Indoor air pollution : measurement, health impact and photochemical methods treatment.

L’accroissement de la population humaine, l’agriculture intensive et le développement industriel créent une pollution de l’air qui aujourd’hui devient préoccupante pour notre santé et notre environnement. Si la qualité de l’air extérieur fait l’objet depuis plusieurs décennies de règlementations qui permettent aujourd’hui de constater une diminution globale de la pollution dans les grandes agglomérations européennes, la pollution de l’air intérieur a quant à elle été longtemps sous-estimée. En effet, avec le développement de matériaux composites pour la construction et l’ameublement, la gamme de polluants de l’air intérieur s’est très largement agrandie et les concentrations ont globalement augmenté. Plusieurs études ont ainsi montré que de nombreux composés organiques volatils étaient détectés dans l’air intérieur à des concentrations bien plus élevées qu’à l’extérieur. D’autre part, la modification des modes de vie sédentaires et citadines ont pour conséquence une augmentation du temps passé dans des espaces confinés comme les logements, les lieux de travail et les transports en commun. Le simple renouvellement de l’air intérieur par de l’air extérieur devenant de moins en moins satisfaisant dans les grandes agglomérations, de nouvelles méthodes de traitement sont actuellement développées pour diminuer les concentrations de ces polluants tout en limitant la consommation d’énergie. La photocatalyse, en tant que procédé d’oxydation avancé fait partie des technologies intéressantes pour minéraliser des composés organiques volatils (COV). Après un rapide rappel du contexte sociétal de la pollution atmosphérique, les conditions de mesures et les méthodes possibles pour le traitement de cette pollution sont présentées. Le chapitre suivant regroupe les résultats sur le développement de matériaux photocatalytiques innovants et la mesure de leur efficacité. La première partie de ce chapitre fait le bilan des réacteurs photocatalytiques adaptés à l’étude de réactions à l’interface solide-gaz et résume les nombreuses difficultés liées à l’évaluation des performances de divers matériaux dans des conditions le plus souvent difficilement comparables. Dans la seconde partie, un premier matériau composite constitué de film polymère et de dioxyde de titane a été caractérisé par sa capacité à oxyder un composé volatil, le diméthyle disulfure, utilisé en agriculture pour la fumigation. Le développement d’un second matériau photocatalytique original, constitué de fibres de TiO2 pur a, quant à lui, été caractérisé par sa capacité à minéraliser des COV représentatifs de la pollution de l’air intérieur (acétone, heptane, toluène). Les deux dernières parties de ce chapitre se situent à l’interface entre la photochimie et la biologie. Dans un premier temps, la capacité d’inactivation bactérienne d’un textile « intelligent » sur lequel sont fixées des particules de dioxyde de titane couplées à un photosensibilisateur a été étudiée et l’efficacité sous rayonnement visible de ce tissu original a été analysée. L’impact de la pollution de l’air intérieur sur des cellules de la peau fait l’objet de la dernière partie de ce chapitre. Pour cela un montage permettant d’exposer des cellules de kératinocytes en culture, mais également des biopsies de peau humaine, à des concentrations contrôlées en COV a été mis au point. Nous avons ainsi pu mettre en évidence une réponse cellulaire à ce stress environnemental et préciser l’origine de ce stress. Enfin ce travail se termine par une ouverture sur des projets de recherche actuellement en cours ayant pour objet la mesure des espèces réactives de l’oxygène impliquées dans les réactions photochimiques et le développement de nouveau matériaux hybrides polymère/photosensibilisateurs. Des idées de projets à l’interface de la photochimie et de la biologie ouvrent de nouvelles perspectives à la suite de ces premiers résultats.The increase of human population, the modern agriculture and industrial development generate air pollution, which is nowadays worrying for health and environment. Since several decades, outdoor air pollution has been regulated giving rise a global decrease of pollution in the most important European cities. However indoor air pollution was neglected for a long time. Indeed with development of composite materials for building and furnishing, the number of air pollutants strongly increased together with their concentrations. Several studies have thus demonstrated that numerous volatile organic compounds (VOC) were detected indoor at much higher concentration than outdoor. Moreover, due to the modification of sedentary and urban lifestyles, the time spent in confined spaces like housing, working places and public transportation increases. It is less and less satisfactory to simply renew indoor air with outdoor air in most of urban agglomerations. Accordingly, new processes for air treatment are developed in order to decrease indoor air pollutant concentrations while limiting energetic consumption. Photocatalysis is an advanced oxidation process potentially interesting for VOC removal. After a short reminder on the societal context of atmospheric pollution, measurement and treatment methods are presented in chapters I and II. The following chapter gathers the results obtained on the development of new photocatalytic materials and on the measure of their efficiency. The first part of this chapter is devoted to an overview of photocatalytic reactors for gas solid reactions and summarizes the numerous problems arising from the comparison of different materials under various conditions, which are not always similar. In the second part, a composite material made of titanium dioxide encapsulated in a polymer film is characterized and used for the oxidation of a volatile compound used for agricultural fumigation, dimethyl disulfide. The spectroscopic analysis led to the optimization of the material as a function of its thickness and its titanium dioxide loading. A second innovative photocatalytic material made of pure TiO2 fibers is characterized by its mineralization ability of representative indoor air VOC (acetone, heptane, and toluene). The performance of this material is compared to that of a commercial one, Quartzel ® made of TiO2 deposited on quartz fibers, under strictly identical conditions. The two last parts of this chapter are at the interface between photochemistry and biology. In a first strep, bacterial inactivation by a smart textile where titanium dioxide particles coupled with a photosensitizer is studded under visible light. In the last part, the impact of indoor air pollution on skin cells is presented. A dedicated device allowing keratinocytes culture cells and skin biopsies exposures to controlled VOC concentrations is developed. It is thus possible to evidence and to determine the origin of the cellular response to this environmental stress. At last, new research projects for a near future are then presented. They concern the determination of reactive oxygen species involved in photochemical reactions and the development of new hybrid polymers encapsulating photosensitizing molecules. Prospective ideas at the interface of photochemistry and biology conclude this memory

