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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.
2
Jonck, Heine. "Development of platinum metal specific separating agents." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/712.
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In this dissertation, the aim was to develop a platinum specific resin to be utilized for the early removal of platinum from the industrial feed solution. Efforts were therefore directed towards the syntheses of silica based resins, with active centra, designed for platinum. The large chlorometallate ions present in the feed stream, were characterized in terms of physical parameters relevant to phase distribution, namely distortability (RD), charge density, softness (σ) etc. Matching cations for each of the types were investigated. In order to attempt the design of platinum specific resins, different structural amines were used to aminate the silicone precursor and to subsequently fix these onto the silica framework. Two different solvents namely alcohol and dmf were used in this process, resulting in two sets of resins, with different properties. The design was based on previous experience with these ions, with reference to their behaviour towards different types of cations. The platinum species, PtCl6 2- and PtCl4 2-, as well as the most important contaminants in the feed stream, were typified, bearing in mind size, charge, charge density and distortability. Different types of cationic centra, having differences in charge density, stereochemical crowding and extent of hydrophobicity, were synthesized and tested-both as solvent extractants (where possible) and silica based resins. The results indicated that, partly screened secondary ammonium cationic resin species, which could be regarded as “intermediate”, proved to be satisfactory both in their high percentage extraction for PtCl4 2- and rejection of contaminants like chlororhodates, chloroiridates(III) and FeCl4 -. It was however necessary, to work at a redox potential, where iridium(IV) in the form of IrCl6 2-, was absent. Various 2-aminoalkane resins were prepared, with variation in the length of alkane group and synthesised by the two different solvents. The latter resulted in two sets of resins with not only differing compactness, but also having significantly different properties with reference to platinum specificity, HCl effect and stripping potential. The 2-aminobutane and 2-aminoheptane resins in particular, proved to be very satisfactory platinum specific resins, both with respect to selectivity, platinum capacity and stripping potential. The various physical parameters could be applied to identify the chemical behaviour of anions and assist in the development of anion specificity for the relevant species.
3
Wicks, Joseph Leslie Michael. "Routes to mixed metal compounds of the platinum group : metal σ-acetylide complexes and platinum clusters". Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620495.
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4
Pike, Sarah Jane. "Dynamic platinum(II)- based metallosupramolecular architectures." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7942.
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Over the past two decades, transitions metals have been extensively employed towards the construction (using coordination driven assembly) and operation (using reversible metal-ligand switching motifs) of supramolecular architectures. This Thesis details the investigation of an array of dynamic platinum(II)-based metallosupramolecular architectures and includes a series of model studies on switchable platinum(II) coordination modes. Chapter Two describes the synthesis and study of a series of prototype noninterlocked molecular machines. The inherent dynamics of intramolecular metalligand substitution reactions (metallotrophic shifts) are exploited to drive a d8 platinum(II-)-phenanthroline component along different ligating architectures to achieve translational (and in one case rotary) motion of the sub-molecular components. Variable temperature NMR studies of these complexes have established the kinetic parameters for the observed shuttling processes. In Chapter Three, the switchable behaviour of a metal-ligand coordination motif is reported in which a proton input is employed to modify the overall thermodynamic bias and light is orthogonally utilized to selectively lower the energetic barrier for the binding event to re-equilibration. A discussion of the light-promoted ligand exchange reaction is presented, supported by a combination of TD-DFT calculations and kinetic studies. Chapter Four describes the exploitation of this discovered pH-switchable metalligand motif for the stimuli-responsive reversible assembly of two dimensional and three dimensional metallosupramolecular architectures. Whilst Chapter Five details how this reversible motif can be exploited to induce controlled exchange between “3+1” and “2+2” square planar platinum donor sets in response to the application of acid-base stimuli.
5
Ringo, Jessica M. "Square planar d8 metal complexes with nitrogen-based ligands: structural analysis, metal-metal cooperativity, and applications." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1562842509907911.
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Sherman, D. J. "Studies on some platinum metal compounds." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382671.
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Crofts, Rhona D. "Platinum metal complexes of macrocyclic ligands." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/13493.
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Sekota, Mantoa Makoena C. "Catalytic reactions of platinum group metal phthalocyanines." Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1006151.
