PhysicoChimie des Processus de Combustion et de l'Atmosphère

Vous êtes ici : Accueil > Thèses & Stages > Offres de masters2

Offres de stages master deuxième année

Master Chimie, Energie, Environnement
2017-2018
Laboratoire de Physicochimie des Processus de Combustion et de l'Atmosphère
PC2A - UMR CNRS 8522
Université des Sciences et Technologies de Lille
Cité scientifique, Bâtiment C11
59655 Villeneuve d'Ascq Cedex, France
fax : 03.20.43.69.77

lien vers le site du master chimie

Liste des offres

 

  • CHANGES ON POLLEN GRAINS INDUCED BY O3 AND NO2
    Présentation:

    Pollen grain has a brief airborne life ranging from hours to days during pollination period. Pollen grain is modified by gaseous and particulate pollution during its transport in the atmosphere.

    The modifications of pollen grains by atmospheric pollution induce an inhibition of the reproductive capabilities of the pollen (germination), an increase of the allergenic potential and facilitate the dispersion of allergens in the fine fraction of atmospheric aerosols.

    The aim of this research project is to gain more knowledge on the chemical actions of gaseous pollutants on the pollen grains. Several study in PC2A have already been conducted in this specific area of interest1–4 with various pollen grains (birch, timothy grass, pine and ragweed). Here we proposed a work on the action of NO2 and a combination of NO2/O3 on pollen in atmospheric conditions.

    The candidate will gain a strong training into the following laboratory equipment: aerosol flow tube, aerosol sizer (SMPS and APS), gas analyser, GC-MS and GC-FID.

     

    1.Chassard, G. et al. Kinetic of NO2 Uptake by Phleum Pratense Pollen: Chemical and Allergenic Implications. Environmental Pollution 196, 107–113 (2015).

    2.Naas, O. et al. Chemical modification of coating of Pinus halepensis pollen by ozone exposure. Environmental Pollution 214, 816–821 (2016).

    3.Sénéchal, H. et al. A Review of the Effects of Major Atmospheric Pollutants on Pollen Grains, Pollen Content and Allergenicity. The Scientific World Journal 2015, ID 940243 (2015).

    4.Visez, N. et al. Wind-Induced Mechanical Rupture of Birch Pollen: Potential Implications for Allergen Dispersal. Journal of Aerosol Science 89, 77–84 (2015).

    Linked to the workpackage of the Labex CaPPA : WP 2

    Keywords: Heterogeneous Chemistry, Analytical Chemistry, Experimental work

    Encadrant: Nicolas Visez
    Laboratoire: lab. PC2A
    Contact: nicolas.visez@univ-lille1.fr

  • Study of I2 interactions with inorganic aerosols using molecular modelling tools
    Présentation:

    Reactive halogen species play an important role in tropospheric chemistry, especially in the polar and marine boundary layers. They impact the oxidative capacity of the troposphere via catalytic destruction of ozone or altering NO/NO2 and OH/HO2 cycles. Although iodine species are a minor constituent of seawater, recent field studies have measured significant levels of organic and inorganic iodine in the marine boundary layer.

     

    In this context, the aim of this research project is to gain more knowledge on the heterogeneous processes of solid surfaces with gas-phase molecular iodine. Inorganic aerosols are very important in the marine boundary layer and several surfaces will be studied (NaCl, sulfate, nitrate). After an initial training at the lab, molecular simulations will be performed using the Vienna Ab initio Simulation Package (VASP).

     

    Keywords: aerosols, marine boundary layer, I2, molecular simulations.

    Linked to the workpackage of the Labex CaPPA : WP6

    Encadrant: Fayçal Allouti, Florent Louis
    Laboratoire: lab. PC2A
    Contact: Fayçal Allouti, Florent Louis

  • Study of the reactivity of CH3O2 radicals by laser photolyse coupled to Cavity Ring Down Spectroscopy CRDS
    Présentation:

    The hydroxyl radical, OH, and the hydroperoxyl radical, HO2, linked together under atmospheric conditions through a rapid pseudo-equilibrium, are responsible for a vast number of chemical reactions in the atmosphere. Peroxy radicals RO2, are reactive intermediates in the atmospheric oxidation of all hydrocarbons.

    This is why the accurate modelling of atmospheric chemistry relies strongly on the availability of reliable kinetic data for reactions involving these radicals.

    PC2A has developed an experimental set-up which enables to monitor simultaneously OH and HO2 / RO2 radicals in a time resolved manner. This enables to measure kinetics data of reactions of atmospheric interest involving these radicals. The set-up consists of a low-pressure cell, where radicals are generated by pulsed laser photolysis. Following the pulsed initiation of the reaction, the, time-resolved concentrations of OH and HO2 / RO2 are monitored by Laser Induced Fluorescence for OH (LIF) and by continuous wave cavity ring-down spectroscopy (cw-CRDS) for HO2 / RO2.

    In the frame of this placement, this experimental setup will be used to investigate the oxidation kinetics of species of atmospheric interest. We will determine the rate constants and product yields of a few key reactions involving CH3O2 radicals: this radical is formed during the atmospheric oxidation of CH4, an important green house gas, but also during the oxidation of many other hydrocarbons. However, very little is known on the reactivity of this radical and we plan to investigate the rate constants and the product yields of a few key reactions of this radical, for example (R1) CH3O2 + OH and (R2) CH3O2 + HO2. The reaction will be initiated by a pulsed photolysis of CH3I in the presence of O2, and the different reaction partners and possible products will then be measured by the two laser-based methods: OH and CH3O (possible product of R1) by LIF and CH3O2 and HO2 by cw-CRDS.

    Keywords: Atmospheric chemistry, peroxy radicals, spectroscopy, laser photolysis

    Linked to the workpackage of the Labex CaPPA : WP 1

     

    Encadrant: Christa Fittschen
    Laboratoire: PC2A
    Contact: Christa Fittschen 0320337266

  • Kinetic modeling of the combustion of biofuels
    Présentation:

    Description: To reduce fuel consumption, Greenhouse Gases, NOX and soot particles emissions, recent developments in engine technology have focused on operating engines at lower temperatures and fuel concentrations. These constraints have motivated the apparition of Exhaust Gas Recirculation (EGR) technology, and triggered interest in Low-Temperature Combustion (LTC) engines. In these conditions, combustion chemistry is more complex as it relies on the formation of peroxides. Chemical branching is degenerate and highly fuel-specific. To accommodate the use of modern fuels such as biodiesels or fuels produced from biomass, predictive models of this combustion chemistry must be constructed and validated.

     

    Recently, the interest has grown on the use of liquid fuels produced from lignocellulosic biomass. Among those, methylated tetrahydrofurans have numerous advantages in terms of ease of production and compatibility with existing fuels derived from fossil resources. An experimental study in engine-relevant conditions, will be performed at PC2A, to provide an understanding of the reaction pathways involved in its oxidation. To gain deeper insight into the chemical mechanism, and build a predictive tool of its combustion, a modeling study will be initiated. This work will help build a predictive model of the observed reactivity of this fuel.

     

    Keywords: Pollutant reduction, Low temperature combustion, engines, kinetic modeling.

    Encadrant: Guillaume VANHOVE
    Laboratoire: lab. PC2A
    Contact: Guillaume VANHOVE