«XVIII МЕНДЕЛЕЕВСКИЙ СЪЕЗД ПО ОБЩЕЙ И ПРИКЛАДНОЙ ХИМИИ Москва, 23–28 сентября 2007 г. ТЕЗИСЫ ДОКЛАДОВ Москва – 2007 УДК ...»
However, in contrast to the glasses, which are characterized by a constant leaching rate throughout the test period, the experimental data (test MCC-1) show a pattern typical of mineral matrices, with the leaching rate controlled by the solubility, diffusion, and rate of the solution transfer in the system of connected pores of the low-permeable monolith.
It was found that, at contact with solution, the pores in the monolithic samples are filled with a calcium hydrosilicate gel decreasing their porosity and, in turn, leaching rate. SCAS matrices exceed special glasses and are close to some ceramic compositions in the safety of immobilization of alkali and alkaline-earth elements. Thus polymineral glass-ceramics in which decrease in leach ing rate is reached due to interaction with a leaching solution, are perspective at the decision of eco logical problems.
Moreover, fly ash is a powder-like industrial waste accumulated in gigaton amounts. This material can be used in mixtures with various carbonate-containing components (limestone, dolomite) without any pre-treatment. The high temperature synthesis of SCAS can be performed using residual solid fuel (coke) contained in the fly ash.
These problems were discussed in Ref. 1 in more details.
References 1. A.D. Chervonnyi, and N.A. Chervonnaya, Radiochemistry 2004, 46, 190.
2478 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, SYNTHESIS AND PROPERTIES OF SOLID GADOLINIUM CARBOXYLATES, INTENDED FOR MANUFACTURING LIQUID ORGANIC SCINTILLATOR FOR DETECTING ANTINEUTRINO OF NUCLEAR REACTORS Danilov N.A., Krylov Yu.S., Tsivadze A.Yu.
Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Science, Moscow, Russia.
One of the main problems at manufacturing metal-loaded liquid organic scintillator (MeLS), in tended for detecting neutrino is stability (not less than three years) their optical properties (a trans parency and light output). Earlier1 it has been shown, that one of the main reasons of instability of optical properties MeLS is presence of water in an organic phase. Therefore manufacturing MeLS is recognized perspective by dissolution preliminary made solid waterless Gd-carboxylates in corre sponding solvents.
In the given work results on synthesis and studying of properties solid waterless gadolinium car boxylates (GdR3), where R – a radical of carboxylic acids are submitted. The technique of reception solid waterless gadolinium carboxylates with carboxylic acids from C4 up to C9 has been developed, and their properties are investigated. By method of differential thermogravimetry determines melt ing point and decomposition point of gadolinium carboxylates, their solubility in water and in vari ous organic solvents were determined. With the purpose of increase in solubility GdR3 and stability GdLS influence of additives of carboxylic acids and neutral organophosphorus compounds (NOPC), such as phosphates, phosphonates and phosphinooxides has been investigated.
It is shown, that the best stability of optical properties have scintillator on the basis of com pounds GdR33HR and GdR33NOPS. Long-term tests of optical properties received scintillator have confirmed their stability within more than three years that corresponds to the requirements showed to GdLS, intended for detecting antineutrino of nuclear reactors.
References 1. N.A.Danilov, Yu.S.Krylov, G.V.Korpusov, etc. Radiochemistry 2005, V.47, 5, 445-451.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 RECEPTION LIQUID ORGANIC Gd-LOADED SCINTILLATOR BY LIQUID EXTRACTION METHOD FOR DETECTING ANTINEUTRINO OF NUCLEAR REACTORS Danilov N.A., Krylov Yu.S., Tsivadze A.Yu.
Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Science, Moscow, Russia Long-term experiments with reactor antineutrino represent of the most effective method of research neutrino ossilation, that opens in turn an opportunity of definition mass of neutrino and studying of physics outside standard model of weak electric interactions.
The purpose of work was manufacturing liquid organic Gd-loaded scintillator (Gd-LS) with con centration of Gd 0,1% with a high transparency and light output, and stability of these properties not less than three years.
Work included basic researches about the purpose of a choice of organic solvents and extrac tants, to the greatest degree adequate to tasks in view. Trimethylbenzene (TMB), phenylxelylethan (PXE) and their mixes with dodecane and mineral oil have been investigated as solvents.
The 2-methylvaleric acid (H2MVA) has been chosen as extractant. It is found, that depending on conditions of carrying out of experiment in an organic phase.exist the complexes: Gd (2MVA)33(H2MVA)nH2O, Gd(2MVA)3nH2O, Gd(OH)x (2MVA)3-xnH2O, where n = 12 de pending on the used solvent. The greatest solubility in organic solvents has Gd(2MVA)33(H2MVA)nH2O.
Influence of the contents of water in an organic phase on stability of optical properties Gd-LS has been investigated and shown, that presence of water is one of the main reasons of their instabil ity. It is shown, that use of driers for removal of water of their organic phase allows to increase in some times stability of optical properties Gd-LS, but at the same time brings in it undesirable impu rity (Na, 40K, etc.). The conclusion about perspectivity of manufacturing Gd-LS on the basis of solid waterless Gd carboxilates (preliminary prepared) in corresponding solvents is made.
2480 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, MOLECULAR CHARACTERIZATION OF ACTINIDE OXOCATIONS FROM PROTACTINIUM TO PLUTONIUM Den Auwer C.a, Fillaux C.a, Guilbaud P.a, Guillaumont D.a, Jeanson A.a, Moisy P.a, Le Naour C.b, Trubert D.b, Simoni E.b, Di Giandomenico V.b, Hennig C.c, Scheinost A.c a CEA Marcoule DEN/DRCP/SCPS, 30207 Bagnols sur Cze, France firstname.lastname@example.org b IPN Orsay, 91405 Orsay, France c FZR, ROBL at ESRF, 38043 Grenoble, France For industrial, environmental and public health purposes, actinide chemistry has been the subject of considerable efforts since the 50’s. Aqueous redox chemistry, ionic selective recognition, uptake by specific biomolecules or compartments of the geosphere are some of the major fields of investiga tion. The physical-chemical properties of the actinide elements strongly depend on the 5f/6d elec tronic configuration. Some of them (U, Np, Pu and Am) can form AnO2n+ (n= 1, 2) oxocations, so called actinyls, with two strong An-O covalent bonds. In any case, the cation polyhedron is charac terized by large, flexible coordination spheres with various stable and metastable metal oxidation states.
In solution, EXAFS and XANES at the actinide LIII edge is an ideal structural probe of the cation coordination sphere. Furthermore, coupling the EXAFS data with molecular dynamics calculations leads to a better description of the cation-solvent interactions. In addition, disorder can explicitly be taken into account using time spaced snapshots of the molecule. This is particularly important when large polyhedra are composed of ligands of similar types as water molecules.
Protactinium, as the first actinide with 5f-electrons involved in bonding, occupies a key position in the actinide series. At formal oxidation state V (its most stable oxidation state in solution as well as in the solid state) Pa(V) corresponds to the formal 5f0 electronic configuration. U(VI) also corre sponds to the formal oxidation state 5f0 and is most often encountered as the stable oxocationic form UO22+. The first stable form of U, Np or Pu at formal oxidation state (V) under atmospheric conditions is NpO2+ with formal 5f2 electronic configuration. U(V) is highly unstable under atmos pheric conditions and Pu(V) dismutates into Pu(IV) and Pu(VI). On the other hand, the existence of the PaO2+ form in solution and in solid state is highly improbable and has never been reported.
This presentation addresses the structural characterization with EXAFS of actinide cations at oxidation states (V) and (VI) as one walks across the periodic table from Z = 91 (protactinium) to Z = 94 (plutonium). For the fist time to our knowledge, the occurrence of the oxocation form of Pa(V) in H2SO4 solution has been inferred from EXAFS and XANES data at the Pa LIII edge. A structural comparison between Pa, U, Np and Pu oxocations in aqueous solution at formal oxidation states (V) and (VI) is carried out. These results are corroborated by quantum chemical and molecular dynam ics calculations.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 NOVEL SORBENTS ON THE BASIS OF OXY-HYDROXIDES OF IV GROUP METALS Denisova T.A., Maximova L.G., Polyakov E.V., Shein I.R., Zhuravlev N.A., Leonidova O.N., Baklanova Ya.V.
Institute of Solid State Chemistry of UB RAS, Ekaterinburg, Pervomayskaya, In the present work new oxy-hydroxide compounds of zirconium(IV) and tin(IV), H2ZrO3 and Li0,2H1,8SnO3, are prepared from disordered Li2MO3 (M=Z, Sn) by an ionic exchange in acid media.
