The Fe(II) regeneration process is an important aspect of Alternate Anode Reaction Technology (AART) using Fe(II)/Fe(III)-SO2 reactions for copper hydrometallurgy; however little has been done to study it specifically. The process regenerates Fe(II) via Fe(III) reduction by SO2(aq), catalyzed by activated carbon particles. To better understand and improve the process, two studies have been conducted with respect to variable factors and their affects on the regeneration. A study of fundamental kinetics confirms that the regeneration reaction is mass transfer-controlled, requiring adsorption of reactants onto the catalyst surface for reaction. The reaction rate is limited by the diffusivity of Fe(III). Initial Fe(III) concentration and carbon particle size are determined to be the most influential factors on the rate under the condition studied. Furthermore, it is observed that flow rate may inhibit the reaction by reducing ion diffusivity. A rate expression for the regeneration is derived and experimentally validated, and the Fe(III) diffusivity is determined to be 1.1x10-7 cm2/s. An optimization problem is also developed and solved for the process, constrained by the requirement that negligible SO2 could be present in the process effluent. Before optimization, a relationship is developed between regeneration rate and variable factors. Again, carbon size and initial Fe(III) are the most influential factors on the regeneration rate, related to it linearly; temperature is significant with a squared relationship to the rate; initial SO2 is insignificant. Optimal conditions are found with minimum carbon particle size, maximum initial Fe(III) concentration, and moderate temperature. / Master of Science

Approved for public release, distribution is unlimited / The Lineate Image Near Ultraviolet Spectrometer (LINUS) is a spectral imager developed to operate in the 0.3-0.4 micron spectral region. The 2-D imager operates with a scan mirror, forming image scenes over time intervals of 10-20 minutes. Sensor calibration was conducted in the laboratory, and the system response to Sulfur Dioxide (SO2) gas was determined. The absorption profile for SO2 was measured, and curves of growth were constructed as a function of gas concentration. Test measurements were performed at the Naval Postgraduate School (NPS), from the roof of Spanagel Hall. Field observations were conducted at a coal-burning factory site at Concord, CA with the purpose of quantifying the presence of SO2. The Concord field measurement showed traces of SO2, with further analysis still required. / Civilian, DSO National Laboratories, Singapore

Devido à escassez de dados espectroscópicos sobre as interações de aminas aromáticas com SO2 e devido também à importância que complexos de transferência de carga assumem numa série de processos, inclusive biológicos, realizou-se um estudo objetivando a caracterização dessa interação através de várias técnicas espectroscópicas, como a espectroscopia Raman, no Infravermelho, no visível-ultravioleta e de Ressonância Magnética Nuclear. A partir dos dados obtidos nesses estudos concluímos que ocorre transferência de carga da amina para o SO2 ; essa transferência ocorre a partir do orbital ocupado de maior energia da amina , localizado principalmente no átomo de nitrogênio, para o orbital vago de mais baixa -energia do SO2 (π * ) localizado no a-tomo de enxofre. Os espectros vibracionais mostram que não é possível correlacionar as frequências de estiramento do SO2 complexado com o pKb (ou potencial de ionização) da base e sugerem que fatores estéricos podem ser importantes, influenciando o recobrimento dos orbitais do doador e do aceptor. No caso particular da ANI.SO2 , alterações na região de estiramento N-H do espectro no infravermelho , indicam que muito provavelmente ocorre a formação de ligações de hidrogênio entre a amina e o SO2 além da interação através do átomo de nitrogênio. ° comportamento termocrômico dos complexos foi investigado através de espectroscopia Raman à baixa temperatura. As informações preliminares obtidas sugerem que o desaparecimento da côr é devido a uma depopulação dos estados vibracionais excitados, a partir dos quais se efetuam as transições eletrônicas com fatores de Franck-Condon muito favoráveis / The shortage of spectroscopic data on the interactions between amines and SO2, together with the relevance that molecular complexes have in several process, including biological ones, stimulated us to study these systems by Raman, Infrared, Visible-Ultra violet and NMR spectroscopic techniques. From the data obtained, it\'s possible to conclude that there is charge transfer from the HOMO of the amines, which is localized mainly at the nitrogen atom, to the LUMO of SO2, localized at the sulfur atom. The vibrational spectra show that it is impossible to correlate any of the SO2 vibrational bands to the pKb of the donor and suggest that steric hindrance may play an important role in such interations, affecting the overlap of donor and aceptor orbitals; in the case of ANI.SO2 , the band shape in the N-H stretching region led us to conclude that hidrogen bonding between the amine and SO2 occurs, together with the specific interation through the nitrogen atom. The complexes show Pré-Resonance Raman Effect and from its study one concludes that SO2 belongs to the chromophoric group. The thermochromism that the complexes present was investigated by Raman Spectroscopy at low temperature. The informations obtained strongly suggest that the vanishing of its colour may be atributed to a depopulation of an vibrational excited state from which the charge transfer eletronic transition can occur with apreciable Franck-Condon factors.

