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1
Trenholme, W. J. F. "Metal-organic frameworks for platinum group metal extraction." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32795/.
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This Thesis describes the synthesis and characterisation of a variety of functionalised metal-organic frameworks (MOFs). These MOFs have been used for the extraction of platinum group metal (PGM) compounds from aqueous and organic solvents and for the storage of gases such as CO2, CH4 and the C2 hydrocarbons. Chapter 1 contains an introduction to PGM properties and uses with specific focus on the chemical properties which allow for separation of PGMs from base metal compounds and for separation between different PGM compounds. The synthesis and structure prediction of MOFs is then introduced, leading into an overview of the use of functionalised MOFs, especially those used for the encapsulation and extraction of metal ions from solution. General experimental techniques and details are described, as is the theory behind inductively coupled plasma optical emission spectrometry (ICP-OES), the most widely used analytical technique reported in this work. Chapter 2 describes the synthesis of chemically stable amine-functionalised Zr(IV) MOFs; UiO-68-NH2 and UiO-66-NH2, for extraction of PGM anions from aqueous and acidic solutions. ICP-OES was used to show that both materials exhibit close to 100% uptake of PtCl62- when present in just 3.5 equivalents per anion, comparable to the best materials reported for PtCl62- extraction. Furthermore, UiO-66-NH2 exhibited consistently higher PtCl62- uptake from aqueous solutions than four industrially used materials supplied by Johnson Matthey. Back-extraction of PtCl62- was demonstrated simply by heating the doped MOF in 4 M HCl, removing 99% of the PGM while maintaining the phase and crystallinity of UiO-66-NH2. Separation of PdCl62- from PtCl62- from acidic HCl solutions was exhibited by UiO-66-NH2, showing an exceptional selectivity of 20:1 for Pd:Pt from 2 M HCl. Likewise, 100% selectivity for PtCl62- and PdCl62- over CuCl2 and CuSO4 from acidic solutions was demonstrated, even in cases in which Cu was in 100-fold excess. Solid state NMR was employed to confirm the interaction between the framework and the PGM anions, with XPS results suggesting that the encapsulated Pt species within UiO-66-NH2 may be PtCl3(NH2)3 or PtCl4(NH2)2. Chapter 3 describes the synthesis and characterisation of a series of functionalised Cu(II) MOFs, NOTT-151, -155, -125 and -150, for the removal of neutral PGM complexes, Pd(OAc)2, PtCl4 and Rh2(OAc)4, from THF. The design of the MOFs allowed for an investigation into the effect of different topologies (ssa and fof), cage sizes and functional groups (amine, oxamide and methyl) on the uptake of each PGM complex. ICP-OES analysis showed that the MOFs were capable of extracting each PGM complex. The oxamide-functionalised NOTT-125 exhibited the most consistent uptake of Pd(OAc)2 with a maximum capacity of 35 mg g-1 (7 NH(CO)2NH groups per PtCl4). The amine-functionalised NOTT-155 showed the highest uptake of PtCl4, with a maximum capacity of 73 mg g-1 (4 NH2 groups per PtCl4). Uptake of Rh2(OAc)4 was generally low, however NOTT-125 showed a maximum extraction of 87 mg g-1 (3 NH(CO)2NH groups per PGM). The larger pore fof MOFs, NOTT-155 and NOTT-125, were more effective for each extraction than the MOFs of ssa topology, NOTT-151 and NOTT-150. However, of the ssa MOFs, amine-functionalised NOTT-151 was shown to give higher uptake of each PGM than the isostructural methyl-functionalised NOTT-150. This demonstrated the importance of incorporating a functional group capable of coordinating to the metal complex. Chapter 4 introduces the use of a nitrogen-rich triazine core in the synthesis of a variety of organic linkers to prepare MOFs for gas storage applications. The preparation of a novel 3,24-connected Cu(II) MOF of rht topology, denoted NOTT-160, is described and the structure characterised using X-ray crystallography. The material is shown to exhibit good uptake of C2 hydrocarbons with uptake of 128 cc g-1, 115 cc g-1, 110 cc g-1 for C2H2, C2H4, C2H6 respectively at 298 K and 1 bar (this becomes 212 cc g-1, 175 cc g-1 and 201 cc g-1 at 273 K and 1 bar). The selectivities of 79:1 and 70:1 calculated using Henry’s law for the separations of C2H2:CH4 and C2H4:CH4 respectively at 298 K are the third and second highest reported values for a MOF under these conditions. Ideal adsorbed solution theory (IAST) was also employed to calculate and predict these selectivities and shows agreement with the results obtained using Henry’s law. In addition, NOTT-160 shows an exceptional volumetric working capacity for CH4 of 221 cm3 cm-3 at 80 bar and 298 K. This is the second highest working capacity reported for a MOF under these conditions, with the excellent performance attributed to the high porosity and comparatively high crystal density of the material. Chapter 5 contains a summary of the work presented in this thesis.
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Pornsinlapatip, Pornpun. "Flow-injection solvent extraction of metal chelates." Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284394.
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Lunkov, Sergey. "Modelling metal complexation in solvent extraction systems." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/2018.
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This thesis represents a theoretical investigation of synergistic solvent extraction of transition metal ions based on models for the commercial used components, namely LIX63 and Versatic10 acid. Quantum mechanical studies of oxime isomerisation have been conducted in order to understand the thermodynamic and kinetic properties of the syn/anti interconversion of LIX63, which is found to favour an oligomeric form in non-polar solvents.
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Ge, Xinlei. "Extraction of Metal Values : Thermodynamics of Electrolyte Solutions and Molten Salts Extraction Process." Doctoral thesis, Stockholm : Skolan för industriell teknik och management, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10638.
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Healy, Mary Rose. "Outer-sphere interactions in metal solvent extraction systems." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28712.
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This work aims to define the modes of action of a series of metal extraction ligands with particular focus on how these depend on the formation of supramolecular assemblies. Though solvent extraction processes are well established industrially often the understanding, particularly of the metal coordination chemistry, is less so. A greater understanding of a variety of solvent extraction systems can lead to the development of stronger and more specific extractants. Chapter 2 examines the role of inter-ligand interactions in the extraction of copper by phenolic oximes and pyrazoles. Computational methods are used to understand the importance of inter-ligand outer-sphere interactions in square-planar copper complexes. It is shown that functionalisation at different positions on the phenol ring can either stabilise or destabilise the copper complex and it is possible to predict the strength of extractants from DFT calculations. Substitution ortho to the phenolic oxygen in the oximes and pyrazoles can have a major effect of enhancing the strength of extractants by “buttressing” the H-bonding between ligands. However, in the amino-methyl substituted oximes buttressing is so strong that is has an adverse effect on complex formation. Crystal structures are confirmed by both ENDOR EPR spectroscopy and DFT structures. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)- phenols (X = H, OMe, Br and NO2) was synthesised and characterised (X = H, OMe, Br and NO2) and the copper extractant found to be 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)- 1H-pyrazol-3-yl)-phenol extractants. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. Studies also showed that substitution can affect not only complex stability through inter-ligand interactions through hydrogen bonding in the outer-sphere but also the strength of metal-ligand bonds. Chapter 3 looks at synergistic solvent extraction systems: where more than one extractant works together to provide additional strength and selectivity. Combinations of neutral N and O donor ligands with carboxylic, phosphinic and sulfonic acids were studied by solvent extraction, crystallographic and computational methods. Crystal structures and DFT-optimised structures show that ligands and acid form pseudo-tridentate ligands where both the neutral ligand and the deprotonated acid are coordinated directly to the metal centre with inter-ligand hydrogen bonding allowing for a more flexible backbone than a classic tridentate system. Although synergistic extractions systems often utilise carboxylic acids many of the structures show the similarities with systems containing phosphinic acids and it was shown experimentally that some extraction systems show greater synergism with phosphinic than carboxylic acid in the recovery of nickel. Chapter 4 deals with the extraction of molybdenum with commercial phosphinic acid extractant Cyanex 600. The propensity for molybdenum to form oxo clusters in aqueous solutions and the influence pH in both the speciation of the Mo species and extraction conditions contributes to a complex extraction profile. The pH dependence of extraction shows that different mechanisms operate at low (pH < 0) and high (pH > 0) pH. The extraction curve shows a conventional S-curve between pH 0 and 1.5 and slope analysis within this pH range gives a value very close to two but identification of structures which match this profile is complex. Maximum pH extraction is see at ~ pH 1.5. ESMS studies identified very similar species in the organic phase despite the variation seen in the S-curve. A survey of the structures of metal complexes of phosphinate ligands suggests that molybdenum-phosphinate complexes can often form cubane-like structure and negative ion ESMS data supports the concept of cluster formation in the organic phase. A common feature of the spectra are tetra- tri- and bi-metal- oxo species and spectra show a large number of peaks. It is very probable that the extraction of molybdenum(VI) with phosphinic acids is a dynamic system as extraction is influenced by the molybdenum speciation in the aqueous phase which is in turn influenced by both the pH and the molybdenum concentration both of which change over the course of a conventional extraction.
