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1
Malcolm, Robert Karl. "Tactic poly(olefin sulphone)s." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295459.
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Fee, S. J. G. "Studies of the conformational properties of simple alkyl sulphones and poly(olefin sulphone)s." Thesis, Queen's University Belfast, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373529.
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Kneale, Christopher Juan. "Synthetic and mechanistic aspects of organosulphur chemistry." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253138.
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Al-Jebouri, Hamza Yaseen. "Synthesis of butadiene sulphone derivatives with cyano substituents." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/847181/.
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The vicinal dicyano compounds are good starting materials for the synthesis of macromolecules such as phthalocyanines and tetrazaporphins. The synthesis of cyano compounds and vicinal dicyano compounds, particularly the cyano derivatives of butadiene sulphones have been studied in this work. This thesis is divided into five chapters as follows: The first chapter contains a general introduction about organic cyanides; their preparations, reactions and applications. In the second chapter, the synthesis of butadiene sulphone derivatives leading to mono and dicyano substituents is dealt with. It includes some mechanistic studies as well as spectroscopic studies by means of ir, [1]H nmr and mass spectrometry. Chapter three discusses the synthesis of 3-cyano-and 3,4-dicyanodihydrothiophene. Oxidation of dihydrothiophenes into butadiene sulphones is also discussed in this chapter. The synthesis of alpha,beta-unsaturated nitriles from ketones and aldehydes, and in particular, the synthesis of 2,3-dicyano-1,3-butadiene is discussed in chapter four. The addition of hydrogen cyanide to alpha,beta-unsaturated nitriles is also discussed. Chapter five deals with the multistep synthesis of 2,3-dicyano-1,3-butadiene from phthalic anhydride. It also contains some mechanistic studies.
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Sergis, Andreas Neophytos. "Reactions of sulphone stabilised carbanions with fluorinated aromatic compounds." Thesis, University of Greenwich, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280469.
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Phillipson, Neil. "Ketone homologation via hydroxy sulphone rearrangement - a new method for the synthesis of polyoxygenated carbon frameworks." Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282294.
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Denness, James E. "The preparation and characterisation of trifluoromethylated poly(ether sulphone)s and poly(ether ether ketone)s." Thesis, University of York, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306268.
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Ngabe, Barnabe. "Physical chemistry of sulphide self-heating." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123024.
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ABSTRACTA prerequisite step towards building a self-heating (SH) model for sulphide materials is the determination of physico-chemical parameters such as the specific heat capacity (Cp), and the energy of activation (Ea). The specific heat capacity of one copper and three nickel concentrates was determined over the temperature range 50 to 80oC in the presence of 6% moisture using the self-heating (SH) apparatus and confirmed by Drop Calorimetry. The Cp values from both techniques were comparable. The Cp values were similar for all concentrates increasing from 0.4 to 1.4 Jg-1K-1 as temperature increased from 50 to 80oC. From the Cp values, the enthalpy change (ΔH), the entropy change (ΔS) and the Gibbs free energy change (ΔG) for self-heating, were determined. The ΔG was negative, demonstrating that self-heating of the concentrates was spontaneous.Using the self-heating apparatus the, activation energy (Ea) was determined for the Ni-and Cu-concentrates and for pairs of sulphide minerals. The Ea ranged from 22 to 30 kJ.mol-1, implying a common reaction. Further support for a common reaction is the strong positive correlation between Ea and ln(QA/Cp) where Q (J.kg-1) is the heat of reaction causing self-heating and A the Arrhenius pre-exponential factor (s-1). Comparing to literature, the Ea values correspond to partial oxidation of hydrogen sulphide, supporting the contention that H2S may be an intermediate product in the self-heating of sulphide minerals. A positive relationship between Ea and the rest potential difference (ΔV) for the sulphide pairs and a negative relationship between Cp and ΔV were demonstrated which support a connection between self-heating and the galvanic effect.RESUMÉLa réalisation d'un modèle mathématique de l'auto-échauffement des concentrés sulfurés de nickel et de cuivre et des mélanges des minerais sulfurés, enjoint à la détermination des paramètres physico-chimiques tels que les capacités de chaleur spécifiques (Cp), et les énergies d'activation (Ea). Les capacités de chaleur spécifiques d'un concentré de cuivre et de trois concentrés de nickel contenant 6% d'humidité, ont été déterminées par utilisation d'un instrument de mesure de vitesse d'auto – échauffement et validées par la calorimétrie de chute dans l'intervalle de températures allant de 50 à 80oC. Les Cp (0.4 à 1.4 Jg-1K-1) obtenues sont similaires pour tous les échantillons. A partir des valeurs des Cp, les variations de l'enthalpie (ΔH), l'entropie (ΔS) et de l'énergie libre de Gibbs (ΔG) de l'auto échauffement ont été déterminées. La valeur négative de ΔG confirme le caractère spontané de l'auto échauffement des minerais sulfurés.Les énergies d'activation (Ea) pour l'auto-échauffement des concentrés de nickel et cuivre et des paires de minerais sulfurés étaient déterminées en faisant usage de l'appareil d'auto-échauffement. Les Ea ainsi obtenues oscillent entre 22 et 30 kJ.mol-1 : Ce qui est suggestif d'une rèaction chimique commune gouvernant l'auto-échauffement de ces matériaux. Ce fait est corroboré par la forte corrélation obtenue entre Ea et ln(QA/Cp) (Q (J.kg-1) est la chaleur de la rèaction chimique responsable de l'auto-échauffement et A (s-1) la constante d'Arrhenius).Ensuite celles-ci sont similaires à celle de l'oxydation partielle du H2S. Il se pourrait, ce faisant, que H2S soit un composé intermediaire lors de l'auto–échauffement des sulfures.Enfin, la corrélation positive entre Ea et la difference de potential (ΔV) dans les paires de minerais sulfurés et celle negative entre Cp et ΔV sont une preuve qu'il existe bel et bien une connection entre l'auto-échauffement et l'effet galvanique.
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Hewkin, Cheryl T. "New chemistry of sulphonyl substituted small rings." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293576.
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Laffey, Thomas Gerard. "Applications of sulphones in organic synthesis." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276586.
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Doherty, Stephen. "The photochemistry and photophysics of colloidal dipsersions of zinc sulphide and cadmium sulphide." Thesis, University of East Anglia, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306053.
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The potential use of colloidal semiconductor systems regarding solar energy conversion and preparative organic chemistry has long been recognised. However there have been few reports concerning the characterisation of semiconductor systems with a view to identifying the factors which affect semiconductor photocatalysis. This thesis identifies the main criteria which control energy ttansfer from the semiconductor excited state to an acceptor molecule. 1bese factors are: degradation (the semiconductor must be stable under photolysis conditions). thermodynamics (charge ttansfer from the semiconductor excited state to the acceptor ground state must be exothermic). kinetics (long lived semiconductor excited states favour energy ttansfer) and physical (charge transfer generally requires intimate contact between the donor/acceptor species). In order to satisfy these conditions ZnS. CdS and ZnS/CdS semiconductors have been prepared in iPAJwa~. AOT/heptane!water and water. Together. these systems provide three distinct phases for additive dissolution (i.e. water. iPA, heptane). UV/VIS absorption spectroscopy has been used to detennine the absorption onset positions of the colloids. From these measurements it has been found that the CdS, ZnS and CdSlLnS systems have absorption onset energies ranging from 2.53 to 4.96 eV which are dependent on the semiconductor particle sizes. Importantly, co-colloidal CdSlLnS systems have been prepared which have tuneable absorption onset energies (2.53 to 4.96 eV). Furthermore. the AOT !heptane/water systems show indefinite stability to dark ageing. Photolysis experiments (l = 254 nm) have revealed that semiconductor photodegradation shows a marked oxygen dependence and can be inhibited by the presence of charge scavengers (e.g. S2-. isopropanol) illustrating the importance of surface reactions. These results led to the development of semiconductor systems which had photodegradation quantum yields of zero. Time-resolved and steady state measurements have proven that semiconductors luminesce with high quantum yields (~ > 0.1), via an "allowed" process, over nanosecond time scales. The luminescence excitation spectra show the characteristic semiconductor absorption profile. The semiconductors give a broad emission band (1.91 to 3.4 eV) which is Stokes shifted from the absorption profile (by up to 0.9 eV). The importance of surface sites has been demonstrated and the main non-radiative (e.g. M-aqua and M-S042-) and radiative centres (M2+, S2-) have been identified. It has been found that luminescence quenching by additives is a powerful indicator for energy ttansfer processes. The results from iP A quenching experiments led to the photochemistry of CdS and ZnS in iP Nwaaer being investigated. Upon illumination of both of these systems (A = 254 nm; a wavelength at which iPA does not absorb) acetone was produced with a concomitant reduction in the iPA concentration (measured using IH and 13C NMR). Finally, new models have been proposed for the "exciton" absorption, photodegradation and photoluminescence of conoidal semiconductor systems
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Galer, Jacqueline Mary. "Synthesis and characterisation of electrically conducting copper sulphide coating copper sulphide coatings on polymeric fibres and films." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317628.
