Memoria para optar al título de Geóloga / El presente trabajo tiene como objetivo la estimación de flujo de dióxido de azufre en penachos volcánicos mediante una cámara infrarroja. Nicair 1. Es posible medir el SO2 debido al alto contraste que tiene este gas en penachos volcánicos y la atmósfera circundante y la alta señal que posee el SO2 en el espectro centrado en los 8.6µm donde el vapor de agua es débil. La cámara infrarroja captó la señal recibida al fotografíar los penachos volcánicos y mediante el procesamiento de las imágenes según la metodología presentada en este trabajo, se obtuvieron las concentraciones lineales de SO2 (ppmm), las que junto a la estimación de la velocidad de desplazamiento, se integraron según transectas perpendiculares al desplazamiento del penacho para obtener las tasas de emisión (toneladas día-1). Se estimaron concentraciones lineales de SO2 en los volcanes Irruputuncu, Ollagüe y Láscar y solo en este último se calcularon las tasas de emisión en las cercanías al cráter (400 m de altura). Los resultados obtenidos indican emisiones inferiores a las 140 ton/día las que son coherentes con un estratovolcán en estado de quiescencia y la ausencia de cuerpo magmático superficial. Se propone profundizar en las aplicaciones de la cámara infrarroja, considerando que es un instrumento portable. Específicamente estimar tasas de emisión de SO2 en periodos más prolongados y estudiar las emisiones nocturnas. / Centro de Excelencia en Geotermia de Los Andes

Background: Air pollution has been associated with adverse health effects for all-cause and specific respiratory morbidity and mortality outcomes. Acute exacerbations of COPD (AE-COPD) accelerate the decline in pulmonary function and are associated with greater mortality, morbidity, health care utilization, and reduced quality of life. Since the 1970 Clean Air Act was implemented, important reductions in air pollution have been achieved, but no safe threshold has been identified. Objectives: The study was planned to evaluate associations between exposure to ambient concentrations of five criteria air pollutants (CO, SO2/, NO2/, ozone, PM2.5/) in Philadelphia, Pennsylvania, and visits to Temple University Hospital for AE-COPD, from January 1, 2005 through March 31, 2007. To identify subgroups with greater susceptibility to air pollution, associations were examined according to age, gender, race, residence, and antibiotic prescription. Methods: Average daily air pollutant concentrations were obtained from the EPA's Air Quality Services Data Mart. Air pollutant exposures were evaluated for the day of the visit (lag0), one and two days preceding the visit (lag1 and lag2), and the average concentration over three days (lag012). Poisson regression provided rate ratios (RRs) to estimate associations between air pollution exposures and AE-COPD hospital visits. Results: Of 1546 hospital visits for AE-COPD, 43% were from persons 65 years or older, 50% of each gender, and 90% from Philadelphia. In single pollutant models, increased RRs were present at all lags for NO2/ (e.g., RR = 2.27 [95%CI: 1.52, 3.38] at lag012) and SO2/ (e.g., RR = 1.70 [95%CI: 1.38, 2.08] at lag012). For PM2.5/, the direct effect was present only during the winter at lag1, lag2, and lag012 (RR = 1.79 [95%CI: 1.08, 2.96]). Inverse associations were present for ozone at all lags (e.g., RR = 0.64 [95%CI: 0.53, 0.76] at lag012). Compared to the cohort as a whole, those ≥ 65 years of age were at greater risk of an AE-COPD hospital visit associated with PM2.5/ and CO at lag012, with NO2/ and SO2/ at lag0 and lag012, but there was no difference in ozone effect. Conclusions: Primary gaseous air pollution exposures (SO2/, CO, NO2/) were associated with increased AE-COPD hospital visits among COPD patients at Temple University Hospital. The effects of SO2/, CO, NO2/, and PM2.5 were greater for the subgroup ≥ 65 years of age compared to the cohort as a whole. Inverse associations with ozone were consistent across subgroups. These results suggest that air quality during the study period was insufficient to protect the health of COPD patients, especially those ≥ 65 years old. Further study is needed to understand generalizability to other populations and to evaluate lower ranges of exposure from current levels of air pollution. / Public Health

