Download or read book Sp ciations mol culaire et supramol culaire de syst mes d extraction liquide liquide base de malonamide et ou d acides dialkylphosphoriques pour la s paration Actinide III Lanthanide III written by Benoît Gannaz and published by . This book was released on 2006 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: LE SYSTEME D'EXTRACTION LIQUIDE-LIQUIDE UTILISE DANS LE PROCEDE DIAMEX-SANEX, DEVELOPPE POUR LA SEPARATION ACTINIDES(III)/LANTHANIDES(III) EST BASE SUR L'UTILISATION DE MELANGES DU MALONAMIDE DMDOHEMA ET D'UN ACIDE DIALKYLPHOSPHORIQUE (HDEHP OU HDHP), DILUES DANS LE TETRAPROPYLENEHYDROGENE. LA COMPLEXITE DE CES SYSTEMES A CONDUIT A METTRE EN PLACE UNE DEMARCHE ORIGINALE POUR COMPLETER L'APPROCHE CONVENTIONNELLE (THERMODYNAMIQUE, EXTRACTION LIQUIDE-LIQUIDE) QUI NE REND PAS TOUJOURS COMPTE DES PHENOMENES MACROSCOPIQUES (3E PHASE, SUR-STOECHIOMETRIE) OBSERVES. CETTE DEMARCHE A CONSISTE A COMBINER DES ETUDES DE SPECIATIONS SUPRAMOLECULAIRE (VPO, DNPA, DXPA) ET MOLECULAIRE (EXTRACTION LIQUIDE-LIQUIDE, ESI-MS, IR, EXAFS) SUR LES SYSTEMES D'EXTRACTION UNITAIRES (DMDOHEMA OU HDHP DANS LE N-DODECANE) ET SUR LEUR MELANGE. MALGRE LES FORTES CONTRAINTES INHERENTES A LA MANIPULATION D'ISOTOPES RADIOACTIFS, LA PLUPART DE CES TECHNIQUES A ETE MISE EN ŒUVRE AVEC DES RADIOELEMENTS, COMME L'AMERICIUM(III) DANS LES EXPERIENCES DE DXPA, CONSTITUANT UNE PREMIERE MONDIALE. DANS CHAQUE SYSTEME ETUDIE, LES ACTINIDES ET LES LANTHANIDES SONT EXTRAITS EN PHASE ORGANIQUE, AU SEIN DE CŒURS POLAIRES DE MICELLES INVERSES. LES COMPOSITIONS DES SPHERES INTERNES ET EXTERNES DE CES ESPECES SONT PROPOSEES. AINSI, LES CATIONS METALLIQUES 4F OU 5F SONT EXTRAITS, PAR LES SYSTEMES A UN EXTRACTANT, DANS DES MICELLES INVERSES : [(DMDOHEMA)2M(NO3)3]INT[(DMDOHEMA)X(HNO3)Z(H2O)W]EXT ET M(DHP)3(HDHP)Y-3(H2O)W AVEC Y = 3 A 6. DANS LE CAS DU MELANGE, L'EXTRACTANT MINORITAIRE JOUE LE ROLE DE CO-SURFACTANT LORS DE LA FORMATION D'AGREGATS MIXTES [(DMDOHEMA)2M(NO3)3-V(DHP)V]INT[(DMDOHEMA)X(HDHP)Y(HNO3)Z(H2O)W]EXT.]ext.

