Evaluation technique des analyseurs de mesure de la qualité de l'air

Les objectifs des évaluations techniques des analyseurs de mesure de la qualité de l'air sont : de vérifier les performances métrologiques de ces analyseurs, de connaître la capacité des appareils à travailler sur le terrain, d'évaluer la capacité du fournisseur à résoudre les problèmes techniques que pose l'exploitation de son appareil. Cette activité existe à l'INERIS depuis plus de 20 ans (ex CERCHAR et ex IRCHA). Elle s'appuie sur une procédure décrite dans la norme française NF X 20-300 révisée en 199

Sampling and analysis of PAH and oxygenated PAH in diesel exhaust and ambient air

Polycyclic Aromatic Hydrocarbons (PAH) and their oxygenated derivatives occur in particles or in the vapour phase in the atmosphere. Some of these compounds, particularly the PAH, are known as strong carcinogens and/or mutagens. Emissions from diesel engines are an important source of these contaminants in urban air. In this work, the chemical composition of diesel particles was studied from two different perspectives: the gaz/particule partitioning and the different size fractions of these compounds. A dilution tunnel, with a diesel car connected, was built for the purpose of this study. Measurements were carried out near a motorway in Paris for comparison to the tunnel test results. The results show, firstly, that the gaseous phase of the PAH is predominant (up to 20 times) with respect to the particulate phase, and that the PAH and their derivatives are mainly adsorbed in the very fine particulate fraction (for particle size under 0.4 urn). Secondly, the oxygenated PAH, neglected in the majority of previous studies, are predominant with respect to the PAH

Experimental underground facility to evaluate remote sensing instruments

International audienceSince the end of eighties optical remote sensing instruments have been used by French air quality monitoring networks. This type of instrument offers new perspectives to characterise the atmospheric pollution. Indeed, it is possible to measure simultaneously several pollutants like S02, NO, N02, Oa, hydrocarbons, and specific pollutants such äs NH3, naphtalene,..

Some experiences of atmospheric PAH monitoring in France

International audienceOver recent years INERIS has carried out PAH measurements in ambient air. The aim of these studies is to propose methods which could be used by air quality monitoring networks in order to meet future regulations. INERIS used high volume samplers to collect PAH in particulate phase and in gaseous phase, and analysed 17 compounds. During field campaigns in urban sites, INERIS worked in close relation with LHVP, which has an experience in the low volume samplers

Sampling and analysis of organic compounds in diesel particulate matter

International audienceThe fraction of atmospheric semi-volatile organic compounds (SVOC) is partitioned between the gaseous and particulate phases. Certain of these compounds eg. polynuclear aromatic hydrocarbons (PAH) and their derivatives have been shown to exhibit mutagenic or carcinogenic properties. Emissions from diesel engines are an important source of these contaminants. In a dilution chamber, we studied a diesel engine emissions. It is shown firstly, that the gaseous fraction is predominant (by up to 20 times) with respect to the particulate phase. Secondly, the polar compounds, neglected in the majority of previous studies, are the predominant species. A test campaign was carried out in Paris-Porte d'Auteuil which yielded similar results to the laboratory experiment

Implementation of open-path measurement techniques

International audienceFor a long time INERIS has carried out metrological tests on automatic devices used in air quality monitoring networks. In France the standard text NF X 20-300 drives the evaluations in terms of the following metrological features : response time, linearity, limits, drift, ... In order to apply this text, the instruments have been fed with reference mixtures of gases in several reproducible concentrations. Compliance with this requirement is quite easy to obtain, in the case of conventional techniques, but the problems remain with optical remote sensing instruments. Indeed, it is impossible to manufacture a measurement cell as long as the optical path (greater than 100 meters). This difficulty can be solved by using the Beer-Lambert law indicating that the product of the concentration by the distance is a constant value

Sugar-responsive Pickering emulsions mediated by switching hydrophobicity in microgels

International audienceHypothesis: Pickering emulsions stabilized by soft and responsive microgels can demulsify on demandupon microgel collapse. The concept has been explored with simple model microgels such as poly(Nisopropylacrylamide)(pNIPAM) and their derivatives, but the role of functionalization is largely unexplored.Experiments: Saccharide-responsive phenylboronic-modified microgels are used as Pickering emulsionstabilizers. Emulsion stability and microgel organization at drop surface are studied as a function of saccharideconcentration. Better insight into their behavior at interfaces is gained through adsorption kineticsand Langmuir film studies at air-water interface.Findings: The functionalization of water-swollen microgels by phenylboronic functions imparts somehydrophobicity to the structure, at the origin of additional internal cross-links analogous which rigidifythe structure compared to non-functionalized microgels, as proved by their slow adsorption kinetics andpoor interfacial compressibility. Upon boronate ester formation with diol groups of the saccharide, thehydrophobic character of the phenylboronic acid decreases, increasing the adsorption kinetics and theirinterfacial compressibility. Emulsions are stable in the presence of saccharide, given the high deformabilityof the yet-hydrophilic microgels, and mechanically unstable with less deformable particles in lo

Interfacial rheology of model water-air microgels laden interfaces: effect of cross-linking

International audienceHypothesis The mechanical properties of model air/water interfaces covered by poly(Nisopropylacrylamide) microgels depend on the microgels deformability or in other words on the amount of cross-linker added during synthesis.Experiments The study is carried out by measuring the apparent dilational, the compression and the shear moduli using three complementary methods: 1) the pendant drop method with perturbative areas, 2) the Langmuir trough compression, and 3) shear rheology using a double wall ring cell mounted onto a Langmuir through.Findings In the range of surface coverages studied, the interfaces exhibit a solid-like behavior and elasticity goes through a maximum as a function of the surface pressure. This is observable whatever the investigation method. This maximum elasticity depends on the microgel deformability: the softer the microgels the higher the value of the moduli. The mechanical behavior of model interfaces is discussed, taking into account the core-shell structure of the particles and their packing at the interface