Sulfide minerals are a major source of metals; however, certain sulfide minerals, such as pyrite and pyrrhotite, are less desirable. Froth flotation is a commonly used separation technique, which requires the use of several reagents to float and depress different sulfide minerals. Xanthate, a thiol collector, has gained immense usage in sulfide minerals flotation. However, some sulfides are naturally hydrophobic and may float without a collector. Iron sulfides, such as pyrite and pyrrhotite, are few of the most abundant minerals, yet economically insignificant. Their existence with other sulfide minerals leads to an inefficient separation process as well as environmental problems, such as acid mine drainage during mining and processing and SO2 emissions during smelting process. A part of the present study is focused on understanding their behavior, which leads to undesired flotation and difficulties in separation. The major reasons for the undesired flotation are attributed to the collectorless hydrophobicity and the activation with heavy metal ions. To better understand the collectorless hydrophobicity of pyrite, Electrochemical Impedance Spectroscopy (EIS) of freshly fractured pyrite electrodes was used to study the oxidation and reduction of the mineral. The EIS results showed that the rate of reaction increases with oxidation and reduction. At moderate oxidizing potentials, the rate of reaction is too slow to replenish hydrophilic iron species leaving hydrophobic sulfur species on the surface. However, at higher potentials, iron species are replaced fast enough to depress its flotation. Effects of pH and polishing were also explored using EIS. Besides collectorless hydrophobicity, the activation of pyrrhotite with nickel ions and interaction with xanthate ions makes the separation more difficult. DETA and SO2 are commonly used as pyrrhotite depressants; however, the mechanism is not very well understood. Contact angle measurements, cyclic voltammetry and Tafel studies have been used to elucidate the depressing action of DETA and SO2. It was observed that DETA and SO2 complement each other in maintaining lower pulp potentials and removing polysulfides. DETA also helps in deactivating pyrrhotite. Therefore, the combined use of DETA and SO2 leads to the inhibition of both the collectorless flotation and the adsorption of xanthate. The adsorption of xanthate on sulfide minerals is a mixed-potential mechanism, i.e., the anodic oxidation of xanthate requires a cathodic counterpart. Normally, the cathodic reaction is provided by the reduction of oxygen. However, oxygen can be replaced by other oxidants. Ferric ions are normally present in the flotation pulp. Their source could be either iron from the grinding circuit or the ore itself. The galvanic studies were carried out to test the possibility of using ferric ions as oxidants and positive results were obtained. Tafel studies were carried out to measure the activation energies for the adsorption of ethylxanthate on several sulfide minerals. Pyrite, pyrrhotite (pure and nickel activated), chalcocite and covellite were studied in 10-4 M ethylxanthate solution at pH 6.8 at temperatures in the range of 22 – 30 0C. The Tafel studies showed that xanthate adsorbs as dixanthogen (X2) on pyrite and pyrrhotite, nickel dixanthate (NiX2) on nickel-activated pyrrhotite and cuprous xanthate (CuX) on both chalcocite and covellite. However, the mechanism for xanthate adsorption on each mineral is different. The free energy of reaction estimated from the activation energies are in good agreement with thermodynamically calculated ones. / Ph. D.

The environmentally unsafe by-products (CO2, H2S, NOx and SO2 for example) of using carbon-based fuels for energy generation have paved the way for research on cleaner, renewable and possibly cheaper alternative energy production methods. Hydrogen gas, which is considered as an energy carrier, can be applied in a fuel cell setup for the production of electrical energy. Although various methods of hydrogen production are available, sulphur-based thermochemical processes (such as the Hybrid Sulfur Process (HyS)) are favoured as alternative options for large scale application. The SO2 electrolyser is applied in producing H2 gas and H2SO4 by electrochemically converting SO2 gas and water. This study focused firstly on the evaluation of the performance of the SO2 electrolyser for the production of hydrogen and sulphuric acid, using commercially available PFSA (perfluorosulfonic acid) (Nafion®) as benchmark by evaluating i) various operating parameters (such as cell temperature and membrane thickness), ii) the influence of MEA (membrane electrode assembly) manufacturing parameters (hot pressing time and pressure) and iii) the effect of H2S as a contaminant. Subsequently, the suitability of novel PBI polyaromatic blend membranes was evaluated for application in an SO2 electrolyser. The parametric study revealed that, depending on the desired operating voltage and acid concentration, the optimisation of the operating conditions was critical. An increased cell temperature promoted both cell voltage and acid concentration while the use of thin membranes resulted in a reduced voltage and acid concentration. While an increased catalyst loading resulted in increased cell efficiency, such increase would result in an increase in manufacturing costs. Using electrochemical impedance spectroscopy at the optimised operating conditions, the MEA manufacturing process