Download or read book Advanced Extraction Methods for Actinide written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The separation of An(III) ions from chemically similar Ln(III) ions is perhaps one of the most difficult problems encountered during the processing of nuclear waste. In the 3+ oxidation states, the metal ions have an identical charge and roughly the same ionic radius. They differ strictly in the relative energies of their f- and d-orbitals, and to separate these metal ions, ligands will need to be developed that take advantage of this small but important distinction. The extraction of uranium and plutonium from nitric acid solution can be performed quantitatively by the extraction with the TBP (tributyl phosphate). Commercially, this process has found wide use in the PUREX (plutonium uranium extraction) reprocessing method. The TRUEX (transuranium extraction) process is further used to coextract the trivalent lanthanides and actinides ions from HLLW generated during PUREX extraction. This method uses CMPO [(N, N-diisobutylcarbamoylmethyl) octylphenylphosphineoxide] intermixed with TBP as a synergistic agent. However, the final separation of trivalent actinides from trivalent lanthanides still remains a challenging task. In TRUEX nitric acid solution, the Am(III) ion is coordinated by three CMPO molecules and three nitrate anions. Taking inspiration from this data and previous work with calix[4]arene systems, researchers on this project have developed a C3-symmetric tris-CMPO ligand system using a triphenoxymethane platform as a base. The triphenoxymethane ligand systems have many advantages for the preparation of complex ligand systems. The compounds are very easy to prepare. The steric and solubility properties can be tuned through an extreme range by the inclusion of different alkoxy and alkyl groups such as methyoxy, ethoxy, t-butoxy, methyl, octyl, t-pentyl, or even t-pentyl at the ortho- and para-positions of the aryl rings. The triphenoxymethane ligand system shows promise as an improved extractant for both tetravalent and trivalent actinide recoveries form high level liquid wastes and a general actinide clean-up procedure. The selectivity of the standard extractant for tetravalent actinides, (N, N-diisobutylcarbamoylmethyl) octylphenylphosphineoxide (CMPO), was markedly improved by the attachment of three CMPO-like functions onto a triphenoxymethane platform, and a ligand that is both highly selective and effective for An(IV) ions was isolated. A 10 fold excess of ligand will remove virtually all of the 4+ actinides from the acidic layer without extracting appreciable quantities of An(III) and Ln(III) unlike simple CMPO ligands. Inspired by the success of the DIAMEX industrial process for extractions, three new tripodal chelates bearing three diglycolamide and thiodiglycolamide units precisely arranged on a triphenoxymethane platform have been synthesized for an highly efficient extraction of trivalent f-element cations from nitric acid media. A single equivalent of ligand will remove 80% of the Ln(III) ion from the acidic layer since the ligand is perfectly suited to accommodate the tricapped trigonal prismatic geometry preferred by the metal center. The ligand is perhaps the most efficient binder available for the heavier lanthanides and due to this unique attribute, the extraction event can be easily followed by 1H NMR spectroscopy confirming the formation of a TPP complex. The most lipophilic di-n-butyl tris-diglycolamide was found to be a significantly weaker extractant in comparison to the di-isopropyl analogs. The tris-thiodiglycolamide derivative proved to be an ineffective chelate for f-elements and demonstrated the importance of the etheric oxygens in the metal binding. The results presented herein clearly demonstrate a cooperative action of these three ligating groups within a single molecule, confirmed by composition and structure of the extracted complexes, and since actinides prefer to have high coordination numbers, the ligands should be particularly adept at binding with three arms. The use of such an extractant permits the extraction of metal ions form highly acidic environment through the ability of the compound to buffer the effect of high acid concentration. Stability toward hydrolysis and ease of synthesis and purification are additional favorable properties. The ligands describe above based on the triphenoxymethane platform are not only easily available in large quantities but also amenable to nearly unlimited chemical modifications. Finally, with this platform, two highly effective ligands incorporating CMPO and glycoldiamide moieties have been prepared and fully characterized, and both examples are perhaps the most efficient and selective examples of these important classes of ligands. Continued refinements of these systems have the potentially further improve the selectivity and affinity for An(III) ions.

