Actinide plutonium

The actinides plutonium, neptunium, protoactinium, and thorium (151,173) bind to transferrin. The larger Th4+ ion (radius, 0.94 A) still binds to both sites, although binding to the second site (probably the N-terminal site) is significantly weaker than that to the first and apparently involves only one Tyr ligand compared with two Tyr in the other (151). Although UV difference spectra for Pu4+ are equivocal (174), it seems likely that two Pu4+ are bound. The likely carrier properties of transferrin for Pu4+ makes the design of competitive chelators of some importance (151). 

Of the actinides, plutonium is potentially a particularly dangerous biological hazard because of the chemical and biological similarities between Pu(IV) and Fe(III). With this similarity in mind, a series of tetracatechol ligands with both linear and cyclic tetramines as backbone were synthesized in accordance with the general scheme outlined above 24,118) (see Fig. 7a and b). The eight-coordinate nature of Pu(IV)... 

The heavier elements (transactinides), Z=104 (1969) through 106 (1974) were produced in heavy-ion accelerators by bombardment of heavy actinide (plutonium-californium) targets with light ions (carbon, boron, neon, oxygen), so called hot-fiision reactions. The institutions involved in the production of these elements were the LBNL (USA) and the JINR (Russia) (see Ref. 31 for a review). 

Studies of the immobilization behavior of Cd, Cr, and V in the cement matrices shown above revealed that (i) Cd is effectively retained in all cements and shows no sensitivity to the leachate pH and (ii) both NMLs of Cr and V are maximized at intermediate levels of alumina in the cement matrix and minimized at high and low alumina contents, presumably related to the amphoteric nature of Al (Heimann et al, 1992 Ivey et al, 1990). Multicomponent systems tests of the interaction of cement and radioactive waste forms (used UO2 fuel, fuel recycle waste glass) have provided evidence that actinides (plutonium 239 -1- 240, americium 241, curium 244) would be efficiently adsorbed onto cement (Heimann, 1988a), presumably related to the presence of apatite structures (Beall and Allard, 1982). 

Bourges G, Lambertin D, Rochefort S, Delpech S, Picard G (2006) In 4th topical conference on plutonium and actinides/plutonium futures—the sciatce 2006, Elsevier Science Sa, Pacific Grove, CA, pp 404 09... 

Desire, Hussonnois and GuUlaumont (1969) determined stability constants for the species AnOH + for the actinides, plutonium(III), americium(III), curium (III), berkelium(III) and californium (III) using a solvent extraction technique. The stability constants obtained for americium(III) and curium(III) are two orders of magnitude larger than other similar data available in the literature. The stability constants of the lanthanide(III) and actinide(III) ions are very difficult to obtain using solvent extraction due to problems associated with attainment of maximum extraction into the solvent phase before the narrow band of pH between the onset of hydrolysis reactions and the precipitation of solid hydroxide phases. Consequently, the data of Desire, Hussonnois and GuUlaumont (1969) are not retained in this review. 

The many possible oxidation states of the actinides up to americium make the chemistry of their compounds rather extensive and complicated. Taking plutonium as an example, it exhibits oxidation states of -E 3, -E 4, +5 and -E 6, four being the most stable oxidation state. These states are all known in solution, for example Pu" as Pu ", and Pu as PuOj. PuOl" is analogous to UO , which is the stable uranium ion in solution. Each oxidation state is characterised by a different colour, for example PuOj is pink, but change of oxidation state and disproportionation can occur very readily between the various states. The chemistry in solution is also complicated by the ease of complex formation. However, plutonium can also form compounds such as oxides, carbides, nitrides and anhydrous halides which do not involve reactions in solution. Hence for example, it forms a violet fluoride, PuFj. and a brown fluoride. Pup4 a monoxide, PuO (probably an interstitial compound), and a stable dioxide, PUO2. The dioxide was the first compound of an artificial element to be separated in a weighable amount and the first to be identified by X-ray diffraction methods. 

Planet pluto) Plutonium was the second transuranium element of the actinide series to be discovered. The isotope 238pu was produced in 1940 by Seaborg, McMillan, Kennedy, and Wahl by deuteron bombardment of uranium in the 60-inch cyclotron at Berkeley, California. Plutonium also exists in trace quantities in naturally occurring uranium ores. It is formed in much the same manner as neptunium, by irradiation of natural uranium with the neutrons which are present. 

The actinide elements are a group of chemically similar elements with atomic numbers 89 through 103 and their names, symbols, atomic numbers, and discoverers are given in Table 1 (1-3) (see Thorium and thorium compounds Uranium and uranium compounds Plutonium and plutonium compounds Nuclear reactors and Radioisotopes). 

