Thèses sur le sujet « Ion-solvent »
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1
Dakua, Vikas Kumar. « Physico-chemical studies on interactions between ion-solvent, ion-ion and solvent-solvent in aqueous and non-aqueous pure and mixed solvent systems ». Thesis, University of North Bengal, 2008. http://hdl.handle.net/123456789/707.
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Chimpalee, Dolrudee. « Applications of ion-pair solvent extraction ». Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336039.
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Haldar, Purushottam. « Ion-ion and ion-solvent interactions for same 1:1 electrolytes in 2 ethoxyethanol and its binary mixtures with water ». Thesis, University of North Bengal, 2006. http://hdl.handle.net/123456789/708.
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Das, Susanta. « Studies on ion-solvent interactions of electrolytes in solution ». Thesis, University of North Bengal, 1986. http://hdl.handle.net/123456789/730.
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Oesterle, Matthew John. « Silver ion and solvent effects on polystyrene photochemistry ». Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/27565.
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Ghosh, Saroj Kumar. « STUDIES ON THE ION-SOLVENT INTERACTIONS OF ELECTROLYTES AND RELATED STRUCTURAL CHANGES IN AQUO-ORGANIC SOLVENTS ». Thesis, University of North Bengal, 1989. http://hdl.handle.net/123456789/725.
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Roy, Mahendra Nath. « Studies on the ion-solvent interactions of some tetraalkylammonium and common ions in non-aqueous and mixed solvents ». Thesis, University of North Bengal, 1993. http://hdl.handle.net/123456789/740.
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Saha, Nirmal. « Ion-solvent interactions of some symmetrical Tetraalkylammonium Bromides in Acetonitrile methanol and their binary mixtures ». Thesis, University of North Bengal, 2001. http://hdl.handle.net/123456789/700.
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Cattrall, R. W. « Studies in solvent extraction chemistry and ion-selective electrodes / ». Title page and contents only, 1985. http://web4.library.adelaide.edu.au/theses/09SD/09sdc369.pdf.
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Choi, Jong-Ho Okumura Mitchio Okumura Mitchio. « Infrared spectroscopy of molecular ions and ion-solvent clusters / ». Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-09252007-09111.
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Muhuri, Prakash Kumar. « Studies on the ion-solvent interactions of some electrolytes in propylene carbonate and its binary mixtures with other organic solvent systems ». Thesis, University of North Bengal, 1993. http://hdl.handle.net/123456789/710.
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Atkins, Penelope (Kelly). « Ion solvation in organic solvent mixtures relevant to lithium batteries ». Thesis, Atkins, Penelope (Kelly) (1989) Ion solvation in organic solvent mixtures relevant to lithium batteries. PhD thesis, Murdoch University, 1989. https://researchrepository.murdoch.edu.au/id/eprint/51779/.
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The solvation of lithium ions in mixed nonaqueous solvents relevant to organic electrolyte lithium batteries has been investigated. The solvents studied were propylene carbonate (PC) and its mixtures with 1,2-dimethoxyethane (DME), tetrahydrofuran (THE), and acetonitrile (AN) over the entire composition range wherever In order possible. to provide a suitable context in which to evaluate Li+ solvation, other alkali metal ions and the silver ion were also studied.
The literature of ion solvation in mixed organic solvents was reviewed and literature data included for comparison with experimental results...
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Wang, Ying. « Solvent uptake and swelling by a PS-DVB column packing and metal ion speciation by microdrop solvent extraction ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0009/NQ59693.pdf.
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Ghosh, Debapratim. « Studies on the behaviour of polyelectrolytes & ; their interaction with small ion & ; surfactant in mixed solvent ». Thesis, University of North Bengal, 2009. http://hdl.handle.net/123456789/1380.
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Bauer, Caroline. « Metal ion extractant in microemulsion : where solvent extraction and surfactant science meet ». Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20041/document.
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Le but du travail est d'étudier la structure supramoléculaire de mélanges de tensioactif hydrophile, n-octyl-beta-glucoside (C8G1), et d'un extractant d'ions métalliques hydrophobe, le tributyl-n-phosphate (TBP), en présence d'eau, d'huile et de sels. Les systèmes classiques d'extraction ionique (composés d'une phase aqueuse, d'huile et d'extractant dont le but est d'extraire un soluté de la phase polaire sont passés en revue. L'aspect colloïdal et les transitions de phases que l'on retrouve dans ces systèmes sont souvent décrits singulièrement. Nous avons transposé l'approche « diagramme de phases » issue de la physico-chimie des systèmes moléculaires organisés à ces systèmes d'extractant afin d'orienter globalement l'analyse de ces systèmes complexes. La discussion est basée sur des considérations géométriques. Un modèle thermodynamique a été développé en considérant les contraintes d'empilement des ces extractants dans le film moléculaire formant les micelles inverses d'extractant dans l'huile. Ce modèle a permis de prédire la solubilité de l'eau au sein de ces micelles inverses ainsi que leurs tailles obtenues expérimentalement. Dans une deuxième partie, le comportement physico-chimique des phases aqueuses et organiques composées respectivement d'eau/C8G1 et de TBP/huile/eau ont été étudiées, en s'intéressant particulièrement aux effets de sels, par des techniques de diffusion de rayons X aux petits angles, diffusion dynamique de la lumière et de spectroscopie UV-visible. Dans la dernière partie la description complète de la microémulsion en faisant varier la balance hydrophile-hydrophobe du mélange C8G1 et TBP a été obtenue en combinant des mesures de diffusion de neutrons aux petits angles et d'analyse chimique (Karl-Fischer, Carbone Organique Total, ICP-OES…). Le comportement co-surfactant du TBP a été déterminé par comparaison aux co-surfactants classiques que sont les n-alcools (4The presented work describes the supramolecular structure of mixtures of a hydrophilic surfactant n-octyl-beta-glucoside (C8G1), and the hydrophobic metal ion extractant tributylphosphate (TBP) in n-dodecane/water as well as in the presence of salts.In the first part, basic solvent extraction system, composed of water, oil and extractant, will be introduced. The focus, however, lies on the extraction of multivalent metal ions from the aqueous phase. During this extraction process and in the following thermodynamic equilibrium, aggregation and phase transition in supramolecular assemblies occur, which are already described in literature. Notably, these reports rest on individual studies and specific conclusions, while a general concept is still missing. We therefore suggest the use of generalized phase diagrams to present the physico-chemical behaviour of (amphiphilic) extractant systems. These phase diagrams facilitated the development of a thermodynamic model based on molecular geometry and packing of the extractant molecules in the oil phase. As a result, we are now in the position to predict size and water content of extractant aggregates and, thus, verify the experimental results by calculation.Consequently, the second part presents a systematic study of the aqueous and organic phase of water/C8G1 and water/oil/TBP mixtures. The focus lies on understanding the interaction between metal ions and both amphiphilic molecules by means of small angle x-ray scattering (SAXS), dynamic light scattering (DLS) and UV-Vis spectroscopy. We confirmed the assumption that extraction of metal ions is driven by TBP, while C8G1 remains passive. In the third and last part, microemulsions of C8G1, TBP, water (and salt) and n-dodecane are characterized by small angle neutron scattering (SANS), and chemical analytics (Karl Fischer, total organic carbon, ICP-OES,...). The co-surfactant behaviour of TBP was highlighted by comparison to the classical n-alcohol (4
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Sinha, Anuradha. « Investigation on viscous synergy and antagonism of some liquid mixtures and ion-solvent interaction of some compounds in various solvent systems ». Thesis, University of North Bengal, 2006. http://hdl.handle.net/123456789/705.
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Booker, Nicholas Anthony. « Removal of cadmium from wet process phosphoric acid by cation exchange ». Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47365.
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Khan, Simi. « Reactive solvent extraction of #beta#-lactams and some theoretical aspects of ion pairing ». Thesis, London South Bank University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280769.
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Jayasinghe, Nivari School of Chemical Engineering & Industrial Chemistry UNSW. « Ion exchange equilibria of the gold cyanide complex in aqueous and mixed solvent environments ». Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/23056.