These compounds are considering as analogues of a metatitanic acid H2TiO3. Crystal structures of H2ZrO3 and Li0,2H1,8SnO3 are shown differ from the structure of the initial Li2MO3 and oxides MO phases. The prepared compounds are dehydrated in an interval 100-200°C with formation corre sponding hydrated oxides. On the basis of the analysis of NMR spectra of 1H and 7Li it is shown, that an energy of protons bonding with a crystal lattice in H2ZrO3 and Li0,2H1,8SnO3 strongly differs depending on the protons location in certain crystal positions. In contrast, in the metatitanic acid all the protons are belonged to OH-groups and have close bond energy. Thereof, approximately half of the protons in the former compounds are relatively mobility at room temperature, and form water molecules in case Li0,2H1,8SnO3. Quantum-chemical calculations of energy characteristics are car ried out for Li2TiO3 and Li2SnO3 in comparison with Li1.75H0.25MO3 (M=Ti, Sn). These simulations consider transformation of the solids in which one of eight ions of lithium in various positions are replaced by a proton. It is found, that in a the case of Li2TiO3 the most energy preferable position of a proton location is the position Li(3), whereas for the Li2SnO3 this position may be referred to Li(1). This conclusion testifies that different positions of the proton have different bond energies in these compounds. The specified features impact temperature dependence of low-temperature con ductivity in these compounds. In a metatitanic acid protons are moved from one crystal position to another in accordance with the jump known mechanism. In the solid Li0,2H1,8SnO3 mobile mole cules of water participate in a movement of protons of OH- groups.
On the basis of sorption experiment it is shown, that H2TiO3, H2ZrO3, Li0,2H1,8SnO3 and hy drated titanium oxide HDT (TiO2·0,74H2O) essentially differ by the level of affinity (of distribution coefficient, Kd) to cations and anions. According to the estimates values of Kd these materials can be arranged into the following general array of sorption affinity: H2ZrO3H2TiO3 TiO2·0,74H2O Li0,2H1,8SnO3.
Al Fe Ga As Ba Lu Th U lg Kd, мл/г HDT H2ZrO3 H2TiO3 Li0,2Н1,8SnO Figure. Comparative sorption activity of oxy-hydroxide compounds The work was supported by RFBR, grant 06-08-00847 and Leading Scientific Schools, grant SS-5138.2006.3.
2482 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, CHEMICAL PROCESSES IN CARBONATE-CARBON DIOXIDE SOLUTIONS CONTAINING URANIUM, NEPTUNIUM, AND IRON IONS Gogolev A.V., Zakharova E.V., Rodygina N.I., Fedoseev A.M., Shilov V.P.
The interaction between compounds of pentavalent neptunium and divalent iron was studied in bi carbonate solutions of various concentration. The interaction between Np(V) and Fe(II) in the pres ence of phthalate ions was briefly considered. It was found that in solutions saturated with Ar or CO2 the reduction of Np(V) by divalent iron occurred at any bicarbonate ion concentration. At the value of [Na(K)HCO3]0.86 mole/L the reaction (1) is completed during the mixing of solutions and the recording of spectra. In the diluted bicarbonate solutions the interaction (1) gets considera bly slower, probably due to the lower solubility of the neptunium(V) carbonate complexes:
Fe(II) + Np(V) Fe(III) + Np(IV) (1) When diluted bicarbonate solutions are saturated with CO2, the solubility of Np(V) compounds increases, but is does not yield a higher reaction (1) rate;
it remains low. The reduction of uranium (VI) carbonate complexes by iron(II) compounds occurs in diluted bicarbonate solutions. At the elevated temperatures in the argon atmosphere the reaction produces UO2 and FeOOH.
The reduction of Np(V) by U(IV) ions in concentrated bicarbonate solutions occurs quickly and completely as well.
Np(V) + U(IV) Np(IV) + U(VI) (2) In diluted bicarbonate solutions and in solutions saturated by CO2 in the reaction (2) take part the hydroxide U(IV) compounds, U(IV) polymer, and mixed-valent U(IV)/U(VI) compounds. At the excess of Np(V) in the carbon dioxide solutions containing polymer uranium (IV) hydroxide the polymer Np(IV) is accumulated. Intermediate products of the Np(V) reduction with the U(IV) polymer in solutions with pH 2-5 are the mixed-valent compounds containing U(IV)/U(VI)/Np(IV)/Np(V). The spectra of U(IV) and Np(IV) solutions at pH 2-5 saturated with Ar differ from those of the analogous solutions saturated with CO2. The phenomenon, possibly, might be explained by the fact of the carbonic acid interaction with the intermediate tetravalent ac tinide hydrolysis products.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 CATION-CATION INTERACTIONS IN Pu(V) COMPOUNDS Grigoriev M.S., Bessonov A.A., Charushnikova I.A., Krot N.N.
A. N. Frumkin Intstitute of Physical Chemistry and Electrochemistry, RAS, 31 Leninsky prosp., 119991 Moscow, Russia Transuranium elements in pentavalent state exist in solutions and solid compounds mainly in a form of linear dioxocations AnO2+, in which the “yl” O atoms have a significant negative charge and the positive charge on the central atom is appreciably higher than unity. Due to such charge distribu tion, these cations have high complex-forming ability. Also, they can enter into mutual coordina tion, referred to as cation-cation (CC) interaction. The ability for the CC interaction becomes weaker in the series Np-Pu-Am. The major part of the data on the structure and properties of An(V) solid compounds have been obtained for Np(V). The information about Pu(V) compounds until re cent times was very scarce, in particular, it was not known if Pu(V) can form CC complexes in crystals. The reason of such situation is higher radioactivity of Pu, as compared with Np, as well as a low stability of Pu(V) in water solutions.
The studies on the synthesis and structure of novel Pu(V) compounds, carried out recently in IPCE RAS, have shown that several different types of CC complexes are present in Pu(V) com pounds.
(NH4)[PuO2C2O4]·2.67H2O1 is isostructural with analogous Np(V) compound with known struc ture. Thus, this compound contains trimers of plutonyl(V) ions which are coordinated to each other as monodentate ligands.
The [(PuO2)2L2(OOCC6H5)2] compounds, where L is 2,2’-bipyridine or phenanthroline, contain dimeric dioxocations (PuO2+)2, in which two of the four O atoms bridge the Pu atoms2–4. Earlier, a similar dimer was known only for a double Np(V) and Na mellitate – Na4[(NpO2)2C6(COO)6]·8H2O. From spectral data for CsPuO2C2O4·2H2O1 we can suppose that PuO2+ dioxocations act as biden tate ligands in CC complexes but this supposition needs additional proofs.
References 1. A. A. Bessonov, N. N. Krot, M. S. Grigor’ev, V. I. Makarenkov, Radiochemistry 2005, 47, 468.
2. I. A. Charushnikova, N. N. Krot, Z. A. Starikova, Radiochim. Acta (in press).
3. M. S. Grigoriev, A. A. Bessonov, N. N. Krot, K. Yu. Suponitsky, Acta Cryst. 2006, E63, m561.
4. A. A. Bessonov, N. N. Krot, M. S. Grigor’ev, V. I. Makarenkov, Radiochemistry (in press).
5. A. Cousson, S. Dabos, H. Abazli, F. Nectoux, M. Pags, G. Choppin, J. Less-Common Met. 1984, 99, 233.
2484 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, UNDERESTANDING THE CHANGING ROLE OF THE 5f ELECTRONS THROUGH CORRELATIONS Haire R.G.
Oak Ridge National Laboratory, Oak Ridge, TN 37831-6375 USA email@example.com Great strides have been made in experimental and computational high-pressure studies of the acti nide in the last six years. Most of these investigations have been concerned with the structural sta bility of the f-electron metals, although some efforts have included alloys and compounds. The most interesting findings have been with the elements, as the presence and bonding roles of non actinide atoms in compounds perturbs the involvement of 5f electrons.
The early actinides behave differently than the higher members of the series. However, the latter are different in behavior from that for the lanthanides;
one reason is the 5f electrons have a much greater spatial extension than their 4f counterparts. The nature of the earlier members of the actinide series are often considered from the standpoint of distortion of the bonding via incorporation of 5f states in their bonding, which brings about significant changes in crystal symmetries and properties.
With the transplutonium elements the normal ground-state crystal structures are governed by 6d bonding. However with significant changes in interatomic distances via pressure, the 5f electrons are readily perturbed and acquire the electronic nature and structural behaviors similar to the earlier actinides having 5f-electron character in their bonding. More recent thoughts have considered the roles of spin polarization and magnetic interactions in the context of the crystal symmetries and bonding. Some of these were observed and discussed in the context of the unexpected findings with curium1, americium-curium and berkelium-curium alloys2, and correlations of electronic configura tions with bonding changes observed under pressure3.
Presented here is an overview of the behaviors of several actinide materials, some experimental and computational insights into the bonding changes encountered, and selected correlations that can be considered in understanding changes occurring in the materials’ electronic configurations and bonding.
References 1. S. Heathman, R. G. Haire, T. Le Bihan, A. Lindbaum, M. Idiri, P. Normile, S. Li, R. Ahuja, B. Johansson and 2. G. H. Lander, Science, 309,110 (2005);
and references therein.
3. S. Heathman, R. G. Haire, T. Le Bihan, R. Ahuja, S. Li, W. Luo and B. Johansson, Alloys and Comp., (in press, 2007).
4. R. G. Haire and S. Heathman, Mat. Res, Soc. Symp. Proc., (in press, 2007).
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 NEW DEVELOPMENTS IN RADIONUCLIDE SEPARATION USING INORGANIC MATERIALS Harjula R., Koivula R., Kelokaski P., Paajanen A.