was optimised with respect to hot press pressure and time, while the effect of selected operating conditions was used to evaluate the charge transfer resistance, ohmic resistance and mass transport limitations. Results showed that the optimal hot pressing conditions were 125 kg.cm-2 and 50 kg.cm-2 for 5 minutes when using 25 and 10 cm2 active areas, respectively. The charge transfer resistance and mass transport were mostly influenced by the hot pressing procedure, while the ohmic resistance varied most with temperature. Applying the SO2 electrolyser in an alternative environment to the HyS thermochemical cycle, the effect of H2S on the SO2 electrolyser anode was investigated for the possible use of SO2 electrolysis to remove SO2 from mining off-gas which could contain H2S. Polarisation curves, EIS and CO stripping were used to evaluate the transient voltage response of various H2S levels (ppm) on cell efficiency. EIS confirmed that the charge transfer resistance increased as the H2S competed with the SO2 for active catalyst sites. Mass transport limitations were observed at high H2S levels (80 ppm) while the ECSA (electrochemical surface area obtained by CO stripping) showed a significant reduction of active catalyst sites due to the presence of H2S. Pure SO2 reduced the effective active area by 89% (which is desired in this case) while the presence of 80 ppm H2S reduced the active catalyst area to 85%. The suitability of PBI-based blend membranes in the SO2 electrolyser was evaluated by using chemical stability tests and electrochemical MEA characterisation. F6PBI was used as the PBI-containing base excess polymer which was blended with either partially fluorinated aromatic polyether (sFS001), poly(2,6-dimethylbromide-1,4-phenylene oxide (PPOBr) or poly(tetrafluorostyrene-4-phosphonic acid) (PWN) in various ratios. Some of the blend membranes also contained a cross-linking agent which was specifically added in an attempt to reduce swelling and promote cross-linking within the polymer matrix. The chemical stability of the blended membranes was confirmed by using weight and swelling changes, TGA-FTIR and TGA-MS. All membranes tested showed low to no chemical degradation when exposed to 80 wt% H2SO4 at 80°C for 120 h. Once the MEA doping procedure had been optimised, electrochemical characterisation of the PBI MEAs, including polarisation curves, voltage stepping and long term operation (> 24 h) was used to evaluate the MEAs. Although performance degradation was observed for the PBI membranes during voltage stepping, it was shown that this characterisation technique could be applied with relative ease, producing valuable insights into MEA stability. Since it is expected that the SO2 electrolyser will be operated under static conditions (cell temperature, pressure and current density) in an industrial setting (HyS cycle or for SO2 removal), a long term study was included. Operating the SO2 electrolyser under constant current density of 0.1 A cm-2 confirmed that PBI-based polyaromatic membranes were suitable, if not preferred, for the SO2 environment, showing stable performance for 170 hours. This work evaluated the performance of commercial materials while further adding insights into both characterisation techniques for chemical stability of polymer materials and electrochemical methods for MEA evaluation to current published literature. In addition to the characterisation techniques this study also provides ample support for the use of PBI-based materials in the SO2 electrolyser. / PhD (Chemistry), North-West University, Potchefstroom Campus, 2015

The environmentally unsafe by-products (CO2, H2S, NOx and SO2 for example) of using carbon-based fuels for energy generation have paved the way for research on cleaner, renewable and possibly cheaper alternative energy production methods. Hydrogen gas, which is considered as an energy carrier, can be applied in a fuel cell setup for the production of electrical energy. Although various methods of hydrogen production are available, sulphur-based thermochemical processes (such as the Hybrid Sulfur Process (HyS)) are favoured as alternative options for large scale application. The SO2 electrolyser is applied in producing H2 gas and H2SO4 by electrochemically converting SO2 gas and water. This study focused firstly on the evaluation of the performance of the SO2 electrolyser for the production of hydrogen and sulphuric acid, using commercially available PFSA (perfluorosulfonic acid) (Nafion®) as benchmark by evaluating i) various operating parameters (such as cell temperature and membrane thickness), ii) the influence of MEA (membrane electrode assembly) manufacturing parameters (hot pressing time and pressure) and iii) the effect of H2S as a contaminant. Subsequently, the suitability of novel PBI polyaromatic blend membranes was evaluated for application in an SO2 electrolyser. The parametric study