Although the metallurgical industry has made great strides in the reduction of unwanted emissions to the atmosphere as a result of production processes, significant challenges still exist. From a global perspective, even large reductions in emissions per produced ton become immaterial when considering that the total world production of metals continues to increase. Two such particularly hazardous emissions are sulfur dioxide, primarily from copper ore roasting, and mercury, which has had increasing emissions from the steel industry in recent years. Both pollutants have severe consequences for the environment and also for human health. The primary motivations of this work have hence been: (1). to study sulfate formation on soot from sulfur dioxide emissions reacting with ozone and H2O in the vapor phase and (2). to study factors involving the behavior of mercury adsorption on metal surfaces involved in steelmaking, in order to further the understanding of select emissions from scrap-based steelmaking. Gas phase experiments were conducted to examine the heterogeneous oxidation of sulfur dioxide on soot in the presence of ozone and water vapor. The sulfur dioxide oxidation into sulfate was quantified using a particle-into-liquid sampler coupled with ion chromatography to measure the sulfate formation at atmospheric pressure. Water vapor, ozone and sulfur dioxide concentrations were controlled. Due to the ozone oxidation, multilayer adsorption of sulfur dioxide on soot, as well as sulfate formation and physisorption on secondary surface layer sites were observed. The exposure also caused the soot to become hydrophilic, due to the sulfur dioxide adsorption and also likely the formation of carboxyl groups on the surface. No significant increase in sulfate formation was observed at ozone concentrations above 1000 ppm. The effects of common surface contaminants such as oxygen and chlorine were examined on the metal surfaces, as well as the impact of changes in temperature, with controlled conditions using thermal desorption auger electron spectroscopy. It was established that low temperatures (82 K through 111 K) were conducive to mercury adsorption, wherein physisorption and subsequent lateral mercury interactions in mercury adlayers occurred. Chlorine appeared to favor mercury uptake, as determined by the increased mercury coverage at low temperatures on polycrystalline iron, copper and zinc. Oxygen, however, was found to be an inhibitor of mercury, most notably at room temperature. It was surprising to establish that no mercury adsorbed on zinc surfaces at room temperature and only on polycrystalline samples at low temperature. The mercury signal intensity increased up to the limit of the melting temperature for iron systems, on the oxidized copper surface and the polycrystalline zinc surfaces, prior to desorption from the surfaces. It is suggested that this is due to a rearrangement of mercury atoms on the surface at increasing temperatures, whereas at 85 K, mercury adhered to its initial adsorption position. In other words, mercury wet these surfaces on annealing, transitioning from an islanded surface at low temperature to a smooth layer before desorption. Based on these results, it was concluded that the mercury bond to the oxidized surface was weakened compared to clean copper. Furthermore, it is proposed that a surface phase transition occurred on polycrystalline zinc prior to desorption. No such transition was observed on iron. Activation energies of desorption were calculated for the relevant metal surfaces. It was established that clean iron had the highest activation energy of desorption. The large bond strength between mercury and iron may account for the highest desorption temperature of the iron systems. Zinc and copper had similar activation energies and desorption temperatures, which were respectively lower than that of iron. X-Ray Photoelectron and Auger Electron Spectroscopy were used to ascertain common surface contamination, i.e. chlorine, oxygen and sulfur, which affected mercury adsorption. Laser Ablation Inductively Coupled Plasma Time of Flight Mass Spectrometry was used to determine the depth of mercury adsorption on the samples. The technique also showed that the samples contained mercury in the surface layers. Accompanied by the rising demand for metals is the increase in emissions from metals manufacturing. Moreover, it is critical to minimize sulfur dioxide emissions as particulates from soot continue to be