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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Formation of nanocoatings by laser-assisted spray pyrolysis and laser ablation on 2d gold nanotemplates

Dedigamuwa, Gayan S 01 June 2005 (has links)
This thesis describes a new Laser-Assisted Spray Pyrolysis technique developed to grow nanoparticle coatings with controllable particle sizes. In this method, droplets of a precursor formed by a nebulizer are injected into a growth chamber using SF6 carrier gas. An experimental study and a computational model to investigate the particle size dependence on various growth parameters have been carried out. The results show that heating of 1.5and#61549;m droplets of metalorganic precursor in a carrier gas using a CO2 laser resulted in the formation of TiC and Fe3O4 particles with diameters in the range of 50-60nm. Also the results show that by reducing the concentration of the metal organic precursor the diameter of the deposited particles can be reduced.
42

Casting Identities in Central Seclusion : Aspects of non-ferrous metalworking and society on Gotland in the Early Medieval Period

Gustafsson, Ny Björn January 2013 (has links)
The aim of this thesis has been to investigate and interpret late Iron Ageand Early Medieval traces of non-ferrous metalworking on the islandGotland, Sweden. Gotland was not, based on the archaeological record, anintegrated part of the common Scandinavian culture. Instead a local,endemic cultural expression had developed; a seclusion which lasted forcenturies despite the islands central position in the Baltic Sea. In thepast, key elements for the understanding of local settlement- and burialpractices as well as the local material culture were mainly recovered andreported by local farmers. A specific category of such finds – so-called‘bronze slag’ is discussed and partly reinterpreted in the first study ofthis thesis. Two further studies treat different aspects of metalworkingand metalworkers – one discusses common archaeological notions ofScandinavian workshops, production sites and metalworkers from a criticalperspective while the other mainly focuses on the Gotlandic finds frommetal-detector surveys carried out over the last 35 years. Based on whereand to which extent, both from a quantitative and a qualitative point ofview, these finds occur a hierarchical classification into four sub groupsis presented – ordinary farm sites with traces of non-ferrous metalworking,workshop sites, potential workshop sites and last, extrovert harboursettlements. A fourth study presents an attempt to evaluate the usefulnessof magnetometry in delimiting extant traces of high-temperature crafts,such as metalworking. The last study of the thesis presents an attempt touse trace elements analysis of skeletal lead in human bone to identifypotential non-ferrous metalworkers. As the wearing of endemic Gotlandic jewellery appears to have been centralin the manifestation of the local identity it is argued that themetalworking artisans played a crucial role in defining how this identitywas signalled and displayed via the jewellery and dress-related metalobjects. It is further suggested that these artisans might have played animportant role in upholding the local economy before the advent of localminting. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.</p>
43

Metal oxide-facilitated oxidation of antibacterial agents

Zhang, Huichun. January 2004 (has links) (PDF)
Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2005. Directed by Ching-Hua Huang. / Wine, Paul, Committee Member ; Pavlostathis, Spyros, Committee Member ; Mulholland, James, Committee Member ; Yiacoumi, Sotira, Committee Member ; Huang, Ching-Hua, Committee Chair. Includes bibliographical references.
44

Procédé de recuits sous champ magnétique intense pour microstructures optimisées / High magnetic field processing for soft magnetic properties improvement in FeCo and FeNi alloys