revealed that, depending on the desired operating voltage and acid concentration, the optimisation of the operating conditions was critical. An increased cell temperature promoted both cell voltage and acid concentration while the use of thin membranes resulted in a reduced voltage and acid concentration. While an increased catalyst loading resulted in increased cell efficiency, such increase would result in an increase in manufacturing costs. Using electrochemical impedance spectroscopy at the optimised operating conditions, the MEA manufacturing process was optimised with respect to hot press pressure and time, while the effect of selected operating conditions was used to evaluate the charge transfer resistance, ohmic resistance and mass transport limitations. Results showed that the optimal hot pressing conditions were 125 kg.cm-2 and 50 kg.cm-2 for 5 minutes when using 25 and 10 cm2 active areas, respectively. The charge transfer resistance and mass transport were mostly influenced by the hot pressing procedure, while the ohmic resistance varied most with temperature. Applying the SO2 electrolyser in an alternative environment to the HyS thermochemical cycle, the effect of H2S on the SO2 electrolyser anode was investigated for the possible use of SO2 electrolysis to remove SO2 from mining off-gas which could contain H2S. Polarisation curves, EIS and CO stripping were used to evaluate the transient voltage response of various H2S levels (ppm) on cell efficiency. EIS confirmed that the charge transfer resistance increased as the H2S competed with the SO2 for active catalyst sites. Mass transport limitations were observed at high H2S levels (80 ppm) while the ECSA (electrochemical surface area obtained by CO stripping) showed a significant reduction of active catalyst sites due to the presence of H2S. Pure SO2 reduced the effective active area by 89% (which is desired in this case) while the presence of 80 ppm H2S reduced the active catalyst area to 85%. The suitability of PBI-based blend membranes in the SO2 electrolyser was evaluated by using chemical stability tests and electrochemical MEA characterisation. F6PBI was used as the PBI-containing base excess polymer which was blended with either partially fluorinated aromatic polyether (sFS001), poly(2,6-dimethylbromide-1,4-phenylene oxide (PPOBr) or poly(tetrafluorostyrene-4-phosphonic acid) (PWN) in various ratios. Some of the blend membranes also contained a cross-linking agent which was specifically added in an attempt to reduce swelling and promote cross-linking within the polymer matrix. The chemical stability of the blended membranes was confirmed by using weight and swelling changes, TGA-FTIR and TGA-MS. All membranes tested showed low to no chemical degradation when exposed to 80 wt% H2SO4 at 80°C for 120 h. Once the MEA doping procedure had been optimised, electrochemical characterisation of the PBI MEAs, including polarisation curves, voltage stepping and long term operation (> 24 h) was used to evaluate the MEAs. Although performance degradation was observed for the PBI membranes during voltage stepping, it was shown that this characterisation technique could be applied with relative ease, producing valuable insights into MEA stability. Since it is expected that the SO2 electrolyser will be operated under static conditions (cell temperature, pressure and current density) in an industrial setting (HyS cycle or for SO2 removal), a long term study was included. Operating the SO2 electrolyser under constant current density of 0.1 A cm-2 confirmed that PBI-based polyaromatic membranes were suitable, if not preferred, for the SO2 environment, showing stable performance for 170 hours. This work evaluated the performance of commercial materials while further adding insights into both characterisation techniques for chemical stability of polymer materials and electrochemical methods for MEA evaluation to current published literature. In addition to the characterisation techniques this study also provides ample support for the use of PBI-based materials in the SO2 electrolyser. / PhD (Chemistry), North-West University, Potchefstroom Campus, 2015

In recent years, membrane gas absorption technology has been considered as one of the promising alternatives to conventional techniques for CO2 capture due to its favorable mass transfer performance. As a hybrid approach of chemical absorption and membrane separation, it exhibits a number of advantages, such as operational flexibility, compact structure, high surface-area-to-volume ratio, linear scale up, modularity and predictable performance. One of the main challenges of membrane gas absorption technology is the membrane wetting by absorbent over prolonged operating time, which may significantly decrease the mass transfer coefficients of the membrane module. In this thesis, the experimental was set up to investigate the dependency of CO2 removal