[en] Full text of publication follows. To improve the recycling of nuclear fuel (as well as the reducing of the volume and the toxicity of ultimate waste), different actinide separations have been considered. Specific families of molecules were selected considering several criteria; among them the performance in terms of chemical affinity and selectivity towards the actinide target was important. The design and/or the optimization of new ligands could be improved with a deep understanding of actinides distribution and of the selectivity. N, N-dialkyl-amides RR'N-C(O)-R'' belong to a classical family of extractants which have been proposed some years ago to selectively separate uranium(VI) and plutonium(IV). The influence of the alkyl groups R, R' and R'' on the extraction and physico-chemical properties has already been discussed. But the relation between a macroscopic behavior of a solvent extraction system and the molecular contributions is difficult to obtain with high solute concentrations. In order to increase the knowledge in this field, a large number of investigations have been applied on the same extraction systems (3 reference dialkyl-amides): -) Thermodynamic data (free energy ΔextG0, enthalpy ΔextH0 and entropy ΔextS0) were acquired by the classical Van't Hoff method and by direct calorimetry to provide the enthalpies of extraction and also specific heats; -) Dedicated methods like electro-spray ionization mass spectrometry analysis and X-ray diffraction on single crystals provide information about the stoichiometry of the extracted species; -) Spectroscopic investigations with UV-visible absorption, Fourier transform infrared and XAS experiments combined with theoretical calculations probed the actinide coordination in the inner sphere. The results obtained will be discussed to identify the origin of the different affinities between ligands and the difference of selectivity between cations. (authors)
Source
Societe Francaise d'Energie Nucleaire - SFEN, 103 rue Reaumur, 75002 Paris (France); 2455 p; ISBN 978-1-4951-6286-2; 
; 2015; p. 1646; GLOBAL 2015: Nuclear fuel cycle for a low-carbon future; Paris (France); 21-24 Sep 2015; Available (USB stick) from: SFEN, 103 rue Reaumur, 75002 Paris (France)
; 2015; p. 1646; GLOBAL 2015: Nuclear fuel cycle for a low-carbon future; Paris (France); 21-24 Sep 2015; Available (USB stick) from: SFEN, 103 rue Reaumur, 75002 Paris (France)
[en] The hexa-cyano-metallate family is well known in transition metal chemistry because the remarkable electronic delocalization along the metal-cyano-metal bond can be tuned in order to design systems that undergo a reversible and controlled change of their physical properties. We have been working for few years on the description of the molecular and electronic structure of materials formed with [Fe(CN)6]n- building blocks and actinide ions (An Th, U, Np, Pu, Am) and have compared these new materials to those obtained with lanthanide cations at oxidation state +III. In order to evaluate the influence of the actinide coordination polyhedron on the three-dimensional molecular structure, both atomic number and formal oxidation state have been varied: oxidation states +III, +IV. EXAFS at both iron K edge and actinide L-III edge is the dedicated structural probe to obtain structural information on these systems. Data at both edges have been combined to obtain a three-dimensional model. In addition, qualitative electronic information has been gathered with two spectroscopic tools: UV-Near IR spectrophotometry and low energy XANES data that can probe each atom of the structural unit: Fe, C, N and An. Coupling these spectroscopic tools to theoretical calculations will lead in the future to a better description of bonding as 5f orbitals are being filled by modification of oxidation state and/or atomic number. (authors)
Journal
IOP Conference Series. Materials Science and Engineering (Online); ISSN 1757-899X; ; v. 9(no.1); p. 1-11
; v. 9(no.1); p. 1-11
[en] Ruthenium extraction with uranium and plutonium during the reprocessing of nuclear used fuel is an important element to follow because its presence leads to a decrease of the decontamination factors and causes enhanced radiolysis of the solvent. A study was carried out on the speciation of ruthenium in both aqueous and organic phases by complementary spectroscopic techniques such as Fourier Transform Infrared spectroscopy (FTIR) and X-ray absorption spectroscopy. The results show a different Ru extraction behavior depending on the initial HNO_3 conditions (1 M - 4 M). It also provides evidence of a second shell TBP-Ru complexation. By providing a better understanding of the ruthenium extraction mechanism, this study will help to support the modeling of related processes
Journal
Procedia Chemistry; ISSN 1876-6196; ; v. 21; p. 54-60
; v. 21; p. 54-60