Couplage photocatalyse-oxydation par le ferrate (VI) pour le traitement du colorant rhodamine 6G

Un facteur limitant de l’oxydation photocatalytique du dioxyde de titane (TiO2) sous irradiation UV est la recombinaison des électrons de la bande de conduction (e-cb) avec les trous d’électron (h+vb) à la surface de TiO2. Le couplage du ferrate(VI), Fe(VI), connu comme un oxydant respectueux de l’environnement, avec la photocatalyse UV/TiO2 pourrait conduire à une synergie oxydative de par le piégeage de e-cb par Fe(VI) et la consécutive formation de l’espèce hautement réactive Fe(V). Cette étude décrit les résultats du couplage TiO2 commercial P25 avec Fe(VI) sous forme pure ou sous forme d’une matière synthétisée dans notre laboratoire (produit solide nommé Fe(VI) matter) pour l’abattement du colorant rhodamine 6G (R6G). Les cinétiques de transformation de R6G ([R6G]0 = 10‑5 M; pH = 8,00 ± 0,05), en présence de TiO2 ([P25] = 0,1 g∙L‑1) illuminé sous UV et/ou de Fe(VI) ([Fe(VI)]0 = 10‑4 M) sont suivies par spectrophotométrie. Une synergie est mise en évidence lors du traitement de R6G par UV/TiO2/Fe(VI) pur, conduisant à une accélération de la transformation de R6G et à une minéralisation plus importante. Cependant, cet abattement n’est pas atteint lors du couplage UV/TiO2/Fe(VI) matter. Une étude de l’impact de sels inorganiques présents dans Fe(VI) matter sur l’activité photocatalytique est présentée. Le sulfate, SO42‑, et le Fe(OH)3 en particulier mènent à une forte inhibition de l’activité de TiO2. Le suivi de la production des radicaux hydroxyles (OH•) montre une inhibition physique de leur production due à la formation d’une couche de sels inorganiques à la surface de TiO2 et au piégeage de radicaux OH• dans la solution.A limiting factor in photocatalytic oxidation using UV irradiation of titanium dioxide (TiO2) is the recombination of conduction band electrons (e-cb) with electron holes (h+vb) on TiO2 surface. Coupling ferrate(VI), Fe(VI), known as an “environmentally friendly” oxidant, with UV/TiO2 photocatalysis may involve an oxidation synergism arising from the Fe(VI) scavenging of e-cb and the corresponding beneficial formation of highly reactive Fe(V). This study describes the results of coupling P25 TiO2 and Fe(VI) (pure or Fe(VI) matter synthesized in our laboratory) to remove the dye rhodamine 6G (R6G). Abatement kinetics for R6G, ([R6G]0 = 10‑5 M; pH = 8.00 ± 0.05), in presence of TiO2 ([P25] = 0.1 g∙L‑1) illuminated under an UV source and/or Fe(VI) ([Fe(VI)]0 = 10‑4 M) were followed by spectrophotometry. A synergism was highlighted during the treatment of R6G by UV/TiO2/pure Fe(VI), leading to a faster abatement and a better mineralization. However, this abatement was not reached when coupling Fe(VI) matter with UV/TiO2. A study of the impact of the inorganic salts present in the Fe(VI) matter on the oxidative activities is presented. Sulfate, SO42‑, and Fe(OH)3 in particular lead to a high inhibition of TiO2 activity. The monitoring of hydroxyl radical (OH•) production highlighted a physical inhibition of the formation of OH•, probably due to the formation of an inorganic salt layer at the surface of TiO2 and also to the scavenging of OH• in the bulk solution

Photocatalytic TiO2 Macroscopic Fibers Obtained Through Integrative Chemistry

