Co-treatment of industrial air streams using A.O.P. and adsorption processes

Coupling adsorption with two different photochemical oxidation methods was investigated, in order to treat industrial gaseous effluents containing a low concentration of Volatile Organic Compounds (VOC). Prior to adsorption/photocatalysis cyclic study, new TiO2 based catalysts were prepared by impregnating commercial zeolites in pellets form using a sol-gel technique. Scanning Electronic Microscopy observations linked to BET and adsorption equilibrium measurements of two VOC (1-butanol or BuOH and methyl-ethyl-ketone or MEK) showed that TiO2 happened to. x on the inert binder, without significant modification of support properties. A specific diffusion cell was used to produce dilute polluted air streams for each VOC in dynamic experiments, in which adsorption and photodegradation phases were alternatively carried out. Adsorption/photocatalysis co-treatment unable the total degradation of BuOH, and the regeneration of adsorbent. When using V-UV photolysis, pure zeolites were used, irradiated at 172 nm with an xenon excimer lamp. Excellent results were observed, since a total and rapid degradation was obtained for both VOC, especially thanks to a determining role of ozone

Hyperalgésie et tolérance aigüe à la morphine après chirurgie sous fortes doses d'opioïdes (de l'animal à la pratique clinique chez l'homme)

Notre travail de thèse a concerné l'étude du processus de sensibilisation à la douleur et l'étude de stratégies thérapeutiques permettant de prévenir ou de bloquer chez l'animal comme chez l'homme le développement d'un tel processus. Par une approche comportementale réalisée chez le rat, nous avons montré que sur un modèle de douleur incisionnelle comme précédemment noté après inflammation, une substance opioide telle que le fentanyl amplifie les jours suivants son administration non seulement l'hyperalgésie induite par l'acte chirurgical, mais aggrave aussi la tolérance à la morphine en postopératoire. Le développement d'une hyperalgésie conduirait à un changement d'état qui serait lui aussi aggravé par l'administration de fortes doses d'analgésiques opioides durant l'acte opératoire. Ce changement d'état révélé par l'administration de naloxone dans nos expérimentations animales serait associé à une sensibilisation à la douleur. Par une approche électrophysiologique in vivo, nous avons aussi noté que les animaux opérés et comparés à des animaux témoins présentaient à distance de la chirurgie à J1, une réponse accrue à uns stimulation mécanique croissante des neurones WDR de la corne dorsale de la moelle dont le champ récepteur incluait la zone opérée. L'administration de fortes doses de fentanyl peropératoires entraînait une majoration importante de cette mécanosensibilité des neurones WDR. D'un point de vue thérapeutique, chez l'animal, nous avons testé l'administration à peropératoire d'agent anti-NMDA comme la kétamine, le protoxyde d'azote et le sévoflurane. Les deux premiers agents, kétamine et protoxyde d'azote, se sont révélés capables de réduire non seulement l'hyperalgésie postopératoire induite par les fortes doses de fentanyl utilisées en peropératoire, mais aussi la tolérance aigue à la morphine en postopératoire. Chez l'homme, en chirurgie digestive, notre étude révèle que l'administration per et postopératoire de kétamine pouvait aussi réduire non seulement l'intensité et l'extension de l'hyperalgésie péricicatricielle, mais aussi diminuait la consommation totale de morphine sur 48 heures postopératoires.The aim of this work was to study the pain sensitization processes and to evaluate therapeutic strategies to prevent or to treat such a process in rats as well as in humans. By using a behavioural approach in rats, we have demonstrated that, as previously reported with inflammatory pain, rats operated under high doses of fentanyl developed higher level of postoperative hyperalgesia ut also presented stronger morphine tolerance after surgery. The development of hyperalgesia could lead to a change in the animal's state that would be also enhanced by preoperative high doses of fentanyl. The change in the animal's state, noticed after taloxone injection, could be associated with latent pain sensitization. Electrophysiological data we gathered in vivo at D1 in rats reported that operated rats (on D0), as compared to sham ones, had WDR neurons in dorsal horn that showed a higher electrical response to mechanical stimulations of their receptor field including the surgical area. Perioperative high doses of fentanyl induced an enhancement of this late postoperative mechanosensitivity of the WDR neurons. From a therapeutic viewpoint, in animals, we tested peroperative administration of different anti-NMDA agents : ketamine, nitrous oxide and sevoflurane. Ketamine and nitrous oxide were able to reduce not only postoperative hyperalgesia induced by high doses of fentanyl, but also acute postoperative morphine tolerance. In humans, for abdominal surgery, our study reported that per and postoperative administration of ketamine permitted to reduce not only intensity and extension of hyperalgesia around the wound, but also morphine consumption for the 48 postoperative hours.Without analgesic effects per se, antihyperalgesic agents could oppose to the development of the pain sensitization improving thus the management of acute postoperative pain and decreasing the chronicisation of acute pain.BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Effet isotopique du soufre au cours de l’oxydation de l’anhydride sulfureux en milieu sulfurique et mécanisme de cette oxydation