Frincu, Bianca 28 September 2012 (has links)
Actuellement le prix de l'énergie augmente continuellement. Ainsi, un des grands défis de la société est de limiter au maximum la consommation énergétique. La mise en oeuvre de matériaux pour l’énergie et le développement de leurs propriétés est au coeur de cette problématique.Dans cette optique, ce travail est dédié à l’évaluation d’un nouveau procédé de fabrication thermomagnétique dans le but de développer de nouvelles microstructures et/ou des propriétés améliorées inaccessibles par des traitements thermomécaniques classiques. L’objectif principal est d'étudier l'effet du champ magnétique sur deux principaux alliages, Fe-Co et Fe-Ni en vue d'améliorer leurs propriétés magnétiques douces.Dans les alliages Fe-Co, les températures de transformation de la ferrite vers l’austénite, mesurées jusqu’à16T, sont augmentées par l'application d'un champ magnétique intense. Ce décalage est modélisé en fonction du champ, en se basant sur une analyse thermodynamique. Dans les deux alliages, la phase ferritique eststabilisée par le champ intense à plus haute température ce qui permet le développement d’une microstructure àgros grains. Les propriétés magnétiques douces sont également améliorées par l'application d'un champ magnétique à la fois dans l’alliage Fe-Co27% et dans Fe-Co49%V2% en induisant respectivement le développement d’une texture Goss dans le premier alliage et une forte anisotropie induite dans le second.Dans les alliages Fe - Ni contenant 80% l'utilisation d’un champ magnétique intense pendant le traitement thermique (jusqu'à 7 T) permet d’améliorer le développement de l'anisotropie induite, permettant de« coucher » la forme du cycle d'hystérésis. Le comportement magnétique dynamique du matériau est ainsiamélioré par le champ magnétique.Ces résultats significatifs soutiennent l'idée que l'introduction du champ magnétique dans les techniques defabrication des matériaux conventionnels est une piste prometteuse pour améliorer d’avantage leurs propriétésfonctionnelles. / Energy is becoming increasingly expensive and a major challenge for the society is to minimize energyconsumption. One of the issues of this challenge focuses on the industrial processing of energy related materialand the development of their properties.The overall objective of this work is to evaluate thermo-magnetic processing as a new technology with thegoal of developing novel microstructures and/or improved properties unattainable through conventionalthermo-mechanical processing. This main target is addressed with the study of the effect of magnetic field ontwo main alloys, Fe-Co and Fe-Ni in view of improving their functional soft magnetic properties.In FeCo alloys the non – equilibrium ferrite to austenite phase transformation measured up to 16T is foundto be increased by the application of a high magnetic field. Its evolution with the field intensity is explainedusing a thermodynamic analysis. In both grades, the ferrite phase is found to be stabilized at higher temperaturetogether with a coarse grains microstructure during recrystallization and growth in high field. Soft magneticproperties are also improved by the application of a magnetic field both in the Fe-Co27% and Fe-Co49%-V2%alloys by a field induced Goss texture enhancement and an extended field induced anisotropy respectively.In the Fe – 80%Ni composition the use of high magnetic field during processing (up to 7T) is found toimprove the magnetic induced anisotropy and to tailor the hysteresis loop shape. The dynamic magneticbehavior is greatly improved by high field annealing.These significant results support the idea that introducing the magnetic field application into conventionalmaterials processing is a promising way to improve material properties.
45

On the Factors Influencing the Stability of Phases in the Multiferroic System BiFeO3-PbTiO3

