This thesis aims to clarify the sources of, and mechanisms associated with, the generation of ozone maxima over the southern African region. Inasmuch as, tropospheric ozone concentration is a function of both chemistry and meteorology, this thesis concentrates on the role of atmospheric dynamics. Firstly, a statistical analysis of the relationship between total ozone and meteorological parameters revealed a generally weak negative relationship between total ozone and the height of the 500, 300 and 100 hPa geopotential surfaces. The relationship is best expressed by the passage of a mid-latitude cyclone while anticyclonic conditions exhibited a weak relationship. An examination of the spatial distribution of total ozone and potential vorticity (PV), during the passage of westerly troughs, prompted a more thorough investigation of the exchange of ozone between the stratosphere and troposphere. The relationship between tropospheric ozone, and low pressure and anticyclonic systems is investigated further using data obtained during the South African Fire-Atmospheric Research Initiative (SAFARI) conducted in 1992. Ozone concentrations, as expressed by ozonesonde data, reveal different characteristic profiles for the two scenarios. Explanations for the differences observed are sought in the observed circulation patterns during the experiment. Case studies at Okaukuejo (Namibia), Irene (South Africa) and Brazzaville (Congo), which were utilised as ground stations during SAFARI, are presented in an attempt to gain insight into the vertical distribution of ozone over the entire expanse of the study region. The role of convective systems in the generation of short-lived upper tropospheric ozone maxima at tropical latitudes is illustrated while the different vertical ozone signatures, expressed under cyclonic and anticyclonic systems as described earlier, are reconfirmed by the Okaukuejo and Irene data. An attempt is made to investigate dynamic links between the troposphere and stratosphere and the concomitant exchange of ozone during the passage of westerly trough systems. Particularly deep troughs or cut off low pressure systems are identified as important mechanisms in the generation of upper tropospheric ozone maxima. An examination of the vertical distribution of ozone at Irene during the passage of a COL, using data obtained from the SA'ARI 1994 experiment, suggests concurrence with Danielsen's (1968) model of tropopause folding. The intrusion of high PV and dry stratospheric air, coupled with downward flow near the tropopause, in the vicinity of the upper tropospheric disturbance, promotes the transport of ozone-rich air to tropospheric altitudes. The limited availability of data has severely hampered the understanding of tropospheric ozo~e in southern Africa in the past. This study demonstrates the value of daily vertical ozone data, even for very short periods. / Thesis (Ph.D.)-University of Natal, 1995.

Thesis (Ph. D.)--University of Arizona, 1992. / Includes bibliographical references (leaves 224-241).

Cette thèse a pour objet de contribuer au développement du procédé de dépollution des eaux usées industrielles par ozonation catalytique hétérogène mettant en oeuvre un catalyseur poudre breveté, déposé sur des mousses de différents matériaux. Pour cela, une molécule modèle réfractaire, l'acide succinique a été ozonée en présence de catalyseur dans un réacteur lors d'expériences au cours desquelles plusieurs paramètres d'importance pour l'efficacité du procédé ont été modifiés (localisation du catalyseur, configuration du réacteur, introduction d'ozone...).Dans un premier temps la cinétique réactionnelle a été déterminée en faisant varier les concentrations initiales en acide succinique et en catalyseur.Par la suite, l'influence de la localisation du catalyseur supporté au sein du système réactionnel et du mode d'introduction de l'ozone gaz a été étudiée.La variation du temps de séjour de la solution par variation d'une part du débit d'entrée et d'autre part du volume de solution dans le système a permis (i) la confirmation de la loi cinétique et (ii) la détermination d'un volume limite à partir duquel l'efficacité de la réaction est affectée.Les résultats obtenus ont aboutis à la proposition d'un mécanisme d'ozonation catalytique hétérogène en plusieurs étapes et à la définition de paramètres de dimensionnement en vue d'une application industrielle. / This study aims at developing an industrial wastewater treatment process based on heterogeneous catalytic ozonation implementing a patented powder catalyst stuck on stainless steel and ceramic foam. A refractory model compound, succinic acid, was chosen to be ozonated in the presence of the catalyst while different operating parameters were varied.Kinetic of the catalytic reaction was determined varying initial concentrations of succinic acid and catalyst.The influence of solid catalyst within the reaction system and of the way of introduction of ozone gas was also investigated.The variation of the solution Hydraulic Retention Time through (i) inlet flow rate variation and (ii) volume of solution in the reaction system variation, allowed the confirmation of the kinetic law and the determination of a threshold volume below which the reaction efficiency decreased.The results obtained allowed the proposition of heterogeneous catalytic ozonation mechanism comprising several steps and the definition of design parameters.