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Cooper, W. S. "Characterisation of sulpho oils." Thesis, Liverpool John Moores University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375103.
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Paulls, David Andrew. "Enhancement of the chemiluminescent oxidation of sulphite." Thesis, University of Hull, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337058.
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West, John. "The low temperature hydrolysis of carbonyl sulphide." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366499.
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Stebbing, Simon Richard. "The optical properties of colloidal cadmium sulphide." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265327.
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Belissont, Rémi. "Germanium and related elements in sulphide minerals : crystal chemistry, incorporation and isotope fractionation." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0049/document.
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Le germanium est un métalloïde « stratégique » dans l’industrie high-tech, notamment pour la transition énergétique et le secteur des communications. Étant distinctement sidérophile, lithophile, chalcophile et organophile, le Ge possède un fort potentiel comme traceur géochimique. Ces travaux de thèse visent à améliorer la compréhension de la géochimie du cycle du Ge et des facteurs qui contrôlent son incorporation dans les minéraux et les gisements métalliques. Les cibles de cette étude concernent le gisement filonien à Zn de Saint-Salvy (Massif Central, France), le gisement filonien à Cu de Barrigão (Ceinture pyriteuse ibérique, Portugal), et le gisement à Zn–Cu de Kipushi (R.D. Congo). Les porteurs de Ge les plus importants sont respectivement la sphalérite (jusqu’à 2580 ppm), la chalcopyrite (jusqu’à 5750 ppm) et la réniérite (5,0–9,1 %). Les résultats montrent qu’il existe une relation de premier ordre entre la concentration en Ge dans la sphalérite et le type de gisement. La spectroscopie XANES par rayonnement synchrotron met en évidence la présence de Ge4+ en site tétraédrique dans les sulfures analysés. Les corrélations élémentaires observées dans la sphalérite et la chalcopyrite suggèrent une incorporation du Ge par co-substitutions, e.g., 3Zn2+ ↔ Ge4+ + 2(Cu,Ag)+ et 3Fe3+ ↔ 2Ge4+ + Cu+, ou via la création de lacunes cristallographiques, e.g., 2Zn2+ ↔ Ge4+ + ?. La corrélation positive δ74Ge–[Ge]ZnS des sphalérites de Saint-Salvy indiquerait que coefficient de partage (KdGe) augmenterai avec T. Les compositions isotopiques δ74Ge des sulfures étudiés varient de –5,72‰ à +3,67‰. Les compositions légères mesurées dans les gisements de Saint-Salvy et Barrigão semblent liées à des variations de température des fluides (basse à moyennes T) lors de l’incorporation de Ge en système ouvert, alors que la tendance marquée vers les compositions isotopiques lourdes à Kipushi indiquerait un fractionnement de RayleighGermanium is a critical metalloid in many high-tech industries, especially for the energy transition and the communication sector. Being distinctly siderophile, lithophile, chalcophile and organophile, Ge can be a particularly useful geochemical tracer. This thesis aims at understanding the Ge geochemistry and the factors controlling its concentration in Ge-bearing minerals and ore deposits. Three contrasted Ge-bearing deposits were studied, the Saint-Salvy Zn vein-type deposit, French Massif Central, the Barrigão Cu vein-type deposit, Iberian pyrite belt, Portugal, and the Kipushi Zn–Cu carbonate-hosted deposit, Central African copper-belt, D.R. Congo. The most important Ge-bearing minerals are sphalerite (up to 2580 ppm Ge), chalcopyrite (up to 5750 ppm Ge), and renierite (5.0–9.1 wt.% Ge). The results show a first order relation between the Ge content and the deposition temperature. Synchrotron-based XANES spectroscopy showed that Ge4+ occur in tetrahedral sites in the studied sulphides. Element correlations suggest that Ge is chiefly incorporated in sphalerite and chalcopyrite through coupled substitutions, e.g., 3Zn2+ ↔ Ge4+ + 2(Cu,Ag)+ and 3Fe3+ ↔ 2Ge4+ + Cu+, respectively, or via the creation of lattice vacancies, e.g., 2Zn2+ ↔ Ge4+ + ?. The positive δ74Ge–Ge content correlation observed in sphalerite from Saint-Salvy could indicate that Ge partition coefficient (KdGe) increases with temperature. Ge isotopes in sulphides yield δ74Ge values spanning from –5.72‰ to +3.67‰. The light δ74Ge compositions of Saint-Salvy and Barrigão ores appear to be related to variations in low to moderate fluid temperatures during Ge uptake in open system (e.g., fluid cooling), while the trend towards heavy δ74Ge compositions observed at Kipushi likely translates a Rayleigh fractionation effect during ore formation in closed system, associated with significant fluid modification
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Ikumapayi, Fatai Kolawole. "Flotation chemistry of complex sulphide ores : recycling of process water and flotation selectivity." Licentiate thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26634.
