Extraction and sorption preconcentration of U(VI), Am(III), and Pu(IV) from nitric acid solutions with alkylenediphosphine dioxides

The extraction of U(VI), Am(III), and Pu(VI) from nitric acid solutions in the form of complexes with alkylenebis(diphenylphosphine) dioxides and their sorption with POLIORGS F-6 sorbent prepared by noncovalent immobilization of methylenebis(diphenylphosphine) dioxide (MDPPD) on a KhAD-7M? polymeric matrix were studied. The preconcentration conditions and distribution coefficients of U(VI), Am(III), and Pu(IV) in their sorption from 3 M HNO₃ were determined. The possibility of concentrating actinides from multicomponent solutions was demonstrated. The composition and nature of complexes of U(VI) with MDPPD were determined from the ³¹P NMR data.     

Radiation resistance of a series of organophosphorus extractants

Extraction of U(VI), TUE, and REE from acid process solution with solutions of mono-and bidentate neutral organophosphorus compounds (NOPCs), phenyloctyl(N,N-diisobutylcarbamoylmethyl)phosphine oxide (CMPO), 2-ethylhexyl (N,N-dibutylcarbamoylmethyl)phenylphosphinate (CMPP), and unsymmetrical phosphine oxide (UPO) was studied as influenced by γ-irradiation at different absorbed dose rates. In all cases extraction of the target radionuclides decreased with increasing absorbed dose of γ-radiation. The resistance of the NOPCs to radiolysis decreases as CMPO>CMPP>UPO owing to the difference in the structures of their molecules.     

Phosphoryl-Containing Chelating Sorbents for Concentrating Actinides

New chelating sorbents with phosphinate, carbamoylmethylphosphinate, and methylenediphosphine dioxide functionalities are synthesized by chemical and noncovalent binding of the ligands to polymer matrices, chloromethylated styrene copolymer and XAD-7 acrylate polymer. The sorption and kinetic characteristics of the sorbents with respect to U(VI), Th(IV), Pu(IV), and Am(III) are studied in nitric acid solutions. The sorbents obtained by noncovalent binding of the ligands to XAD-7 demonstrate better kinetic properties. The sorbents can be used for concentrating actinides from 3–5 M HNO₃ and for their partitioning.     

Efficiency of different methods for removing U,Th, and K from a liquid scintillator

The efficiency of removing U and Th from a liquid organic scintillator based on linear alkylbenzene (LAB) by stripping with a 0.02 M aqueous solution of aminomethylenediphosphonic acid and by sorption on aluminum oxide and silica gel was studied. A procedure was developed for purification of scintillation additives (2,5-diphenyloxazole, 2-biphenyl-5-phenyloxazole, p-terphenyl) to remove ⁴⁰K.     

Extraction of f Elements and Technetium from HNO3 Solutions with Solutions of Alkyl (N,N-Diethylcarbamoylmethyl)phenylphosphinates

Phosphinic acid derivatives, alkyl (N,N-diethylcarbamoylmethyl)phenylphosphinates (ADPs) were synthesized, studied, and tested as extractants for f elements and technetium at the Mayak Production Association. The distribution factors of these elements D were studied in relation to the ADP and HNO₃ concentrations. The influence exerted by the structure of the alkoxy group at the P atom on DAm and DEu in extraction of Am(III) and Eu(III) (chosen as examples) from nitric acid solutions with solutions of ADPs in dichloroethane was examined. The differences between the distribution factors of Am(III), Pu(IV), U(VI), and Tc(VII) are sufficiently high for complete separation of these elements with a high degree of purification in one step of extraction with ADP solutions. The changes observed in the IR spectrum of the 2-ethylhexyl ADP upon complexation with Pr(III) suggest high complexing power of this reagent toward lanthanide ions. The spectrometric data suggest bidentate coordination of the metal with the chelating groups of the reagent.     

A procedure for removing uranium,thorium, and potassium-40 microimpurities from a liquid organic scintillator based on linear alkylbenzene

A procedure was developed for removing uranium, thorium, and potassium from a liquid organic scintillator based on linear alkylbenzene (LAB) by stripping with water. The volume ratio of the scintillator and water in the process should be no less than 1: 5. The attenuation length (L₄₂₀) of LAB after treatment with water does not change and is as high as 13.0 ± 1.8 m. The solubility of water in LAB and of LAB in water was determined to be 46 and 5.1 ppm, respectively.