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Brown, Stanley. "Heavy metal detoxification of sewage sludge." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302700.
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Davis, Lauren Elizabeth. "Extraction : one woman's epilepsy." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/3281.
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Boodhoo, Kishore. "Functionalised cyclodextrins for multi-metallic assemblies : towards metal extraction." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273554.
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Smith, Kate Jennifer. "Ditopic ligands for the extraction of divalent metal salts." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/12982.
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This thesis extends earlier work at the University of Edinburgh aimed at opening up new flowsheets for the hydrometallurgical recovery of base metals using tetradentate ligands which are capable of transporting metal salts {both a metal cation and its attendant anion(s)}. Prototypes were based on salicylaldimine derivatives of diamines, “salen” ligands in which coordination of a metal dication releases the two phenolic protons which are captured by pendant secondary amine groups generating a preorganised dicationic binding site for the anion(s). The thesis initially deals with the design, synthesis and evaluation of ligands to improve the strength, selectivity and speed of binding of nickel(II) sulfate by incorporating two additional donors in the salen unit to generate N2X2O22- binding sites for the nickel yielding pseudo octahedral complexes. The ligands N,N or O,O or S,S o-aminophenyl-substituted 1,2-diaminoethane, 1,2-dioxaethane, 1,3-dioxapropane or 1,2-diethioethane were also used in a screening study with some other divalent metal salts (calcium, cobalt, copper, magnesium, manganese and zinc) commonly found in the feed solutions in commercial processes. Chapter two deals with the nickel(II) coordination chemistry of a series of sexadentate (N2X2O22-) ligands. Nickel-ligand-anion complexes have been synthesised for sulfate, nitrate and chloride salts and neutral nickel-ligand complexes have been made. Crystal structures of complexes all contain the same isomer which has a planar mer arrangement of the salicylaldimato XNO- units. A “nickel only” complex for an X2N2O22- ligand with pendent piperidine groups shows that these could provide a cavity to encapsulate a single sulfate anion. All the ligands were found to be very weak extractants and showed slow complexation kinetics and phase transfer of nickel sulfate. The synthesis and characterisation of a series of tridentate ligands related to the sexadentate ligands, with NXO- binding sites, are reported in chapter three. In theory these could form complexes with a ligand: nickel ratio of 2:1, with a more nearly “ideal” octahedral donor set. Solid state structures of the ligands show them to be pre-organised with an approximately 90° X˙˙˙N˙˙˙O angle. Nickel complexes have been synthesised for sulfate, chloride and acetate salts. Analysis indicates that complexes with ligand: nickel: dianion ratios of 2:1:1 were formed. The tridentate ligands were found to be very weak extractants for nickel sulfate. Chapter four describes the screening of the potentially sexadentate N2X2O22-, tridentate NXO- and the tetradentate “salen” ligands N2O22- in which the complexation and phase transfer of calcium(II), cobalt(II), copper(II), magnesium(II), manganese(II), nickel(II) and zinc(II) sulfates and chlorides were studied.
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Barker, Michael H. "Electrochemistry at liquid/liquid interfaces for metal ion extraction." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367192.
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The aim of this project was to produce a selective extraction system for the separation of precious metal ions from waste electrolyte streams utilising liquid/liquid electrochemical techniques. During the course of this project the work partitioned into three different aspects of charge transfer: electron transfer, ion transfer and membrane studies. Some fundamental physicochemical properties of liquid/liquid systems were explored. For electron transfer reactions the dependence of the rate of electron transfer on supporting electrolyte concentration in the organic phase for the water/1,2-DCE interface was measured using the technique of interfacial electrochemical impedance spectroscopy. No dependence of the rate of electron transfer on the concentration of the supporting electrolyte in the organic phase was observed. The effect of the solvent on the kinetics of electron transfer has also been examined. The results show that the rate does not follow the expected Marcusian dependence. Several solvents previously unused for liquid/liquid studies have been screened; one solvent in particular, 1,2-difluorobenzene, shows great promise for future work. The ion transfer studies show that platinates can be separated under potential control across the water/1,2-DCE and the water/methyl isobutyl ketone interfaces. Ion transfer and separation of chloroaurate and chloroplatinates have been discussed on the basis of the Galvani potential of ion transfer. Evidence of ion pairing between the platinates and the organic supporting electrolyte cation was found. The thermodynamics of the platinate transfer have also been explored and, in collaboration with Dr Robert Deeth, preliminary density functional theory calculations have been performed to explain the experimental results in terms of a model accounting for the surface charge density of the platinates. This goes further than the classical Born approach of treating the ion as a hard sphere of charge in a dielectric continuum. The ion transfer across membranes has been studied and the results were applied to single and dual membrane supported liquid/liquid interfaces for separating platinates from base metals. [PtCl6]2- transfer across a supported liquid membrane was demonstrated. The scale–up experiments were not successful, but if certain points can be addressed, it may be possible for future studies to build on what has been achieved here. Additional to the three traditional sections of liquid/liquid work, a method of preparing gold nanoparticles has been found using ketones as the reducing agent at the water/ketone interface. The formation of gold mirrors has been observed and nanoparticles have been isolated and characterised.
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Ca, Diep Vu. "NANOSTRUCTURED ASSEMBLIES FOR SOLID PHASE EXTRACTION OF METAL IONS." Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1107552000.
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Chamupathi, Virittamulla Gamage. "Role of the interface in metal solvent extraction kinetics." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184256.
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Interfacially active reagents are utilized in metal solvent extraction processes and it is therefore important to understand the role of the liquid-liquid interface in the study of the kinetics and equilibria of extraction. The diffusion problems encountered in the traditional apparatus were overcome by using a high speed stirring apparatus. The microporous teflon membrane phase separator permitted more accurate measurements of interfacial areas, characterization of extraction kinetics of metal chelates, and a greater understanding of the phase separation mechanism. In contrast to the neutral ligands, the anionic ligand of dithizones and substituted dithizones showed significant interfacial adsorption at the chloroform/water interface as monitored spectro-photometrically. Equilibrium studies on p-halodithizones indicated that the adsorption constant increased as the substituent was altered from chloro to bromo to iodo, and with the distribution ratio of the ligand. Kinetic studies on dithizone and p-iododithizone with Ni(II) and Zn(II) indicated that the extent of participation of the interface in solvent extraction kinetics of these metal ions is dictated by the interfacial activity of the extractant and the mechanisms of the rate limiting step in the bulk aqueous and interfacial regions.
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Rashid, Salman Ghanem. "Studies on copper extraction with hydroxyoxime extractants for the design of hollow fibre membrane based extraction processes." Thesis, University of South Wales, 1999. https://pure.southwales.ac.uk/en/studentthesis/studies-on-copper-extraction-with-hydroxyoxime-extractants-for-the-design-of-hollow-fibre-membrane-based-extraction-processes(7e631b77-71e2-4d6e-8c03-4636d42f9f69).html.
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This work has included a review of the most relevant aspects of measurement techniques and mathematical models proposed in the literature to assess the equilibrium and mass transfer data of metal extraction by the use of chelating agents. The limitations of these techniques and models have been highlighted. Three chelating extractants diluted in EscaidllO were used to study the extraction equilibrium of copper. The extractants are 5-nonylacetophenone oxime (LIX84®), 5- dodeylsalicylaldoxime (LIX860®) and 50/50 v/v mixture of both oximes (LIX984®). The copper concentration changes in the aqueous and the organic phases were monitored by using atomic absorption spectrophotometer. Two mathematical models (a chemical model and a semi-empirical model) have been developed in this study to predict the equilibrium data of copper sulfate/hydroxyoxime system. The chemical model was found to fit all the three equilibrium systems (CuSO4/LIX84®, LIX860®and LIX984®) equally. The semi-empirical model based on Freundlich's adsorption equation was also found to fit the three systems but with less accuracy. The mass transfer characteristics and properties of copper extraction and recovery from an aqueous solution using LIX984® were studied using dispersion-based (rising drops) and dispersion-free techniques. In the dispersion-based technique the organic phase was dispersed in form of drops at the tip of hypodermic needle while the aqueous solution was used as a continuous phase. The extraction process was carried out in four different height columns under wide range of conditions. The effects of the columns' height, the dispersed and the continuous phases concentrations on the metal rate of mass transfer were investigated. It has been found in that the metal's rate of mass transfer and system's overall mass transfer coefficient have remained constant in all four columns. A model utilising the two-film theory, some of the dimensionless groups and the experimental results has been proposed in this work to calculate the local mass transfer coefficients in the dispersed phase and the continuous phase. The overall mass transfer coefficient and the calculated local coefficients were used to account for the reaction rate constant at the interface from the sum of the individual resistances to mass transfer. A dispersion-free technique consisting of a microporous hollow fibre module was used in this study to examine the mass transfer properties of the extraction and stripping processes of copper across an immobilised interface system. The extraction and re-extraction (stripping) processes in this system were conducted under a wide range of operating conditions and produced satisfactory results. In general it has been found that counter current flow arrangement gave higher concentration driving forces which were reflected in form higher metal concentrations at the extract phase. A generalised mathematical model was developed in this study which utilised Wilson's method, the experimental data, some dimensionless groups and the two-film theory to account for local resistances and predict the system's overall mass transfer coefficient. A correlation was established first to calculate mass transfer coefficients using a form of Leveque's equation which relates the two phase's physical properties and the system's parameters. The membrane mass transfer coefficient was calculated from the structural properties of the membrane material. While the resistance at the reaction interface was calculated under set of experimental conditions. The individual coefficients were then used to predict the overall mass transfer coefficient under any set of conditions by using the aditivity approach of the individual resistances to mass transfer. However, further checks and investigations are necessary to validate this model over variety of extraction systems and membrane configurations.