Kothai, V January 2015 (has links) (PDF)
Rhombohedral perovskite BiFeO3 is a single phase multiferroic compound exhibiting both magnetic (Neel temperature ~370˚C) and ferroelectric (Curie point ~840˚C) ordering well above the room temperature. Ferroelectricity in BiFeO3 is due to stereochemically active 6slone pair in Biion which causes large relative displacements of Bi and O ions along the [111] direction. Long range spiral modulation of the canted antiferromagnetic spin arrangement in Feeffectively cancels the macroscopic magnetization due to Dzyaloshinskii–Moriya interaction and thereby prevents linear magneto-electric effect. Synthesizing dense pure BiFeO3 by conventional solid state method is difficult due to the formation of thermodynamically stable secondary phases such as Bi2Fe4O9, Bi25FeO39 and Bi46Fe2O72. To stabilize the perovskite phase and to suppress the cycloid several groups have adopted different strategies such as thin film growth, different synthesis methods and chemical substitution. Of the various substitutions reported in the literature, PbTiO3 substitution has shown very interesting features, such as (i) unusually large tetragonality (c/a~1.19), (ii) formation of morphotropic phase boundary (MPB) and (iii) high curie point Tc~650C. MPB ferroelectric systems such as lead zirconate titanate (PZT) are known to exhibit high piezoelectric response due to the coupling between strain and polarization. Hence the existence of magnetic ordering in BiFeO3-PbTiO3 offers an interesting scenario where polarization, strain and magnetization may couple together. The high Curie point also makes the system an interesting candidate for high temperature piezoelectric application. However its potential as a high temperature piezoelectric material has not been realized yet. A detailed review of literature suggests a lack of clear agreement with regards to the composition range of the reported MPB itself. Different research groups have reported different composition range of MPB for this system even for almost similar synthesis conditions. The present thesis deals with broadly two parts, firstly with the preparation of pure BiFeO3 by co-precipitation and hydrothermal methods and its thermal stability and secondly resolving the cause of discrepancy in range of MPB reported in BiFeO3-PbTiO3 solid solution. Detailed examination of this system (BiFeO3-PbTiO3) around the reported MPB composition by temperature dependent X-ray, electron and neutron diffraction techniques, in conjunction with a systematic correlation of sintering temperature and time with microstructural and phase formation behavior revealed the fact that the formation of MPB or the single ferroelectric phase is critically dependent on the grain size. This phenomenon is also intimately related to the abnormal grain growth in this system. Chapter 1 gives the brief overview of the literature on the topics relevant to the present study. The literature survey starts with a brief introduction about the perovskite oxides; their ferroelectric, magnetic and multiferroic properties were discussed in further sections. A brief outline on the grain growth mechanism is described. An overview of BiFeO3 and various synthesis methods, different chemical substitutions and their effect on properties are provided. A brief review of published literature on BiFeO3-PbTiO3 solid solution and its properties is also presented. Chapter 2 deals with the synthesis of pure BiFeO3, heat treatment and characterisation. BiFeO3 was synthesised by (a) co-precipitation and (b) hydrothermal methods. In co-precipitation method, calcination of precipitate at different temperature resulted in the formation of BiFeO3 along with secondary phases (Bi2Fe4O9 and Bi24FeO39). The optimum calcination temperature to prepare pure BiFeO3 was found to be 560C. The synthesized pure BiFeO3 exhibits weak ferromagnetic hysteresis at room temperature, the degree of which increases slightly at 10K (-263C). The hydrothermal treatment was carried out in (a) carbonate and (b) hydroxide precipitates with KOH as mineralizer. BiFeO3 prepared using hydroxide precipitate was stable till 800C whereas with carbonate precipitate it was stable only till 600C. Chapter 3 deals with the stability of phases in (1-x)BiFeO3 -(x)PbTiO3 solid solution. Samples prepared by conventional solid state route sometimes remain as dense pellet and on certain occasions it disintegrate completely into powder observed after sintering. Irrespective of the composition, sintering time and temperature, powder X-ray Diffraction (XRD) pattern of the survived pellet (crushed into powder) shows coexistence of rhombohedral (R3c) and tetragonal (P4mm) phases and the disintegrated powder (without crushing) show 100% tetragonal (P4mm) phase. Very high spontaneous tetragonal strain (c/a-1) ~0.19 at MPB is believed to be the origin for disintegration. But in all the survived pellets at least a minor fraction of rhombohedral phase (5-7%) is present. Systematic sintering studies with the time and temperature shows, decreasing the sintering temperature and time will increase the lifetime of the pellet and by increasing the sintering temperature and time the pellet will disintegrate. In this work we have conclusively proved that the wide composition range of MPB reported in the literature is due to kinetic arrest of the metastable rhombohedral phase and that if sufficient temperature and time is given, the metastable