efficiency and mass transfer rate on various operating parameters, such as the gas and liquid flow rates, absorbent type and concentration and volume fraction CO2 at the feed gas inlet. In addition, the simultaneous removal of SO2 and CO2 was investigated to evaluate the feasibility of simultaneous desulphurization and decarbonization in the same membrane contactor. During 14 days of continuous operation, it was observed that the CO2 mass transfer rate decreased significantly following the operating time, which was attributed to partial membrane wetting. To better understand the wetting mechanism of membrane pores during their prolonged contact with absorbents, immersion experiments for up to 90 days were carried out. Various membrane characterization methods were used to illustrate the wetting process before and after the membrane fibers were exposed to the absorbents. The characterization results showed that the absorbent molecules diffused into the polypropylene polymer during the contact with the membrane, resulting in the swelling of the membrane. In addition, the effects of operating parameters such as immersion time and absorbent type on the membrane wetting were investigated in detail. Finally, based on the analysis results, methods to smooth the membrane wetting were discussed. It was suggested that improving the hydrophobicity of polypropylene membrane by surface modification may be an effective way to improve the long-term operating performance of membrane contactors. Therefore, the polypropylene hollow fibers were modified by depositing a thin superhydrophobic coating on the membrane surface to improve their hydrophobicity. The mixture of cyclohexanone and methylethyl ketone was considered as the best non-solvent to achieve the fiber surface with good homogeneity and acceptably high hydrophobicity. In the long-period operation, the modified membrane contactor exhibited more stable and efficient performance than the untreated one. Hence, surface treatment provides a feasibility of improving the system stability for CO2 capture from the view of long-term operation. / En av de tekniker som under senare framhållits som ett lovande alternativ till konventionell CO2-avskiljning är membran-gas-absorptionstekniken på grund av god prestanda vad gäller masstransport. Det blandade angreppssättet med både kemisk absorption och membranseparation har en rad fördelar, såsom driftflexibilitet, kompakt konstruktion, högt yt-volymsförhållande, linjär uppskalning, modularitet och förutsägbar prestanda. En av de viktigaste utmaningarna för membran-gas-absorptionstekniken är vätningen av membranet med absorbenten under långa drifttider, vilket väsentligt kan minska membranmodulens masstransportkoefficienter.  I avhandlingen har en rad olika driftparametrars påverkan på CO2-reningsgraden och massöverföringshastigheten undersökts. Driftparametrar inkluderar gas- och vätskeflöden, typ av absorbent och koncentration och volymfraktion av CO2 vid gasinloppet. Avskiljning av SO2 och CO2 har dessutom undersökts för att utvärdera möjligheten att samtidigt, i samma membranenhet, avlägsna svavel och kol. Under 14 dagars kontinuerlig drift konstaterades det att massöverföringshastigheten för CO2 minskade avsevärt med drifttiden, vilket hänfördes till partiell vätning av membranet.   För att bättre förstå mekanismerna för vätning av membranporer under långvarig kontakt med absorbenter genomfördes doppningsexperiment i upp till 90 dagar. Olika metoder för karakterisering av membran användes för att illustrera vätningsprocessen före och efter det att membranfibrerna exponerades för absorbenterna. Resultaten av karakteriseringen visade att absorbentmolekylerna spreds in i polypropenpolymeren under kontakten med membranet, vilket ledde till att membranet svällde. Dessutom undersöktes effekterna av driftsparametrar såsom nedsänkningstid och typ av absorbent i detalj. Slutligen, på grundval av analysresultaten, diskuterades metoder för att underlätta vätningen av membran. Att förbättra polypropylenmembranets hydrofobicitet genom modifiering av ytan föreslogs kunna vara ett effektivt sätt att förbättra den långsiktiga driftprestandan för membranenheter. Därför modifierades de ihåliga fibrerna av polyproylen med ett tunt lager av en superhydrofob beläggning på membranets yta för att förbättra hydrofobiciteten. En blandning av cyklohexanon och metyletylketon ansågs vara det bästa icke-lösningsmedlet för att få en fiber yta med god homogenitet och acceptabelt hög hydrofobicitet. Under lång driftperiod, uppvisade den modifierade membranenheten stabilare och effektivare prestanda än den obehandlade. Därför erbjuder ytbehandling en möjlighet till att förbättra systemets stabilitet för CO2-avskiljning när det gäller långsiktig drift. / VR-SIDA Swedish Research Links Programme