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Recycling of flotation effluents through the ore processing plant is one of the ways of reducing both plant-operating costs and industrial impact onto the local ecosystem. Such waters named acid mine drainage (AMD), if discharged from sulphide flotation are gypsum (CaSO4.H2O) saturated and have a high salinity (on the order of 1000 ppm). As minor species, they commonly contain reduced sulphur compounds (RSC) (sulfoxyanions with sulphur in the oxidation state below (VI) such as SO32-, S2O32-, S2O52-, and S4O62-), cations of ferrous and non-ferrous metals, frothing molecules, residual chemical reagents and products of their degradation. Tailing ponds also host communities of chemolithotrophic and heterotrophic microorganisms which play an important role in dictating their aqueous and solid phase chemical speciation. Consequently, the key step towards developing scientific approaches of recycling of the tailing waters is elucidation of how, in what extent, and why the tailing water components, taken singly or jointly influence flotation of sulphides. In this work, the influence of main process water components of calcium and sulphate on chalcopyrite, galena, sphalerite and pyrite flotation has been investigated through Hallimond flotation, zeta-potential and diffuse reflectance FTIR spectroscopy measurements using pure mineral samples as well as bench scale flotation tests using complex sulphide ore. The significance of process water species in flotation has been assessed using deionised water, process water and simulated water containing calcium and sulphate ions in experiments. In addition, the effect of temperature in bench scale flotation tests has also been examined. Hallimond flotation indicated depression of chalcopyrite, galena and sphalerite and activation of pyrite in the presence of calcium and sulphate ions with potassium amyl xanthate as collector. Calcium ions have significant influence on zeta-potential characteristics and xanthate adsorption behaviour of chalcopyrite, galena, sphalerite and pyrite compared to sulphate ions. FTIR studies revealed the presence of surface oxidised sulfoxy species and surface iron and calcium carbonates on chalcopyrite in the presence of process water and water containing calcium ions, surface oxidised sulfoxy and carbonate species on galena in the presence of deionised water, process water and water containing calcium and sulphate ions, hydrated surface oxidised species and surface iron and calcium carbonates on pyrite in the presence of process water and water containing calcium ions all at pH 10.5 in which the surface species influenced xanthate adsorption. The presence of surface oxidised sulfoxy and carbonate species on sphalerite were also revealed at pH 11.5 in the presence of deionised water, process water and water containing calcium and sulphate ions in which surface species does not influence xanthate adsorption. Bench scale flotation using two different complex sulphide ores showed that chalcopyrite recovery is better in process water than tap water and general depression of chalcopyrite at temperatures lower than 22oC in either tap water or process water, activation of chalcopyrite at all temperatures in process water and depression of chalcopyrite when tap water containing calcium and sulphate ions was used at 22oC. It also showed that galena recovery is better in tap water than process water and depression of galena at temperatures lower than 22oC in either tap water or process water. It also showed that sphalerite recovery is better in process water than in tap water better recovery of sphalerite at temperatures lower than 22oC in either tap water or process water.Godkänd; 2010; 20101114 (fatiku); LICENTIATSEMINARIUM Ämnesområde: Mineralteknik/Mineral Processing Examinator: Professor Kota Hanumantha Rao, Luleå tekniska universitet Diskutant: PhD Jaakko Leppinen, Outotec, Non-Ferrous Solutions, Espoo, Finland Tid: Fredag den 10 december 2010 kl 10.00 Plats: F531 Bergrum, Luleå tekniska universitet
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Deuchar, Christopher Norton. "The detection and measurement of hydrogen sulphide." Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/10223/.
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Gas measurement techniques for hydrogen sulphide (H2S) have been investigated, with particular reference to the monitoring of average ambient concentrations and also the rapidly changing concentrations which may be associated with vehicle pollution. Two new techniques have been identified, and new equipment built and tested, for H2S determination. The first of these is designed to measure long term average concentrations of H2S and the second to evaluate rapidly changing peak concentrations over very short periods of time. The implementation of catalytic converters in modern petrol driven motor vehicles has resulted in undesirable emissions of hydrogen sulphide gas. The reasons for these emissions are discussed. Ambient concentrations of H2S have been measured at the roadside and the average contribution originating from vehicular emissions on major roads determined. Results are presented which confirm the elevation of hydrogen sulphide concentrations at the road side of an average of single figure parts per billion. Peak H2S concentrations of up to 100 ppb were also measured at the roadside and within motor vehicles. The peaks were of very short duration and therefore of only minimal contribution to average ambient concentrations. Measurements of H2S concentrations at a variety of locations have also been made,and results are presented, of comparisons between areas with no source of H2S nearby, roadside sites and other possible H2S sources such as sewage treatment works and landfill sites. Known H2S concentrations, in excess of 500 ppm from a point source on a landfill site, were found to diminish rapidly toward zero, within 150 m of the source. This demonstrated the high reactivity of H2S and therefore the importance of measuring H2S concentration as closely as possible to the emission source. Consequently, this high reactivity is particularly important in the consideration of roadside and 'on-road' monitoring of H2S.
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Green, Kevin J. "Photocatalytic studies with titanium dioxide and cadmium sulphide." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335627.
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Bartels, Birgit. "A study of activated ketal reduction with borane dimenthyl sulphide." Doctoral thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/22140.
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Carbonyl reduction to secondary alcohols is a fundamentally important reaction in organic chemistry and many reagents have been developed for achieving this transformation efficiently, with regard to both the optical and material yield. An alternative approach, popularized in recent times, is the dissociative reduction of ketals to afford ethers as protected secondary derivatives and a number of approaches accomplishing a high degree of stereoselectivity have been developed. This thesis describes a study of a novel reagent combination, namely borane dimethyl sulphide and trimethylsilyl trifluoromrthanesulphonate (TMSOTf) for reductive ketal cleavage.
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Poole, Mark Charles. "Synthetic and spectroscopic studies of organic sulphides, sulphoxides, sulphones, and their metal complexes." Thesis, University of Exeter, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332281.
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Wright, J. A. "Factors influencing the adsorption of polyelectrolytes on barium sulphate." Thesis, University of Salford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372161.
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Healy, J. "Some metal sulphide interactions governing copper solubility and availability." Thesis, Robert Gordon University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379262.
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Fredriksson, Andreas. "Adsorption of heptyl xanthate at the metal sulphide/aqueousinterface." Licentiate thesis, Luleå, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16791.
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In sulphide mineral flotation a sufficient hydrophobicity of the mineral surfaces is obtained by the adsorption of collector chemicals at the metal sulphide/aqueous interface. This surface alteration is of fundamental and applied interest. In this thesis, attenuated total reflection infrared spectroscopy has been used to monitor the adsorption kinetics and the orientation of heptyl xanthate when adsorbed onto three solid surfaces - germanium, zinc sulphide and lead sulphide in-situ. The choice of using the ATR technique is because it is very suitable when working with water as solvent, and the choice of germanium as internal reflection element is because of its small penetration depth due to a high refraction index. The Chemical Bath Deposition method has been used to deposit metal sulphides onto germanium internal reflection elements. For determining the adsorption of heptyl xanthate onto lead sulphide a novel method has been tested, and verified as capable in recovering information about surface reactions at a lead sulphide/aqueous interface. In the study of surface reactions the substrate is of vast importance, implying that the chemistry of the surface has to be well characterised. This work has utilized X-ray Photoelectron spectroscopy, and ATR spectroscopy, in the characterisation of the different surfaces. The adsorption kinetics has been followed to adsorption equilibrium at different concentrations. In the case of heptyl xanthate adsorbed at the zinc sulphide/aqueous interface, an adsorption isotherm has been calculated from the equilibrium data. On the assumption that the adsorption step was rate controlling a second order rate equation was derived and adsorption rate data tested according to this equation. In addition, an orientation study of the heptyl xanthate molecule at the different interfaces was performed, which requires polarised infrared light. In the case of heptyl xanthate adorbed onto germanium, both surface excess and a degree of alignment of the alkyl chain from the surface normal has been calculated.Godkänd; 2004; 20070127 (ysko)
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Vacalis, N. "Formation of 3-deoxyhexosulose in the sulphite-inhibited Maillard reaction." Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373476.
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Goh, Siew Wei Chemistry Faculty of Science UNSW. "Application of surface science to sulfide mineral processing." Awarded by:University of New South Wales. School of Chemistry, 2006. http://handle.unsw.edu.au/1959.4/32912.