Laboratory of Radiochemistry, PO Box 55, 00014 Helsinki University, Finland Selective ion media, e.g. inorganic adsorbents and ion exchangers, are increasingly used for the re moval of key radionuclides such as 60Co, 90Sr and 137Cs from nuclear waste effluents due to their radiation stability, high processing capacity and high decontamination efficiency1.The applications of materials that are commercially available (e.g. zeolites, titanates, silicotitanates, hexacyanofer rates) will be reviewed in the first part of the presentation. New ways to use of inorganic materials in special contactors (Cartridge filters, Funda filters)2 as fine powders, to increase radionuclide up take rate, will also be described. Such novel application has been used e.g. in UK (Sellafield) and in several nuclear power plants in the USA. Main emphasis is on materials (CsTreat, SrTreat and CoTreat) developed at the University of Helsinki.
Many commercial materials available have limitations, e.g. poor performance in acidic solutions and in the presence of Ca ions. In the second part, development of new materials that overcome these problems will be described. These materials include mixed oxide pyrochlores, which can be tailored for special separation tasks (Fig. 1) Fig. 1. Selectivity of the pyrochlores can be tuned by substitution of different metals in the frame work which affects the framework acidity and crystal window size.
References 1. R. Harjula, J. Lehto, Selective Separation of Radionuclides from Nuclear Waste Solutions with Inorganic Ion Ex changers, Radiochim. Acta, 86(1999)65.
2. R. Harjula, A.Paajanen, J.Lehto, E. Tusa, R. Smith and P. Standring, Additional Testing Of CoTreat Inorganic Ion Exchange Media For The Removal Of Co-60 From Thorp Pond Water, Proceedings of Waste Management Conference, February 29- March 4, 2004, Tucson, AZ.
2486 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, ACTINIDE SUPRAMOLECULAR CHEMISTRY YESTERDAY AND TODAY Ionova G.V., Mikhalko V.K., Tsivadze A.Yu.
Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, 119991, Moscow, Leninski prospect The work is dedicated to the memory of V. I. Spitsyn who had stimulated the development of fun damental investigations in the field of actinide chemistry in Russia Yesterday. The aim of this work is to bridge a gap between the early and modern actinide su pramolecular chemistry (AnSCh). The origin of AnSCh has been sourced from actinide environ mental chemistry and technology extraction processes Truex, Tramex, Talspeak, Cyanex, Todga, CHON. The An/Ln interaction with tributyl phosphate and other ligating agents in the Purex proc ess for nuclear fuel processing had became the focus of attention over the past 50 years. Yet the early studies of UVI, PuIV, NpVI, ThIV, AmIII separation by liquid-liquid extraction had yielded in formation on the formation in organic phase of “large” extracted systems – polymers, aggregates, micelles /1/, which today are named supramolecular assemblies (SMA). The “self-assembling” had been called “self-salting” /2/. The formation of SMA explores the coordination bonds and intermo lecular forces – hydrogen bonds, aromatic stacking, polar and van der Waals interactions: any new forces have not been discovered in AnSCh. In natural waters numerous hydrolysis polynuclear spe cies [Thn(OH)m](4n-m)+ of ThIV /3/ (but not ThIII /4/) have been shown to exist which can be consid ered as discrete cyclic nanostructures. Upon migration of radionuclides in the geosphere the SMA (AnO2)j(CO3)k(SO4)l(OH)m2(j-k-l)-m, An=U, Np, Pu, have been studied /5/.
Today. The scientists had to recognize that “the Purex Process remains far from perfect. It also does not address the isolation of other An cations“ /6/. The early works in the field of AnSCh help highlight some of benefit that could come from the study of new An supramolecular systems. One important solution to the problem of An separation is to use new selective extractants. In our theo retical work we focused attention on the thermodynamics of An assembling with macrocyclic ligands. To solve the problem of An – selectivity identification, the bond energies An-O and An-N have been calculated for the wide range of macrocyclic ligands: expanded phtalocyanines;
calyxarene. The trend in thermody namic properties of SMA with AnIV, An=Th, U, Pu;
AnVI=AnO2+2, An=U, Np, Pu;
AnV=AnO+2, An=U, Np, Pu, has been studied. It was shown that self-assembled An supramolecules thermody namically profit from enthalphic as well as entropic effects. The role of solvation effects has been considered;
the hydrogen bond energies have been calculated for 200 SМА. We have established the regularity: the stronger the coordination (ionic + covalent) bonds, the weaker the intermolecular hydrogen bonds /7/.
References 1. F. Peppard, G. W. Mason, W. J. Driscoll. Inorg. Chem. V. 7, p. 276, 2. C. Nash, in: Handbook on the Physics and Chemistry of Rare Earths, vol. 18, ed. by K. A. Gshneidner, L. Eyring, North Holland, Amsterdam, p. 197-238, 3. D. Clark, D. Hobart, M. Neu. Chem. Rev. 95, 25, 4. G. Ionova, R. Guillaumont, C. Madic. Polyhedron, V. 17, N11-12, P. 5. W. J. Ullman, F. Schreiner. Radiochim. Acta, 43, 37, 6. J. L. Sessler, A. E. Vivian, A. K. Seidel. Coordin. Chem. Rev. №216- 217, p. 411-434, 7. A. Yu. Tsivadze, G. V. Ionova, V. K. Mikhalko, Russ. Chem. Rev., № 3, ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 CHEMILUMINESCENCE OF URANIUM AND TRANSURANIUM ELEMENTS Kazakov V.P.a, Tananaev I.G.b, Myasoedov B.F.b a Institute of organic chemistry USC of the RAS, 450054 Ufa, pr. Oktyabrya, 71. E-mail: firstname.lastname@example.org b A.N. Frumkin Institute of physical chemistry and electrochemistry of the RAS 119991 Moscow, Leninskiy prospect, 31, E-mail: email@example.com Chemiluminescence of uranium and transuranium elements has been discovered and investigated by the efforts of the Russian scientists mainly at the Institute of organic chemistry USC RAS in Ufa and at the Institute of physical chemistry and electrochemistry RAS in Moscow. The report presents the survey of the investigations in this field.
Although a majority of papers devoted to the behaviuor of chemiluminescence of 5f elements in solution, the report will begin with the results of recent years in which solid phase reactions of the uranium compounds will be described. Further chemiluminescence of transuranium elements occur ring on the border of liquid –solid phase will be considered. A short movie will illustrate a me chanical mobility of the crystals in the process of the reaction. This mobility is caused by the adhe sive forces arising on the border of division of the reagents in which a crystal water plays a crucial role. Pulsating character of the reaction is illustrated;
the latter is displayed by the anomalous fluc tuations of the chemiluminescence intensity as well as by the irregular evolving of gas (recorded by the mass spectrometry) during interaction of four valency uranium – U(SO4)2.nH2O with sodium salt of eight valency xenon – Na4XeO6.8H2O. In chemiluminescent reactions of uranium in solu tions there are a several ways of uranyl ion formation in excited state illustrated by the following scheme:
O * U4+ UO22+ + U 4+ 3, + Xe O O +U * UO 22+ UO 2+ O UO22+ + h 3, Xe 2+ O Eu 4 + U * 2+ UO22+ UO These are the reactions in which uranyl ion plays a role of an acceptor of the energy evolving in the other reactions (e.g. during reduction of Np(VII) compounds or the oxidation of elementary sul fur by the ozone in the presence of ions UO22+) and redox transformations of the uranium ions (e.g.
disproportionation reactions of its five valency state-uranoyl ion).
Low temperature reactions in frozen acid solutions in which a phase transitions in matrix play a crucial role are considered.
Examples of unusual mode of uranium behavior in reactions in concentrated sulfuric acid are given, namely appearance of autooscillation behavior (“flickering chemiluminescence”) as well as appearance of “photon chaos”. It is pointed out that the majority of the reactions (including autooscillation one) described in the report, easily observed by the naked human eye in slightly darkened room.
Analytical possibilities of femto-quantities of the uranium (4+) determination were considered.
The work was supported by the: RFFI 05-03-32285, OKHNM №1-OX;
Scientific school support NSh – 5486.2006.3;
Foundation for promotion of science DOE U.S.RUC2-20012-MO-04.
2488 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, PROSPECTS OF THE RADIOSPECTROSCOPY APPLICATION FOR STUDIES OF THE SANDSHALE ROCK DEFECTS Khodyakov A.A., Zakharova E.V., Kaimin E.P., Konstantinova L.I.
Frumkin Institute of Physical Chemistry and Electrochemistry of the RAS, 31 Leninsky Prospect, Moscow, The study of technogenic transformations in sandshale rock is a necessary condition in forecasting safety of a low-level radioactive waste (LLRW) repository. During the long-term contact with waste the structural changes in minerals may occur ambiguously affecting the sorption properties of the rock. The EPR method could be used as one of the techniques for the LLRW impact analysis on the rock. In this work we studied the sandshale rock sampled from the LLWR repository in the vi cinity of an injection well (Sample 1, 290 m depth;
Sample 2, 340 m depth). The repository is in operation since 1968 and the rock was in contact with the waste practically all the time. The rock with no LLWR impact was studied also (Sample 3, 290 m depth). To identify the paramagnetic cen ters (PC) detected in the rocks we also studied kaolinite and the electron stream irradiated Sample 3.