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Ion exchange equilibria are presented for [ ]??? ??? Au(CN)2 / Cl , [ ]??? ??? Au(CN)2 / SCN and SCN??? / Cl??? in aqueous solution, and in various mixed solvents, at 303K using Purolite A500 as the ion-exchanger. The mixed solvents investigated include water-acetone, water-dimethylsulfoxide (DMSO) and water-N-methyl-2-pyrrolidone (NMP). In aqueous solution, the selectivity of Purolite A500 for a given anion increases in the order: [ ]??? ??? < ??? < Cl SCN Au(CN)2 . This selectivity sequence confirms the high affinity of the ion exchange resin for the [ ]??? Au(CN)2 species. In mixed solvents, however, the selectivity of Purolite A500 for [ ]??? Au(CN)2 decreases with an increase in the composition of the organic solvent in the external solution. Mixed solvents containing greater than 60 mol% organic solvent are preferred for the displacement of [ ]??? Au(CN)2 from the resin. The effectiveness of a given type of mixed solvent generally increases in the following order: DMSO &it acetone &it NMP. The ion exchange equilibria are correlated using the Law of Mass Action, modified with activity coefficients, to determine the equilibrium constant for each binary system. The fitted values of the equilibrium constants are consistent with the trends observed in the ion exchange isotherms. The accuracy of the correlation results in the mixed solvent systems range from 1 to 10% and this is similar to the level of accuracy obtained for the ion exchange equilibria in aqueous solution. From these results it can be concluded that the Law of Mass Action is equally valid in mixed solvent systems. The variation in the equilibrium constant with mixed solvent composition, for a given binary system, correlates well with the dielectric constant of the mixed solvent. For a given value of the dielectric constant, however, the equilibrium constant, however, the equilibrium constant is dependent on the type of mixed solvent. A fundamental relationship is derived between the equilibrium constants and the Gibbs energies of transfer associated with the solvation of the ions in the mixed solvents. Based on this relationship, the redistribution of ions between the pore solution and the bulk mixed solvent, appears to be the most significant factor that governs the selectivity of the resin in mixed solvent systems.
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Das, Bijan. « Physico - chemical investigations on the ion-solvent interactions of some Tetraalkylammonium and common ions in non-aqueous and mixed binary aqueous solvent systems ». Thesis, University of North Bengal, 1992. http://hdl.handle.net/123456789/719.
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Östlund, Erik. « Impact of Water on Recycling Lithium Ion Battery Cathode Material in a Deep Eutectic Solvent ». Thesis, Uppsala universitet, Strukturkemi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-417814.
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Modekrutti, Subrahmanyam. « UNHINDERED TRIANGULENE SALT PAIRS : SUBSTITUTION-DEPENDENT CONTACT ION PAIRING AND COMPLEX SOLVENT-SEPARATED DISCOTIC IONS IN SOLUTION ». UKnowledge, 2015. http://uknowledge.uky.edu/chemistry_etds/50.
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This work sought to enforce aromatic interactions between compatible π-molecular orbital systems with ionic bonding. In this case the interacting partners are oppositely charged discotic triangulene derivatives. The observed properties of the heterodimeric ion-pairs likely arise due to a hypothetical synergy between electrostatics and π-interactions. The work presented here describes investigation of putative covalency arising from this hypothetical synergy in the electrostatics driven π-stacking. In order to probe this, various hypotheses were made and experiments were designed to test their validity. The results from the experiments show existence of contact ion-pairs and complex solvent-separated discotic ions in solution. The formation of complex ion-pairs arise due to the fact that the electrostatic interaction that brings the discotic ions together is strong, but does not neutralize when the contact is made. So, the dipole created by the monopoles in a dimeric contact ion-pair can attract ions at both termini forming oligomers. This process apparently continues towards highly aggregated states and then to nanometric species and at some point the material precipitates. The propensity to aggregate and form complex-ions limited our approach to the measurement of the energetics of the ion-pairing for two reasons: (1) the observables had a complex dependence on temperature, solvent, concentration and ionic strength; and (2) the mass in solution was undergoing kinetic evolution towards solid states. The turbidimetric effects arising due to aggregate formation further complicated the extraction of weak interactions between the ions and hence effects determination of ion-pairing constants.
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Dey, Rabindra. « Studies on the ion-solvent interactions of tetraalkylammonium and common ions in tetrahydrofuran and its binary mixtures ». Thesis, University of North Bengal, 2005. http://hdl.handle.net/123456789/773.
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Ma, Minhui. « Solvent microextraction with simultaneous back extraction and the effect of tetra-n-butylammonium ion on ODS bonded phase ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34805.pdf.
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AL-Shroofy, Mohanad N. « UNDERSTANDING AND IMPROVING MANUFACTURING PROCESSES FOR MAKING LITHIUM-ION BATTERY ELECTRODES ». UKnowledge, 2017. http://uknowledge.uky.edu/cme_etds/76.
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Lithium-ion batteries (LIBs) have been widely used as the most popular rechargeable energy storage and power sources in today’s portable electronics, electric vehicles, and plug-in hybrid electric vehicles. LIBs have gained much interest worldwide in the last three decades because of their high energy density, voltage, rate of charge and discharge, reliability, and design flexibility. I am exploring the possibility of developing battery manufacturing technologies that would lower the cost, reduce the environmental impact, and increase cell performance and durability.
This dissertation is focused firstly on understanding the effect of mixing sequence (the order of introducing materials) and optimizing the electrode fabrication for the best electrochemical performance, durability, lower cost, and improve the existing manufacturing processes. The electrode system consists of active material, polymer binder, conductive agent, and solvent. I have investigated four different mixing sequences to prepare the slurries for making the positive electrode. The key sequence-related factor appears to be whether the active material and conductive agent are mixed in the presence of or prior to the introduction of the binder solution. The mixing sequences 1, 2, 3, and 4 were optimized, and the rheological behavior of the slurries, morphology, conductivity, and mechanical and electrochemical properties of electrodes were investigated. Slurries from sequences 1 and 4 show different rheological properties from 2 and 3. The amount of NMP required to achieve a comparable final slurry viscosity differed significantly for the sequences under study. The sequence 1 shows better long-term cycling behavior than sequences 2, 3 and 4. This study quantifies the link between electrode slurry mix parameters and electrode quality.
Secondly, a new method of making lithium-ion battery electrodes by adapting an immersion precipitation (IP) technology commonly used in membrane manufacturing was developed and demonstrated. The composition, structure, and electrochemical performance of the electrode made by the IP method were compared favorably with that made by the conventional method. The toxic and expensive organic solvent (NMP) was captured in coagulation bath instead of being released to the atmosphere. The IP electrodes show an excellent performance and durability at potentially lower cost and less environmental impact.
Thirdly, I have developed and demonstrated a solvent-free dry-powder coating process for making LiNi1/3Mn1/3Co1/3O2 (NMC) positive electrodes in lithium-ion batteries, and compared the performance and durability of electrodes made by the dry-powder coating processes with that by wet-slurry coating processes. The technology that has been used is the electrostatic spray deposition (ESD) process. This process eliminates volatile organic compound emission, reduces thermal curing time from hours to minutes, and offers high deposition rates onto large surfaces. The long-term cycling shows that the dry-powder coated electrodes have similar performance and durability as the conventional wet-slurry made electrodes.
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Dougassa, Yvon. « Propriétés de transport et solubilité des gaz dans les électrolytes pour les batteries lithium-ion ». Thesis, Tours, 2014. http://www.theses.fr/2014TOUR4035/document.
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Lors du fonctionnement des batteries Li-ion, la dégradation progressive de l’électrolyte engendre la génération des gaz qui sont à l’origine du phénomène des surpressions dans ces dispositifs, et a pour conséquence des problèmes de sécurité. Cette thèse aborde l’étude de la solubilité des gaz issus des réactions de dégradation des électrolytes tels que le CO2, CH4, ou encore C2H4 dans plusieurs systèmes simples (solvants purs) ou complexes (mélanges binaires, ternaires et quaternaires avec sel de lithium), en fonction de la température, de la structure des solvants et des sels, ainsi que de leurs concentrations en solution. A cet effet, nous avons mesuré préalablement les propriétés volumétriques, de transport, ainsi que les pressions de vapeur des électrolytes formulés en fonction de la composition et de la températureThe performance and the safety of a lithium-ion battery depend to a great extent on the stability of the electrolyte solution, because the high voltage of the battery may cause the decomposition of lithium salt or organic solvents, which limits then the battery lifetime. During these degradations, several gases are, generally, generated like the CO2, CO, CH4 and C2H4, which induce in fact several problems related to the pressure increase inside the sealed cell. The main objective of this PhD thesis is to understand the key thermodynamic parameters which drive the gas dissolution in classical solvents and electrolytes. For that, several pure solvents and electrolytes have been firstly investigated to determine their volumetric and transport properties, as well as, their vapour pressure as the function of temperature and composition
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Nandi, Debasis. « Physico - chemical investigations on the ion-solvent interactions of Tetraalkylammonium and alkali metal halides in non-aqueous solvents and their aqueous binary mixtures ». Thesis, University of North Bengal, 1989. http://hdl.handle.net/123456789/718.