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Wang, Jin 1954. "Extraction of heavy metals with supercritical carbon dioxide : a novel approach to heavy metal analysis and decontamination." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39890.
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The technique of extraction with supercritical carbon dioxide (SC-CO$ sb2$), which is now used routinely for the recovery of non-polar analytes from a variety of liquid and semipermeable solid media, was extended to the efficient extraction of metal ions. Measurements of the solubilities in SC-CO$ sb2$ corroborated the hypothesis that the non-polar character of a series of tetraalkylammoniun dialkyldithiocarbamates ion pairs was influenced (i) primarily by the chain length of the alkyl substituent(s) on the carbamate nitrogen and (ii) to a lesser extent, by the chain length of the alkyl substituent(s) on the ammonium counter ion. In operation, analyte metal(s) in aqueous medium was derivatized by in situ complexation with the dithiocarbamate complexing reagent and the product complex(es) was partitioned into the SC-CO$ sb2$ mobile phase then purged from the extractor by replacing the headspace with fresh solvent. A novel silica flame-in-tube interface was developed for the sensitive detection, by atomic absorption spectrometry (AAS), of As, Cd, Cu, Mn, Pb, Se, or Zn in SC-CO$ sb2$ extractor eluate. For different analyte elements, the limits of detection (LODs) ranged from sub-nanogram to low picogram if standard was flow injected into the mobile phase. These sensitivities permitted differences in the rates of mobilization of different forms of the analyte metal from various media to be explored as a technique for probing the interaction of the analyte metal with the matrix. A portion of the Zn burden in fresh bovine liver was mobilized rapidly in the absence of complexing agent and the remainder was solubilized more rapidly than the Zn in a freeze-dried reference material of this tissue. The nebulizer assembly of a conventional flame-AAS was modified to extend the range of metals amenable to on-line detection. Supplemental heating of the inlet air to 200$ sp circ$C resulted in an on line detector which provided approximately a ten-fold improvement over convention
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Premaratne, Wijendra A. P. Jeewantha. "Mineral chemistry and metal extraction of Sri Lanka beach sands." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404128.
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Mead, D. A. "Investigation of the supported liquid membrane process for metal extraction." Thesis, University of Hertfordshire, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376472.
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Doidge, Euan Douglas. "Designing reagents for the solvent extraction of critical metal resources." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31070.
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The work in this thesis aims to develop new systems for the more efficient recovery of metals from aqueous solution using solvent extraction. Understanding the underlying coordination chemistry to improve hydrometallurgical methods is crucial in order to meet the demand for critical metals for use in modern technologies, reduce the environment impact of recovery from primary mining deposits, and recycle valuable metals from secondary sources (e.g. mobile phones, WEEE). Chapter 2 examines the use of a simple primary amide that can load gold and other chloridometalates into a toluene phase through an outer-sphere mechanism. The loading of a variety of metals/metalloids from varying [HCl] is reported, highlighting the selectivity for gold over other metalates and chloride due to a combination of speciation of those metals and the relative ease of extraction of lower charged species (the Hofmeister bias). The advantages in loading/stripping, toxicity and mass balances compared to commercial alternatives are also outlined, in particular the efficacy of separating gold from a mixed-metal solution representative of those found in WEEE. The mode of action of the primary amide (and secondary/tertiary analogues) is determined using slope analysis, Karl-Fischer water determinations, NMR and MS measurements, EXAFS and computational models. The extraction occurs by the dynamic assembly of multiple amide ligands and gold metalates to generate supramolecular clusters held together through hydrogen-bonding and electrostatic interactions. The secondary and tertiary amides are found to be able to extract monoanionic metalates in a similar manner as the primary amide, although clustering occurs to a lesser extent. Whilst the secondary and tertiary amides are stronger gold extractants than the primary amide, they are not observed to be as successful when extracting from a mixed-metal solution. Instead, a 3rd phase is seen to form from these amides and some metals at higher metal concentrations, which removes the ligands from solution and prevents successful extraction of gold. Chapter 3 builds on an observation in Chapter 2 that a synergistic combination of a simple primary amide and an amine can extract chloridometalates that are typically difficult to solvent extract, such as iridium(III) and rhodium(III). These metalates, complexes with increased anionic charge and varying speciation in aqueous solution, are typically recovered last in a metal production flowsheet. The combination of a primary amide and primary amine was found to be the most effective at extracting the chloridometalates; the strength and strippability of the system is of particular interest in the context of rhodium(III) recovery as this metal currently is not extracted in commercial circuits. The mode of action of the system is investigated using similar techniques to Chapter 2, and reveals that the amine is the more important component of the synergistic mixture compared to the amide, with an improvement in extraction observed when both components are present. Rh(III) is extracted as a mixture of RhCl6 3– and RhCl5(OH2)2– complexes, dependent on the initial [HCl] concentration and the age of the initial aqueous solution. Chapter 4 investigates the feasibility of the recovery of lanthanides as anionic metalates from chloride-, nitrate- or sulfate-rich feeds. Reagents that have been found to be strong chloridometalate extractants, fragmented versions of these, and ‘classic’ commercial outer-sphere reagents are studied. The variations of ligand, anion type and concentration, proton concentration and solvent for the extraction of lanthanides is investigated. However, despite these permutations, no extraction of lanthanides is observed due to the difficulty in extracting more highly hydrated species and the lack of stability of the metalates in aqueous solution.
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Tucker, Kate Louise. "Heavy metal extraction using advanced liquid-liquid style partitioning systems." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/heavy-metal-extraction-using-advanced-liquid--liquid-style-partitioning-systems(6a238cb4-94cf-4fa8-bffe-d1a1b70adaa6).html.
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Understanding the behaviour of heavy metals involved in the nuclear fuel cycle is of paramount importance to the reprocessing and storage of spent nuclear fuel. These studies have attempted to obtain a greater understanding of the fundamental chemistry of these systems, by investigating extraction performance and speciation in current (PUREX) and proposed (GANEX) extraction processes. Various complexes have been shown to exist in the post-extracted organic fraction of the systems analysed. For Zr(IV), U(VI) and Np(VI) separated from aqueous nitric and hydrochloric using TBP, the complexes [Zr(NO3/Cl)4(TBP)4], [UO2(NO3/Cl)2(TBP)2] and [NpO2(NO3/Cl)2(TBP)2] formed, respectively. For Zr(IV) separated from aqueous mixtures of HNO3 and HCl at equal concentration, a preference was shown to [Zr(Cl)4(TBP)4] over the analogous nitrate complex. For U(VI) separated from aqueous mixtures of HNO3 and HCl, a preference was shown to [UO2(Cl)2(TBP)2], even at high aqueous nitrate concentrations. NMR data for Pu(IV) separated from aqueous HNO3, HCl and mixtures of both, using TBP were presented, where possible complexation was observed. It is thought that [Pu(NO3)4(TBP)4] or [PuCl4(TBP)4] species existed within the organic fraction for Pu(IV) separated from aqueous HNO3 and HCl, respectively. These systems showed high distribution ratios where an increase was observed with increasing aqueous acid concentration overall. Distribution ratio data were presented for the lanthanide series separated from aqueous nitric acid, using the proposed GANEX solvent system(s). The lanthanides analysed showed an increase in distribution ratio with increasing aqueous nitric acid concentration and with increasing TODGA concentration in the organic fraction. Heavier lanthanides were observed to give higher distribution ratios overall. The best distribution ratios were observed for lanthanides separated using 0.2 M TODGA with 1-octanol (5 % by volume) over the nitric acid concentration range analysed. For lanthanides separated using 0.5 M DMDOHEMA, an optimum distribution ratio was observed at around 6 M aqueous nitric acid concentration. The distribution ratio data for lanthanides separated from a range of DMDOHEMA concentrations, were observed to increase with increasing organic DMDOHEMA concentration. The distribution ratios observed for isotopes of Np, Am, Eu and Pu separated using 0.2 M TODGA, increased with increasing aqueous nitric acid concentration. The same trend was observed for the aforementioned isotopes separated using 0.5 M DMDOHEMA. However, pertechnetate separated using 0.2 M TODGA from aqueous nitric acid, showed a decrease in the distribution ratios observed over the acid concentration range analysed. This was contrary to pertechnetate separated from aqueous nitric acid using 0.5 M DMDOHEMA, where a small increase in distribution ratio was observed over the concentration range analysed. For Np(VI) separated from some proposed GANEX solvents, the 0.2 M TODGA/0.5 DMDOHEMA combination gave the best distribution of neptunium into the organic fraction. For Np(VI) separated using 0.5 M DMDOHEMA, the complex [Np(DMDOHEMA)2(NO3)4] was observed. Additional attempts to analyse Np(VI) behaviour under GANEX style conditions via EXAFS, were not successful due to immediate reduction of the Np(VI) on the beam line.