It was found that in EPR spectra of the rocks (except kaolinite) that constitute the superimposed signals from the PC of different origin (see Fig.1, 2) components of the superfine structure (SFS) are observed with the resolution of ~ 0.6 T characteristic for [A1] centers. One of the signals is attributed to the paramagnetic defects of [AlO4/2]/Me+ or [AlO3/2O-Me+] type. Three-dimensional anisotropic signal (see Fig.2, A) with 16 SFS components could be assumed as the [Al*O3/2O …2(Al)] center, where [Al*] occupies an irregular node in the Si4O10- layer, and […2(Al)] are in the local [Al*] environment with lower symmetry as compared to octahedron. Some lines present in the spectra appeared from the electrons captured by the non-bridge silicon-bound oxygen. In the Sam ple 2 spectrum the line responsible for one of the signals from the electrons captured by the non bridge silicon-bound oxygen (see Fig,1, denoted by the arrow) practically disappears, and the A signal is not seen also. It might witness that the fall of concentration of the above defects is related to their destruction as a result of the technogenic LLRW impact on the rock under study.
Fig. 1. EPR spectra (recorded at 77 K) Sam- Fig. 2. EPR spectra (recorded at 77 K) of ple 2 (1), Sample 1 (2) and Sample 3 kaolinite (1) and Sample 3 after the (3). irradiation with electrons up to the accumulated dose of 240 kGray (2).
This work was completed under the financial support of RFFR No. 05-03-32129.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 APPLICATION OF THE ELECTROOSMOSIS AND RADIOSPECTROSCOPY FOR STUDY OF THE RADIONUCLIDE SORPTION MECHANISMS Khodyakov A.A., Zakharova E.V., Kaimin E.P., Konstantinova L.I.
IPCE RAS, 31 Leninsky Prospect, 119991 Moscow During the long-term interaction of liquid radioactive waste with the repository host rocks the rock transformation, the initial mineral solubilization, and the synthesis of new phases may occur. The technogenic transformation of the rock may produce the rock that differs from the original both in sorption properties and in mechanisms of the radionuclide interaction with the rock components.
The above changes were studied using the electroosmosis and the method of EPR.
The experiments were performed with rock samples taken from the depth of ~300 m in the vicin ity of the alkaline waste repository (Sample 1). Sample 2 was obtained after the interaction of Sam ple 1 with alkaline waste at 70°C. Sample 2 was rinsed before the experiments with distilled water.
The elektrokinetic potential value (eff) was calculated from the results of the electroosmotic trans fer of liquid in Sample 1 and Sample 2. Experiments on 137Cs+ and 90Sr2+ trapping with the rock samples were conducted with various liquid phase composition;
the identification of 137Cs+ speci ation in the rocks was performed and EPR spectra of the samples were also recorded.
It was found that at the boundary of the solid and liquid phase the double electric layer (DEL) is formed, where the rock particle surface carries the negative charge. As compared to Sample 1 the higher eff value of Sample 2 corresponds to the higher 90Sr2+ sorption factor value (S, %, see Table 1). The thickness of the diffuse DEL part and the peculiarities of its structure do not significantly affect the sorption of 137Cs+ (see Table 1). As the NaNO3 concentration increases, the S parameter for 90 Sr2+ falls to 51% in Sample 2 and to 14% in Sample 1. The quantity of 137Cs+ trapped by the defects of volume and rock particle surface (Sdef) was evaluated by the amount of cesium remained after the desorption with 1M HCl solution. If was found that the Sdef in Sample 1 exceeds the same in Sample 2 by 11%. The difference in Sdef parameters corresponds to the difference in the para magnetic defect concentration in the rocks (see Table 1). It witnesses the fact that the adsorption center function, in the absence of the significant effect of the diffuse DEL part thickness and the peculiarities of its structure on the sorption of 137Cs+, is, most probably, carried out by the defects of volume and rock particle surface.
Table 1. Values of the electrokinetic potential, sorption factors (S) of 90Sr2+, Cs+, and paramag netic defect concentration (R) Parameter Sample 1 Sample eff, relative units 1 S (%) of 90Sr2+ 72 S (%) of 137Cs+ 100 S (%) of 137Cs+ in 0.1 M NaNO3 99 S (%) of 137Cs+ in 0.5 M NaNO3 96 R, [centers.g-1] 1016 2490 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, THE FORCE INFLUENCE MECHANISM FIELDS FOR RATE OF EXTRACTION Kizim N.F.a, Pronin E.V.a, Golubina E.N.a, Tarasov V.V.b a Novomoskovsk Institute, Mendeleev University of Chemical Technology of Russia, Novomoskovsk, Druzhby Street, 8.
b Mendeleev University of Chemical Technology of Russia, Moscow, Miusskay square, Extraction it is widely used in a radiochemical practice. Subject to hydrodynamical instability of interface rate extraction can increase in systems on the order. In this connection studying of the rea sons causing the given phenomenon, search of ways of artificial creation of conditions for devel opment spontaneous surface convection and its preservations during all technological process repre sents significant practical interest.
One of possible approaches is influences of a field of vibrations on a dynamic interfacial layer, instead of on system as a whole as it is done in pulsation to the equipment. Oscillatory influence of a tape, moving from an organic phase in water and on the contrary with frequency up to 4 s-1, have shown that the mass factor transfer essentially increases. However this effect brightly shown in the beginning of process, dies away in time.
Placing a vibrating element of the certain form on an interface and carrying out vibrations with amplitude of the order of the several tenth mm, but in other frequency range (2,5 – 12 kHz), we managed to reach the same effect, but with a smaller expense of mechanical energy brought in a dynamic interfacial layer. The mechanism of influence of a field of the vibrations, in details consid ered in the given message, is interpreted by us within the limits of is artificial created effect Maran goni.
Other possible ways for a mass intensification transfer processes is application of electric fields of the high tension providing development of hydrodynamical instability both on interface, and in volumes of contacting phases. In the message results of regular studying of influence of an external electric field for the rate mass transfer processes in extraction systems are presented:
1) di-(2-ethylhexyl)phosphoric acid (D2EHPA), toluene (octane) – rare earth elements (Ce, Ho, Pr, Nd, Eu), H2O, 2) tributyl phosphate (TBP), toluene (pentane, hexane, decane, octane) – HNO3 (CH3COOH), H2O.
It is established, that in systems with D2EHPA the major importance at extraction metals has de velopment of effect Marangoni and formation of the structured dynamic interfacial layer reducing efficiency of influence for an external electric field. While rate of carry extragent in a water phase in absence of a taken component increases with growth of intensity of an electric field, rate extrac tion an element changes slightly. It is shown, that introduction in system aliphatic spirits can lead to reduction of rate mass transfer due to formation and hardening of interfacial structures at a premise of system in an external electric field.
For systems with TBP it is established, that influence of a field on extraction (stripping) nitric acid more considerably, than CH3COOH which is accompanied intensive spontaneous surface con vection. Are come out with assumptions concerning influence of the nature of solvent and a trans ferable component on efficiency of application of an external electric field.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 KINETIC ISOTOPIC EFFECT OF THE INTERACTION BETWEEN THE MOLECULAR HYDROGEN AND THE SH GROUPS OF Co(Ni)MoS CATALYSTS IN THE COURSE OF THIOPHENE HYDRODESULFURIZATION Kogan V.M.
N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences 47, Leninsky prospect, Moscow 119991, Russian Federation In the series of studies using isotopes 35S and 3H we have developed the “forcing out” (or “extru sive”) mechanism of hydrodesulfurization of thiophene or another sulfurorganic compound on the surface of sulfide Co(Ni)Mo catalyst1–3. According to the mechanism, the sulfur of thiophene “ex trudes” the sulfide sulfur from the catalyst surface into the gas phase. The mechanism includes a step of the interaction of the gas phase H2 with the SH group of the catalyst followed by the H2S formation. This interaction explains a transfer of the radioactivity into the H2S in the course of thio phene HDS over the catalyst labeled by 35S (scheme 1).
Scheme 1 Scheme H C4H8 +C4H10 n H H2S + C4H8 + C4H HH S H2 SH H SH a b (Co)Mo/ Al2O SH H SH H /T SH S H2S (Co)Mo/ Al2O However, one can suppose an alternative mechanism. The radioactivity transfers into the H2S molecule due to an isotopic exchange between labeled catalyst *SH group and the formed H2S (path a, scheme 2). In this case the change in molar radioactivity is not related to the catalytic activity in the HDS.
The data of the experiments with 35S and 3H where taken into account when we considered all the hypothetically possible pathways of such exchange and came to the conclusion that none of the pathways under consideration is under way. Then it follows that the radioactivity in the formed H2S is the result of the “extrusive” mechanism and that the intensity of sulfur replacement does relate to the catalytic activity in the HDS.
Two possible mechanisms of the H2S formation on sulfide catalyst surface with the participation of the gas phase hydrogen have been considered (schemes 3 and 4):
S(ads) + H2(g) SH(ads) + H(ads) (a) S(ads) + H(ads) SH(ads) (c) SH(ads) + H(ads) H2S(g) (b) SH(ads) + H2(g) H2S(g) + H(ads) (d) Scheme 3 Scheme It has been shown that scheme 4 takes place rather than scheme 3, i.e. molecular hydrogen inter acts with the SH group (d) but not with sulfide sulfur (a).
The study was supported by the Russian Foundation for Basic Research (Grant RFBR 05-03-39006).
References 1. V. M. Kogan, in: “Transition Metal Sulfides. Chemistry and Catalysis” NATO ASI Series, 1998, p. 235.
