The LINEATE IMAGING NEAR ULTRAVIOLET SPECTROMETER (LINUS) instrument has been used to remotely detect and measure sulfur dioxide (SO2). The sensor was calibrated in the lab, with curves of growth created for the 0.29 0.31 æ - spectral range of the LINUS sensor. Field observations were made of a coal burning plant in St. Johnâ s, Arizona at a range of 537 m. The Salt River Coronado plant stacks were emitting on average about 100 ppm and 200 ppm from the left and right stacks respectively. Analysis of the LINUS data matched those values within a few percent. Possible uses for this technology include remote verification of industry emissions and detection of unreported SO2 sources.

Orientador: Nelson Ramos Stradiotto / Banca: Maria Del Pilar Taboada Sotomayor / Banca: José Fernando de Andrade / Banca: Jeosadaque José de Sene / Banca: Adaléa Lopes Brandes Marques / Resumo: Os compostos sulfurados no petróleo têm causado diversos problemas como os correlacionados à corrosão de equipamentos, envenenamento de catalisadores em processo de refino, qualidade dos produtos, além de liberação de gases tóxicos diretamente ao meio ambiente. Os compostos sulfurados em especial (enxofre elementar, difenil dissulfeto e 1-butanotiol) podem agravar estes problemas, sendo os principais causadores de corrosão de equipamentos nas refinarias de petróleo. Devido a tais considerações, a proposição deste trabalho é o desenvolvimento de metodologias eletroanalíticas para determinação de compostos sulfurados em gasolina, utilizando os eletrodos de filme de mercúrio, amálgama sólido e hexacianoferrato de cobre. No primeiro trabalho desenvolvido utilizou-se o eletrodo filme de mercúrio juntamente com as técnicas eletroanalíticas de voltametria de varredura linear (VVL), onda quadrada (VOQ) e pulso diferencial (VPD) em solução de acetato de sódio 1,4 mol L-1 e ácido acético 2% em metanol, como eletrólito suporte. O método apresentou limites de detecção na ordem de 10-9 a 10-4 mol L-1 para as técnicas eletroanalíticas de VVL, VOQ e VPD, inferiores aos já relatados na literatura usando método análogo. A quantificação dos compostos de enxofre em amostras de gasolina, a partir do monitoramento do sinal de redução sobre a superfície do eletrodo filme de mercúrio, utilizando a técnica de voltametria de onda quadrada, foi possível sem tratamento prévio da amostra, cujo procedimento mostrou ser bastante eficiente não provocando qualquer interferência associada aos constituintes da matriz, exibindo valores de 3,5x10-8, 3,7x10-7 e 4,2x10-8 mol L-1 para enxofre elementar, difenil dissulfeto e 1-butanotiol, respectivamente. A quantificação nas amostras de gasolina, avaliadas em termos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The presence of sulfur compounds in petroleum has caused several problems including those related to the corrosion of equipments, and the quality of final products, as well as the emission of toxic gases to the environment. Sulfur compounds (elemental sulfur, diphenyl disulfide and 1-butanethiol), can increase these problems, being the main causes of corrosion of equipments in the refineries of petroleum. Based on these assumptions, the principal proposal of this work is the development of electroanalytical methodology for determination of sulfur compounds in gasoline using the electrodes of mercury film, amalgam solid and copper hexacyanoferrate. In the first developed work the mercury film electrode was used together with the electroanalytical techniques of linear scan voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) in solution of 1.4 mol L-1 sodium acetate and acetic acid 2% in methanol. The method presented detection limits in the order from 10-9 to 10-4 mol L-1 for the electroanalytical techniques of LSV, SWV and DPV. These limits are inferior to the previous related in the literature using similar method. The quantification of the sulfur compounds in gasoline samples, starting from the monitoring of the reduction sign on the mercury film electrode surface using the technique of square wave voltammetry was possible without previous sample treatment, whose procedure showed to be efficient, it not provoking any interference associated to the sample, exhibiting values of 3.5x10-8, 3.7x10-7 and 4.2x10-8 mol L-1 for elemental sulfur, diphenyl disulfide and 1-butanethiol, respectively. The quantification in the samples of gasoline in recovery terms showed that the methodology electroanalytical supplied quite acceptable results with recovery levels and precision compatible to the found by other techniques. In a second... (Complete abstract click electronic access below) / Doutor

