Thesis defense of Florent Blancho

Identification, production and characterization of environmental nanoplastics using geochemical and nanometrology tools

Abstract

The use of plastics has been accompanied by a massive release of plastic waste into the environment. Their alteration by photo-oxidation produces nanoplastics (NPs), whose characteristics and properties make them potentially important metal vectors. Being difficult to sample in the environment, their study has been carried out with models not representative of environmental NPs. It is therefore essential to produce more relevant NPs models in order to better understand their behavior and impact on metal pollutants.

Py-GCMS allows the identification of polypropylene nanoparticles in the presence of organic matter as in environmental matrices. The mechanical abrasion of the weathering layers of photo-oxidized plastics in the environment allowed us to produce a more representative model.

These NPs models present on their surface functions complexing metals and controlling their colloidal stability. The use of rare earths and thermodynamic modeling, allowed us to demonstrate that the metal adsorption of metals is controlled by the formation of mono- or bidentate complexes with the surface carboxylic sites. The formation of mono- or bidentate complexes depends on the valence of the metals studied and the physicochemical conditions of the medium. More globally, the reactivity of NPs depends on their oxidation state which controls their surface site density. Due to their sorption properties, NPs can be key players in the dynamics of metals in areas polluted by plastics such as: agricultural soils amended with plastic waste and landfills.

Key-words: Nanoplastics, identification, characterization, metal-NPs interactions, modeling

In video-conference using the following link https://univ-rennes1-fr.zoom.us/j/93767994077 (meeting ID : 937 6799 4077 ; Password : 857241)