No presente trabalho foram investigados vários sistemas moleculares contendo o dióxido de enxofre (SO2) como espécie elétron aceptora e diversas espécies elétron doadoras como aminas (alifáticas e aromáticas), complexos inorgânicos e líquidos iônicos. Estes compostos são chamados de complexos do tipo doador-aceptor, que no caso do SO2 são caracterizados por apresentarem baixas energias de ligação entre as espécies se comparada à maioria dos complexos desta categoria. A caracterização vibracional dos complexos e adutos de SO2, assim como do processo de transferência de carga (CT) intermolecular e da estabilidade destes sistemas consistem nos principais objetivos deste trabalho, tendo sido para tanto utilizadas as técnicas de espectroscopia eletrônica (UV-Vis), espectroscopia vibracional (Raman e infravermelho), cálculos de química quântica (DFT) e cálculos de dinâmica molecular clássica (MD). No caso de complexos entre aminas e SO2 foi observado que além da basicidade das aminas, o efeito estérico consiste em um fator crucial para a estabilidade. No caso de aminas aromáticas, complexos coloridos foram formados permitindo a obtenção de espectros Raman ressonante. No caso de um complexo inorgânico, com utilidade potencial como sensor de SO2foi observada a aplicação da espectroscopia Raman ressonante na caracterização do complexo de estequiometria 2:1. Já no caso da interação de SO2 e líquidos iônicos (LI) foi observada a capacidade de absorção de SO2 por LI e a conseqüente mudança das propriedades físico-químicas destes líquidos, o que abre a possibilidade, além de sua potencial utilização no contexto ambiental, de sintonizar propriedades de líquidos iônicos através da adição controlada de SO2. / In the present work molecular systems bearing the sulfur dioxide (SO2) as an electron acceptor species and several electron donor species as amines (aliphatic and aromatic), inorganic complexes and ionic liquids were investigated. Such complexes are commonly known as donor-acceptor complexes, and in particular, in the case of SO2 complexes are characterized by low binding energies when compared with the majority of charge transfer (CT) complexes. The vibrational characterization of the SO2 complexes, as well as of the intermolecular charge transfer (CT) process and of their stabilities are the main subjects of this work, and for such, electronic spectroscopy (UV-Vis), vibrational spectroscopy (Raman and infrared), quantum chemical (DFT) calculations and molecular dynamics (MD) simulations were used. In the case of complexes formed by amines and SO2 it was observed that besides the amine basicities, the steric effect plays a crucial role in their stabilities. In the case of aromatic amines, colored complexes were formed allowing the resonance Raman study. The use of Raman spectroscopy in the characterization of an inorganic complex (SO2 sensor) indicates the potential use of the resonance Raman effect for SO2 monitoring. In the case of the interaction between SO2 and ionic liquids it was observed the great capability of ionic liquids as SO2 absorbers, and the consequent change in the physical-chemical properties of these liquids, what opens the possibility, in addition to its potential use in the environmental context, for tuning the ionic liquids properties via the controlled addition of SO2.

No presente trabalho foram investigados vários sistemas moleculares contendo o dióxido de enxofre (SO2) como espécie elétron aceptora e diversas espécies elétron doadoras como aminas (alifáticas e aromáticas), complexos inorgânicos e líquidos iônicos. Estes compostos são chamados de complexos do tipo doador-aceptor, que no caso do SO2 são caracterizados por apresentarem baixas energias de ligação entre as espécies se comparada à maioria dos complexos desta categoria. A caracterização vibracional dos complexos e adutos de SO2, assim como do processo de transferência de carga (CT) intermolecular e da estabilidade destes sistemas consistem nos principais objetivos deste trabalho, tendo sido para tanto utilizadas as técnicas de espectroscopia eletrônica (UV-Vis), espectroscopia vibracional (Raman e infravermelho), cálculos de química quântica (DFT) e cálculos de dinâmica molecular clássica (MD). No caso de complexos entre aminas e SO2 foi observado que além da basicidade das aminas, o efeito estérico consiste em um fator crucial para a estabilidade. No caso de aminas aromáticas, complexos coloridos foram formados permitindo a obtenção de espectros Raman ressonante. No caso de um complexo inorgânico, com utilidade potencial como sensor de SO2foi observada a aplicação da espectroscopia Raman ressonante na caracterização do complexo de estequiometria 2:1. Já no caso da interação de SO2 e líquidos iônicos (LI) foi observada a capacidade de absorção de SO2 por LI e a conseqüente mudança das propriedades físico-químicas destes líquidos, o que abre a possibilidade, além de sua potencial utilização no contexto ambiental, de sintonizar propriedades de líquidos iônicos através