2. V.M. Kogan, N.N. Rozhdestvenskaya, I.K. Korshevets, Applied Catalysis A: General, 2002, 234, 207.
3. V. M. Kogan Applied Catalysis A: General 2003, 237, 161.
2492 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, HYBRID MACROCYCLES AS EFFECTIVE RECEPTORS FOR PERRHENATE AND PERTECNETATE ANIONS Kolesnikov G.V., Mishkovskaya E.N., Boev N.V., Ustynyuk Yu.A., Tananaev I.G., Katayev E.A.
A.N.Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28, Vavilov st., 119991, Moscow, Russian Federation.
The development of highly efficient systems capable of binding specific anions selectively is rec ognized as being a key predicate to solving a number of fundamental problems, including anion sensing, extraction, and separation. Pertechnetate anion is the most common form of the long-lived isotope 99Tc (t1/2 = 2.13 x 105 years) that is formed from 235U or 239Pu. The recognition and extrac tion of pertechnetate anion is one of the most critical problem having appeared in applied chemis try, concerning mostly reprocessing of spent fuel and diagnostic nuclear medicine.
Our previous investigations showed the ability of oligopyrrolic macrocycles efficiently bind oxoanions in particular sulfate, phosphate and perrhenate. The aim of the work presented was to examine properties of our macrocyclic molecules for analytical use, namely binding and extraction.
The anion-binding properties of a series of bipyrrole containing receptors were measured using UV VIS titration method. Only three receptors 1, 2 and 3 bearing bipyrrole motif have proven selective for binding ReO4- anion (as non-radioactive analogue of TcO4-), K Re O 10 10 M. The re 5 ceptors 1 and 2 were used as their BF4– salts, 3 as neutral ligand. Extraction experiments revealed that receptors 1•(HBF4)2 and 2•(HBF4)2 efficiently extract pertechnetate in wide range of pH with out phase transfer agents. 1•(HBF4)2 extract with 90% efficiency in 2-13 pH range, while 2 was 70% effective in 3-7 pH range.
For 1 and 2 as the most effective agents competitive extraction was investigated. This study dis played high level of pertechnetate extraction for 1 even in presence of sulfate and perchlorate ani ons at neutral pH.
Ph Ph Ph Ph N N HN HN O O O O H H NH NH HN HN N HN H N NH N HN NH HN O O HN HN NH NH NH n-Pr n-Pr HN n-Pr n-Pr H NH N 1 2 The work was supported by Russian Foundation for Basic Research (grant no. 05-03-32684 and 05-03-08017) and ongoing collaboration with prof. J. L. Sessler from University of Texas at Austin, USA.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 SEPARATION OF RADIOELEMENTS IN NON-STATIONARY CONDITIONS BY BULK LIQUID MEMBRANE Kopyrin A.A., Afonin M.A., Budjak A.A.
Saintt.-Petersburg state Institute of technology (Technical University), 26, Moscowsky ave., St.-Petersburg, Russia, firstname.lastname@example.org Performing of a separation process of elements with similar properties far from a thermodynamic equilibrium in non-stationary conditions is based on differences in kinetics of complex formation of these elements in an aqueous phase and the process of transferring between aqueous and organic phases.
The majority of state-of-the-art separation processes of elements and radioactive isotopes are based on achievement by system of a stationary state or close to them. Thus at separation of ele ments with similar properties, there are certain difficulties. The present status of a problem of sepa ration and excretion of lanthanides, uranium and other elements with similar properties puts for ward a problem of search of new paths of separation of elements.
In the present work non-stationary extraction is used for separation of rare earths (REE) and ura nium in extraction system with use of a continuous liquid membrane that has enabled to combine advantages of liquid membranes and non-stationary extraction. For this purpose are used periodic oxidation / reduction of ions of cerium by an electrochemical method as a source of non-stationary behavior of extraction system with a bulk liquid membrane.
Time profiles of red / ox potential, temperatures, and also kinetics of extraction of U, Ce and Eu by a tri-n-butylphosphate (TBP) in oscillatory extraction systems are investigated. Metals concen tration was determined by the methods of radiometry, potentiometry, and spectrophotometry.
Experimental data have shown, that the concentration of Ce4+, Eu3+, and UO22 + periodically change. Partition coefficients of uranium, and europium change periodically in a time and are, as a rule, in phase opposition with oscillations of concentration of Ce4+.
The effect of interference of oscillatory reaction, extraction of uranium and REE at presence of cerium at non-stationary conditions is detected. Ways and methods of management by oscillatory extraction of uranium and REE are revealed.
The mathematical model is developed and the mechanism of oscillatory extraction of cerium, uranium, praseodymium and neodymium is studied. The new method of extraction and separation of similar elements, and also isotopes of rare and the radioactive elements, based on oscillatory process of extraction / stripping in two extractors connected by a bulk liquid membrane is created.
This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under grant RC0 20000-SC14 and RUC2-20011-ST-04 administered by the Civilian Research and Development Foundation.
2494 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, REE SEPARATION BY LIQUID MEMBRANE UNDER PERIODICAL TEMPERATURE OSCILLATIONS Kopyrin A.A., Afonin M.A., Fomichev A.A., Bitkov G.A.
Saint-Petersburg Institute of Technology, 26 Moskovsky av., 190013, Saint-Petersburg, Russia, email@example.com The influence of periodical oscillations of the temperature on extraction and stripping processes in the extraction systems is studied. Two extraction system were investigated, №1: 6M NaNO3 – Nd(NO3)3 – Pr(NO3)3 – TBP – kerosene and №2: [Nd(NO3)3·3TBP] – [Pr(NO3)3·3TBP] – kerosene – 0.1M HNO3. An experiment with periodical influence of the temperature on the extraction system NaNO3 – Nd(NO3)3 – Pr(NO3)3 – TBP – kerosene – 0.1M HNO3 for REE separation by bulk liquid membrane between two extractors1 was performed. This experiment shows higher separation coef ficient of REE in comparison with the system with constant temperature in the extractors.
The values of pre-exponential factor and activation energy for direct and reverse reactions of ex traction and stripping reactions of Pr and Nd were calculated using proposed mathematical model.
r s r s Ea = Ea Ea r r s s r r E E uu r suu s s a a k (Pr) = k0 (Pr) / k0 (Pr) e RT = 4, 29 105 e RT Ea = 25 kJ r r s s r r E E uur su u s s a a k ( Nd ) = k0 ( Nd ) / k0 ( Nd ) e RT = 7, 23 106 e RT Ea = 30 kJ The similar data was received for the system Nd(NO3)3 – Pr(NO3)3 – 6 M NaNO3 – H2O– 0.7 M TBP – kerosene. The parameters of modified Arrhenius equation were estimated by solving of the reverse kinetics problem from the temporal dependence of the metal concentrations in aqueous and organic phases at temperature T = 293, 298, 303, and 308 K:
r r 25000 k Nd k Pr 9,03101 s = 4.45 106 T 4,8310 e RT s = 1.88 10 T e RT k Pr k Nd The series of experiments with influence of periodical oscillations of the temperature on the ex traction system for separation of rare earth elements using bulk liquid membrane between two ex tractors are performed. The mathematical model describes experimental data adequately.
This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under grant RC0 20000-SC14 and RUC2-20011-ST-04 administered by the Civilian Research and Development Foundation.
References 1. A.A. Kopyrin, M.A. Afonin, A.A. Fomichev, The extraction processes kinetics of REE separation in non-equilibrium conditions, Radiokhimiya (in russian), 2006, v. 48, №5, pp. 412-416.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 A CASE STUDY OF THE GLOBAL AND REGIONAL CS-137 CONTAMINATION IN CONJUGATED ELEMENTARY LANDSCAPES: GEOMORPHOLOGY, SOIL AND PLANT RELATIONSHIP Korobova E.M.
Vernadsky Institute of Geochemistry and Analytical Chemistry, 119991 Moscow, Russia Cs-137 distribution in soils and plants of the conjugated elementary landscapes that characterized different geomorphological positions was studied in the period of 1987-2006 at a number of test sites located in the zones of global and regional contamination (the lower reaches of the Pechora and Yenisey rivers, Bryansk, Gomel and Kiev regions). The studies showed a significant role of the elementary landscape structure in radiocesium fixation and secondary redistribution in soils and plants. Cs-137 proved to be the tracer for natural processes of mass migration in local landscapes.
2496 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, EVALUATION OF BEHAVIOR 241Am IN THE DEEP REPOSITORY OF LIQUID RADIOACTIVE WASTES Kosareva I.M., Savushkina M.K., Lazareva N.I., Viglovskaia O.E.
Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences;
31 Leninskii prospekt, Moscow, 199991 Russia At present the problem of behavior in environment 241Am, the product of radioactive decay 241Pu, is becoming more actual. The question of evaluation of sorption 241Am during the interaction of radio active wastes with rocks of deep repository of liquid radioactive wastes is rather topically.
There are a lot of investigations, devoted to sorption 241Am on inorganic sorbents, soils, rock samples in hydrothermal conditions. However, that area with hydrothermal conditions in repository is restricted, that’s why the question of evaluation of sorption’s properties of the rocks at the tem perature of 20–25°C is very significant.
In this work results of investigation of sorption 241Am on rock samples of the deep repository of liquid radioactive wastes of Siberian Chemical Combine are presented.
Sorption capacity of the rock samples from saltfree solutions and solutions – imitators of the wastes in static conditions on reaching the equilibrium position, depending on pH values and dy namic conditions, that are becoming the first phase of ejection of radioactive wastes, is specified.
