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The history of the development of fluorinated compounds as potential diluents in solvent extraction processes is described. Fluorinated diluents were first investigated in the former Soviet Union and later in the United States and Europe. Fluorinated diluents represent a class of compounds that can be used as primary diluents or as phase modifiers. They are of particular utility when extractant solubility is limited in traditional hydrocarbon diluents and a polar diluent is needed. The chemical and physical characterisitics of fluorinated diluents are provided for a broad range of compounds. Other properties such as toxidcity and resistance to radiolysis are described. Fluorinated compounds have been studied for over 40 years and have been used at industrial scale as a primary diluent for cesium and strontium extraction in Russia and as a phase modifer for an insustrial-scale cesium extraction process in the United States. The advantages and disadvantages of traditional hydrocarbon diluents are compared with chlorinated diluents, chlorinated and fluorinated diluents, and a number of different types of fluorinated diluents. Developing trends for teh use of fluorinated diluents in solvent extraction processes are discussed. This article should provide assistance to researchers investigating new or improved solvent extraction processes where traditional hydrocarbon diluents may not be appropriate. [ABSTRACT FROM AUTHOR]

New non-inflammable compounds – carbonates of fluorinated alcohols were proposed as potential diluents for tributyl phosphate (TBP). These compounds are commercially available, have high boiling point, high density, and low solubility in water solutions. Extraction of actinides from nitric acid by TBP solutions in fluorinated carbonates was studied. TBP solutions in fluorinated carbonates show lower extraction ability comparing with TBP solutions in hydrocarbon diluents. In spite of this, it is possible to extract more than 99.9% of tetra- and hexavalent actinides presented in spent nuclear fuel solutions. The advantage of proposed solvent is possibility to obtain uranium strip product with uranium concentration higher than 100 g/l. [ABSTRACT FROM AUTHOR]

Extraction of actinides from aqueous nitric acid by three different heterocyclic dicarboxamides (2,6-pyridinedicarboxamide, 2,2′-bipyridine-6,6′-dicarboxamide and 1,10-phenanthroline-2,9-dicarboxamides) was studied. It was shown that all studied ligands extract actinides at different oxidation states (U(VI), Np(V), Pu(IV), Am(III), Cm(III)) from acidic solutions. All studied diamides extract Am(III) better than Cm(III). Et(pHexPh)ClPhen contains electron-withdrawing chlorine atoms at the positions 4 and 7 of the phenanthroline moiety (SFAm/Cm = 4-6) and possesses the highest separation factor Am(III)/Cm(III). The studied ligands possess high extraction ability to all actinides present in HLW and therefore they could be used for simultaneous extraction of actinides in the GANEX-type process. [ABSTRACT FROM AUTHOR]

The TcO precipitation with organic complexes of Cu(II) from nitric acid solutions was studied. Complex Cu(phen)(NO) was chosen as the optimal precipitant. The conditions for maximum Tc precipitation of 95 ± 3 % were determined. It was shown the possibility to obtain metal-Tc alloys by thermal treatment of the precipitates. As found, the addition of the fusible metal (Sn) to the sediment was required to receive appropriate matrix. Cu-Tc-Sn matrix was tested for Tc leaching. [ABSTRACT FROM AUTHOR]

Extraction properties of various heterocyclic carboxylic acid amides are considered. The extraction properties of heterocyclic dicarboxylic acid diamides are determined by two major factors: diamide structure and kind of diluent. Among heterocyclic (di)carboxylic acid amides and diamides, the most promising extractants for separating actinides and lanthanides are tri- and tetradentate extractants: diamides of dipicolinic, bipyridinedicarboxylic, and phenanthrolinedicarboxylic acids, which can be used for recovering metals from acid solutions. [ABSTRACT FROM AUTHOR]

The extraction of americium and lanthanides by diamides of 2,2′-dipyridyl-6,6′-dicarboxilic acid solutions in polar diluents was investigated. The dependence of extraction properties of the diamides on their structure was studied and the distribution ratios of americium and lanthanides from nitric acid solutions were determined. The highest extraction was found for the compounds with the ethyl-group and the alkyl-substituted aryl-group on the amidic nitrogen. The Am/Ln separation factors higher than 10 were achieved for extraction from high acidity media. [ABSTRACT FROM AUTHOR]