L'ion nitrate (NO3-) présent dans les neiges Antarctiques est issus de l'oxydation des oxydes d'azote (NOx = NO + NO2) dans l'atmosphère. Aux sites de faible accumulation de neige tels que Vostok et Dôme C sur le plateau de l'Est de l'Antarctique, le nitrate n'est pas piégé de manière ultime dans la neige, ce qui limite fortement l'interprétation des enregistrements en nitrate dans les carottes de glace. Des mesures récentes de la composition isotopique en azote du nitrate (δ15N) montrent des valeurs extrêmement élevées (+339‰) dans les premiers décimètres de la neige de Dôme C. Ces valeurs ont été attribuées à la photolyse du nitrate et au recyclage important qui en résulte. Le nitrate possède, par ailleurs, une anomalie isotopique en oxygène (Δ17O) qui permet de tracer l'activité de l'ozone (O3) au cours de sa formation. Ce travail de thèse présente le premier enregistrement de la composition isotopique complète du nitrate (δ15N, Δ17O et δ18O) dans une carotte de glace : la carotte de glace de Vostok dont les 64 échantillons analysés couvrent une période de 150 000 ans. Ce jeu de données a été complété par 313 échantillons collectés entre 2007 et 2010 dans le continuum atmosphère/givre/neige au Dôme C ainsi que dans 21 puits de neige prélevés dans une zone couvrant l'essentiel de l'Est de l'Antarctique. L'analyse isotopique de ces échantillons modernes a permis de contraindre le modèle conceptuel TRANSITS développé au cours de cette thèse et dont le but est de représenter le recyclage du nitrate à l'interface entre l'atmosphère et la neige ainsi que son impact sur la composition isotopique du nitrate archivé. Les valeurs positives et élevées du δ15N du nitrate piégé dans la carotte de glace de Vostok montrent que le recyclage du nitrate a toujours eu lieu sur le plateau Antarctique au cours de la période étudiée. Les variations du flux primaire de nitrate reçu au site de Vostok estimées à l'aide du modèle TRANSITS montrent, en périodes glaciaires, un flux primaire plus important qui pourrait être lié à une dénitrification stratosphérique plus conséquente. Les valeurs de Δ17O du nitrate montrent que l'incursion d'ozone d'origine stratosphérique dans la troposphère était plus fréquente en périodes glaciaires. Nous proposons enfin que les résultats acquis dans le cadre de cette thèse pourraient permettre de mieux contraindre le cycle de l'azote sur la côte Antarctique et d'apporter des éléments d'interprétation des enregistrements en nitrate dans les carottes de glace de sites de plus forte accumulation de neige (au Groenland par exemple). / Nitrate ions (NO3-) found in Antarctic snows stem from the degradation of nitrogen oxydes (NOx = NO + NO2) in the atmosphere. At sites with low snow accumulation rates such as Vostok or Dome C (East Antarctic plateau), nitrate deposition to the snow is not irreversible and this strongly hampers the interpretation of nitrate concentration records in ice cores. Nitrogen stable isotopic (δ15N) as high as +339‰ were measured in nitrate in the upper firn at Dome C and have been attributed to nitrate photolysis initiating a strong recycling at the snow surface. The oxygen isotopic anomaly (Δ17O) reflects the activity of ozone (O3) in nitrate formation. We present the first comprehensive isotopic analysis of nitrate (δ15N, Δ17O and δ18O) in a deep ice core. 64 samples of nitrate from the Vostok ice core have been analyzed and cover the last 150 000 years. This dataset has been completed with 313 samples recently collected in the atmosphere/surface hoar/snow continuum at Dome C as well as in several snowpits from various sites covering most of the East Antarctica. Those present-day samples are used to evaluate a conceptual model (named TRANSITS) developped during this PhD and which aims at representing nitrate recycling at the snow/atmosphere interface and at modelling its impact on the isotopic composition of the archived nitrate. High positive δ15N values measured in the Vostok ice core reveal that nitrate recycling has always occurred at the surface of the Antarctic plateau over this period. Past variations of the primary flux of nitrate to the Vostok site have been estimated using the TRANSITS model. They show that glacials are characterized by higher inputs which may be linked to a greater stratospheric denitrification. The Δ17O values indicate that intrusions of stratospheric air masses to the troposphere may have been more frequent in glacials thus incorporating significant amounts of stratospheric ozone to the lower atmosphere. Last, we suggest that this study may have some relevance to the coastal nitrogen budget in Antarctica and to the interpretation of ice cores retrieved from high accumulation sites (e.g. in Greenland).