Orientador: Nelson Ramos Stradiotto / Banca: Marcelo Firmino de Oliveira / Banca: Jeosadaque José de Sene / Resumo: O enxofre presente no biodiesel é um contaminante que mesmo em baixas quantidades está associado ao mau funcionamento de conversores catalíticos, emissão de gases e materiais particulados, e a corrosão de partes do motor. Neste trabalho, foi desenvolvido um eletrodo de amálgama sólido de prata (AgSAE) para determinação de enxofre em microemulsões de biodiesel. A caracterização eletroquímica do AgSAE foi realizada em solução eletrólito tampão amônia/amônio devido as melhores condições de análise do enxofre ser em meio alcalino. Através dos experimentos de voltametria cíclica de redissolução adsortiva, sugere-se que o processo redox envolvido se distância da reversibilidade possivelmente devido a uma reação química acoplada. Antes de cada medida foi estipulado um tempo de acúmulo de 120 segundos, devido ao processo adsortivo que ocorre entre o sulfeto em solução e a superfície do AgSAE. Essa característica adsortiva permitiu alcançar um LD da ordem de 10-8 mol L-1 em meio aquoso para as técnica de LSAdSV, SWAdSV e DPAdSV. Um diagrama de fase ternário foi construído a fim de estipular a região onde se forma uma microemulsão caracterizando a sua composição. Avaliou-se o comportamento eletroquímico do sulfeto em dez diferentes composições, observando que em apenas quatro há redução. A microemulsão que apresentou melhor resposta em termos de intensidade de corrente de pico catódica e resolução foi 25% de solução tampão (pH 9,0), 5% de biodiesel e 70% de propanol. A validação do método foi realizada em um material de referência certificado de biodiesel de soja, os LD e LQ obtidos para LSAdSV, SWAdSV e DPAdSV foram da ordem de 10-7 mol L-1. O estudo de recuperação apresentou valores próximos de 100%. A metodologia foi aplicada na determinação de enxofre em... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The sulfur present in biodiesel is a contaminant that even at low quantities is associated with the malfunctioning of catalytic converters, gaseous and particulate materials, and corrosion of engine parts. In this work, we developed a solid amalgam electrode silver (AgSAE) for determination of sulfur in biodiesel microemulsions. The electrochemical characterization was performed on the AgSAE electrolyte solution buffered ammonia/ammonium due to better analysis of the sulfur being in an alkaline medium, as the pH study shows conducted. Through the adsorptive stripping cyclic voltammetry experiments, it is suggested that the redox process involved becomes far from reversibility possibly due to a chemical reaction coupled. Before each measurement one was fixed accumulation time of 120 seconds, due to adsorptive process that occurs between the sulfite solution and the surface of AgSAE. This characteristic achieves an adsorptive LD of the order of 10-8 mol L-1 in aqueous medium. A ternary phase diagram was constructed to stipulate the region where it forms a microemulsion characterizing its composition. We evaluated the electrochemical behavior of sulfate in ten different compositions, noting that there are only four in reduction. The microemulsion showed better response in terms of intensity and cathodic peak current resolution was 25% of buffer (pH 9,0), 5% biodiesel and 70% propanol. The method validation was performed in a certified reference material of biodiesel from soybeans, LOD and LOQ obtained for LSAdSV, and SWAdSV DPAdSV were the order of 10-7 mol L-1, and the study showed recovery values close to 100%. The methodology was applied in the determination of sulfur in biodiesel sample, the sulfur content in the samples was... (Complete abstract click electronic access below) / Mestre