Download or read book Comparaison de diff rentes m thodes d investigation sur les cin tiques de transfert en extraction liquide liquide written by Sandrine Colombani and published by . This book was released on 2000 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: En extraction liquide-liquide, les études cinétiques font appel à de nombreuses techniques, dont le choix semble plus conjoncturel que scientifique. Par ailleurs, la comparaison des résultats publiés concernant un même système chimique et différentes techniques est complexe. Les objectifs de ce travail sont une meilleure compréhension des phénomènes de transfert et la proposition d’une méthodologie pour les étudier. L’extraction du fer (III) en milieu chlorhydrique par le TBP est étudiée avec trois dispositifs choisi à l’issue d’une bibliographie critique : une cellule à aire interfaciale constante de type ARMOLLEX, un dispositif de colonnes à goutte unique et une cellule homothétique fortement agitée. L’étude thermodynamique de l’extraction a montré que le complexe extrait est HFeCl4(TBP)55h2O)n. Un mécanisme original est proposé et validé pour expliquer cette stœchiométrie inhabituelle. Une étude comparative de l’influence des paramètres hydrodynamiques sur la cinétique d’extraction permet de déterminer l’existence d’un régime mixte en cellule ARMOLLEX (coexistence d’une résistance diffusionnelle en phase organique et d’une résistance interfaciale chimique) et d’un régime chimique en goutte unique. Les études effectuées montrent que le système Fe(III)-HCI/TBP-dodécane est réversible thermodynamiquement et cinétiquement. Les mécanismes réactionnels proposés ont pour étape limitante la formation du complexe interfacial HFeCl4(TBP)2. Un essai en cellule homothétique fortement agitée montre que ce système est trop rapide pour être étudié à l’aide de cette technique. L’apparente indépendance de la cinétique de transfert par rapport aux paramètres hydrodynamiques, souvent associée à l’atteinte du régime chimique en cellule à aire interfaciale constante, est remise en question. La nécessité de confirmer la nature du régime de transfert par une autre technique telle que la goutte unique est démontrée. Une méthodologie des études cinétiques est proposée.

Download or read book Extraction of Actinide III IV V VI Ions and TcO4 ByN N N N Tetraisobutyl 3 oxa glutaramide written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The extraction behavior of U(VI), Np(V), Pu(IV), Am(III), and TcO4− with N, N, N', N'-tetraisobutyl-3-oxa-glutaramide (TiBOGA) were investigated. An organic phase of 0.2 mol/L TiBOGA in 40/60% (V/V) 1-octanol/kerosene showed good extractability for actinides (III, IV, V VI) and TcO4−from aqueous solutions of HNO3 (0.1 to 4 mol/L). At 25 C, the distribution ratio of the actinide ions (D{sub An}) generally increased as the concentration of HNO3 in the aqueous phase was increased from 0.1 to 4 mol/L, while the D{sub Tc} at first increased, then decreased, with a maximum of 3.0 at 2 mol/L HNO3. Based on the slope analysis of the dependence of D{sub M} (M = An or Tc) on the concentrations of reagents, the formula of extracted complexes were assumed to be UO2L2(NO3)2, NpO2L2(NO3), PuL(NO3)4, AmL3(NO3)3, and HL2(TcO4) where L = TiBOGA. The enthalpy and entropy of the corresponding extraction reactions, [Delta]{sub r}H and [Delta]{sub r}S, were calculated from the dependence of D on temperature in the range of 15-55 C. For U(VI), Np(V), Am(III) and TcO4−, the extraction reactions are enthalpy driven and disfavored by entropy ([Delta]{sub r}H 0 and [Delta]{sub r}S 0). In contrast, the extraction reaction of Pu(IV) is entropy driven and disfavored by enthalpy ([Delta]{sub r}H 0 and [Delta]{sub r}S 0). A test run with 0.2 mol/L TiBOGA in 40/60% 1-octanol/kerosene was performed to separate actinides and TcO4− from a simulated acidic high-level liquid waste (HLLW), using tracer amounts of 238U(VI), 237Np(V), 239Pu(VI), 241Am(III) and 99TcO4−. The distribution ratios of U(VI), Np(V), Pu(VI), Am(III) and TcO4− were 12.4, 3.9, 87,> 1000 and 1.5, respectively, confirming that TiBOGA is a promising extractant for the separation of all actinides and TcO4− from acidic HLLW. It is noteworthy that the extractability of TiBOGA for Np(V) from acidic HLLW (D{sub Np(V)} = 3.9) is much higher than that of many other extractants that have been studies for the separation of actinides from HLLW.