New diamides of dipicolinic acid have been prepared and their affinity for lanthanides, americium, and uranium has been explored using the liquid-liquid extraction method. These extractants feature mixed alkyl/aryl substituents. The highest extraction is seen for phenyl/ethyl derivatives. The structure-reactivity relationship for extraction and solubility is discussed. [ABSTRACT FROM AUTHOR]

Abstract: New ligands for complexing of the post-transition metals – diamides of 2,2′-bipyridyl-6,6′-dicarboxylic acid were developed, synthesised and characterised. They were proposed to be effective extractants towards americium. The structures of the amides were studied in solid as well as in solution. Theextraction of Am and lanthanides depending on diamide structure, chlorinated cobalt dicarbollide (CCD) – diamide ratio, type of diluent was studied. The optimal conditions for Am/REE separation were determined. The properties of new potentiometric sensors on the base of 2,2′-dipyridyl-6,6′-dicarboxylic acid diamides were studied. The correlation structure vs. properties of ionophores (i.e. extractants), their sensitivity and selectivity in sensor analysis and extraction are discussed. [Copyright &y& Elsevier]

Extraction of nitric acid, perchloric acid, americium, and europium with dialkyldiarylamides of 2,6-pyridinecarboxylic (dipicolinic) acid in polar fluorinated solvents (diluents) was analysed. Among the extractants studied N, N′-diethyl-N, N′-ditolylamide dipicolinate is characterized by the best extraction properties. On passing from nitric to perchloric acid solutions extraction of metals sharply increases. Extraction of americium from nitric acid solutions is significantly greater as compared with europium (separation coefficient reaches 6), whereas extraction of americium and europium from perchloric acid solutions is nearly similar. The effect of diluent on the extraction was analyzed; for different diluents the maximum of extraction from perchloric acid solutions shifts form 3 to 6 M. [ABSTRACT FROM AUTHOR]

Extraction of Am and Eu with N,N′-substituted pyridine-2,6-dicarboxamides in fluorinated diluents was studied. N,N′-Diethyl- N,N′-di( p-tolyl)pyridine-2,6-dicarboxamide (EtTPDA) is readily soluble in fluorinated diluents, and its solutions allow the extraction of TPE and REE from nitric acid solutions. The extraction ability of EtTPDA in fluorinated polar diluents is higher than in CHCl3. In the extraction with EtTPDA, the Am/Eu selectivity is independent of the extractant concentration and decreases with an increase in the acidity of the medium. Americium is extracted with EtTPDA better than Eu, which allows selective recovery of Am at moderate HNO3 concentrations. [ABSTRACT FROM AUTHOR]

The extraction properties of diamide derivatives of dipicolinamide (2,6‐pyridinedicarboxylamide or DPA, (R′R″NCO) 2 C 5 NH 3 ) in mixtures containing chlorinated cobalt dicarbollide in the acid form (HCCD), with and without a substituted polyethylene glycol (PEG), have been investigated. Distribution ratios of Cs, Sr, U, Eu and Am have been measured for various concentrations of diamide, PEG, aqueous phase nitric acid, with various HCCD:diamide ratios, and using different organic diluents. In the absence of HCCD, the diamides show little affinity for the extraction of Am or Eu from nitric acid solutions (distributions typically [ABSTRACT FROM AUTHOR]

Extraction of Am and Eu using mixtures of diphosphinc dioxides (DPDO, e.g., (R1)2P(O)(CH2)nP(O)(R2)2 where R1, R2 = Ph, Bu; n = 1,2), with and without chlorinated cobalt dicarbollide (CCD) in the polar diluents 1,2-dichloroethane (DCE)+ meta-nitrobenzotrifluoride (F-3), bis-tetrafluoropropyl ether of diethylene glycol (F-8) and phenyltrifluoromethyl sulfone (FS-13) from HNO3, HClO4, LiNO3 and LiClO4 solutions has been investigated. The anomalous aryl strengthening (AAS) effect, i.e. the anomalous increase of extraction ability of methylene bridged diphosphine dioxides due to substitution of aromatic (i.e., phenyl) for alkyl (e.g., butyl or octyl) moieties (DAm increases by three to lour orders of magnitude), is only observed during the extraction of Am and Eu from acidic media. In salt media the AAS effect is weakly observed, and is practically absent in such diluents as F-3 and FS-13. The extraction isotherm in the case of DPDO with an observed AAS effect indicates the distribution coefficients of Eu decrease by a factor of two to three, even at the concentration ratio of DPDO:Eu = 50:1; however, these values decrease only by L0% for the DPDO that do not indicate an observed AAS effect. It is proposed that the presence of water in the diluent is necessary for manifestation of the AAS effect. The synergistic effects of adding chlorinated cobalt dicarbollide (CCD) with the DPDO that has been reported for other systems was also found to prevail in several of the systems investigated in this study. On addition of CCD with the DPDO, a considerable synergistic effect is observed (DAm increases by three to four orders of magnitude) during Am and Eu extraction from nitrate media, in perchlorate media the synergistic effect is absent. The most probable reason for synergism in the presence of CCD is the higher... [ABSTRACT FROM AUTHOR]