released in the atmosphere. For scrap-based steelmaking, monolayer mercury adsorption on clean iron and copper at room temperature are significant results. With the rising use of electronic devices in vehicles, the sorting of scrap becomes increasingly important. Mercury not adsorbing on zinc at room temperature is also of relevance as it disproves the theory of increased mercury adsorption with the increased use of galvanized scrap in summer conditions. However, the low temperature studies showed multilayer adsorption of mercury on iron, zinc and copper, which has relevance for the reported temporal variations of mercury deposition in arctic regions. Keywords: mercury, iron, zinc, sulfur dioxide, adsorption, pollution, thermal desorption, polycrystalline, surfaces, spectroscopy / QC 20120326

The work presented in this thesis document reflects the results of a study carried out to better quantify the magnitude and fate of the anthropogenic air pollutants emitted from East Asia. Simulations of anthropogenic sulfur compounds by a regional on-line coupled chemistry-climate model suggest that large portions of East Asia have high SOx concentrations, and most subregions within East Asia are net exporters of SOx (SO2+SO4) (i.e. the anthropogenic S emissions from the region are greater than the deposition to the region). Among them, China is responsible for ~ 85% of the total emissions, and ~ 50 % of its total emitted SOx is exported to locations outside its borders. During the later winter to early spring when the continental outflow conditions predominate, about 20% of the total emitted SOx within the investigated area has been exported to North Pacific Ocean based on our model simulations. Those exported anthropogenic SOx from East Asia (mainly in the form of sulfate) is likely large enough to perturb the sulfate aerosol concentration over the North Pacific Ocean. Our investigation by integrating numerical simulations through a regional off-line full chemistry transport model, which is driven by the meteorological conditions calculated by a regional climate model, with field measurements of both gaseous and particulate species at a rural site adjacent to the largest industrialized area in China suggests that CO emissions from China, especially eastern China are likely underestimated by ~ 50 % in the current East Asia anthropogenic emission inventories. In addition, a 60-90 % underestimation of particulate carbonaceous emission in the inventories is suggested. Further statistical diagnoses, together with the back-trajectory analysis show that the missing CO sources are likely associated with SO2 sources that are already accounted for in the current inventories. This in turn suggests the emission factors of coal-combustors used in the current inventories are likely underestimated.

D. Tech. Chemical, Metallurgical and Materials Engineering / This study provides experimental data and new perspectives on selective precipitation of platinum group metals (PGMs) in the presence of base metals while at the same time reviewing the mass transfer characteristics and models associated with metal sulphides precipitation in liquid-liquid and gas-liquid systems. In this study, the objective was to investigate and validate the concept of selective precipitation of platinum from chloride media using sulphur-bearing liquids or gases.

D. Tech. Mechanical Engineering. / Investigates and/or rank the performance of locally available materials (i.e. limestone, dolomite, or calcrete) as sorbents in the capture of SO2 emissions from coal-fired power plants. Two experimental procedures were adopted in this work: the pH-stat method was used to simulate conditions encountered in wet flue gas desulphurisation (WFGD); and the fixed-bed reactor was used to simulate conditions encountered in the dry in-duct flue gas desulphurisation (DFGD) process. It is important to note that most studies of using calcium-based materials as sorbents for SO2 removal have been carried out in overseas countries. These studies were carried out using materials and research conditions prevailing in the particular countries. Furthermore, all South African coal-fired power stations burn low grade coal allowing the high grade coal to be exported. As a result, coal-fired power stations in South Africa emit higher emissions than the overseas power stations which are operated on high grade coals. Thus the results achieved internationally may not be directly translated to the South African conditions.

