Z. V. Safronova

Extraction of Lanthanides(III) from Aqueous Nitrate Media with Tetra‐(p‐tolyl)[(o‐Phenylene)Oxymethylene] Diphosphine Dioxide

A novel tridentate neutral organophosphorus compound, tetra‐(p‐tolyl)[(o‐phenylene)oxymethylene] diphosphine dioxide (I) has been synthesized and its extracting ability for microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 and NH4NO3 aqueous solutions has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes and conditional extraction constants of Ln(III) have been determined. The extraction behavior of compound I is compared with that of the diglycolamide ligand TODGA. The potentialities of polymeric resin impregnated with compound I for the preconcentration of lanthanides(III) from nitric acid solutions are demonstrated.

EXTRACTION OF SCANDIUM, RARE-EARTH ELEMENTS, AND YTTRIUM FROM NITRIC ACID SOLUTIONS BY SELECTED DIPHOSPHINE DIOXIDES

ABSTRACT The extraction of microquantities of Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 solutions by selected diphosphine dioxides of various structures in dichlorethane has been studied. It has been found that the extraction of these elements decreases with an increase in the number of methylene units (n) in the molecule of dioxide Ph2P(O)(CH2)3P(O)Ph2. Extractability of rare-earth elements decreases from La to Lu when methylene dioxide is used. With ethylene dioxides, it changes in the reverse order. The effect of HNO3 concentration in the aqueous phase and that of the extractants in the organic phase on the extraction of Sc, rare earth elements, and Y are considered. The stoichiometry of the extracted complexes has been determined and the extraction constants calculated.

Extraction of U(VI), Th(IV), Sc(III), and Rare‐Earth Elements from Nitric Acid Solutions by Selected Bifunctional Neutral Organophosphorus Compounds

Abstract The extraction of microquantities of U, Th, Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 solutions by bifunctional neutral organophosphorus compounds R2P(O)CH2P(O)Ph(OBu), R = Ph (II), R = Oct (IV), R = p‐Tol (V), R = p‐CH3OC6H4 (VI) in organic diluents has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined and the extraction constants calculated. The replacement of phenyl radicals in the Ph2P(O)CH2‐fragment of compound II by p‐tolyl or p‐methoxy‐phenyl ones leads to an increase of metal ions extraction. The introduction of octyl substituents at the same part of molecule II instead of phenyl ones favors the extraction of Th(IV), Sc(III), and heavier Ln(III) ions. However, the extraction of La–Eu from HNO3 solutions decreases when octyl‐substituted compound IV is used as an extractant. All effects of substituent replacements were studied with 1,2‐dichloroethane as diluent. The extractive efficiency of compounds II, IV, V, and VI is compared with that of tetraphenylmethylene‐diphosphine dioxide (I) and dibutyl(diphenylphosphinylmethyl)phosphonate (III).

Extraction of Rare‐Earth Elements from Nitric Acid Solutions by Selected Bifunctional Acidic Organophosphorus Compounds

Abstract The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 solutions by bifunctional acidic organophosphorus compounds R2P(O)CH2P(O)Ph(OH), R=Ph (I), R=Oct (II), R=p‐Tol (III), R=p‐CH3OC6H4 (IV), and Ph2P(O)CH2P(O)(OBu)(OH) (V) in organic diluents has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. The replacement of phenyl radicals in the Ph2P(O)CH2 fragment of (diphenylphosphinylmethyl)phenylphosphinic acid (I) by p‐tolyl ones has been found to increase rare‐earth ion extraction. The introduction of p‐methoxy‐phenyl or octyl substituents instead of phenyl ones at the same part of molecule I, facilitates the extraction of Eu–Lu and Y or Tb–Lu and Y, respectively. However, the extraction of other lanthanides from 3 M HNO3 solutions decreases when p‐methoxy‐phenyl or octyl‐substituted compounds in toluene are used as extractants. The replacement of phenyl radical in the P(O)OH fragment of compound I by a butoxy‐group brings about a decrease in rare‐earth elements (REE) extraction. The effect of octyl radicals substitution by phenyl ones in compound II on the extraction of lanthanide ions decreases as the atomic number of REE increases. The extraction efficiency of octyl‐substituted compound II has been observed to be higher than that of phenyl‐substituted compound I when HNO3 concentration in the aqueous phase decreased or when diluents with a small Schmidts diluent parameter (DP) were used.