Digitized by Kansas Correctional Industries

Studies were conducted into the mechanism and kinetics of the dissolution of synthetic zinc sulfide and zinc concentrate in aqueous solutions containing sulfur dioxide.Experiments at ambient temperature established that the dissolution of ZnS in aqueous solutions of sulfur dioxide proceeds via acidic non-oxidative dissolution and not by direct reaction of the sulfide with S02(aq). The non-oxidative dissolution reaction generates H2S(aq) or HS-(aq) species which are thought to rapidly react with sulfurous acid species, S02(aq) or HS03-(aq), to possibly produce initially sulfane monosulfonates as intermediates, followed by sulfane disulfonates and elemental sulfur. The formation of sulfane monosulfonates is postulated based upon inhibition observed in ZnS / S02 leaches which is not attributable to either H2S(aq) or occlusion elemental sulfur.At elevated temperatures (100oC - 200oC) the rate of ZnS dissolution in sulfurous acid is affected by the thermal decomposition of sulfurous acid, which produces sulfuric acid, which leaches the mineral non-oxidatively. Increasing the temperature increases the rate of thermal decomposition of sulfurous acid and consequently, the rate of sulfuric acid formation, increasing the rate of ZnS dissolution.The kinetics of the dissolution of ZnS in solutions of sulfuric acid and sulfur dioxide were investigated at temperatures up to 200oC. At 100oC and 150oC, the dissolution of ZnS in H2SO4 was found to obey the relationd[Zn2+]/dt = kfAs[H+] krAs[H2S(aq)]1/2[Zn2+]1/2and equilibria and rate constants for the ZnS / H2S04 reaction were obtained over the range, 100oC to 200oC. The activation energies of the forward and reverse reactions were found to be 56 +/- 11 kJ mol-1 and 45 +/- 15 kJ mol-1, respectively. The equilibrium constants were 4.99x10-4, 1.26x10-3 and 2.83x10-3 at 100oC, 150oC and 200oC, respectively.In the presence of added S02, ++ / at low ZnS pulp density (0.5 g L-1), the rate of ZnS dissolution in sulfuric acid increased due to the removal of H2S(aq) by reaction with S02(aq) or HS03-(aq). However the increase in rate was much less than that expected for the complete removal of H2S(aq). As with leaches of ZnS in sulfurous acid at ambient temperature, the inhibition was not attributable to the presence of residual H2S(aq) or to occlusion of unreacted ZnS by elemental sulfur, but is thought to be due to aqueous species that are like "H2S", in that they may react with Zn2+ to reprecipitate W.To this end, sulfane monosulfonates have again been postulated. The rate of ZnS dissolution, under conditions of low pulp density, was independent Of S02 concentration, suggesting that under these conditions the rate of the H2S / S02 reaction is also independent of the S02 concentration.At higher pulp densities (200 g L-1), similar to those expected in an industrial application, synthetic zinc sulfide leached rapidly in H2S04 / S02 solutions to approximately 60% zinc extraction, but was then inhibited by the large amounts of sulfur that formed. These caused agglomerates of zinc sulfide and elemental sulfur to form, even at temperatures below the melting point of sulfur, reducing the surface area of zinc sulfide available for reaction.Leaches of zinc concentrate at low pulp densities in H2S04 / S02 solutions and at temperatures above sulfur's meting point, were inhibited by the formation of molten sulfur. In contrast to synthetic zinc sulfide, zinc concentrate is readily wet by molten sulfur. Three surfactants orthophenylenediamine, quebracho and sodium ligninsulfonate were found to be reasonably effective in preventing molten sulfur from occluding the mineral surface. At high pulp densities, the H2S04 / S02 leach solution was unable to effect, the extraction of zinc from a zinc concentrate beyond approximately ++ / 10%.Integral S02 / H2S04 leaching of zinc concentrate was found not to be a commercial prospect. However, sidestream processing of zinc concentrate in an acid leach stage followed by reaction of generated H2S with S02 from the roasting stage to produce elemental sulfur may be viable.

No description available.