The photocatalytic properties of titanium dioxide depend not only on its electronic properties, but also on the material size and shape, which can increase interactions between the reactants and catalyst. Most studies to date show that reducing the particle size down to the nanoscale increases photocatalytic efficiency, as a result of a higher surface to volume ratio and because a larger proportion of the material is actually irradiated by light. We demonstrate that a multiscale shape design, which integrates surface roughness, particle shape, and 1D material processing and orientation, can favor photocatalytic properties in the solidgas regime, especially mineralization (conversion into CO2), when the hierarchical 1D orientation of the material is combined with unidirectional gas flow. Several materials with hierarchical structure were prepared and characterized. They have been tested for the photocatalytic mineralization of gaseous acetone and compared with commercial catalysts. Our study reveals that a suitable combination of multiscale design and optimization of the material orientation and gas flow favors high mineralization

Exploring the effects of dietary inulin in rainbow trout fed a high-starch, 100% plant-based diet

Abstract Background High dietary carbohydrates can spare protein in rainbow trout (Oncorhynchus mykiss) but may affect growth and health. Inulin, a prebiotic, could have nutritional and metabolic effects, along with anti-inflammatory properties in teleosts, improving growth and welfare. We tested this hypothesis in rainbow trout by feeding them a 100% plant-based diet, which is a viable alternative to fishmeal and fish oil in aquaculture feeds. In a two-factor design, we examined the impact of inulin (2%) as well as the variation in the carbohydrates (CHO)/plant protein ratio on rainbow trout. We assessed the influence of these factors on zootechnical parameters, plasma metabolites, gut microbiota, production of short-chain fatty acids and lactic acid, as well as the expression of free-fatty acid receptor genes in the mid-intestine, intermediary liver metabolism, and immune markers in a 12-week feeding trial. Results The use of 2% inulin did not significantly change the fish intestinal microbiota, but interestingly, the high CHO/protein ratio group showed a change in intestinal microbiota and in particular the beta diversity, with 21 bacterial genera affected, including Ralstonia, Bacillus, and 11 lactic-acid producing bacteria. There were higher levels of butyric, and valeric acid in groups fed with high CHO/protein diet but not with inulin. The high CHO/protein group showed a decrease in the expression of pro-inflammatory cytokines (il1b, il8, and tnfa) in liver and a lower expression of the genes coding for tight-junction proteins in mid-intestine (tjp1a and tjp3). However, the 2% inulin did not modify the expression of plasma immune markers. Finally, inulin induced a negative effect on rainbow trout growth performance irrespective of the dietary carbohydrates. Conclusions With a 100% plant-based diet, inclusion of high levels of carbohydrates could be a promising way for fish nutrition in aquaculture through a protein sparing effect whereas the supplementation of 2% inulin does not appear to improve the use of CHO when combined with a 100% plant-based diet