Each of the elements has a number of isotopes (2,4), all radioactive and some of which can be obtained in isotopicaHy pure form. More than 200 in number and mosdy synthetic in origin, they are produced by neutron or charged-particle induced transmutations (2,4). The known radioactive isotopes are distributed among the 15 elements approximately as follows actinium and thorium, 25 each protactinium, 20 uranium, neptunium, plutonium, americium, curium, californium, einsteinium, and fermium, 15 each herkelium, mendelevium, nobehum, and lawrencium, 10 each. There is frequently a need for values to be assigned for the atomic weights of the actinide elements. Any precise experimental work would require a value for the isotope or isotopic mixture being used, but where there is a purely formal demand for atomic weights, mass numbers that are chosen on the basis of half-life and availabiUty have customarily been used. A Hst of these is provided in Table 1. 

Thorium, uranium, and plutonium are well known for their role as the basic fuels (or sources of fuel) for the release of nuclear energy (5). The importance of the remainder of the actinide group Hes at present, for the most part, in the realm of pure research, but a number of practical appHcations are also known (6). The actinides present a storage-life problem in nuclear waste disposal and consideration is being given to separation methods for their recovery prior to disposal (see Waste treati nt, hazardous waste Nuclear reactors, waste managet nt). 

Table 6 presents a summary of the oxidation—reduction characteristics of actinide ions (12—14,17,20). The disproportionation reactions of UO2, Pu , PUO2, and AmO are very compHcated and have been studied extensively. In the case of plutonium, the situation is especially complex four oxidation states of plutonium [(111), (IV), (V), and (VI) ] can exist together ia aqueous solution ia equiUbrium with each other at appreciable concentrations. 

A number of organic compounds, eg, acetylacetone [123-54-6] and cupferron [135-20-6] form compounds with aqueous actinide ions (IV state for reagents mentioned) that can be extracted from aqueous solution by organic solvents (12). The chelate complexes are especially noteworthy and, among these, the ones formed with diketones, such as 3-(2-thiophenoyl)-l,l,l-trifluoroacetone [326-91-0] (C4H2SCOCH2COCF2), are of importance in separation procedures for plutonium. 

The primary issue is to prevent groundwater from becoming radioactively contaminated. Thus, the property of concern of the long-lived radioactive species is their solubility in water. The long-lived actinides such as plutonium are metallic and insoluble even if water were to penetrate into the repository. Certain fission-product isotopes such as iodine-129 and technicium-99 are soluble, however, and therefore represent the principal although very low level hazard. Studies of Yucca Mountain, Nevada, tentatively chosen as the site for the spent fuel and high level waste repository, are underway (44). 

Actinide Peroxides. Many peroxo compounds of thorium, protactinium, uranium, neptunium, plutonium, and americium are known (82,89). The crystal stmctures of a number of these have been deterrnined. Perhaps the best known are uranium peroxide dihydrate [1344-60-1/, UO 2H20, and, the uranium peroxide tetrahydrate [15737-4-5] UO 4H2O, which are formed when hydrogen peroxide is added to an acid solution of a uranyl salt. 

Plutonium [7440-07-5] Pu, element number 94 in the Periodic Table, is a member of the actinide series and is metaUic (see Actinides and transactinides). Isotopes of mass number 232 through 246 have been identified. AH are radioactive. The most important isotope is plutonium-239 [15117-48-3] Pu also of importance are Pu, Pu, and Pu. 

Nuclear Waste Reprocessing. Liquid waste remaining from processing of spent reactor fuel for military plutonium production is typically acidic and contains substantial transuranic residues. The cleanup of such waste in 1996 is a higher priority than military plutonium processing. Cleanup requires removal of long-Hved actinides from nitric or hydrochloric acid solutions. The transuranium extraction (Tmex) process has been developed for... 

W. N. Miner, Plutonium 1970 and Other Actinides, MetaUurgical Society of AIME, New York, 1970. 

H. Blank and R. Liadner, Plutonium 1975 and Other Actinides, North HoUand Publishing Co., American Elsevier Publishing Co., New York, 1975. 

The symposium was designed to provide an overview of the current status of plutonium chemistry by practitioners in the various areas covered. The authors, drawn from U.S. and foreign universities and national laboratories, were encouraged to include review material to place their subjects in perspective, as well as to suggest what they believe to be productive directions for future investigation. We find it particularly useful that the contributions represent a mixture of fundamental as well as more applied environmental and process chemical research. Although we do not claim that this volume represents all areas of plutonium chemistry that are currently under active investigation, this collection does represent a reasonably broad and balanced view of the field. The contents of the volume should be useful as a reference both for those familiar with actinide chemistry and for those with limited interests who seek an introduction to the literature and current status in an area of plutonium chemistry. 

The known oxidation states of plutonium present a 5f -series, starting from f1 [Pu(VII)] up to f5 [Pu(III)]. But contrary to the 4f - and 5f series across the period table, where the properties can be described by some smooth varying parameters, changing of the oxidation states influences the electronic properties drastically. Due to the large range of available oxidation states plutonium represents a favorable element among the actinides to study these effects. 

The chemical similarity between lanthanide and actinide metals suggests that C2H I2 might also react with actinide metals. Preliminary experiments found no reaction between thorium or uranium metals and a THF solution of Plutonium and neptunium... 

---