Thesis (M.S.)--Ohio University, June, 2008. / Title from PDF t.p. Includes bibliographical references.

Submitted by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-01-25T19:15:21Z No. of bitstreams: 1 DissALP.pdf: 1718193 bytes, checksum: 49e0c5e9f494782677bd84e48bbf0257 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-01-25T19:15:34Z (GMT) No. of bitstreams: 1 DissALP.pdf: 1718193 bytes, checksum: 49e0c5e9f494782677bd84e48bbf0257 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-01-25T19:15:43Z (GMT) No. of bitstreams: 1 DissALP.pdf: 1718193 bytes, checksum: 49e0c5e9f494782677bd84e48bbf0257 (MD5) / Made available in DSpace on 2018-01-25T19:15:55Z (GMT). No. of bitstreams: 1 DissALP.pdf: 1718193 bytes, checksum: 49e0c5e9f494782677bd84e48bbf0257 (MD5) Previous issue date: 2017-04-11 / Não recebi financiamento / One of the main concerns in the ethanol-producing industries is the growth control of undesirable microorganisms that can cause decrease in the fermentative yield. Among non-Saccharomyces yeasts which can contaminate the fermentation process, the genus Dekkera is the most important because it is able to grow in fermentation conditions and be adapted to the substrates. Regarding the bacteria, Lactobacillus is the most representative genus. In the wine industry, several antimicrobial agents are utilized to control the undesirable yeast and bacteria populations, among them the sulphur dioxide (SO2) which is used in the form of sulphite salts. However, the microbial control by this substance is not known yet in the sugar and alcohol industries, in which the acid treatment of the cells and antibiotics are largely utilized to control the growth of bacteria. In this context, this work aimed to verify the effect of the addition of potassium metabisulphite (PMB) in two steps of the fermentative process for fuel alcohol production: to the raw sugarcane juice and to the acid treatment of the cells. In the first step, PMB concentration and exposure time to the antimicrobial were determined to cause decrease in the number of native yeast and bacteria in the sugarcane juice. Secondly, the minimum inhibitory concentration of PMB was determined to control the growth of Dekkera bruxellensis, an important yeast contaminant of the alcoholic fermentation, when added to the acid treatment of the cells, both in pure culture and in co-culture with Saccharomyces cerevisiae and Lactobacillus fermentum. The effect of this treatment on the fermentative parameters was also analysed. The PMB was effective to control the growth of native yeast and bacteria in the sugarcane juice at the concentration of 800 mg/L with exposure time that varied from 3 to 6 hours, resulting in a maximal reduction of one log cycle for yeasts and from 1.5 to 1.9 log cycles for bacteria. When added to the acid treatment of the cells (pH 2.0), a reduction of approximately one log cycle of D. bruxellensis was verified from the concentration of 225 mg/L of PMB. However, in co-culture with S. cerevisiae and L. fermentum, this concentration also resulted in the decrease of S. cerevisiae cell number, with negative effect on ethanol production. In a cell-recycled batch fermentation, the combination of acid treatment and 150 mg/L of PMB caused a substantial decrease in S. cerevisiae viability as well in the growth of both contaminants, with reduction in the ethanol production and fermentative efficiency. Although the potassium metabisulphite is effective in the context of wine fermentation, it was not appropriate to the fuel ethanol production especially due to the peculiar characteristics of the substrate and the conditions in which the fermentation is carried out. / Uma das principais preocupações das indústrias de produção de etanol combustível é controlar o crescimento de micro-organismos não selecionados para o processo, os quais podem causar prejuízos ao rendimento e a produtividade. Dentre as leveduras não-Saccharomyces contaminantes da fermentação, destaca-se o gênero Dekkera, por apresentar capacidade de crescimento nas condições de fermentação e adaptação aos substratos, e dentre as bactérias, o