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The voltammetric behaviour of I-cysteine and other organic compounds such as hydrazine, hydroxylamine and methionine has been studied on GCE modified with phthalocyanine complexes of osmium, rhodium and ruthenium. For cysteine oxidation, the catalytic activity of the electrode was dependent the nature of the axial ligand. When cyanide and dimethylsulphoxide (DMSO) were used as axial ligands, giving (DMSO)(Cl)Rh(III)Pc, [(CN)₂Rh(III)Pc], (DMSO)₂0S(II)Pc and [(DMSO)₂Ru(II)Pc].2DMSO complexes, the peak current increased with repetitive scanning, indicating the increase in catalytic activity of the electrode after each scan. This behaviour was not observed when pyridine was used as axial ligand. The improvement of the catalytic activity of the GCE after the first scan has been attributed to the formation of the dimeric π-cation radical species at the electrode surface. Water soluble phthalocyanine complex ([(CN)₂Os(II)Pc]²⁻) and the tetramethyltetra-pyridinoporphyrazine complexes of Pd(II) and Pt(II), ([Pd(II)2,3Tmtppa(-2)]⁴⁺, [Pd(II)3,4Tmtppa(-2)]⁴⁺, [Pt(II)2,3Tmtppa(-2)]⁴⁺ and [Pt(II)3,4Tmtppa(-2)⁴⁺) have been prepared. [(CN)₂Os(II)Pc]²⁻ is soluble in water at pH greater 4 without the formation of dimers. The [M(II)Tmtppa(-2)]⁴⁺ (M = Pd or Pt) show high solubility in water and are stable only in acidic pHs. The cyclic voltammetry of the MPc and [M(II)Tmtppa(-2)]⁴⁺ complexes prepared, is also reported. The interactions of amino acids I-histidine and I-cysteine with the [M(II)Tmtppa(-2)]⁴⁺ complexes of Pd(II) and Pt(ll) were studied. All the [M(Il)Tmtppa(-2)]⁴⁺ are readily reduced to the monoanion species [M(Il)Tmtppa(-3)]³⁻ in the presence of histidine and cysteine. The rate constants for the interaction of [M(Il)Tmtppa(-2)]⁴⁺ complexes ofPt(II) and Pd(II), with histidine and cysteine range from approximately 2 x 10⁻³ to 0.26 dm³ mol⁻¹ s⁻¹. Kinetics of the interaction of [Co(Il)TSPc]⁴⁻ with amino acids, histidine and cysteine in pH 7.2 buffer were studied. The rate constants were found to be first order in both [Co(II)TSPc]⁴⁻ and the amino acid. The formation of [Co(III)TSPc]³⁻ in the presence of histidine occurred with the rate constant of 0.16 dm³ mol⁻¹ s⁻¹, whereas the formation of the [Co(I)TSPc]⁵⁻ species in the presence of cysteine gave the rate constant of 2.2 dm³ mo⁻¹ s¹. The relative quantum yield (QΔ) for singlet oxygen production by [(CN)₂Os(Il)Pc]²⁻, and [(CN)⁴Ru(II)Pc]²⁻ in DMF using diphenylisobenzofuran (DPBF) and a chemical quencher were determined. The quantum yield values were obtained as 0.39 ± 0.05 , and 0.76 ± 0.02 for [(CN₂Os(II)Pc]²⁻ and [(CN)₂Ru(II)Pc]²⁻ respectively. The differences in quantum yield values have been explained in terms of donor abilities of both the central metal and the axial ligands.
9
Acharya, Suvra. "Platinum metal`s complexes: synthesis and characterization." Thesis, University of North Bengal, 2011. http://hdl.handle.net/123456789/1384.
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10
Smale, Simon. "Study of the hydrogen evolution reaction on platinum and platinum group metal surfaces." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54760/.
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The hydrogen evolution reaction (HER) has been examined on a variety of Pt and Pt-group metal surfaces to investigate the rate of the reaction. Pt stepped single crystal surfaces were investigated in relation to the HER using cyclic voltammetry, linear sweep voltammetry and multi-frequency AC voltammetry. It was found that the hydrogen evolution reaction activity did not show a dependence on the structure of single crystal platinum electrode surfaces. Thick films of Au, Rh and Pd were deposited onto Pt {111} and successfully annealed to give pseudomorphic surfaces of the bulk metal. The aim of such measurements was to investigate whether strains within the crystal lattice of these films would result in enhanced HER activity. None of the surfaces investigated showed significant HER enhancement. Rather, results similar to those observed using the bulk metals were obtained. Rough Ir and Pt deposits on Pt{111} were also investigated. Enhanced HER activity was observed on these surfaces. This enhancement was interpreted in terms of the structural arrangement of the Ir and Pt deposits. For Pd films on Pt {111} (0 < fVPd < 2 monolayers) it was observed that Pt dominated the HER kinetics for Pd coverages up to one monolayer and was still influential on the HER at two monolayers of Pd. Similarly Pd-Pt surface alloys also showed that Pd had little or no influence on the HER kinetics even with 75 % Pd in the surface layer. Possible mechanisms for this behaviour have been proposed, in particular, the role of subsurface hydrogen in HER on Pt is discussed.
11
Look, Jennifer L. "Mechanistic studies of reactions between molecular oxygen and platinum alkyl and platinum hydrocarbyl hydride complexes /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/11599.
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12
Matthews, Richard P. "Ion Pairing in Aqueous Metal Sulfates and Platinum Group Metal Ammonium Solutions." Doctoral thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/6330.
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The structure and dynamics of ions and ion pairs in solution play an integral part in several biological and chemical processes. Historically the calculation of ion pair association constants from computer simulations has been complicated due to the difficulty in validating metal ion force fields for solution simulations. In this thesis a force field for divalent metal ions in metal sulfate solutions (i.e. Mg2+SO4 2-, Ca2+SO4 2-, Mn2+SO4 2-, Fe2+SO4 2-, Co2+SO4 2-, Ni2+SO4 2-, Cu2+SO4 2- and Zn2+SO4 2-) important in physical and biophysical experiments is produced. Potential of mean force calculations are used to provide ion pair free energy profiles and free energy perturbation calculations are used to calibrate the potential of mean force (PMF) from which association constants for ion pairs can be produced for these metal sulfate solutions. The calibrated free energy profiles result in calculated association constants that are in excellent agreement with available experimental data where available. Consequently the force field has been shown to be accurate for simulations of biophysical and physical systems. Furthermore the method, proposed in this