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Micromixing has a decisive action on the yield of fast reactions such as combustions, polymerizations, neutralizations and precipitations. The aim of this study was to test the possible effect of ultrasound on micromixing, through the phenomenon of acoustic cavitation. To evaluate the local state of micromixing, we used a system of parallel competing reactions involving the Dushman reaction between iodide and iodate, coupled with a neutralization. At first, we studied the effects of the acoustic frequency on micromixing (20-540-1000 kHz). It was found that micromixing through acoustic cavitation and acoustic streaming was more important at 20 kHz than at 540 kHz or 1 MHz. At high and low frequency, it was shown that the injection must be located near the ultrasonic emitter. The influence of the acoustic intensity proved to be predominant mostly for low intensities; for an acoustic intensity of 10 W cm(-2), a characteristic micromixing time of about 0.015 s has been obtained. Viscous media have been studied and experiments showed that micromixing is more difficult to achieve than in aqueous media, but that ultrasound may be as effective as classic stirring.

Using periodic density functional theory combined with advanced dispersion correction schemes, the adsorption of NO, NO 2 , CO, H 2 O and CO 2 has been investigated for various cation-exchanged faujasite zeolites. In the context of preventing harmful releases from diesel engines in confined environment, our aim was to find a suitable material able to selectively trap NO, NO 2 and CO toward H 2 O and CO 2 which are also present in the exhaust gas and could inhibit adsorption of targeted species. In order to identify the most promising adsorbent materials, we have undertaken a full screening of monovalent cations which can be incorporated into the zeolite and find that Cu + presents the best adsorption selectivity, followed by Ag + . However, the analysis of the bonds stretching upon adsorption revealed that Cu + , differently from Ag + , activates the N-O bonds in NO and NO 2 , which might lead to undesirable by-products during the adsorption process.

Hydrocarbon pyrolysis in low-pressure gas carburizing conditions leads to gas phase reactions, which produce polycyclic aromatic hydrocarbons (PAHs), some of which, such as benzo[a]pyrene, are carcinogenic. Workers can be exposed to these PAHs during maintenance and cleaning operations of carburizing furnaces. The aim of the study is the prediction of the formation of sixteen PAHs considered as priority pollutants by the Environmental Protection Agency in the United States (US EPA). A model has been implemented in order to describe the reaction pathways leading to their formation. It was validated using experimental data from the literature, obtained during pyrolysis of different hydrocarbons such as acetylene and ethylene. Flux analyses were realized in order to determine main reaction pathways leading to benzene depending on the reactant. Simulations were also performed to compare PAH formation between acetylene, ethylene and propane pyrolysis.

Three chlorinated VOCs of industrial significance were investigated in the low concentration domain (dichloromethane (DCM), tetrachlorethylene (TCE), and chlorobenzene (CB)), and using three solvents (di(2-ethylhexyl) phthalate (DEHP), di(2-ethylhexyl) adipate (DEHA), and tetraethylene glycol dimethyl ether (TEGDME)). The affinity of solvents toward a chlorinated VOC was studied by determining the Henry's law constant (infinite dilution activity coefficient) in the temperature range 30-70°C. Three techniques were used for this purpose: headspace gas chromatography (HSGC), indirect, i.e., varying volume, headspace gas chromatography (IHSGC), and inert gas stripping (GS). The accuracies of the techniques were assessed and compared to one another. Generally, agreement between the three methods is good. The comparison was extended to literature data. The Henry's law constant measured with HSGC method were correlated as a function of temperature with an equation similar to the van't Hoff equation. For DCM, TEGDME appears as the most suitable solvent, with limiting activity coefficient near 0.20 at 30°C. DEHA has the greatest affinity toward TCE and CB, with activity coefficients at 0.69 for TCE and 0.57 for CB.

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