Neste trabalho, foram desenvolvidos filmes finos de composição SrTi1-xFexO3 (0,00≤ x ≤0,150) nanoestruturados visando sua aplicação como sensor de gás ozônio. Os filmes finos foram depositados através da técnica de deposição por feixe de elétrons (EBD) cujo alvo utilizado foram pastilhas obtidas a partir do pó cristalino SrTi1-xFexO3 (0,00≤ x ≤0,150) sintetizadas através do método dos precursores poliméricos. Foi observado a partir das analises termogravimétrica e térmica diferencial que a incorporação de ferro no sistema diminui a temperatura de queima do pó precursor, sugerindo que o ferro atua como catalisador na cadeia polimérica. Os filmes depositados por DFE apresentam-se no estado amorfo sendo necessário um tratamento térmico ex-situ para que a fase cristalina desejada seja obtida. Todos os filmes apresentaram uma boa aderência aos diferentes tipos de substratos utilizados. Após o processo de cristalização, os filmes depositados sobre diferentes substratos foram caracterizados através das técnicas de difração de raios-X, espectroscopia UV-Vis e microscopia de força atômica (MFA). Foi observado que um aumento na temperatura de tratamento térmico dos filmes leva a um aumento no grau de cristalização e a uma diminuição no valor da energia de gap, calculada a partir dos espectros UV-VIS. A analise por MFA mostrou que a mudança do tipo de substrato utilizado não influencia as propriedades estruturais e microestruturais dos filmes. Através da realização de medidas de resistência elétrica, observou-se que os filmes cristalinos submetidos a um tratamento térmico ex-situ a 500oC por 4 horas apresentaram uma boa sensibilidade ao gás ozônio sendo possível detectar a presença de até 75 ppb de ozônio. / In this study, nanostructured thin films of SrTi1-xFexO3 (0.00 ≤ x ≤ 0.150) compositions were prepared looking their application as ozone gas sensor. The thin films were deposited using the technique of electron beam deposition (EBD) whose targets were obtained from polycrystalline SrTi1-xFexO3 (0.00 ≤ x ≤ 0.150) powders synthesized by the polymeric precursor method. It was observed from the thermogravimetric and differential thermal analysis that the incorporation of iron in the system decreases the calcination temperature of the precursor powders, suggesting that the iron acts as a catalyst in the polymer chain. The as obtained films deposited by EBD present an amorphous state being necessary a ex-situ heat treatment to obtain the desired crystalline phase. All films showed good adhesion to different substrates. After the crystallization process, the films deposited on different substrates were characterized through X-ray diffraction, UV-Vis spectroscopy and atomic force microscopy (AFM) trechniques. It was observed that an increase in the annealing temperature of the film results in an increase in the degree of crystallization and a decrease in the value of band gap energy, which was calculated from the UV-VIS spectra. The AFM analysis showed that changing the type of substrate does not influence the structural properties and microstructure of the films. By carrying out measurements of electrical resistance, it was observed that the crystalline films subjected to a ex-situ heat treatment at 500oC for 4 hours showed a good sensitivity to the ozone gas being possible to detect the presence of up to 75 ppb ozone.