thesis, for calibrating PMFs and calculating detailed association constants from those curves can most likely be used for complex systems that have previously been computationally inaccessible. Next a detailed account of solvation structures and the nature of ion pair formation mechanisms for important metal sulfates in aqueous media are presented. Radial and spatial distribution functions calculated for several ion pair species reveal that the transition from free ions to contact ion pairs involves the loss of between one to two water molecules from the cation depending on the cation size. This is correlated with the experimental hydration numbers calculated for metal sulfate electrolyte solutions at several concentrations using density and ultrasonic velocity measurements. These experiments reveal a decrease in hydration number with an increase in concentration, which can be attributed to the formation of ion pairs. A more complex metal system is the industrially important platinum group metal (PGM) chloro-anion one. Their industrial importance relates to the search for a Green Chemistry Process for the separation of PGM chloro complexes that have been extracted from the mined ore into an acidic aqueous media. This requires a PGM separation process in water. Here an understanding of the hydration structure about the iii PGM chloro-anion complexes and the role that ammonium counter-ions play in disrupting that solvent structure when ammonium PGM salts are formed, is critical in the process design. To this end a solution force field, inclusive of the majority of PGM chloro-anion complexes (i.e. (Y)2[PtCl4]2-, (Y)2[PdCl4]2-, (Y)2[PtCl6]2-, (Y)2[PdCl6]2-, (Y)2[IrCl6]2-, (Y)2[OsCl6]2-, (Y)2[RuCl6]2-, (Y)3[IrCl6]3-, (Y)3[RhCl6]3- and (Y)3[RuCl6]3- , where Y = NH4 +) arising in acidic aqueous media, parameterised from experimental and quantum mechanically derived properties, was developed. Nanosecond atomistic molecular dynamics simulations were then performed for the PGM chloro-anion complexes. Analysis of the solvation structure using radial and spatial distribution functions revealed two distinct solvent structures corresponding to the square planar and octahedral species. The formation of ion pairs disrupts the solvent structure where the hydration shells about the bivalent hexachlorometallates are more affected compared with the trivalent hexachlorometallates and these first shell waters in turn are more affected than those in the bivalent tetrachlorometallates. Finally to inform the design of a separation process transport properties such as diffusion coefficients, ion hydration numbers and water residence times for the PGM chloro-anion complexes were calculated. It is observed that the diffusion rates of PGM chloro-anion complexes are strongly correlated to their ion hydration numbers as calculated by Voronoi tessellation of the simulation cell, such that a larger hydration shell volume results in a slower PGM chloro-anion diffusion rate.
13
Bell, Michael Niall. "Organometallic platinum group metal complexes incorporating macrocyclic ligands." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/13895.
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Spankie, S. A. A. "Ylide complexes of palladium and platinum." Thesis, Heriot-Watt University, 1987. http://hdl.handle.net/10399/1018.
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15
Gash, Rosslyn Clare. "Metal haloalkyl in complexes in catalysis." Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/14706.
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In this thesis, the preparation of a number of halomethyl complexes of rhodium, platinum, and palladium is described. Complexes of the type trans-[Rh(CH2X)X(P4)]+ (X = Cl, Br, I, P = PMe3, dmpe) were found to be unstable, decomposing in situ to give a mixtures of dihalo, trihalo, and phosphine ylide species. Platinum and palladium species of the type trans-M(CH2X)X(PEt3)2 (X = Cl, I, M = Pt, Pd), which were formed by the reaction between M(PEt3)3 CH2XY were also unstable. In the case of platinum, phosphine ylide species were isolated from reaction mixtures, whilst the palladium halomethyl species decomposed over a number of days to give dihalide complexes. However, palladium iodomethyl species prepared via reactions involving 2 moles of phosphine per mole of metal were found to be stable. Neutral rhodium halomethyl complexes were also found to be far more stable than their cationic counterparts. The synthesis and characterisation of trans-RhCl(CO)(CH2l)I(P)2/ (P = PMe3, PEt3, or Et2PPh), prepared by oxidative addition of CH2I2 to RhCl(CO)(P)2 is described. When less basic phosphines (such as PPh3) or the sterically hindered phosphine PCy3 were used, no evidence of any reaction between the rhodium complex and the CH2I2 was observed. The molecular structure of trans-RhCl(CO)(CH2l)I(PEt3)2 has been studied by X-ray diffraction analysis. This complex proved to be inert to substitution at the iodomethyl carbon atom by neutral nucleophiles such as H2O, CH3OH, and PEts, but prone to substitution by Cl-. The lability of iodomethyl (and chloromethyl) ligands towards CO insertion has also been studied. There is evidence to suggest that an iodoacyl platinum complex may form in solution after the complex cis-Pt(CH2l)I(PPh3)2 had been left under 1 atm CO for 24 hours. However, in the case of trans-Pd(CH2l)I(PCy3)2 this same reaction took 7 days under 70 atm pressure of CO. All of the rhodium iodomethyl complexes prepared were also inert to CO insertion at ambient temperature and 1 atm CO, but excellent evidence for CO insertion having taken place in irflns-RhCl(CO)(CH2l)I(PEt3)2 was observed at 70°C and 35 atm of CO. Evidence for CO insertion into a rhodium-chloromethyl bond was also observed under the more forcing conditions of 100°C and 70 atm CO. This insertion reaction may prove to be extremely useful in catalytic systems. A report of some preliminary catalytic studies involving the production of diethylmalonate from CH2I2 and C2-products from the hydroformylation of (CH2O)[sub]n under very mild conditions is also presented. It is thought that these catalytic reactions proceed via carbonyl insertion into a rhodium-iodomethyl bond.
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Kruyswijk, Lizelle. "Electrorefining of base metal refinery residue copper alloy for platinum group metal recovery." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/6080.