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Surface spectroscopic techniques have been applied to facets of the flotation beneficiation and hydrometallurgical extraction of sulfide minerals to enhance the fundamental understanding of these industrially important processes. As a precursor to the determination of surface chemical composition, the sub-surface properties of some sulfide minerals that have not previously been fully characterised were also investigated. The electronic properties of ??-NiS and ??-NiS (millerite), Ni3S2 (heazlewoodite), (Ni,Fe)9S8 (pentlandite), CuFe2S3 (cubanite), CuFeS2 (chalcopyrite), Cu5FeS4 (bornite) and CuS (covellite) were investigated by conventional and synchrotron X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy augmented by ab initio density of state calculations and NEXAFS spectral simulations. Particular aspects studied included the relationship between sulfur coordination number and core electron binding energies, the higher than expected core electron binding energies for the sulfur in the metal-excess nickel sulfides, and the formal oxidation states of the Cu and Fe in Cu-Fe sulfides. It was concluded that the binding energy dependence on coordination number was less than previously believed, that Ni-Ni bonding was the most likely explanation for the unusual properties of the Ni sulfides, and that there was no convincing evidence for Cu(II) in sulfides as had been claimed. Most of the NEXAFS spectra simulated by the FEFF8 and WIEN2k ab initio codes agreed well with experimental spectra, and the calculated densities of states were useful in rationalising the observed properties. XPS, static secondary ion mass spectrometry (SIMS) and NEXAFS spectroscopy were used to investigate thiol flotation collector adsorption on several sulfides in order to determine the way in which the collector chemisorbs to the mineral surface, to differentiate monolayer from multilayer coverage, and to characterise the multilayer species. It was found that static SIMS alone was able to differentiate monolayer from multilayer coverage, and together with angle-resolved NEXAFS spectroscopy, was also able to confirm that 2-mercaptobenzothiazole interacted through both its N and exocyclic S atoms. The altered layers formed on chalcopyrite and heazlewoodite during acid leaching were examined primarily by means of threshold S KLL Auger electron spectroscopy, but no evidence for buried interfacial species was obtained.
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Luu, Wing T. "Effect of Aluminum Sulfate and Sodium Alumniate on the Drainage and Retention Properties of Fibrous Suspensions." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/LuuWT2005.pdf.
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Neo, Darren Chi Jin. "The surface chemistry and interface engineering of lead sulphide colloidal quantum dots for photovoltaic applications." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:3a23c635-992b-4e46-94d6-72c2aea61ce9.
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This thesis examines the effect of lead sulphide (PbS) CQDs' surface chemistry and interfaces to their photovoltaic performance. Using PbS CQDs as the starting material, cation-exchange was utilised to form PbS/CdS core/shell CQDs, which were thoroughly characterised and the improved surface passivation was shown by increased photoluminescence yield and lifetime. The core/shell CQDs were incorporated into a ZnO/CQD heterojunction solar cell device and showed a substantial improvement of the mean open-circuit voltage (Voc), from 0.4 V to 0.6 V, over PbS reference devices. By optimising shell thickness and surface ligands, core/shell CQD devices with average device efficiency of 5.6 % were fabricated as compared to 3.0 % for unshelled PbS devices. The lower defect density due to better passivation confers lower carrier density in core/shell CQD film. To take advantage of low defect concentration and to aid charge extraction, a 3 dimensional quantum funnel concept was sought of by blending two populations of PbS/CdS CQDs of different sizes. By incorporating a blend component within a heterojunction device, even when the device thickness is beyond what is optimal for the depletion width and the diffusion length of the system, high Voc is still maintained. In a separate study, a p-i-n device strategy was examined, and with this approach, a maximum device efficiency of 6.4 % was achieved. Despite the improvements made to Voc by optimizing surface passivation, fill factors of the devices are low. By using poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole transport material (HTM), fill factor and the overall performance improved over a reference device without the HTM. Further studies showed that oxidation of the HTM material results in increased p-type characteristic, thus optimising hole transport. This beneficial oxidation process also makes the device air-stable. From this, devices of up to 8.1 % efficiency and devices with fill factor as high as 0.72 were fabricated.
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Swift, Simone. "Molecular modelling of the complex polysaccharide heparan sulphate." Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/10739/.
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Heparan Sulphate plays an important role in many life processes and so an understanding of its role as a universal co-receptor is of great importance. Traditionally oligosaccharides derived from the related molecule heparin have been at the forefront of molecular drug design, due to its similarity in structure and function. To obtain a more complex and detailed picture of the role of HS in structural biology further complex work must be undertaken on HS. Here in this study a number of HS derived octasaccharides have been purified. Alongside this is work carried on HS derived decasaccharides, of which all have undergone extensive molecular modelling simulations. The role of the Iduronates in the HS structure, at monosaccharide level has indicated a major role for these structures in biological activity. Further work has indicated the level of sulphation is also a requirement which in turn influences conformational behaviour. Up until now this has only really been studied at the monosaccharide level and so this study has generated a number of different HS models which can confirm the importance of iduronate conformation in biological activity. Not only that but it has also been identified that certain torsional geometries within the glycosidic bonds between monosaccharides also has a major influence on conformation. Local deviations in the molecular modelling data suggest there is a slight difference between active and inactive oligosaccharides with the ability to bind and activate the HS:FGF2:FGFR IIIc complex. The implications of these and other structural insights are discussed with the implication heavily towards a combination of both torsional geometry and iduronate conformation in biological activity. To further aid our understanding HS dp10 oligosaccharides were docked into a FGF2 which was in a complex with a heparin hexasaccharide. Docking experiments were carried in order to attain structural information on the binding of these molecules. The Goodger oligosaccharides were docked into the X-ray crystal structure and were chosen specifically for their iduronate conformation or the torsional geometry.
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Cai, Xin. "Determination of dapsone and its metabolites." Scholarly Commons, 1994. https://scholarlycommons.pacific.edu/uop_etds/2282.
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Methods were developed for the detection and quantification of the sulfone drug, 4,4'-diaminodiphenyl sulfone, or dapsone (DDS) and its metabolites, monoacetyldapsone (MAD) and diacetyldapsone (DAD). The work involved the synthesis of those two metabolites; confirmation of them by NMR and mass spectrometry; separation and identification of mixtures of DDS, MAD and DAD using HPLC with a uv detector and/or a mass spectrometric detector. The HPLC was operated at 1 m1/min at 285 nm, using a C-18 reversed-phase column (AXXI CHROM, 5 micron, 25cm x 2.1mm). The isochratic mobile phase consisted of 67% aqueous pH 6 phosphate buffer, 23% acetonitrile and 10% methanol, or 23% acetonitrile and 77% water. The limit of determination using a 5 pl sample was 0.2 pg/ml (0.004 nmole) for DDS, 0.3 pg/ml (0.005 nmole) for MAD and 0.4pg/ml (0.006 nmole) for DAD.
The LC/MS work was done using an electrospray interface between the HPLC and the quadrupole mass spectrometer. The LC/MS method gave crucial information to confirm the identity of the three compounds measured.
Overall, a combination of the two techniques is a superior approach for the determination of DDS and its metabolites with the MS confirming the identity of the metabolites and the HPLC separating and quantitating the analyses. Since only a small amount of sample is required in the experiment, these methods could be applied in studies involving analysis of metabolites from urine and plasma, facilitating future pharmacokinetics analysis of DDS and its metabolites.
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Oldale, Jonathan Mark. "A comparative study of the silver photodoping of amorphous germanium sulphide films." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315315.
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Hunter, C. J. "An electrochemical investigation of the froth flotation of iron bearing sulphide minerals." Thesis, Brunel University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.351913.
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Madsen, Alex. "Lithium iron sulphide as a positive electrode material for rechargeable lithium batteries." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355748/.