Download or read book ETUDE PAR RMN DE LA CONFORMATION DES EXTRACTANTS A FONCTION AMIDE EN PHASE ORGANIQUE written by Claude Berthon and published by . This book was released on 1993 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: CETTE ETUDE SE SITUE DANS LE CADRE DU RETRAITEMENT DES DECHETS RADIOACTIFS ET A ESSENTIELLEMENT FAIT APPEL A LA RMN. NOUS NOUS SOMMES INTERESSES AUX FACTEURS CONFORMATIONNELS AFIN DE COMPRENDRE LES PHENOMENES QUI CONTROLENT LA SELECTIVITE ET L'EFFICACITE DES EXTRACTANTS A FONCTION AMIDE. LES MONOAMIDES SYMETRIQUES SELECTIONNES DOBA (C#3H#7CON(CH#2CH(C#2H#5)C#4H#9)#2), DOIBA ((CH#3)#2CCHON(CH#2CH(C#2H#5)C#4H#9)#2) ET DOTA ((CH#3)#3CCH#2CON(CH#2CH(C#2H#5)C#4H#9)#2) EXISTENT EN PHASE ORGANIQUE SOUS FORME DE DEUX CONFORMERES QUASI EQUIVALENTS CIS ET TRANS. LE MALONAMIDE SELECTIONNE DMDBTDMA ((C#4H#9(CH#3)NCO)#2CHC#1#4H#2#9) PRESENTE QUATRE CONFORMERES EN RAISON DE LA DISSYMETRIE DE SES DEUX FONCTIONS AMIDES. DES INTERACTIONS FAIBLES ENTRE MOLECULES ET MONOAMIDES PERMETTENT LEUR ASSOCIATION SOUS FORME DE DIMERES. LE MALONAMIDE DONNE NON SEULEMENT DES DIMERES MAIS AUSSI DES AGREGATS. LA MODELISATION DE L'EXTRACTION DE L'ACIDE NITRIQUE A PERMIS DE DECRIRE LE SYSTEME EN PRENANT EN COMPTE SIX ESPECES CHIMIQUES: L,L#2,L#2(HNO#3),L(HNO#3),L(HNO#3)#2,L(HNO#3)#3 (L ETANT UN MONOAMIDE). LES LANTHANIDES (LN: LANTHANIDE) TRIVALENTS SONT COMPLEXES PAR LES MONOAMIDES SOUS LA FORME DE COMPLEXES NEUTRES L#3LN(NO#3)#3 ET L#2LN(NO#3)#3. LEUR PROPORTION DEPEND DE L'ENCOMBREMENT STERIQUE SUR LE CARBONYLE ET DU RAYON IONIQUE DU METAL. CECI EST AUSSI OBSERVE POUR L'EXTRACTION EN MILIEU FAIBLEMENT ACIDE DE PU#4#+ ET TH#4#+ PAR LES MONOAMIDES. LE COMPLEXE MAJORITAIRE EST: L#2AN(NO#3)#4 (AN: ACTINIDE) SAUF POUR LE SYSTEME TH#4#+-DOBA OU APPARAIT L'ESPECE SUPPLEMENTAIRE (DOBA)#3TH(NO#3)#4. DES CINETIQUES D'ECHANGE ENTRE LA MOLECULE D'EXTRACTANT ET LE COMPLEXE SONT OBSERVES. DES DIFFERENCES CONFORMATIONNELLES CARACTERISTIQUES DES COMPLEXES DE LANTHANIDES ET D'ACTINIDES PERMETTENT D'EXPLIQUER POURQUOI LES AN#4#+ SONT EXTRAITS ET PAS LES LN#3#+