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Secondary leach concentrate (SLC) is an important bleed stream for minor elements from Anglo Platinum’s Base Metal Refinery (BMR) which produces copper nickel and cobalt sulphate. It contains mainly sulphur, iron jarosites, unleached base metals and platinum group metals (PGMs), which makes the treatment of SLC necessary. The SLC is currently toll-refined at Umicore’s Hoboken smelter and refinery to recover revenue from entrapped valuable metals. This method of treatment results in excessively high costs due to high transport and toll refining expenses as well as penalties. Thus, an in-house method of treatment by Anglo Platinum itself would prove beneficial in that it would eliminate these excessive costs and also provide a method of treatment in the event of residues exporting becoming banned or strongly penalised in future. Therefore, a method for treating SLC in-house is investigated. The first stage of the proposed treatment method involves a pyrometallurgical process where the removal of amphoterics by oxidative fuming, followed by reduction to recover base metals from the slag takes place. The PGMs are reported mainly to the metal alloy phase along with the base metals during this process. The project discussed in this report deals with the treatment of this furnace alloy which is referred to as Cu alloy. The Cu alloy is used to produce anodes to be applied to an electrorefining application for the recovery of Cu as a Cu cathode and PGMs in the form of anode slimes. Spent electrolyte from the BMR copper electrowinning section adjusted to specific pH and Cu concentration is used as electrolyte to which dissolvable metals (such as Ni and Fe) are recovered.
17
Ghosh, Biswa Nath [Verfasser]. "Multivalent binding in platinum metal complexes / Biswa Nath Ghosh." Gießen : Universitätsbibliothek, 2011. http://d-nb.info/1064990460/34.
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Carmichael, J. "Hydrogenation of deactivated carbonyls over platinum group metal catalysts." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426964.
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Wells, Peter Philip. "Controlled surface modification of supported platinum group metal catalysts." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438652.
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Stanger, Gillian. "Preparation and characterisation of the platinum group metal fluorides." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/33924.
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An extensive reveiw of the platinum group metal fluorides has been carried out and in the light of this, new preparative routes have been developed and characterisation has been significantly improved. The preparation of the platinum group metal fluorides in both static and dynamic systems is discussed in chapter two. The fluorinations of ruthenium, rhodium and platinum sponges in dynamic systems proved to be of greatest interest. In these studies large amounts of ruthenium hexafluoride and platinum hexafluoride were produced and traces of rhodium hexafluoride were noted, where as previously more forcing conditions had been employed in the preparation of these compounds. It is believed that rigorous drying of the flow line and hydrogenation of the metal in situ are responsible for the success of this new preparative route. When ruthenium is fluorinated in the dynamic system ruthenium hexafluoride and tetrameric ruthenium pentafluoride are produced in large quantities, and smaller amounts of a red glassy material is also formed. There have been no previous reports of any red material forming during this reaction. It is now believed that this material is a trimeric form of ruthenium pentafluoride. The charaterisation of these fluorides was carried out using a large variety of techniques, the most useful being mass spectrometry and matrix isolated infrared spectroscopy. Mass spectrometry proved invaluble in the characterisation of the trimeric ruthenium pentafluoride, while matrix isolation enabled good quality infrared spectra of the reactive hexafluorides to be recorded. These techniques were also utilised to give the first insight into the behaviour of the tetrameric pentafluorides in the gas phase. Iridium pentafluoride has been shown to be monomeric at elevated temperatures, under similar conditions ruthenium and osmium pentafluorides decompose to the metal and fluorine. Platinum pentafluoride is known to be unstable at room temperature and thought to decompose to the hexafluoride and tetrafluoride. Using matrix isolation, direct evidence of this has been obtained.
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Johnson, T. "Platinum group metal modifications of TiO₂ for environmental remediation." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3006082/.
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Ghosh, Biswanath [Verfasser]. "Multivalent binding in platinum metal complexes / Biswa Nath Ghosh." Gießen : Universitätsbibliothek, 2011. http://nbn-resolving.de/urn:nbn:de:hebis:26-opus-84600.
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Forder, Robin James. "Transition metal complexes of phosphine and mixed phosphathia ligands." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243129.
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Newell, Helen E. "Alkane adsorption on metal surfaces." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243748.
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Cartwright, P. S. "Synthetic and spectroscopic studies of transition metal complexes." Thesis, Bucks New University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380302.
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Luedtke, Avery T. "Synthesis, structure, and reactivity of five-coordinate platinum(IV) complexes /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/11565.
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Gregory, Adrian John. "The understanding and development of novel platinum electroplating baths." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261556.
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Bojczuk, M. "Carbonyl exhange mechanisms in transition metal compounds." Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372765.
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Vos, Amelda. "Evaluation of exposure to airborne soluble platinum in a precious metal refinery during non–routine operations / Amelda Vos." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7601.
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Background: Platinum refinery workers are exposed to various elements during the refining
process, with soluble platinum salts posing a potential health risk. Platinum salts are extremely
potent sensitisers that can result in the clinical syndrome of platinum salt sensitivity (PSS) that
leads to skin and respiratory hypersensitivity in refinery workers. Several published research
articles document refinery workers’ exposure levels to soluble platinum salts during production.
However, the exposure levels to soluble platinum salts during non–routine stock take activities
are unknown although cases of sensitisation have been diagnosed following these nonoperational
periods. Stock take for the platinum refinery under study commenced on 18
January 2010 and ended 22 February 2010. Increased emphasis was placed on flushing plant
equipment rather than dismantling it. The aim was to dismantle 10% of what previously was
dismantled to reduce the risk of exposing employees to soluble platinum salts, to reduce the
chance of damaging plant equipment and for cost and time saving purposes.
Aim: The objectives of this study are to:
(i) quantify work area and personal exposure levels;
(ii) identify work areas and work practices with exposure levels exceeding the occupational
exposure limit (OEL) (>2 ug/m3);
(iii) determine whether exposure levels differ significantly between:
a) personal sampling groups (engineering versus production),
b) area sampling groups (open versus closed–face sampling),
c) work areas,
d) total area and total personal sampling groups and to
(iv) evaluate the efficiency of the current control measures utilised.