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Camilo, Nilton Soares. « Reação de 'alfa'-amidoalquilação de ions N-aciliminio com nucleofilos de carbono em sistema micelar SDS/agua, na ausencia de solvente e em liquido ionico : aplicação na sintese de um analogo da febrifugina ». [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249286.
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Orientador: Ronaldo Aloise PilliTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-07T21:45:34Z (GMT). No. of bitstreams: 1 Camilo_NiltonSoares_D.pdf: 3180029 bytes, checksum: 2847c04256e604434393243a35c4298a (MD5) Previous issue date: 2006
Doutorado
Quimica Organica
Doutor em Ciências
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Patwardhan, Neeraj Narendra. « Study of Synthesis, Reactions and Enantiomerization of Cα-Chiral Grignard Reagents ». Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/37814.
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The development of chiral organometallics for asymmetric synthesis is a topic of significant research in the recent past. The most studied in this class are the chiral organolithium reagents with many reported examples. The primary focus of our research is the development of Cα-chiral Grignard reagents, where the metal bearing α-carbon is the sole source of chirality. Examples of such Grignard reagents are rare owing to the problems associated with their synthesis, and their low configurational stability. We have studied these problems in three different modules of this project.
Reactions of 1-magnesio-2,2-diphenyl-cyclopropylcarbonitrile with carbon electrophiles are first attempted in order to expand the utility of this configurationally stable Cα-chiral Grignard reagent in asymmetric synthesis. This reagent has been shown to be non-reactive towards carbon electrophiles at low temperatures. Consequently, we attempt to enhance the reactivity of this compound through two different approaches, Lewis-base activation and the "ate-complex" generation. The Magnesium/Halogen (Mg/X) exchange reactions have been shown to be extremely useful in the synthesis of complex Aryl, alkenyl (sp²) and alkynyl (sp) Grignard reagents. Examples of Mg/X exchange reactions of Alkyl (sp³) halides are, however, rare. Even more rare are such examples with secondary and tertiary alkyl halides, justifying the relative paucity of chiral Grignard reagents. In this module of our project, we study the Mg/X exchange reactions on secondary alkyl halides possessing a γ-hydroxyl group, as an internal activator for such Mg/X exchange reactions.
Enantiomerization pathways of chiral organolithium compounds have been widely studied. However, few such studies have been performed on chiral Grignard reagents. In this module of the project, we studied the solvent assisted enantiomerization mechanism of the Cα-chiral 1-magnesio-2,2-diphenyl-cyclopropylcarbonitrile. Rate constant for the enantiomerization of this compound was measured in three different ethereal solvents to study the effect of solvent on the configurational stability. Finally, the order of the enantiomerization process with respect to [Et₂O] was studied in order to predict the mechanism of this process in Et₂O solvent.
Our kinetic studies on the enantiomerization process provided us with a definitive picture for the enantiomerization of the Cα-chiral 1-magnesio-2,2-diphenyl-cyclopropylcarbonitrile, where solvation of the Grignard reagent preceded an ion-pair separation step which eventually lead to enantiomerization of the Grignard species. However, the precise structure of all the involved solvated intermediates could not be determined as kinetics was not able to distinguish between these intermediates. We next performed computational calculations to study the effect of solvation on the analogous 1-magnesio-cyclopropylcarbonitrile in order to address the unanswered questions from our kinetic studies.Ph. D.
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Štulák, Stanislav. « Stanovení bodu tuhnutí elektrolytů s retardérem hoření kryoskopickou metodou ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-221001.
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The thesis is devoted to the field of properties investigation of new types of electrolytes, and assess the appropriateness of electrolytes studied in this paper for use in Li -ion batteries. It focuses specifically on electrolytes based on aprotic solvents and their mixtures with the flame retardants. The goal of the thesis is to investigate the effects of FRAs on electrolyte mixtures via changes in specific conductivity and freezing point. These objectives were fulfilled by using electrochemical impedance spectroscopy in combination with a cryoscopic measurement method. There were overall 16 samples examined. The samples were prepared as a combination of chemicals, specifically Ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), dimethyl sulfone (DMSO2), triethyl phosphate (TEP) Dimethyl methylphosphonate (DMMP), triphenyl phosphate (TPP). Based on the results of the experiments, the mixtures were sorted according to the observed properties in the tables listed in the last part of this paper. These values can be further used to supplement the continuing research of electrolytes and also as assistance in searching for the new electrolyte mixtures.
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Barucha-Kraszewska, Justyna. « Experimental and stimulation analyses of fluorescent solvent relaxation process in biomembranes : Inflence of ions and molecular interpretation of the dye dynamics ». Thesis, Besançon, 2012. http://www.theses.fr/2012BESA3010/document.
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De nombreux processus biologiques liés aux membranes cellulaires lipidiques sont encore très mal connus. La présence d'eau et d'ions à l'interface influence les propriétés structurelles et dynamiques de la bicouche lipidique. Les techniques de fluorescence sont très utiles pour étudier les membranes en raison de la grande sensibilité des sondes à leur environnement. Nous avons utilisé la technique de relaxation de solvant (SR) pour explorer l'hydratation et la mobilité de l'eau. Nous avons également réalisé des calculs quantiques (QM) et des dynamiques moléculaires (DM) pour étayer nos expériences. Les résultats SR montrent qu'un petit cation (Na+) est très attiré par la membrane et augmente sa rigidité à l'opposé des cations (NH4+, Cs+) plus gros. Les anions (CI04-, SCN-) s'adsorbent à l'interface plus facilement que Cl-. Ces anions changent la mobilité et l'hydratation des têtes polaires des lipides de la bicouche. Les études SR de la zone hydrophobe de la membrane montrent que les processus de relaxation sont ici très complexes. lis reflètent des processus rapides intramoléculaire (relaxation de torsion, transferts de charge) et des processus intermoléculaires lents. Les calculs QM ont permis de créer les champs de force de trois sondes fluorescentes (Prodan, Laurdan et C-laurdan). Les simulations DM ont permis de déterminer les positions des sondes dans une membrane DOPC. La modélisation reproduit correctement les résultats SR, en particulier les temps de relaxation : de l'ordre de la ps en solvant aqueux et de la ns dans la membrane. Les simulations MD sont complémentaires des méthodes SR et permettent de surveiller le comportement de molécules uniquesMany biologically important processes and phcnomena in lipid membranes are still not fully understood. The presence of ions and water molœules has a significant influence on the structural and dynamical properties of lipid bilayers. Fluorescent techniques are versatile tools for studying the lipid membranes, because the fluorescence emission is strongly sensitive to dye environment. We have conducted fluorescent solvent relaxation (SR) experiments to explore the hydration and mobility properties in lipid membranes in the presence of different chaotropic ions. We have also carried out Quantum Mechanical (QM) calculations and Molecular Dynamics (MD) simulations for supporting the SR experiments. SR experiments show that small cation (Na+) is attracted to the membrane and increases rigidity ofbilayer, while larger cations (NH/, Cs+) should not. Large anions (CI04·, SCN') adsorl, at the membrane interface more easily than smaller ones (Cl') and significantly change tl!e mobility and hydration of the headgroup region oflipid bilayer. SR study ofhydrophobic part of the membrane show that SR processes are complex there and reflect botl!: faster, intramolecular (torsional relaxation or fonnation of charge transfer state) and slower, intermolecular (SR) relaxation processes. QM calculatiom were used to create force-field for three fluorescent dyes (Prodan, Laurdan and C-laurdan). MD simulations allow detennining position of the dye in the lipid membrane in the ground state and after excitation and reproduce correctly SR timescale- ps in water and ns in the membrane. MD simulations extend the capabilities of SR method and allow observing the behaviour of individual molecules
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Rudolph, Wolfram W., Dieter Fischer et Gert Irmer. « jz Vibrational spectroscopic studies and DFT calculations on NaCH₃CO₂(aq) and CH₃COOH(aq) ». Royal Society of Chemistry, 2014. https://tud.qucosa.de/id/qucosa%3A36074.