gênero Lactobacillus. Na indústria do vinho, vários agentes antimicrobianos são utilizados para o controle das populações de leveduras e bactérias indesejáveis, dentre eles o dióxido de enxofre (SO2), utilizado na forma de sais de sulfito. No entanto, o controle de micro-organismos com este agente é pouco conhecido na indústria sucroalcooleira, a qual faz uso principalmente do tratamento ácido entre os ciclos fermentativos e antibióticos para o controle de contaminantes bacterianos. Neste contexto, este trabalho teve por objetivo verificar o efeito da adição de metabissulfito de potássio (MBP) em duas fases do processo fermentativo para produção de etanol combustível: ao caldo de cana bruto e ao tratamento ácido do fermento. Na primeira etapa, verificou-se a concentração e o tempo de contato com o antimicrobiano para causar redução no número de leveduras e bactérias nativas do caldo. Em seguida, determinou-se a concentração mínima inibitória de MBP para o controle do crescimento de Dekkera bruxellensis, uma importante levedura contaminante da fermentação etanólica, quando adicionado ao tratamento ácido do fermento, em cultura pura e em co-cultura com Saccharomyces cerevisiae e Lactobacillus fermentum e o efeito dessa adição sobre os parâmetros fermentativos. O MBP foi eficaz no controle de bactérias e leveduras nativas do caldo na concentração de 800 mg/L com tempo de contato que variou de 3 a 6 horas, proporcionando uma redução máxima de cerca de 1 ciclo log para leveduras e de 1,5 a 1,9 ciclos log para bactérias. Quando adicionado ao tratamento ácido (pH 2,0), ocorreu uma redução de aproximadamente 1 ciclo log de D. bruxellensis a partir de 225 mg/L de MBP. Porém em co-cultura com S. cerevisiae e L. fermentum, essa concentração ocasionou também redução do número de células de S. cerevisiae, com efeito sobre a produção de etanol. Em sistema de fermentação em batelada com reciclo celular, a combinação do tratamento ácido e 150 mg/L de MBP ocasionou queda substancial na viabilidade da levedura do processo e dos contaminantes D. bruxellensis e L. fermentum, com consequente decréscimo na produção de etanol e eficiência fermentativa. Embora seja eficiente no contexto da fermentação para produção de vinhos, o metabissulfito de potássio não se mostrou adequado para a fermentação alcoólica para produção de etanol combustível, devido às características peculiares do substrato utilizado e das condições em que é realizada a fermentação.

Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2017-02-21T16:57:31Z No. of bitstreams: 1 TeseTML.pdf: 9976156 bytes, checksum: 2b00da954b5187d6f10e5593523581c0 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-03-14T20:24:10Z (GMT) No. of bitstreams: 1 TeseTML.pdf: 9976156 bytes, checksum: 2b00da954b5187d6f10e5593523581c0 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-03-14T20:24:20Z (GMT) No. of bitstreams: 1 TeseTML.pdf: 9976156 bytes, checksum: 2b00da954b5187d6f10e5593523581c0 (MD5) / Made available in DSpace on 2017-03-14T20:33:50Z (GMT). No. of bitstreams: 1 TeseTML.pdf: 9976156 bytes, checksum: 2b00da954b5187d6f10e5593523581c0 (MD5) Previous issue date: 2016-08-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The increasing demand for oil and oil derived products contributed to the alarming increase in the gaseous pollutants emissions in general and mainly contributed to the increase in carbon monoxide (CO) emissions in the worldwide. Besides being delivered on fossil fuels burning processes, a large amount of CO is also generated during the oil refining process, especially in the fluid catalytic cracking unit (FCC). In order to reduce the costs associated to the CO oxidation catalysts many efforts have been devoted to substitution of noble metals by non-noble transition metals, such as cobalt oxides and manganese oxides. However, the biggest challenge for this replacement is to keep the activity of these catalysts in the presence of interfering agents, such as SO2 and H2O, which might deactivate the catalysts or even inhibit the CO oxidation reaction. In this context, the aim of this study is to evaluate the activity