M.K. Chmutova

[DIALKYLCARBAMOYLMETHYL] PHOSPHINE OXIDES ON THEIR EXTRACTION CAPACITY AND SELECTIVITY

ABSTRACT Extraction of Am ( III), Pu( IV), U( VI) from nitric acid solutions by dialkyl ( aryl) [ dialkylcarbamoylmethyl] phosphine oxides of different structures has been studied. The nature of substituents at phosphorus and nitrogen atoms and in methylene bridge affects extraction capacity, solubility and selectivity of reagents. The increase in extraction capacity of reagents with respect to Am, U, Pu and decrease in solubility and selectivity at consecutive replacement of alkyl-( or alkoxy-) radicals at phosphorus atom by phenyl ones was found. The advantage of reagents usage with two different radicals one of which is phenyl at phosphorus atom has been shown. The nature of substituent at nitrogen atom affect solubility but does not practically affect extraction capacity of reagent.

Polydentate neutral organophosphorus compounds as extractants of transplutonium elements

Abstract Solvent extraction of 241Am, 244Cm, 249Bk, 252Cf, 253Es, 152–154Eu and 233U from 1 to 15 M HNO3 solutions by a number of polydentate neutral organophosphorus compounds has been studied. The effect of the reagents structure on their extraction capacity, and selectivity has been investigated. Extraction by tetraphenylmethylenephosphine dioxide, which proved to be the best reagent studied, has been studied in detail. It is shown that this compound may be used for quantitative group extraction and concentrating of transplutonium elements from 1 to 15 M HNO3 and from nitrate solutions of arbitrary concentration and acidity.

POLY-(DIPHENYLPHOSPHINYLMETHYL)ARENES - NEW ORGANOPHOSPHORUS EXTRACTANTS OF TRANS-PLUTONIUM ELEMENTS

The extraction properties of poly-(diphenylphosphinylmethyl)arenes in which the fragments of different methyl substituted aromatic compounds serve as hard bridges connecting the P=O functional groups was studied. The extraction of trivalent transplutonium elements and rare earth elements, uranium(VI), plutonium(IV) by chloroform solutions of these reagents as function of HNO/sub 3/ and ligands concentration was investigated. The selectivity of reagents was found to depend only on mutual arrangement of P=O groups in the bridge regardless of their number. Conformational analysis of the reagents described have been used to establish their structure and cause of their selectivity with respect to one or another element. 8 figures, 2 tables.

Extraction of Am(III), Eu(III) and U(VI) from perchloric acid and mixtures of acids by dialkyl-(diaryl) [diethylcarbamoylmethyl] phosphine oxides

ABSTRACT Extraction of Am(III), Eu(III) and U(VI) from perchloric acid solutions by dialkyl(diaryl) [diethyl-carbamoy line thy 1 ] phosphine oxides (CMPO) has been investigated. It has been shown that elements are extracted more effectively from perchloric acid solutions than from nitric acid. An “anomalous aryl effect” increases sufficiently in perchloric media as compared with nitric media. Solvate numbers of elements also increase in perchloric acid, they being extremely high for aryl-substituted reagents and not so high for alkyl-substitu-ted compounds. It has been shown that in HNO9 and HCl04 solutions the value of “anomalous aryl effect” directly depends on the difference in values of element solvate numbers in complexes with aryl- and alkyl-substituted CMPO. Am(III), Eu(III) and U(VI) are not practically extracted from phosphoric and sulphuric acids by CMPO solutions The influence of HCl04 concentration on element extraction from different acid solutions has been studied; a ...

CORRELATION ANALYSIS OF ARYLIC STRENGTHENING OF THE EXTRACTION CAPACITY OF BIDENTATE ORGANOPHOSPHORUS EXTRACTANTS

This paper is devoted to the so-called effect of “anomalous arylic strengthening” (AAS) observed upon extraction of a series of elements, mainly actinides and lanthanides, by bidentate neutral organophosphorus compounds (BNOPC). This “anomalous” effect is an increase in the extraction capacity of a reagent when alkyl substituents at the phosphorus atom are replaced with more electronegative aryl groups. The influence of phenyl substituents at the phosphorus atom on the reactivity of organophosphorus compounds of various types was considered. Based on the data on electronic effects of substituents, hypotheses were formulated about the reasons for AAS involving phenyl groups that are biphilic because they have substituents capable of manifesting both donor and acceptor properties depending on several factors such as,e.g., the nature of the reaction center, the character of the attacking reagent, the nature of the solvent,etc. When a strong complex of a metal with a phenyl substituted reagent of BNOPC is formed during extraction, the phenyl groups become donating, and additional strengthening of the complex appears.