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Aqueous solutions of sodium acetate, NaCH₃CO₂, and acetic acid, CH₃COOH, were studied using Raman and infrared spectroscopy. The spectra were recorded over a large concentration range, in the terahertz region and up to 4000 cmˉ¹. In the isotropic Raman spectrum in R-format, a polarized band at 189 cmˉ¹ was assigned to the υ₁Na–O stretch of the hydrated Na⁺-ion and a shoulder at 245 cmˉ¹ to the restricted translation band, υsO–H⋯O* of the hydrated acetate ion, CH₃CO₂ˉ(aq). The CH₃CO₂ˉ(aq) and the hydrated acetic acid, CH₃COOH(aq), possess pseudo Cs symmetry. Geometrical parameters for the species in the gas phase and for CH₃CO₂ˉ(aq) and CH₃COOH(aq) are reported. Characteristic bands for CH₃CO2ˉ(aq) and CH₃COOH(aq) were assigned under the guidance of the DFT vibrational frequency calculations and discussed in detail. In aqueous NaCH₃CO₂ solutions, at high concentrations, no contact ion pairs could be detected, but instead solvent separated ion pairs were found. In LiCH₃CO₂(aq), however, contact ion pairs are formed which is indicated by the appearance of a shoulder at 939 cmˉ¹ and the shift of the symmetric stretching mode of the –CO₂ˉ group to higher wavenumbers.
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McGillivary, Angela. « Reactive solvent extraction of #beta#-lactam antibiotics and other anions ». Thesis, London South Bank University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326763.
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SENEDA, JOSE A. « Separação e recuperação de chumbo-208 dos resíduos de tório terras raras gerados na unidade piloto de purificação de nitrato de tório ». reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11424.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Faux-Mallet, Marie-Sabine. « Extraction du gallium(iii) en milieu acide : comparaison des methodes d'extraction liquide-liquide et d'echange d'ions sur resines ». Paris 6, 1988. http://www.theses.fr/1988PA066234.
Texte intégralRésumé :
Comparaison des avantages et des inconvenients de l'extraction a l'aide de resines et de l'extraction liquide-liquide en vue de preciser leur domaine respectif d'utilisation en hydrometallurgie. Etude de la separation du gallium contenu dans les solutions d'attaque des minerais de zinc. Utilisation de la resine duolite es467 et pour l'extraction liquide-liquide de l'hydroxy-8 quinoleine et d'une alpha-hydroxy-oxime
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Barakat, Salem Ahmad Salem. « Spectroscopic and flow-injection studies of some novel ion-pair reactions ». Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317545.
Texte intégral
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Harper, Heather. « Solvent Dependent Molecular Mechanics : A Case Study Using Type I Collagen ». Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5035.
Texte intégralRésumé :
Being the most abundant protein in the body, by mass, type I collagen provides the building blocks for tissues such as bone, extra-cellular matrix, tendons, cornea, etc[1-3]. The ability of a single protein to create structures with such various mechanical properties is not fully understood. Before one can engineer and assemble a complex tissue, such as cornea, the mechanisms underlying the formation and assembly, mechanical properties, and structure must be investigated and quantified. The work presented herein contains an extensive study of Type I collagen from the molecular to the tissue level.
The engineering of collagenous tissues that mimic the mechanical and optical properties of native human cornea have been performed by a number of groups[4-7]. In all of these studies, the corneal-mimicking tissues have been created using a number of methods including repeated flow casting. To date, the ability to create self-assembled corneal tissue has not been achieved. Understanding the mechanisms of formation of native cornea will not only bring us closer to achieving self-assembled transplantable corneal tissue but will also aid in the engineering of all collagenous tissues and other structures comprised of filamentous units.
Recently, the study of type I collagen has primarily focused on the tissue, fiber, and fibril scale[2, 8-21]. Grant, et al.[20] measured the elastic modulus of collagen fibrils in various solutions and found that by increasing ion concentration, in the solution around the fibril, the elastic modulus increased. The solution dependent behavior of the elastic modulus of collagen fibrils was measured but the cause of the dependence was unknown. Grant et al. state that due to the complex nature of the interactions between collagen fibrils and aqueous solutions, the exact cause of this effect is difficult to determine. Through work presented herein, not only do we show that this behavior is seen at the molecular level but also quantify the relationship between ionic concentration and molecular stiffness for a variety of ionic species.
Studies of collagen mechanics, on the molecular level, are brief[22-26]. The most prominent of these studies in recent years was performed by Sun, et al.[27] wherein a persistence length of 14.5nm, for human type I procollagen, was measured. The persistence length of the molecule, which is a measure of flexibility, is a highly debated topic with quoted values of 14.5nm[27], 57nm[28], 130nm[29], 175nm[30], 308nm[31], and 544nm[32]. The broad range of values indicates that the flexibility of the collagen molecule is a complex question.
It became apparent that the disagreement of the persistence length of molecular collagen in the literature may be due to the use of different ionic solutions. To address this, an initial atomic force microscope, AFM, study of the persistence length of molecular collagen diluted in DI water and two ionic solutions was conducted. This study showed that there is a strong solution dependence to the flexibility of the molecule. The ionic solutions presented molecules with a large persistence length, a straightened configuration, while the DI water dilution resulted in a persistence length that was a factor of 10 smaller.
Because two different complex ionic solutions in the initial study showed different persistence lengths, an evaluation of the effect of each individual salt was performed. To elucidate the effects of individual ionic species on the conformations and persistence length of Type I collagen varying concentration of monovalent and divalent salts with different cations and anions were tested. It was found that increasing ionic concentration for all species types resulted in a higher persistence length but the rate of change in persistence length as a function of concentration is unique to each species.
In 2002 Leikina, et at.[33] suggested that Type I molecular collagen is unstable at body temperature using differential scanning calorimetry. To examine these results, an AFM study was performed that imaged the collagen molecules after being held at body temperature for varying times. The density of molecules deposited onto mica, above a 200nm length cutoff, was calculated and it shows that the number of molecules above 200nm in length decreases with increasing incubation time.
These environmental studies were performed with an aim to understanding the role of environment in creating a corneal mimicking tissue. Currently, the most promising method of collagen membrane fabrication for corneal replacement was developed by Tanaka, et al.[4]. This unique repeated flow casting method allows for the manufacturing of transparent collagen membranes with controllable thickness and fibrillar alignment. Using the repeated flow casting technique, orthogonally oriented collagen membranes were created and their optical properties were measured using the Generalized High Accuracy Universal Polarimeter, G-HAUP. When engineering a tissue for the eye, the optical properties of the tissue are of the utmost importance. Appropriately for corneal tissues, the measurements for linear birefringence and linear dichroism were negligible.
It was clear, from the literature, that a fundamental understanding of molecular type I collagen was not available. In this work, the mechanical properties and environmentally sensitive behavior of bovine dermal type I molecular collagen is studied. The exploration into the unique behavior of these systems begins with documenting the rich ionic species and concentration dependent flexibility of molecular type I collagen and the temperature dependence on the stability of the molecule is tested. The study concludes with the construction of corneal mimicking tissues using the repeated flow casting method and measuring the complex optical properties of these tissues.
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Spadina, Mario. « Solvation and Ion Specificity in Complex Media ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS020/document.