The maximum of sorption of 241Am is observing in static conditions from solutions with low quantity of electrolyte. Realization of cycles of sorption – desorption, achieve that sorption ca pacity of 241Am is controlled by picking up the composition of desorption solutions.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 CHANGING OF THE FORMS NEPTUNIUM SUBSISTENCE IN THE LIQUID RADIOACTIVE WASTES DISPOSABLE TO DEEP REPOSITORY Kosareva I.M., Savushkina M.K., Lazareva N.I., Fedoseev A.M., Boldirev V.A.
Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences;
31 Leninskii prospekt, Moscow, 199991 Russia The ecological safety of deep repository of liquid radioactive wastes reached on the assumption of guaranteed localization components of the waste within special area of the bowels. Starting from the only legal index, characterising radiotoxity the nuclides in the water, its obviously that the most potent danger in the waste are transuranic elements, in the liquid phase, because they safety concen trations very low, and half-life periods are very long.
The object of current study is making conditions, guaranteed irreversible transition of the most neptunium to solid phase, providing low equilibrium concentrations of neptunium in subsurface wa ters.
Based on analysis of literature and the results of investigations it’s determined, that capacity for migration of Np (IV) is rather low in comparison Np (V). It’s connected with smaller solubility of hydroxides and ability to form mixed hydroxides with Fe (III) by analogy with Pu (IV).
Because of 237Np in wastes exists mainly in form of neptunoile, – NpO2 + it was worked out the method of getting and stabilisation of Np (IV) in subacid nitrate solutions using applying in radio chemical practice reagents – oxalic acid and Fe(II). Determined concentration features and condi tions of process, providing the total reduction Np(IV) to Np (V).
The realization of this method will allow significantly reduce content of 237Np in liquid phase, and miniaturize area of the repository of liquid radioactive wastes where concentration of 237Np ex ceeds secure level.
2498 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, PERSPECTIVES OF THE IMPROVEMENT OF SPENT NUCLEAR FUEL TREATMENT TECHNOLOGY Kosyakov V.N.
RRC “Kurchatov Institute”, 123182, Kurchatov sq. 1, Moscow, Russia More than 50 years passed since so called Purex-process has been proposed for Spent Nuclear Fuel (SNF) treatment technologies. It’s based on selective extraction of uranium and plutonium by tribu tylphosphate (TBP) and is still applied in all countries. The main disadvantages of the process are well known. There are: enormous amounts of high level radioactive wastes (HLRW) and low radia tion stability of the extractant. Therefore almost all of the users are dealing with its improvent last time. A review of the most efficient approaches and versions of Purex-process improvement pro posed in Russia is presented in the paper.
The analysis of the fission products and actinides yields in the course of reactor operation, taking into account the decay of short-lived radio nuclides for the SNF intermediate storage time, has shown that after 10-15 yrs of storage only 7 chemical elements (Sr, I, Cs, Sm, Np, Am and Cm) are represented by really hazardous highly radioactive nuclides requiring serious isolation from the en vironment. Their sum quantity takes only 15% of the total amount of fission products in SNF. It means that if the advanced technology is designed to recover apart from uranium and plutonium this 7 elements as well, the amount of HLRW, requiring long-time controlled storage, could be reduced by a factor of 6. Just this aim is pursued by the most of the authors trying to improve Purex – proc ess by fractionation and by other modifications of solvent extraction process.
With the transition of the traditional fuel cycle to the higher fuel burn up figures and uranium plutonium fuel application, the specific – activity of the treated solutions increased drastically and a moment could come when even the application of centrifugal extractors could not decrease the extractant destruction and it seems necessary to change the solvent extraction process by a water free, high temperature methods of SNF treatment, which are discussed in the paper as well.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 ELECTROCHEMICAL STABILIZATION OF THE OXIDATION STATES OF RADIOACTIVE ELEMENTS IN THE PROCESSES OF THEIR SEPARATION AND DETERMINATION Kosyakov V.N., Yakovlev N.G.
FSI RRC “Kurchatov Institute”, Kurchatov sq. 1, Moscow, 123182 Russia In modern methods of isolation, separation and determination of radioactive elements redox proc esses including polyvalent ions of these elements are used if possible. The perspectivity of the use of the electrochemical methods for the stabilization of oxidation states of the ions involved is obvi ous. The main advantages are the followings: additional reagents are not added into the solutions;
variable parameters of the electrochemical processes – such as the electrode potential and the cell current – are perfectly fit for the automatization;
redox potential in the separation system could be totally controlled so ensuring the stabilization of the desired oxidation states of the elements. How ever the electron transfer process has a geterogeneous nature and the high electrolysis efficiency could be achieved at high values of the mass transfer coefficients and specific electrode surface, which usually could be realized by three-dimensional electrodes.
The authors have shown the feasibilities of the realization of the electrochemical redox processes in solvent extraction and extraction chromatography systems, and in perticular its use for the deter mination of the radionuclides in the environmental objects. For U, Np and Pu the systems were cho sen and tested, where the using of the electrochemical processes ensures selective quantitative isola tion and subsequent determination of these elements in one probe.
Special attention was paid to the constructive peculiarities of the electrochemical cells and work ing electrodes. The matter is that simultaneously the cell serves as the extraction chromatography column and the working electrode is the carrier of the organic phase. The electrochemical cells used were three sections type and had the volumes of 0.20-1.0 mL. The working electrodes were pre pared from carbon fibres materials (CFM). It was found, that electrodes made from CFM could in tensify the electrochemical processes in 2-3 orders of magnitude due to the high special surface and in 5-10 times due to high values of the mass transfer coefficients.
The results of the investigations of the electrochemical redox processes with the participation of the ions of U, Np, Pu, Am, Cm, Bk and Ce in the phosphporus organic extractant – nitric acid sys tems are presented in this work. Di-2-ethyl hexyl phosphoric acid (HDEHP) and tri-octyl phosphine oxide (TOPO) were used as extractants. The extractants are strongly adsorbed on carbonized elec trode surface, which allows to obtain durable chemically modified electrodes. With the use of CFM as electrodes material the range of working potentials from -0.4 to 1.5 V (NHE) is covered and the following redox transitions could be carried out: U(VI)/U(IV), Np(V)/Np(VI), Np(V)/Np(III), Np(III)/Np(IV), Np(IV)/Np(VI), Pu(IV)/Pu(III), Bk(IV)/Bk(III) and Ce(IV)/Ce(III). The influence of the extractant on the proceeding processes was considered. The main parameters of the investi gated processes were found and the recommendations for practical use of such processes were given.
2500 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, SORPTION OF RADIOACTIVE IODINE, CAESIUM, AND STRONTIUM FROM THE WATER ON LAYERED DOUBLE HYDROXIDES Krasavina E.P., Kulyukhin S.A., Rumer I.A., Mizina L.V., Gorbacheva M.P.
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences;
31 Leninskii prospekt, Moscow, 199991 Russia Human activities in the nuclear power industry leads to contamination of the environment with ra dioactive products, including the most biologically harmful nuclear fuel fission products such as iodine, caesium and strontium radionuclides. Various chemical species of these radionuclides can be sorbed on various natural products, including hydrotalkit minerals. The structure of the minerals includes Mg2+, Al3+, OH- and CO32- ions in various ratios: MgnAl(OH)m[(CO3)1/2·xH2O], were n = or 3;
m = 6 or 8;
x = 1 – 5. Hydrotalkit belongs to the class of layered double hydroxides (LDH), whose structure consists of positively charged hydroxide layers [ M 12+x M x + (OH)2]x+ and anions oc curring in the interlayer space. This suggests the probability of an exchange between the interlayer anions and ionic species of radioactive iodine occurring in the water phase. In addition, the presence of mobile Mg2+ ions in the hydrotalkit lattice suggests the probability of their exchange for radioac tive Cs+ and Sr2+ ions in the water solution.
We studied the sorption of 131I-, 131IO3-, 137Cs+, and 85Sr2+ on LDH of Mg and Al (Mg-Al-LDH) in carbonate (Mg-Al-LDH-CO3) and nitrate (Mg-Al-LDH-NO3) forms. After a 60 minutes’ contact between the liquid and solid phases, the distribution coefficients Kd for 131I- and 131IO3- on the Mg Al-LDH-CO3 solid phase from the water solution were 38 and 34 ml/g, respectively. Under similar conditions, Kd for 131I- and 131IO3- on the Mg-Al-LDH-NO3 solid phase is about 5 ml/g. After a hours’ contact between the liquid and solid phases, Kd for 131I- and 131IO3- on the solid phase of lay ered double oxides (LDO) of Mg and Al (Mg-Al-LDO), which was obtained by thermal decomposi tion of Mg-Al-LDH from water solutions, reached 7999 and 7068 ml/g, respectively.