of cobalt and/or manganese catalysts, promoted or not by molybdenum and supported on mesoporous molecular sieve type SBA-15 in the CO oxidation reaction in the presence of SO2 (450 ppm) and H2O (10% V/V). These catalysts were prepared by three different methods: (i) impregnation, (ii) deposition-precipitation using microwave and (iii) one-pot. It is noteworthy that the catalysts prepared by the methods of deposition-precipitation and one-pot represents a major breakthrough regarding to green synthesis methods, since they allowed representative savings of energy and water. It was found that the one-pot and deposition-precipitation methods yielded catalysts with high dispersion of the active phase and quite active in CO oxidation reaction. Furthermore, analysis of XRD, Raman, EPR, UV-Vis, XPS and H2-TPR revealed that the one-pot method yielded better dispersion of the molybdenum species over the SBA-15 support, which provided excellent resistance to the cobalt and/or manganese catalysts to SO2 and H2O poisoning. Moreover, the catalysts promoted by molybdenum and prepared by the deposition-precipitation method were composed by cobalt or manganese molybdates, as indicated by XRD, Raman, UV-Vis and XPS techniques, which are less active in the CO oxidation reaction. The catalysts promoted by molybdenum and prepared by the impregnation method possessed a smaller dispersion of the promoter, with the formation of molybdenum oxide, and thus reducing the resistance of these catalysts in the presence of the interfering agents. / A crescente demanda por petróleo e seus derivados contribuiu para o alarmante aumento das emissões de poluentes gasosos de um modo geral e principalmente contribuiu para o aumento das emissões do monóxido de carbono (CO) em todo o mundo. Além de ser emitido em processos de queima de combustíveis fósseis, grande quantidade de CO também é gerada durante o processo de refino do petróleo, principalmente na unidade de craqueamento catalítico em leito fluido (FCC). Com o objetivo de reduzir os custos associados aos catalisadores de oxidação do CO diversos esforços têm sido dedicados para a substituição dos metais nobres por metais de transição não nobres, tais como óxidos de cobalto e óxidos de manganês. Entretanto, o maior desafio para esta substituição é manter a atividade destes catalisadores na presença dos agentes interferentes, SO2 e H2O, que atuam desativando estes catalisadores ou mesmo inibindo a reação de oxidação do CO. Neste contexto, o objetivo geral deste trabalho é avaliar a atividade de catalisadores de cobalto e/ou manganês, modificados ou não por molibdênio e suportados em peneira molecular mesoporosa tipo SBA-15 na reação de oxidação do CO na presença de SO2 (450 ppm) e H2O (10 % V/V). Estes catalisadores foram preparados por três diferentes métodos: (i) impregnação, (ii) deposição-precipitação utilizando micro-ondas e (iii) one-pot. Vale ressaltar que os catalisadores preparados pelos métodos de deposição-precipitação e one-pot representam um grande avanço no que se diz respeito a métodos verdes de síntese, pois permitiram grande economia de energia e de água. Foi constatado que os métodos one-pot e deposição-precipitação renderam catalisadores com elevada dispersão das fases ativas e bem ativos na reação de oxidação do CO. Além disso, as análises de DRX, Raman, EPR, UV-Vis, XPS e H2-RTP revelaram que o método one-pot rendeu a melhor dispersão das espécies de molibdênio sobre o suporte de SBA-15, que conferiu excelente resistência aos catalisadores de cobalto e/ou manganês ao envenenamento por SO2 e H2O. Por outro lado, os catalisadores modificados por molibdênio e preparados pelo método de deposição-precipitação foram compostos por molibdatos de cobalto ou manganês, conforme indicado pelas técnicas de DRX, Raman,UV-Vis e XPS, fase menos ativa na reação de oxidação do CO. Além disso, os catalisadores preparados pelo método de impregnação e modificados por molibdênio possuíram menor dispersão do metal promotor, com formação de óxido de molibdênio, e, reduzindo assim, a resistência destes catalisadores na presença dos agentes interferentes.