Design and Method: A total of 58 platinum samples were collected, consisting of 38 personal
and 20 area samples. Personal sampling consisted of Institute of Occupational Medicine (IOM)
samplers housing reusable 25 mm filter cassettes with mixed cellulose ester (MCE) membrane
filters for the collection of inhalable airborne particles. Because both the cassette and the filter
were pre and post–weighed as a single unit, all particles collected (even those against the walls
of the cassette) were included in the analysis. Sampling was conducted in accordance with the
stock take schedule and scope and included a roster for the systematic dismantling and
cleaning of the refinery, following the process flow.
A target population of maximum five fitters and five operators per area were identified,
responsible for dismantling and cleaning plant equipment respectively. The sampling strategy
was based on the identification and sampling of employees presumed to have the highest
exposure risk. The Occupational Exposure Sampling Strategy Manual (OESSM) refers to this
as the “maximum risk employees” (Liedel et al., 1977). The selection of the maximum risk
employees was done with reasonable certainty since the employees sampled were working
closest to the source of exposure. Sampling was conducted for the total duration of the task
consisting of single sample measurements.
Area sampling was conducted by means of BUCKAir high volume samplers fitted with preweighed
47 mm MCE filter cassettes to show the spread of the contaminant in the work area.
The high volume samplers were calibrated to operate at a sampling volume of 20 L/min. The
sampling heads were positioned 1.5 m from the ground surface and as near as possible to the
work location or failing this as near as is possible to major sources of exposure. Samples were
collected and analysed according to the method for the determination of hazardous substances
46/2 (MDHS 46/2). This is an advanced sampling and analysis standard which enables
detection of low levels of soluble platinum (0.01 ug/m3).
Results: Thirty eight personal platinum samples were collected, consisting of a sampled
engineering (n=15) and production (n=23) subgroup. Out of the thirty eight personal samples
taken in total, 21% of the samples’ concentrations exceeded the OEL of 2 ug/m3 and ranged
between 0.004–20.479 ug/m3. Twenty area platinum samples were collected, consisting of open
(n=10) and closed face (n=10) sampling. Out of the twenty area samples taken in total, 10% of
the samples’ concentrations exceeded the OEL of 2 ug/m3 and ranged between 0.0004–5.752
ug/m3. The mean personal exposure levels for the production subgroup (2.739 ug/m3) were
significantly higher compared to the engineering subgroup’s mean personal exposure levels
(0.393 ug/m3). This significant difference (p=0.033) was expected since the production
subgroup was more exposed and involved in the digging out of residues and the cleaning of
plant equipment compared to the engineering subgroup with limited exposure and involved in
the opening of plant equipment. Although the mean exposure levels for open face sampling
(0.725 ug/m3) were higher compared to the mean exposure levels for closed face sampling
(0.441 ug/m3) no significant difference (p=0.579) were noted. The mean area exposure levels
(0.583 ug/m3) were significantly lower (p=0.004) compared to the mean personal exposure
levels (1.813 ug/m3) for similar areas and tasks performed and, therefore, not an effective
indicator of personal exposure levels.
Higher personal exposure levels were expected since the workers were closer to the source of
exposure and since the platinum salts could have diluted in the workplace’s air resulting in lower
area exposure levels.
Conclusion: The research study addressed the problem statement, met the objectives set out
in Chapter 1, hypotheses were accepted and rejected and future studies were recommended.
It was hypothesised that:
a) refinery workers are exposed to airborne soluble platinum during non–operational periods;
b) exposure levels do not differ significantly between the personal sampling groups
(engineering vs production);
c) exposure levels do not differ significantly between the area sampling groups (open versus
closed–face sampling);
d) exposure levels do not differ significantly between work areas;
e) exposure levels differ significantly between total personal and total area sampling groups.
The results confirmed that refinery workers are exposed to airborne soluble platinum during
non–operational periods and hypothesis a was accepted. The personal exposure levels of the
engineering versus production sampling groups differed statistically (p=0.033) and hypothesis b
was rejected. The exposure levels of the open and closed face sampling groups did not differ
significantly (p=0.579) and hypothesis c was accepted. In addition no statistical difference
(p>0.05) was indicated between the work areas and hypothesis d was accepted. Total personal
versus total area exposure levels (p=0.004) differed statistically and hypothesis e was accepted.<br>Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.
30
Li, Yuan. "Synthesis and mechanical characterization of transversely isotropic nanoporous platinum." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42927.
Full textAbstract:
Nanoporous (NP) metal foams combine desirable characteristics of metals with unique nanoarchitectural features to yield weight normalized properties far superior than either dense metals or bulk metal foams. Due to their high surface to volume ratios these structures show great promise as components of fuel cells, as sensors and have been suggested for use in biological applications, for example as antimicrobial scaffolds or as platforms on which to explore biological material behavior. While most NP metal foams are isotropic, structures with anisotropic features spanning different length scales can further extend applications. This work examines the parameters controlling the synthesis of transversely isotropic NP Platinum foam by dealloying an amorphous Pt-Si alloy. The structure that is examined in this work is hierarchical with Voronoi polyhedra that form on the free surface and under each polyhedral hyper-structure, nanocrystalline NP Pt foam forms with radial struts of length ~60 nm and grain size of 5 nm. The size of the polyhedra can be tailored by changing the dealloying potential. In turn, the mechanical properties of these structures as assessed by nanoindentation can range from 1 to 3GPa depending on the geometric arrangement of the struts. Finally, the initiation location of these structures and the relationship between electrochemical parameters and dealloying front evolution is examined.
31
Petroski, Janet Marie. "Platinum metal nanoparticles : investigation of shape, surface, catalysis and assembly." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/30961.
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Martinez, Josep Vicent Colomer i. "Towards separation of platinum group metal anions from feed solutions." Thesis, University of Southampton, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496074.
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Coll, Richard Kevin. "The structural and reaction chemistries of some platinum metal complexes." Thesis, University of Canterbury. Chemistry, 1988. http://hdl.handle.net/10092/8553.
