Neptunium compounds using

All isotopes of neptunium are highly radioactive and are hazardous and thus need to be carefully used in controlled laboratory settings. These isotopes as well as neptuniums compounds are radioactive poisons. 

Protactinium-233 and neptunium-239 diphthalocyanines are prepared from the corresponding thorium-232 and uranium-238 diphthalocyanines by element transformation [6]. The existence of Pa and Np di-Pcs is proven by repeated sublimation of the irradiated parent compounds using platinum gauze to retain the impurities. Neptunium di-Pc is also synthesized on the tracer scale from irradiated uranium metal, using the normal synthetic method for uranium di-Pc (Example 29) [6], Other actinide phthalocyanines are reported [107-114], Their structures, as well as those of 200 metal phthalocyanines and their derivatives, are classified in an excellent recent review [115]. More recent experimental data on actinide phthalocyanines are absent in the available literature. 

AnXe species are known for fluorides of uranium, neptunium, and plutonium and for UCle. The hexafluorides are volatile compounds obtained by fluorinating Anp4. The highly volatile UFs is the compound used for the large-scale isotope separation of from UCle can be made by the reaction of AICI3 and UFe. The hexa-halides have octahedral geometry. 

Several preparative methods do not use elemental mixtures. Group IIA-Pt intermetallic compounds have been prepared by reacting platinum metal with the group-IIA oxide under hydrogen or ammonia at 900-1200 C. Beryllium metal reacts with neptunium fluoride under vacuum at 1100-1200°C to form BC 3Np. 

Fluorine is used in the separation of uranium, neptunium and plutonium isotopes by converting them into hexafluorides followed by gaseous diffusion then recovering these elements from nuclear reactors. It is used also as an oxidizer in rocket-fuel mixtures. Other applications are production of many fluo-ro compounds of commercial importance, such as sulfur hexafluoride, chlorine trifluoride and various fluorocarbons. 

The most widely used neutral extractants, however, are the organophosphoms compounds, of which the ester, TBP, is the most important. TBP forms complexes with the actinide elements thorium, uranium, neptunium, and plutonium by bonding to the central metal atom via the phosphoryl oxygen in the structure... 

These compounds, tested in NPHE at Cadarache, were used as reference compounds for the extraction of actinides by functionalized calixarenes (see below). The distribution ratios for neptunium mainly at the oxidation state (V), plutonium at the oxidation state (IV), and americium (III) are shown in Table 4.21 for OOCMPO. They were also used as references for the americium over europium selectivity (Table 4.22). 

Extraction of neptunium, plutonium, and americium from simulated radioactive liquid waste was carried out in particular with tert-butyl and dealkylated tetramers, hexamers, and octamers of calixarene [ethoxy(diphenylphosphine oxide)]. Among these six calixarenes, the highest distribution ratios were obtained with the dealkylated calix[8]arene. Using a different sample of the dealkylated hexamer, the Strasbourg group concluded that this compound is the most efficient. This discrepancy can be explained by the presence of impurities, detected by NMR, which were probably responsible for the poor performances of the dealkylated hexamer tested at Cadarache. 

Although PUCI4 has been well characterized in the gas phase (51) in the temperature range 670-1025 K, all attempts to obtain tTiTs compound in the solid state have failed. Use of a plot of the difference AHf(MCl4,c) - AHf(M , aq) (, 8) as a function of the actinide ionic radii ( ) (as done above for PuFa) in the case of thorium, protactinium, uranium and neptunium yields a first path leading to aH (PuC14,c). A second path involves the extrapolation to the plutonium system of the difference AH5o n( C 4 ) ... 

Np (V) (3) and Pu (V) (8), the last two being the first non-oxygenated neptunium (V) and plutonium (V) compounds. Some of the preparative procedures used for uranium (V) fiuoro complexes are shown in Table IV. 

A variety of methods have been used to characterize the solubility-limiting radionuclide solids and the nature of sorbed species at the solid/water interface in experimental studies. Electron microscopy and standard X-ray diffraction techniques can be used to identify some of the solids from precipitation experiments. X-ray absorption spectroscopy (XAS) can be used to obtain structural information on solids and is particularly useful for investigating noncrystalline and polymeric actinide compounds that cannot be characterized by X-ray diffraction analysis (Silva and Nitsche, 1995). X-ray absorption near edge spectroscopy (XANES) can provide information about the oxidation state and local structure of actinides in solution, solids, or at the solution/ solid interface. For example, Bertsch et al. (1994) used this technique to investigate uranium speciation in soils and sediments at uranium processing facilities. Many of the surface spectroscopic techniques have been reviewed recently by Bertsch and Hunter (2001) and Brown et al. (1999). Specihc recent applications of the spectroscopic techniques to radionuclides are described by Runde et al. (2002b). Rai and co-workers have carried out a number of experimental studies of the solubility and speciation of plutonium, neptunium, americium, and uranium that illustrate combinations of various solution and spectroscopic techniques (Rai et al, 1980, 1997, 1998 Felmy et al, 1989, 1990 Xia et al., 2001). 

Neptunium and its compounds of neptunium have been made for research purposes. They are used in specialized detection devices and in nuclear reactors. Neither the element nor its compounds have any commercial uses. 

The ni3(P04)4 and U3(P04)4 phosphates were first characterized in 1957-1963 [15-18] as isostructural compounds with monoclinic unit cells, space group P2, or Pm, or P2 m. More recently, the data were critically revised in a number of papers [8,19-24], where the authors used new methods of studying solids, and carried out detailed experiments on the phase formation in the systems Th02 -P2O5 and UO2 - P2O5. In the authors opinion [8,19-24], attempts to synthesize single phase products such as "M3(P04)4" for both thorium and uranium [15-18] failed. This was also the case for the compounds of similar stoichiometry with neptunium (IV) and plutonimn (IV) [19, 24],... 

Pentavalent neptunium forms with monopyridinecarboxylic acids (picolininc, nicotinic, isonicotinic) solid complexes of different compositions. For picolinic acid, solid compounds with Np Pic ratio from 1 1 to 1 3 were synthesized and characterized using X-ray single crystal crystallography [101]. For nicotinic and isonicotinic acids only 1 1 complexes were obtained. In all cases heterocyclic nitrogen atom participates in the formation of coordination bonds with metal atom. 

Although the existence of a volatile higher fluoride of plutonium had been surmised from tracer experiments, positive evidence of the existence of PuF6 was obtained by Florin (31) who first prepared the compound. An investigation of the preparation and properties of PuF6 was also conducted by Mandleberg et al. (58). but in recent years the compound has been most intensively studied by Weinstock and his collaborators. Plutonium hexafluoride can be prepared by a variety of procedures similar to those used for the preparation of uranium hexafluoride. The most widely used method consists in the fluorination of plutonium tetrafluoride with elemental fluorine. Whereas uranium hexafluoride can be prepared by the analogous reaction at 300°, and neptunium hexafluoride at 500°, the preparation of plutonium hexafluoride by this reaction appears to require a... 

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