1D Organization of ZnO and TiO2 nanoparticles toward advanced photonic and photocatalytic materials

Nowadays Chemist are request to construct more and more complex architectures bearing multifunctionalities enable to respond to external stimuli. The construction of such complex architectures will be addressed through strong interplay in chemical science, as proposed recently with the concept of integrative Chemistry.[1] We synthesized PVA/ZnO-nanorods composite fibers using co-axial flux extrusion.[2] These fibers exhibit higher anisotropic photonic properties, both in absorption and emission, as a result of the collective alignment of the ZnO nanorods along the main axis of the PVA fiber. This photonic anisotropy is triggered by a synergistic interaction between the PVA matrix, stretched above Tg, and cooled down under strain. Compared with non-elongated fibers that present an isotropic emission, composite fibers previously submitted to a tensile stress absorb selectively UV emission when the polarized laser beam is parallel to the main axis of the fiber. In addition, their photolumincescence is also anisotropic, with a waveguide behavior along the main axis of the fiber. Mechanical properties of these composite fibers are also drastically improved, compared with pure PVA fibers: the longitudinal Young modulus of these fibers is increased from 2 to 6 GPa upon ZnO addition, a value similar to those already observed for composite fibers, prepared either with carbon nanotubes, or Vanadium Oxide macroscopic fibers. [1] N. Brun, S. Ungureanu, H. Deleuze and R. Backov. Chem. Soc. Rev., 2011, 40, 771 [2] Kinadjian, N., Achard, M.-F., Julián-López, B., Maugey, M., Poulin, P., Prouzet, E. and Backov, R. (2012). Adv. Funct. Mater.. doi: 10.1002/adfm.20120036

Effect of Plasma Activated Liquid (PAL) on bacteria viability.

<p>A: 1: control bacteria incubated for 2 hours in PBS and % of surviving cells was evaluated by the CFU method. 2: <i>E</i>. <i>coli</i> exposed to He plasma for 10 min with 2 hr storage at 4°C. 3: Bacteria exposed to PAL (PBS treated for 10 min He plasma) for 2 hr at 4°C. 4: Bacteria exposed to He plasma for 10 min and incubated for 2 hours with non-plasma treated PBS at 4°C. 5: Bacteria exposed to plasma for 10 min and then incubated for 2 hours at 4°C with PAL (PBS treated for 10 min He plasma). 6: Bacteria exposed to PAL (PBS treated for 10 min He plasma and left at room temperature for 2 hours) for 2 hours at 4°C. The values are means ± SEM of 3 separate experiments (*p<0.01 and ** p<0.05 vs control). B: Same experimental procedures using He-N₂ plasma. C: Same experimental procedures using He-O₂ plasma.</p

Effect of plasma exposure on bacterial morphology analyzed by SEM.

<p>A: Control (<i>E</i>. <i>coli</i>). Two pictures for each conditions are presented B: after 10 min He plasma treatment and 2 hour post-treatment storage at 4°C. C: after 10 min He-N₂ plasma treatment and 2 hour post-treatment storage. D: after 10 min He-O₂ plasma treatment and 2 hour post-treatment storage.</p

Detection of oxidatively modified proteins following plasma exposure.