Full textAbstract:
The work described in this thesis is concerned principally with the preparation, photochemistry, and structural chemistry of some platinum metal complexes. The work is in two parts. The first part is a study of the photochemistry of complexes of the stoichiometric type M(NO)XnL₂ n = 2 or 3 for M = Ru, Rh, Os, Ir; X = Cl, Br, I; and L = R₂s, R₂se, Ph₃P, Ph₃As, and Ph₃ Sb, and the second part is on the preparative and structural chemistries of halogeno- complexes of iridium, ruthenium and rhodium.
The main photochemical reaction observed was oxidation of the ligand (R₂S and R₂Se to R₂SO and R₂Seo, and R₃E to R₃E to R₃EO for E = P, As, Sb), and in many instances the oxidised ligand subsequently coordinated to the complex. The oxidation is achieved with nitrogen oxides (NO, NO₂) for the organosulphides, organoselenides, triphenylphosphine and triphenylarsine, whereas for the triphenylstibine, O₂ appears to be the oxidisng agent. The photochemical reactions of the nitrosyl complexes were investigated using ¹H n.m.r., infrared, UV-visible and mass spectrometric methods.
The X-ray single crystal structures were determined on some starting materials and on some crystalline materials isolated during preparations of the complexes investigated in this work. The structures determined were; RhCl₃(Et₂s)₂(Et₂SO), space group P1, a = 9372(4) Å, b = 9.608(5) Å, c = 12.449(6) Å, α = 79.52(4)°, β = 86.88(3), Υ = 70.66(3)°; Os(NO)Br₃(Et₂S)(Et₂SO) space group P2₁/c, a = 13.398(3) Å, b= 8.501(2) Å, c = 16.199(3) Å, β = 105.69(1)°; Ru(NO)Br₃(Et₂PPh)₂ space group P2₁/c, a = 13.505(2) Å, b = 7.389(0) Å, c = 24.492(3) Å, β = 91.22(1), and Os(NO)Cl₂(Et₂PPh)₂(CH₃OCH₂CH₂O) space group P2₁/c; a= 10.869(1) Å, b = 11.381(1) Å, c= 22.673(2) Å β = 102.17(1)°.
During the preparative study of some trihalogenostannato complexes of the type A₃[MCln(SnX₃)6-n] M = Rh, Ir; n = 1-3, a number of halogeno- complexes were produced. The X-ray single crystal structures of K₃[IrCl₆] space group P2₁/c; a₁= 12.500(7) Å, b=7.424(6) Å, c = 11.831(10) Å, β= 108.48(6)°, (H₃O)₂[IrBr₆] space group Fm3m; a = 10.2738(28) Å, (NH₄)₂[IrBr₆] space group Fm3m, a = 10.440(2) Å, A₃ [Ircl₅(SnCl₃)] for A = K space group Pmn2₁, a=9.5873(13) Å, b = 9.5170(15) Å, c = 7.8480(9)Å, and A= NH₄ space group Pmn2₁, a= 9.593(3) Å, b = 9.495(2) Å, c = 7.832(2) Å, were determined.
A review of the preparative and X-ray structural studies of the platinum metal halogeno- complexes Ru, Os, Rh, Ir, has been prepared, covering the period from 1967 to 1987.
34
Lenthall, Joseph T. "Anion and platinum group metal binding of bis(thioureido) ligands." Thesis, Durham University, 2007. http://etheses.dur.ac.uk/2854/.
Full textAbstract:
A series of bis(thioureido) ligands have been synthesised, which show anion binding in acetone-d(_6). Their structures have been determined by X-ray crystallography and some exhibit hydrogen bonding interactions with the π-electrons of the the thiocarbonyl bond. This hydrogen bonding interaction has been investigated for the general thiocarbonyl and carbonyl bond using the CSD, and a marked difference in the interaction of hydrogen bond donors with the π-electrons of carbonyl and thiocarbonyl bonds has been shown. The bis(thioureido) ligands have been coordinated to platinum group metals and the differing binding modes of the ligands investigated. The reaction of ligands with 2 carbon atoms between thiourea groups with [{Ru(n(^6)-С(_6)Н(_4)МеСН(Ме)(_2))С1(μ- Cl)}(_շ)], yields a mixture of products that may be consolidated into a single product with a water wash. The water instigates a deprotonation of an NH group that allows nitrogen coordination to ruthenium, yielding a S,S,N terdentate Ru(II) half-sandwich complex, with four- and seven-membered adjoining metallacycles. A chiral metal centre is formed and in the solid state, opposite enantiomers hydrogen-bond to each other through chloride counter-ions. Ruthenium complexes with an interaction from the pyridyl nitrogen in ligands containing pyridyl binding moieties have also been characterised. Bidentate S,S coordination is observed for the reaction of bisthiourea ligands with [Pd(dppe)Cl(_2)], forming nine- and ten-membered metallacycles. A similar binding mode is observed in a Pt(II) analogue. A polymer analogue of the bisthiourea ligands has been synthesised, and has been tested to extract metals from mixed metal solutions. Using well-defined metal salts in methanol, ruthenium(II) may be loaded onto the polymer from a single metal solution, acetontrile solvent inhibits the uptake of platinum group metals from mixed metal solutions, the polymer is selective for Cu(II) even when acetonitrile solvent is present and in the absence of Cu(II) or acetonitrile, can selectively extract Pt(II) over Ru(II), Fe(II), Cr(III) and Ni(II). The ruthenium loaded resin may be stripped of Ru(II) effectively using concentrated nitric acid solution in two hours. Testing the bisthiourea polymer in an acetic acid mixed metal solution demonstrated that the polymer was not suitable for platinum group metal extraction from the acetic acid medium, when compared to a commercially available resin.
