OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 9735 We report the role played by acidic surface sites of ZSM-5 on ozone removal. Ozone removal is mainly due to ozone decomposition on mild/strong Lewis acid sites. Adsorbed oxygen species appear on ZSM-5 surface because of ozone decomposition. Keywords:Acidic sites Chemical surface properties Lewis acid sites Ozone Synthetic zeolites ZSM-5 zeolite a b s t r a c t In this work, chemical interactions between ozone and zeolite surface active sites are studied in order to propose a process for gaseous ozone removal. Synthetic ZSM-5 zeolites with three different Si/Al 2 ratios and similar specific surface areas and microporous volumes were used in this study. Zeolite samples were characterised using Fourier Transform InfraRed spectroscopy (FTIR) and pyridine sorption IR studies in order to determine acidic site concentrations and strength. Ozone removal experiments were conducted in a quartz fixed-bed flow reactor, at 20°C and 101 kPa. Experiments using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) were conducted in order to identify adsorbed ozone and/or adsorbed oxygen species on zeolite surface. Pyridine IR measurements evidence two kinds of Lewis acid sites induced by extra-framework aluminium species and electronic aluminium defaults inside zeolite structure. Results obtained here evidence the important role of acidic surface sites of ZSM-5 zeolite on gaseous ozone removal. The total amount of removed ozone is found to be directly proportional to the total content of Lewis acid sites. DRIFTS experiments exhibit two bands around 800 and 1400 cm À1 that could correspond to adsorbed oxygen species linked to zeolite surface. DRIFTS experiments also exhibit a band around 1100 cm À1 that correspond to adsorbed ozone on the zeolite surface. Gaseous ozone removal using ZSM-5 zeolite could be largely attributed to ozone decomposition on Lewis acid sites and also to ozone adsorption on the surface of the zeolites.

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Exopolysaccharides (EPS) from cell-free Porphyridium cruentum media were concentrated then purified (diafiltration) on a 0.14 µm ceramic membrane. The influence of cross-flow velocities on filtration performances was investigated. Mean permeate fluxes equal to 49.8, 68.9 and 81.9 L.h-1. m-2 were obtained during the concentration at 4 bar for respectively cross-flow velocities inside the membrane lumen equal to 2.5, 3.3 and 4.2 m.s-1; 49.7 L.h-1. m-2 for the diafiltration at 3.3 m.s-1. Permeate fluxes were correctly predicted from polysaccharide concentrations (10 % deviation). Volume reduction factors higher than 7.8 were reached. Rejection rates of polysaccharides and proteins varied according to the cross-flow velocities. Thus, the EPS recovery rate or time of filtration could be modulated following the cross-flow velocity. Polysaccharides were concentrated 6.3 to 10.4 times in such a way that the final sugars concentration reached 1.74 to 2.26 g.L-1. Rheological behavior of filtered solutions changed following the concentration progress. More than 80 % (w/w) of polysaccharides were recovered while 49 % and 99 % of proteins and salts were removed respectively. The filtrations allowed reaching a final monosaccharide content of dry matter equal to 48.9 % against 0.6 % (w/w) initially.2 Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. Graphical abstractHighlights ► Simple and rapid micro-alga's exopolysaccharide (EPS) concentration and purification ► High yields of EPS recovery and good permeate fluxes ► Change of rheological behaviour and composition of filtered solutions during filtration ► Time and degree of concentration change following the cross-flow velocity ► Advanced characterization of extracts

A hybrid process combining adsorption and ozonation was examined as an alternative treatment for odorous volatile organic compounds (VOCs). Methyl ethyl ketone (MEK) was chosen to study the influence of operating parameters. Two synthetic aluminosilicates (faujasite-Y and ZSM-5) were tested for adsorption and reactivity with ozone. The adsorption equilibrium measurement on both adsorbents showed that adsorption performance depends on temperature but is not sensitive to relative humidity, due to the hydrophobic properties of the materials. Adsorbed VOCs were oxidized at low temperature when ozonated flow was sent to the reactor. Regeneration of the fixed bed was achieved at the same time, releasing mainly CO(2) and H(2)O. Intermediates of oxidation, such as 2,3-butanedione and acetic acid, were identified, leading to incomplete mineralization. The influence of concentration and humidity are discussed. Four successive cycles were tested: after the first adsorption/ozonation cycle, the adsorption efficiency was not affected during subsequent cycles. These results show that the same sample of adsorbent can be used in the treatment process for a long time. Ozonation regeneration is a promising process for VOC removal.

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For several decades, it has been known that ozone emissions are harmful to humans, plants, and animals. Heterogeneous catalytic decomposition is an efficient process for removing ozone from air. This study examines the effect of the zeolite's framework and pore width on efficiency for decomposing gaseous ozone. Four highly hydrophobic zeolites are used: a large cavity zeolite (Faujasite/H-FAU), a medium pore zeolite with parallel channel (Mordenite/H-MOR), and two medium pore zeolites with interconnected channels (H-ZSM-5/H-MFI and Na-ZSM-5/Na-MFI). Experiments were conducted in fixed-bed flow reactors loaded with zeolite at ambient conditions (20 8C and 101 kPa). Zeolite surfaces were analyzed during the experiments in order to understand the influence of physical and chemical surface properties on the ozone decomposition mechanism. A higher amount of ozone is eliminated using H-MOR, compared with the zeolite samples H-FAU, H-MFI, and Na-MFI. Pore width and micropore framework size distribution (channel and cages) appear to be key factors. A narrow channel or cage, slightly larger than the ozone molecule size, seems to promote ozone interactions with Lewis acid sites. Fourier transform infrared spectroscopy shows that Lewis acid sites (LAS), located on the walls of zeolite pores, decompose ozone. This leads to the formation of atomic oxygen species that could react with another ozone molecule to form dioxygen. Hence, LAS are regenerated, ready to decompose another ozone molecule once more.