Texte intégralRésumé :
Le but de cette thèse était de créer des modèles pour deux applications qui apparaissent couramment en chimie séparative, à savoir la séparation solide-liquide et la séparation liquide-liquide. L'avantage de la modélisation est manifeste dans les deux cas. L'étude fondamentale des propriétés des ions et de leur solvatation dans les milieux complexes, en tenant compte de façon simplifié des différents effets mis en jeu, nous a permis de construire un cadre qui utile aussi bien aux chimistes en laboratoire qu’aux ingénieurs lors de la conception des procédés. Nous avons adapté cette stratégie sur deux systèmes différents, qui peuvent tous deux être considérés comme complexes. Le premier système modèle pour étudier la séparation solide-liquide était des nanotubes de TiO2 dispersés dans une solution aqueuse. Ce système a été étudié au moyen de la Théorie de la Fonctionnelle de la Densité Classique couplée à une méthode de régulation de charge, au sein de l'ensemble Grand-Canonique. La méthode s'est avérée efficace pour établir la description complète des propriétés de charge des nanotubes de TiO2. Dans ce cas, nous nous sommes intéressés à obtenir la description de l'ion à l'intérieur des nanotubes chargés sous l'influence du champ électrique (créé par les nanotubes). Les calculs ont prédit des effets tels que la différence de charge de surface entre la surface externe et la surface interne, ou la violation de l'électroneutralité à l'intérieur des nanotubes. Il a été démontré que le modèle était en accord avec les données expérimentales. De plus, la méthode peut être utilisée directement pour prédire diverses techniques de titrage. Une simple généralisation de l'approche proposée permettra d'étudier l'efficacité d'adsorption réelle du procédé de séparation solide-liquide. Le second système modèle concerne l'étude du procédé d'extraction liquide-liquide et il comprend trois parties distinctes. Les trois parties ont été consacrées aux cas des extractants non ioniques, puis acides (échangeurs d'ions), et enfin aux mélanges synergiques d'extractants. Un modèle simple de thermodynamique statistique, dans lequel nous avons incorporé certains des concepts bien établis en chimie colloïdale, a fourni une approche de type matière molle pour calculer le processus à l'échelle de l'ingénieur. Nous avons développé une approche classique d'équilibres simples pour une compréhension plus large et plus intuitive de la formation des agrégats polydisperses dans l'extraction liquide-liquide. La principale conclusion présentée est que l’on doit proposer un nouveau paradigme pour la chimie : à l'équilibre, de nombreux agrégats de composition très différente mais similaires en énergie libre, coexistent. Avec la polydispersité obtenue, nous avons ainsi proposé un outil pour étudier un comportement plus "global" de l'extraction liquide-liquide. Cela nous a poussés à passer des considérations classiques d'isothermes d'extraction à celles plus précises des " cartes " d’extraction. Un grand soin a été apporté à l'étude de la synergie puisqu'il s'agit d'une important question depuis 60 ans dans la communauté scientifique et industrielle de la séparation. A notre connaissance, la première rationalisation quantitative de la synergie d’extraction a été proposée dans le cadre de cette thèse. Les effets sous-jacents des contrôles enthalpique et entropique sur la structuration des phases organiques ont été découplés et étudiés en détail. Nous espérons que cette thèse a démontré l'importance de la modélisation mésoscopique sur des exemples pratiques utilisés à la fois par les chimistes et les ingénieursThe object of this thesis was to create models for two applications which readily appear in separation chemistry, namely the solid-liquid and the liquid-liquid extractions. The benefit of modelling in both cases is twofold. Studying the fundamental properties of ions and their solvation properties in the complex media, and simplifying the expression for important effects, enables us to construct the framework which can be used by both chemists in the laboratory, as well as the chemical engineers in the process design. For two applications we adapted two different systems, both of which can be considered as complex. The model system to study the solid-liquid separation were TiO$_{mathrm{2}}$ nanotubes dispersed in the aqueous solution. This system was studied by the means of Classical Density Functional Theory coupled with the charge regulation method, within the Grand-canonical ensemble. Indeed, the method proved to be successful in establishing the full description of the charge properties of TiO$_{mathrm{2}}$ nanotubes. In this case, we were interested in obtaining the description of ion inside the charged nanotubes under influence by the electric field (exhibited by nanotubes). Calculations predicted effects such as the difference in surface charge between the outer and the inner surface, or the violation of electroneutrality inside the nanotubes. It was demonstrated that the model was in the agreement with the experimental data. Moreover, the method can be directly used to predict titration for various techniques. A simple generalization of the proposed approach can be used to study the actual adsorption efficiency of the solid-liquid separation process. The model system to study the liquid-liquid extraction process included three distinct parts. The three parts were devoted to the cases on non-ionic, acidic ion exchangers, and finally the synergistic mixtures of extractants. Simple bulk statistical thermodynamics model, in which we incorporated some of the well-established concepts in colloidal chemistry provided a soft-matter approach for the calculation of actual engineering-scale processes. Were have expanded a classical simple equilibria approach to broader, more intuitive polydisperse aggregates formation that underlines the liquid-liquid extraction. The key finding can be presented as a current opinion or newly-proposed paradigm: at equilibrium, many aggregates completely different in composition but similar in free energy coexist. With obtained polydispersity, we were equipped with a tool to study a more 'global' behavior of liquid-liquid extraction. This urged us to pass our considerations of historical extraction isotherms to extraction 'maps'. Great care was devoted to the study of synergy since it is a 60-year old ongoing question in the separation industrial and science community. To our best knowledge, the first quantitative rationalization total synergistic extraction was proposed within this thesis. Underlying effects of enthalpy and entropy control on the organic phase structuring were decoupled and studied in detail. Hopefully, this thesis demonstrated the importance of mesoscopic modelling to assist both chemists and chemical engineers in practical examples
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Pelikán, Ondřej. « Elektrolyty s obsahem retardéru hoření na bázi fosforu ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377067.
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The diploma thesis is focused on the theoretical knowledge of lithium accumulators. More attention is given to electrolytes and especially to flame retardants, where the types and individual examples of flame retardants are described more detailed. The practical part is focused on the individual laboratory measurement of selected samples of electrolytes with different flame retardants. The measurement results are analyzed in other parts.
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QUEIROZ, CARLOS A. da S. « Terras raras : fracionamento, purificação e controle analítico ». reponame:Repositório Institucional do IPEN, 1988. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11634.
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Dissertacao (Mestrado)
IEA/D
Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
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Loret, Jean-François. « Extraction de metaux precieux par des gels organiques ». Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13068.
