Adsorption and reactivity of mineral dust toward selected VOCs present in the atmosphere

PhD student: Mohamad Nour ZEINEDDINE

Erosion of the Earth’s crust and volcanic activities can lead to significant and variable emissions of mineral dust in the atmosphere. These particles can act as efficient sorption or reactivity platforms for atmospheric trace gases. Several studies have suggested that the photocatalytic oxidation of adsorbed volatile organic compounds (VOC) may occur on the surface of mineral dust, although this phenomenon is still widely unknown and not taken into account in the chemistry-transport models.

During the PhD thesis, laboratory experiments will help in determining (i) if dust naturally present in the atmosphere can lead to long-distance transport of adsorbed VOCs; (ii) if heterogeneous processes can occur at the surface and modify the atmospheric lifetime of organic species; (iii) to what extent sorption and reactivity properties can be linked to the morphology or chemical composition of mineral dust.

First, the finest size fraction of natural samples of mineral dust (from desert or volcanic eruptions) will be characterized in terms of morphology, chemical composition, and specific area using various techniques. These samples will be then deposited into a reaction cell equipped with in situ DRIFTS and coupled to a SIFT-MS analyzer, in order to characterize the sorption properties of selected VOCs. A wall-coated flow tube reactor will be developed and used to determine the influence of the presence of mineral dust onto the atmospheric reactivity of these VOCs in different experimental conditions. 

Ecole Doctorale: SMRE

Supervisors: Frédéric THEVENET et Véronique RIFFAULT

Laboratory: Département Sciences de l’Atmosphère et Génie de l’Environnement (SAGE)

Financing: Region / Labex CaPPA