Le but de cette étude est de chercher si les vapeurs nitreuses peuvent catalyser la réaction d’échange du soufre entre l’anhydride sulfureux et l’acide sulfurique en milieu sulfurique.Au cours de l’oxydation de l’anhydride la phase vapeur s’appauvrit en soufre lourd. Mais les expériences réalisées avec de l’acide sulfurique marqué H235SO4 montrent que le soufre n’échange pas avec une vitesse mesurable à température ordinaire. Le fractionnement isotopique observé ne peut donc être expliqué par une évolution vers l’équilibre thermodynamique. L’absence d’échange est interprétée à la lumière des mécanismes proposés pour l’oxydation catalytique de l’anhydride sulfureux

Heterogeneous photocatalysis of butanol and methyl ethyl ketone—characterization of catalyst and dynamic study

International audienceNew titanium dioxide (TiO2) based catalysts were prepared by impregnating commercial zeolites in pellets form using a sol–gel technique. Characterization was done with chemical analysis, X-Ray diffraction, scanning electron microscopy, and BET measurements, together with volatile organic compounds (VOC) adsorption equilibrium experiments. TiO2 happened to fix on the inert binder leading to a close intimacy of mixing with the zeolites crystallites, without significant modification of support properties. A diffusion cell was used to produce dilute polluted air streams for dynamic experiments, in which adsorption and photodegradation phases were alternatively carried out. Regeneration of adsorbent was evaluated regarding experimental conditions. Through a comparison with the results obtained on impregnated mesoporous borosilicate beads, it was clarified that zeolite supports had no effect on 1-butanol (BuOH) photooxidation mechanisms. Yet, evidence for mass transfer limitation was found, and attributed to intracrystalline diffusion in zeolites

Photooxidation of dimethylsulfide in the gas phase: A comparison between TiO2-silica and photosensitizer-silica based materials

International audienceThe photooxidation of dimethylsulfide (DMS) in the gas phase was studied with two different materials, under identical conditions. The first material (TiO2-QZ) is based on titanium dioxide (TiO2) deposited on quartz bars by the sol-gel method. The second one (DCA-SG) is based on the well known photosensitizer, 9,10-dicyanoanthracene (DCA) encapsulated in a sol-gel silica network. In spite of non-optimized conditions, both materials allow the oxidation of DMS in air under irradiation. However, the oxidation products are strikingly different: dimethyldisulfide is the main product detected in the gas phase with TiO2-QZ due to a too short residence time to achieve complete mineralization. With DCA-SG no gaseous product is detected in the treated gaseous flow for more than 100 h, due to the exclusive formation of polar dimethylsulfoxide and dimethylsulfone which are totally adsorbed on the highly polar silica gel. The efficiency of this latter reaction depends on the DMS concentration, gas flow and light intensity, but is not affected by the presence of small amounts of water. Singlet oxygen appears to be formed efficiently under these conditions. The saturation of DCA-SG by the oxidation products was demonstrated by several complementary methods, and some possible solutions to regenerate the material are proposed. The complementarities of both TiO2-QZ and DCA-SG could be used to achieve the oxidation of different classes of pollutants