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Hildreth, Scott A. "Statistical SPICE parameter extraction for an N-Well CMOS process /." Online version of thesis, 1995. http://hdl.handle.net/1850/12177.
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Galbraith, Stuart G. "Ditopic ligands for the selective solvent extraction of transition metal sulfates." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/10911.
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The thesis considers the development of new reagents which could transport transition metal salts in extractive hydrometallurgy and addresses the ligand design features which are needed to control the strength and selectivity of binding of both a particular metal cation and its attendant anions(s). Extractive metallurgy of base metals is surveyed in chapter 1 and suggests that more efficient recovery processes are needed. One new approach, which could lead to much better materials balances in many cases, is to use hydrometallurgical techniques which involve co-extraction and transport of metal cations and their attendant anion(s). The problems in obtaining the selective extraction of anions makes the development of such a process very challenging, especially for hydrophilic anions such as sulphate which would be present in many pregnant solutions generated in processing sulfides ores. The rapidly emerging field of anion coordination chemistry and approaches to the development of selective ligands are discussed. Chapter 2 focuses on the pH dependence of sulfate-loading from an aqueous solution into chloroform solutions of a selection of zwitterionic ditopic ligands containing two 3-dialkylaminomethylsalicylaldimine units. These “salen-type2 ligands have quadridentate N2O22- binding sites for divalent metal cations and the cis-coordination of the phenolate aligns the pendant protonated 3-dialkylaminomethyl groups to bind to a sulfate dianion. Studies of the pH dependence of sulfate-loading confirm that sulfate binding is enhanced significantly by the incorporation of a divalent cation such as Cu2+ in the salen N2O22- site. Metal dication loading is very dependent on the nature of the bridging group between the two imines in the “salen” unit; Cu2+ loading follows the order ortho-phenylene > 1,2-ethane > 2,2’-biphenyl. The ethane-bridged ligand, 4,4’-di-tert-butyl-6,6’-bis(dihexylaminomethyl)-2,2’-(ethylenedinitrilodimethylidyne) diphenol, was found to have a nearly ideal loading profile for CuSo4. Stability to hydrolysis and oxidation is a key requirement for commercial metal solvent extractants. The stability of the imine bond in the “salen-type” extractants investigated in chapter 2 was tested in a two phase chloroform: water systems under conditions likely to be used for loading or stripping of metal salts. Stability is dependent on the nature of the bridging unit between the two imines varying in this order 2,2’-biphenyl > ortho-phenylene > 1,2-ethane. Two new ligands, 4,4’-di-tert-butyl-6,6’-bis(dihexylaminomethyl)-2,2’-(ethylenedinitrilo-1,1’-phenyldimethylidyne) diphenol and N,N’-dimethyl-N,N’-bis(2-hydroxy-3-[(E)-phenyliminomethyl]-5-tert-butylbenzyl)hexane-1,6-diamine, which exhibit improved stabilities at low pH are also discussed.
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Chatreewongsin, Urai. "Metal Extraction From Soil Samples By Chelation in a Microwave System." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/26982.
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This work involves the combination of chelation and microwave extraction as a technique for extracting adsorbed metals in soil. It has been termed in this work, Chelate Assisted Microwave Extraction (CAME). Unlike other extraction methods, CAME is able to differentiate between anthropological and geological trace metals.
The method has been applied to major sample matrices included three types of soils (Bertie Sandy Loam, Davidson Silty Clay, and Davidson Clayey Loam) as well as sea sand, alumina, and iron oxide. In order to investigate the effects of sorptive coatings on metal concentrations, a sample set was first treated with humic acids, which represented organic coated materials. Afterwards, copper (II) solutions were spiked to both untreated and treated matrices and the efficiencies of recoveries were studied. Metal determinations were performed by Inductively Coupled Plasma-Atomic Emission Spectrophotometry (ICP-AES).
Initial studies of control (untreated soil) and long-term Cu amended (spiked) Bertie Sandy Loam (BSL) indicated that extraction efficiencies were method dependent. Ethylenediaminetetraacetic acid (EDTA) was a primary chelating agent used for method comparisons. Extracting solutions having a pH range from 7.8 to 10.1 did not affect the EDTA-microwave method, but the increase in pH enhanced Cu removal by the EDTA-shaking extraction method which was a conventional chelation using a mechanical shaker. With the EDTA-microwave method, complete extraction was achieved in a short period of time (20 minutes). Compared to the EDTA-shaking method using two sandy soils, the EDTA-microwave method proved to be more efficient in extracting sorbed metals in soils (5.9 vs. 4.6 µg/g for the control BSL and 37.5 vs. 27.8 µg/g for the amended BSL.
FT-IR and C13 NMR were used to characterize extracted and commercially available humic acids. The latter was employed to prepare the humate coated materials. Iron oxide containing materials such as Davidson Silty Clay (DSC), Davidson Clayey Loam (DCL), and iron oxide (Fe2O3), showed extremely high adsorption capabilities for humic acids, while sea sand, Bertie Sandy Loam, and alumina (Al₂O₃) provided lower adsorption capabilities for humic acids. Two sets of uncoated and humate coated materials were used for Cu spiking procedures using 0.001 M Cu (II) at pH 5.3 for 24 hour-equilibration. Three original soils and alumina showed high adsorption capabilities for Cu (II). The presence of coated humate helped increase Cu adsorption capabilities of these soils, but diminished the ability of alumina to react with Cu (II) ions. For HA-uncoated matrices, iron oxide had a higher Cu adsorption capability than sea sand but less than real soils. Humate coating improved Cu adsorption capabilities of not only real soils but iron oxide and sea sand as well.
Lastly, the developed method named Chelate Assisted Microwave Extraction (CAME) was further examined and optimized. Several samples were investigated for extraction efficiencies. A two-step extraction, applying 120 W for 5 min followed by 60 W for 10 min, was efficient in removing sorbed metals from different matrices regardless of sorptive oxide and organic components. Concentrations of chelating agents slightly affected percent metal removal; however, there was no significant difference in results obtained using EDTA or diethylenetriaminepentaacetic acid (DTPA). Recoveries of spiked metals (Cu and Cd) ranged from 96 to 107%. Using the untreated (control) Davidson Silty Clay and Bertie Sandy Loam, the comparison of other chelating solutions were made. Clearly, CAME was promising and proved to be a good alternative to classical shaking method for extracting adsorbed metals from soils.Ph. D.
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DESHPANDE, SUSHILENDRA ARUN. "FEATURE EXTRACTION AND INTRA-FEATURE DESIGN ADVISOR FOR SHEET METAL PARTS." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1070392705.
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Howard, Maury Elizabeth. "Characterization of synthetic biopolymeric chelators for trace metal extraction and recovery /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Jabbour, Rabih Elie. "Characterization of selected immobilized metal-ions using solid phase extraction sorbents." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282773.
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Solid phase extraction (SPE) has been developed as an alternative to liquid-liquid extraction (LLE) in the sample preparation process. The advantages of SPE over LLE are that it is a more useful, reliable tool for sample preparation, which offers greater selectivity. The selectivity of an SPE sorbent is vital for the isolation of analyte from a biological matrix containing a myriad of interferences. The use of conventional ion exchange SPE for such an extraction process might not be adequate due to the adverse effects of interfering ions. Metals immobilized on various modified silicas were investigated to determine if the addition of metals improved selectivity. The selectivity of these sorbents was studied by the extraction of analytes from high ionic strength matrices. Extraction selectivity was found to depend on different factors, including the type of bonded species, metal ions used and the analytes, counter ions, sample pH and elution solvent composition. Utilizing coordination complexation between analytes and immobilized metal ions, particularly when different phases are stacked, can increase selectivity for a particular analyte. Metals immobilized by ionic exchange sorbents were observed to retain analytes of tridentate chelation capability more than immobilized metals on bonded chelators. However, bonded chelators were observed to be advantageous because they more strongly retained metal ions, relative to ionic exchangers. The interactions of immobilized silver ions with unsaturated molecules utilizing SPE were investigated. Retention of silver ions was found dependent on the nature of bonded phase. The silver ions immobilized by coordination interactions showed weaker retention than silver immobilized by ionic interactions. Retention of alkenes by silver was found to have higher flow dependence, as compared to ionic exchange or ligand exchange processes. Retention of analytes was observed to depend on a variety of factors, including the type of bonded phase used for silver immobilization, the composition of the elution solvent, steric factors, the degree of unsaturation, the geometry and position of the double bonds of the analyte molecules. Extraction selectivity for geometrical isomers decreased when silver ions were immobilized by long chain cation exchangers versus those on conventional short chain cation exchangers.