O ozônio, forma triatômica do oxigênio, tem sido amplamente estudado ao longo dos anos. Sua aplicação destaca-se devido ao seu alto poder oxidativo na ação contra bactérias, fungos, protozoários e vírus. A alta instabilidade faz com que o gás transforme-se em oxigênio após determinado tempo, não liberando resíduos no ambiente. Também tem sua aplicação estudada de forma a aprimorar o sistema circulatório, produzindo aumento na oxigenação tecidual, estimulando a produção de antioxidantes endógenos e causando efeito imunomodulador (com a estimulação da liberação de citocinas). Foi o objetivo deste trabalho a organização das informações sobre o ozônio empregado na Medicina Veterinária e Odontologia Humana, principalmente suas aplicações como antimicrobiano, para esclarecer a importância de suas utilizações e fornecer subsídios para que a ozonioterapia possa ser utilizada na Odontologia Veterinária. Assim, com base na literatura, foi possível concluir que a ozonioterapia constitui proposta coadjuvante promissora diante da necessidade do controle da infecção, além da ação imunomoduladora que pode ser empregada nas mais variadas situações da prática clínica. / Ozone, the triatomic form of oxygen, has been widely studied over the years. With a very oxidative potential, acts against bacteria, fungi, protozoa and viruses. The high instability, after a few minutes makes it return to the oxygen form. This is important because of the non residual effect on the environment. The ozone has also an immune modulating effect, stimulating the release of endogenous anti-oxidants and acts in the circulation system inducing to an increase on oxygen tissue levels. This research aimed to gather information about ozone, particularly the antimicrobial effect, raising the importance of the applications, aiming a possible use of the ozone in Veterinary Dentistry. Therefore, it is possible to conclude that the ozone therapy can be an important adjuvant to infectious diseases control, and can be used in different types of clinical applications.

Chaque année en France, les semenciers sont contraints de déclasser plus de 10 000 tonnes de semences. Ces semences sont actuellement incinérées dans des cimenteries au frais des semenciers et non valorisables dans des procédés de valorisation des agro-ressources, compte tenu de leur teneur non négligeable en pesticides. Par conséquent, il apparaît nécessaire de réduire, dans un premier temps, la quantité de produits phytosanitaires présents dans les enrobages avant de pouvoir valoriser ces semences déclassées.L’objet de cette thèse consiste donc à développer un outil permettant de décomposer une grande partie des produits phytosanitaires présents sur les enrobages par ozonation. Dans un premier temps, une méthode d’extraction par liquide pressurisé a été développée pour la quantification des produits phytosanitaires présents sur les enrobages avant et après ozonation. Cette méthode d’extraction a été validée et a permis de déterminer, par la suite,l’efficacité du traitement d’ozonation sur les semences enrobées.Ensuite, afin d’évaluer l’efficacité d’un traitement à l’ozone, deux pesticides présents dans la solution d’enrobage Gaucho Blé® -l’imidaclopride et le bitertanol- ont été ozonés, en solution aqueuse dans un réacteur agité. Les deux produits ont été dégradés complètement en moins de 30 minutes et la loi cinétique de leurs réactions d’ozonation a montré que l’ordre partiel de la réaction a été de 1 pour l’ozone et pour le pesticide. Les produits de dégradation,formés au cours de l’ozonation, ont aussi été analysés par spectrométrie de masse ESI(+)-MSet la structure de la plupart des produits de dégradation a été déterminée. Un schéma des différentes voies de dégradation de l’imidaclopride et du bitertanol a pu être proposé.Enfin, l’ozonation des pesticides a été étudiée sur les semences de blé tendre enrobées avec la solution de Gaucho Blé® dans un réacteur à lit fixe. L’humidification des grains avant ozonation, la concentration en ozone dans le gaz et la durée de traitement ont semblé être les facteurs importants pour accélérer la cinétique de dégradation des pesticides dans les enrobages. Les pesticides ont été dégradés (respectivement 99 et 90 % de dégradation pour l’imidaclopride et le bitertanol). La loi cinétique de la réaction d’ozonation de l’imidaclopride et du bitertanol a présenté des ordres partiels égaux à 1 pour l’ozone et pour le pesticide. Ce procédé a ensuite été appliqué à d’autres types de semences enrobées et s’est avéré efficace sur tous les principes actifs étudiés. Enfin, les semences enrobées ont été ozonées dans un réacteur prototype (réacteur à plateau vibrant) dans lequel tous les pesticides étudiés ont été dégradés mais à des taux de dégradation plus faibles qu’en réacteur à lit fixe. / Every year in France, seed producers must downgrade more than 10,000 tons of seeds. These seeds are currently incinerated in cement factories at seed producers’ expenses and non available for the processes of valorization of renewable resources, due to their significant pesticide content. Consequently, in the first step, the quantity of pesticides present in the seed loading must be reduced before a subsequent valorization of the downgraded seeds. The purpose of this PhD work is thus to develop a process for the decomposition of a large amount of the pesticides present in the seed loading. First, an extraction procedure by pressurized liquid was developed for the quantitation of phytopharmaceuticals present on the loading before and after the ozonation. This extraction method was validated and enabled to determine, subsequently, the efficiency of the ozonation process on the loaded seeds. In the second time, in order to evaluate the efficiency of an ozonation treatment, both pesticides present in the Gaucho Blé® seed loading solution – imidacloprid and bitertanol – were ozonated, in aqueous solutions in a stirred reactor. Both compounds were completely decomposed in 30 minutes and the kinetic law for the ozonation of both compounds displayed a partial order of 1 for ozone and 1 for the pesticide. Degradation products, formed during the ozonation, were analyzed by mass spectrometry ESI(+)-MS and the structure of most of the compounds was characterized. Degradation pathways for imidacloprid and bitertanol were thus proposed. Finally, the ozonation of pesticides were applied to soft wheat seeds loaded with Gaucho Blé® loading solution, in a fixed bed reactor. The humidification of seeds before ozonation, the concentration of ozone in the inlet gas and the ozonation time were the predominant factors to accelerate the kinetic of degradation of pesticides in the seed loadings. The pesticides were successfully decomposed (respectively 99 and 90 % for the degradation of imidacloprid and bitertanol). The kinetic laws for the ozonation reactions of imidacloprid and bitertanol were determined and the partial orders of the reaction were 1 for both ozone and the pesticide. This process was then applied to the treatment of other loaded seeds and showed good degradation rates for all the studied pesticides. Subsequently, the loaded seeds were ozonated in a prototype reactor equipped with a dynamic plate in which all the pesticides were decomposed but with lower degradation rates than in a fixed bed reactor.