<p>A: Bacteria exposed to plasma treatment (He, He-O₂ and He-N₂) for 10 min with 2 hours post-treatment storage. To detect oxidatively, modified protein bacterial extracts were treated with 2,4-dinitorphenylhydrazine to derivatize protein carbonyls and then evaluated by SDS-gel electrophoresis using 2,4-dinitrophenyl antibodies. B: Detection of 4-hydroxy-2-nonenal protein modification by ELISA. The values are means ± SEM of 3 separate experiments. C: Western blot analysis using nitrotyrosine specific antibodies. D: Bacterial extracts collected, lysed and detected by dot blot for lipid A content. Dot blot results were analyzed with a dot calibration curve and relative quantity of bacteria lipid A was estimated. The relative intensity of each spot was quantified (Image J).</p

Effect of plasma exposure on bacteria inactivation and viability.

<p>A: Survival curves obtained by CFU counting method for <i>E</i>. <i>coli</i> bacteria exposed to He plasma for different times (black diamond, control; white square, He gas only; black cross, 1 min He plasma treatment; white circle, 2 min 30 s; white triangle, 5 min and black circle, 10 min) and left for different post-treatment storage times 2, 3, 4, 5, 6 and 24 h in PBS at 4°C. B: Survival curves for <i>E</i>. <i>coli</i> exposed to He-N₂ plasma for different times (black diamond, control; white square, He only; black cross 1 min He-N₂ plasma treatment; white circle, 2 min 30 s; white triangle, 5 min and black circle, 10 min); and left for different post-treatment storage times. C: Survival curves for <i>E</i>. <i>coli</i> exposed to He-O₂ plasma for different times (black diamond, control; white square, He only; black cross, 1 min He-O₂ plasma treatment; white circle, 2 min 30 s; white triangle, 5 min and black circle, 10 min) and left for different post-treatment storage times. D: Survival curves obtained by MPN method for <i>E</i>. <i>coli</i> exposed to He plasma (white square) and He-O₂ plasma (white triangle) for 10 min and different post-treatment storage times (1 hr and 2 hr). Non-treated bacteria (black diamond). The values are means ± SEM of 3 separate experiments. E: Flow cytometry analysis of bacteria after 10 min plasma treatment (He, He-O₂ and He-N₂) and one hour post-treatment storage. Cells were initially gated on an FL2-A vs SSC-A plot (dashes). Simultaneous staining with thiazole orange (TO) and propidium iodide (PI) allowed the distinction between live (TO⁺PI⁻, red circle), dead (TO⁺PI⁺, black circle), and injured (TO⁺PI^int, dark grey) cell populations, revealing increased cell injury and death in the treated sample as expected. The TO⁻PI⁺ population was excluded from the analysis as debris.</p

Effect of Plasma Activated Liquid (PAL) on bacteria viability.

<p>A: 1: control bacteria incubated for 2 hours in PBS and % of surviving cells was evaluated by the CFU method. 2: <i>E</i>. <i>coli</i> exposed to He plasma for 10 min with 2 hr storage at 4°C. 3: Bacteria exposed to PAL (PBS treated for 10 min He plasma) for 2 hr at 4°C. 4: Bacteria exposed to He plasma for 10 min and incubated for 2 hours with non-plasma treated PBS at 4°C. 5: Bacteria exposed to plasma for 10 min and then incubated for 2 hours at 4°C with PAL (PBS treated for 10 min He plasma). 6: Bacteria exposed to PAL (PBS treated for 10 min He plasma and left at room temperature for 2 hours) for 2 hours at 4°C. The values are means ± SEM of 3 separate experiments (*p<0.01 and ** p<0.05 vs control). B: Same experimental procedures using He-N₂ plasma. C: Same experimental procedures using He-O₂ plasma.</p