phase disappears. The suppression/formation of minor rhombohedral phase is expected due to the play of local kinetic factors during the transformation process. This makes the system behave in an unpredictable way with regard to the fraction of rhombohedral phase that is observed at room temperature. A systematic X-ray and neutron powder diffraction study of the giant tetragonality multiferroic (1-x)BiFeO3 -(x)PbTiO3 have shown that the compositions close to the morphotropic phase boundary of this system present two different structural phase transition scenarios on cooling from the cubic phase: (i) Pm3m P4mm(T2)+P4mm(T1) P4mm (T1) and (ii) Pm3m P4mm(T2) + P4mm(T1) + R3c P4mm (T1) + R3c. The comparatively larger tetragonality of the T1 phase as compared to the coexisting isostructural T2 phase is shown to be a result of significantly greater degree of overlap of the Pb/Bi-6s and Ti/Fe-3d with the O-2p orbitals as compared to that in the T2 phase. High temperature electron diffraction studies show that the metastable rhombohedral phase is present in the cubic matrix well above the Curie point as nuclei. Life time of the metastable R3c nuclei is very sensitive to composition and temperature, and nearly diverges at x → 0.27. MPB like state appears only if the system is cooled before the metastable R3c nuclei could vanish. Issue of the metastable rhombohedral state is developed further in Chapter 4. A one-to-one correlation was found between the grain size and phase formation behavior. Fine grained (~1µm) microstructure (usually pellets) shows phase coexistence (R3c+P4mm) and the disintegrated coarse grains (~10µm) show tetragonal (P4mm) phase. Microstructural analysis revealed the disintegration was caused by abnormal grain growth along with the disappearance of metastable rhombohedral phase. Abnormal grain growth starts at the periphery/crack i.e., at the free surface and move towards the canter of the pellet. Size reduction of disintegrated coarse grains (~10µm) to fine grains (~1µm) by crushing the sample showed that the system switching form pure tetragonal (P4mm) state to the MPB state comprising of tetragonal and rhombohedral phases (R3c+P4mm). In another approach the smaller sized particles of x=0.20 were synthesized by sol gel method. It was reported that in conventional solid state route x=0.20 exhibits pure rhombohedral phase. The sol-gel sample calcined at 500C (particle size ~15nm) stabilizes tetragonal metastable phase along with the stable rhombohedral phase, the morphotropic phase boundary state. Samples calcined at higher temperature, 800C (particle size ~50nm) also showed stable rhombohedral phase. Ferromagnetic behavior was observed in the sample having phase coexistence and the sample with pure rhombohedral phase showed antiferromagnetic behavior. Hence this material is a promising candidate which can be tuned to exhibit different behavior just by adopting different grain size. Chapter 5 deals with the magnetic structure of (1-x)BiFeO3 -xPbTiO3 solid solution with change in composition and temperature. Magnetic structure was studied using powder neutron diffraction in the composition range x=0.05 -0.35. Rietveld analysis was carried out for the nuclear and magnetic phases, by considering R3c phase for the nuclear structure. To account for the magnetic Bragg peak at d=4.59Å, three antiferromagnetic models were considered for the magnetic structure: (i) helical spin arrangement as in BiFeO3, (ii) commensurate G-type antiferromagnetic ordering with moments in the a-b plane (of the hexagonal cell), and (iii) commensurate G-type ordering with moments parallel to the c-axis (of the hexagonal cell). The third model was found to be suitable to explain the magnetic peak accurately and the better fitting of magnetic peak was observed in this model compared to others. At room temperature the MPB compositions have rhombohedral and tetragonal nuclear phases along with the rhombohedral magnetic phase. Addition of PbTiO3 in BiFeO3 not only changes the magnetic structure but also reduces the magnetic moment due to the substitution of Ti in Fesite. High temperature neutron diffraction studies reveal the magnetic transition at ~300C for x=0.20, ~95C for x=0.27 and ~150C for x=0.35. The Neel temperature observed in neutron diffraction studies were also confirmed by DSC and by temperature dependent dielectric studies. For x=0.20, anomalous variation in the lattice parameters and the octahedral tilt angle was observed across the magnetic transition temperature. In the magnetic phase, the c-parameter was contracted and the octahedral tilt angle slightly increased. This result suggests a coupling between spin, lattice and structural degrees of freedom around the transition temperature. Temperature dependent powder neutron diffraction study at low temperature from 300K (27C) to 4K (-269C) in x=0.35 shows the evolution of tetragonal magnetic phase at 200K (-73C) whose intensity is increasing with decrease in temperature. Below 200K, x=0.35 has rhombohedral and tetragonal magnetic and nuclear phases. While in x=0.27 at low temperature, rhombohedral magnetic and nuclear phases are present along with the tetragonal nuclear phase alone (the tetragonal magnetic phase is absent). We propose this discrepancy in the Neel temperature and the magnetic phase formation can be due to the probabilistic nature of the existence of metastable rhombohedral phase which was discussed earlier.
46