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Lithium iron sulphide has been investigated as a low-cost, high energy density and relatively safe positive electrode material for secondary lithium batteries. Lithium iron sulphide was synthesised, characterised and compared with natural pyrite samples and was shown to have a capacity of 350 mAh.g-1 upon cycling between 1.45 and 2.80 V vs. Li. The capacity was attributed to the Fe2+/Fe3+ redox couple at potentials up to 2.55 V, and oxidation of sulphur sites from Fe3+(S2-)2 to Fe3+S2-(S2)2-0.5 up to 2.80 V. The cycle life performance of lithium iron sulphide is poor when the cell is cycled between 1.45 and 2.80 V, with the cell loosing approximately 1.4 mAh.g-1 per cycle, although this performance is superior to comparable pyrite electrodes. Calcium doped samples of lithium iron sulphide were synthesised. Calcium doping was shown to impact upon lithium transport properties of the bulk lithium iron sulphide, improving the rate performance of the material. Improvements in cycle life performance of the calcium doped samples were offset by decreased specific capacity due to lithium substitution. The poor cycle life performance of lithium iron sulphide cells was attributed to the utilisation of the high voltage plateau corresponding to sulphur site oxidation/reduction. Experiments utilising a variety of negative electrode materials has identified the formation of soluble polysulphide species upon cycling of the cell, which reduce irreversibly at the negative electrode, contributing to active mass loss and poor cycle life performance. In-situ XRD studies have highlighted the structural decomposition that occurs upon utilisation of the sulphide, which results in irreversible amorphisation of the lithium iron sulphide crystal structure. Lithium iron sulphide was treated via coating with lithium boron oxide glass and a novel carbon coating method via thermal decomposition of butyl-methyl-pyrrolydinium-dicyanimide. Both treatments were shown to increase the cycle life performance of lithium iron sulphide, due to decreased dissolution of polysulphide upon cycling. The choice of binder, electrode formulation and electrolyte was also shown to impact upon the cycle life performance of lithium iron sulphide cells.
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Severmann, Silke. "The geochemistry and geomicrobiology of relict hydrothermal sulphide deposits." Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/42169/.
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The diagenetic re-mineralisation of seafloor-sulphide deposits and the role of microbes in the metal-exchange processes were investigated in metalliferous sediments from the Alvin relict hydrothermal zone in the TAG area at 2608'N (Mid- Atlantic Ridge). The solid-phase and concomitant pore water concentrations of AI, Si, Ca, Clot, Corg, S, Fe, Mn, Cu, Zn, P, V, Co, U, Mo, Au, Ag and REE's were measured in a 230 cm long gravity core from the southern periphery of the relict vent field. These measurements were complemented by detailed analysis of bacterial abundance and specific activity. The altered sulphidic sediments are capped with a ~30cm thick layer of carbonate-rich (~60% CaCO3), Fe-stained sediments. Two distinct sulphide layers, interbedded with Fe-oxysilicates, and overlain by a thin layer of Fe/Mn oxyhydroxides, were found in this core. The dominant mineral-phase in both sulphide layers, which originate from mass-wasting of mound sediments, is pyrite with some goethite. Reaction of the exposed metal-sulphides in the upper sulphide layer with seawater has produced a thin layer of secondary atacamite, which is enriched in Au. Primary sphalerite is dissolved in the upper sulphide layer and re-precipitation as secondary sphalerite directly above and below. U continues to be scavenged from the porewater, producing marked enrichments on oxidised sulphide rims. The re-mineralisation processes identified in this core are in close analogy to the large-scale zone-refining that has been described for the active TAG mound and ancient ore-deposits. REE/Fe ratios clearly distinguish between plume derived sediments in the carbonate cap and slumped material from the hydrothermal mound. The REE signature of bulk sediments and clay phases imply multiple stages of alteration by diffuse fluids in the upper sulphide layer and intermediate layer, whereas the lower sulphide layer is not affected. Alteration by reactive low-temperature hydrothermal fluids is also inferred to be responsible for the observed diagenetic overprinting of trace-metal distributions in the upper sulphide layer. The intermediate layer is rich in nontronite, which has been precipitated in situ from diffuse fluids. The presence of Mn- and Fe-reducing bacteria coincide with elevated porewater concentrations of Mn and Fe, indicating direct involvement of bacteria in the cycling of these metals. Total counts of viable cells and general activity measurements show that although bacterial populations are relatively small, they are healthy and well adapted to this potentially toxic environment. The existence of active microbial communities in metalliferous sediments may therefore provide a continuum of bacterial populations between high and low temperature hydrothermal systems, thus representing an important transitional stage in the hydrothermal ecosystem. Microbial reduction and oxidation of S was observed throughout the core, indicating that microorganisms are particularly active in terms of S-cycling. For deep-sea sediments extremely high sulphate reduction rates (67 nmol/cm3/d) were measured in the ironstained carbonate cap. In the absence of significant organic carbon (~0.2 %) this strongly suggests the synthesis of alternative electron-donors by chemolithotrophic bacteria to support the observed high rates of heterothrophic activity in these sediments.
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Shaw, Alan. "Synthesis and reactivity studies on oxo and sulphide compounds of the early transition metals." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6554/.
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This thesis describes studies directed towards the preparation of new oxo compounds of the early transition metals with a view to delineating some of the complex factors which govern their stability and reactivity. For a number of the types of compound studied, the work has also been extended to analogous sulphide systems in order to provide a contrast with another chalcogenide element and further aid an understanding of the bonding and reactivity of both of these elements in a transition metal enviroment. Chapter 1 highlights the areas of transition metal oxo chemistry of relevance to the general theme of the thesis. Chapter 2 describes the use of the commercially available reagents Me(_3)SiYR (R = alkyl, SiMe(_3); Y = O, S), for rapid, convenient, solution syntheses of transition metal oxohalide and sulphidohalide compounds of molybdenum, tungsten, niobium and tantalum. In addition, this methodology allows the preparation of mixed oxosulphidohalide materials and, in certain cases, intermediate alkoxo(siloxo) halide compounds have been isolated. Chapter 3 describes the synthesis, characterisation and reactivity of a series of mononuclear mono-oxo complexes of molybdenum and tungsten including M(O)(OAr)(_4) [M=W, Ar=2,6-Me(_2)C(_6)H(_3) (DMP), 2,4,6-Me(_3)C(_6)H(_2) (TMP), 2,6-Pr(^i)C(_6)H(_3) (DIPP); M=Mo, Ar=(DMP)], M(_2)(O)(_3)(DMP)(_6) and Mo(O)C1(_2)(DMP)(_2). Attempts to synthesise related mononuclear complexes containing the cis di-oxo moeity are also discussed. Chapter 4 describes the synthesis and reactivity of seven coordinate oxo and sulphidohalide derivatives of niobium and tantalum which exhibit the phenomenon of bond-stretch isomerism. Compounds prepared include Nb(O)Br(_3)(PMe(_3))(_3), Nb(S)X(_3)(PMe(_3))(_3) (X=C1, Br) and Ta(S)C1(_3)(PMe(_3))(_3). The latter three have been characterised by X-ray crystallography. Chapter 5 describes the synthesis and reactivity of half-sandwich oxo compounds of niobium and tantalum. Some of the derivatives prepared include[CpNbC1(_3)](_2)(µ(_2)-O), [CpTaC1(_3)](_2)(|µ(_2)-O) and [Cp*TaC1(_3)](_2)(µ(_2)O). The stability of [Cp*Ta(O)Cl(_2)](_2) has been investigated and the X-ray structure of the trinuclear decomposition product Cp*(_3)Ta(_3)O(_4)C1(_4) is described. Chapter 6 describes the use of alkali metal aryloxides as intercalating agents and the preparation of a series of novel intercalation compounds, of the type W(O)(_2)C1(_2)xM (M = Li, Na and K) which display the properties characteristic of tungsten bronzes. Chapter 7 gives experimental details for chapters 2 6.
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Hopwood, Jeremy D. "Barium sulphate crystallisation in synthetic and biological systems : a study of growth and form." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320476.
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Burke, Adrian Alan. "Removal of hydrogen sulfide from hot fuel gas using an electrochemical membrane system." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/11702.
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Bello, Yusuf O. "Tellurium and selenium precipitation from copper sulphate solutions." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95895.