Solvent extraction of transplutonium elements by the mixtures of tri-n-octylamine with neutral extractants from nitrate solutions

Abstract Using 241Am, 244Cm, 250–252Cf and 152Eu the solvent extraction of the trivalent transplutonium elements and europium from nitrate solutions into mixtures of tri-n-octylamine (TOA) with tri-n-butyl phosphate (TBP) and other neutral extractants in different solvents has been studied. A synergistic effect has been found for mixtures of TOA with TBP, tri-n-octylphosphine oxide and triphenylphosphine oxide. The influence of different factors on the synergistic effect are mixtures of with TBP has been studied. Possible reasons for the synergistic effect are discussed. The authors suggest that the effect is due to the formation of mixed anionic complexes of the metals containing coordinated TBP molecules and NO3−-groups.

Oxides of dialkyl(diaryl)[dialkylcarbamoylmethyl]phosphines

Conclusions1.Oxides of dialkyl(diaryl)[dialkylcarbamoylmethyl]phosphines have been synthesized and characterized.2.The character of the substituents on the phosphorus atom substantially influences the extraction properties of the compounds obtained with respect to Am(III), the p-phenyl-substituted derivatives being most effective.

Extraction of Actinides from HNO3 Solutions with Solutions of Dialkyl Methylphosphonates

Extraction of actinides with dialkyl methylphosphonates was studied with the aim to find a compromise between the use of highly effective but expensive chemicals, on the one hand, and weakly effective but cheap and readily available chemicals, on the other hand, and also to find possible ways of utilization of methylphosphonic dichloride, which is the starting substance in syntheses not only of dialkyl methylphosphonates, but also of chemical weapons. In systems with 3 M HNO3 as the aqueous phase and a solution of tributyl phosphate (TBP), diisoamyl methylphosphonate (DIAMP), or bidentate diphenyl(carbamoylmethyl)phosphine oxide (Ph2Bu2) in dichloroethane as organic phase, at equal concentrations of the organophosphorus compounds, the distribution coefficients of Am(III) increase in the order TBP <; DIAMP < Ph2Bu2 in a proportion of 1 : 50 : 5 × 104. Mixtures of dialkyl methylphosphonates and acidic phosphonates show a synergistic effect, which, however, can be utilized only at [HNO3] > 0.1 M and [HIAMP] < 1.5 M (HIAMP is isoamyl hydrogen methylphosphonate).

Extraction of Americium(III) from Nitric Acid Solutions with Neat Diphenyl(dibutylcarbamoylmethyl)phosphine Oxide in the Presence of Metal Salts

Extraction of Am(III) from nitric acid solutions with a liquid complex of diphenyl(dibutylcarbamoylmethyl)phosphine oxide (Ph2Bu2) with nitric acid as influenced by concentration of Al, Ca, Na, Ni, Co, Cr, Fe, Zr, and Mo nitrates was studied. Nonextractable (Al, Ca, Na) and poorly extractable (Ni, Co, Cr) nitrates at their widely varied concentration do not interfere with the exhaustive extraction of americium from 3 M HNO3. These salts facilitate both formation of the extraction-active liquid phase on contact of Ph2Bu2 with 1 M HNO3 and exhaustive extraction of americium from the acid. Extraction of Fe(III) at its widely varied concentration insignificantly interferes with extraction of americium, but this effect increases with increasing acidity and phase contact time. Americium is extracted with a powdered reagent from 0.1 M HNO3 when liquid extractant is not formed in the visible amounts. In extraction of americium from weakly acidic solutions in the presence of salts the solid reagent, apparently, partially transforms into the liquid extractant, and two different extraction mechanisms are operative. It was shown that the neat liquid complex of Ph2Bu2 with HNO3 can be used for exhaustive extraction of americium from high-level saline wastes from plants for processing nuclear fuel.

Solid-Phase Extraction of Eu(III) and Am(III) with Synergistic Mixtures of Extractants

Solid-phase extraction (SPE) of Eu(III) and Am(III) in systems containing a chelating agent and a neutral electron-donor compound was studied. In the systems 1-phenyl-3-methyl-4-benzoylpyrazol-5-one-tetraphenylmethylenediphosphine dioxide and 1-phenyl-3-methyl-4-benzoylpyrazol-5-one-trioctylphosphine oxide, the distribution factors of Eu(III) and Am(III) showed a synergistic effect owing to adduct formation.