"Mayak" production association has convincingly demonstrated the possibility of creating a HLW partitioning scheme based on different radical phosphine oxide in heavy fluorinated or chlorinated diluents, including in the presence of tributyl phosphate. The separation system makes it possible to efficiently recover uranium, plutonium, neptunium, REE–TPE, as well as technetium from solutions (up to 2 M) in HNO3 and separate them into at least two fractions: a fraction of trivalent REE/TPE with the bulk of technetium and a fraction of polyvalent actinides. [ABSTRACT FROM AUTHOR]

Extraction of uranium with trifluoromethyl alkyl diketones differing in the length of the alkyl chain was studied. The size of the alkyl group only slightly affects the extraction. Extraction of complexes formed by uranyl nitrate with β-diketones in pentafluoroethane (Freon-125) was studied. The complexes are efficiently extracted with both super- and subcritical Freon-125. In contrast to extraction of these complexes in supercritical CO2, in extraction with Freon-125 the complexes do not decompose. [ABSTRACT FROM AUTHOR]

Results are presented of tests, mastering, industrial exploitation, and optimization of an integrated scheme for fractionation of liquid high-activity wastes (HAWs) produced in processing of spent nuclear fuel (SNF), which includes the extractive recovery of the Cs–Sr with the system based on chlorinated cobalt dicarbollide in a heavy fluorinated diluent and extraction from the resulting raffinates of a group of rtansplutonium and rare-earth elements by the oxalate precipitation method. This was done at Mayak Production Association in 1996–2003. A total of more than 1600 m3 of HAWs that were stored during a long time in storage facilities and contain more than 54 MCi of β- emitters. About 52 MCi of β- and also about 0.5 MCi of α-nuclides were isolated into concentrates and transferred to vitrification. The scale of activities on integrated fractionation of acid HAWs has no analogs in the world. [ABSTRACT FROM AUTHOR]

Problems of the development of potentiometric sensors and multisensor systems for the determination of rare-earth elements in aqueous solutions are considered. The efficiency of the approach to the fabrication of sensors based on the application of substances and regularities used in solvent extraction is shown. Possibilities of multisensor systems for the selective determination of individual lanthanides in complex mixtures are demonstrated. [ABSTRACT FROM AUTHOR]

Extraction of Cs, Sr, Eu, U, Np, and Am with mixtures of dipicolinic acid diamides with chlorinated cobalt dicarbollide was studied. A synergistic effect was revealed. [ABSTRACT FROM AUTHOR]

A CVD process was developed for producing 63Ni-based atomic batteries by deposition of active 63Ni layers onto semiconductor silicon supports. Tetrakis(trifluorophosphine)nickel synthesized from 63Ni metal and phosphorus trifluoride was used as the volatile precursor. The influence of the support temperature and working pressure on the characteristics of the 63Ni coating was examined. [ABSTRACT FROM AUTHOR]

N,N′-Dialkyl-N,N′-diaryl-1,10-phenanthroline-2,9-dicarboxamides (IV) were predicted (DFT simulation) and then were proved experimentally to be efficient donor ligands with high and unusual selectivity for the extraction separation of lanthanides. Distribution coefficients D of lanthanide cations in two-phase aqueous solution–polar organic solvent decrease with increasing Ln3+ atomic number. The selectivity factors SFLn1/Ln2 for adjacent lanthanide ions were found to be about 3. [ABSTRACT FROM AUTHOR]