Virtually no sorption of 85Sr2+ and 137Cs+ from water solutions on the solid phases Mg-Al-LDH CO3, Mg-Al-LDH-NO3, and Mg-Al-LDO was observed (Kd 5 ml/g). The addition of EDTA ions into the structure of the LDH solid phase led to an in increase in Kd for 85Sr2+ from the water solu tion by a factor of more than 20 (Kd are 23.5 and 107 ml/g after 24 and 100 hours’ contact between the liquid and solid phases, respectively). On the other hand, under similar conditions, the addition of EDTA ions to the solution from which the sorption of 85Sr2+ on the Mg-Al-LDO solid phase was carried out, Kd for 85Sr2+ was not higher than 10 ml/g.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 RADIOTRACERS FOR POSITRON EMISSION TOMOGRAPHY:
ROUTINE PRODUCTIONS AND NEW DEVELOPMENTS AT THE IHB RAS Krasikova R.N., Gomzina N.A., Fedorova O.S., Kuznetsova O.F., Rizhikov N.N.
Institute of the Human Brain RAS, 9, Pavolva str, 197376, St.-Petersburg, Russia e-mail firstname.lastname@example.org Positron emission tomography (PET) is the most sensitive non-invasive tool in a medical imaging which provides in-vivo information about complex physiological and biochemical processes (perfu sion, metabolism, receptor and enzyme status and others) in normal and pathology conditions. At the same time PET is the most expensive and complex imaging modality which is in a great extend caused by short half-life of four conventional positron emitting radionuclides, 15O, 13N, 11C and 18F (T1/2 from 2 to 110 min). These radionuclides have to be produced via expensive on-site medical cyclotron closely related to radiochemistry lab for the preparation of PET radiopharmaceuticals (RPs). First PET center in Russia was established in 1991 at the Institute of Human Brain Russian Academy of Sciences (IHB RAS), St.-Petersburg on the base of Scanditronix MC-17 cyclotron ( MeV protons and 8.5 MeV deuterons). Here Anatech RB86 laboratory robot (Anatech, Sweden) is used for routine syntheses of the most important RPs, 2-[18F]-fluorodeoxy-D-glucose (FDG) and L-[methyl-11C] methionine, and applied for researches and development of new RPs. Robotic syn thesis of [18F]FDG is based on well-known Hamacher’s method with modification at the alkali hy drolysis step. It provides well reproducible radiochemical yield of the product (63±3%, EOS (n = 80) in high radiochemical purity within 35 min synthesis time1.
Although [18F]FDG is the most widely used tumor-imaging agent (80% of all PET studies in the world), it has well-known limitations in assessment of brain tumors due to high glucose uptake in a gray matter and inflammation. [18F]fluorinated amino acids (FAA) provide higher contract im ages and allow more accurate characterization of brain tumors. A limiting factor in their implemen tation into clinical routines is difficult synthesis. Therefore a search for new synthetic strategies for the FAA is a “hot spot” in PET radiochemistry.
In cooperation with INEOS RAS, Moscow, new asymmetric synthesis methods for the FAA have been developed. They allow to introduce 18F-label in aromatic ring via multi step nucleophilic synthesis starting from aqueous [18F]fluoride. With this approach 2-18F-fluoro-L-tyrosine and 6-18F fluoro-L-DOPA were prepared in good yields and more than 95% enantiomeric purity2,3, which is essential for PET application. Chain-labeled FAA, O-(2’-[18F]fluoroethyl)-L-tyrosine was prepared via 18F-fluoroethylation of non-protected L-tyrosine using [18F]fluoroethylbromide4. An alternate approach has been direct nucleophilic displacement of tosyl leaving group by 18F-fluoride in new chiral precursor Ni-BPB-Tyr-OCH2CH2OTs. In cooperation with Karolinska Institute, Sweden, new receptor radioligand [18F]flumazenil for PET diagnostics of epilepsy has been introduced6. Due to longer half-life of 18F this radiotracer may replace traditionally used [11C]flumazenil (T1/2 20,4 min).
Acknowledgements The researches on the asymmetric synthesis of [18F]FAA were supported by ISTC grant 2780, SNSF grant 7SUPJO62161.00/1, RFBR grant (OFI 06-03-08089) References 1. N.A.Gomzina, D.A.Vasiliev, R.N.Krasikova, Radiochemistry 2002, 44, 2. R.N. Krasikova, O.S.Fedorova, V.V.Zaitsev, et al., Nucl Med Biol. 2004, 31, 3. O.S. Fedorova, O.F. Kuznetsova, I.K.Mosevich et al., Radiochemistry 2006, 48, 4. N.A.Gomzina, D.A.Vasiliev, R.N.Krasikova, Radiochemistry 2006 (in press) 5. O.F. Kuznetsova, R.N. Krasikova, O.S. Fedorova et al., Quart J Nucl Med MI. 2006, 50, 6. N.N.Ryzhikov, N. Seneca, R.N. Krasikova et al., Nucl Med Biol. 2005, 32, 2502 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, SYNTHESIS AND STUDY OF THE PROPERTIES OF NEW PROMISING MATERIAL, SUPERDISPERSED URANIUM DIOXIDE, FOR MOX-FUEL FABRICATION Krivitsky A.G.a, Manakov I.V.a, Bobilev A.I.a, Rovny S.I.a, Tananaev I.G.b a FSUE “MAYAK” Production Association, 18 Ermolayev str., Ozyorsk, Chelyabinsk Region, Russia;
e-mail: cpl@ po-mayak.ru b A.N. Frumkin Institute of Physical Chemistry and Elelectrochemistry of RAS, Moscow, Russia From the point of view of plutonium dioxide and depleted uranium dioxide incorporation into nu clear fuel cycle, application of the mixed uranium and plutonium oxide (MOX) fuel in the Russian VVER-1000, foreign PWR and Russian fast breeder reactors (BN-600, BN-800) and in Europe is the most promising. In the case when the most common method for MOX-fuel fabrication by oxide mechanic blending, the quality of the sintered pellet is effected by the properties of ceramic compo nents such as UO2 and PuO2. It is acknowledged at the moment that unusual properties of nanomaterials and compositions based on such materials are caused by features of specific particles (crystallites) as well as their col lective behavior that depends on the type of interaction between nanoparticles. The structure and dispersion of the nanomaterial depends strongly on the way of its fabrication2. For the purposes of MOX-fuel fabrication technology improvement with “PAKET” facility at “MAYAK” PA, the way to modify commercial uranium dioxide with superdispersed (nano-) fraction, is offered.
Synthesis of superdispersed uranium powder dioxide was performed with ammonia polyuranate (APU) precipitation from uranylnitrate solution at constant pH. Further thermal processing included APU drying, incineration with air and U3O8 recovery to UO2 in the flow of hydrogen mixed with argon. Sintering and recovery temperature was varied in the range from 600 0C to 800 0C with the purpose of fabrication of powders with different activity3, monitoring of which was based on spe cific surface value SBET. For stabilization of superdispersed powder properties the technique for product passivation with gas mixtures with low oxidation potential, was developed.
As a result of laboratory work samples of superdispersed powders of uranium dioxide with spe cific surface SBET were obtained and tested by varying parameters of APU precipitation and its thermal processing. Mean conditional particle size ("-grain") was (0.12-0.32) m. Physical-and chemical and morphological properties of the produced modified uranium dioxide allowed im provement of ceramic properties (density, porosity, metal distribution homogeneity and uniformity of generated solid solutions) of the MOX-fuel pellet.
The work has been conducted with financial support of the Russian Foundation for Fundamental Research (grant # 07-03-00896).
References 1. A.I. Bobylev et al. Atomic Energy 2003, 95, 301- 2. I.D. Morokhov et al. Superdispersed metal environment. Moscow, Atomizdat Publ., 1977, p. 264.
3. I.S. Kurina Atomic Energy 1999, 86, 189-194.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 ACTINIDE CONTRACTION IN COMPOUNDS OF OXYGENATED ACTINIDE IONS Krot N.N., Charushnikova I.A., Grigoriev M.S.
A. N. Frumkin Institute of Physical Chemistry Chemistry and Electrochemistry, RAS, 31 Leninsky prosp., 119991 Moscow, Russia For the first time single crystals of a number of penta-, hexa- and heptavalent Pu compounds have been obtained, X-ray structural analysis of these crystals has been carried out. A comparison of geometric characteristics of oxygen environment of An atoms has been made for isostructural com pounds in the series U-Np-Pu. A character of the changes in interatomic distances An-O has been determined. Such data are of interest to elucidate the effects of actinide contraction in the com pounds of oxygenated actinide ions AnO2+, AnO22+ and AnO4(OH)23-.
The influence of various ligands (acetate (Ac), oxalate (Ox), triphenylphosphineoxide (TPPO), phthalate (Phthal), carbonate) on the bond lengths in AnO2+ and AnO22+ cations and on other geo metric characteristics of An atom coordination polyhedra has been studied by the examples of the next compounds: SrAnO2(Ac)3·3H2O (An(V) = Np, Pu);
Co(NH3)6AnO2(Ox)2·3H2O (An(V) = Np, Pu);
AnO2(TPPO)4(ClO4)2 (An(VI) = U, Np, Pu);
AnO2(NO3)2(TPPO)2 (An(VI) = U,1 Np, Pu);
Na4AnO2(Phthal)3·nH2O (An(VI) = Np, Pu);
(NH4)4AnO2(CO3)3 (An(VI) = U,2 Np, Pu). On the base of the comparison of geometric characteristics of U, Np and Pu polyhedra in isostructural compounds conclusions have been made about the type of actinide contraction depending on the charge of the dioxocation and the nature of the ligand forming the oxygen environment of the An atom.