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Angarita, Fonseca Maria Paula. "Electrolytic extraction of a metal from its metal compound: estimates of optimal energy requirements and their consequences." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98004.
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Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 62-66).
To ensure the sustainability of a world whose growing population demands more materials, products, and energy, we must closely examine the sustainability of the industries that supply them. Metal-making industries encounter an opportunity space at the extraction stage of a metal life cycle when aiming at making a significant impact in energy efficiency and carbon emission mitigation. We first develop a thermodynamic model that establishes the technical criteria for the most efficient operation of an electrolytic cell for a variety of metals. Second, we explore the rigidity of the operating boundary conditions and their impact on energy consumption. We then proceed to examine the energy and carbon impact of a hypothetical electrolytic ferrochromium operation in the United States. This case study demonstrates that the thermodynamic model can serve as a reference framework through which diverse stakeholders can compare the environmental impact of existing and innovative metal extraction processes in order to make informed decisions about environmental regulation, investments, subsidies, and mineral resource management.
by Maria Paula Angarita Fonseca.
S.M. in Technology and Policy
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Diffin, B. "The mechanism of metal detoxification of waste activated sludge by pH depression." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353776.
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Adams, Robert Jonathan Watt. "The extraction of caesium and cobalt(II) from solution using inorganic ion exchangers in electrochemical ion exchange." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385171.
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Copham, Piers Martin. "Rotating electrodes in molten salt electrowinning." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330202.
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Lopian, Tobias. "Characterization of a metal-extracting water-poor microemulsion." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT206/document.
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Le recyclage des terres rares à partir de déchets électroniques n'a toujours pas trouvé une réalisation industrielle significative. L'une des raisons est le manque de procédures de séparation optimisées en raison de connaissances fondamentales médiocres sur ces systèmes. En raison des similitudes chimiques et physiques de ces métaux, la conception d'une formulation efficace, adaptative et prédictive est toujours hors de portée des possibilités. L'interprétation supramoléculaire de la formation complexe dans la phase organique est de plus en plus importante au cours des dernières années. C'est l'approche la plus prometteuse permettant l'explication de divers phénomènes, tels que la formation de la troisième phase et les signaux forts dans de petites expériences de diffusion et de revenir à des méthodes bien connues de la science des tensioactifs. Notre contribution à une compréhension plus complète dans cette matière est l'analyse du comportement électrodynamique de ces phases et la corrélation de ces résultats avec les résultats des propriétés d'auto-assemblage et du transport de masse dans ces médias. Pour cette étude, nous avons spécifiquement conçu un modèle de référence, en passant un processus d'extraction à ses quatre composants fondamentaux: l'extracteur avant l'extraction (acide Di-(2-éthylhexyl) phosphorique, HDEHP), l'extrait après extraction (son sel de sodium, NaDEHP ), le toluène comme diluant apolaire et de l'eau. Un prisme de phase de Gibbs a été préparé (illustré sur la figure 1), où l'axe z donne le rapport de HDEHP à NaDEHP, ce qui représente le développement d'une extraction. Couvrant le domaine de basse fréquence, la spectroscopie d'impédance a été la méthode de choix afin de déterminer la conductivité dépendant de la fréquence. En utilisant la spectroscopie de relaxation diélectrique, nous révélons des processus dynamiques rapides à haute fréquence. Des mesures combinées SAXS et SANS ont été effectuées pour comparer les tendances électrodynamiques avec les propriétés d'agrégation et les interactions entre groupes. Deux phénomènes ont été identifiés comme responsables du profil de conductivité dans les systèmes micellaires inverse: la formation d'agrégats chargés par la dissimulation et la percolation. Tout au long du système de référence, ces deux processus ont été sondés en fonction de trois variables: la concentration totale d'agent d'extraction, le rapport eau-agent tensioactif et le rapport Na: H. En tant que résultat majeur, l'eau joue un rôle important dans les deux processus. En cas de percolation, les agrégats inverse ne peuvent pas fusionner en l'absence d'eau. Par conséquent, la conductivité électrique est interdite. Dans les systèmes dilués, l'eau facilite le processus de dismutation, entraînant une augmentation de la conductivitéRecycling of rare earths from electronic waste has still not found a significant industrial realization. One reason is the lack of optimized separation procedures due to poor fundamental knowledge on these systems. Due to the chemical and physical similarities of these metals, designing an efficient, adaptive and predictive formulation is still out of scope of possibilities. The supramolecular interpretation of complex-formation in the organic phase has gained an increasing importance in the last years. It is the most promising approach allowing the explanation of diverse phenomena, such as third phase formation and strong signals in small scattering experiments and to revert to methods well known from surfactant science. Our contribution towards a more complete understanding in this matter is the analysis of the electrodynamic behaviour of such phases and the correlation of these findings with the results of self-assembly properties and mass transport in these media.For this study, we specifically designed a reference model, breaking an extraction process down to its four fundamental components: The extractant before extraction (Di-(2-ethylhexyl)phosphoric acid, HDEHP), the extractant after extraction (its sodium salt, NaDEHP), toluene as apolar diluent and water. A Gibbs phase prism has been prepared (illustrated in Figure 1), where the z-axis gives the ratio of HDEHP to NaDEHP, representing the development of an extraction. Covering the low frequency-domain, impedance spectroscopy has been the method of choice in order to determine the frequency-dependent conductivity. Using dielectric relaxation spectroscopy, we reveal fast dynamic processes at high frequencies. Combined SAXS and SANS measurements have been performed to compare the electrodynamic trends with aggregation properties and intercluster interactions.Two phenomena have been identified to be responsible for the conductivity profile in reverse micellar systems: the formation of charged aggregates through dismutation and percolation. Throughout the reference system, these two processes have been probed as function of three variables: total extractant concentration, the water-to-surfactant ratio and the Na:H-ratio. As a major result, water plays a significant role in both processes. In case of percolation, reverse aggregates are not able to merge in the absence of water. Therefore, electrical conductivity is prohibited. In dilute systems, water facilitates the dismutation–process leading to an increase in conductivity
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Mebrahtu, Fanuel M. "Transport and extraction of Au(lll) using thiourea ligands." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50206.
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Thesis (MSc)--Stellenbosch University, 2004.ENGLISH ABSTRACT: A series of di- and mono-substituted acyl(aroyl) thioureas were examined for the extraction and transportation of Au(III). Two-phase metal ion extraction experiments were employed to investigate the extraction behaviour of these ligands. The effect of varying ligand concentration on the extraction trend of these ligands was investigated. The results show that the different substituent groups on the benzoyl ring can affect the extraction pattern of the metal. Furthermore, the alkyl substituents on the thiourea moiety and varying the ligand concentration have an influence on the percentage of metal ion extracted. With the exception of the H2L2(N,N-di-propyl-N'- benzoylthiourea ) ligand the di-alkyl substituted thioureas were more efficient for the metal ion extraction than the mono-alkyl ligands. In almost all the experimental set ups there was reduction of the Au(lIl) to Au(l) and Au(O) but it was more pronounced with HL3 (N,N-di-(2-hydroxyethyl)-N'-benzoylthiourea). Transport experiments were also conducted, the experimental set up for transportation was a concentric type cell involving a 3-phase system - 2 aqueous phases ( source and receiving phase) separated by a chloroform membrane incorporating the ligand. The transport results however only gave a satisfactory result of about 5% of gold transported by the HL1 (N,N-dibutyl-N'-benzoylthiourea). All other ligands attempted resulted in metal ion being present in the organic phase, but no metal ion present in the receiving phase. To help drive the transport of the metal ion to the receiving phase CN-, S203 2- and perchloric acid were incorporated into the receiving phase. The transport results were not enhanced with these substances being present in the aqueous receiving phase. The aqueous source and receiving phases were analyzed by flame atomic absorption spectroscopy (FAAS). Finally the N,N-diethyl-N'-camphanoylthiourea (HL10) ligand and its complex with Au(l) were synthesised. Single crystals of the complex were grown for X-ray crystallography and the crystal and molecular structure of the complex was determined. The complex crystallizes in the monoclinic space group P21. The cell parameters are a = 10.7356(7)A b = 16.3443(11)A c = 10.9268(7)A f3 = 103.1450(10t , and final R-factor of 1.76%. The coordination sphere around Au(l) shows a nearly linear arrangement of sulphur and chloride.