Desenvolvimento e validação de métodos analíticos para determinação de ferro (II) em preparações farmacêuticas de ferro bisglicinado / Development and validation of analytical methods for determination of Fe(II) in ferrous bisglycinate pharmaceutical preparations

Ceni, Danieli Cátia January 2009 (has links)
Ferro bisglicinado (Fe-bis-gli) é um aminoácido quelado, formado pela ligação de duas moléculas de glicina a uma molécula de ferro (II), utilizado para prevenção e tratamento da anemia ferropriva. Não há descrição de métodos analíticos em códigos oficiais para o controle de qualidade do ferro bisglicinado em formas farmacêuticas. É comercializado na forma de cápsulas, produzidas por farmácias magistrais e em forma oral líquida. Deste modo, o objetivo deste trabalho foi a validação de métodos analíticos para o controle qualitativo e quantitativo do Febis- gli em cápsulas e forma oral líquida. A identificação e caracterização do fármaco foram realizadas através da determinação dos caracteres físicos, solubilidade, aquametria, espectrofotometria na região do infravermelho (IV), reações específicas e espectroscopia de Mössbauer. Para a determinação quantitativa foram validados métodos de espectrofotometria na região do visível (VIS), ordem-zero e primeira derivada (VIS-D¹), e cromatografia líquida de alta eficiência (CLAE). A análise estatística demonstrou equivalência entre os métodos CLAE / VIS para a determinação do teor das cápsulas e entre os métodos CLAE / VIS-D¹ para a determinação do Fe-bis-gli na forma oral líquida. / Ferrous bisglicycinate (Fe-bis-gli) is an amino acid chelate which is formed by the binding of two molecules of glycine to one molecule of Fe(II), used for prevention and treatment of iron deficiency. There are no analytical methods in official codes for the quality control of Fe-bis-gli in pharmaceutical forms; however it is marketed in the form of capsules , produced by compounding pharmacies and as oral liquid form. The aim of this work was the validation of analytical methods for the qualitative and quantitative analysis of Fe-bis-gli capsules and oral liquid form. The identification and characterization of the drug were performed through the determination of physical characteristics, solubility, water, infrared (IR), specific reactions and Mössbauer spectroscopy. For the quantitative determination VIS spectrophotometry methods have been validated, zero-order and first derivative (VIS-D¹) and high performance liquid chromatography (HPLC). Statistical analysis showed that HPLC / VIS methods were equivalent to assay capsules and HPLC / VIS-D¹ methods were equivalent to assay Fe-bis-gli in oral liquid form.
47

Produção de sulfato ferroso a partir de rejeitos de carvão

Vigânico, Eunice Maria January 2009 (has links)
A mineração de carvão gera grandes volumes de rejeitos que podem ser responsáveis por graves danos ambientais. A oxidação da pirita (FeS2), na presença de ar e água, promove a formação da drenagem ácida de mina (DAM), uma solução aquosa fortemente ácida e rica em sulfato e ferro (nas formas Fe²+ e Fe³+), além de outros metais associados. Atualmente, poucos estudos têm considerado a possibilidade da produção de materiais de valor econômico agregado a partir da água de percolação em rejeitos de carvão. Neste trabalho, o objetivo foi o desenvolvimento de uma rota hidrometalúrgica para a produção de sulfato ferroso (FeSO4). O trabalho experimental consistiu inicialmente na coleta de amostra de rejeitos de carvão rico em pirita e a sua caracterização. Realizou-se, em laboratório, a lixiviação do material em colunas de percolação em ambiente oxidante, adequado para proporcionar a oxidação da pirita em meio aquoso. A recirculação da lixívia permitiu a obtenção de um extrato rico em ferro. A seguir, procedeu-se a conversão do Fe³+ em Fe²+ para obtenção do sulfato ferroso, utilizandose radiação ultravioleta. O lixiviado, rico em Fe+², foi evaporado para cristalização do sulfato ferroso e purificado com álcool etílico. Os cristais foram caracterizados por análise química elementar, difração de raios X e microscopia eletrônica de varredura. A recuperação de Fe na forma melanterita (FeSO4.7H2O) em relação ao Fe pirítico existente na coluna (0,30 kg de Fe pirítico por kg de rejeito de carvão) variou de 7,5 a 9,0 %. Os resultados demonstraram que é possível produzir sulfato ferroso n-hidratado tendo como matéria-prima o rejeito rico em pirita resultante da mineração de carvão mineral. / The coal mining generates large volumes of tailings that may be responsible for serious environmental damages. The oxidation of pyrite (FeS2), in the presence of air and water, promotes the formation of acid mine drainage (AMD), an aqueous and highly acid solution rich in sulfate and iron (in the form Fe³+ and Fe²+), along with other associated metals. Currently, few studies have considered the possibility of production of materials with agregated economic value from the percolation of water in coal mining tailings. In this study, the objective was the development of a hydrometallurgical route for its production. The experimental work consisted initially in the collection of samples of coal waste rich in pyrite and its characterization. In the laboratory was performed the leaching of the material in percolation collums in an oxidizing environment, appropriate to provide the pyrite oxidation in aqueous medium. The recirculation of liquor allowed to obtain an extract rich in the iron. Then, the conversion of Fe³+ to Fe²+ for obtaining ferrous sulfate was performed using ultraviolet irradiation. The leached liquor, rich in Fe+², was evaporated for ferrous sulphate crystallization and purified with ethanol. The ferrous sulphate crystals were characterized by x ray diffraction and scanning electron microscopy. The recovery of Fe in the form melanterite (FeSO4.7H2O ) on pyrite Fe existing in the column (0,30 kg of Fe per kg of pyrite tailings and coal) ranged from 7,5 to 9,0 %. The results demonstrated that it is possible to produce nhydrated iron sulfate having as a raw material the waste rich in pyrite produced from the coal mining.
48