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Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: The copper sulphate leach solutions produced during the final pressure leach stages in base metal refinery processes contain low concentrations of other precious metals (OPMs, namely Rh, Ru and Ir ) and impurities in addition to the base metals (BMs) of interest. Se and Te impurities, in particular, must be removed from the leach solution before it is fed to copper electrowinning because these species have adverse effects on electrowinning efficiency. Currently, these elements are being precipitated from the leach solution with sulphurous acid. Se precipitation is satisfactory but Te removal still proves challenging. Previous studies have shown that tellurium can either be precipitated as cuprous telluride from copper sulphate solutions by reduction with sulphurous acid alone, or by the addition of SO2 as a precipitating agent and metallic copper as an additional precipitating agent. The objective of this study was to evaluate the effects of different process variables on Te and Se recovery in order to propose operating conditions at which increased tellurium precipitation can be achieved with minimal co-precipitation of base metals of interest (notably Cu and Ni). This would also aid in the development of a better understanding of tellurium and selenium precipitation mechanisms in CuSO4-H2SO4 medium.
AFRIKKANSE OPSOMMING: Die kopersulfaat logingsoplossing wat gedurende die finale druklogingstadia in basis metaal raffinaderye produseer word bevat, behalwe vir die basis metale van belang, ook lae konsentrasies ander edelmetale (AEM, naamlik Rh, Ru, en Ir) sowel as onsuiwerhede. Se en Te onsuiwerhede, in die besonder, moet vanuit die logingsoplossing verwyder word voordat die oplossing na die koper elektrowinning gevoer word omdat hierdie spesies negatiewe effekte op die elektrowinning effektiwiteit het. Hierdie elemente word tans met swaweligsuur vanuit die logingsoplossing gepresipiteer. Se presipitasie is voldoende, maar die Te verwydering bly steeds problematies. Vorige studies het getoon dat tellurium as kuprotelluried vanuit kopersulfaat oplossings presipiteer kan word deur middel van reduksie met swaweligsuur alleen, of met die byvoeging van SO2 as presipiteermiddel en metallieke koper as addisionele presipiteermiddel. Die doelwit van hierdie studie was om die effekte van verskillende prosesveranderlikes op Te en Se presipitasie te ondersoek ten einde bedryfstoestande voor te stel wat verbeterde tellurium presipitasie toelaat met minimale kopresipitasie van basis metale van belang (hoofsaaklik Cu en Ni). Dit sal ook bydra tot die ontwikkeling van ʼn beter begrip van die tellurium en selenium presipitasie meganisme in ʼn CuSO4-H2SO4 medium.
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Chen, Ting. "Physicochemical Properties of Nickel and Cobalt Sulphate Solutions of Hydrometallurgical Relevance." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040706.144034.
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Producing nickel and cobalt metal by high pressure acid leaching (HPAL) of nickel laterites is becoming one of Australia's largest mineral processing industries. However, the background chemical information for this process, including the fundamental physicochemical properties of acidic metal sulphate leachate solutions, is not well known. In order to improve the efficiency of current and future HPAL plants, high quality physicochemical and thermodynamic data will be necessary. This thesis reports measurements on the densities and heat capacities of nickel and cobalt sulphate solutions and their mixtures along with detailed studies of the nature of the species present and the thermodynamics of their interconversions.
Densities and heat capacities of nickel and cobalt sulphate and perchlorate solutions and their ternary mixtures were measured using a vibrating tube densimeter and a flow microcalorimeter respectively. These data were used to calculate the apparent molal volumes and heat capacities of these solutions. Standard partial molal quantities were then obtained by appropriate extrapolation procedures, along with the volume and heat capacity changes of ion pair formation. A comparison has been made between experimental densities and heat capacities with those predicted by Young's rule. Good agreement was obtained except when the degree of complexation varied significantly in the mixturesThe various ion pair species in nickel and cobalt sulphate solutions, along with those of magnesium sulphate (which is a major impurity in HPAL leachates), were reinvestigated by dielectric relaxation spectroscopy.
Doubly solvent separated ion pairs, solvent shared ion pairs and contact ion pairs were shown to exist simultaneously in solution and their concentrations were determined from dilute to near-saturated concentrations. Evidence for the possible existence of a triple ion,
M2SO4 2+, was also obtained in highly concentrated solutions. The equilibrium constants of the stepwise reactions and the effective hydration numbers of ions and ion pairs were also calculated.
The heats of complexation of nickel(II) and cobalt(II) sulphate were determined at different ionic strengths in sodium perchlorate media by titration calorimetry. These data were fitted to a specific ion interaction model to obtain the standard state values. The corresponding entropies of complexation were calculated and were found to be the major contributor to the stability of the complexes.
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Fredriksson, Andreas. "Kinetics of collector in-situ adsorption on metal sulphide surfaces studied by ATR-FTIR spectroscopy." Doctoral thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26680.
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In sulphide mineral flotation, a sufficient hydrophobicity of the mineral surfaces is obtained by the adsorption of collector chemicals at the metal sulphide/aqueous interface. This surface alteration is of fundamental and applied interest. In this thesis, attenuated total reflection infrared spectroscopy has been used to monitor the adsorption kinetics and the orientation of heptyl xanthate when adsorbed onto three solid surfaces - germanium, zinc sulphide and lead sulphide in-situ. The Chemical Bath Deposition method has been used to deposit metal sulphides onto germanium internal reflection elements, and verified as capable in synthesizing metal sulphide surfaces for adsorption studies recovering information about surface reactions at metal sulphide/solution interfaces. In the study of surface reactions the substrate is of great importance, implying that the chemistry of the surface has to be well characterised. This work has utilized X-ray photoelectron spectroscopy in the characterisation of the different surfaces. The adsorption kinetics has been followed to monitor the adsorption equilibria at different concentrations. In the case of heptyl xanthate adsorbed at the zinc sulphide/aqueous interface, an adsorption isotherm has been calculated from the equilibrium data. On the assumption that the adsorption step was rate controlling a pseudo-first order equation was derived and adsorption rate data, in all the three studied systems, tested according to this equation. In addition, an orientation study of the heptyl xanthate molecule at the different interfaces was performed, which requires polarised infrared light. Density Functional calculations of a free heptyl xanthate molecule, and a heptyl xanthate molecule adsorbed on a pure Ge(111) were utilized to get more information about the in-situ adsorption of heptyl xanthate on a germanium surface. The important vibration bands were assigned to different vibrations, and the theoretical infrared spectra were compared with the experimentally analyzed spectra. This study shows the strengths of using advanced first-principle Density Functional Theory in the interpretation of real surface adsorption systems.Godkänd; 2006; 20070314 (evan)
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Armstrong, John P. "Variations in silicate and sulphide mineral chemistry between free-milling metallic and refractory invisible gold ores, Con Mine, Yellowknife, Northwest Territories." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ28472.pdf.
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Cagli, Eda. "Asymmetric Diethylzinc Addition To N-sulphonyl And N-phosphinoyl Arylaldimines." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615394/index.pdf.
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Design of new chiral ligands for asymmetric synthesis is important. The ligand should be economical and efficient in enantioselective transformations. For the synthesis of some natural products and biologically active compounds, optically active amines are used as important intermediates. For this reason, it is significant to develop new catalyst system which can produce optically active amines in an economical and efficient way. Our group developed PFAM ligands and used successfully for the enantioselective synthesis of organic compounds. In this work, these ligands were tested as chiral catalysts for enantioselective synthesis of amines. N-sulphonyl and N-phosphinoyl imines synthesized from aromatic aldehydes were used as the starting material for enantioselective diethylzinc addition reaction in the presence of copper salt and PFAM ligands. By improving the known procedure, N-benzylidine sulphonylaldimine was obtained in excellent yield (98%). Asymmetric diethylzinc addition reaction to N-sulphonyl and N-phosphinoyl aryaldimines provided chiral amines in up to 81% enantioselectivity and 99% yield.