By the examples of the complexes of bipyridine (Bipy) benzoates (Benz) and m-nitrobenzoates (Benz-NO2) of actinides the actinide contraction was studied in the compounds with cation-cation (CC) interaction ([AnO2(Bipy)(Benz)]2, An(V) = Np, Pu) and in the compounds without CC inter action ([AnO2(Bipy)(Benz-NO2)(H2O)]·0.5Bipy (An(V) = Np, Pu). It has been shown that a stronger ligand (Benz) promotes formation of CC bonds. At the transition from Np to Pu, the acti nide contraction results in a significant shortening of An-O bonds, especially in the AnO2+ cation, and in an elongation of An–N bonds. The change of the ligand (Benz) for a weaker one (Benz-NO2) results in formation of compounds without CC interaction. The actinide contraction results in a shortening of all bonds in the coordination sphere of An atoms at the transition from Np to Pu.
At the transition from Np(VII) to Pu(VII) in the M3AnO4(OH)2·nH2O (M = K, Cs) salts, the co valent An–O bond lengths in the equatorial planes of the coordination polyhedra – tetragonal bipyramids – are practically unchanged, the distances from the central An atoms to OH-groups be come significantly shorter.
References 1. N. W. Alcock, M. M. Roberts, D. J. Brown, J.C.S., Dalton Trans. 1982, 25.
2. V. N. Serezhkin, M. A. Soldatkina, N. V. Boiko, Zh. Strukturnoy Khimii 1983, 24, 138.
2504 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, USAGE OF TRITUM LABELED HUMIC SUBSTANCES FOR THE STUDY OF THEIR INTERACTION WITH BIOMEMBRANES UNDER OPTIMUM AND SALT STRESS CONDITIONS Kulikova N.A.a, Badun G.A.b, Tyasto Z.A.b, Chernysheva M.G.b, Perminova I.V.b a Department of Soil Science, Lomonosov Moscow State University, Moscow, Russia b Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia Humic substances (HS) are the natural organic compounds comprising 50 to 90% of the organic matter of peat, lignites, sapropels, as well as of the non-living organic matter of soil and water eco systems. The beneficial effects of HS on living organisms have been numerously reported. The mechanism of their action remains unclear, and the ways of HS usage by organisms are also sophis ticated. Problem of bioavailability of HS and their penetration into the cells is even more sophisti cated due to difficulties in HS determination in the presence of other organic substances. In spite of many studies demonstrating HS adsorption onto different biological membranes, there are only a few data on quantitative estimation1,2 or influence of the environment conditions on this process.
The most convenient way is a use of labeled compounds, and the availability of isotope-labeled HS is an important prerequisite to elucidate the fate of the heterogeneous organic matter in complex environments.
Labeling of HS can be accomplished by the addition of a labeled precursor to an unlabeled soil sample during composting3 or by the synthesis of model polymeric compounds under defined con ditions. The latter are synthesized either by enzyme mediated (usually initiated by adding H2O2 in the presence of horseradish peroxidase) oxidative polymerization of phenolic compounds4, or by their spontaneous polymerization in the presence of oxygen or other oxidants, usually at alkaline pH.5 Usage of those techniques, however, does not allow producing labeled preparation completely identical in their properties to the native preparations. Some methods of the direct labeling of HS were therefore developed including labeling of HS with 3H.6 The main advantage of the direct la beling of HS is an opportunity to produce a broad spectrum of isotope-labeled native humics vary ing significantly in both their origin and properties. The objective of the study was to quantify HS interaction with biomembrane using tritium labeled HS and bacteria Escherichia coli as a model under optimum and salt stress conditions.
Six samples of HS originated from coal, peat and soil were examined. Observed values of bio concentration factor of HS by Escherichia coli under optimum and salt stress conditions varied in the range 0.9-13.1 or 0.2-130 l kg-1, respectively, depending considerably on the HS preparation.
Surface activity of HS was demonstrated to be a leading factor determining their both sorption and uptake by bacteria cells.
This research was supported by the grants of the Russian Foundation for Basic Research (#06-03-33036 and #06-04 49017a).
References 1. L. Parent, M.R. Twiss, P.G. Campbell, P.G., Environ. Sci. Technol. 1996, 30, 1713-1720.
2. J.B. Fein, J.-F. Boily, K. Guclu, E. Kaulbach, Chem. Geol. 1999, 162, 33-45.
3. K.M. Haider, J.P. Martin, Soil Biol Biochem. 1988, 20, 425–429.
4. A. Kappler, R. Ji, A. Brune Soil Biol Biochem. 2000, 32, 1271–1280.
5. K.T. Steffen, A. Hatakka, M. Hofrichter, Appl. Environ. Microbiol. 2002, 68, 3442-3448.
6. G.A. Badun, V.Yu. Pozdnyakova, A.V. Kudryavtsev, I.V. Perminova, Bulg. J. of Ecol. Sci. 2003, 2(3-4), 26-27.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 RECOVERY OF URANIUM AND PLUTONIUM FROM SIMULATED SPENT FUEL BY SUPERCRITICAL FLUID EXTRACTION FOLLOWED BY THEIR SEPARATION AND ISOLATION FROM FISSION PRODUCTS BY THE METHOD OF COUNTERCURRENT CHROMATOGRAPHY Kulyako Yu.M., Trofimov T.I., Samsonov M.D., Malikov D.A., Myasoedov B.F.
V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry RAS 119991, GSP-1, Moscow V-334, Kosygin Street, The method of extraction of U and Pu from simulated spent fuel (SSF) by adducts of organic ex tractants with HNO3 with the use of supercritical or subcritical CO2 as an inert solvent followed by separation of U and Pu and their isolation from fission products (FP) by countercurrent chromatog raphy (CCC) is proposed. SSF was solid U(Pu)O2 solution containing 137Cs, 90Sr, 140Ba, 140La, 141 Ce, 147Nd, 95Nb, 95Zr, 103Ru, 131I, 99Tc with their contents corresponding to those in actual spent fuel in water-moderated and fast reactors. Tributyl phosphate, D2EHPA, diethyl ketone, methyl isobutyl ketone (hexone) and N,N’-dimethyl-N,N’-dioctyl hexyl ethoxy malonamide (DMDOHEMA) were used as adducts with HNO3 for direct dissolution of SSF. It was shown that these adducts extract from SSF up to 99% of U and Pu. At that there is formed little volume of an aqueous phase, containing Cs, Sr, Ba, basic quantities of Nb, La, Ce, Nd and Tc (up to 90%). Zir conium (about 60%), iodine and ruthenium (60-80%) pass into adduct phase. Adduct containing U, Pu and residual amount of fission products is separated from aqueous phase by the dissolving of this adduct in environmentally friendly supercritical or subcritical CO2, flow of which transports the desired product into planetary centrifuge. At that decompression occurs and gaseous CO2 leaves the system. Uranium and plutonium are separated and isolated from fission products in the planetary centrifuge by the method of countercurrent chromatography in dynamic mode using stepwise elu tion.
The work was supported by Russian Foundation for Basic Research, grant no. 06-03-32067a.
2506 ХVIII Менделеевский съезд по общей и прикладной химии, Москва, SOLUBILITY OF PLUTONIUM NITRATE IN THE MELT OF URANYL NITRATE Kulyako Yu.M., Trofimov T.I., Samsonov M.D., Shadrin A.Yu., Myasoedov B.F.
V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry RAS 119991, GSP-1, Moscow V-334, Kosygin Street, It was established that Pu(IV) is isomorphically dissolved and distributed uniformly in a mass of uranyl nitrate at Pu(IV) nitrate content in uranyl nitrate up to 20 wt%. It was shown that HNO3 con tent in the mixed U-Pu melt up to 7M does not change solubility of Pu(IV) nitrate in uranyl nitrate.
It was revealed that during dissolution of solid Pu(IV) nitrate in 1-6M HNO3 Pu(IV) disproportion ates into Pu(III) and Pu(VI). At the same time when dissolved in HNO3 solutions with acid concen tration of 10M and more Pu(IV) passes into the solutions in the form of Pu(NO3)62+ and its dispro portionation is not observed.
The work was supported by Russian Foundation for Basic Research, grant # 06-03-32067a.
ХVIII Менделеевский съезд по общей и прикладной химии, Москва, 2007 NEW MATERIALS FOR DECREASING OF RADIOACTIVE IODINE IN THE WATER COOLANT ON THE WORKING AND NEW DEVELOPED NPPS Kulyukhin S.A., Mizina L.V., Rumer I.A., Konovalova N.A.
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences;
31 Leninskii prospekt, Moscow, 199991 Russia Radioactive iodine activity in the water coolant increases in 30-200 times during shutdown of the working WWER or RBMK reactors. At the same time the radioactive iodine content in a gas phase increases more than by the order. Because of oxidation-reduction reactions, radioactive iodine can be present as ionic forms – I-, IO- and IO3-, and as I2 in the coolant. The molecular form of radioac tive iodine brings the basic contribution to pollution of a gas phase since factors of I2 distribution between gas and water phases on some orders are higher, than at ionic forms. The similar effect of increase in the radioactive iodine content in the coolant during shutdown can be observed also as on working (PWR, LWR, BWR), and on new developed (EPR /Framatome ANP/, SWR- /Framatome ANP/, AP-600 and AP-1000 /Westinghouse/, ESBWR /General Electric/, APWR /Mitsubishi/, ABWR /Toshiba and Hitachi/) NPPs.