35
Wenger, J. C. "Surface chemistry of the group IIB metal dimethyls on platinum." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334697.
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Mack, Cherie-Lynn. "Screening of technologies for the recovery of rhodium (III) metal ions from a precious metal refinery wastewater." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1004046.
Full textAbstract:
The selective recovery of rhodium from wastewaters, in which the metal would be otherwise lost, would be highly profitable if the process were suitably low-cost. Current recovery processes are generally high maintenance and high-cost, whereas biological processes can be engineered to run with little external input in terms of cost and maintenance. Three emerging technologies were chosen based on their reported efficiency when removing base metals from wastewaters. The first technology screened, the sulphide-extraction membrane bioreactor (SEMB), consists of a sulphate-reducing prokaryote (SRP) anaerobic digester, in which a silicone membrane is submerged. Wastewater is passed through the membrane and metal ions are precipitated as metal sulphides by the hydrogen sulphide gas, which is capable of permeating the membrane. The second technology screened was a fluidized sand bed reactor in which metal ions are removed from solution via induction of nucleated precipitation by sodium carbonate onto the sand grains. The third, and most well established removal technology screened was a biosorption system using immobilized Saccharomyces cerevisiae biomass as the biosorbent. Experimental trials with each technology highlighted drawbacks with each; the SEMB system proved to be largely ineffective when challenged with the removal of rhodium from the wastewater as the rhodium precipitate fouled the membrane within hours, the fluidized bed system seemed unable to overcome the acidity of the wastewater and thus could not precipitate out the rhodium metal, and the efficiency of the biosorption process was hampered by the diversity of rhodium species present in the wastewater, which reduced the amount recovered. The outcomes of the trials with each technology indicated that further optimization of the technology or pretreatment of the wastewater is necessary before any of these options can be implemented. It could be concluded, however, that despite further optimization, both the SEMB and the fluidized bed system were not applicable in this case as precipitation would be non-specific, resulting in the necessity for further steps in order to purify the rhodium ions. Hence, the biosorption system was shown to be most applicable, and further optimization of the system could yield a highly efficient rhodium recovery process.
37
Fraser, Adam Earl. "Synthesis and characterisation of gold- and platinum-based multimetallic catalysts." Thesis, University of Cambridge, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709517.
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Mayo, Richard Andrew. "Transition-metal derivatives of phosphine, arsine and stibine." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/15303.
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Nxusani, Ezo. "Synthesis and analysis of Novel Platinum group Metal Chalcogenide Metal Quantum Dot and Electrochemical Markers." University of the Western Cape, 2018. http://hdl.handle.net/11394/6424.
Full textAbstract:
Magister Scientiae - MSc (Chemistry)<br>Although cadmium and lead chalcogenide quantum dot have excellent optical and photoluminescent
properties that are highly favorable for biological applications, there still exists increasing concerns
due to the toxicity of these metals. We, therefore, report the synthesis of new aqueous soluble IrSe
quantum dot at room temperature utilizing a bottom-up wet chemistry approach. NaHSe and H2IrCl6
were utilized as the Se and Ir source, respectively. High-resolution transmission electron microscopy
reveals that the synthesized 3MPA-IrSe Qd are 3 nm in diameter. The characteristics and properties
of the IrSe Qd are investigated utilizing, Selected Area electron diffraction, ATR- Fourier Transform
Infra-Red Spectroscopy, Energy Dispersive X-ray spectroscopy, Photoluminescence, Cyclic
Voltammetry and chronocoulometry. A 3 fold increase in the optical band gap of IrSe quantum dot in
comparison to reported bulk IrSe is observed consistent with the effective mass approximation theory
for semiconductor materials of particles sizes < 10 nm. The PL emission of the IrSe quantum dot is at
519 nm. Their electro-activity is studied on gold electrodes and exhibit reduction and oxidation at -
107 mV and +641 mV, with lowered reductive potentials. The synthesized quantum dot are suitable
for low energy requiring electrochemical applications such as biological sensors and candidates for
further investigation as photoluminescent biological labels.
40
Getton, Frederick P. "Design of metal oxide catalysts." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314049.
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Getty, April D. "Syntheses and reactivity studies of hydroxo-palladium(II) and amido-platinum(IV) complexes /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8653.
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Coleman, Nicholas Richard Boldero. "Direct liquid crystal templating of mesoporous silica and platinum." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302011.
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Coston, T. P. J. "Studies of transition metal complexes using dynamic NMR techniques." Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380737.
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Hinot, Karelle. "Catalytic soot oxidation by platinum on sintered metal filters influence of the platinum quantity, particle size and location, and investigation of the platinum soot contact /." Karlsruhe : Univ.-Verl. Karlsruhe, 2007. http://www.uvka.de/univerlag/volltexte/2007/201/.
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Hinot, Karelle. "Catalytic soot oxidation by platinum on sintered metal filters influence of the platinum quantity, particle size and location, and investigation of the platinum soot contact." Karlsruhe Univ.-Verl. Karlsruhe, 2006. http://www.uvka.de/univerlag/volltexte/2007/201/.
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McAslan, Ewan Blyth. "Synthetic, structural and spectroscopic studies on some platinum group metal complexes." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/28560.
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Ghaffar, Tallit. "Synthesis, structure and catalytic activity of some platinum group metal complexes." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281709.
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Wilson, Tamsyn Sarah Elisabeth. "The interaction of platinum group metal nanocrystals with selected oxide supports." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614912.
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Burger, M. R. (Marga Retha). "Condensed phase properties of platinum group metal complexes from computational simulations." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16263.