Recovery of Rare-Earth Elements from Nitric Acid Solutions with a Polymeric Sorbent Impregnated with Diphenyl(dialkylcarbamoylmethyl)phosphine Oxides

The distribution of lanthanides (Ln), including also Y, between aqueous HNO3 and a microporous styrene-divinylbenzene copolymer impregnated with diphenyl(dialkylcarbamoylmethyl)phosphine oxides (CMPOs) and their α-substituted derivatives was studied in relation to the aqueous phase acidity and extractant content in the solid phase. Rare-earth elements pass into the sorbent phase in the form of complexes with the Ln : CMPO ratio of 1 : 2. The Ln distribution factors grow as the HNO3 concentration in the aqueous phase is increased from 0.1 to 7.0 M.

Preconcentration of U(VI), Th(IV), and REE(III) from nitric acid solutions using carbon nanotubes modified with bis(dioctylphosphinylmethyl)phosphinic acid

The extraction of microamounts of U(VI) and Th(IV) from HNO3 solutions in the form of complexes with bis(dioctylphosphinylmethyl)phenylphosphinic acid was studied. The stoichiometry of the extractable complexes was studied, and the influence of the extractant structure on the efficiency and selectivity of the U(VI) and Th(IV) extraction was examined. U(VI), Th(IV), and REE(III) can be preconcentrated from nitric acid solutions with a complexing sorbent prepared by noncovalent immobilization of bis(dioctylphosphinylmethyl) phosphinic acid on the surface of carbon nanotubes.

Selectivity of extraction of U(VI), Th(IV), and REE(III) from perchloric acid solutions with bidentate phosphoryl-substituted butyl phenylphosphinates

Extraction of microamounts of U(VI), Th(IV), and REE(III) from HClO4 solutions with solutions of bidentate phosphoryl-substituted butyl phenylphosphinates R2P(O)CH2P(O)Ph(OBu) [R = phenyl (I), octyl (II)] in dichloroethane was studied. The effect of substituents at the phosphorus atom in the phosphine oxide moiety of these compounds on their extraction ability and selectivity was examined, and the stoichiometry of the extractable complexes was determined. In going from nitric to perchloric acid solutions, the efficiency of the extraction of U(VI) and REE(III) considerably increases, the U/REE separation factors increase, but the Th/U separation factors decrease.

Extraction and sorption preconcentration of rare-earth elements(III) and scandium(III) with phosphorylmethyl-substituted butylphenylphosphinates from perchloric acid solutions

The interphase distribution of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc perchlorates between aqueous HClO4 solutions and solutions of bidentate phosphorylmethyl-substituted butylphenylphosphinates Oct2P(O)CH2P(O)Ph(OBu) (compound I) and Ph2P(O)CH2P(O)Ph(OBu) (compound II) in 1,2-dichloroethane is studied. The stoichiometry of extracted complexes is determined, and the efficiency of metal ion extraction into the organic phase is considered as a function of the HClO4 concentration in the aqueous phase and the nature of the organic solvent. The possibility of concentrating rare-earth elements (REE)(III) and scandium(III) from HClO4 solutions with the complexing sorbent synthesized by noncovalent immobilization of I and II compounds on a macroporuos polymer matrix is shown.

Extraction of U(VI), Th(IV), Pu(IV), and Am(III) from nitric acid solutions with polyfunctional organophosphorus acids

Extraction of microamounts of U(VI), Th(IV), Pu(IV), and Am(III) nitrates from aqueous HNO3 solutions with solutions of (diphenylphosphinylmethyl)phenylphosphinic, (di-p-tolylphosphinylmethyl)phenylphosphinic, and (dioctylphosphinylmethyl)phosphinic acids and of butyl hydrogen (diphenylphosphinylmethyl)phosphonate in organic diluents was studied. The metal: extractant stoichiometric ratio in the extractable complexes was determined, and the diluent effect on the extraction efficiency was examined. The possibility of using a macroporous polymeric sorbent impregnated with (dioctylphosphinylmethyl)phenylphosphinic acid for concentrating metal ions from HNO3 solutions was demonstrated.

Extraction of Am(III) and Eu(III) from Nitric Acid Solutions with Bidentate Neutral Organophosphorus Compounds

Extraction of HNO3 and microamounts of Am and Eu from nitric acid solutions with solutions of bidentate butyl (phosphorylmethyl)phenylphosphinates R2P(O)CH2P(O)Ph(OBu) [R = octyl (I), phenyl (II), p-tolyl (III), p-anisyl (IV)] in 1,2-dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the apparent extraction constants were calculated. The extractive power of the reagents studied toward HNO3 increases in the order II < III < IV < I, and toward Am(III), in the order I < II < III < IV.