Texte intégralRésumé :
Preparation de gels qui sont des polymeres reticules qui gonflent lorsqu'ils sont plonges dans des solvants adequats. Le gel pvc-tbp est utilise pour extraire l'or en milieu hcl : les ions m(cn)::(2)**(-) (m=ag,au) en milieu koh sont extraits par le gel dcy-18c6-chcl::(3)-br (br = polylentadiene)
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Lakay, Eugene Marlin. « Novel ion-exchange materials derived from poly(styrene-co-maleimide) and a study of the extraction and recovery of gold (III) chloride from acidic solutions ». Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80148.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: In this study an economical, environmentally friendly, selective and efficient process for the extraction and recovery of [AuCl4]- from aqueous acidic chloride-rich solutions, particularly those aqueous solutions having low concentrations of the precious metal complexes has been investigated. Functionalized poly(styrene-co-maleimide) (PSMI) nanoparticles were synthesized by thermal imidization of the poly(styrene-co-maleic anhydride) (PSMA) copolymer with 3-N,N-dimethylaminopropylamine. Stable water-based dispersions were obtained containing spherical, monodisperse PSMI nanoparticles with a narrow size-distribution and average diameters of 50 ± 5 nm. The specific surface area of the bulk PSMI nanoparticles is 88.1 ± 2.2 m2/g with an average pore diameter of 82.3 Å. 13C NMR, FTIR and elemental analyses confirmed the successful and complete conversion of PSMA into the PSMI derivative. The functionalized PSMI nanoparticles synthesized were investigated as a novel anion-exchange material for the extraction of [AuCl4]- ions from aqueous acidic solutions. Batch sorption studies were carried out as a function of various parameters, such as initial gold concentration, PSMI mass, contact time and agitation rate. The [AuCl4]- extraction occurred with extremely fast sorption kinetics and is dependent on the rate of agitation during the batch sorption process. The functionalized PSMI nanoparticles show a maximum gold loading capacity of 1.76 mmol/g (347.7 mg/g). Langmuir and Freundlich isotherm models were applied to analyze the experimental sorption data. The best model describing the sorption process is given by the Langmuir model. Desorption efficiencies of about 80 % and 93 % were obtained using acidified thiourea (0.25 M thiourea/2 M HCl) and a mixture of 10 M HNO3/0.5 HCl as elutant solutions, respectively. X-ray photoelectron spectroscopy (XPS) analysis unambiguously confirms that the immobilized gold species exists in several oxidation states of 0, +I and +III on the PSMI nanoparticles. This proves that the [AuCl4]- ions initially present in the gold feed solutions unfortunately are subject to a reduction phenomenon on the surface of the functionalized PSMI nanoparticles. The existence of the various gold species contributed significantly to poor desorption efficiencies. In addition to PSMI nanoparticles, micro- to millimeter size PSMI resin beads was prepared by an electrospray methodology. This allows for a wide range of PSMI spherical and quasi-spherical bead diameters of shape to be prepared by manipulation of the experimental conditions employed during the electrospray process, such as the concentration of the PSMI in solution, the capillary tip-to-collector distance, flow rate and the applied voltage. 13C NMR and FTIR spectroscopy analyses show that the electrospray methodology allows PSMI resin beads preparation without any change in chemical composition of the PSMI material. Surface area and porosity analysis shows that 450 μm and 1620 μm PSMI beads selected for use in the gold extraction experiments are microporous and have BET specific surface areas of 2.8 ± 0.4 m2/g and 2.0 ± 0.1 m2/g, respectively. Micro- to millimeter size PSMI resin beads of 450 μm and 1620 μm diameter were tested as potential anion-exchange resins for the extraction of [AuCl4]- from aqueous acidic solutions. The time-dependent studies reveal that the extent of gold uptake increases with an increase in contact time and is dependent on the gold concentration in the [AuCl4]- feed solutions. A maximum loading capacity of 120.7 mg/g and 98.16 mg/g was attained for the 450 μm and 1620 μm resin beads, respectively. The experimental sorption data followed a linear trend consistent with a Freundlich sorption model. This sorption trend for [AuCl4]- suggests that a multi-layer sorption process predominates. Desorption of immobilized gold species from the loaded PSMI resin beads was investigated using various elutants such as HCl, HNO3, thiourea, NaCN and NaOH solutions. The best results were obtained using a mixture of 10 M HNO3/0.5 M HCl as elutant with a desorption efficiency of about 97%. Finally, superparamagnetic magnetite (Fe3O4) nanoparticles with a high degree of crystallinity and phase purity were synthesized by a chemical co-precipitation of Fe2+ and Fe3+ salts. The average diameters of the obtained Fe3O4 nanoparticles were about 7 – 8 nm. The Fe3O4 nanoparticles were coated with oleic acid surfactant molecules and used as seed particles for the preparation of 50 nm diameter magnetic PSMI nanoparticles via an in situ imidization reaction. TEM analysis confirmed that the magnetically responsive PSMI nanoparticles consist of magnetite core-polymer shell structure, although more work is required to perfect such materials.
AFRIKAANSE OPSOMMING: In hierdie studie is ‘n ekonomiese, omgewings vriendelike, seleketiewe en effektiewe proses vir die ekstraksie en herwinning van [AuCl4]- uit suur chloried-ryke oplossings, spesifiek oplossings van lae konsentrasies van edel metal komplekse was bestudeer. Gefunksionaliseerde poli(stireen-ko-maleïmied) (PSMI) nanopartikels was gesintetiseer deur middel van termiese imidisasie van die poli(stireen-ko-maleïk anhidried) kopolimeer met 3-N,N-dimetielaminopropielamien. Stabiele dispersies in water was gevind wat soos sweriese mono-disperse PSMI nanopartikels met ‘n noue partikel-grootte verspreiding met ‘n gemiddelde deursnee van 50 ± 5 nm. Die spesifieke oppervlak area van die massa PSMI nanopartikels is 88.1 ± 2.2 m2/g met ‘n gemiddelde porie-grootte van 82.3 Å. 13C NMR, FTIR en elementêre analiese bevestig die suksesvolle en volledige omskakeling van PSMA na PSMI. Die gefunksionaliseerde PSMI nanopartikels was bestudeer as ‘n nuwe anion-uitruil material vir die ekstraksie van [AuCl4]- ione uit suur oplossings. Stel sorpsie studies was uitgevoer as ‘n funksie van verskeie parameters soos onder andere die goud konentrasie in oplossing, PSMI massa, kontak tyd en ‘n mengings tempo. Die [AuCl4]- ekstraksie gebeur met ‘n geweldige sorpsie kinetika en is afhanklik van die mengings tempo gedurende die stel sorpsie proses. Die gefunksionaliseerde PSMI nanopartikels het ‘n maksimum goud sorpsie kapsiteit van 1.76 mmol/g (347.7 mg/g). Langmuir en Freundlich isoterm modelle was gepas en geanaliseer op die experimentele sorpsie data waarvan die Langmuir isoterm model die data die beste gepas het. De-sorpsie effektiwiteit van ongeveer 80 % en 93% was vekry vir die aangesuurde thiourea (0.25 M thiourea/2 M HCl) en ‘n mengsel van 10 M HNO3/0.5 M HCl as elueer oplossings, onderskeidelik. X-straal foto-elektron spektroskopie (XPS) analiese bevestig ongetwydeld die geimmobileerde goud spesies in oksidasietoestande van 0, +I, en +III op die PSMI nanopartikels. Hierdie is bewyse dat die [AuCl4]- oorspronklik teenwoordig in die goud oplossings is onderhewe auto-reduksie fenomeen op die oppervlak van die gefunksionalieerde PSMI nanopartikels. Die bestaan van verskeie goud spesies dra by tot die power de-sorpsie effektiwiteit van ge-immobiliseerde goud. Bykomend tot die nanopartikels is mikro- tot millimeter grootte PSMI partikels voorberei met ‘n elektro-sproei proses. Hierdie metode stel ons instaat om ‘n wye reeks sferiese en quasi-sferiese PSMI partikel se deersnee voorteberei. Deur die manupulasie van die eksperimentele kondisies gedurende die elektro-sproei proses, soos die konsentrasie van die PSMI in oplossing, die kapilêre punt-tot-ontvanger afstant, vloeispoed en die toegepasde potensiaal. 13C KMR en FTIR spectroskopiese analiese wys dat die elektro-sproei proses die PSMI partikel bereiding toelaat sonder enige veranderinge in die chemiese samestelling van die PSMI materiaal. Oppervlak area en porie-grootte analise wys dat 450lksdfhld en dskl jmm partikels gebruik in die goud ekstraksie eksperimente is mikro-porieës en het spesifieke oppervlak-areas van 2.8 ± 0.4 m2/g en 2.0 ± 0.1 m2/g onderskeidelik. Mikro- tot millimeter grootte poli(stireen-ko-maleimied) (PSMI) partikels van 450 μm en 1620 μm deursnee was getoets as potensieele anion-uitruilings-hars vir die ekstraksie van [AuCl4]- vanuit suur oplossings. Die tyd afhanklike studies gee aanduiding dat die mate van goud opname toeneem met ‘n toename in kontak-tyd en is afhanklik van die goud konsentrasie in die [AuCl4]- oplossings. ‘n Maksimum opname-kapasiteit van 120.7 mg/g en 98.2 mg/g was verkry vir die 450 μm en 1620 μm hars partikels onderskeidelik. Die eksperimentele sorpsie-data volg ‘n lineêre neiging in ooreenstemming met die Freundlich model. Die sorpsie neiging van [AuCl4]- dui aan dat ‘n meervuldige laag sorpsie proses domineer. De-sorpsie van die geimobiliseerde goud spesies vanaf die PSMI hars partikels was bestudeer deur gebruik te maak van verskeie elueermiddels soos HCl, HNO3, thiourea, NaCN en NaOH oplossings. Die beste resultate is verkry deur ‘n mengsel te gebruik van 10M HNO3/0.5M HCl as elueermiddel met n de-sorpsie effektiviteit van ongeveer 97%. Superparamagnetiese magnetiet (Fe3O4) nanopartikels met ‘n hoë graad van kristaliniteit en fase-reinheid was voorberei deur ‘n chemiese ko-neerslagvorming van Fe2+ en Fe3+ soute. Die gemiddelde deursnee van die Fe3O4 nanopartikels was ongeveer 7 – 8 nm. Die Fe3O4 nanopartikels was omhul met oleic suur benatter molekules wat gebruik word as saadjies vir voorbereiding van 50 nm deursnee-magnetiese PSMI nanopartikels deur middel van ‘n imidisasie reaksie. TEM analiese bevestig dat die magnetiese PSMI partikels nanopartikels bestaan uit ‘n magnetiet-kern polimeer-skil struktuur.