AFRIKAANSE OPSOMMING: In hierdie proefskrif is In aantal mono- en di-gesubstitueerde asiel(ariel) thioureums ondersoek vir die transportasie en ekstraksie van Au(III). Twee-fase metaalioon vloeistof-vloeistof ekstraksie eksperimente is gebruik om die ekstraksie patroon van hierdie ligande te ondersoek. Die effek van verskillende ligand konsentrasies op die ekstraksie neiging van hierdie ligande is ondersoek. Resultate toon dat die verskillende substituente op die benziel ring die ekstraksie patroon van die metaalioon beïnvloed. Verder, is gevind dat die alkiel substituente op die thioureum saam met varierende ligand konsentrasies geensins die metaalioon ekstraksie beïnvloed nie. Met die uitsondering van H2L2 (N,N-dipropiel-N'-benzielthioureum) is die di-alkiel gesubstitueerde ligande meer effektief vir metaalioon ekstraksie in vergelyking met die mono-alkiel ligande. In baie van die eksperimente is In reduksie van Au(llI) na Au(l) en Au(O) gesien en dit is baie duidelik met ligand HL3 (N,N-di(2- hidroksie-etiel)N'-benzielthioureum). Alle waterige fases is ge-analiseer met gebruik van Atoomabsorpsie Spektroskopie (AAS). Transportasie eksperimente is ook uitgevoer met gebruik van In drie-fase selsisteem. Twee waterige fases (bron- en ontvang-fase) is geskei met die chloroform membraan fase wat die ligande bevat. Hierdie eksperimente het net In 5% Au(lll) transportasie getoon met HL1(N,N-dibutiel-N'-benzielthioureum). Daar was geen transportasie van Au(lIl) met enige van die ander ligande. Analise van die twee waterige fases het getoon dat die metaalioon eindelik goed ge-ekstraeer is en is teenwoordig in die membraan fase. Om die transportasie van Au(lIl) aan te spoor, is CN-, s2ol- en perchloorsuur in die ontvang-fase geinkorporeer. Die resultate was geensins beïnvloed nie. N,N-di-etiel-N'-kamfonielthioureum (HL10)ligande en die kompleks daarvan met Au(l) is ook gesintetiseer. Enkel-kristalle van die kompleks is verkry en X-straal kristallografiese analiese is onderneem. Hierdie kompleks kristalliseer in die monokliniese ruimtegroep P21,met a =10.7356(7)Á, b=16.3443(11)Á, c=10.9268(7)Á en ~=103.1450(10t. Die finale R-faktor is 1.76%. Die koordinasie om Au(l) toon In liniêre geometrie met swael en chloor.
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Squires, Clare. "Ligand self assembly to enhance the strength and selectivity of metal extraction." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/14470.
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The strength and selectivity of commercial phenolic oxime copper extractants are thought to be due to the hydrogen-bonded pseudo-macrocycle which this ligand forms around copper. This thesis investigates the role of hydrogen-bonding of sulfonamido ligands to determine the importance of ligand association prior to and upon complexation. Chapter 2 deals with the coordination chemistry of a series of 11 relatively simple bidentate monosulfonamidodiamine ligands. The solid state structures of these ligands are difficult to predict and illustrate that a surfeit of hydrogen-bond donors and acceptors incorporated into a relatively flexible ligand leads to a variety of hydrogen-bond interactions in the solid-state and hence a range of complicated secondary structures are observed including two and three dimensional arrays. However, these ligands do form pseudo-macrocycles around copper and nickel(II) centres. These ligands were found to be quite weak (pH1/2 4-6) extractants when used in pH-swing process. Increasing the size of the chelate ring from five to six leads to even weaker extractants. In Chapter 3 the synthesis and characterisation of a series of 6 sulfonamido-oxime ligands which have a similar backbone to the commercial ortho-phenolic oximes are described. The majority of solid-state structures contain hydrogen-bonded dimers and appear to have structures which are independent of small substituent changes in the ligand. However the E, Z isomerisation of the oxime is important. The Z isomer only forms polymeric species. Complex formation by the sulfonamido-oxime ligands is less predictable than with the monosulfonamidodiamines and both 2:1 and 1:1, ligand to metal complexes are observed. In addition to the expected bonding of the sulfonamido and oximic nitrogen atoms, the bonding of the sulfonamido oxygen atoms and the deprotonated oximic oxygen atom to metal ions is also observed. Investigation of the solution chemistry of the monosulfonamidodiamine and the sulfonamido-oxime ligands are considered in Chapter 4. ESI-MS shows evidence for dimer formation and 1H nmr, VPO and IR analyses show that self-association occurs in solution and is very concentration, temperature and solvent dependent. This chapter also discusses the development of monosulfonamidodiamine and sulfonamido-oxime ligands with higher solubility in solvents of low polarity such as toluene. The possibility of developing sulfinamido ligands is also discussed covering the synthesis of sulfinyl chlorides and the attempted preparation of prototype sulfinamido ligands. Chapter 5 deals with the development of pseudo-macrocyclic and pseudo-cage structures using ternary metal/sulfonamide/amine systems. Bis- and tris-sulfonamido ligands have been synthesised and their solid state structures were investigated. The formation of metal complexes of these ligands proved difficult and no ternary complexes were isolated.
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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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Ager, Patrick. "Mobilizationpurging of aqueous metal ions into supercritical carbon dioxide." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20553.
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The technology of supercritical fluid extraction (SFE) offers the opportunity to efficiently extract both relatively non-polar analytes as well as ionic materials (such as metal ions) that can be mobilized with the addition of complexing reagents. The nebulizer of a conventional flame atomic absorption spectrometer (FAAS) was modified to extend the range of metals amenable to on-line detection. The flow injection thermospray-FAAS (FI-TE-FAAS) interface provided efficient detection for a variety of less volatile elements (Co, Cr(III), Cr(VI), Fe, Ni, Mn and Al) present as ions in aqueous media or as complexes in the supercritical fluid (SC-CO2) carrier phase. The range of possible metal analytes that can be monitored has been increased over the nine elements (Ag, As, Cd, Cu, Hg, Mn, Pb, Se and Zn) that could be detected with an all-silica interface. The acetylacetonate complexes offered considerable potential for metal detection in an SC-CO2 carrier phase. Limits of detection (LODs) were used to compare the instrument responses to different metals. (Abstract shortened by UMI.)
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Rinsant, Damien. "Elaboration de matériaux hybrides fonctionnalisés de type MOFs pour l’extraction sélective de l’uranium." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS062.
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L’offre en combustible nucléaire à base d’uranium est un enjeu clé de la stratégie française de production d’électricité, d’autant plus que la demande en uranium naturel continuera à augmenter dans un futur proche. Il y a donc un intérêt à proposer de nouveaux procédés d’extraction de l’uranium plus efficaces et plus écologiques que ceux utilisés actuellement. L’objectif de cette thèse est donc de valoriser l’uranium issu des lixiviats de minerais par des procédés de séparations solide-liquide avec des matériaux de type Metal Organic Framework (MOF). Les MOFs sont des matériaux hybrides, cristallins présentant des surfaces spécifiques élevées et présentant d’excellentes performances pour l’adsorption de l’uranium dans des solutions à faible acidité.Pour répondre à cet objectif, la stabilité de plusieurs familles de MOFs a été étudiée au cours du temps dans des solutions acides simulant les lixiviats de minerais. Après quoi, des MOFs à base de zirconium et de ligand diacides carboxyliques fonctionnalisés par des amines tertiaires et des ligands amidophosphonates ont été synthétisés puis caractérisés par DRX, BET, ATG, MEB, FT-IR et RMN. Trois matériaux de type MOFs ont été étudiés permettant de comparer deux fonctions extractantes et deux porosités différentes. Pour cela des acquisitions de données d’extraction de l’uranium en milieu sulfurique ont été réalisées en fonction du temps, de la concentration en uranium, de la concentration en sulfate et du pH. L’ensemble de ces données couplé avec des analyses spectroscopiques ont permis de proposer des mécanismes d’extractions de l’uranium pour les deux fonctions extractantes étudiées.Mots-clés : MOFs, synthèse organique, extraction solide-liquide, uraniumThe increase of world energy production involves the research and development of new more efficient and ecofriendly processes for uranium ores valorization. Therefore, the development of new materials for an efficient solid-liquid extraction of U is necessary. In this thesis, the synthesis of materials named Metal Organic Framework (MOF) and their use to the uranium extraction from ores are studied. MOFs are hybrid and crystalline materials showing high performances for uranium extractions in weak acid solutions.In order to answer to this objective, the stability of two type of MOFs has been studied at different contact time in acidic solution simulating the ore leachate. Afterwards, zirconium based MOFs functionalized with two different organic functions have been synthesized and characterized with PXRD, BET, TGA, SEM, FT-IR and NMR. The uranium extraction behavior with three functionalized MOFs has been studied in function of the contact time, uranium concentration, sulfate concentration and pH. The uranium extraction values coupled with spectroscopic analysis of uranium loaded materials afford the understanding of uranium extraction mechanisms for both materials.Keywords: MOFs, organic synthesis, solid-liquid separation, uranium
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Murthy, Challa Venkata Ramachandra. "Modelling of the rate of stripping of zinc from di(2-ethylhexyl) phosphoric acid in n-heptane." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/8688.
