V. K. Karandashev

EXTRACTION OF METAL CHLORIDE COMPLEXES BY PHOSPHORYL-CONTAINING PODANDS

ABSTRACT Extraction of Ti, Mn, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ag, Cd, In, Sn, Sb(III), Te(IV), La, Ta, W, Hg, Tl(III), Pb and Bi from hydrochloric acid solutions by a series of phosphoryl-containing podands with various terminal groups and oxygen bridges of different lengths has been investigated. The extraction results are discussed in relation to different diluents (nitrobenzene, dichloroethane, CHCb, CCU, toluene) and to the structure of the podands under study. It has been shown that the control over the podand structure and the nature of the diluents used allows wide-range variations of the metal chloride complexes extrability.

Extraction of Alkaline Earth Metal Ions with TODGA in the Presence of Ionic Liquids

Abstract The extraction of microquantities of Ca(II), Sr(II), and Ba(II) from aqueous solutions into the organic phase containing a diglycolamide ligand N,N,N′,N′- tetraoctyl-3-oxapentane diamide (TODGA) and ionic liquids (ILs) 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C4mim][Tf2N]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) 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 and conditional extraction constants of alkaline earth metal ions have been determined. A considerable synergistic effect was observed in the presence of ILs in the organic phase containing diglycolamide ligands. This effect is connected with the hydrophobic nature of the IL anion. The partition of ILs between the equilibrium organic and aqueous phases can govern the extractability of alkaline earth metal ions in TODGA - IL systems.

In silico design of new uranyl extractants based on phosphoryl-containing podands: QSPR studies, generation and screening of virtual combinatorial library, and experimental tests.

This paper is devoted to computer-aided design of new extractants of the uranyl cation involving three main steps: (i) a QSPR study, (ii) generation and screening of a virtual combinatorial library, and (iii) synthesis of several predicted compounds and their experimental extraction studies. First, we performed a QSPR modeling of the distribution coefficient (logD) of uranyl extracted by phosphoryl-containing podands from water to 1,2-dichloroethane. Two different approaches were used: one based on classical structural and physicochemical descriptors (implemented in the CODESSA PRO program) and another one based on fragment descriptors (implemented in the TRAIL program). Three statistically significant models obtained with TRAIL involve as descriptors either sequences of atoms and bonds or atoms with their close environment (augmented atoms). The best models of CODESSA PRO include its own molecular descriptors as well as fragment descriptors obtained with TRAIL. At the second step, a virtual combinatorial library of 2024 podands has been generated with the CombiLib program, followed by the assessment of logD values using developed QSPR models. At the third step, eight of these hypothetical compounds were synthesized and tested experimentally. Comparison with experiment shows that developed QSPR models successfully predict logD values for 7 of 8 compounds from that blind test set.

Effect of ionic liquids on the extraction of rare-earth elements by bidentate neutral organophosphorus compounds from chloride solutions

The partition of microamounts of lanthanide chlorides (Ln = La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) between aqueous HCl and organic solutions of tetraphenylmethylenediphosphine dioxide, diphenyl(diethylcarbamoylmethyl)phosphine oxide, and dibutyl(diethylcarbamoylmethyl)phosphine oxide was studied in the presence of ionic liquids (ILs): 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The stoichiometry of extracted complexes was determined. The effect of the aqueous HCl concentration, the nature of the extractant, and the organic diluent on the efficiency of lanthanide extraction was studied.

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 RARE-EARTH ELEMENTS FROM NITRIC SOLUTIONS BY PHOSPHORYL-CONTAINING PODANDS

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 phosphoryl-containing podands of various structures has been studied. It has been found that the maximum extraction of rare earth elements is exhibited by reagents containing one ether oxygen atom in the molecule, bound to diphenylphosphoryl or ditolylphosphoryl containing podands towards REE varies in a wide range, depending on the number of oxygen atoms in the polyether chain and the structure of the fragment connecting the ether oxygen atom with the terminal PO group. The podand structure which ensures a polydentate coordination of the reagent molecule to yield chelate complexes is favourable for REE extraction. The replacement of phenyl radicals in the podand VII molecule for butyl ones (compound IX) drastically reduces REE extraction. REE extraction by podands VII and VII increase from La to Lu with a decrease in the radii of extracted ions

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 chromatographic separation of Y, REE, Bi, Th, and U from the matrix suitable for their determination in pure iron and Low-Alloyed steels by ICP-MS and ICP-AES

The possibilities of tetraphenylmethylene-diphosphineoxide as stationary phase in extraction chromatography separation of REE, as well as Y, Bi, Th, and U from solutions of iron and microamounts of many other elements have been studied. The optimal conditions of separation are determined. The proposed procedure of chromatographic separation is quite applicable to the on- and off-line modes of ICP-MS and ICP-AES analyses of high-purity iron and low-alloyed steels.

EXTRACTION OF RARE-EARTH ELEMENTS AND YTTRIUM FROM NITRIC ACID SOLUTIONS BY BUTYL(DIPHENYLPHOSPHINYL-METHYL)PHENYLPHOSPHINATE

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 butyl(diphenylphosphinylmethyl)phenylphosphinate in organic diluents or on macroporous polymeric supports has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant in the organic phase on the extraction of rare-earth elements and Y are considered. The stoichiometry of the extracted complexes has been determined and the extraction constants calculated. Extractability of rare-earth elements decreases from La to Lu. The extractive efficiency and selectivity of butyl(diphenylphosphinylmethyl)phenylphosphinate are compared with those of dibutyl(diphenylphosphinylmethyl)phosphonate and tetraphenylmethylenediphosphine dioxide.