Protótipo em escala piloto para produção de sulfato ferroso a partir de concentrado de pirita da mineração de carvão

Vigânico, Eunice Maria January 2014 (has links)
O presente trabalho teve como objetivo desenvolver um protótipo para a produção hidrometalúrgica de sulfato ferroso heptahidratado (FeSO4.7H2O – melanterita). A matéria prima foi um concentrado de pirita obtido a partir de rejeitos do beneficiamento de carvão mineral. Construiu-se, em escala piloto, uma planta de lixiviação com 300 kg de um concentrado com 73,2% de pirita. Nesta unidade, realizou-se uma etapa de lixiviação com água, em circuito fechado, sob condições aeróbias, com o intuito de se obter um extrato aquoso rico em íons férrico e sulfato. A seguir, procederam-se mudanças no sistema de forma a estabelecer uma condição anaeróbia ao meio, transformando os íons férricos em ferrosos. O lixiviado, rico em Fe2+, foi precipitado na forma de sulfato ferroso heptahidratado pela adição de etanol. Esse precipitado foi submetido a uma etapa de recristalização, obtendo-se cristais de melanterita de maior pureza. Ambos os produtos foram caracterizado por análise química elementar e difração de raios X. Os cristais de melanterita recristalizados apresentaram alta pureza, com qualidade para uso químico e farmacêutico. Assim, desenvolveu-se uma nova rota para produção de sulfato ferroso tendo como matéria-prima um concentrado de pirita da mineração de carvão (usualmente o sulfato ferroso é produzido como coproduto da produção de ilmenita e aço). A tecnologia apresenta uma elevada conversão do ferro lixiviado em melanterita e os insumos necessários são pirita, água e álcool etílico. A proposta abre uma nova possibilidade de uso dos rejeitos de carvão e a possibilidade de comercialização de outro produto na cadeia produtiva de carvão mineral. / The aim of this work was to develop a prototype for hydrometallurgical production of ferrous sulfate heptahydrate crystals (FeSO4.7H2O – melanterite). The raw material was a pyrite concentrate obtained from a coal tailing. The leaching system was assembled in pilot scale with 300 kg of a concentrate with 73.2% pyrite. Initially, it was carried out a leaching step in aerobic conditions with the purpose to obtain an aqueous solution rich in ferric ions and sulfate. Next, modifications were proceeded to establish an anaerobic condition in the reactor, converting the ferric to ferrous ions. Ethanol was added to the leaching solution to provide the precipitation of the Fe2+ and sulfate as ferrous sulfate heptahydrate. The ferrous sulfate precipitate was recrystallized, allowing producing melanterite crystals of higher purity. The crystals were characterized in terms of chemical and mineralogical composition. The process allowed producing crystals with a high purity attending chemical and pharmaceutical purposes. Thus, it was developed a process to produce ferrous sulfate from coal wastes (usually, ferrous sulfate crystals are produced as a co product from titanium dioxide and steel production). The technology presents a high conversion factor of soluble Fe2+ to melanterite and the necessary incomes are pyrite, water, and ethylic alcohol. The hydrometallurgical technique applied in this study allowed production of a commercial grade product from coal mining waste material.
49

