Understanding the influence of media geometry on the degradation of acrylonitrile: Experimental and CFD analysis

International audienc

Oxydation photocatalytique de composés organiques volatils (application au traitement de l'air intérieur)

Un travail de recherche expérimentale concernant la destruction de composés organiques volatils par oxydation photocatalytique est réalisé dans le but de purifier les atmosphères intérieures. La première partie porte sur le choix de matériaux photocatalytiques adaptés, parmi des matériaux synthétisés au laboratoire et des produits d'origine industrielle. Quatre photocatalyseurs sont conservés, constitués de TiO2 déposé sur différents supports. La deuxième partie est dédiée à l'étude cinétique de la dégradation de la butanone en présence des quatre catalyseurs. L'influence de différents paramètres expérimentaux et des caractéristiques propres aux matériaux est mise en évidence. L'identification des intermédiaires de réaction permet de proposer un schéma réactionnel. Un mécanisme puis une loi de vitesse en sont déduits Des expérimentations conduites avec d'autres polluants à faible concentration permettent de conclure que l'oxydation photocatalytique est adaptée au traitement de l'air intérieur.NANTES-BU Sciences (441092104) / SudocNANTES-Ecole Centrale (441092306) / SudocNANTES-ENS Mines (441092314) / SudocSudocFranceF

Influence of operating parameters on the single-pass photocatalytic removal efficiency of acrylonitrile

International audiencePhotocatalytic oxidation (PCO) is an advanced air cleaning technology that is used as a means to improve air quality in indoor environments and could also potentially be used in hospital operating rooms (ORs). However, when it comes to the feasibility of using PCO to remove VOCs, most studies have been on those that are commonly found in indoor environments like homes and schools. There are little or no studies on other indoor environments like hospitals. Therefore in this work, acrylonitrile, one of the hazardous compounds found in surgical smoke (a source of pollution in the OR) was chosen as a representative compound to evaluate the performance of a photocatalytic system in an OR. The experiments were performed in a 420-L multi-pass laboratory reactor. The performance of the system was based on the influence that three operating parameters (air velocity, light intensity and initial concentration) would have on the single-pass removal efficiency (SPRE). A mathematical model was used to enable the calculation of the SPRE from the experimental degradation profile. The influence of the operating parameters on the degradation of acrylonitrile as well as the possible inter-mediates formed and mineralization rates are discussed

Influence of operating parameters on the single-pass photocatalytic removal efficiency of acrylonitrile

International audiencePhotocatalytic oxidation (PCO) is an advanced air cleaning technology that is used as a means to improve air quality in indoor environments and could also potentially be used in hospital operating rooms (ORs). However, when it comes to the feasibility of using PCO to remove VOCs, most studies have been on those that are commonly found in indoor environments like homes and schools. There are little or no studies on other indoor environments like hospitals. Therefore in this work, acrylonitrile, one of the hazardous compounds found in surgical smoke (a source of pollution in the OR) was chosen as a representative compound to evaluate the performance of a photocatalytic system in an OR. The experiments were performed in a 420-L multi-pass laboratory reactor. The performance of the system was based on the influence that three operating parameters (air velocity, light intensity and initial concentration) would have on the single-pass removal efficiency (SPRE). A mathematical model was used to enable the calculation of the SPRE from the experimental degradation profile. The influence of the operating parameters on the degradation of acrylonitrile as well as the possible inter-mediates formed and mineralization rates are discussed

Photocatalytic oxidation of isoflurane, an anesthetic gas: The influence of operating parameters

International audienc

Influence des paramètres opératoires sur la dégradation photocatalytique d'un gaz anesthésiant : l'isoflurane

International audienc

Influence of environmental parameters on the photocatalytic oxidation efficiency of acrylonitrile and isoflurane; two operating room pollutants

International audienceIn hospitals, operating rooms (ORs) are very demanding in terms of the indoor air quality (IAQ) and require systems that minimize the concentrations of pollutants (microorganisms, chemical and particulate matter). Air treatment devices that use photocatalytic oxidation (PCO) could potentially be used in the OR to improve IAQ. In this work, the fate of two OR pollutants acrylonitrile (chemical found in surgical smoke) and isoflurane (an-esthetic gas) when they go through a PCO device was investigated. The experiments were conducted in a laboratory closed loop multi-pass reactor. A mathematical model was utilized to enable the calculation of one indicator (single-pass removal efficiency) for acrylonitrile and two indicators (induction period and single-pass removal efficiency) for isoflurane. The degradation efficiency was then accessed by studying the influence of environmental parameters on these indicators. The parameters that were studied are the relative humidity, presence of co-pollutants and presence of particles. The parameters were observed to have similar effects on the degradation of both compounds. Increasing relative humidity inhibited the degradation probably due to competitive adsorption. The presence of co-pollutants like nitrous oxide and acetic acid caused a possible competition for adsorption unto active sites thus decreased the degradation efficiency of acrylonitrile and isoflurane. The increase in the concentration of the co-pollutants enhances the competitive effect and further decreases the degradation efficiency of the target pollutants. Finally the presence of particles on the photocatalytic media could block active sites thereby inhibiting the degradation of acrylonitrile and isoflurane

TiO2-Based Materials for Toluene Photocalytic Oxidation: Water Vapor Influence

International audienc

Stand-alone purification unit for indoor air quality improvement: Evaluation of photocatalytic commercial devices

International audienc

Controls of sedimentary supply and gravity driven deformation on the eastern Niger delta (Plio-Pleistocene) from the shoreline to the deep sea plain

International audienceWe studied the evolution of the gravity flow sedimentary within a large shelf-edge delta (Eastern Niger delta) over the last 2,5Myr taking into account the influence of the contemporaneous gravity driven deformation and sedimentary supply. To do this, we mapped (i) the shoreline geometry and (ii) the associated turbiditic systems for 9 intervals using a classification based on three morphological end-members: erosive, constructive and depositional modes. We characterized the depositional profile of the passive margin delta from the littoral domain to the abyssal plain and its spatial and temporal variability. We showed that, at the scale of the delta, the depositional profile varied from (i) a shelf edge delta profile with a slope break at the location of the shoreline during progradation to (ii) a ramp profile characteristic of a mid-shelf delta during retrogradation. Thus, during a stratigraphic cycle, the delta front evolved from a prograding slope break during the development of the HST, to steepening clinoforms during the development of the LST that progressively flattened out during the TST to reach a ramp profile at the MFS. The turbiditic systems (including MTC) initiate near the shoreline, at the toe of the delta front. Also, they form preferentially down slope synthetic faults or within antithetic fault relays. They are initially erosive, becoming constructive further down slope and eventually depositional. They may become erosive again as they cut through the compressional structures. We showed that the stratigraphic state (progradation/retrogradation) controls the amount of sediment reaching the platform and strongly impacts the density of gravity flow sedimentary systems (low density during progradation and high density during progradation). On the other hand, the gravity driven deformation controls the slope of the sea-floor and, in doing so, their morphology (erosive/constructive/depositional). Within this framework, lateral migrations of the delta impact both the spatial distribution of gravity driven deformation and gravity flow sedimentary systems. We think these results may be extrapolated to many shelf-edge deltas affected by gravity-driven deformation. Also, these results provide us with a tool to predict the spatial distribution of the domains in erosion/transit/sedimentation of the gravity flow sedimentary systems as well as their expected lithologies