New ethyltolyl-substituted derivatives of dipicolinic acid,N,N-diethyl-N',N'-ditolyl diamides (DPA) have been synthesized and evaluated for their extraction capability toward americium and lanthanides. These diamides were studied as a stand-alone extractant in conjunction with a polar solvent FS-13 (trifluoromethylphenyl sulfone) as well as in an extraction mixture in conjunction with the synergistic extractant chlorinated cobalt dicarbollide and FS-13. The effect of the ortho-, meta-, and para position of the methyl group on the tolyl ring of theN,N'-diethyl-N,N'-ditolyl-diamide (EtTDPA) was investigated. Data on the extraction ability of different diamides of dipicolinic acid show that the Et(o)TDPA has the most promising properties because it has the best balanced selectivity between the heavy and light lanthanoids. [ABSTRACT FROM AUTHOR]

New polymeric sensors with high sensitivity to cations of transition metals and lanthanides in acid media are suggested. The role of active substances in the polymeric membranes of the sensors is played by diamides of dipicolinic acid with various structures, which are compounds exhibiting a high extraction capacity for various metals. [ABSTRACT FROM AUTHOR]

Three ortho-, meta-, and para-derivates of ethyl(tolyl)diamides of dipicolinic acid were synthesized and tested on their extraction performance from nitric acids solutions. Extraction of americium and lanthanides (Ln) by these compounds as a function of nitric acid concentration was studied. Distribution ratios of studied metals were determined using ICP-OES method and radiotracer 241Am. Am/Ln separation differs among studied diamides, and the best separation was found for N,N'-diethyl-N,N'-di(ortho)tolyl-diamide. [ABSTRACT FROM AUTHOR]

The composition and structure of complexes that are formed in the system consisting of chlorinated cobalt dicarbollide (CCD), polyethylene glycol (PEG), and Sr2+ or Ba2+ in a polar diluent, dichloroethane or phenyl trifluoromethyl sulfone, were studied by IR and NMR spectroscopy. In extraction of Sr2+ and Ba2+ with solutions of [H5O·PEG]CCD-, the organic phase contains the ionic associates [M2+·PEG]CCD. The Sr2+ and Ba2+ complexes have similar composition and structure: The oxygen atoms of two OH groups and six COC groups of a PEG molecule fill the first coordination sphere of the metal ions. Also, no more than two water molecules can be coordinated in the second sphere, forming hydrogen bonds with the hydrogen atoms of two OH groups of PEG. The coordination of the OH groups of PEG with the Sr2+ and Ba2+ ions is preferable over the coordination of the COC groups, as follows from the fact that the extraction of Sr2+ and Ba2+ with CCD-PEG mixtures gets worse on replacement of the OH groups of PEG by other substituents. A considerable increase in the efficiency of Sr2+ and Ba2+ extraction with H-CCD solutions in the presence of PEG is due to the fact that all the H2O molecules in the first coordination spheres of the M2+ ions are replaced by the COC and OH groups of PEG with the formation of a hydrophobic complex [M2+·PEG](H2O)2. [ABSTRACT FROM AUTHOR]

We have predicted earlier by DFT simulation that tridentate O,N,O-donor cyclic dilactams (B) belonging to the family of pyridine-2,6-dicarboxamides are much more selective and efficient extractants for the separation of lanthanides and actinides than open-structure pyridine-2,6-dicarboxamides due to the higher degree of “ligand preorganization”. In the present work, three new ligands of type (B) were synthesized. Extraction experiments showed that, in line with the data from DFT simulation, these ligands have 5–6-fold higher selectivity for the separation of an Am3+/Eu3+ pair and provide distribution coefficients D which are by three orders of magnitude higher than those for the related parent ligands with an open structure. Determination of the solvate numbers (SNs) for Eu3+ and Am3+ cations by slope analysis has shown that the stoichiometry of complexes, in the form of which these ions pass from the aqueous into the organic phase, depends to a considerable extent on the polarity of the organic solvent. Strongly polar solvents (ε ＞ 20) extract these cations mainly in the form of 1 : 1 complexes LM(NO3)3 having according to the DFT simulation the largest dipole moments (μ = 18.6–19.7 D). The solvents of low polarity (ε≤ 10) extract these cations mainly in the form of less polar 2 : 1 complexes L2M(NO3)3 (μ≈ 1.6 D). For solvents of intermediate polarity fractional values of solvate numbers were obtained which indicates the coexistence of complexes LM(NO3)3 and L2M(NO3)3 in the organic phase. [ABSTRACT FROM AUTHOR]