da adição controlada de SO2. / In the present work molecular systems bearing the sulfur dioxide (SO2) as an electron acceptor species and several electron donor species as amines (aliphatic and aromatic), inorganic complexes and ionic liquids were investigated. Such complexes are commonly known as donor-acceptor complexes, and in particular, in the case of SO2 complexes are characterized by low binding energies when compared with the majority of charge transfer (CT) complexes. The vibrational characterization of the SO2 complexes, as well as of the intermolecular charge transfer (CT) process and of their stabilities are the main subjects of this work, and for such, electronic spectroscopy (UV-Vis), vibrational spectroscopy (Raman and infrared), quantum chemical (DFT) calculations and molecular dynamics (MD) simulations were used. In the case of complexes formed by amines and SO2 it was observed that besides the amine basicities, the steric effect plays a crucial role in their stabilities. In the case of aromatic amines, colored complexes were formed allowing the resonance Raman study. The use of Raman spectroscopy in the characterization of an inorganic complex (SO2 sensor) indicates the potential use of the resonance Raman effect for SO2 monitoring. In the case of the interaction between SO2 and ionic liquids it was observed the great capability of ionic liquids as SO2 absorbers, and the consequent change in the physical-chemical properties of these liquids, what opens the possibility, in addition to its potential use in the environmental context, for tuning the ionic liquids properties via the controlled addition of SO2.

Les nouvelles pratiques utilisées pour l’élaboration du vin amènent à une recrudescence des altérations microbiennes. C’est pourquoi, de nouvelles méthodes doivent être développées afin de quantifier ces microorganismes de façon précise, rapide et avec de faibles coûts. Les principales altérations du vin sont dues aux bactéries acétiques (BA) (A. aceti, A. pasteurianus, G. oxydans et Ga. liquefaciens) et à Brettanomyces bruxellensis. Par l’action d’enzymes, les 1ères transforment l’éthanol en acide acétique alors que B. bruxellensis transforme les acides hydroxycinnamiques en éthyles phénols (EP) (molécules odorantes désagréables). La cytométrie en flux couplée à la technique d’hybridation in situ en fluorescence a tout d’abord été étudiée. Aucun résultat reproductible n’a été développé pour les BA en vin rouge alors que pour B. bruxellensis, le protocole existant a été amélioré avec une quantification possible en 18 h. La PCR en temps réel a également été utilisées afin de quantifier ces microorganismes. Un protocole a été développé pour la quantification des BA en vin rouge (103 cellules/mL) avec l’utilisation d’un témoin interne microbiologique permettant de valider le rendement de l’extraction de l’ADN. Pour B. bruxellensis, trois kits commerciaux ont été analysés lors d’une étude interlaboratoires. Les quantifications se sont révélées significativement différentes des énumérations sur boite de Pétri avec une quantification des cellules mortes. De plus, il a été étudié et validé l’effet population de B. bruxellensis sur l’efficacité du SO2. Il ressort également de ces expérimentations que les cellules en état viable mais non cultivable ne produisent pas d’EP. / New practices used to elaborate wine lead to an increase of wine spoilage due to microorganisms. That is why, new technics have to be developed to quantify these microorganisms accurately, quickly and with low costs. The main wine spoilages are due to acetic acid bacteria (AAB) (A. aceti, A. pasteurianus, G. oxydans and Ga. liquefaciens) and Brettanomyces bruxellensis development. AAB transforms ethanol to acetic acid while B. bruxellensis transforms hydroxycinnamic acids to ethyl phenols (EP) (unpleasant odor molecules). In order to detect these wine spoilage microrganisms, flow cytometry coupled to fluorescent in situ hybridization has been assessed. No reproducible results have been developed for AAB in red wine while for B. bruxellensis, the existing protocol has been improved with a possible quantification after 18 h compared to 48-72 h in the previous protocol. The real-time PCR was also used to quantify these microorganisms. A protocol has been developed for the AAB quantification in red wine (103 cells/mL) with the use of a microbiological internal control to validate the DNA yield after extraction. For B. bruxellensis, three commercial kits were analyzed in an interlaboratory study. Quantifications were significantly different to the enumerations by Petri dish, with dead cell quantifications. Moreover, we demonstrated that the effectiveness of sulfite is dependent of the B. bruxellensis population. It also appears from these experiments that cells in viable but not culturable state do not produce EP.

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