The sedimentary sulfur cycle is one of the main components of estuarine biogeochemical systems. It is initiated by the oxidation of organic matter via sulfate reducing bacteria which produce hydrogen sulfide (H2S). The S(II) then reacts via both abiotic and biotic pathways to form sulfur with other oxidation states. The three most widely-studied “operationally”–defined components of the sedimentary sulfur system are total reduced (inorganic) sulfur (TRS), acid volatile sulfide (AVS), and dissolved (=filter-passing) sulfide. This study focused on several parameters that are widely held to be important in determining TRS in sediments and the relative proportions of TRS, AVS and dissolved S(II) forms. The formation of iron sulfide minerals requires metabolizable organic matter and SO4 2- to produce S(II) and “reactive”-Fe as a source for the iron in iron sulfide minerals. One of these components is generally the limiting factor in TRS formation (e.g., Berner 1970). Nine different sites from three locations on the Central Texas coast were studied for a variety of parameters including organic matter, sulfate concentrations, sulfate reduction rate, solid “reactive” and dissolved iron, and grain size, as well as TRS, AVS, and ΣH2S. At each site five sediment cores were taken to a depth of 20 cm whenever possible. The cores were sectioned in 2 cm intervals. The porewater was extracted and both solid and dissolved components were analyzed using a variety of methods, including carbon and sulfur coulometry, acid extraction, chromium extraction, and drying the sediment. The results of he analyses showed that the central Texas coast is a widely diverse system. Some sites were very sandy while others were fine-grained. This variety was especially true for the Nueces Bay and Baffin Bay sites. The East Matagorda Bay sites showed more homogeneity in almost all analysis. While the heterogeneity of locations along the Central Texas coast makes it difficult to make a definitive statement about the controls on TRS in this area, most sites are controlled by the low amounts of iron in the system, which limits the amount of iron sulfide that can form. Low reactive iron concentrations and high degrees of pyritization (DOPs) support this argument. Exceptions exist for low-salinity (sulfate-limited) or very fine-grained (organic matter limited) sites.

The longstanding view has been that metabolism allows for cell division to take place, but that metabolic processes do not actively promote cell division. I have recently challenged this notion by identifying a unique gain-of-function metabolic mutant in the budding yeast Saccharomyces cerevisiae. Moderate over-expression of Abf2p, a conserved mitochondrial DNA (mtDNA) maintenance protein, increases the amount of mtDNA by 100-150%. I have shown that cells moderately over-expressing Abf2p can out-proliferate their wild type (WT) counterparts, initiate DNA replication sooner, and increase in size faster than WT cells. Yeast grown under certain conditions in continuous cultures become synchronized with respect to their oxygen consumption, displaying distinctive oxidative and reductive phases. In cells over-expressing Abf2p, the reductive phase is expanded compared to that of WT cells. Since glutathione, the cell?s main redox buffer and sulfur containing metabolite, peaks during this phase, I asked if sulfur metabolism was altered in cells with more mtDNA. Sulfur metabolite levels are increased ~40% in cells over-expressing Abf2p. Furthermore, exogenous addition of various sulfur containing compounds, which is known to increase sulfur metabolic flux, caused WT cells to increase in size faster and initiate DNA replication sooner, mimicking the phenotype seen in cells moderately overexpressing Abf2p. I then investigated possible interactions between sulfur metabolism enzymes and the yeast Cdk, Cdc28p. Performing co-immunoprecipitation experiments, two enzymes of the sulfur metabolic pathway were found to bind Cdc28p. One of these, Cys4p, lies at the critical junction point between the pathways leading to the formation of glutathione versus one carbon metabolism. The interaction of the enzymes with Cdc28p appears to be dependent on progression through the cell cycle, and preliminary evidence suggests that Cdc28p/Cys4p binding may peak at the G1/S transition of the cell cycle. In summary, I have identified a unique gain-of-function metabolic mutant in S. cerevisiae that leads to accelerated initiation of DNA replication. Sulfur metabolic flux is up-regulated in cells over-expressing Abf2p, and exogenous sulfur sources added to WT cultures phenocopied cells over-expressing Abf2p. Most importantly, I have shown a physical interaction between sulfur metabolic enzymes and the Cdk driving the cell cycle in yeast.

Thesis (M. Phil.)--University of Hong Kong, 1978.

No description available.