The conditions of pertechnetate ion precipitation with ferroin nitrate in nitric acid solutions were determined. The effect of precipitation condition on the composition and structure of ferroin pertechnetate complexes was analyzed. At aging of the precipitate in the mother liquor the formation of nitrosyl group in the complex was found, which is confirmed by appearance in the IR spectrum of the band at 1700 cm belonging to the coordinated nitrosyl group. Analysis of the IR spectra of ferroin perrhenate and pertechnetate complexes showed that coordinated nitrosyl group is formed only in the presence of technetium in the complex structure. [ABSTRACT FROM AUTHOR]

Solvent extraction of Am(III), Pu(IV) and Eu(III) was done from nitric acid medium using a solvent system containing a substituted dipicolinamide extractant dissolved in room temperature ionic liquid. The solvent system was found to be more efficient as compared to the previously reported solvents in molecular diluents. [ABSTRACT FROM AUTHOR]

The possibility of using the atomic-force microscopy as a method for detection of the analytical signal from plasticized polymeric sensor membranes was analyzed. The surfaces of cadmium-selective membranes based on two polymeric matrices were examined. The digital images were processed with multivariate image analysis techniques. A correlation was found between the surface profile of an ion-selective membrane and the concentration of the ion in solution. [ABSTRACT FROM AUTHOR]

A procedure was developed for determining the gravimetric concentration of Tc in aqueous solutions from spent nuclear fuel reprocessing without their preliminary separation, using an inductively coupled plasma optical emission spectrometer (ICP-OES). The optimal conditions for minimizing spectral and matrix interferences were determined. They allowed the lower limit of Tc determination in process salt solutions to be decreased from 1 to 0.25 mg l. [ABSTRACT FROM AUTHOR]

The procedure was proposed for the synthesis of various dipyridyldiamides. Their various properties in the series of rare-earth elements were studied. The possibility to use the synthe-sized compounds in polymer membranes of electrochemical sensors for the development of novel types of sensors was shown. A comparison of the influence of the ligand structure on the extraction and sensor characteristics was performed. [ABSTRACT FROM AUTHOR]

Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (HB) in the presence of N, N, N′, N′-tetraisobutyl-2,6-dipicolinamide [T(iBu)DPA, L] has been investigated. The equilibrium data have been explained assuming that the species HL, HL, CaL, SrL and SrL are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in nitrobenzene saturated with water have been determined. [ABSTRACT FROM AUTHOR]

Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (HB) in the presence of diphenyl- N,N-dibutylcarbamoylmethyl phosphine oxide (DPDBCMPO, L) has been investigated. The equilibrium data have been explained assuming that the species HL, $$ {\text{HL}}_{2}^{ + } $$, CaL, $$ {\text{CaL}}_{ 2}^{{ 2 { + }}} $$, $$ {\text{CaL}}_{ 3}^{{ 2 { + }}} $$, SrL, $$ {\text{SrL}}_{ 2}^{{ 2 { + }}} $$, $$ {\text{SrL}}_{ 3}^{{ 2 { + }}} $$ and $$ {\text{SrL}}_{ 4}^{{ 2 { + }}} $$ are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in nitrobenzene saturated with water have been determined. In the considered nitrobenzene medium, it was found that the stability constants of the complexes CaL, $$ {\text{CaL}}_{ 2}^{{ 2 { + }}} $$ and $$ {\text{CaL}}_{ 3}^{{ 2 { + }}} $$, where L is DPDBCMPO, are somewhat higher than those of the corresponding complex species SrL, $$ {\text{SrL}}_{ 2}^{{ 2 { + }}} $$ and $$ {\text{SrL}}_{ 3}^{{ 2 { + }}} $$. [ABSTRACT FROM AUTHOR]

Extraction of microamounts of europium and americium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate (H+B−) in the presence of N,N,N′,N′-tetraethyl-2,6-dipicolinamide (TEtDPA, L) has been investigated. The equilibrium data have been explained assuming that the species HL+, $$ {\text{HL}}_{ 2}^{ + } , $$ $$ {\text{ML}_{2}^{3 +}} $$ and $$ {\text{ML}_{ 3}^{ 3+}} $$ (M3+ = Eu3+, Am3+) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in FS 13 saturated with water have been determined. It was found that the stability constants of the corresponding complexes $$ {\text{EuL}}_{n}^{ 3+ } $$ and $$ {\text{AmL}}_{n}^{ 3+ }$$, where n = 2, 3 and L is TEtDPA, in the mentioned FS 13 medium are comparable. [ABSTRACT FROM AUTHOR]