Full textAbstract:
Thesis (MSc)--University of Stellenbosch, 2004<br>ENGLISH ABSTRACT: A variety of computational techniques are used to calculate structural, thermodynamic and transport
properties of two specific Platinum Group Metal (PGM) complex systems. The first system consists of
a PGM complex ([PdCl4]2-; [PtCl4]2-; [PtCl6]2- or [RhCl6]3-) with sodium counter-ions in a water
solution at 30ºC and at a concentration of 0.106 mol/dm3. The second system under consideration is
that of a PGM complex ([PdCl4]2-; [PtCl4]2-; [PtCl6]2- or [RhCl6]3-) with sodium counter-ions in a water
solution in the presence of four poly (ethylene oxide) (PEO) chains at 30ºC and at a concentration of
0.013 mol/dm3. A conformational study of the two types of dihedral angles in a PEO chain (-C-O-C-Cand
-O-C-C-O-) is performed and the extreme flexibility of the polymer is confirmed. Dihedral angle
distributions of the two dihedral angles are calculated and explained in terms of the potential energy
surface obtained from the conformational study. The solvation geometries of the PGM complexes are
confirmed and the results are contrasted with those in the system where the polymer (PEO) is present.
It is concluded that the effect of the polymer on the structure and degree of solvation is negligible. The
free energy of solvation values of the PGM complexes are calculated to provide insight into their
structural characteristics such as solvation shell volume and geometry. The structural and
thermodynamic properties of the PGM complexes in solution are also used to explain the trends
observed in the calculated diffusion coefficients. Comments are made on the accuracy of the calculated
diffusion coefficients as well as the legitimacy of the mechanistic speculations which results from
them. Suggestions regarding possible future improvements to the computational methods are made.<br>AFRIKAANSE OPSOMMING: Verskeie berekenings tegnieke is aangewend om die strukturele, termodinamiese en verplasings
eienskappe van twee spesifieke Platinumgroep Metaal (PGM)-kompleks sisteme te bereken. Die eerste
sisteem bestaan uit die PGM-kompleks ([PdCl4]2-; [PtCl4]2-; [PtCl6]2- of [RhCl6]3-) met natrium teenione
in water by 30ºC en met ‘n konsentrasie van 0.106 mol/dm3. Die tweede sisteem bestaan uit die
PGM-kompleks ([PdCl4]2-; [PtCl4]2-; [PtCl6]2- of [RhCl6]3-) met natrium teen-ione in water in die
teenwoordigheid van vier poli-etileenoksied (PEO) kettings by 30ºC en met ‘n konsentrasie van 0.013
mol/dm3. ‘n Studie is gemaak van die konformasies van die twee soorte dihedrale-hoeke in ‘n PEOketting
(-C-O-C-C- en -O-C-C-O-) en die insense buigbaarheid van die polimeer is hiermee bevestig.
Die dihedrale-hoek-verspreidings van die twee tipes dihedrale hoeke is bereken en word verduidelik in
terme van die potensiёle energie kromvlakke soos bereken tydens die konformasie analiese. Die
geometrie van die solvasie van die PGM-komplekse is bereken en vergelyk met die sisteme waar die
polimeer (PEO) teenwoordig is. Hieruit word afgelei dat die effek van die polimeer op die struktuur en
graad van solvasie van die komplekse minimal is. Die vrye energie van solvasie van die PGMkomplekse
is bereken met die doel om insig in te win oor die stukturele eienskappe soos byvoorbeeld
die volume van die solvasie sfeer en die geometrie daarvan. Die strukturele en termodinamiese
eienskappe van die PGM-komplekse in oplossing word ook gebruik om die neigings in die berekende
diffusie koёffisiente te verduidelik. Opmerkings word gemaak aangaande die akkuraatheid van die
berekende diffusie koeffisiente asook die geldigheid van die meganistiese spekulasies wat daaruit
gemaak word. Voorstelle word ook gemaak rakende toekomsige verbeterings aan die reken tegnieke.
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Bunker, Janet Constance. "The effects of some platinum group metal complexes on bacterial growth." Thesis, Royal Holloway, University of London, 1985. http://repository.royalholloway.ac.uk/items/a0148261-1454-40d1-94dc-bf2b46c26c71/1/.
Full textAbstract:
Experimental conditions were established which gave reproducible power-time and biomass-time traces for Klebsiella aerogenes growing in glucose-limited medium and Staphylococcus aureus 13137, Ps47 and Pseudomonas aeruginosa in nutrient broth. Aeration of the cultures was critical in determining the shape and reproducibility of the power-time traces. High oxygen tensions caused a reduction in the final biomass value and an increase in waste heat production in nutrient broth. Biomass production occured without any accompanying heat production and vice versa in nutrient broth. The reproducible power-time and biomass-time traces were used to assess the effects of a range of platinum group metal complexes (PGMC) on bacterial metabolism. Several complexes showed anitbacterial activity unlike any other antibacterial agent studied, whilst other complexes had a negligible effect on bacterial growth. Generally complexes were active against either K.aerogenes or S.aureus. Neither organism was able to develop resistance against active complexes. No structure-activity relationships could be established. However, three square-planar palladium complexes, with different ligands, had similar effects on the thermal and growth properties of K.aerogenes. Changes occurring in PGMC solutions with time, monitored spectrophotometrically, reduced antibacterial activity as did interactions between the complex and components of nutrient broth. PGMC solutions had a markedly different effect on bacterial growth when present in the medium before inoculation compared to the effect when the complex was injected in the mid-exponential growth phase. Microcalorimetry is a technique which allows for rapid screening of complexes and continuous monitoring of their effects on bacterial metabolism. The apparent inability of bacteria, even a strain of S.aureus resistant to several antibiotics, to develop resistance against active complexes indicates their potential in clinical applications.