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Misran, Misni. "Thermodynamics and kinetics of spontaneous vesicle formation and breakdown of surfactants in aqueous media : sodium 6-phenyltridecane sulphonate and fatty acids." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297474.
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Murphy, K. J. "An NMR and molecular modelling study on the solution conformation of Heparan Sulphate : new insights into the relationship between structure and function." Thesis, University of Huddersfield, 2007. http://eprints.hud.ac.uk/id/eprint/189/.
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A deeper insight into the structural biology of HS is key to understanding its nearuniversal functional role as a co-receptor for growth factors and morphogens. Due to the extreme difficulty in preparing homogeneous HS oligosaccharides for structural and functional studies, traditionally, oligosaccharides derived from the related molecule heparin are used as HS structural models. In this study a number of authentic HS derived hexasaccharides, in addition to heparin derived hexasaccharides, have been purified in sufficient quantity to permit a detailed NMR and molecular modelling based analysis of their three dimensional structure. The primary sequence of one HS derived oligosaccharide has never previously been published. Studies on all oligosaccharides and their chemically de-2-O-sulphated derivatives have revealed additional new insights into the structural influence of sulphate groups. Consistent with previous studies, at the monosaccharide level, sulphation was found to influence iduronate conformational behaviour. However, with the data presented, a number of gaps in the literature have now been filled, and it is now possible for the first time to predict the balance of iduronate conformational equilibria within any HS monosaccharide sequence. Sulphation was also found to influence the overall topology of the oligosaccharide chains themselves. In particular, for the first time NMR data is presented to show that local deviations may occur along the helical axis of each oligosaccharide when it is free in solution. Polyacrylamide gel electrophoresis data and molecular dynamic modelling data are presented to suggest that the rate at which local deviations occur may be influenced by the sulphation pattern contained within a particular oligosaccharide. The functional implications of these and other new structural insights are discussed, and in particular are related to a library of HS derived decasaccharide structures previously tested for biological activity
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Edwards, Andrew R. "Protected sulphonate nanoparticles, thiol-Michael functionalisation of nanogel decorated nanoparticles, and thiol-Michael microcapsules for agricultural mobility and adhesion applications." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/79684/.
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Targeted delivery of an active ingredient to plant systems required extensive studies in areas of soil mobility, plant root adhesion and encapsulation. To accomplish the aims of mobility and adhesion to roots, specific surface charges and colloidal forces are required. These charges are required to provide sufficient repulsive forces preventing adhesion to soil and attractive forces allowing adhesion to roots. To accomplish the aims of synthesising colloids for mobility, adhesion and also encapsulation we formed a specific strategy. We aimed to increase the anionic surface charge on colloidal nanoparticles as a means to aid mobility studies of colloids through soil by providing increased repulsive forces to prevent adhesion to both air interfaces and soil. We also designed a way to decorate colloidal nanoparticles with microgel particles thus forming a soft adhesive surface layer with which further functionality could be incorporated i.e. surface charges. Finally we designed a simple methodology for the encapsulation of oil with post functionalisation in mind. We synthesised colloidal nanoparticles, less than 200 nm, using soap-free emulsion polymerisation of styrene where up to 50 wt% of protected ethyl styrene sulphonate monomer was incorporated. The nanoparticles were hydrolysed to release the sulphonic charge using thermolysis in an autoclave. Soap-free emulsion polymerisation was used to synthesise raspberry-like and core-shell morphology decorated nanoparticles by the adhesion of crosslinked nanogel particles to a range of hydrophobic and hydrophilic seeds. Poly(acrylic) and poly(styrenic) seeds were synthesised with a range of hydrophobicities whereby more decoration of nanogel particles was achieved for hydrophilic seeds. The nanogel decoration was studied using di-, tri- and multi-functional acrylates and the morphologies changed from raspberry-like to core-shell as the functionality of the crosslinker increased. The presence of Vinyl functional groups was proved using Raman microscopy. Post functionalisation with different thiols was carried out using nucleophilic thiol-Michael addition chemistry and a loss of vinyl groups was shown. Encapsulation of aromatic oil was carried out using an interfacial thiol-Michael addition reaction between a tetra- functional thiol and a penta-/hexa- functional ene using an amine nucleophilic catalyst. A microfluidic device was used to control the capsule sizes and dispersity and light microscopy was used to study capsule sizes and dry-down properties. No rupture was observed for the millimetre and microcapsules produced but unfortunately size scale-down could not be accomplished for the current system using high shear homogenisation. In conclusion we increased the loading of sulphonate charge for colloidal poly(styrene) nanoparticles and we successfully increased the surface area of styrenic and acrylic seed nanoparticles using nanogel particle adhesion. We post functionalised decorated nanoparticles using thiol-Michael addition reactions and synthesised capsules using thiol-Michael addition reactions confined in a microfluidic device.
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Pilkington, Melanie. "An exploration of the uses of cyclic sulphamidates and cyclic sulphate esters in organic synthesis, and an investigation of attractive molecular interactions by x-ray crystallography." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282483.
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Avenius, Joel. "Sänkta sjöars inverkan på ytvatten i Västerbottens kustland : Samband mellan sänkningsnivåer och vattenkemi i sjöar på sulfidrika sedimentjordar." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-62140.
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Lake lowering in sulphide-rich areas is currently a major environmental impact for surface water. This study focuses on whether there is a relationship between a gradient of lake lowering and surface water impacts in areas of sulphide-rich sediments, in order to better understand their contribution of heavy metals and sulfuric acid. Also, is it a reasonable method to use the reduced lake area in order to quantify the gradient? The survey was conducted by collecting water samples from reference lakes and lowered lakes from south to north in coastal areas within the county of Västerbotten. Water samples were then analyzed for TOC, pH, conductivity, anions, base cations, alkalinity, acidity, sulfate, Al, Cd, Fe, Mn, Cu, Zn and Pb. These parameters were then compared statistically using regression analysis and t-tests. The results show that no gradient was discernible in response to the reduced lake area. However, significant differences (p < 0,05) between the reference lakes and all the reduced lakes were visible for pH, conductivity, Cd, Cu, Zn and Al. The study shows that there is a correlation between lake lowering and negative impacts on surface water. However, to calculate a gradient from the reduced lake area is deficient as it is limited by the lakes volume reduction, and how the area around the lake has been affected. Further studies on the subject are therefore necessary.FLISIK (för livskraftiga småvatten i kvarkenregionen)
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Mulwanda, James. "Recovery of dissolved platinum group metals from a pregnant copper sulphate leach solution by precipitation." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86538.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: In Base Metal Refineries (BMRs), the copper sulphate leach solution produced during the final pressure leaching stage contains impurities such as selenium and tellurium, as well as other precious metals (OPMs, namely Rh, Ru, and Ir). Se and Te are removed by precipitation with sulphur dioxide prior to electrowinning of Cu. While a small percentage of the dissolved OPMs precipitate with the Se and Te, the largest portion remains in solution and is recycled to the first stage leach. If a larger portion of the OPMs in solution can be recovered in the Se/Te precipitation stage, OPM losses and the OPM inventory of the plant can be reduced. The aim of this project was to determine operating conditions that would allow maximum OPM recovery with minimal Cu and Ni co-precipitation in the Se/Te removal section of a BMR. The effects that the operating temperature, pressure, stirring rate, reagent type, and reagent quantity have on the metal precipitation behavior and precipitate characteristics were determined experimentally. Thio-urea and sulphurous acid were evaluated as precipitation reagents for temperatures of 80°C and 160°C, stirring rates of 250 rpm and 500 rpm, and pressures equal to ambient pressure and 7 bar. 200 % and 320 % excess thio-urea and 720 % and 960 % excess sulphur dioxide were used. The precipitation of OPMs with sulphur dioxide was generally poor; the maximum percentage Rh, Ru, and Ir precipitated were 35 %, 18 %, and 20 %, respectively. It was, however, found that the OPM precipitation increased as the reagent amount was increased. Increasing the temperature further increased Rh and Ir precipitation but affected the Ru precipitation negatively. Thio-urea precipitated virtually all of the Rh contained in the solution irrespective of the values of the process variables studied. As was the case with sulphur dioxide, increasing the amount of thio-urea added resulted in increased Ru and Ir precipitation, while higher temperatures favored Ir precipitation but not Ru precipitation. The maximum percentage Ru and Ir precipitation achieved with thio-urea were 87 % and 60 %, respectively. Complete Se precipitation was observed at all process conditions, while Te precipitation increased as the operating temperature and the reagent quantity were increased. Maximum Te precipitation of 98 % and 90 % were achieved when using 320 % excess thio-urea and 960 % sulphurous acid quantities, respectively, at 160°C and a stirring rate of 250 rpm. Increasing the reagent quantity and temperature did, however, also result in increased copper and nickel precipitation. The statistical analysis of the results allowed regression models to be fitted to predict the percentage metal precipitation as a function of the investigated process variables. These models were used to define an objective function to determine the optimal operating conditions. A temperature of 80oC, a pressure of 7 bar, and 200 % excess thio-urea were proposed as the optimum operating conditions that would yield 98 % Rh, 75 % Ru, and 48 % Ir precipitation with less than 5 % Cu and Ni co-precipitation. Experimental validation tests confirmed the model predicted values and proved repeatability of the experimental data.