Extraction of microamounts of europium and americium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate (H+B−) in the presence of N, N′-diethyl- N, N′-diphenyl-2,6-dipicolinamide (EtPhDPA, L) has been investigated. The equilibrium data have been explained assuming that the species HL+, HL2 +, ML2 3+, ML3 3+ and ML4 3+ (M3+ = Eu3+, Am3+) are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in FS 13 saturated with water have been determined. It was found that the stability constants of the corresponding complexes EuL and AmL, where n = 2, 3, 4 and L is EtPhDPA, in water-saturated FS 13 are comparable. [ABSTRACT FROM AUTHOR]

Extraction of microamounts of Eu and Am with a nitrobenzene solution of chlorinated hydrogen dicarbollylcobaltate (H+B−) in the presence of N,N′-diethyl- N,N′-diphenyl-2,6-dipicolinamide (EtPhDPA, L) was studied. The equilibrium data were interpreted assuming that the complexes HL+, HL, ML, ML, and ML4/3+ (M3+ = Eu3+, Am3+) are extracted into the organic phase. The extraction and stability constants of the species in water-saturated nitrobenzene were determined. The stability constants of the related complexes EuL and AmL, where n = 2, 3, 4, in this medium are comparable. [ABSTRACT FROM AUTHOR]

The concentration of molybdenum(VI) in dissolved spent nuclear fuel is comparable with the concentrations of Tc, and the minor actinides (Np, Am). Therefore it is of great interest to understand its behavior under conditions imposed by separation processes. The simultaneous extraction ability of ortho, meta, and para isomers of N,N′-diethyl- N,N′-ditolyl-dipicolinamide (EtTDPA) for molybdenum and technetium were investigated in a large range of nitric and hydrochloric acid conditions. Molybdenum shows no increase in extraction at higher concentrations of nitric acid giving a solvate number n=0 with all isomers of EtTDPA, while Mo shows great extractability from HCl. Technetium distribution ratios decrease with increasing concentrations of nitrate showing indication of ion exchange occurring between TcO4 − and NO3 − anions. Et(m)TDPA and Et(p)TDPA show the greatest extractability, with 60% of the total technetium extracted into the organic phase at 1M HNO3. [ABSTRACT FROM AUTHOR]

Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B−) in the presence of N,N,N′,N′-tetraethyl-2,6-dipicolinamide (TEtDPA, L) has been investigated. The equilibrium data have been explained assuming that the cations HL+, HL, ML and ML (M3+ = Eu3+, Am3+) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It has been found that the stability constants of the corresponding complexes EuL and AmL, where n = 2, 3 and L is TEtDPA, in the mentioned medium are comparable. [ABSTRACT FROM AUTHOR]

Synergistic extraction of long-lived fission products 137Cs+, 85Sr2+, and 152Eu3+ from dilute HNO3 into dichloroethane with ligands derived from p-(1-adamantyl)thiacalix[4]arene in mixtures with chlorinated cobalt dicarbollide was studied. An extraordinary synergistic effect is observed in extraction of europium with p-(1-adamantyl)thiacalix[4]arene tetraacetate derivative. Amides of p-(1-adamantyl)thiacalix-[4]arene tetracarboxylic acid are selective toward europium, although their extraction ability toward the examined ions is lower than that of the classical extractant, p-(1-adamantyl)calix[4]arene tetracarboxylic acid diethylamide. [ABSTRACT FROM AUTHOR]