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Pokapanich, Wandared. « Solvent–Solute Interaction : Studied by Synchrotron Radiation Based Photo and Auger Electron Spectroscopies ». Doctoral thesis, Uppsala universitet, Yt- och gränsskiktsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-138749.
Texte intégralRésumé :
Aqueous solutions were studied using photoelectron and Auger spectroscopy, based on synchrotron radiation and a liquid micro-jet setup. By varying the photon energy in photoelectron spectra, we depth profiled an aqueous tetrabutylammonium iodide (TBAI) solution. Assuming uniform angular emission from the core levels, we found that the TBA+ ions were oriented at the surface with the hydrophobic butyl arms sticking into the liquid. We investigated the association between ions and their neighbors in aqueous solutions by studying the electronic decay after core ionization. The (2p)−1 decay of solvated K+ and Ca2+ ions was studied. The main features in the investigated decay spectra corresponded to two-hole final states localized on the ions. The spectra also showed additional features, related to delocalized two-hole final states with vacancies on a cation and a neighboring water molecule. These two processes compete, and by comparing relative intensities and using the known rate for the localized decay, we determined the time-scale for the delocalized process for the two ions. We compared to delocalized electronic decay processes in Na+, Mg2+, and Al3+, and found that they were slower in K+ and Ca2+, due to different internal decay mechanisms of the ions, as well as external differences in the ion-solute distances and interactions. In the O 1s Auger spectra of aqueous metal halide solutions, we observed features related to delocalized two-hole final states with vacancies on a water molecule and a neighboring solvated anion. The relative intensity of these feature indicated that the strength of the interaction between the halide ions and water correlated with ionic size. The delocalized decay was also used to investigate contact ion pair formation in high concentrated potassium halide solutions, but no concrete evidence of contact ion pairs was observed.Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 726
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Migeon, Valérie. « Application des isotopes du molybdène en traçage des matériaux du cycle nucléaire ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN008/document.
Texte intégralRésumé :
Au cours de ces dernières décennies, des études ont étés menées pour identifier plusieurs traceurs des matériaux du cycle du combustible nucléaire, dans le cadre de la lutte contre la prolifération nucléaire. Ces matériaux sont généralement collectés lors d’inspections dans des installations nucléaires, ou saisis lors de contrôles de trafics illicites. Les informations fournies par ces traceurs sont parcellaires et ne permettent pas de déterminer avec exactitude la provenance et l’historique industriel de ces matériaux.Le but de ce travail de thèse est de démontrer le potentiel de l’utilisation des isotopes du molybdène pour le traçage des matériaux du cycle du combustible nucléaire. Le choix s’est porté sur le molybdène car en raison de la similarité de leurs propriétés chimiques, le molybdène et l’uranium sont étroitement associés dans les minerais d’uranium et tout au long de la chaîne de purification de l’uranium. L’étude s’est focalisée sur une partie de l’amont du cycle du combustible, depuis l’extraction des minerais d’uranium jusqu’à la production des concentrés miniers d’uranium : divers procédés physiques et chimiques sont appliqués, à la fois pour purifier l’uranium et abaisser la concentration en molybdène.Au cours de cette étude, une nouvelle méthode de séparation du molybdène a été développée pour caractériser sa composition isotopique dans des minerais, minéraux et concentrés miniers d’uranium. La variabilité des compositions isotopiques du molybdène dans un gisement d’uranium est principalement due aux mécanismes d’adsorption et/ou de précipitation du molybdène. Les gisements magmatiques et sédimentaires ont des compositions isotopiques différentes, ce qui permet ainsi leurs distinctions. Les concentrés miniers d’uranium produits à partir de ces deux types de gisements ont des compositions isotopiques similaires aux minerais. Ces résultats soulignent ainsi le potentiel des isotopes du molybdène comme traceur des origines des concentrés miniers d’uranium. Cependant, un fractionnement des isotopes du molybdène a été établi lors de la production des concentrés miniers d’uranium pour deux usines au Niger. Les procédés de purification de l’uranium tels que la lixiviation, l’extraction par solvant et la précipitation ont été reproduits en laboratoire sur des échantillons réels pour expliquer le fractionnement isotopique du molybdène lors de la production des concentrés miniers. Au cours de ces procédés, le fractionnement peut être positif (lixiviation), négatif (extraction par solvant, précipitation à l’eau oxygénée) ou nul (précipitation à l’ammoniaque). Dans le cas des échantillons du Niger, la somme de ces procédés est négative, dans le sens des données expérimentales que nous avons obtenues, démontrant ainsi également le potentiel de l’utilisation des isotopes du molybdène comme traceur des procédés de transformations des matériaux du cycle du combustible nucléaireNuclear forensics aims at determining the age, provenance as well as industrial or storage history of uranium ores and uranium ore concentrates that are part of the nuclear fuel cycle. Several potential tracers have already been identified for this purpose. However, these tracers are not providing always unambiguous information. This study is focused on establishing Mo isotopes as a new tracer of uranium ore provenance and of ore processing for its application in nuclear forensics. Molybdenum and uranium share a number of common geochemical properties. In the nuclear fuel cycle, molybdenum is an impurity that is difficult to separate during uranium extraction and purification processes, while its concentration is required to be lower than some specification limits. We focused this study on the first part of the nuclear fuel cycle, from the uranium ores extraction to the production of uranium ore concentrates.We developed an enhanced separation method for Mo from a uranium-rich matrix (uranium ores, uranium minerals, uranium ore concentrates) in order to analyze the mass fractionation induced by processes typical of the nuclear fuel cycle. Molybdenum isotopic compositions in uranium ores depend of adsorption and precipitation processes. The δ98Mo values of sedimentary uranium ores is shifted to negative values relative to magmatic ores. This provides a means of distinguishing these types of uranium ores. Uranium ores concentrates produced from both uranium ore natures (magmatic and sedimentary) have Mo isotope compositions similar to the uranium ores. These results suggest that molybdenum isotopes have a strong potential of as a tracer for identifying the origin of the uranium ore concentrates. However, Mo isotopes fractionations were established during the production of uranium ore concentrates in the both Niger mills. We reproduced in laboratory the lixiviation, solvent extraction and precipitation processes to explain these observations. The Mo isotopes fractionation is positive for the lixiviation process, negative for the solvent extraction and precipitation with hydrogen peroxide, and null for ammonia precipitation. In the case of the Niger samples, the sum of these processes is negative and agrees with our experimental data. Mo isotopes have a strong potential as a tracer for identifying the origin and transformation of uranium in the nuclear fuel cycle, in the framework of nuclear forensics
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Guha, Thakurta Soma. « Anhydrous State Proton and Lithium Ion Conducting Solid Polymer Electrolytes Based on Sulfonated Bisphenol-A-Poly(Arylene Ethers) ». University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1239911460.
Texte intégral
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Jarnagin, Nathan D. « High χ block copolymers for sub 20 nm pitch patterning : synthesis, solvent annealing, directed self assembly, and selective block removal ». Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50287.
Texte intégralRésumé :
Block copolymer (BCP) thin film patterns, generated using directed self-assembly (DSA) of diblock copolymers, have shown excellent promise as templates for semiconductor device manufacturing since they have the potential to produce feature pitches and sizes well below 20 nm and 10 nm, respectively, using current 193 nm optical lithography. The goal of this work is to explore block copolymers with sufficient thermodynamics driving force (as described by the Flory Huggins interaction parameter, χ) for phase separation at these smallest lengths scales. Here, poly(styrene)-b-poly(hydroxystyrene) is investigated since the PHOST domain is known to form extensive hydrogen bond networks resulting in increased χ due to this strong enthalpic interaction.
In this work, nitroxide mediated polymerization (NMP) techniques were utilized to produce PS-b-PHOST diblock copolymers with a range of molecular weights (5000-30000) with low PDI approaching 1.2. The phase separation of low molecular weight PS-b-PHOST on neutral underlayer substrates via solvent annealing provided thin film vertical lamellae with 13 nm pitch. These results illustrate the improved resolution of PS-b-PHOST compared with the current industry standard of PS-b-PMMA (with 20 nm pitch). The directed self assembly of lamellar PS-b-PHOST patterns with 18 nm pitch via graphoepitaxy is demonstrated.