[en] Highlights: • An extraction method based on the cationic properties of VEN was successfully developed. • The non-targeted approach allowed the identification of new VEN metabolites in mussels. • OH-VEN was the predominant metabolite detected in VEN-exposed mussels. Exposure of aquatic organisms to antidepressants is currently well documented, while little information is available on how wild organisms cope with exposure to these pharmaceutical products. Studies on antidepressant metabolism in exposed organisms could generate information on their detoxification pathways and pharmacokinetics. The goal of this study was to enhance knowledge on the metabolism of venlafaxine (VEN)—an antidepressant frequently found in aquatic ecosystems—in Mytilus galloprovincialis, a bivalve that is present worldwide. An original tissue extraction technique based on the cationic properties of VEN was developed for further analysis of VEN and its metabolites using targeted and non-targeted approaches. This extraction method was assessed in terms of recovery and matrix effects for VEN metabolites. Commercial analytical standards were applied to characterize metabolites found in mussels exposed to 10 μg/L VEN for 3 and 7 days. Targeted and non-targeted approaches using liquid chromatography (LC) combined with high-resolution mass spectrometry (HRMS) were implemented to screen for expected metabolites based on the literature on aquatic species, and for metabolites not previously documented. Four venlafaxine metabolites were identified, namely N-desmethylvenlafaxine and O-desmethylvenlafaxine, which were clearly identified using analytical standards, and two other metabolites revealed by non-target analysis. According to the signal intensity, hydroxy-venlafaxine (OH-VEN) was the predominant metabolite detected in mussels exposed for 3 and 7 days.
Journal
[en] Actinide elements, all radioactive, are present on Earth for a period several orders of magnitude longer than the life cycle of a human being. Their toxicology is therefore a societal issue, even in the absence of accidental nuclear events. Since the first studies conducted during World War II, actinide toxicologists have studied their retention and excretion rates, their physiological impact in case of exposure and their main biological targets. With the increasing access to unconventional spectroscopic and analytical tools and the growing role of modeling and structural biology, the understanding of the impact of actinides on living organisms at the biomolecular level has improved. The modes of interaction with metabolites and proteins, from a thermodynamic and structural point of view as well as their biological activity, have been better and better described. This also means understanding the mechanisms of complexation and the influence of physicochemical form on affinity, exploring their consequences on the function of proteins/enzymes for certain targets. This article covers twenty years of so-called 'bio-actinide chemistry' with a selection of examples, illustrating the complementarity of the scientific disciplines involved
Journal
Actualite Chimique; ISSN 0151-9093; ; v. 460-461; p. 68-75
; v. 460-461; p. 68-75
[en] The hexacyanometallate family is well known in transition metal chemistry because the remarkable electronic delocalization along the metal-cyano-metal bond can be tuned in order to design systems that undergo a reversible and controlled change of their physical properties. We have been working for few years on the description of the molecular and electronic structure of materials formed with [Fe(CN)6]n- building blocks and actinide ions (An = Th, U, Np, Pu, Am) and have compared these new materials to those obtained with lanthanide cations at oxidation state +III. In order to evaluate the influence of the actinide coordination polyhedron on the three-dimensional molecular structure, both atomic number and formal oxidation state have been varied : oxidation states +III, +IV. EXAFS at both iron K edge and actinide LIII edge is the dedicated structural probe to obtain structural information on these systems. Data at both edges have been combined to obtain a three-dimensional model. In addition, qualitative electronic information has been gathered with two spectroscopic tools : UV-Near IR spectrophotometry and low energy XANES data that can probe each atom of the structural unit : Fe, C, N and An. Coupling these spectroscopic tools to theoretical calculations will lead in the future to a better description of bonding in these molecular solids. Of primary interest is the actinide cation ability to form ionic - covalent bonding as 5f orbitals are being filled by modification of oxidation state and/or atomic number.
Journal
IOP Conference Series. Materials Science and Engineering (Online); ISSN 1757-899X; ; v. 9(1); [11 p.]
; v. 9(1); [11 p.]