Extraction of Am, Eu, Pd, and Tc from 0.1–3.0 M HNO3 with solutions of phosphorylated calix[ n]arenes in m-nitrobenzotrifluoride (NBTF) was studied. The ring size and position of phosphoryl groups (in the upper or lower rim) affect the extraction of Am and Eu significantly and that of Tc and Pd only slightly. Calix[4]arenes phosphorylated at the upper rim extract Am and Eu considerably better than do their analogs with substituents in the lower rim and substituted calix[6]arenes. Compounds with the phosphoryl group linked to the calixarene core by the methylene bridge show the highest extracting performance. In contrast to monodentate phosphine oxides, in calix[4]arenes the size of the alkyl substituent at the P atom strongly affects the efficiency of extraction of the radionuclides. With a decrease in the length of the alkyl radical in substituents −CH2P(O)Alk2, the distribution ratios of all the radionuclies, as a rule, decrease. With a decrease of Alk in −CH2P(O)PhAlk, the distribution ratios increase for Eu and Am but remain unchanged for Tc and Pd. Calix-arenebis(methylenediphosphonates) with the propoxy substituents at the P atom extract Eu and Am hundreds times more efficiently than do their analogs with methoxy, isopropoxy, and butoxy substituents. The possibility of joint recovery of Am, Eu, Tc, and Pd from nitric acid solutions with calix[4]arenes containing dialkylmethylenephosphine oxide substituents in the upper rim was demonstrated. The prevalent species formed in the extraction of Tc are complexes of the composition M2L. The composition of complexes formed by calix-arenes with Am and Eu depends on the preparation procedure. [ABSTRACT FROM AUTHOR]

A procedure was developed for conversion of spent UNEX solvent into a solid infusible resin, insoluble in aqueous alkali and acid solutions and organic solvents, by condensation with phenol and paraform. Incorporation of phenyl trifluoromethyl sulfone into the resin was confirmed by physicochemical methods. Resistance of the cured resin to high temperatures was proved by thermogravimetry. The developed procedure can also be applied to other organic wastes containing weakly reactive aromatic compounds such as nitrobenzotrifluoride, 1,2-dichlorobenzene, and nitrobenzene. [ABSTRACT FROM AUTHOR]

A variety of novel sensing materials on the basis of phosphine oxides for solvent polymeric sensors have been developed and studied. It was found that phosphine oxide sensors exhibit good sensitivity to rare earth metal cations, such as La3+, Pr3+, Nd3+, Eu3+ and also to Y3+. Polymeric sensors can be comprised into electronic tongue sensor arrays that may allow detection of several rare-earth metal ions simultaneously in mixed solutions. Such sensor arrays are highly promising for environmental and industrial sensing, e.g., for analysis of spent nuclear fuel. [ABSTRACT FROM AUTHOR]

Scientists at the Idaho National Laboratory (INL) and Khlopin Radium Institute (KRI) collaboratively developed and validated the concept of a Universal Extraction (UNEX) process for simultaneously removing the major radionuclides (Cs, Sr, actinides, and lanthanides) from acidic radioactive waste in a single solvent extraction process. The process chemistry is unique and complicated, since the extractants, chlorinated cobalt dicarbollide (CCD), polyethylene glycol (PEG), and diphenyl- N,N-di-n-butylcarbamoylmethylphosphine oxide (Ph2CMPO), operatesynergistically to extract the major radionuclides.A combination of classical chemistry techniques, infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy were utilized to identify and explain the structures formed in the organic phase with protons or metal ions. Model systems, CCD-PEG and CCD-bidentate organophosphorus compounds were studied and possible structures of complexes, existing in the organic phase, are proposed and properties of the UNEX extractant are discussed. [ABSTRACT FROM AUTHOR]

The radiation stability of UNEX stripping solutions containing water, methylamine carbonate, nitrilotriacetic acid, and metal salts was experimentally studied. The decomposition of the methylamine carbonate and nitrilotriacetic acid under gamma irradiation (dose: 0.29 kGy) is lower than 0.5 molecules per 100 eV or about 7.2E-04% and 0.047%, respectively. The decomposition products do not adversely affect the UNEX process up to a 3 MGy absorbed dose. The stripping solutions can be regenerated and reused. [ABSTRACT FROM AUTHOR]

Extraction and sorption recovery of Pd from nitric acid solutions with extractants containing carbamoyl phosphine oxides (CMPO) was studied. The Pd distribution coefficients under different extraction conditions were determined. The possibility of Pd recovery in the course of spent nuclear fuel processing was demonstrated. A number of solid extractants composed of carbamoyl phosphine oxides and inert matrices (styrene-divinylbenzene polymer and silica gel) were tested. The Pd distribution coefficients in the course of sorption and desorption under the static and dynamic conditions were measured. [ABSTRACT FROM AUTHOR]

