Extraction of Am(III), U(VI), and Pu(IV) from HCl Solutions with Diphenyl(dibutylcarbamoylmethyl)phosphine Oxide

Extraction of Am(III), U(VI), and Pu(IV) from HCl solutions with solutions of diphenyl(dibutylcarbamoylmethyl)phosphine oxide in dichloroethane and m-nitrobenzotrifluoride was studied. The curves of the Am(III) and U(VI) extraction as a function of the acid concentration pass through a minimum at [HCl] = 1 M, followed by a steep ascent at the acid concentration increased further. The logarithmic dependences of the distribution factors on the extractant concentration are nonlinear, with the slope of the upper portions close to 2 for Am(III) and 1 for U(VI). Pu(IV) is extracted noticeably worse than U(VI). A significant anomalous aryl strengthening effect is observed in HCl solutions.     

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.     

[DIALKYLCARBAMOYLMETHYL] PHOSPHINE OXIDES ON THEIR EXTRACTION CAPACITY AND SELECTIVITY

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.     

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

ABSTRACT

The extraction properties of poly-(diphenylphosphinylmethyl) arenes in which the fragments of different methyl substituted aromatic compounds serve as hard bridges connecting the P=0 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 HNO₃, and ligands concentration was investigated. The selectivity of reagents was found to depend only on mutual arrangement of P=0 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.     

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.     

Extraction of Americium and Neodymium from Perchloric and Hydrochloric Acid Solutions with Neat Diphenyl(dibutylcarbamoylmethyl)phosphine Oxide

Interaction of solid diphenyl(dibutylcarbamoylmethyl)phosphine oxide (Ph₂Bu₂) with perchloric and hydrochloric acid solutions was studied. On contact with the acids, this agent forms a liquid substance (liquid reagent, LR) exhibiting extractive power. The conditions of LR formation and extraction of Am(III) from HCl solutions with LR in the absence of organic diluent were studied. The solubility of Ph₂Bu₂ in 3 M HClO₄ is 2.5 mg l^{- 1}. The composition of the LR formed in HClO₄ solutions is 2Ph₂Bu₂·HClO₄·nH₂O. Perchloric acid is quantitatively backwashed from the LR phase with water. Formation of an Nd(III) complex with LR in HClO₄ solutions is accompanied by cementation (solidification) of the compound. The resulting complex has the 3 : 1 [Ph₂Bu₂ : Nd(III)] composition and mp 120°C. According to the IR spectrum, the coordination of Ph2Bu2 with the HClO₄ molecule is monodentate, and with the Nd(III) ion (in the absence of organic diluent) it is bidentate.     

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).