This study presents various methods of measuring ozone and consolidates current state of knowledge in the field of disposable printed ozone dosimeters. The paper also identifies prospective dyes for preparation of ozone dosimeters available on the market. Information gathered from literature review was used to prepare dosimeters based on two different dyes. These were calibrated for screen printing technology and their sensitivity to ozone was optimized to achieve visual detectability. Prepared samples were observed and studied while being exposed to ozone. Then, long term mechanical and chemical properties of these were tested in order to identify appropriate conditions for storage.

The diploma thesis deals with the cleaning of car air conditioning system with ozone. The aim is to design equipment for ozone production, its location and cleaning algorithm. The thesis is divided into two parts. The introductory theoretical part describes the principle of operation of conventional automotive air conditioning, then discusses the methods of pollution and solutions to remove these pollutions. The theoretical part ends with a summary of information on ozone. The practical part is continuously followed by the design of device for the ozone production directly in the car. The final part deals with the location of such a device in a car, measuring its parameters and evaluating the results.

This master's thesis deals with the study of the reactions of the ozone and oxygen with various construction materials. Ozone as an unstable gas tends to decompose spontaneously and this process can be accelerated by reaction with other substances. The aim of this work is to determine the course of ozone's formation and its depletion in after the contact with various substances. Ozone is widely used mainly due to its disinfecting effects. Therefore, the monitoring of these reactions is beneficial for the choosing of ozonizer's material or its accessories. The theoretical part of this work describes the important properties of the ozone, the possibilities of using this gas, various methods of its generation, the influence of gas admixtures and a temperature on its generation and decomposition, the methods of determining the concentration and surface reaction. The dependence of ozone's formation on the size of the reaction space was monitored for either the silicone and Teflon material in the experimental part of the thesis. The length of the hoses was 20-50 cm and the diameter of the inner space was 6 mm for Teflon and 7,99 mm for a silicone. Furthermore, other experiments were performed for the silicone material, where the formation of the ozone was monitored while the oxygen and argon were being used as working gases. The formation and the depletion of the ozone depending on the changes of reaction time were investigated in the third series of experiments. We worked with a ceramic material with two different inner diameters and also with a brass and a stainless steel material in this experiment. The materials were constructed as the tubes of the same length of 54 cm. The ozone generated from the oxygen was enclosed into the reaction tube and the depletion was monitored. The last experiment was focused on the monitoring of the course of ozone's formation in a quartz cuvette influenced by the reaction time and the composition of the working gas. The amount of generated ozone was determined by absorption spectrometry in the all studied cases. The ozone flowing through the system was adsorbed by the surface of the material during the discharge. A mixture of gases (the adsorbed ozone, the oxygen and the argon in various ratios) was present in the sealed reaction space. The Ozone was formed on the surface of the material. The adsorbed ozone decomposed into a molecular and an atomic oxygen. The atomic oxygen reacted with the oxygen molecule occurring in the reaction space. The reaction time leading to the biggest obtained concentration of generated ozone was determined by the experimental data. For most of the materials, the reaction time was about 6 minutes.