A synergistic extraction mixture containing chlorinated cobalt dicarbollide (CCD), polyethylene glycol (PEG), and diphenyl-N,N-dibutylcarbamoyl phosphine oxide (CMPO) in a suitable polar diluent is being developed for the simultaneous recovery of Cs, Sr, and the actinides from highly acidic radioactive wastes. Development of this UNEX process was by a successful collaboration between scientists from the Idaho National Engineering and Environmental Laboratory (INEEL) and the Khlopin Radium Institute (KRI) in St. Petersburg, Russia. Development efforts focused on the treatment of radioactive waste currently stored at the INEEL. The development of the UNEX process has and continues to be an evolutionary process. Numerous countercurrent flowsheet demonstrations have been conducted to date, including two tests with several liters of actual radioactive tank waste, one test with dissolved radioactive calcine, and several tests with surrogate INEEL tank and dissolved calcine wastes. All countercurrent flowsheet tests have been performed in banks of centrifugal contactors. Removal efficiencies of 99.95% for 137Cs, 99.995% for 90Sr, and 99.96% for total α (predominately 241Am, 238Pu, and 239Pu) were observed in countercurrent tests with samples of actual INEEL tank waste. The evolutionary concepts included in the development of the UNEX process are discussed, including development of the current diluent, phenyltrifluoromethyl sulfone, to replace nitroaromatic diluents used in earlier studies. Results from the most recent countercurrent flowsheet testing with 1.2 L of actual dissolved INEEL calcine are also presented, which represents the current state of UNEX development. Finally, future research directions in the development and understanding of the UNEX process are discussed. [ABSTRACT FROM AUTHOR]

A fission product solvent extraction technology for the simultaneous extraction of Cs and Sr from acidic tank waste has been developed as a collaborative effort of the Idaho National Engineering and Environmental Laboratory (INEEL) and the Khlopin Radium Institute in St. Petersburg, Russia. The process is being developed as a potential method for treating the current five million liter inventory of acidic tank waste stored at the INEEL. The fission product extraction process is based on an immiscible organic phase comprised of chlorinated cobalt dicarbollide (CCD, Cs extractant) and polyethylene glycol (PEG, Sr extractant) dissolved in a poly-fluorinated sulfone diluent. Batch contact experiments and preliminary flowsheet testing were used to define potential solvent composition and flowsheet configuration. This information was used to specify an initial flowsheet for countercurrent testing with simulated tank waste using a 3.3-cm diameter centrifugal contactor pilot plant at the INEEL. The initial extractant composition was 0.08 M CCD, 0.6 vol% PEG-400 in a phenyl trifluoromethyl sulfone (FS-13) diluent. Approximately 1.5 L of solvent was used (with continuous recycle) to treat 43 L of simulated tank waste during 75 hr of continuous operation. Greater than 99.992% of the Sr and 97.45% of the Cs were extracted from the simulated tank waste and recovered in the strip product. The matrix components Ba (>99.6%), Pb (99.8%), and Ca (10.6%) were also extracted from the simulated tank waste and recovered in the strip product. Less than 1% of the K, Na, Fe, Zr, and Mo were extracted from the tank waste simulant. Finally, none of the analytically determined waste components were observed to build up in the organic solvent. [ABSTRACT FROM AUTHOR]

A teritiary solvent containing chlorinated cobalt dicarbollide, polyethylene glycol and diphenylcarbamoylmethylphosphine oxide was evaluated in different non-nitroaromatic diluents for the separation of cesium, strontium, actinides and rare earth elements from acidic liquid radioactive waste. Decontamination factors of >95% for Cs, 99.7% for Sr, and 99.99% for actinides were achieved in four successive batch contacts using actual radioactive waste. Pilot plant testing in centrifugal contactors using simulated wastes, has demonstrated removal of >99% of all targeted ions. [ABSTRACT FROM AUTHOR]

Conversion of UO2 into uranyl nitrate in liquid N2O4 in the presence of water was studied. The completeness of conversion of oxides in spent nuclear fuel (SNF) into nitrates is determined by the temperature and reagent ratio. The conversion of uranium oxides is complete in 2–6 h at 70–120°C and molar ratio [UO2]: [N2O4]: [H2O] = 1: (2–4): (6–8). The conversion of real oxide SNF (RBMK, 14–20 GW day/t U) in a mixture of liquid CO2 and NO2 was carried out. [ABSTRACT FROM AUTHOR]