AFRIKAANSE OPSOMMING: Die kopersulfaat logingsoplossing wat tydens die finale drukloging stadium in Basis Metaal Raffinaderye (BMRe) produseer word, bevat onsuiwerhede soos selenium en tellurium sowel as ander edelmetale (AEMe, naamlik Rh, Ru, en Ir). Se en Te word voor Cu elektrowinning verwyder deur middel van presipitasie met swaweldioksied. Alhoewel ʼn klein persentasie van die opgeloste AEMe saam met die Se en Te presipiteer, bly die grootste gedeelte in oplossing en word gevolglik na die eerste loging stadium hersirkuleer. AEM verliese en die AEM inventaris van die aanleg kan verminder word indien ʼn groter gedeelte van die AEMe in die Se/Te presipitasie stadium herwin kan word. Die doel van hierdie projek was om bedryfstoestande te bepaal om maksimum AEM herwinning met minimale Cu en Ni kopresipitasie in die Se/Te verwyderingseksie van ʼn BMR te behaal. Die effekte wat bedryfstoestande soos temperatuur, druk, roerder tempo, tipe reagens, en hoeveelheid reagens op die metaal presipitasiegedrag en presipitaat eienskappe het, is eksperimenteel bepaal. Tio-ureum en swaweligsuur is evalueer as presipitasie reagense vir temperature van 80°C en 160°C, roerder tempo’s van 250 rpm en 500 rpm, en drukke gelyk aan omgewingsdruk en 7 bar. 200 % en 320 % oormaat tio-ureum en 720 % en 960 % oormaat swaweldioksied is gebruik. Die presipitasie van AEMe met swaweldioksied was swak in die algemeen; die maksimum persentasie Rh, Ru, en Ir presipitasie wat behaal is, is 35 %, 18 %, en 20 %, onderskeidelik. Daar is egter gevind dat die AEM presipitasie toeneem indien die hoeveelheid reagens toeneem. ʼn Toename in die temperatuur het verder tot ʼn toename in Rh en Ir presipitasie gelei, maar dit het Ru presipitasie negatief affekteer. Tio-ureum het basies al die Rh in oplossing laat presipiteer, ongeag die waardes van die ander prosesveranderlikes wat ondersoek is. Soos wat die geval vir swaweldioksied was, het ʼn toename in die hoeveelheid tio-ureum ʼn toename in die Ru en Ir presipitasie tot gevolg gehad, terwyl hoër temperature Ir presipitasie bevoordeel en Ru presipitasie benadeel het. Die maksimum persentasie Ru en Ir presipitasie wat met tio-ureum behaal is, is 87 % en 60 %, onderskeidelik. Volledige Se presipitasie is by alle proses toestande waargeneem, terwyl Te presipitasie toegeneem het soos wat die temperatuur en die hoeveelheid reagens toegeneem het. Maksimum Te presipitasie van 98 % en 90 % is behaal toe 320 % oormaat tio-ureum en 960 % oormaat swaweligsuur, onderskeidelik, by 160°C en ʼn roerder tempo van 250 rpm gebruik is. ʼn Toename in die hoeveelheid reagens en die temperatuur het egter ook meer koper en nikkel presipitasie tot gevolg gehad. Die statistiese analise van die resultate het dit moontlik gemaak om regressie modelle te pas om die persentasie metaal presipitasie as ʼn funksie van die ondersoekte veranderlikes te voorspel. Hierdie modelle is gebruik om ʼn doelfunksie te definieer ten einde die optimale bedryfstoestande te bepaal. ʼn Temperatuur van 80°C, ʼn druk van 7 bar, en 200 % oormaat tioureum is voorgestel as die optimale bedryfstoestande wat 98 % Rh, 75 % Ru, en 48 % Ir presipitasie met minder as 5 % Cu en Ni kopresipitasie tot gevolg sal hê. Eksperimentele geldigheidsbepalingtoetse het die waardes wat deur die modelle voorspel is bevestig en die herhaalbaarheid van die eksperimentele data bewys.
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Rashamuse, Konanani Justice. "The bioaccumulation of platinum (IV) from aqueous solution using sulphate reducing bacteria: role of a hydrogenase enzyme." Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1004063.
Full textAbstract:
The enzymatic reduction of a high-valence form of metals to a low-valence reduced form has been proposed as a strategy to treat water contaminated with a range of metals and radionuclides. Metal reduction by sulphate reducing bacteria (SRB) is carried out either chemically (involving reduction by hydrogen sulphide) or enzymatically (involving redox enzymes such as the hydrogenases). While reduction of metal ions by hydrogen sulphide is well known, the enzymatic mechanism for metal reduction is poorly understood. The aims of this study were to investigate the role of SRB in facilitating platinum removal, and to investigate the role of a hydrogenase in platinum reduction in vitro. In order to avoid precipitation of platinum as platinum sulphide, a resting (non-growing) mixed SRB culture was used. The maximum initial concentration of platinum (IV), which SRB can effectively remove from solution was shown to be 50 mg.l⁻¹. Electron donor studies showed high platinum (IV) uptake in the presence of hydrogen, suggesting that platinum (IV) uptake from solution by SRB requires careful optimization with respect to the correct electron donor. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis indicated that platinum was being precipitated in the periplasm, a major area of hydrogenase activity in SRB. Purification of the hydrogenase by ammonium sulphate precipitation (65%), Toyopearl-Super Q 650S ion exchange and Sephacry 1 S-100 size exclusion chromatography revealed that the hydrogenase was monomeric with a molecular weight of 58 KDa, when analyzed by 12% SDS-PAGE. The purified hydrogenase showed optimal temperature and pH at 35°C and 7.5 respectively, and a poor thermal stability. In vitro investigation of platinum reduction by purified hydrogenase from mixed SRB culture showed that hydrogenase reduces platinum only in the presence of hydrogen. Major platinum (IV) reduction was observed when hydrogenase was incubated with cytochrome C₃ (physiological electron carrier in vivo) under hydrogen. The same observations were also noted with industrial effluent. Collectively these findings suggest that in vitro platinum reduction is mediated by hydrogenase with a concerted action of cytochrome C₃ required to shuttle the electron from hydrogenase.