing two Ph₂P(O)CH₂C(O)NH- bidentate moieties connected by a 4, 7, 10 - trioxatridecane spacer through amide nitrogen atoms was synthesized and studied as an extractant for U(VI), Th(IV), and lanthanides(III) ions from HNO₃ solutions. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. Bis-CMPO ligand 1 was found to possess a higher extraction efficiency towards U(VI), Th(IV), and lanthanides(III) ions than its mono analog diphenylphosphorylacetic acid N-nonylamide 5 and bis-CMPO ligands containing a di- and a triethylene glycol spacers. The values of D_U, D_Th, and D_Ln for compound 1 are more than two orders of magnitude higher than those for its mono-CMPO analog 5.     

Extraction of U(VI) and Th(IV) from nitric acid solutions with tetraaryl-substituted (<Emphasis Type="Italic">o</Emphasis>-phenyleneoxymethylene)diphosphine dioxides

Extraction of U(VI) and Th(IV) from HNO₃ solutions in the form of complexes with tetraarylsubstituted (o-phenyleneoxymethylene)diphosphine dioxides is studied. The effect of substituents at the P atoms in the extractant molecule on its extraction ability and selectivity is considered. The stoichiometry of the extractable complexes is determined. The possibility of U(VI) and Th(IV) preconcentration with a complexing sorbent prepared by noncovalent immobilization of tetra-p-tolyl-substituted (o-phenyleneoxymethylene)-diphosphine dioxide on a polymeric matrix is demonstrated.     

Extraction of U(VI), Th(IV), and REE(III) from nitrate solutions with diaryl(dialkylcarbamoylalkyl)phosphine oxides containing a dialkylcarbamoylmethyl substituent in the alkylene bridge

The extraction of microamounts of U(VI), Th(IV), and REE(III) from HNO₃ and NH₄NO₃ solutions with solutions of diaryl(dialkylcarbamoylalkyl)phosphine oxides containing a dialkylcarbamoylmethyl substituent in the alkylene bridge was studied. The stoichiometry of the complexes extracted from nitric acid solutions with N,N,N',N'-tetrabutyl-2-(di-p-anisylphosphinyl)butanedioic diamide I was determined. The influence of the extractant structure and aqueous phase composition on the efficiency and selectivity of the extraction of U(VI), Th(IV), and REE(III) into the organic phase was examined. Introduction of the–CH₂C(O)NAlk₂ fragment into the methylene bridge of the diaryl(dialkylcarbamoylmethyl)phosphine oxide molecule considerably enhances the extraction of REE(III) from neutral nitrate solutions. Such modification of the extractant molecule only slightly influences the extraction of REE(III) from nitric acid solutions, but leads to a considerable increase in the U(VI) extraction and to a decrease in the Th(IV) extraction. The selectivity of the extraction of U(VI) and REE(III) is thus considerably increased.     

Extraction of rare earth elements(III) from HNO3 and HCl solutions with mixtures of carbamoylmethylphosphine oxides and picrolonic acid

Extraction of REE(III) microamounts from HNO₃ and HCl solutions with mixtures of mono- and bis-carbamoylmethylphosphine oxides with picrolonic acid in 1,2-dichloroethane was studied. The strong synergistic effect observed is due to increased hydrophobicity of the extractable complexes. The influence of the structure of carbamoylmethylphosphine oxides on the REE(III) extraction efficiency was considered, and the stoichiometry of the extractable complexes was determined. The possibility of REE(III) recovery and preconcentration from nitric acid solutions with a complexing sorbent prepared by noncovalent immobilization of the reagent mixture on the surface of a macroporous polymeric sorbent was demonstrated.     

Extraction of Lanthanides(III) with N,N′-Bis(Diphenylphosphinyl-Methylcarbonyl)Diaza-18-Crown-6 in the Presence of Ionic Liquids

The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from nitric acid solutions into an organic phase containing N,N′-bis(diphenylphosphinyl-methylcarbonyl)diaza-18-crown-6 and ionic liquid (IL) 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (BMImTf₂N) has been studied. The effect of HNO₃ concentration in the aqueous phase and that of the extractant and IL concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. A considerable synergistic effect was observed in the presence of IL in the organic phase containing a neutral organophosphorus ligand. This effect is connected with the hydrophobic nature of the IL anion. The partition of IL between the equilibrium organic and aqueous phases is the dominant factor governing the extractability of lanthanide (III) ions in the extraction system. The potentialities of polymeric resin impregnated with compound I and BMImTf₂N for the preconcentration of lanthanides(III) from nitric acid solutions are demonstrated.     

Extraction of Rare-Earth Elements from Nitric Acid Solutions with Ethylenediphosphine Dioxides

Extraction of microamounts of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu from HNO₃ aqueous solutions with ethylenediphosphine dioxides in organic diluents was studied. The effect of the dioxide structure on its extractive power and selectivity was considered. The stoichiometry of extractable solvates was determined.     

Extraction Properties of Trioxides of Pentasubstituted Diethylenetriphosphines in Nitric Acid Solutions

Extraction of HNO₃ and microamounts of U(VI), Th(IV), Sc(III), and REEs(III) from HNO₃ solutions with solutions of trioxides of symmetrical dioctyltriphenyldiethylenetriphosphine and pentaphenyl-diethylenetriphosphine in dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the effective extraction constants of HNO₃ and REEs were calculated. As the number of phosphoryl groups in the extractant molecule increases, the extraction of metal ions from nitric acid solutions is enhanced. Replacement of the octyl radicals at the terminal phosphorus atoms by the phenyl radicals is accom-panied by an increase in extraction of metal ions from solutions with the HNO₃ concentration exceeding 3 M.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 72–76.Original Russian Text Copyright © 2005 by Turanov, Karandashev, Bondarenko.