Also, a highly selective atomic layer deposition (ALD) and etch technique was investigated which provided selective block removal of (PS-b-PHOST) block copolymer patterns which initially exhibited no inherent etch contrast. In this process, the PS domain is removed leaving a high fidelity etch relief pattern of the original block copolymer template. Finally, an alternative system is presented, namely Poly(trimethylsilylstyrene)-block-poly(hydroxystyrene) (PTMSS-b-PHOST), which utilizes silicon containing functionality in one of the blocks, providing high etch contrast. PTMSS-b-PHOST patterns were also exposed to oxygen plasma allowing selective block removal of the PS domain without the need for additional ALD processing steps.
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Marouani-Keraghel, Saïda. « Reduction electrochimique de composes d'uranyle en milieu organique ». Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13175.
Texte intégralRésumé :
Etude de la reduction chimique de sels (nitrate et acetate) d'uranyle et des complexes (phenyl-1 methyl-3 acyl-4 pyrazolones-5) et beta-cetophosphonates d'uranyle en milieu organique et en presence de perchlorate d'ammonium sur une electrode de mercure
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Duignan, Timothy Thomas. « Modelling specific ion effects with the continuum solvent ». Phd thesis, 2015. http://hdl.handle.net/1885/13642.
Texte intégralRésumé :
Electrolyte solutions play a central role in many processes from industry to
biology. Understanding and building predictive models of their properties
has therefore been a fundamental goal of physical chemistry from its beginnings.
The challenge remains.
In this thesis I outline a continuum solvent model of univalent monatomic
ions in water. This model calculates the free energy of: 1) a single ion in
bulk, 2) of an ion approaching the air–water interface and 3) of two ions approaching
each other. Its central advancements are to include quantitatively
accurate ionic dispersion interaction energies, missing from classical theories,
including the higher order multipole moment contributions to these
interactions. It also includes the contribution from the cavity formation energy
consistently, including the effect of changes in the cavity’s shape. Lastly,
it uses a quantum mechanical treatment of the ions and provides satisfactory
values for their size parameters. Because one consistent framework is used
with the same assumptions to calculate the free energies in these three different
situations the number of parameters can be minimised and the model
can be properly tested.
These three calculations can be used to reproduce experimental solvation
free energies, solvation entropies, partial molar volumes, surface tensions
and activity/osmotic coefficients of the alkali-halide electrolyte solutions. A
minimum of parameters are used and crucially no salt–specific fitting parameters
are necessary. The model is quantitative and predictive and is therefore
a satisfactory model of electrolyte solutions.
It provides an explanation of several key qualitative puzzles regarding
these properties. Namely that ions of the same size can have different solvation
energies, that large ions can adsorb to the air–water interface and that
ions in solution that have similar solvation energies are more strongly attracted to each other than ions that have dissimilar solvation energies. The
continuum solvent model and separate ab initio calculations show that dispersion
interactions play a key role in controlling these effects. In particular,
dispersion energies explain the attraction of large ions for each other in water
and the difference in solvation energy of ions of the same size. The success
of the model implies that it is possible to understand the key properties of
electrolyte solutions using a continuum solvent model. This is an important
conclusion considering the massive computational demands of explicit solvent
treatments.
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Choi, Jong-Ho. « Infrared spectroscopy of molecular ions and ion-solvent clusters ». Thesis, 1995. https://thesis.library.caltech.edu/3763/1/Choi_jh_1995.pdf.
Texte intégralRésumé :
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
Studies to elucidate details of ion-molecule interactions at the molecular level are of extreme importance for understanding the solvation process and ion-molecule reactions in clusters and in the condensed phase. In the quest of this purpose, infrared predissociation spectroscopy has been applied to three ionic systems.
Infrared spectra of mass-selected clusters NO[superscript +](H2O)n showed that the smaller clusters (n=1-3) were complexes of H2O ligands bound to a nitrosonium ion NO[superscript +] core. In the n = 4 cluster, we found evidence for the onset of an intracluster reaction that formed HONO. From an analysis of the spectrum, we concluded that the n = 5 cluster rearranged to form H3O[superscript +](H2O)3(HONO), i.e., an adduct of the reaction products. This study provides clear evidence for the intracluster rearrangement reaction NO[superscript +](H2O)n[...]H3O[superscript +](H2O)n-2(HONO) at n[...]4.
Infrared spectroscopic results on NO2[superscript +](HOX)(X=H,D,[superscript 35]Cl,[superscript 37]Cl) clusters showed a remarkable similarity in the chemistry of protonated nitric acid and chlorine nitrate, and two types of isomers were observed. The structure of the ground-state isomer is an ionmolecule complex, NO2[superscript +](HOX), and the second most stable isomer is a covalently bound species, (OH)(OX)NO[superscript +]. We found evidence for an IR photon-induced isomerization reaction. These spectroscopic results were quite consistent with the predictions of ab initio theory, and may provide important clues to the heterogeneous reaction mechanism involved in the depletion of stratospheric ozone.
The first infrared spectroscopic observations of gas-phase hydrated chloride clusters, [...], led to crucial suggestions concerning the structures of halide-water systems. In [...], the water forms a nearly linear hydrogen bond with the chloride ion, and in [...] and [...], the water ligands hydrate the chloride ion asymmetrically, but do not form a hydrogen bond with each other. The observed results for n = 1 and 2 showed good agreement with correlated ab initio calculations. In the n = 4 cluster, the probed structure was the one in which one [...]-bonded water ligand forms a hydrogen bond to an adjacent water ligand. In [...], a liquid-phase-like broad spectrum was observed with several peaks still apparent.
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Xu, Ren-Bin, et 許荏賓. « Solvent Extraction Separate of Valuable Metals from Spent Secondary Lithium-ion Battery ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/gr2u34.
Texte intégralRésumé :
碩士朝陽科技大學
環境工程與管理系
104
This study focused the ternary metals recycling from scrap secondary lithium batteries and explored the best operation parameters. By varied pH of extractants (P204 and P507) and metal acid solution, the affinity between extractants and different metal ions was change. The different affinity results the separation and purification of different metal ions. The four major separated targets are Co, Mn, Ni, Li, respectively. Cobalt is the most expensive one and it’s also the key metal for purification. The major results can be divided into five parts: 1. The optimum extraction ratio among different saponification degree of 10-90%: In P204 system with saponification degree of 70%, the single extraction ratio of Mn was 49.5%. The extraction ratios of Co, Ni and Li were all less than 2%. In P507 system with saponification degree of 50%, the single extraction ratio of Co was 54%. The extraction ratios of Ni and Li were all less than 3%. 2. The optimum extraction ratio among different O/A ratio of 1:4, 2:3, 1:1, 3:2, and 4:1: In P204 system with O/A ratio of 1:1, the single extraction ratio of Mn was 42%. The extraction ratios of Co, Ni and Li were all less than 2%. In P507 system with O/A ratio of 1:1, the single extraction of Co is 30%. The extraction ratios of Ni and Li were all less than 3%. 3. The optimum extraction conditions among different extractant concentration of 20 to 80%: In P204 system with extractant concentration of 20%, the single extraction ratio of Mn was 64%. The extraction ratios of Co, Ni and Li were all less than with other extractant concentration. In P507 system with extractant concentration of 20%, the single extraction of Co is 58%. The extraction ratios of Ni and Li were all less than 6%. 4. The optimum extraction parameters in single-stage extraction: In P204 system, the single extraction ratio of Mn was 61%. The extraction ratios of Co, Ni, and Li were all less than 10%. In P507 system, the single extraction ratio of Co was 55%. The extraction ratios of Ni and Li do not exceed 5%. The ternary metals of Co, Mn and Ni can be separated and purified by subsequent multi-stage extraction. 5. The optimum extraction conditions of the multi-stage countercurrent extraction (three-stage of P204 and six-stage of P507): In P204 system, three-stage countercurrent extraction ratio of Mn is 95%. Total losses of Co, Ni, and Li were less than 10%, respectively. In P507 system, six-stage countercurrent extraction ratio of Co is 95%. Total losses of Ni, and Li were less than 10%, respectively.