Download or read book Sp ciation dans les phases organiques des syst mes d extraction liquide liquide contenant un malonamide et un acide dialkylphosphorique written by Julie Muller and published by . This book was released on 2012 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: Le but de la thèse est d’améliorer la compréhension des équilibres chimiques mis en jeu lors de l’extraction des actinides(III) et des lanthanides(III) dans le procédé hydrométallurgique DIAMEX-SANEX de retraitement du combustible nucléaire usé. Il s’agit de décrire au mieux les différents équilibres chimiques pour améliorer la modélisation des propriétés extractantes de ce procédé. La phase organique est constituée d’un mélange d’extractants : un malonamide, le DMDOHEMA, et un acide dialkylphosphorique, le HDEHP, dilués dans un alcane. Ce mélange extractant présente un comportement singulier comparé au comportement des deux extractants seuls. On observe un effet synergique vis-à-vis de l’extraction d’Eu(III) et Am(III) en milieu acide (HNO3 ≈ 1 mol/L en phase aqueuse) et un effet antagoniste à faible acidité (pH

Download or read book Principles of Polarography written by Jaroslav Heyrovský and published by Elsevier. This book was released on 2013-09-11 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Polarography is a revised and extended version of an original Czech edition that appeared in 1962 at the Publishing House of the Czechoslovak Academy of Sciences in Prague. Based on a one-term course of lectures for third-year students of chemistry at the Charles University it brings the fundamental results of more than forty years' research in the field of polarography. The book contains 22 chapters and opens with a discussion of the principles of polarography. This is followed by separate chapters on polarizable electrodes used in polarography; charging current; influence of the resistance of the electrolyte on polarographic curves; migration and diffusion-controlled currents; and equation of a reversible polarographic wave. Subsequent chapters deal with reversible processes controlled by diffusion of complex ions; reversible reduction of organic substances; deposition of mercury ions; irreversible electrode processes; applications of limiting currents; polarographic curves for the formation of semiquinones and dimers; and catalytic hydrogen currents.

Download or read book Scientific Basis for Nuclear Waste Management XXII Volume 556 written by David J. Wronkiewicz and published by . This book was released on 1999-11-24 with total page 1370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Safe and effective management of nuclear waste provides a broad range of challenges for materials science. Waste processing, waste form and engineered barrier properties, interactions between engineered and geological systems, radiation effects, chemistry and transport of waste species, and long-term predictions of repository performance are just some of the scientific problems facing modern society. This book, the 22nd in a very successful series from MRS, offers an international and inter-disciplinary perspective on the issues, and features developments in both fundamental and applied areas. Topics include: development and characterization of ceramic waste forms; ceramic waste form corrosion; glass waste form processing; glass formulation, properties and structure; glass waste form corrosion; spent nuclear fuel; performance assessment; repository backfill; flow and transport; natural analogues; container corrosion; metal waste form corrosion; radionuclide speciation and solubility; radionuclide sorption; microbial effects; radiation effects; cement waste forms and waste treatment.

Download or read book Scientific Basis for Nuclear Waste Management XXIII Volume 608 written by Robert W. Smith and published by . This book was released on 2000-10-09 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt: This long-standing symposia series has become the premier, international forum for scientific and engineering issues related to all levels and types of radioactive wastes and their management. Topics include: fuel cladding and spent nuclear fuel; container fabrication and corrosion; performance assessment; repository performance; radionuclide sorption and transport; cement-based materials and waste containment; corrosion of ceramic wasteforms; structure and characterization of ceramics; radiation effects; natural analogs; wasteform characterization and processing; and corrosion and characterization of glass wasteforms.

Download or read book Desorption Mass Spectrometry written by Philip A. Lyon and published by . This book was released on 1985 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridges the gap between SIMS and FAB mass spectrometry. Focuses on surface techniques that can use either SIMS or FAB mass spectrometry. Includes fundamentals, instrumental design, and applications. Demythologizes particle bombardment by addressing both the chemistry and physics involved.