Produção de coagulante férrico a partir da lixiviação de concentrado de pirita da mineração de carvão via cristalização/solubilização de sulfato ferroso : estudo comparativo entre rejeitos de duas jazidas

Villetti, Pedro Ivo Chitolina January 2017 (has links)
O beneficiamento de carvão mineral para a utilização em termoelétricas gera grandes quantida-des de rejeitos, os quais contêm diversos minerais, entre eles a pirita (sulfeto de ferro - FeS2). A pirita, na presença de água e oxigênio se oxida, gerando a drenagem ácida de minas (DAM), principal fonte de contaminação dos aquíferos e do solo nas regiões carboníferas. Atualmente, a DAM é tratada pelo método de neutralização/precipitação de metais. Essa é uma técnica con-siderada “fim-de-tubo” com diversas desvantagens, entre elas o alto custo. Entretanto, através de técnicas preventivas, baseadas nos princípios da produção mais limpa, é possível, concomi-tantemente, minimizar a geração de DAM e agregar valor à parte ou totalidade dos rejeitos de carvão. Assim, o objetivo deste trabalho foi estudar a produção do coagulante sulfato férrico a partir da lixiviação de um concentrado de pirita oriundo de rejeitos de carvão via cristaliza-ção/solubilização de sulfato ferroso, comparando o processo para duas jazidas distintas de car-vão mineral. Amostras de concentrados de pirita foram obtidas de rejeitos de carvão das jazidas do Estado de Santa Catarina, minerados na cidade de Forquilhinha, e do Estado do Paraná, na cidade de Figueira A parte experimental foi realizada a partir de um reator de leito empacotado em planta-piloto e envolveu as seguintes etapas: produção de um lixiviado férrico, conversão do lixiviado férrico em ferroso, precipitação do Fe2+ e do sulfato na forma de cristais de sulfato ferroso heptahidratado com auxílio de etanol. Estudou-se, de forma detalhada, a proporção li-xiviado:etanol para o melhor rendimento do processo. Os cristais de sulfato ferroso produzidos a partir do concentrado de pirita catarinense apresentaram características semelhantes a um pa-drão analítico (menos de 1% de impurezas). Os cristais produzidos a partir da pirita paranaense apresentaram um índice levemente superior ao padrão estabelecido comercialmente (1,08%), além de apresentar alguns metais bastante perigosos à saúde, como arsênio. Também se estudou a produção do coagulante férrico via dissolução dos cristais de sulfato ferroso e oxidação do ferro pela adição de soluções aquosas com agentes ácidos e oxidantes. A melhor condição ob-tida foi a seguinte: 5 g de sulfato ferroso, 7,5 mL de água destilada, 1,5 mL de peróxido de hidrogênio e 5 gotas de ácido sulfúrico. Essa proporção proporcionou um coagulante com quase 12% de ferro, sendo que 97% deste ferro na forma férrica. O coagulante produzido foi utilizado no tratamento de água do corpo hídrico Guaíba, empregando-se como referência os padrões brasileiros de potabilidade (Portaria nº 2914 do Ministério da Saúde). Mostrando-se eficiente no tratamento de água para fins de abastecimento público. / The coal processing for use in power plants, generates amounts of residues, which contain var-ious minerals, such as pyrite (iron sulfide-FeS2). Pyrite, in the presence of water and oxygen, oxidizes, generating acid mine drainage (AMD), the main source of contamination of aquifers and soil in the carboniferous region of Santa Catarina. Currently, the AMD is treated by the method of neutralization/precipitation of metals. This is a technique considered "end-of-pipe" with many disadvantages, like the excessive cost. However, through preventive techniques, based on the principles of cleaner production, it is possible, at the same time, minimize the generation of AMD and to add value to a part or totality of coal waste. Thus, the objective of this work was to study the production of ferric sulphate coagulant from the leaching of a pyrite concentrate from coal tailings via crystallization / solubilization of ferrous sulphate, comparing the process to two distinct mineral coal deposits. Samples of pyrite concentrates were obtained from coal tailings from the State of Santa Catarina mines, mined in the city of Forquilhinha, and from the State of Paraná, in the city of Figueira The experimental part was carried out in a bed reactor packed in a pilot plant and involved the following steps: production of a ferric leachate, conversion of ferric leachate into ferrous, precipitation of Fe2 + and sulphate as crystals of ferrous sulphate heptahydrate. It was also studied, in detail, the proportion leached:ethanol for the best yield of the process. The ferrous sulphate crystals produced from the Santa Catarina pyrite concentrate showed characteristics similar to an analytical standard (less than 1% of im-purities). The crystals produced from the Paraná pyrite concentrate presented an index slightly higher than the commercially established standard (1.08%), besides presenting some metals very dangerous to health, such as arsenic. The production of ferric coagulant was also studied by dissolving the ferrous sulphate crystals and iron oxidation by adding aqueous solutions with acidic and oxidizing agents. The best condition obtained was as follows: 5 g of ferrous sulphate, 7.5 ml of distilled water, 1.5 ml of hydrogen peroxide and, 5 drops of sulfuric acid. This pro-portion provided a coagulant with almost 12% iron, with 97% of this iron in the ferric form. The coagulant produced was used in the water treatment of lake Guaíba, using as reference the Brazilian standards of potability. The coagulant produced showed to be efficient in the water treatment for public supply purposes.
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Desenvolvimento e validação de métodos analíticos para determinação de ferro (II) em preparações farmacêuticas de ferro bisglicinado / Development and validation of analytical methods for determination of Fe(II) in ferrous bisglycinate pharmaceutical preparations