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Stewart, Neil Stuart. "The technology and control of mining in Roman Britain." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249933.
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Ho, Mark D. "Application and assessment of sequential extraction for trace metal characterization of contaminated soil." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0009/MQ40907.pdf.
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Uheida, Abdusalam. "Selective separation of metal ions by solvent extraction, liquid membranes and magnetic nanoparticles /." Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3871.
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Chen, Fu-Yih Jeffrey. "Characterization of the liquid-liquid interface and its influence on metal extraction processes." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186977.
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8-Mercaptoquinoline (QSH) exhibited substantial interfacial activity in its neutral form. The interfacial activity of QSH may stem from its zwitterionic form QH⁺S⁻. The interfacial activities of Ni-HPMBP system are in the order Ni(PMBP)₂ > PMBP⁻ > HPMBP. The interfacial rate constant of formation reaction is 4 times greater than the bulk value. The bulk and interfacial rate constants for dissociation reaction of Ni(PMBP)₂ are essentially the same. The centrifugal partition chromatography (CPC) inefficiency as measured by the quantity channel equivalent of a theoretical plate (CETP), reflects the slow chemical kinetics of the back extraction reaction, and increases with the half life of the dissociation reaction. This correlation, for the first time, enables the determination of the interfacial areas generated, and hence the average size of the mobile phase droplets, in the CPC experiments. The interfacial activities of dodecylsalicylaldoxime (HDSO) in its neutral and deprotonated forms and its Ni complex at the hexanes-aqueous interface are very nearly the same. The Ni²⁺ is complexed by HDSO and DSO⁻ in the bulk aqueous and hexanes-aqueous interface. The interfacial rate constants for HDSO and DSO⁻ are 3-5 times smaller than the bulk aqueous values. The interfacial rate constant of the dissociation of Ni(DSO)₂ is an order of magnitude larger than the bulk dissociation rate constant. The CPC efficiencies for the Ni-HDSO system indicate specific interfacial areas of 1350 cm⁻¹ being generated in these experiments corresponding to a mobile phase droplet size of 24 μm. This effect leads to much larger CPC efficiencies than that predicted by the dissociation kinetics in the highly stirred mixture. The interfacial excess of 8-hydroxy-7-iodo-5-quinoline sulfonic acid is about 3 times bigger than its nickel complex, in contrast to the OMNTP which interfacial excess is about 4 times smaller than its barium complex. A new ATR-based method, agar-organic phase model, was developed for the determination of the liquid-liquid (L-L) interfacial adsorption of ligands and their metal-ligand complexes which were useful in L-L extraction.
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Okino, Fumito. "Study on the Instability Analysis of the Liquid Metal and Application for the Fusion Energy Conversion System." Kyoto University, 2014. http://hdl.handle.net/2433/192209.
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Kong, Frederick. "Silicon-on-sapphire MOSFET parameter extraction by small-signal measurement /." [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17051.pdf.
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Sotiropoulos, Dimitrios. "Rate controlling mechanisms in the extraction of zinc and copper with a supported liquid membrane." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/8811.
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Sylvester, Paul. "Extraction of cobalt and other metal ions from aqueous solutions using inorganic ion exchangers." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278137.
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Croxtall, Ben. "The application of solid phase extraction in organic synthesis using fluorous derivatised metal catalysts." Thesis, University of Leicester, 2003. http://hdl.handle.net/2381/30076.
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This thesis describes the synthesis, characterisation and coordination chemistry of a variety of fluorinated ß-diketonate ligands (I) and carboxylate ligands (II), the catalytic activity of the resultant metal complexes for oxidation and C-C bond forming reactions, and an evaluation of fluorous methodologies for catalyst/product separation. (Fig. 3706) Chapter 1 introduces the concept and application of fluorous methodologies, including fluorous biphase catalysis and fluorous reverse phase silica gel (FRPSG), as alternative approaches to product/catalyst separation in homogeneous catalysis. Chapter 2 describes the synthesis and characterisation, in some cases by X-ray diffraction, of the fluorinated ß-diketonate ligands and an evaluation of the influence of the perfluoroalkyl groups on the coordination of these ligands to a variety of transition metals including copper, nickel, palladium and zinc. Chapter 3 outlines attempts to sue fluorous nickel ß-diketonate complexes for the oxidation of sulfides. The results indicate that a metal catalyst is not necessary for oxidation in this system although the veracity of catalyst separation using FRPSG was established. This chapter also describes the investigation of a fluorous molybdenum ß-diketonate complex for the oxidation of alkenes, although the extreme moisture senstiviity of the complex negated any attempts at recovery and recycling. The scope of Lewis acid catalysed coupling of ß-diketones with cyanoformates and the ability to reuse and recycle the fluorinated ß-diketonate catalysts is described in chapter 4. Chapter 5 describes attempts to extend this efficient separation procedure to the C-C bond forming reactions of rhodium carboxylate dimers. Although catalysis was observed, catalyst/product separation using FRPSG was unsuccessful. Chapter 6 summarises all the experimental details and spectroscopic data, whilst a CD-rom includes all of the crystallographic data.
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McKim, Artie S. "Synthesis and Alkali Metal Extraction Properties of Novel Cage-Functionalized Crown Coronands and Cryptands." Thesis, University of North Texas, 1999. https://digital.library.unt.edu/ark:/67531/metadc277666/.
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Marshall, Karen L. "Chelate Assisted, Pressurized, Liquid Extraction for the Removal of Adsorbed Metal Contaminants From Soils." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/78001.
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Chelate Assisted, Pressurized, Liquid Extraction (CAPLE) has been developed in our laboratory as an efficient, separation-based, extraction methodology for heavy metals in soils. Unlike current extraction methods used in environmental determination of contaminated soils, CAPLE is able to selectively remove adsorbed metals from the soil matrix without requiring the total destruction of the sample. By not fracturing the soil matrix particles, as with hot acid digestion methods, geologically bound metals are not liberated in the CAPLE process. This unique feature of CAPLE allows us to quantify levels of contaminant metals and correlate them to anthropological activity in the area.
CAPLE requires the use of a modified supercritical fluid extractor for operation with water at sub-critical levels. The extraction of the sorbed metals is facilitated by the use of a chelating agent. Metal determinations are performed by atomic absorption (FAAS or GFAAS) or ICP emission spectrometry.
CAPLE has been subjected to a variety of experimental conditions in order to elucidate the strengths and possible weaknesses of the extraction technique. The uses of the chelating agents (type and concentration) have been optimized. Possible release of metals from the resulting ionic strength of the chelating solutions have been shown not to be a factor. Both pressure and temperature effects have been studied and adjusted for optimal conditions.
The majority of the research lies in the application of CAPLE to a variety of soil conditions. The effect on particle size of the soil and soil coating (humic acid and iron oxides) has been studied. In all soil systems and coatings studied, CAPLE could be optimized to completely remove chemisorbed metals. Tests of CAPLE on Cu-sludge amended soils provided excellent agreement with traditional methods of soil analysis. Not only was good agreement obtained between the recoveries of the methods, but CAPLE was also found to be much faster, more environmentally friendly, and much less prone to sample loss or sample contamination compared to traditional soil extraction methods.
A final portion of this work involves a rigorous statistical analysis of CAPLE to a sequential extraction method. Since a Standard Reference Material (SRM) has not been provided for chemisorbed metals onto soils, a comparative analysis was chosen to validate the technique. Using the Cu-amended soils, CAPLE was found to effectively liberate all chemisorbed metals as compared to the sequential extraction technique. There was no statistical difference in recovery between the two extraction methods.
CAPLE is shown in this work to be a viable extraction method for analyzing contaminant metals in soils. It is a rapid and efficient technique. Unlike traditional digestion methods, it is able to differentiate anthropological metals from geologically occurring metals. Its ease of use, coupled with simplicity of instrumental design and analytical reagents make it an attractive extraction technique for environmental analysis.Ph. D.
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Griffin, Jonathan. "Transition metal oxides and their use as hole extraction materials in organic photovoltaic devices." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5125/.