Ceni, Danieli Cátia January 2009 (has links)
Ferro bisglicinado (Fe-bis-gli) é um aminoácido quelado, formado pela ligação de duas moléculas de glicina a uma molécula de ferro (II), utilizado para prevenção e tratamento da anemia ferropriva. Não há descrição de métodos analíticos em códigos oficiais para o controle de qualidade do ferro bisglicinado em formas farmacêuticas. É comercializado na forma de cápsulas, produzidas por farmácias magistrais e em forma oral líquida. Deste modo, o objetivo deste trabalho foi a validação de métodos analíticos para o controle qualitativo e quantitativo do Febis- gli em cápsulas e forma oral líquida. A identificação e caracterização do fármaco foram realizadas através da determinação dos caracteres físicos, solubilidade, aquametria, espectrofotometria na região do infravermelho (IV), reações específicas e espectroscopia de Mössbauer. Para a determinação quantitativa foram validados métodos de espectrofotometria na região do visível (VIS), ordem-zero e primeira derivada (VIS-D¹), e cromatografia líquida de alta eficiência (CLAE). A análise estatística demonstrou equivalência entre os métodos CLAE / VIS para a determinação do teor das cápsulas e entre os métodos CLAE / VIS-D¹ para a determinação do Fe-bis-gli na forma oral líquida. / Ferrous bisglicycinate (Fe-bis-gli) is an amino acid chelate which is formed by the binding of two molecules of glycine to one molecule of Fe(II), used for prevention and treatment of iron deficiency. There are no analytical methods in official codes for the quality control of Fe-bis-gli in pharmaceutical forms; however it is marketed in the form of capsules , produced by compounding pharmacies and as oral liquid form. The aim of this work was the validation of analytical methods for the qualitative and quantitative analysis of Fe-bis-gli capsules and oral liquid form. The identification and characterization of the drug were performed through the determination of physical characteristics, solubility, water, infrared (IR), specific reactions and Mössbauer spectroscopy. For the quantitative determination VIS spectrophotometry methods have been validated, zero-order and first derivative (VIS-D¹) and high performance liquid chromatography (HPLC). Statistical analysis showed that HPLC / VIS methods were equivalent to assay capsules and HPLC / VIS-D¹ methods were equivalent to assay Fe-bis-gli in oral liquid form.

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