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One of the limiting factors in the efficiency of organic photovoltaic devices utilising new generations of donor polymers is the ability to obtain Ohmic contacts between the electrodes and the organic layers. This is due to the fact these new donor polymers often have deeper energy levels meaning that at the interfaces between the organic layer and the electrode contact barriers are formed. PEDOT:PSS is the current benchmark material that is used to reduce or remove these contact barriers however even this material has too shallow an energy level and has serious issues with long term stability. One possible class of materials that might overcome these limitations and give increased device performance and lifetimes are metal oxides. However these materials are currently deposited mainly through vacuum deposition and the difficulty of incorporating vacuum based depositions into roll-to-roll fabrication setups limits the commercial use of these materials. Using a combination of spectroscopic techniques and device results this work shows that metal oxides can be used to effectively reduce these contact barriers and achieve high performance using deep energy level donor polymers. It has been shown that Vanadium (V) Oxide can be deposited from solution at room temperature while maintaining high efficiencies. The work continues to look at spray coating, a roll-to-roll compatible deposition technique, and how it can be used to incorporate ultrathin film of solution processed Molybdenum (VI) Oxide for fabricating efficient devices. In addition I have shown that the processing of these materials is only limited by the possible introduction of metallic gap states that can occur due to high temperature processing.
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Manzke, Yori. "Non-local, local, and extraction spin valves based on ferromagnetic metal/GaAs hybrid structures." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17230.
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Im Gebiet der Spin-Elektronik wird der Spin des Elektrons zusätzlich zu seiner Ladung für Bauelementkonzepte ausgenutzt. Hierbei ist die effiziente elektrische Erzeugung einer Spinakkumulation in einem halbleitenden Material von großer Bedeutung. Die Erzeugung der Spinakkumulation kann mithilfe eines ferromagnetischen Metall-Kontaktes erfolgen. Wird eine elektrische Spannung an die Grenzfläche zwischen dem ferromagnetischen Metall und dem Halbleiter so angelegt, dass spinpolarisierte Elektronen vom Metall in den Halbleiter fließen, spricht man von elektrischer Spininjektion. Bei einer Umkehrung der Spannung werden bevorzugt Elektronen der entgegengesetzten Spinorientierung aus dem halbleitenden Material entfernt. Dieser Prozess wird als Spinextraktion bezeichnet. In dieser Arbeit wird die elektrische Erzeugung einer Spinakkumulation in lateral strukturierten, epitaktischen Hybridstrukturen bestehend aus ferromagnetischen Metallkontakten auf n-dotiertem GaAs untersucht. Allgemein ist neben der Spinpolarisation im Ferromagneten auch die spinunabhängige elektrische Charakteristik eines Kontaktes von zentraler Bedeutung für die effiziente Spinerzeugung. Hier wird gezeigt, dass die gewöhnlichen Strom-Spannungs-Kennlinien die Spininjektionseigenschaften dominieren können. Außerdem wird ein neuartiges Bauelementkonzept vorgestellt und experimentell untersucht. Hierbei handelt es sich um ein lokales Spin-Ventil, welches Spinextraktion statt Spininjektion als Spinerzeugungsprozess verwendet. Im Gegensatz zum gewöhnlichen lokalen Spin-Ventil kann ein solches Extraktions-Spin-Ventil als Baustein eines erweiterten Bauelements angesehen werden, welches auf mehreren, aufeinanderfolgenden Extraktionsprozessen beruht. Die Eigenschaften des Extraktions-Spin-Ventils werden diskutiert und es wird gezeigt, wie seine Funktionalität beispielsweise für das Auslesen der Daten in magnetischen Speichern angewendet werden kann.The efficient electrical generation of a spin accumulation inside a semiconductor (SC) utilizing the interface with a ferromagnetic metal (FM) is essential for the realization of many spintronic device concepts, in which the spin of the electron is exploited in addition to its charge for computational and memory purposes. At FM/n-type SC hybrid contacts, the application of a reverse bias leads to the injection of spin-polarized electrons into the SC. Alternatively, an applied forward bias can be used to generate a spin accumulation of opposite sign due to the extraction of electrons with a particular spin orientation. In this work, the electrical generation and detection of a spin accumulation is studied using epitaxial and laterally structured ferromagnetic metal/n-type GaAs hybrid systems in various measurement geometries. To achieve a high spin generation efficiency, the spinindependent electrical properties of the contact have to be considered in addition to the choice of the injector material with respect to its degree of spin polarization. Here, it is shown that the current-voltage characteristics can even constitute the dominating design parameter with respect to the spin injection properties. In addition, a novel device concept is presented and studied experimentally. This approach essentially relies on spin extraction as the spin generation process in a local spin valve geometry. In contrast to local spin valves based on spin injection, the presented extraction spin valve can be regarded as a building block of an extended device comprising multiple extraction events along the lateral spin transport channel. It is shown how such multiple extraction spin valves allow for an intriguing functionality, which can be used, for example, for the read-out of data in magnetic memory applications.
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Moleko, Pulleng. "The coordination and extractive chemistry of the later 3d transition metal ions with N, N'-donor imidazole-based ligands." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/8382.
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The application of bidentate N,N'-donor ligands, such as 2,2'-biimidazole (BIIMH2) and 2,2'-pyridylimidazole (PIMH) and (1H-benzimidazol-2yl)-N-methylmethanamine (BIMAH), in the solvent extraction of base metal ions from an acidic sulfate/sulfonate medium was investigated. PIMH and BIMAH showed selectivity for Ni(II) with the only interfering ion being Cu(II) in the pH range 1.2-1.8 but BIIMH2 lacked selectivity. The extraction patterns observed were influenced by stereochemical aspects, and this agreed well with the envisaged design of nickel(II)-specific extractants through stereochemical “tailor-making” which is proposed in this study. The extraction patterns were explained from a coordination chemistry point of view using spectroscopic analysis and single crystal X-ray analysis to diagnose the geometry of the complexes formed from the interaction of the base metal ions with the ligands. The formation of the trigonal bipyrimidal [Cu(PIM)2(H2O)](SO4) complex, with a water molecule coordinated, while nickel(II) forms a square planar bisPIMH was put forward as the reason for extraction pattern observed with this ligand. Cobalt(II) also forms a bisPIMH complex but has two water molecules coordinated in the formation of a distorted octahedral complex, and this results in less extractable species. A similar observation as for PIMH was noticed in BIMAH complexation reactions. The BIIMH2 complexes were found to be distorted octahedral, through the bis-coordination of BIIMH2 and two sulfonate ions, resulting in lack of pH-metric separation of the later 3d metal ions. The stability constants data was in agreement with what was observed in the solvent extraction and coordination chemistry studies for the three ligand systems.
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Norman, Sofia. "Extraction of Heavy Metals from Fly Ash using Electrochemical Methods." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-64361.
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In today’s society large quantities of waste is produced. In Sweden this is reused as fuel for incineration processes where electricity and district heating are generated. However, during this process two hazardous by-products are formed, namely slag and fly ash. These contain relatively high concentrations of heavy metals, which make them harmful to the environment if not taken care of, but also make them valuable resources if the metals could be extracted and reutilized. One possible way to extract metals from the waste products is to use electrochemical methods. In order to implement these techniques on an industrial scale, there are several parameters that have to be considered. One important parameter is the choice of material of the electrode, which needs to have a large surface area, a high chemical inertness and electrical conductivity, and preferably also a reasonable price. A material that fulfills these qualifications is reticulated vitreous carbon (RVC), and therefore the extraction efficiency of this porous material has been evaluated in this thesis. Studies were also performed to evaluate how several other parameters affected the extraction efficiency, since this does not rely on the choice of electrode material alone. The results showed that RVC is suitable as electrode material for efficient metal extraction from fly ash. The most efficient electrode combination was RVC with a pore size of 10 pores per linear inch as working electrode, stainless steel as counter electrode, and Ag/AgCl as reference electrode. Both the amperometric and galvanostatic experiments extracted equal amounts of copper within the same time interval, which means that the choice of using either controlled potential or controlled current for an efficient extraction of copper was not of significant importance. The mass transfer rate for copper was 0.12 mg·h-1·cm-2 in both methods, where an electrolyte of 200 ml was used with an initial copper concentration of 50 mg/l. Regarding stirring of the electrolyte, circulation in the solution is an advantage, but not critical for an efficient reduction. The extraction efficiency for one particular metal did not seem to be affected by the presence of other metals in the electrolyte. It was also shown that a selective extraction of metals was possible by applying different potentials. Lastly, an experiment with fly ash was performed, with the optimal conditions and electrode combination based on the previous experiments. This yielded a mass transfer rate of 0.59 mg·h-1·cm-2 for zinc using an electrolyte of 200 ml, which initially contained 595 mg/l of zinc.